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+config SELECT_MEMORY_MODEL
+	def_bool y
+	depends on ARCH_SELECT_MEMORY_MODEL
+
+choice
+	prompt "Memory model"
+	depends on SELECT_MEMORY_MODEL
+	default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
+	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
+	default FLATMEM_MANUAL
+
+config FLATMEM_MANUAL
+	bool "Flat Memory"
+	depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
+	help
+	  This option allows you to change some of the ways that
+	  Linux manages its memory internally.  Most users will
+	  only have one option here: FLATMEM.  This is normal
+	  and a correct option.
+
+	  Some users of more advanced features like NUMA and
+	  memory hotplug may have different options here.
+	  DISCONTIGMEM is a more mature, better tested system,
+	  but is incompatible with memory hotplug and may suffer
+	  decreased performance over SPARSEMEM.  If unsure between
+	  "Sparse Memory" and "Discontiguous Memory", choose
+	  "Discontiguous Memory".
+
+	  If unsure, choose this option (Flat Memory) over any other.
+
+config DISCONTIGMEM_MANUAL
+	bool "Discontiguous Memory"
+	depends on ARCH_DISCONTIGMEM_ENABLE
+	help
+	  This option provides enhanced support for discontiguous
+	  memory systems, over FLATMEM.  These systems have holes
+	  in their physical address spaces, and this option provides
+	  more efficient handling of these holes.  However, the vast
+	  majority of hardware has quite flat address spaces, and
+	  can have degraded performance from the extra overhead that
+	  this option imposes.
+
+	  Many NUMA configurations will have this as the only option.
+
+	  If unsure, choose "Flat Memory" over this option.
+
+config SPARSEMEM_MANUAL
+	bool "Sparse Memory"
+	depends on ARCH_SPARSEMEM_ENABLE
+	help
+	  This will be the only option for some systems, including
+	  memory hotplug systems.  This is normal.
+
+	  For many other systems, this will be an alternative to
+	  "Discontiguous Memory".  This option provides some potential
+	  performance benefits, along with decreased code complexity,
+	  but it is newer, and more experimental.
+
+	  If unsure, choose "Discontiguous Memory" or "Flat Memory"
+	  over this option.
+
+endchoice
+
+config DISCONTIGMEM
+	def_bool y
+	depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
+
+config SPARSEMEM
+	def_bool y
+	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
+
+config FLATMEM
+	def_bool y
+	depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
+
+config FLAT_NODE_MEM_MAP
+	def_bool y
+	depends on !SPARSEMEM
+
+#
+# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
+# to represent different areas of memory.  This variable allows
+# those dependencies to exist individually.
+#
+config NEED_MULTIPLE_NODES
+	def_bool y
+	depends on DISCONTIGMEM || NUMA
+
+config HAVE_MEMORY_PRESENT
+	def_bool y
+	depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
+
+#
+# SPARSEMEM_EXTREME (which is the default) does some bootmem
+# allocations when memory_present() is called.  If this cannot
+# be done on your architecture, select this option.  However,
+# statically allocating the mem_section[] array can potentially
+# consume vast quantities of .bss, so be careful.
+#
+# This option will also potentially produce smaller runtime code
+# with gcc 3.4 and later.
+#
+config SPARSEMEM_STATIC
+	bool
+
+#
+# Architecture platforms which require a two level mem_section in SPARSEMEM
+# must select this option. This is usually for architecture platforms with
+# an extremely sparse physical address space.
+#
+config SPARSEMEM_EXTREME
+	def_bool y
+	depends on SPARSEMEM && !SPARSEMEM_STATIC
+
+config SPARSEMEM_VMEMMAP_ENABLE
+	bool
+
+config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
+	def_bool y
+	depends on SPARSEMEM && X86_64
+
+config SPARSEMEM_VMEMMAP
+	bool "Sparse Memory virtual memmap"
+	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
+	default y
+	help
+	 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
+	 pfn_to_page and page_to_pfn operations.  This is the most
+	 efficient option when sufficient kernel resources are available.
+
+config HAVE_MEMBLOCK
+	bool
+
+config HAVE_MEMBLOCK_NODE_MAP
+	bool
+
+config HAVE_MEMBLOCK_PHYS_MAP
+	bool
+
+config HAVE_GENERIC_RCU_GUP
+	bool
+
+config ARCH_DISCARD_MEMBLOCK
+	bool
+
+config NO_BOOTMEM
+	bool
+
+config MEMORY_ISOLATION
+	bool
+
+config MOVABLE_NODE
+	bool "Enable to assign a node which has only movable memory"
+	depends on HAVE_MEMBLOCK
+	depends on NO_BOOTMEM
+	depends on X86_64
+	depends on NUMA
+	default n
+	help
+	  Allow a node to have only movable memory.  Pages used by the kernel,
+	  such as direct mapping pages cannot be migrated.  So the corresponding
+	  memory device cannot be hotplugged.  This option allows the following
+	  two things:
+	  - When the system is booting, node full of hotpluggable memory can
+	  be arranged to have only movable memory so that the whole node can
+	  be hot-removed. (need movable_node boot option specified).
+	  - After the system is up, the option allows users to online all the
+	  memory of a node as movable memory so that the whole node can be
+	  hot-removed.
+
+	  Users who don't use the memory hotplug feature are fine with this
+	  option on since they don't specify movable_node boot option or they
+	  don't online memory as movable.
+
+	  Say Y here if you want to hotplug a whole node.
+	  Say N here if you want kernel to use memory on all nodes evenly.
+
+#
+# Only be set on architectures that have completely implemented memory hotplug
+# feature. If you are not sure, don't touch it.
+#
+config HAVE_BOOTMEM_INFO_NODE
+	def_bool n
+
+# eventually, we can have this option just 'select SPARSEMEM'
+config MEMORY_HOTPLUG
+	bool "Allow for memory hot-add"
+	depends on SPARSEMEM || X86_64_ACPI_NUMA
+	depends on ARCH_ENABLE_MEMORY_HOTPLUG
+	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
+
+config MEMORY_HOTPLUG_SPARSE
+	def_bool y
+	depends on SPARSEMEM && MEMORY_HOTPLUG
+
+config MEMORY_HOTREMOVE
+	bool "Allow for memory hot remove"
+	select MEMORY_ISOLATION
+	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
+	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
+	depends on MIGRATION
+
+# Heavily threaded applications may benefit from splitting the mm-wide
+# page_table_lock, so that faults on different parts of the user address
+# space can be handled with less contention: split it at this NR_CPUS.
+# Default to 4 for wider testing, though 8 might be more appropriate.
+# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
+# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
+# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
+#
+config SPLIT_PTLOCK_CPUS
+	int
+	default "999999" if !MMU
+	default "999999" if ARM && !CPU_CACHE_VIPT
+	default "999999" if PARISC && !PA20
+	default "4"
+
+config ARCH_ENABLE_SPLIT_PMD_PTLOCK
+	bool
+
+#
+# support for memory balloon
+config MEMORY_BALLOON
+	bool
+
+#
+# support for memory balloon compaction
+config BALLOON_COMPACTION
+	bool "Allow for balloon memory compaction/migration"
+	def_bool y
+	depends on COMPACTION && MEMORY_BALLOON
+	help
+	  Memory fragmentation introduced by ballooning might reduce
+	  significantly the number of 2MB contiguous memory blocks that can be
+	  used within a guest, thus imposing performance penalties associated
+	  with the reduced number of transparent huge pages that could be used
+	  by the guest workload. Allowing the compaction & migration for memory
+	  pages enlisted as being part of memory balloon devices avoids the
+	  scenario aforementioned and helps improving memory defragmentation.
+
+#
+# support for memory compaction
+config COMPACTION
+	bool "Allow for memory compaction"
+	def_bool y
+	select MIGRATION
+	depends on MMU
+	help
+	  Allows the compaction of memory for the allocation of huge pages.
+
+#
+# support for page migration
+#
+config MIGRATION
+	bool "Page migration"
+	def_bool y
+	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
+	help
+	  Allows the migration of the physical location of pages of processes
+	  while the virtual addresses are not changed. This is useful in
+	  two situations. The first is on NUMA systems to put pages nearer
+	  to the processors accessing. The second is when allocating huge
+	  pages as migration can relocate pages to satisfy a huge page
+	  allocation instead of reclaiming.
+
+config ARCH_ENABLE_HUGEPAGE_MIGRATION
+	bool
+
+config PHYS_ADDR_T_64BIT
+	def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
+
+config ZONE_DMA_FLAG
+	int
+	default "0" if !ZONE_DMA
+	default "1"
+
+config BOUNCE
+	bool "Enable bounce buffers"
+	default y
+	depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
+	help
+	  Enable bounce buffers for devices that cannot access
+	  the full range of memory available to the CPU. Enabled
+	  by default when ZONE_DMA or HIGHMEM is selected, but you
+	  may say n to override this.
+
+# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
+# have more than 4GB of memory, but we don't currently use the IOTLB to present
+# a 32-bit address to OHCI.  So we need to use a bounce pool instead.
+config NEED_BOUNCE_POOL
+	bool
+	default y if TILE && USB_OHCI_HCD
+
+config NR_QUICK
+	int
+	depends on QUICKLIST
+	default "2" if AVR32
+	default "1"
+
+config VIRT_TO_BUS
+	bool
+	help
+	  An architecture should select this if it implements the
+	  deprecated interface virt_to_bus().  All new architectures
+	  should probably not select this.
+
+
+config MMU_NOTIFIER
+	bool
+	select SRCU
+
+config KSM
+	bool "Enable KSM for page merging"
+	depends on MMU
+	help
+	  Enable Kernel Samepage Merging: KSM periodically scans those areas
+	  of an application's address space that an app has advised may be
+	  mergeable.  When it finds pages of identical content, it replaces
+	  the many instances by a single page with that content, so
+	  saving memory until one or another app needs to modify the content.
+	  Recommended for use with KVM, or with other duplicative applications.
+	  See Documentation/vm/ksm.txt for more information: KSM is inactive
+	  until a program has madvised that an area is MADV_MERGEABLE, and
+	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
+
+config DEFAULT_MMAP_MIN_ADDR
+        int "Low address space to protect from user allocation"
+	depends on MMU
+        default 4096
+        help
+	  This is the portion of low virtual memory which should be protected
+	  from userspace allocation.  Keeping a user from writing to low pages
+	  can help reduce the impact of kernel NULL pointer bugs.
+
+	  For most ia64, ppc64 and x86 users with lots of address space
+	  a value of 65536 is reasonable and should cause no problems.
+	  On arm and other archs it should not be higher than 32768.
+	  Programs which use vm86 functionality or have some need to map
+	  this low address space will need CAP_SYS_RAWIO or disable this
+	  protection by setting the value to 0.
+
+	  This value can be changed after boot using the
+	  /proc/sys/vm/mmap_min_addr tunable.
+
+config ARCH_SUPPORTS_MEMORY_FAILURE
+	bool
+
+config MEMORY_FAILURE
+	depends on MMU
+	depends on ARCH_SUPPORTS_MEMORY_FAILURE
+	bool "Enable recovery from hardware memory errors"
+	select MEMORY_ISOLATION
+	select RAS
+	help
+	  Enables code to recover from some memory failures on systems
+	  with MCA recovery. This allows a system to continue running
+	  even when some of its memory has uncorrected errors. This requires
+	  special hardware support and typically ECC memory.
+
+config HWPOISON_INJECT
+	tristate "HWPoison pages injector"
+	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
+	select PROC_PAGE_MONITOR
+
+config NOMMU_INITIAL_TRIM_EXCESS
+	int "Turn on mmap() excess space trimming before booting"
+	depends on !MMU
+	default 1
+	help
+	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
+	  of memory on which to store mappings, but it can only ask the system
+	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
+	  more than it requires.  To deal with this, mmap() is able to trim off
+	  the excess and return it to the allocator.
+
+	  If trimming is enabled, the excess is trimmed off and returned to the
+	  system allocator, which can cause extra fragmentation, particularly
+	  if there are a lot of transient processes.
+
+	  If trimming is disabled, the excess is kept, but not used, which for
+	  long-term mappings means that the space is wasted.
+
+	  Trimming can be dynamically controlled through a sysctl option
+	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
+	  excess pages there must be before trimming should occur, or zero if
+	  no trimming is to occur.
+
+	  This option specifies the initial value of this option.  The default
+	  of 1 says that all excess pages should be trimmed.
+
+	  See Documentation/nommu-mmap.txt for more information.
+
+config TRANSPARENT_HUGEPAGE
+	bool "Transparent Hugepage Support"
+	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select COMPACTION
+	help
+	  Transparent Hugepages allows the kernel to use huge pages and
+	  huge tlb transparently to the applications whenever possible.
+	  This feature can improve computing performance to certain
+	  applications by speeding up page faults during memory
+	  allocation, by reducing the number of tlb misses and by speeding
+	  up the pagetable walking.
+
+	  If memory constrained on embedded, you may want to say N.
+
+choice
+	prompt "Transparent Hugepage Support sysfs defaults"
+	depends on TRANSPARENT_HUGEPAGE
+	default TRANSPARENT_HUGEPAGE_ALWAYS
+	help
+	  Selects the sysfs defaults for Transparent Hugepage Support.
+
+	config TRANSPARENT_HUGEPAGE_ALWAYS
+		bool "always"
+	help
+	  Enabling Transparent Hugepage always, can increase the
+	  memory footprint of applications without a guaranteed
+	  benefit but it will work automatically for all applications.
+
+	config TRANSPARENT_HUGEPAGE_MADVISE
+		bool "madvise"
+	help
+	  Enabling Transparent Hugepage madvise, will only provide a
+	  performance improvement benefit to the applications using
+	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
+	  memory footprint of applications without a guaranteed
+	  benefit.
+endchoice
+
+#
+# UP and nommu archs use km based percpu allocator
+#
+config NEED_PER_CPU_KM
+	depends on !SMP
+	bool
+	default y
+
+config CLEANCACHE
+	bool "Enable cleancache driver to cache clean pages if tmem is present"
+	default n
+	help
+	  Cleancache can be thought of as a page-granularity victim cache
+	  for clean pages that the kernel's pageframe replacement algorithm
+	  (PFRA) would like to keep around, but can't since there isn't enough
+	  memory.  So when the PFRA "evicts" a page, it first attempts to use
+	  cleancache code to put the data contained in that page into
+	  "transcendent memory", memory that is not directly accessible or
+	  addressable by the kernel and is of unknown and possibly
+	  time-varying size.  And when a cleancache-enabled
+	  filesystem wishes to access a page in a file on disk, it first
+	  checks cleancache to see if it already contains it; if it does,
+	  the page is copied into the kernel and a disk access is avoided.
+	  When a transcendent memory driver is available (such as zcache or
+	  Xen transcendent memory), a significant I/O reduction
+	  may be achieved.  When none is available, all cleancache calls
+	  are reduced to a single pointer-compare-against-NULL resulting
+	  in a negligible performance hit.
+
+	  If unsure, say Y to enable cleancache
+
+config FRONTSWAP
+	bool "Enable frontswap to cache swap pages if tmem is present"
+	depends on SWAP
+	default n
+	help
+	  Frontswap is so named because it can be thought of as the opposite
+	  of a "backing" store for a swap device.  The data is stored into
+	  "transcendent memory", memory that is not directly accessible or
+	  addressable by the kernel and is of unknown and possibly
+	  time-varying size.  When space in transcendent memory is available,
+	  a significant swap I/O reduction may be achieved.  When none is
+	  available, all frontswap calls are reduced to a single pointer-
+	  compare-against-NULL resulting in a negligible performance hit
+	  and swap data is stored as normal on the matching swap device.
+
+	  If unsure, say Y to enable frontswap.
+
+config CMA
+	bool "Contiguous Memory Allocator"
+	depends on HAVE_MEMBLOCK && MMU
+	select MIGRATION
+	select MEMORY_ISOLATION
+	help
+	  This enables the Contiguous Memory Allocator which allows other
+	  subsystems to allocate big physically-contiguous blocks of memory.
+	  CMA reserves a region of memory and allows only movable pages to
+	  be allocated from it. This way, the kernel can use the memory for
+	  pagecache and when a subsystem requests for contiguous area, the
+	  allocated pages are migrated away to serve the contiguous request.
+
+	  If unsure, say "n".
+
+config CMA_DEBUG
+	bool "CMA debug messages (DEVELOPMENT)"
+	depends on DEBUG_KERNEL && CMA
+	help
+	  Turns on debug messages in CMA.  This produces KERN_DEBUG
+	  messages for every CMA call as well as various messages while
+	  processing calls such as dma_alloc_from_contiguous().
+	  This option does not affect warning and error messages.
+
+config CMA_DEBUGFS
+	bool "CMA debugfs interface"
+	depends on CMA && DEBUG_FS
+	help
+	  Turns on the DebugFS interface for CMA.
+
+config CMA_AREAS
+	int "Maximum count of the CMA areas"
+	depends on CMA
+	default 7
+	help
+	  CMA allows to create CMA areas for particular purpose, mainly,
+	  used as device private area. This parameter sets the maximum
+	  number of CMA area in the system.
+
+	  If unsure, leave the default value "7".
+
+config MEM_SOFT_DIRTY
+	bool "Track memory changes"
+	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
+	select PROC_PAGE_MONITOR
+	help
+	  This option enables memory changes tracking by introducing a
+	  soft-dirty bit on pte-s. This bit it set when someone writes
+	  into a page just as regular dirty bit, but unlike the latter
+	  it can be cleared by hands.
+
+	  See Documentation/vm/soft-dirty.txt for more details.
+
+config ZSWAP
+	bool "Compressed cache for swap pages (EXPERIMENTAL)"
+	depends on FRONTSWAP && CRYPTO=y
+	select CRYPTO_LZO
+	select ZPOOL
+	default n
+	help
+	  A lightweight compressed cache for swap pages.  It takes
+	  pages that are in the process of being swapped out and attempts to
+	  compress them into a dynamically allocated RAM-based memory pool.
+	  This can result in a significant I/O reduction on swap device and,
+	  in the case where decompressing from RAM is faster that swap device
+	  reads, can also improve workload performance.
+
+	  This is marked experimental because it is a new feature (as of
+	  v3.11) that interacts heavily with memory reclaim.  While these
+	  interactions don't cause any known issues on simple memory setups,
+	  they have not be fully explored on the large set of potential
+	  configurations and workloads that exist.
+
+config ZPOOL
+	tristate "Common API for compressed memory storage"
+	default n
+	help
+	  Compressed memory storage API.  This allows using either zbud or
+	  zsmalloc.
+
+config ZBUD
+	tristate "Low density storage for compressed pages"
+	default n
+	help
+	  A special purpose allocator for storing compressed pages.
+	  It is designed to store up to two compressed pages per physical
+	  page.  While this design limits storage density, it has simple and
+	  deterministic reclaim properties that make it preferable to a higher
+	  density approach when reclaim will be used.
+
+config ZSMALLOC
+	tristate "Memory allocator for compressed pages"
+	depends on MMU
+	default n
+	help
+	  zsmalloc is a slab-based memory allocator designed to store
+	  compressed RAM pages.  zsmalloc uses virtual memory mapping
+	  in order to reduce fragmentation.  However, this results in a
+	  non-standard allocator interface where a handle, not a pointer, is
+	  returned by an alloc().  This handle must be mapped in order to
+	  access the allocated space.
+
+config PGTABLE_MAPPING
+	bool "Use page table mapping to access object in zsmalloc"
+	depends on ZSMALLOC
+	help
+	  By default, zsmalloc uses a copy-based object mapping method to
+	  access allocations that span two pages. However, if a particular
+	  architecture (ex, ARM) performs VM mapping faster than copying,
+	  then you should select this. This causes zsmalloc to use page table
+	  mapping rather than copying for object mapping.
+
+	  You can check speed with zsmalloc benchmark:
+	  https://github.com/spartacus06/zsmapbench
+
+config ZSMALLOC_STAT
+	bool "Export zsmalloc statistics"
+	depends on ZSMALLOC
+	select DEBUG_FS
+	help
+	  This option enables code in the zsmalloc to collect various
+	  statistics about whats happening in zsmalloc and exports that
+	  information to userspace via debugfs.
+	  If unsure, say N.
+
+config GENERIC_EARLY_IOREMAP
+	bool
+
+config MAX_STACK_SIZE_MB
+	int "Maximum user stack size for 32-bit processes (MB)"
+	default 80
+	range 8 256 if METAG
+	range 8 2048
+	depends on STACK_GROWSUP && (!64BIT || COMPAT)
+	help
+	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
+	  user processes when the stack grows upwards (currently only on parisc
+	  and metag arch). The stack will be located at the highest memory
+	  address minus the given value, unless the RLIMIT_STACK hard limit is
+	  changed to a smaller value in which case that is used.
+
+	  A sane initial value is 80 MB.
+
+# For architectures that support deferred memory initialisation
+config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
+	bool
+
+config DEFERRED_STRUCT_PAGE_INIT
+	bool "Defer initialisation of struct pages to kswapd"
+	default n
+	depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
+	depends on MEMORY_HOTPLUG
+	help
+	  Ordinarily all struct pages are initialised during early boot in a
+	  single thread. On very large machines this can take a considerable
+	  amount of time. If this option is set, large machines will bring up
+	  a subset of memmap at boot and then initialise the rest in parallel
+	  when kswapd starts. This has a potential performance impact on
+	  processes running early in the lifetime of the systemm until kswapd
+	  finishes the initialisation.
+
+config IDLE_PAGE_TRACKING
+	bool "Enable idle page tracking"
+	depends on SYSFS && MMU
+	select PAGE_EXTENSION if !64BIT
+	help
+	  This feature allows to estimate the amount of user pages that have
+	  not been touched during a given period of time. This information can
+	  be useful to tune memory cgroup limits and/or for job placement
+	  within a compute cluster.
+
+	  See Documentation/vm/idle_page_tracking.txt for more details.
+
+config ZONE_DEVICE
+	bool "Device memory (pmem, etc...) hotplug support" if EXPERT
+	default !ZONE_DMA
+	depends on !ZONE_DMA
+	depends on MEMORY_HOTPLUG
+	depends on MEMORY_HOTREMOVE
+	depends on X86_64 #arch_add_memory() comprehends device memory
+
+	help
+	  Device memory hotplug support allows for establishing pmem,
+	  or other device driver discovered memory regions, in the
+	  memmap. This allows pfn_to_page() lookups of otherwise
+	  "device-physical" addresses which is needed for using a DAX
+	  mapping in an O_DIRECT operation, among other things.
+
+	  If FS_DAX is enabled, then say Y.
+
+config FRAME_VECTOR
+	bool
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
new file mode 100644
index 0000000..957d3da
--- /dev/null
+++ b/mm/Kconfig.debug
@@ -0,0 +1,30 @@
+config PAGE_EXTENSION
+	bool "Extend memmap on extra space for more information on page"
+	---help---
+	  Extend memmap on extra space for more information on page. This
+	  could be used for debugging features that need to insert extra
+	  field for every page. This extension enables us to save memory
+	  by not allocating this extra memory according to boottime
+	  configuration.
+
+config DEBUG_PAGEALLOC
+	bool "Debug page memory allocations"
+	depends on DEBUG_KERNEL
+	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
+	depends on !KMEMCHECK
+	select PAGE_EXTENSION
+	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
+	---help---
+	  Unmap pages from the kernel linear mapping after free_pages().
+	  This results in a large slowdown, but helps to find certain types
+	  of memory corruption.
+
+	  For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
+	  fill the pages with poison patterns after free_pages() and verify
+	  the patterns before alloc_pages().  Additionally,
+	  this option cannot be enabled in combination with hibernation as
+	  that would result in incorrect warnings of memory corruption after
+	  a resume because free pages are not saved to the suspend image.
+
+config PAGE_POISONING
+	bool
diff --git a/mm/Makefile b/mm/Makefile
new file mode 100644
index 0000000..2ed4319
--- /dev/null
+++ b/mm/Makefile
@@ -0,0 +1,83 @@
+#
+# Makefile for the linux memory manager.
+#
+
+KASAN_SANITIZE_slab_common.o := n
+KASAN_SANITIZE_slub.o := n
+
+mmu-y			:= nommu.o
+mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
+			   mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
+			   vmalloc.o pagewalk.o pgtable-generic.o
+
+ifdef CONFIG_CROSS_MEMORY_ATTACH
+mmu-$(CONFIG_MMU)	+= process_vm_access.o
+endif
+
+obj-y			:= filemap.o mempool.o oom_kill.o \
+			   maccess.o page_alloc.o page-writeback.o \
+			   readahead.o swap.o truncate.o vmscan.o shmem.o \
+			   util.o mmzone.o vmstat.o backing-dev.o \
+			   mm_init.o mmu_context.o percpu.o slab_common.o \
+			   compaction.o vmacache.o \
+			   interval_tree.o list_lru.o workingset.o \
+			   debug.o $(mmu-y)
+
+obj-y += init-mm.o
+
+ifdef CONFIG_NO_BOOTMEM
+	obj-y		+= nobootmem.o
+else
+	obj-y		+= bootmem.o
+endif
+
+obj-$(CONFIG_ADVISE_SYSCALLS)	+= fadvise.o
+ifdef CONFIG_MMU
+	obj-$(CONFIG_ADVISE_SYSCALLS)	+= madvise.o
+endif
+obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o
+
+obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o
+obj-$(CONFIG_FRONTSWAP)	+= frontswap.o
+obj-$(CONFIG_ZSWAP)	+= zswap.o
+obj-$(CONFIG_HAS_DMA)	+= dmapool.o
+obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
+obj-$(CONFIG_NUMA) 	+= mempolicy.o
+obj-$(CONFIG_SPARSEMEM)	+= sparse.o
+obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
+obj-$(CONFIG_SLOB) += slob.o
+obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
+obj-$(CONFIG_KSM) += ksm.o
+obj-$(CONFIG_PAGE_POISONING) += debug-pagealloc.o
+obj-$(CONFIG_SLAB) += slab.o
+obj-$(CONFIG_SLUB) += slub.o
+obj-$(CONFIG_KMEMCHECK) += kmemcheck.o
+obj-$(CONFIG_KASAN)	+= kasan/
+obj-$(CONFIG_FAILSLAB) += failslab.o
+obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
+obj-$(CONFIG_MEMTEST)		+= memtest.o
+obj-$(CONFIG_MIGRATION) += migrate.o
+obj-$(CONFIG_QUICKLIST) += quicklist.o
+obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o
+obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
+obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o
+obj-$(CONFIG_MEMCG_SWAP) += swap_cgroup.o
+obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o
+obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
+obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
+obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
+obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
+obj-$(CONFIG_PAGE_OWNER) += page_owner.o
+obj-$(CONFIG_CLEANCACHE) += cleancache.o
+obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
+obj-$(CONFIG_ZPOOL)	+= zpool.o
+obj-$(CONFIG_ZBUD)	+= zbud.o
+obj-$(CONFIG_ZSMALLOC)	+= zsmalloc.o
+obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
+obj-$(CONFIG_CMA)	+= cma.o
+obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
+obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
+obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
+obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
+obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o
+obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
new file mode 100644
index 0000000..a988d4e
--- /dev/null
+++ b/mm/backing-dev.c
@@ -0,0 +1,1059 @@
+
+#include <linux/wait.h>
+#include <linux/backing-dev.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/writeback.h>
+#include <linux/device.h>
+#include <trace/events/writeback.h>
+
+static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
+
+struct backing_dev_info noop_backing_dev_info = {
+	.name		= "noop",
+	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+EXPORT_SYMBOL_GPL(noop_backing_dev_info);
+
+static struct class *bdi_class;
+
+/*
+ * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
+ * locking.
+ */
+DEFINE_SPINLOCK(bdi_lock);
+LIST_HEAD(bdi_list);
+
+/* bdi_wq serves all asynchronous writeback tasks */
+struct workqueue_struct *bdi_wq;
+
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+static struct dentry *bdi_debug_root;
+
+static void bdi_debug_init(void)
+{
+	bdi_debug_root = debugfs_create_dir("bdi", NULL);
+}
+
+static int bdi_debug_stats_show(struct seq_file *m, void *v)
+{
+	struct backing_dev_info *bdi = m->private;
+	struct bdi_writeback *wb = &bdi->wb;
+	unsigned long background_thresh;
+	unsigned long dirty_thresh;
+	unsigned long wb_thresh;
+	unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
+	struct inode *inode;
+
+	nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
+	spin_lock(&wb->list_lock);
+	list_for_each_entry(inode, &wb->b_dirty, i_io_list)
+		nr_dirty++;
+	list_for_each_entry(inode, &wb->b_io, i_io_list)
+		nr_io++;
+	list_for_each_entry(inode, &wb->b_more_io, i_io_list)
+		nr_more_io++;
+	list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
+		if (inode->i_state & I_DIRTY_TIME)
+			nr_dirty_time++;
+	spin_unlock(&wb->list_lock);
+
+	global_dirty_limits(&background_thresh, &dirty_thresh);
+	wb_thresh = wb_calc_thresh(wb, dirty_thresh);
+
+#define K(x) ((x) << (PAGE_SHIFT - 10))
+	seq_printf(m,
+		   "BdiWriteback:       %10lu kB\n"
+		   "BdiReclaimable:     %10lu kB\n"
+		   "BdiDirtyThresh:     %10lu kB\n"
+		   "DirtyThresh:        %10lu kB\n"
+		   "BackgroundThresh:   %10lu kB\n"
+		   "BdiDirtied:         %10lu kB\n"
+		   "BdiWritten:         %10lu kB\n"
+		   "BdiWriteBandwidth:  %10lu kBps\n"
+		   "b_dirty:            %10lu\n"
+		   "b_io:               %10lu\n"
+		   "b_more_io:          %10lu\n"
+		   "b_dirty_time:       %10lu\n"
+		   "bdi_list:           %10u\n"
+		   "state:              %10lx\n",
+		   (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
+		   (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
+		   K(wb_thresh),
+		   K(dirty_thresh),
+		   K(background_thresh),
+		   (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
+		   (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
+		   (unsigned long) K(wb->write_bandwidth),
+		   nr_dirty,
+		   nr_io,
+		   nr_more_io,
+		   nr_dirty_time,
+		   !list_empty(&bdi->bdi_list), bdi->wb.state);
+#undef K
+
+	return 0;
+}
+
+static int bdi_debug_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, bdi_debug_stats_show, inode->i_private);
+}
+
+static const struct file_operations bdi_debug_stats_fops = {
+	.open		= bdi_debug_stats_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
+{
+	bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
+	bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
+					       bdi, &bdi_debug_stats_fops);
+}
+
+static void bdi_debug_unregister(struct backing_dev_info *bdi)
+{
+	debugfs_remove(bdi->debug_stats);
+	debugfs_remove(bdi->debug_dir);
+}
+#else
+static inline void bdi_debug_init(void)
+{
+}
+static inline void bdi_debug_register(struct backing_dev_info *bdi,
+				      const char *name)
+{
+}
+static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
+{
+}
+#endif
+
+static ssize_t read_ahead_kb_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct backing_dev_info *bdi = dev_get_drvdata(dev);
+	unsigned long read_ahead_kb;
+	ssize_t ret;
+
+	ret = kstrtoul(buf, 10, &read_ahead_kb);
+	if (ret < 0)
+		return ret;
+
+	bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
+
+	return count;
+}
+
+#define K(pages) ((pages) << (PAGE_SHIFT - 10))
+
+#define BDI_SHOW(name, expr)						\
+static ssize_t name##_show(struct device *dev,				\
+			   struct device_attribute *attr, char *page)	\
+{									\
+	struct backing_dev_info *bdi = dev_get_drvdata(dev);		\
+									\
+	return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr);	\
+}									\
+static DEVICE_ATTR_RW(name);
+
+BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
+
+static ssize_t min_ratio_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct backing_dev_info *bdi = dev_get_drvdata(dev);
+	unsigned int ratio;
+	ssize_t ret;
+
+	ret = kstrtouint(buf, 10, &ratio);
+	if (ret < 0)
+		return ret;
+
+	ret = bdi_set_min_ratio(bdi, ratio);
+	if (!ret)
+		ret = count;
+
+	return ret;
+}
+BDI_SHOW(min_ratio, bdi->min_ratio)
+
+static ssize_t max_ratio_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct backing_dev_info *bdi = dev_get_drvdata(dev);
+	unsigned int ratio;
+	ssize_t ret;
+
+	ret = kstrtouint(buf, 10, &ratio);
+	if (ret < 0)
+		return ret;
+
+	ret = bdi_set_max_ratio(bdi, ratio);
+	if (!ret)
+		ret = count;
+
+	return ret;
+}
+BDI_SHOW(max_ratio, bdi->max_ratio)
+
+static ssize_t stable_pages_required_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *page)
+{
+	struct backing_dev_info *bdi = dev_get_drvdata(dev);
+
+	return snprintf(page, PAGE_SIZE-1, "%d\n",
+			bdi_cap_stable_pages_required(bdi) ? 1 : 0);
+}
+static DEVICE_ATTR_RO(stable_pages_required);
+
+static struct attribute *bdi_dev_attrs[] = {
+	&dev_attr_read_ahead_kb.attr,
+	&dev_attr_min_ratio.attr,
+	&dev_attr_max_ratio.attr,
+	&dev_attr_stable_pages_required.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(bdi_dev);
+
+static __init int bdi_class_init(void)
+{
+	bdi_class = class_create(THIS_MODULE, "bdi");
+	if (IS_ERR(bdi_class))
+		return PTR_ERR(bdi_class);
+
+	bdi_class->dev_groups = bdi_dev_groups;
+	bdi_debug_init();
+	return 0;
+}
+postcore_initcall(bdi_class_init);
+
+static int __init default_bdi_init(void)
+{
+	int err;
+
+	bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
+					      WQ_UNBOUND | WQ_SYSFS, 0);
+	if (!bdi_wq)
+		return -ENOMEM;
+
+	err = bdi_init(&noop_backing_dev_info);
+
+	return err;
+}
+subsys_initcall(default_bdi_init);
+
+/*
+ * This function is used when the first inode for this wb is marked dirty. It
+ * wakes-up the corresponding bdi thread which should then take care of the
+ * periodic background write-out of dirty inodes. Since the write-out would
+ * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
+ * set up a timer which wakes the bdi thread up later.
+ *
+ * Note, we wouldn't bother setting up the timer, but this function is on the
+ * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
+ * by delaying the wake-up.
+ *
+ * We have to be careful not to postpone flush work if it is scheduled for
+ * earlier. Thus we use queue_delayed_work().
+ */
+void wb_wakeup_delayed(struct bdi_writeback *wb)
+{
+	unsigned long timeout;
+
+	timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
+	spin_lock_bh(&wb->work_lock);
+	if (test_bit(WB_registered, &wb->state))
+		queue_delayed_work(bdi_wq, &wb->dwork, timeout);
+	spin_unlock_bh(&wb->work_lock);
+}
+
+/*
+ * Initial write bandwidth: 100 MB/s
+ */
+#define INIT_BW		(100 << (20 - PAGE_SHIFT))
+
+static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
+		   int blkcg_id, gfp_t gfp)
+{
+	int i, err;
+
+	memset(wb, 0, sizeof(*wb));
+
+	wb->bdi = bdi;
+	wb->last_old_flush = jiffies;
+	INIT_LIST_HEAD(&wb->b_dirty);
+	INIT_LIST_HEAD(&wb->b_io);
+	INIT_LIST_HEAD(&wb->b_more_io);
+	INIT_LIST_HEAD(&wb->b_dirty_time);
+	spin_lock_init(&wb->list_lock);
+
+	wb->bw_time_stamp = jiffies;
+	wb->balanced_dirty_ratelimit = INIT_BW;
+	wb->dirty_ratelimit = INIT_BW;
+	wb->write_bandwidth = INIT_BW;
+	wb->avg_write_bandwidth = INIT_BW;
+
+	spin_lock_init(&wb->work_lock);
+	INIT_LIST_HEAD(&wb->work_list);
+	INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
+
+	wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
+	if (!wb->congested)
+		return -ENOMEM;
+
+	err = fprop_local_init_percpu(&wb->completions, gfp);
+	if (err)
+		goto out_put_cong;
+
+	for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
+		err = percpu_counter_init(&wb->stat[i], 0, gfp);
+		if (err)
+			goto out_destroy_stat;
+	}
+
+	return 0;
+
+out_destroy_stat:
+	while (--i)
+		percpu_counter_destroy(&wb->stat[i]);
+	fprop_local_destroy_percpu(&wb->completions);
+out_put_cong:
+	wb_congested_put(wb->congested);
+	return err;
+}
+
+/*
+ * Remove bdi from the global list and shutdown any threads we have running
+ */
+static void wb_shutdown(struct bdi_writeback *wb)
+{
+	/* Make sure nobody queues further work */
+	spin_lock_bh(&wb->work_lock);
+	if (!test_and_clear_bit(WB_registered, &wb->state)) {
+		spin_unlock_bh(&wb->work_lock);
+		return;
+	}
+	spin_unlock_bh(&wb->work_lock);
+
+	/*
+	 * Drain work list and shutdown the delayed_work.  !WB_registered
+	 * tells wb_workfn() that @wb is dying and its work_list needs to
+	 * be drained no matter what.
+	 */
+	mod_delayed_work(bdi_wq, &wb->dwork, 0);
+	flush_delayed_work(&wb->dwork);
+	WARN_ON(!list_empty(&wb->work_list));
+}
+
+static void wb_exit(struct bdi_writeback *wb)
+{
+	int i;
+
+	WARN_ON(delayed_work_pending(&wb->dwork));
+
+	for (i = 0; i < NR_WB_STAT_ITEMS; i++)
+		percpu_counter_destroy(&wb->stat[i]);
+
+	fprop_local_destroy_percpu(&wb->completions);
+	wb_congested_put(wb->congested);
+}
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+#include <linux/memcontrol.h>
+
+/*
+ * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
+ * blkcg->cgwb_list, and memcg->cgwb_list.  bdi->cgwb_tree is also RCU
+ * protected.  cgwb_release_wait is used to wait for the completion of cgwb
+ * releases from bdi destruction path.
+ */
+static DEFINE_SPINLOCK(cgwb_lock);
+static DECLARE_WAIT_QUEUE_HEAD(cgwb_release_wait);
+
+/**
+ * wb_congested_get_create - get or create a wb_congested
+ * @bdi: associated bdi
+ * @blkcg_id: ID of the associated blkcg
+ * @gfp: allocation mask
+ *
+ * Look up the wb_congested for @blkcg_id on @bdi.  If missing, create one.
+ * The returned wb_congested has its reference count incremented.  Returns
+ * NULL on failure.
+ */
+struct bdi_writeback_congested *
+wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
+{
+	struct bdi_writeback_congested *new_congested = NULL, *congested;
+	struct rb_node **node, *parent;
+	unsigned long flags;
+retry:
+	spin_lock_irqsave(&cgwb_lock, flags);
+
+	node = &bdi->cgwb_congested_tree.rb_node;
+	parent = NULL;
+
+	while (*node != NULL) {
+		parent = *node;
+		congested = container_of(parent, struct bdi_writeback_congested,
+					 rb_node);
+		if (congested->blkcg_id < blkcg_id)
+			node = &parent->rb_left;
+		else if (congested->blkcg_id > blkcg_id)
+			node = &parent->rb_right;
+		else
+			goto found;
+	}
+
+	if (new_congested) {
+		/* !found and storage for new one already allocated, insert */
+		congested = new_congested;
+		new_congested = NULL;
+		rb_link_node(&congested->rb_node, parent, node);
+		rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
+		goto found;
+	}
+
+	spin_unlock_irqrestore(&cgwb_lock, flags);
+
+	/* allocate storage for new one and retry */
+	new_congested = kzalloc(sizeof(*new_congested), gfp);
+	if (!new_congested)
+		return NULL;
+
+	atomic_set(&new_congested->refcnt, 0);
+	new_congested->bdi = bdi;
+	new_congested->blkcg_id = blkcg_id;
+	goto retry;
+
+found:
+	atomic_inc(&congested->refcnt);
+	spin_unlock_irqrestore(&cgwb_lock, flags);
+	kfree(new_congested);
+	return congested;
+}
+
+/**
+ * wb_congested_put - put a wb_congested
+ * @congested: wb_congested to put
+ *
+ * Put @congested and destroy it if the refcnt reaches zero.
+ */
+void wb_congested_put(struct bdi_writeback_congested *congested)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
+		local_irq_restore(flags);
+		return;
+	}
+
+	/* bdi might already have been destroyed leaving @congested unlinked */
+	if (congested->bdi) {
+		rb_erase(&congested->rb_node,
+			 &congested->bdi->cgwb_congested_tree);
+		congested->bdi = NULL;
+	}
+
+	spin_unlock_irqrestore(&cgwb_lock, flags);
+	kfree(congested);
+}
+
+static void cgwb_release_workfn(struct work_struct *work)
+{
+	struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
+						release_work);
+	struct backing_dev_info *bdi = wb->bdi;
+
+	spin_lock_irq(&cgwb_lock);
+	list_del_rcu(&wb->bdi_node);
+	spin_unlock_irq(&cgwb_lock);
+
+	wb_shutdown(wb);
+
+	css_put(wb->memcg_css);
+	css_put(wb->blkcg_css);
+
+	fprop_local_destroy_percpu(&wb->memcg_completions);
+	percpu_ref_exit(&wb->refcnt);
+	wb_exit(wb);
+	kfree_rcu(wb, rcu);
+
+	if (atomic_dec_and_test(&bdi->usage_cnt))
+		wake_up_all(&cgwb_release_wait);
+}
+
+static void cgwb_release(struct percpu_ref *refcnt)
+{
+	struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
+						refcnt);
+	schedule_work(&wb->release_work);
+}
+
+static void cgwb_kill(struct bdi_writeback *wb)
+{
+	lockdep_assert_held(&cgwb_lock);
+
+	WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
+	list_del(&wb->memcg_node);
+	list_del(&wb->blkcg_node);
+	percpu_ref_kill(&wb->refcnt);
+}
+
+static int cgwb_create(struct backing_dev_info *bdi,
+		       struct cgroup_subsys_state *memcg_css, gfp_t gfp)
+{
+	struct mem_cgroup *memcg;
+	struct cgroup_subsys_state *blkcg_css;
+	struct blkcg *blkcg;
+	struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
+	struct bdi_writeback *wb;
+	unsigned long flags;
+	int ret = 0;
+
+	memcg = mem_cgroup_from_css(memcg_css);
+	blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
+	blkcg = css_to_blkcg(blkcg_css);
+	memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
+	blkcg_cgwb_list = &blkcg->cgwb_list;
+
+	/* look up again under lock and discard on blkcg mismatch */
+	spin_lock_irqsave(&cgwb_lock, flags);
+	wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
+	if (wb && wb->blkcg_css != blkcg_css) {
+		cgwb_kill(wb);
+		wb = NULL;
+	}
+	spin_unlock_irqrestore(&cgwb_lock, flags);
+	if (wb)
+		goto out_put;
+
+	/* need to create a new one */
+	wb = kmalloc(sizeof(*wb), gfp);
+	if (!wb)
+		return -ENOMEM;
+
+	ret = wb_init(wb, bdi, blkcg_css->id, gfp);
+	if (ret)
+		goto err_free;
+
+	ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
+	if (ret)
+		goto err_wb_exit;
+
+	ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
+	if (ret)
+		goto err_ref_exit;
+
+	wb->memcg_css = memcg_css;
+	wb->blkcg_css = blkcg_css;
+	INIT_WORK(&wb->release_work, cgwb_release_workfn);
+	set_bit(WB_registered, &wb->state);
+
+	/*
+	 * The root wb determines the registered state of the whole bdi and
+	 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
+	 * whether they're still online.  Don't link @wb if any is dead.
+	 * See wb_memcg_offline() and wb_blkcg_offline().
+	 */
+	ret = -ENODEV;
+	spin_lock_irqsave(&cgwb_lock, flags);
+	if (test_bit(WB_registered, &bdi->wb.state) &&
+	    blkcg_cgwb_list->next && memcg_cgwb_list->next) {
+		/* we might have raced another instance of this function */
+		ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
+		if (!ret) {
+			atomic_inc(&bdi->usage_cnt);
+			list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
+			list_add(&wb->memcg_node, memcg_cgwb_list);
+			list_add(&wb->blkcg_node, blkcg_cgwb_list);
+			css_get(memcg_css);
+			css_get(blkcg_css);
+		}
+	}
+	spin_unlock_irqrestore(&cgwb_lock, flags);
+	if (ret) {
+		if (ret == -EEXIST)
+			ret = 0;
+		goto err_fprop_exit;
+	}
+	goto out_put;
+
+err_fprop_exit:
+	fprop_local_destroy_percpu(&wb->memcg_completions);
+err_ref_exit:
+	percpu_ref_exit(&wb->refcnt);
+err_wb_exit:
+	wb_exit(wb);
+err_free:
+	kfree(wb);
+out_put:
+	css_put(blkcg_css);
+	return ret;
+}
+
+/**
+ * wb_get_create - get wb for a given memcg, create if necessary
+ * @bdi: target bdi
+ * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
+ * @gfp: allocation mask to use
+ *
+ * Try to get the wb for @memcg_css on @bdi.  If it doesn't exist, try to
+ * create one.  The returned wb has its refcount incremented.
+ *
+ * This function uses css_get() on @memcg_css and thus expects its refcnt
+ * to be positive on invocation.  IOW, rcu_read_lock() protection on
+ * @memcg_css isn't enough.  try_get it before calling this function.
+ *
+ * A wb is keyed by its associated memcg.  As blkcg implicitly enables
+ * memcg on the default hierarchy, memcg association is guaranteed to be
+ * more specific (equal or descendant to the associated blkcg) and thus can
+ * identify both the memcg and blkcg associations.
+ *
+ * Because the blkcg associated with a memcg may change as blkcg is enabled
+ * and disabled closer to root in the hierarchy, each wb keeps track of
+ * both the memcg and blkcg associated with it and verifies the blkcg on
+ * each lookup.  On mismatch, the existing wb is discarded and a new one is
+ * created.
+ */
+struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
+				    struct cgroup_subsys_state *memcg_css,
+				    gfp_t gfp)
+{
+	struct bdi_writeback *wb;
+
+	might_sleep_if(gfpflags_allow_blocking(gfp));
+
+	if (!memcg_css->parent)
+		return &bdi->wb;
+
+	do {
+		rcu_read_lock();
+		wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
+		if (wb) {
+			struct cgroup_subsys_state *blkcg_css;
+
+			/* see whether the blkcg association has changed */
+			blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
+						     &io_cgrp_subsys);
+			if (unlikely(wb->blkcg_css != blkcg_css ||
+				     !wb_tryget(wb)))
+				wb = NULL;
+			css_put(blkcg_css);
+		}
+		rcu_read_unlock();
+	} while (!wb && !cgwb_create(bdi, memcg_css, gfp));
+
+	return wb;
+}
+
+static int cgwb_bdi_init(struct backing_dev_info *bdi)
+{
+	int ret;
+
+	INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
+	bdi->cgwb_congested_tree = RB_ROOT;
+	atomic_set(&bdi->usage_cnt, 1);
+
+	ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
+	if (!ret) {
+		bdi->wb.memcg_css = mem_cgroup_root_css;
+		bdi->wb.blkcg_css = blkcg_root_css;
+	}
+	return ret;
+}
+
+static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
+{
+	struct radix_tree_iter iter;
+	struct rb_node *rbn;
+	void **slot;
+
+	WARN_ON(test_bit(WB_registered, &bdi->wb.state));
+
+	spin_lock_irq(&cgwb_lock);
+
+	radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
+		cgwb_kill(*slot);
+
+	while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
+		struct bdi_writeback_congested *congested =
+			rb_entry(rbn, struct bdi_writeback_congested, rb_node);
+
+		rb_erase(rbn, &bdi->cgwb_congested_tree);
+		congested->bdi = NULL;	/* mark @congested unlinked */
+	}
+
+	spin_unlock_irq(&cgwb_lock);
+
+	/*
+	 * All cgwb's and their congested states must be shutdown and
+	 * released before returning.  Drain the usage counter to wait for
+	 * all cgwb's and cgwb_congested's ever created on @bdi.
+	 */
+	atomic_dec(&bdi->usage_cnt);
+	wait_event(cgwb_release_wait, !atomic_read(&bdi->usage_cnt));
+}
+
+/**
+ * wb_memcg_offline - kill all wb's associated with a memcg being offlined
+ * @memcg: memcg being offlined
+ *
+ * Also prevents creation of any new wb's associated with @memcg.
+ */
+void wb_memcg_offline(struct mem_cgroup *memcg)
+{
+	LIST_HEAD(to_destroy);
+	struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
+	struct bdi_writeback *wb, *next;
+
+	spin_lock_irq(&cgwb_lock);
+	list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
+		cgwb_kill(wb);
+	memcg_cgwb_list->next = NULL;	/* prevent new wb's */
+	spin_unlock_irq(&cgwb_lock);
+}
+
+/**
+ * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
+ * @blkcg: blkcg being offlined
+ *
+ * Also prevents creation of any new wb's associated with @blkcg.
+ */
+void wb_blkcg_offline(struct blkcg *blkcg)
+{
+	LIST_HEAD(to_destroy);
+	struct bdi_writeback *wb, *next;
+
+	spin_lock_irq(&cgwb_lock);
+	list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
+		cgwb_kill(wb);
+	blkcg->cgwb_list.next = NULL;	/* prevent new wb's */
+	spin_unlock_irq(&cgwb_lock);
+}
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+static int cgwb_bdi_init(struct backing_dev_info *bdi)
+{
+	int err;
+
+	bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
+	if (!bdi->wb_congested)
+		return -ENOMEM;
+
+	atomic_set(&bdi->wb_congested->refcnt, 1);
+
+	err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
+	if (err) {
+		wb_congested_put(bdi->wb_congested);
+		return err;
+	}
+	return 0;
+}
+
+static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
+{
+	wb_congested_put(bdi->wb_congested);
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+
+int bdi_init(struct backing_dev_info *bdi)
+{
+	int ret;
+
+	bdi->dev = NULL;
+
+	bdi->min_ratio = 0;
+	bdi->max_ratio = 100;
+	bdi->max_prop_frac = FPROP_FRAC_BASE;
+	INIT_LIST_HEAD(&bdi->bdi_list);
+	INIT_LIST_HEAD(&bdi->wb_list);
+	init_waitqueue_head(&bdi->wb_waitq);
+
+	ret = cgwb_bdi_init(bdi);
+
+	list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
+
+	return ret;
+}
+EXPORT_SYMBOL(bdi_init);
+
+int bdi_register(struct backing_dev_info *bdi, struct device *parent,
+		const char *fmt, ...)
+{
+	va_list args;
+	struct device *dev;
+
+	if (bdi->dev)	/* The driver needs to use separate queues per device */
+		return 0;
+
+	va_start(args, fmt);
+	dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
+	va_end(args);
+	if (IS_ERR(dev))
+		return PTR_ERR(dev);
+
+	bdi->dev = dev;
+
+	bdi_debug_register(bdi, dev_name(dev));
+	set_bit(WB_registered, &bdi->wb.state);
+
+	spin_lock_bh(&bdi_lock);
+	list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+	spin_unlock_bh(&bdi_lock);
+
+	trace_writeback_bdi_register(bdi);
+	return 0;
+}
+EXPORT_SYMBOL(bdi_register);
+
+int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
+{
+	return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
+}
+EXPORT_SYMBOL(bdi_register_dev);
+
+int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
+{
+	int rc;
+
+	rc = bdi_register(bdi, NULL, "%u:%u", MAJOR(owner->devt),
+			MINOR(owner->devt));
+	if (rc)
+		return rc;
+	bdi->owner = owner;
+	get_device(owner);
+	return 0;
+}
+EXPORT_SYMBOL(bdi_register_owner);
+
+/*
+ * Remove bdi from bdi_list, and ensure that it is no longer visible
+ */
+static void bdi_remove_from_list(struct backing_dev_info *bdi)
+{
+	spin_lock_bh(&bdi_lock);
+	list_del_rcu(&bdi->bdi_list);
+	spin_unlock_bh(&bdi_lock);
+
+	synchronize_rcu_expedited();
+}
+
+void bdi_unregister(struct backing_dev_info *bdi)
+{
+	/* make sure nobody finds us on the bdi_list anymore */
+	bdi_remove_from_list(bdi);
+	wb_shutdown(&bdi->wb);
+	cgwb_bdi_destroy(bdi);
+
+	if (bdi->dev) {
+		bdi_debug_unregister(bdi);
+		device_unregister(bdi->dev);
+		bdi->dev = NULL;
+	}
+
+	if (bdi->owner) {
+		put_device(bdi->owner);
+		bdi->owner = NULL;
+	}
+}
+
+void bdi_exit(struct backing_dev_info *bdi)
+{
+	WARN_ON_ONCE(bdi->dev);
+	wb_exit(&bdi->wb);
+}
+
+void bdi_destroy(struct backing_dev_info *bdi)
+{
+	bdi_unregister(bdi);
+	bdi_exit(bdi);
+}
+EXPORT_SYMBOL(bdi_destroy);
+
+/*
+ * For use from filesystems to quickly init and register a bdi associated
+ * with dirty writeback
+ */
+int bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
+{
+	int err;
+
+	bdi->name = name;
+	bdi->capabilities = 0;
+	err = bdi_init(bdi);
+	if (err)
+		return err;
+
+	err = bdi_register(bdi, NULL, "%.28s-%ld", name,
+			   atomic_long_inc_return(&bdi_seq));
+	if (err) {
+		bdi_destroy(bdi);
+		return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(bdi_setup_and_register);
+
+static wait_queue_head_t congestion_wqh[2] = {
+		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
+		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
+	};
+static atomic_t nr_wb_congested[2];
+
+void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)
+{
+	wait_queue_head_t *wqh = &congestion_wqh[sync];
+	enum wb_state bit;
+
+	bit = sync ? WB_sync_congested : WB_async_congested;
+	if (test_and_clear_bit(bit, &congested->state))
+		atomic_dec(&nr_wb_congested[sync]);
+	smp_mb__after_atomic();
+	if (waitqueue_active(wqh))
+		wake_up(wqh);
+}
+EXPORT_SYMBOL(clear_wb_congested);
+
+void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
+{
+	enum wb_state bit;
+
+	bit = sync ? WB_sync_congested : WB_async_congested;
+	if (!test_and_set_bit(bit, &congested->state))
+		atomic_inc(&nr_wb_congested[sync]);
+}
+EXPORT_SYMBOL(set_wb_congested);
+
+/**
+ * congestion_wait - wait for a backing_dev to become uncongested
+ * @sync: SYNC or ASYNC IO
+ * @timeout: timeout in jiffies
+ *
+ * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
+ * write congestion.  If no backing_devs are congested then just wait for the
+ * next write to be completed.
+ */
+long congestion_wait(int sync, long timeout)
+{
+	long ret;
+	unsigned long start = jiffies;
+	DEFINE_WAIT(wait);
+	wait_queue_head_t *wqh = &congestion_wqh[sync];
+
+	prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
+	ret = io_schedule_timeout(timeout);
+	finish_wait(wqh, &wait);
+
+	trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
+					jiffies_to_usecs(jiffies - start));
+
+	return ret;
+}
+EXPORT_SYMBOL(congestion_wait);
+
+/**
+ * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes
+ * @zone: A zone to check if it is heavily congested
+ * @sync: SYNC or ASYNC IO
+ * @timeout: timeout in jiffies
+ *
+ * In the event of a congested backing_dev (any backing_dev) and the given
+ * @zone has experienced recent congestion, this waits for up to @timeout
+ * jiffies for either a BDI to exit congestion of the given @sync queue
+ * or a write to complete.
+ *
+ * In the absence of zone congestion, a short sleep or a cond_resched is
+ * performed to yield the processor and to allow other subsystems to make
+ * a forward progress.
+ *
+ * The return value is 0 if the sleep is for the full timeout. Otherwise,
+ * it is the number of jiffies that were still remaining when the function
+ * returned. return_value == timeout implies the function did not sleep.
+ */
+long wait_iff_congested(struct zone *zone, int sync, long timeout)
+{
+	long ret;
+	unsigned long start = jiffies;
+	DEFINE_WAIT(wait);
+	wait_queue_head_t *wqh = &congestion_wqh[sync];
+
+	/*
+	 * If there is no congestion, or heavy congestion is not being
+	 * encountered in the current zone, yield if necessary instead
+	 * of sleeping on the congestion queue
+	 */
+	if (atomic_read(&nr_wb_congested[sync]) == 0 ||
+	    !test_bit(ZONE_CONGESTED, &zone->flags)) {
+
+		/*
+		 * Memory allocation/reclaim might be called from a WQ
+		 * context and the current implementation of the WQ
+		 * concurrency control doesn't recognize that a particular
+		 * WQ is congested if the worker thread is looping without
+		 * ever sleeping. Therefore we have to do a short sleep
+		 * here rather than calling cond_resched().
+		 */
+		if (current->flags & PF_WQ_WORKER)
+			schedule_timeout_uninterruptible(1);
+		else
+			cond_resched();
+
+		/* In case we scheduled, work out time remaining */
+		ret = timeout - (jiffies - start);
+		if (ret < 0)
+			ret = 0;
+
+		goto out;
+	}
+
+	/* Sleep until uncongested or a write happens */
+	prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
+	ret = io_schedule_timeout(timeout);
+	finish_wait(wqh, &wait);
+
+out:
+	trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
+					jiffies_to_usecs(jiffies - start));
+
+	return ret;
+}
+EXPORT_SYMBOL(wait_iff_congested);
+
+int pdflush_proc_obsolete(struct ctl_table *table, int write,
+			void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	char kbuf[] = "0\n";
+
+	if (*ppos || *lenp < sizeof(kbuf)) {
+		*lenp = 0;
+		return 0;
+	}
+
+	if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
+		return -EFAULT;
+	printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
+			table->procname);
+
+	*lenp = 2;
+	*ppos += *lenp;
+	return 2;
+}
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
new file mode 100644
index 0000000..300117f
--- /dev/null
+++ b/mm/balloon_compaction.c
@@ -0,0 +1,215 @@
+/*
+ * mm/balloon_compaction.c
+ *
+ * Common interface for making balloon pages movable by compaction.
+ *
+ * Copyright (C) 2012, Red Hat, Inc.  Rafael Aquini <aquini@redhat.com>
+ */
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/balloon_compaction.h>
+
+/*
+ * balloon_page_enqueue - allocates a new page and inserts it into the balloon
+ *			  page list.
+ * @b_dev_info: balloon device decriptor where we will insert a new page to
+ *
+ * Driver must call it to properly allocate a new enlisted balloon page
+ * before definetively removing it from the guest system.
+ * This function returns the page address for the recently enqueued page or
+ * NULL in the case we fail to allocate a new page this turn.
+ */
+struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info)
+{
+	unsigned long flags;
+	struct page *page = alloc_page(balloon_mapping_gfp_mask() |
+					__GFP_NOMEMALLOC | __GFP_NORETRY);
+	if (!page)
+		return NULL;
+
+	/*
+	 * Block others from accessing the 'page' when we get around to
+	 * establishing additional references. We should be the only one
+	 * holding a reference to the 'page' at this point.
+	 */
+	BUG_ON(!trylock_page(page));
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	balloon_page_insert(b_dev_info, page);
+	__count_vm_event(BALLOON_INFLATE);
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+	unlock_page(page);
+	return page;
+}
+EXPORT_SYMBOL_GPL(balloon_page_enqueue);
+
+/*
+ * balloon_page_dequeue - removes a page from balloon's page list and returns
+ *			  the its address to allow the driver release the page.
+ * @b_dev_info: balloon device decriptor where we will grab a page from.
+ *
+ * Driver must call it to properly de-allocate a previous enlisted balloon page
+ * before definetively releasing it back to the guest system.
+ * This function returns the page address for the recently dequeued page or
+ * NULL in the case we find balloon's page list temporarily empty due to
+ * compaction isolated pages.
+ */
+struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
+{
+	struct page *page, *tmp;
+	unsigned long flags;
+	bool dequeued_page;
+
+	dequeued_page = false;
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
+		/*
+		 * Block others from accessing the 'page' while we get around
+		 * establishing additional references and preparing the 'page'
+		 * to be released by the balloon driver.
+		 */
+		if (trylock_page(page)) {
+#ifdef CONFIG_BALLOON_COMPACTION
+			if (!PagePrivate(page)) {
+				/* raced with isolation */
+				unlock_page(page);
+				continue;
+			}
+#endif
+			balloon_page_delete(page);
+			__count_vm_event(BALLOON_DEFLATE);
+			unlock_page(page);
+			dequeued_page = true;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+
+	if (!dequeued_page) {
+		/*
+		 * If we are unable to dequeue a balloon page because the page
+		 * list is empty and there is no isolated pages, then something
+		 * went out of track and some balloon pages are lost.
+		 * BUG() here, otherwise the balloon driver may get stuck into
+		 * an infinite loop while attempting to release all its pages.
+		 */
+		spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+		if (unlikely(list_empty(&b_dev_info->pages) &&
+			     !b_dev_info->isolated_pages))
+			BUG();
+		spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+		page = NULL;
+	}
+	return page;
+}
+EXPORT_SYMBOL_GPL(balloon_page_dequeue);
+
+#ifdef CONFIG_BALLOON_COMPACTION
+
+static inline void __isolate_balloon_page(struct page *page)
+{
+	struct balloon_dev_info *b_dev_info = balloon_page_device(page);
+	unsigned long flags;
+
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	ClearPagePrivate(page);
+	list_del(&page->lru);
+	b_dev_info->isolated_pages++;
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+}
+
+static inline void __putback_balloon_page(struct page *page)
+{
+	struct balloon_dev_info *b_dev_info = balloon_page_device(page);
+	unsigned long flags;
+
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	SetPagePrivate(page);
+	list_add(&page->lru, &b_dev_info->pages);
+	b_dev_info->isolated_pages--;
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+}
+
+/* __isolate_lru_page() counterpart for a ballooned page */
+bool balloon_page_isolate(struct page *page)
+{
+	/*
+	 * Avoid burning cycles with pages that are yet under __free_pages(),
+	 * or just got freed under us.
+	 *
+	 * In case we 'win' a race for a balloon page being freed under us and
+	 * raise its refcount preventing __free_pages() from doing its job
+	 * the put_page() at the end of this block will take care of
+	 * release this page, thus avoiding a nasty leakage.
+	 */
+	if (likely(get_page_unless_zero(page))) {
+		/*
+		 * As balloon pages are not isolated from LRU lists, concurrent
+		 * compaction threads can race against page migration functions
+		 * as well as race against the balloon driver releasing a page.
+		 *
+		 * In order to avoid having an already isolated balloon page
+		 * being (wrongly) re-isolated while it is under migration,
+		 * or to avoid attempting to isolate pages being released by
+		 * the balloon driver, lets be sure we have the page lock
+		 * before proceeding with the balloon page isolation steps.
+		 */
+		if (likely(trylock_page(page))) {
+			/*
+			 * A ballooned page, by default, has PagePrivate set.
+			 * Prevent concurrent compaction threads from isolating
+			 * an already isolated balloon page by clearing it.
+			 */
+			if (balloon_page_movable(page)) {
+				__isolate_balloon_page(page);
+				unlock_page(page);
+				return true;
+			}
+			unlock_page(page);
+		}
+		put_page(page);
+	}
+	return false;
+}
+
+/* putback_lru_page() counterpart for a ballooned page */
+void balloon_page_putback(struct page *page)
+{
+	/*
+	 * 'lock_page()' stabilizes the page and prevents races against
+	 * concurrent isolation threads attempting to re-isolate it.
+	 */
+	lock_page(page);
+
+	if (__is_movable_balloon_page(page)) {
+		__putback_balloon_page(page);
+		/* drop the extra ref count taken for page isolation */
+		put_page(page);
+	} else {
+		WARN_ON(1);
+		dump_page(page, "not movable balloon page");
+	}
+	unlock_page(page);
+}
+
+/* move_to_new_page() counterpart for a ballooned page */
+int balloon_page_migrate(struct page *newpage,
+			 struct page *page, enum migrate_mode mode)
+{
+	struct balloon_dev_info *balloon = balloon_page_device(page);
+	int rc = -EAGAIN;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+
+	if (WARN_ON(!__is_movable_balloon_page(page))) {
+		dump_page(page, "not movable balloon page");
+		return rc;
+	}
+
+	if (balloon && balloon->migratepage)
+		rc = balloon->migratepage(balloon, newpage, page, mode);
+
+	return rc;
+}
+#endif /* CONFIG_BALLOON_COMPACTION */
diff --git a/mm/bootmem.c b/mm/bootmem.c
new file mode 100644
index 0000000..3b63807
--- /dev/null
+++ b/mm/bootmem.c
@@ -0,0 +1,869 @@
+/*
+ *  bootmem - A boot-time physical memory allocator and configurator
+ *
+ *  Copyright (C) 1999 Ingo Molnar
+ *                1999 Kanoj Sarcar, SGI
+ *                2008 Johannes Weiner
+ *
+ * Access to this subsystem has to be serialized externally (which is true
+ * for the boot process anyway).
+ */
+#include <linux/init.h>
+#include <linux/pfn.h>
+#include <linux/slab.h>
+#include <linux/bootmem.h>
+#include <linux/export.h>
+#include <linux/kmemleak.h>
+#include <linux/range.h>
+#include <linux/memblock.h>
+#include <linux/bug.h>
+#include <linux/io.h>
+
+#include <asm/processor.h>
+
+#include "internal.h"
+
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+struct pglist_data __refdata contig_page_data = {
+	.bdata = &bootmem_node_data[0]
+};
+EXPORT_SYMBOL(contig_page_data);
+#endif
+
+unsigned long max_low_pfn;
+unsigned long min_low_pfn;
+unsigned long max_pfn;
+
+bootmem_data_t bootmem_node_data[MAX_NUMNODES] __initdata;
+
+static struct list_head bdata_list __initdata = LIST_HEAD_INIT(bdata_list);
+
+static int bootmem_debug;
+
+static int __init bootmem_debug_setup(char *buf)
+{
+	bootmem_debug = 1;
+	return 0;
+}
+early_param("bootmem_debug", bootmem_debug_setup);
+
+#define bdebug(fmt, args...) ({				\
+	if (unlikely(bootmem_debug))			\
+		printk(KERN_INFO			\
+			"bootmem::%s " fmt,		\
+			__func__, ## args);		\
+})
+
+static unsigned long __init bootmap_bytes(unsigned long pages)
+{
+	unsigned long bytes = DIV_ROUND_UP(pages, 8);
+
+	return ALIGN(bytes, sizeof(long));
+}
+
+/**
+ * bootmem_bootmap_pages - calculate bitmap size in pages
+ * @pages: number of pages the bitmap has to represent
+ */
+unsigned long __init bootmem_bootmap_pages(unsigned long pages)
+{
+	unsigned long bytes = bootmap_bytes(pages);
+
+	return PAGE_ALIGN(bytes) >> PAGE_SHIFT;
+}
+
+/*
+ * link bdata in order
+ */
+static void __init link_bootmem(bootmem_data_t *bdata)
+{
+	bootmem_data_t *ent;
+
+	list_for_each_entry(ent, &bdata_list, list) {
+		if (bdata->node_min_pfn < ent->node_min_pfn) {
+			list_add_tail(&bdata->list, &ent->list);
+			return;
+		}
+	}
+
+	list_add_tail(&bdata->list, &bdata_list);
+}
+
+/*
+ * Called once to set up the allocator itself.
+ */
+static unsigned long __init init_bootmem_core(bootmem_data_t *bdata,
+	unsigned long mapstart, unsigned long start, unsigned long end)
+{
+	unsigned long mapsize;
+
+	mminit_validate_memmodel_limits(&start, &end);
+	bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
+	bdata->node_min_pfn = start;
+	bdata->node_low_pfn = end;
+	link_bootmem(bdata);
+
+	/*
+	 * Initially all pages are reserved - setup_arch() has to
+	 * register free RAM areas explicitly.
+	 */
+	mapsize = bootmap_bytes(end - start);
+	memset(bdata->node_bootmem_map, 0xff, mapsize);
+
+	bdebug("nid=%td start=%lx map=%lx end=%lx mapsize=%lx\n",
+		bdata - bootmem_node_data, start, mapstart, end, mapsize);
+
+	return mapsize;
+}
+
+/**
+ * init_bootmem_node - register a node as boot memory
+ * @pgdat: node to register
+ * @freepfn: pfn where the bitmap for this node is to be placed
+ * @startpfn: first pfn on the node
+ * @endpfn: first pfn after the node
+ *
+ * Returns the number of bytes needed to hold the bitmap for this node.
+ */
+unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
+				unsigned long startpfn, unsigned long endpfn)
+{
+	return init_bootmem_core(pgdat->bdata, freepfn, startpfn, endpfn);
+}
+
+/**
+ * init_bootmem - register boot memory
+ * @start: pfn where the bitmap is to be placed
+ * @pages: number of available physical pages
+ *
+ * Returns the number of bytes needed to hold the bitmap.
+ */
+unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
+{
+	max_low_pfn = pages;
+	min_low_pfn = start;
+	return init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages);
+}
+
+/*
+ * free_bootmem_late - free bootmem pages directly to page allocator
+ * @addr: starting physical address of the range
+ * @size: size of the range in bytes
+ *
+ * This is only useful when the bootmem allocator has already been torn
+ * down, but we are still initializing the system.  Pages are given directly
+ * to the page allocator, no bootmem metadata is updated because it is gone.
+ */
+void __init free_bootmem_late(unsigned long physaddr, unsigned long size)
+{
+	unsigned long cursor, end;
+
+	kmemleak_free_part(__va(physaddr), size);
+
+	cursor = PFN_UP(physaddr);
+	end = PFN_DOWN(physaddr + size);
+
+	for (; cursor < end; cursor++) {
+		__free_pages_bootmem(pfn_to_page(cursor), cursor, 0);
+		totalram_pages++;
+	}
+}
+
+static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
+{
+	struct page *page;
+	unsigned long *map, start, end, pages, cur, count = 0;
+
+	if (!bdata->node_bootmem_map)
+		return 0;
+
+	map = bdata->node_bootmem_map;
+	start = bdata->node_min_pfn;
+	end = bdata->node_low_pfn;
+
+	bdebug("nid=%td start=%lx end=%lx\n",
+		bdata - bootmem_node_data, start, end);
+
+	while (start < end) {
+		unsigned long idx, vec;
+		unsigned shift;
+
+		idx = start - bdata->node_min_pfn;
+		shift = idx & (BITS_PER_LONG - 1);
+		/*
+		 * vec holds at most BITS_PER_LONG map bits,
+		 * bit 0 corresponds to start.
+		 */
+		vec = ~map[idx / BITS_PER_LONG];
+
+		if (shift) {
+			vec >>= shift;
+			if (end - start >= BITS_PER_LONG)
+				vec |= ~map[idx / BITS_PER_LONG + 1] <<
+					(BITS_PER_LONG - shift);
+		}
+		/*
+		 * If we have a properly aligned and fully unreserved
+		 * BITS_PER_LONG block of pages in front of us, free
+		 * it in one go.
+		 */
+		if (IS_ALIGNED(start, BITS_PER_LONG) && vec == ~0UL) {
+			int order = ilog2(BITS_PER_LONG);
+
+			__free_pages_bootmem(pfn_to_page(start), start, order);
+			count += BITS_PER_LONG;
+			start += BITS_PER_LONG;
+		} else {
+			cur = start;
+
+			start = ALIGN(start + 1, BITS_PER_LONG);
+			while (vec && cur != start) {
+				if (vec & 1) {
+					page = pfn_to_page(cur);
+					__free_pages_bootmem(page, cur, 0);
+					count++;
+				}
+				vec >>= 1;
+				++cur;
+			}
+		}
+	}
+
+	cur = bdata->node_min_pfn;
+	page = virt_to_page(bdata->node_bootmem_map);
+	pages = bdata->node_low_pfn - bdata->node_min_pfn;
+	pages = bootmem_bootmap_pages(pages);
+	count += pages;
+	while (pages--)
+		__free_pages_bootmem(page++, cur++, 0);
+	bdata->node_bootmem_map = NULL;
+
+	bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
+
+	return count;
+}
+
+static int reset_managed_pages_done __initdata;
+
+void reset_node_managed_pages(pg_data_t *pgdat)
+{
+	struct zone *z;
+
+	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
+		z->managed_pages = 0;
+}
+
+void __init reset_all_zones_managed_pages(void)
+{
+	struct pglist_data *pgdat;
+
+	if (reset_managed_pages_done)
+		return;
+
+	for_each_online_pgdat(pgdat)
+		reset_node_managed_pages(pgdat);
+
+	reset_managed_pages_done = 1;
+}
+
+/**
+ * free_all_bootmem - release free pages to the buddy allocator
+ *
+ * Returns the number of pages actually released.
+ */
+unsigned long __init free_all_bootmem(void)
+{
+	unsigned long total_pages = 0;
+	bootmem_data_t *bdata;
+
+	reset_all_zones_managed_pages();
+
+	list_for_each_entry(bdata, &bdata_list, list)
+		total_pages += free_all_bootmem_core(bdata);
+
+	totalram_pages += total_pages;
+
+	return total_pages;
+}
+
+static void __init __free(bootmem_data_t *bdata,
+			unsigned long sidx, unsigned long eidx)
+{
+	unsigned long idx;
+
+	bdebug("nid=%td start=%lx end=%lx\n", bdata - bootmem_node_data,
+		sidx + bdata->node_min_pfn,
+		eidx + bdata->node_min_pfn);
+
+	if (WARN_ON(bdata->node_bootmem_map == NULL))
+		return;
+
+	if (bdata->hint_idx > sidx)
+		bdata->hint_idx = sidx;
+
+	for (idx = sidx; idx < eidx; idx++)
+		if (!test_and_clear_bit(idx, bdata->node_bootmem_map))
+			BUG();
+}
+
+static int __init __reserve(bootmem_data_t *bdata, unsigned long sidx,
+			unsigned long eidx, int flags)
+{
+	unsigned long idx;
+	int exclusive = flags & BOOTMEM_EXCLUSIVE;
+
+	bdebug("nid=%td start=%lx end=%lx flags=%x\n",
+		bdata - bootmem_node_data,
+		sidx + bdata->node_min_pfn,
+		eidx + bdata->node_min_pfn,
+		flags);
+
+	if (WARN_ON(bdata->node_bootmem_map == NULL))
+		return 0;
+
+	for (idx = sidx; idx < eidx; idx++)
+		if (test_and_set_bit(idx, bdata->node_bootmem_map)) {
+			if (exclusive) {
+				__free(bdata, sidx, idx);
+				return -EBUSY;
+			}
+			bdebug("silent double reserve of PFN %lx\n",
+				idx + bdata->node_min_pfn);
+		}
+	return 0;
+}
+
+static int __init mark_bootmem_node(bootmem_data_t *bdata,
+				unsigned long start, unsigned long end,
+				int reserve, int flags)
+{
+	unsigned long sidx, eidx;
+
+	bdebug("nid=%td start=%lx end=%lx reserve=%d flags=%x\n",
+		bdata - bootmem_node_data, start, end, reserve, flags);
+
+	BUG_ON(start < bdata->node_min_pfn);
+	BUG_ON(end > bdata->node_low_pfn);
+
+	sidx = start - bdata->node_min_pfn;
+	eidx = end - bdata->node_min_pfn;
+
+	if (reserve)
+		return __reserve(bdata, sidx, eidx, flags);
+	else
+		__free(bdata, sidx, eidx);
+	return 0;
+}
+
+static int __init mark_bootmem(unsigned long start, unsigned long end,
+				int reserve, int flags)
+{
+	unsigned long pos;
+	bootmem_data_t *bdata;
+
+	pos = start;
+	list_for_each_entry(bdata, &bdata_list, list) {
+		int err;
+		unsigned long max;
+
+		if (pos < bdata->node_min_pfn ||
+		    pos >= bdata->node_low_pfn) {
+			BUG_ON(pos != start);
+			continue;
+		}
+
+		max = min(bdata->node_low_pfn, end);
+
+		err = mark_bootmem_node(bdata, pos, max, reserve, flags);
+		if (reserve && err) {
+			mark_bootmem(start, pos, 0, 0);
+			return err;
+		}
+
+		if (max == end)
+			return 0;
+		pos = bdata->node_low_pfn;
+	}
+	BUG();
+}
+
+/**
+ * free_bootmem_node - mark a page range as usable
+ * @pgdat: node the range resides on
+ * @physaddr: starting address of the range
+ * @size: size of the range in bytes
+ *
+ * Partial pages will be considered reserved and left as they are.
+ *
+ * The range must reside completely on the specified node.
+ */
+void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
+			      unsigned long size)
+{
+	unsigned long start, end;
+
+	kmemleak_free_part(__va(physaddr), size);
+
+	start = PFN_UP(physaddr);
+	end = PFN_DOWN(physaddr + size);
+
+	mark_bootmem_node(pgdat->bdata, start, end, 0, 0);
+}
+
+/**
+ * free_bootmem - mark a page range as usable
+ * @addr: starting physical address of the range
+ * @size: size of the range in bytes
+ *
+ * Partial pages will be considered reserved and left as they are.
+ *
+ * The range must be contiguous but may span node boundaries.
+ */
+void __init free_bootmem(unsigned long physaddr, unsigned long size)
+{
+	unsigned long start, end;
+
+	kmemleak_free_part(__va(physaddr), size);
+
+	start = PFN_UP(physaddr);
+	end = PFN_DOWN(physaddr + size);
+
+	mark_bootmem(start, end, 0, 0);
+}
+
+/**
+ * reserve_bootmem_node - mark a page range as reserved
+ * @pgdat: node the range resides on
+ * @physaddr: starting address of the range
+ * @size: size of the range in bytes
+ * @flags: reservation flags (see linux/bootmem.h)
+ *
+ * Partial pages will be reserved.
+ *
+ * The range must reside completely on the specified node.
+ */
+int __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
+				 unsigned long size, int flags)
+{
+	unsigned long start, end;
+
+	start = PFN_DOWN(physaddr);
+	end = PFN_UP(physaddr + size);
+
+	return mark_bootmem_node(pgdat->bdata, start, end, 1, flags);
+}
+
+/**
+ * reserve_bootmem - mark a page range as reserved
+ * @addr: starting address of the range
+ * @size: size of the range in bytes
+ * @flags: reservation flags (see linux/bootmem.h)
+ *
+ * Partial pages will be reserved.
+ *
+ * The range must be contiguous but may span node boundaries.
+ */
+int __init reserve_bootmem(unsigned long addr, unsigned long size,
+			    int flags)
+{
+	unsigned long start, end;
+
+	start = PFN_DOWN(addr);
+	end = PFN_UP(addr + size);
+
+	return mark_bootmem(start, end, 1, flags);
+}
+
+static unsigned long __init align_idx(struct bootmem_data *bdata,
+				      unsigned long idx, unsigned long step)
+{
+	unsigned long base = bdata->node_min_pfn;
+
+	/*
+	 * Align the index with respect to the node start so that the
+	 * combination of both satisfies the requested alignment.
+	 */
+
+	return ALIGN(base + idx, step) - base;
+}
+
+static unsigned long __init align_off(struct bootmem_data *bdata,
+				      unsigned long off, unsigned long align)
+{
+	unsigned long base = PFN_PHYS(bdata->node_min_pfn);
+
+	/* Same as align_idx for byte offsets */
+
+	return ALIGN(base + off, align) - base;
+}
+
+static void * __init alloc_bootmem_bdata(struct bootmem_data *bdata,
+					unsigned long size, unsigned long align,
+					unsigned long goal, unsigned long limit)
+{
+	unsigned long fallback = 0;
+	unsigned long min, max, start, sidx, midx, step;
+
+	bdebug("nid=%td size=%lx [%lu pages] align=%lx goal=%lx limit=%lx\n",
+		bdata - bootmem_node_data, size, PAGE_ALIGN(size) >> PAGE_SHIFT,
+		align, goal, limit);
+
+	BUG_ON(!size);
+	BUG_ON(align & (align - 1));
+	BUG_ON(limit && goal + size > limit);
+
+	if (!bdata->node_bootmem_map)
+		return NULL;
+
+	min = bdata->node_min_pfn;
+	max = bdata->node_low_pfn;
+
+	goal >>= PAGE_SHIFT;
+	limit >>= PAGE_SHIFT;
+
+	if (limit && max > limit)
+		max = limit;
+	if (max <= min)
+		return NULL;
+
+	step = max(align >> PAGE_SHIFT, 1UL);
+
+	if (goal && min < goal && goal < max)
+		start = ALIGN(goal, step);
+	else
+		start = ALIGN(min, step);
+
+	sidx = start - bdata->node_min_pfn;
+	midx = max - bdata->node_min_pfn;
+
+	if (bdata->hint_idx > sidx) {
+		/*
+		 * Handle the valid case of sidx being zero and still
+		 * catch the fallback below.
+		 */
+		fallback = sidx + 1;
+		sidx = align_idx(bdata, bdata->hint_idx, step);
+	}
+
+	while (1) {
+		int merge;
+		void *region;
+		unsigned long eidx, i, start_off, end_off;
+find_block:
+		sidx = find_next_zero_bit(bdata->node_bootmem_map, midx, sidx);
+		sidx = align_idx(bdata, sidx, step);
+		eidx = sidx + PFN_UP(size);
+
+		if (sidx >= midx || eidx > midx)
+			break;
+
+		for (i = sidx; i < eidx; i++)
+			if (test_bit(i, bdata->node_bootmem_map)) {
+				sidx = align_idx(bdata, i, step);
+				if (sidx == i)
+					sidx += step;
+				goto find_block;
+			}
+
+		if (bdata->last_end_off & (PAGE_SIZE - 1) &&
+				PFN_DOWN(bdata->last_end_off) + 1 == sidx)
+			start_off = align_off(bdata, bdata->last_end_off, align);
+		else
+			start_off = PFN_PHYS(sidx);
+
+		merge = PFN_DOWN(start_off) < sidx;
+		end_off = start_off + size;
+
+		bdata->last_end_off = end_off;
+		bdata->hint_idx = PFN_UP(end_off);
+
+		/*
+		 * Reserve the area now:
+		 */
+		if (__reserve(bdata, PFN_DOWN(start_off) + merge,
+				PFN_UP(end_off), BOOTMEM_EXCLUSIVE))
+			BUG();
+
+		region = phys_to_virt(PFN_PHYS(bdata->node_min_pfn) +
+				start_off);
+		memset(region, 0, size);
+		/*
+		 * The min_count is set to 0 so that bootmem allocated blocks
+		 * are never reported as leaks.
+		 */
+		kmemleak_alloc(region, size, 0, 0);
+		return region;
+	}
+
+	if (fallback) {
+		sidx = align_idx(bdata, fallback - 1, step);
+		fallback = 0;
+		goto find_block;
+	}
+
+	return NULL;
+}
+
+static void * __init alloc_bootmem_core(unsigned long size,
+					unsigned long align,
+					unsigned long goal,
+					unsigned long limit)
+{
+	bootmem_data_t *bdata;
+	void *region;
+
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc(size, GFP_NOWAIT);
+
+	list_for_each_entry(bdata, &bdata_list, list) {
+		if (goal && bdata->node_low_pfn <= PFN_DOWN(goal))
+			continue;
+		if (limit && bdata->node_min_pfn >= PFN_DOWN(limit))
+			break;
+
+		region = alloc_bootmem_bdata(bdata, size, align, goal, limit);
+		if (region)
+			return region;
+	}
+
+	return NULL;
+}
+
+static void * __init ___alloc_bootmem_nopanic(unsigned long size,
+					      unsigned long align,
+					      unsigned long goal,
+					      unsigned long limit)
+{
+	void *ptr;
+
+restart:
+	ptr = alloc_bootmem_core(size, align, goal, limit);
+	if (ptr)
+		return ptr;
+	if (goal) {
+		goal = 0;
+		goto restart;
+	}
+
+	return NULL;
+}
+
+/**
+ * __alloc_bootmem_nopanic - allocate boot memory without panicking
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may happen on any node in the system.
+ *
+ * Returns NULL on failure.
+ */
+void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
+					unsigned long goal)
+{
+	unsigned long limit = 0;
+
+	return ___alloc_bootmem_nopanic(size, align, goal, limit);
+}
+
+static void * __init ___alloc_bootmem(unsigned long size, unsigned long align,
+					unsigned long goal, unsigned long limit)
+{
+	void *mem = ___alloc_bootmem_nopanic(size, align, goal, limit);
+
+	if (mem)
+		return mem;
+	/*
+	 * Whoops, we cannot satisfy the allocation request.
+	 */
+	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
+	panic("Out of memory");
+	return NULL;
+}
+
+/**
+ * __alloc_bootmem - allocate boot memory
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may happen on any node in the system.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem(unsigned long size, unsigned long align,
+			      unsigned long goal)
+{
+	unsigned long limit = 0;
+
+	return ___alloc_bootmem(size, align, goal, limit);
+}
+
+void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
+				unsigned long size, unsigned long align,
+				unsigned long goal, unsigned long limit)
+{
+	void *ptr;
+
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc(size, GFP_NOWAIT);
+again:
+
+	/* do not panic in alloc_bootmem_bdata() */
+	if (limit && goal + size > limit)
+		limit = 0;
+
+	ptr = alloc_bootmem_bdata(pgdat->bdata, size, align, goal, limit);
+	if (ptr)
+		return ptr;
+
+	ptr = alloc_bootmem_core(size, align, goal, limit);
+	if (ptr)
+		return ptr;
+
+	if (goal) {
+		goal = 0;
+		goto again;
+	}
+
+	return NULL;
+}
+
+void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
+				   unsigned long align, unsigned long goal)
+{
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
+}
+
+void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
+				    unsigned long align, unsigned long goal,
+				    unsigned long limit)
+{
+	void *ptr;
+
+	ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
+	if (ptr)
+		return ptr;
+
+	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
+	panic("Out of memory");
+	return NULL;
+}
+
+/**
+ * __alloc_bootmem_node - allocate boot memory from a specific node
+ * @pgdat: node to allocate from
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may fall back to any node in the system if the specified node
+ * can not hold the requested memory.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
+				   unsigned long align, unsigned long goal)
+{
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	return  ___alloc_bootmem_node(pgdat, size, align, goal, 0);
+}
+
+void * __init __alloc_bootmem_node_high(pg_data_t *pgdat, unsigned long size,
+				   unsigned long align, unsigned long goal)
+{
+#ifdef MAX_DMA32_PFN
+	unsigned long end_pfn;
+
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	/* update goal according ...MAX_DMA32_PFN */
+	end_pfn = pgdat_end_pfn(pgdat);
+
+	if (end_pfn > MAX_DMA32_PFN + (128 >> (20 - PAGE_SHIFT)) &&
+	    (goal >> PAGE_SHIFT) < MAX_DMA32_PFN) {
+		void *ptr;
+		unsigned long new_goal;
+
+		new_goal = MAX_DMA32_PFN << PAGE_SHIFT;
+		ptr = alloc_bootmem_bdata(pgdat->bdata, size, align,
+						 new_goal, 0);
+		if (ptr)
+			return ptr;
+	}
+#endif
+
+	return __alloc_bootmem_node(pgdat, size, align, goal);
+
+}
+
+#ifndef ARCH_LOW_ADDRESS_LIMIT
+#define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
+#endif
+
+/**
+ * __alloc_bootmem_low - allocate low boot memory
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may happen on any node in the system.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
+				  unsigned long goal)
+{
+	return ___alloc_bootmem(size, align, goal, ARCH_LOW_ADDRESS_LIMIT);
+}
+
+void * __init __alloc_bootmem_low_nopanic(unsigned long size,
+					  unsigned long align,
+					  unsigned long goal)
+{
+	return ___alloc_bootmem_nopanic(size, align, goal,
+					ARCH_LOW_ADDRESS_LIMIT);
+}
+
+/**
+ * __alloc_bootmem_low_node - allocate low boot memory from a specific node
+ * @pgdat: node to allocate from
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may fall back to any node in the system if the specified node
+ * can not hold the requested memory.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
+				       unsigned long align, unsigned long goal)
+{
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	return ___alloc_bootmem_node(pgdat, size, align,
+				     goal, ARCH_LOW_ADDRESS_LIMIT);
+}
diff --git a/mm/cleancache.c b/mm/cleancache.c
new file mode 100644
index 0000000..8fc5081
--- /dev/null
+++ b/mm/cleancache.c
@@ -0,0 +1,319 @@
+/*
+ * Cleancache frontend
+ *
+ * This code provides the generic "frontend" layer to call a matching
+ * "backend" driver implementation of cleancache.  See
+ * Documentation/vm/cleancache.txt for more information.
+ *
+ * Copyright (C) 2009-2010 Oracle Corp. All rights reserved.
+ * Author: Dan Magenheimer
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/exportfs.h>
+#include <linux/mm.h>
+#include <linux/debugfs.h>
+#include <linux/cleancache.h>
+
+/*
+ * cleancache_ops is set by cleancache_register_ops to contain the pointers
+ * to the cleancache "backend" implementation functions.
+ */
+static struct cleancache_ops *cleancache_ops __read_mostly;
+
+/*
+ * Counters available via /sys/kernel/debug/cleancache (if debugfs is
+ * properly configured.  These are for information only so are not protected
+ * against increment races.
+ */
+static u64 cleancache_succ_gets;
+static u64 cleancache_failed_gets;
+static u64 cleancache_puts;
+static u64 cleancache_invalidates;
+
+static void cleancache_register_ops_sb(struct super_block *sb, void *unused)
+{
+	switch (sb->cleancache_poolid) {
+	case CLEANCACHE_NO_BACKEND:
+		__cleancache_init_fs(sb);
+		break;
+	case CLEANCACHE_NO_BACKEND_SHARED:
+		__cleancache_init_shared_fs(sb);
+		break;
+	}
+}
+
+/*
+ * Register operations for cleancache. Returns 0 on success.
+ */
+int cleancache_register_ops(struct cleancache_ops *ops)
+{
+	if (cmpxchg(&cleancache_ops, NULL, ops))
+		return -EBUSY;
+
+	/*
+	 * A cleancache backend can be built as a module and hence loaded after
+	 * a cleancache enabled filesystem has called cleancache_init_fs. To
+	 * handle such a scenario, here we call ->init_fs or ->init_shared_fs
+	 * for each active super block. To differentiate between local and
+	 * shared filesystems, we temporarily initialize sb->cleancache_poolid
+	 * to CLEANCACHE_NO_BACKEND or CLEANCACHE_NO_BACKEND_SHARED
+	 * respectively in case there is no backend registered at the time
+	 * cleancache_init_fs or cleancache_init_shared_fs is called.
+	 *
+	 * Since filesystems can be mounted concurrently with cleancache
+	 * backend registration, we have to be careful to guarantee that all
+	 * cleancache enabled filesystems that has been mounted by the time
+	 * cleancache_register_ops is called has got and all mounted later will
+	 * get cleancache_poolid. This is assured by the following statements
+	 * tied together:
+	 *
+	 * a) iterate_supers skips only those super blocks that has started
+	 *    ->kill_sb
+	 *
+	 * b) if iterate_supers encounters a super block that has not finished
+	 *    ->mount yet, it waits until it is finished
+	 *
+	 * c) cleancache_init_fs is called from ->mount and
+	 *    cleancache_invalidate_fs is called from ->kill_sb
+	 *
+	 * d) we call iterate_supers after cleancache_ops has been set
+	 *
+	 * From a) it follows that if iterate_supers skips a super block, then
+	 * either the super block is already dead, in which case we do not need
+	 * to bother initializing cleancache for it, or it was mounted after we
+	 * initiated iterate_supers. In the latter case, it must have seen
+	 * cleancache_ops set according to d) and initialized cleancache from
+	 * ->mount by itself according to c). This proves that we call
+	 * ->init_fs at least once for each active super block.
+	 *
+	 * From b) and c) it follows that if iterate_supers encounters a super
+	 * block that has already started ->init_fs, it will wait until ->mount
+	 * and hence ->init_fs has finished, then check cleancache_poolid, see
+	 * that it has already been set and therefore do nothing. This proves
+	 * that we call ->init_fs no more than once for each super block.
+	 *
+	 * Combined together, the last two paragraphs prove the function
+	 * correctness.
+	 *
+	 * Note that various cleancache callbacks may proceed before this
+	 * function is called or even concurrently with it, but since
+	 * CLEANCACHE_NO_BACKEND is negative, they will all result in a noop
+	 * until the corresponding ->init_fs has been actually called and
+	 * cleancache_ops has been set.
+	 */
+	iterate_supers(cleancache_register_ops_sb, NULL);
+	return 0;
+}
+EXPORT_SYMBOL(cleancache_register_ops);
+
+/* Called by a cleancache-enabled filesystem at time of mount */
+void __cleancache_init_fs(struct super_block *sb)
+{
+	int pool_id = CLEANCACHE_NO_BACKEND;
+
+	if (cleancache_ops) {
+		pool_id = cleancache_ops->init_fs(PAGE_SIZE);
+		if (pool_id < 0)
+			pool_id = CLEANCACHE_NO_POOL;
+	}
+	sb->cleancache_poolid = pool_id;
+}
+EXPORT_SYMBOL(__cleancache_init_fs);
+
+/* Called by a cleancache-enabled clustered filesystem at time of mount */
+void __cleancache_init_shared_fs(struct super_block *sb)
+{
+	int pool_id = CLEANCACHE_NO_BACKEND_SHARED;
+
+	if (cleancache_ops) {
+		pool_id = cleancache_ops->init_shared_fs(sb->s_uuid, PAGE_SIZE);
+		if (pool_id < 0)
+			pool_id = CLEANCACHE_NO_POOL;
+	}
+	sb->cleancache_poolid = pool_id;
+}
+EXPORT_SYMBOL(__cleancache_init_shared_fs);
+
+/*
+ * If the filesystem uses exportable filehandles, use the filehandle as
+ * the key, else use the inode number.
+ */
+static int cleancache_get_key(struct inode *inode,
+			      struct cleancache_filekey *key)
+{
+	int (*fhfn)(struct inode *, __u32 *fh, int *, struct inode *);
+	int len = 0, maxlen = CLEANCACHE_KEY_MAX;
+	struct super_block *sb = inode->i_sb;
+
+	key->u.ino = inode->i_ino;
+	if (sb->s_export_op != NULL) {
+		fhfn = sb->s_export_op->encode_fh;
+		if  (fhfn) {
+			len = (*fhfn)(inode, &key->u.fh[0], &maxlen, NULL);
+			if (len <= FILEID_ROOT || len == FILEID_INVALID)
+				return -1;
+			if (maxlen > CLEANCACHE_KEY_MAX)
+				return -1;
+		}
+	}
+	return 0;
+}
+
+/*
+ * "Get" data from cleancache associated with the poolid/inode/index
+ * that were specified when the data was put to cleanache and, if
+ * successful, use it to fill the specified page with data and return 0.
+ * The pageframe is unchanged and returns -1 if the get fails.
+ * Page must be locked by caller.
+ *
+ * The function has two checks before any action is taken - whether
+ * a backend is registered and whether the sb->cleancache_poolid
+ * is correct.
+ */
+int __cleancache_get_page(struct page *page)
+{
+	int ret = -1;
+	int pool_id;
+	struct cleancache_filekey key = { .u.key = { 0 } };
+
+	if (!cleancache_ops) {
+		cleancache_failed_gets++;
+		goto out;
+	}
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	pool_id = page->mapping->host->i_sb->cleancache_poolid;
+	if (pool_id < 0)
+		goto out;
+
+	if (cleancache_get_key(page->mapping->host, &key) < 0)
+		goto out;
+
+	ret = cleancache_ops->get_page(pool_id, key, page->index, page);
+	if (ret == 0)
+		cleancache_succ_gets++;
+	else
+		cleancache_failed_gets++;
+out:
+	return ret;
+}
+EXPORT_SYMBOL(__cleancache_get_page);
+
+/*
+ * "Put" data from a page to cleancache and associate it with the
+ * (previously-obtained per-filesystem) poolid and the page's,
+ * inode and page index.  Page must be locked.  Note that a put_page
+ * always "succeeds", though a subsequent get_page may succeed or fail.
+ *
+ * The function has two checks before any action is taken - whether
+ * a backend is registered and whether the sb->cleancache_poolid
+ * is correct.
+ */
+void __cleancache_put_page(struct page *page)
+{
+	int pool_id;
+	struct cleancache_filekey key = { .u.key = { 0 } };
+
+	if (!cleancache_ops) {
+		cleancache_puts++;
+		return;
+	}
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	pool_id = page->mapping->host->i_sb->cleancache_poolid;
+	if (pool_id >= 0 &&
+		cleancache_get_key(page->mapping->host, &key) >= 0) {
+		cleancache_ops->put_page(pool_id, key, page->index, page);
+		cleancache_puts++;
+	}
+}
+EXPORT_SYMBOL(__cleancache_put_page);
+
+/*
+ * Invalidate any data from cleancache associated with the poolid and the
+ * page's inode and page index so that a subsequent "get" will fail.
+ *
+ * The function has two checks before any action is taken - whether
+ * a backend is registered and whether the sb->cleancache_poolid
+ * is correct.
+ */
+void __cleancache_invalidate_page(struct address_space *mapping,
+					struct page *page)
+{
+	/* careful... page->mapping is NULL sometimes when this is called */
+	int pool_id = mapping->host->i_sb->cleancache_poolid;
+	struct cleancache_filekey key = { .u.key = { 0 } };
+
+	if (!cleancache_ops)
+		return;
+
+	if (pool_id >= 0) {
+		VM_BUG_ON_PAGE(!PageLocked(page), page);
+		if (cleancache_get_key(mapping->host, &key) >= 0) {
+			cleancache_ops->invalidate_page(pool_id,
+					key, page->index);
+			cleancache_invalidates++;
+		}
+	}
+}
+EXPORT_SYMBOL(__cleancache_invalidate_page);
+
+/*
+ * Invalidate all data from cleancache associated with the poolid and the
+ * mappings's inode so that all subsequent gets to this poolid/inode
+ * will fail.
+ *
+ * The function has two checks before any action is taken - whether
+ * a backend is registered and whether the sb->cleancache_poolid
+ * is correct.
+ */
+void __cleancache_invalidate_inode(struct address_space *mapping)
+{
+	int pool_id = mapping->host->i_sb->cleancache_poolid;
+	struct cleancache_filekey key = { .u.key = { 0 } };
+
+	if (!cleancache_ops)
+		return;
+
+	if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
+		cleancache_ops->invalidate_inode(pool_id, key);
+}
+EXPORT_SYMBOL(__cleancache_invalidate_inode);
+
+/*
+ * Called by any cleancache-enabled filesystem at time of unmount;
+ * note that pool_id is surrendered and may be returned by a subsequent
+ * cleancache_init_fs or cleancache_init_shared_fs.
+ */
+void __cleancache_invalidate_fs(struct super_block *sb)
+{
+	int pool_id;
+
+	pool_id = sb->cleancache_poolid;
+	sb->cleancache_poolid = CLEANCACHE_NO_POOL;
+
+	if (cleancache_ops && pool_id >= 0)
+		cleancache_ops->invalidate_fs(pool_id);
+}
+EXPORT_SYMBOL(__cleancache_invalidate_fs);
+
+static int __init init_cleancache(void)
+{
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *root = debugfs_create_dir("cleancache", NULL);
+	if (root == NULL)
+		return -ENXIO;
+	debugfs_create_u64("succ_gets", S_IRUGO, root, &cleancache_succ_gets);
+	debugfs_create_u64("failed_gets", S_IRUGO,
+				root, &cleancache_failed_gets);
+	debugfs_create_u64("puts", S_IRUGO, root, &cleancache_puts);
+	debugfs_create_u64("invalidates", S_IRUGO,
+				root, &cleancache_invalidates);
+#endif
+	return 0;
+}
+module_init(init_cleancache)
diff --git a/mm/cma.c b/mm/cma.c
new file mode 100644
index 0000000..bd0e141
--- /dev/null
+++ b/mm/cma.c
@@ -0,0 +1,461 @@
+/*
+ * Contiguous Memory Allocator
+ *
+ * Copyright (c) 2010-2011 by Samsung Electronics.
+ * Copyright IBM Corporation, 2013
+ * Copyright LG Electronics Inc., 2014
+ * Written by:
+ *	Marek Szyprowski <m.szyprowski@samsung.com>
+ *	Michal Nazarewicz <mina86@mina86.com>
+ *	Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *	Joonsoo Kim <iamjoonsoo.kim@lge.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License or (at your optional) any later version of the license.
+ */
+
+#define pr_fmt(fmt) "cma: " fmt
+
+#ifdef CONFIG_CMA_DEBUG
+#ifndef DEBUG
+#  define DEBUG
+#endif
+#endif
+#define CREATE_TRACE_POINTS
+
+#include <linux/memblock.h>
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/log2.h>
+#include <linux/cma.h>
+#include <linux/highmem.h>
+#include <linux/io.h>
+#include <trace/events/cma.h>
+
+#include "cma.h"
+
+struct cma cma_areas[MAX_CMA_AREAS];
+unsigned cma_area_count;
+static DEFINE_MUTEX(cma_mutex);
+
+phys_addr_t cma_get_base(const struct cma *cma)
+{
+	return PFN_PHYS(cma->base_pfn);
+}
+
+unsigned long cma_get_size(const struct cma *cma)
+{
+	return cma->count << PAGE_SHIFT;
+}
+
+static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
+					     int align_order)
+{
+	if (align_order <= cma->order_per_bit)
+		return 0;
+	return (1UL << (align_order - cma->order_per_bit)) - 1;
+}
+
+/*
+ * Find a PFN aligned to the specified order and return an offset represented in
+ * order_per_bits.
+ */
+static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
+					       int align_order)
+{
+	if (align_order <= cma->order_per_bit)
+		return 0;
+
+	return (ALIGN(cma->base_pfn, (1UL << align_order))
+		- cma->base_pfn) >> cma->order_per_bit;
+}
+
+static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
+					      unsigned long pages)
+{
+	return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
+}
+
+static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
+			     unsigned int count)
+{
+	unsigned long bitmap_no, bitmap_count;
+
+	bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
+	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
+
+	mutex_lock(&cma->lock);
+	bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
+	mutex_unlock(&cma->lock);
+}
+
+static int __init cma_activate_area(struct cma *cma)
+{
+	int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
+	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
+	unsigned i = cma->count >> pageblock_order;
+	struct zone *zone;
+
+	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+
+	if (!cma->bitmap)
+		return -ENOMEM;
+
+	WARN_ON_ONCE(!pfn_valid(pfn));
+	zone = page_zone(pfn_to_page(pfn));
+
+	do {
+		unsigned j;
+
+		base_pfn = pfn;
+		for (j = pageblock_nr_pages; j; --j, pfn++) {
+			WARN_ON_ONCE(!pfn_valid(pfn));
+			/*
+			 * alloc_contig_range requires the pfn range
+			 * specified to be in the same zone. Make this
+			 * simple by forcing the entire CMA resv range
+			 * to be in the same zone.
+			 */
+			if (page_zone(pfn_to_page(pfn)) != zone)
+				goto err;
+		}
+		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
+	} while (--i);
+
+	mutex_init(&cma->lock);
+
+#ifdef CONFIG_CMA_DEBUGFS
+	INIT_HLIST_HEAD(&cma->mem_head);
+	spin_lock_init(&cma->mem_head_lock);
+#endif
+
+	return 0;
+
+err:
+	kfree(cma->bitmap);
+	cma->count = 0;
+	return -EINVAL;
+}
+
+static int __init cma_init_reserved_areas(void)
+{
+	int i;
+
+	for (i = 0; i < cma_area_count; i++) {
+		int ret = cma_activate_area(&cma_areas[i]);
+
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+core_initcall(cma_init_reserved_areas);
+
+/**
+ * cma_init_reserved_mem() - create custom contiguous area from reserved memory
+ * @base: Base address of the reserved area
+ * @size: Size of the reserved area (in bytes),
+ * @order_per_bit: Order of pages represented by one bit on bitmap.
+ * @res_cma: Pointer to store the created cma region.
+ *
+ * This function creates custom contiguous area from already reserved memory.
+ */
+int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
+				 unsigned int order_per_bit,
+				 struct cma **res_cma)
+{
+	struct cma *cma;
+	phys_addr_t alignment;
+
+	/* Sanity checks */
+	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
+		pr_err("Not enough slots for CMA reserved regions!\n");
+		return -ENOSPC;
+	}
+
+	if (!size || !memblock_is_region_reserved(base, size))
+		return -EINVAL;
+
+	/* ensure minimal alignment required by mm core */
+	alignment = PAGE_SIZE <<
+			max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
+
+	/* alignment should be aligned with order_per_bit */
+	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
+		return -EINVAL;
+
+	if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
+		return -EINVAL;
+
+	/*
+	 * Each reserved area must be initialised later, when more kernel
+	 * subsystems (like slab allocator) are available.
+	 */
+	cma = &cma_areas[cma_area_count];
+	cma->base_pfn = PFN_DOWN(base);
+	cma->count = size >> PAGE_SHIFT;
+	cma->order_per_bit = order_per_bit;
+	*res_cma = cma;
+	cma_area_count++;
+	totalcma_pages += (size / PAGE_SIZE);
+
+	return 0;
+}
+
+/**
+ * cma_declare_contiguous() - reserve custom contiguous area
+ * @base: Base address of the reserved area optional, use 0 for any
+ * @size: Size of the reserved area (in bytes),
+ * @limit: End address of the reserved memory (optional, 0 for any).
+ * @alignment: Alignment for the CMA area, should be power of 2 or zero
+ * @order_per_bit: Order of pages represented by one bit on bitmap.
+ * @fixed: hint about where to place the reserved area
+ * @res_cma: Pointer to store the created cma region.
+ *
+ * This function reserves memory from early allocator. It should be
+ * called by arch specific code once the early allocator (memblock or bootmem)
+ * has been activated and all other subsystems have already allocated/reserved
+ * memory. This function allows to create custom reserved areas.
+ *
+ * If @fixed is true, reserve contiguous area at exactly @base.  If false,
+ * reserve in range from @base to @limit.
+ */
+int __init cma_declare_contiguous(phys_addr_t base,
+			phys_addr_t size, phys_addr_t limit,
+			phys_addr_t alignment, unsigned int order_per_bit,
+			bool fixed, struct cma **res_cma)
+{
+	phys_addr_t memblock_end = memblock_end_of_DRAM();
+	phys_addr_t highmem_start;
+	int ret = 0;
+
+#ifdef CONFIG_X86
+	/*
+	 * high_memory isn't direct mapped memory so retrieving its physical
+	 * address isn't appropriate.  But it would be useful to check the
+	 * physical address of the highmem boundary so it's justifiable to get
+	 * the physical address from it.  On x86 there is a validation check for
+	 * this case, so the following workaround is needed to avoid it.
+	 */
+	highmem_start = __pa_nodebug(high_memory);
+#else
+	highmem_start = __pa(high_memory);
+#endif
+	pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
+		__func__, &size, &base, &limit, &alignment);
+
+	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
+		pr_err("Not enough slots for CMA reserved regions!\n");
+		return -ENOSPC;
+	}
+
+	if (!size)
+		return -EINVAL;
+
+	if (alignment && !is_power_of_2(alignment))
+		return -EINVAL;
+
+	/*
+	 * Sanitise input arguments.
+	 * Pages both ends in CMA area could be merged into adjacent unmovable
+	 * migratetype page by page allocator's buddy algorithm. In the case,
+	 * you couldn't get a contiguous memory, which is not what we want.
+	 */
+	alignment = max(alignment,  (phys_addr_t)PAGE_SIZE <<
+			  max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
+	base = ALIGN(base, alignment);
+	size = ALIGN(size, alignment);
+	limit &= ~(alignment - 1);
+
+	if (!base)
+		fixed = false;
+
+	/* size should be aligned with order_per_bit */
+	if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
+		return -EINVAL;
+
+	/*
+	 * If allocating at a fixed base the request region must not cross the
+	 * low/high memory boundary.
+	 */
+	if (fixed && base < highmem_start && base + size > highmem_start) {
+		ret = -EINVAL;
+		pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
+			&base, &highmem_start);
+		goto err;
+	}
+
+	/*
+	 * If the limit is unspecified or above the memblock end, its effective
+	 * value will be the memblock end. Set it explicitly to simplify further
+	 * checks.
+	 */
+	if (limit == 0 || limit > memblock_end)
+		limit = memblock_end;
+
+	/* Reserve memory */
+	if (fixed) {
+		if (memblock_is_region_reserved(base, size) ||
+		    memblock_reserve(base, size) < 0) {
+			ret = -EBUSY;
+			goto err;
+		}
+	} else {
+		phys_addr_t addr = 0;
+
+		/*
+		 * All pages in the reserved area must come from the same zone.
+		 * If the requested region crosses the low/high memory boundary,
+		 * try allocating from high memory first and fall back to low
+		 * memory in case of failure.
+		 */
+		if (base < highmem_start && limit > highmem_start) {
+			addr = memblock_alloc_range(size, alignment,
+						    highmem_start, limit,
+						    MEMBLOCK_NONE);
+			limit = highmem_start;
+		}
+
+		if (!addr) {
+			addr = memblock_alloc_range(size, alignment, base,
+						    limit,
+						    MEMBLOCK_NONE);
+			if (!addr) {
+				ret = -ENOMEM;
+				goto err;
+			}
+		}
+
+		/*
+		 * kmemleak scans/reads tracked objects for pointers to other
+		 * objects but this address isn't mapped and accessible
+		 */
+		kmemleak_ignore(phys_to_virt(addr));
+		base = addr;
+	}
+
+	ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
+	if (ret)
+		goto err;
+
+	pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
+		&base);
+	return 0;
+
+err:
+	pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
+	return ret;
+}
+
+/**
+ * cma_alloc() - allocate pages from contiguous area
+ * @cma:   Contiguous memory region for which the allocation is performed.
+ * @count: Requested number of pages.
+ * @align: Requested alignment of pages (in PAGE_SIZE order).
+ *
+ * This function allocates part of contiguous memory on specific
+ * contiguous memory area.
+ */
+struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align)
+{
+	unsigned long mask, offset;
+	unsigned long pfn = -1;
+	unsigned long start = 0;
+	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
+	struct page *page = NULL;
+	int ret;
+
+	if (!cma || !cma->count)
+		return NULL;
+
+	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
+		 count, align);
+
+	if (!count)
+		return NULL;
+
+	mask = cma_bitmap_aligned_mask(cma, align);
+	offset = cma_bitmap_aligned_offset(cma, align);
+	bitmap_maxno = cma_bitmap_maxno(cma);
+	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
+
+	for (;;) {
+		mutex_lock(&cma->lock);
+		bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
+				bitmap_maxno, start, bitmap_count, mask,
+				offset);
+		if (bitmap_no >= bitmap_maxno) {
+			mutex_unlock(&cma->lock);
+			break;
+		}
+		bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
+		/*
+		 * It's safe to drop the lock here. We've marked this region for
+		 * our exclusive use. If the migration fails we will take the
+		 * lock again and unmark it.
+		 */
+		mutex_unlock(&cma->lock);
+
+		pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
+		mutex_lock(&cma_mutex);
+		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
+		mutex_unlock(&cma_mutex);
+		if (ret == 0) {
+			page = pfn_to_page(pfn);
+			break;
+		}
+
+		cma_clear_bitmap(cma, pfn, count);
+		if (ret != -EBUSY)
+			break;
+
+		pr_debug("%s(): memory range at %p is busy, retrying\n",
+			 __func__, pfn_to_page(pfn));
+		/* try again with a bit different memory target */
+		start = bitmap_no + mask + 1;
+	}
+
+	trace_cma_alloc(pfn, page, count, align);
+
+	pr_debug("%s(): returned %p\n", __func__, page);
+	return page;
+}
+
+/**
+ * cma_release() - release allocated pages
+ * @cma:   Contiguous memory region for which the allocation is performed.
+ * @pages: Allocated pages.
+ * @count: Number of allocated pages.
+ *
+ * This function releases memory allocated by alloc_cma().
+ * It returns false when provided pages do not belong to contiguous area and
+ * true otherwise.
+ */
+bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
+{
+	unsigned long pfn;
+
+	if (!cma || !pages)
+		return false;
+
+	pr_debug("%s(page %p)\n", __func__, (void *)pages);
+
+	pfn = page_to_pfn(pages);
+
+	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
+		return false;
+
+	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
+
+	free_contig_range(pfn, count);
+	cma_clear_bitmap(cma, pfn, count);
+	trace_cma_release(pfn, pages, count);
+
+	return true;
+}
diff --git a/mm/cma.h b/mm/cma.h
new file mode 100644
index 0000000..17c75a4
--- /dev/null
+++ b/mm/cma.h
@@ -0,0 +1,24 @@
+#ifndef __MM_CMA_H__
+#define __MM_CMA_H__
+
+struct cma {
+	unsigned long   base_pfn;
+	unsigned long   count;
+	unsigned long   *bitmap;
+	unsigned int order_per_bit; /* Order of pages represented by one bit */
+	struct mutex    lock;
+#ifdef CONFIG_CMA_DEBUGFS
+	struct hlist_head mem_head;
+	spinlock_t mem_head_lock;
+#endif
+};
+
+extern struct cma cma_areas[MAX_CMA_AREAS];
+extern unsigned cma_area_count;
+
+static inline unsigned long cma_bitmap_maxno(struct cma *cma)
+{
+	return cma->count >> cma->order_per_bit;
+}
+
+#endif
diff --git a/mm/cma_debug.c b/mm/cma_debug.c
new file mode 100644
index 0000000..f8e4b60
--- /dev/null
+++ b/mm/cma_debug.c
@@ -0,0 +1,206 @@
+/*
+ * CMA DebugFS Interface
+ *
+ * Copyright (c) 2015 Sasha Levin <sasha.levin@oracle.com>
+ */
+
+
+#include <linux/debugfs.h>
+#include <linux/cma.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm_types.h>
+
+#include "cma.h"
+
+struct cma_mem {
+	struct hlist_node node;
+	struct page *p;
+	unsigned long n;
+};
+
+static struct dentry *cma_debugfs_root;
+
+static int cma_debugfs_get(void *data, u64 *val)
+{
+	unsigned long *p = data;
+
+	*val = *p;
+
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");
+
+static int cma_used_get(void *data, u64 *val)
+{
+	struct cma *cma = data;
+	unsigned long used;
+
+	mutex_lock(&cma->lock);
+	/* pages counter is smaller than sizeof(int) */
+	used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
+	mutex_unlock(&cma->lock);
+	*val = (u64)used << cma->order_per_bit;
+
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(cma_used_fops, cma_used_get, NULL, "%llu\n");
+
+static int cma_maxchunk_get(void *data, u64 *val)
+{
+	struct cma *cma = data;
+	unsigned long maxchunk = 0;
+	unsigned long start, end = 0;
+	unsigned long bitmap_maxno = cma_bitmap_maxno(cma);
+
+	mutex_lock(&cma->lock);
+	for (;;) {
+		start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end);
+		if (start >= cma->count)
+			break;
+		end = find_next_bit(cma->bitmap, bitmap_maxno, start);
+		maxchunk = max(end - start, maxchunk);
+	}
+	mutex_unlock(&cma->lock);
+	*val = (u64)maxchunk << cma->order_per_bit;
+
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(cma_maxchunk_fops, cma_maxchunk_get, NULL, "%llu\n");
+
+static void cma_add_to_cma_mem_list(struct cma *cma, struct cma_mem *mem)
+{
+	spin_lock(&cma->mem_head_lock);
+	hlist_add_head(&mem->node, &cma->mem_head);
+	spin_unlock(&cma->mem_head_lock);
+}
+
+static struct cma_mem *cma_get_entry_from_list(struct cma *cma)
+{
+	struct cma_mem *mem = NULL;
+
+	spin_lock(&cma->mem_head_lock);
+	if (!hlist_empty(&cma->mem_head)) {
+		mem = hlist_entry(cma->mem_head.first, struct cma_mem, node);
+		hlist_del_init(&mem->node);
+	}
+	spin_unlock(&cma->mem_head_lock);
+
+	return mem;
+}
+
+static int cma_free_mem(struct cma *cma, int count)
+{
+	struct cma_mem *mem = NULL;
+
+	while (count) {
+		mem = cma_get_entry_from_list(cma);
+		if (mem == NULL)
+			return 0;
+
+		if (mem->n <= count) {
+			cma_release(cma, mem->p, mem->n);
+			count -= mem->n;
+			kfree(mem);
+		} else if (cma->order_per_bit == 0) {
+			cma_release(cma, mem->p, count);
+			mem->p += count;
+			mem->n -= count;
+			count = 0;
+			cma_add_to_cma_mem_list(cma, mem);
+		} else {
+			pr_debug("cma: cannot release partial block when order_per_bit != 0\n");
+			cma_add_to_cma_mem_list(cma, mem);
+			break;
+		}
+	}
+
+	return 0;
+
+}
+
+static int cma_free_write(void *data, u64 val)
+{
+	int pages = val;
+	struct cma *cma = data;
+
+	return cma_free_mem(cma, pages);
+}
+DEFINE_SIMPLE_ATTRIBUTE(cma_free_fops, NULL, cma_free_write, "%llu\n");
+
+static int cma_alloc_mem(struct cma *cma, int count)
+{
+	struct cma_mem *mem;
+	struct page *p;
+
+	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+	if (!mem)
+		return -ENOMEM;
+
+	p = cma_alloc(cma, count, 0);
+	if (!p) {
+		kfree(mem);
+		return -ENOMEM;
+	}
+
+	mem->p = p;
+	mem->n = count;
+
+	cma_add_to_cma_mem_list(cma, mem);
+
+	return 0;
+}
+
+static int cma_alloc_write(void *data, u64 val)
+{
+	int pages = val;
+	struct cma *cma = data;
+
+	return cma_alloc_mem(cma, pages);
+}
+DEFINE_SIMPLE_ATTRIBUTE(cma_alloc_fops, NULL, cma_alloc_write, "%llu\n");
+
+static void cma_debugfs_add_one(struct cma *cma, int idx)
+{
+	struct dentry *tmp;
+	char name[16];
+	int u32s;
+
+	sprintf(name, "cma-%d", idx);
+
+	tmp = debugfs_create_dir(name, cma_debugfs_root);
+
+	debugfs_create_file("alloc", S_IWUSR, tmp, cma,
+				&cma_alloc_fops);
+
+	debugfs_create_file("free", S_IWUSR, tmp, cma,
+				&cma_free_fops);
+
+	debugfs_create_file("base_pfn", S_IRUGO, tmp,
+				&cma->base_pfn, &cma_debugfs_fops);
+	debugfs_create_file("count", S_IRUGO, tmp,
+				&cma->count, &cma_debugfs_fops);
+	debugfs_create_file("order_per_bit", S_IRUGO, tmp,
+				&cma->order_per_bit, &cma_debugfs_fops);
+	debugfs_create_file("used", S_IRUGO, tmp, cma, &cma_used_fops);
+	debugfs_create_file("maxchunk", S_IRUGO, tmp, cma, &cma_maxchunk_fops);
+
+	u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
+	debugfs_create_u32_array("bitmap", S_IRUGO, tmp, (u32*)cma->bitmap, u32s);
+}
+
+static int __init cma_debugfs_init(void)
+{
+	int i;
+
+	cma_debugfs_root = debugfs_create_dir("cma", NULL);
+	if (!cma_debugfs_root)
+		return -ENOMEM;
+
+	for (i = 0; i < cma_area_count; i++)
+		cma_debugfs_add_one(&cma_areas[i], i);
+
+	return 0;
+}
+late_initcall(cma_debugfs_init);
diff --git a/mm/compaction.c b/mm/compaction.c
new file mode 100644
index 0000000..dba02de
--- /dev/null
+++ b/mm/compaction.c
@@ -0,0 +1,1745 @@
+/*
+ * linux/mm/compaction.c
+ *
+ * Memory compaction for the reduction of external fragmentation. Note that
+ * this heavily depends upon page migration to do all the real heavy
+ * lifting
+ *
+ * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
+ */
+#include <linux/swap.h>
+#include <linux/migrate.h>
+#include <linux/compaction.h>
+#include <linux/mm_inline.h>
+#include <linux/backing-dev.h>
+#include <linux/sysctl.h>
+#include <linux/sysfs.h>
+#include <linux/balloon_compaction.h>
+#include <linux/page-isolation.h>
+#include <linux/kasan.h>
+#include "internal.h"
+
+#ifdef CONFIG_COMPACTION
+static inline void count_compact_event(enum vm_event_item item)
+{
+	count_vm_event(item);
+}
+
+static inline void count_compact_events(enum vm_event_item item, long delta)
+{
+	count_vm_events(item, delta);
+}
+#else
+#define count_compact_event(item) do { } while (0)
+#define count_compact_events(item, delta) do { } while (0)
+#endif
+
+#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/compaction.h>
+
+static unsigned long release_freepages(struct list_head *freelist)
+{
+	struct page *page, *next;
+	unsigned long high_pfn = 0;
+
+	list_for_each_entry_safe(page, next, freelist, lru) {
+		unsigned long pfn = page_to_pfn(page);
+		list_del(&page->lru);
+		__free_page(page);
+		if (pfn > high_pfn)
+			high_pfn = pfn;
+	}
+
+	return high_pfn;
+}
+
+static void map_pages(struct list_head *list)
+{
+	struct page *page;
+
+	list_for_each_entry(page, list, lru) {
+		arch_alloc_page(page, 0);
+		kernel_map_pages(page, 1, 1);
+		kasan_alloc_pages(page, 0);
+	}
+}
+
+static inline bool migrate_async_suitable(int migratetype)
+{
+	return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
+}
+
+/*
+ * Check that the whole (or subset of) a pageblock given by the interval of
+ * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
+ * with the migration of free compaction scanner. The scanners then need to
+ * use only pfn_valid_within() check for arches that allow holes within
+ * pageblocks.
+ *
+ * Return struct page pointer of start_pfn, or NULL if checks were not passed.
+ *
+ * It's possible on some configurations to have a setup like node0 node1 node0
+ * i.e. it's possible that all pages within a zones range of pages do not
+ * belong to a single zone. We assume that a border between node0 and node1
+ * can occur within a single pageblock, but not a node0 node1 node0
+ * interleaving within a single pageblock. It is therefore sufficient to check
+ * the first and last page of a pageblock and avoid checking each individual
+ * page in a pageblock.
+ */
+static struct page *pageblock_pfn_to_page(unsigned long start_pfn,
+				unsigned long end_pfn, struct zone *zone)
+{
+	struct page *start_page;
+	struct page *end_page;
+
+	/* end_pfn is one past the range we are checking */
+	end_pfn--;
+
+	if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
+		return NULL;
+
+	start_page = pfn_to_page(start_pfn);
+
+	if (page_zone(start_page) != zone)
+		return NULL;
+
+	end_page = pfn_to_page(end_pfn);
+
+	/* This gives a shorter code than deriving page_zone(end_page) */
+	if (page_zone_id(start_page) != page_zone_id(end_page))
+		return NULL;
+
+	return start_page;
+}
+
+#ifdef CONFIG_COMPACTION
+
+/* Do not skip compaction more than 64 times */
+#define COMPACT_MAX_DEFER_SHIFT 6
+
+/*
+ * Compaction is deferred when compaction fails to result in a page
+ * allocation success. 1 << compact_defer_limit compactions are skipped up
+ * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
+ */
+void defer_compaction(struct zone *zone, int order)
+{
+	zone->compact_considered = 0;
+	zone->compact_defer_shift++;
+
+	if (order < zone->compact_order_failed)
+		zone->compact_order_failed = order;
+
+	if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
+		zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
+
+	trace_mm_compaction_defer_compaction(zone, order);
+}
+
+/* Returns true if compaction should be skipped this time */
+bool compaction_deferred(struct zone *zone, int order)
+{
+	unsigned long defer_limit = 1UL << zone->compact_defer_shift;
+
+	if (order < zone->compact_order_failed)
+		return false;
+
+	/* Avoid possible overflow */
+	if (++zone->compact_considered > defer_limit)
+		zone->compact_considered = defer_limit;
+
+	if (zone->compact_considered >= defer_limit)
+		return false;
+
+	trace_mm_compaction_deferred(zone, order);
+
+	return true;
+}
+
+/*
+ * Update defer tracking counters after successful compaction of given order,
+ * which means an allocation either succeeded (alloc_success == true) or is
+ * expected to succeed.
+ */
+void compaction_defer_reset(struct zone *zone, int order,
+		bool alloc_success)
+{
+	if (alloc_success) {
+		zone->compact_considered = 0;
+		zone->compact_defer_shift = 0;
+	}
+	if (order >= zone->compact_order_failed)
+		zone->compact_order_failed = order + 1;
+
+	trace_mm_compaction_defer_reset(zone, order);
+}
+
+/* Returns true if restarting compaction after many failures */
+bool compaction_restarting(struct zone *zone, int order)
+{
+	if (order < zone->compact_order_failed)
+		return false;
+
+	return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
+		zone->compact_considered >= 1UL << zone->compact_defer_shift;
+}
+
+/* Returns true if the pageblock should be scanned for pages to isolate. */
+static inline bool isolation_suitable(struct compact_control *cc,
+					struct page *page)
+{
+	if (cc->ignore_skip_hint)
+		return true;
+
+	return !get_pageblock_skip(page);
+}
+
+static void reset_cached_positions(struct zone *zone)
+{
+	zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
+	zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
+	zone->compact_cached_free_pfn = zone_end_pfn(zone);
+}
+
+/*
+ * This function is called to clear all cached information on pageblocks that
+ * should be skipped for page isolation when the migrate and free page scanner
+ * meet.
+ */
+static void __reset_isolation_suitable(struct zone *zone)
+{
+	unsigned long start_pfn = zone->zone_start_pfn;
+	unsigned long end_pfn = zone_end_pfn(zone);
+	unsigned long pfn;
+
+	zone->compact_blockskip_flush = false;
+
+	/* Walk the zone and mark every pageblock as suitable for isolation */
+	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+		struct page *page;
+
+		cond_resched();
+
+		if (!pfn_valid(pfn))
+			continue;
+
+		page = pfn_to_page(pfn);
+		if (zone != page_zone(page))
+			continue;
+
+		clear_pageblock_skip(page);
+	}
+
+	reset_cached_positions(zone);
+}
+
+void reset_isolation_suitable(pg_data_t *pgdat)
+{
+	int zoneid;
+
+	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+		struct zone *zone = &pgdat->node_zones[zoneid];
+		if (!populated_zone(zone))
+			continue;
+
+		/* Only flush if a full compaction finished recently */
+		if (zone->compact_blockskip_flush)
+			__reset_isolation_suitable(zone);
+	}
+}
+
+/*
+ * If no pages were isolated then mark this pageblock to be skipped in the
+ * future. The information is later cleared by __reset_isolation_suitable().
+ */
+static void update_pageblock_skip(struct compact_control *cc,
+			struct page *page, unsigned long nr_isolated,
+			bool migrate_scanner)
+{
+	struct zone *zone = cc->zone;
+	unsigned long pfn;
+
+	if (cc->ignore_skip_hint)
+		return;
+
+	if (!page)
+		return;
+
+	if (nr_isolated)
+		return;
+
+	set_pageblock_skip(page);
+
+	pfn = page_to_pfn(page);
+
+	/* Update where async and sync compaction should restart */
+	if (migrate_scanner) {
+		if (pfn > zone->compact_cached_migrate_pfn[0])
+			zone->compact_cached_migrate_pfn[0] = pfn;
+		if (cc->mode != MIGRATE_ASYNC &&
+		    pfn > zone->compact_cached_migrate_pfn[1])
+			zone->compact_cached_migrate_pfn[1] = pfn;
+	} else {
+		if (pfn < zone->compact_cached_free_pfn)
+			zone->compact_cached_free_pfn = pfn;
+	}
+}
+#else
+static inline bool isolation_suitable(struct compact_control *cc,
+					struct page *page)
+{
+	return true;
+}
+
+static void update_pageblock_skip(struct compact_control *cc,
+			struct page *page, unsigned long nr_isolated,
+			bool migrate_scanner)
+{
+}
+#endif /* CONFIG_COMPACTION */
+
+/*
+ * Compaction requires the taking of some coarse locks that are potentially
+ * very heavily contended. For async compaction, back out if the lock cannot
+ * be taken immediately. For sync compaction, spin on the lock if needed.
+ *
+ * Returns true if the lock is held
+ * Returns false if the lock is not held and compaction should abort
+ */
+static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags,
+						struct compact_control *cc)
+{
+	if (cc->mode == MIGRATE_ASYNC) {
+		if (!spin_trylock_irqsave(lock, *flags)) {
+			cc->contended = COMPACT_CONTENDED_LOCK;
+			return false;
+		}
+	} else {
+		spin_lock_irqsave(lock, *flags);
+	}
+
+	return true;
+}
+
+/*
+ * Compaction requires the taking of some coarse locks that are potentially
+ * very heavily contended. The lock should be periodically unlocked to avoid
+ * having disabled IRQs for a long time, even when there is nobody waiting on
+ * the lock. It might also be that allowing the IRQs will result in
+ * need_resched() becoming true. If scheduling is needed, async compaction
+ * aborts. Sync compaction schedules.
+ * Either compaction type will also abort if a fatal signal is pending.
+ * In either case if the lock was locked, it is dropped and not regained.
+ *
+ * Returns true if compaction should abort due to fatal signal pending, or
+ *		async compaction due to need_resched()
+ * Returns false when compaction can continue (sync compaction might have
+ *		scheduled)
+ */
+static bool compact_unlock_should_abort(spinlock_t *lock,
+		unsigned long flags, bool *locked, struct compact_control *cc)
+{
+	if (*locked) {
+		spin_unlock_irqrestore(lock, flags);
+		*locked = false;
+	}
+
+	if (fatal_signal_pending(current)) {
+		cc->contended = COMPACT_CONTENDED_SCHED;
+		return true;
+	}
+
+	if (need_resched()) {
+		if (cc->mode == MIGRATE_ASYNC) {
+			cc->contended = COMPACT_CONTENDED_SCHED;
+			return true;
+		}
+		cond_resched();
+	}
+
+	return false;
+}
+
+/*
+ * Aside from avoiding lock contention, compaction also periodically checks
+ * need_resched() and either schedules in sync compaction or aborts async
+ * compaction. This is similar to what compact_unlock_should_abort() does, but
+ * is used where no lock is concerned.
+ *
+ * Returns false when no scheduling was needed, or sync compaction scheduled.
+ * Returns true when async compaction should abort.
+ */
+static inline bool compact_should_abort(struct compact_control *cc)
+{
+	/* async compaction aborts if contended */
+	if (need_resched()) {
+		if (cc->mode == MIGRATE_ASYNC) {
+			cc->contended = COMPACT_CONTENDED_SCHED;
+			return true;
+		}
+
+		cond_resched();
+	}
+
+	return false;
+}
+
+/*
+ * Isolate free pages onto a private freelist. If @strict is true, will abort
+ * returning 0 on any invalid PFNs or non-free pages inside of the pageblock
+ * (even though it may still end up isolating some pages).
+ */
+static unsigned long isolate_freepages_block(struct compact_control *cc,
+				unsigned long *start_pfn,
+				unsigned long end_pfn,
+				struct list_head *freelist,
+				bool strict)
+{
+	int nr_scanned = 0, total_isolated = 0;
+	struct page *cursor, *valid_page = NULL;
+	unsigned long flags = 0;
+	bool locked = false;
+	unsigned long blockpfn = *start_pfn;
+
+	cursor = pfn_to_page(blockpfn);
+
+	/* Isolate free pages. */
+	for (; blockpfn < end_pfn; blockpfn++, cursor++) {
+		int isolated, i;
+		struct page *page = cursor;
+
+		/*
+		 * Periodically drop the lock (if held) regardless of its
+		 * contention, to give chance to IRQs. Abort if fatal signal
+		 * pending or async compaction detects need_resched()
+		 */
+		if (!(blockpfn % SWAP_CLUSTER_MAX)
+		    && compact_unlock_should_abort(&cc->zone->lock, flags,
+								&locked, cc))
+			break;
+
+		nr_scanned++;
+		if (!pfn_valid_within(blockpfn))
+			goto isolate_fail;
+
+		if (!valid_page)
+			valid_page = page;
+
+		/*
+		 * For compound pages such as THP and hugetlbfs, we can save
+		 * potentially a lot of iterations if we skip them at once.
+		 * The check is racy, but we can consider only valid values
+		 * and the only danger is skipping too much.
+		 */
+		if (PageCompound(page)) {
+			unsigned int comp_order = compound_order(page);
+
+			if (likely(comp_order < MAX_ORDER)) {
+				blockpfn += (1UL << comp_order) - 1;
+				cursor += (1UL << comp_order) - 1;
+			}
+
+			goto isolate_fail;
+		}
+
+		if (!PageBuddy(page))
+			goto isolate_fail;
+
+		/*
+		 * If we already hold the lock, we can skip some rechecking.
+		 * Note that if we hold the lock now, checked_pageblock was
+		 * already set in some previous iteration (or strict is true),
+		 * so it is correct to skip the suitable migration target
+		 * recheck as well.
+		 */
+		if (!locked) {
+			/*
+			 * The zone lock must be held to isolate freepages.
+			 * Unfortunately this is a very coarse lock and can be
+			 * heavily contended if there are parallel allocations
+			 * or parallel compactions. For async compaction do not
+			 * spin on the lock and we acquire the lock as late as
+			 * possible.
+			 */
+			locked = compact_trylock_irqsave(&cc->zone->lock,
+								&flags, cc);
+			if (!locked)
+				break;
+
+			/* Recheck this is a buddy page under lock */
+			if (!PageBuddy(page))
+				goto isolate_fail;
+		}
+
+		/* Found a free page, break it into order-0 pages */
+		isolated = split_free_page(page);
+		if (!isolated)
+			break;
+
+		total_isolated += isolated;
+		cc->nr_freepages += isolated;
+		for (i = 0; i < isolated; i++) {
+			list_add(&page->lru, freelist);
+			page++;
+		}
+		if (!strict && cc->nr_migratepages <= cc->nr_freepages) {
+			blockpfn += isolated;
+			break;
+		}
+		/* Advance to the end of split page */
+		blockpfn += isolated - 1;
+		cursor += isolated - 1;
+		continue;
+
+isolate_fail:
+		if (strict)
+			break;
+		else
+			continue;
+
+	}
+
+	if (locked)
+		spin_unlock_irqrestore(&cc->zone->lock, flags);
+
+	/*
+	 * There is a tiny chance that we have read bogus compound_order(),
+	 * so be careful to not go outside of the pageblock.
+	 */
+	if (unlikely(blockpfn > end_pfn))
+		blockpfn = end_pfn;
+
+	trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn,
+					nr_scanned, total_isolated);
+
+	/* Record how far we have got within the block */
+	*start_pfn = blockpfn;
+
+	/*
+	 * If strict isolation is requested by CMA then check that all the
+	 * pages requested were isolated. If there were any failures, 0 is
+	 * returned and CMA will fail.
+	 */
+	if (strict && blockpfn < end_pfn)
+		total_isolated = 0;
+
+	/* Update the pageblock-skip if the whole pageblock was scanned */
+	if (blockpfn == end_pfn)
+		update_pageblock_skip(cc, valid_page, total_isolated, false);
+
+	count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
+	if (total_isolated)
+		count_compact_events(COMPACTISOLATED, total_isolated);
+	return total_isolated;
+}
+
+/**
+ * isolate_freepages_range() - isolate free pages.
+ * @start_pfn: The first PFN to start isolating.
+ * @end_pfn:   The one-past-last PFN.
+ *
+ * Non-free pages, invalid PFNs, or zone boundaries within the
+ * [start_pfn, end_pfn) range are considered errors, cause function to
+ * undo its actions and return zero.
+ *
+ * Otherwise, function returns one-past-the-last PFN of isolated page
+ * (which may be greater then end_pfn if end fell in a middle of
+ * a free page).
+ */
+unsigned long
+isolate_freepages_range(struct compact_control *cc,
+			unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long isolated, pfn, block_end_pfn;
+	LIST_HEAD(freelist);
+
+	pfn = start_pfn;
+	block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+
+	for (; pfn < end_pfn; pfn += isolated,
+				block_end_pfn += pageblock_nr_pages) {
+		/* Protect pfn from changing by isolate_freepages_block */
+		unsigned long isolate_start_pfn = pfn;
+
+		block_end_pfn = min(block_end_pfn, end_pfn);
+
+		/*
+		 * pfn could pass the block_end_pfn if isolated freepage
+		 * is more than pageblock order. In this case, we adjust
+		 * scanning range to right one.
+		 */
+		if (pfn >= block_end_pfn) {
+			block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+			block_end_pfn = min(block_end_pfn, end_pfn);
+		}
+
+		if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
+			break;
+
+		isolated = isolate_freepages_block(cc, &isolate_start_pfn,
+						block_end_pfn, &freelist, true);
+
+		/*
+		 * In strict mode, isolate_freepages_block() returns 0 if
+		 * there are any holes in the block (ie. invalid PFNs or
+		 * non-free pages).
+		 */
+		if (!isolated)
+			break;
+
+		/*
+		 * If we managed to isolate pages, it is always (1 << n) *
+		 * pageblock_nr_pages for some non-negative n.  (Max order
+		 * page may span two pageblocks).
+		 */
+	}
+
+	/* split_free_page does not map the pages */
+	map_pages(&freelist);
+
+	if (pfn < end_pfn) {
+		/* Loop terminated early, cleanup. */
+		release_freepages(&freelist);
+		return 0;
+	}
+
+	/* We don't use freelists for anything. */
+	return pfn;
+}
+
+/* Update the number of anon and file isolated pages in the zone */
+static void acct_isolated(struct zone *zone, struct compact_control *cc)
+{
+	struct page *page;
+	unsigned int count[2] = { 0, };
+
+	if (list_empty(&cc->migratepages))
+		return;
+
+	list_for_each_entry(page, &cc->migratepages, lru)
+		count[!!page_is_file_cache(page)]++;
+
+	mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
+	mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
+}
+
+/* Similar to reclaim, but different enough that they don't share logic */
+static bool too_many_isolated(struct zone *zone)
+{
+	unsigned long active, inactive, isolated;
+
+	inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
+					zone_page_state(zone, NR_INACTIVE_ANON);
+	active = zone_page_state(zone, NR_ACTIVE_FILE) +
+					zone_page_state(zone, NR_ACTIVE_ANON);
+	isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
+					zone_page_state(zone, NR_ISOLATED_ANON);
+
+	return isolated > (inactive + active) / 2;
+}
+
+/**
+ * isolate_migratepages_block() - isolate all migrate-able pages within
+ *				  a single pageblock
+ * @cc:		Compaction control structure.
+ * @low_pfn:	The first PFN to isolate
+ * @end_pfn:	The one-past-the-last PFN to isolate, within same pageblock
+ * @isolate_mode: Isolation mode to be used.
+ *
+ * Isolate all pages that can be migrated from the range specified by
+ * [low_pfn, end_pfn). The range is expected to be within same pageblock.
+ * Returns zero if there is a fatal signal pending, otherwise PFN of the
+ * first page that was not scanned (which may be both less, equal to or more
+ * than end_pfn).
+ *
+ * The pages are isolated on cc->migratepages list (not required to be empty),
+ * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
+ * is neither read nor updated.
+ */
+static unsigned long
+isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
+			unsigned long end_pfn, isolate_mode_t isolate_mode)
+{
+	struct zone *zone = cc->zone;
+	unsigned long nr_scanned = 0, nr_isolated = 0;
+	struct list_head *migratelist = &cc->migratepages;
+	struct lruvec *lruvec;
+	unsigned long flags = 0;
+	bool locked = false;
+	struct page *page = NULL, *valid_page = NULL;
+	unsigned long start_pfn = low_pfn;
+
+	/*
+	 * Ensure that there are not too many pages isolated from the LRU
+	 * list by either parallel reclaimers or compaction. If there are,
+	 * delay for some time until fewer pages are isolated
+	 */
+	while (unlikely(too_many_isolated(zone))) {
+		/* async migration should just abort */
+		if (cc->mode == MIGRATE_ASYNC)
+			return 0;
+
+		congestion_wait(BLK_RW_ASYNC, HZ/10);
+
+		if (fatal_signal_pending(current))
+			return 0;
+	}
+
+	if (compact_should_abort(cc))
+		return 0;
+
+	/* Time to isolate some pages for migration */
+	for (; low_pfn < end_pfn; low_pfn++) {
+		bool is_lru;
+
+		/*
+		 * Periodically drop the lock (if held) regardless of its
+		 * contention, to give chance to IRQs. Abort async compaction
+		 * if contended.
+		 */
+		if (!(low_pfn % SWAP_CLUSTER_MAX)
+		    && compact_unlock_should_abort(&zone->lru_lock, flags,
+								&locked, cc))
+			break;
+
+		if (!pfn_valid_within(low_pfn))
+			continue;
+		nr_scanned++;
+
+		page = pfn_to_page(low_pfn);
+
+		if (!valid_page)
+			valid_page = page;
+
+		/*
+		 * Skip if free. We read page order here without zone lock
+		 * which is generally unsafe, but the race window is small and
+		 * the worst thing that can happen is that we skip some
+		 * potential isolation targets.
+		 */
+		if (PageBuddy(page)) {
+			unsigned long freepage_order = page_order_unsafe(page);
+
+			/*
+			 * Without lock, we cannot be sure that what we got is
+			 * a valid page order. Consider only values in the
+			 * valid order range to prevent low_pfn overflow.
+			 */
+			if (freepage_order > 0 && freepage_order < MAX_ORDER)
+				low_pfn += (1UL << freepage_order) - 1;
+			continue;
+		}
+
+		/*
+		 * Check may be lockless but that's ok as we recheck later.
+		 * It's possible to migrate LRU pages and balloon pages
+		 * Skip any other type of page
+		 */
+		is_lru = PageLRU(page);
+		if (!is_lru) {
+			if (unlikely(balloon_page_movable(page))) {
+				if (balloon_page_isolate(page)) {
+					/* Successfully isolated */
+					goto isolate_success;
+				}
+			}
+		}
+
+		/*
+		 * Regardless of being on LRU, compound pages such as THP and
+		 * hugetlbfs are not to be compacted. We can potentially save
+		 * a lot of iterations if we skip them at once. The check is
+		 * racy, but we can consider only valid values and the only
+		 * danger is skipping too much.
+		 */
+		if (PageCompound(page)) {
+			unsigned int comp_order = compound_order(page);
+
+			if (likely(comp_order < MAX_ORDER))
+				low_pfn += (1UL << comp_order) - 1;
+
+			continue;
+		}
+
+		if (!is_lru)
+			continue;
+
+		/*
+		 * Migration will fail if an anonymous page is pinned in memory,
+		 * so avoid taking lru_lock and isolating it unnecessarily in an
+		 * admittedly racy check.
+		 */
+		if (!page_mapping(page) &&
+		    page_count(page) > page_mapcount(page))
+			continue;
+
+		/* If we already hold the lock, we can skip some rechecking */
+		if (!locked) {
+			locked = compact_trylock_irqsave(&zone->lru_lock,
+								&flags, cc);
+			if (!locked)
+				break;
+
+			/* Recheck PageLRU and PageCompound under lock */
+			if (!PageLRU(page))
+				continue;
+
+			/*
+			 * Page become compound since the non-locked check,
+			 * and it's on LRU. It can only be a THP so the order
+			 * is safe to read and it's 0 for tail pages.
+			 */
+			if (unlikely(PageCompound(page))) {
+				low_pfn += (1UL << compound_order(page)) - 1;
+				continue;
+			}
+		}
+
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+
+		/* Try isolate the page */
+		if (__isolate_lru_page(page, isolate_mode) != 0)
+			continue;
+
+		VM_BUG_ON_PAGE(PageCompound(page), page);
+
+		/* Successfully isolated */
+		del_page_from_lru_list(page, lruvec, page_lru(page));
+
+isolate_success:
+		list_add(&page->lru, migratelist);
+		cc->nr_migratepages++;
+		nr_isolated++;
+
+		/* Avoid isolating too much */
+		if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
+			++low_pfn;
+			break;
+		}
+	}
+
+	/*
+	 * The PageBuddy() check could have potentially brought us outside
+	 * the range to be scanned.
+	 */
+	if (unlikely(low_pfn > end_pfn))
+		low_pfn = end_pfn;
+
+	if (locked)
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+
+	/*
+	 * Update the pageblock-skip information and cached scanner pfn,
+	 * if the whole pageblock was scanned without isolating any page.
+	 */
+	if (low_pfn == end_pfn)
+		update_pageblock_skip(cc, valid_page, nr_isolated, true);
+
+	trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
+						nr_scanned, nr_isolated);
+
+	count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
+	if (nr_isolated)
+		count_compact_events(COMPACTISOLATED, nr_isolated);
+
+	return low_pfn;
+}
+
+/**
+ * isolate_migratepages_range() - isolate migrate-able pages in a PFN range
+ * @cc:        Compaction control structure.
+ * @start_pfn: The first PFN to start isolating.
+ * @end_pfn:   The one-past-last PFN.
+ *
+ * Returns zero if isolation fails fatally due to e.g. pending signal.
+ * Otherwise, function returns one-past-the-last PFN of isolated page
+ * (which may be greater than end_pfn if end fell in a middle of a THP page).
+ */
+unsigned long
+isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
+							unsigned long end_pfn)
+{
+	unsigned long pfn, block_end_pfn;
+
+	/* Scan block by block. First and last block may be incomplete */
+	pfn = start_pfn;
+	block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+
+	for (; pfn < end_pfn; pfn = block_end_pfn,
+				block_end_pfn += pageblock_nr_pages) {
+
+		block_end_pfn = min(block_end_pfn, end_pfn);
+
+		if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
+			continue;
+
+		pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
+							ISOLATE_UNEVICTABLE);
+
+		if (!pfn)
+			break;
+
+		if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
+			break;
+	}
+	acct_isolated(cc->zone, cc);
+
+	return pfn;
+}
+
+#endif /* CONFIG_COMPACTION || CONFIG_CMA */
+#ifdef CONFIG_COMPACTION
+
+/* Returns true if the page is within a block suitable for migration to */
+static bool suitable_migration_target(struct page *page)
+{
+	/* If the page is a large free page, then disallow migration */
+	if (PageBuddy(page)) {
+		/*
+		 * We are checking page_order without zone->lock taken. But
+		 * the only small danger is that we skip a potentially suitable
+		 * pageblock, so it's not worth to check order for valid range.
+		 */
+		if (page_order_unsafe(page) >= pageblock_order)
+			return false;
+	}
+
+	/* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
+	if (migrate_async_suitable(get_pageblock_migratetype(page)))
+		return true;
+
+	/* Otherwise skip the block */
+	return false;
+}
+
+/*
+ * Test whether the free scanner has reached the same or lower pageblock than
+ * the migration scanner, and compaction should thus terminate.
+ */
+static inline bool compact_scanners_met(struct compact_control *cc)
+{
+	return (cc->free_pfn >> pageblock_order)
+		<= (cc->migrate_pfn >> pageblock_order);
+}
+
+/*
+ * Based on information in the current compact_control, find blocks
+ * suitable for isolating free pages from and then isolate them.
+ */
+static void isolate_freepages(struct compact_control *cc)
+{
+	struct zone *zone = cc->zone;
+	struct page *page;
+	unsigned long block_start_pfn;	/* start of current pageblock */
+	unsigned long isolate_start_pfn; /* exact pfn we start at */
+	unsigned long block_end_pfn;	/* end of current pageblock */
+	unsigned long low_pfn;	     /* lowest pfn scanner is able to scan */
+	struct list_head *freelist = &cc->freepages;
+
+	/*
+	 * Initialise the free scanner. The starting point is where we last
+	 * successfully isolated from, zone-cached value, or the end of the
+	 * zone when isolating for the first time. For looping we also need
+	 * this pfn aligned down to the pageblock boundary, because we do
+	 * block_start_pfn -= pageblock_nr_pages in the for loop.
+	 * For ending point, take care when isolating in last pageblock of a
+	 * a zone which ends in the middle of a pageblock.
+	 * The low boundary is the end of the pageblock the migration scanner
+	 * is using.
+	 */
+	isolate_start_pfn = cc->free_pfn;
+	block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
+	block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
+						zone_end_pfn(zone));
+	low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
+
+	/*
+	 * Isolate free pages until enough are available to migrate the
+	 * pages on cc->migratepages. We stop searching if the migrate
+	 * and free page scanners meet or enough free pages are isolated.
+	 */
+	for (; block_start_pfn >= low_pfn;
+				block_end_pfn = block_start_pfn,
+				block_start_pfn -= pageblock_nr_pages,
+				isolate_start_pfn = block_start_pfn) {
+		/*
+		 * This can iterate a massively long zone without finding any
+		 * suitable migration targets, so periodically check if we need
+		 * to schedule, or even abort async compaction.
+		 */
+		if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
+						&& compact_should_abort(cc))
+			break;
+
+		page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
+									zone);
+		if (!page)
+			continue;
+
+		/* Check the block is suitable for migration */
+		if (!suitable_migration_target(page))
+			continue;
+
+		/* If isolation recently failed, do not retry */
+		if (!isolation_suitable(cc, page))
+			continue;
+
+		/* Found a block suitable for isolating free pages from. */
+		isolate_freepages_block(cc, &isolate_start_pfn, block_end_pfn,
+					freelist, false);
+
+		/*
+		 * If we isolated enough freepages, or aborted due to lock
+		 * contention, terminate.
+		 */
+		if ((cc->nr_freepages >= cc->nr_migratepages)
+							|| cc->contended) {
+			if (isolate_start_pfn >= block_end_pfn) {
+				/*
+				 * Restart at previous pageblock if more
+				 * freepages can be isolated next time.
+				 */
+				isolate_start_pfn =
+					block_start_pfn - pageblock_nr_pages;
+			}
+			break;
+		} else if (isolate_start_pfn < block_end_pfn) {
+			/*
+			 * If isolation failed early, do not continue
+			 * needlessly.
+			 */
+			break;
+		}
+	}
+
+	/* split_free_page does not map the pages */
+	map_pages(freelist);
+
+	/*
+	 * Record where the free scanner will restart next time. Either we
+	 * broke from the loop and set isolate_start_pfn based on the last
+	 * call to isolate_freepages_block(), or we met the migration scanner
+	 * and the loop terminated due to isolate_start_pfn < low_pfn
+	 */
+	cc->free_pfn = isolate_start_pfn;
+}
+
+/*
+ * This is a migrate-callback that "allocates" freepages by taking pages
+ * from the isolated freelists in the block we are migrating to.
+ */
+static struct page *compaction_alloc(struct page *migratepage,
+					unsigned long data,
+					int **result)
+{
+	struct compact_control *cc = (struct compact_control *)data;
+	struct page *freepage;
+
+	/*
+	 * Isolate free pages if necessary, and if we are not aborting due to
+	 * contention.
+	 */
+	if (list_empty(&cc->freepages)) {
+		if (!cc->contended)
+			isolate_freepages(cc);
+
+		if (list_empty(&cc->freepages))
+			return NULL;
+	}
+
+	freepage = list_entry(cc->freepages.next, struct page, lru);
+	list_del(&freepage->lru);
+	cc->nr_freepages--;
+
+	return freepage;
+}
+
+/*
+ * This is a migrate-callback that "frees" freepages back to the isolated
+ * freelist.  All pages on the freelist are from the same zone, so there is no
+ * special handling needed for NUMA.
+ */
+static void compaction_free(struct page *page, unsigned long data)
+{
+	struct compact_control *cc = (struct compact_control *)data;
+
+	list_add(&page->lru, &cc->freepages);
+	cc->nr_freepages++;
+}
+
+/* possible outcome of isolate_migratepages */
+typedef enum {
+	ISOLATE_ABORT,		/* Abort compaction now */
+	ISOLATE_NONE,		/* No pages isolated, continue scanning */
+	ISOLATE_SUCCESS,	/* Pages isolated, migrate */
+} isolate_migrate_t;
+
+/*
+ * Allow userspace to control policy on scanning the unevictable LRU for
+ * compactable pages.
+ */
+int sysctl_compact_unevictable_allowed __read_mostly = 1;
+
+/*
+ * Isolate all pages that can be migrated from the first suitable block,
+ * starting at the block pointed to by the migrate scanner pfn within
+ * compact_control.
+ */
+static isolate_migrate_t isolate_migratepages(struct zone *zone,
+					struct compact_control *cc)
+{
+	unsigned long low_pfn, end_pfn;
+	unsigned long isolate_start_pfn;
+	struct page *page;
+	const isolate_mode_t isolate_mode =
+		(sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
+		(cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
+
+	/*
+	 * Start at where we last stopped, or beginning of the zone as
+	 * initialized by compact_zone()
+	 */
+	low_pfn = cc->migrate_pfn;
+
+	/* Only scan within a pageblock boundary */
+	end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
+
+	/*
+	 * Iterate over whole pageblocks until we find the first suitable.
+	 * Do not cross the free scanner.
+	 */
+	for (; end_pfn <= cc->free_pfn;
+			low_pfn = end_pfn, end_pfn += pageblock_nr_pages) {
+
+		/*
+		 * This can potentially iterate a massively long zone with
+		 * many pageblocks unsuitable, so periodically check if we
+		 * need to schedule, or even abort async compaction.
+		 */
+		if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
+						&& compact_should_abort(cc))
+			break;
+
+		page = pageblock_pfn_to_page(low_pfn, end_pfn, zone);
+		if (!page)
+			continue;
+
+		/* If isolation recently failed, do not retry */
+		if (!isolation_suitable(cc, page))
+			continue;
+
+		/*
+		 * For async compaction, also only scan in MOVABLE blocks.
+		 * Async compaction is optimistic to see if the minimum amount
+		 * of work satisfies the allocation.
+		 */
+		if (cc->mode == MIGRATE_ASYNC &&
+		    !migrate_async_suitable(get_pageblock_migratetype(page)))
+			continue;
+
+		/* Perform the isolation */
+		isolate_start_pfn = low_pfn;
+		low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
+								isolate_mode);
+
+		if (!low_pfn || cc->contended) {
+			acct_isolated(zone, cc);
+			return ISOLATE_ABORT;
+		}
+
+		/*
+		 * Record where we could have freed pages by migration and not
+		 * yet flushed them to buddy allocator.
+		 * - this is the lowest page that could have been isolated and
+		 * then freed by migration.
+		 */
+		if (cc->nr_migratepages && !cc->last_migrated_pfn)
+			cc->last_migrated_pfn = isolate_start_pfn;
+
+		/*
+		 * Either we isolated something and proceed with migration. Or
+		 * we failed and compact_zone should decide if we should
+		 * continue or not.
+		 */
+		break;
+	}
+
+	acct_isolated(zone, cc);
+	/* Record where migration scanner will be restarted. */
+	cc->migrate_pfn = low_pfn;
+
+	return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
+}
+
+/*
+ * order == -1 is expected when compacting via
+ * /proc/sys/vm/compact_memory
+ */
+static inline bool is_via_compact_memory(int order)
+{
+	return order == -1;
+}
+
+static int __compact_finished(struct zone *zone, struct compact_control *cc,
+			    const int migratetype)
+{
+	unsigned int order;
+	unsigned long watermark;
+
+	if (cc->contended || fatal_signal_pending(current))
+		return COMPACT_CONTENDED;
+
+	/* Compaction run completes if the migrate and free scanner meet */
+	if (compact_scanners_met(cc)) {
+		/* Let the next compaction start anew. */
+		reset_cached_positions(zone);
+
+		/*
+		 * Mark that the PG_migrate_skip information should be cleared
+		 * by kswapd when it goes to sleep. kswapd does not set the
+		 * flag itself as the decision to be clear should be directly
+		 * based on an allocation request.
+		 */
+		if (!current_is_kswapd())
+			zone->compact_blockskip_flush = true;
+
+		return COMPACT_COMPLETE;
+	}
+
+	if (is_via_compact_memory(cc->order))
+		return COMPACT_CONTINUE;
+
+	/* Compaction run is not finished if the watermark is not met */
+	watermark = low_wmark_pages(zone);
+
+	if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
+							cc->alloc_flags))
+		return COMPACT_CONTINUE;
+
+	/* Direct compactor: Is a suitable page free? */
+	for (order = cc->order; order < MAX_ORDER; order++) {
+		struct free_area *area = &zone->free_area[order];
+		bool can_steal;
+
+		/* Job done if page is free of the right migratetype */
+		if (!list_empty(&area->free_list[migratetype]))
+			return COMPACT_PARTIAL;
+
+#ifdef CONFIG_CMA
+		/* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
+		if (migratetype == MIGRATE_MOVABLE &&
+			!list_empty(&area->free_list[MIGRATE_CMA]))
+			return COMPACT_PARTIAL;
+#endif
+		/*
+		 * Job done if allocation would steal freepages from
+		 * other migratetype buddy lists.
+		 */
+		if (find_suitable_fallback(area, order, migratetype,
+						true, &can_steal) != -1)
+			return COMPACT_PARTIAL;
+	}
+
+	return COMPACT_NO_SUITABLE_PAGE;
+}
+
+static int compact_finished(struct zone *zone, struct compact_control *cc,
+			    const int migratetype)
+{
+	int ret;
+
+	ret = __compact_finished(zone, cc, migratetype);
+	trace_mm_compaction_finished(zone, cc->order, ret);
+	if (ret == COMPACT_NO_SUITABLE_PAGE)
+		ret = COMPACT_CONTINUE;
+
+	return ret;
+}
+
+/*
+ * compaction_suitable: Is this suitable to run compaction on this zone now?
+ * Returns
+ *   COMPACT_SKIPPED  - If there are too few free pages for compaction
+ *   COMPACT_PARTIAL  - If the allocation would succeed without compaction
+ *   COMPACT_CONTINUE - If compaction should run now
+ */
+static unsigned long __compaction_suitable(struct zone *zone, int order,
+					int alloc_flags, int classzone_idx)
+{
+	int fragindex;
+	unsigned long watermark;
+
+	if (is_via_compact_memory(order))
+		return COMPACT_CONTINUE;
+
+	watermark = low_wmark_pages(zone);
+	/*
+	 * If watermarks for high-order allocation are already met, there
+	 * should be no need for compaction at all.
+	 */
+	if (zone_watermark_ok(zone, order, watermark, classzone_idx,
+								alloc_flags))
+		return COMPACT_PARTIAL;
+
+	/*
+	 * Watermarks for order-0 must be met for compaction. Note the 2UL.
+	 * This is because during migration, copies of pages need to be
+	 * allocated and for a short time, the footprint is higher
+	 */
+	watermark += (2UL << order);
+	if (!zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags))
+		return COMPACT_SKIPPED;
+
+	/*
+	 * fragmentation index determines if allocation failures are due to
+	 * low memory or external fragmentation
+	 *
+	 * index of -1000 would imply allocations might succeed depending on
+	 * watermarks, but we already failed the high-order watermark check
+	 * index towards 0 implies failure is due to lack of memory
+	 * index towards 1000 implies failure is due to fragmentation
+	 *
+	 * Only compact if a failure would be due to fragmentation.
+	 */
+	fragindex = fragmentation_index(zone, order);
+	if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
+		return COMPACT_NOT_SUITABLE_ZONE;
+
+	return COMPACT_CONTINUE;
+}
+
+unsigned long compaction_suitable(struct zone *zone, int order,
+					int alloc_flags, int classzone_idx)
+{
+	unsigned long ret;
+
+	ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
+	trace_mm_compaction_suitable(zone, order, ret);
+	if (ret == COMPACT_NOT_SUITABLE_ZONE)
+		ret = COMPACT_SKIPPED;
+
+	return ret;
+}
+
+static int compact_zone(struct zone *zone, struct compact_control *cc)
+{
+	int ret;
+	unsigned long start_pfn = zone->zone_start_pfn;
+	unsigned long end_pfn = zone_end_pfn(zone);
+	const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
+	const bool sync = cc->mode != MIGRATE_ASYNC;
+
+	ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
+							cc->classzone_idx);
+	switch (ret) {
+	case COMPACT_PARTIAL:
+	case COMPACT_SKIPPED:
+		/* Compaction is likely to fail */
+		return ret;
+	case COMPACT_CONTINUE:
+		/* Fall through to compaction */
+		;
+	}
+
+	/*
+	 * Clear pageblock skip if there were failures recently and compaction
+	 * is about to be retried after being deferred. kswapd does not do
+	 * this reset as it'll reset the cached information when going to sleep.
+	 */
+	if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
+		__reset_isolation_suitable(zone);
+
+	/*
+	 * Setup to move all movable pages to the end of the zone. Used cached
+	 * information on where the scanners should start but check that it
+	 * is initialised by ensuring the values are within zone boundaries.
+	 */
+	cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
+	cc->free_pfn = zone->compact_cached_free_pfn;
+	if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
+		cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
+		zone->compact_cached_free_pfn = cc->free_pfn;
+	}
+	if (cc->migrate_pfn < start_pfn || cc->migrate_pfn > end_pfn) {
+		cc->migrate_pfn = start_pfn;
+		zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
+		zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
+	}
+	cc->last_migrated_pfn = 0;
+
+	trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
+				cc->free_pfn, end_pfn, sync);
+
+	migrate_prep_local();
+
+	while ((ret = compact_finished(zone, cc, migratetype)) ==
+						COMPACT_CONTINUE) {
+		int err;
+
+		switch (isolate_migratepages(zone, cc)) {
+		case ISOLATE_ABORT:
+			ret = COMPACT_CONTENDED;
+			putback_movable_pages(&cc->migratepages);
+			cc->nr_migratepages = 0;
+			goto out;
+		case ISOLATE_NONE:
+			/*
+			 * We haven't isolated and migrated anything, but
+			 * there might still be unflushed migrations from
+			 * previous cc->order aligned block.
+			 */
+			goto check_drain;
+		case ISOLATE_SUCCESS:
+			;
+		}
+
+		err = migrate_pages(&cc->migratepages, compaction_alloc,
+				compaction_free, (unsigned long)cc, cc->mode,
+				MR_COMPACTION);
+
+		trace_mm_compaction_migratepages(cc->nr_migratepages, err,
+							&cc->migratepages);
+
+		/* All pages were either migrated or will be released */
+		cc->nr_migratepages = 0;
+		if (err) {
+			putback_movable_pages(&cc->migratepages);
+			/*
+			 * migrate_pages() may return -ENOMEM when scanners meet
+			 * and we want compact_finished() to detect it
+			 */
+			if (err == -ENOMEM && !compact_scanners_met(cc)) {
+				ret = COMPACT_CONTENDED;
+				goto out;
+			}
+		}
+
+check_drain:
+		/*
+		 * Has the migration scanner moved away from the previous
+		 * cc->order aligned block where we migrated from? If yes,
+		 * flush the pages that were freed, so that they can merge and
+		 * compact_finished() can detect immediately if allocation
+		 * would succeed.
+		 */
+		if (cc->order > 0 && cc->last_migrated_pfn) {
+			int cpu;
+			unsigned long current_block_start =
+				cc->migrate_pfn & ~((1UL << cc->order) - 1);
+
+			if (cc->last_migrated_pfn < current_block_start) {
+				cpu = get_cpu();
+				lru_add_drain_cpu(cpu);
+				drain_local_pages(zone);
+				put_cpu();
+				/* No more flushing until we migrate again */
+				cc->last_migrated_pfn = 0;
+			}
+		}
+
+	}
+
+out:
+	/*
+	 * Release free pages and update where the free scanner should restart,
+	 * so we don't leave any returned pages behind in the next attempt.
+	 */
+	if (cc->nr_freepages > 0) {
+		unsigned long free_pfn = release_freepages(&cc->freepages);
+
+		cc->nr_freepages = 0;
+		VM_BUG_ON(free_pfn == 0);
+		/* The cached pfn is always the first in a pageblock */
+		free_pfn &= ~(pageblock_nr_pages-1);
+		/*
+		 * Only go back, not forward. The cached pfn might have been
+		 * already reset to zone end in compact_finished()
+		 */
+		if (free_pfn > zone->compact_cached_free_pfn)
+			zone->compact_cached_free_pfn = free_pfn;
+	}
+
+	trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
+				cc->free_pfn, end_pfn, sync, ret);
+
+	if (ret == COMPACT_CONTENDED)
+		ret = COMPACT_PARTIAL;
+
+	return ret;
+}
+
+static unsigned long compact_zone_order(struct zone *zone, int order,
+		gfp_t gfp_mask, enum migrate_mode mode, int *contended,
+		int alloc_flags, int classzone_idx)
+{
+	unsigned long ret;
+	struct compact_control cc = {
+		.nr_freepages = 0,
+		.nr_migratepages = 0,
+		.order = order,
+		.gfp_mask = gfp_mask,
+		.zone = zone,
+		.mode = mode,
+		.alloc_flags = alloc_flags,
+		.classzone_idx = classzone_idx,
+	};
+	INIT_LIST_HEAD(&cc.freepages);
+	INIT_LIST_HEAD(&cc.migratepages);
+
+	ret = compact_zone(zone, &cc);
+
+	VM_BUG_ON(!list_empty(&cc.freepages));
+	VM_BUG_ON(!list_empty(&cc.migratepages));
+
+	*contended = cc.contended;
+	return ret;
+}
+
+int sysctl_extfrag_threshold = 500;
+
+/**
+ * try_to_compact_pages - Direct compact to satisfy a high-order allocation
+ * @gfp_mask: The GFP mask of the current allocation
+ * @order: The order of the current allocation
+ * @alloc_flags: The allocation flags of the current allocation
+ * @ac: The context of current allocation
+ * @mode: The migration mode for async, sync light, or sync migration
+ * @contended: Return value that determines if compaction was aborted due to
+ *	       need_resched() or lock contention
+ *
+ * This is the main entry point for direct page compaction.
+ */
+unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
+			int alloc_flags, const struct alloc_context *ac,
+			enum migrate_mode mode, int *contended)
+{
+	int may_enter_fs = gfp_mask & __GFP_FS;
+	int may_perform_io = gfp_mask & __GFP_IO;
+	struct zoneref *z;
+	struct zone *zone;
+	int rc = COMPACT_DEFERRED;
+	int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
+
+	*contended = COMPACT_CONTENDED_NONE;
+
+	/* Check if the GFP flags allow compaction */
+	if (!order || !may_enter_fs || !may_perform_io)
+		return COMPACT_SKIPPED;
+
+	trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
+
+	/* Compact each zone in the list */
+	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
+								ac->nodemask) {
+		int status;
+		int zone_contended;
+
+		if (compaction_deferred(zone, order))
+			continue;
+
+		status = compact_zone_order(zone, order, gfp_mask, mode,
+				&zone_contended, alloc_flags,
+				ac->classzone_idx);
+		rc = max(status, rc);
+		/*
+		 * It takes at least one zone that wasn't lock contended
+		 * to clear all_zones_contended.
+		 */
+		all_zones_contended &= zone_contended;
+
+		/* If a normal allocation would succeed, stop compacting */
+		if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
+					ac->classzone_idx, alloc_flags)) {
+			/*
+			 * We think the allocation will succeed in this zone,
+			 * but it is not certain, hence the false. The caller
+			 * will repeat this with true if allocation indeed
+			 * succeeds in this zone.
+			 */
+			compaction_defer_reset(zone, order, false);
+			/*
+			 * It is possible that async compaction aborted due to
+			 * need_resched() and the watermarks were ok thanks to
+			 * somebody else freeing memory. The allocation can
+			 * however still fail so we better signal the
+			 * need_resched() contention anyway (this will not
+			 * prevent the allocation attempt).
+			 */
+			if (zone_contended == COMPACT_CONTENDED_SCHED)
+				*contended = COMPACT_CONTENDED_SCHED;
+
+			goto break_loop;
+		}
+
+		if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
+			/*
+			 * We think that allocation won't succeed in this zone
+			 * so we defer compaction there. If it ends up
+			 * succeeding after all, it will be reset.
+			 */
+			defer_compaction(zone, order);
+		}
+
+		/*
+		 * We might have stopped compacting due to need_resched() in
+		 * async compaction, or due to a fatal signal detected. In that
+		 * case do not try further zones and signal need_resched()
+		 * contention.
+		 */
+		if ((zone_contended == COMPACT_CONTENDED_SCHED)
+					|| fatal_signal_pending(current)) {
+			*contended = COMPACT_CONTENDED_SCHED;
+			goto break_loop;
+		}
+
+		continue;
+break_loop:
+		/*
+		 * We might not have tried all the zones, so  be conservative
+		 * and assume they are not all lock contended.
+		 */
+		all_zones_contended = 0;
+		break;
+	}
+
+	/*
+	 * If at least one zone wasn't deferred or skipped, we report if all
+	 * zones that were tried were lock contended.
+	 */
+	if (rc > COMPACT_SKIPPED && all_zones_contended)
+		*contended = COMPACT_CONTENDED_LOCK;
+
+	return rc;
+}
+
+
+/* Compact all zones within a node */
+static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
+{
+	int zoneid;
+	struct zone *zone;
+
+	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+
+		zone = &pgdat->node_zones[zoneid];
+		if (!populated_zone(zone))
+			continue;
+
+		cc->nr_freepages = 0;
+		cc->nr_migratepages = 0;
+		cc->zone = zone;
+		INIT_LIST_HEAD(&cc->freepages);
+		INIT_LIST_HEAD(&cc->migratepages);
+
+		/*
+		 * When called via /proc/sys/vm/compact_memory
+		 * this makes sure we compact the whole zone regardless of
+		 * cached scanner positions.
+		 */
+		if (is_via_compact_memory(cc->order))
+			__reset_isolation_suitable(zone);
+
+		if (is_via_compact_memory(cc->order) ||
+				!compaction_deferred(zone, cc->order))
+			compact_zone(zone, cc);
+
+		if (cc->order > 0) {
+			if (zone_watermark_ok(zone, cc->order,
+						low_wmark_pages(zone), 0, 0))
+				compaction_defer_reset(zone, cc->order, false);
+		}
+
+		VM_BUG_ON(!list_empty(&cc->freepages));
+		VM_BUG_ON(!list_empty(&cc->migratepages));
+	}
+}
+
+void compact_pgdat(pg_data_t *pgdat, int order)
+{
+	struct compact_control cc = {
+		.order = order,
+		.mode = MIGRATE_ASYNC,
+	};
+
+	if (!order)
+		return;
+
+	__compact_pgdat(pgdat, &cc);
+}
+
+static void compact_node(int nid)
+{
+	struct compact_control cc = {
+		.order = -1,
+		.mode = MIGRATE_SYNC,
+		.ignore_skip_hint = true,
+	};
+
+	__compact_pgdat(NODE_DATA(nid), &cc);
+}
+
+/* Compact all nodes in the system */
+static void compact_nodes(void)
+{
+	int nid;
+
+	/* Flush pending updates to the LRU lists */
+	lru_add_drain_all();
+
+	for_each_online_node(nid)
+		compact_node(nid);
+}
+
+/* The written value is actually unused, all memory is compacted */
+int sysctl_compact_memory;
+
+/* This is the entry point for compacting all nodes via /proc/sys/vm */
+int sysctl_compaction_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos)
+{
+	if (write)
+		compact_nodes();
+
+	return 0;
+}
+
+int sysctl_extfrag_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos)
+{
+	proc_dointvec_minmax(table, write, buffer, length, ppos);
+
+	return 0;
+}
+
+#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
+static ssize_t sysfs_compact_node(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	int nid = dev->id;
+
+	if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
+		/* Flush pending updates to the LRU lists */
+		lru_add_drain_all();
+
+		compact_node(nid);
+	}
+
+	return count;
+}
+static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
+
+int compaction_register_node(struct node *node)
+{
+	return device_create_file(&node->dev, &dev_attr_compact);
+}
+
+void compaction_unregister_node(struct node *node)
+{
+	return device_remove_file(&node->dev, &dev_attr_compact);
+}
+#endif /* CONFIG_SYSFS && CONFIG_NUMA */
+
+#endif /* CONFIG_COMPACTION */
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
new file mode 100644
index 0000000..5bf5906
--- /dev/null
+++ b/mm/debug-pagealloc.c
@@ -0,0 +1,137 @@
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/page_ext.h>
+#include <linux/poison.h>
+#include <linux/ratelimit.h>
+
+static bool page_poisoning_enabled __read_mostly;
+
+static bool need_page_poisoning(void)
+{
+	if (!debug_pagealloc_enabled())
+		return false;
+
+	return true;
+}
+
+static void init_page_poisoning(void)
+{
+	if (!debug_pagealloc_enabled())
+		return;
+
+	page_poisoning_enabled = true;
+}
+
+struct page_ext_operations page_poisoning_ops = {
+	.need = need_page_poisoning,
+	.init = init_page_poisoning,
+};
+
+static inline void set_page_poison(struct page *page)
+{
+	struct page_ext *page_ext;
+
+	page_ext = lookup_page_ext(page);
+	__set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+}
+
+static inline void clear_page_poison(struct page *page)
+{
+	struct page_ext *page_ext;
+
+	page_ext = lookup_page_ext(page);
+	__clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+}
+
+static inline bool page_poison(struct page *page)
+{
+	struct page_ext *page_ext;
+
+	page_ext = lookup_page_ext(page);
+	return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+}
+
+static void poison_page(struct page *page)
+{
+	void *addr = kmap_atomic(page);
+
+	set_page_poison(page);
+	memset(addr, PAGE_POISON, PAGE_SIZE);
+	kunmap_atomic(addr);
+}
+
+static void poison_pages(struct page *page, int n)
+{
+	int i;
+
+	for (i = 0; i < n; i++)
+		poison_page(page + i);
+}
+
+static bool single_bit_flip(unsigned char a, unsigned char b)
+{
+	unsigned char error = a ^ b;
+
+	return error && !(error & (error - 1));
+}
+
+static void check_poison_mem(unsigned char *mem, size_t bytes)
+{
+	static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
+	unsigned char *start;
+	unsigned char *end;
+
+	start = memchr_inv(mem, PAGE_POISON, bytes);
+	if (!start)
+		return;
+
+	for (end = mem + bytes - 1; end > start; end--) {
+		if (*end != PAGE_POISON)
+			break;
+	}
+
+	if (!__ratelimit(&ratelimit))
+		return;
+	else if (start == end && single_bit_flip(*start, PAGE_POISON))
+		printk(KERN_ERR "pagealloc: single bit error\n");
+	else
+		printk(KERN_ERR "pagealloc: memory corruption\n");
+
+	print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
+			end - start + 1, 1);
+	dump_stack();
+}
+
+static void unpoison_page(struct page *page)
+{
+	void *addr;
+
+	if (!page_poison(page))
+		return;
+
+	addr = kmap_atomic(page);
+	check_poison_mem(addr, PAGE_SIZE);
+	clear_page_poison(page);
+	kunmap_atomic(addr);
+}
+
+static void unpoison_pages(struct page *page, int n)
+{
+	int i;
+
+	for (i = 0; i < n; i++)
+		unpoison_page(page + i);
+}
+
+void __kernel_map_pages(struct page *page, int numpages, int enable)
+{
+	if (!page_poisoning_enabled)
+		return;
+
+	if (enable)
+		unpoison_pages(page, numpages);
+	else
+		poison_pages(page, numpages);
+}
diff --git a/mm/debug.c b/mm/debug.c
new file mode 100644
index 0000000..668aa35
--- /dev/null
+++ b/mm/debug.c
@@ -0,0 +1,240 @@
+/*
+ * mm/debug.c
+ *
+ * mm/ specific debug routines.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/trace_events.h>
+#include <linux/memcontrol.h>
+
+static const struct trace_print_flags pageflag_names[] = {
+	{1UL << PG_locked,		"locked"	},
+	{1UL << PG_error,		"error"		},
+	{1UL << PG_referenced,		"referenced"	},
+	{1UL << PG_uptodate,		"uptodate"	},
+	{1UL << PG_dirty,		"dirty"		},
+	{1UL << PG_lru,			"lru"		},
+	{1UL << PG_active,		"active"	},
+	{1UL << PG_slab,		"slab"		},
+	{1UL << PG_owner_priv_1,	"owner_priv_1"	},
+	{1UL << PG_arch_1,		"arch_1"	},
+	{1UL << PG_reserved,		"reserved"	},
+	{1UL << PG_private,		"private"	},
+	{1UL << PG_private_2,		"private_2"	},
+	{1UL << PG_writeback,		"writeback"	},
+	{1UL << PG_head,		"head"		},
+	{1UL << PG_swapcache,		"swapcache"	},
+	{1UL << PG_mappedtodisk,	"mappedtodisk"	},
+	{1UL << PG_reclaim,		"reclaim"	},
+	{1UL << PG_swapbacked,		"swapbacked"	},
+	{1UL << PG_unevictable,		"unevictable"	},
+#ifdef CONFIG_MMU
+	{1UL << PG_mlocked,		"mlocked"	},
+#endif
+#ifdef CONFIG_ARCH_USES_PG_UNCACHED
+	{1UL << PG_uncached,		"uncached"	},
+#endif
+#ifdef CONFIG_MEMORY_FAILURE
+	{1UL << PG_hwpoison,		"hwpoison"	},
+#endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	{1UL << PG_compound_lock,	"compound_lock"	},
+#endif
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+	{1UL << PG_young,		"young"		},
+	{1UL << PG_idle,		"idle"		},
+#endif
+};
+
+static void dump_flags(unsigned long flags,
+			const struct trace_print_flags *names, int count)
+{
+	const char *delim = "";
+	unsigned long mask;
+	int i;
+
+	pr_emerg("flags: %#lx(", flags);
+
+	/* remove zone id */
+	flags &= (1UL << NR_PAGEFLAGS) - 1;
+
+	for (i = 0; i < count && flags; i++) {
+
+		mask = names[i].mask;
+		if ((flags & mask) != mask)
+			continue;
+
+		flags &= ~mask;
+		pr_cont("%s%s", delim, names[i].name);
+		delim = "|";
+	}
+
+	/* check for left over flags */
+	if (flags)
+		pr_cont("%s%#lx", delim, flags);
+
+	pr_cont(")\n");
+}
+
+void dump_page_badflags(struct page *page, const char *reason,
+		unsigned long badflags)
+{
+	pr_emerg("page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
+		  page, atomic_read(&page->_count), page_mapcount(page),
+		  page->mapping, page->index);
+	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
+	dump_flags(page->flags, pageflag_names, ARRAY_SIZE(pageflag_names));
+	if (reason)
+		pr_alert("page dumped because: %s\n", reason);
+	if (page->flags & badflags) {
+		pr_alert("bad because of flags:\n");
+		dump_flags(page->flags & badflags,
+				pageflag_names, ARRAY_SIZE(pageflag_names));
+	}
+#ifdef CONFIG_MEMCG
+	if (page->mem_cgroup)
+		pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
+#endif
+}
+
+void dump_page(struct page *page, const char *reason)
+{
+	dump_page_badflags(page, reason, 0);
+}
+EXPORT_SYMBOL(dump_page);
+
+#ifdef CONFIG_DEBUG_VM
+
+static const struct trace_print_flags vmaflags_names[] = {
+	{VM_READ,			"read"		},
+	{VM_WRITE,			"write"		},
+	{VM_EXEC,			"exec"		},
+	{VM_SHARED,			"shared"	},
+	{VM_MAYREAD,			"mayread"	},
+	{VM_MAYWRITE,			"maywrite"	},
+	{VM_MAYEXEC,			"mayexec"	},
+	{VM_MAYSHARE,			"mayshare"	},
+	{VM_GROWSDOWN,			"growsdown"	},
+	{VM_PFNMAP,			"pfnmap"	},
+	{VM_DENYWRITE,			"denywrite"	},
+	{VM_LOCKONFAULT,		"lockonfault"	},
+	{VM_LOCKED,			"locked"	},
+	{VM_IO,				"io"		},
+	{VM_SEQ_READ,			"seqread"	},
+	{VM_RAND_READ,			"randread"	},
+	{VM_DONTCOPY,			"dontcopy"	},
+	{VM_DONTEXPAND,			"dontexpand"	},
+	{VM_ACCOUNT,			"account"	},
+	{VM_NORESERVE,			"noreserve"	},
+	{VM_HUGETLB,			"hugetlb"	},
+#if defined(CONFIG_X86)
+	{VM_PAT,			"pat"		},
+#elif defined(CONFIG_PPC)
+	{VM_SAO,			"sao"		},
+#elif defined(CONFIG_PARISC) || defined(CONFIG_METAG) || defined(CONFIG_IA64)
+	{VM_GROWSUP,			"growsup"	},
+#elif !defined(CONFIG_MMU)
+	{VM_MAPPED_COPY,		"mappedcopy"	},
+#else
+	{VM_ARCH_1,			"arch_1"	},
+#endif
+	{VM_DONTDUMP,			"dontdump"	},
+#ifdef CONFIG_MEM_SOFT_DIRTY
+	{VM_SOFTDIRTY,			"softdirty"	},
+#endif
+	{VM_MIXEDMAP,			"mixedmap"	},
+	{VM_HUGEPAGE,			"hugepage"	},
+	{VM_NOHUGEPAGE,			"nohugepage"	},
+	{VM_MERGEABLE,			"mergeable"	},
+};
+
+void dump_vma(const struct vm_area_struct *vma)
+{
+	pr_emerg("vma %p start %p end %p\n"
+		"next %p prev %p mm %p\n"
+		"prot %lx anon_vma %p vm_ops %p\n"
+		"pgoff %lx file %p private_data %p\n",
+		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
+		vma->vm_prev, vma->vm_mm,
+		(unsigned long)pgprot_val(vma->vm_page_prot),
+		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
+		vma->vm_file, vma->vm_private_data);
+	dump_flags(vma->vm_flags, vmaflags_names, ARRAY_SIZE(vmaflags_names));
+}
+EXPORT_SYMBOL(dump_vma);
+
+void dump_mm(const struct mm_struct *mm)
+{
+	pr_emerg("mm %p mmap %p seqnum %d task_size %lu\n"
+#ifdef CONFIG_MMU
+		"get_unmapped_area %p\n"
+#endif
+		"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
+		"pgd %p mm_users %d mm_count %d nr_ptes %lu nr_pmds %lu map_count %d\n"
+		"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
+		"pinned_vm %lx shared_vm %lx exec_vm %lx stack_vm %lx\n"
+		"start_code %lx end_code %lx start_data %lx end_data %lx\n"
+		"start_brk %lx brk %lx start_stack %lx\n"
+		"arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
+		"binfmt %p flags %lx core_state %p\n"
+#ifdef CONFIG_AIO
+		"ioctx_table %p\n"
+#endif
+#ifdef CONFIG_MEMCG
+		"owner %p "
+#endif
+		"exe_file %p\n"
+#ifdef CONFIG_MMU_NOTIFIER
+		"mmu_notifier_mm %p\n"
+#endif
+#ifdef CONFIG_NUMA_BALANCING
+		"numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
+#endif
+#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
+		"tlb_flush_pending %d\n"
+#endif
+		"%s",	/* This is here to hold the comma */
+
+		mm, mm->mmap, mm->vmacache_seqnum, mm->task_size,
+#ifdef CONFIG_MMU
+		mm->get_unmapped_area,
+#endif
+		mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
+		mm->pgd, atomic_read(&mm->mm_users),
+		atomic_read(&mm->mm_count),
+		atomic_long_read((atomic_long_t *)&mm->nr_ptes),
+		mm_nr_pmds((struct mm_struct *)mm),
+		mm->map_count,
+		mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
+		mm->pinned_vm, mm->shared_vm, mm->exec_vm, mm->stack_vm,
+		mm->start_code, mm->end_code, mm->start_data, mm->end_data,
+		mm->start_brk, mm->brk, mm->start_stack,
+		mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
+		mm->binfmt, mm->flags, mm->core_state,
+#ifdef CONFIG_AIO
+		mm->ioctx_table,
+#endif
+#ifdef CONFIG_MEMCG
+		mm->owner,
+#endif
+		mm->exe_file,
+#ifdef CONFIG_MMU_NOTIFIER
+		mm->mmu_notifier_mm,
+#endif
+#ifdef CONFIG_NUMA_BALANCING
+		mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
+#endif
+#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
+		mm->tlb_flush_pending,
+#endif
+		""		/* This is here to not have a comma! */
+		);
+
+		dump_flags(mm->def_flags, vmaflags_names,
+				ARRAY_SIZE(vmaflags_names));
+}
+
+#endif		/* CONFIG_DEBUG_VM */
diff --git a/mm/dmapool.c b/mm/dmapool.c
new file mode 100644
index 0000000..57312b5
--- /dev/null
+++ b/mm/dmapool.c
@@ -0,0 +1,537 @@
+/*
+ * DMA Pool allocator
+ *
+ * Copyright 2001 David Brownell
+ * Copyright 2007 Intel Corporation
+ *   Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * This software may be redistributed and/or modified under the terms of
+ * the GNU General Public License ("GPL") version 2 as published by the
+ * Free Software Foundation.
+ *
+ * This allocator returns small blocks of a given size which are DMA-able by
+ * the given device.  It uses the dma_alloc_coherent page allocator to get
+ * new pages, then splits them up into blocks of the required size.
+ * Many older drivers still have their own code to do this.
+ *
+ * The current design of this allocator is fairly simple.  The pool is
+ * represented by the 'struct dma_pool' which keeps a doubly-linked list of
+ * allocated pages.  Each page in the page_list is split into blocks of at
+ * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
+ * list of free blocks within the page.  Used blocks aren't tracked, but we
+ * keep a count of how many are currently allocated from each page.
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/poison.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
+#define DMAPOOL_DEBUG 1
+#endif
+
+struct dma_pool {		/* the pool */
+	struct list_head page_list;
+	spinlock_t lock;
+	size_t size;
+	struct device *dev;
+	size_t allocation;
+	size_t boundary;
+	char name[32];
+	struct list_head pools;
+};
+
+struct dma_page {		/* cacheable header for 'allocation' bytes */
+	struct list_head page_list;
+	void *vaddr;
+	dma_addr_t dma;
+	unsigned int in_use;
+	unsigned int offset;
+};
+
+static DEFINE_MUTEX(pools_lock);
+static DEFINE_MUTEX(pools_reg_lock);
+
+static ssize_t
+show_pools(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	unsigned temp;
+	unsigned size;
+	char *next;
+	struct dma_page *page;
+	struct dma_pool *pool;
+
+	next = buf;
+	size = PAGE_SIZE;
+
+	temp = scnprintf(next, size, "poolinfo - 0.1\n");
+	size -= temp;
+	next += temp;
+
+	mutex_lock(&pools_lock);
+	list_for_each_entry(pool, &dev->dma_pools, pools) {
+		unsigned pages = 0;
+		unsigned blocks = 0;
+
+		spin_lock_irq(&pool->lock);
+		list_for_each_entry(page, &pool->page_list, page_list) {
+			pages++;
+			blocks += page->in_use;
+		}
+		spin_unlock_irq(&pool->lock);
+
+		/* per-pool info, no real statistics yet */
+		temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
+				 pool->name, blocks,
+				 pages * (pool->allocation / pool->size),
+				 pool->size, pages);
+		size -= temp;
+		next += temp;
+	}
+	mutex_unlock(&pools_lock);
+
+	return PAGE_SIZE - size;
+}
+
+static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
+
+/**
+ * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
+ * @name: name of pool, for diagnostics
+ * @dev: device that will be doing the DMA
+ * @size: size of the blocks in this pool.
+ * @align: alignment requirement for blocks; must be a power of two
+ * @boundary: returned blocks won't cross this power of two boundary
+ * Context: !in_interrupt()
+ *
+ * Returns a dma allocation pool with the requested characteristics, or
+ * null if one can't be created.  Given one of these pools, dma_pool_alloc()
+ * may be used to allocate memory.  Such memory will all have "consistent"
+ * DMA mappings, accessible by the device and its driver without using
+ * cache flushing primitives.  The actual size of blocks allocated may be
+ * larger than requested because of alignment.
+ *
+ * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
+ * cross that size boundary.  This is useful for devices which have
+ * addressing restrictions on individual DMA transfers, such as not crossing
+ * boundaries of 4KBytes.
+ */
+struct dma_pool *dma_pool_create(const char *name, struct device *dev,
+				 size_t size, size_t align, size_t boundary)
+{
+	struct dma_pool *retval;
+	size_t allocation;
+	bool empty = false;
+
+	if (align == 0)
+		align = 1;
+	else if (align & (align - 1))
+		return NULL;
+
+	if (size == 0)
+		return NULL;
+	else if (size < 4)
+		size = 4;
+
+	if ((size % align) != 0)
+		size = ALIGN(size, align);
+
+	allocation = max_t(size_t, size, PAGE_SIZE);
+
+	if (!boundary)
+		boundary = allocation;
+	else if ((boundary < size) || (boundary & (boundary - 1)))
+		return NULL;
+
+	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
+	if (!retval)
+		return retval;
+
+	strlcpy(retval->name, name, sizeof(retval->name));
+
+	retval->dev = dev;
+
+	INIT_LIST_HEAD(&retval->page_list);
+	spin_lock_init(&retval->lock);
+	retval->size = size;
+	retval->boundary = boundary;
+	retval->allocation = allocation;
+
+	INIT_LIST_HEAD(&retval->pools);
+
+	/*
+	 * pools_lock ensures that the ->dma_pools list does not get corrupted.
+	 * pools_reg_lock ensures that there is not a race between
+	 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
+	 * when the first invocation of dma_pool_create() failed on
+	 * device_create_file() and the second assumes that it has been done (I
+	 * know it is a short window).
+	 */
+	mutex_lock(&pools_reg_lock);
+	mutex_lock(&pools_lock);
+	if (list_empty(&dev->dma_pools))
+		empty = true;
+	list_add(&retval->pools, &dev->dma_pools);
+	mutex_unlock(&pools_lock);
+	if (empty) {
+		int err;
+
+		err = device_create_file(dev, &dev_attr_pools);
+		if (err) {
+			mutex_lock(&pools_lock);
+			list_del(&retval->pools);
+			mutex_unlock(&pools_lock);
+			mutex_unlock(&pools_reg_lock);
+			kfree(retval);
+			return NULL;
+		}
+	}
+	mutex_unlock(&pools_reg_lock);
+	return retval;
+}
+EXPORT_SYMBOL(dma_pool_create);
+
+static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
+{
+	unsigned int offset = 0;
+	unsigned int next_boundary = pool->boundary;
+
+	do {
+		unsigned int next = offset + pool->size;
+		if (unlikely((next + pool->size) >= next_boundary)) {
+			next = next_boundary;
+			next_boundary += pool->boundary;
+		}
+		*(int *)(page->vaddr + offset) = next;
+		offset = next;
+	} while (offset < pool->allocation);
+}
+
+static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
+{
+	struct dma_page *page;
+
+	page = kmalloc(sizeof(*page), mem_flags);
+	if (!page)
+		return NULL;
+	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
+					 &page->dma, mem_flags);
+	if (page->vaddr) {
+#ifdef	DMAPOOL_DEBUG
+		memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+		pool_initialise_page(pool, page);
+		page->in_use = 0;
+		page->offset = 0;
+	} else {
+		kfree(page);
+		page = NULL;
+	}
+	return page;
+}
+
+static inline bool is_page_busy(struct dma_page *page)
+{
+	return page->in_use != 0;
+}
+
+static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
+{
+	dma_addr_t dma = page->dma;
+
+#ifdef	DMAPOOL_DEBUG
+	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+	dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
+	list_del(&page->page_list);
+	kfree(page);
+}
+
+/**
+ * dma_pool_destroy - destroys a pool of dma memory blocks.
+ * @pool: dma pool that will be destroyed
+ * Context: !in_interrupt()
+ *
+ * Caller guarantees that no more memory from the pool is in use,
+ * and that nothing will try to use the pool after this call.
+ */
+void dma_pool_destroy(struct dma_pool *pool)
+{
+	bool empty = false;
+
+	if (unlikely(!pool))
+		return;
+
+	mutex_lock(&pools_reg_lock);
+	mutex_lock(&pools_lock);
+	list_del(&pool->pools);
+	if (pool->dev && list_empty(&pool->dev->dma_pools))
+		empty = true;
+	mutex_unlock(&pools_lock);
+	if (empty)
+		device_remove_file(pool->dev, &dev_attr_pools);
+	mutex_unlock(&pools_reg_lock);
+
+	while (!list_empty(&pool->page_list)) {
+		struct dma_page *page;
+		page = list_entry(pool->page_list.next,
+				  struct dma_page, page_list);
+		if (is_page_busy(page)) {
+			if (pool->dev)
+				dev_err(pool->dev,
+					"dma_pool_destroy %s, %p busy\n",
+					pool->name, page->vaddr);
+			else
+				printk(KERN_ERR
+				       "dma_pool_destroy %s, %p busy\n",
+				       pool->name, page->vaddr);
+			/* leak the still-in-use consistent memory */
+			list_del(&page->page_list);
+			kfree(page);
+		} else
+			pool_free_page(pool, page);
+	}
+
+	kfree(pool);
+}
+EXPORT_SYMBOL(dma_pool_destroy);
+
+/**
+ * dma_pool_alloc - get a block of consistent memory
+ * @pool: dma pool that will produce the block
+ * @mem_flags: GFP_* bitmask
+ * @handle: pointer to dma address of block
+ *
+ * This returns the kernel virtual address of a currently unused block,
+ * and reports its dma address through the handle.
+ * If such a memory block can't be allocated, %NULL is returned.
+ */
+void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
+		     dma_addr_t *handle)
+{
+	unsigned long flags;
+	struct dma_page *page;
+	size_t offset;
+	void *retval;
+
+	might_sleep_if(gfpflags_allow_blocking(mem_flags));
+
+	spin_lock_irqsave(&pool->lock, flags);
+	list_for_each_entry(page, &pool->page_list, page_list) {
+		if (page->offset < pool->allocation)
+			goto ready;
+	}
+
+	/* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
+	if (!page)
+		return NULL;
+
+	spin_lock_irqsave(&pool->lock, flags);
+
+	list_add(&page->page_list, &pool->page_list);
+ ready:
+	page->in_use++;
+	offset = page->offset;
+	page->offset = *(int *)(page->vaddr + offset);
+	retval = offset + page->vaddr;
+	*handle = offset + page->dma;
+#ifdef	DMAPOOL_DEBUG
+	{
+		int i;
+		u8 *data = retval;
+		/* page->offset is stored in first 4 bytes */
+		for (i = sizeof(page->offset); i < pool->size; i++) {
+			if (data[i] == POOL_POISON_FREED)
+				continue;
+			if (pool->dev)
+				dev_err(pool->dev,
+					"dma_pool_alloc %s, %p (corrupted)\n",
+					pool->name, retval);
+			else
+				pr_err("dma_pool_alloc %s, %p (corrupted)\n",
+					pool->name, retval);
+
+			/*
+			 * Dump the first 4 bytes even if they are not
+			 * POOL_POISON_FREED
+			 */
+			print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
+					data, pool->size, 1);
+			break;
+		}
+	}
+	if (!(mem_flags & __GFP_ZERO))
+		memset(retval, POOL_POISON_ALLOCATED, pool->size);
+#endif
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	if (mem_flags & __GFP_ZERO)
+		memset(retval, 0, pool->size);
+
+	return retval;
+}
+EXPORT_SYMBOL(dma_pool_alloc);
+
+static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
+{
+	struct dma_page *page;
+
+	list_for_each_entry(page, &pool->page_list, page_list) {
+		if (dma < page->dma)
+			continue;
+		if ((dma - page->dma) < pool->allocation)
+			return page;
+	}
+	return NULL;
+}
+
+/**
+ * dma_pool_free - put block back into dma pool
+ * @pool: the dma pool holding the block
+ * @vaddr: virtual address of block
+ * @dma: dma address of block
+ *
+ * Caller promises neither device nor driver will again touch this block
+ * unless it is first re-allocated.
+ */
+void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
+{
+	struct dma_page *page;
+	unsigned long flags;
+	unsigned int offset;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	page = pool_find_page(pool, dma);
+	if (!page) {
+		spin_unlock_irqrestore(&pool->lock, flags);
+		if (pool->dev)
+			dev_err(pool->dev,
+				"dma_pool_free %s, %p/%lx (bad dma)\n",
+				pool->name, vaddr, (unsigned long)dma);
+		else
+			printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
+			       pool->name, vaddr, (unsigned long)dma);
+		return;
+	}
+
+	offset = vaddr - page->vaddr;
+#ifdef	DMAPOOL_DEBUG
+	if ((dma - page->dma) != offset) {
+		spin_unlock_irqrestore(&pool->lock, flags);
+		if (pool->dev)
+			dev_err(pool->dev,
+				"dma_pool_free %s, %p (bad vaddr)/%Lx\n",
+				pool->name, vaddr, (unsigned long long)dma);
+		else
+			printk(KERN_ERR
+			       "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
+			       pool->name, vaddr, (unsigned long long)dma);
+		return;
+	}
+	{
+		unsigned int chain = page->offset;
+		while (chain < pool->allocation) {
+			if (chain != offset) {
+				chain = *(int *)(page->vaddr + chain);
+				continue;
+			}
+			spin_unlock_irqrestore(&pool->lock, flags);
+			if (pool->dev)
+				dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
+					"already free\n", pool->name,
+					(unsigned long long)dma);
+			else
+				printk(KERN_ERR "dma_pool_free %s, dma %Lx "
+					"already free\n", pool->name,
+					(unsigned long long)dma);
+			return;
+		}
+	}
+	memset(vaddr, POOL_POISON_FREED, pool->size);
+#endif
+
+	page->in_use--;
+	*(int *)vaddr = page->offset;
+	page->offset = offset;
+	/*
+	 * Resist a temptation to do
+	 *    if (!is_page_busy(page)) pool_free_page(pool, page);
+	 * Better have a few empty pages hang around.
+	 */
+	spin_unlock_irqrestore(&pool->lock, flags);
+}
+EXPORT_SYMBOL(dma_pool_free);
+
+/*
+ * Managed DMA pool
+ */
+static void dmam_pool_release(struct device *dev, void *res)
+{
+	struct dma_pool *pool = *(struct dma_pool **)res;
+
+	dma_pool_destroy(pool);
+}
+
+static int dmam_pool_match(struct device *dev, void *res, void *match_data)
+{
+	return *(struct dma_pool **)res == match_data;
+}
+
+/**
+ * dmam_pool_create - Managed dma_pool_create()
+ * @name: name of pool, for diagnostics
+ * @dev: device that will be doing the DMA
+ * @size: size of the blocks in this pool.
+ * @align: alignment requirement for blocks; must be a power of two
+ * @allocation: returned blocks won't cross this boundary (or zero)
+ *
+ * Managed dma_pool_create().  DMA pool created with this function is
+ * automatically destroyed on driver detach.
+ */
+struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
+				  size_t size, size_t align, size_t allocation)
+{
+	struct dma_pool **ptr, *pool;
+
+	ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
+	if (pool)
+		devres_add(dev, ptr);
+	else
+		devres_free(ptr);
+
+	return pool;
+}
+EXPORT_SYMBOL(dmam_pool_create);
+
+/**
+ * dmam_pool_destroy - Managed dma_pool_destroy()
+ * @pool: dma pool that will be destroyed
+ *
+ * Managed dma_pool_destroy().
+ */
+void dmam_pool_destroy(struct dma_pool *pool)
+{
+	struct device *dev = pool->dev;
+
+	WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
+}
+EXPORT_SYMBOL(dmam_pool_destroy);
diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
new file mode 100644
index 0000000..6d5717b
--- /dev/null
+++ b/mm/early_ioremap.c
@@ -0,0 +1,280 @@
+/*
+ * Provide common bits of early_ioremap() support for architectures needing
+ * temporary mappings during boot before ioremap() is available.
+ *
+ * This is mostly a direct copy of the x86 early_ioremap implementation.
+ *
+ * (C) Copyright 1995 1996, 2014 Linus Torvalds
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <asm/fixmap.h>
+#include <asm/early_ioremap.h>
+
+#ifdef CONFIG_MMU
+static int early_ioremap_debug __initdata;
+
+static int __init early_ioremap_debug_setup(char *str)
+{
+	early_ioremap_debug = 1;
+
+	return 0;
+}
+early_param("early_ioremap_debug", early_ioremap_debug_setup);
+
+static int after_paging_init __initdata;
+
+void __init __weak early_ioremap_shutdown(void)
+{
+}
+
+void __init early_ioremap_reset(void)
+{
+	early_ioremap_shutdown();
+	after_paging_init = 1;
+}
+
+/*
+ * Generally, ioremap() is available after paging_init() has been called.
+ * Architectures wanting to allow early_ioremap after paging_init() can
+ * define __late_set_fixmap and __late_clear_fixmap to do the right thing.
+ */
+#ifndef __late_set_fixmap
+static inline void __init __late_set_fixmap(enum fixed_addresses idx,
+					    phys_addr_t phys, pgprot_t prot)
+{
+	BUG();
+}
+#endif
+
+#ifndef __late_clear_fixmap
+static inline void __init __late_clear_fixmap(enum fixed_addresses idx)
+{
+	BUG();
+}
+#endif
+
+static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
+static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
+static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
+
+void __init early_ioremap_setup(void)
+{
+	int i;
+
+	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
+		if (WARN_ON(prev_map[i]))
+			break;
+
+	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
+		slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*i);
+}
+
+static int __init check_early_ioremap_leak(void)
+{
+	int count = 0;
+	int i;
+
+	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
+		if (prev_map[i])
+			count++;
+
+	if (WARN(count, KERN_WARNING
+		 "Debug warning: early ioremap leak of %d areas detected.\n"
+		 "please boot with early_ioremap_debug and report the dmesg.\n",
+		 count))
+		return 1;
+	return 0;
+}
+late_initcall(check_early_ioremap_leak);
+
+static void __init __iomem *
+__early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
+{
+	unsigned long offset;
+	resource_size_t last_addr;
+	unsigned int nrpages;
+	enum fixed_addresses idx;
+	int i, slot;
+
+	WARN_ON(system_state != SYSTEM_BOOTING);
+
+	slot = -1;
+	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+		if (!prev_map[i]) {
+			slot = i;
+			break;
+		}
+	}
+
+	if (WARN(slot < 0, "%s(%08llx, %08lx) not found slot\n",
+		 __func__, (u64)phys_addr, size))
+		return NULL;
+
+	/* Don't allow wraparound or zero size */
+	last_addr = phys_addr + size - 1;
+	if (WARN_ON(!size || last_addr < phys_addr))
+		return NULL;
+
+	prev_size[slot] = size;
+	/*
+	 * Mappings have to be page-aligned
+	 */
+	offset = offset_in_page(phys_addr);
+	phys_addr &= PAGE_MASK;
+	size = PAGE_ALIGN(last_addr + 1) - phys_addr;
+
+	/*
+	 * Mappings have to fit in the FIX_BTMAP area.
+	 */
+	nrpages = size >> PAGE_SHIFT;
+	if (WARN_ON(nrpages > NR_FIX_BTMAPS))
+		return NULL;
+
+	/*
+	 * Ok, go for it..
+	 */
+	idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
+	while (nrpages > 0) {
+		if (after_paging_init)
+			__late_set_fixmap(idx, phys_addr, prot);
+		else
+			__early_set_fixmap(idx, phys_addr, prot);
+		phys_addr += PAGE_SIZE;
+		--idx;
+		--nrpages;
+	}
+	WARN(early_ioremap_debug, "%s(%08llx, %08lx) [%d] => %08lx + %08lx\n",
+	     __func__, (u64)phys_addr, size, slot, offset, slot_virt[slot]);
+
+	prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
+	return prev_map[slot];
+}
+
+void __init early_iounmap(void __iomem *addr, unsigned long size)
+{
+	unsigned long virt_addr;
+	unsigned long offset;
+	unsigned int nrpages;
+	enum fixed_addresses idx;
+	int i, slot;
+
+	slot = -1;
+	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+		if (prev_map[i] == addr) {
+			slot = i;
+			break;
+		}
+	}
+
+	if (WARN(slot < 0, "early_iounmap(%p, %08lx) not found slot\n",
+		 addr, size))
+		return;
+
+	if (WARN(prev_size[slot] != size,
+		 "early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
+		 addr, size, slot, prev_size[slot]))
+		return;
+
+	WARN(early_ioremap_debug, "early_iounmap(%p, %08lx) [%d]\n",
+	     addr, size, slot);
+
+	virt_addr = (unsigned long)addr;
+	if (WARN_ON(virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)))
+		return;
+
+	offset = offset_in_page(virt_addr);
+	nrpages = PAGE_ALIGN(offset + size) >> PAGE_SHIFT;
+
+	idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
+	while (nrpages > 0) {
+		if (after_paging_init)
+			__late_clear_fixmap(idx);
+		else
+			__early_set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR);
+		--idx;
+		--nrpages;
+	}
+	prev_map[slot] = NULL;
+}
+
+/* Remap an IO device */
+void __init __iomem *
+early_ioremap(resource_size_t phys_addr, unsigned long size)
+{
+	return __early_ioremap(phys_addr, size, FIXMAP_PAGE_IO);
+}
+
+/* Remap memory */
+void __init *
+early_memremap(resource_size_t phys_addr, unsigned long size)
+{
+	return (__force void *)__early_ioremap(phys_addr, size,
+					       FIXMAP_PAGE_NORMAL);
+}
+#ifdef FIXMAP_PAGE_RO
+void __init *
+early_memremap_ro(resource_size_t phys_addr, unsigned long size)
+{
+	return (__force void *)__early_ioremap(phys_addr, size, FIXMAP_PAGE_RO);
+}
+#endif
+
+#define MAX_MAP_CHUNK	(NR_FIX_BTMAPS << PAGE_SHIFT)
+
+void __init copy_from_early_mem(void *dest, phys_addr_t src, unsigned long size)
+{
+	unsigned long slop, clen;
+	char *p;
+
+	while (size) {
+		slop = offset_in_page(src);
+		clen = size;
+		if (clen > MAX_MAP_CHUNK - slop)
+			clen = MAX_MAP_CHUNK - slop;
+		p = early_memremap(src & PAGE_MASK, clen + slop);
+		memcpy(dest, p + slop, clen);
+		early_memunmap(p, clen + slop);
+		dest += clen;
+		src += clen;
+		size -= clen;
+	}
+}
+
+#else /* CONFIG_MMU */
+
+void __init __iomem *
+early_ioremap(resource_size_t phys_addr, unsigned long size)
+{
+	return (__force void __iomem *)phys_addr;
+}
+
+/* Remap memory */
+void __init *
+early_memremap(resource_size_t phys_addr, unsigned long size)
+{
+	return (void *)phys_addr;
+}
+void __init *
+early_memremap_ro(resource_size_t phys_addr, unsigned long size)
+{
+	return (void *)phys_addr;
+}
+
+void __init early_iounmap(void __iomem *addr, unsigned long size)
+{
+}
+
+#endif /* CONFIG_MMU */
+
+
+void __init early_memunmap(void *addr, unsigned long size)
+{
+	early_iounmap((__force void __iomem *)addr, size);
+}
diff --git a/mm/fadvise.c b/mm/fadvise.c
new file mode 100644
index 0000000..b8a5bc6
--- /dev/null
+++ b/mm/fadvise.c
@@ -0,0 +1,162 @@
+/*
+ * mm/fadvise.c
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 11Jan2003	Andrew Morton
+ *		Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/pagevec.h>
+#include <linux/fadvise.h>
+#include <linux/writeback.h>
+#include <linux/syscalls.h>
+#include <linux/swap.h>
+
+#include <asm/unistd.h>
+
+/*
+ * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
+ * deactivate the pages and clear PG_Referenced.
+ */
+SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
+{
+	struct fd f = fdget(fd);
+	struct inode *inode;
+	struct address_space *mapping;
+	struct backing_dev_info *bdi;
+	loff_t endbyte;			/* inclusive */
+	pgoff_t start_index;
+	pgoff_t end_index;
+	unsigned long nrpages;
+	int ret = 0;
+
+	if (!f.file)
+		return -EBADF;
+
+	inode = file_inode(f.file);
+	if (S_ISFIFO(inode->i_mode)) {
+		ret = -ESPIPE;
+		goto out;
+	}
+
+	mapping = f.file->f_mapping;
+	if (!mapping || len < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (IS_DAX(inode)) {
+		switch (advice) {
+		case POSIX_FADV_NORMAL:
+		case POSIX_FADV_RANDOM:
+		case POSIX_FADV_SEQUENTIAL:
+		case POSIX_FADV_WILLNEED:
+		case POSIX_FADV_NOREUSE:
+		case POSIX_FADV_DONTNEED:
+			/* no bad return value, but ignore advice */
+			break;
+		default:
+			ret = -EINVAL;
+		}
+		goto out;
+	}
+
+	/* Careful about overflows. Len == 0 means "as much as possible" */
+	endbyte = offset + len;
+	if (!len || endbyte < len)
+		endbyte = -1;
+	else
+		endbyte--;		/* inclusive */
+
+	bdi = inode_to_bdi(mapping->host);
+
+	switch (advice) {
+	case POSIX_FADV_NORMAL:
+		f.file->f_ra.ra_pages = bdi->ra_pages;
+		spin_lock(&f.file->f_lock);
+		f.file->f_mode &= ~FMODE_RANDOM;
+		spin_unlock(&f.file->f_lock);
+		break;
+	case POSIX_FADV_RANDOM:
+		spin_lock(&f.file->f_lock);
+		f.file->f_mode |= FMODE_RANDOM;
+		spin_unlock(&f.file->f_lock);
+		break;
+	case POSIX_FADV_SEQUENTIAL:
+		f.file->f_ra.ra_pages = bdi->ra_pages * 2;
+		spin_lock(&f.file->f_lock);
+		f.file->f_mode &= ~FMODE_RANDOM;
+		spin_unlock(&f.file->f_lock);
+		break;
+	case POSIX_FADV_WILLNEED:
+		/* First and last PARTIAL page! */
+		start_index = offset >> PAGE_CACHE_SHIFT;
+		end_index = endbyte >> PAGE_CACHE_SHIFT;
+
+		/* Careful about overflow on the "+1" */
+		nrpages = end_index - start_index + 1;
+		if (!nrpages)
+			nrpages = ~0UL;
+
+		/*
+		 * Ignore return value because fadvise() shall return
+		 * success even if filesystem can't retrieve a hint,
+		 */
+		force_page_cache_readahead(mapping, f.file, start_index,
+					   nrpages);
+		break;
+	case POSIX_FADV_NOREUSE:
+		break;
+	case POSIX_FADV_DONTNEED:
+		if (!inode_write_congested(mapping->host))
+			__filemap_fdatawrite_range(mapping, offset, endbyte,
+						   WB_SYNC_NONE);
+
+		/*
+		 * First and last FULL page! Partial pages are deliberately
+		 * preserved on the expectation that it is better to preserve
+		 * needed memory than to discard unneeded memory.
+		 */
+		start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
+		end_index = (endbyte >> PAGE_CACHE_SHIFT);
+
+		if (end_index >= start_index) {
+			unsigned long count = invalidate_mapping_pages(mapping,
+						start_index, end_index);
+
+			/*
+			 * If fewer pages were invalidated than expected then
+			 * it is possible that some of the pages were on
+			 * a per-cpu pagevec for a remote CPU. Drain all
+			 * pagevecs and try again.
+			 */
+			if (count < (end_index - start_index + 1)) {
+				lru_add_drain_all();
+				invalidate_mapping_pages(mapping, start_index,
+						end_index);
+			}
+		}
+		break;
+	default:
+		ret = -EINVAL;
+	}
+out:
+	fdput(f);
+	return ret;
+}
+
+#ifdef __ARCH_WANT_SYS_FADVISE64
+
+SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
+{
+	return sys_fadvise64_64(fd, offset, len, advice);
+}
+
+#endif
diff --git a/mm/failslab.c b/mm/failslab.c
new file mode 100644
index 0000000..79171b4
--- /dev/null
+++ b/mm/failslab.c
@@ -0,0 +1,60 @@
+#include <linux/fault-inject.h>
+#include <linux/slab.h>
+
+static struct {
+	struct fault_attr attr;
+	bool ignore_gfp_reclaim;
+	bool cache_filter;
+} failslab = {
+	.attr = FAULT_ATTR_INITIALIZER,
+	.ignore_gfp_reclaim = true,
+	.cache_filter = false,
+};
+
+bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
+{
+	if (gfpflags & __GFP_NOFAIL)
+		return false;
+
+	if (failslab.ignore_gfp_reclaim && (gfpflags & __GFP_RECLAIM))
+		return false;
+
+	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
+		return false;
+
+	return should_fail(&failslab.attr, size);
+}
+
+static int __init setup_failslab(char *str)
+{
+	return setup_fault_attr(&failslab.attr, str);
+}
+__setup("failslab=", setup_failslab);
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+static int __init failslab_debugfs_init(void)
+{
+	struct dentry *dir;
+	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+
+	dir = fault_create_debugfs_attr("failslab", NULL, &failslab.attr);
+	if (IS_ERR(dir))
+		return PTR_ERR(dir);
+
+	if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
+				&failslab.ignore_gfp_reclaim))
+		goto fail;
+	if (!debugfs_create_bool("cache-filter", mode, dir,
+				&failslab.cache_filter))
+		goto fail;
+
+	return 0;
+fail:
+	debugfs_remove_recursive(dir);
+
+	return -ENOMEM;
+}
+
+late_initcall(failslab_debugfs_init);
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
diff --git a/mm/filemap.c b/mm/filemap.c
new file mode 100644
index 0000000..69f75c7
--- /dev/null
+++ b/mm/filemap.c
@@ -0,0 +1,2747 @@
+/*
+ *	linux/mm/filemap.c
+ *
+ * Copyright (C) 1994-1999  Linus Torvalds
+ */
+
+/*
+ * This file handles the generic file mmap semantics used by
+ * most "normal" filesystems (but you don't /have/ to use this:
+ * the NFS filesystem used to do this differently, for example)
+ */
+#include <linux/export.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/capability.h>
+#include <linux/kernel_stat.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/hash.h>
+#include <linux/writeback.h>
+#include <linux/backing-dev.h>
+#include <linux/pagevec.h>
+#include <linux/blkdev.h>
+#include <linux/security.h>
+#include <linux/cpuset.h>
+#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
+#include <linux/hugetlb.h>
+#include <linux/memcontrol.h>
+#include <linux/cleancache.h>
+#include <linux/rmap.h>
+#include "internal.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/filemap.h>
+
+/*
+ * FIXME: remove all knowledge of the buffer layer from the core VM
+ */
+#include <linux/buffer_head.h> /* for try_to_free_buffers */
+
+#include <asm/mman.h>
+
+/*
+ * Shared mappings implemented 30.11.1994. It's not fully working yet,
+ * though.
+ *
+ * Shared mappings now work. 15.8.1995  Bruno.
+ *
+ * finished 'unifying' the page and buffer cache and SMP-threaded the
+ * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
+ *
+ * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
+ */
+
+/*
+ * Lock ordering:
+ *
+ *  ->i_mmap_rwsem		(truncate_pagecache)
+ *    ->private_lock		(__free_pte->__set_page_dirty_buffers)
+ *      ->swap_lock		(exclusive_swap_page, others)
+ *        ->mapping->tree_lock
+ *
+ *  ->i_mutex
+ *    ->i_mmap_rwsem		(truncate->unmap_mapping_range)
+ *
+ *  ->mmap_sem
+ *    ->i_mmap_rwsem
+ *      ->page_table_lock or pte_lock	(various, mainly in memory.c)
+ *        ->mapping->tree_lock	(arch-dependent flush_dcache_mmap_lock)
+ *
+ *  ->mmap_sem
+ *    ->lock_page		(access_process_vm)
+ *
+ *  ->i_mutex			(generic_perform_write)
+ *    ->mmap_sem		(fault_in_pages_readable->do_page_fault)
+ *
+ *  bdi->wb.list_lock
+ *    sb_lock			(fs/fs-writeback.c)
+ *    ->mapping->tree_lock	(__sync_single_inode)
+ *
+ *  ->i_mmap_rwsem
+ *    ->anon_vma.lock		(vma_adjust)
+ *
+ *  ->anon_vma.lock
+ *    ->page_table_lock or pte_lock	(anon_vma_prepare and various)
+ *
+ *  ->page_table_lock or pte_lock
+ *    ->swap_lock		(try_to_unmap_one)
+ *    ->private_lock		(try_to_unmap_one)
+ *    ->tree_lock		(try_to_unmap_one)
+ *    ->zone.lru_lock		(follow_page->mark_page_accessed)
+ *    ->zone.lru_lock		(check_pte_range->isolate_lru_page)
+ *    ->private_lock		(page_remove_rmap->set_page_dirty)
+ *    ->tree_lock		(page_remove_rmap->set_page_dirty)
+ *    bdi.wb->list_lock		(page_remove_rmap->set_page_dirty)
+ *    ->inode->i_lock		(page_remove_rmap->set_page_dirty)
+ *    ->memcg->move_lock	(page_remove_rmap->mem_cgroup_begin_page_stat)
+ *    bdi.wb->list_lock		(zap_pte_range->set_page_dirty)
+ *    ->inode->i_lock		(zap_pte_range->set_page_dirty)
+ *    ->private_lock		(zap_pte_range->__set_page_dirty_buffers)
+ *
+ * ->i_mmap_rwsem
+ *   ->tasklist_lock            (memory_failure, collect_procs_ao)
+ */
+
+static int page_cache_tree_insert(struct address_space *mapping,
+				  struct page *page, void **shadowp)
+{
+	struct radix_tree_node *node;
+	void **slot;
+	int error;
+
+	error = __radix_tree_create(&mapping->page_tree, page->index,
+				    &node, &slot);
+	if (error)
+		return error;
+	if (*slot) {
+		void *p;
+
+		p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
+		if (!radix_tree_exceptional_entry(p))
+			return -EEXIST;
+		if (shadowp)
+			*shadowp = p;
+		mapping->nrshadows--;
+		if (node)
+			workingset_node_shadows_dec(node);
+	}
+	radix_tree_replace_slot(slot, page);
+	mapping->nrpages++;
+	if (node) {
+		workingset_node_pages_inc(node);
+		/*
+		 * Don't track node that contains actual pages.
+		 *
+		 * Avoid acquiring the list_lru lock if already
+		 * untracked.  The list_empty() test is safe as
+		 * node->private_list is protected by
+		 * mapping->tree_lock.
+		 */
+		if (!list_empty(&node->private_list))
+			list_lru_del(&workingset_shadow_nodes,
+				     &node->private_list);
+	}
+	return 0;
+}
+
+static void page_cache_tree_delete(struct address_space *mapping,
+				   struct page *page, void *shadow)
+{
+	struct radix_tree_node *node;
+	unsigned long index;
+	unsigned int offset;
+	unsigned int tag;
+	void **slot;
+
+	VM_BUG_ON(!PageLocked(page));
+
+	__radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
+
+	if (!node) {
+		/*
+		 * We need a node to properly account shadow
+		 * entries. Don't plant any without. XXX
+		 */
+		shadow = NULL;
+	}
+
+	if (shadow) {
+		mapping->nrshadows++;
+		/*
+		 * Make sure the nrshadows update is committed before
+		 * the nrpages update so that final truncate racing
+		 * with reclaim does not see both counters 0 at the
+		 * same time and miss a shadow entry.
+		 */
+		smp_wmb();
+	}
+	mapping->nrpages--;
+
+	if (!node) {
+		/* Clear direct pointer tags in root node */
+		mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
+		radix_tree_replace_slot(slot, shadow);
+		return;
+	}
+
+	/* Clear tree tags for the removed page */
+	index = page->index;
+	offset = index & RADIX_TREE_MAP_MASK;
+	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
+		if (test_bit(offset, node->tags[tag]))
+			radix_tree_tag_clear(&mapping->page_tree, index, tag);
+	}
+
+	/* Delete page, swap shadow entry */
+	radix_tree_replace_slot(slot, shadow);
+	workingset_node_pages_dec(node);
+	if (shadow)
+		workingset_node_shadows_inc(node);
+	else
+		if (__radix_tree_delete_node(&mapping->page_tree, node))
+			return;
+
+	/*
+	 * Track node that only contains shadow entries.
+	 *
+	 * Avoid acquiring the list_lru lock if already tracked.  The
+	 * list_empty() test is safe as node->private_list is
+	 * protected by mapping->tree_lock.
+	 */
+	if (!workingset_node_pages(node) &&
+	    list_empty(&node->private_list)) {
+		node->private_data = mapping;
+		list_lru_add(&workingset_shadow_nodes, &node->private_list);
+	}
+}
+
+/*
+ * Delete a page from the page cache and free it. Caller has to make
+ * sure the page is locked and that nobody else uses it - or that usage
+ * is safe.  The caller must hold the mapping's tree_lock and
+ * mem_cgroup_begin_page_stat().
+ */
+void __delete_from_page_cache(struct page *page, void *shadow,
+			      struct mem_cgroup *memcg)
+{
+	struct address_space *mapping = page->mapping;
+
+	trace_mm_filemap_delete_from_page_cache(page);
+	/*
+	 * if we're uptodate, flush out into the cleancache, otherwise
+	 * invalidate any existing cleancache entries.  We can't leave
+	 * stale data around in the cleancache once our page is gone
+	 */
+	if (PageUptodate(page) && PageMappedToDisk(page))
+		cleancache_put_page(page);
+	else
+		cleancache_invalidate_page(mapping, page);
+
+	page_cache_tree_delete(mapping, page, shadow);
+
+	page->mapping = NULL;
+	/* Leave page->index set: truncation lookup relies upon it */
+
+	/* hugetlb pages do not participate in page cache accounting. */
+	if (!PageHuge(page))
+		__dec_zone_page_state(page, NR_FILE_PAGES);
+	if (PageSwapBacked(page))
+		__dec_zone_page_state(page, NR_SHMEM);
+	BUG_ON(page_mapped(page));
+
+	/*
+	 * At this point page must be either written or cleaned by truncate.
+	 * Dirty page here signals a bug and loss of unwritten data.
+	 *
+	 * This fixes dirty accounting after removing the page entirely but
+	 * leaves PageDirty set: it has no effect for truncated page and
+	 * anyway will be cleared before returning page into buddy allocator.
+	 */
+	if (WARN_ON_ONCE(PageDirty(page)))
+		account_page_cleaned(page, mapping, memcg,
+				     inode_to_wb(mapping->host));
+}
+
+/**
+ * delete_from_page_cache - delete page from page cache
+ * @page: the page which the kernel is trying to remove from page cache
+ *
+ * This must be called only on pages that have been verified to be in the page
+ * cache and locked.  It will never put the page into the free list, the caller
+ * has a reference on the page.
+ */
+void delete_from_page_cache(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct mem_cgroup *memcg;
+	unsigned long flags;
+
+	void (*freepage)(struct page *);
+
+	BUG_ON(!PageLocked(page));
+
+	freepage = mapping->a_ops->freepage;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	spin_lock_irqsave(&mapping->tree_lock, flags);
+	__delete_from_page_cache(page, NULL, memcg);
+	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	mem_cgroup_end_page_stat(memcg);
+
+	if (freepage)
+		freepage(page);
+	page_cache_release(page);
+}
+EXPORT_SYMBOL(delete_from_page_cache);
+
+static int filemap_check_errors(struct address_space *mapping)
+{
+	int ret = 0;
+	/* Check for outstanding write errors */
+	if (test_bit(AS_ENOSPC, &mapping->flags) &&
+	    test_and_clear_bit(AS_ENOSPC, &mapping->flags))
+		ret = -ENOSPC;
+	if (test_bit(AS_EIO, &mapping->flags) &&
+	    test_and_clear_bit(AS_EIO, &mapping->flags))
+		ret = -EIO;
+	return ret;
+}
+
+/**
+ * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
+ * @mapping:	address space structure to write
+ * @start:	offset in bytes where the range starts
+ * @end:	offset in bytes where the range ends (inclusive)
+ * @sync_mode:	enable synchronous operation
+ *
+ * Start writeback against all of a mapping's dirty pages that lie
+ * within the byte offsets <start, end> inclusive.
+ *
+ * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
+ * opposed to a regular memory cleansing writeback.  The difference between
+ * these two operations is that if a dirty page/buffer is encountered, it must
+ * be waited upon, and not just skipped over.
+ */
+int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
+				loff_t end, int sync_mode)
+{
+	int ret;
+	struct writeback_control wbc = {
+		.sync_mode = sync_mode,
+		.nr_to_write = LONG_MAX,
+		.range_start = start,
+		.range_end = end,
+	};
+
+	if (!mapping_cap_writeback_dirty(mapping))
+		return 0;
+
+	wbc_attach_fdatawrite_inode(&wbc, mapping->host);
+	ret = do_writepages(mapping, &wbc);
+	wbc_detach_inode(&wbc);
+	return ret;
+}
+
+static inline int __filemap_fdatawrite(struct address_space *mapping,
+	int sync_mode)
+{
+	return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
+}
+
+int filemap_fdatawrite(struct address_space *mapping)
+{
+	return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
+}
+EXPORT_SYMBOL(filemap_fdatawrite);
+
+int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
+				loff_t end)
+{
+	return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
+}
+EXPORT_SYMBOL(filemap_fdatawrite_range);
+
+/**
+ * filemap_flush - mostly a non-blocking flush
+ * @mapping:	target address_space
+ *
+ * This is a mostly non-blocking flush.  Not suitable for data-integrity
+ * purposes - I/O may not be started against all dirty pages.
+ */
+int filemap_flush(struct address_space *mapping)
+{
+	return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
+}
+EXPORT_SYMBOL(filemap_flush);
+
+static int __filemap_fdatawait_range(struct address_space *mapping,
+				     loff_t start_byte, loff_t end_byte)
+{
+	pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
+	pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
+	struct pagevec pvec;
+	int nr_pages;
+	int ret = 0;
+
+	if (end_byte < start_byte)
+		goto out;
+
+	pagevec_init(&pvec, 0);
+	while ((index <= end) &&
+			(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+			PAGECACHE_TAG_WRITEBACK,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
+		unsigned i;
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			/* until radix tree lookup accepts end_index */
+			if (page->index > end)
+				continue;
+
+			wait_on_page_writeback(page);
+			if (TestClearPageError(page))
+				ret = -EIO;
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+out:
+	return ret;
+}
+
+/**
+ * filemap_fdatawait_range - wait for writeback to complete
+ * @mapping:		address space structure to wait for
+ * @start_byte:		offset in bytes where the range starts
+ * @end_byte:		offset in bytes where the range ends (inclusive)
+ *
+ * Walk the list of under-writeback pages of the given address space
+ * in the given range and wait for all of them.  Check error status of
+ * the address space and return it.
+ *
+ * Since the error status of the address space is cleared by this function,
+ * callers are responsible for checking the return value and handling and/or
+ * reporting the error.
+ */
+int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
+			    loff_t end_byte)
+{
+	int ret, ret2;
+
+	ret = __filemap_fdatawait_range(mapping, start_byte, end_byte);
+	ret2 = filemap_check_errors(mapping);
+	if (!ret)
+		ret = ret2;
+
+	return ret;
+}
+EXPORT_SYMBOL(filemap_fdatawait_range);
+
+/**
+ * filemap_fdatawait_keep_errors - wait for writeback without clearing errors
+ * @mapping: address space structure to wait for
+ *
+ * Walk the list of under-writeback pages of the given address space
+ * and wait for all of them.  Unlike filemap_fdatawait(), this function
+ * does not clear error status of the address space.
+ *
+ * Use this function if callers don't handle errors themselves.  Expected
+ * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
+ * fsfreeze(8)
+ */
+void filemap_fdatawait_keep_errors(struct address_space *mapping)
+{
+	loff_t i_size = i_size_read(mapping->host);
+
+	if (i_size == 0)
+		return;
+
+	__filemap_fdatawait_range(mapping, 0, i_size - 1);
+}
+
+/**
+ * filemap_fdatawait - wait for all under-writeback pages to complete
+ * @mapping: address space structure to wait for
+ *
+ * Walk the list of under-writeback pages of the given address space
+ * and wait for all of them.  Check error status of the address space
+ * and return it.
+ *
+ * Since the error status of the address space is cleared by this function,
+ * callers are responsible for checking the return value and handling and/or
+ * reporting the error.
+ */
+int filemap_fdatawait(struct address_space *mapping)
+{
+	loff_t i_size = i_size_read(mapping->host);
+
+	if (i_size == 0)
+		return 0;
+
+	return filemap_fdatawait_range(mapping, 0, i_size - 1);
+}
+EXPORT_SYMBOL(filemap_fdatawait);
+
+int filemap_write_and_wait(struct address_space *mapping)
+{
+	int err = 0;
+
+	if (mapping->nrpages) {
+		err = filemap_fdatawrite(mapping);
+		/*
+		 * Even if the above returned error, the pages may be
+		 * written partially (e.g. -ENOSPC), so we wait for it.
+		 * But the -EIO is special case, it may indicate the worst
+		 * thing (e.g. bug) happened, so we avoid waiting for it.
+		 */
+		if (err != -EIO) {
+			int err2 = filemap_fdatawait(mapping);
+			if (!err)
+				err = err2;
+		}
+	} else {
+		err = filemap_check_errors(mapping);
+	}
+	return err;
+}
+EXPORT_SYMBOL(filemap_write_and_wait);
+
+/**
+ * filemap_write_and_wait_range - write out & wait on a file range
+ * @mapping:	the address_space for the pages
+ * @lstart:	offset in bytes where the range starts
+ * @lend:	offset in bytes where the range ends (inclusive)
+ *
+ * Write out and wait upon file offsets lstart->lend, inclusive.
+ *
+ * Note that `lend' is inclusive (describes the last byte to be written) so
+ * that this function can be used to write to the very end-of-file (end = -1).
+ */
+int filemap_write_and_wait_range(struct address_space *mapping,
+				 loff_t lstart, loff_t lend)
+{
+	int err = 0;
+
+	if (mapping->nrpages) {
+		err = __filemap_fdatawrite_range(mapping, lstart, lend,
+						 WB_SYNC_ALL);
+		/* See comment of filemap_write_and_wait() */
+		if (err != -EIO) {
+			int err2 = filemap_fdatawait_range(mapping,
+						lstart, lend);
+			if (!err)
+				err = err2;
+		}
+	} else {
+		err = filemap_check_errors(mapping);
+	}
+	return err;
+}
+EXPORT_SYMBOL(filemap_write_and_wait_range);
+
+/**
+ * replace_page_cache_page - replace a pagecache page with a new one
+ * @old:	page to be replaced
+ * @new:	page to replace with
+ * @gfp_mask:	allocation mode
+ *
+ * This function replaces a page in the pagecache with a new one.  On
+ * success it acquires the pagecache reference for the new page and
+ * drops it for the old page.  Both the old and new pages must be
+ * locked.  This function does not add the new page to the LRU, the
+ * caller must do that.
+ *
+ * The remove + add is atomic.  The only way this function can fail is
+ * memory allocation failure.
+ */
+int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
+{
+	int error;
+
+	VM_BUG_ON_PAGE(!PageLocked(old), old);
+	VM_BUG_ON_PAGE(!PageLocked(new), new);
+	VM_BUG_ON_PAGE(new->mapping, new);
+
+	error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
+	if (!error) {
+		struct address_space *mapping = old->mapping;
+		void (*freepage)(struct page *);
+		struct mem_cgroup *memcg;
+		unsigned long flags;
+
+		pgoff_t offset = old->index;
+		freepage = mapping->a_ops->freepage;
+
+		page_cache_get(new);
+		new->mapping = mapping;
+		new->index = offset;
+
+		memcg = mem_cgroup_begin_page_stat(old);
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		__delete_from_page_cache(old, NULL, memcg);
+		error = page_cache_tree_insert(mapping, new, NULL);
+		BUG_ON(error);
+
+		/*
+		 * hugetlb pages do not participate in page cache accounting.
+		 */
+		if (!PageHuge(new))
+			__inc_zone_page_state(new, NR_FILE_PAGES);
+		if (PageSwapBacked(new))
+			__inc_zone_page_state(new, NR_SHMEM);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		mem_cgroup_end_page_stat(memcg);
+		mem_cgroup_replace_page(old, new);
+		radix_tree_preload_end();
+		if (freepage)
+			freepage(old);
+		page_cache_release(old);
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(replace_page_cache_page);
+
+static int __add_to_page_cache_locked(struct page *page,
+				      struct address_space *mapping,
+				      pgoff_t offset, gfp_t gfp_mask,
+				      void **shadowp)
+{
+	int huge = PageHuge(page);
+	struct mem_cgroup *memcg;
+	int error;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(PageSwapBacked(page), page);
+
+	if (!huge) {
+		error = mem_cgroup_try_charge(page, current->mm,
+					      gfp_mask, &memcg);
+		if (error)
+			return error;
+	}
+
+	error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM);
+	if (error) {
+		if (!huge)
+			mem_cgroup_cancel_charge(page, memcg);
+		return error;
+	}
+
+	page_cache_get(page);
+	page->mapping = mapping;
+	page->index = offset;
+
+	spin_lock_irq(&mapping->tree_lock);
+	error = page_cache_tree_insert(mapping, page, shadowp);
+	radix_tree_preload_end();
+	if (unlikely(error))
+		goto err_insert;
+
+	/* hugetlb pages do not participate in page cache accounting. */
+	if (!huge)
+		__inc_zone_page_state(page, NR_FILE_PAGES);
+	spin_unlock_irq(&mapping->tree_lock);
+	if (!huge)
+		mem_cgroup_commit_charge(page, memcg, false);
+	trace_mm_filemap_add_to_page_cache(page);
+	return 0;
+err_insert:
+	page->mapping = NULL;
+	/* Leave page->index set: truncation relies upon it */
+	spin_unlock_irq(&mapping->tree_lock);
+	if (!huge)
+		mem_cgroup_cancel_charge(page, memcg);
+	page_cache_release(page);
+	return error;
+}
+
+/**
+ * add_to_page_cache_locked - add a locked page to the pagecache
+ * @page:	page to add
+ * @mapping:	the page's address_space
+ * @offset:	page index
+ * @gfp_mask:	page allocation mode
+ *
+ * This function is used to add a page to the pagecache. It must be locked.
+ * This function does not add the page to the LRU.  The caller must do that.
+ */
+int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
+		pgoff_t offset, gfp_t gfp_mask)
+{
+	return __add_to_page_cache_locked(page, mapping, offset,
+					  gfp_mask, NULL);
+}
+EXPORT_SYMBOL(add_to_page_cache_locked);
+
+int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
+				pgoff_t offset, gfp_t gfp_mask)
+{
+	void *shadow = NULL;
+	int ret;
+
+	__set_page_locked(page);
+	ret = __add_to_page_cache_locked(page, mapping, offset,
+					 gfp_mask, &shadow);
+	if (unlikely(ret))
+		__clear_page_locked(page);
+	else {
+		/*
+		 * The page might have been evicted from cache only
+		 * recently, in which case it should be activated like
+		 * any other repeatedly accessed page.
+		 */
+		if (shadow && workingset_refault(shadow)) {
+			SetPageActive(page);
+			workingset_activation(page);
+		} else
+			ClearPageActive(page);
+		lru_cache_add(page);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
+
+#ifdef CONFIG_NUMA
+struct page *__page_cache_alloc(gfp_t gfp)
+{
+	int n;
+	struct page *page;
+
+	if (cpuset_do_page_mem_spread()) {
+		unsigned int cpuset_mems_cookie;
+		do {
+			cpuset_mems_cookie = read_mems_allowed_begin();
+			n = cpuset_mem_spread_node();
+			page = __alloc_pages_node(n, gfp, 0);
+		} while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
+
+		return page;
+	}
+	return alloc_pages(gfp, 0);
+}
+EXPORT_SYMBOL(__page_cache_alloc);
+#endif
+
+/*
+ * In order to wait for pages to become available there must be
+ * waitqueues associated with pages. By using a hash table of
+ * waitqueues where the bucket discipline is to maintain all
+ * waiters on the same queue and wake all when any of the pages
+ * become available, and for the woken contexts to check to be
+ * sure the appropriate page became available, this saves space
+ * at a cost of "thundering herd" phenomena during rare hash
+ * collisions.
+ */
+wait_queue_head_t *page_waitqueue(struct page *page)
+{
+	const struct zone *zone = page_zone(page);
+
+	return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
+}
+EXPORT_SYMBOL(page_waitqueue);
+
+void wait_on_page_bit(struct page *page, int bit_nr)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
+
+	if (test_bit(bit_nr, &page->flags))
+		__wait_on_bit(page_waitqueue(page), &wait, bit_wait_io,
+							TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL(wait_on_page_bit);
+
+int wait_on_page_bit_killable(struct page *page, int bit_nr)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
+
+	if (!test_bit(bit_nr, &page->flags))
+		return 0;
+
+	return __wait_on_bit(page_waitqueue(page), &wait,
+			     bit_wait_io, TASK_KILLABLE);
+}
+
+int wait_on_page_bit_killable_timeout(struct page *page,
+				       int bit_nr, unsigned long timeout)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
+
+	wait.key.timeout = jiffies + timeout;
+	if (!test_bit(bit_nr, &page->flags))
+		return 0;
+	return __wait_on_bit(page_waitqueue(page), &wait,
+			     bit_wait_io_timeout, TASK_KILLABLE);
+}
+EXPORT_SYMBOL_GPL(wait_on_page_bit_killable_timeout);
+
+/**
+ * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
+ * @page: Page defining the wait queue of interest
+ * @waiter: Waiter to add to the queue
+ *
+ * Add an arbitrary @waiter to the wait queue for the nominated @page.
+ */
+void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
+{
+	wait_queue_head_t *q = page_waitqueue(page);
+	unsigned long flags;
+
+	spin_lock_irqsave(&q->lock, flags);
+	__add_wait_queue(q, waiter);
+	spin_unlock_irqrestore(&q->lock, flags);
+}
+EXPORT_SYMBOL_GPL(add_page_wait_queue);
+
+/**
+ * unlock_page - unlock a locked page
+ * @page: the page
+ *
+ * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
+ * Also wakes sleepers in wait_on_page_writeback() because the wakeup
+ * mechanism between PageLocked pages and PageWriteback pages is shared.
+ * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
+ *
+ * The mb is necessary to enforce ordering between the clear_bit and the read
+ * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
+ */
+void unlock_page(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	clear_bit_unlock(PG_locked, &page->flags);
+	smp_mb__after_atomic();
+	wake_up_page(page, PG_locked);
+}
+EXPORT_SYMBOL(unlock_page);
+
+/**
+ * end_page_writeback - end writeback against a page
+ * @page: the page
+ */
+void end_page_writeback(struct page *page)
+{
+	/*
+	 * TestClearPageReclaim could be used here but it is an atomic
+	 * operation and overkill in this particular case. Failing to
+	 * shuffle a page marked for immediate reclaim is too mild to
+	 * justify taking an atomic operation penalty at the end of
+	 * ever page writeback.
+	 */
+	if (PageReclaim(page)) {
+		ClearPageReclaim(page);
+		rotate_reclaimable_page(page);
+	}
+
+	if (!test_clear_page_writeback(page))
+		BUG();
+
+	smp_mb__after_atomic();
+	wake_up_page(page, PG_writeback);
+}
+EXPORT_SYMBOL(end_page_writeback);
+
+/*
+ * After completing I/O on a page, call this routine to update the page
+ * flags appropriately
+ */
+void page_endio(struct page *page, int rw, int err)
+{
+	if (rw == READ) {
+		if (!err) {
+			SetPageUptodate(page);
+		} else {
+			ClearPageUptodate(page);
+			SetPageError(page);
+		}
+		unlock_page(page);
+	} else { /* rw == WRITE */
+		if (err) {
+			struct address_space *mapping;
+
+			SetPageError(page);
+			mapping = page_mapping(page);
+			if (mapping)
+				mapping_set_error(mapping, err);
+		}
+		end_page_writeback(page);
+	}
+}
+EXPORT_SYMBOL_GPL(page_endio);
+
+/**
+ * __lock_page - get a lock on the page, assuming we need to sleep to get it
+ * @page: the page to lock
+ */
+void __lock_page(struct page *page)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
+
+	__wait_on_bit_lock(page_waitqueue(page), &wait, bit_wait_io,
+							TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL(__lock_page);
+
+int __lock_page_killable(struct page *page)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
+
+	return __wait_on_bit_lock(page_waitqueue(page), &wait,
+					bit_wait_io, TASK_KILLABLE);
+}
+EXPORT_SYMBOL_GPL(__lock_page_killable);
+
+/*
+ * Return values:
+ * 1 - page is locked; mmap_sem is still held.
+ * 0 - page is not locked.
+ *     mmap_sem has been released (up_read()), unless flags had both
+ *     FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
+ *     which case mmap_sem is still held.
+ *
+ * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
+ * with the page locked and the mmap_sem unperturbed.
+ */
+int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+			 unsigned int flags)
+{
+	if (flags & FAULT_FLAG_ALLOW_RETRY) {
+		/*
+		 * CAUTION! In this case, mmap_sem is not released
+		 * even though return 0.
+		 */
+		if (flags & FAULT_FLAG_RETRY_NOWAIT)
+			return 0;
+
+		up_read(&mm->mmap_sem);
+		if (flags & FAULT_FLAG_KILLABLE)
+			wait_on_page_locked_killable(page);
+		else
+			wait_on_page_locked(page);
+		return 0;
+	} else {
+		if (flags & FAULT_FLAG_KILLABLE) {
+			int ret;
+
+			ret = __lock_page_killable(page);
+			if (ret) {
+				up_read(&mm->mmap_sem);
+				return 0;
+			}
+		} else
+			__lock_page(page);
+		return 1;
+	}
+}
+
+/**
+ * page_cache_next_hole - find the next hole (not-present entry)
+ * @mapping: mapping
+ * @index: index
+ * @max_scan: maximum range to search
+ *
+ * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the
+ * lowest indexed hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'return - index >=
+ * max_scan' will be true). In rare cases of index wrap-around, 0 will
+ * be returned.
+ *
+ * page_cache_next_hole may be called under rcu_read_lock. However,
+ * like radix_tree_gang_lookup, this will not atomically search a
+ * snapshot of the tree at a single point in time. For example, if a
+ * hole is created at index 5, then subsequently a hole is created at
+ * index 10, page_cache_next_hole covering both indexes may return 10
+ * if called under rcu_read_lock.
+ */
+pgoff_t page_cache_next_hole(struct address_space *mapping,
+			     pgoff_t index, unsigned long max_scan)
+{
+	unsigned long i;
+
+	for (i = 0; i < max_scan; i++) {
+		struct page *page;
+
+		page = radix_tree_lookup(&mapping->page_tree, index);
+		if (!page || radix_tree_exceptional_entry(page))
+			break;
+		index++;
+		if (index == 0)
+			break;
+	}
+
+	return index;
+}
+EXPORT_SYMBOL(page_cache_next_hole);
+
+/**
+ * page_cache_prev_hole - find the prev hole (not-present entry)
+ * @mapping: mapping
+ * @index: index
+ * @max_scan: maximum range to search
+ *
+ * Search backwards in the range [max(index-max_scan+1, 0), index] for
+ * the first hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'index - return >=
+ * max_scan' will be true). In rare cases of wrap-around, ULONG_MAX
+ * will be returned.
+ *
+ * page_cache_prev_hole may be called under rcu_read_lock. However,
+ * like radix_tree_gang_lookup, this will not atomically search a
+ * snapshot of the tree at a single point in time. For example, if a
+ * hole is created at index 10, then subsequently a hole is created at
+ * index 5, page_cache_prev_hole covering both indexes may return 5 if
+ * called under rcu_read_lock.
+ */
+pgoff_t page_cache_prev_hole(struct address_space *mapping,
+			     pgoff_t index, unsigned long max_scan)
+{
+	unsigned long i;
+
+	for (i = 0; i < max_scan; i++) {
+		struct page *page;
+
+		page = radix_tree_lookup(&mapping->page_tree, index);
+		if (!page || radix_tree_exceptional_entry(page))
+			break;
+		index--;
+		if (index == ULONG_MAX)
+			break;
+	}
+
+	return index;
+}
+EXPORT_SYMBOL(page_cache_prev_hole);
+
+/**
+ * find_get_entry - find and get a page cache entry
+ * @mapping: the address_space to search
+ * @offset: the page cache index
+ *
+ * Looks up the page cache slot at @mapping & @offset.  If there is a
+ * page cache page, it is returned with an increased refcount.
+ *
+ * If the slot holds a shadow entry of a previously evicted page, or a
+ * swap entry from shmem/tmpfs, it is returned.
+ *
+ * Otherwise, %NULL is returned.
+ */
+struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
+{
+	void **pagep;
+	struct page *page;
+
+	rcu_read_lock();
+repeat:
+	page = NULL;
+	pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
+	if (pagep) {
+		page = radix_tree_deref_slot(pagep);
+		if (unlikely(!page))
+			goto out;
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page))
+				goto repeat;
+			/*
+			 * A shadow entry of a recently evicted page,
+			 * or a swap entry from shmem/tmpfs.  Return
+			 * it without attempting to raise page count.
+			 */
+			goto out;
+		}
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/*
+		 * Has the page moved?
+		 * This is part of the lockless pagecache protocol. See
+		 * include/linux/pagemap.h for details.
+		 */
+		if (unlikely(page != *pagep)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+	}
+out:
+	rcu_read_unlock();
+
+	return page;
+}
+EXPORT_SYMBOL(find_get_entry);
+
+/**
+ * find_lock_entry - locate, pin and lock a page cache entry
+ * @mapping: the address_space to search
+ * @offset: the page cache index
+ *
+ * Looks up the page cache slot at @mapping & @offset.  If there is a
+ * page cache page, it is returned locked and with an increased
+ * refcount.
+ *
+ * If the slot holds a shadow entry of a previously evicted page, or a
+ * swap entry from shmem/tmpfs, it is returned.
+ *
+ * Otherwise, %NULL is returned.
+ *
+ * find_lock_entry() may sleep.
+ */
+struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
+{
+	struct page *page;
+
+repeat:
+	page = find_get_entry(mapping, offset);
+	if (page && !radix_tree_exception(page)) {
+		lock_page(page);
+		/* Has the page been truncated? */
+		if (unlikely(page->mapping != mapping)) {
+			unlock_page(page);
+			page_cache_release(page);
+			goto repeat;
+		}
+		VM_BUG_ON_PAGE(page->index != offset, page);
+	}
+	return page;
+}
+EXPORT_SYMBOL(find_lock_entry);
+
+/**
+ * pagecache_get_page - find and get a page reference
+ * @mapping: the address_space to search
+ * @offset: the page index
+ * @fgp_flags: PCG flags
+ * @gfp_mask: gfp mask to use for the page cache data page allocation
+ *
+ * Looks up the page cache slot at @mapping & @offset.
+ *
+ * PCG flags modify how the page is returned.
+ *
+ * FGP_ACCESSED: the page will be marked accessed
+ * FGP_LOCK: Page is return locked
+ * FGP_CREAT: If page is not present then a new page is allocated using
+ *		@gfp_mask and added to the page cache and the VM's LRU
+ *		list. The page is returned locked and with an increased
+ *		refcount. Otherwise, %NULL is returned.
+ *
+ * If FGP_LOCK or FGP_CREAT are specified then the function may sleep even
+ * if the GFP flags specified for FGP_CREAT are atomic.
+ *
+ * If there is a page cache page, it is returned with an increased refcount.
+ */
+struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
+	int fgp_flags, gfp_t gfp_mask)
+{
+	struct page *page;
+
+repeat:
+	page = find_get_entry(mapping, offset);
+	if (radix_tree_exceptional_entry(page))
+		page = NULL;
+	if (!page)
+		goto no_page;
+
+	if (fgp_flags & FGP_LOCK) {
+		if (fgp_flags & FGP_NOWAIT) {
+			if (!trylock_page(page)) {
+				page_cache_release(page);
+				return NULL;
+			}
+		} else {
+			lock_page(page);
+		}
+
+		/* Has the page been truncated? */
+		if (unlikely(page->mapping != mapping)) {
+			unlock_page(page);
+			page_cache_release(page);
+			goto repeat;
+		}
+		VM_BUG_ON_PAGE(page->index != offset, page);
+	}
+
+	if (page && (fgp_flags & FGP_ACCESSED))
+		mark_page_accessed(page);
+
+no_page:
+	if (!page && (fgp_flags & FGP_CREAT)) {
+		int err;
+		if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
+			gfp_mask |= __GFP_WRITE;
+		if (fgp_flags & FGP_NOFS)
+			gfp_mask &= ~__GFP_FS;
+
+		page = __page_cache_alloc(gfp_mask);
+		if (!page)
+			return NULL;
+
+		if (WARN_ON_ONCE(!(fgp_flags & FGP_LOCK)))
+			fgp_flags |= FGP_LOCK;
+
+		/* Init accessed so avoid atomic mark_page_accessed later */
+		if (fgp_flags & FGP_ACCESSED)
+			__SetPageReferenced(page);
+
+		err = add_to_page_cache_lru(page, mapping, offset,
+				gfp_mask & GFP_RECLAIM_MASK);
+		if (unlikely(err)) {
+			page_cache_release(page);
+			page = NULL;
+			if (err == -EEXIST)
+				goto repeat;
+		}
+	}
+
+	return page;
+}
+EXPORT_SYMBOL(pagecache_get_page);
+
+/**
+ * find_get_entries - gang pagecache lookup
+ * @mapping:	The address_space to search
+ * @start:	The starting page cache index
+ * @nr_entries:	The maximum number of entries
+ * @entries:	Where the resulting entries are placed
+ * @indices:	The cache indices corresponding to the entries in @entries
+ *
+ * find_get_entries() will search for and return a group of up to
+ * @nr_entries entries in the mapping.  The entries are placed at
+ * @entries.  find_get_entries() takes a reference against any actual
+ * pages it returns.
+ *
+ * The search returns a group of mapping-contiguous page cache entries
+ * with ascending indexes.  There may be holes in the indices due to
+ * not-present pages.
+ *
+ * Any shadow entries of evicted pages, or swap entries from
+ * shmem/tmpfs, are included in the returned array.
+ *
+ * find_get_entries() returns the number of pages and shadow entries
+ * which were found.
+ */
+unsigned find_get_entries(struct address_space *mapping,
+			  pgoff_t start, unsigned int nr_entries,
+			  struct page **entries, pgoff_t *indices)
+{
+	void **slot;
+	unsigned int ret = 0;
+	struct radix_tree_iter iter;
+
+	if (!nr_entries)
+		return 0;
+
+	rcu_read_lock();
+restart:
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+		struct page *page;
+repeat:
+		page = radix_tree_deref_slot(slot);
+		if (unlikely(!page))
+			continue;
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page))
+				goto restart;
+			/*
+			 * A shadow entry of a recently evicted page,
+			 * or a swap entry from shmem/tmpfs.  Return
+			 * it without attempting to raise page count.
+			 */
+			goto export;
+		}
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/* Has the page moved? */
+		if (unlikely(page != *slot)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+export:
+		indices[ret] = iter.index;
+		entries[ret] = page;
+		if (++ret == nr_entries)
+			break;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+/**
+ * find_get_pages - gang pagecache lookup
+ * @mapping:	The address_space to search
+ * @start:	The starting page index
+ * @nr_pages:	The maximum number of pages
+ * @pages:	Where the resulting pages are placed
+ *
+ * find_get_pages() will search for and return a group of up to
+ * @nr_pages pages in the mapping.  The pages are placed at @pages.
+ * find_get_pages() takes a reference against the returned pages.
+ *
+ * The search returns a group of mapping-contiguous pages with ascending
+ * indexes.  There may be holes in the indices due to not-present pages.
+ *
+ * find_get_pages() returns the number of pages which were found.
+ */
+unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
+			    unsigned int nr_pages, struct page **pages)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	unsigned ret = 0;
+
+	if (unlikely(!nr_pages))
+		return 0;
+
+	rcu_read_lock();
+restart:
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+		struct page *page;
+repeat:
+		page = radix_tree_deref_slot(slot);
+		if (unlikely(!page))
+			continue;
+
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				WARN_ON(iter.index);
+				goto restart;
+			}
+			/*
+			 * A shadow entry of a recently evicted page,
+			 * or a swap entry from shmem/tmpfs.  Skip
+			 * over it.
+			 */
+			continue;
+		}
+
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/* Has the page moved? */
+		if (unlikely(page != *slot)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+
+		pages[ret] = page;
+		if (++ret == nr_pages)
+			break;
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+/**
+ * find_get_pages_contig - gang contiguous pagecache lookup
+ * @mapping:	The address_space to search
+ * @index:	The starting page index
+ * @nr_pages:	The maximum number of pages
+ * @pages:	Where the resulting pages are placed
+ *
+ * find_get_pages_contig() works exactly like find_get_pages(), except
+ * that the returned number of pages are guaranteed to be contiguous.
+ *
+ * find_get_pages_contig() returns the number of pages which were found.
+ */
+unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
+			       unsigned int nr_pages, struct page **pages)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	unsigned int ret = 0;
+
+	if (unlikely(!nr_pages))
+		return 0;
+
+	rcu_read_lock();
+restart:
+	radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
+		struct page *page;
+repeat:
+		page = radix_tree_deref_slot(slot);
+		/* The hole, there no reason to continue */
+		if (unlikely(!page))
+			break;
+
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				goto restart;
+			}
+			/*
+			 * A shadow entry of a recently evicted page,
+			 * or a swap entry from shmem/tmpfs.  Stop
+			 * looking for contiguous pages.
+			 */
+			break;
+		}
+
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/* Has the page moved? */
+		if (unlikely(page != *slot)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+
+		/*
+		 * must check mapping and index after taking the ref.
+		 * otherwise we can get both false positives and false
+		 * negatives, which is just confusing to the caller.
+		 */
+		if (page->mapping == NULL || page->index != iter.index) {
+			page_cache_release(page);
+			break;
+		}
+
+		pages[ret] = page;
+		if (++ret == nr_pages)
+			break;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL(find_get_pages_contig);
+
+/**
+ * find_get_pages_tag - find and return pages that match @tag
+ * @mapping:	the address_space to search
+ * @index:	the starting page index
+ * @tag:	the tag index
+ * @nr_pages:	the maximum number of pages
+ * @pages:	where the resulting pages are placed
+ *
+ * Like find_get_pages, except we only return pages which are tagged with
+ * @tag.   We update @index to index the next page for the traversal.
+ */
+unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
+			int tag, unsigned int nr_pages, struct page **pages)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	unsigned ret = 0;
+
+	if (unlikely(!nr_pages))
+		return 0;
+
+	rcu_read_lock();
+restart:
+	radix_tree_for_each_tagged(slot, &mapping->page_tree,
+				   &iter, *index, tag) {
+		struct page *page;
+repeat:
+		page = radix_tree_deref_slot(slot);
+		if (unlikely(!page))
+			continue;
+
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				goto restart;
+			}
+			/*
+			 * A shadow entry of a recently evicted page.
+			 *
+			 * Those entries should never be tagged, but
+			 * this tree walk is lockless and the tags are
+			 * looked up in bulk, one radix tree node at a
+			 * time, so there is a sizable window for page
+			 * reclaim to evict a page we saw tagged.
+			 *
+			 * Skip over it.
+			 */
+			continue;
+		}
+
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/* Has the page moved? */
+		if (unlikely(page != *slot)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+
+		pages[ret] = page;
+		if (++ret == nr_pages)
+			break;
+	}
+
+	rcu_read_unlock();
+
+	if (ret)
+		*index = pages[ret - 1]->index + 1;
+
+	return ret;
+}
+EXPORT_SYMBOL(find_get_pages_tag);
+
+/*
+ * CD/DVDs are error prone. When a medium error occurs, the driver may fail
+ * a _large_ part of the i/o request. Imagine the worst scenario:
+ *
+ *      ---R__________________________________________B__________
+ *         ^ reading here                             ^ bad block(assume 4k)
+ *
+ * read(R) => miss => readahead(R...B) => media error => frustrating retries
+ * => failing the whole request => read(R) => read(R+1) =>
+ * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
+ * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
+ * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
+ *
+ * It is going insane. Fix it by quickly scaling down the readahead size.
+ */
+static void shrink_readahead_size_eio(struct file *filp,
+					struct file_ra_state *ra)
+{
+	ra->ra_pages /= 4;
+}
+
+/**
+ * do_generic_file_read - generic file read routine
+ * @filp:	the file to read
+ * @ppos:	current file position
+ * @iter:	data destination
+ * @written:	already copied
+ *
+ * This is a generic file read routine, and uses the
+ * mapping->a_ops->readpage() function for the actual low-level stuff.
+ *
+ * This is really ugly. But the goto's actually try to clarify some
+ * of the logic when it comes to error handling etc.
+ */
+static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
+		struct iov_iter *iter, ssize_t written)
+{
+	struct address_space *mapping = filp->f_mapping;
+	struct inode *inode = mapping->host;
+	struct file_ra_state *ra = &filp->f_ra;
+	pgoff_t index;
+	pgoff_t last_index;
+	pgoff_t prev_index;
+	unsigned long offset;      /* offset into pagecache page */
+	unsigned int prev_offset;
+	int error = 0;
+
+	index = *ppos >> PAGE_CACHE_SHIFT;
+	prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
+	prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
+	last_index = (*ppos + iter->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
+	offset = *ppos & ~PAGE_CACHE_MASK;
+
+	for (;;) {
+		struct page *page;
+		pgoff_t end_index;
+		loff_t isize;
+		unsigned long nr, ret;
+
+		cond_resched();
+find_page:
+		if (fatal_signal_pending(current)) {
+			error = -EINTR;
+			goto out;
+		}
+
+		page = find_get_page(mapping, index);
+		if (!page) {
+			page_cache_sync_readahead(mapping,
+					ra, filp,
+					index, last_index - index);
+			page = find_get_page(mapping, index);
+			if (unlikely(page == NULL))
+				goto no_cached_page;
+		}
+		if (PageReadahead(page)) {
+			page_cache_async_readahead(mapping,
+					ra, filp, page,
+					index, last_index - index);
+		}
+		if (!PageUptodate(page)) {
+			if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
+					!mapping->a_ops->is_partially_uptodate)
+				goto page_not_up_to_date;
+			if (!trylock_page(page))
+				goto page_not_up_to_date;
+			/* Did it get truncated before we got the lock? */
+			if (!page->mapping)
+				goto page_not_up_to_date_locked;
+			if (!mapping->a_ops->is_partially_uptodate(page,
+							offset, iter->count))
+				goto page_not_up_to_date_locked;
+			unlock_page(page);
+		}
+page_ok:
+		/*
+		 * i_size must be checked after we know the page is Uptodate.
+		 *
+		 * Checking i_size after the check allows us to calculate
+		 * the correct value for "nr", which means the zero-filled
+		 * part of the page is not copied back to userspace (unless
+		 * another truncate extends the file - this is desired though).
+		 */
+
+		isize = i_size_read(inode);
+		end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+		if (unlikely(!isize || index > end_index)) {
+			page_cache_release(page);
+			goto out;
+		}
+
+		/* nr is the maximum number of bytes to copy from this page */
+		nr = PAGE_CACHE_SIZE;
+		if (index == end_index) {
+			nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
+			if (nr <= offset) {
+				page_cache_release(page);
+				goto out;
+			}
+		}
+		nr = nr - offset;
+
+		/* If users can be writing to this page using arbitrary
+		 * virtual addresses, take care about potential aliasing
+		 * before reading the page on the kernel side.
+		 */
+		if (mapping_writably_mapped(mapping))
+			flush_dcache_page(page);
+
+		/*
+		 * When a sequential read accesses a page several times,
+		 * only mark it as accessed the first time.
+		 */
+		if (prev_index != index || offset != prev_offset)
+			mark_page_accessed(page);
+		prev_index = index;
+
+		/*
+		 * Ok, we have the page, and it's up-to-date, so
+		 * now we can copy it to user space...
+		 */
+
+		ret = copy_page_to_iter(page, offset, nr, iter);
+		offset += ret;
+		index += offset >> PAGE_CACHE_SHIFT;
+		offset &= ~PAGE_CACHE_MASK;
+		prev_offset = offset;
+
+		page_cache_release(page);
+		written += ret;
+		if (!iov_iter_count(iter))
+			goto out;
+		if (ret < nr) {
+			error = -EFAULT;
+			goto out;
+		}
+		continue;
+
+page_not_up_to_date:
+		/* Get exclusive access to the page ... */
+		error = lock_page_killable(page);
+		if (unlikely(error))
+			goto readpage_error;
+
+page_not_up_to_date_locked:
+		/* Did it get truncated before we got the lock? */
+		if (!page->mapping) {
+			unlock_page(page);
+			page_cache_release(page);
+			continue;
+		}
+
+		/* Did somebody else fill it already? */
+		if (PageUptodate(page)) {
+			unlock_page(page);
+			goto page_ok;
+		}
+
+readpage:
+		/*
+		 * A previous I/O error may have been due to temporary
+		 * failures, eg. multipath errors.
+		 * PG_error will be set again if readpage fails.
+		 */
+		ClearPageError(page);
+		/* Start the actual read. The read will unlock the page. */
+		error = mapping->a_ops->readpage(filp, page);
+
+		if (unlikely(error)) {
+			if (error == AOP_TRUNCATED_PAGE) {
+				page_cache_release(page);
+				error = 0;
+				goto find_page;
+			}
+			goto readpage_error;
+		}
+
+		if (!PageUptodate(page)) {
+			error = lock_page_killable(page);
+			if (unlikely(error))
+				goto readpage_error;
+			if (!PageUptodate(page)) {
+				if (page->mapping == NULL) {
+					/*
+					 * invalidate_mapping_pages got it
+					 */
+					unlock_page(page);
+					page_cache_release(page);
+					goto find_page;
+				}
+				unlock_page(page);
+				shrink_readahead_size_eio(filp, ra);
+				error = -EIO;
+				goto readpage_error;
+			}
+			unlock_page(page);
+		}
+
+		goto page_ok;
+
+readpage_error:
+		/* UHHUH! A synchronous read error occurred. Report it */
+		page_cache_release(page);
+		goto out;
+
+no_cached_page:
+		/*
+		 * Ok, it wasn't cached, so we need to create a new
+		 * page..
+		 */
+		page = page_cache_alloc_cold(mapping);
+		if (!page) {
+			error = -ENOMEM;
+			goto out;
+		}
+		error = add_to_page_cache_lru(page, mapping, index,
+				mapping_gfp_constraint(mapping, GFP_KERNEL));
+		if (error) {
+			page_cache_release(page);
+			if (error == -EEXIST) {
+				error = 0;
+				goto find_page;
+			}
+			goto out;
+		}
+		goto readpage;
+	}
+
+out:
+	ra->prev_pos = prev_index;
+	ra->prev_pos <<= PAGE_CACHE_SHIFT;
+	ra->prev_pos |= prev_offset;
+
+	*ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
+	file_accessed(filp);
+	return written ? written : error;
+}
+
+/**
+ * generic_file_read_iter - generic filesystem read routine
+ * @iocb:	kernel I/O control block
+ * @iter:	destination for the data read
+ *
+ * This is the "read_iter()" routine for all filesystems
+ * that can use the page cache directly.
+ */
+ssize_t
+generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+	struct file *file = iocb->ki_filp;
+	ssize_t retval = 0;
+	loff_t *ppos = &iocb->ki_pos;
+	loff_t pos = *ppos;
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		struct address_space *mapping = file->f_mapping;
+		struct inode *inode = mapping->host;
+		size_t count = iov_iter_count(iter);
+		loff_t size;
+
+		if (!count)
+			goto out; /* skip atime */
+		size = i_size_read(inode);
+		retval = filemap_write_and_wait_range(mapping, pos,
+					pos + count - 1);
+		if (!retval) {
+			struct iov_iter data = *iter;
+			retval = mapping->a_ops->direct_IO(iocb, &data, pos);
+		}
+
+		if (retval > 0) {
+			*ppos = pos + retval;
+			iov_iter_advance(iter, retval);
+		}
+
+		/*
+		 * Btrfs can have a short DIO read if we encounter
+		 * compressed extents, so if there was an error, or if
+		 * we've already read everything we wanted to, or if
+		 * there was a short read because we hit EOF, go ahead
+		 * and return.  Otherwise fallthrough to buffered io for
+		 * the rest of the read.  Buffered reads will not work for
+		 * DAX files, so don't bother trying.
+		 */
+		if (retval < 0 || !iov_iter_count(iter) || *ppos >= size ||
+		    IS_DAX(inode)) {
+			file_accessed(file);
+			goto out;
+		}
+	}
+
+	retval = do_generic_file_read(file, ppos, iter, retval);
+out:
+	return retval;
+}
+EXPORT_SYMBOL(generic_file_read_iter);
+
+#ifdef CONFIG_MMU
+/**
+ * page_cache_read - adds requested page to the page cache if not already there
+ * @file:	file to read
+ * @offset:	page index
+ *
+ * This adds the requested page to the page cache if it isn't already there,
+ * and schedules an I/O to read in its contents from disk.
+ */
+static int page_cache_read(struct file *file, pgoff_t offset)
+{
+	struct address_space *mapping = file->f_mapping;
+	struct page *page;
+	int ret;
+
+	do {
+		page = page_cache_alloc_cold(mapping);
+		if (!page)
+			return -ENOMEM;
+
+		ret = add_to_page_cache_lru(page, mapping, offset,
+				mapping_gfp_constraint(mapping, GFP_KERNEL));
+		if (ret == 0)
+			ret = mapping->a_ops->readpage(file, page);
+		else if (ret == -EEXIST)
+			ret = 0; /* losing race to add is OK */
+
+		page_cache_release(page);
+
+	} while (ret == AOP_TRUNCATED_PAGE);
+
+	return ret;
+}
+
+#define MMAP_LOTSAMISS  (100)
+
+/*
+ * Synchronous readahead happens when we don't even find
+ * a page in the page cache at all.
+ */
+static void do_sync_mmap_readahead(struct vm_area_struct *vma,
+				   struct file_ra_state *ra,
+				   struct file *file,
+				   pgoff_t offset)
+{
+	struct address_space *mapping = file->f_mapping;
+
+	/* If we don't want any read-ahead, don't bother */
+	if (vma->vm_flags & VM_RAND_READ)
+		return;
+	if (!ra->ra_pages)
+		return;
+
+	if (vma->vm_flags & VM_SEQ_READ) {
+		page_cache_sync_readahead(mapping, ra, file, offset,
+					  ra->ra_pages);
+		return;
+	}
+
+	/* Avoid banging the cache line if not needed */
+	if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
+		ra->mmap_miss++;
+
+	/*
+	 * Do we miss much more than hit in this file? If so,
+	 * stop bothering with read-ahead. It will only hurt.
+	 */
+	if (ra->mmap_miss > MMAP_LOTSAMISS)
+		return;
+
+	/*
+	 * mmap read-around
+	 */
+	ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
+	ra->size = ra->ra_pages;
+	ra->async_size = ra->ra_pages / 4;
+	ra_submit(ra, mapping, file);
+}
+
+/*
+ * Asynchronous readahead happens when we find the page and PG_readahead,
+ * so we want to possibly extend the readahead further..
+ */
+static void do_async_mmap_readahead(struct vm_area_struct *vma,
+				    struct file_ra_state *ra,
+				    struct file *file,
+				    struct page *page,
+				    pgoff_t offset)
+{
+	struct address_space *mapping = file->f_mapping;
+
+	/* If we don't want any read-ahead, don't bother */
+	if (vma->vm_flags & VM_RAND_READ)
+		return;
+	if (ra->mmap_miss > 0)
+		ra->mmap_miss--;
+	if (PageReadahead(page))
+		page_cache_async_readahead(mapping, ra, file,
+					   page, offset, ra->ra_pages);
+}
+
+/**
+ * filemap_fault - read in file data for page fault handling
+ * @vma:	vma in which the fault was taken
+ * @vmf:	struct vm_fault containing details of the fault
+ *
+ * filemap_fault() is invoked via the vma operations vector for a
+ * mapped memory region to read in file data during a page fault.
+ *
+ * The goto's are kind of ugly, but this streamlines the normal case of having
+ * it in the page cache, and handles the special cases reasonably without
+ * having a lot of duplicated code.
+ *
+ * vma->vm_mm->mmap_sem must be held on entry.
+ *
+ * If our return value has VM_FAULT_RETRY set, it's because
+ * lock_page_or_retry() returned 0.
+ * The mmap_sem has usually been released in this case.
+ * See __lock_page_or_retry() for the exception.
+ *
+ * If our return value does not have VM_FAULT_RETRY set, the mmap_sem
+ * has not been released.
+ *
+ * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
+ */
+int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	int error;
+	struct file *file = vma->vm_file;
+	struct address_space *mapping = file->f_mapping;
+	struct file_ra_state *ra = &file->f_ra;
+	struct inode *inode = mapping->host;
+	pgoff_t offset = vmf->pgoff;
+	struct page *page;
+	loff_t size;
+	int ret = 0;
+
+	size = round_up(i_size_read(inode), PAGE_CACHE_SIZE);
+	if (offset >= size >> PAGE_CACHE_SHIFT)
+		return VM_FAULT_SIGBUS;
+
+	/*
+	 * Do we have something in the page cache already?
+	 */
+	page = find_get_page(mapping, offset);
+	if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
+		/*
+		 * We found the page, so try async readahead before
+		 * waiting for the lock.
+		 */
+		do_async_mmap_readahead(vma, ra, file, page, offset);
+	} else if (!page) {
+		/* No page in the page cache at all */
+		do_sync_mmap_readahead(vma, ra, file, offset);
+		count_vm_event(PGMAJFAULT);
+		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+		ret = VM_FAULT_MAJOR;
+retry_find:
+		page = find_get_page(mapping, offset);
+		if (!page)
+			goto no_cached_page;
+	}
+
+	if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
+		page_cache_release(page);
+		return ret | VM_FAULT_RETRY;
+	}
+
+	/* Did it get truncated? */
+	if (unlikely(page->mapping != mapping)) {
+		unlock_page(page);
+		put_page(page);
+		goto retry_find;
+	}
+	VM_BUG_ON_PAGE(page->index != offset, page);
+
+	/*
+	 * We have a locked page in the page cache, now we need to check
+	 * that it's up-to-date. If not, it is going to be due to an error.
+	 */
+	if (unlikely(!PageUptodate(page)))
+		goto page_not_uptodate;
+
+	/*
+	 * Found the page and have a reference on it.
+	 * We must recheck i_size under page lock.
+	 */
+	size = round_up(i_size_read(inode), PAGE_CACHE_SIZE);
+	if (unlikely(offset >= size >> PAGE_CACHE_SHIFT)) {
+		unlock_page(page);
+		page_cache_release(page);
+		return VM_FAULT_SIGBUS;
+	}
+
+	vmf->page = page;
+	return ret | VM_FAULT_LOCKED;
+
+no_cached_page:
+	/*
+	 * We're only likely to ever get here if MADV_RANDOM is in
+	 * effect.
+	 */
+	error = page_cache_read(file, offset);
+
+	/*
+	 * The page we want has now been added to the page cache.
+	 * In the unlikely event that someone removed it in the
+	 * meantime, we'll just come back here and read it again.
+	 */
+	if (error >= 0)
+		goto retry_find;
+
+	/*
+	 * An error return from page_cache_read can result if the
+	 * system is low on memory, or a problem occurs while trying
+	 * to schedule I/O.
+	 */
+	if (error == -ENOMEM)
+		return VM_FAULT_OOM;
+	return VM_FAULT_SIGBUS;
+
+page_not_uptodate:
+	/*
+	 * Umm, take care of errors if the page isn't up-to-date.
+	 * Try to re-read it _once_. We do this synchronously,
+	 * because there really aren't any performance issues here
+	 * and we need to check for errors.
+	 */
+	ClearPageError(page);
+	error = mapping->a_ops->readpage(file, page);
+	if (!error) {
+		wait_on_page_locked(page);
+		if (!PageUptodate(page))
+			error = -EIO;
+	}
+	page_cache_release(page);
+
+	if (!error || error == AOP_TRUNCATED_PAGE)
+		goto retry_find;
+
+	/* Things didn't work out. Return zero to tell the mm layer so. */
+	shrink_readahead_size_eio(file, ra);
+	return VM_FAULT_SIGBUS;
+}
+EXPORT_SYMBOL(filemap_fault);
+
+void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	struct file *file = vma->vm_file;
+	struct address_space *mapping = file->f_mapping;
+	loff_t size;
+	struct page *page;
+	unsigned long address = (unsigned long) vmf->virtual_address;
+	unsigned long addr;
+	pte_t *pte;
+
+	rcu_read_lock();
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff) {
+		if (iter.index > vmf->max_pgoff)
+			break;
+repeat:
+		page = radix_tree_deref_slot(slot);
+		if (unlikely(!page))
+			goto next;
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page))
+				break;
+			else
+				goto next;
+		}
+
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/* Has the page moved? */
+		if (unlikely(page != *slot)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+
+		if (!PageUptodate(page) ||
+				PageReadahead(page) ||
+				PageHWPoison(page))
+			goto skip;
+		if (!trylock_page(page))
+			goto skip;
+
+		if (page->mapping != mapping || !PageUptodate(page))
+			goto unlock;
+
+		size = round_up(i_size_read(mapping->host), PAGE_CACHE_SIZE);
+		if (page->index >= size >> PAGE_CACHE_SHIFT)
+			goto unlock;
+
+		pte = vmf->pte + page->index - vmf->pgoff;
+		if (!pte_none(*pte))
+			goto unlock;
+
+		if (file->f_ra.mmap_miss > 0)
+			file->f_ra.mmap_miss--;
+		addr = address + (page->index - vmf->pgoff) * PAGE_SIZE;
+		do_set_pte(vma, addr, page, pte, false, false);
+		unlock_page(page);
+		goto next;
+unlock:
+		unlock_page(page);
+skip:
+		page_cache_release(page);
+next:
+		if (iter.index == vmf->max_pgoff)
+			break;
+	}
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(filemap_map_pages);
+
+int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct inode *inode = file_inode(vma->vm_file);
+	int ret = VM_FAULT_LOCKED;
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vma->vm_file);
+	lock_page(page);
+	if (page->mapping != inode->i_mapping) {
+		unlock_page(page);
+		ret = VM_FAULT_NOPAGE;
+		goto out;
+	}
+	/*
+	 * We mark the page dirty already here so that when freeze is in
+	 * progress, we are guaranteed that writeback during freezing will
+	 * see the dirty page and writeprotect it again.
+	 */
+	set_page_dirty(page);
+	wait_for_stable_page(page);
+out:
+	sb_end_pagefault(inode->i_sb);
+	return ret;
+}
+EXPORT_SYMBOL(filemap_page_mkwrite);
+
+const struct vm_operations_struct generic_file_vm_ops = {
+	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite	= filemap_page_mkwrite,
+};
+
+/* This is used for a general mmap of a disk file */
+
+int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
+{
+	struct address_space *mapping = file->f_mapping;
+
+	if (!mapping->a_ops->readpage)
+		return -ENOEXEC;
+	file_accessed(file);
+	vma->vm_ops = &generic_file_vm_ops;
+	return 0;
+}
+
+/*
+ * This is for filesystems which do not implement ->writepage.
+ */
+int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
+		return -EINVAL;
+	return generic_file_mmap(file, vma);
+}
+#else
+int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
+{
+	return -ENOSYS;
+}
+int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
+{
+	return -ENOSYS;
+}
+#endif /* CONFIG_MMU */
+
+EXPORT_SYMBOL(generic_file_mmap);
+EXPORT_SYMBOL(generic_file_readonly_mmap);
+
+static struct page *wait_on_page_read(struct page *page)
+{
+	if (!IS_ERR(page)) {
+		wait_on_page_locked(page);
+		if (!PageUptodate(page)) {
+			page_cache_release(page);
+			page = ERR_PTR(-EIO);
+		}
+	}
+	return page;
+}
+
+static struct page *__read_cache_page(struct address_space *mapping,
+				pgoff_t index,
+				int (*filler)(void *, struct page *),
+				void *data,
+				gfp_t gfp)
+{
+	struct page *page;
+	int err;
+repeat:
+	page = find_get_page(mapping, index);
+	if (!page) {
+		page = __page_cache_alloc(gfp | __GFP_COLD);
+		if (!page)
+			return ERR_PTR(-ENOMEM);
+		err = add_to_page_cache_lru(page, mapping, index, gfp);
+		if (unlikely(err)) {
+			page_cache_release(page);
+			if (err == -EEXIST)
+				goto repeat;
+			/* Presumably ENOMEM for radix tree node */
+			return ERR_PTR(err);
+		}
+		err = filler(data, page);
+		if (err < 0) {
+			page_cache_release(page);
+			page = ERR_PTR(err);
+		} else {
+			page = wait_on_page_read(page);
+		}
+	}
+	return page;
+}
+
+static struct page *do_read_cache_page(struct address_space *mapping,
+				pgoff_t index,
+				int (*filler)(void *, struct page *),
+				void *data,
+				gfp_t gfp)
+
+{
+	struct page *page;
+	int err;
+
+retry:
+	page = __read_cache_page(mapping, index, filler, data, gfp);
+	if (IS_ERR(page))
+		return page;
+	if (PageUptodate(page))
+		goto out;
+
+	lock_page(page);
+	if (!page->mapping) {
+		unlock_page(page);
+		page_cache_release(page);
+		goto retry;
+	}
+	if (PageUptodate(page)) {
+		unlock_page(page);
+		goto out;
+	}
+	err = filler(data, page);
+	if (err < 0) {
+		page_cache_release(page);
+		return ERR_PTR(err);
+	} else {
+		page = wait_on_page_read(page);
+		if (IS_ERR(page))
+			return page;
+	}
+out:
+	mark_page_accessed(page);
+	return page;
+}
+
+/**
+ * read_cache_page - read into page cache, fill it if needed
+ * @mapping:	the page's address_space
+ * @index:	the page index
+ * @filler:	function to perform the read
+ * @data:	first arg to filler(data, page) function, often left as NULL
+ *
+ * Read into the page cache. If a page already exists, and PageUptodate() is
+ * not set, try to fill the page and wait for it to become unlocked.
+ *
+ * If the page does not get brought uptodate, return -EIO.
+ */
+struct page *read_cache_page(struct address_space *mapping,
+				pgoff_t index,
+				int (*filler)(void *, struct page *),
+				void *data)
+{
+	return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
+}
+EXPORT_SYMBOL(read_cache_page);
+
+/**
+ * read_cache_page_gfp - read into page cache, using specified page allocation flags.
+ * @mapping:	the page's address_space
+ * @index:	the page index
+ * @gfp:	the page allocator flags to use if allocating
+ *
+ * This is the same as "read_mapping_page(mapping, index, NULL)", but with
+ * any new page allocations done using the specified allocation flags.
+ *
+ * If the page does not get brought uptodate, return -EIO.
+ */
+struct page *read_cache_page_gfp(struct address_space *mapping,
+				pgoff_t index,
+				gfp_t gfp)
+{
+	filler_t *filler = (filler_t *)mapping->a_ops->readpage;
+
+	return do_read_cache_page(mapping, index, filler, NULL, gfp);
+}
+EXPORT_SYMBOL(read_cache_page_gfp);
+
+/*
+ * Performs necessary checks before doing a write
+ *
+ * Can adjust writing position or amount of bytes to write.
+ * Returns appropriate error code that caller should return or
+ * zero in case that write should be allowed.
+ */
+inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	unsigned long limit = rlimit(RLIMIT_FSIZE);
+	loff_t pos;
+
+	if (!iov_iter_count(from))
+		return 0;
+
+	/* FIXME: this is for backwards compatibility with 2.4 */
+	if (iocb->ki_flags & IOCB_APPEND)
+		iocb->ki_pos = i_size_read(inode);
+
+	pos = iocb->ki_pos;
+
+	if (limit != RLIM_INFINITY) {
+		if (iocb->ki_pos >= limit) {
+			send_sig(SIGXFSZ, current, 0);
+			return -EFBIG;
+		}
+		iov_iter_truncate(from, limit - (unsigned long)pos);
+	}
+
+	/*
+	 * LFS rule
+	 */
+	if (unlikely(pos + iov_iter_count(from) > MAX_NON_LFS &&
+				!(file->f_flags & O_LARGEFILE))) {
+		if (pos >= MAX_NON_LFS)
+			return -EFBIG;
+		iov_iter_truncate(from, MAX_NON_LFS - (unsigned long)pos);
+	}
+
+	/*
+	 * Are we about to exceed the fs block limit ?
+	 *
+	 * If we have written data it becomes a short write.  If we have
+	 * exceeded without writing data we send a signal and return EFBIG.
+	 * Linus frestrict idea will clean these up nicely..
+	 */
+	if (unlikely(pos >= inode->i_sb->s_maxbytes))
+		return -EFBIG;
+
+	iov_iter_truncate(from, inode->i_sb->s_maxbytes - pos);
+	return iov_iter_count(from);
+}
+EXPORT_SYMBOL(generic_write_checks);
+
+int pagecache_write_begin(struct file *file, struct address_space *mapping,
+				loff_t pos, unsigned len, unsigned flags,
+				struct page **pagep, void **fsdata)
+{
+	const struct address_space_operations *aops = mapping->a_ops;
+
+	return aops->write_begin(file, mapping, pos, len, flags,
+							pagep, fsdata);
+}
+EXPORT_SYMBOL(pagecache_write_begin);
+
+int pagecache_write_end(struct file *file, struct address_space *mapping,
+				loff_t pos, unsigned len, unsigned copied,
+				struct page *page, void *fsdata)
+{
+	const struct address_space_operations *aops = mapping->a_ops;
+
+	return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
+}
+EXPORT_SYMBOL(pagecache_write_end);
+
+ssize_t
+generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos)
+{
+	struct file	*file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode	*inode = mapping->host;
+	ssize_t		written;
+	size_t		write_len;
+	pgoff_t		end;
+	struct iov_iter data;
+
+	write_len = iov_iter_count(from);
+	end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
+
+	written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
+	if (written)
+		goto out;
+
+	/*
+	 * After a write we want buffered reads to be sure to go to disk to get
+	 * the new data.  We invalidate clean cached page from the region we're
+	 * about to write.  We do this *before* the write so that we can return
+	 * without clobbering -EIOCBQUEUED from ->direct_IO().
+	 */
+	if (mapping->nrpages) {
+		written = invalidate_inode_pages2_range(mapping,
+					pos >> PAGE_CACHE_SHIFT, end);
+		/*
+		 * If a page can not be invalidated, return 0 to fall back
+		 * to buffered write.
+		 */
+		if (written) {
+			if (written == -EBUSY)
+				return 0;
+			goto out;
+		}
+	}
+
+	data = *from;
+	written = mapping->a_ops->direct_IO(iocb, &data, pos);
+
+	/*
+	 * Finally, try again to invalidate clean pages which might have been
+	 * cached by non-direct readahead, or faulted in by get_user_pages()
+	 * if the source of the write was an mmap'ed region of the file
+	 * we're writing.  Either one is a pretty crazy thing to do,
+	 * so we don't support it 100%.  If this invalidation
+	 * fails, tough, the write still worked...
+	 */
+	if (mapping->nrpages) {
+		invalidate_inode_pages2_range(mapping,
+					      pos >> PAGE_CACHE_SHIFT, end);
+	}
+
+	if (written > 0) {
+		pos += written;
+		iov_iter_advance(from, written);
+		if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
+			i_size_write(inode, pos);
+			mark_inode_dirty(inode);
+		}
+		iocb->ki_pos = pos;
+	}
+out:
+	return written;
+}
+EXPORT_SYMBOL(generic_file_direct_write);
+
+/*
+ * Find or create a page at the given pagecache position. Return the locked
+ * page. This function is specifically for buffered writes.
+ */
+struct page *grab_cache_page_write_begin(struct address_space *mapping,
+					pgoff_t index, unsigned flags)
+{
+	struct page *page;
+	int fgp_flags = FGP_LOCK|FGP_ACCESSED|FGP_WRITE|FGP_CREAT;
+
+	if (flags & AOP_FLAG_NOFS)
+		fgp_flags |= FGP_NOFS;
+
+	page = pagecache_get_page(mapping, index, fgp_flags,
+			mapping_gfp_mask(mapping));
+	if (page)
+		wait_for_stable_page(page);
+
+	return page;
+}
+EXPORT_SYMBOL(grab_cache_page_write_begin);
+
+ssize_t generic_perform_write(struct file *file,
+				struct iov_iter *i, loff_t pos)
+{
+	struct address_space *mapping = file->f_mapping;
+	const struct address_space_operations *a_ops = mapping->a_ops;
+	long status = 0;
+	ssize_t written = 0;
+	unsigned int flags = 0;
+
+	/*
+	 * Copies from kernel address space cannot fail (NFSD is a big user).
+	 */
+	if (!iter_is_iovec(i))
+		flags |= AOP_FLAG_UNINTERRUPTIBLE;
+
+	do {
+		struct page *page;
+		unsigned long offset;	/* Offset into pagecache page */
+		unsigned long bytes;	/* Bytes to write to page */
+		size_t copied;		/* Bytes copied from user */
+		void *fsdata;
+
+		offset = (pos & (PAGE_CACHE_SIZE - 1));
+		bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
+						iov_iter_count(i));
+
+again:
+		/*
+		 * Bring in the user page that we will copy from _first_.
+		 * Otherwise there's a nasty deadlock on copying from the
+		 * same page as we're writing to, without it being marked
+		 * up-to-date.
+		 *
+		 * Not only is this an optimisation, but it is also required
+		 * to check that the address is actually valid, when atomic
+		 * usercopies are used, below.
+		 */
+		if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
+			status = -EFAULT;
+			break;
+		}
+
+		if (fatal_signal_pending(current)) {
+			status = -EINTR;
+			break;
+		}
+
+		status = a_ops->write_begin(file, mapping, pos, bytes, flags,
+						&page, &fsdata);
+		if (unlikely(status < 0))
+			break;
+
+		if (mapping_writably_mapped(mapping))
+			flush_dcache_page(page);
+
+		copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
+		flush_dcache_page(page);
+
+		status = a_ops->write_end(file, mapping, pos, bytes, copied,
+						page, fsdata);
+		if (unlikely(status < 0))
+			break;
+		copied = status;
+
+		cond_resched();
+
+		iov_iter_advance(i, copied);
+		if (unlikely(copied == 0)) {
+			/*
+			 * If we were unable to copy any data at all, we must
+			 * fall back to a single segment length write.
+			 *
+			 * If we didn't fallback here, we could livelock
+			 * because not all segments in the iov can be copied at
+			 * once without a pagefault.
+			 */
+			bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
+						iov_iter_single_seg_count(i));
+			goto again;
+		}
+		pos += copied;
+		written += copied;
+
+		balance_dirty_pages_ratelimited(mapping);
+	} while (iov_iter_count(i));
+
+	return written ? written : status;
+}
+EXPORT_SYMBOL(generic_perform_write);
+
+/**
+ * __generic_file_write_iter - write data to a file
+ * @iocb:	IO state structure (file, offset, etc.)
+ * @from:	iov_iter with data to write
+ *
+ * This function does all the work needed for actually writing data to a
+ * file. It does all basic checks, removes SUID from the file, updates
+ * modification times and calls proper subroutines depending on whether we
+ * do direct IO or a standard buffered write.
+ *
+ * It expects i_mutex to be grabbed unless we work on a block device or similar
+ * object which does not need locking at all.
+ *
+ * This function does *not* take care of syncing data in case of O_SYNC write.
+ * A caller has to handle it. This is mainly due to the fact that we want to
+ * avoid syncing under i_mutex.
+ */
+ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space * mapping = file->f_mapping;
+	struct inode 	*inode = mapping->host;
+	ssize_t		written = 0;
+	ssize_t		err;
+	ssize_t		status;
+
+	/* We can write back this queue in page reclaim */
+	current->backing_dev_info = inode_to_bdi(inode);
+	err = file_remove_privs(file);
+	if (err)
+		goto out;
+
+	err = file_update_time(file);
+	if (err)
+		goto out;
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		loff_t pos, endbyte;
+
+		written = generic_file_direct_write(iocb, from, iocb->ki_pos);
+		/*
+		 * If the write stopped short of completing, fall back to
+		 * buffered writes.  Some filesystems do this for writes to
+		 * holes, for example.  For DAX files, a buffered write will
+		 * not succeed (even if it did, DAX does not handle dirty
+		 * page-cache pages correctly).
+		 */
+		if (written < 0 || !iov_iter_count(from) || IS_DAX(inode))
+			goto out;
+
+		status = generic_perform_write(file, from, pos = iocb->ki_pos);
+		/*
+		 * If generic_perform_write() returned a synchronous error
+		 * then we want to return the number of bytes which were
+		 * direct-written, or the error code if that was zero.  Note
+		 * that this differs from normal direct-io semantics, which
+		 * will return -EFOO even if some bytes were written.
+		 */
+		if (unlikely(status < 0)) {
+			err = status;
+			goto out;
+		}
+		/*
+		 * We need to ensure that the page cache pages are written to
+		 * disk and invalidated to preserve the expected O_DIRECT
+		 * semantics.
+		 */
+		endbyte = pos + status - 1;
+		err = filemap_write_and_wait_range(mapping, pos, endbyte);
+		if (err == 0) {
+			iocb->ki_pos = endbyte + 1;
+			written += status;
+			invalidate_mapping_pages(mapping,
+						 pos >> PAGE_CACHE_SHIFT,
+						 endbyte >> PAGE_CACHE_SHIFT);
+		} else {
+			/*
+			 * We don't know how much we wrote, so just return
+			 * the number of bytes which were direct-written
+			 */
+		}
+	} else {
+		written = generic_perform_write(file, from, iocb->ki_pos);
+		if (likely(written > 0))
+			iocb->ki_pos += written;
+	}
+out:
+	current->backing_dev_info = NULL;
+	return written ? written : err;
+}
+EXPORT_SYMBOL(__generic_file_write_iter);
+
+/**
+ * generic_file_write_iter - write data to a file
+ * @iocb:	IO state structure
+ * @from:	iov_iter with data to write
+ *
+ * This is a wrapper around __generic_file_write_iter() to be used by most
+ * filesystems. It takes care of syncing the file in case of O_SYNC file
+ * and acquires i_mutex as needed.
+ */
+ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
+
+	mutex_lock(&inode->i_mutex);
+	ret = generic_write_checks(iocb, from);
+	if (ret > 0)
+		ret = __generic_file_write_iter(iocb, from);
+	mutex_unlock(&inode->i_mutex);
+
+	if (ret > 0) {
+		ssize_t err;
+
+		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		if (err < 0)
+			ret = err;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(generic_file_write_iter);
+
+/**
+ * try_to_release_page() - release old fs-specific metadata on a page
+ *
+ * @page: the page which the kernel is trying to free
+ * @gfp_mask: memory allocation flags (and I/O mode)
+ *
+ * The address_space is to try to release any data against the page
+ * (presumably at page->private).  If the release was successful, return `1'.
+ * Otherwise return zero.
+ *
+ * This may also be called if PG_fscache is set on a page, indicating that the
+ * page is known to the local caching routines.
+ *
+ * The @gfp_mask argument specifies whether I/O may be performed to release
+ * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS).
+ *
+ */
+int try_to_release_page(struct page *page, gfp_t gfp_mask)
+{
+	struct address_space * const mapping = page->mapping;
+
+	BUG_ON(!PageLocked(page));
+	if (PageWriteback(page))
+		return 0;
+
+	if (mapping && mapping->a_ops->releasepage)
+		return mapping->a_ops->releasepage(page, gfp_mask);
+	return try_to_free_buffers(page);
+}
+
+EXPORT_SYMBOL(try_to_release_page);
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
new file mode 100644
index 0000000..7cf2b71
--- /dev/null
+++ b/mm/frame_vector.c
@@ -0,0 +1,230 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/pagemap.h>
+#include <linux/sched.h>
+
+/**
+ * get_vaddr_frames() - map virtual addresses to pfns
+ * @start:	starting user address
+ * @nr_frames:	number of pages / pfns from start to map
+ * @write:	whether pages will be written to by the caller
+ * @force:	whether to force write access even if user mapping is
+ *		readonly. See description of the same argument of
+		get_user_pages().
+ * @vec:	structure which receives pages / pfns of the addresses mapped.
+ *		It should have space for at least nr_frames entries.
+ *
+ * This function maps virtual addresses from @start and fills @vec structure
+ * with page frame numbers or page pointers to corresponding pages (choice
+ * depends on the type of the vma underlying the virtual address). If @start
+ * belongs to a normal vma, the function grabs reference to each of the pages
+ * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
+ * touch page structures and the caller must make sure pfns aren't reused for
+ * anything else while he is using them.
+ *
+ * The function returns number of pages mapped which may be less than
+ * @nr_frames. In particular we stop mapping if there are more vmas of
+ * different type underlying the specified range of virtual addresses.
+ * When the function isn't able to map a single page, it returns error.
+ *
+ * This function takes care of grabbing mmap_sem as necessary.
+ */
+int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
+		     bool write, bool force, struct frame_vector *vec)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	int ret = 0;
+	int err;
+	int locked;
+
+	if (nr_frames == 0)
+		return 0;
+
+	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
+		nr_frames = vec->nr_allocated;
+
+	down_read(&mm->mmap_sem);
+	locked = 1;
+	vma = find_vma_intersection(mm, start, start + 1);
+	if (!vma) {
+		ret = -EFAULT;
+		goto out;
+	}
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
+		vec->got_ref = true;
+		vec->is_pfns = false;
+		ret = get_user_pages_locked(current, mm, start, nr_frames,
+			write, force, (struct page **)(vec->ptrs), &locked);
+		goto out;
+	}
+
+	vec->got_ref = false;
+	vec->is_pfns = true;
+	do {
+		unsigned long *nums = frame_vector_pfns(vec);
+
+		while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
+			err = follow_pfn(vma, start, &nums[ret]);
+			if (err) {
+				if (ret == 0)
+					ret = err;
+				goto out;
+			}
+			start += PAGE_SIZE;
+			ret++;
+		}
+		/*
+		 * We stop if we have enough pages or if VMA doesn't completely
+		 * cover the tail page.
+		 */
+		if (ret >= nr_frames || start < vma->vm_end)
+			break;
+		vma = find_vma_intersection(mm, start, start + 1);
+	} while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
+out:
+	if (locked)
+		up_read(&mm->mmap_sem);
+	if (!ret)
+		ret = -EFAULT;
+	if (ret > 0)
+		vec->nr_frames = ret;
+	return ret;
+}
+EXPORT_SYMBOL(get_vaddr_frames);
+
+/**
+ * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
+ *			them
+ * @vec:	frame vector to put
+ *
+ * Drop references to pages if get_vaddr_frames() acquired them. We also
+ * invalidate the frame vector so that it is prepared for the next call into
+ * get_vaddr_frames().
+ */
+void put_vaddr_frames(struct frame_vector *vec)
+{
+	int i;
+	struct page **pages;
+
+	if (!vec->got_ref)
+		goto out;
+	pages = frame_vector_pages(vec);
+	/*
+	 * frame_vector_pages() might needed to do a conversion when
+	 * get_vaddr_frames() got pages but vec was later converted to pfns.
+	 * But it shouldn't really fail to convert pfns back...
+	 */
+	if (WARN_ON(IS_ERR(pages)))
+		goto out;
+	for (i = 0; i < vec->nr_frames; i++)
+		put_page(pages[i]);
+	vec->got_ref = false;
+out:
+	vec->nr_frames = 0;
+}
+EXPORT_SYMBOL(put_vaddr_frames);
+
+/**
+ * frame_vector_to_pages - convert frame vector to contain page pointers
+ * @vec:	frame vector to convert
+ *
+ * Convert @vec to contain array of page pointers.  If the conversion is
+ * successful, return 0. Otherwise return an error. Note that we do not grab
+ * page references for the page structures.
+ */
+int frame_vector_to_pages(struct frame_vector *vec)
+{
+	int i;
+	unsigned long *nums;
+	struct page **pages;
+
+	if (!vec->is_pfns)
+		return 0;
+	nums = frame_vector_pfns(vec);
+	for (i = 0; i < vec->nr_frames; i++)
+		if (!pfn_valid(nums[i]))
+			return -EINVAL;
+	pages = (struct page **)nums;
+	for (i = 0; i < vec->nr_frames; i++)
+		pages[i] = pfn_to_page(nums[i]);
+	vec->is_pfns = false;
+	return 0;
+}
+EXPORT_SYMBOL(frame_vector_to_pages);
+
+/**
+ * frame_vector_to_pfns - convert frame vector to contain pfns
+ * @vec:	frame vector to convert
+ *
+ * Convert @vec to contain array of pfns.
+ */
+void frame_vector_to_pfns(struct frame_vector *vec)
+{
+	int i;
+	unsigned long *nums;
+	struct page **pages;
+
+	if (vec->is_pfns)
+		return;
+	pages = (struct page **)(vec->ptrs);
+	nums = (unsigned long *)pages;
+	for (i = 0; i < vec->nr_frames; i++)
+		nums[i] = page_to_pfn(pages[i]);
+	vec->is_pfns = true;
+}
+EXPORT_SYMBOL(frame_vector_to_pfns);
+
+/**
+ * frame_vector_create() - allocate & initialize structure for pinned pfns
+ * @nr_frames:	number of pfns slots we should reserve
+ *
+ * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
+ * pfns.
+ */
+struct frame_vector *frame_vector_create(unsigned int nr_frames)
+{
+	struct frame_vector *vec;
+	int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
+
+	if (WARN_ON_ONCE(nr_frames == 0))
+		return NULL;
+	/*
+	 * This is absurdly high. It's here just to avoid strange effects when
+	 * arithmetics overflows.
+	 */
+	if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
+		return NULL;
+	/*
+	 * Avoid higher order allocations, use vmalloc instead. It should
+	 * be rare anyway.
+	 */
+	if (size <= PAGE_SIZE)
+		vec = kmalloc(size, GFP_KERNEL);
+	else
+		vec = vmalloc(size);
+	if (!vec)
+		return NULL;
+	vec->nr_allocated = nr_frames;
+	vec->nr_frames = 0;
+	return vec;
+}
+EXPORT_SYMBOL(frame_vector_create);
+
+/**
+ * frame_vector_destroy() - free memory allocated to carry frame vector
+ * @vec:	Frame vector to free
+ *
+ * Free structure allocated by frame_vector_create() to carry frames.
+ */
+void frame_vector_destroy(struct frame_vector *vec)
+{
+	/* Make sure put_vaddr_frames() got called properly... */
+	VM_BUG_ON(vec->nr_frames > 0);
+	kvfree(vec);
+}
+EXPORT_SYMBOL(frame_vector_destroy);
diff --git a/mm/frontswap.c b/mm/frontswap.c
new file mode 100644
index 0000000..27a9924
--- /dev/null
+++ b/mm/frontswap.c
@@ -0,0 +1,504 @@
+/*
+ * Frontswap frontend
+ *
+ * This code provides the generic "frontend" layer to call a matching
+ * "backend" driver implementation of frontswap.  See
+ * Documentation/vm/frontswap.txt for more information.
+ *
+ * Copyright (C) 2009-2012 Oracle Corp.  All rights reserved.
+ * Author: Dan Magenheimer
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/security.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/frontswap.h>
+#include <linux/swapfile.h>
+
+/*
+ * frontswap_ops are added by frontswap_register_ops, and provide the
+ * frontswap "backend" implementation functions.  Multiple implementations
+ * may be registered, but implementations can never deregister.  This
+ * is a simple singly-linked list of all registered implementations.
+ */
+static struct frontswap_ops *frontswap_ops __read_mostly;
+
+#define for_each_frontswap_ops(ops)		\
+	for ((ops) = frontswap_ops; (ops); (ops) = (ops)->next)
+
+/*
+ * If enabled, frontswap_store will return failure even on success.  As
+ * a result, the swap subsystem will always write the page to swap, in
+ * effect converting frontswap into a writethrough cache.  In this mode,
+ * there is no direct reduction in swap writes, but a frontswap backend
+ * can unilaterally "reclaim" any pages in use with no data loss, thus
+ * providing increases control over maximum memory usage due to frontswap.
+ */
+static bool frontswap_writethrough_enabled __read_mostly;
+
+/*
+ * If enabled, the underlying tmem implementation is capable of doing
+ * exclusive gets, so frontswap_load, on a successful tmem_get must
+ * mark the page as no longer in frontswap AND mark it dirty.
+ */
+static bool frontswap_tmem_exclusive_gets_enabled __read_mostly;
+
+#ifdef CONFIG_DEBUG_FS
+/*
+ * Counters available via /sys/kernel/debug/frontswap (if debugfs is
+ * properly configured).  These are for information only so are not protected
+ * against increment races.
+ */
+static u64 frontswap_loads;
+static u64 frontswap_succ_stores;
+static u64 frontswap_failed_stores;
+static u64 frontswap_invalidates;
+
+static inline void inc_frontswap_loads(void) {
+	frontswap_loads++;
+}
+static inline void inc_frontswap_succ_stores(void) {
+	frontswap_succ_stores++;
+}
+static inline void inc_frontswap_failed_stores(void) {
+	frontswap_failed_stores++;
+}
+static inline void inc_frontswap_invalidates(void) {
+	frontswap_invalidates++;
+}
+#else
+static inline void inc_frontswap_loads(void) { }
+static inline void inc_frontswap_succ_stores(void) { }
+static inline void inc_frontswap_failed_stores(void) { }
+static inline void inc_frontswap_invalidates(void) { }
+#endif
+
+/*
+ * Due to the asynchronous nature of the backends loading potentially
+ * _after_ the swap system has been activated, we have chokepoints
+ * on all frontswap functions to not call the backend until the backend
+ * has registered.
+ *
+ * This would not guards us against the user deciding to call swapoff right as
+ * we are calling the backend to initialize (so swapon is in action).
+ * Fortunatly for us, the swapon_mutex has been taked by the callee so we are
+ * OK. The other scenario where calls to frontswap_store (called via
+ * swap_writepage) is racing with frontswap_invalidate_area (called via
+ * swapoff) is again guarded by the swap subsystem.
+ *
+ * While no backend is registered all calls to frontswap_[store|load|
+ * invalidate_area|invalidate_page] are ignored or fail.
+ *
+ * The time between the backend being registered and the swap file system
+ * calling the backend (via the frontswap_* functions) is indeterminate as
+ * frontswap_ops is not atomic_t (or a value guarded by a spinlock).
+ * That is OK as we are comfortable missing some of these calls to the newly
+ * registered backend.
+ *
+ * Obviously the opposite (unloading the backend) must be done after all
+ * the frontswap_[store|load|invalidate_area|invalidate_page] start
+ * ignoring or failing the requests.  However, there is currently no way
+ * to unload a backend once it is registered.
+ */
+
+/*
+ * Register operations for frontswap
+ */
+void frontswap_register_ops(struct frontswap_ops *ops)
+{
+	DECLARE_BITMAP(a, MAX_SWAPFILES);
+	DECLARE_BITMAP(b, MAX_SWAPFILES);
+	struct swap_info_struct *si;
+	unsigned int i;
+
+	bitmap_zero(a, MAX_SWAPFILES);
+	bitmap_zero(b, MAX_SWAPFILES);
+
+	spin_lock(&swap_lock);
+	plist_for_each_entry(si, &swap_active_head, list) {
+		if (!WARN_ON(!si->frontswap_map))
+			set_bit(si->type, a);
+	}
+	spin_unlock(&swap_lock);
+
+	/* the new ops needs to know the currently active swap devices */
+	for_each_set_bit(i, a, MAX_SWAPFILES)
+		ops->init(i);
+
+	/*
+	 * Setting frontswap_ops must happen after the ops->init() calls
+	 * above; cmpxchg implies smp_mb() which will ensure the init is
+	 * complete at this point.
+	 */
+	do {
+		ops->next = frontswap_ops;
+	} while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next);
+
+	spin_lock(&swap_lock);
+	plist_for_each_entry(si, &swap_active_head, list) {
+		if (si->frontswap_map)
+			set_bit(si->type, b);
+	}
+	spin_unlock(&swap_lock);
+
+	/*
+	 * On the very unlikely chance that a swap device was added or
+	 * removed between setting the "a" list bits and the ops init
+	 * calls, we re-check and do init or invalidate for any changed
+	 * bits.
+	 */
+	if (unlikely(!bitmap_equal(a, b, MAX_SWAPFILES))) {
+		for (i = 0; i < MAX_SWAPFILES; i++) {
+			if (!test_bit(i, a) && test_bit(i, b))
+				ops->init(i);
+			else if (test_bit(i, a) && !test_bit(i, b))
+				ops->invalidate_area(i);
+		}
+	}
+}
+EXPORT_SYMBOL(frontswap_register_ops);
+
+/*
+ * Enable/disable frontswap writethrough (see above).
+ */
+void frontswap_writethrough(bool enable)
+{
+	frontswap_writethrough_enabled = enable;
+}
+EXPORT_SYMBOL(frontswap_writethrough);
+
+/*
+ * Enable/disable frontswap exclusive gets (see above).
+ */
+void frontswap_tmem_exclusive_gets(bool enable)
+{
+	frontswap_tmem_exclusive_gets_enabled = enable;
+}
+EXPORT_SYMBOL(frontswap_tmem_exclusive_gets);
+
+/*
+ * Called when a swap device is swapon'd.
+ */
+void __frontswap_init(unsigned type, unsigned long *map)
+{
+	struct swap_info_struct *sis = swap_info[type];
+	struct frontswap_ops *ops;
+
+	BUG_ON(sis == NULL);
+
+	/*
+	 * p->frontswap is a bitmap that we MUST have to figure out which page
+	 * has gone in frontswap. Without it there is no point of continuing.
+	 */
+	if (WARN_ON(!map))
+		return;
+	/*
+	 * Irregardless of whether the frontswap backend has been loaded
+	 * before this function or it will be later, we _MUST_ have the
+	 * p->frontswap set to something valid to work properly.
+	 */
+	frontswap_map_set(sis, map);
+
+	for_each_frontswap_ops(ops)
+		ops->init(type);
+}
+EXPORT_SYMBOL(__frontswap_init);
+
+bool __frontswap_test(struct swap_info_struct *sis,
+				pgoff_t offset)
+{
+	if (sis->frontswap_map)
+		return test_bit(offset, sis->frontswap_map);
+	return false;
+}
+EXPORT_SYMBOL(__frontswap_test);
+
+static inline void __frontswap_set(struct swap_info_struct *sis,
+				   pgoff_t offset)
+{
+	set_bit(offset, sis->frontswap_map);
+	atomic_inc(&sis->frontswap_pages);
+}
+
+static inline void __frontswap_clear(struct swap_info_struct *sis,
+				     pgoff_t offset)
+{
+	clear_bit(offset, sis->frontswap_map);
+	atomic_dec(&sis->frontswap_pages);
+}
+
+/*
+ * "Store" data from a page to frontswap and associate it with the page's
+ * swaptype and offset.  Page must be locked and in the swap cache.
+ * If frontswap already contains a page with matching swaptype and
+ * offset, the frontswap implementation may either overwrite the data and
+ * return success or invalidate the page from frontswap and return failure.
+ */
+int __frontswap_store(struct page *page)
+{
+	int ret = -1;
+	swp_entry_t entry = { .val = page_private(page), };
+	int type = swp_type(entry);
+	struct swap_info_struct *sis = swap_info[type];
+	pgoff_t offset = swp_offset(entry);
+	struct frontswap_ops *ops;
+
+	/*
+	 * Return if no backend registed.
+	 * Don't need to inc frontswap_failed_stores here.
+	 */
+	if (!frontswap_ops)
+		return -1;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(sis == NULL);
+
+	/*
+	 * If a dup, we must remove the old page first; we can't leave the
+	 * old page no matter if the store of the new page succeeds or fails,
+	 * and we can't rely on the new page replacing the old page as we may
+	 * not store to the same implementation that contains the old page.
+	 */
+	if (__frontswap_test(sis, offset)) {
+		__frontswap_clear(sis, offset);
+		for_each_frontswap_ops(ops)
+			ops->invalidate_page(type, offset);
+	}
+
+	/* Try to store in each implementation, until one succeeds. */
+	for_each_frontswap_ops(ops) {
+		ret = ops->store(type, offset, page);
+		if (!ret) /* successful store */
+			break;
+	}
+	if (ret == 0) {
+		__frontswap_set(sis, offset);
+		inc_frontswap_succ_stores();
+	} else {
+		inc_frontswap_failed_stores();
+	}
+	if (frontswap_writethrough_enabled)
+		/* report failure so swap also writes to swap device */
+		ret = -1;
+	return ret;
+}
+EXPORT_SYMBOL(__frontswap_store);
+
+/*
+ * "Get" data from frontswap associated with swaptype and offset that were
+ * specified when the data was put to frontswap and use it to fill the
+ * specified page with data. Page must be locked and in the swap cache.
+ */
+int __frontswap_load(struct page *page)
+{
+	int ret = -1;
+	swp_entry_t entry = { .val = page_private(page), };
+	int type = swp_type(entry);
+	struct swap_info_struct *sis = swap_info[type];
+	pgoff_t offset = swp_offset(entry);
+	struct frontswap_ops *ops;
+
+	if (!frontswap_ops)
+		return -1;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(sis == NULL);
+	if (!__frontswap_test(sis, offset))
+		return -1;
+
+	/* Try loading from each implementation, until one succeeds. */
+	for_each_frontswap_ops(ops) {
+		ret = ops->load(type, offset, page);
+		if (!ret) /* successful load */
+			break;
+	}
+	if (ret == 0) {
+		inc_frontswap_loads();
+		if (frontswap_tmem_exclusive_gets_enabled) {
+			SetPageDirty(page);
+			__frontswap_clear(sis, offset);
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL(__frontswap_load);
+
+/*
+ * Invalidate any data from frontswap associated with the specified swaptype
+ * and offset so that a subsequent "get" will fail.
+ */
+void __frontswap_invalidate_page(unsigned type, pgoff_t offset)
+{
+	struct swap_info_struct *sis = swap_info[type];
+	struct frontswap_ops *ops;
+
+	if (!frontswap_ops)
+		return;
+
+	BUG_ON(sis == NULL);
+	if (!__frontswap_test(sis, offset))
+		return;
+
+	for_each_frontswap_ops(ops)
+		ops->invalidate_page(type, offset);
+	__frontswap_clear(sis, offset);
+	inc_frontswap_invalidates();
+}
+EXPORT_SYMBOL(__frontswap_invalidate_page);
+
+/*
+ * Invalidate all data from frontswap associated with all offsets for the
+ * specified swaptype.
+ */
+void __frontswap_invalidate_area(unsigned type)
+{
+	struct swap_info_struct *sis = swap_info[type];
+	struct frontswap_ops *ops;
+
+	if (!frontswap_ops)
+		return;
+
+	BUG_ON(sis == NULL);
+	if (sis->frontswap_map == NULL)
+		return;
+
+	for_each_frontswap_ops(ops)
+		ops->invalidate_area(type);
+	atomic_set(&sis->frontswap_pages, 0);
+	bitmap_zero(sis->frontswap_map, sis->max);
+}
+EXPORT_SYMBOL(__frontswap_invalidate_area);
+
+static unsigned long __frontswap_curr_pages(void)
+{
+	unsigned long totalpages = 0;
+	struct swap_info_struct *si = NULL;
+
+	assert_spin_locked(&swap_lock);
+	plist_for_each_entry(si, &swap_active_head, list)
+		totalpages += atomic_read(&si->frontswap_pages);
+	return totalpages;
+}
+
+static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused,
+					int *swapid)
+{
+	int ret = -EINVAL;
+	struct swap_info_struct *si = NULL;
+	int si_frontswap_pages;
+	unsigned long total_pages_to_unuse = total;
+	unsigned long pages = 0, pages_to_unuse = 0;
+
+	assert_spin_locked(&swap_lock);
+	plist_for_each_entry(si, &swap_active_head, list) {
+		si_frontswap_pages = atomic_read(&si->frontswap_pages);
+		if (total_pages_to_unuse < si_frontswap_pages) {
+			pages = pages_to_unuse = total_pages_to_unuse;
+		} else {
+			pages = si_frontswap_pages;
+			pages_to_unuse = 0; /* unuse all */
+		}
+		/* ensure there is enough RAM to fetch pages from frontswap */
+		if (security_vm_enough_memory_mm(current->mm, pages)) {
+			ret = -ENOMEM;
+			continue;
+		}
+		vm_unacct_memory(pages);
+		*unused = pages_to_unuse;
+		*swapid = si->type;
+		ret = 0;
+		break;
+	}
+
+	return ret;
+}
+
+/*
+ * Used to check if it's necessory and feasible to unuse pages.
+ * Return 1 when nothing to do, 0 when need to shink pages,
+ * error code when there is an error.
+ */
+static int __frontswap_shrink(unsigned long target_pages,
+				unsigned long *pages_to_unuse,
+				int *type)
+{
+	unsigned long total_pages = 0, total_pages_to_unuse;
+
+	assert_spin_locked(&swap_lock);
+
+	total_pages = __frontswap_curr_pages();
+	if (total_pages <= target_pages) {
+		/* Nothing to do */
+		*pages_to_unuse = 0;
+		return 1;
+	}
+	total_pages_to_unuse = total_pages - target_pages;
+	return __frontswap_unuse_pages(total_pages_to_unuse, pages_to_unuse, type);
+}
+
+/*
+ * Frontswap, like a true swap device, may unnecessarily retain pages
+ * under certain circumstances; "shrink" frontswap is essentially a
+ * "partial swapoff" and works by calling try_to_unuse to attempt to
+ * unuse enough frontswap pages to attempt to -- subject to memory
+ * constraints -- reduce the number of pages in frontswap to the
+ * number given in the parameter target_pages.
+ */
+void frontswap_shrink(unsigned long target_pages)
+{
+	unsigned long pages_to_unuse = 0;
+	int uninitialized_var(type), ret;
+
+	/*
+	 * we don't want to hold swap_lock while doing a very
+	 * lengthy try_to_unuse, but swap_list may change
+	 * so restart scan from swap_active_head each time
+	 */
+	spin_lock(&swap_lock);
+	ret = __frontswap_shrink(target_pages, &pages_to_unuse, &type);
+	spin_unlock(&swap_lock);
+	if (ret == 0)
+		try_to_unuse(type, true, pages_to_unuse);
+	return;
+}
+EXPORT_SYMBOL(frontswap_shrink);
+
+/*
+ * Count and return the number of frontswap pages across all
+ * swap devices.  This is exported so that backend drivers can
+ * determine current usage without reading debugfs.
+ */
+unsigned long frontswap_curr_pages(void)
+{
+	unsigned long totalpages = 0;
+
+	spin_lock(&swap_lock);
+	totalpages = __frontswap_curr_pages();
+	spin_unlock(&swap_lock);
+
+	return totalpages;
+}
+EXPORT_SYMBOL(frontswap_curr_pages);
+
+static int __init init_frontswap(void)
+{
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *root = debugfs_create_dir("frontswap", NULL);
+	if (root == NULL)
+		return -ENXIO;
+	debugfs_create_u64("loads", S_IRUGO, root, &frontswap_loads);
+	debugfs_create_u64("succ_stores", S_IRUGO, root, &frontswap_succ_stores);
+	debugfs_create_u64("failed_stores", S_IRUGO, root,
+				&frontswap_failed_stores);
+	debugfs_create_u64("invalidates", S_IRUGO,
+				root, &frontswap_invalidates);
+#endif
+	return 0;
+}
+
+module_init(init_frontswap);
diff --git a/mm/gup.c b/mm/gup.c
new file mode 100644
index 0000000..b599526
--- /dev/null
+++ b/mm/gup.c
@@ -0,0 +1,1430 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+
+#include <linux/sched.h>
+#include <linux/rwsem.h>
+#include <linux/hugetlb.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+
+static struct page *no_page_table(struct vm_area_struct *vma,
+		unsigned int flags)
+{
+	/*
+	 * When core dumping an enormous anonymous area that nobody
+	 * has touched so far, we don't want to allocate unnecessary pages or
+	 * page tables.  Return error instead of NULL to skip handle_mm_fault,
+	 * then get_dump_page() will return NULL to leave a hole in the dump.
+	 * But we can only make this optimization where a hole would surely
+	 * be zero-filled if handle_mm_fault() actually did handle it.
+	 */
+	if ((flags & FOLL_DUMP) && (!vma->vm_ops || !vma->vm_ops->fault))
+		return ERR_PTR(-EFAULT);
+	return NULL;
+}
+
+static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
+		pte_t *pte, unsigned int flags)
+{
+	/* No page to get reference */
+	if (flags & FOLL_GET)
+		return -EFAULT;
+
+	if (flags & FOLL_TOUCH) {
+		pte_t entry = *pte;
+
+		if (flags & FOLL_WRITE)
+			entry = pte_mkdirty(entry);
+		entry = pte_mkyoung(entry);
+
+		if (!pte_same(*pte, entry)) {
+			set_pte_at(vma->vm_mm, address, pte, entry);
+			update_mmu_cache(vma, address, pte);
+		}
+	}
+
+	/* Proper page table entry exists, but no corresponding struct page */
+	return -EEXIST;
+}
+
+/*
+ * FOLL_FORCE can write to even unwritable pte's, but only
+ * after we've gone through a COW cycle and they are dirty.
+ */
+static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
+{
+	return pte_write(pte) ||
+		((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
+}
+
+static struct page *follow_page_pte(struct vm_area_struct *vma,
+		unsigned long address, pmd_t *pmd, unsigned int flags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct page *page;
+	spinlock_t *ptl;
+	pte_t *ptep, pte;
+
+retry:
+	if (unlikely(pmd_bad(*pmd)))
+		return no_page_table(vma, flags);
+
+	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+	pte = *ptep;
+	if (!pte_present(pte)) {
+		swp_entry_t entry;
+		/*
+		 * KSM's break_ksm() relies upon recognizing a ksm page
+		 * even while it is being migrated, so for that case we
+		 * need migration_entry_wait().
+		 */
+		if (likely(!(flags & FOLL_MIGRATION)))
+			goto no_page;
+		if (pte_none(pte))
+			goto no_page;
+		entry = pte_to_swp_entry(pte);
+		if (!is_migration_entry(entry))
+			goto no_page;
+		pte_unmap_unlock(ptep, ptl);
+		migration_entry_wait(mm, pmd, address);
+		goto retry;
+	}
+	if ((flags & FOLL_NUMA) && pte_protnone(pte))
+		goto no_page;
+	if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) {
+		pte_unmap_unlock(ptep, ptl);
+		return NULL;
+	}
+
+	page = vm_normal_page(vma, address, pte);
+	if (unlikely(!page)) {
+		if (flags & FOLL_DUMP) {
+			/* Avoid special (like zero) pages in core dumps */
+			page = ERR_PTR(-EFAULT);
+			goto out;
+		}
+
+		if (is_zero_pfn(pte_pfn(pte))) {
+			page = pte_page(pte);
+		} else {
+			int ret;
+
+			ret = follow_pfn_pte(vma, address, ptep, flags);
+			page = ERR_PTR(ret);
+			goto out;
+		}
+	}
+
+	if (flags & FOLL_GET)
+		get_page_foll(page);
+	if (flags & FOLL_TOUCH) {
+		if ((flags & FOLL_WRITE) &&
+		    !pte_dirty(pte) && !PageDirty(page))
+			set_page_dirty(page);
+		/*
+		 * pte_mkyoung() would be more correct here, but atomic care
+		 * is needed to avoid losing the dirty bit: it is easier to use
+		 * mark_page_accessed().
+		 */
+		mark_page_accessed(page);
+	}
+	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
+		/*
+		 * The preliminary mapping check is mainly to avoid the
+		 * pointless overhead of lock_page on the ZERO_PAGE
+		 * which might bounce very badly if there is contention.
+		 *
+		 * If the page is already locked, we don't need to
+		 * handle it now - vmscan will handle it later if and
+		 * when it attempts to reclaim the page.
+		 */
+		if (page->mapping && trylock_page(page)) {
+			lru_add_drain();  /* push cached pages to LRU */
+			/*
+			 * Because we lock page here, and migration is
+			 * blocked by the pte's page reference, and we
+			 * know the page is still mapped, we don't even
+			 * need to check for file-cache page truncation.
+			 */
+			mlock_vma_page(page);
+			unlock_page(page);
+		}
+	}
+out:
+	pte_unmap_unlock(ptep, ptl);
+	return page;
+no_page:
+	pte_unmap_unlock(ptep, ptl);
+	if (!pte_none(pte))
+		return NULL;
+	return no_page_table(vma, flags);
+}
+
+/**
+ * follow_page_mask - look up a page descriptor from a user-virtual address
+ * @vma: vm_area_struct mapping @address
+ * @address: virtual address to look up
+ * @flags: flags modifying lookup behaviour
+ * @page_mask: on output, *page_mask is set according to the size of the page
+ *
+ * @flags can have FOLL_ flags set, defined in <linux/mm.h>
+ *
+ * Returns the mapped (struct page *), %NULL if no mapping exists, or
+ * an error pointer if there is a mapping to something not represented
+ * by a page descriptor (see also vm_normal_page()).
+ */
+struct page *follow_page_mask(struct vm_area_struct *vma,
+			      unsigned long address, unsigned int flags,
+			      unsigned int *page_mask)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	spinlock_t *ptl;
+	struct page *page;
+	struct mm_struct *mm = vma->vm_mm;
+
+	*page_mask = 0;
+
+	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
+	if (!IS_ERR(page)) {
+		BUG_ON(flags & FOLL_GET);
+		return page;
+	}
+
+	pgd = pgd_offset(mm, address);
+	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+		return no_page_table(vma, flags);
+
+	pud = pud_offset(pgd, address);
+	if (pud_none(*pud))
+		return no_page_table(vma, flags);
+	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
+		page = follow_huge_pud(mm, address, pud, flags);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
+	if (unlikely(pud_bad(*pud)))
+		return no_page_table(vma, flags);
+
+	pmd = pmd_offset(pud, address);
+	if (pmd_none(*pmd))
+		return no_page_table(vma, flags);
+	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
+		page = follow_huge_pmd(mm, address, pmd, flags);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
+	if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
+		return no_page_table(vma, flags);
+	if (pmd_trans_huge(*pmd)) {
+		if (flags & FOLL_SPLIT) {
+			split_huge_page_pmd(vma, address, pmd);
+			return follow_page_pte(vma, address, pmd, flags);
+		}
+		ptl = pmd_lock(mm, pmd);
+		if (likely(pmd_trans_huge(*pmd))) {
+			if (unlikely(pmd_trans_splitting(*pmd))) {
+				spin_unlock(ptl);
+				wait_split_huge_page(vma->anon_vma, pmd);
+			} else {
+				page = follow_trans_huge_pmd(vma, address,
+							     pmd, flags);
+				spin_unlock(ptl);
+				*page_mask = HPAGE_PMD_NR - 1;
+				return page;
+			}
+		} else
+			spin_unlock(ptl);
+	}
+	return follow_page_pte(vma, address, pmd, flags);
+}
+
+static int get_gate_page(struct mm_struct *mm, unsigned long address,
+		unsigned int gup_flags, struct vm_area_struct **vma,
+		struct page **page)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	int ret = -EFAULT;
+
+	/* user gate pages are read-only */
+	if (gup_flags & FOLL_WRITE)
+		return -EFAULT;
+	if (address > TASK_SIZE)
+		pgd = pgd_offset_k(address);
+	else
+		pgd = pgd_offset_gate(mm, address);
+	BUG_ON(pgd_none(*pgd));
+	pud = pud_offset(pgd, address);
+	BUG_ON(pud_none(*pud));
+	pmd = pmd_offset(pud, address);
+	if (pmd_none(*pmd))
+		return -EFAULT;
+	VM_BUG_ON(pmd_trans_huge(*pmd));
+	pte = pte_offset_map(pmd, address);
+	if (pte_none(*pte))
+		goto unmap;
+	*vma = get_gate_vma(mm);
+	if (!page)
+		goto out;
+	*page = vm_normal_page(*vma, address, *pte);
+	if (!*page) {
+		if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(*pte)))
+			goto unmap;
+		*page = pte_page(*pte);
+	}
+	get_page(*page);
+out:
+	ret = 0;
+unmap:
+	pte_unmap(pte);
+	return ret;
+}
+
+/*
+ * mmap_sem must be held on entry.  If @nonblocking != NULL and
+ * *@flags does not include FOLL_NOWAIT, the mmap_sem may be released.
+ * If it is, *@nonblocking will be set to 0 and -EBUSY returned.
+ */
+static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
+		unsigned long address, unsigned int *flags, int *nonblocking)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned int fault_flags = 0;
+	int ret;
+
+	/* mlock all present pages, but do not fault in new pages */
+	if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
+		return -ENOENT;
+	if (*flags & FOLL_WRITE)
+		fault_flags |= FAULT_FLAG_WRITE;
+	if (nonblocking)
+		fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+	if (*flags & FOLL_NOWAIT)
+		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
+	if (*flags & FOLL_TRIED) {
+		VM_WARN_ON_ONCE(fault_flags & FAULT_FLAG_ALLOW_RETRY);
+		fault_flags |= FAULT_FLAG_TRIED;
+	}
+
+	ret = handle_mm_fault(mm, vma, address, fault_flags);
+	if (ret & VM_FAULT_ERROR) {
+		if (ret & VM_FAULT_OOM)
+			return -ENOMEM;
+		if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
+			return *flags & FOLL_HWPOISON ? -EHWPOISON : -EFAULT;
+		if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
+			return -EFAULT;
+		BUG();
+	}
+
+	if (tsk) {
+		if (ret & VM_FAULT_MAJOR)
+			tsk->maj_flt++;
+		else
+			tsk->min_flt++;
+	}
+
+	if (ret & VM_FAULT_RETRY) {
+		if (nonblocking)
+			*nonblocking = 0;
+		return -EBUSY;
+	}
+
+	/*
+	 * The VM_FAULT_WRITE bit tells us that do_wp_page has broken COW when
+	 * necessary, even if maybe_mkwrite decided not to set pte_write. We
+	 * can thus safely do subsequent page lookups as if they were reads.
+	 * But only do so when looping for pte_write is futile: in some cases
+	 * userspace may also be wanting to write to the gotten user page,
+	 * which a read fault here might prevent (a readonly page might get
+	 * reCOWed by userspace write).
+	 */
+	if ((ret & VM_FAULT_WRITE) && !(vma->vm_flags & VM_WRITE))
+	        *flags |= FOLL_COW;
+	return 0;
+}
+
+static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
+{
+	vm_flags_t vm_flags = vma->vm_flags;
+
+	if (vm_flags & (VM_IO | VM_PFNMAP))
+		return -EFAULT;
+
+	if (gup_flags & FOLL_WRITE) {
+		if (!(vm_flags & VM_WRITE)) {
+			if (!(gup_flags & FOLL_FORCE))
+				return -EFAULT;
+			/*
+			 * We used to let the write,force case do COW in a
+			 * VM_MAYWRITE VM_SHARED !VM_WRITE vma, so ptrace could
+			 * set a breakpoint in a read-only mapping of an
+			 * executable, without corrupting the file (yet only
+			 * when that file had been opened for writing!).
+			 * Anon pages in shared mappings are surprising: now
+			 * just reject it.
+			 */
+			if (!is_cow_mapping(vm_flags)) {
+				WARN_ON_ONCE(vm_flags & VM_MAYWRITE);
+				return -EFAULT;
+			}
+		}
+	} else if (!(vm_flags & VM_READ)) {
+		if (!(gup_flags & FOLL_FORCE))
+			return -EFAULT;
+		/*
+		 * Is there actually any vma we can reach here which does not
+		 * have VM_MAYREAD set?
+		 */
+		if (!(vm_flags & VM_MAYREAD))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+/**
+ * __get_user_pages() - pin user pages in memory
+ * @tsk:	task_struct of target task
+ * @mm:		mm_struct of target mm
+ * @start:	starting user address
+ * @nr_pages:	number of pages from start to pin
+ * @gup_flags:	flags modifying pin behaviour
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_pages long. Or NULL, if caller
+ *		only intends to ensure the pages are faulted in.
+ * @vmas:	array of pointers to vmas corresponding to each page.
+ *		Or NULL if the caller does not require them.
+ * @nonblocking: whether waiting for disk IO or mmap_sem contention
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno. Each page returned must be released
+ * with a put_page() call when it is finished with. vmas will only
+ * remain valid while mmap_sem is held.
+ *
+ * Must be called with mmap_sem held.  It may be released.  See below.
+ *
+ * __get_user_pages walks a process's page tables and takes a reference to
+ * each struct page that each user address corresponds to at a given
+ * instant. That is, it takes the page that would be accessed if a user
+ * thread accesses the given user virtual address at that instant.
+ *
+ * This does not guarantee that the page exists in the user mappings when
+ * __get_user_pages returns, and there may even be a completely different
+ * page there in some cases (eg. if mmapped pagecache has been invalidated
+ * and subsequently re faulted). However it does guarantee that the page
+ * won't be freed completely. And mostly callers simply care that the page
+ * contains data that was valid *at some point in time*. Typically, an IO
+ * or similar operation cannot guarantee anything stronger anyway because
+ * locks can't be held over the syscall boundary.
+ *
+ * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
+ * the page is written to, set_page_dirty (or set_page_dirty_lock, as
+ * appropriate) must be called after the page is finished with, and
+ * before put_page is called.
+ *
+ * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
+ * or mmap_sem contention, and if waiting is needed to pin all pages,
+ * *@nonblocking will be set to 0.  Further, if @gup_flags does not
+ * include FOLL_NOWAIT, the mmap_sem will be released via up_read() in
+ * this case.
+ *
+ * A caller using such a combination of @nonblocking and @gup_flags
+ * must therefore hold the mmap_sem for reading only, and recognize
+ * when it's been released.  Otherwise, it must be held for either
+ * reading or writing and will not be released.
+ *
+ * In most cases, get_user_pages or get_user_pages_fast should be used
+ * instead of __get_user_pages. __get_user_pages should be used only if
+ * you need some special @gup_flags.
+ */
+long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		unsigned long start, unsigned long nr_pages,
+		unsigned int gup_flags, struct page **pages,
+		struct vm_area_struct **vmas, int *nonblocking)
+{
+	long i = 0;
+	unsigned int page_mask;
+	struct vm_area_struct *vma = NULL;
+
+	if (!nr_pages)
+		return 0;
+
+	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
+
+	/*
+	 * If FOLL_FORCE is set then do not force a full fault as the hinting
+	 * fault information is unrelated to the reference behaviour of a task
+	 * using the address space
+	 */
+	if (!(gup_flags & FOLL_FORCE))
+		gup_flags |= FOLL_NUMA;
+
+	do {
+		struct page *page;
+		unsigned int foll_flags = gup_flags;
+		unsigned int page_increm;
+
+		/* first iteration or cross vma bound */
+		if (!vma || start >= vma->vm_end) {
+			vma = find_extend_vma(mm, start);
+			if (!vma && in_gate_area(mm, start)) {
+				int ret;
+				ret = get_gate_page(mm, start & PAGE_MASK,
+						gup_flags, &vma,
+						pages ? &pages[i] : NULL);
+				if (ret)
+					return i ? : ret;
+				page_mask = 0;
+				goto next_page;
+			}
+
+			if (!vma || check_vma_flags(vma, gup_flags))
+				return i ? : -EFAULT;
+			if (is_vm_hugetlb_page(vma)) {
+				i = follow_hugetlb_page(mm, vma, pages, vmas,
+						&start, &nr_pages, i,
+						gup_flags);
+				continue;
+			}
+		}
+retry:
+		/*
+		 * If we have a pending SIGKILL, don't keep faulting pages and
+		 * potentially allocating memory.
+		 */
+		if (unlikely(fatal_signal_pending(current)))
+			return i ? i : -ERESTARTSYS;
+		cond_resched();
+		page = follow_page_mask(vma, start, foll_flags, &page_mask);
+		if (!page) {
+			int ret;
+			ret = faultin_page(tsk, vma, start, &foll_flags,
+					nonblocking);
+			switch (ret) {
+			case 0:
+				goto retry;
+			case -EFAULT:
+			case -ENOMEM:
+			case -EHWPOISON:
+				return i ? i : ret;
+			case -EBUSY:
+				return i;
+			case -ENOENT:
+				goto next_page;
+			}
+			BUG();
+		} else if (PTR_ERR(page) == -EEXIST) {
+			/*
+			 * Proper page table entry exists, but no corresponding
+			 * struct page.
+			 */
+			goto next_page;
+		} else if (IS_ERR(page)) {
+			return i ? i : PTR_ERR(page);
+		}
+		if (pages) {
+			pages[i] = page;
+			flush_anon_page(vma, page, start);
+			flush_dcache_page(page);
+			page_mask = 0;
+		}
+next_page:
+		if (vmas) {
+			vmas[i] = vma;
+			page_mask = 0;
+		}
+		page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
+		if (page_increm > nr_pages)
+			page_increm = nr_pages;
+		i += page_increm;
+		start += page_increm * PAGE_SIZE;
+		nr_pages -= page_increm;
+	} while (nr_pages);
+	return i;
+}
+EXPORT_SYMBOL(__get_user_pages);
+
+/*
+ * fixup_user_fault() - manually resolve a user page fault
+ * @tsk:	the task_struct to use for page fault accounting, or
+ *		NULL if faults are not to be recorded.
+ * @mm:		mm_struct of target mm
+ * @address:	user address
+ * @fault_flags:flags to pass down to handle_mm_fault()
+ *
+ * This is meant to be called in the specific scenario where for locking reasons
+ * we try to access user memory in atomic context (within a pagefault_disable()
+ * section), this returns -EFAULT, and we want to resolve the user fault before
+ * trying again.
+ *
+ * Typically this is meant to be used by the futex code.
+ *
+ * The main difference with get_user_pages() is that this function will
+ * unconditionally call handle_mm_fault() which will in turn perform all the
+ * necessary SW fixup of the dirty and young bits in the PTE, while
+ * handle_mm_fault() only guarantees to update these in the struct page.
+ *
+ * This is important for some architectures where those bits also gate the
+ * access permission to the page because they are maintained in software.  On
+ * such architectures, gup() will not be enough to make a subsequent access
+ * succeed.
+ *
+ * This has the same semantics wrt the @mm->mmap_sem as does filemap_fault().
+ */
+int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
+		     unsigned long address, unsigned int fault_flags)
+{
+	struct vm_area_struct *vma;
+	vm_flags_t vm_flags;
+	int ret;
+
+	vma = find_extend_vma(mm, address);
+	if (!vma || address < vma->vm_start)
+		return -EFAULT;
+
+	vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ;
+	if (!(vm_flags & vma->vm_flags))
+		return -EFAULT;
+
+	ret = handle_mm_fault(mm, vma, address, fault_flags);
+	if (ret & VM_FAULT_ERROR) {
+		if (ret & VM_FAULT_OOM)
+			return -ENOMEM;
+		if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
+			return -EHWPOISON;
+		if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
+			return -EFAULT;
+		BUG();
+	}
+	if (tsk) {
+		if (ret & VM_FAULT_MAJOR)
+			tsk->maj_flt++;
+		else
+			tsk->min_flt++;
+	}
+	return 0;
+}
+
+static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
+						struct mm_struct *mm,
+						unsigned long start,
+						unsigned long nr_pages,
+						int write, int force,
+						struct page **pages,
+						struct vm_area_struct **vmas,
+						int *locked, bool notify_drop,
+						unsigned int flags)
+{
+	long ret, pages_done;
+	bool lock_dropped;
+
+	if (locked) {
+		/* if VM_FAULT_RETRY can be returned, vmas become invalid */
+		BUG_ON(vmas);
+		/* check caller initialized locked */
+		BUG_ON(*locked != 1);
+	}
+
+	if (pages)
+		flags |= FOLL_GET;
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
+	pages_done = 0;
+	lock_dropped = false;
+	for (;;) {
+		ret = __get_user_pages(tsk, mm, start, nr_pages, flags, pages,
+				       vmas, locked);
+		if (!locked)
+			/* VM_FAULT_RETRY couldn't trigger, bypass */
+			return ret;
+
+		/* VM_FAULT_RETRY cannot return errors */
+		if (!*locked) {
+			BUG_ON(ret < 0);
+			BUG_ON(ret >= nr_pages);
+		}
+
+		if (!pages)
+			/* If it's a prefault don't insist harder */
+			return ret;
+
+		if (ret > 0) {
+			nr_pages -= ret;
+			pages_done += ret;
+			if (!nr_pages)
+				break;
+		}
+		if (*locked) {
+			/* VM_FAULT_RETRY didn't trigger */
+			if (!pages_done)
+				pages_done = ret;
+			break;
+		}
+		/* VM_FAULT_RETRY triggered, so seek to the faulting offset */
+		pages += ret;
+		start += ret << PAGE_SHIFT;
+
+		/*
+		 * Repeat on the address that fired VM_FAULT_RETRY
+		 * without FAULT_FLAG_ALLOW_RETRY but with
+		 * FAULT_FLAG_TRIED.
+		 */
+		*locked = 1;
+		lock_dropped = true;
+		down_read(&mm->mmap_sem);
+		ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
+				       pages, NULL, NULL);
+		if (ret != 1) {
+			BUG_ON(ret > 1);
+			if (!pages_done)
+				pages_done = ret;
+			break;
+		}
+		nr_pages--;
+		pages_done++;
+		if (!nr_pages)
+			break;
+		pages++;
+		start += PAGE_SIZE;
+	}
+	if (notify_drop && lock_dropped && *locked) {
+		/*
+		 * We must let the caller know we temporarily dropped the lock
+		 * and so the critical section protected by it was lost.
+		 */
+		up_read(&mm->mmap_sem);
+		*locked = 0;
+	}
+	return pages_done;
+}
+
+/*
+ * We can leverage the VM_FAULT_RETRY functionality in the page fault
+ * paths better by using either get_user_pages_locked() or
+ * get_user_pages_unlocked().
+ *
+ * get_user_pages_locked() is suitable to replace the form:
+ *
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
+ *
+ *  to:
+ *
+ *      int locked = 1;
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
+ *      if (locked)
+ *          up_read(&mm->mmap_sem);
+ */
+long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
+			   unsigned long start, unsigned long nr_pages,
+			   int write, int force, struct page **pages,
+			   int *locked)
+{
+	return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
+				       pages, NULL, locked, true, FOLL_TOUCH);
+}
+EXPORT_SYMBOL(get_user_pages_locked);
+
+/*
+ * Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to
+ * pass additional gup_flags as last parameter (like FOLL_HWPOISON).
+ *
+ * NOTE: here FOLL_TOUCH is not set implicitly and must be set by the
+ * caller if required (just like with __get_user_pages). "FOLL_GET",
+ * "FOLL_WRITE" and "FOLL_FORCE" are set implicitly as needed
+ * according to the parameters "pages", "write", "force"
+ * respectively.
+ */
+__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+					       unsigned long start, unsigned long nr_pages,
+					       int write, int force, struct page **pages,
+					       unsigned int gup_flags)
+{
+	long ret;
+	int locked = 1;
+	down_read(&mm->mmap_sem);
+	ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
+				      pages, NULL, &locked, false, gup_flags);
+	if (locked)
+		up_read(&mm->mmap_sem);
+	return ret;
+}
+EXPORT_SYMBOL(__get_user_pages_unlocked);
+
+/*
+ * get_user_pages_unlocked() is suitable to replace the form:
+ *
+ *      down_read(&mm->mmap_sem);
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
+ *
+ *  with:
+ *
+ *      get_user_pages_unlocked(tsk, mm, ..., pages);
+ *
+ * It is functionally equivalent to get_user_pages_fast so
+ * get_user_pages_fast should be used instead, if the two parameters
+ * "tsk" and "mm" are respectively equal to current and current->mm,
+ * or if "force" shall be set to 1 (get_user_pages_fast misses the
+ * "force" parameter).
+ */
+long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+			     unsigned long start, unsigned long nr_pages,
+			     int write, int force, struct page **pages)
+{
+	return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
+					 force, pages, FOLL_TOUCH);
+}
+EXPORT_SYMBOL(get_user_pages_unlocked);
+
+/*
+ * get_user_pages() - pin user pages in memory
+ * @tsk:	the task_struct to use for page fault accounting, or
+ *		NULL if faults are not to be recorded.
+ * @mm:		mm_struct of target mm
+ * @start:	starting user address
+ * @nr_pages:	number of pages from start to pin
+ * @write:	whether pages will be written to by the caller
+ * @force:	whether to force access even when user mapping is currently
+ *		protected (but never forces write access to shared mapping).
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_pages long. Or NULL, if caller
+ *		only intends to ensure the pages are faulted in.
+ * @vmas:	array of pointers to vmas corresponding to each page.
+ *		Or NULL if the caller does not require them.
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno. Each page returned must be released
+ * with a put_page() call when it is finished with. vmas will only
+ * remain valid while mmap_sem is held.
+ *
+ * Must be called with mmap_sem held for read or write.
+ *
+ * get_user_pages walks a process's page tables and takes a reference to
+ * each struct page that each user address corresponds to at a given
+ * instant. That is, it takes the page that would be accessed if a user
+ * thread accesses the given user virtual address at that instant.
+ *
+ * This does not guarantee that the page exists in the user mappings when
+ * get_user_pages returns, and there may even be a completely different
+ * page there in some cases (eg. if mmapped pagecache has been invalidated
+ * and subsequently re faulted). However it does guarantee that the page
+ * won't be freed completely. And mostly callers simply care that the page
+ * contains data that was valid *at some point in time*. Typically, an IO
+ * or similar operation cannot guarantee anything stronger anyway because
+ * locks can't be held over the syscall boundary.
+ *
+ * If write=0, the page must not be written to. If the page is written to,
+ * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
+ * after the page is finished with, and before put_page is called.
+ *
+ * get_user_pages is typically used for fewer-copy IO operations, to get a
+ * handle on the memory by some means other than accesses via the user virtual
+ * addresses. The pages may be submitted for DMA to devices or accessed via
+ * their kernel linear mapping (via the kmap APIs). Care should be taken to
+ * use the correct cache flushing APIs.
+ *
+ * See also get_user_pages_fast, for performance critical applications.
+ *
+ * get_user_pages should be phased out in favor of
+ * get_user_pages_locked|unlocked or get_user_pages_fast. Nothing
+ * should use get_user_pages because it cannot pass
+ * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
+ */
+long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		unsigned long start, unsigned long nr_pages, int write,
+		int force, struct page **pages, struct vm_area_struct **vmas)
+{
+	return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
+				       pages, vmas, NULL, false, FOLL_TOUCH);
+}
+EXPORT_SYMBOL(get_user_pages);
+
+/**
+ * populate_vma_page_range() -  populate a range of pages in the vma.
+ * @vma:   target vma
+ * @start: start address
+ * @end:   end address
+ * @nonblocking:
+ *
+ * This takes care of mlocking the pages too if VM_LOCKED is set.
+ *
+ * return 0 on success, negative error code on error.
+ *
+ * vma->vm_mm->mmap_sem must be held.
+ *
+ * If @nonblocking is NULL, it may be held for read or write and will
+ * be unperturbed.
+ *
+ * If @nonblocking is non-NULL, it must held for read only and may be
+ * released.  If it's released, *@nonblocking will be set to 0.
+ */
+long populate_vma_page_range(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end, int *nonblocking)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long nr_pages = (end - start) / PAGE_SIZE;
+	int gup_flags;
+
+	VM_BUG_ON(start & ~PAGE_MASK);
+	VM_BUG_ON(end   & ~PAGE_MASK);
+	VM_BUG_ON_VMA(start < vma->vm_start, vma);
+	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+
+	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
+	if (vma->vm_flags & VM_LOCKONFAULT)
+		gup_flags &= ~FOLL_POPULATE;
+
+	/*
+	 * We want to touch writable mappings with a write fault in order
+	 * to break COW, except for shared mappings because these don't COW
+	 * and we would not want to dirty them for nothing.
+	 */
+	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
+		gup_flags |= FOLL_WRITE;
+
+	/*
+	 * We want mlock to succeed for regions that have any permissions
+	 * other than PROT_NONE.
+	 */
+	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
+		gup_flags |= FOLL_FORCE;
+
+	/*
+	 * We made sure addr is within a VMA, so the following will
+	 * not result in a stack expansion that recurses back here.
+	 */
+	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
+				NULL, NULL, nonblocking);
+}
+
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long end, nstart, nend;
+	struct vm_area_struct *vma = NULL;
+	int locked = 0;
+	long ret = 0;
+
+	VM_BUG_ON(start & ~PAGE_MASK);
+	VM_BUG_ON(len != PAGE_ALIGN(len));
+	end = start + len;
+
+	for (nstart = start; nstart < end; nstart = nend) {
+		/*
+		 * We want to fault in pages for [nstart; end) address range.
+		 * Find first corresponding VMA.
+		 */
+		if (!locked) {
+			locked = 1;
+			down_read(&mm->mmap_sem);
+			vma = find_vma(mm, nstart);
+		} else if (nstart >= vma->vm_end)
+			vma = vma->vm_next;
+		if (!vma || vma->vm_start >= end)
+			break;
+		/*
+		 * Set [nstart; nend) to intersection of desired address
+		 * range with the first VMA. Also, skip undesirable VMA types.
+		 */
+		nend = min(end, vma->vm_end);
+		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+			continue;
+		if (nstart < vma->vm_start)
+			nstart = vma->vm_start;
+		/*
+		 * Now fault in a range of pages. populate_vma_page_range()
+		 * double checks the vma flags, so that it won't mlock pages
+		 * if the vma was already munlocked.
+		 */
+		ret = populate_vma_page_range(vma, nstart, nend, &locked);
+		if (ret < 0) {
+			if (ignore_errors) {
+				ret = 0;
+				continue;	/* continue at next VMA */
+			}
+			break;
+		}
+		nend = nstart + ret * PAGE_SIZE;
+		ret = 0;
+	}
+	if (locked)
+		up_read(&mm->mmap_sem);
+	return ret;	/* 0 or negative error code */
+}
+
+/**
+ * get_dump_page() - pin user page in memory while writing it to core dump
+ * @addr: user address
+ *
+ * Returns struct page pointer of user page pinned for dump,
+ * to be freed afterwards by page_cache_release() or put_page().
+ *
+ * Returns NULL on any kind of failure - a hole must then be inserted into
+ * the corefile, to preserve alignment with its headers; and also returns
+ * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
+ * allowing a hole to be left in the corefile to save diskspace.
+ *
+ * Called without mmap_sem, but after all other threads have been killed.
+ */
+#ifdef CONFIG_ELF_CORE
+struct page *get_dump_page(unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	struct page *page;
+
+	if (__get_user_pages(current, current->mm, addr, 1,
+			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
+			     NULL) < 1)
+		return NULL;
+	flush_cache_page(vma, addr, page_to_pfn(page));
+	return page;
+}
+#endif /* CONFIG_ELF_CORE */
+
+/*
+ * Generic RCU Fast GUP
+ *
+ * get_user_pages_fast attempts to pin user pages by walking the page
+ * tables directly and avoids taking locks. Thus the walker needs to be
+ * protected from page table pages being freed from under it, and should
+ * block any THP splits.
+ *
+ * One way to achieve this is to have the walker disable interrupts, and
+ * rely on IPIs from the TLB flushing code blocking before the page table
+ * pages are freed. This is unsuitable for architectures that do not need
+ * to broadcast an IPI when invalidating TLBs.
+ *
+ * Another way to achieve this is to batch up page table containing pages
+ * belonging to more than one mm_user, then rcu_sched a callback to free those
+ * pages. Disabling interrupts will allow the fast_gup walker to both block
+ * the rcu_sched callback, and an IPI that we broadcast for splitting THPs
+ * (which is a relatively rare event). The code below adopts this strategy.
+ *
+ * Before activating this code, please be aware that the following assumptions
+ * are currently made:
+ *
+ *  *) HAVE_RCU_TABLE_FREE is enabled, and tlb_remove_table is used to free
+ *      pages containing page tables.
+ *
+ *  *) THP splits will broadcast an IPI, this can be achieved by overriding
+ *      pmdp_splitting_flush.
+ *
+ *  *) ptes can be read atomically by the architecture.
+ *
+ *  *) access_ok is sufficient to validate userspace address ranges.
+ *
+ * The last two assumptions can be relaxed by the addition of helper functions.
+ *
+ * This code is based heavily on the PowerPC implementation by Nick Piggin.
+ */
+#ifdef CONFIG_HAVE_GENERIC_RCU_GUP
+
+#ifdef __HAVE_ARCH_PTE_SPECIAL
+static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
+			 int write, struct page **pages, int *nr)
+{
+	pte_t *ptep, *ptem;
+	int ret = 0;
+
+	ptem = ptep = pte_offset_map(&pmd, addr);
+	do {
+		/*
+		 * In the line below we are assuming that the pte can be read
+		 * atomically. If this is not the case for your architecture,
+		 * please wrap this in a helper function!
+		 *
+		 * for an example see gup_get_pte in arch/x86/mm/gup.c
+		 */
+		pte_t pte = READ_ONCE(*ptep);
+		struct page *page;
+
+		/*
+		 * Similar to the PMD case below, NUMA hinting must take slow
+		 * path using the pte_protnone check.
+		 */
+		if (!pte_present(pte) || pte_special(pte) ||
+			pte_protnone(pte) || (write && !pte_write(pte)))
+			goto pte_unmap;
+
+		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+		page = pte_page(pte);
+
+		if (!page_cache_get_speculative(page))
+			goto pte_unmap;
+
+		if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+			put_page(page);
+			goto pte_unmap;
+		}
+
+		pages[*nr] = page;
+		(*nr)++;
+
+	} while (ptep++, addr += PAGE_SIZE, addr != end);
+
+	ret = 1;
+
+pte_unmap:
+	pte_unmap(ptem);
+	return ret;
+}
+#else
+
+/*
+ * If we can't determine whether or not a pte is special, then fail immediately
+ * for ptes. Note, we can still pin HugeTLB and THP as these are guaranteed not
+ * to be special.
+ *
+ * For a futex to be placed on a THP tail page, get_futex_key requires a
+ * __get_user_pages_fast implementation that can pin pages. Thus it's still
+ * useful to have gup_huge_pmd even if we can't operate on ptes.
+ */
+static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
+			 int write, struct page **pages, int *nr)
+{
+	return 0;
+}
+#endif /* __HAVE_ARCH_PTE_SPECIAL */
+
+static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
+		unsigned long end, int write, struct page **pages, int *nr)
+{
+	struct page *head, *page, *tail;
+	int refs;
+
+	if (write && !pmd_write(orig))
+		return 0;
+
+	refs = 0;
+	head = pmd_page(orig);
+	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	tail = page;
+	do {
+		VM_BUG_ON_PAGE(compound_head(page) != head, page);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	/*
+	 * Any tail pages need their mapcount reference taken before we
+	 * return. (This allows the THP code to bump their ref count when
+	 * they are split into base pages).
+	 */
+	while (refs--) {
+		if (PageTail(tail))
+			get_huge_page_tail(tail);
+		tail++;
+	}
+
+	return 1;
+}
+
+static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
+		unsigned long end, int write, struct page **pages, int *nr)
+{
+	struct page *head, *page, *tail;
+	int refs;
+
+	if (write && !pud_write(orig))
+		return 0;
+
+	refs = 0;
+	head = pud_page(orig);
+	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+	tail = page;
+	do {
+		VM_BUG_ON_PAGE(compound_head(page) != head, page);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pud_val(orig) != pud_val(*pudp))) {
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	while (refs--) {
+		if (PageTail(tail))
+			get_huge_page_tail(tail);
+		tail++;
+	}
+
+	return 1;
+}
+
+static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
+			unsigned long end, int write,
+			struct page **pages, int *nr)
+{
+	int refs;
+	struct page *head, *page, *tail;
+
+	if (write && !pgd_write(orig))
+		return 0;
+
+	refs = 0;
+	head = pgd_page(orig);
+	page = head + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
+	tail = page;
+	do {
+		VM_BUG_ON_PAGE(compound_head(page) != head, page);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) {
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	while (refs--) {
+		if (PageTail(tail))
+			get_huge_page_tail(tail);
+		tail++;
+	}
+
+	return 1;
+}
+
+static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
+		int write, struct page **pages, int *nr)
+{
+	unsigned long next;
+	pmd_t *pmdp;
+
+	pmdp = pmd_offset(&pud, addr);
+	do {
+		pmd_t pmd = READ_ONCE(*pmdp);
+
+		next = pmd_addr_end(addr, end);
+		if (pmd_none(pmd) || pmd_trans_splitting(pmd))
+			return 0;
+
+		if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd))) {
+			/*
+			 * NUMA hinting faults need to be handled in the GUP
+			 * slowpath for accounting purposes and so that they
+			 * can be serialised against THP migration.
+			 */
+			if (pmd_protnone(pmd))
+				return 0;
+
+			if (!gup_huge_pmd(pmd, pmdp, addr, next, write,
+				pages, nr))
+				return 0;
+
+		} else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd))))) {
+			/*
+			 * architecture have different format for hugetlbfs
+			 * pmd format and THP pmd format
+			 */
+			if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr,
+					 PMD_SHIFT, next, write, pages, nr))
+				return 0;
+		} else if (!gup_pte_range(pmd, addr, next, write, pages, nr))
+				return 0;
+	} while (pmdp++, addr = next, addr != end);
+
+	return 1;
+}
+
+static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
+			 int write, struct page **pages, int *nr)
+{
+	unsigned long next;
+	pud_t *pudp;
+
+	pudp = pud_offset(&pgd, addr);
+	do {
+		pud_t pud = READ_ONCE(*pudp);
+
+		next = pud_addr_end(addr, end);
+		if (pud_none(pud))
+			return 0;
+		if (unlikely(pud_huge(pud))) {
+			if (!gup_huge_pud(pud, pudp, addr, next, write,
+					  pages, nr))
+				return 0;
+		} else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) {
+			if (!gup_huge_pd(__hugepd(pud_val(pud)), addr,
+					 PUD_SHIFT, next, write, pages, nr))
+				return 0;
+		} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
+			return 0;
+	} while (pudp++, addr = next, addr != end);
+
+	return 1;
+}
+
+/*
+ * Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
+ * the regular GUP. It will only return non-negative values.
+ */
+int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
+			  struct page **pages)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long addr, len, end;
+	unsigned long next, flags;
+	pgd_t *pgdp;
+	int nr = 0;
+
+	start &= PAGE_MASK;
+	addr = start;
+	len = (unsigned long) nr_pages << PAGE_SHIFT;
+	end = start + len;
+
+	if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
+					start, len)))
+		return 0;
+
+	/*
+	 * Disable interrupts.  We use the nested form as we can already have
+	 * interrupts disabled by get_futex_key.
+	 *
+	 * With interrupts disabled, we block page table pages from being
+	 * freed from under us. See mmu_gather_tlb in asm-generic/tlb.h
+	 * for more details.
+	 *
+	 * We do not adopt an rcu_read_lock(.) here as we also want to
+	 * block IPIs that come from THPs splitting.
+	 */
+
+	local_irq_save(flags);
+	pgdp = pgd_offset(mm, addr);
+	do {
+		pgd_t pgd = READ_ONCE(*pgdp);
+
+		next = pgd_addr_end(addr, end);
+		if (pgd_none(pgd))
+			break;
+		if (unlikely(pgd_huge(pgd))) {
+			if (!gup_huge_pgd(pgd, pgdp, addr, next, write,
+					  pages, &nr))
+				break;
+		} else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd))))) {
+			if (!gup_huge_pd(__hugepd(pgd_val(pgd)), addr,
+					 PGDIR_SHIFT, next, write, pages, &nr))
+				break;
+		} else if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
+			break;
+	} while (pgdp++, addr = next, addr != end);
+	local_irq_restore(flags);
+
+	return nr;
+}
+
+/**
+ * get_user_pages_fast() - pin user pages in memory
+ * @start:	starting user address
+ * @nr_pages:	number of pages from start to pin
+ * @write:	whether pages will be written to
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_pages long.
+ *
+ * Attempt to pin user pages in memory without taking mm->mmap_sem.
+ * If not successful, it will fall back to taking the lock and
+ * calling get_user_pages().
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno.
+ */
+int get_user_pages_fast(unsigned long start, int nr_pages, int write,
+			struct page **pages)
+{
+	struct mm_struct *mm = current->mm;
+	int nr, ret;
+
+	start &= PAGE_MASK;
+	nr = __get_user_pages_fast(start, nr_pages, write, pages);
+	ret = nr;
+
+	if (nr < nr_pages) {
+		/* Try to get the remaining pages with get_user_pages */
+		start += nr << PAGE_SHIFT;
+		pages += nr;
+
+		ret = get_user_pages_unlocked(current, mm, start,
+					      nr_pages - nr, write, 0, pages);
+
+		/* Have to be a bit careful with return values */
+		if (nr > 0) {
+			if (ret < 0)
+				ret = nr;
+			else
+				ret += nr;
+		}
+	}
+
+	return ret;
+}
+
+#endif /* CONFIG_HAVE_GENERIC_RCU_GUP */
diff --git a/mm/highmem.c b/mm/highmem.c
new file mode 100644
index 0000000..123bcd3
--- /dev/null
+++ b/mm/highmem.c
@@ -0,0 +1,488 @@
+/*
+ * High memory handling common code and variables.
+ *
+ * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de
+ *          Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de
+ *
+ *
+ * Redesigned the x86 32-bit VM architecture to deal with
+ * 64-bit physical space. With current x86 CPUs this
+ * means up to 64 Gigabytes physical RAM.
+ *
+ * Rewrote high memory support to move the page cache into
+ * high memory. Implemented permanent (schedulable) kmaps
+ * based on Linus' idea.
+ *
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/swap.h>
+#include <linux/bio.h>
+#include <linux/pagemap.h>
+#include <linux/mempool.h>
+#include <linux/blkdev.h>
+#include <linux/init.h>
+#include <linux/hash.h>
+#include <linux/highmem.h>
+#include <linux/kgdb.h>
+#include <asm/tlbflush.h>
+
+
+#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
+DEFINE_PER_CPU(int, __kmap_atomic_idx);
+#endif
+
+/*
+ * Virtual_count is not a pure "count".
+ *  0 means that it is not mapped, and has not been mapped
+ *    since a TLB flush - it is usable.
+ *  1 means that there are no users, but it has been mapped
+ *    since the last TLB flush - so we can't use it.
+ *  n means that there are (n-1) current users of it.
+ */
+#ifdef CONFIG_HIGHMEM
+
+/*
+ * Architecture with aliasing data cache may define the following family of
+ * helper functions in its asm/highmem.h to control cache color of virtual
+ * addresses where physical memory pages are mapped by kmap.
+ */
+#ifndef get_pkmap_color
+
+/*
+ * Determine color of virtual address where the page should be mapped.
+ */
+static inline unsigned int get_pkmap_color(struct page *page)
+{
+	return 0;
+}
+#define get_pkmap_color get_pkmap_color
+
+/*
+ * Get next index for mapping inside PKMAP region for page with given color.
+ */
+static inline unsigned int get_next_pkmap_nr(unsigned int color)
+{
+	static unsigned int last_pkmap_nr;
+
+	last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
+	return last_pkmap_nr;
+}
+
+/*
+ * Determine if page index inside PKMAP region (pkmap_nr) of given color
+ * has wrapped around PKMAP region end. When this happens an attempt to
+ * flush all unused PKMAP slots is made.
+ */
+static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
+{
+	return pkmap_nr == 0;
+}
+
+/*
+ * Get the number of PKMAP entries of the given color. If no free slot is
+ * found after checking that many entries, kmap will sleep waiting for
+ * someone to call kunmap and free PKMAP slot.
+ */
+static inline int get_pkmap_entries_count(unsigned int color)
+{
+	return LAST_PKMAP;
+}
+
+/*
+ * Get head of a wait queue for PKMAP entries of the given color.
+ * Wait queues for different mapping colors should be independent to avoid
+ * unnecessary wakeups caused by freeing of slots of other colors.
+ */
+static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
+{
+	static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
+
+	return &pkmap_map_wait;
+}
+#endif
+
+unsigned long totalhigh_pages __read_mostly;
+EXPORT_SYMBOL(totalhigh_pages);
+
+
+EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
+
+unsigned int nr_free_highpages (void)
+{
+	pg_data_t *pgdat;
+	unsigned int pages = 0;
+
+	for_each_online_pgdat(pgdat) {
+		pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
+			NR_FREE_PAGES);
+		if (zone_movable_is_highmem())
+			pages += zone_page_state(
+					&pgdat->node_zones[ZONE_MOVABLE],
+					NR_FREE_PAGES);
+	}
+
+	return pages;
+}
+
+static int pkmap_count[LAST_PKMAP];
+static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
+
+pte_t * pkmap_page_table;
+
+/*
+ * Most architectures have no use for kmap_high_get(), so let's abstract
+ * the disabling of IRQ out of the locking in that case to save on a
+ * potential useless overhead.
+ */
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+#define lock_kmap()             spin_lock_irq(&kmap_lock)
+#define unlock_kmap()           spin_unlock_irq(&kmap_lock)
+#define lock_kmap_any(flags)    spin_lock_irqsave(&kmap_lock, flags)
+#define unlock_kmap_any(flags)  spin_unlock_irqrestore(&kmap_lock, flags)
+#else
+#define lock_kmap()             spin_lock(&kmap_lock)
+#define unlock_kmap()           spin_unlock(&kmap_lock)
+#define lock_kmap_any(flags)    \
+		do { spin_lock(&kmap_lock); (void)(flags); } while (0)
+#define unlock_kmap_any(flags)  \
+		do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
+#endif
+
+struct page *kmap_to_page(void *vaddr)
+{
+	unsigned long addr = (unsigned long)vaddr;
+
+	if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
+		int i = PKMAP_NR(addr);
+		return pte_page(pkmap_page_table[i]);
+	}
+
+	return virt_to_page(addr);
+}
+EXPORT_SYMBOL(kmap_to_page);
+
+static void flush_all_zero_pkmaps(void)
+{
+	int i;
+	int need_flush = 0;
+
+	flush_cache_kmaps();
+
+	for (i = 0; i < LAST_PKMAP; i++) {
+		struct page *page;
+
+		/*
+		 * zero means we don't have anything to do,
+		 * >1 means that it is still in use. Only
+		 * a count of 1 means that it is free but
+		 * needs to be unmapped
+		 */
+		if (pkmap_count[i] != 1)
+			continue;
+		pkmap_count[i] = 0;
+
+		/* sanity check */
+		BUG_ON(pte_none(pkmap_page_table[i]));
+
+		/*
+		 * Don't need an atomic fetch-and-clear op here;
+		 * no-one has the page mapped, and cannot get at
+		 * its virtual address (and hence PTE) without first
+		 * getting the kmap_lock (which is held here).
+		 * So no dangers, even with speculative execution.
+		 */
+		page = pte_page(pkmap_page_table[i]);
+		pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);
+
+		set_page_address(page, NULL);
+		need_flush = 1;
+	}
+	if (need_flush)
+		flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
+}
+
+/**
+ * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
+ */
+void kmap_flush_unused(void)
+{
+	lock_kmap();
+	flush_all_zero_pkmaps();
+	unlock_kmap();
+}
+
+static inline unsigned long map_new_virtual(struct page *page)
+{
+	unsigned long vaddr;
+	int count;
+	unsigned int last_pkmap_nr;
+	unsigned int color = get_pkmap_color(page);
+
+start:
+	count = get_pkmap_entries_count(color);
+	/* Find an empty entry */
+	for (;;) {
+		last_pkmap_nr = get_next_pkmap_nr(color);
+		if (no_more_pkmaps(last_pkmap_nr, color)) {
+			flush_all_zero_pkmaps();
+			count = get_pkmap_entries_count(color);
+		}
+		if (!pkmap_count[last_pkmap_nr])
+			break;	/* Found a usable entry */
+		if (--count)
+			continue;
+
+		/*
+		 * Sleep for somebody else to unmap their entries
+		 */
+		{
+			DECLARE_WAITQUEUE(wait, current);
+			wait_queue_head_t *pkmap_map_wait =
+				get_pkmap_wait_queue_head(color);
+
+			__set_current_state(TASK_UNINTERRUPTIBLE);
+			add_wait_queue(pkmap_map_wait, &wait);
+			unlock_kmap();
+			schedule();
+			remove_wait_queue(pkmap_map_wait, &wait);
+			lock_kmap();
+
+			/* Somebody else might have mapped it while we slept */
+			if (page_address(page))
+				return (unsigned long)page_address(page);
+
+			/* Re-start */
+			goto start;
+		}
+	}
+	vaddr = PKMAP_ADDR(last_pkmap_nr);
+	set_pte_at(&init_mm, vaddr,
+		   &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
+
+	pkmap_count[last_pkmap_nr] = 1;
+	set_page_address(page, (void *)vaddr);
+
+	return vaddr;
+}
+
+/**
+ * kmap_high - map a highmem page into memory
+ * @page: &struct page to map
+ *
+ * Returns the page's virtual memory address.
+ *
+ * We cannot call this from interrupts, as it may block.
+ */
+void *kmap_high(struct page *page)
+{
+	unsigned long vaddr;
+
+	/*
+	 * For highmem pages, we can't trust "virtual" until
+	 * after we have the lock.
+	 */
+	lock_kmap();
+	vaddr = (unsigned long)page_address(page);
+	if (!vaddr)
+		vaddr = map_new_virtual(page);
+	pkmap_count[PKMAP_NR(vaddr)]++;
+	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
+	unlock_kmap();
+	return (void*) vaddr;
+}
+
+EXPORT_SYMBOL(kmap_high);
+
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+/**
+ * kmap_high_get - pin a highmem page into memory
+ * @page: &struct page to pin
+ *
+ * Returns the page's current virtual memory address, or NULL if no mapping
+ * exists.  If and only if a non null address is returned then a
+ * matching call to kunmap_high() is necessary.
+ *
+ * This can be called from any context.
+ */
+void *kmap_high_get(struct page *page)
+{
+	unsigned long vaddr, flags;
+
+	lock_kmap_any(flags);
+	vaddr = (unsigned long)page_address(page);
+	if (vaddr) {
+		BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
+		pkmap_count[PKMAP_NR(vaddr)]++;
+	}
+	unlock_kmap_any(flags);
+	return (void*) vaddr;
+}
+#endif
+
+/**
+ * kunmap_high - unmap a highmem page into memory
+ * @page: &struct page to unmap
+ *
+ * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
+ * only from user context.
+ */
+void kunmap_high(struct page *page)
+{
+	unsigned long vaddr;
+	unsigned long nr;
+	unsigned long flags;
+	int need_wakeup;
+	unsigned int color = get_pkmap_color(page);
+	wait_queue_head_t *pkmap_map_wait;
+
+	lock_kmap_any(flags);
+	vaddr = (unsigned long)page_address(page);
+	BUG_ON(!vaddr);
+	nr = PKMAP_NR(vaddr);
+
+	/*
+	 * A count must never go down to zero
+	 * without a TLB flush!
+	 */
+	need_wakeup = 0;
+	switch (--pkmap_count[nr]) {
+	case 0:
+		BUG();
+	case 1:
+		/*
+		 * Avoid an unnecessary wake_up() function call.
+		 * The common case is pkmap_count[] == 1, but
+		 * no waiters.
+		 * The tasks queued in the wait-queue are guarded
+		 * by both the lock in the wait-queue-head and by
+		 * the kmap_lock.  As the kmap_lock is held here,
+		 * no need for the wait-queue-head's lock.  Simply
+		 * test if the queue is empty.
+		 */
+		pkmap_map_wait = get_pkmap_wait_queue_head(color);
+		need_wakeup = waitqueue_active(pkmap_map_wait);
+	}
+	unlock_kmap_any(flags);
+
+	/* do wake-up, if needed, race-free outside of the spin lock */
+	if (need_wakeup)
+		wake_up(pkmap_map_wait);
+}
+
+EXPORT_SYMBOL(kunmap_high);
+#endif
+
+#if defined(HASHED_PAGE_VIRTUAL)
+
+#define PA_HASH_ORDER	7
+
+/*
+ * Describes one page->virtual association
+ */
+struct page_address_map {
+	struct page *page;
+	void *virtual;
+	struct list_head list;
+};
+
+static struct page_address_map page_address_maps[LAST_PKMAP];
+
+/*
+ * Hash table bucket
+ */
+static struct page_address_slot {
+	struct list_head lh;			/* List of page_address_maps */
+	spinlock_t lock;			/* Protect this bucket's list */
+} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
+
+static struct page_address_slot *page_slot(const struct page *page)
+{
+	return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
+}
+
+/**
+ * page_address - get the mapped virtual address of a page
+ * @page: &struct page to get the virtual address of
+ *
+ * Returns the page's virtual address.
+ */
+void *page_address(const struct page *page)
+{
+	unsigned long flags;
+	void *ret;
+	struct page_address_slot *pas;
+
+	if (!PageHighMem(page))
+		return lowmem_page_address(page);
+
+	pas = page_slot(page);
+	ret = NULL;
+	spin_lock_irqsave(&pas->lock, flags);
+	if (!list_empty(&pas->lh)) {
+		struct page_address_map *pam;
+
+		list_for_each_entry(pam, &pas->lh, list) {
+			if (pam->page == page) {
+				ret = pam->virtual;
+				goto done;
+			}
+		}
+	}
+done:
+	spin_unlock_irqrestore(&pas->lock, flags);
+	return ret;
+}
+
+EXPORT_SYMBOL(page_address);
+
+/**
+ * set_page_address - set a page's virtual address
+ * @page: &struct page to set
+ * @virtual: virtual address to use
+ */
+void set_page_address(struct page *page, void *virtual)
+{
+	unsigned long flags;
+	struct page_address_slot *pas;
+	struct page_address_map *pam;
+
+	BUG_ON(!PageHighMem(page));
+
+	pas = page_slot(page);
+	if (virtual) {		/* Add */
+		pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
+		pam->page = page;
+		pam->virtual = virtual;
+
+		spin_lock_irqsave(&pas->lock, flags);
+		list_add_tail(&pam->list, &pas->lh);
+		spin_unlock_irqrestore(&pas->lock, flags);
+	} else {		/* Remove */
+		spin_lock_irqsave(&pas->lock, flags);
+		list_for_each_entry(pam, &pas->lh, list) {
+			if (pam->page == page) {
+				list_del(&pam->list);
+				spin_unlock_irqrestore(&pas->lock, flags);
+				goto done;
+			}
+		}
+		spin_unlock_irqrestore(&pas->lock, flags);
+	}
+done:
+	return;
+}
+
+void __init page_address_init(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
+		INIT_LIST_HEAD(&page_address_htable[i].lh);
+		spin_lock_init(&page_address_htable[i].lock);
+	}
+}
+
+#endif	/* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
new file mode 100644
index 0000000..6c6f5cc
--- /dev/null
+++ b/mm/huge_memory.c
@@ -0,0 +1,3100 @@
+/*
+ *  Copyright (C) 2009  Red Hat, Inc.
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2. See
+ *  the COPYING file in the top-level directory.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/hugetlb.h>
+#include <linux/mmu_notifier.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/shrinker.h>
+#include <linux/mm_inline.h>
+#include <linux/dax.h>
+#include <linux/kthread.h>
+#include <linux/khugepaged.h>
+#include <linux/freezer.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/migrate.h>
+#include <linux/hashtable.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/page_idle.h>
+
+#include <asm/tlb.h>
+#include <asm/pgalloc.h>
+#include "internal.h"
+
+/*
+ * By default transparent hugepage support is disabled in order that avoid
+ * to risk increase the memory footprint of applications without a guaranteed
+ * benefit. When transparent hugepage support is enabled, is for all mappings,
+ * and khugepaged scans all mappings.
+ * Defrag is invoked by khugepaged hugepage allocations and by page faults
+ * for all hugepage allocations.
+ */
+unsigned long transparent_hugepage_flags __read_mostly =
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
+	(1<<TRANSPARENT_HUGEPAGE_FLAG)|
+#endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
+	(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
+#endif
+	(1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
+	(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
+	(1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+
+/* default scan 8*512 pte (or vmas) every 30 second */
+static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
+static unsigned int khugepaged_pages_collapsed;
+static unsigned int khugepaged_full_scans;
+static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
+/* during fragmentation poll the hugepage allocator once every minute */
+static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
+static struct task_struct *khugepaged_thread __read_mostly;
+static DEFINE_MUTEX(khugepaged_mutex);
+static DEFINE_SPINLOCK(khugepaged_mm_lock);
+static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
+/*
+ * default collapse hugepages if there is at least one pte mapped like
+ * it would have happened if the vma was large enough during page
+ * fault.
+ */
+static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
+
+static int khugepaged(void *none);
+static int khugepaged_slab_init(void);
+static void khugepaged_slab_exit(void);
+
+#define MM_SLOTS_HASH_BITS 10
+static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
+
+static struct kmem_cache *mm_slot_cache __read_mostly;
+
+/**
+ * struct mm_slot - hash lookup from mm to mm_slot
+ * @hash: hash collision list
+ * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
+ * @mm: the mm that this information is valid for
+ */
+struct mm_slot {
+	struct hlist_node hash;
+	struct list_head mm_node;
+	struct mm_struct *mm;
+};
+
+/**
+ * struct khugepaged_scan - cursor for scanning
+ * @mm_head: the head of the mm list to scan
+ * @mm_slot: the current mm_slot we are scanning
+ * @address: the next address inside that to be scanned
+ *
+ * There is only the one khugepaged_scan instance of this cursor structure.
+ */
+struct khugepaged_scan {
+	struct list_head mm_head;
+	struct mm_slot *mm_slot;
+	unsigned long address;
+};
+static struct khugepaged_scan khugepaged_scan = {
+	.mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
+};
+
+
+static void set_recommended_min_free_kbytes(void)
+{
+	struct zone *zone;
+	int nr_zones = 0;
+	unsigned long recommended_min;
+
+	for_each_populated_zone(zone)
+		nr_zones++;
+
+	/* Ensure 2 pageblocks are free to assist fragmentation avoidance */
+	recommended_min = pageblock_nr_pages * nr_zones * 2;
+
+	/*
+	 * Make sure that on average at least two pageblocks are almost free
+	 * of another type, one for a migratetype to fall back to and a
+	 * second to avoid subsequent fallbacks of other types There are 3
+	 * MIGRATE_TYPES we care about.
+	 */
+	recommended_min += pageblock_nr_pages * nr_zones *
+			   MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
+
+	/* don't ever allow to reserve more than 5% of the lowmem */
+	recommended_min = min(recommended_min,
+			      (unsigned long) nr_free_buffer_pages() / 20);
+	recommended_min <<= (PAGE_SHIFT-10);
+
+	if (recommended_min > min_free_kbytes) {
+		if (user_min_free_kbytes >= 0)
+			pr_info("raising min_free_kbytes from %d to %lu "
+				"to help transparent hugepage allocations\n",
+				min_free_kbytes, recommended_min);
+
+		min_free_kbytes = recommended_min;
+	}
+	setup_per_zone_wmarks();
+}
+
+static int start_stop_khugepaged(void)
+{
+	int err = 0;
+	if (khugepaged_enabled()) {
+		if (!khugepaged_thread)
+			khugepaged_thread = kthread_run(khugepaged, NULL,
+							"khugepaged");
+		if (IS_ERR(khugepaged_thread)) {
+			pr_err("khugepaged: kthread_run(khugepaged) failed\n");
+			err = PTR_ERR(khugepaged_thread);
+			khugepaged_thread = NULL;
+			goto fail;
+		}
+
+		if (!list_empty(&khugepaged_scan.mm_head))
+			wake_up_interruptible(&khugepaged_wait);
+
+		set_recommended_min_free_kbytes();
+	} else if (khugepaged_thread) {
+		kthread_stop(khugepaged_thread);
+		khugepaged_thread = NULL;
+	}
+fail:
+	return err;
+}
+
+static atomic_t huge_zero_refcount;
+struct page *huge_zero_page __read_mostly;
+
+struct page *get_huge_zero_page(void)
+{
+	struct page *zero_page;
+retry:
+	if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
+		return READ_ONCE(huge_zero_page);
+
+	zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
+			HPAGE_PMD_ORDER);
+	if (!zero_page) {
+		count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
+		return NULL;
+	}
+	count_vm_event(THP_ZERO_PAGE_ALLOC);
+	preempt_disable();
+	if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
+		preempt_enable();
+		__free_pages(zero_page, compound_order(zero_page));
+		goto retry;
+	}
+
+	/* We take additional reference here. It will be put back by shrinker */
+	atomic_set(&huge_zero_refcount, 2);
+	preempt_enable();
+	return READ_ONCE(huge_zero_page);
+}
+
+static void put_huge_zero_page(void)
+{
+	/*
+	 * Counter should never go to zero here. Only shrinker can put
+	 * last reference.
+	 */
+	BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
+}
+
+static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
+					struct shrink_control *sc)
+{
+	/* we can free zero page only if last reference remains */
+	return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
+}
+
+static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
+				       struct shrink_control *sc)
+{
+	if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
+		struct page *zero_page = xchg(&huge_zero_page, NULL);
+		BUG_ON(zero_page == NULL);
+		__free_pages(zero_page, compound_order(zero_page));
+		return HPAGE_PMD_NR;
+	}
+
+	return 0;
+}
+
+static struct shrinker huge_zero_page_shrinker = {
+	.count_objects = shrink_huge_zero_page_count,
+	.scan_objects = shrink_huge_zero_page_scan,
+	.seeks = DEFAULT_SEEKS,
+};
+
+#ifdef CONFIG_SYSFS
+
+static ssize_t double_flag_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf,
+				enum transparent_hugepage_flag enabled,
+				enum transparent_hugepage_flag req_madv)
+{
+	if (test_bit(enabled, &transparent_hugepage_flags)) {
+		VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
+		return sprintf(buf, "[always] madvise never\n");
+	} else if (test_bit(req_madv, &transparent_hugepage_flags))
+		return sprintf(buf, "always [madvise] never\n");
+	else
+		return sprintf(buf, "always madvise [never]\n");
+}
+static ssize_t double_flag_store(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 const char *buf, size_t count,
+				 enum transparent_hugepage_flag enabled,
+				 enum transparent_hugepage_flag req_madv)
+{
+	if (!memcmp("always", buf,
+		    min(sizeof("always")-1, count))) {
+		set_bit(enabled, &transparent_hugepage_flags);
+		clear_bit(req_madv, &transparent_hugepage_flags);
+	} else if (!memcmp("madvise", buf,
+			   min(sizeof("madvise")-1, count))) {
+		clear_bit(enabled, &transparent_hugepage_flags);
+		set_bit(req_madv, &transparent_hugepage_flags);
+	} else if (!memcmp("never", buf,
+			   min(sizeof("never")-1, count))) {
+		clear_bit(enabled, &transparent_hugepage_flags);
+		clear_bit(req_madv, &transparent_hugepage_flags);
+	} else
+		return -EINVAL;
+
+	return count;
+}
+
+static ssize_t enabled_show(struct kobject *kobj,
+			    struct kobj_attribute *attr, char *buf)
+{
+	return double_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_FLAG,
+				TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+}
+static ssize_t enabled_store(struct kobject *kobj,
+			     struct kobj_attribute *attr,
+			     const char *buf, size_t count)
+{
+	ssize_t ret;
+
+	ret = double_flag_store(kobj, attr, buf, count,
+				TRANSPARENT_HUGEPAGE_FLAG,
+				TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+
+	if (ret > 0) {
+		int err;
+
+		mutex_lock(&khugepaged_mutex);
+		err = start_stop_khugepaged();
+		mutex_unlock(&khugepaged_mutex);
+
+		if (err)
+			ret = err;
+	}
+
+	return ret;
+}
+static struct kobj_attribute enabled_attr =
+	__ATTR(enabled, 0644, enabled_show, enabled_store);
+
+static ssize_t single_flag_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf,
+				enum transparent_hugepage_flag flag)
+{
+	return sprintf(buf, "%d\n",
+		       !!test_bit(flag, &transparent_hugepage_flags));
+}
+
+static ssize_t single_flag_store(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 const char *buf, size_t count,
+				 enum transparent_hugepage_flag flag)
+{
+	unsigned long value;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &value);
+	if (ret < 0)
+		return ret;
+	if (value > 1)
+		return -EINVAL;
+
+	if (value)
+		set_bit(flag, &transparent_hugepage_flags);
+	else
+		clear_bit(flag, &transparent_hugepage_flags);
+
+	return count;
+}
+
+/*
+ * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
+ * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
+ * memory just to allocate one more hugepage.
+ */
+static ssize_t defrag_show(struct kobject *kobj,
+			   struct kobj_attribute *attr, char *buf)
+{
+	return double_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+				TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
+}
+static ssize_t defrag_store(struct kobject *kobj,
+			    struct kobj_attribute *attr,
+			    const char *buf, size_t count)
+{
+	return double_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+				 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
+}
+static struct kobj_attribute defrag_attr =
+	__ATTR(defrag, 0644, defrag_show, defrag_store);
+
+static ssize_t use_zero_page_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return single_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+}
+static ssize_t use_zero_page_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	return single_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+}
+static struct kobj_attribute use_zero_page_attr =
+	__ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
+#ifdef CONFIG_DEBUG_VM
+static ssize_t debug_cow_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return single_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
+}
+static ssize_t debug_cow_store(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       const char *buf, size_t count)
+{
+	return single_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
+}
+static struct kobj_attribute debug_cow_attr =
+	__ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
+#endif /* CONFIG_DEBUG_VM */
+
+static struct attribute *hugepage_attr[] = {
+	&enabled_attr.attr,
+	&defrag_attr.attr,
+	&use_zero_page_attr.attr,
+#ifdef CONFIG_DEBUG_VM
+	&debug_cow_attr.attr,
+#endif
+	NULL,
+};
+
+static struct attribute_group hugepage_attr_group = {
+	.attrs = hugepage_attr,
+};
+
+static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
+}
+
+static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  const char *buf, size_t count)
+{
+	unsigned long msecs;
+	int err;
+
+	err = kstrtoul(buf, 10, &msecs);
+	if (err || msecs > UINT_MAX)
+		return -EINVAL;
+
+	khugepaged_scan_sleep_millisecs = msecs;
+	wake_up_interruptible(&khugepaged_wait);
+
+	return count;
+}
+static struct kobj_attribute scan_sleep_millisecs_attr =
+	__ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
+	       scan_sleep_millisecs_store);
+
+static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
+}
+
+static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
+					   struct kobj_attribute *attr,
+					   const char *buf, size_t count)
+{
+	unsigned long msecs;
+	int err;
+
+	err = kstrtoul(buf, 10, &msecs);
+	if (err || msecs > UINT_MAX)
+		return -EINVAL;
+
+	khugepaged_alloc_sleep_millisecs = msecs;
+	wake_up_interruptible(&khugepaged_wait);
+
+	return count;
+}
+static struct kobj_attribute alloc_sleep_millisecs_attr =
+	__ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
+	       alloc_sleep_millisecs_store);
+
+static ssize_t pages_to_scan_show(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
+}
+static ssize_t pages_to_scan_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int err;
+	unsigned long pages;
+
+	err = kstrtoul(buf, 10, &pages);
+	if (err || !pages || pages > UINT_MAX)
+		return -EINVAL;
+
+	khugepaged_pages_to_scan = pages;
+
+	return count;
+}
+static struct kobj_attribute pages_to_scan_attr =
+	__ATTR(pages_to_scan, 0644, pages_to_scan_show,
+	       pages_to_scan_store);
+
+static ssize_t pages_collapsed_show(struct kobject *kobj,
+				    struct kobj_attribute *attr,
+				    char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
+}
+static struct kobj_attribute pages_collapsed_attr =
+	__ATTR_RO(pages_collapsed);
+
+static ssize_t full_scans_show(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_full_scans);
+}
+static struct kobj_attribute full_scans_attr =
+	__ATTR_RO(full_scans);
+
+static ssize_t khugepaged_defrag_show(struct kobject *kobj,
+				      struct kobj_attribute *attr, char *buf)
+{
+	return single_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+}
+static ssize_t khugepaged_defrag_store(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	return single_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+}
+static struct kobj_attribute khugepaged_defrag_attr =
+	__ATTR(defrag, 0644, khugepaged_defrag_show,
+	       khugepaged_defrag_store);
+
+/*
+ * max_ptes_none controls if khugepaged should collapse hugepages over
+ * any unmapped ptes in turn potentially increasing the memory
+ * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
+ * reduce the available free memory in the system as it
+ * runs. Increasing max_ptes_none will instead potentially reduce the
+ * free memory in the system during the khugepaged scan.
+ */
+static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
+					     struct kobj_attribute *attr,
+					     char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
+}
+static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
+					      struct kobj_attribute *attr,
+					      const char *buf, size_t count)
+{
+	int err;
+	unsigned long max_ptes_none;
+
+	err = kstrtoul(buf, 10, &max_ptes_none);
+	if (err || max_ptes_none > HPAGE_PMD_NR-1)
+		return -EINVAL;
+
+	khugepaged_max_ptes_none = max_ptes_none;
+
+	return count;
+}
+static struct kobj_attribute khugepaged_max_ptes_none_attr =
+	__ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
+	       khugepaged_max_ptes_none_store);
+
+static struct attribute *khugepaged_attr[] = {
+	&khugepaged_defrag_attr.attr,
+	&khugepaged_max_ptes_none_attr.attr,
+	&pages_to_scan_attr.attr,
+	&pages_collapsed_attr.attr,
+	&full_scans_attr.attr,
+	&scan_sleep_millisecs_attr.attr,
+	&alloc_sleep_millisecs_attr.attr,
+	NULL,
+};
+
+static struct attribute_group khugepaged_attr_group = {
+	.attrs = khugepaged_attr,
+	.name = "khugepaged",
+};
+
+static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
+{
+	int err;
+
+	*hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
+	if (unlikely(!*hugepage_kobj)) {
+		pr_err("failed to create transparent hugepage kobject\n");
+		return -ENOMEM;
+	}
+
+	err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
+	if (err) {
+		pr_err("failed to register transparent hugepage group\n");
+		goto delete_obj;
+	}
+
+	err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
+	if (err) {
+		pr_err("failed to register transparent hugepage group\n");
+		goto remove_hp_group;
+	}
+
+	return 0;
+
+remove_hp_group:
+	sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
+delete_obj:
+	kobject_put(*hugepage_kobj);
+	return err;
+}
+
+static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
+{
+	sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
+	sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
+	kobject_put(hugepage_kobj);
+}
+#else
+static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
+{
+	return 0;
+}
+
+static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
+{
+}
+#endif /* CONFIG_SYSFS */
+
+static int __init hugepage_init(void)
+{
+	int err;
+	struct kobject *hugepage_kobj;
+
+	if (!has_transparent_hugepage()) {
+		transparent_hugepage_flags = 0;
+		return -EINVAL;
+	}
+
+	err = hugepage_init_sysfs(&hugepage_kobj);
+	if (err)
+		goto err_sysfs;
+
+	err = khugepaged_slab_init();
+	if (err)
+		goto err_slab;
+
+	err = register_shrinker(&huge_zero_page_shrinker);
+	if (err)
+		goto err_hzp_shrinker;
+
+	/*
+	 * By default disable transparent hugepages on smaller systems,
+	 * where the extra memory used could hurt more than TLB overhead
+	 * is likely to save.  The admin can still enable it through /sys.
+	 */
+	if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
+		transparent_hugepage_flags = 0;
+		return 0;
+	}
+
+	err = start_stop_khugepaged();
+	if (err)
+		goto err_khugepaged;
+
+	return 0;
+err_khugepaged:
+	unregister_shrinker(&huge_zero_page_shrinker);
+err_hzp_shrinker:
+	khugepaged_slab_exit();
+err_slab:
+	hugepage_exit_sysfs(hugepage_kobj);
+err_sysfs:
+	return err;
+}
+subsys_initcall(hugepage_init);
+
+static int __init setup_transparent_hugepage(char *str)
+{
+	int ret = 0;
+	if (!str)
+		goto out;
+	if (!strcmp(str, "always")) {
+		set_bit(TRANSPARENT_HUGEPAGE_FLAG,
+			&transparent_hugepage_flags);
+		clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+			  &transparent_hugepage_flags);
+		ret = 1;
+	} else if (!strcmp(str, "madvise")) {
+		clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+			  &transparent_hugepage_flags);
+		set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+			&transparent_hugepage_flags);
+		ret = 1;
+	} else if (!strcmp(str, "never")) {
+		clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+			  &transparent_hugepage_flags);
+		clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+			  &transparent_hugepage_flags);
+		ret = 1;
+	}
+out:
+	if (!ret)
+		pr_warn("transparent_hugepage= cannot parse, ignored\n");
+	return ret;
+}
+__setup("transparent_hugepage=", setup_transparent_hugepage);
+
+pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
+{
+	if (likely(vma->vm_flags & VM_WRITE))
+		pmd = pmd_mkwrite(pmd);
+	return pmd;
+}
+
+static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
+{
+	pmd_t entry;
+	entry = mk_pmd(page, prot);
+	entry = pmd_mkhuge(entry);
+	return entry;
+}
+
+static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
+					struct vm_area_struct *vma,
+					unsigned long address, pmd_t *pmd,
+					struct page *page, gfp_t gfp,
+					unsigned int flags)
+{
+	struct mem_cgroup *memcg;
+	pgtable_t pgtable;
+	spinlock_t *ptl;
+	unsigned long haddr = address & HPAGE_PMD_MASK;
+
+	VM_BUG_ON_PAGE(!PageCompound(page), page);
+
+	if (mem_cgroup_try_charge(page, mm, gfp, &memcg)) {
+		put_page(page);
+		count_vm_event(THP_FAULT_FALLBACK);
+		return VM_FAULT_FALLBACK;
+	}
+
+	pgtable = pte_alloc_one(mm, haddr);
+	if (unlikely(!pgtable)) {
+		mem_cgroup_cancel_charge(page, memcg);
+		put_page(page);
+		return VM_FAULT_OOM;
+	}
+
+	clear_huge_page(page, haddr, HPAGE_PMD_NR);
+	/*
+	 * The memory barrier inside __SetPageUptodate makes sure that
+	 * clear_huge_page writes become visible before the set_pmd_at()
+	 * write.
+	 */
+	__SetPageUptodate(page);
+
+	ptl = pmd_lock(mm, pmd);
+	if (unlikely(!pmd_none(*pmd))) {
+		spin_unlock(ptl);
+		mem_cgroup_cancel_charge(page, memcg);
+		put_page(page);
+		pte_free(mm, pgtable);
+	} else {
+		pmd_t entry;
+
+		/* Deliver the page fault to userland */
+		if (userfaultfd_missing(vma)) {
+			int ret;
+
+			spin_unlock(ptl);
+			mem_cgroup_cancel_charge(page, memcg);
+			put_page(page);
+			pte_free(mm, pgtable);
+			ret = handle_userfault(vma, address, flags,
+					       VM_UFFD_MISSING);
+			VM_BUG_ON(ret & VM_FAULT_FALLBACK);
+			return ret;
+		}
+
+		entry = mk_huge_pmd(page, vma->vm_page_prot);
+		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+		page_add_new_anon_rmap(page, vma, haddr);
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_active_or_unevictable(page, vma);
+		pgtable_trans_huge_deposit(mm, pmd, pgtable);
+		set_pmd_at(mm, haddr, pmd, entry);
+		add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
+		atomic_long_inc(&mm->nr_ptes);
+		spin_unlock(ptl);
+		count_vm_event(THP_FAULT_ALLOC);
+	}
+
+	return 0;
+}
+
+static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
+{
+	return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_RECLAIM)) | extra_gfp;
+}
+
+/* Caller must hold page table lock. */
+static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
+		struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
+		struct page *zero_page)
+{
+	pmd_t entry;
+	if (!pmd_none(*pmd))
+		return false;
+	entry = mk_pmd(zero_page, vma->vm_page_prot);
+	entry = pmd_mkhuge(entry);
+	pgtable_trans_huge_deposit(mm, pmd, pgtable);
+	set_pmd_at(mm, haddr, pmd, entry);
+	atomic_long_inc(&mm->nr_ptes);
+	return true;
+}
+
+int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			       unsigned long address, pmd_t *pmd,
+			       unsigned int flags)
+{
+	gfp_t gfp;
+	struct page *page;
+	unsigned long haddr = address & HPAGE_PMD_MASK;
+
+	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
+		return VM_FAULT_FALLBACK;
+	if (unlikely(anon_vma_prepare(vma)))
+		return VM_FAULT_OOM;
+	if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
+		return VM_FAULT_OOM;
+	if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
+			transparent_hugepage_use_zero_page()) {
+		spinlock_t *ptl;
+		pgtable_t pgtable;
+		struct page *zero_page;
+		bool set;
+		int ret;
+		pgtable = pte_alloc_one(mm, haddr);
+		if (unlikely(!pgtable))
+			return VM_FAULT_OOM;
+		zero_page = get_huge_zero_page();
+		if (unlikely(!zero_page)) {
+			pte_free(mm, pgtable);
+			count_vm_event(THP_FAULT_FALLBACK);
+			return VM_FAULT_FALLBACK;
+		}
+		ptl = pmd_lock(mm, pmd);
+		ret = 0;
+		set = false;
+		if (pmd_none(*pmd)) {
+			if (userfaultfd_missing(vma)) {
+				spin_unlock(ptl);
+				ret = handle_userfault(vma, address, flags,
+						       VM_UFFD_MISSING);
+				VM_BUG_ON(ret & VM_FAULT_FALLBACK);
+			} else {
+				set_huge_zero_page(pgtable, mm, vma,
+						   haddr, pmd,
+						   zero_page);
+				spin_unlock(ptl);
+				set = true;
+			}
+		} else
+			spin_unlock(ptl);
+		if (!set) {
+			pte_free(mm, pgtable);
+			put_huge_zero_page();
+		}
+		return ret;
+	}
+	gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
+	page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
+	if (unlikely(!page)) {
+		count_vm_event(THP_FAULT_FALLBACK);
+		return VM_FAULT_FALLBACK;
+	}
+	return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp,
+					    flags);
+}
+
+static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
+		pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pmd_t entry;
+	spinlock_t *ptl;
+
+	ptl = pmd_lock(mm, pmd);
+	if (pmd_none(*pmd)) {
+		entry = pmd_mkhuge(pfn_pmd(pfn, prot));
+		if (write) {
+			entry = pmd_mkyoung(pmd_mkdirty(entry));
+			entry = maybe_pmd_mkwrite(entry, vma);
+		}
+		set_pmd_at(mm, addr, pmd, entry);
+		update_mmu_cache_pmd(vma, addr, pmd);
+	}
+	spin_unlock(ptl);
+}
+
+int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
+			pmd_t *pmd, unsigned long pfn, bool write)
+{
+	pgprot_t pgprot = vma->vm_page_prot;
+	/*
+	 * If we had pmd_special, we could avoid all these restrictions,
+	 * but we need to be consistent with PTEs and architectures that
+	 * can't support a 'special' bit.
+	 */
+	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
+	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
+						(VM_PFNMAP|VM_MIXEDMAP));
+	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
+	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
+
+	if (addr < vma->vm_start || addr >= vma->vm_end)
+		return VM_FAULT_SIGBUS;
+	if (track_pfn_insert(vma, &pgprot, pfn))
+		return VM_FAULT_SIGBUS;
+	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
+	return VM_FAULT_NOPAGE;
+}
+
+int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		  pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
+		  struct vm_area_struct *vma)
+{
+	spinlock_t *dst_ptl, *src_ptl;
+	struct page *src_page;
+	pmd_t pmd;
+	pgtable_t pgtable;
+	int ret;
+
+	ret = -ENOMEM;
+	pgtable = pte_alloc_one(dst_mm, addr);
+	if (unlikely(!pgtable))
+		goto out;
+
+	dst_ptl = pmd_lock(dst_mm, dst_pmd);
+	src_ptl = pmd_lockptr(src_mm, src_pmd);
+	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+
+	ret = -EAGAIN;
+	pmd = *src_pmd;
+	if (unlikely(!pmd_trans_huge(pmd))) {
+		pte_free(dst_mm, pgtable);
+		goto out_unlock;
+	}
+	/*
+	 * When page table lock is held, the huge zero pmd should not be
+	 * under splitting since we don't split the page itself, only pmd to
+	 * a page table.
+	 */
+	if (is_huge_zero_pmd(pmd)) {
+		struct page *zero_page;
+		/*
+		 * get_huge_zero_page() will never allocate a new page here,
+		 * since we already have a zero page to copy. It just takes a
+		 * reference.
+		 */
+		zero_page = get_huge_zero_page();
+		set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
+				zero_page);
+		ret = 0;
+		goto out_unlock;
+	}
+
+	if (unlikely(pmd_trans_splitting(pmd))) {
+		/* split huge page running from under us */
+		spin_unlock(src_ptl);
+		spin_unlock(dst_ptl);
+		pte_free(dst_mm, pgtable);
+
+		wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
+		goto out;
+	}
+	src_page = pmd_page(pmd);
+	VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+	get_page(src_page);
+	page_dup_rmap(src_page);
+	add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+
+	pmdp_set_wrprotect(src_mm, addr, src_pmd);
+	pmd = pmd_mkold(pmd_wrprotect(pmd));
+	pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+	set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+	atomic_long_inc(&dst_mm->nr_ptes);
+
+	ret = 0;
+out_unlock:
+	spin_unlock(src_ptl);
+	spin_unlock(dst_ptl);
+out:
+	return ret;
+}
+
+void huge_pmd_set_accessed(struct mm_struct *mm,
+			   struct vm_area_struct *vma,
+			   unsigned long address,
+			   pmd_t *pmd, pmd_t orig_pmd,
+			   int dirty)
+{
+	spinlock_t *ptl;
+	pmd_t entry;
+	unsigned long haddr;
+
+	ptl = pmd_lock(mm, pmd);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		goto unlock;
+
+	entry = pmd_mkyoung(orig_pmd);
+	haddr = address & HPAGE_PMD_MASK;
+	if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
+		update_mmu_cache_pmd(vma, address, pmd);
+
+unlock:
+	spin_unlock(ptl);
+}
+
+/*
+ * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
+ * during copy_user_huge_page()'s copy_page_rep(): in the case when
+ * the source page gets split and a tail freed before copy completes.
+ * Called under pmd_lock of checked pmd, so safe from splitting itself.
+ */
+static void get_user_huge_page(struct page *page)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
+		struct page *endpage = page + HPAGE_PMD_NR;
+
+		atomic_add(HPAGE_PMD_NR, &page->_count);
+		while (++page < endpage)
+			get_huge_page_tail(page);
+	} else {
+		get_page(page);
+	}
+}
+
+static void put_user_huge_page(struct page *page)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
+		struct page *endpage = page + HPAGE_PMD_NR;
+
+		while (page < endpage)
+			put_page(page++);
+	} else {
+		put_page(page);
+	}
+}
+
+static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
+					struct vm_area_struct *vma,
+					unsigned long address,
+					pmd_t *pmd, pmd_t orig_pmd,
+					struct page *page,
+					unsigned long haddr)
+{
+	struct mem_cgroup *memcg;
+	spinlock_t *ptl;
+	pgtable_t pgtable;
+	pmd_t _pmd;
+	int ret = 0, i;
+	struct page **pages;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+
+	pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
+			GFP_KERNEL);
+	if (unlikely(!pages)) {
+		ret |= VM_FAULT_OOM;
+		goto out;
+	}
+
+	for (i = 0; i < HPAGE_PMD_NR; i++) {
+		pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
+					       __GFP_OTHER_NODE,
+					       vma, address, page_to_nid(page));
+		if (unlikely(!pages[i] ||
+			     mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
+						   &memcg))) {
+			if (pages[i])
+				put_page(pages[i]);
+			while (--i >= 0) {
+				memcg = (void *)page_private(pages[i]);
+				set_page_private(pages[i], 0);
+				mem_cgroup_cancel_charge(pages[i], memcg);
+				put_page(pages[i]);
+			}
+			kfree(pages);
+			ret |= VM_FAULT_OOM;
+			goto out;
+		}
+		set_page_private(pages[i], (unsigned long)memcg);
+	}
+
+	for (i = 0; i < HPAGE_PMD_NR; i++) {
+		copy_user_highpage(pages[i], page + i,
+				   haddr + PAGE_SIZE * i, vma);
+		__SetPageUptodate(pages[i]);
+		cond_resched();
+	}
+
+	mmun_start = haddr;
+	mmun_end   = haddr + HPAGE_PMD_SIZE;
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+	ptl = pmd_lock(mm, pmd);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		goto out_free_pages;
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+
+	pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+	/* leave pmd empty until pte is filled */
+
+	pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+	pmd_populate(mm, &_pmd, pgtable);
+
+	for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+		pte_t *pte, entry;
+		entry = mk_pte(pages[i], vma->vm_page_prot);
+		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+		memcg = (void *)page_private(pages[i]);
+		set_page_private(pages[i], 0);
+		page_add_new_anon_rmap(pages[i], vma, haddr);
+		mem_cgroup_commit_charge(pages[i], memcg, false);
+		lru_cache_add_active_or_unevictable(pages[i], vma);
+		pte = pte_offset_map(&_pmd, haddr);
+		VM_BUG_ON(!pte_none(*pte));
+		set_pte_at(mm, haddr, pte, entry);
+		pte_unmap(pte);
+	}
+	kfree(pages);
+
+	smp_wmb(); /* make pte visible before pmd */
+	pmd_populate(mm, pmd, pgtable);
+	page_remove_rmap(page);
+	spin_unlock(ptl);
+
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+	ret |= VM_FAULT_WRITE;
+	put_page(page);
+
+out:
+	return ret;
+
+out_free_pages:
+	spin_unlock(ptl);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+	for (i = 0; i < HPAGE_PMD_NR; i++) {
+		memcg = (void *)page_private(pages[i]);
+		set_page_private(pages[i], 0);
+		mem_cgroup_cancel_charge(pages[i], memcg);
+		put_page(pages[i]);
+	}
+	kfree(pages);
+	goto out;
+}
+
+int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
+{
+	spinlock_t *ptl;
+	int ret = 0;
+	struct page *page = NULL, *new_page;
+	struct mem_cgroup *memcg;
+	unsigned long haddr;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+	gfp_t huge_gfp;			/* for allocation and charge */
+
+	ptl = pmd_lockptr(mm, pmd);
+	VM_BUG_ON_VMA(!vma->anon_vma, vma);
+	haddr = address & HPAGE_PMD_MASK;
+	if (is_huge_zero_pmd(orig_pmd))
+		goto alloc;
+	spin_lock(ptl);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		goto out_unlock;
+
+	page = pmd_page(orig_pmd);
+	VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
+	if (page_mapcount(page) == 1) {
+		pmd_t entry;
+		entry = pmd_mkyoung(orig_pmd);
+		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+		if (pmdp_set_access_flags(vma, haddr, pmd, entry,  1))
+			update_mmu_cache_pmd(vma, address, pmd);
+		ret |= VM_FAULT_WRITE;
+		goto out_unlock;
+	}
+	get_user_huge_page(page);
+	spin_unlock(ptl);
+alloc:
+	if (transparent_hugepage_enabled(vma) &&
+	    !transparent_hugepage_debug_cow()) {
+		huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
+		new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
+	} else
+		new_page = NULL;
+
+	if (unlikely(!new_page)) {
+		if (!page) {
+			split_huge_page_pmd(vma, address, pmd);
+			ret |= VM_FAULT_FALLBACK;
+		} else {
+			ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
+					pmd, orig_pmd, page, haddr);
+			if (ret & VM_FAULT_OOM) {
+				split_huge_page(page);
+				ret |= VM_FAULT_FALLBACK;
+			}
+			put_user_huge_page(page);
+		}
+		count_vm_event(THP_FAULT_FALLBACK);
+		goto out;
+	}
+
+	if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) {
+		put_page(new_page);
+		if (page) {
+			split_huge_page(page);
+			put_user_huge_page(page);
+		} else
+			split_huge_page_pmd(vma, address, pmd);
+		ret |= VM_FAULT_FALLBACK;
+		count_vm_event(THP_FAULT_FALLBACK);
+		goto out;
+	}
+
+	count_vm_event(THP_FAULT_ALLOC);
+
+	if (!page)
+		clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
+	else
+		copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
+	__SetPageUptodate(new_page);
+
+	mmun_start = haddr;
+	mmun_end   = haddr + HPAGE_PMD_SIZE;
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+	spin_lock(ptl);
+	if (page)
+		put_user_huge_page(page);
+	if (unlikely(!pmd_same(*pmd, orig_pmd))) {
+		spin_unlock(ptl);
+		mem_cgroup_cancel_charge(new_page, memcg);
+		put_page(new_page);
+		goto out_mn;
+	} else {
+		pmd_t entry;
+		entry = mk_huge_pmd(new_page, vma->vm_page_prot);
+		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+		pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+		page_add_new_anon_rmap(new_page, vma, haddr);
+		mem_cgroup_commit_charge(new_page, memcg, false);
+		lru_cache_add_active_or_unevictable(new_page, vma);
+		set_pmd_at(mm, haddr, pmd, entry);
+		update_mmu_cache_pmd(vma, address, pmd);
+		if (!page) {
+			add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
+			put_huge_zero_page();
+		} else {
+			VM_BUG_ON_PAGE(!PageHead(page), page);
+			page_remove_rmap(page);
+			put_page(page);
+		}
+		ret |= VM_FAULT_WRITE;
+	}
+	spin_unlock(ptl);
+out_mn:
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out:
+	return ret;
+out_unlock:
+	spin_unlock(ptl);
+	return ret;
+}
+
+/*
+ * FOLL_FORCE can write to even unwritable pmd's, but only
+ * after we've gone through a COW cycle and they are dirty.
+ */
+static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
+{
+	return pmd_write(pmd) ||
+	       ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
+}
+
+struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
+				   unsigned long addr,
+				   pmd_t *pmd,
+				   unsigned int flags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct page *page = NULL;
+
+	assert_spin_locked(pmd_lockptr(mm, pmd));
+
+	if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
+		goto out;
+
+	/* Avoid dumping huge zero page */
+	if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
+		return ERR_PTR(-EFAULT);
+
+	/* Full NUMA hinting faults to serialise migration in fault paths */
+	if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
+		goto out;
+
+	page = pmd_page(*pmd);
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+	if (flags & FOLL_TOUCH) {
+		pmd_t _pmd;
+		/*
+		 * We should set the dirty bit only for FOLL_WRITE but
+		 * for now the dirty bit in the pmd is meaningless.
+		 * And if the dirty bit will become meaningful and
+		 * we'll only set it with FOLL_WRITE, an atomic
+		 * set_bit will be required on the pmd to set the
+		 * young bit, instead of the current set_pmd_at.
+		 */
+		_pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
+		if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
+					  pmd, _pmd,  1))
+			update_mmu_cache_pmd(vma, addr, pmd);
+	}
+	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
+		if (page->mapping && trylock_page(page)) {
+			lru_add_drain();
+			if (page->mapping)
+				mlock_vma_page(page);
+			unlock_page(page);
+		}
+	}
+	page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
+	VM_BUG_ON_PAGE(!PageCompound(page), page);
+	if (flags & FOLL_GET)
+		get_page_foll(page);
+
+out:
+	return page;
+}
+
+/* NUMA hinting page fault entry point for trans huge pmds */
+int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
+				unsigned long addr, pmd_t pmd, pmd_t *pmdp)
+{
+	spinlock_t *ptl;
+	struct anon_vma *anon_vma = NULL;
+	struct page *page;
+	unsigned long haddr = addr & HPAGE_PMD_MASK;
+	int page_nid = -1, this_nid = numa_node_id();
+	int target_nid, last_cpupid = -1;
+	bool page_locked;
+	bool migrated = false;
+	bool was_writable;
+	int flags = 0;
+
+	/* A PROT_NONE fault should not end up here */
+	BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
+
+	ptl = pmd_lock(mm, pmdp);
+	if (unlikely(!pmd_same(pmd, *pmdp)))
+		goto out_unlock;
+
+	/*
+	 * If there are potential migrations, wait for completion and retry
+	 * without disrupting NUMA hinting information. Do not relock and
+	 * check_same as the page may no longer be mapped.
+	 */
+	if (unlikely(pmd_trans_migrating(*pmdp))) {
+		page = pmd_page(*pmdp);
+		if (!get_page_unless_zero(page))
+			goto out_unlock;
+		spin_unlock(ptl);
+		wait_on_page_locked(page);
+		put_page(page);
+		goto out;
+	}
+
+	page = pmd_page(pmd);
+	BUG_ON(is_huge_zero_page(page));
+	page_nid = page_to_nid(page);
+	last_cpupid = page_cpupid_last(page);
+	count_vm_numa_event(NUMA_HINT_FAULTS);
+	if (page_nid == this_nid) {
+		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
+		flags |= TNF_FAULT_LOCAL;
+	}
+
+	/* See similar comment in do_numa_page for explanation */
+	if (!(vma->vm_flags & VM_WRITE))
+		flags |= TNF_NO_GROUP;
+
+	/*
+	 * Acquire the page lock to serialise THP migrations but avoid dropping
+	 * page_table_lock if at all possible
+	 */
+	page_locked = trylock_page(page);
+	target_nid = mpol_misplaced(page, vma, haddr);
+	if (target_nid == -1) {
+		/* If the page was locked, there are no parallel migrations */
+		if (page_locked)
+			goto clear_pmdnuma;
+	}
+
+	/* Migration could have started since the pmd_trans_migrating check */
+	if (!page_locked) {
+		if (!get_page_unless_zero(page))
+			goto out_unlock;
+		spin_unlock(ptl);
+		wait_on_page_locked(page);
+		put_page(page);
+		page_nid = -1;
+		goto out;
+	}
+
+	/*
+	 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
+	 * to serialises splits
+	 */
+	get_page(page);
+	spin_unlock(ptl);
+	anon_vma = page_lock_anon_vma_read(page);
+
+	/* Confirm the PMD did not change while page_table_lock was released */
+	spin_lock(ptl);
+	if (unlikely(!pmd_same(pmd, *pmdp))) {
+		unlock_page(page);
+		put_page(page);
+		page_nid = -1;
+		goto out_unlock;
+	}
+
+	/* Bail if we fail to protect against THP splits for any reason */
+	if (unlikely(!anon_vma)) {
+		put_page(page);
+		page_nid = -1;
+		goto clear_pmdnuma;
+	}
+
+	/*
+	 * Migrate the THP to the requested node, returns with page unlocked
+	 * and access rights restored.
+	 */
+	spin_unlock(ptl);
+	migrated = migrate_misplaced_transhuge_page(mm, vma,
+				pmdp, pmd, addr, page, target_nid);
+	if (migrated) {
+		flags |= TNF_MIGRATED;
+		page_nid = target_nid;
+	} else
+		flags |= TNF_MIGRATE_FAIL;
+
+	goto out;
+clear_pmdnuma:
+	BUG_ON(!PageLocked(page));
+	was_writable = pmd_write(pmd);
+	pmd = pmd_modify(pmd, vma->vm_page_prot);
+	pmd = pmd_mkyoung(pmd);
+	if (was_writable)
+		pmd = pmd_mkwrite(pmd);
+	set_pmd_at(mm, haddr, pmdp, pmd);
+	update_mmu_cache_pmd(vma, addr, pmdp);
+	unlock_page(page);
+out_unlock:
+	spin_unlock(ptl);
+
+out:
+	if (anon_vma)
+		page_unlock_anon_vma_read(anon_vma);
+
+	if (page_nid != -1)
+		task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
+
+	return 0;
+}
+
+int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+		 pmd_t *pmd, unsigned long addr)
+{
+	pmd_t orig_pmd;
+	spinlock_t *ptl;
+
+	if (__pmd_trans_huge_lock(pmd, vma, &ptl) != 1)
+		return 0;
+	/*
+	 * For architectures like ppc64 we look at deposited pgtable
+	 * when calling pmdp_huge_get_and_clear. So do the
+	 * pgtable_trans_huge_withdraw after finishing pmdp related
+	 * operations.
+	 */
+	orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
+			tlb->fullmm);
+	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+	if (vma_is_dax(vma)) {
+		spin_unlock(ptl);
+		if (is_huge_zero_pmd(orig_pmd))
+			put_huge_zero_page();
+	} else if (is_huge_zero_pmd(orig_pmd)) {
+		pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
+		atomic_long_dec(&tlb->mm->nr_ptes);
+		spin_unlock(ptl);
+		put_huge_zero_page();
+	} else {
+		struct page *page = pmd_page(orig_pmd);
+		page_remove_rmap(page);
+		VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
+		add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+		VM_BUG_ON_PAGE(!PageHead(page), page);
+		pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
+		atomic_long_dec(&tlb->mm->nr_ptes);
+		spin_unlock(ptl);
+		tlb_remove_page(tlb, page);
+	}
+	return 1;
+}
+
+int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
+		  unsigned long old_addr,
+		  unsigned long new_addr, unsigned long old_end,
+		  pmd_t *old_pmd, pmd_t *new_pmd)
+{
+	spinlock_t *old_ptl, *new_ptl;
+	int ret = 0;
+	pmd_t pmd;
+
+	struct mm_struct *mm = vma->vm_mm;
+
+	if ((old_addr & ~HPAGE_PMD_MASK) ||
+	    (new_addr & ~HPAGE_PMD_MASK) ||
+	    old_end - old_addr < HPAGE_PMD_SIZE ||
+	    (new_vma->vm_flags & VM_NOHUGEPAGE))
+		goto out;
+
+	/*
+	 * The destination pmd shouldn't be established, free_pgtables()
+	 * should have release it.
+	 */
+	if (WARN_ON(!pmd_none(*new_pmd))) {
+		VM_BUG_ON(pmd_trans_huge(*new_pmd));
+		goto out;
+	}
+
+	/*
+	 * We don't have to worry about the ordering of src and dst
+	 * ptlocks because exclusive mmap_sem prevents deadlock.
+	 */
+	ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
+	if (ret == 1) {
+		new_ptl = pmd_lockptr(mm, new_pmd);
+		if (new_ptl != old_ptl)
+			spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
+		pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
+		VM_BUG_ON(!pmd_none(*new_pmd));
+
+		if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
+			pgtable_t pgtable;
+			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
+		}
+		set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
+		if (new_ptl != old_ptl)
+			spin_unlock(new_ptl);
+		spin_unlock(old_ptl);
+	}
+out:
+	return ret;
+}
+
+/*
+ * Returns
+ *  - 0 if PMD could not be locked
+ *  - 1 if PMD was locked but protections unchange and TLB flush unnecessary
+ *  - HPAGE_PMD_NR is protections changed and TLB flush necessary
+ */
+int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+		unsigned long addr, pgprot_t newprot, int prot_numa)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	spinlock_t *ptl;
+	int ret = 0;
+
+	if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+		pmd_t entry;
+		bool preserve_write = prot_numa && pmd_write(*pmd);
+		ret = 1;
+
+		/*
+		 * Avoid trapping faults against the zero page. The read-only
+		 * data is likely to be read-cached on the local CPU and
+		 * local/remote hits to the zero page are not interesting.
+		 */
+		if (prot_numa && is_huge_zero_pmd(*pmd)) {
+			spin_unlock(ptl);
+			return ret;
+		}
+
+		if (!prot_numa || !pmd_protnone(*pmd)) {
+			entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
+			entry = pmd_modify(entry, newprot);
+			if (preserve_write)
+				entry = pmd_mkwrite(entry);
+			ret = HPAGE_PMD_NR;
+			set_pmd_at(mm, addr, pmd, entry);
+			BUG_ON(!preserve_write && pmd_write(entry));
+		}
+		spin_unlock(ptl);
+	}
+
+	return ret;
+}
+
+/*
+ * Returns 1 if a given pmd maps a stable (not under splitting) thp.
+ * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
+ *
+ * Note that if it returns 1, this routine returns without unlocking page
+ * table locks. So callers must unlock them.
+ */
+int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
+		spinlock_t **ptl)
+{
+	*ptl = pmd_lock(vma->vm_mm, pmd);
+	if (likely(pmd_trans_huge(*pmd))) {
+		if (unlikely(pmd_trans_splitting(*pmd))) {
+			spin_unlock(*ptl);
+			wait_split_huge_page(vma->anon_vma, pmd);
+			return -1;
+		} else {
+			/* Thp mapped by 'pmd' is stable, so we can
+			 * handle it as it is. */
+			return 1;
+		}
+	}
+	spin_unlock(*ptl);
+	return 0;
+}
+
+/*
+ * This function returns whether a given @page is mapped onto the @address
+ * in the virtual space of @mm.
+ *
+ * When it's true, this function returns *pmd with holding the page table lock
+ * and passing it back to the caller via @ptl.
+ * If it's false, returns NULL without holding the page table lock.
+ */
+pmd_t *page_check_address_pmd(struct page *page,
+			      struct mm_struct *mm,
+			      unsigned long address,
+			      enum page_check_address_pmd_flag flag,
+			      spinlock_t **ptl)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	if (address & ~HPAGE_PMD_MASK)
+		return NULL;
+
+	pgd = pgd_offset(mm, address);
+	if (!pgd_present(*pgd))
+		return NULL;
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		return NULL;
+	pmd = pmd_offset(pud, address);
+
+	*ptl = pmd_lock(mm, pmd);
+	if (!pmd_present(*pmd))
+		goto unlock;
+	if (pmd_page(*pmd) != page)
+		goto unlock;
+	/*
+	 * split_vma() may create temporary aliased mappings. There is
+	 * no risk as long as all huge pmd are found and have their
+	 * splitting bit set before __split_huge_page_refcount
+	 * runs. Finding the same huge pmd more than once during the
+	 * same rmap walk is not a problem.
+	 */
+	if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
+	    pmd_trans_splitting(*pmd))
+		goto unlock;
+	if (pmd_trans_huge(*pmd)) {
+		VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
+			  !pmd_trans_splitting(*pmd));
+		return pmd;
+	}
+unlock:
+	spin_unlock(*ptl);
+	return NULL;
+}
+
+static int __split_huge_page_splitting(struct page *page,
+				       struct vm_area_struct *vma,
+				       unsigned long address)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	spinlock_t *ptl;
+	pmd_t *pmd;
+	int ret = 0;
+	/* For mmu_notifiers */
+	const unsigned long mmun_start = address;
+	const unsigned long mmun_end   = address + HPAGE_PMD_SIZE;
+
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	pmd = page_check_address_pmd(page, mm, address,
+			PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
+	if (pmd) {
+		/*
+		 * We can't temporarily set the pmd to null in order
+		 * to split it, the pmd must remain marked huge at all
+		 * times or the VM won't take the pmd_trans_huge paths
+		 * and it won't wait on the anon_vma->root->rwsem to
+		 * serialize against split_huge_page*.
+		 */
+		pmdp_splitting_flush(vma, address, pmd);
+
+		ret = 1;
+		spin_unlock(ptl);
+	}
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+	return ret;
+}
+
+static void __split_huge_page_refcount(struct page *page,
+				       struct list_head *list)
+{
+	int i;
+	struct zone *zone = page_zone(page);
+	struct lruvec *lruvec;
+	int tail_count = 0;
+
+	/* prevent PageLRU to go away from under us, and freeze lru stats */
+	spin_lock_irq(&zone->lru_lock);
+	lruvec = mem_cgroup_page_lruvec(page, zone);
+
+	compound_lock(page);
+	/* complete memcg works before add pages to LRU */
+	mem_cgroup_split_huge_fixup(page);
+
+	for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
+		struct page *page_tail = page + i;
+
+		/* tail_page->_mapcount cannot change */
+		BUG_ON(page_mapcount(page_tail) < 0);
+		tail_count += page_mapcount(page_tail);
+		/* check for overflow */
+		BUG_ON(tail_count < 0);
+		BUG_ON(atomic_read(&page_tail->_count) != 0);
+		/*
+		 * tail_page->_count is zero and not changing from
+		 * under us. But get_page_unless_zero() may be running
+		 * from under us on the tail_page. If we used
+		 * atomic_set() below instead of atomic_add(), we
+		 * would then run atomic_set() concurrently with
+		 * get_page_unless_zero(), and atomic_set() is
+		 * implemented in C not using locked ops. spin_unlock
+		 * on x86 sometime uses locked ops because of PPro
+		 * errata 66, 92, so unless somebody can guarantee
+		 * atomic_set() here would be safe on all archs (and
+		 * not only on x86), it's safer to use atomic_add().
+		 */
+		atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
+			   &page_tail->_count);
+
+		/* after clearing PageTail the gup refcount can be released */
+		smp_mb__after_atomic();
+
+		page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+		page_tail->flags |= (page->flags &
+				     ((1L << PG_referenced) |
+				      (1L << PG_swapbacked) |
+				      (1L << PG_mlocked) |
+				      (1L << PG_uptodate) |
+				      (1L << PG_active) |
+				      (1L << PG_unevictable)));
+		page_tail->flags |= (1L << PG_dirty);
+
+		clear_compound_head(page_tail);
+
+		if (page_is_young(page))
+			set_page_young(page_tail);
+		if (page_is_idle(page))
+			set_page_idle(page_tail);
+
+		/*
+		 * __split_huge_page_splitting() already set the
+		 * splitting bit in all pmd that could map this
+		 * hugepage, that will ensure no CPU can alter the
+		 * mapcount on the head page. The mapcount is only
+		 * accounted in the head page and it has to be
+		 * transferred to all tail pages in the below code. So
+		 * for this code to be safe, the split the mapcount
+		 * can't change. But that doesn't mean userland can't
+		 * keep changing and reading the page contents while
+		 * we transfer the mapcount, so the pmd splitting
+		 * status is achieved setting a reserved bit in the
+		 * pmd, not by clearing the present bit.
+		*/
+		page_tail->_mapcount = page->_mapcount;
+
+		BUG_ON(page_tail->mapping);
+		page_tail->mapping = page->mapping;
+
+		page_tail->index = page->index + i;
+		page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
+
+		BUG_ON(!PageAnon(page_tail));
+		BUG_ON(!PageUptodate(page_tail));
+		BUG_ON(!PageDirty(page_tail));
+		BUG_ON(!PageSwapBacked(page_tail));
+
+		lru_add_page_tail(page, page_tail, lruvec, list);
+	}
+	atomic_sub(tail_count, &page->_count);
+	BUG_ON(atomic_read(&page->_count) <= 0);
+
+	__mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
+
+	ClearPageCompound(page);
+	compound_unlock(page);
+	spin_unlock_irq(&zone->lru_lock);
+
+	for (i = 1; i < HPAGE_PMD_NR; i++) {
+		struct page *page_tail = page + i;
+		BUG_ON(page_count(page_tail) <= 0);
+		/*
+		 * Tail pages may be freed if there wasn't any mapping
+		 * like if add_to_swap() is running on a lru page that
+		 * had its mapping zapped. And freeing these pages
+		 * requires taking the lru_lock so we do the put_page
+		 * of the tail pages after the split is complete.
+		 */
+		put_page(page_tail);
+	}
+
+	/*
+	 * Only the head page (now become a regular page) is required
+	 * to be pinned by the caller.
+	 */
+	BUG_ON(page_count(page) <= 0);
+}
+
+static int __split_huge_page_map(struct page *page,
+				 struct vm_area_struct *vma,
+				 unsigned long address)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	spinlock_t *ptl;
+	pmd_t *pmd, _pmd;
+	int ret = 0, i;
+	pgtable_t pgtable;
+	unsigned long haddr;
+
+	pmd = page_check_address_pmd(page, mm, address,
+			PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
+	if (pmd) {
+		pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+		pmd_populate(mm, &_pmd, pgtable);
+		if (pmd_write(*pmd))
+			BUG_ON(page_mapcount(page) != 1);
+
+		haddr = address;
+		for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+			pte_t *pte, entry;
+			BUG_ON(PageCompound(page+i));
+			/*
+			 * Note that NUMA hinting access restrictions are not
+			 * transferred to avoid any possibility of altering
+			 * permissions across VMAs.
+			 */
+			entry = mk_pte(page + i, vma->vm_page_prot);
+			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+			if (!pmd_write(*pmd))
+				entry = pte_wrprotect(entry);
+			if (!pmd_young(*pmd))
+				entry = pte_mkold(entry);
+			pte = pte_offset_map(&_pmd, haddr);
+			BUG_ON(!pte_none(*pte));
+			set_pte_at(mm, haddr, pte, entry);
+			pte_unmap(pte);
+		}
+
+		smp_wmb(); /* make pte visible before pmd */
+		/*
+		 * Up to this point the pmd is present and huge and
+		 * userland has the whole access to the hugepage
+		 * during the split (which happens in place). If we
+		 * overwrite the pmd with the not-huge version
+		 * pointing to the pte here (which of course we could
+		 * if all CPUs were bug free), userland could trigger
+		 * a small page size TLB miss on the small sized TLB
+		 * while the hugepage TLB entry is still established
+		 * in the huge TLB. Some CPU doesn't like that. See
+		 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
+		 * Erratum 383 on page 93. Intel should be safe but is
+		 * also warns that it's only safe if the permission
+		 * and cache attributes of the two entries loaded in
+		 * the two TLB is identical (which should be the case
+		 * here). But it is generally safer to never allow
+		 * small and huge TLB entries for the same virtual
+		 * address to be loaded simultaneously. So instead of
+		 * doing "pmd_populate(); flush_pmd_tlb_range();" we first
+		 * mark the current pmd notpresent (atomically because
+		 * here the pmd_trans_huge and pmd_trans_splitting
+		 * must remain set at all times on the pmd until the
+		 * split is complete for this pmd), then we flush the
+		 * SMP TLB and finally we write the non-huge version
+		 * of the pmd entry with pmd_populate.
+		 */
+		pmdp_invalidate(vma, address, pmd);
+		pmd_populate(mm, pmd, pgtable);
+		ret = 1;
+		spin_unlock(ptl);
+	}
+
+	return ret;
+}
+
+/* must be called with anon_vma->root->rwsem held */
+static void __split_huge_page(struct page *page,
+			      struct anon_vma *anon_vma,
+			      struct list_head *list)
+{
+	int mapcount, mapcount2;
+	pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+	struct anon_vma_chain *avc;
+
+	BUG_ON(!PageHead(page));
+	BUG_ON(PageTail(page));
+
+	mapcount = 0;
+	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
+		struct vm_area_struct *vma = avc->vma;
+		unsigned long addr = vma_address(page, vma);
+		BUG_ON(is_vma_temporary_stack(vma));
+		mapcount += __split_huge_page_splitting(page, vma, addr);
+	}
+	/*
+	 * It is critical that new vmas are added to the tail of the
+	 * anon_vma list. This guarantes that if copy_huge_pmd() runs
+	 * and establishes a child pmd before
+	 * __split_huge_page_splitting() freezes the parent pmd (so if
+	 * we fail to prevent copy_huge_pmd() from running until the
+	 * whole __split_huge_page() is complete), we will still see
+	 * the newly established pmd of the child later during the
+	 * walk, to be able to set it as pmd_trans_splitting too.
+	 */
+	if (mapcount != page_mapcount(page)) {
+		pr_err("mapcount %d page_mapcount %d\n",
+			mapcount, page_mapcount(page));
+		BUG();
+	}
+
+	__split_huge_page_refcount(page, list);
+
+	mapcount2 = 0;
+	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
+		struct vm_area_struct *vma = avc->vma;
+		unsigned long addr = vma_address(page, vma);
+		BUG_ON(is_vma_temporary_stack(vma));
+		mapcount2 += __split_huge_page_map(page, vma, addr);
+	}
+	if (mapcount != mapcount2) {
+		pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
+			mapcount, mapcount2, page_mapcount(page));
+		BUG();
+	}
+}
+
+/*
+ * Split a hugepage into normal pages. This doesn't change the position of head
+ * page. If @list is null, tail pages will be added to LRU list, otherwise, to
+ * @list. Both head page and tail pages will inherit mapping, flags, and so on
+ * from the hugepage.
+ * Return 0 if the hugepage is split successfully otherwise return 1.
+ */
+int split_huge_page_to_list(struct page *page, struct list_head *list)
+{
+	struct anon_vma *anon_vma;
+	int ret = 1;
+
+	BUG_ON(is_huge_zero_page(page));
+	BUG_ON(!PageAnon(page));
+
+	/*
+	 * The caller does not necessarily hold an mmap_sem that would prevent
+	 * the anon_vma disappearing so we first we take a reference to it
+	 * and then lock the anon_vma for write. This is similar to
+	 * page_lock_anon_vma_read except the write lock is taken to serialise
+	 * against parallel split or collapse operations.
+	 */
+	anon_vma = page_get_anon_vma(page);
+	if (!anon_vma)
+		goto out;
+	anon_vma_lock_write(anon_vma);
+
+	ret = 0;
+	if (!PageCompound(page))
+		goto out_unlock;
+
+	BUG_ON(!PageSwapBacked(page));
+	__split_huge_page(page, anon_vma, list);
+	count_vm_event(THP_SPLIT);
+
+	BUG_ON(PageCompound(page));
+out_unlock:
+	anon_vma_unlock_write(anon_vma);
+	put_anon_vma(anon_vma);
+out:
+	return ret;
+}
+
+#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
+
+int hugepage_madvise(struct vm_area_struct *vma,
+		     unsigned long *vm_flags, int advice)
+{
+	switch (advice) {
+	case MADV_HUGEPAGE:
+#ifdef CONFIG_S390
+		/*
+		 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
+		 * can't handle this properly after s390_enable_sie, so we simply
+		 * ignore the madvise to prevent qemu from causing a SIGSEGV.
+		 */
+		if (mm_has_pgste(vma->vm_mm))
+			return 0;
+#endif
+		/*
+		 * Be somewhat over-protective like KSM for now!
+		 */
+		if (*vm_flags & VM_NO_THP)
+			return -EINVAL;
+		*vm_flags &= ~VM_NOHUGEPAGE;
+		*vm_flags |= VM_HUGEPAGE;
+		/*
+		 * If the vma become good for khugepaged to scan,
+		 * register it here without waiting a page fault that
+		 * may not happen any time soon.
+		 */
+		if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
+			return -ENOMEM;
+		break;
+	case MADV_NOHUGEPAGE:
+		/*
+		 * Be somewhat over-protective like KSM for now!
+		 */
+		if (*vm_flags & VM_NO_THP)
+			return -EINVAL;
+		*vm_flags &= ~VM_HUGEPAGE;
+		*vm_flags |= VM_NOHUGEPAGE;
+		/*
+		 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
+		 * this vma even if we leave the mm registered in khugepaged if
+		 * it got registered before VM_NOHUGEPAGE was set.
+		 */
+		break;
+	}
+
+	return 0;
+}
+
+static int __init khugepaged_slab_init(void)
+{
+	mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
+					  sizeof(struct mm_slot),
+					  __alignof__(struct mm_slot), 0, NULL);
+	if (!mm_slot_cache)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void __init khugepaged_slab_exit(void)
+{
+	kmem_cache_destroy(mm_slot_cache);
+}
+
+static inline struct mm_slot *alloc_mm_slot(void)
+{
+	if (!mm_slot_cache)	/* initialization failed */
+		return NULL;
+	return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
+}
+
+static inline void free_mm_slot(struct mm_slot *mm_slot)
+{
+	kmem_cache_free(mm_slot_cache, mm_slot);
+}
+
+static struct mm_slot *get_mm_slot(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+
+	hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
+		if (mm == mm_slot->mm)
+			return mm_slot;
+
+	return NULL;
+}
+
+static void insert_to_mm_slots_hash(struct mm_struct *mm,
+				    struct mm_slot *mm_slot)
+{
+	mm_slot->mm = mm;
+	hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
+}
+
+static inline int khugepaged_test_exit(struct mm_struct *mm)
+{
+	return atomic_read(&mm->mm_users) == 0;
+}
+
+int __khugepaged_enter(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	int wakeup;
+
+	mm_slot = alloc_mm_slot();
+	if (!mm_slot)
+		return -ENOMEM;
+
+	/* __khugepaged_exit() must not run from under us */
+	VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
+	if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
+		free_mm_slot(mm_slot);
+		return 0;
+	}
+
+	spin_lock(&khugepaged_mm_lock);
+	insert_to_mm_slots_hash(mm, mm_slot);
+	/*
+	 * Insert just behind the scanning cursor, to let the area settle
+	 * down a little.
+	 */
+	wakeup = list_empty(&khugepaged_scan.mm_head);
+	list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
+	spin_unlock(&khugepaged_mm_lock);
+
+	atomic_inc(&mm->mm_count);
+	if (wakeup)
+		wake_up_interruptible(&khugepaged_wait);
+
+	return 0;
+}
+
+int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
+			       unsigned long vm_flags)
+{
+	unsigned long hstart, hend;
+	if (!vma->anon_vma)
+		/*
+		 * Not yet faulted in so we will register later in the
+		 * page fault if needed.
+		 */
+		return 0;
+	if (vma->vm_ops || (vm_flags & VM_NO_THP))
+		/* khugepaged not yet working on file or special mappings */
+		return 0;
+	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+	hend = vma->vm_end & HPAGE_PMD_MASK;
+	if (hstart < hend)
+		return khugepaged_enter(vma, vm_flags);
+	return 0;
+}
+
+void __khugepaged_exit(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	int free = 0;
+
+	spin_lock(&khugepaged_mm_lock);
+	mm_slot = get_mm_slot(mm);
+	if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
+		hash_del(&mm_slot->hash);
+		list_del(&mm_slot->mm_node);
+		free = 1;
+	}
+	spin_unlock(&khugepaged_mm_lock);
+
+	if (free) {
+		clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
+		free_mm_slot(mm_slot);
+		mmdrop(mm);
+	} else if (mm_slot) {
+		/*
+		 * This is required to serialize against
+		 * khugepaged_test_exit() (which is guaranteed to run
+		 * under mmap sem read mode). Stop here (after we
+		 * return all pagetables will be destroyed) until
+		 * khugepaged has finished working on the pagetables
+		 * under the mmap_sem.
+		 */
+		down_write(&mm->mmap_sem);
+		up_write(&mm->mmap_sem);
+	}
+}
+
+static void release_pte_page(struct page *page)
+{
+	/* 0 stands for page_is_file_cache(page) == false */
+	dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
+	unlock_page(page);
+	putback_lru_page(page);
+}
+
+static void release_pte_pages(pte_t *pte, pte_t *_pte)
+{
+	while (--_pte >= pte) {
+		pte_t pteval = *_pte;
+		if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
+			release_pte_page(pte_page(pteval));
+	}
+}
+
+static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
+					unsigned long address,
+					pte_t *pte)
+{
+	struct page *page;
+	pte_t *_pte;
+	int none_or_zero = 0;
+	bool referenced = false, writable = false;
+	for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
+	     _pte++, address += PAGE_SIZE) {
+		pte_t pteval = *_pte;
+		if (pte_none(pteval) || (pte_present(pteval) &&
+				is_zero_pfn(pte_pfn(pteval)))) {
+			if (!userfaultfd_armed(vma) &&
+			    ++none_or_zero <= khugepaged_max_ptes_none)
+				continue;
+			else
+				goto out;
+		}
+		if (!pte_present(pteval))
+			goto out;
+		page = vm_normal_page(vma, address, pteval);
+		if (unlikely(!page))
+			goto out;
+
+		VM_BUG_ON_PAGE(PageCompound(page), page);
+		VM_BUG_ON_PAGE(!PageAnon(page), page);
+		VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+
+		/*
+		 * We can do it before isolate_lru_page because the
+		 * page can't be freed from under us. NOTE: PG_lock
+		 * is needed to serialize against split_huge_page
+		 * when invoked from the VM.
+		 */
+		if (!trylock_page(page))
+			goto out;
+
+		/*
+		 * cannot use mapcount: can't collapse if there's a gup pin.
+		 * The page must only be referenced by the scanned process
+		 * and page swap cache.
+		 */
+		if (page_count(page) != 1 + !!PageSwapCache(page)) {
+			unlock_page(page);
+			goto out;
+		}
+		if (pte_write(pteval)) {
+			writable = true;
+		} else {
+			if (PageSwapCache(page) && !reuse_swap_page(page)) {
+				unlock_page(page);
+				goto out;
+			}
+			/*
+			 * Page is not in the swap cache. It can be collapsed
+			 * into a THP.
+			 */
+		}
+
+		/*
+		 * Isolate the page to avoid collapsing an hugepage
+		 * currently in use by the VM.
+		 */
+		if (isolate_lru_page(page)) {
+			unlock_page(page);
+			goto out;
+		}
+		/* 0 stands for page_is_file_cache(page) == false */
+		inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
+		VM_BUG_ON_PAGE(!PageLocked(page), page);
+		VM_BUG_ON_PAGE(PageLRU(page), page);
+
+		/* If there is no mapped pte young don't collapse the page */
+		if (pte_young(pteval) ||
+		    page_is_young(page) || PageReferenced(page) ||
+		    mmu_notifier_test_young(vma->vm_mm, address))
+			referenced = true;
+	}
+	if (likely(referenced && writable))
+		return 1;
+out:
+	release_pte_pages(pte, _pte);
+	return 0;
+}
+
+static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
+				      struct vm_area_struct *vma,
+				      unsigned long address,
+				      spinlock_t *ptl)
+{
+	pte_t *_pte;
+	for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
+		pte_t pteval = *_pte;
+		struct page *src_page;
+
+		if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+			clear_user_highpage(page, address);
+			add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
+			if (is_zero_pfn(pte_pfn(pteval))) {
+				/*
+				 * ptl mostly unnecessary.
+				 */
+				spin_lock(ptl);
+				/*
+				 * paravirt calls inside pte_clear here are
+				 * superfluous.
+				 */
+				pte_clear(vma->vm_mm, address, _pte);
+				spin_unlock(ptl);
+			}
+		} else {
+			src_page = pte_page(pteval);
+			copy_user_highpage(page, src_page, address, vma);
+			VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
+			release_pte_page(src_page);
+			/*
+			 * ptl mostly unnecessary, but preempt has to
+			 * be disabled to update the per-cpu stats
+			 * inside page_remove_rmap().
+			 */
+			spin_lock(ptl);
+			/*
+			 * paravirt calls inside pte_clear here are
+			 * superfluous.
+			 */
+			pte_clear(vma->vm_mm, address, _pte);
+			page_remove_rmap(src_page);
+			spin_unlock(ptl);
+			free_page_and_swap_cache(src_page);
+		}
+
+		address += PAGE_SIZE;
+		page++;
+	}
+}
+
+static void khugepaged_alloc_sleep(void)
+{
+	DEFINE_WAIT(wait);
+
+	add_wait_queue(&khugepaged_wait, &wait);
+	freezable_schedule_timeout_interruptible(
+		msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
+	remove_wait_queue(&khugepaged_wait, &wait);
+}
+
+static int khugepaged_node_load[MAX_NUMNODES];
+
+static bool khugepaged_scan_abort(int nid)
+{
+	int i;
+
+	/*
+	 * If zone_reclaim_mode is disabled, then no extra effort is made to
+	 * allocate memory locally.
+	 */
+	if (!zone_reclaim_mode)
+		return false;
+
+	/* If there is a count for this node already, it must be acceptable */
+	if (khugepaged_node_load[nid])
+		return false;
+
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		if (!khugepaged_node_load[i])
+			continue;
+		if (node_distance(nid, i) > RECLAIM_DISTANCE)
+			return true;
+	}
+	return false;
+}
+
+#ifdef CONFIG_NUMA
+static int khugepaged_find_target_node(void)
+{
+	static int last_khugepaged_target_node = NUMA_NO_NODE;
+	int nid, target_node = 0, max_value = 0;
+
+	/* find first node with max normal pages hit */
+	for (nid = 0; nid < MAX_NUMNODES; nid++)
+		if (khugepaged_node_load[nid] > max_value) {
+			max_value = khugepaged_node_load[nid];
+			target_node = nid;
+		}
+
+	/* do some balance if several nodes have the same hit record */
+	if (target_node <= last_khugepaged_target_node)
+		for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
+				nid++)
+			if (max_value == khugepaged_node_load[nid]) {
+				target_node = nid;
+				break;
+			}
+
+	last_khugepaged_target_node = target_node;
+	return target_node;
+}
+
+static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+{
+	if (IS_ERR(*hpage)) {
+		if (!*wait)
+			return false;
+
+		*wait = false;
+		*hpage = NULL;
+		khugepaged_alloc_sleep();
+	} else if (*hpage) {
+		put_page(*hpage);
+		*hpage = NULL;
+	}
+
+	return true;
+}
+
+static struct page *
+khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
+		       unsigned long address, int node)
+{
+	VM_BUG_ON_PAGE(*hpage, *hpage);
+
+	/*
+	 * Before allocating the hugepage, release the mmap_sem read lock.
+	 * The allocation can take potentially a long time if it involves
+	 * sync compaction, and we do not need to hold the mmap_sem during
+	 * that. We will recheck the vma after taking it again in write mode.
+	 */
+	up_read(&mm->mmap_sem);
+
+	*hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
+	if (unlikely(!*hpage)) {
+		count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
+		*hpage = ERR_PTR(-ENOMEM);
+		return NULL;
+	}
+
+	count_vm_event(THP_COLLAPSE_ALLOC);
+	return *hpage;
+}
+#else
+static int khugepaged_find_target_node(void)
+{
+	return 0;
+}
+
+static inline struct page *alloc_hugepage(int defrag)
+{
+	return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
+			   HPAGE_PMD_ORDER);
+}
+
+static struct page *khugepaged_alloc_hugepage(bool *wait)
+{
+	struct page *hpage;
+
+	do {
+		hpage = alloc_hugepage(khugepaged_defrag());
+		if (!hpage) {
+			count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
+			if (!*wait)
+				return NULL;
+
+			*wait = false;
+			khugepaged_alloc_sleep();
+		} else
+			count_vm_event(THP_COLLAPSE_ALLOC);
+	} while (unlikely(!hpage) && likely(khugepaged_enabled()));
+
+	return hpage;
+}
+
+static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+{
+	if (!*hpage)
+		*hpage = khugepaged_alloc_hugepage(wait);
+
+	if (unlikely(!*hpage))
+		return false;
+
+	return true;
+}
+
+static struct page *
+khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
+		       unsigned long address, int node)
+{
+	up_read(&mm->mmap_sem);
+	VM_BUG_ON(!*hpage);
+
+	return  *hpage;
+}
+#endif
+
+static bool hugepage_vma_check(struct vm_area_struct *vma)
+{
+	if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
+	    (vma->vm_flags & VM_NOHUGEPAGE))
+		return false;
+
+	if (!vma->anon_vma || vma->vm_ops)
+		return false;
+	if (is_vma_temporary_stack(vma))
+		return false;
+	return !(vma->vm_flags & VM_NO_THP);
+}
+
+static void collapse_huge_page(struct mm_struct *mm,
+				   unsigned long address,
+				   struct page **hpage,
+				   struct vm_area_struct *vma,
+				   int node)
+{
+	pmd_t *pmd, _pmd;
+	pte_t *pte;
+	pgtable_t pgtable;
+	struct page *new_page;
+	spinlock_t *pmd_ptl, *pte_ptl;
+	int isolated;
+	unsigned long hstart, hend;
+	struct mem_cgroup *memcg;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+	gfp_t gfp;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	/* Only allocate from the target node */
+	gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
+		__GFP_THISNODE;
+
+	/* release the mmap_sem read lock. */
+	new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
+	if (!new_page)
+		return;
+
+	if (unlikely(mem_cgroup_try_charge(new_page, mm,
+					   gfp, &memcg)))
+		return;
+
+	/*
+	 * Prevent all access to pagetables with the exception of
+	 * gup_fast later hanlded by the ptep_clear_flush and the VM
+	 * handled by the anon_vma lock + PG_lock.
+	 */
+	down_write(&mm->mmap_sem);
+	if (unlikely(khugepaged_test_exit(mm)))
+		goto out;
+
+	vma = find_vma(mm, address);
+	if (!vma)
+		goto out;
+	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+	hend = vma->vm_end & HPAGE_PMD_MASK;
+	if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+		goto out;
+	if (!hugepage_vma_check(vma))
+		goto out;
+	pmd = mm_find_pmd(mm, address);
+	if (!pmd)
+		goto out;
+
+	anon_vma_lock_write(vma->anon_vma);
+
+	pte = pte_offset_map(pmd, address);
+	pte_ptl = pte_lockptr(mm, pmd);
+
+	mmun_start = address;
+	mmun_end   = address + HPAGE_PMD_SIZE;
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
+	/*
+	 * After this gup_fast can't run anymore. This also removes
+	 * any huge TLB entry from the CPU so we won't allow
+	 * huge and small TLB entries for the same virtual address
+	 * to avoid the risk of CPU bugs in that area.
+	 */
+	_pmd = pmdp_collapse_flush(vma, address, pmd);
+	spin_unlock(pmd_ptl);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+	spin_lock(pte_ptl);
+	isolated = __collapse_huge_page_isolate(vma, address, pte);
+	spin_unlock(pte_ptl);
+
+	if (unlikely(!isolated)) {
+		pte_unmap(pte);
+		spin_lock(pmd_ptl);
+		BUG_ON(!pmd_none(*pmd));
+		/*
+		 * We can only use set_pmd_at when establishing
+		 * hugepmds and never for establishing regular pmds that
+		 * points to regular pagetables. Use pmd_populate for that
+		 */
+		pmd_populate(mm, pmd, pmd_pgtable(_pmd));
+		spin_unlock(pmd_ptl);
+		anon_vma_unlock_write(vma->anon_vma);
+		goto out;
+	}
+
+	/*
+	 * All pages are isolated and locked so anon_vma rmap
+	 * can't run anymore.
+	 */
+	anon_vma_unlock_write(vma->anon_vma);
+
+	__collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
+	pte_unmap(pte);
+	__SetPageUptodate(new_page);
+	pgtable = pmd_pgtable(_pmd);
+
+	_pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
+	_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
+
+	/*
+	 * spin_lock() below is not the equivalent of smp_wmb(), so
+	 * this is needed to avoid the copy_huge_page writes to become
+	 * visible after the set_pmd_at() write.
+	 */
+	smp_wmb();
+
+	spin_lock(pmd_ptl);
+	BUG_ON(!pmd_none(*pmd));
+	page_add_new_anon_rmap(new_page, vma, address);
+	mem_cgroup_commit_charge(new_page, memcg, false);
+	lru_cache_add_active_or_unevictable(new_page, vma);
+	pgtable_trans_huge_deposit(mm, pmd, pgtable);
+	set_pmd_at(mm, address, pmd, _pmd);
+	update_mmu_cache_pmd(vma, address, pmd);
+	spin_unlock(pmd_ptl);
+
+	*hpage = NULL;
+
+	khugepaged_pages_collapsed++;
+out_up_write:
+	up_write(&mm->mmap_sem);
+	return;
+
+out:
+	mem_cgroup_cancel_charge(new_page, memcg);
+	goto out_up_write;
+}
+
+static int khugepaged_scan_pmd(struct mm_struct *mm,
+			       struct vm_area_struct *vma,
+			       unsigned long address,
+			       struct page **hpage)
+{
+	pmd_t *pmd;
+	pte_t *pte, *_pte;
+	int ret = 0, none_or_zero = 0;
+	struct page *page;
+	unsigned long _address;
+	spinlock_t *ptl;
+	int node = NUMA_NO_NODE;
+	bool writable = false, referenced = false;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	pmd = mm_find_pmd(mm, address);
+	if (!pmd)
+		goto out;
+
+	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
+	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+	for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
+	     _pte++, _address += PAGE_SIZE) {
+		pte_t pteval = *_pte;
+		if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+			if (!userfaultfd_armed(vma) &&
+			    ++none_or_zero <= khugepaged_max_ptes_none)
+				continue;
+			else
+				goto out_unmap;
+		}
+		if (!pte_present(pteval))
+			goto out_unmap;
+		if (pte_write(pteval))
+			writable = true;
+
+		page = vm_normal_page(vma, _address, pteval);
+		if (unlikely(!page))
+			goto out_unmap;
+		/*
+		 * Record which node the original page is from and save this
+		 * information to khugepaged_node_load[].
+		 * Khupaged will allocate hugepage from the node has the max
+		 * hit record.
+		 */
+		node = page_to_nid(page);
+		if (khugepaged_scan_abort(node))
+			goto out_unmap;
+		khugepaged_node_load[node]++;
+		VM_BUG_ON_PAGE(PageCompound(page), page);
+		if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
+			goto out_unmap;
+		/*
+		 * cannot use mapcount: can't collapse if there's a gup pin.
+		 * The page must only be referenced by the scanned process
+		 * and page swap cache.
+		 */
+		if (page_count(page) != 1 + !!PageSwapCache(page))
+			goto out_unmap;
+		if (pte_young(pteval) ||
+		    page_is_young(page) || PageReferenced(page) ||
+		    mmu_notifier_test_young(vma->vm_mm, address))
+			referenced = true;
+	}
+	if (referenced && writable)
+		ret = 1;
+out_unmap:
+	pte_unmap_unlock(pte, ptl);
+	if (ret) {
+		node = khugepaged_find_target_node();
+		/* collapse_huge_page will return with the mmap_sem released */
+		collapse_huge_page(mm, address, hpage, vma, node);
+	}
+out:
+	return ret;
+}
+
+static void collect_mm_slot(struct mm_slot *mm_slot)
+{
+	struct mm_struct *mm = mm_slot->mm;
+
+	VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
+
+	if (khugepaged_test_exit(mm)) {
+		/* free mm_slot */
+		hash_del(&mm_slot->hash);
+		list_del(&mm_slot->mm_node);
+
+		/*
+		 * Not strictly needed because the mm exited already.
+		 *
+		 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
+		 */
+
+		/* khugepaged_mm_lock actually not necessary for the below */
+		free_mm_slot(mm_slot);
+		mmdrop(mm);
+	}
+}
+
+static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
+					    struct page **hpage)
+	__releases(&khugepaged_mm_lock)
+	__acquires(&khugepaged_mm_lock)
+{
+	struct mm_slot *mm_slot;
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	int progress = 0;
+
+	VM_BUG_ON(!pages);
+	VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
+
+	if (khugepaged_scan.mm_slot)
+		mm_slot = khugepaged_scan.mm_slot;
+	else {
+		mm_slot = list_entry(khugepaged_scan.mm_head.next,
+				     struct mm_slot, mm_node);
+		khugepaged_scan.address = 0;
+		khugepaged_scan.mm_slot = mm_slot;
+	}
+	spin_unlock(&khugepaged_mm_lock);
+
+	mm = mm_slot->mm;
+	down_read(&mm->mmap_sem);
+	if (unlikely(khugepaged_test_exit(mm)))
+		vma = NULL;
+	else
+		vma = find_vma(mm, khugepaged_scan.address);
+
+	progress++;
+	for (; vma; vma = vma->vm_next) {
+		unsigned long hstart, hend;
+
+		cond_resched();
+		if (unlikely(khugepaged_test_exit(mm))) {
+			progress++;
+			break;
+		}
+		if (!hugepage_vma_check(vma)) {
+skip:
+			progress++;
+			continue;
+		}
+		hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+		hend = vma->vm_end & HPAGE_PMD_MASK;
+		if (hstart >= hend)
+			goto skip;
+		if (khugepaged_scan.address > hend)
+			goto skip;
+		if (khugepaged_scan.address < hstart)
+			khugepaged_scan.address = hstart;
+		VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
+
+		while (khugepaged_scan.address < hend) {
+			int ret;
+			cond_resched();
+			if (unlikely(khugepaged_test_exit(mm)))
+				goto breakouterloop;
+
+			VM_BUG_ON(khugepaged_scan.address < hstart ||
+				  khugepaged_scan.address + HPAGE_PMD_SIZE >
+				  hend);
+			ret = khugepaged_scan_pmd(mm, vma,
+						  khugepaged_scan.address,
+						  hpage);
+			/* move to next address */
+			khugepaged_scan.address += HPAGE_PMD_SIZE;
+			progress += HPAGE_PMD_NR;
+			if (ret)
+				/* we released mmap_sem so break loop */
+				goto breakouterloop_mmap_sem;
+			if (progress >= pages)
+				goto breakouterloop;
+		}
+	}
+breakouterloop:
+	up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
+breakouterloop_mmap_sem:
+
+	spin_lock(&khugepaged_mm_lock);
+	VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
+	/*
+	 * Release the current mm_slot if this mm is about to die, or
+	 * if we scanned all vmas of this mm.
+	 */
+	if (khugepaged_test_exit(mm) || !vma) {
+		/*
+		 * Make sure that if mm_users is reaching zero while
+		 * khugepaged runs here, khugepaged_exit will find
+		 * mm_slot not pointing to the exiting mm.
+		 */
+		if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
+			khugepaged_scan.mm_slot = list_entry(
+				mm_slot->mm_node.next,
+				struct mm_slot, mm_node);
+			khugepaged_scan.address = 0;
+		} else {
+			khugepaged_scan.mm_slot = NULL;
+			khugepaged_full_scans++;
+		}
+
+		collect_mm_slot(mm_slot);
+	}
+
+	return progress;
+}
+
+static int khugepaged_has_work(void)
+{
+	return !list_empty(&khugepaged_scan.mm_head) &&
+		khugepaged_enabled();
+}
+
+static int khugepaged_wait_event(void)
+{
+	return !list_empty(&khugepaged_scan.mm_head) ||
+		kthread_should_stop();
+}
+
+static void khugepaged_do_scan(void)
+{
+	struct page *hpage = NULL;
+	unsigned int progress = 0, pass_through_head = 0;
+	unsigned int pages = khugepaged_pages_to_scan;
+	bool wait = true;
+
+	barrier(); /* write khugepaged_pages_to_scan to local stack */
+
+	while (progress < pages) {
+		if (!khugepaged_prealloc_page(&hpage, &wait))
+			break;
+
+		cond_resched();
+
+		if (unlikely(kthread_should_stop() || try_to_freeze()))
+			break;
+
+		spin_lock(&khugepaged_mm_lock);
+		if (!khugepaged_scan.mm_slot)
+			pass_through_head++;
+		if (khugepaged_has_work() &&
+		    pass_through_head < 2)
+			progress += khugepaged_scan_mm_slot(pages - progress,
+							    &hpage);
+		else
+			progress = pages;
+		spin_unlock(&khugepaged_mm_lock);
+	}
+
+	if (!IS_ERR_OR_NULL(hpage))
+		put_page(hpage);
+}
+
+static void khugepaged_wait_work(void)
+{
+	if (khugepaged_has_work()) {
+		if (!khugepaged_scan_sleep_millisecs)
+			return;
+
+		wait_event_freezable_timeout(khugepaged_wait,
+					     kthread_should_stop(),
+			msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
+		return;
+	}
+
+	if (khugepaged_enabled())
+		wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
+}
+
+static int khugepaged(void *none)
+{
+	struct mm_slot *mm_slot;
+
+	set_freezable();
+	set_user_nice(current, MAX_NICE);
+
+	while (!kthread_should_stop()) {
+		khugepaged_do_scan();
+		khugepaged_wait_work();
+	}
+
+	spin_lock(&khugepaged_mm_lock);
+	mm_slot = khugepaged_scan.mm_slot;
+	khugepaged_scan.mm_slot = NULL;
+	if (mm_slot)
+		collect_mm_slot(mm_slot);
+	spin_unlock(&khugepaged_mm_lock);
+	return 0;
+}
+
+static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
+		unsigned long haddr, pmd_t *pmd)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pgtable_t pgtable;
+	pmd_t _pmd;
+	int i;
+
+	pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+	/* leave pmd empty until pte is filled */
+
+	pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+	pmd_populate(mm, &_pmd, pgtable);
+
+	for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+		pte_t *pte, entry;
+		entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
+		entry = pte_mkspecial(entry);
+		pte = pte_offset_map(&_pmd, haddr);
+		VM_BUG_ON(!pte_none(*pte));
+		set_pte_at(mm, haddr, pte, entry);
+		pte_unmap(pte);
+	}
+	smp_wmb(); /* make pte visible before pmd */
+	pmd_populate(mm, pmd, pgtable);
+	put_huge_zero_page();
+}
+
+void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
+		pmd_t *pmd)
+{
+	spinlock_t *ptl;
+	struct page *page = NULL;
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long haddr = address & HPAGE_PMD_MASK;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+
+	BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
+
+	mmun_start = haddr;
+	mmun_end   = haddr + HPAGE_PMD_SIZE;
+again:
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	ptl = pmd_lock(mm, pmd);
+	if (unlikely(!pmd_trans_huge(*pmd)))
+		goto unlock;
+	if (vma_is_dax(vma)) {
+		pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+		if (is_huge_zero_pmd(_pmd))
+			put_huge_zero_page();
+	} else if (is_huge_zero_pmd(*pmd)) {
+		__split_huge_zero_page_pmd(vma, haddr, pmd);
+	} else {
+		page = pmd_page(*pmd);
+		VM_BUG_ON_PAGE(!page_count(page), page);
+		get_page(page);
+	}
+ unlock:
+	spin_unlock(ptl);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+	if (!page)
+		return;
+
+	split_huge_page(page);
+	put_page(page);
+
+	/*
+	 * We don't always have down_write of mmap_sem here: a racing
+	 * do_huge_pmd_wp_page() might have copied-on-write to another
+	 * huge page before our split_huge_page() got the anon_vma lock.
+	 */
+	if (unlikely(pmd_trans_huge(*pmd)))
+		goto again;
+}
+
+void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
+		pmd_t *pmd)
+{
+	struct vm_area_struct *vma;
+
+	vma = find_vma(mm, address);
+	BUG_ON(vma == NULL);
+	split_huge_page_pmd(vma, address, pmd);
+}
+
+static void split_huge_page_address(struct mm_struct *mm,
+				    unsigned long address)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
+
+	pgd = pgd_offset(mm, address);
+	if (!pgd_present(*pgd))
+		return;
+
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		return;
+
+	pmd = pmd_offset(pud, address);
+	if (!pmd_present(*pmd))
+		return;
+	/*
+	 * Caller holds the mmap_sem write mode, so a huge pmd cannot
+	 * materialize from under us.
+	 */
+	split_huge_page_pmd_mm(mm, address, pmd);
+}
+
+void vma_adjust_trans_huge(struct vm_area_struct *vma,
+			     unsigned long start,
+			     unsigned long end,
+			     long adjust_next)
+{
+	/*
+	 * If the new start address isn't hpage aligned and it could
+	 * previously contain an hugepage: check if we need to split
+	 * an huge pmd.
+	 */
+	if (start & ~HPAGE_PMD_MASK &&
+	    (start & HPAGE_PMD_MASK) >= vma->vm_start &&
+	    (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
+		split_huge_page_address(vma->vm_mm, start);
+
+	/*
+	 * If the new end address isn't hpage aligned and it could
+	 * previously contain an hugepage: check if we need to split
+	 * an huge pmd.
+	 */
+	if (end & ~HPAGE_PMD_MASK &&
+	    (end & HPAGE_PMD_MASK) >= vma->vm_start &&
+	    (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
+		split_huge_page_address(vma->vm_mm, end);
+
+	/*
+	 * If we're also updating the vma->vm_next->vm_start, if the new
+	 * vm_next->vm_start isn't page aligned and it could previously
+	 * contain an hugepage: check if we need to split an huge pmd.
+	 */
+	if (adjust_next > 0) {
+		struct vm_area_struct *next = vma->vm_next;
+		unsigned long nstart = next->vm_start;
+		nstart += adjust_next << PAGE_SHIFT;
+		if (nstart & ~HPAGE_PMD_MASK &&
+		    (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
+		    (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
+			split_huge_page_address(next->vm_mm, nstart);
+	}
+}
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
new file mode 100644
index 0000000..7294301
--- /dev/null
+++ b/mm/hugetlb.c
@@ -0,0 +1,4466 @@
+/*
+ * Generic hugetlb support.
+ * (C) Nadia Yvette Chambers, April 2004
+ */
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/seq_file.h>
+#include <linux/sysctl.h>
+#include <linux/highmem.h>
+#include <linux/mmu_notifier.h>
+#include <linux/nodemask.h>
+#include <linux/pagemap.h>
+#include <linux/mempolicy.h>
+#include <linux/compiler.h>
+#include <linux/cpuset.h>
+#include <linux/mutex.h>
+#include <linux/bootmem.h>
+#include <linux/sysfs.h>
+#include <linux/slab.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/page-isolation.h>
+#include <linux/jhash.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/tlb.h>
+
+#include <linux/io.h>
+#include <linux/hugetlb.h>
+#include <linux/hugetlb_cgroup.h>
+#include <linux/node.h>
+#include "internal.h"
+
+int hugepages_treat_as_movable;
+
+int hugetlb_max_hstate __read_mostly;
+unsigned int default_hstate_idx;
+struct hstate hstates[HUGE_MAX_HSTATE];
+/*
+ * Minimum page order among possible hugepage sizes, set to a proper value
+ * at boot time.
+ */
+static unsigned int minimum_order __read_mostly = UINT_MAX;
+
+__initdata LIST_HEAD(huge_boot_pages);
+
+/* for command line parsing */
+static struct hstate * __initdata parsed_hstate;
+static unsigned long __initdata default_hstate_max_huge_pages;
+static unsigned long __initdata default_hstate_size;
+
+/*
+ * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
+ * free_huge_pages, and surplus_huge_pages.
+ */
+DEFINE_SPINLOCK(hugetlb_lock);
+
+/*
+ * Serializes faults on the same logical page.  This is used to
+ * prevent spurious OOMs when the hugepage pool is fully utilized.
+ */
+static int num_fault_mutexes;
+struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
+
+/* Forward declaration */
+static int hugetlb_acct_memory(struct hstate *h, long delta);
+
+static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
+{
+	bool free = (spool->count == 0) && (spool->used_hpages == 0);
+
+	spin_unlock(&spool->lock);
+
+	/* If no pages are used, and no other handles to the subpool
+	 * remain, give up any reservations mased on minimum size and
+	 * free the subpool */
+	if (free) {
+		if (spool->min_hpages != -1)
+			hugetlb_acct_memory(spool->hstate,
+						-spool->min_hpages);
+		kfree(spool);
+	}
+}
+
+struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
+						long min_hpages)
+{
+	struct hugepage_subpool *spool;
+
+	spool = kzalloc(sizeof(*spool), GFP_KERNEL);
+	if (!spool)
+		return NULL;
+
+	spin_lock_init(&spool->lock);
+	spool->count = 1;
+	spool->max_hpages = max_hpages;
+	spool->hstate = h;
+	spool->min_hpages = min_hpages;
+
+	if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
+		kfree(spool);
+		return NULL;
+	}
+	spool->rsv_hpages = min_hpages;
+
+	return spool;
+}
+
+void hugepage_put_subpool(struct hugepage_subpool *spool)
+{
+	spin_lock(&spool->lock);
+	BUG_ON(!spool->count);
+	spool->count--;
+	unlock_or_release_subpool(spool);
+}
+
+/*
+ * Subpool accounting for allocating and reserving pages.
+ * Return -ENOMEM if there are not enough resources to satisfy the
+ * the request.  Otherwise, return the number of pages by which the
+ * global pools must be adjusted (upward).  The returned value may
+ * only be different than the passed value (delta) in the case where
+ * a subpool minimum size must be manitained.
+ */
+static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
+				      long delta)
+{
+	long ret = delta;
+
+	if (!spool)
+		return ret;
+
+	spin_lock(&spool->lock);
+
+	if (spool->max_hpages != -1) {		/* maximum size accounting */
+		if ((spool->used_hpages + delta) <= spool->max_hpages)
+			spool->used_hpages += delta;
+		else {
+			ret = -ENOMEM;
+			goto unlock_ret;
+		}
+	}
+
+	if (spool->min_hpages != -1) {		/* minimum size accounting */
+		if (delta > spool->rsv_hpages) {
+			/*
+			 * Asking for more reserves than those already taken on
+			 * behalf of subpool.  Return difference.
+			 */
+			ret = delta - spool->rsv_hpages;
+			spool->rsv_hpages = 0;
+		} else {
+			ret = 0;	/* reserves already accounted for */
+			spool->rsv_hpages -= delta;
+		}
+	}
+
+unlock_ret:
+	spin_unlock(&spool->lock);
+	return ret;
+}
+
+/*
+ * Subpool accounting for freeing and unreserving pages.
+ * Return the number of global page reservations that must be dropped.
+ * The return value may only be different than the passed value (delta)
+ * in the case where a subpool minimum size must be maintained.
+ */
+static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
+				       long delta)
+{
+	long ret = delta;
+
+	if (!spool)
+		return delta;
+
+	spin_lock(&spool->lock);
+
+	if (spool->max_hpages != -1)		/* maximum size accounting */
+		spool->used_hpages -= delta;
+
+	if (spool->min_hpages != -1) {		/* minimum size accounting */
+		if (spool->rsv_hpages + delta <= spool->min_hpages)
+			ret = 0;
+		else
+			ret = spool->rsv_hpages + delta - spool->min_hpages;
+
+		spool->rsv_hpages += delta;
+		if (spool->rsv_hpages > spool->min_hpages)
+			spool->rsv_hpages = spool->min_hpages;
+	}
+
+	/*
+	 * If hugetlbfs_put_super couldn't free spool due to an outstanding
+	 * quota reference, free it now.
+	 */
+	unlock_or_release_subpool(spool);
+
+	return ret;
+}
+
+static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
+{
+	return HUGETLBFS_SB(inode->i_sb)->spool;
+}
+
+static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
+{
+	return subpool_inode(file_inode(vma->vm_file));
+}
+
+/*
+ * Region tracking -- allows tracking of reservations and instantiated pages
+ *                    across the pages in a mapping.
+ *
+ * The region data structures are embedded into a resv_map and protected
+ * by a resv_map's lock.  The set of regions within the resv_map represent
+ * reservations for huge pages, or huge pages that have already been
+ * instantiated within the map.  The from and to elements are huge page
+ * indicies into the associated mapping.  from indicates the starting index
+ * of the region.  to represents the first index past the end of  the region.
+ *
+ * For example, a file region structure with from == 0 and to == 4 represents
+ * four huge pages in a mapping.  It is important to note that the to element
+ * represents the first element past the end of the region. This is used in
+ * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
+ *
+ * Interval notation of the form [from, to) will be used to indicate that
+ * the endpoint from is inclusive and to is exclusive.
+ */
+struct file_region {
+	struct list_head link;
+	long from;
+	long to;
+};
+
+/*
+ * Add the huge page range represented by [f, t) to the reserve
+ * map.  In the normal case, existing regions will be expanded
+ * to accommodate the specified range.  Sufficient regions should
+ * exist for expansion due to the previous call to region_chg
+ * with the same range.  However, it is possible that region_del
+ * could have been called after region_chg and modifed the map
+ * in such a way that no region exists to be expanded.  In this
+ * case, pull a region descriptor from the cache associated with
+ * the map and use that for the new range.
+ *
+ * Return the number of new huge pages added to the map.  This
+ * number is greater than or equal to zero.
+ */
+static long region_add(struct resv_map *resv, long f, long t)
+{
+	struct list_head *head = &resv->regions;
+	struct file_region *rg, *nrg, *trg;
+	long add = 0;
+
+	spin_lock(&resv->lock);
+	/* Locate the region we are either in or before. */
+	list_for_each_entry(rg, head, link)
+		if (f <= rg->to)
+			break;
+
+	/*
+	 * If no region exists which can be expanded to include the
+	 * specified range, the list must have been modified by an
+	 * interleving call to region_del().  Pull a region descriptor
+	 * from the cache and use it for this range.
+	 */
+	if (&rg->link == head || t < rg->from) {
+		VM_BUG_ON(resv->region_cache_count <= 0);
+
+		resv->region_cache_count--;
+		nrg = list_first_entry(&resv->region_cache, struct file_region,
+					link);
+		list_del(&nrg->link);
+
+		nrg->from = f;
+		nrg->to = t;
+		list_add(&nrg->link, rg->link.prev);
+
+		add += t - f;
+		goto out_locked;
+	}
+
+	/* Round our left edge to the current segment if it encloses us. */
+	if (f > rg->from)
+		f = rg->from;
+
+	/* Check for and consume any regions we now overlap with. */
+	nrg = rg;
+	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
+		if (&rg->link == head)
+			break;
+		if (rg->from > t)
+			break;
+
+		/* If this area reaches higher then extend our area to
+		 * include it completely.  If this is not the first area
+		 * which we intend to reuse, free it. */
+		if (rg->to > t)
+			t = rg->to;
+		if (rg != nrg) {
+			/* Decrement return value by the deleted range.
+			 * Another range will span this area so that by
+			 * end of routine add will be >= zero
+			 */
+			add -= (rg->to - rg->from);
+			list_del(&rg->link);
+			kfree(rg);
+		}
+	}
+
+	add += (nrg->from - f);		/* Added to beginning of region */
+	nrg->from = f;
+	add += t - nrg->to;		/* Added to end of region */
+	nrg->to = t;
+
+out_locked:
+	resv->adds_in_progress--;
+	spin_unlock(&resv->lock);
+	VM_BUG_ON(add < 0);
+	return add;
+}
+
+/*
+ * Examine the existing reserve map and determine how many
+ * huge pages in the specified range [f, t) are NOT currently
+ * represented.  This routine is called before a subsequent
+ * call to region_add that will actually modify the reserve
+ * map to add the specified range [f, t).  region_chg does
+ * not change the number of huge pages represented by the
+ * map.  However, if the existing regions in the map can not
+ * be expanded to represent the new range, a new file_region
+ * structure is added to the map as a placeholder.  This is
+ * so that the subsequent region_add call will have all the
+ * regions it needs and will not fail.
+ *
+ * Upon entry, region_chg will also examine the cache of region descriptors
+ * associated with the map.  If there are not enough descriptors cached, one
+ * will be allocated for the in progress add operation.
+ *
+ * Returns the number of huge pages that need to be added to the existing
+ * reservation map for the range [f, t).  This number is greater or equal to
+ * zero.  -ENOMEM is returned if a new file_region structure or cache entry
+ * is needed and can not be allocated.
+ */
+static long region_chg(struct resv_map *resv, long f, long t)
+{
+	struct list_head *head = &resv->regions;
+	struct file_region *rg, *nrg = NULL;
+	long chg = 0;
+
+retry:
+	spin_lock(&resv->lock);
+retry_locked:
+	resv->adds_in_progress++;
+
+	/*
+	 * Check for sufficient descriptors in the cache to accommodate
+	 * the number of in progress add operations.
+	 */
+	if (resv->adds_in_progress > resv->region_cache_count) {
+		struct file_region *trg;
+
+		VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
+		/* Must drop lock to allocate a new descriptor. */
+		resv->adds_in_progress--;
+		spin_unlock(&resv->lock);
+
+		trg = kmalloc(sizeof(*trg), GFP_KERNEL);
+		if (!trg) {
+			kfree(nrg);
+			return -ENOMEM;
+		}
+
+		spin_lock(&resv->lock);
+		list_add(&trg->link, &resv->region_cache);
+		resv->region_cache_count++;
+		goto retry_locked;
+	}
+
+	/* Locate the region we are before or in. */
+	list_for_each_entry(rg, head, link)
+		if (f <= rg->to)
+			break;
+
+	/* If we are below the current region then a new region is required.
+	 * Subtle, allocate a new region at the position but make it zero
+	 * size such that we can guarantee to record the reservation. */
+	if (&rg->link == head || t < rg->from) {
+		if (!nrg) {
+			resv->adds_in_progress--;
+			spin_unlock(&resv->lock);
+			nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
+			if (!nrg)
+				return -ENOMEM;
+
+			nrg->from = f;
+			nrg->to   = f;
+			INIT_LIST_HEAD(&nrg->link);
+			goto retry;
+		}
+
+		list_add(&nrg->link, rg->link.prev);
+		chg = t - f;
+		goto out_nrg;
+	}
+
+	/* Round our left edge to the current segment if it encloses us. */
+	if (f > rg->from)
+		f = rg->from;
+	chg = t - f;
+
+	/* Check for and consume any regions we now overlap with. */
+	list_for_each_entry(rg, rg->link.prev, link) {
+		if (&rg->link == head)
+			break;
+		if (rg->from > t)
+			goto out;
+
+		/* We overlap with this area, if it extends further than
+		 * us then we must extend ourselves.  Account for its
+		 * existing reservation. */
+		if (rg->to > t) {
+			chg += rg->to - t;
+			t = rg->to;
+		}
+		chg -= rg->to - rg->from;
+	}
+
+out:
+	spin_unlock(&resv->lock);
+	/*  We already know we raced and no longer need the new region */
+	kfree(nrg);
+	return chg;
+out_nrg:
+	spin_unlock(&resv->lock);
+	return chg;
+}
+
+/*
+ * Abort the in progress add operation.  The adds_in_progress field
+ * of the resv_map keeps track of the operations in progress between
+ * calls to region_chg and region_add.  Operations are sometimes
+ * aborted after the call to region_chg.  In such cases, region_abort
+ * is called to decrement the adds_in_progress counter.
+ *
+ * NOTE: The range arguments [f, t) are not needed or used in this
+ * routine.  They are kept to make reading the calling code easier as
+ * arguments will match the associated region_chg call.
+ */
+static void region_abort(struct resv_map *resv, long f, long t)
+{
+	spin_lock(&resv->lock);
+	VM_BUG_ON(!resv->region_cache_count);
+	resv->adds_in_progress--;
+	spin_unlock(&resv->lock);
+}
+
+/*
+ * Delete the specified range [f, t) from the reserve map.  If the
+ * t parameter is LONG_MAX, this indicates that ALL regions after f
+ * should be deleted.  Locate the regions which intersect [f, t)
+ * and either trim, delete or split the existing regions.
+ *
+ * Returns the number of huge pages deleted from the reserve map.
+ * In the normal case, the return value is zero or more.  In the
+ * case where a region must be split, a new region descriptor must
+ * be allocated.  If the allocation fails, -ENOMEM will be returned.
+ * NOTE: If the parameter t == LONG_MAX, then we will never split
+ * a region and possibly return -ENOMEM.  Callers specifying
+ * t == LONG_MAX do not need to check for -ENOMEM error.
+ */
+static long region_del(struct resv_map *resv, long f, long t)
+{
+	struct list_head *head = &resv->regions;
+	struct file_region *rg, *trg;
+	struct file_region *nrg = NULL;
+	long del = 0;
+
+retry:
+	spin_lock(&resv->lock);
+	list_for_each_entry_safe(rg, trg, head, link) {
+		/*
+		 * Skip regions before the range to be deleted.  file_region
+		 * ranges are normally of the form [from, to).  However, there
+		 * may be a "placeholder" entry in the map which is of the form
+		 * (from, to) with from == to.  Check for placeholder entries
+		 * at the beginning of the range to be deleted.
+		 */
+		if (rg->to <= f && (rg->to != rg->from || rg->to != f))
+			continue;
+
+		if (rg->from >= t)
+			break;
+
+		if (f > rg->from && t < rg->to) { /* Must split region */
+			/*
+			 * Check for an entry in the cache before dropping
+			 * lock and attempting allocation.
+			 */
+			if (!nrg &&
+			    resv->region_cache_count > resv->adds_in_progress) {
+				nrg = list_first_entry(&resv->region_cache,
+							struct file_region,
+							link);
+				list_del(&nrg->link);
+				resv->region_cache_count--;
+			}
+
+			if (!nrg) {
+				spin_unlock(&resv->lock);
+				nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
+				if (!nrg)
+					return -ENOMEM;
+				goto retry;
+			}
+
+			del += t - f;
+
+			/* New entry for end of split region */
+			nrg->from = t;
+			nrg->to = rg->to;
+			INIT_LIST_HEAD(&nrg->link);
+
+			/* Original entry is trimmed */
+			rg->to = f;
+
+			list_add(&nrg->link, &rg->link);
+			nrg = NULL;
+			break;
+		}
+
+		if (f <= rg->from && t >= rg->to) { /* Remove entire region */
+			del += rg->to - rg->from;
+			list_del(&rg->link);
+			kfree(rg);
+			continue;
+		}
+
+		if (f <= rg->from) {	/* Trim beginning of region */
+			del += t - rg->from;
+			rg->from = t;
+		} else {		/* Trim end of region */
+			del += rg->to - f;
+			rg->to = f;
+		}
+	}
+
+	spin_unlock(&resv->lock);
+	kfree(nrg);
+	return del;
+}
+
+/*
+ * A rare out of memory error was encountered which prevented removal of
+ * the reserve map region for a page.  The huge page itself was free'ed
+ * and removed from the page cache.  This routine will adjust the subpool
+ * usage count, and the global reserve count if needed.  By incrementing
+ * these counts, the reserve map entry which could not be deleted will
+ * appear as a "reserved" entry instead of simply dangling with incorrect
+ * counts.
+ */
+void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve)
+{
+	struct hugepage_subpool *spool = subpool_inode(inode);
+	long rsv_adjust;
+
+	rsv_adjust = hugepage_subpool_get_pages(spool, 1);
+	if (restore_reserve && rsv_adjust) {
+		struct hstate *h = hstate_inode(inode);
+
+		hugetlb_acct_memory(h, 1);
+	}
+}
+
+/*
+ * Count and return the number of huge pages in the reserve map
+ * that intersect with the range [f, t).
+ */
+static long region_count(struct resv_map *resv, long f, long t)
+{
+	struct list_head *head = &resv->regions;
+	struct file_region *rg;
+	long chg = 0;
+
+	spin_lock(&resv->lock);
+	/* Locate each segment we overlap with, and count that overlap. */
+	list_for_each_entry(rg, head, link) {
+		long seg_from;
+		long seg_to;
+
+		if (rg->to <= f)
+			continue;
+		if (rg->from >= t)
+			break;
+
+		seg_from = max(rg->from, f);
+		seg_to = min(rg->to, t);
+
+		chg += seg_to - seg_from;
+	}
+	spin_unlock(&resv->lock);
+
+	return chg;
+}
+
+/*
+ * Convert the address within this vma to the page offset within
+ * the mapping, in pagecache page units; huge pages here.
+ */
+static pgoff_t vma_hugecache_offset(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	return ((address - vma->vm_start) >> huge_page_shift(h)) +
+			(vma->vm_pgoff >> huge_page_order(h));
+}
+
+pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
+				     unsigned long address)
+{
+	return vma_hugecache_offset(hstate_vma(vma), vma, address);
+}
+
+/*
+ * Return the size of the pages allocated when backing a VMA. In the majority
+ * cases this will be same size as used by the page table entries.
+ */
+unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
+{
+	struct hstate *hstate;
+
+	if (!is_vm_hugetlb_page(vma))
+		return PAGE_SIZE;
+
+	hstate = hstate_vma(vma);
+
+	return 1UL << huge_page_shift(hstate);
+}
+EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
+
+/*
+ * Return the page size being used by the MMU to back a VMA. In the majority
+ * of cases, the page size used by the kernel matches the MMU size. On
+ * architectures where it differs, an architecture-specific version of this
+ * function is required.
+ */
+#ifndef vma_mmu_pagesize
+unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
+{
+	return vma_kernel_pagesize(vma);
+}
+#endif
+
+/*
+ * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
+ * bits of the reservation map pointer, which are always clear due to
+ * alignment.
+ */
+#define HPAGE_RESV_OWNER    (1UL << 0)
+#define HPAGE_RESV_UNMAPPED (1UL << 1)
+#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
+
+/*
+ * These helpers are used to track how many pages are reserved for
+ * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
+ * is guaranteed to have their future faults succeed.
+ *
+ * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
+ * the reserve counters are updated with the hugetlb_lock held. It is safe
+ * to reset the VMA at fork() time as it is not in use yet and there is no
+ * chance of the global counters getting corrupted as a result of the values.
+ *
+ * The private mapping reservation is represented in a subtly different
+ * manner to a shared mapping.  A shared mapping has a region map associated
+ * with the underlying file, this region map represents the backing file
+ * pages which have ever had a reservation assigned which this persists even
+ * after the page is instantiated.  A private mapping has a region map
+ * associated with the original mmap which is attached to all VMAs which
+ * reference it, this region map represents those offsets which have consumed
+ * reservation ie. where pages have been instantiated.
+ */
+static unsigned long get_vma_private_data(struct vm_area_struct *vma)
+{
+	return (unsigned long)vma->vm_private_data;
+}
+
+static void set_vma_private_data(struct vm_area_struct *vma,
+							unsigned long value)
+{
+	vma->vm_private_data = (void *)value;
+}
+
+struct resv_map *resv_map_alloc(void)
+{
+	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
+	struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
+
+	if (!resv_map || !rg) {
+		kfree(resv_map);
+		kfree(rg);
+		return NULL;
+	}
+
+	kref_init(&resv_map->refs);
+	spin_lock_init(&resv_map->lock);
+	INIT_LIST_HEAD(&resv_map->regions);
+
+	resv_map->adds_in_progress = 0;
+
+	INIT_LIST_HEAD(&resv_map->region_cache);
+	list_add(&rg->link, &resv_map->region_cache);
+	resv_map->region_cache_count = 1;
+
+	return resv_map;
+}
+
+void resv_map_release(struct kref *ref)
+{
+	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
+	struct list_head *head = &resv_map->region_cache;
+	struct file_region *rg, *trg;
+
+	/* Clear out any active regions before we release the map. */
+	region_del(resv_map, 0, LONG_MAX);
+
+	/* ... and any entries left in the cache */
+	list_for_each_entry_safe(rg, trg, head, link) {
+		list_del(&rg->link);
+		kfree(rg);
+	}
+
+	VM_BUG_ON(resv_map->adds_in_progress);
+
+	kfree(resv_map);
+}
+
+static inline struct resv_map *inode_resv_map(struct inode *inode)
+{
+	return inode->i_mapping->private_data;
+}
+
+static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
+{
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+	if (vma->vm_flags & VM_MAYSHARE) {
+		struct address_space *mapping = vma->vm_file->f_mapping;
+		struct inode *inode = mapping->host;
+
+		return inode_resv_map(inode);
+
+	} else {
+		return (struct resv_map *)(get_vma_private_data(vma) &
+							~HPAGE_RESV_MASK);
+	}
+}
+
+static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
+{
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
+
+	set_vma_private_data(vma, (get_vma_private_data(vma) &
+				HPAGE_RESV_MASK) | (unsigned long)map);
+}
+
+static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
+{
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
+
+	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
+}
+
+static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
+{
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+
+	return (get_vma_private_data(vma) & flag) != 0;
+}
+
+/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
+void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
+{
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+	if (!(vma->vm_flags & VM_MAYSHARE))
+		vma->vm_private_data = (void *)0;
+}
+
+/* Returns true if the VMA has associated reserve pages */
+static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
+{
+	if (vma->vm_flags & VM_NORESERVE) {
+		/*
+		 * This address is already reserved by other process(chg == 0),
+		 * so, we should decrement reserved count. Without decrementing,
+		 * reserve count remains after releasing inode, because this
+		 * allocated page will go into page cache and is regarded as
+		 * coming from reserved pool in releasing step.  Currently, we
+		 * don't have any other solution to deal with this situation
+		 * properly, so add work-around here.
+		 */
+		if (vma->vm_flags & VM_MAYSHARE && chg == 0)
+			return true;
+		else
+			return false;
+	}
+
+	/* Shared mappings always use reserves */
+	if (vma->vm_flags & VM_MAYSHARE) {
+		/*
+		 * We know VM_NORESERVE is not set.  Therefore, there SHOULD
+		 * be a region map for all pages.  The only situation where
+		 * there is no region map is if a hole was punched via
+		 * fallocate.  In this case, there really are no reverves to
+		 * use.  This situation is indicated if chg != 0.
+		 */
+		if (chg)
+			return false;
+		else
+			return true;
+	}
+
+	/*
+	 * Only the process that called mmap() has reserves for
+	 * private mappings.
+	 */
+	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
+		return true;
+
+	return false;
+}
+
+static void enqueue_huge_page(struct hstate *h, struct page *page)
+{
+	int nid = page_to_nid(page);
+	list_move(&page->lru, &h->hugepage_freelists[nid]);
+	h->free_huge_pages++;
+	h->free_huge_pages_node[nid]++;
+}
+
+static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
+{
+	struct page *page;
+
+	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
+		if (!is_migrate_isolate_page(page))
+			break;
+	/*
+	 * if 'non-isolated free hugepage' not found on the list,
+	 * the allocation fails.
+	 */
+	if (&h->hugepage_freelists[nid] == &page->lru)
+		return NULL;
+	list_move(&page->lru, &h->hugepage_activelist);
+	set_page_refcounted(page);
+	h->free_huge_pages--;
+	h->free_huge_pages_node[nid]--;
+	return page;
+}
+
+/* Movability of hugepages depends on migration support. */
+static inline gfp_t htlb_alloc_mask(struct hstate *h)
+{
+	if (hugepages_treat_as_movable || hugepage_migration_supported(h))
+		return GFP_HIGHUSER_MOVABLE;
+	else
+		return GFP_HIGHUSER;
+}
+
+static struct page *dequeue_huge_page_vma(struct hstate *h,
+				struct vm_area_struct *vma,
+				unsigned long address, int avoid_reserve,
+				long chg)
+{
+	struct page *page = NULL;
+	struct mempolicy *mpol;
+	nodemask_t *nodemask;
+	struct zonelist *zonelist;
+	struct zone *zone;
+	struct zoneref *z;
+	unsigned int cpuset_mems_cookie;
+
+	/*
+	 * A child process with MAP_PRIVATE mappings created by their parent
+	 * have no page reserves. This check ensures that reservations are
+	 * not "stolen". The child may still get SIGKILLed
+	 */
+	if (!vma_has_reserves(vma, chg) &&
+			h->free_huge_pages - h->resv_huge_pages == 0)
+		goto err;
+
+	/* If reserves cannot be used, ensure enough pages are in the pool */
+	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
+		goto err;
+
+retry_cpuset:
+	cpuset_mems_cookie = read_mems_allowed_begin();
+	zonelist = huge_zonelist(vma, address,
+					htlb_alloc_mask(h), &mpol, &nodemask);
+
+	for_each_zone_zonelist_nodemask(zone, z, zonelist,
+						MAX_NR_ZONES - 1, nodemask) {
+		if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
+			page = dequeue_huge_page_node(h, zone_to_nid(zone));
+			if (page) {
+				if (avoid_reserve)
+					break;
+				if (!vma_has_reserves(vma, chg))
+					break;
+
+				SetPagePrivate(page);
+				h->resv_huge_pages--;
+				break;
+			}
+		}
+	}
+
+	mpol_cond_put(mpol);
+	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
+		goto retry_cpuset;
+	return page;
+
+err:
+	return NULL;
+}
+
+/*
+ * common helper functions for hstate_next_node_to_{alloc|free}.
+ * We may have allocated or freed a huge page based on a different
+ * nodes_allowed previously, so h->next_node_to_{alloc|free} might
+ * be outside of *nodes_allowed.  Ensure that we use an allowed
+ * node for alloc or free.
+ */
+static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
+{
+	nid = next_node(nid, *nodes_allowed);
+	if (nid == MAX_NUMNODES)
+		nid = first_node(*nodes_allowed);
+	VM_BUG_ON(nid >= MAX_NUMNODES);
+
+	return nid;
+}
+
+static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
+{
+	if (!node_isset(nid, *nodes_allowed))
+		nid = next_node_allowed(nid, nodes_allowed);
+	return nid;
+}
+
+/*
+ * returns the previously saved node ["this node"] from which to
+ * allocate a persistent huge page for the pool and advance the
+ * next node from which to allocate, handling wrap at end of node
+ * mask.
+ */
+static int hstate_next_node_to_alloc(struct hstate *h,
+					nodemask_t *nodes_allowed)
+{
+	int nid;
+
+	VM_BUG_ON(!nodes_allowed);
+
+	nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
+	h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
+
+	return nid;
+}
+
+/*
+ * helper for free_pool_huge_page() - return the previously saved
+ * node ["this node"] from which to free a huge page.  Advance the
+ * next node id whether or not we find a free huge page to free so
+ * that the next attempt to free addresses the next node.
+ */
+static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
+{
+	int nid;
+
+	VM_BUG_ON(!nodes_allowed);
+
+	nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
+	h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
+
+	return nid;
+}
+
+#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask)		\
+	for (nr_nodes = nodes_weight(*mask);				\
+		nr_nodes > 0 &&						\
+		((node = hstate_next_node_to_alloc(hs, mask)) || 1);	\
+		nr_nodes--)
+
+#define for_each_node_mask_to_free(hs, nr_nodes, node, mask)		\
+	for (nr_nodes = nodes_weight(*mask);				\
+		nr_nodes > 0 &&						\
+		((node = hstate_next_node_to_free(hs, mask)) || 1);	\
+		nr_nodes--)
+
+#if defined(CONFIG_CMA) && defined(CONFIG_X86_64)
+static void destroy_compound_gigantic_page(struct page *page,
+					unsigned int order)
+{
+	int i;
+	int nr_pages = 1 << order;
+	struct page *p = page + 1;
+
+	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
+		clear_compound_head(p);
+		set_page_refcounted(p);
+	}
+
+	set_compound_order(page, 0);
+	__ClearPageHead(page);
+}
+
+static void free_gigantic_page(struct page *page, unsigned int order)
+{
+	free_contig_range(page_to_pfn(page), 1 << order);
+}
+
+static int __alloc_gigantic_page(unsigned long start_pfn,
+				unsigned long nr_pages)
+{
+	unsigned long end_pfn = start_pfn + nr_pages;
+	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+}
+
+static bool pfn_range_valid_gigantic(unsigned long start_pfn,
+				unsigned long nr_pages)
+{
+	unsigned long i, end_pfn = start_pfn + nr_pages;
+	struct page *page;
+
+	for (i = start_pfn; i < end_pfn; i++) {
+		if (!pfn_valid(i))
+			return false;
+
+		page = pfn_to_page(i);
+
+		if (PageReserved(page))
+			return false;
+
+		if (page_count(page) > 0)
+			return false;
+
+		if (PageHuge(page))
+			return false;
+	}
+
+	return true;
+}
+
+static bool zone_spans_last_pfn(const struct zone *zone,
+			unsigned long start_pfn, unsigned long nr_pages)
+{
+	unsigned long last_pfn = start_pfn + nr_pages - 1;
+	return zone_spans_pfn(zone, last_pfn);
+}
+
+static struct page *alloc_gigantic_page(int nid, unsigned int order)
+{
+	unsigned long nr_pages = 1 << order;
+	unsigned long ret, pfn, flags;
+	struct zone *z;
+
+	z = NODE_DATA(nid)->node_zones;
+	for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
+		spin_lock_irqsave(&z->lock, flags);
+
+		pfn = ALIGN(z->zone_start_pfn, nr_pages);
+		while (zone_spans_last_pfn(z, pfn, nr_pages)) {
+			if (pfn_range_valid_gigantic(pfn, nr_pages)) {
+				/*
+				 * We release the zone lock here because
+				 * alloc_contig_range() will also lock the zone
+				 * at some point. If there's an allocation
+				 * spinning on this lock, it may win the race
+				 * and cause alloc_contig_range() to fail...
+				 */
+				spin_unlock_irqrestore(&z->lock, flags);
+				ret = __alloc_gigantic_page(pfn, nr_pages);
+				if (!ret)
+					return pfn_to_page(pfn);
+				spin_lock_irqsave(&z->lock, flags);
+			}
+			pfn += nr_pages;
+		}
+
+		spin_unlock_irqrestore(&z->lock, flags);
+	}
+
+	return NULL;
+}
+
+static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
+static void prep_compound_gigantic_page(struct page *page, unsigned int order);
+
+static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
+{
+	struct page *page;
+
+	page = alloc_gigantic_page(nid, huge_page_order(h));
+	if (page) {
+		prep_compound_gigantic_page(page, huge_page_order(h));
+		prep_new_huge_page(h, page, nid);
+	}
+
+	return page;
+}
+
+static int alloc_fresh_gigantic_page(struct hstate *h,
+				nodemask_t *nodes_allowed)
+{
+	struct page *page = NULL;
+	int nr_nodes, node;
+
+	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
+		page = alloc_fresh_gigantic_page_node(h, node);
+		if (page)
+			return 1;
+	}
+
+	return 0;
+}
+
+static inline bool gigantic_page_supported(void) { return true; }
+#else
+static inline bool gigantic_page_supported(void) { return false; }
+static inline void free_gigantic_page(struct page *page, unsigned int order) { }
+static inline void destroy_compound_gigantic_page(struct page *page,
+						unsigned int order) { }
+static inline int alloc_fresh_gigantic_page(struct hstate *h,
+					nodemask_t *nodes_allowed) { return 0; }
+#endif
+
+static void update_and_free_page(struct hstate *h, struct page *page)
+{
+	int i;
+
+	if (hstate_is_gigantic(h) && !gigantic_page_supported())
+		return;
+
+	h->nr_huge_pages--;
+	h->nr_huge_pages_node[page_to_nid(page)]--;
+	for (i = 0; i < pages_per_huge_page(h); i++) {
+		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
+				1 << PG_referenced | 1 << PG_dirty |
+				1 << PG_active | 1 << PG_private |
+				1 << PG_writeback);
+	}
+	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
+	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
+	set_page_refcounted(page);
+	if (hstate_is_gigantic(h)) {
+		destroy_compound_gigantic_page(page, huge_page_order(h));
+		free_gigantic_page(page, huge_page_order(h));
+	} else {
+		__free_pages(page, huge_page_order(h));
+	}
+}
+
+struct hstate *size_to_hstate(unsigned long size)
+{
+	struct hstate *h;
+
+	for_each_hstate(h) {
+		if (huge_page_size(h) == size)
+			return h;
+	}
+	return NULL;
+}
+
+/*
+ * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
+ * to hstate->hugepage_activelist.)
+ *
+ * This function can be called for tail pages, but never returns true for them.
+ */
+bool page_huge_active(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageHuge(page), page);
+	return PageHead(page) && PagePrivate(&page[1]);
+}
+
+/* never called for tail page */
+static void set_page_huge_active(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
+	SetPagePrivate(&page[1]);
+}
+
+static void clear_page_huge_active(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
+	ClearPagePrivate(&page[1]);
+}
+
+void free_huge_page(struct page *page)
+{
+	/*
+	 * Can't pass hstate in here because it is called from the
+	 * compound page destructor.
+	 */
+	struct hstate *h = page_hstate(page);
+	int nid = page_to_nid(page);
+	struct hugepage_subpool *spool =
+		(struct hugepage_subpool *)page_private(page);
+	bool restore_reserve;
+
+	set_page_private(page, 0);
+	page->mapping = NULL;
+	BUG_ON(page_count(page));
+	BUG_ON(page_mapcount(page));
+	restore_reserve = PagePrivate(page);
+	ClearPagePrivate(page);
+
+	/*
+	 * A return code of zero implies that the subpool will be under its
+	 * minimum size if the reservation is not restored after page is free.
+	 * Therefore, force restore_reserve operation.
+	 */
+	if (hugepage_subpool_put_pages(spool, 1) == 0)
+		restore_reserve = true;
+
+	spin_lock(&hugetlb_lock);
+	clear_page_huge_active(page);
+	hugetlb_cgroup_uncharge_page(hstate_index(h),
+				     pages_per_huge_page(h), page);
+	if (restore_reserve)
+		h->resv_huge_pages++;
+
+	if (h->surplus_huge_pages_node[nid]) {
+		/* remove the page from active list */
+		list_del(&page->lru);
+		update_and_free_page(h, page);
+		h->surplus_huge_pages--;
+		h->surplus_huge_pages_node[nid]--;
+	} else {
+		arch_clear_hugepage_flags(page);
+		enqueue_huge_page(h, page);
+	}
+	spin_unlock(&hugetlb_lock);
+}
+
+static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
+{
+	INIT_LIST_HEAD(&page->lru);
+	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
+	spin_lock(&hugetlb_lock);
+	set_hugetlb_cgroup(page, NULL);
+	h->nr_huge_pages++;
+	h->nr_huge_pages_node[nid]++;
+	spin_unlock(&hugetlb_lock);
+	put_page(page); /* free it into the hugepage allocator */
+}
+
+static void prep_compound_gigantic_page(struct page *page, unsigned int order)
+{
+	int i;
+	int nr_pages = 1 << order;
+	struct page *p = page + 1;
+
+	/* we rely on prep_new_huge_page to set the destructor */
+	set_compound_order(page, order);
+	__SetPageHead(page);
+	__ClearPageReserved(page);
+	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
+		/*
+		 * For gigantic hugepages allocated through bootmem at
+		 * boot, it's safer to be consistent with the not-gigantic
+		 * hugepages and clear the PG_reserved bit from all tail pages
+		 * too.  Otherwse drivers using get_user_pages() to access tail
+		 * pages may get the reference counting wrong if they see
+		 * PG_reserved set on a tail page (despite the head page not
+		 * having PG_reserved set).  Enforcing this consistency between
+		 * head and tail pages allows drivers to optimize away a check
+		 * on the head page when they need know if put_page() is needed
+		 * after get_user_pages().
+		 */
+		__ClearPageReserved(p);
+		set_page_count(p, 0);
+		set_compound_head(p, page);
+	}
+}
+
+/*
+ * PageHuge() only returns true for hugetlbfs pages, but not for normal or
+ * transparent huge pages.  See the PageTransHuge() documentation for more
+ * details.
+ */
+int PageHuge(struct page *page)
+{
+	if (!PageCompound(page))
+		return 0;
+
+	page = compound_head(page);
+	return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
+}
+EXPORT_SYMBOL_GPL(PageHuge);
+
+/*
+ * PageHeadHuge() only returns true for hugetlbfs head page, but not for
+ * normal or transparent huge pages.
+ */
+int PageHeadHuge(struct page *page_head)
+{
+	if (!PageHead(page_head))
+		return 0;
+
+	return get_compound_page_dtor(page_head) == free_huge_page;
+}
+
+pgoff_t __basepage_index(struct page *page)
+{
+	struct page *page_head = compound_head(page);
+	pgoff_t index = page_index(page_head);
+	unsigned long compound_idx;
+
+	if (!PageHuge(page_head))
+		return page_index(page);
+
+	if (compound_order(page_head) >= MAX_ORDER)
+		compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
+	else
+		compound_idx = page - page_head;
+
+	return (index << compound_order(page_head)) + compound_idx;
+}
+
+static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
+{
+	struct page *page;
+
+	page = __alloc_pages_node(nid,
+		htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
+						__GFP_REPEAT|__GFP_NOWARN,
+		huge_page_order(h));
+	if (page) {
+		prep_new_huge_page(h, page, nid);
+	}
+
+	return page;
+}
+
+static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
+{
+	struct page *page;
+	int nr_nodes, node;
+	int ret = 0;
+
+	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
+		page = alloc_fresh_huge_page_node(h, node);
+		if (page) {
+			ret = 1;
+			break;
+		}
+	}
+
+	if (ret)
+		count_vm_event(HTLB_BUDDY_PGALLOC);
+	else
+		count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+
+	return ret;
+}
+
+/*
+ * Free huge page from pool from next node to free.
+ * Attempt to keep persistent huge pages more or less
+ * balanced over allowed nodes.
+ * Called with hugetlb_lock locked.
+ */
+static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
+							 bool acct_surplus)
+{
+	int nr_nodes, node;
+	int ret = 0;
+
+	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
+		/*
+		 * If we're returning unused surplus pages, only examine
+		 * nodes with surplus pages.
+		 */
+		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
+		    !list_empty(&h->hugepage_freelists[node])) {
+			struct page *page =
+				list_entry(h->hugepage_freelists[node].next,
+					  struct page, lru);
+			list_del(&page->lru);
+			h->free_huge_pages--;
+			h->free_huge_pages_node[node]--;
+			if (acct_surplus) {
+				h->surplus_huge_pages--;
+				h->surplus_huge_pages_node[node]--;
+			}
+			update_and_free_page(h, page);
+			ret = 1;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Dissolve a given free hugepage into free buddy pages. This function does
+ * nothing for in-use (including surplus) hugepages.
+ */
+static void dissolve_free_huge_page(struct page *page)
+{
+	spin_lock(&hugetlb_lock);
+	if (PageHuge(page) && !page_count(page)) {
+		struct page *head = compound_head(page);
+		struct hstate *h = page_hstate(head);
+		int nid = page_to_nid(head);
+		list_del(&head->lru);
+		h->free_huge_pages--;
+		h->free_huge_pages_node[nid]--;
+		update_and_free_page(h, head);
+	}
+	spin_unlock(&hugetlb_lock);
+}
+
+/*
+ * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
+ * make specified memory blocks removable from the system.
+ * Note that this will dissolve a free gigantic hugepage completely, if any
+ * part of it lies within the given range.
+ */
+void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn;
+
+	if (!hugepages_supported())
+		return;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
+		dissolve_free_huge_page(pfn_to_page(pfn));
+}
+
+/*
+ * There are 3 ways this can get called:
+ * 1. With vma+addr: we use the VMA's memory policy
+ * 2. With !vma, but nid=NUMA_NO_NODE:  We try to allocate a huge
+ *    page from any node, and let the buddy allocator itself figure
+ *    it out.
+ * 3. With !vma, but nid!=NUMA_NO_NODE.  We allocate a huge page
+ *    strictly from 'nid'
+ */
+static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
+		struct vm_area_struct *vma, unsigned long addr, int nid)
+{
+	int order = huge_page_order(h);
+	gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
+	unsigned int cpuset_mems_cookie;
+
+	/*
+	 * We need a VMA to get a memory policy.  If we do not
+	 * have one, we use the 'nid' argument.
+	 *
+	 * The mempolicy stuff below has some non-inlined bits
+	 * and calls ->vm_ops.  That makes it hard to optimize at
+	 * compile-time, even when NUMA is off and it does
+	 * nothing.  This helps the compiler optimize it out.
+	 */
+	if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
+		/*
+		 * If a specific node is requested, make sure to
+		 * get memory from there, but only when a node
+		 * is explicitly specified.
+		 */
+		if (nid != NUMA_NO_NODE)
+			gfp |= __GFP_THISNODE;
+		/*
+		 * Make sure to call something that can handle
+		 * nid=NUMA_NO_NODE
+		 */
+		return alloc_pages_node(nid, gfp, order);
+	}
+
+	/*
+	 * OK, so we have a VMA.  Fetch the mempolicy and try to
+	 * allocate a huge page with it.  We will only reach this
+	 * when CONFIG_NUMA=y.
+	 */
+	do {
+		struct page *page;
+		struct mempolicy *mpol;
+		struct zonelist *zl;
+		nodemask_t *nodemask;
+
+		cpuset_mems_cookie = read_mems_allowed_begin();
+		zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
+		mpol_cond_put(mpol);
+		page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
+		if (page)
+			return page;
+	} while (read_mems_allowed_retry(cpuset_mems_cookie));
+
+	return NULL;
+}
+
+/*
+ * There are two ways to allocate a huge page:
+ * 1. When you have a VMA and an address (like a fault)
+ * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
+ *
+ * 'vma' and 'addr' are only for (1).  'nid' is always NUMA_NO_NODE in
+ * this case which signifies that the allocation should be done with
+ * respect for the VMA's memory policy.
+ *
+ * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
+ * implies that memory policies will not be taken in to account.
+ */
+static struct page *__alloc_buddy_huge_page(struct hstate *h,
+		struct vm_area_struct *vma, unsigned long addr, int nid)
+{
+	struct page *page;
+	unsigned int r_nid;
+
+	if (hstate_is_gigantic(h))
+		return NULL;
+
+	/*
+	 * Make sure that anyone specifying 'nid' is not also specifying a VMA.
+	 * This makes sure the caller is picking _one_ of the modes with which
+	 * we can call this function, not both.
+	 */
+	if (vma || (addr != -1)) {
+		VM_WARN_ON_ONCE(addr == -1);
+		VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
+	}
+	/*
+	 * Assume we will successfully allocate the surplus page to
+	 * prevent racing processes from causing the surplus to exceed
+	 * overcommit
+	 *
+	 * This however introduces a different race, where a process B
+	 * tries to grow the static hugepage pool while alloc_pages() is
+	 * called by process A. B will only examine the per-node
+	 * counters in determining if surplus huge pages can be
+	 * converted to normal huge pages in adjust_pool_surplus(). A
+	 * won't be able to increment the per-node counter, until the
+	 * lock is dropped by B, but B doesn't drop hugetlb_lock until
+	 * no more huge pages can be converted from surplus to normal
+	 * state (and doesn't try to convert again). Thus, we have a
+	 * case where a surplus huge page exists, the pool is grown, and
+	 * the surplus huge page still exists after, even though it
+	 * should just have been converted to a normal huge page. This
+	 * does not leak memory, though, as the hugepage will be freed
+	 * once it is out of use. It also does not allow the counters to
+	 * go out of whack in adjust_pool_surplus() as we don't modify
+	 * the node values until we've gotten the hugepage and only the
+	 * per-node value is checked there.
+	 */
+	spin_lock(&hugetlb_lock);
+	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
+		spin_unlock(&hugetlb_lock);
+		return NULL;
+	} else {
+		h->nr_huge_pages++;
+		h->surplus_huge_pages++;
+	}
+	spin_unlock(&hugetlb_lock);
+
+	page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
+
+	spin_lock(&hugetlb_lock);
+	if (page) {
+		INIT_LIST_HEAD(&page->lru);
+		r_nid = page_to_nid(page);
+		set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
+		set_hugetlb_cgroup(page, NULL);
+		/*
+		 * We incremented the global counters already
+		 */
+		h->nr_huge_pages_node[r_nid]++;
+		h->surplus_huge_pages_node[r_nid]++;
+		__count_vm_event(HTLB_BUDDY_PGALLOC);
+	} else {
+		h->nr_huge_pages--;
+		h->surplus_huge_pages--;
+		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+	}
+	spin_unlock(&hugetlb_lock);
+
+	return page;
+}
+
+/*
+ * Allocate a huge page from 'nid'.  Note, 'nid' may be
+ * NUMA_NO_NODE, which means that it may be allocated
+ * anywhere.
+ */
+static
+struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
+{
+	unsigned long addr = -1;
+
+	return __alloc_buddy_huge_page(h, NULL, addr, nid);
+}
+
+/*
+ * Use the VMA's mpolicy to allocate a huge page from the buddy.
+ */
+static
+struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
+		struct vm_area_struct *vma, unsigned long addr)
+{
+	return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
+}
+
+/*
+ * This allocation function is useful in the context where vma is irrelevant.
+ * E.g. soft-offlining uses this function because it only cares physical
+ * address of error page.
+ */
+struct page *alloc_huge_page_node(struct hstate *h, int nid)
+{
+	struct page *page = NULL;
+
+	spin_lock(&hugetlb_lock);
+	if (h->free_huge_pages - h->resv_huge_pages > 0)
+		page = dequeue_huge_page_node(h, nid);
+	spin_unlock(&hugetlb_lock);
+
+	if (!page)
+		page = __alloc_buddy_huge_page_no_mpol(h, nid);
+
+	return page;
+}
+
+/*
+ * Increase the hugetlb pool such that it can accommodate a reservation
+ * of size 'delta'.
+ */
+static int gather_surplus_pages(struct hstate *h, int delta)
+{
+	struct list_head surplus_list;
+	struct page *page, *tmp;
+	int ret, i;
+	int needed, allocated;
+	bool alloc_ok = true;
+
+	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
+	if (needed <= 0) {
+		h->resv_huge_pages += delta;
+		return 0;
+	}
+
+	allocated = 0;
+	INIT_LIST_HEAD(&surplus_list);
+
+	ret = -ENOMEM;
+retry:
+	spin_unlock(&hugetlb_lock);
+	for (i = 0; i < needed; i++) {
+		page = __alloc_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
+		if (!page) {
+			alloc_ok = false;
+			break;
+		}
+		list_add(&page->lru, &surplus_list);
+	}
+	allocated += i;
+
+	/*
+	 * After retaking hugetlb_lock, we need to recalculate 'needed'
+	 * because either resv_huge_pages or free_huge_pages may have changed.
+	 */
+	spin_lock(&hugetlb_lock);
+	needed = (h->resv_huge_pages + delta) -
+			(h->free_huge_pages + allocated);
+	if (needed > 0) {
+		if (alloc_ok)
+			goto retry;
+		/*
+		 * We were not able to allocate enough pages to
+		 * satisfy the entire reservation so we free what
+		 * we've allocated so far.
+		 */
+		goto free;
+	}
+	/*
+	 * The surplus_list now contains _at_least_ the number of extra pages
+	 * needed to accommodate the reservation.  Add the appropriate number
+	 * of pages to the hugetlb pool and free the extras back to the buddy
+	 * allocator.  Commit the entire reservation here to prevent another
+	 * process from stealing the pages as they are added to the pool but
+	 * before they are reserved.
+	 */
+	needed += allocated;
+	h->resv_huge_pages += delta;
+	ret = 0;
+
+	/* Free the needed pages to the hugetlb pool */
+	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
+		if ((--needed) < 0)
+			break;
+		/*
+		 * This page is now managed by the hugetlb allocator and has
+		 * no users -- drop the buddy allocator's reference.
+		 */
+		put_page_testzero(page);
+		VM_BUG_ON_PAGE(page_count(page), page);
+		enqueue_huge_page(h, page);
+	}
+free:
+	spin_unlock(&hugetlb_lock);
+
+	/* Free unnecessary surplus pages to the buddy allocator */
+	list_for_each_entry_safe(page, tmp, &surplus_list, lru)
+		put_page(page);
+	spin_lock(&hugetlb_lock);
+
+	return ret;
+}
+
+/*
+ * This routine has two main purposes:
+ * 1) Decrement the reservation count (resv_huge_pages) by the value passed
+ *    in unused_resv_pages.  This corresponds to the prior adjustments made
+ *    to the associated reservation map.
+ * 2) Free any unused surplus pages that may have been allocated to satisfy
+ *    the reservation.  As many as unused_resv_pages may be freed.
+ *
+ * Called with hugetlb_lock held.  However, the lock could be dropped (and
+ * reacquired) during calls to cond_resched_lock.  Whenever dropping the lock,
+ * we must make sure nobody else can claim pages we are in the process of
+ * freeing.  Do this by ensuring resv_huge_page always is greater than the
+ * number of huge pages we plan to free when dropping the lock.
+ */
+static void return_unused_surplus_pages(struct hstate *h,
+					unsigned long unused_resv_pages)
+{
+	unsigned long nr_pages;
+
+	/* Cannot return gigantic pages currently */
+	if (hstate_is_gigantic(h))
+		goto out;
+
+	/*
+	 * Part (or even all) of the reservation could have been backed
+	 * by pre-allocated pages. Only free surplus pages.
+	 */
+	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
+
+	/*
+	 * We want to release as many surplus pages as possible, spread
+	 * evenly across all nodes with memory. Iterate across these nodes
+	 * until we can no longer free unreserved surplus pages. This occurs
+	 * when the nodes with surplus pages have no free pages.
+	 * free_pool_huge_page() will balance the the freed pages across the
+	 * on-line nodes with memory and will handle the hstate accounting.
+	 *
+	 * Note that we decrement resv_huge_pages as we free the pages.  If
+	 * we drop the lock, resv_huge_pages will still be sufficiently large
+	 * to cover subsequent pages we may free.
+	 */
+	while (nr_pages--) {
+		h->resv_huge_pages--;
+		unused_resv_pages--;
+		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
+			goto out;
+		cond_resched_lock(&hugetlb_lock);
+	}
+
+out:
+	/* Fully uncommit the reservation */
+	h->resv_huge_pages -= unused_resv_pages;
+}
+
+
+/*
+ * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
+ * are used by the huge page allocation routines to manage reservations.
+ *
+ * vma_needs_reservation is called to determine if the huge page at addr
+ * within the vma has an associated reservation.  If a reservation is
+ * needed, the value 1 is returned.  The caller is then responsible for
+ * managing the global reservation and subpool usage counts.  After
+ * the huge page has been allocated, vma_commit_reservation is called
+ * to add the page to the reservation map.  If the page allocation fails,
+ * the reservation must be ended instead of committed.  vma_end_reservation
+ * is called in such cases.
+ *
+ * In the normal case, vma_commit_reservation returns the same value
+ * as the preceding vma_needs_reservation call.  The only time this
+ * is not the case is if a reserve map was changed between calls.  It
+ * is the responsibility of the caller to notice the difference and
+ * take appropriate action.
+ */
+enum vma_resv_mode {
+	VMA_NEEDS_RESV,
+	VMA_COMMIT_RESV,
+	VMA_END_RESV,
+};
+static long __vma_reservation_common(struct hstate *h,
+				struct vm_area_struct *vma, unsigned long addr,
+				enum vma_resv_mode mode)
+{
+	struct resv_map *resv;
+	pgoff_t idx;
+	long ret;
+
+	resv = vma_resv_map(vma);
+	if (!resv)
+		return 1;
+
+	idx = vma_hugecache_offset(h, vma, addr);
+	switch (mode) {
+	case VMA_NEEDS_RESV:
+		ret = region_chg(resv, idx, idx + 1);
+		break;
+	case VMA_COMMIT_RESV:
+		ret = region_add(resv, idx, idx + 1);
+		break;
+	case VMA_END_RESV:
+		region_abort(resv, idx, idx + 1);
+		ret = 0;
+		break;
+	default:
+		BUG();
+	}
+
+	if (vma->vm_flags & VM_MAYSHARE)
+		return ret;
+	else
+		return ret < 0 ? ret : 0;
+}
+
+static long vma_needs_reservation(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
+}
+
+static long vma_commit_reservation(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
+}
+
+static void vma_end_reservation(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
+}
+
+struct page *alloc_huge_page(struct vm_area_struct *vma,
+				    unsigned long addr, int avoid_reserve)
+{
+	struct hugepage_subpool *spool = subpool_vma(vma);
+	struct hstate *h = hstate_vma(vma);
+	struct page *page;
+	long map_chg, map_commit;
+	long gbl_chg;
+	int ret, idx;
+	struct hugetlb_cgroup *h_cg;
+
+	idx = hstate_index(h);
+	/*
+	 * Examine the region/reserve map to determine if the process
+	 * has a reservation for the page to be allocated.  A return
+	 * code of zero indicates a reservation exists (no change).
+	 */
+	map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
+	if (map_chg < 0)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * Processes that did not create the mapping will have no
+	 * reserves as indicated by the region/reserve map. Check
+	 * that the allocation will not exceed the subpool limit.
+	 * Allocations for MAP_NORESERVE mappings also need to be
+	 * checked against any subpool limit.
+	 */
+	if (map_chg || avoid_reserve) {
+		gbl_chg = hugepage_subpool_get_pages(spool, 1);
+		if (gbl_chg < 0) {
+			vma_end_reservation(h, vma, addr);
+			return ERR_PTR(-ENOSPC);
+		}
+
+		/*
+		 * Even though there was no reservation in the region/reserve
+		 * map, there could be reservations associated with the
+		 * subpool that can be used.  This would be indicated if the
+		 * return value of hugepage_subpool_get_pages() is zero.
+		 * However, if avoid_reserve is specified we still avoid even
+		 * the subpool reservations.
+		 */
+		if (avoid_reserve)
+			gbl_chg = 1;
+	}
+
+	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
+	if (ret)
+		goto out_subpool_put;
+
+	spin_lock(&hugetlb_lock);
+	/*
+	 * glb_chg is passed to indicate whether or not a page must be taken
+	 * from the global free pool (global change).  gbl_chg == 0 indicates
+	 * a reservation exists for the allocation.
+	 */
+	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
+	if (!page) {
+		spin_unlock(&hugetlb_lock);
+		page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
+		if (!page)
+			goto out_uncharge_cgroup;
+		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
+			SetPagePrivate(page);
+			h->resv_huge_pages--;
+		}
+		spin_lock(&hugetlb_lock);
+		list_move(&page->lru, &h->hugepage_activelist);
+		/* Fall through */
+	}
+	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
+	spin_unlock(&hugetlb_lock);
+
+	set_page_private(page, (unsigned long)spool);
+
+	map_commit = vma_commit_reservation(h, vma, addr);
+	if (unlikely(map_chg > map_commit)) {
+		/*
+		 * The page was added to the reservation map between
+		 * vma_needs_reservation and vma_commit_reservation.
+		 * This indicates a race with hugetlb_reserve_pages.
+		 * Adjust for the subpool count incremented above AND
+		 * in hugetlb_reserve_pages for the same page.  Also,
+		 * the reservation count added in hugetlb_reserve_pages
+		 * no longer applies.
+		 */
+		long rsv_adjust;
+
+		rsv_adjust = hugepage_subpool_put_pages(spool, 1);
+		hugetlb_acct_memory(h, -rsv_adjust);
+	}
+	return page;
+
+out_uncharge_cgroup:
+	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
+out_subpool_put:
+	if (map_chg || avoid_reserve)
+		hugepage_subpool_put_pages(spool, 1);
+	vma_end_reservation(h, vma, addr);
+	return ERR_PTR(-ENOSPC);
+}
+
+/*
+ * alloc_huge_page()'s wrapper which simply returns the page if allocation
+ * succeeds, otherwise NULL. This function is called from new_vma_page(),
+ * where no ERR_VALUE is expected to be returned.
+ */
+struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
+				unsigned long addr, int avoid_reserve)
+{
+	struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
+	if (IS_ERR(page))
+		page = NULL;
+	return page;
+}
+
+int __weak alloc_bootmem_huge_page(struct hstate *h)
+{
+	struct huge_bootmem_page *m;
+	int nr_nodes, node;
+
+	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
+		void *addr;
+
+		addr = memblock_virt_alloc_try_nid_nopanic(
+				huge_page_size(h), huge_page_size(h),
+				0, BOOTMEM_ALLOC_ACCESSIBLE, node);
+		if (addr) {
+			/*
+			 * Use the beginning of the huge page to store the
+			 * huge_bootmem_page struct (until gather_bootmem
+			 * puts them into the mem_map).
+			 */
+			m = addr;
+			goto found;
+		}
+	}
+	return 0;
+
+found:
+	BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
+	/* Put them into a private list first because mem_map is not up yet */
+	list_add(&m->list, &huge_boot_pages);
+	m->hstate = h;
+	return 1;
+}
+
+static void __init prep_compound_huge_page(struct page *page,
+		unsigned int order)
+{
+	if (unlikely(order > (MAX_ORDER - 1)))
+		prep_compound_gigantic_page(page, order);
+	else
+		prep_compound_page(page, order);
+}
+
+/* Put bootmem huge pages into the standard lists after mem_map is up */
+static void __init gather_bootmem_prealloc(void)
+{
+	struct huge_bootmem_page *m;
+
+	list_for_each_entry(m, &huge_boot_pages, list) {
+		struct hstate *h = m->hstate;
+		struct page *page;
+
+#ifdef CONFIG_HIGHMEM
+		page = pfn_to_page(m->phys >> PAGE_SHIFT);
+		memblock_free_late(__pa(m),
+				   sizeof(struct huge_bootmem_page));
+#else
+		page = virt_to_page(m);
+#endif
+		WARN_ON(page_count(page) != 1);
+		prep_compound_huge_page(page, h->order);
+		WARN_ON(PageReserved(page));
+		prep_new_huge_page(h, page, page_to_nid(page));
+		/*
+		 * If we had gigantic hugepages allocated at boot time, we need
+		 * to restore the 'stolen' pages to totalram_pages in order to
+		 * fix confusing memory reports from free(1) and another
+		 * side-effects, like CommitLimit going negative.
+		 */
+		if (hstate_is_gigantic(h))
+			adjust_managed_page_count(page, 1 << h->order);
+	}
+}
+
+static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
+{
+	unsigned long i;
+
+	for (i = 0; i < h->max_huge_pages; ++i) {
+		if (hstate_is_gigantic(h)) {
+			if (!alloc_bootmem_huge_page(h))
+				break;
+		} else if (!alloc_fresh_huge_page(h,
+					 &node_states[N_MEMORY]))
+			break;
+	}
+	h->max_huge_pages = i;
+}
+
+static void __init hugetlb_init_hstates(void)
+{
+	struct hstate *h;
+
+	for_each_hstate(h) {
+		if (minimum_order > huge_page_order(h))
+			minimum_order = huge_page_order(h);
+
+		/* oversize hugepages were init'ed in early boot */
+		if (!hstate_is_gigantic(h))
+			hugetlb_hstate_alloc_pages(h);
+	}
+	VM_BUG_ON(minimum_order == UINT_MAX);
+}
+
+static char * __init memfmt(char *buf, unsigned long n)
+{
+	if (n >= (1UL << 30))
+		sprintf(buf, "%lu GB", n >> 30);
+	else if (n >= (1UL << 20))
+		sprintf(buf, "%lu MB", n >> 20);
+	else
+		sprintf(buf, "%lu KB", n >> 10);
+	return buf;
+}
+
+static void __init report_hugepages(void)
+{
+	struct hstate *h;
+
+	for_each_hstate(h) {
+		char buf[32];
+		pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
+			memfmt(buf, huge_page_size(h)),
+			h->free_huge_pages);
+	}
+}
+
+#ifdef CONFIG_HIGHMEM
+static void try_to_free_low(struct hstate *h, unsigned long count,
+						nodemask_t *nodes_allowed)
+{
+	int i;
+
+	if (hstate_is_gigantic(h))
+		return;
+
+	for_each_node_mask(i, *nodes_allowed) {
+		struct page *page, *next;
+		struct list_head *freel = &h->hugepage_freelists[i];
+		list_for_each_entry_safe(page, next, freel, lru) {
+			if (count >= h->nr_huge_pages)
+				return;
+			if (PageHighMem(page))
+				continue;
+			list_del(&page->lru);
+			update_and_free_page(h, page);
+			h->free_huge_pages--;
+			h->free_huge_pages_node[page_to_nid(page)]--;
+		}
+	}
+}
+#else
+static inline void try_to_free_low(struct hstate *h, unsigned long count,
+						nodemask_t *nodes_allowed)
+{
+}
+#endif
+
+/*
+ * Increment or decrement surplus_huge_pages.  Keep node-specific counters
+ * balanced by operating on them in a round-robin fashion.
+ * Returns 1 if an adjustment was made.
+ */
+static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
+				int delta)
+{
+	int nr_nodes, node;
+
+	VM_BUG_ON(delta != -1 && delta != 1);
+
+	if (delta < 0) {
+		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
+			if (h->surplus_huge_pages_node[node])
+				goto found;
+		}
+	} else {
+		for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
+			if (h->surplus_huge_pages_node[node] <
+					h->nr_huge_pages_node[node])
+				goto found;
+		}
+	}
+	return 0;
+
+found:
+	h->surplus_huge_pages += delta;
+	h->surplus_huge_pages_node[node] += delta;
+	return 1;
+}
+
+#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
+static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
+						nodemask_t *nodes_allowed)
+{
+	unsigned long min_count, ret;
+
+	if (hstate_is_gigantic(h) && !gigantic_page_supported())
+		return h->max_huge_pages;
+
+	/*
+	 * Increase the pool size
+	 * First take pages out of surplus state.  Then make up the
+	 * remaining difference by allocating fresh huge pages.
+	 *
+	 * We might race with __alloc_buddy_huge_page() here and be unable
+	 * to convert a surplus huge page to a normal huge page. That is
+	 * not critical, though, it just means the overall size of the
+	 * pool might be one hugepage larger than it needs to be, but
+	 * within all the constraints specified by the sysctls.
+	 */
+	spin_lock(&hugetlb_lock);
+	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
+		if (!adjust_pool_surplus(h, nodes_allowed, -1))
+			break;
+	}
+
+	while (count > persistent_huge_pages(h)) {
+		/*
+		 * If this allocation races such that we no longer need the
+		 * page, free_huge_page will handle it by freeing the page
+		 * and reducing the surplus.
+		 */
+		spin_unlock(&hugetlb_lock);
+
+		/* yield cpu to avoid soft lockup */
+		cond_resched();
+
+		if (hstate_is_gigantic(h))
+			ret = alloc_fresh_gigantic_page(h, nodes_allowed);
+		else
+			ret = alloc_fresh_huge_page(h, nodes_allowed);
+		spin_lock(&hugetlb_lock);
+		if (!ret)
+			goto out;
+
+		/* Bail for signals. Probably ctrl-c from user */
+		if (signal_pending(current))
+			goto out;
+	}
+
+	/*
+	 * Decrease the pool size
+	 * First return free pages to the buddy allocator (being careful
+	 * to keep enough around to satisfy reservations).  Then place
+	 * pages into surplus state as needed so the pool will shrink
+	 * to the desired size as pages become free.
+	 *
+	 * By placing pages into the surplus state independent of the
+	 * overcommit value, we are allowing the surplus pool size to
+	 * exceed overcommit. There are few sane options here. Since
+	 * __alloc_buddy_huge_page() is checking the global counter,
+	 * though, we'll note that we're not allowed to exceed surplus
+	 * and won't grow the pool anywhere else. Not until one of the
+	 * sysctls are changed, or the surplus pages go out of use.
+	 */
+	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
+	min_count = max(count, min_count);
+	try_to_free_low(h, min_count, nodes_allowed);
+	while (min_count < persistent_huge_pages(h)) {
+		if (!free_pool_huge_page(h, nodes_allowed, 0))
+			break;
+		cond_resched_lock(&hugetlb_lock);
+	}
+	while (count < persistent_huge_pages(h)) {
+		if (!adjust_pool_surplus(h, nodes_allowed, 1))
+			break;
+	}
+out:
+	ret = persistent_huge_pages(h);
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+
+#define HSTATE_ATTR_RO(_name) \
+	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+#define HSTATE_ATTR(_name) \
+	static struct kobj_attribute _name##_attr = \
+		__ATTR(_name, 0644, _name##_show, _name##_store)
+
+static struct kobject *hugepages_kobj;
+static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
+
+static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
+
+static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
+{
+	int i;
+
+	for (i = 0; i < HUGE_MAX_HSTATE; i++)
+		if (hstate_kobjs[i] == kobj) {
+			if (nidp)
+				*nidp = NUMA_NO_NODE;
+			return &hstates[i];
+		}
+
+	return kobj_to_node_hstate(kobj, nidp);
+}
+
+static ssize_t nr_hugepages_show_common(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h;
+	unsigned long nr_huge_pages;
+	int nid;
+
+	h = kobj_to_hstate(kobj, &nid);
+	if (nid == NUMA_NO_NODE)
+		nr_huge_pages = h->nr_huge_pages;
+	else
+		nr_huge_pages = h->nr_huge_pages_node[nid];
+
+	return sprintf(buf, "%lu\n", nr_huge_pages);
+}
+
+static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
+					   struct hstate *h, int nid,
+					   unsigned long count, size_t len)
+{
+	int err;
+	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
+
+	if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (nid == NUMA_NO_NODE) {
+		/*
+		 * global hstate attribute
+		 */
+		if (!(obey_mempolicy &&
+				init_nodemask_of_mempolicy(nodes_allowed))) {
+			NODEMASK_FREE(nodes_allowed);
+			nodes_allowed = &node_states[N_MEMORY];
+		}
+	} else if (nodes_allowed) {
+		/*
+		 * per node hstate attribute: adjust count to global,
+		 * but restrict alloc/free to the specified node.
+		 */
+		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
+		init_nodemask_of_node(nodes_allowed, nid);
+	} else
+		nodes_allowed = &node_states[N_MEMORY];
+
+	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
+
+	if (nodes_allowed != &node_states[N_MEMORY])
+		NODEMASK_FREE(nodes_allowed);
+
+	return len;
+out:
+	NODEMASK_FREE(nodes_allowed);
+	return err;
+}
+
+static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
+					 struct kobject *kobj, const char *buf,
+					 size_t len)
+{
+	struct hstate *h;
+	unsigned long count;
+	int nid;
+	int err;
+
+	err = kstrtoul(buf, 10, &count);
+	if (err)
+		return err;
+
+	h = kobj_to_hstate(kobj, &nid);
+	return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
+}
+
+static ssize_t nr_hugepages_show(struct kobject *kobj,
+				       struct kobj_attribute *attr, char *buf)
+{
+	return nr_hugepages_show_common(kobj, attr, buf);
+}
+
+static ssize_t nr_hugepages_store(struct kobject *kobj,
+	       struct kobj_attribute *attr, const char *buf, size_t len)
+{
+	return nr_hugepages_store_common(false, kobj, buf, len);
+}
+HSTATE_ATTR(nr_hugepages);
+
+#ifdef CONFIG_NUMA
+
+/*
+ * hstate attribute for optionally mempolicy-based constraint on persistent
+ * huge page alloc/free.
+ */
+static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
+				       struct kobj_attribute *attr, char *buf)
+{
+	return nr_hugepages_show_common(kobj, attr, buf);
+}
+
+static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
+	       struct kobj_attribute *attr, const char *buf, size_t len)
+{
+	return nr_hugepages_store_common(true, kobj, buf, len);
+}
+HSTATE_ATTR(nr_hugepages_mempolicy);
+#endif
+
+
+static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h = kobj_to_hstate(kobj, NULL);
+	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
+}
+
+static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int err;
+	unsigned long input;
+	struct hstate *h = kobj_to_hstate(kobj, NULL);
+
+	if (hstate_is_gigantic(h))
+		return -EINVAL;
+
+	err = kstrtoul(buf, 10, &input);
+	if (err)
+		return err;
+
+	spin_lock(&hugetlb_lock);
+	h->nr_overcommit_huge_pages = input;
+	spin_unlock(&hugetlb_lock);
+
+	return count;
+}
+HSTATE_ATTR(nr_overcommit_hugepages);
+
+static ssize_t free_hugepages_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h;
+	unsigned long free_huge_pages;
+	int nid;
+
+	h = kobj_to_hstate(kobj, &nid);
+	if (nid == NUMA_NO_NODE)
+		free_huge_pages = h->free_huge_pages;
+	else
+		free_huge_pages = h->free_huge_pages_node[nid];
+
+	return sprintf(buf, "%lu\n", free_huge_pages);
+}
+HSTATE_ATTR_RO(free_hugepages);
+
+static ssize_t resv_hugepages_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h = kobj_to_hstate(kobj, NULL);
+	return sprintf(buf, "%lu\n", h->resv_huge_pages);
+}
+HSTATE_ATTR_RO(resv_hugepages);
+
+static ssize_t surplus_hugepages_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h;
+	unsigned long surplus_huge_pages;
+	int nid;
+
+	h = kobj_to_hstate(kobj, &nid);
+	if (nid == NUMA_NO_NODE)
+		surplus_huge_pages = h->surplus_huge_pages;
+	else
+		surplus_huge_pages = h->surplus_huge_pages_node[nid];
+
+	return sprintf(buf, "%lu\n", surplus_huge_pages);
+}
+HSTATE_ATTR_RO(surplus_hugepages);
+
+static struct attribute *hstate_attrs[] = {
+	&nr_hugepages_attr.attr,
+	&nr_overcommit_hugepages_attr.attr,
+	&free_hugepages_attr.attr,
+	&resv_hugepages_attr.attr,
+	&surplus_hugepages_attr.attr,
+#ifdef CONFIG_NUMA
+	&nr_hugepages_mempolicy_attr.attr,
+#endif
+	NULL,
+};
+
+static struct attribute_group hstate_attr_group = {
+	.attrs = hstate_attrs,
+};
+
+static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
+				    struct kobject **hstate_kobjs,
+				    struct attribute_group *hstate_attr_group)
+{
+	int retval;
+	int hi = hstate_index(h);
+
+	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
+	if (!hstate_kobjs[hi])
+		return -ENOMEM;
+
+	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
+	if (retval)
+		kobject_put(hstate_kobjs[hi]);
+
+	return retval;
+}
+
+static void __init hugetlb_sysfs_init(void)
+{
+	struct hstate *h;
+	int err;
+
+	hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
+	if (!hugepages_kobj)
+		return;
+
+	for_each_hstate(h) {
+		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
+					 hstate_kobjs, &hstate_attr_group);
+		if (err)
+			pr_err("Hugetlb: Unable to add hstate %s", h->name);
+	}
+}
+
+#ifdef CONFIG_NUMA
+
+/*
+ * node_hstate/s - associate per node hstate attributes, via their kobjects,
+ * with node devices in node_devices[] using a parallel array.  The array
+ * index of a node device or _hstate == node id.
+ * This is here to avoid any static dependency of the node device driver, in
+ * the base kernel, on the hugetlb module.
+ */
+struct node_hstate {
+	struct kobject		*hugepages_kobj;
+	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
+};
+static struct node_hstate node_hstates[MAX_NUMNODES];
+
+/*
+ * A subset of global hstate attributes for node devices
+ */
+static struct attribute *per_node_hstate_attrs[] = {
+	&nr_hugepages_attr.attr,
+	&free_hugepages_attr.attr,
+	&surplus_hugepages_attr.attr,
+	NULL,
+};
+
+static struct attribute_group per_node_hstate_attr_group = {
+	.attrs = per_node_hstate_attrs,
+};
+
+/*
+ * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
+ * Returns node id via non-NULL nidp.
+ */
+static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
+{
+	int nid;
+
+	for (nid = 0; nid < nr_node_ids; nid++) {
+		struct node_hstate *nhs = &node_hstates[nid];
+		int i;
+		for (i = 0; i < HUGE_MAX_HSTATE; i++)
+			if (nhs->hstate_kobjs[i] == kobj) {
+				if (nidp)
+					*nidp = nid;
+				return &hstates[i];
+			}
+	}
+
+	BUG();
+	return NULL;
+}
+
+/*
+ * Unregister hstate attributes from a single node device.
+ * No-op if no hstate attributes attached.
+ */
+static void hugetlb_unregister_node(struct node *node)
+{
+	struct hstate *h;
+	struct node_hstate *nhs = &node_hstates[node->dev.id];
+
+	if (!nhs->hugepages_kobj)
+		return;		/* no hstate attributes */
+
+	for_each_hstate(h) {
+		int idx = hstate_index(h);
+		if (nhs->hstate_kobjs[idx]) {
+			kobject_put(nhs->hstate_kobjs[idx]);
+			nhs->hstate_kobjs[idx] = NULL;
+		}
+	}
+
+	kobject_put(nhs->hugepages_kobj);
+	nhs->hugepages_kobj = NULL;
+}
+
+/*
+ * hugetlb module exit:  unregister hstate attributes from node devices
+ * that have them.
+ */
+static void hugetlb_unregister_all_nodes(void)
+{
+	int nid;
+
+	/*
+	 * disable node device registrations.
+	 */
+	register_hugetlbfs_with_node(NULL, NULL);
+
+	/*
+	 * remove hstate attributes from any nodes that have them.
+	 */
+	for (nid = 0; nid < nr_node_ids; nid++)
+		hugetlb_unregister_node(node_devices[nid]);
+}
+
+/*
+ * Register hstate attributes for a single node device.
+ * No-op if attributes already registered.
+ */
+static void hugetlb_register_node(struct node *node)
+{
+	struct hstate *h;
+	struct node_hstate *nhs = &node_hstates[node->dev.id];
+	int err;
+
+	if (nhs->hugepages_kobj)
+		return;		/* already allocated */
+
+	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
+							&node->dev.kobj);
+	if (!nhs->hugepages_kobj)
+		return;
+
+	for_each_hstate(h) {
+		err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
+						nhs->hstate_kobjs,
+						&per_node_hstate_attr_group);
+		if (err) {
+			pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
+				h->name, node->dev.id);
+			hugetlb_unregister_node(node);
+			break;
+		}
+	}
+}
+
+/*
+ * hugetlb init time:  register hstate attributes for all registered node
+ * devices of nodes that have memory.  All on-line nodes should have
+ * registered their associated device by this time.
+ */
+static void __init hugetlb_register_all_nodes(void)
+{
+	int nid;
+
+	for_each_node_state(nid, N_MEMORY) {
+		struct node *node = node_devices[nid];
+		if (node->dev.id == nid)
+			hugetlb_register_node(node);
+	}
+
+	/*
+	 * Let the node device driver know we're here so it can
+	 * [un]register hstate attributes on node hotplug.
+	 */
+	register_hugetlbfs_with_node(hugetlb_register_node,
+				     hugetlb_unregister_node);
+}
+#else	/* !CONFIG_NUMA */
+
+static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
+{
+	BUG();
+	if (nidp)
+		*nidp = -1;
+	return NULL;
+}
+
+static void hugetlb_unregister_all_nodes(void) { }
+
+static void hugetlb_register_all_nodes(void) { }
+
+#endif
+
+static void __exit hugetlb_exit(void)
+{
+	struct hstate *h;
+
+	hugetlb_unregister_all_nodes();
+
+	for_each_hstate(h) {
+		kobject_put(hstate_kobjs[hstate_index(h)]);
+	}
+
+	kobject_put(hugepages_kobj);
+	kfree(hugetlb_fault_mutex_table);
+}
+module_exit(hugetlb_exit);
+
+static int __init hugetlb_init(void)
+{
+	int i;
+
+	if (!hugepages_supported())
+		return 0;
+
+	if (!size_to_hstate(default_hstate_size)) {
+		default_hstate_size = HPAGE_SIZE;
+		if (!size_to_hstate(default_hstate_size))
+			hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
+	}
+	default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
+	if (default_hstate_max_huge_pages)
+		default_hstate.max_huge_pages = default_hstate_max_huge_pages;
+
+	hugetlb_init_hstates();
+	gather_bootmem_prealloc();
+	report_hugepages();
+
+	hugetlb_sysfs_init();
+	hugetlb_register_all_nodes();
+	hugetlb_cgroup_file_init();
+
+#ifdef CONFIG_SMP
+	num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
+#else
+	num_fault_mutexes = 1;
+#endif
+	hugetlb_fault_mutex_table =
+		kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
+	BUG_ON(!hugetlb_fault_mutex_table);
+
+	for (i = 0; i < num_fault_mutexes; i++)
+		mutex_init(&hugetlb_fault_mutex_table[i]);
+	return 0;
+}
+module_init(hugetlb_init);
+
+/* Should be called on processing a hugepagesz=... option */
+void __init hugetlb_add_hstate(unsigned int order)
+{
+	struct hstate *h;
+	unsigned long i;
+
+	if (size_to_hstate(PAGE_SIZE << order)) {
+		pr_warning("hugepagesz= specified twice, ignoring\n");
+		return;
+	}
+	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
+	BUG_ON(order == 0);
+	h = &hstates[hugetlb_max_hstate++];
+	h->order = order;
+	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
+	h->nr_huge_pages = 0;
+	h->free_huge_pages = 0;
+	for (i = 0; i < MAX_NUMNODES; ++i)
+		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
+	INIT_LIST_HEAD(&h->hugepage_activelist);
+	h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
+	h->next_nid_to_free = first_node(node_states[N_MEMORY]);
+	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
+					huge_page_size(h)/1024);
+
+	parsed_hstate = h;
+}
+
+static int __init hugetlb_nrpages_setup(char *s)
+{
+	unsigned long *mhp;
+	static unsigned long *last_mhp;
+
+	/*
+	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
+	 * so this hugepages= parameter goes to the "default hstate".
+	 */
+	if (!hugetlb_max_hstate)
+		mhp = &default_hstate_max_huge_pages;
+	else
+		mhp = &parsed_hstate->max_huge_pages;
+
+	if (mhp == last_mhp) {
+		pr_warning("hugepages= specified twice without "
+			   "interleaving hugepagesz=, ignoring\n");
+		return 1;
+	}
+
+	if (sscanf(s, "%lu", mhp) <= 0)
+		*mhp = 0;
+
+	/*
+	 * Global state is always initialized later in hugetlb_init.
+	 * But we need to allocate >= MAX_ORDER hstates here early to still
+	 * use the bootmem allocator.
+	 */
+	if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
+		hugetlb_hstate_alloc_pages(parsed_hstate);
+
+	last_mhp = mhp;
+
+	return 1;
+}
+__setup("hugepages=", hugetlb_nrpages_setup);
+
+static int __init hugetlb_default_setup(char *s)
+{
+	default_hstate_size = memparse(s, &s);
+	return 1;
+}
+__setup("default_hugepagesz=", hugetlb_default_setup);
+
+static unsigned int cpuset_mems_nr(unsigned int *array)
+{
+	int node;
+	unsigned int nr = 0;
+
+	for_each_node_mask(node, cpuset_current_mems_allowed)
+		nr += array[node];
+
+	return nr;
+}
+
+#ifdef CONFIG_SYSCTL
+static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
+			 struct ctl_table *table, int write,
+			 void __user *buffer, size_t *length, loff_t *ppos)
+{
+	struct hstate *h = &default_hstate;
+	unsigned long tmp = h->max_huge_pages;
+	int ret;
+
+	if (!hugepages_supported())
+		return -ENOTSUPP;
+
+	table->data = &tmp;
+	table->maxlen = sizeof(unsigned long);
+	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
+	if (ret)
+		goto out;
+
+	if (write)
+		ret = __nr_hugepages_store_common(obey_mempolicy, h,
+						  NUMA_NO_NODE, tmp, *length);
+out:
+	return ret;
+}
+
+int hugetlb_sysctl_handler(struct ctl_table *table, int write,
+			  void __user *buffer, size_t *length, loff_t *ppos)
+{
+
+	return hugetlb_sysctl_handler_common(false, table, write,
+							buffer, length, ppos);
+}
+
+#ifdef CONFIG_NUMA
+int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
+			  void __user *buffer, size_t *length, loff_t *ppos)
+{
+	return hugetlb_sysctl_handler_common(true, table, write,
+							buffer, length, ppos);
+}
+#endif /* CONFIG_NUMA */
+
+int hugetlb_overcommit_handler(struct ctl_table *table, int write,
+			void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	struct hstate *h = &default_hstate;
+	unsigned long tmp;
+	int ret;
+
+	if (!hugepages_supported())
+		return -ENOTSUPP;
+
+	tmp = h->nr_overcommit_huge_pages;
+
+	if (write && hstate_is_gigantic(h))
+		return -EINVAL;
+
+	table->data = &tmp;
+	table->maxlen = sizeof(unsigned long);
+	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
+	if (ret)
+		goto out;
+
+	if (write) {
+		spin_lock(&hugetlb_lock);
+		h->nr_overcommit_huge_pages = tmp;
+		spin_unlock(&hugetlb_lock);
+	}
+out:
+	return ret;
+}
+
+#endif /* CONFIG_SYSCTL */
+
+void hugetlb_report_meminfo(struct seq_file *m)
+{
+	struct hstate *h = &default_hstate;
+	if (!hugepages_supported())
+		return;
+	seq_printf(m,
+			"HugePages_Total:   %5lu\n"
+			"HugePages_Free:    %5lu\n"
+			"HugePages_Rsvd:    %5lu\n"
+			"HugePages_Surp:    %5lu\n"
+			"Hugepagesize:   %8lu kB\n",
+			h->nr_huge_pages,
+			h->free_huge_pages,
+			h->resv_huge_pages,
+			h->surplus_huge_pages,
+			1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
+}
+
+int hugetlb_report_node_meminfo(int nid, char *buf)
+{
+	struct hstate *h = &default_hstate;
+	if (!hugepages_supported())
+		return 0;
+	return sprintf(buf,
+		"Node %d HugePages_Total: %5u\n"
+		"Node %d HugePages_Free:  %5u\n"
+		"Node %d HugePages_Surp:  %5u\n",
+		nid, h->nr_huge_pages_node[nid],
+		nid, h->free_huge_pages_node[nid],
+		nid, h->surplus_huge_pages_node[nid]);
+}
+
+void hugetlb_show_meminfo(void)
+{
+	struct hstate *h;
+	int nid;
+
+	if (!hugepages_supported())
+		return;
+
+	for_each_node_state(nid, N_MEMORY)
+		for_each_hstate(h)
+			pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
+				nid,
+				h->nr_huge_pages_node[nid],
+				h->free_huge_pages_node[nid],
+				h->surplus_huge_pages_node[nid],
+				1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
+}
+
+void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
+{
+	seq_printf(m, "HugetlbPages:\t%8lu kB\n",
+		   atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
+}
+
+/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
+unsigned long hugetlb_total_pages(void)
+{
+	struct hstate *h;
+	unsigned long nr_total_pages = 0;
+
+	for_each_hstate(h)
+		nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
+	return nr_total_pages;
+}
+
+static int hugetlb_acct_memory(struct hstate *h, long delta)
+{
+	int ret = -ENOMEM;
+
+	spin_lock(&hugetlb_lock);
+	/*
+	 * When cpuset is configured, it breaks the strict hugetlb page
+	 * reservation as the accounting is done on a global variable. Such
+	 * reservation is completely rubbish in the presence of cpuset because
+	 * the reservation is not checked against page availability for the
+	 * current cpuset. Application can still potentially OOM'ed by kernel
+	 * with lack of free htlb page in cpuset that the task is in.
+	 * Attempt to enforce strict accounting with cpuset is almost
+	 * impossible (or too ugly) because cpuset is too fluid that
+	 * task or memory node can be dynamically moved between cpusets.
+	 *
+	 * The change of semantics for shared hugetlb mapping with cpuset is
+	 * undesirable. However, in order to preserve some of the semantics,
+	 * we fall back to check against current free page availability as
+	 * a best attempt and hopefully to minimize the impact of changing
+	 * semantics that cpuset has.
+	 */
+	if (delta > 0) {
+		if (gather_surplus_pages(h, delta) < 0)
+			goto out;
+
+		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
+			return_unused_surplus_pages(h, delta);
+			goto out;
+		}
+	}
+
+	ret = 0;
+	if (delta < 0)
+		return_unused_surplus_pages(h, (unsigned long) -delta);
+
+out:
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+
+static void hugetlb_vm_op_open(struct vm_area_struct *vma)
+{
+	struct resv_map *resv = vma_resv_map(vma);
+
+	/*
+	 * This new VMA should share its siblings reservation map if present.
+	 * The VMA will only ever have a valid reservation map pointer where
+	 * it is being copied for another still existing VMA.  As that VMA
+	 * has a reference to the reservation map it cannot disappear until
+	 * after this open call completes.  It is therefore safe to take a
+	 * new reference here without additional locking.
+	 */
+	if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
+		kref_get(&resv->refs);
+}
+
+static void hugetlb_vm_op_close(struct vm_area_struct *vma)
+{
+	struct hstate *h = hstate_vma(vma);
+	struct resv_map *resv = vma_resv_map(vma);
+	struct hugepage_subpool *spool = subpool_vma(vma);
+	unsigned long reserve, start, end;
+	long gbl_reserve;
+
+	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
+		return;
+
+	start = vma_hugecache_offset(h, vma, vma->vm_start);
+	end = vma_hugecache_offset(h, vma, vma->vm_end);
+
+	reserve = (end - start) - region_count(resv, start, end);
+
+	kref_put(&resv->refs, resv_map_release);
+
+	if (reserve) {
+		/*
+		 * Decrement reserve counts.  The global reserve count may be
+		 * adjusted if the subpool has a minimum size.
+		 */
+		gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
+		hugetlb_acct_memory(h, -gbl_reserve);
+	}
+}
+
+/*
+ * We cannot handle pagefaults against hugetlb pages at all.  They cause
+ * handle_mm_fault() to try to instantiate regular-sized pages in the
+ * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
+ * this far.
+ */
+static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	BUG();
+	return 0;
+}
+
+const struct vm_operations_struct hugetlb_vm_ops = {
+	.fault = hugetlb_vm_op_fault,
+	.open = hugetlb_vm_op_open,
+	.close = hugetlb_vm_op_close,
+};
+
+static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
+				int writable)
+{
+	pte_t entry;
+
+	if (writable) {
+		entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
+					 vma->vm_page_prot)));
+	} else {
+		entry = huge_pte_wrprotect(mk_huge_pte(page,
+					   vma->vm_page_prot));
+	}
+	entry = pte_mkyoung(entry);
+	entry = pte_mkhuge(entry);
+	entry = arch_make_huge_pte(entry, vma, page, writable);
+
+	return entry;
+}
+
+static void set_huge_ptep_writable(struct vm_area_struct *vma,
+				   unsigned long address, pte_t *ptep)
+{
+	pte_t entry;
+
+	entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
+	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
+		update_mmu_cache(vma, address, ptep);
+}
+
+static int is_hugetlb_entry_migration(pte_t pte)
+{
+	swp_entry_t swp;
+
+	if (huge_pte_none(pte) || pte_present(pte))
+		return 0;
+	swp = pte_to_swp_entry(pte);
+	if (non_swap_entry(swp) && is_migration_entry(swp))
+		return 1;
+	else
+		return 0;
+}
+
+static int is_hugetlb_entry_hwpoisoned(pte_t pte)
+{
+	swp_entry_t swp;
+
+	if (huge_pte_none(pte) || pte_present(pte))
+		return 0;
+	swp = pte_to_swp_entry(pte);
+	if (non_swap_entry(swp) && is_hwpoison_entry(swp))
+		return 1;
+	else
+		return 0;
+}
+
+int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
+			    struct vm_area_struct *vma)
+{
+	pte_t *src_pte, *dst_pte, entry;
+	struct page *ptepage;
+	unsigned long addr;
+	int cow;
+	struct hstate *h = hstate_vma(vma);
+	unsigned long sz = huge_page_size(h);
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+	int ret = 0;
+
+	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+
+	mmun_start = vma->vm_start;
+	mmun_end = vma->vm_end;
+	if (cow)
+		mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
+
+	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
+		spinlock_t *src_ptl, *dst_ptl;
+		src_pte = huge_pte_offset(src, addr);
+		if (!src_pte)
+			continue;
+		dst_pte = huge_pte_alloc(dst, addr, sz);
+		if (!dst_pte) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		/* If the pagetables are shared don't copy or take references */
+		if (dst_pte == src_pte)
+			continue;
+
+		dst_ptl = huge_pte_lock(h, dst, dst_pte);
+		src_ptl = huge_pte_lockptr(h, src, src_pte);
+		spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+		entry = huge_ptep_get(src_pte);
+		if (huge_pte_none(entry)) { /* skip none entry */
+			;
+		} else if (unlikely(is_hugetlb_entry_migration(entry) ||
+				    is_hugetlb_entry_hwpoisoned(entry))) {
+			swp_entry_t swp_entry = pte_to_swp_entry(entry);
+
+			if (is_write_migration_entry(swp_entry) && cow) {
+				/*
+				 * COW mappings require pages in both
+				 * parent and child to be set to read.
+				 */
+				make_migration_entry_read(&swp_entry);
+				entry = swp_entry_to_pte(swp_entry);
+				set_huge_pte_at(src, addr, src_pte, entry);
+			}
+			set_huge_pte_at(dst, addr, dst_pte, entry);
+		} else {
+			if (cow) {
+				huge_ptep_set_wrprotect(src, addr, src_pte);
+				mmu_notifier_invalidate_range(src, mmun_start,
+								   mmun_end);
+			}
+			entry = huge_ptep_get(src_pte);
+			ptepage = pte_page(entry);
+			get_page(ptepage);
+			page_dup_rmap(ptepage);
+			set_huge_pte_at(dst, addr, dst_pte, entry);
+			hugetlb_count_add(pages_per_huge_page(h), dst);
+		}
+		spin_unlock(src_ptl);
+		spin_unlock(dst_ptl);
+	}
+
+	if (cow)
+		mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
+
+	return ret;
+}
+
+void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
+			    unsigned long start, unsigned long end,
+			    struct page *ref_page)
+{
+	int force_flush = 0;
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long address;
+	pte_t *ptep;
+	pte_t pte;
+	spinlock_t *ptl;
+	struct page *page;
+	struct hstate *h = hstate_vma(vma);
+	unsigned long sz = huge_page_size(h);
+	const unsigned long mmun_start = start;	/* For mmu_notifiers */
+	const unsigned long mmun_end   = end;	/* For mmu_notifiers */
+
+	WARN_ON(!is_vm_hugetlb_page(vma));
+	BUG_ON(start & ~huge_page_mask(h));
+	BUG_ON(end & ~huge_page_mask(h));
+
+	tlb_start_vma(tlb, vma);
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	address = start;
+again:
+	for (; address < end; address += sz) {
+		ptep = huge_pte_offset(mm, address);
+		if (!ptep)
+			continue;
+
+		ptl = huge_pte_lock(h, mm, ptep);
+		if (huge_pmd_unshare(mm, &address, ptep))
+			goto unlock;
+
+		pte = huge_ptep_get(ptep);
+		if (huge_pte_none(pte))
+			goto unlock;
+
+		/*
+		 * Migrating hugepage or HWPoisoned hugepage is already
+		 * unmapped and its refcount is dropped, so just clear pte here.
+		 */
+		if (unlikely(!pte_present(pte))) {
+			huge_pte_clear(mm, address, ptep);
+			goto unlock;
+		}
+
+		page = pte_page(pte);
+		/*
+		 * If a reference page is supplied, it is because a specific
+		 * page is being unmapped, not a range. Ensure the page we
+		 * are about to unmap is the actual page of interest.
+		 */
+		if (ref_page) {
+			if (page != ref_page)
+				goto unlock;
+
+			/*
+			 * Mark the VMA as having unmapped its page so that
+			 * future faults in this VMA will fail rather than
+			 * looking like data was lost
+			 */
+			set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
+		}
+
+		pte = huge_ptep_get_and_clear(mm, address, ptep);
+		tlb_remove_tlb_entry(tlb, ptep, address);
+		if (huge_pte_dirty(pte))
+			set_page_dirty(page);
+
+		hugetlb_count_sub(pages_per_huge_page(h), mm);
+		page_remove_rmap(page);
+		force_flush = !__tlb_remove_page(tlb, page);
+		if (force_flush) {
+			address += sz;
+			spin_unlock(ptl);
+			break;
+		}
+		/* Bail out after unmapping reference page if supplied */
+		if (ref_page) {
+			spin_unlock(ptl);
+			break;
+		}
+unlock:
+		spin_unlock(ptl);
+	}
+	/*
+	 * mmu_gather ran out of room to batch pages, we break out of
+	 * the PTE lock to avoid doing the potential expensive TLB invalidate
+	 * and page-free while holding it.
+	 */
+	if (force_flush) {
+		force_flush = 0;
+		tlb_flush_mmu(tlb);
+		if (address < end && !ref_page)
+			goto again;
+	}
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+	tlb_end_vma(tlb, vma);
+}
+
+void __unmap_hugepage_range_final(struct mmu_gather *tlb,
+			  struct vm_area_struct *vma, unsigned long start,
+			  unsigned long end, struct page *ref_page)
+{
+	__unmap_hugepage_range(tlb, vma, start, end, ref_page);
+
+	/*
+	 * Clear this flag so that x86's huge_pmd_share page_table_shareable
+	 * test will fail on a vma being torn down, and not grab a page table
+	 * on its way out.  We're lucky that the flag has such an appropriate
+	 * name, and can in fact be safely cleared here. We could clear it
+	 * before the __unmap_hugepage_range above, but all that's necessary
+	 * is to clear it before releasing the i_mmap_rwsem. This works
+	 * because in the context this is called, the VMA is about to be
+	 * destroyed and the i_mmap_rwsem is held.
+	 */
+	vma->vm_flags &= ~VM_MAYSHARE;
+}
+
+void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
+			  unsigned long end, struct page *ref_page)
+{
+	struct mm_struct *mm;
+	struct mmu_gather tlb;
+
+	mm = vma->vm_mm;
+
+	tlb_gather_mmu(&tlb, mm, start, end);
+	__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
+	tlb_finish_mmu(&tlb, start, end);
+}
+
+/*
+ * This is called when the original mapper is failing to COW a MAP_PRIVATE
+ * mappping it owns the reserve page for. The intention is to unmap the page
+ * from other VMAs and let the children be SIGKILLed if they are faulting the
+ * same region.
+ */
+static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
+			      struct page *page, unsigned long address)
+{
+	struct hstate *h = hstate_vma(vma);
+	struct vm_area_struct *iter_vma;
+	struct address_space *mapping;
+	pgoff_t pgoff;
+
+	/*
+	 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
+	 * from page cache lookup which is in HPAGE_SIZE units.
+	 */
+	address = address & huge_page_mask(h);
+	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
+			vma->vm_pgoff;
+	mapping = file_inode(vma->vm_file)->i_mapping;
+
+	/*
+	 * Take the mapping lock for the duration of the table walk. As
+	 * this mapping should be shared between all the VMAs,
+	 * __unmap_hugepage_range() is called as the lock is already held
+	 */
+	i_mmap_lock_write(mapping);
+	vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
+		/* Do not unmap the current VMA */
+		if (iter_vma == vma)
+			continue;
+
+		/*
+		 * Shared VMAs have their own reserves and do not affect
+		 * MAP_PRIVATE accounting but it is possible that a shared
+		 * VMA is using the same page so check and skip such VMAs.
+		 */
+		if (iter_vma->vm_flags & VM_MAYSHARE)
+			continue;
+
+		/*
+		 * Unmap the page from other VMAs without their own reserves.
+		 * They get marked to be SIGKILLed if they fault in these
+		 * areas. This is because a future no-page fault on this VMA
+		 * could insert a zeroed page instead of the data existing
+		 * from the time of fork. This would look like data corruption
+		 */
+		if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
+			unmap_hugepage_range(iter_vma, address,
+					     address + huge_page_size(h), page);
+	}
+	i_mmap_unlock_write(mapping);
+}
+
+/*
+ * Hugetlb_cow() should be called with page lock of the original hugepage held.
+ * Called with hugetlb_instantiation_mutex held and pte_page locked so we
+ * cannot race with other handlers or page migration.
+ * Keep the pte_same checks anyway to make transition from the mutex easier.
+ */
+static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pte_t *ptep, pte_t pte,
+			struct page *pagecache_page, spinlock_t *ptl)
+{
+	struct hstate *h = hstate_vma(vma);
+	struct page *old_page, *new_page;
+	int ret = 0, outside_reserve = 0;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+
+	old_page = pte_page(pte);
+
+retry_avoidcopy:
+	/* If no-one else is actually using this page, avoid the copy
+	 * and just make the page writable */
+	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
+		page_move_anon_rmap(old_page, vma, address);
+		set_huge_ptep_writable(vma, address, ptep);
+		return 0;
+	}
+
+	/*
+	 * If the process that created a MAP_PRIVATE mapping is about to
+	 * perform a COW due to a shared page count, attempt to satisfy
+	 * the allocation without using the existing reserves. The pagecache
+	 * page is used to determine if the reserve at this address was
+	 * consumed or not. If reserves were used, a partial faulted mapping
+	 * at the time of fork() could consume its reserves on COW instead
+	 * of the full address range.
+	 */
+	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
+			old_page != pagecache_page)
+		outside_reserve = 1;
+
+	page_cache_get(old_page);
+
+	/*
+	 * Drop page table lock as buddy allocator may be called. It will
+	 * be acquired again before returning to the caller, as expected.
+	 */
+	spin_unlock(ptl);
+	new_page = alloc_huge_page(vma, address, outside_reserve);
+
+	if (IS_ERR(new_page)) {
+		/*
+		 * If a process owning a MAP_PRIVATE mapping fails to COW,
+		 * it is due to references held by a child and an insufficient
+		 * huge page pool. To guarantee the original mappers
+		 * reliability, unmap the page from child processes. The child
+		 * may get SIGKILLed if it later faults.
+		 */
+		if (outside_reserve) {
+			page_cache_release(old_page);
+			BUG_ON(huge_pte_none(pte));
+			unmap_ref_private(mm, vma, old_page, address);
+			BUG_ON(huge_pte_none(pte));
+			spin_lock(ptl);
+			ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+			if (likely(ptep &&
+				   pte_same(huge_ptep_get(ptep), pte)))
+				goto retry_avoidcopy;
+			/*
+			 * race occurs while re-acquiring page table
+			 * lock, and our job is done.
+			 */
+			return 0;
+		}
+
+		ret = (PTR_ERR(new_page) == -ENOMEM) ?
+			VM_FAULT_OOM : VM_FAULT_SIGBUS;
+		goto out_release_old;
+	}
+
+	/*
+	 * When the original hugepage is shared one, it does not have
+	 * anon_vma prepared.
+	 */
+	if (unlikely(anon_vma_prepare(vma))) {
+		ret = VM_FAULT_OOM;
+		goto out_release_all;
+	}
+
+	copy_user_huge_page(new_page, old_page, address, vma,
+			    pages_per_huge_page(h));
+	__SetPageUptodate(new_page);
+	set_page_huge_active(new_page);
+
+	mmun_start = address & huge_page_mask(h);
+	mmun_end = mmun_start + huge_page_size(h);
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+	/*
+	 * Retake the page table lock to check for racing updates
+	 * before the page tables are altered
+	 */
+	spin_lock(ptl);
+	ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
+		ClearPagePrivate(new_page);
+
+		/* Break COW */
+		huge_ptep_clear_flush(vma, address, ptep);
+		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
+		set_huge_pte_at(mm, address, ptep,
+				make_huge_pte(vma, new_page, 1));
+		page_remove_rmap(old_page);
+		hugepage_add_new_anon_rmap(new_page, vma, address);
+		/* Make the old page be freed below */
+		new_page = old_page;
+	}
+	spin_unlock(ptl);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out_release_all:
+	page_cache_release(new_page);
+out_release_old:
+	page_cache_release(old_page);
+
+	spin_lock(ptl); /* Caller expects lock to be held */
+	return ret;
+}
+
+/* Return the pagecache page at a given address within a VMA */
+static struct page *hugetlbfs_pagecache_page(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	struct address_space *mapping;
+	pgoff_t idx;
+
+	mapping = vma->vm_file->f_mapping;
+	idx = vma_hugecache_offset(h, vma, address);
+
+	return find_lock_page(mapping, idx);
+}
+
+/*
+ * Return whether there is a pagecache page to back given address within VMA.
+ * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
+ */
+static bool hugetlbfs_pagecache_present(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	struct address_space *mapping;
+	pgoff_t idx;
+	struct page *page;
+
+	mapping = vma->vm_file->f_mapping;
+	idx = vma_hugecache_offset(h, vma, address);
+
+	page = find_get_page(mapping, idx);
+	if (page)
+		put_page(page);
+	return page != NULL;
+}
+
+int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
+			   pgoff_t idx)
+{
+	struct inode *inode = mapping->host;
+	struct hstate *h = hstate_inode(inode);
+	int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
+
+	if (err)
+		return err;
+	ClearPagePrivate(page);
+
+	spin_lock(&inode->i_lock);
+	inode->i_blocks += blocks_per_huge_page(h);
+	spin_unlock(&inode->i_lock);
+	return 0;
+}
+
+static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			   struct address_space *mapping, pgoff_t idx,
+			   unsigned long address, pte_t *ptep, unsigned int flags)
+{
+	struct hstate *h = hstate_vma(vma);
+	int ret = VM_FAULT_SIGBUS;
+	int anon_rmap = 0;
+	unsigned long size;
+	struct page *page;
+	pte_t new_pte;
+	spinlock_t *ptl;
+
+	/*
+	 * Currently, we are forced to kill the process in the event the
+	 * original mapper has unmapped pages from the child due to a failed
+	 * COW. Warn that such a situation has occurred as it may not be obvious
+	 */
+	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
+		pr_warning("PID %d killed due to inadequate hugepage pool\n",
+			   current->pid);
+		return ret;
+	}
+
+	/*
+	 * Use page lock to guard against racing truncation
+	 * before we get page_table_lock.
+	 */
+retry:
+	page = find_lock_page(mapping, idx);
+	if (!page) {
+		size = i_size_read(mapping->host) >> huge_page_shift(h);
+		if (idx >= size)
+			goto out;
+		page = alloc_huge_page(vma, address, 0);
+		if (IS_ERR(page)) {
+			ret = PTR_ERR(page);
+			if (ret == -ENOMEM)
+				ret = VM_FAULT_OOM;
+			else
+				ret = VM_FAULT_SIGBUS;
+			goto out;
+		}
+		clear_huge_page(page, address, pages_per_huge_page(h));
+		__SetPageUptodate(page);
+		set_page_huge_active(page);
+
+		if (vma->vm_flags & VM_MAYSHARE) {
+			int err = huge_add_to_page_cache(page, mapping, idx);
+			if (err) {
+				put_page(page);
+				if (err == -EEXIST)
+					goto retry;
+				goto out;
+			}
+		} else {
+			lock_page(page);
+			if (unlikely(anon_vma_prepare(vma))) {
+				ret = VM_FAULT_OOM;
+				goto backout_unlocked;
+			}
+			anon_rmap = 1;
+		}
+	} else {
+		/*
+		 * If memory error occurs between mmap() and fault, some process
+		 * don't have hwpoisoned swap entry for errored virtual address.
+		 * So we need to block hugepage fault by PG_hwpoison bit check.
+		 */
+		if (unlikely(PageHWPoison(page))) {
+			ret = VM_FAULT_HWPOISON |
+				VM_FAULT_SET_HINDEX(hstate_index(h));
+			goto backout_unlocked;
+		}
+	}
+
+	/*
+	 * If we are going to COW a private mapping later, we examine the
+	 * pending reservations for this page now. This will ensure that
+	 * any allocations necessary to record that reservation occur outside
+	 * the spinlock.
+	 */
+	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
+		if (vma_needs_reservation(h, vma, address) < 0) {
+			ret = VM_FAULT_OOM;
+			goto backout_unlocked;
+		}
+		/* Just decrements count, does not deallocate */
+		vma_end_reservation(h, vma, address);
+	}
+
+	ptl = huge_pte_lockptr(h, mm, ptep);
+	spin_lock(ptl);
+	size = i_size_read(mapping->host) >> huge_page_shift(h);
+	if (idx >= size)
+		goto backout;
+
+	ret = 0;
+	if (!huge_pte_none(huge_ptep_get(ptep)))
+		goto backout;
+
+	if (anon_rmap) {
+		ClearPagePrivate(page);
+		hugepage_add_new_anon_rmap(page, vma, address);
+	} else
+		page_dup_rmap(page);
+	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
+				&& (vma->vm_flags & VM_SHARED)));
+	set_huge_pte_at(mm, address, ptep, new_pte);
+
+	hugetlb_count_add(pages_per_huge_page(h), mm);
+	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
+		/* Optimization, do the COW without a second fault */
+		ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl);
+	}
+
+	spin_unlock(ptl);
+	unlock_page(page);
+out:
+	return ret;
+
+backout:
+	spin_unlock(ptl);
+backout_unlocked:
+	unlock_page(page);
+	put_page(page);
+	goto out;
+}
+
+#ifdef CONFIG_SMP
+u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
+			    struct vm_area_struct *vma,
+			    struct address_space *mapping,
+			    pgoff_t idx, unsigned long address)
+{
+	unsigned long key[2];
+	u32 hash;
+
+	if (vma->vm_flags & VM_SHARED) {
+		key[0] = (unsigned long) mapping;
+		key[1] = idx;
+	} else {
+		key[0] = (unsigned long) mm;
+		key[1] = address >> huge_page_shift(h);
+	}
+
+	hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
+
+	return hash & (num_fault_mutexes - 1);
+}
+#else
+/*
+ * For uniprocesor systems we always use a single mutex, so just
+ * return 0 and avoid the hashing overhead.
+ */
+u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
+			    struct vm_area_struct *vma,
+			    struct address_space *mapping,
+			    pgoff_t idx, unsigned long address)
+{
+	return 0;
+}
+#endif
+
+int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, unsigned int flags)
+{
+	pte_t *ptep, entry;
+	spinlock_t *ptl;
+	int ret;
+	u32 hash;
+	pgoff_t idx;
+	struct page *page = NULL;
+	struct page *pagecache_page = NULL;
+	struct hstate *h = hstate_vma(vma);
+	struct address_space *mapping;
+	int need_wait_lock = 0;
+
+	address &= huge_page_mask(h);
+
+	ptep = huge_pte_offset(mm, address);
+	if (ptep) {
+		entry = huge_ptep_get(ptep);
+		if (unlikely(is_hugetlb_entry_migration(entry))) {
+			migration_entry_wait_huge(vma, mm, ptep);
+			return 0;
+		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
+			return VM_FAULT_HWPOISON_LARGE |
+				VM_FAULT_SET_HINDEX(hstate_index(h));
+	} else {
+		ptep = huge_pte_alloc(mm, address, huge_page_size(h));
+		if (!ptep)
+			return VM_FAULT_OOM;
+	}
+
+	mapping = vma->vm_file->f_mapping;
+	idx = vma_hugecache_offset(h, vma, address);
+
+	/*
+	 * Serialize hugepage allocation and instantiation, so that we don't
+	 * get spurious allocation failures if two CPUs race to instantiate
+	 * the same page in the page cache.
+	 */
+	hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
+	mutex_lock(&hugetlb_fault_mutex_table[hash]);
+
+	entry = huge_ptep_get(ptep);
+	if (huge_pte_none(entry)) {
+		ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
+		goto out_mutex;
+	}
+
+	ret = 0;
+
+	/*
+	 * entry could be a migration/hwpoison entry at this point, so this
+	 * check prevents the kernel from going below assuming that we have
+	 * a active hugepage in pagecache. This goto expects the 2nd page fault,
+	 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
+	 * handle it.
+	 */
+	if (!pte_present(entry))
+		goto out_mutex;
+
+	/*
+	 * If we are going to COW the mapping later, we examine the pending
+	 * reservations for this page now. This will ensure that any
+	 * allocations necessary to record that reservation occur outside the
+	 * spinlock. For private mappings, we also lookup the pagecache
+	 * page now as it is used to determine if a reservation has been
+	 * consumed.
+	 */
+	if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
+		if (vma_needs_reservation(h, vma, address) < 0) {
+			ret = VM_FAULT_OOM;
+			goto out_mutex;
+		}
+		/* Just decrements count, does not deallocate */
+		vma_end_reservation(h, vma, address);
+
+		if (!(vma->vm_flags & VM_MAYSHARE))
+			pagecache_page = hugetlbfs_pagecache_page(h,
+								vma, address);
+	}
+
+	ptl = huge_pte_lock(h, mm, ptep);
+
+	/* Check for a racing update before calling hugetlb_cow */
+	if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
+		goto out_ptl;
+
+	/*
+	 * hugetlb_cow() requires page locks of pte_page(entry) and
+	 * pagecache_page, so here we need take the former one
+	 * when page != pagecache_page or !pagecache_page.
+	 */
+	page = pte_page(entry);
+	if (page != pagecache_page)
+		if (!trylock_page(page)) {
+			need_wait_lock = 1;
+			goto out_ptl;
+		}
+
+	get_page(page);
+
+	if (flags & FAULT_FLAG_WRITE) {
+		if (!huge_pte_write(entry)) {
+			ret = hugetlb_cow(mm, vma, address, ptep, entry,
+					pagecache_page, ptl);
+			goto out_put_page;
+		}
+		entry = huge_pte_mkdirty(entry);
+	}
+	entry = pte_mkyoung(entry);
+	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
+						flags & FAULT_FLAG_WRITE))
+		update_mmu_cache(vma, address, ptep);
+out_put_page:
+	if (page != pagecache_page)
+		unlock_page(page);
+	put_page(page);
+out_ptl:
+	spin_unlock(ptl);
+
+	if (pagecache_page) {
+		unlock_page(pagecache_page);
+		put_page(pagecache_page);
+	}
+out_mutex:
+	mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+	/*
+	 * Generally it's safe to hold refcount during waiting page lock. But
+	 * here we just wait to defer the next page fault to avoid busy loop and
+	 * the page is not used after unlocked before returning from the current
+	 * page fault. So we are safe from accessing freed page, even if we wait
+	 * here without taking refcount.
+	 */
+	if (need_wait_lock)
+		wait_on_page_locked(page);
+	return ret;
+}
+
+long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			 struct page **pages, struct vm_area_struct **vmas,
+			 unsigned long *position, unsigned long *nr_pages,
+			 long i, unsigned int flags)
+{
+	unsigned long pfn_offset;
+	unsigned long vaddr = *position;
+	unsigned long remainder = *nr_pages;
+	struct hstate *h = hstate_vma(vma);
+
+	while (vaddr < vma->vm_end && remainder) {
+		pte_t *pte;
+		spinlock_t *ptl = NULL;
+		int absent;
+		struct page *page;
+
+		/*
+		 * If we have a pending SIGKILL, don't keep faulting pages and
+		 * potentially allocating memory.
+		 */
+		if (unlikely(fatal_signal_pending(current))) {
+			remainder = 0;
+			break;
+		}
+
+		/*
+		 * Some archs (sparc64, sh*) have multiple pte_ts to
+		 * each hugepage.  We have to make sure we get the
+		 * first, for the page indexing below to work.
+		 *
+		 * Note that page table lock is not held when pte is null.
+		 */
+		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
+		if (pte)
+			ptl = huge_pte_lock(h, mm, pte);
+		absent = !pte || huge_pte_none(huge_ptep_get(pte));
+
+		/*
+		 * When coredumping, it suits get_dump_page if we just return
+		 * an error where there's an empty slot with no huge pagecache
+		 * to back it.  This way, we avoid allocating a hugepage, and
+		 * the sparse dumpfile avoids allocating disk blocks, but its
+		 * huge holes still show up with zeroes where they need to be.
+		 */
+		if (absent && (flags & FOLL_DUMP) &&
+		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
+			if (pte)
+				spin_unlock(ptl);
+			remainder = 0;
+			break;
+		}
+
+		/*
+		 * We need call hugetlb_fault for both hugepages under migration
+		 * (in which case hugetlb_fault waits for the migration,) and
+		 * hwpoisoned hugepages (in which case we need to prevent the
+		 * caller from accessing to them.) In order to do this, we use
+		 * here is_swap_pte instead of is_hugetlb_entry_migration and
+		 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
+		 * both cases, and because we can't follow correct pages
+		 * directly from any kind of swap entries.
+		 */
+		if (absent || is_swap_pte(huge_ptep_get(pte)) ||
+		    ((flags & FOLL_WRITE) &&
+		      !huge_pte_write(huge_ptep_get(pte)))) {
+			int ret;
+
+			if (pte)
+				spin_unlock(ptl);
+			ret = hugetlb_fault(mm, vma, vaddr,
+				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
+			if (!(ret & VM_FAULT_ERROR))
+				continue;
+
+			remainder = 0;
+			break;
+		}
+
+		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
+		page = pte_page(huge_ptep_get(pte));
+same_page:
+		if (pages) {
+			pages[i] = mem_map_offset(page, pfn_offset);
+			get_page_foll(pages[i]);
+		}
+
+		if (vmas)
+			vmas[i] = vma;
+
+		vaddr += PAGE_SIZE;
+		++pfn_offset;
+		--remainder;
+		++i;
+		if (vaddr < vma->vm_end && remainder &&
+				pfn_offset < pages_per_huge_page(h)) {
+			/*
+			 * We use pfn_offset to avoid touching the pageframes
+			 * of this compound page.
+			 */
+			goto same_page;
+		}
+		spin_unlock(ptl);
+	}
+	*nr_pages = remainder;
+	*position = vaddr;
+
+	return i ? i : -EFAULT;
+}
+
+unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
+		unsigned long address, unsigned long end, pgprot_t newprot)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long start = address;
+	pte_t *ptep;
+	pte_t pte;
+	struct hstate *h = hstate_vma(vma);
+	unsigned long pages = 0;
+
+	BUG_ON(address >= end);
+	flush_cache_range(vma, address, end);
+
+	mmu_notifier_invalidate_range_start(mm, start, end);
+	i_mmap_lock_write(vma->vm_file->f_mapping);
+	for (; address < end; address += huge_page_size(h)) {
+		spinlock_t *ptl;
+		ptep = huge_pte_offset(mm, address);
+		if (!ptep)
+			continue;
+		ptl = huge_pte_lock(h, mm, ptep);
+		if (huge_pmd_unshare(mm, &address, ptep)) {
+			pages++;
+			spin_unlock(ptl);
+			continue;
+		}
+		pte = huge_ptep_get(ptep);
+		if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
+			spin_unlock(ptl);
+			continue;
+		}
+		if (unlikely(is_hugetlb_entry_migration(pte))) {
+			swp_entry_t entry = pte_to_swp_entry(pte);
+
+			if (is_write_migration_entry(entry)) {
+				pte_t newpte;
+
+				make_migration_entry_read(&entry);
+				newpte = swp_entry_to_pte(entry);
+				set_huge_pte_at(mm, address, ptep, newpte);
+				pages++;
+			}
+			spin_unlock(ptl);
+			continue;
+		}
+		if (!huge_pte_none(pte)) {
+			pte = huge_ptep_get_and_clear(mm, address, ptep);
+			pte = pte_mkhuge(huge_pte_modify(pte, newprot));
+			pte = arch_make_huge_pte(pte, vma, NULL, 0);
+			set_huge_pte_at(mm, address, ptep, pte);
+			pages++;
+		}
+		spin_unlock(ptl);
+	}
+	/*
+	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
+	 * may have cleared our pud entry and done put_page on the page table:
+	 * once we release i_mmap_rwsem, another task can do the final put_page
+	 * and that page table be reused and filled with junk.
+	 */
+	flush_tlb_range(vma, start, end);
+	mmu_notifier_invalidate_range(mm, start, end);
+	i_mmap_unlock_write(vma->vm_file->f_mapping);
+	mmu_notifier_invalidate_range_end(mm, start, end);
+
+	return pages << h->order;
+}
+
+int hugetlb_reserve_pages(struct inode *inode,
+					long from, long to,
+					struct vm_area_struct *vma,
+					vm_flags_t vm_flags)
+{
+	long ret, chg;
+	struct hstate *h = hstate_inode(inode);
+	struct hugepage_subpool *spool = subpool_inode(inode);
+	struct resv_map *resv_map;
+	long gbl_reserve;
+
+	/*
+	 * Only apply hugepage reservation if asked. At fault time, an
+	 * attempt will be made for VM_NORESERVE to allocate a page
+	 * without using reserves
+	 */
+	if (vm_flags & VM_NORESERVE)
+		return 0;
+
+	/*
+	 * Shared mappings base their reservation on the number of pages that
+	 * are already allocated on behalf of the file. Private mappings need
+	 * to reserve the full area even if read-only as mprotect() may be
+	 * called to make the mapping read-write. Assume !vma is a shm mapping
+	 */
+	if (!vma || vma->vm_flags & VM_MAYSHARE) {
+		resv_map = inode_resv_map(inode);
+
+		chg = region_chg(resv_map, from, to);
+
+	} else {
+		resv_map = resv_map_alloc();
+		if (!resv_map)
+			return -ENOMEM;
+
+		chg = to - from;
+
+		set_vma_resv_map(vma, resv_map);
+		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
+	}
+
+	if (chg < 0) {
+		ret = chg;
+		goto out_err;
+	}
+
+	/*
+	 * There must be enough pages in the subpool for the mapping. If
+	 * the subpool has a minimum size, there may be some global
+	 * reservations already in place (gbl_reserve).
+	 */
+	gbl_reserve = hugepage_subpool_get_pages(spool, chg);
+	if (gbl_reserve < 0) {
+		ret = -ENOSPC;
+		goto out_err;
+	}
+
+	/*
+	 * Check enough hugepages are available for the reservation.
+	 * Hand the pages back to the subpool if there are not
+	 */
+	ret = hugetlb_acct_memory(h, gbl_reserve);
+	if (ret < 0) {
+		/* put back original number of pages, chg */
+		(void)hugepage_subpool_put_pages(spool, chg);
+		goto out_err;
+	}
+
+	/*
+	 * Account for the reservations made. Shared mappings record regions
+	 * that have reservations as they are shared by multiple VMAs.
+	 * When the last VMA disappears, the region map says how much
+	 * the reservation was and the page cache tells how much of
+	 * the reservation was consumed. Private mappings are per-VMA and
+	 * only the consumed reservations are tracked. When the VMA
+	 * disappears, the original reservation is the VMA size and the
+	 * consumed reservations are stored in the map. Hence, nothing
+	 * else has to be done for private mappings here
+	 */
+	if (!vma || vma->vm_flags & VM_MAYSHARE) {
+		long add = region_add(resv_map, from, to);
+
+		if (unlikely(chg > add)) {
+			/*
+			 * pages in this range were added to the reserve
+			 * map between region_chg and region_add.  This
+			 * indicates a race with alloc_huge_page.  Adjust
+			 * the subpool and reserve counts modified above
+			 * based on the difference.
+			 */
+			long rsv_adjust;
+
+			rsv_adjust = hugepage_subpool_put_pages(spool,
+								chg - add);
+			hugetlb_acct_memory(h, -rsv_adjust);
+		}
+	}
+	return 0;
+out_err:
+	if (!vma || vma->vm_flags & VM_MAYSHARE)
+		region_abort(resv_map, from, to);
+	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
+		kref_put(&resv_map->refs, resv_map_release);
+	return ret;
+}
+
+long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
+								long freed)
+{
+	struct hstate *h = hstate_inode(inode);
+	struct resv_map *resv_map = inode_resv_map(inode);
+	long chg = 0;
+	struct hugepage_subpool *spool = subpool_inode(inode);
+	long gbl_reserve;
+
+	if (resv_map) {
+		chg = region_del(resv_map, start, end);
+		/*
+		 * region_del() can fail in the rare case where a region
+		 * must be split and another region descriptor can not be
+		 * allocated.  If end == LONG_MAX, it will not fail.
+		 */
+		if (chg < 0)
+			return chg;
+	}
+
+	spin_lock(&inode->i_lock);
+	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
+	spin_unlock(&inode->i_lock);
+
+	/*
+	 * If the subpool has a minimum size, the number of global
+	 * reservations to be released may be adjusted.
+	 */
+	gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
+	hugetlb_acct_memory(h, -gbl_reserve);
+
+	return 0;
+}
+
+#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
+static unsigned long page_table_shareable(struct vm_area_struct *svma,
+				struct vm_area_struct *vma,
+				unsigned long addr, pgoff_t idx)
+{
+	unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
+				svma->vm_start;
+	unsigned long sbase = saddr & PUD_MASK;
+	unsigned long s_end = sbase + PUD_SIZE;
+
+	/* Allow segments to share if only one is marked locked */
+	unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
+	unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
+
+	/*
+	 * match the virtual addresses, permission and the alignment of the
+	 * page table page.
+	 */
+	if (pmd_index(addr) != pmd_index(saddr) ||
+	    vm_flags != svm_flags ||
+	    sbase < svma->vm_start || svma->vm_end < s_end)
+		return 0;
+
+	return saddr;
+}
+
+static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
+{
+	unsigned long base = addr & PUD_MASK;
+	unsigned long end = base + PUD_SIZE;
+
+	/*
+	 * check on proper vm_flags and page table alignment
+	 */
+	if (vma->vm_flags & VM_MAYSHARE &&
+	    vma->vm_start <= base && end <= vma->vm_end)
+		return true;
+	return false;
+}
+
+/*
+ * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
+ * and returns the corresponding pte. While this is not necessary for the
+ * !shared pmd case because we can allocate the pmd later as well, it makes the
+ * code much cleaner. pmd allocation is essential for the shared case because
+ * pud has to be populated inside the same i_mmap_rwsem section - otherwise
+ * racing tasks could either miss the sharing (see huge_pte_offset) or select a
+ * bad pmd for sharing.
+ */
+pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
+{
+	struct vm_area_struct *vma = find_vma(mm, addr);
+	struct address_space *mapping = vma->vm_file->f_mapping;
+	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
+			vma->vm_pgoff;
+	struct vm_area_struct *svma;
+	unsigned long saddr;
+	pte_t *spte = NULL;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	if (!vma_shareable(vma, addr))
+		return (pte_t *)pmd_alloc(mm, pud, addr);
+
+	i_mmap_lock_write(mapping);
+	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
+		if (svma == vma)
+			continue;
+
+		saddr = page_table_shareable(svma, vma, addr, idx);
+		if (saddr) {
+			spte = huge_pte_offset(svma->vm_mm, saddr);
+			if (spte) {
+				get_page(virt_to_page(spte));
+				break;
+			}
+		}
+	}
+
+	if (!spte)
+		goto out;
+
+	ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte);
+	spin_lock(ptl);
+	if (pud_none(*pud)) {
+		pud_populate(mm, pud,
+				(pmd_t *)((unsigned long)spte & PAGE_MASK));
+		mm_inc_nr_pmds(mm);
+	} else {
+		put_page(virt_to_page(spte));
+	}
+	spin_unlock(ptl);
+out:
+	pte = (pte_t *)pmd_alloc(mm, pud, addr);
+	i_mmap_unlock_write(mapping);
+	return pte;
+}
+
+/*
+ * unmap huge page backed by shared pte.
+ *
+ * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
+ * indicated by page_count > 1, unmap is achieved by clearing pud and
+ * decrementing the ref count. If count == 1, the pte page is not shared.
+ *
+ * called with page table lock held.
+ *
+ * returns: 1 successfully unmapped a shared pte page
+ *	    0 the underlying pte page is not shared, or it is the last user
+ */
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+	pgd_t *pgd = pgd_offset(mm, *addr);
+	pud_t *pud = pud_offset(pgd, *addr);
+
+	BUG_ON(page_count(virt_to_page(ptep)) == 0);
+	if (page_count(virt_to_page(ptep)) == 1)
+		return 0;
+
+	pud_clear(pud);
+	put_page(virt_to_page(ptep));
+	mm_dec_nr_pmds(mm);
+	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
+	return 1;
+}
+#define want_pmd_share()	(1)
+#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
+pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
+{
+	return NULL;
+}
+
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+	return 0;
+}
+#define want_pmd_share()	(0)
+#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
+
+#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
+pte_t *huge_pte_alloc(struct mm_struct *mm,
+			unsigned long addr, unsigned long sz)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pte_t *pte = NULL;
+
+	pgd = pgd_offset(mm, addr);
+	pud = pud_alloc(mm, pgd, addr);
+	if (pud) {
+		if (sz == PUD_SIZE) {
+			pte = (pte_t *)pud;
+		} else {
+			BUG_ON(sz != PMD_SIZE);
+			if (want_pmd_share() && pud_none(*pud))
+				pte = huge_pmd_share(mm, addr, pud);
+			else
+				pte = (pte_t *)pmd_alloc(mm, pud, addr);
+		}
+	}
+	BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
+
+	return pte;
+}
+
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd = NULL;
+
+	pgd = pgd_offset(mm, addr);
+	if (pgd_present(*pgd)) {
+		pud = pud_offset(pgd, addr);
+		if (pud_present(*pud)) {
+			if (pud_huge(*pud))
+				return (pte_t *)pud;
+			pmd = pmd_offset(pud, addr);
+		}
+	}
+	return (pte_t *) pmd;
+}
+
+#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
+
+/*
+ * These functions are overwritable if your architecture needs its own
+ * behavior.
+ */
+struct page * __weak
+follow_huge_addr(struct mm_struct *mm, unsigned long address,
+			      int write)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+struct page * __weak
+follow_huge_pmd(struct mm_struct *mm, unsigned long address,
+		pmd_t *pmd, int flags)
+{
+	struct page *page = NULL;
+	spinlock_t *ptl;
+	pte_t pte;
+retry:
+	ptl = pmd_lockptr(mm, pmd);
+	spin_lock(ptl);
+	/*
+	 * make sure that the address range covered by this pmd is not
+	 * unmapped from other threads.
+	 */
+	if (!pmd_huge(*pmd))
+		goto out;
+	pte = huge_ptep_get((pte_t *)pmd);
+	if (pte_present(pte)) {
+		page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
+		if (flags & FOLL_GET)
+			get_page(page);
+	} else {
+		if (is_hugetlb_entry_migration(pte)) {
+			spin_unlock(ptl);
+			__migration_entry_wait(mm, (pte_t *)pmd, ptl);
+			goto retry;
+		}
+		/*
+		 * hwpoisoned entry is treated as no_page_table in
+		 * follow_page_mask().
+		 */
+	}
+out:
+	spin_unlock(ptl);
+	return page;
+}
+
+struct page * __weak
+follow_huge_pud(struct mm_struct *mm, unsigned long address,
+		pud_t *pud, int flags)
+{
+	if (flags & FOLL_GET)
+		return NULL;
+
+	return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
+}
+
+#ifdef CONFIG_MEMORY_FAILURE
+
+/*
+ * This function is called from memory failure code.
+ * Assume the caller holds page lock of the head page.
+ */
+int dequeue_hwpoisoned_huge_page(struct page *hpage)
+{
+	struct hstate *h = page_hstate(hpage);
+	int nid = page_to_nid(hpage);
+	int ret = -EBUSY;
+
+	spin_lock(&hugetlb_lock);
+	/*
+	 * Just checking !page_huge_active is not enough, because that could be
+	 * an isolated/hwpoisoned hugepage (which have >0 refcount).
+	 */
+	if (!page_huge_active(hpage) && !page_count(hpage)) {
+		/*
+		 * Hwpoisoned hugepage isn't linked to activelist or freelist,
+		 * but dangling hpage->lru can trigger list-debug warnings
+		 * (this happens when we call unpoison_memory() on it),
+		 * so let it point to itself with list_del_init().
+		 */
+		list_del_init(&hpage->lru);
+		set_page_refcounted(hpage);
+		h->free_huge_pages--;
+		h->free_huge_pages_node[nid]--;
+		ret = 0;
+	}
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+#endif
+
+bool isolate_huge_page(struct page *page, struct list_head *list)
+{
+	bool ret = true;
+
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+	spin_lock(&hugetlb_lock);
+	if (!page_huge_active(page) || !get_page_unless_zero(page)) {
+		ret = false;
+		goto unlock;
+	}
+	clear_page_huge_active(page);
+	list_move_tail(&page->lru, list);
+unlock:
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+
+void putback_active_hugepage(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+	spin_lock(&hugetlb_lock);
+	set_page_huge_active(page);
+	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
+	spin_unlock(&hugetlb_lock);
+	put_page(page);
+}
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
new file mode 100644
index 0000000..d8fb10d
--- /dev/null
+++ b/mm/hugetlb_cgroup.c
@@ -0,0 +1,423 @@
+/*
+ *
+ * Copyright IBM Corporation, 2012
+ * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ */
+
+#include <linux/cgroup.h>
+#include <linux/page_counter.h>
+#include <linux/slab.h>
+#include <linux/hugetlb.h>
+#include <linux/hugetlb_cgroup.h>
+
+struct hugetlb_cgroup {
+	struct cgroup_subsys_state css;
+	/*
+	 * the counter to account for hugepages from hugetlb.
+	 */
+	struct page_counter hugepage[HUGE_MAX_HSTATE];
+};
+
+#define MEMFILE_PRIVATE(x, val)	(((x) << 16) | (val))
+#define MEMFILE_IDX(val)	(((val) >> 16) & 0xffff)
+#define MEMFILE_ATTR(val)	((val) & 0xffff)
+
+static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
+
+static inline
+struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
+{
+	return s ? container_of(s, struct hugetlb_cgroup, css) : NULL;
+}
+
+static inline
+struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
+{
+	return hugetlb_cgroup_from_css(task_css(task, hugetlb_cgrp_id));
+}
+
+static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
+{
+	return (h_cg == root_h_cgroup);
+}
+
+static inline struct hugetlb_cgroup *
+parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
+{
+	return hugetlb_cgroup_from_css(h_cg->css.parent);
+}
+
+static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
+{
+	int idx;
+
+	for (idx = 0; idx < hugetlb_max_hstate; idx++) {
+		if (page_counter_read(&h_cg->hugepage[idx]))
+			return true;
+	}
+	return false;
+}
+
+static struct cgroup_subsys_state *
+hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
+	struct hugetlb_cgroup *h_cgroup;
+	int idx;
+
+	h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
+	if (!h_cgroup)
+		return ERR_PTR(-ENOMEM);
+
+	if (parent_h_cgroup) {
+		for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
+			page_counter_init(&h_cgroup->hugepage[idx],
+					  &parent_h_cgroup->hugepage[idx]);
+	} else {
+		root_h_cgroup = h_cgroup;
+		for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
+			page_counter_init(&h_cgroup->hugepage[idx], NULL);
+	}
+	return &h_cgroup->css;
+}
+
+static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
+{
+	struct hugetlb_cgroup *h_cgroup;
+
+	h_cgroup = hugetlb_cgroup_from_css(css);
+	kfree(h_cgroup);
+}
+
+
+/*
+ * Should be called with hugetlb_lock held.
+ * Since we are holding hugetlb_lock, pages cannot get moved from
+ * active list or uncharged from the cgroup, So no need to get
+ * page reference and test for page active here. This function
+ * cannot fail.
+ */
+static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
+				       struct page *page)
+{
+	unsigned int nr_pages;
+	struct page_counter *counter;
+	struct hugetlb_cgroup *page_hcg;
+	struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);
+
+	page_hcg = hugetlb_cgroup_from_page(page);
+	/*
+	 * We can have pages in active list without any cgroup
+	 * ie, hugepage with less than 3 pages. We can safely
+	 * ignore those pages.
+	 */
+	if (!page_hcg || page_hcg != h_cg)
+		goto out;
+
+	nr_pages = 1 << compound_order(page);
+	if (!parent) {
+		parent = root_h_cgroup;
+		/* root has no limit */
+		page_counter_charge(&parent->hugepage[idx], nr_pages);
+	}
+	counter = &h_cg->hugepage[idx];
+	/* Take the pages off the local counter */
+	page_counter_cancel(counter, nr_pages);
+
+	set_hugetlb_cgroup(page, parent);
+out:
+	return;
+}
+
+/*
+ * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
+ * the parent cgroup.
+ */
+static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
+{
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
+	struct hstate *h;
+	struct page *page;
+	int idx = 0;
+
+	do {
+		for_each_hstate(h) {
+			spin_lock(&hugetlb_lock);
+			list_for_each_entry(page, &h->hugepage_activelist, lru)
+				hugetlb_cgroup_move_parent(idx, h_cg, page);
+
+			spin_unlock(&hugetlb_lock);
+			idx++;
+		}
+		cond_resched();
+	} while (hugetlb_cgroup_have_usage(h_cg));
+}
+
+int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
+				 struct hugetlb_cgroup **ptr)
+{
+	int ret = 0;
+	struct page_counter *counter;
+	struct hugetlb_cgroup *h_cg = NULL;
+
+	if (hugetlb_cgroup_disabled())
+		goto done;
+	/*
+	 * We don't charge any cgroup if the compound page have less
+	 * than 3 pages.
+	 */
+	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
+		goto done;
+again:
+	rcu_read_lock();
+	h_cg = hugetlb_cgroup_from_task(current);
+	if (!css_tryget_online(&h_cg->css)) {
+		rcu_read_unlock();
+		goto again;
+	}
+	rcu_read_unlock();
+
+	if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages, &counter))
+		ret = -ENOMEM;
+	css_put(&h_cg->css);
+done:
+	*ptr = h_cg;
+	return ret;
+}
+
+/* Should be called with hugetlb_lock held */
+void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
+				  struct hugetlb_cgroup *h_cg,
+				  struct page *page)
+{
+	if (hugetlb_cgroup_disabled() || !h_cg)
+		return;
+
+	set_hugetlb_cgroup(page, h_cg);
+	return;
+}
+
+/*
+ * Should be called with hugetlb_lock held
+ */
+void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
+				  struct page *page)
+{
+	struct hugetlb_cgroup *h_cg;
+
+	if (hugetlb_cgroup_disabled())
+		return;
+	lockdep_assert_held(&hugetlb_lock);
+	h_cg = hugetlb_cgroup_from_page(page);
+	if (unlikely(!h_cg))
+		return;
+	set_hugetlb_cgroup(page, NULL);
+	page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
+	return;
+}
+
+void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
+				    struct hugetlb_cgroup *h_cg)
+{
+	if (hugetlb_cgroup_disabled() || !h_cg)
+		return;
+
+	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
+		return;
+
+	page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
+	return;
+}
+
+enum {
+	RES_USAGE,
+	RES_LIMIT,
+	RES_MAX_USAGE,
+	RES_FAILCNT,
+};
+
+static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
+				   struct cftype *cft)
+{
+	struct page_counter *counter;
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
+
+	counter = &h_cg->hugepage[MEMFILE_IDX(cft->private)];
+
+	switch (MEMFILE_ATTR(cft->private)) {
+	case RES_USAGE:
+		return (u64)page_counter_read(counter) * PAGE_SIZE;
+	case RES_LIMIT:
+		return (u64)counter->limit * PAGE_SIZE;
+	case RES_MAX_USAGE:
+		return (u64)counter->watermark * PAGE_SIZE;
+	case RES_FAILCNT:
+		return counter->failcnt;
+	default:
+		BUG();
+	}
+}
+
+static DEFINE_MUTEX(hugetlb_limit_mutex);
+
+static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
+				    char *buf, size_t nbytes, loff_t off)
+{
+	int ret, idx;
+	unsigned long nr_pages;
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
+
+	if (hugetlb_cgroup_is_root(h_cg)) /* Can't set limit on root */
+		return -EINVAL;
+
+	buf = strstrip(buf);
+	ret = page_counter_memparse(buf, "-1", &nr_pages);
+	if (ret)
+		return ret;
+
+	idx = MEMFILE_IDX(of_cft(of)->private);
+
+	switch (MEMFILE_ATTR(of_cft(of)->private)) {
+	case RES_LIMIT:
+		mutex_lock(&hugetlb_limit_mutex);
+		ret = page_counter_limit(&h_cg->hugepage[idx], nr_pages);
+		mutex_unlock(&hugetlb_limit_mutex);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	return ret ?: nbytes;
+}
+
+static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
+				    char *buf, size_t nbytes, loff_t off)
+{
+	int ret = 0;
+	struct page_counter *counter;
+	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
+
+	counter = &h_cg->hugepage[MEMFILE_IDX(of_cft(of)->private)];
+
+	switch (MEMFILE_ATTR(of_cft(of)->private)) {
+	case RES_MAX_USAGE:
+		page_counter_reset_watermark(counter);
+		break;
+	case RES_FAILCNT:
+		counter->failcnt = 0;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	return ret ?: nbytes;
+}
+
+static char *mem_fmt(char *buf, int size, unsigned long hsize)
+{
+	if (hsize >= (1UL << 30))
+		snprintf(buf, size, "%luGB", hsize >> 30);
+	else if (hsize >= (1UL << 20))
+		snprintf(buf, size, "%luMB", hsize >> 20);
+	else
+		snprintf(buf, size, "%luKB", hsize >> 10);
+	return buf;
+}
+
+static void __init __hugetlb_cgroup_file_init(int idx)
+{
+	char buf[32];
+	struct cftype *cft;
+	struct hstate *h = &hstates[idx];
+
+	/* format the size */
+	mem_fmt(buf, 32, huge_page_size(h));
+
+	/* Add the limit file */
+	cft = &h->cgroup_files[0];
+	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
+	cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
+	cft->read_u64 = hugetlb_cgroup_read_u64;
+	cft->write = hugetlb_cgroup_write;
+
+	/* Add the usage file */
+	cft = &h->cgroup_files[1];
+	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
+	cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
+	cft->read_u64 = hugetlb_cgroup_read_u64;
+
+	/* Add the MAX usage file */
+	cft = &h->cgroup_files[2];
+	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
+	cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
+	cft->write = hugetlb_cgroup_reset;
+	cft->read_u64 = hugetlb_cgroup_read_u64;
+
+	/* Add the failcntfile */
+	cft = &h->cgroup_files[3];
+	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
+	cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
+	cft->write = hugetlb_cgroup_reset;
+	cft->read_u64 = hugetlb_cgroup_read_u64;
+
+	/* NULL terminate the last cft */
+	cft = &h->cgroup_files[4];
+	memset(cft, 0, sizeof(*cft));
+
+	WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
+					  h->cgroup_files));
+}
+
+void __init hugetlb_cgroup_file_init(void)
+{
+	struct hstate *h;
+
+	for_each_hstate(h) {
+		/*
+		 * Add cgroup control files only if the huge page consists
+		 * of more than two normal pages. This is because we use
+		 * page[2].private for storing cgroup details.
+		 */
+		if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
+			__hugetlb_cgroup_file_init(hstate_index(h));
+	}
+}
+
+/*
+ * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
+ * when we migrate hugepages
+ */
+void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
+{
+	struct hugetlb_cgroup *h_cg;
+	struct hstate *h = page_hstate(oldhpage);
+
+	if (hugetlb_cgroup_disabled())
+		return;
+
+	VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
+	spin_lock(&hugetlb_lock);
+	h_cg = hugetlb_cgroup_from_page(oldhpage);
+	set_hugetlb_cgroup(oldhpage, NULL);
+
+	/* move the h_cg details to new cgroup */
+	set_hugetlb_cgroup(newhpage, h_cg);
+	list_move(&newhpage->lru, &h->hugepage_activelist);
+	spin_unlock(&hugetlb_lock);
+	return;
+}
+
+struct cgroup_subsys hugetlb_cgrp_subsys = {
+	.css_alloc	= hugetlb_cgroup_css_alloc,
+	.css_offline	= hugetlb_cgroup_css_offline,
+	.css_free	= hugetlb_cgroup_css_free,
+};
diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
new file mode 100644
index 0000000..9d26fd9
--- /dev/null
+++ b/mm/hwpoison-inject.c
@@ -0,0 +1,141 @@
+/* Inject a hwpoison memory failure on a arbitrary pfn */
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/hugetlb.h>
+#include "internal.h"
+
+static struct dentry *hwpoison_dir;
+
+static int hwpoison_inject(void *data, u64 val)
+{
+	unsigned long pfn = val;
+	struct page *p;
+	struct page *hpage;
+	int err;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!pfn_valid(pfn))
+		return -ENXIO;
+
+	p = pfn_to_page(pfn);
+	hpage = compound_head(p);
+	/*
+	 * This implies unable to support free buddy pages.
+	 */
+	if (!get_hwpoison_page(p))
+		return 0;
+
+	if (!hwpoison_filter_enable)
+		goto inject;
+
+	if (!PageLRU(hpage) && !PageHuge(p))
+		shake_page(hpage, 0);
+	/*
+	 * This implies unable to support non-LRU pages.
+	 */
+	if (!PageLRU(hpage) && !PageHuge(p))
+		goto put_out;
+
+	/*
+	 * do a racy check with elevated page count, to make sure PG_hwpoison
+	 * will only be set for the targeted owner (or on a free page).
+	 * memory_failure() will redo the check reliably inside page lock.
+	 */
+	err = hwpoison_filter(hpage);
+	if (err)
+		goto put_out;
+
+inject:
+	pr_info("Injecting memory failure at pfn %#lx\n", pfn);
+	return memory_failure(pfn, 18, MF_COUNT_INCREASED);
+put_out:
+	put_hwpoison_page(p);
+	return 0;
+}
+
+static int hwpoison_unpoison(void *data, u64 val)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	return unpoison_memory(val);
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
+DEFINE_SIMPLE_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");
+
+static void pfn_inject_exit(void)
+{
+	debugfs_remove_recursive(hwpoison_dir);
+}
+
+static int pfn_inject_init(void)
+{
+	struct dentry *dentry;
+
+	hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
+	if (hwpoison_dir == NULL)
+		return -ENOMEM;
+
+	/*
+	 * Note that the below poison/unpoison interfaces do not involve
+	 * hardware status change, hence do not require hardware support.
+	 * They are mainly for testing hwpoison in software level.
+	 */
+	dentry = debugfs_create_file("corrupt-pfn", 0200, hwpoison_dir,
+					  NULL, &hwpoison_fops);
+	if (!dentry)
+		goto fail;
+
+	dentry = debugfs_create_file("unpoison-pfn", 0200, hwpoison_dir,
+				     NULL, &unpoison_fops);
+	if (!dentry)
+		goto fail;
+
+	dentry = debugfs_create_u32("corrupt-filter-enable", 0600,
+				    hwpoison_dir, &hwpoison_filter_enable);
+	if (!dentry)
+		goto fail;
+
+	dentry = debugfs_create_u32("corrupt-filter-dev-major", 0600,
+				    hwpoison_dir, &hwpoison_filter_dev_major);
+	if (!dentry)
+		goto fail;
+
+	dentry = debugfs_create_u32("corrupt-filter-dev-minor", 0600,
+				    hwpoison_dir, &hwpoison_filter_dev_minor);
+	if (!dentry)
+		goto fail;
+
+	dentry = debugfs_create_u64("corrupt-filter-flags-mask", 0600,
+				    hwpoison_dir, &hwpoison_filter_flags_mask);
+	if (!dentry)
+		goto fail;
+
+	dentry = debugfs_create_u64("corrupt-filter-flags-value", 0600,
+				    hwpoison_dir, &hwpoison_filter_flags_value);
+	if (!dentry)
+		goto fail;
+
+#ifdef CONFIG_MEMCG
+	dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
+				    hwpoison_dir, &hwpoison_filter_memcg);
+	if (!dentry)
+		goto fail;
+#endif
+
+	return 0;
+fail:
+	pfn_inject_exit();
+	return -ENOMEM;
+}
+
+module_init(pfn_inject_init);
+module_exit(pfn_inject_exit);
+MODULE_LICENSE("GPL");
diff --git a/mm/init-mm.c b/mm/init-mm.c
new file mode 100644
index 0000000..975e49f
--- /dev/null
+++ b/mm/init-mm.c
@@ -0,0 +1,27 @@
+#include <linux/mm_types.h>
+#include <linux/rbtree.h>
+#include <linux/rwsem.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/cpumask.h>
+
+#include <linux/atomic.h>
+#include <linux/user_namespace.h>
+#include <asm/pgtable.h>
+#include <asm/mmu.h>
+
+#ifndef INIT_MM_CONTEXT
+#define INIT_MM_CONTEXT(name)
+#endif
+
+struct mm_struct init_mm = {
+	.mm_rb		= RB_ROOT,
+	.pgd		= swapper_pg_dir,
+	.mm_users	= ATOMIC_INIT(2),
+	.mm_count	= ATOMIC_INIT(1),
+	.mmap_sem	= __RWSEM_INITIALIZER(init_mm.mmap_sem),
+	.page_table_lock =  __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
+	.mmlist		= LIST_HEAD_INIT(init_mm.mmlist),
+	.user_ns	= &init_user_ns,
+	INIT_MM_CONTEXT(init_mm)
+};
diff --git a/mm/internal.h b/mm/internal.h
new file mode 100644
index 0000000..f63f439
--- /dev/null
+++ b/mm/internal.h
@@ -0,0 +1,468 @@
+/* internal.h: mm/ internal definitions
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#ifndef __MM_INTERNAL_H
+#define __MM_INTERNAL_H
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+
+/*
+ * The set of flags that only affect watermark checking and reclaim
+ * behaviour. This is used by the MM to obey the caller constraints
+ * about IO, FS and watermark checking while ignoring placement
+ * hints such as HIGHMEM usage.
+ */
+#define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\
+			__GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
+			__GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\
+			__GFP_ATOMIC)
+
+/* The GFP flags allowed during early boot */
+#define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS))
+
+/* Control allocation cpuset and node placement constraints */
+#define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE)
+
+/* Do not use these with a slab allocator */
+#define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK)
+
+void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
+		unsigned long floor, unsigned long ceiling);
+
+static inline void set_page_count(struct page *page, int v)
+{
+	atomic_set(&page->_count, v);
+}
+
+extern int __do_page_cache_readahead(struct address_space *mapping,
+		struct file *filp, pgoff_t offset, unsigned long nr_to_read,
+		unsigned long lookahead_size);
+
+/*
+ * Submit IO for the read-ahead request in file_ra_state.
+ */
+static inline unsigned long ra_submit(struct file_ra_state *ra,
+		struct address_space *mapping, struct file *filp)
+{
+	return __do_page_cache_readahead(mapping, filp,
+					ra->start, ra->size, ra->async_size);
+}
+
+/*
+ * Turn a non-refcounted page (->_count == 0) into refcounted with
+ * a count of one.
+ */
+static inline void set_page_refcounted(struct page *page)
+{
+	VM_BUG_ON_PAGE(PageTail(page), page);
+	VM_BUG_ON_PAGE(atomic_read(&page->_count), page);
+	set_page_count(page, 1);
+}
+
+static inline void __get_page_tail_foll(struct page *page,
+					bool get_page_head)
+{
+	/*
+	 * If we're getting a tail page, the elevated page->_count is
+	 * required only in the head page and we will elevate the head
+	 * page->_count and tail page->_mapcount.
+	 *
+	 * We elevate page_tail->_mapcount for tail pages to force
+	 * page_tail->_count to be zero at all times to avoid getting
+	 * false positives from get_page_unless_zero() with
+	 * speculative page access (like in
+	 * page_cache_get_speculative()) on tail pages.
+	 */
+	VM_BUG_ON_PAGE(atomic_read(&compound_head(page)->_count) <= 0, page);
+	if (get_page_head)
+		atomic_inc(&compound_head(page)->_count);
+	get_huge_page_tail(page);
+}
+
+/*
+ * This is meant to be called as the FOLL_GET operation of
+ * follow_page() and it must be called while holding the proper PT
+ * lock while the pte (or pmd_trans_huge) is still mapping the page.
+ */
+static inline void get_page_foll(struct page *page)
+{
+	if (unlikely(PageTail(page)))
+		/*
+		 * This is safe only because
+		 * __split_huge_page_refcount() can't run under
+		 * get_page_foll() because we hold the proper PT lock.
+		 */
+		__get_page_tail_foll(page, true);
+	else {
+		/*
+		 * Getting a normal page or the head of a compound page
+		 * requires to already have an elevated page->_count.
+		 */
+		VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page);
+		atomic_inc(&page->_count);
+	}
+}
+
+extern unsigned long highest_memmap_pfn;
+
+/*
+ * in mm/vmscan.c:
+ */
+extern int isolate_lru_page(struct page *page);
+extern void putback_lru_page(struct page *page);
+extern bool zone_reclaimable(struct zone *zone);
+
+/*
+ * in mm/rmap.c:
+ */
+extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address);
+
+/*
+ * in mm/page_alloc.c
+ */
+
+/*
+ * Structure for holding the mostly immutable allocation parameters passed
+ * between functions involved in allocations, including the alloc_pages*
+ * family of functions.
+ *
+ * nodemask, migratetype and high_zoneidx are initialized only once in
+ * __alloc_pages_nodemask() and then never change.
+ *
+ * zonelist, preferred_zone and classzone_idx are set first in
+ * __alloc_pages_nodemask() for the fast path, and might be later changed
+ * in __alloc_pages_slowpath(). All other functions pass the whole strucure
+ * by a const pointer.
+ */
+struct alloc_context {
+	struct zonelist *zonelist;
+	nodemask_t *nodemask;
+	struct zone *preferred_zone;
+	int classzone_idx;
+	int migratetype;
+	enum zone_type high_zoneidx;
+	bool spread_dirty_pages;
+};
+
+/*
+ * Locate the struct page for both the matching buddy in our
+ * pair (buddy1) and the combined O(n+1) page they form (page).
+ *
+ * 1) Any buddy B1 will have an order O twin B2 which satisfies
+ * the following equation:
+ *     B2 = B1 ^ (1 << O)
+ * For example, if the starting buddy (buddy2) is #8 its order
+ * 1 buddy is #10:
+ *     B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
+ *
+ * 2) Any buddy B will have an order O+1 parent P which
+ * satisfies the following equation:
+ *     P = B & ~(1 << O)
+ *
+ * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
+ */
+static inline unsigned long
+__find_buddy_index(unsigned long page_idx, unsigned int order)
+{
+	return page_idx ^ (1 << order);
+}
+
+extern int __isolate_free_page(struct page *page, unsigned int order);
+extern void __free_pages_bootmem(struct page *page, unsigned long pfn,
+					unsigned int order);
+extern void prep_compound_page(struct page *page, unsigned int order);
+#ifdef CONFIG_MEMORY_FAILURE
+extern bool is_free_buddy_page(struct page *page);
+#endif
+extern int user_min_free_kbytes;
+
+#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+
+/*
+ * in mm/compaction.c
+ */
+/*
+ * compact_control is used to track pages being migrated and the free pages
+ * they are being migrated to during memory compaction. The free_pfn starts
+ * at the end of a zone and migrate_pfn begins at the start. Movable pages
+ * are moved to the end of a zone during a compaction run and the run
+ * completes when free_pfn <= migrate_pfn
+ */
+struct compact_control {
+	struct list_head freepages;	/* List of free pages to migrate to */
+	struct list_head migratepages;	/* List of pages being migrated */
+	unsigned long nr_freepages;	/* Number of isolated free pages */
+	unsigned long nr_migratepages;	/* Number of pages to migrate */
+	unsigned long free_pfn;		/* isolate_freepages search base */
+	unsigned long migrate_pfn;	/* isolate_migratepages search base */
+	unsigned long last_migrated_pfn;/* Not yet flushed page being freed */
+	enum migrate_mode mode;		/* Async or sync migration mode */
+	bool ignore_skip_hint;		/* Scan blocks even if marked skip */
+	int order;			/* order a direct compactor needs */
+	const gfp_t gfp_mask;		/* gfp mask of a direct compactor */
+	const int alloc_flags;		/* alloc flags of a direct compactor */
+	const int classzone_idx;	/* zone index of a direct compactor */
+	struct zone *zone;
+	int contended;			/* Signal need_sched() or lock
+					 * contention detected during
+					 * compaction
+					 */
+};
+
+unsigned long
+isolate_freepages_range(struct compact_control *cc,
+			unsigned long start_pfn, unsigned long end_pfn);
+unsigned long
+isolate_migratepages_range(struct compact_control *cc,
+			   unsigned long low_pfn, unsigned long end_pfn);
+int find_suitable_fallback(struct free_area *area, unsigned int order,
+			int migratetype, bool only_stealable, bool *can_steal);
+
+#endif
+
+/*
+ * This function returns the order of a free page in the buddy system. In
+ * general, page_zone(page)->lock must be held by the caller to prevent the
+ * page from being allocated in parallel and returning garbage as the order.
+ * If a caller does not hold page_zone(page)->lock, it must guarantee that the
+ * page cannot be allocated or merged in parallel. Alternatively, it must
+ * handle invalid values gracefully, and use page_order_unsafe() below.
+ */
+static inline unsigned int page_order(struct page *page)
+{
+	/* PageBuddy() must be checked by the caller */
+	return page_private(page);
+}
+
+/*
+ * Like page_order(), but for callers who cannot afford to hold the zone lock.
+ * PageBuddy() should be checked first by the caller to minimize race window,
+ * and invalid values must be handled gracefully.
+ *
+ * READ_ONCE is used so that if the caller assigns the result into a local
+ * variable and e.g. tests it for valid range before using, the compiler cannot
+ * decide to remove the variable and inline the page_private(page) multiple
+ * times, potentially observing different values in the tests and the actual
+ * use of the result.
+ */
+#define page_order_unsafe(page)		READ_ONCE(page_private(page))
+
+static inline bool is_cow_mapping(vm_flags_t flags)
+{
+	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+}
+
+/* mm/util.c */
+void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct vm_area_struct *prev, struct rb_node *rb_parent);
+
+#ifdef CONFIG_MMU
+extern long populate_vma_page_range(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end, int *nonblocking);
+extern void munlock_vma_pages_range(struct vm_area_struct *vma,
+			unsigned long start, unsigned long end);
+static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
+{
+	munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
+}
+
+/*
+ * must be called with vma's mmap_sem held for read or write, and page locked.
+ */
+extern void mlock_vma_page(struct page *page);
+extern unsigned int munlock_vma_page(struct page *page);
+
+/*
+ * Clear the page's PageMlocked().  This can be useful in a situation where
+ * we want to unconditionally remove a page from the pagecache -- e.g.,
+ * on truncation or freeing.
+ *
+ * It is legal to call this function for any page, mlocked or not.
+ * If called for a page that is still mapped by mlocked vmas, all we do
+ * is revert to lazy LRU behaviour -- semantics are not broken.
+ */
+extern void clear_page_mlock(struct page *page);
+
+/*
+ * mlock_migrate_page - called only from migrate_misplaced_transhuge_page()
+ * (because that does not go through the full procedure of migration ptes):
+ * to migrate the Mlocked page flag; update statistics.
+ */
+static inline void mlock_migrate_page(struct page *newpage, struct page *page)
+{
+	if (TestClearPageMlocked(page)) {
+		int nr_pages = hpage_nr_pages(page);
+
+		/* Holding pmd lock, no change in irq context: __mod is safe */
+		__mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
+		SetPageMlocked(newpage);
+		__mod_zone_page_state(page_zone(newpage), NR_MLOCK, nr_pages);
+	}
+}
+
+extern pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+extern unsigned long vma_address(struct page *page,
+				 struct vm_area_struct *vma);
+#endif
+#else /* !CONFIG_MMU */
+static inline void clear_page_mlock(struct page *page) { }
+static inline void mlock_vma_page(struct page *page) { }
+static inline void mlock_migrate_page(struct page *new, struct page *old) { }
+
+#endif /* !CONFIG_MMU */
+
+/*
+ * Return the mem_map entry representing the 'offset' subpage within
+ * the maximally aligned gigantic page 'base'.  Handle any discontiguity
+ * in the mem_map at MAX_ORDER_NR_PAGES boundaries.
+ */
+static inline struct page *mem_map_offset(struct page *base, int offset)
+{
+	if (unlikely(offset >= MAX_ORDER_NR_PAGES))
+		return nth_page(base, offset);
+	return base + offset;
+}
+
+/*
+ * Iterator over all subpages within the maximally aligned gigantic
+ * page 'base'.  Handle any discontiguity in the mem_map.
+ */
+static inline struct page *mem_map_next(struct page *iter,
+						struct page *base, int offset)
+{
+	if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) {
+		unsigned long pfn = page_to_pfn(base) + offset;
+		if (!pfn_valid(pfn))
+			return NULL;
+		return pfn_to_page(pfn);
+	}
+	return iter + 1;
+}
+
+/*
+ * FLATMEM and DISCONTIGMEM configurations use alloc_bootmem_node,
+ * so all functions starting at paging_init should be marked __init
+ * in those cases. SPARSEMEM, however, allows for memory hotplug,
+ * and alloc_bootmem_node is not used.
+ */
+#ifdef CONFIG_SPARSEMEM
+#define __paginginit __meminit
+#else
+#define __paginginit __init
+#endif
+
+/* Memory initialisation debug and verification */
+enum mminit_level {
+	MMINIT_WARNING,
+	MMINIT_VERIFY,
+	MMINIT_TRACE
+};
+
+#ifdef CONFIG_DEBUG_MEMORY_INIT
+
+extern int mminit_loglevel;
+
+#define mminit_dprintk(level, prefix, fmt, arg...) \
+do { \
+	if (level < mminit_loglevel) { \
+		if (level <= MMINIT_WARNING) \
+			printk(KERN_WARNING "mminit::" prefix " " fmt, ##arg); \
+		else \
+			printk(KERN_DEBUG "mminit::" prefix " " fmt, ##arg); \
+	} \
+} while (0)
+
+extern void mminit_verify_pageflags_layout(void);
+extern void mminit_verify_zonelist(void);
+#else
+
+static inline void mminit_dprintk(enum mminit_level level,
+				const char *prefix, const char *fmt, ...)
+{
+}
+
+static inline void mminit_verify_pageflags_layout(void)
+{
+}
+
+static inline void mminit_verify_zonelist(void)
+{
+}
+#endif /* CONFIG_DEBUG_MEMORY_INIT */
+
+/* mminit_validate_memmodel_limits is independent of CONFIG_DEBUG_MEMORY_INIT */
+#if defined(CONFIG_SPARSEMEM)
+extern void mminit_validate_memmodel_limits(unsigned long *start_pfn,
+				unsigned long *end_pfn);
+#else
+static inline void mminit_validate_memmodel_limits(unsigned long *start_pfn,
+				unsigned long *end_pfn)
+{
+}
+#endif /* CONFIG_SPARSEMEM */
+
+#define ZONE_RECLAIM_NOSCAN	-2
+#define ZONE_RECLAIM_FULL	-1
+#define ZONE_RECLAIM_SOME	0
+#define ZONE_RECLAIM_SUCCESS	1
+
+extern int hwpoison_filter(struct page *p);
+
+extern u32 hwpoison_filter_dev_major;
+extern u32 hwpoison_filter_dev_minor;
+extern u64 hwpoison_filter_flags_mask;
+extern u64 hwpoison_filter_flags_value;
+extern u64 hwpoison_filter_memcg;
+extern u32 hwpoison_filter_enable;
+
+extern unsigned long vm_mmap_pgoff(struct file *, unsigned long,
+        unsigned long, unsigned long,
+        unsigned long, unsigned long);
+
+extern void set_pageblock_order(void);
+unsigned long reclaim_clean_pages_from_list(struct zone *zone,
+					    struct list_head *page_list);
+/* The ALLOC_WMARK bits are used as an index to zone->watermark */
+#define ALLOC_WMARK_MIN		WMARK_MIN
+#define ALLOC_WMARK_LOW		WMARK_LOW
+#define ALLOC_WMARK_HIGH	WMARK_HIGH
+#define ALLOC_NO_WATERMARKS	0x04 /* don't check watermarks at all */
+
+/* Mask to get the watermark bits */
+#define ALLOC_WMARK_MASK	(ALLOC_NO_WATERMARKS-1)
+
+#define ALLOC_HARDER		0x10 /* try to alloc harder */
+#define ALLOC_HIGH		0x20 /* __GFP_HIGH set */
+#define ALLOC_CPUSET		0x40 /* check for correct cpuset */
+#define ALLOC_CMA		0x80 /* allow allocations from CMA areas */
+#define ALLOC_FAIR		0x100 /* fair zone allocation */
+
+enum ttu_flags;
+struct tlbflush_unmap_batch;
+
+#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
+void try_to_unmap_flush(void);
+void try_to_unmap_flush_dirty(void);
+void flush_tlb_batched_pending(struct mm_struct *mm);
+#else
+static inline void try_to_unmap_flush(void)
+{
+}
+static inline void try_to_unmap_flush_dirty(void)
+{
+}
+static inline void flush_tlb_batched_pending(struct mm_struct *mm)
+{
+}
+#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
+#endif	/* __MM_INTERNAL_H */
diff --git a/mm/interval_tree.c b/mm/interval_tree.c
new file mode 100644
index 0000000..f2c2492
--- /dev/null
+++ b/mm/interval_tree.c
@@ -0,0 +1,112 @@
+/*
+ * mm/interval_tree.c - interval tree for mapping->i_mmap
+ *
+ * Copyright (C) 2012, Michel Lespinasse <walken@google.com>
+ *
+ * This file is released under the GPL v2.
+ */
+
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/rmap.h>
+#include <linux/interval_tree_generic.h>
+
+static inline unsigned long vma_start_pgoff(struct vm_area_struct *v)
+{
+	return v->vm_pgoff;
+}
+
+static inline unsigned long vma_last_pgoff(struct vm_area_struct *v)
+{
+	return v->vm_pgoff + ((v->vm_end - v->vm_start) >> PAGE_SHIFT) - 1;
+}
+
+INTERVAL_TREE_DEFINE(struct vm_area_struct, shared.rb,
+		     unsigned long, shared.rb_subtree_last,
+		     vma_start_pgoff, vma_last_pgoff,, vma_interval_tree)
+
+/* Insert node immediately after prev in the interval tree */
+void vma_interval_tree_insert_after(struct vm_area_struct *node,
+				    struct vm_area_struct *prev,
+				    struct rb_root *root)
+{
+	struct rb_node **link;
+	struct vm_area_struct *parent;
+	unsigned long last = vma_last_pgoff(node);
+
+	VM_BUG_ON_VMA(vma_start_pgoff(node) != vma_start_pgoff(prev), node);
+
+	if (!prev->shared.rb.rb_right) {
+		parent = prev;
+		link = &prev->shared.rb.rb_right;
+	} else {
+		parent = rb_entry(prev->shared.rb.rb_right,
+				  struct vm_area_struct, shared.rb);
+		if (parent->shared.rb_subtree_last < last)
+			parent->shared.rb_subtree_last = last;
+		while (parent->shared.rb.rb_left) {
+			parent = rb_entry(parent->shared.rb.rb_left,
+				struct vm_area_struct, shared.rb);
+			if (parent->shared.rb_subtree_last < last)
+				parent->shared.rb_subtree_last = last;
+		}
+		link = &parent->shared.rb.rb_left;
+	}
+
+	node->shared.rb_subtree_last = last;
+	rb_link_node(&node->shared.rb, &parent->shared.rb, link);
+	rb_insert_augmented(&node->shared.rb, root,
+			    &vma_interval_tree_augment);
+}
+
+static inline unsigned long avc_start_pgoff(struct anon_vma_chain *avc)
+{
+	return vma_start_pgoff(avc->vma);
+}
+
+static inline unsigned long avc_last_pgoff(struct anon_vma_chain *avc)
+{
+	return vma_last_pgoff(avc->vma);
+}
+
+INTERVAL_TREE_DEFINE(struct anon_vma_chain, rb, unsigned long, rb_subtree_last,
+		     avc_start_pgoff, avc_last_pgoff,
+		     static inline, __anon_vma_interval_tree)
+
+void anon_vma_interval_tree_insert(struct anon_vma_chain *node,
+				   struct rb_root *root)
+{
+#ifdef CONFIG_DEBUG_VM_RB
+	node->cached_vma_start = avc_start_pgoff(node);
+	node->cached_vma_last = avc_last_pgoff(node);
+#endif
+	__anon_vma_interval_tree_insert(node, root);
+}
+
+void anon_vma_interval_tree_remove(struct anon_vma_chain *node,
+				   struct rb_root *root)
+{
+	__anon_vma_interval_tree_remove(node, root);
+}
+
+struct anon_vma_chain *
+anon_vma_interval_tree_iter_first(struct rb_root *root,
+				  unsigned long first, unsigned long last)
+{
+	return __anon_vma_interval_tree_iter_first(root, first, last);
+}
+
+struct anon_vma_chain *
+anon_vma_interval_tree_iter_next(struct anon_vma_chain *node,
+				 unsigned long first, unsigned long last)
+{
+	return __anon_vma_interval_tree_iter_next(node, first, last);
+}
+
+#ifdef CONFIG_DEBUG_VM_RB
+void anon_vma_interval_tree_verify(struct anon_vma_chain *node)
+{
+	WARN_ON_ONCE(node->cached_vma_start != avc_start_pgoff(node));
+	WARN_ON_ONCE(node->cached_vma_last != avc_last_pgoff(node));
+}
+#endif
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
new file mode 100644
index 0000000..6471014
--- /dev/null
+++ b/mm/kasan/Makefile
@@ -0,0 +1,8 @@
+KASAN_SANITIZE := n
+
+CFLAGS_REMOVE_kasan.o = -pg
+# Function splitter causes unnecessary splits in __asan_load1/__asan_store1
+# see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
+CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
+
+obj-y := kasan.o report.o kasan_init.o
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
new file mode 100644
index 0000000..bc0a8d8
--- /dev/null
+++ b/mm/kasan/kasan.c
@@ -0,0 +1,552 @@
+/*
+ * This file contains shadow memory manipulation code.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * Some code borrowed from https://github.com/xairy/kasan-prototype by
+ *        Andrey Konovalov <adech.fo@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/kmemleak.h>
+#include <linux/memblock.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <linux/kasan.h>
+
+#include "kasan.h"
+#include "../slab.h"
+
+/*
+ * Poisons the shadow memory for 'size' bytes starting from 'addr'.
+ * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
+ */
+static void kasan_poison_shadow(const void *address, size_t size, u8 value)
+{
+	void *shadow_start, *shadow_end;
+
+	shadow_start = kasan_mem_to_shadow(address);
+	shadow_end = kasan_mem_to_shadow(address + size);
+
+	memset(shadow_start, value, shadow_end - shadow_start);
+}
+
+void kasan_unpoison_shadow(const void *address, size_t size)
+{
+	kasan_poison_shadow(address, size, 0);
+
+	if (size & KASAN_SHADOW_MASK) {
+		u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
+		*shadow = size & KASAN_SHADOW_MASK;
+	}
+}
+
+
+/*
+ * All functions below always inlined so compiler could
+ * perform better optimizations in each of __asan_loadX/__assn_storeX
+ * depending on memory access size X.
+ */
+
+static __always_inline bool memory_is_poisoned_1(unsigned long addr)
+{
+	s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(shadow_value)) {
+		s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
+		return unlikely(last_accessible_byte >= shadow_value);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_2(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		if (memory_is_poisoned_1(addr + 1))
+			return true;
+
+		/*
+		 * If single shadow byte covers 2-byte access, we don't
+		 * need to do anything more. Otherwise, test the first
+		 * shadow byte.
+		 */
+		if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
+			return false;
+
+		return unlikely(*(u8 *)shadow_addr);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_4(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		if (memory_is_poisoned_1(addr + 3))
+			return true;
+
+		/*
+		 * If single shadow byte covers 4-byte access, we don't
+		 * need to do anything more. Otherwise, test the first
+		 * shadow byte.
+		 */
+		if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
+			return false;
+
+		return unlikely(*(u8 *)shadow_addr);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_8(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		if (memory_is_poisoned_1(addr + 7))
+			return true;
+
+		/*
+		 * If single shadow byte covers 8-byte access, we don't
+		 * need to do anything more. Otherwise, test the first
+		 * shadow byte.
+		 */
+		if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
+			return false;
+
+		return unlikely(*(u8 *)shadow_addr);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_16(unsigned long addr)
+{
+	u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		u16 shadow_first_bytes = *(u16 *)shadow_addr;
+
+		if (unlikely(shadow_first_bytes))
+			return true;
+
+		/*
+		 * If two shadow bytes covers 16-byte access, we don't
+		 * need to do anything more. Otherwise, test the last
+		 * shadow byte.
+		 */
+		if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
+			return false;
+
+		return memory_is_poisoned_1(addr + 15);
+	}
+
+	return false;
+}
+
+static __always_inline unsigned long bytes_is_zero(const u8 *start,
+					size_t size)
+{
+	while (size) {
+		if (unlikely(*start))
+			return (unsigned long)start;
+		start++;
+		size--;
+	}
+
+	return 0;
+}
+
+static __always_inline unsigned long memory_is_zero(const void *start,
+						const void *end)
+{
+	unsigned int words;
+	unsigned long ret;
+	unsigned int prefix = (unsigned long)start % 8;
+
+	if (end - start <= 16)
+		return bytes_is_zero(start, end - start);
+
+	if (prefix) {
+		prefix = 8 - prefix;
+		ret = bytes_is_zero(start, prefix);
+		if (unlikely(ret))
+			return ret;
+		start += prefix;
+	}
+
+	words = (end - start) / 8;
+	while (words) {
+		if (unlikely(*(u64 *)start))
+			return bytes_is_zero(start, 8);
+		start += 8;
+		words--;
+	}
+
+	return bytes_is_zero(start, (end - start) % 8);
+}
+
+static __always_inline bool memory_is_poisoned_n(unsigned long addr,
+						size_t size)
+{
+	unsigned long ret;
+
+	ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
+			kasan_mem_to_shadow((void *)addr + size - 1) + 1);
+
+	if (unlikely(ret)) {
+		unsigned long last_byte = addr + size - 1;
+		s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
+
+		if (unlikely(ret != (unsigned long)last_shadow ||
+			((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
+			return true;
+	}
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
+{
+	if (__builtin_constant_p(size)) {
+		switch (size) {
+		case 1:
+			return memory_is_poisoned_1(addr);
+		case 2:
+			return memory_is_poisoned_2(addr);
+		case 4:
+			return memory_is_poisoned_4(addr);
+		case 8:
+			return memory_is_poisoned_8(addr);
+		case 16:
+			return memory_is_poisoned_16(addr);
+		default:
+			BUILD_BUG();
+		}
+	}
+
+	return memory_is_poisoned_n(addr, size);
+}
+
+
+static __always_inline void check_memory_region(unsigned long addr,
+						size_t size, bool write)
+{
+	if (unlikely(size == 0))
+		return;
+
+	if (unlikely((void *)addr <
+		kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
+		kasan_report(addr, size, write, _RET_IP_);
+		return;
+	}
+
+	if (likely(!memory_is_poisoned(addr, size)))
+		return;
+
+	kasan_report(addr, size, write, _RET_IP_);
+}
+
+void __asan_loadN(unsigned long addr, size_t size);
+void __asan_storeN(unsigned long addr, size_t size);
+
+#undef memset
+void *memset(void *addr, int c, size_t len)
+{
+	__asan_storeN((unsigned long)addr, len);
+
+	return __memset(addr, c, len);
+}
+
+#undef memmove
+void *memmove(void *dest, const void *src, size_t len)
+{
+	__asan_loadN((unsigned long)src, len);
+	__asan_storeN((unsigned long)dest, len);
+
+	return __memmove(dest, src, len);
+}
+
+#undef memcpy
+void *memcpy(void *dest, const void *src, size_t len)
+{
+	__asan_loadN((unsigned long)src, len);
+	__asan_storeN((unsigned long)dest, len);
+
+	return __memcpy(dest, src, len);
+}
+
+void kasan_alloc_pages(struct page *page, unsigned int order)
+{
+	if (likely(!PageHighMem(page)))
+		kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
+}
+
+void kasan_free_pages(struct page *page, unsigned int order)
+{
+	if (likely(!PageHighMem(page)))
+		kasan_poison_shadow(page_address(page),
+				PAGE_SIZE << order,
+				KASAN_FREE_PAGE);
+}
+
+void kasan_poison_slab(struct page *page)
+{
+	kasan_poison_shadow(page_address(page),
+			PAGE_SIZE << compound_order(page),
+			KASAN_KMALLOC_REDZONE);
+}
+
+void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
+{
+	kasan_unpoison_shadow(object, cache->object_size);
+}
+
+void kasan_poison_object_data(struct kmem_cache *cache, void *object)
+{
+	kasan_poison_shadow(object,
+			round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
+			KASAN_KMALLOC_REDZONE);
+}
+
+void kasan_slab_alloc(struct kmem_cache *cache, void *object)
+{
+	kasan_kmalloc(cache, object, cache->object_size);
+}
+
+void kasan_slab_free(struct kmem_cache *cache, void *object)
+{
+	unsigned long size = cache->object_size;
+	unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
+
+	/* RCU slabs could be legally used after free within the RCU period */
+	if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
+		return;
+
+	kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
+}
+
+void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
+{
+	unsigned long redzone_start;
+	unsigned long redzone_end;
+
+	if (unlikely(object == NULL))
+		return;
+
+	redzone_start = round_up((unsigned long)(object + size),
+				KASAN_SHADOW_SCALE_SIZE);
+	redzone_end = round_up((unsigned long)object + cache->object_size,
+				KASAN_SHADOW_SCALE_SIZE);
+
+	kasan_unpoison_shadow(object, size);
+	kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+		KASAN_KMALLOC_REDZONE);
+}
+EXPORT_SYMBOL(kasan_kmalloc);
+
+void kasan_kmalloc_large(const void *ptr, size_t size)
+{
+	struct page *page;
+	unsigned long redzone_start;
+	unsigned long redzone_end;
+
+	if (unlikely(ptr == NULL))
+		return;
+
+	page = virt_to_page(ptr);
+	redzone_start = round_up((unsigned long)(ptr + size),
+				KASAN_SHADOW_SCALE_SIZE);
+	redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
+
+	kasan_unpoison_shadow(ptr, size);
+	kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+		KASAN_PAGE_REDZONE);
+}
+
+void kasan_krealloc(const void *object, size_t size)
+{
+	struct page *page;
+
+	if (unlikely(object == ZERO_SIZE_PTR))
+		return;
+
+	page = virt_to_head_page(object);
+
+	if (unlikely(!PageSlab(page)))
+		kasan_kmalloc_large(object, size);
+	else
+		kasan_kmalloc(page->slab_cache, object, size);
+}
+
+void kasan_kfree(void *ptr)
+{
+	struct page *page;
+
+	page = virt_to_head_page(ptr);
+
+	if (unlikely(!PageSlab(page)))
+		kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
+				KASAN_FREE_PAGE);
+	else
+		kasan_slab_free(page->slab_cache, ptr);
+}
+
+void kasan_kfree_large(const void *ptr)
+{
+	struct page *page = virt_to_page(ptr);
+
+	kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
+			KASAN_FREE_PAGE);
+}
+
+int kasan_module_alloc(void *addr, size_t size)
+{
+	void *ret;
+	size_t shadow_size;
+	unsigned long shadow_start;
+
+	shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
+	shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
+			PAGE_SIZE);
+
+	if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
+		return -EINVAL;
+
+	ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
+			shadow_start + shadow_size,
+			GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+			PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
+			__builtin_return_address(0));
+
+	if (ret) {
+		find_vm_area(addr)->flags |= VM_KASAN;
+		kmemleak_ignore(ret);
+		return 0;
+	}
+
+	return -ENOMEM;
+}
+
+void kasan_free_shadow(const struct vm_struct *vm)
+{
+	if (vm->flags & VM_KASAN)
+		vfree(kasan_mem_to_shadow(vm->addr));
+}
+
+static void register_global(struct kasan_global *global)
+{
+	size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
+
+	kasan_unpoison_shadow(global->beg, global->size);
+
+	kasan_poison_shadow(global->beg + aligned_size,
+		global->size_with_redzone - aligned_size,
+		KASAN_GLOBAL_REDZONE);
+}
+
+void __asan_register_globals(struct kasan_global *globals, size_t size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		register_global(&globals[i]);
+}
+EXPORT_SYMBOL(__asan_register_globals);
+
+void __asan_unregister_globals(struct kasan_global *globals, size_t size)
+{
+}
+EXPORT_SYMBOL(__asan_unregister_globals);
+
+#define DEFINE_ASAN_LOAD_STORE(size)				\
+	void __asan_load##size(unsigned long addr)		\
+	{							\
+		check_memory_region(addr, size, false);		\
+	}							\
+	EXPORT_SYMBOL(__asan_load##size);			\
+	__alias(__asan_load##size)				\
+	void __asan_load##size##_noabort(unsigned long);	\
+	EXPORT_SYMBOL(__asan_load##size##_noabort);		\
+	void __asan_store##size(unsigned long addr)		\
+	{							\
+		check_memory_region(addr, size, true);		\
+	}							\
+	EXPORT_SYMBOL(__asan_store##size);			\
+	__alias(__asan_store##size)				\
+	void __asan_store##size##_noabort(unsigned long);	\
+	EXPORT_SYMBOL(__asan_store##size##_noabort)
+
+DEFINE_ASAN_LOAD_STORE(1);
+DEFINE_ASAN_LOAD_STORE(2);
+DEFINE_ASAN_LOAD_STORE(4);
+DEFINE_ASAN_LOAD_STORE(8);
+DEFINE_ASAN_LOAD_STORE(16);
+
+void __asan_loadN(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, false);
+}
+EXPORT_SYMBOL(__asan_loadN);
+
+__alias(__asan_loadN)
+void __asan_loadN_noabort(unsigned long, size_t);
+EXPORT_SYMBOL(__asan_loadN_noabort);
+
+void __asan_storeN(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, true);
+}
+EXPORT_SYMBOL(__asan_storeN);
+
+__alias(__asan_storeN)
+void __asan_storeN_noabort(unsigned long, size_t);
+EXPORT_SYMBOL(__asan_storeN_noabort);
+
+/* to shut up compiler complaints */
+void __asan_handle_no_return(void) {}
+EXPORT_SYMBOL(__asan_handle_no_return);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static int kasan_mem_notifier(struct notifier_block *nb,
+			unsigned long action, void *data)
+{
+	return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
+}
+
+static int __init kasan_memhotplug_init(void)
+{
+	pr_err("WARNING: KASAN doesn't support memory hot-add\n");
+	pr_err("Memory hot-add will be disabled\n");
+
+	hotplug_memory_notifier(kasan_mem_notifier, 0);
+
+	return 0;
+}
+
+module_init(kasan_memhotplug_init);
+#endif
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
new file mode 100644
index 0000000..37ff0ab
--- /dev/null
+++ b/mm/kasan/kasan.h
@@ -0,0 +1,74 @@
+#ifndef __MM_KASAN_KASAN_H
+#define __MM_KASAN_KASAN_H
+
+#include <linux/kasan.h>
+
+#define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
+#define KASAN_SHADOW_MASK       (KASAN_SHADOW_SCALE_SIZE - 1)
+
+#define KASAN_FREE_PAGE         0xFF  /* page was freed */
+#define KASAN_PAGE_REDZONE      0xFE  /* redzone for kmalloc_large allocations */
+#define KASAN_KMALLOC_REDZONE   0xFC  /* redzone inside slub object */
+#define KASAN_KMALLOC_FREE      0xFB  /* object was freed (kmem_cache_free/kfree) */
+#define KASAN_GLOBAL_REDZONE    0xFA  /* redzone for global variable */
+
+/*
+ * Stack redzone shadow values
+ * (Those are compiler's ABI, don't change them)
+ */
+#define KASAN_STACK_LEFT        0xF1
+#define KASAN_STACK_MID         0xF2
+#define KASAN_STACK_RIGHT       0xF3
+#define KASAN_STACK_PARTIAL     0xF4
+
+/* Don't break randconfig/all*config builds */
+#ifndef KASAN_ABI_VERSION
+#define KASAN_ABI_VERSION 1
+#endif
+
+struct kasan_access_info {
+	const void *access_addr;
+	const void *first_bad_addr;
+	size_t access_size;
+	bool is_write;
+	unsigned long ip;
+};
+
+/* The layout of struct dictated by compiler */
+struct kasan_source_location {
+	const char *filename;
+	int line_no;
+	int column_no;
+};
+
+/* The layout of struct dictated by compiler */
+struct kasan_global {
+	const void *beg;		/* Address of the beginning of the global variable. */
+	size_t size;			/* Size of the global variable. */
+	size_t size_with_redzone;	/* Size of the variable + size of the red zone. 32 bytes aligned */
+	const void *name;
+	const void *module_name;	/* Name of the module where the global variable is declared. */
+	unsigned long has_dynamic_init;	/* This needed for C++ */
+#if KASAN_ABI_VERSION >= 4
+	struct kasan_source_location *location;
+#endif
+#if KASAN_ABI_VERSION >= 5
+	char *odr_indicator;
+#endif
+};
+
+static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
+{
+	return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
+		<< KASAN_SHADOW_SCALE_SHIFT);
+}
+
+static inline bool kasan_report_enabled(void)
+{
+	return !current->kasan_depth;
+}
+
+void kasan_report(unsigned long addr, size_t size,
+		bool is_write, unsigned long ip);
+
+#endif
diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c
new file mode 100644
index 0000000..3f9a41c
--- /dev/null
+++ b/mm/kasan/kasan_init.c
@@ -0,0 +1,152 @@
+/*
+ * This file contains some kasan initialization code.
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/pfn.h>
+
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+
+/*
+ * This page serves two purposes:
+ *   - It used as early shadow memory. The entire shadow region populated
+ *     with this page, before we will be able to setup normal shadow memory.
+ *   - Latter it reused it as zero shadow to cover large ranges of memory
+ *     that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
+ */
+unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
+
+#if CONFIG_PGTABLE_LEVELS > 3
+pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
+#endif
+#if CONFIG_PGTABLE_LEVELS > 2
+pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
+#endif
+pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
+
+static __init void *early_alloc(size_t size, int node)
+{
+	return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
+					BOOTMEM_ALLOC_ACCESSIBLE, node);
+}
+
+static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
+				unsigned long end)
+{
+	pte_t *pte = pte_offset_kernel(pmd, addr);
+	pte_t zero_pte;
+
+	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
+	zero_pte = pte_wrprotect(zero_pte);
+
+	while (addr + PAGE_SIZE <= end) {
+		set_pte_at(&init_mm, addr, pte, zero_pte);
+		addr += PAGE_SIZE;
+		pte = pte_offset_kernel(pmd, addr);
+	}
+}
+
+static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,
+				unsigned long end)
+{
+	pmd_t *pmd = pmd_offset(pud, addr);
+	unsigned long next;
+
+	do {
+		next = pmd_addr_end(addr, end);
+
+		if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
+			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+			continue;
+		}
+
+		if (pmd_none(*pmd)) {
+			pmd_populate_kernel(&init_mm, pmd,
+					early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+		}
+		zero_pte_populate(pmd, addr, next);
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
+				unsigned long end)
+{
+	pud_t *pud = pud_offset(pgd, addr);
+	unsigned long next;
+
+	do {
+		next = pud_addr_end(addr, end);
+		if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
+			pmd_t *pmd;
+
+			pud_populate(&init_mm, pud, kasan_zero_pmd);
+			pmd = pmd_offset(pud, addr);
+			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+			continue;
+		}
+
+		if (pud_none(*pud)) {
+			pud_populate(&init_mm, pud,
+				early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+		}
+		zero_pmd_populate(pud, addr, next);
+	} while (pud++, addr = next, addr != end);
+}
+
+/**
+ * kasan_populate_zero_shadow - populate shadow memory region with
+ *                               kasan_zero_page
+ * @shadow_start - start of the memory range to populate
+ * @shadow_end   - end of the memory range to populate
+ */
+void __init kasan_populate_zero_shadow(const void *shadow_start,
+				const void *shadow_end)
+{
+	unsigned long addr = (unsigned long)shadow_start;
+	unsigned long end = (unsigned long)shadow_end;
+	pgd_t *pgd = pgd_offset_k(addr);
+	unsigned long next;
+
+	do {
+		next = pgd_addr_end(addr, end);
+
+		if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
+			pud_t *pud;
+			pmd_t *pmd;
+
+			/*
+			 * kasan_zero_pud should be populated with pmds
+			 * at this moment.
+			 * [pud,pmd]_populate*() below needed only for
+			 * 3,2 - level page tables where we don't have
+			 * puds,pmds, so pgd_populate(), pud_populate()
+			 * is noops.
+			 */
+			pgd_populate(&init_mm, pgd, kasan_zero_pud);
+			pud = pud_offset(pgd, addr);
+			pud_populate(&init_mm, pud, kasan_zero_pmd);
+			pmd = pmd_offset(pud, addr);
+			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+			continue;
+		}
+
+		if (pgd_none(*pgd)) {
+			pgd_populate(&init_mm, pgd,
+				early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+		}
+		zero_pud_populate(pgd, addr, next);
+	} while (pgd++, addr = next, addr != end);
+}
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
new file mode 100644
index 0000000..b4e31f7
--- /dev/null
+++ b/mm/kasan/report.c
@@ -0,0 +1,301 @@
+/*
+ * This file contains error reporting code.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * Some code borrowed from https://github.com/xairy/kasan-prototype by
+ *        Andrey Konovalov <adech.fo@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/ftrace.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/kasan.h>
+#include <linux/module.h>
+
+#include <asm/sections.h>
+
+#include "kasan.h"
+#include "../slab.h"
+
+/* Shadow layout customization. */
+#define SHADOW_BYTES_PER_BLOCK 1
+#define SHADOW_BLOCKS_PER_ROW 16
+#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
+#define SHADOW_ROWS_AROUND_ADDR 2
+
+static const void *find_first_bad_addr(const void *addr, size_t size)
+{
+	u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
+	const void *first_bad_addr = addr;
+
+	while (!shadow_val && first_bad_addr < addr + size) {
+		first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
+		shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
+	}
+	return first_bad_addr;
+}
+
+static void print_error_description(struct kasan_access_info *info)
+{
+	const char *bug_type = "unknown-crash";
+	u8 *shadow_addr;
+
+	info->first_bad_addr = find_first_bad_addr(info->access_addr,
+						info->access_size);
+
+	shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
+
+	/*
+	 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
+	 * at the next shadow byte to determine the type of the bad access.
+	 */
+	if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
+		shadow_addr++;
+
+	switch (*shadow_addr) {
+	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
+		/*
+		 * In theory it's still possible to see these shadow values
+		 * due to a data race in the kernel code.
+		 */
+		bug_type = "out-of-bounds";
+		break;
+	case KASAN_PAGE_REDZONE:
+	case KASAN_KMALLOC_REDZONE:
+		bug_type = "slab-out-of-bounds";
+		break;
+	case KASAN_GLOBAL_REDZONE:
+		bug_type = "global-out-of-bounds";
+		break;
+	case KASAN_STACK_LEFT:
+	case KASAN_STACK_MID:
+	case KASAN_STACK_RIGHT:
+	case KASAN_STACK_PARTIAL:
+		bug_type = "stack-out-of-bounds";
+		break;
+	case KASAN_FREE_PAGE:
+	case KASAN_KMALLOC_FREE:
+		bug_type = "use-after-free";
+		break;
+	}
+
+	pr_err("BUG: KASAN: %s in %pS at addr %p\n",
+		bug_type, (void *)info->ip,
+		info->access_addr);
+	pr_err("%s of size %zu by task %s/%d\n",
+		info->is_write ? "Write" : "Read",
+		info->access_size, current->comm, task_pid_nr(current));
+}
+
+static inline bool kernel_or_module_addr(const void *addr)
+{
+	if (addr >= (void *)_stext && addr < (void *)_end)
+		return true;
+	if (is_module_address((unsigned long)addr))
+		return true;
+	return false;
+}
+
+static inline bool init_task_stack_addr(const void *addr)
+{
+	return addr >= (void *)&init_thread_union.stack &&
+		(addr <= (void *)&init_thread_union.stack +
+			sizeof(init_thread_union.stack));
+}
+
+static void print_address_description(struct kasan_access_info *info)
+{
+	const void *addr = info->access_addr;
+
+	if ((addr >= (void *)PAGE_OFFSET) &&
+		(addr < high_memory)) {
+		struct page *page = virt_to_head_page(addr);
+
+		if (PageSlab(page)) {
+			void *object;
+			struct kmem_cache *cache = page->slab_cache;
+			void *last_object;
+
+			object = virt_to_obj(cache, page_address(page), addr);
+			last_object = page_address(page) +
+				page->objects * cache->size;
+
+			if (unlikely(object > last_object))
+				object = last_object; /* we hit into padding */
+
+			object_err(cache, page, object,
+				"kasan: bad access detected");
+			return;
+		}
+		dump_page(page, "kasan: bad access detected");
+	}
+
+	if (kernel_or_module_addr(addr)) {
+		if (!init_task_stack_addr(addr))
+			pr_err("Address belongs to variable %pS\n", addr);
+	}
+
+	dump_stack();
+}
+
+static bool row_is_guilty(const void *row, const void *guilty)
+{
+	return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
+}
+
+static int shadow_pointer_offset(const void *row, const void *shadow)
+{
+	/* The length of ">ff00ff00ff00ff00: " is
+	 *    3 + (BITS_PER_LONG/8)*2 chars.
+	 */
+	return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
+		(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
+}
+
+static void print_shadow_for_address(const void *addr)
+{
+	int i;
+	const void *shadow = kasan_mem_to_shadow(addr);
+	const void *shadow_row;
+
+	shadow_row = (void *)round_down((unsigned long)shadow,
+					SHADOW_BYTES_PER_ROW)
+		- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
+
+	pr_err("Memory state around the buggy address:\n");
+
+	for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
+		const void *kaddr = kasan_shadow_to_mem(shadow_row);
+		char buffer[4 + (BITS_PER_LONG/8)*2];
+		char shadow_buf[SHADOW_BYTES_PER_ROW];
+
+		snprintf(buffer, sizeof(buffer),
+			(i == 0) ? ">%p: " : " %p: ", kaddr);
+		/*
+		 * We should not pass a shadow pointer to generic
+		 * function, because generic functions may try to
+		 * access kasan mapping for the passed address.
+		 */
+		memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
+		print_hex_dump(KERN_ERR, buffer,
+			DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
+			shadow_buf, SHADOW_BYTES_PER_ROW, 0);
+
+		if (row_is_guilty(shadow_row, shadow))
+			pr_err("%*c\n",
+				shadow_pointer_offset(shadow_row, shadow),
+				'^');
+
+		shadow_row += SHADOW_BYTES_PER_ROW;
+	}
+}
+
+static DEFINE_SPINLOCK(report_lock);
+
+static void kasan_report_error(struct kasan_access_info *info)
+{
+	unsigned long flags;
+	const char *bug_type;
+
+	/*
+	 * Make sure we don't end up in loop.
+	 */
+	kasan_disable_current();
+	spin_lock_irqsave(&report_lock, flags);
+	pr_err("================================="
+		"=================================\n");
+	if (info->access_addr <
+			kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
+		if ((unsigned long)info->access_addr < PAGE_SIZE)
+			bug_type = "null-ptr-deref";
+		else if ((unsigned long)info->access_addr < TASK_SIZE)
+			bug_type = "user-memory-access";
+		else
+			bug_type = "wild-memory-access";
+		pr_err("BUG: KASAN: %s on address %p\n",
+			bug_type, info->access_addr);
+		pr_err("%s of size %zu by task %s/%d\n",
+			info->is_write ? "Write" : "Read",
+			info->access_size, current->comm,
+			task_pid_nr(current));
+		dump_stack();
+	} else {
+		print_error_description(info);
+		print_address_description(info);
+		print_shadow_for_address(info->first_bad_addr);
+	}
+	pr_err("================================="
+		"=================================\n");
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+	spin_unlock_irqrestore(&report_lock, flags);
+	kasan_enable_current();
+}
+
+void kasan_report(unsigned long addr, size_t size,
+		bool is_write, unsigned long ip)
+{
+	struct kasan_access_info info;
+
+	if (likely(!kasan_report_enabled()))
+		return;
+
+	disable_trace_on_warning();
+
+	info.access_addr = (void *)addr;
+	info.access_size = size;
+	info.is_write = is_write;
+	info.ip = ip;
+
+	kasan_report_error(&info);
+}
+
+
+#define DEFINE_ASAN_REPORT_LOAD(size)                     \
+void __asan_report_load##size##_noabort(unsigned long addr) \
+{                                                         \
+	kasan_report(addr, size, false, _RET_IP_);	  \
+}                                                         \
+EXPORT_SYMBOL(__asan_report_load##size##_noabort)
+
+#define DEFINE_ASAN_REPORT_STORE(size)                     \
+void __asan_report_store##size##_noabort(unsigned long addr) \
+{                                                          \
+	kasan_report(addr, size, true, _RET_IP_);	   \
+}                                                          \
+EXPORT_SYMBOL(__asan_report_store##size##_noabort)
+
+DEFINE_ASAN_REPORT_LOAD(1);
+DEFINE_ASAN_REPORT_LOAD(2);
+DEFINE_ASAN_REPORT_LOAD(4);
+DEFINE_ASAN_REPORT_LOAD(8);
+DEFINE_ASAN_REPORT_LOAD(16);
+DEFINE_ASAN_REPORT_STORE(1);
+DEFINE_ASAN_REPORT_STORE(2);
+DEFINE_ASAN_REPORT_STORE(4);
+DEFINE_ASAN_REPORT_STORE(8);
+DEFINE_ASAN_REPORT_STORE(16);
+
+void __asan_report_load_n_noabort(unsigned long addr, size_t size)
+{
+	kasan_report(addr, size, false, _RET_IP_);
+}
+EXPORT_SYMBOL(__asan_report_load_n_noabort);
+
+void __asan_report_store_n_noabort(unsigned long addr, size_t size)
+{
+	kasan_report(addr, size, true, _RET_IP_);
+}
+EXPORT_SYMBOL(__asan_report_store_n_noabort);
diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
new file mode 100644
index 0000000..cab58bb
--- /dev/null
+++ b/mm/kmemcheck.c
@@ -0,0 +1,123 @@
+#include <linux/gfp.h>
+#include <linux/mm_types.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include "slab.h"
+#include <linux/kmemcheck.h>
+
+void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
+{
+	struct page *shadow;
+	int pages;
+	int i;
+
+	pages = 1 << order;
+
+	/*
+	 * With kmemcheck enabled, we need to allocate a memory area for the
+	 * shadow bits as well.
+	 */
+	shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
+	if (!shadow) {
+		if (printk_ratelimit())
+			printk(KERN_ERR "kmemcheck: failed to allocate "
+				"shadow bitmap\n");
+		return;
+	}
+
+	for(i = 0; i < pages; ++i)
+		page[i].shadow = page_address(&shadow[i]);
+
+	/*
+	 * Mark it as non-present for the MMU so that our accesses to
+	 * this memory will trigger a page fault and let us analyze
+	 * the memory accesses.
+	 */
+	kmemcheck_hide_pages(page, pages);
+}
+
+void kmemcheck_free_shadow(struct page *page, int order)
+{
+	struct page *shadow;
+	int pages;
+	int i;
+
+	if (!kmemcheck_page_is_tracked(page))
+		return;
+
+	pages = 1 << order;
+
+	kmemcheck_show_pages(page, pages);
+
+	shadow = virt_to_page(page[0].shadow);
+
+	for(i = 0; i < pages; ++i)
+		page[i].shadow = NULL;
+
+	__free_pages(shadow, order);
+}
+
+void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
+			  size_t size)
+{
+	/*
+	 * Has already been memset(), which initializes the shadow for us
+	 * as well.
+	 */
+	if (gfpflags & __GFP_ZERO)
+		return;
+
+	/* No need to initialize the shadow of a non-tracked slab. */
+	if (s->flags & SLAB_NOTRACK)
+		return;
+
+	if (!kmemcheck_enabled || gfpflags & __GFP_NOTRACK) {
+		/*
+		 * Allow notracked objects to be allocated from
+		 * tracked caches. Note however that these objects
+		 * will still get page faults on access, they just
+		 * won't ever be flagged as uninitialized. If page
+		 * faults are not acceptable, the slab cache itself
+		 * should be marked NOTRACK.
+		 */
+		kmemcheck_mark_initialized(object, size);
+	} else if (!s->ctor) {
+		/*
+		 * New objects should be marked uninitialized before
+		 * they're returned to the called.
+		 */
+		kmemcheck_mark_uninitialized(object, size);
+	}
+}
+
+void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
+{
+	/* TODO: RCU freeing is unsupported for now; hide false positives. */
+	if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
+		kmemcheck_mark_freed(object, size);
+}
+
+void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
+			       gfp_t gfpflags)
+{
+	int pages;
+
+	if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
+		return;
+
+	pages = 1 << order;
+
+	/*
+	 * NOTE: We choose to track GFP_ZERO pages too; in fact, they
+	 * can become uninitialized by copying uninitialized memory
+	 * into them.
+	 */
+
+	/* XXX: Can use zone->node for node? */
+	kmemcheck_alloc_shadow(page, order, gfpflags, -1);
+
+	if (gfpflags & __GFP_ZERO)
+		kmemcheck_mark_initialized_pages(page, pages);
+	else
+		kmemcheck_mark_uninitialized_pages(page, pages);
+}
diff --git a/mm/kmemleak-test.c b/mm/kmemleak-test.c
new file mode 100644
index 0000000..dcdcadb
--- /dev/null
+++ b/mm/kmemleak-test.c
@@ -0,0 +1,111 @@
+/*
+ * mm/kmemleak-test.c
+ *
+ * Copyright (C) 2008 ARM Limited
+ * Written by Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#define pr_fmt(fmt) "kmemleak: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/list.h>
+#include <linux/percpu.h>
+#include <linux/fdtable.h>
+
+#include <linux/kmemleak.h>
+
+struct test_node {
+	long header[25];
+	struct list_head list;
+	long footer[25];
+};
+
+static LIST_HEAD(test_list);
+static DEFINE_PER_CPU(void *, kmemleak_test_pointer);
+
+/*
+ * Some very simple testing. This function needs to be extended for
+ * proper testing.
+ */
+static int __init kmemleak_test_init(void)
+{
+	struct test_node *elem;
+	int i;
+
+	printk(KERN_INFO "Kmemleak testing\n");
+
+	/* make some orphan objects */
+	pr_info("kmalloc(32) = %p\n", kmalloc(32, GFP_KERNEL));
+	pr_info("kmalloc(32) = %p\n", kmalloc(32, GFP_KERNEL));
+	pr_info("kmalloc(1024) = %p\n", kmalloc(1024, GFP_KERNEL));
+	pr_info("kmalloc(1024) = %p\n", kmalloc(1024, GFP_KERNEL));
+	pr_info("kmalloc(2048) = %p\n", kmalloc(2048, GFP_KERNEL));
+	pr_info("kmalloc(2048) = %p\n", kmalloc(2048, GFP_KERNEL));
+	pr_info("kmalloc(4096) = %p\n", kmalloc(4096, GFP_KERNEL));
+	pr_info("kmalloc(4096) = %p\n", kmalloc(4096, GFP_KERNEL));
+#ifndef CONFIG_MODULES
+	pr_info("kmem_cache_alloc(files_cachep) = %p\n",
+		kmem_cache_alloc(files_cachep, GFP_KERNEL));
+	pr_info("kmem_cache_alloc(files_cachep) = %p\n",
+		kmem_cache_alloc(files_cachep, GFP_KERNEL));
+#endif
+	pr_info("vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("vmalloc(64) = %p\n", vmalloc(64));
+
+	/*
+	 * Add elements to a list. They should only appear as orphan
+	 * after the module is removed.
+	 */
+	for (i = 0; i < 10; i++) {
+		elem = kzalloc(sizeof(*elem), GFP_KERNEL);
+		pr_info("kzalloc(sizeof(*elem)) = %p\n", elem);
+		if (!elem)
+			return -ENOMEM;
+		INIT_LIST_HEAD(&elem->list);
+		list_add_tail(&elem->list, &test_list);
+	}
+
+	for_each_possible_cpu(i) {
+		per_cpu(kmemleak_test_pointer, i) = kmalloc(129, GFP_KERNEL);
+		pr_info("kmalloc(129) = %p\n",
+			per_cpu(kmemleak_test_pointer, i));
+	}
+
+	return 0;
+}
+module_init(kmemleak_test_init);
+
+static void __exit kmemleak_test_exit(void)
+{
+	struct test_node *elem, *tmp;
+
+	/*
+	 * Remove the list elements without actually freeing the
+	 * memory.
+	 */
+	list_for_each_entry_safe(elem, tmp, &test_list, list)
+		list_del(&elem->list);
+}
+module_exit(kmemleak_test_exit);
+
+MODULE_LICENSE("GPL");
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
new file mode 100644
index 0000000..19423a4
--- /dev/null
+++ b/mm/kmemleak.c
@@ -0,0 +1,1973 @@
+/*
+ * mm/kmemleak.c
+ *
+ * Copyright (C) 2008 ARM Limited
+ * Written by Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ *
+ * For more information on the algorithm and kmemleak usage, please see
+ * Documentation/kmemleak.txt.
+ *
+ * Notes on locking
+ * ----------------
+ *
+ * The following locks and mutexes are used by kmemleak:
+ *
+ * - kmemleak_lock (rwlock): protects the object_list modifications and
+ *   accesses to the object_tree_root. The object_list is the main list
+ *   holding the metadata (struct kmemleak_object) for the allocated memory
+ *   blocks. The object_tree_root is a red black tree used to look-up
+ *   metadata based on a pointer to the corresponding memory block.  The
+ *   kmemleak_object structures are added to the object_list and
+ *   object_tree_root in the create_object() function called from the
+ *   kmemleak_alloc() callback and removed in delete_object() called from the
+ *   kmemleak_free() callback
+ * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
+ *   the metadata (e.g. count) are protected by this lock. Note that some
+ *   members of this structure may be protected by other means (atomic or
+ *   kmemleak_lock). This lock is also held when scanning the corresponding
+ *   memory block to avoid the kernel freeing it via the kmemleak_free()
+ *   callback. This is less heavyweight than holding a global lock like
+ *   kmemleak_lock during scanning
+ * - scan_mutex (mutex): ensures that only one thread may scan the memory for
+ *   unreferenced objects at a time. The gray_list contains the objects which
+ *   are already referenced or marked as false positives and need to be
+ *   scanned. This list is only modified during a scanning episode when the
+ *   scan_mutex is held. At the end of a scan, the gray_list is always empty.
+ *   Note that the kmemleak_object.use_count is incremented when an object is
+ *   added to the gray_list and therefore cannot be freed. This mutex also
+ *   prevents multiple users of the "kmemleak" debugfs file together with
+ *   modifications to the memory scanning parameters including the scan_thread
+ *   pointer
+ *
+ * Locks and mutexes are acquired/nested in the following order:
+ *
+ *   scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
+ *
+ * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
+ * regions.
+ *
+ * The kmemleak_object structures have a use_count incremented or decremented
+ * using the get_object()/put_object() functions. When the use_count becomes
+ * 0, this count can no longer be incremented and put_object() schedules the
+ * kmemleak_object freeing via an RCU callback. All calls to the get_object()
+ * function must be protected by rcu_read_lock() to avoid accessing a freed
+ * structure.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/kthread.h>
+#include <linux/rbtree.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/cpumask.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/rcupdate.h>
+#include <linux/stacktrace.h>
+#include <linux/cache.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <linux/mmzone.h>
+#include <linux/slab.h>
+#include <linux/thread_info.h>
+#include <linux/err.h>
+#include <linux/uaccess.h>
+#include <linux/string.h>
+#include <linux/nodemask.h>
+#include <linux/mm.h>
+#include <linux/workqueue.h>
+#include <linux/crc32.h>
+
+#include <asm/sections.h>
+#include <asm/processor.h>
+#include <linux/atomic.h>
+
+#include <linux/kasan.h>
+#include <linux/kmemcheck.h>
+#include <linux/kmemleak.h>
+#include <linux/memory_hotplug.h>
+
+/*
+ * Kmemleak configuration and common defines.
+ */
+#define MAX_TRACE		16	/* stack trace length */
+#define MSECS_MIN_AGE		5000	/* minimum object age for reporting */
+#define SECS_FIRST_SCAN		60	/* delay before the first scan */
+#define SECS_SCAN_WAIT		600	/* subsequent auto scanning delay */
+#define MAX_SCAN_SIZE		4096	/* maximum size of a scanned block */
+
+#define BYTES_PER_POINTER	sizeof(void *)
+
+/* GFP bitmask for kmemleak internal allocations */
+#define gfp_kmemleak_mask(gfp)	(((gfp) & (GFP_KERNEL | GFP_ATOMIC | \
+					   __GFP_NOACCOUNT)) | \
+				 __GFP_NORETRY | __GFP_NOMEMALLOC | \
+				 __GFP_NOWARN)
+
+/* scanning area inside a memory block */
+struct kmemleak_scan_area {
+	struct hlist_node node;
+	unsigned long start;
+	size_t size;
+};
+
+#define KMEMLEAK_GREY	0
+#define KMEMLEAK_BLACK	-1
+
+/*
+ * Structure holding the metadata for each allocated memory block.
+ * Modifications to such objects should be made while holding the
+ * object->lock. Insertions or deletions from object_list, gray_list or
+ * rb_node are already protected by the corresponding locks or mutex (see
+ * the notes on locking above). These objects are reference-counted
+ * (use_count) and freed using the RCU mechanism.
+ */
+struct kmemleak_object {
+	spinlock_t lock;
+	unsigned long flags;		/* object status flags */
+	struct list_head object_list;
+	struct list_head gray_list;
+	struct rb_node rb_node;
+	struct rcu_head rcu;		/* object_list lockless traversal */
+	/* object usage count; object freed when use_count == 0 */
+	atomic_t use_count;
+	unsigned long pointer;
+	size_t size;
+	/* minimum number of a pointers found before it is considered leak */
+	int min_count;
+	/* the total number of pointers found pointing to this object */
+	int count;
+	/* checksum for detecting modified objects */
+	u32 checksum;
+	/* memory ranges to be scanned inside an object (empty for all) */
+	struct hlist_head area_list;
+	unsigned long trace[MAX_TRACE];
+	unsigned int trace_len;
+	unsigned long jiffies;		/* creation timestamp */
+	pid_t pid;			/* pid of the current task */
+	char comm[TASK_COMM_LEN];	/* executable name */
+};
+
+/* flag representing the memory block allocation status */
+#define OBJECT_ALLOCATED	(1 << 0)
+/* flag set after the first reporting of an unreference object */
+#define OBJECT_REPORTED		(1 << 1)
+/* flag set to not scan the object */
+#define OBJECT_NO_SCAN		(1 << 2)
+
+/* number of bytes to print per line; must be 16 or 32 */
+#define HEX_ROW_SIZE		16
+/* number of bytes to print at a time (1, 2, 4, 8) */
+#define HEX_GROUP_SIZE		1
+/* include ASCII after the hex output */
+#define HEX_ASCII		1
+/* max number of lines to be printed */
+#define HEX_MAX_LINES		2
+
+/* the list of all allocated objects */
+static LIST_HEAD(object_list);
+/* the list of gray-colored objects (see color_gray comment below) */
+static LIST_HEAD(gray_list);
+/* search tree for object boundaries */
+static struct rb_root object_tree_root = RB_ROOT;
+/* rw_lock protecting the access to object_list and object_tree_root */
+static DEFINE_RWLOCK(kmemleak_lock);
+
+/* allocation caches for kmemleak internal data */
+static struct kmem_cache *object_cache;
+static struct kmem_cache *scan_area_cache;
+
+/* set if tracing memory operations is enabled */
+static int kmemleak_enabled;
+/* same as above but only for the kmemleak_free() callback */
+static int kmemleak_free_enabled;
+/* set in the late_initcall if there were no errors */
+static int kmemleak_initialized;
+/* enables or disables early logging of the memory operations */
+static int kmemleak_early_log = 1;
+/* set if a kmemleak warning was issued */
+static int kmemleak_warning;
+/* set if a fatal kmemleak error has occurred */
+static int kmemleak_error;
+
+/* minimum and maximum address that may be valid pointers */
+static unsigned long min_addr = ULONG_MAX;
+static unsigned long max_addr;
+
+static struct task_struct *scan_thread;
+/* used to avoid reporting of recently allocated objects */
+static unsigned long jiffies_min_age;
+static unsigned long jiffies_last_scan;
+/* delay between automatic memory scannings */
+static signed long jiffies_scan_wait;
+/* enables or disables the task stacks scanning */
+static int kmemleak_stack_scan = 1;
+/* protects the memory scanning, parameters and debug/kmemleak file access */
+static DEFINE_MUTEX(scan_mutex);
+/* setting kmemleak=on, will set this var, skipping the disable */
+static int kmemleak_skip_disable;
+/* If there are leaks that can be reported */
+static bool kmemleak_found_leaks;
+
+/*
+ * Early object allocation/freeing logging. Kmemleak is initialized after the
+ * kernel allocator. However, both the kernel allocator and kmemleak may
+ * allocate memory blocks which need to be tracked. Kmemleak defines an
+ * arbitrary buffer to hold the allocation/freeing information before it is
+ * fully initialized.
+ */
+
+/* kmemleak operation type for early logging */
+enum {
+	KMEMLEAK_ALLOC,
+	KMEMLEAK_ALLOC_PERCPU,
+	KMEMLEAK_FREE,
+	KMEMLEAK_FREE_PART,
+	KMEMLEAK_FREE_PERCPU,
+	KMEMLEAK_NOT_LEAK,
+	KMEMLEAK_IGNORE,
+	KMEMLEAK_SCAN_AREA,
+	KMEMLEAK_NO_SCAN
+};
+
+/*
+ * Structure holding the information passed to kmemleak callbacks during the
+ * early logging.
+ */
+struct early_log {
+	int op_type;			/* kmemleak operation type */
+	const void *ptr;		/* allocated/freed memory block */
+	size_t size;			/* memory block size */
+	int min_count;			/* minimum reference count */
+	unsigned long trace[MAX_TRACE];	/* stack trace */
+	unsigned int trace_len;		/* stack trace length */
+};
+
+/* early logging buffer and current position */
+static struct early_log
+	early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
+static int crt_early_log __initdata;
+
+static void kmemleak_disable(void);
+
+/*
+ * Print a warning and dump the stack trace.
+ */
+#define kmemleak_warn(x...)	do {		\
+	pr_warning(x);				\
+	dump_stack();				\
+	kmemleak_warning = 1;			\
+} while (0)
+
+/*
+ * Macro invoked when a serious kmemleak condition occurred and cannot be
+ * recovered from. Kmemleak will be disabled and further allocation/freeing
+ * tracing no longer available.
+ */
+#define kmemleak_stop(x...)	do {	\
+	kmemleak_warn(x);		\
+	kmemleak_disable();		\
+} while (0)
+
+/*
+ * Printing of the objects hex dump to the seq file. The number of lines to be
+ * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
+ * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
+ * with the object->lock held.
+ */
+static void hex_dump_object(struct seq_file *seq,
+			    struct kmemleak_object *object)
+{
+	const u8 *ptr = (const u8 *)object->pointer;
+	size_t len;
+
+	/* limit the number of lines to HEX_MAX_LINES */
+	len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
+
+	seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
+	seq_hex_dump(seq, "    ", DUMP_PREFIX_NONE, HEX_ROW_SIZE,
+		     HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
+}
+
+/*
+ * Object colors, encoded with count and min_count:
+ * - white - orphan object, not enough references to it (count < min_count)
+ * - gray  - not orphan, not marked as false positive (min_count == 0) or
+ *		sufficient references to it (count >= min_count)
+ * - black - ignore, it doesn't contain references (e.g. text section)
+ *		(min_count == -1). No function defined for this color.
+ * Newly created objects don't have any color assigned (object->count == -1)
+ * before the next memory scan when they become white.
+ */
+static bool color_white(const struct kmemleak_object *object)
+{
+	return object->count != KMEMLEAK_BLACK &&
+		object->count < object->min_count;
+}
+
+static bool color_gray(const struct kmemleak_object *object)
+{
+	return object->min_count != KMEMLEAK_BLACK &&
+		object->count >= object->min_count;
+}
+
+/*
+ * Objects are considered unreferenced only if their color is white, they have
+ * not be deleted and have a minimum age to avoid false positives caused by
+ * pointers temporarily stored in CPU registers.
+ */
+static bool unreferenced_object(struct kmemleak_object *object)
+{
+	return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
+		time_before_eq(object->jiffies + jiffies_min_age,
+			       jiffies_last_scan);
+}
+
+/*
+ * Printing of the unreferenced objects information to the seq file. The
+ * print_unreferenced function must be called with the object->lock held.
+ */
+static void print_unreferenced(struct seq_file *seq,
+			       struct kmemleak_object *object)
+{
+	int i;
+	unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
+
+	seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
+		   object->pointer, object->size);
+	seq_printf(seq, "  comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
+		   object->comm, object->pid, object->jiffies,
+		   msecs_age / 1000, msecs_age % 1000);
+	hex_dump_object(seq, object);
+	seq_printf(seq, "  backtrace:\n");
+
+	for (i = 0; i < object->trace_len; i++) {
+		void *ptr = (void *)object->trace[i];
+		seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
+	}
+}
+
+/*
+ * Print the kmemleak_object information. This function is used mainly for
+ * debugging special cases when kmemleak operations. It must be called with
+ * the object->lock held.
+ */
+static void dump_object_info(struct kmemleak_object *object)
+{
+	struct stack_trace trace;
+
+	trace.nr_entries = object->trace_len;
+	trace.entries = object->trace;
+
+	pr_notice("Object 0x%08lx (size %zu):\n",
+		  object->pointer, object->size);
+	pr_notice("  comm \"%s\", pid %d, jiffies %lu\n",
+		  object->comm, object->pid, object->jiffies);
+	pr_notice("  min_count = %d\n", object->min_count);
+	pr_notice("  count = %d\n", object->count);
+	pr_notice("  flags = 0x%lx\n", object->flags);
+	pr_notice("  checksum = %u\n", object->checksum);
+	pr_notice("  backtrace:\n");
+	print_stack_trace(&trace, 4);
+}
+
+/*
+ * Look-up a memory block metadata (kmemleak_object) in the object search
+ * tree based on a pointer value. If alias is 0, only values pointing to the
+ * beginning of the memory block are allowed. The kmemleak_lock must be held
+ * when calling this function.
+ */
+static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
+{
+	struct rb_node *rb = object_tree_root.rb_node;
+
+	while (rb) {
+		struct kmemleak_object *object =
+			rb_entry(rb, struct kmemleak_object, rb_node);
+		if (ptr < object->pointer)
+			rb = object->rb_node.rb_left;
+		else if (object->pointer + object->size <= ptr)
+			rb = object->rb_node.rb_right;
+		else if (object->pointer == ptr || alias)
+			return object;
+		else {
+			kmemleak_warn("Found object by alias at 0x%08lx\n",
+				      ptr);
+			dump_object_info(object);
+			break;
+		}
+	}
+	return NULL;
+}
+
+/*
+ * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
+ * that once an object's use_count reached 0, the RCU freeing was already
+ * registered and the object should no longer be used. This function must be
+ * called under the protection of rcu_read_lock().
+ */
+static int get_object(struct kmemleak_object *object)
+{
+	return atomic_inc_not_zero(&object->use_count);
+}
+
+/*
+ * RCU callback to free a kmemleak_object.
+ */
+static void free_object_rcu(struct rcu_head *rcu)
+{
+	struct hlist_node *tmp;
+	struct kmemleak_scan_area *area;
+	struct kmemleak_object *object =
+		container_of(rcu, struct kmemleak_object, rcu);
+
+	/*
+	 * Once use_count is 0 (guaranteed by put_object), there is no other
+	 * code accessing this object, hence no need for locking.
+	 */
+	hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
+		hlist_del(&area->node);
+		kmem_cache_free(scan_area_cache, area);
+	}
+	kmem_cache_free(object_cache, object);
+}
+
+/*
+ * Decrement the object use_count. Once the count is 0, free the object using
+ * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
+ * delete_object() path, the delayed RCU freeing ensures that there is no
+ * recursive call to the kernel allocator. Lock-less RCU object_list traversal
+ * is also possible.
+ */
+static void put_object(struct kmemleak_object *object)
+{
+	if (!atomic_dec_and_test(&object->use_count))
+		return;
+
+	/* should only get here after delete_object was called */
+	WARN_ON(object->flags & OBJECT_ALLOCATED);
+
+	call_rcu(&object->rcu, free_object_rcu);
+}
+
+/*
+ * Look up an object in the object search tree and increase its use_count.
+ */
+static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	rcu_read_lock();
+	read_lock_irqsave(&kmemleak_lock, flags);
+	object = lookup_object(ptr, alias);
+	read_unlock_irqrestore(&kmemleak_lock, flags);
+
+	/* check whether the object is still available */
+	if (object && !get_object(object))
+		object = NULL;
+	rcu_read_unlock();
+
+	return object;
+}
+
+/*
+ * Look up an object in the object search tree and remove it from both
+ * object_tree_root and object_list. The returned object's use_count should be
+ * at least 1, as initially set by create_object().
+ */
+static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	write_lock_irqsave(&kmemleak_lock, flags);
+	object = lookup_object(ptr, alias);
+	if (object) {
+		rb_erase(&object->rb_node, &object_tree_root);
+		list_del_rcu(&object->object_list);
+	}
+	write_unlock_irqrestore(&kmemleak_lock, flags);
+
+	return object;
+}
+
+/*
+ * Save stack trace to the given array of MAX_TRACE size.
+ */
+static int __save_stack_trace(unsigned long *trace)
+{
+	struct stack_trace stack_trace;
+
+	stack_trace.max_entries = MAX_TRACE;
+	stack_trace.nr_entries = 0;
+	stack_trace.entries = trace;
+	stack_trace.skip = 2;
+	save_stack_trace(&stack_trace);
+
+	return stack_trace.nr_entries;
+}
+
+/*
+ * Create the metadata (struct kmemleak_object) corresponding to an allocated
+ * memory block and add it to the object_list and object_tree_root.
+ */
+static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
+					     int min_count, gfp_t gfp)
+{
+	unsigned long flags;
+	struct kmemleak_object *object, *parent;
+	struct rb_node **link, *rb_parent;
+
+	object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
+	if (!object) {
+		pr_warning("Cannot allocate a kmemleak_object structure\n");
+		kmemleak_disable();
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&object->object_list);
+	INIT_LIST_HEAD(&object->gray_list);
+	INIT_HLIST_HEAD(&object->area_list);
+	spin_lock_init(&object->lock);
+	atomic_set(&object->use_count, 1);
+	object->flags = OBJECT_ALLOCATED;
+	object->pointer = ptr;
+	object->size = size;
+	object->min_count = min_count;
+	object->count = 0;			/* white color initially */
+	object->jiffies = jiffies;
+	object->checksum = 0;
+
+	/* task information */
+	if (in_irq()) {
+		object->pid = 0;
+		strncpy(object->comm, "hardirq", sizeof(object->comm));
+	} else if (in_softirq()) {
+		object->pid = 0;
+		strncpy(object->comm, "softirq", sizeof(object->comm));
+	} else {
+		object->pid = current->pid;
+		/*
+		 * There is a small chance of a race with set_task_comm(),
+		 * however using get_task_comm() here may cause locking
+		 * dependency issues with current->alloc_lock. In the worst
+		 * case, the command line is not correct.
+		 */
+		strncpy(object->comm, current->comm, sizeof(object->comm));
+	}
+
+	/* kernel backtrace */
+	object->trace_len = __save_stack_trace(object->trace);
+
+	write_lock_irqsave(&kmemleak_lock, flags);
+
+	min_addr = min(min_addr, ptr);
+	max_addr = max(max_addr, ptr + size);
+	link = &object_tree_root.rb_node;
+	rb_parent = NULL;
+	while (*link) {
+		rb_parent = *link;
+		parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
+		if (ptr + size <= parent->pointer)
+			link = &parent->rb_node.rb_left;
+		else if (parent->pointer + parent->size <= ptr)
+			link = &parent->rb_node.rb_right;
+		else {
+			kmemleak_stop("Cannot insert 0x%lx into the object "
+				      "search tree (overlaps existing)\n",
+				      ptr);
+			/*
+			 * No need for parent->lock here since "parent" cannot
+			 * be freed while the kmemleak_lock is held.
+			 */
+			dump_object_info(parent);
+			kmem_cache_free(object_cache, object);
+			object = NULL;
+			goto out;
+		}
+	}
+	rb_link_node(&object->rb_node, rb_parent, link);
+	rb_insert_color(&object->rb_node, &object_tree_root);
+
+	list_add_tail_rcu(&object->object_list, &object_list);
+out:
+	write_unlock_irqrestore(&kmemleak_lock, flags);
+	return object;
+}
+
+/*
+ * Mark the object as not allocated and schedule RCU freeing via put_object().
+ */
+static void __delete_object(struct kmemleak_object *object)
+{
+	unsigned long flags;
+
+	WARN_ON(!(object->flags & OBJECT_ALLOCATED));
+	WARN_ON(atomic_read(&object->use_count) < 1);
+
+	/*
+	 * Locking here also ensures that the corresponding memory block
+	 * cannot be freed when it is being scanned.
+	 */
+	spin_lock_irqsave(&object->lock, flags);
+	object->flags &= ~OBJECT_ALLOCATED;
+	spin_unlock_irqrestore(&object->lock, flags);
+	put_object(object);
+}
+
+/*
+ * Look up the metadata (struct kmemleak_object) corresponding to ptr and
+ * delete it.
+ */
+static void delete_object_full(unsigned long ptr)
+{
+	struct kmemleak_object *object;
+
+	object = find_and_remove_object(ptr, 0);
+	if (!object) {
+#ifdef DEBUG
+		kmemleak_warn("Freeing unknown object at 0x%08lx\n",
+			      ptr);
+#endif
+		return;
+	}
+	__delete_object(object);
+}
+
+/*
+ * Look up the metadata (struct kmemleak_object) corresponding to ptr and
+ * delete it. If the memory block is partially freed, the function may create
+ * additional metadata for the remaining parts of the block.
+ */
+static void delete_object_part(unsigned long ptr, size_t size)
+{
+	struct kmemleak_object *object;
+	unsigned long start, end;
+
+	object = find_and_remove_object(ptr, 1);
+	if (!object) {
+#ifdef DEBUG
+		kmemleak_warn("Partially freeing unknown object at 0x%08lx "
+			      "(size %zu)\n", ptr, size);
+#endif
+		return;
+	}
+
+	/*
+	 * Create one or two objects that may result from the memory block
+	 * split. Note that partial freeing is only done by free_bootmem() and
+	 * this happens before kmemleak_init() is called. The path below is
+	 * only executed during early log recording in kmemleak_init(), so
+	 * GFP_KERNEL is enough.
+	 */
+	start = object->pointer;
+	end = object->pointer + object->size;
+	if (ptr > start)
+		create_object(start, ptr - start, object->min_count,
+			      GFP_KERNEL);
+	if (ptr + size < end)
+		create_object(ptr + size, end - ptr - size, object->min_count,
+			      GFP_KERNEL);
+
+	__delete_object(object);
+}
+
+static void __paint_it(struct kmemleak_object *object, int color)
+{
+	object->min_count = color;
+	if (color == KMEMLEAK_BLACK)
+		object->flags |= OBJECT_NO_SCAN;
+}
+
+static void paint_it(struct kmemleak_object *object, int color)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&object->lock, flags);
+	__paint_it(object, color);
+	spin_unlock_irqrestore(&object->lock, flags);
+}
+
+static void paint_ptr(unsigned long ptr, int color)
+{
+	struct kmemleak_object *object;
+
+	object = find_and_get_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("Trying to color unknown object "
+			      "at 0x%08lx as %s\n", ptr,
+			      (color == KMEMLEAK_GREY) ? "Grey" :
+			      (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
+		return;
+	}
+	paint_it(object, color);
+	put_object(object);
+}
+
+/*
+ * Mark an object permanently as gray-colored so that it can no longer be
+ * reported as a leak. This is used in general to mark a false positive.
+ */
+static void make_gray_object(unsigned long ptr)
+{
+	paint_ptr(ptr, KMEMLEAK_GREY);
+}
+
+/*
+ * Mark the object as black-colored so that it is ignored from scans and
+ * reporting.
+ */
+static void make_black_object(unsigned long ptr)
+{
+	paint_ptr(ptr, KMEMLEAK_BLACK);
+}
+
+/*
+ * Add a scanning area to the object. If at least one such area is added,
+ * kmemleak will only scan these ranges rather than the whole memory block.
+ */
+static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+	struct kmemleak_scan_area *area;
+
+	object = find_and_get_object(ptr, 1);
+	if (!object) {
+		kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
+			      ptr);
+		return;
+	}
+
+	area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
+	if (!area) {
+		pr_warning("Cannot allocate a scan area\n");
+		goto out;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	if (size == SIZE_MAX) {
+		size = object->pointer + object->size - ptr;
+	} else if (ptr + size > object->pointer + object->size) {
+		kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
+		dump_object_info(object);
+		kmem_cache_free(scan_area_cache, area);
+		goto out_unlock;
+	}
+
+	INIT_HLIST_NODE(&area->node);
+	area->start = ptr;
+	area->size = size;
+
+	hlist_add_head(&area->node, &object->area_list);
+out_unlock:
+	spin_unlock_irqrestore(&object->lock, flags);
+out:
+	put_object(object);
+}
+
+/*
+ * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
+ * pointer. Such object will not be scanned by kmemleak but references to it
+ * are searched.
+ */
+static void object_no_scan(unsigned long ptr)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	object = find_and_get_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
+		return;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	object->flags |= OBJECT_NO_SCAN;
+	spin_unlock_irqrestore(&object->lock, flags);
+	put_object(object);
+}
+
+/*
+ * Log an early kmemleak_* call to the early_log buffer. These calls will be
+ * processed later once kmemleak is fully initialized.
+ */
+static void __init log_early(int op_type, const void *ptr, size_t size,
+			     int min_count)
+{
+	unsigned long flags;
+	struct early_log *log;
+
+	if (kmemleak_error) {
+		/* kmemleak stopped recording, just count the requests */
+		crt_early_log++;
+		return;
+	}
+
+	if (crt_early_log >= ARRAY_SIZE(early_log)) {
+		crt_early_log++;
+		kmemleak_disable();
+		return;
+	}
+
+	/*
+	 * There is no need for locking since the kernel is still in UP mode
+	 * at this stage. Disabling the IRQs is enough.
+	 */
+	local_irq_save(flags);
+	log = &early_log[crt_early_log];
+	log->op_type = op_type;
+	log->ptr = ptr;
+	log->size = size;
+	log->min_count = min_count;
+	log->trace_len = __save_stack_trace(log->trace);
+	crt_early_log++;
+	local_irq_restore(flags);
+}
+
+/*
+ * Log an early allocated block and populate the stack trace.
+ */
+static void early_alloc(struct early_log *log)
+{
+	struct kmemleak_object *object;
+	unsigned long flags;
+	int i;
+
+	if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
+		return;
+
+	/*
+	 * RCU locking needed to ensure object is not freed via put_object().
+	 */
+	rcu_read_lock();
+	object = create_object((unsigned long)log->ptr, log->size,
+			       log->min_count, GFP_ATOMIC);
+	if (!object)
+		goto out;
+	spin_lock_irqsave(&object->lock, flags);
+	for (i = 0; i < log->trace_len; i++)
+		object->trace[i] = log->trace[i];
+	object->trace_len = log->trace_len;
+	spin_unlock_irqrestore(&object->lock, flags);
+out:
+	rcu_read_unlock();
+}
+
+/*
+ * Log an early allocated block and populate the stack trace.
+ */
+static void early_alloc_percpu(struct early_log *log)
+{
+	unsigned int cpu;
+	const void __percpu *ptr = log->ptr;
+
+	for_each_possible_cpu(cpu) {
+		log->ptr = per_cpu_ptr(ptr, cpu);
+		early_alloc(log);
+	}
+}
+
+/**
+ * kmemleak_alloc - register a newly allocated object
+ * @ptr:	pointer to beginning of the object
+ * @size:	size of the object
+ * @min_count:	minimum number of references to this object. If during memory
+ *		scanning a number of references less than @min_count is found,
+ *		the object is reported as a memory leak. If @min_count is 0,
+ *		the object is never reported as a leak. If @min_count is -1,
+ *		the object is ignored (not scanned and not reported as a leak)
+ * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
+ *
+ * This function is called from the kernel allocators when a new object
+ * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
+ */
+void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
+			  gfp_t gfp)
+{
+	pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
+
+	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
+		create_object((unsigned long)ptr, size, min_count, gfp);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
+}
+EXPORT_SYMBOL_GPL(kmemleak_alloc);
+
+/**
+ * kmemleak_alloc_percpu - register a newly allocated __percpu object
+ * @ptr:	__percpu pointer to beginning of the object
+ * @size:	size of the object
+ * @gfp:	flags used for kmemleak internal memory allocations
+ *
+ * This function is called from the kernel percpu allocator when a new object
+ * (memory block) is allocated (alloc_percpu).
+ */
+void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
+				 gfp_t gfp)
+{
+	unsigned int cpu;
+
+	pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
+
+	/*
+	 * Percpu allocations are only scanned and not reported as leaks
+	 * (min_count is set to 0).
+	 */
+	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
+		for_each_possible_cpu(cpu)
+			create_object((unsigned long)per_cpu_ptr(ptr, cpu),
+				      size, 0, gfp);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
+
+/**
+ * kmemleak_free - unregister a previously registered object
+ * @ptr:	pointer to beginning of the object
+ *
+ * This function is called from the kernel allocators when an object (memory
+ * block) is freed (kmem_cache_free, kfree, vfree etc.).
+ */
+void __ref kmemleak_free(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
+		delete_object_full((unsigned long)ptr);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_FREE, ptr, 0, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_free);
+
+/**
+ * kmemleak_free_part - partially unregister a previously registered object
+ * @ptr:	pointer to the beginning or inside the object. This also
+ *		represents the start of the range to be freed
+ * @size:	size to be unregistered
+ *
+ * This function is called when only a part of a memory block is freed
+ * (usually from the bootmem allocator).
+ */
+void __ref kmemleak_free_part(const void *ptr, size_t size)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
+		delete_object_part((unsigned long)ptr, size);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_free_part);
+
+/**
+ * kmemleak_free_percpu - unregister a previously registered __percpu object
+ * @ptr:	__percpu pointer to beginning of the object
+ *
+ * This function is called from the kernel percpu allocator when an object
+ * (memory block) is freed (free_percpu).
+ */
+void __ref kmemleak_free_percpu(const void __percpu *ptr)
+{
+	unsigned int cpu;
+
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
+		for_each_possible_cpu(cpu)
+			delete_object_full((unsigned long)per_cpu_ptr(ptr,
+								      cpu));
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
+
+/**
+ * kmemleak_update_trace - update object allocation stack trace
+ * @ptr:	pointer to beginning of the object
+ *
+ * Override the object allocation stack trace for cases where the actual
+ * allocation place is not always useful.
+ */
+void __ref kmemleak_update_trace(const void *ptr)
+{
+	struct kmemleak_object *object;
+	unsigned long flags;
+
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
+		return;
+
+	object = find_and_get_object((unsigned long)ptr, 1);
+	if (!object) {
+#ifdef DEBUG
+		kmemleak_warn("Updating stack trace for unknown object at %p\n",
+			      ptr);
+#endif
+		return;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	object->trace_len = __save_stack_trace(object->trace);
+	spin_unlock_irqrestore(&object->lock, flags);
+
+	put_object(object);
+}
+EXPORT_SYMBOL(kmemleak_update_trace);
+
+/**
+ * kmemleak_not_leak - mark an allocated object as false positive
+ * @ptr:	pointer to beginning of the object
+ *
+ * Calling this function on an object will cause the memory block to no longer
+ * be reported as leak and always be scanned.
+ */
+void __ref kmemleak_not_leak(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
+		make_gray_object((unsigned long)ptr);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
+}
+EXPORT_SYMBOL(kmemleak_not_leak);
+
+/**
+ * kmemleak_ignore - ignore an allocated object
+ * @ptr:	pointer to beginning of the object
+ *
+ * Calling this function on an object will cause the memory block to be
+ * ignored (not scanned and not reported as a leak). This is usually done when
+ * it is known that the corresponding block is not a leak and does not contain
+ * any references to other allocated memory blocks.
+ */
+void __ref kmemleak_ignore(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
+		make_black_object((unsigned long)ptr);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
+}
+EXPORT_SYMBOL(kmemleak_ignore);
+
+/**
+ * kmemleak_scan_area - limit the range to be scanned in an allocated object
+ * @ptr:	pointer to beginning or inside the object. This also
+ *		represents the start of the scan area
+ * @size:	size of the scan area
+ * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
+ *
+ * This function is used when it is known that only certain parts of an object
+ * contain references to other objects. Kmemleak will only scan these areas
+ * reducing the number false negatives.
+ */
+void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
+		add_scan_area((unsigned long)ptr, size, gfp);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
+}
+EXPORT_SYMBOL(kmemleak_scan_area);
+
+/**
+ * kmemleak_no_scan - do not scan an allocated object
+ * @ptr:	pointer to beginning of the object
+ *
+ * This function notifies kmemleak not to scan the given memory block. Useful
+ * in situations where it is known that the given object does not contain any
+ * references to other objects. Kmemleak will not scan such objects reducing
+ * the number of false negatives.
+ */
+void __ref kmemleak_no_scan(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
+		object_no_scan((unsigned long)ptr);
+	else if (kmemleak_early_log)
+		log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
+}
+EXPORT_SYMBOL(kmemleak_no_scan);
+
+/*
+ * Update an object's checksum and return true if it was modified.
+ */
+static bool update_checksum(struct kmemleak_object *object)
+{
+	u32 old_csum = object->checksum;
+
+	if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
+		return false;
+
+	kasan_disable_current();
+	object->checksum = crc32(0, (void *)object->pointer, object->size);
+	kasan_enable_current();
+
+	return object->checksum != old_csum;
+}
+
+/*
+ * Memory scanning is a long process and it needs to be interruptable. This
+ * function checks whether such interrupt condition occurred.
+ */
+static int scan_should_stop(void)
+{
+	if (!kmemleak_enabled)
+		return 1;
+
+	/*
+	 * This function may be called from either process or kthread context,
+	 * hence the need to check for both stop conditions.
+	 */
+	if (current->mm)
+		return signal_pending(current);
+	else
+		return kthread_should_stop();
+
+	return 0;
+}
+
+/*
+ * Scan a memory block (exclusive range) for valid pointers and add those
+ * found to the gray list.
+ */
+static void scan_block(void *_start, void *_end,
+		       struct kmemleak_object *scanned)
+{
+	unsigned long *ptr;
+	unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
+	unsigned long *end = _end - (BYTES_PER_POINTER - 1);
+	unsigned long flags;
+
+	read_lock_irqsave(&kmemleak_lock, flags);
+	for (ptr = start; ptr < end; ptr++) {
+		struct kmemleak_object *object;
+		unsigned long pointer;
+
+		if (scan_should_stop())
+			break;
+
+		/* don't scan uninitialized memory */
+		if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
+						  BYTES_PER_POINTER))
+			continue;
+
+		kasan_disable_current();
+		pointer = *ptr;
+		kasan_enable_current();
+
+		if (pointer < min_addr || pointer >= max_addr)
+			continue;
+
+		/*
+		 * No need for get_object() here since we hold kmemleak_lock.
+		 * object->use_count cannot be dropped to 0 while the object
+		 * is still present in object_tree_root and object_list
+		 * (with updates protected by kmemleak_lock).
+		 */
+		object = lookup_object(pointer, 1);
+		if (!object)
+			continue;
+		if (object == scanned)
+			/* self referenced, ignore */
+			continue;
+
+		/*
+		 * Avoid the lockdep recursive warning on object->lock being
+		 * previously acquired in scan_object(). These locks are
+		 * enclosed by scan_mutex.
+		 */
+		spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
+		if (!color_white(object)) {
+			/* non-orphan, ignored or new */
+			spin_unlock(&object->lock);
+			continue;
+		}
+
+		/*
+		 * Increase the object's reference count (number of pointers
+		 * to the memory block). If this count reaches the required
+		 * minimum, the object's color will become gray and it will be
+		 * added to the gray_list.
+		 */
+		object->count++;
+		if (color_gray(object)) {
+			/* put_object() called when removing from gray_list */
+			WARN_ON(!get_object(object));
+			list_add_tail(&object->gray_list, &gray_list);
+		}
+		spin_unlock(&object->lock);
+	}
+	read_unlock_irqrestore(&kmemleak_lock, flags);
+}
+
+/*
+ * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
+ */
+static void scan_large_block(void *start, void *end)
+{
+	void *next;
+
+	while (start < end) {
+		next = min(start + MAX_SCAN_SIZE, end);
+		scan_block(start, next, NULL);
+		start = next;
+		cond_resched();
+	}
+}
+
+/*
+ * Scan a memory block corresponding to a kmemleak_object. A condition is
+ * that object->use_count >= 1.
+ */
+static void scan_object(struct kmemleak_object *object)
+{
+	struct kmemleak_scan_area *area;
+	unsigned long flags;
+
+	/*
+	 * Once the object->lock is acquired, the corresponding memory block
+	 * cannot be freed (the same lock is acquired in delete_object).
+	 */
+	spin_lock_irqsave(&object->lock, flags);
+	if (object->flags & OBJECT_NO_SCAN)
+		goto out;
+	if (!(object->flags & OBJECT_ALLOCATED))
+		/* already freed object */
+		goto out;
+	if (hlist_empty(&object->area_list)) {
+		void *start = (void *)object->pointer;
+		void *end = (void *)(object->pointer + object->size);
+		void *next;
+
+		do {
+			next = min(start + MAX_SCAN_SIZE, end);
+			scan_block(start, next, object);
+
+			start = next;
+			if (start >= end)
+				break;
+
+			spin_unlock_irqrestore(&object->lock, flags);
+			cond_resched();
+			spin_lock_irqsave(&object->lock, flags);
+		} while (object->flags & OBJECT_ALLOCATED);
+	} else
+		hlist_for_each_entry(area, &object->area_list, node)
+			scan_block((void *)area->start,
+				   (void *)(area->start + area->size),
+				   object);
+out:
+	spin_unlock_irqrestore(&object->lock, flags);
+}
+
+/*
+ * Scan the objects already referenced (gray objects). More objects will be
+ * referenced and, if there are no memory leaks, all the objects are scanned.
+ */
+static void scan_gray_list(void)
+{
+	struct kmemleak_object *object, *tmp;
+
+	/*
+	 * The list traversal is safe for both tail additions and removals
+	 * from inside the loop. The kmemleak objects cannot be freed from
+	 * outside the loop because their use_count was incremented.
+	 */
+	object = list_entry(gray_list.next, typeof(*object), gray_list);
+	while (&object->gray_list != &gray_list) {
+		cond_resched();
+
+		/* may add new objects to the list */
+		if (!scan_should_stop())
+			scan_object(object);
+
+		tmp = list_entry(object->gray_list.next, typeof(*object),
+				 gray_list);
+
+		/* remove the object from the list and release it */
+		list_del(&object->gray_list);
+		put_object(object);
+
+		object = tmp;
+	}
+	WARN_ON(!list_empty(&gray_list));
+}
+
+/*
+ * Scan data sections and all the referenced memory blocks allocated via the
+ * kernel's standard allocators. This function must be called with the
+ * scan_mutex held.
+ */
+static void kmemleak_scan(void)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+	int i;
+	int new_leaks = 0;
+
+	jiffies_last_scan = jiffies;
+
+	/* prepare the kmemleak_object's */
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		spin_lock_irqsave(&object->lock, flags);
+#ifdef DEBUG
+		/*
+		 * With a few exceptions there should be a maximum of
+		 * 1 reference to any object at this point.
+		 */
+		if (atomic_read(&object->use_count) > 1) {
+			pr_debug("object->use_count = %d\n",
+				 atomic_read(&object->use_count));
+			dump_object_info(object);
+		}
+#endif
+		/* reset the reference count (whiten the object) */
+		object->count = 0;
+		if (color_gray(object) && get_object(object))
+			list_add_tail(&object->gray_list, &gray_list);
+
+		spin_unlock_irqrestore(&object->lock, flags);
+	}
+	rcu_read_unlock();
+
+	/* data/bss scanning */
+	scan_large_block(_sdata, _edata);
+	scan_large_block(__bss_start, __bss_stop);
+
+#ifdef CONFIG_SMP
+	/* per-cpu sections scanning */
+	for_each_possible_cpu(i)
+		scan_large_block(__per_cpu_start + per_cpu_offset(i),
+				 __per_cpu_end + per_cpu_offset(i));
+#endif
+
+	/*
+	 * Struct page scanning for each node.
+	 */
+	get_online_mems();
+	for_each_online_node(i) {
+		unsigned long start_pfn = node_start_pfn(i);
+		unsigned long end_pfn = node_end_pfn(i);
+		unsigned long pfn;
+
+		for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+			struct page *page;
+
+			if (!pfn_valid(pfn))
+				continue;
+			page = pfn_to_page(pfn);
+			/* only scan if page is in use */
+			if (page_count(page) == 0)
+				continue;
+			scan_block(page, page + 1, NULL);
+		}
+	}
+	put_online_mems();
+
+	/*
+	 * Scanning the task stacks (may introduce false negatives).
+	 */
+	if (kmemleak_stack_scan) {
+		struct task_struct *p, *g;
+
+		read_lock(&tasklist_lock);
+		do_each_thread(g, p) {
+			scan_block(task_stack_page(p), task_stack_page(p) +
+				   THREAD_SIZE, NULL);
+		} while_each_thread(g, p);
+		read_unlock(&tasklist_lock);
+	}
+
+	/*
+	 * Scan the objects already referenced from the sections scanned
+	 * above.
+	 */
+	scan_gray_list();
+
+	/*
+	 * Check for new or unreferenced objects modified since the previous
+	 * scan and color them gray until the next scan.
+	 */
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		spin_lock_irqsave(&object->lock, flags);
+		if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
+		    && update_checksum(object) && get_object(object)) {
+			/* color it gray temporarily */
+			object->count = object->min_count;
+			list_add_tail(&object->gray_list, &gray_list);
+		}
+		spin_unlock_irqrestore(&object->lock, flags);
+	}
+	rcu_read_unlock();
+
+	/*
+	 * Re-scan the gray list for modified unreferenced objects.
+	 */
+	scan_gray_list();
+
+	/*
+	 * If scanning was stopped do not report any new unreferenced objects.
+	 */
+	if (scan_should_stop())
+		return;
+
+	/*
+	 * Scanning result reporting.
+	 */
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		spin_lock_irqsave(&object->lock, flags);
+		if (unreferenced_object(object) &&
+		    !(object->flags & OBJECT_REPORTED)) {
+			object->flags |= OBJECT_REPORTED;
+			new_leaks++;
+		}
+		spin_unlock_irqrestore(&object->lock, flags);
+	}
+	rcu_read_unlock();
+
+	if (new_leaks) {
+		kmemleak_found_leaks = true;
+
+		pr_info("%d new suspected memory leaks (see "
+			"/sys/kernel/debug/kmemleak)\n", new_leaks);
+	}
+
+}
+
+/*
+ * Thread function performing automatic memory scanning. Unreferenced objects
+ * at the end of a memory scan are reported but only the first time.
+ */
+static int kmemleak_scan_thread(void *arg)
+{
+	static int first_run = 1;
+
+	pr_info("Automatic memory scanning thread started\n");
+	set_user_nice(current, 10);
+
+	/*
+	 * Wait before the first scan to allow the system to fully initialize.
+	 */
+	if (first_run) {
+		first_run = 0;
+		ssleep(SECS_FIRST_SCAN);
+	}
+
+	while (!kthread_should_stop()) {
+		signed long timeout = jiffies_scan_wait;
+
+		mutex_lock(&scan_mutex);
+		kmemleak_scan();
+		mutex_unlock(&scan_mutex);
+
+		/* wait before the next scan */
+		while (timeout && !kthread_should_stop())
+			timeout = schedule_timeout_interruptible(timeout);
+	}
+
+	pr_info("Automatic memory scanning thread ended\n");
+
+	return 0;
+}
+
+/*
+ * Start the automatic memory scanning thread. This function must be called
+ * with the scan_mutex held.
+ */
+static void start_scan_thread(void)
+{
+	if (scan_thread)
+		return;
+	scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
+	if (IS_ERR(scan_thread)) {
+		pr_warning("Failed to create the scan thread\n");
+		scan_thread = NULL;
+	}
+}
+
+/*
+ * Stop the automatic memory scanning thread. This function must be called
+ * with the scan_mutex held.
+ */
+static void stop_scan_thread(void)
+{
+	if (scan_thread) {
+		kthread_stop(scan_thread);
+		scan_thread = NULL;
+	}
+}
+
+/*
+ * Iterate over the object_list and return the first valid object at or after
+ * the required position with its use_count incremented. The function triggers
+ * a memory scanning when the pos argument points to the first position.
+ */
+static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct kmemleak_object *object;
+	loff_t n = *pos;
+	int err;
+
+	err = mutex_lock_interruptible(&scan_mutex);
+	if (err < 0)
+		return ERR_PTR(err);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		if (n-- > 0)
+			continue;
+		if (get_object(object))
+			goto out;
+	}
+	object = NULL;
+out:
+	return object;
+}
+
+/*
+ * Return the next object in the object_list. The function decrements the
+ * use_count of the previous object and increases that of the next one.
+ */
+static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct kmemleak_object *prev_obj = v;
+	struct kmemleak_object *next_obj = NULL;
+	struct kmemleak_object *obj = prev_obj;
+
+	++(*pos);
+
+	list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
+		if (get_object(obj)) {
+			next_obj = obj;
+			break;
+		}
+	}
+
+	put_object(prev_obj);
+	return next_obj;
+}
+
+/*
+ * Decrement the use_count of the last object required, if any.
+ */
+static void kmemleak_seq_stop(struct seq_file *seq, void *v)
+{
+	if (!IS_ERR(v)) {
+		/*
+		 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
+		 * waiting was interrupted, so only release it if !IS_ERR.
+		 */
+		rcu_read_unlock();
+		mutex_unlock(&scan_mutex);
+		if (v)
+			put_object(v);
+	}
+}
+
+/*
+ * Print the information for an unreferenced object to the seq file.
+ */
+static int kmemleak_seq_show(struct seq_file *seq, void *v)
+{
+	struct kmemleak_object *object = v;
+	unsigned long flags;
+
+	spin_lock_irqsave(&object->lock, flags);
+	if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
+		print_unreferenced(seq, object);
+	spin_unlock_irqrestore(&object->lock, flags);
+	return 0;
+}
+
+static const struct seq_operations kmemleak_seq_ops = {
+	.start = kmemleak_seq_start,
+	.next  = kmemleak_seq_next,
+	.stop  = kmemleak_seq_stop,
+	.show  = kmemleak_seq_show,
+};
+
+static int kmemleak_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &kmemleak_seq_ops);
+}
+
+static int dump_str_object_info(const char *str)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+	unsigned long addr;
+
+	if (kstrtoul(str, 0, &addr))
+		return -EINVAL;
+	object = find_and_get_object(addr, 0);
+	if (!object) {
+		pr_info("Unknown object at 0x%08lx\n", addr);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	dump_object_info(object);
+	spin_unlock_irqrestore(&object->lock, flags);
+
+	put_object(object);
+	return 0;
+}
+
+/*
+ * We use grey instead of black to ensure we can do future scans on the same
+ * objects. If we did not do future scans these black objects could
+ * potentially contain references to newly allocated objects in the future and
+ * we'd end up with false positives.
+ */
+static void kmemleak_clear(void)
+{
+	struct kmemleak_object *object;
+	unsigned long flags;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		spin_lock_irqsave(&object->lock, flags);
+		if ((object->flags & OBJECT_REPORTED) &&
+		    unreferenced_object(object))
+			__paint_it(object, KMEMLEAK_GREY);
+		spin_unlock_irqrestore(&object->lock, flags);
+	}
+	rcu_read_unlock();
+
+	kmemleak_found_leaks = false;
+}
+
+static void __kmemleak_do_cleanup(void);
+
+/*
+ * File write operation to configure kmemleak at run-time. The following
+ * commands can be written to the /sys/kernel/debug/kmemleak file:
+ *   off	- disable kmemleak (irreversible)
+ *   stack=on	- enable the task stacks scanning
+ *   stack=off	- disable the tasks stacks scanning
+ *   scan=on	- start the automatic memory scanning thread
+ *   scan=off	- stop the automatic memory scanning thread
+ *   scan=...	- set the automatic memory scanning period in seconds (0 to
+ *		  disable it)
+ *   scan	- trigger a memory scan
+ *   clear	- mark all current reported unreferenced kmemleak objects as
+ *		  grey to ignore printing them, or free all kmemleak objects
+ *		  if kmemleak has been disabled.
+ *   dump=...	- dump information about the object found at the given address
+ */
+static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
+			      size_t size, loff_t *ppos)
+{
+	char buf[64];
+	int buf_size;
+	int ret;
+
+	buf_size = min(size, (sizeof(buf) - 1));
+	if (strncpy_from_user(buf, user_buf, buf_size) < 0)
+		return -EFAULT;
+	buf[buf_size] = 0;
+
+	ret = mutex_lock_interruptible(&scan_mutex);
+	if (ret < 0)
+		return ret;
+
+	if (strncmp(buf, "clear", 5) == 0) {
+		if (kmemleak_enabled)
+			kmemleak_clear();
+		else
+			__kmemleak_do_cleanup();
+		goto out;
+	}
+
+	if (!kmemleak_enabled) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (strncmp(buf, "off", 3) == 0)
+		kmemleak_disable();
+	else if (strncmp(buf, "stack=on", 8) == 0)
+		kmemleak_stack_scan = 1;
+	else if (strncmp(buf, "stack=off", 9) == 0)
+		kmemleak_stack_scan = 0;
+	else if (strncmp(buf, "scan=on", 7) == 0)
+		start_scan_thread();
+	else if (strncmp(buf, "scan=off", 8) == 0)
+		stop_scan_thread();
+	else if (strncmp(buf, "scan=", 5) == 0) {
+		unsigned long secs;
+
+		ret = kstrtoul(buf + 5, 0, &secs);
+		if (ret < 0)
+			goto out;
+		stop_scan_thread();
+		if (secs) {
+			jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
+			start_scan_thread();
+		}
+	} else if (strncmp(buf, "scan", 4) == 0)
+		kmemleak_scan();
+	else if (strncmp(buf, "dump=", 5) == 0)
+		ret = dump_str_object_info(buf + 5);
+	else
+		ret = -EINVAL;
+
+out:
+	mutex_unlock(&scan_mutex);
+	if (ret < 0)
+		return ret;
+
+	/* ignore the rest of the buffer, only one command at a time */
+	*ppos += size;
+	return size;
+}
+
+static const struct file_operations kmemleak_fops = {
+	.owner		= THIS_MODULE,
+	.open		= kmemleak_open,
+	.read		= seq_read,
+	.write		= kmemleak_write,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static void __kmemleak_do_cleanup(void)
+{
+	struct kmemleak_object *object;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list)
+		delete_object_full(object->pointer);
+	rcu_read_unlock();
+}
+
+/*
+ * Stop the memory scanning thread and free the kmemleak internal objects if
+ * no previous scan thread (otherwise, kmemleak may still have some useful
+ * information on memory leaks).
+ */
+static void kmemleak_do_cleanup(struct work_struct *work)
+{
+	stop_scan_thread();
+
+	/*
+	 * Once the scan thread has stopped, it is safe to no longer track
+	 * object freeing. Ordering of the scan thread stopping and the memory
+	 * accesses below is guaranteed by the kthread_stop() function.
+	 */
+	kmemleak_free_enabled = 0;
+
+	if (!kmemleak_found_leaks)
+		__kmemleak_do_cleanup();
+	else
+		pr_info("Kmemleak disabled without freeing internal data. "
+			"Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
+}
+
+static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
+
+/*
+ * Disable kmemleak. No memory allocation/freeing will be traced once this
+ * function is called. Disabling kmemleak is an irreversible operation.
+ */
+static void kmemleak_disable(void)
+{
+	/* atomically check whether it was already invoked */
+	if (cmpxchg(&kmemleak_error, 0, 1))
+		return;
+
+	/* stop any memory operation tracing */
+	kmemleak_enabled = 0;
+
+	/* check whether it is too early for a kernel thread */
+	if (kmemleak_initialized)
+		schedule_work(&cleanup_work);
+	else
+		kmemleak_free_enabled = 0;
+
+	pr_info("Kernel memory leak detector disabled\n");
+}
+
+/*
+ * Allow boot-time kmemleak disabling (enabled by default).
+ */
+static int kmemleak_boot_config(char *str)
+{
+	if (!str)
+		return -EINVAL;
+	if (strcmp(str, "off") == 0)
+		kmemleak_disable();
+	else if (strcmp(str, "on") == 0)
+		kmemleak_skip_disable = 1;
+	else
+		return -EINVAL;
+	return 0;
+}
+early_param("kmemleak", kmemleak_boot_config);
+
+static void __init print_log_trace(struct early_log *log)
+{
+	struct stack_trace trace;
+
+	trace.nr_entries = log->trace_len;
+	trace.entries = log->trace;
+
+	pr_notice("Early log backtrace:\n");
+	print_stack_trace(&trace, 2);
+}
+
+/*
+ * Kmemleak initialization.
+ */
+void __init kmemleak_init(void)
+{
+	int i;
+	unsigned long flags;
+
+#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
+	if (!kmemleak_skip_disable) {
+		kmemleak_early_log = 0;
+		kmemleak_disable();
+		return;
+	}
+#endif
+
+	jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
+	jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
+
+	object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
+	scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
+
+	if (crt_early_log > ARRAY_SIZE(early_log))
+		pr_warning("Early log buffer exceeded (%d), please increase "
+			   "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
+
+	/* the kernel is still in UP mode, so disabling the IRQs is enough */
+	local_irq_save(flags);
+	kmemleak_early_log = 0;
+	if (kmemleak_error) {
+		local_irq_restore(flags);
+		return;
+	} else {
+		kmemleak_enabled = 1;
+		kmemleak_free_enabled = 1;
+	}
+	local_irq_restore(flags);
+
+	/*
+	 * This is the point where tracking allocations is safe. Automatic
+	 * scanning is started during the late initcall. Add the early logged
+	 * callbacks to the kmemleak infrastructure.
+	 */
+	for (i = 0; i < crt_early_log; i++) {
+		struct early_log *log = &early_log[i];
+
+		switch (log->op_type) {
+		case KMEMLEAK_ALLOC:
+			early_alloc(log);
+			break;
+		case KMEMLEAK_ALLOC_PERCPU:
+			early_alloc_percpu(log);
+			break;
+		case KMEMLEAK_FREE:
+			kmemleak_free(log->ptr);
+			break;
+		case KMEMLEAK_FREE_PART:
+			kmemleak_free_part(log->ptr, log->size);
+			break;
+		case KMEMLEAK_FREE_PERCPU:
+			kmemleak_free_percpu(log->ptr);
+			break;
+		case KMEMLEAK_NOT_LEAK:
+			kmemleak_not_leak(log->ptr);
+			break;
+		case KMEMLEAK_IGNORE:
+			kmemleak_ignore(log->ptr);
+			break;
+		case KMEMLEAK_SCAN_AREA:
+			kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
+			break;
+		case KMEMLEAK_NO_SCAN:
+			kmemleak_no_scan(log->ptr);
+			break;
+		default:
+			kmemleak_warn("Unknown early log operation: %d\n",
+				      log->op_type);
+		}
+
+		if (kmemleak_warning) {
+			print_log_trace(log);
+			kmemleak_warning = 0;
+		}
+	}
+}
+
+/*
+ * Late initialization function.
+ */
+static int __init kmemleak_late_init(void)
+{
+	struct dentry *dentry;
+
+	kmemleak_initialized = 1;
+
+	if (kmemleak_error) {
+		/*
+		 * Some error occurred and kmemleak was disabled. There is a
+		 * small chance that kmemleak_disable() was called immediately
+		 * after setting kmemleak_initialized and we may end up with
+		 * two clean-up threads but serialized by scan_mutex.
+		 */
+		schedule_work(&cleanup_work);
+		return -ENOMEM;
+	}
+
+	dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
+				     &kmemleak_fops);
+	if (!dentry)
+		pr_warning("Failed to create the debugfs kmemleak file\n");
+	mutex_lock(&scan_mutex);
+	start_scan_thread();
+	mutex_unlock(&scan_mutex);
+
+	pr_info("Kernel memory leak detector initialized\n");
+
+	return 0;
+}
+late_initcall(kmemleak_late_init);
diff --git a/mm/ksm.c b/mm/ksm.c
new file mode 100644
index 0000000..2f028e6
--- /dev/null
+++ b/mm/ksm.c
@@ -0,0 +1,2363 @@
+/*
+ * Memory merging support.
+ *
+ * This code enables dynamic sharing of identical pages found in different
+ * memory areas, even if they are not shared by fork()
+ *
+ * Copyright (C) 2008-2009 Red Hat, Inc.
+ * Authors:
+ *	Izik Eidus
+ *	Andrea Arcangeli
+ *	Chris Wright
+ *	Hugh Dickins
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/mman.h>
+#include <linux/sched.h>
+#include <linux/rwsem.h>
+#include <linux/pagemap.h>
+#include <linux/rmap.h>
+#include <linux/spinlock.h>
+#include <linux/jhash.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/wait.h>
+#include <linux/slab.h>
+#include <linux/rbtree.h>
+#include <linux/memory.h>
+#include <linux/mmu_notifier.h>
+#include <linux/swap.h>
+#include <linux/ksm.h>
+#include <linux/hashtable.h>
+#include <linux/freezer.h>
+#include <linux/oom.h>
+#include <linux/numa.h>
+
+#include <asm/tlbflush.h>
+#include "internal.h"
+
+#ifdef CONFIG_NUMA
+#define NUMA(x)		(x)
+#define DO_NUMA(x)	do { (x); } while (0)
+#else
+#define NUMA(x)		(0)
+#define DO_NUMA(x)	do { } while (0)
+#endif
+
+/*
+ * A few notes about the KSM scanning process,
+ * to make it easier to understand the data structures below:
+ *
+ * In order to reduce excessive scanning, KSM sorts the memory pages by their
+ * contents into a data structure that holds pointers to the pages' locations.
+ *
+ * Since the contents of the pages may change at any moment, KSM cannot just
+ * insert the pages into a normal sorted tree and expect it to find anything.
+ * Therefore KSM uses two data structures - the stable and the unstable tree.
+ *
+ * The stable tree holds pointers to all the merged pages (ksm pages), sorted
+ * by their contents.  Because each such page is write-protected, searching on
+ * this tree is fully assured to be working (except when pages are unmapped),
+ * and therefore this tree is called the stable tree.
+ *
+ * In addition to the stable tree, KSM uses a second data structure called the
+ * unstable tree: this tree holds pointers to pages which have been found to
+ * be "unchanged for a period of time".  The unstable tree sorts these pages
+ * by their contents, but since they are not write-protected, KSM cannot rely
+ * upon the unstable tree to work correctly - the unstable tree is liable to
+ * be corrupted as its contents are modified, and so it is called unstable.
+ *
+ * KSM solves this problem by several techniques:
+ *
+ * 1) The unstable tree is flushed every time KSM completes scanning all
+ *    memory areas, and then the tree is rebuilt again from the beginning.
+ * 2) KSM will only insert into the unstable tree, pages whose hash value
+ *    has not changed since the previous scan of all memory areas.
+ * 3) The unstable tree is a RedBlack Tree - so its balancing is based on the
+ *    colors of the nodes and not on their contents, assuring that even when
+ *    the tree gets "corrupted" it won't get out of balance, so scanning time
+ *    remains the same (also, searching and inserting nodes in an rbtree uses
+ *    the same algorithm, so we have no overhead when we flush and rebuild).
+ * 4) KSM never flushes the stable tree, which means that even if it were to
+ *    take 10 attempts to find a page in the unstable tree, once it is found,
+ *    it is secured in the stable tree.  (When we scan a new page, we first
+ *    compare it against the stable tree, and then against the unstable tree.)
+ *
+ * If the merge_across_nodes tunable is unset, then KSM maintains multiple
+ * stable trees and multiple unstable trees: one of each for each NUMA node.
+ */
+
+/**
+ * struct mm_slot - ksm information per mm that is being scanned
+ * @link: link to the mm_slots hash list
+ * @mm_list: link into the mm_slots list, rooted in ksm_mm_head
+ * @rmap_list: head for this mm_slot's singly-linked list of rmap_items
+ * @mm: the mm that this information is valid for
+ */
+struct mm_slot {
+	struct hlist_node link;
+	struct list_head mm_list;
+	struct rmap_item *rmap_list;
+	struct mm_struct *mm;
+};
+
+/**
+ * struct ksm_scan - cursor for scanning
+ * @mm_slot: the current mm_slot we are scanning
+ * @address: the next address inside that to be scanned
+ * @rmap_list: link to the next rmap to be scanned in the rmap_list
+ * @seqnr: count of completed full scans (needed when removing unstable node)
+ *
+ * There is only the one ksm_scan instance of this cursor structure.
+ */
+struct ksm_scan {
+	struct mm_slot *mm_slot;
+	unsigned long address;
+	struct rmap_item **rmap_list;
+	unsigned long seqnr;
+};
+
+/**
+ * struct stable_node - node of the stable rbtree
+ * @node: rb node of this ksm page in the stable tree
+ * @head: (overlaying parent) &migrate_nodes indicates temporarily on that list
+ * @list: linked into migrate_nodes, pending placement in the proper node tree
+ * @hlist: hlist head of rmap_items using this ksm page
+ * @kpfn: page frame number of this ksm page (perhaps temporarily on wrong nid)
+ * @nid: NUMA node id of stable tree in which linked (may not match kpfn)
+ */
+struct stable_node {
+	union {
+		struct rb_node node;	/* when node of stable tree */
+		struct {		/* when listed for migration */
+			struct list_head *head;
+			struct list_head list;
+		};
+	};
+	struct hlist_head hlist;
+	unsigned long kpfn;
+#ifdef CONFIG_NUMA
+	int nid;
+#endif
+};
+
+/**
+ * struct rmap_item - reverse mapping item for virtual addresses
+ * @rmap_list: next rmap_item in mm_slot's singly-linked rmap_list
+ * @anon_vma: pointer to anon_vma for this mm,address, when in stable tree
+ * @nid: NUMA node id of unstable tree in which linked (may not match page)
+ * @mm: the memory structure this rmap_item is pointing into
+ * @address: the virtual address this rmap_item tracks (+ flags in low bits)
+ * @oldchecksum: previous checksum of the page at that virtual address
+ * @node: rb node of this rmap_item in the unstable tree
+ * @head: pointer to stable_node heading this list in the stable tree
+ * @hlist: link into hlist of rmap_items hanging off that stable_node
+ */
+struct rmap_item {
+	struct rmap_item *rmap_list;
+	union {
+		struct anon_vma *anon_vma;	/* when stable */
+#ifdef CONFIG_NUMA
+		int nid;		/* when node of unstable tree */
+#endif
+	};
+	struct mm_struct *mm;
+	unsigned long address;		/* + low bits used for flags below */
+	unsigned int oldchecksum;	/* when unstable */
+	union {
+		struct rb_node node;	/* when node of unstable tree */
+		struct {		/* when listed from stable tree */
+			struct stable_node *head;
+			struct hlist_node hlist;
+		};
+	};
+};
+
+#define SEQNR_MASK	0x0ff	/* low bits of unstable tree seqnr */
+#define UNSTABLE_FLAG	0x100	/* is a node of the unstable tree */
+#define STABLE_FLAG	0x200	/* is listed from the stable tree */
+
+/* The stable and unstable tree heads */
+static struct rb_root one_stable_tree[1] = { RB_ROOT };
+static struct rb_root one_unstable_tree[1] = { RB_ROOT };
+static struct rb_root *root_stable_tree = one_stable_tree;
+static struct rb_root *root_unstable_tree = one_unstable_tree;
+
+/* Recently migrated nodes of stable tree, pending proper placement */
+static LIST_HEAD(migrate_nodes);
+
+#define MM_SLOTS_HASH_BITS 10
+static DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
+
+static struct mm_slot ksm_mm_head = {
+	.mm_list = LIST_HEAD_INIT(ksm_mm_head.mm_list),
+};
+static struct ksm_scan ksm_scan = {
+	.mm_slot = &ksm_mm_head,
+};
+
+static struct kmem_cache *rmap_item_cache;
+static struct kmem_cache *stable_node_cache;
+static struct kmem_cache *mm_slot_cache;
+
+/* The number of nodes in the stable tree */
+static unsigned long ksm_pages_shared;
+
+/* The number of page slots additionally sharing those nodes */
+static unsigned long ksm_pages_sharing;
+
+/* The number of nodes in the unstable tree */
+static unsigned long ksm_pages_unshared;
+
+/* The number of rmap_items in use: to calculate pages_volatile */
+static unsigned long ksm_rmap_items;
+
+/* Number of pages ksmd should scan in one batch */
+static unsigned int ksm_thread_pages_to_scan = 100;
+
+/* Milliseconds ksmd should sleep between batches */
+static unsigned int ksm_thread_sleep_millisecs = 20;
+
+#ifdef CONFIG_NUMA
+/* Zeroed when merging across nodes is not allowed */
+static unsigned int ksm_merge_across_nodes = 1;
+static int ksm_nr_node_ids = 1;
+#else
+#define ksm_merge_across_nodes	1U
+#define ksm_nr_node_ids		1
+#endif
+
+#define KSM_RUN_STOP	0
+#define KSM_RUN_MERGE	1
+#define KSM_RUN_UNMERGE	2
+#define KSM_RUN_OFFLINE	4
+static unsigned long ksm_run = KSM_RUN_STOP;
+static void wait_while_offlining(void);
+
+static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait);
+static DEFINE_MUTEX(ksm_thread_mutex);
+static DEFINE_SPINLOCK(ksm_mmlist_lock);
+
+#define KSM_KMEM_CACHE(__struct, __flags) kmem_cache_create("ksm_"#__struct,\
+		sizeof(struct __struct), __alignof__(struct __struct),\
+		(__flags), NULL)
+
+static int __init ksm_slab_init(void)
+{
+	rmap_item_cache = KSM_KMEM_CACHE(rmap_item, 0);
+	if (!rmap_item_cache)
+		goto out;
+
+	stable_node_cache = KSM_KMEM_CACHE(stable_node, 0);
+	if (!stable_node_cache)
+		goto out_free1;
+
+	mm_slot_cache = KSM_KMEM_CACHE(mm_slot, 0);
+	if (!mm_slot_cache)
+		goto out_free2;
+
+	return 0;
+
+out_free2:
+	kmem_cache_destroy(stable_node_cache);
+out_free1:
+	kmem_cache_destroy(rmap_item_cache);
+out:
+	return -ENOMEM;
+}
+
+static void __init ksm_slab_free(void)
+{
+	kmem_cache_destroy(mm_slot_cache);
+	kmem_cache_destroy(stable_node_cache);
+	kmem_cache_destroy(rmap_item_cache);
+	mm_slot_cache = NULL;
+}
+
+static inline struct rmap_item *alloc_rmap_item(void)
+{
+	struct rmap_item *rmap_item;
+
+	rmap_item = kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL |
+						__GFP_NORETRY | __GFP_NOWARN);
+	if (rmap_item)
+		ksm_rmap_items++;
+	return rmap_item;
+}
+
+static inline void free_rmap_item(struct rmap_item *rmap_item)
+{
+	ksm_rmap_items--;
+	rmap_item->mm = NULL;	/* debug safety */
+	kmem_cache_free(rmap_item_cache, rmap_item);
+}
+
+static inline struct stable_node *alloc_stable_node(void)
+{
+	return kmem_cache_alloc(stable_node_cache, GFP_KERNEL);
+}
+
+static inline void free_stable_node(struct stable_node *stable_node)
+{
+	kmem_cache_free(stable_node_cache, stable_node);
+}
+
+static inline struct mm_slot *alloc_mm_slot(void)
+{
+	if (!mm_slot_cache)	/* initialization failed */
+		return NULL;
+	return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
+}
+
+static inline void free_mm_slot(struct mm_slot *mm_slot)
+{
+	kmem_cache_free(mm_slot_cache, mm_slot);
+}
+
+static struct mm_slot *get_mm_slot(struct mm_struct *mm)
+{
+	struct mm_slot *slot;
+
+	hash_for_each_possible(mm_slots_hash, slot, link, (unsigned long)mm)
+		if (slot->mm == mm)
+			return slot;
+
+	return NULL;
+}
+
+static void insert_to_mm_slots_hash(struct mm_struct *mm,
+				    struct mm_slot *mm_slot)
+{
+	mm_slot->mm = mm;
+	hash_add(mm_slots_hash, &mm_slot->link, (unsigned long)mm);
+}
+
+/*
+ * ksmd, and unmerge_and_remove_all_rmap_items(), must not touch an mm's
+ * page tables after it has passed through ksm_exit() - which, if necessary,
+ * takes mmap_sem briefly to serialize against them.  ksm_exit() does not set
+ * a special flag: they can just back out as soon as mm_users goes to zero.
+ * ksm_test_exit() is used throughout to make this test for exit: in some
+ * places for correctness, in some places just to avoid unnecessary work.
+ */
+static inline bool ksm_test_exit(struct mm_struct *mm)
+{
+	return atomic_read(&mm->mm_users) == 0;
+}
+
+/*
+ * We use break_ksm to break COW on a ksm page: it's a stripped down
+ *
+ *	if (get_user_pages(current, mm, addr, 1, 1, 1, &page, NULL) == 1)
+ *		put_page(page);
+ *
+ * but taking great care only to touch a ksm page, in a VM_MERGEABLE vma,
+ * in case the application has unmapped and remapped mm,addr meanwhile.
+ * Could a ksm page appear anywhere else?  Actually yes, in a VM_PFNMAP
+ * mmap of /dev/mem or /dev/kmem, where we would not want to touch it.
+ */
+static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
+{
+	struct page *page;
+	int ret = 0;
+
+	do {
+		cond_resched();
+		page = follow_page(vma, addr, FOLL_GET | FOLL_MIGRATION);
+		if (IS_ERR_OR_NULL(page))
+			break;
+		if (PageKsm(page))
+			ret = handle_mm_fault(vma->vm_mm, vma, addr,
+							FAULT_FLAG_WRITE);
+		else
+			ret = VM_FAULT_WRITE;
+		put_page(page);
+	} while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | VM_FAULT_OOM)));
+	/*
+	 * We must loop because handle_mm_fault() may back out if there's
+	 * any difficulty e.g. if pte accessed bit gets updated concurrently.
+	 *
+	 * VM_FAULT_WRITE is what we have been hoping for: it indicates that
+	 * COW has been broken, even if the vma does not permit VM_WRITE;
+	 * but note that a concurrent fault might break PageKsm for us.
+	 *
+	 * VM_FAULT_SIGBUS could occur if we race with truncation of the
+	 * backing file, which also invalidates anonymous pages: that's
+	 * okay, that truncation will have unmapped the PageKsm for us.
+	 *
+	 * VM_FAULT_OOM: at the time of writing (late July 2009), setting
+	 * aside mem_cgroup limits, VM_FAULT_OOM would only be set if the
+	 * current task has TIF_MEMDIE set, and will be OOM killed on return
+	 * to user; and ksmd, having no mm, would never be chosen for that.
+	 *
+	 * But if the mm is in a limited mem_cgroup, then the fault may fail
+	 * with VM_FAULT_OOM even if the current task is not TIF_MEMDIE; and
+	 * even ksmd can fail in this way - though it's usually breaking ksm
+	 * just to undo a merge it made a moment before, so unlikely to oom.
+	 *
+	 * That's a pity: we might therefore have more kernel pages allocated
+	 * than we're counting as nodes in the stable tree; but ksm_do_scan
+	 * will retry to break_cow on each pass, so should recover the page
+	 * in due course.  The important thing is to not let VM_MERGEABLE
+	 * be cleared while any such pages might remain in the area.
+	 */
+	return (ret & VM_FAULT_OOM) ? -ENOMEM : 0;
+}
+
+static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm,
+		unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	if (ksm_test_exit(mm))
+		return NULL;
+	vma = find_vma(mm, addr);
+	if (!vma || vma->vm_start > addr)
+		return NULL;
+	if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
+		return NULL;
+	return vma;
+}
+
+static void break_cow(struct rmap_item *rmap_item)
+{
+	struct mm_struct *mm = rmap_item->mm;
+	unsigned long addr = rmap_item->address;
+	struct vm_area_struct *vma;
+
+	/*
+	 * It is not an accident that whenever we want to break COW
+	 * to undo, we also need to drop a reference to the anon_vma.
+	 */
+	put_anon_vma(rmap_item->anon_vma);
+
+	down_read(&mm->mmap_sem);
+	vma = find_mergeable_vma(mm, addr);
+	if (vma)
+		break_ksm(vma, addr);
+	up_read(&mm->mmap_sem);
+}
+
+static struct page *page_trans_compound_anon(struct page *page)
+{
+	if (PageTransCompound(page)) {
+		struct page *head = compound_head(page);
+		/*
+		 * head may actually be splitted and freed from under
+		 * us but it's ok here.
+		 */
+		if (PageAnon(head))
+			return head;
+	}
+	return NULL;
+}
+
+static struct page *get_mergeable_page(struct rmap_item *rmap_item)
+{
+	struct mm_struct *mm = rmap_item->mm;
+	unsigned long addr = rmap_item->address;
+	struct vm_area_struct *vma;
+	struct page *page;
+
+	down_read(&mm->mmap_sem);
+	vma = find_mergeable_vma(mm, addr);
+	if (!vma)
+		goto out;
+
+	page = follow_page(vma, addr, FOLL_GET);
+	if (IS_ERR_OR_NULL(page))
+		goto out;
+	if (PageAnon(page) || page_trans_compound_anon(page)) {
+		flush_anon_page(vma, page, addr);
+		flush_dcache_page(page);
+	} else {
+		put_page(page);
+out:
+		page = NULL;
+	}
+	up_read(&mm->mmap_sem);
+	return page;
+}
+
+/*
+ * This helper is used for getting right index into array of tree roots.
+ * When merge_across_nodes knob is set to 1, there are only two rb-trees for
+ * stable and unstable pages from all nodes with roots in index 0. Otherwise,
+ * every node has its own stable and unstable tree.
+ */
+static inline int get_kpfn_nid(unsigned long kpfn)
+{
+	return ksm_merge_across_nodes ? 0 : NUMA(pfn_to_nid(kpfn));
+}
+
+static void remove_node_from_stable_tree(struct stable_node *stable_node)
+{
+	struct rmap_item *rmap_item;
+
+	hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
+		if (rmap_item->hlist.next)
+			ksm_pages_sharing--;
+		else
+			ksm_pages_shared--;
+		put_anon_vma(rmap_item->anon_vma);
+		rmap_item->address &= PAGE_MASK;
+		cond_resched();
+	}
+
+	if (stable_node->head == &migrate_nodes)
+		list_del(&stable_node->list);
+	else
+		rb_erase(&stable_node->node,
+			 root_stable_tree + NUMA(stable_node->nid));
+	free_stable_node(stable_node);
+}
+
+/*
+ * get_ksm_page: checks if the page indicated by the stable node
+ * is still its ksm page, despite having held no reference to it.
+ * In which case we can trust the content of the page, and it
+ * returns the gotten page; but if the page has now been zapped,
+ * remove the stale node from the stable tree and return NULL.
+ * But beware, the stable node's page might be being migrated.
+ *
+ * You would expect the stable_node to hold a reference to the ksm page.
+ * But if it increments the page's count, swapping out has to wait for
+ * ksmd to come around again before it can free the page, which may take
+ * seconds or even minutes: much too unresponsive.  So instead we use a
+ * "keyhole reference": access to the ksm page from the stable node peeps
+ * out through its keyhole to see if that page still holds the right key,
+ * pointing back to this stable node.  This relies on freeing a PageAnon
+ * page to reset its page->mapping to NULL, and relies on no other use of
+ * a page to put something that might look like our key in page->mapping.
+ * is on its way to being freed; but it is an anomaly to bear in mind.
+ */
+static struct page *get_ksm_page(struct stable_node *stable_node, bool lock_it)
+{
+	struct page *page;
+	void *expected_mapping;
+	unsigned long kpfn;
+
+	expected_mapping = (void *)stable_node +
+				(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
+again:
+	kpfn = READ_ONCE(stable_node->kpfn);
+	page = pfn_to_page(kpfn);
+
+	/*
+	 * page is computed from kpfn, so on most architectures reading
+	 * page->mapping is naturally ordered after reading node->kpfn,
+	 * but on Alpha we need to be more careful.
+	 */
+	smp_read_barrier_depends();
+	if (READ_ONCE(page->mapping) != expected_mapping)
+		goto stale;
+
+	/*
+	 * We cannot do anything with the page while its refcount is 0.
+	 * Usually 0 means free, or tail of a higher-order page: in which
+	 * case this node is no longer referenced, and should be freed;
+	 * however, it might mean that the page is under page_freeze_refs().
+	 * The __remove_mapping() case is easy, again the node is now stale;
+	 * but if page is swapcache in migrate_page_move_mapping(), it might
+	 * still be our page, in which case it's essential to keep the node.
+	 */
+	while (!get_page_unless_zero(page)) {
+		/*
+		 * Another check for page->mapping != expected_mapping would
+		 * work here too.  We have chosen the !PageSwapCache test to
+		 * optimize the common case, when the page is or is about to
+		 * be freed: PageSwapCache is cleared (under spin_lock_irq)
+		 * in the freeze_refs section of __remove_mapping(); but Anon
+		 * page->mapping reset to NULL later, in free_pages_prepare().
+		 */
+		if (!PageSwapCache(page))
+			goto stale;
+		cpu_relax();
+	}
+
+	if (READ_ONCE(page->mapping) != expected_mapping) {
+		put_page(page);
+		goto stale;
+	}
+
+	if (lock_it) {
+		lock_page(page);
+		if (READ_ONCE(page->mapping) != expected_mapping) {
+			unlock_page(page);
+			put_page(page);
+			goto stale;
+		}
+	}
+	return page;
+
+stale:
+	/*
+	 * We come here from above when page->mapping or !PageSwapCache
+	 * suggests that the node is stale; but it might be under migration.
+	 * We need smp_rmb(), matching the smp_wmb() in ksm_migrate_page(),
+	 * before checking whether node->kpfn has been changed.
+	 */
+	smp_rmb();
+	if (READ_ONCE(stable_node->kpfn) != kpfn)
+		goto again;
+	remove_node_from_stable_tree(stable_node);
+	return NULL;
+}
+
+/*
+ * Removing rmap_item from stable or unstable tree.
+ * This function will clean the information from the stable/unstable tree.
+ */
+static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
+{
+	if (rmap_item->address & STABLE_FLAG) {
+		struct stable_node *stable_node;
+		struct page *page;
+
+		stable_node = rmap_item->head;
+		page = get_ksm_page(stable_node, true);
+		if (!page)
+			goto out;
+
+		hlist_del(&rmap_item->hlist);
+		unlock_page(page);
+		put_page(page);
+
+		if (!hlist_empty(&stable_node->hlist))
+			ksm_pages_sharing--;
+		else
+			ksm_pages_shared--;
+
+		put_anon_vma(rmap_item->anon_vma);
+		rmap_item->address &= PAGE_MASK;
+
+	} else if (rmap_item->address & UNSTABLE_FLAG) {
+		unsigned char age;
+		/*
+		 * Usually ksmd can and must skip the rb_erase, because
+		 * root_unstable_tree was already reset to RB_ROOT.
+		 * But be careful when an mm is exiting: do the rb_erase
+		 * if this rmap_item was inserted by this scan, rather
+		 * than left over from before.
+		 */
+		age = (unsigned char)(ksm_scan.seqnr - rmap_item->address);
+		BUG_ON(age > 1);
+		if (!age)
+			rb_erase(&rmap_item->node,
+				 root_unstable_tree + NUMA(rmap_item->nid));
+		ksm_pages_unshared--;
+		rmap_item->address &= PAGE_MASK;
+	}
+out:
+	cond_resched();		/* we're called from many long loops */
+}
+
+static void remove_trailing_rmap_items(struct mm_slot *mm_slot,
+				       struct rmap_item **rmap_list)
+{
+	while (*rmap_list) {
+		struct rmap_item *rmap_item = *rmap_list;
+		*rmap_list = rmap_item->rmap_list;
+		remove_rmap_item_from_tree(rmap_item);
+		free_rmap_item(rmap_item);
+	}
+}
+
+/*
+ * Though it's very tempting to unmerge rmap_items from stable tree rather
+ * than check every pte of a given vma, the locking doesn't quite work for
+ * that - an rmap_item is assigned to the stable tree after inserting ksm
+ * page and upping mmap_sem.  Nor does it fit with the way we skip dup'ing
+ * rmap_items from parent to child at fork time (so as not to waste time
+ * if exit comes before the next scan reaches it).
+ *
+ * Similarly, although we'd like to remove rmap_items (so updating counts
+ * and freeing memory) when unmerging an area, it's easier to leave that
+ * to the next pass of ksmd - consider, for example, how ksmd might be
+ * in cmp_and_merge_page on one of the rmap_items we would be removing.
+ */
+static int unmerge_ksm_pages(struct vm_area_struct *vma,
+			     unsigned long start, unsigned long end)
+{
+	unsigned long addr;
+	int err = 0;
+
+	for (addr = start; addr < end && !err; addr += PAGE_SIZE) {
+		if (ksm_test_exit(vma->vm_mm))
+			break;
+		if (signal_pending(current))
+			err = -ERESTARTSYS;
+		else
+			err = break_ksm(vma, addr);
+	}
+	return err;
+}
+
+#ifdef CONFIG_SYSFS
+/*
+ * Only called through the sysfs control interface:
+ */
+static int remove_stable_node(struct stable_node *stable_node)
+{
+	struct page *page;
+	int err;
+
+	page = get_ksm_page(stable_node, true);
+	if (!page) {
+		/*
+		 * get_ksm_page did remove_node_from_stable_tree itself.
+		 */
+		return 0;
+	}
+
+	if (WARN_ON_ONCE(page_mapped(page))) {
+		/*
+		 * This should not happen: but if it does, just refuse to let
+		 * merge_across_nodes be switched - there is no need to panic.
+		 */
+		err = -EBUSY;
+	} else {
+		/*
+		 * The stable node did not yet appear stale to get_ksm_page(),
+		 * since that allows for an unmapped ksm page to be recognized
+		 * right up until it is freed; but the node is safe to remove.
+		 * This page might be in a pagevec waiting to be freed,
+		 * or it might be PageSwapCache (perhaps under writeback),
+		 * or it might have been removed from swapcache a moment ago.
+		 */
+		set_page_stable_node(page, NULL);
+		remove_node_from_stable_tree(stable_node);
+		err = 0;
+	}
+
+	unlock_page(page);
+	put_page(page);
+	return err;
+}
+
+static int remove_all_stable_nodes(void)
+{
+	struct stable_node *stable_node;
+	struct list_head *this, *next;
+	int nid;
+	int err = 0;
+
+	for (nid = 0; nid < ksm_nr_node_ids; nid++) {
+		while (root_stable_tree[nid].rb_node) {
+			stable_node = rb_entry(root_stable_tree[nid].rb_node,
+						struct stable_node, node);
+			if (remove_stable_node(stable_node)) {
+				err = -EBUSY;
+				break;	/* proceed to next nid */
+			}
+			cond_resched();
+		}
+	}
+	list_for_each_safe(this, next, &migrate_nodes) {
+		stable_node = list_entry(this, struct stable_node, list);
+		if (remove_stable_node(stable_node))
+			err = -EBUSY;
+		cond_resched();
+	}
+	return err;
+}
+
+static int unmerge_and_remove_all_rmap_items(void)
+{
+	struct mm_slot *mm_slot;
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	int err = 0;
+
+	spin_lock(&ksm_mmlist_lock);
+	ksm_scan.mm_slot = list_entry(ksm_mm_head.mm_list.next,
+						struct mm_slot, mm_list);
+	spin_unlock(&ksm_mmlist_lock);
+
+	for (mm_slot = ksm_scan.mm_slot;
+			mm_slot != &ksm_mm_head; mm_slot = ksm_scan.mm_slot) {
+		mm = mm_slot->mm;
+		down_read(&mm->mmap_sem);
+		for (vma = mm->mmap; vma; vma = vma->vm_next) {
+			if (ksm_test_exit(mm))
+				break;
+			if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
+				continue;
+			err = unmerge_ksm_pages(vma,
+						vma->vm_start, vma->vm_end);
+			if (err)
+				goto error;
+		}
+
+		remove_trailing_rmap_items(mm_slot, &mm_slot->rmap_list);
+
+		spin_lock(&ksm_mmlist_lock);
+		ksm_scan.mm_slot = list_entry(mm_slot->mm_list.next,
+						struct mm_slot, mm_list);
+		if (ksm_test_exit(mm)) {
+			hash_del(&mm_slot->link);
+			list_del(&mm_slot->mm_list);
+			spin_unlock(&ksm_mmlist_lock);
+
+			free_mm_slot(mm_slot);
+			clear_bit(MMF_VM_MERGEABLE, &mm->flags);
+			up_read(&mm->mmap_sem);
+			mmdrop(mm);
+		} else {
+			spin_unlock(&ksm_mmlist_lock);
+			up_read(&mm->mmap_sem);
+		}
+	}
+
+	/* Clean up stable nodes, but don't worry if some are still busy */
+	remove_all_stable_nodes();
+	ksm_scan.seqnr = 0;
+	return 0;
+
+error:
+	up_read(&mm->mmap_sem);
+	spin_lock(&ksm_mmlist_lock);
+	ksm_scan.mm_slot = &ksm_mm_head;
+	spin_unlock(&ksm_mmlist_lock);
+	return err;
+}
+#endif /* CONFIG_SYSFS */
+
+static u32 calc_checksum(struct page *page)
+{
+	u32 checksum;
+	void *addr = kmap_atomic(page);
+	checksum = jhash2(addr, PAGE_SIZE / 4, 17);
+	kunmap_atomic(addr);
+	return checksum;
+}
+
+static int memcmp_pages(struct page *page1, struct page *page2)
+{
+	char *addr1, *addr2;
+	int ret;
+
+	addr1 = kmap_atomic(page1);
+	addr2 = kmap_atomic(page2);
+	ret = memcmp(addr1, addr2, PAGE_SIZE);
+	kunmap_atomic(addr2);
+	kunmap_atomic(addr1);
+	return ret;
+}
+
+static inline int pages_identical(struct page *page1, struct page *page2)
+{
+	return !memcmp_pages(page1, page2);
+}
+
+static int write_protect_page(struct vm_area_struct *vma, struct page *page,
+			      pte_t *orig_pte)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long addr;
+	pte_t *ptep;
+	spinlock_t *ptl;
+	int swapped;
+	int err = -EFAULT;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+
+	addr = page_address_in_vma(page, vma);
+	if (addr == -EFAULT)
+		goto out;
+
+	BUG_ON(PageTransCompound(page));
+
+	mmun_start = addr;
+	mmun_end   = addr + PAGE_SIZE;
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+	ptep = page_check_address(page, mm, addr, &ptl, 0);
+	if (!ptep)
+		goto out_mn;
+
+	if (pte_write(*ptep) || pte_dirty(*ptep)) {
+		pte_t entry;
+
+		swapped = PageSwapCache(page);
+		flush_cache_page(vma, addr, page_to_pfn(page));
+		/*
+		 * Ok this is tricky, when get_user_pages_fast() run it doesn't
+		 * take any lock, therefore the check that we are going to make
+		 * with the pagecount against the mapcount is racey and
+		 * O_DIRECT can happen right after the check.
+		 * So we clear the pte and flush the tlb before the check
+		 * this assure us that no O_DIRECT can happen after the check
+		 * or in the middle of the check.
+		 */
+		entry = ptep_clear_flush_notify(vma, addr, ptep);
+		/*
+		 * Check that no O_DIRECT or similar I/O is in progress on the
+		 * page
+		 */
+		if (page_mapcount(page) + 1 + swapped != page_count(page)) {
+			set_pte_at(mm, addr, ptep, entry);
+			goto out_unlock;
+		}
+		if (pte_dirty(entry))
+			set_page_dirty(page);
+		entry = pte_mkclean(pte_wrprotect(entry));
+		set_pte_at_notify(mm, addr, ptep, entry);
+	}
+	*orig_pte = *ptep;
+	err = 0;
+
+out_unlock:
+	pte_unmap_unlock(ptep, ptl);
+out_mn:
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out:
+	return err;
+}
+
+/**
+ * replace_page - replace page in vma by new ksm page
+ * @vma:      vma that holds the pte pointing to page
+ * @page:     the page we are replacing by kpage
+ * @kpage:    the ksm page we replace page by
+ * @orig_pte: the original value of the pte
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+static int replace_page(struct vm_area_struct *vma, struct page *page,
+			struct page *kpage, pte_t orig_pte)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pmd_t *pmd;
+	pte_t *ptep;
+	spinlock_t *ptl;
+	unsigned long addr;
+	int err = -EFAULT;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+
+	addr = page_address_in_vma(page, vma);
+	if (addr == -EFAULT)
+		goto out;
+
+	pmd = mm_find_pmd(mm, addr);
+	if (!pmd)
+		goto out;
+
+	mmun_start = addr;
+	mmun_end   = addr + PAGE_SIZE;
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+	ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	if (!pte_same(*ptep, orig_pte)) {
+		pte_unmap_unlock(ptep, ptl);
+		goto out_mn;
+	}
+
+	get_page(kpage);
+	page_add_anon_rmap(kpage, vma, addr);
+
+	flush_cache_page(vma, addr, pte_pfn(*ptep));
+	ptep_clear_flush_notify(vma, addr, ptep);
+	set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
+
+	page_remove_rmap(page);
+	if (!page_mapped(page))
+		try_to_free_swap(page);
+	put_page(page);
+
+	pte_unmap_unlock(ptep, ptl);
+	err = 0;
+out_mn:
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out:
+	return err;
+}
+
+static int page_trans_compound_anon_split(struct page *page)
+{
+	int ret = 0;
+	struct page *transhuge_head = page_trans_compound_anon(page);
+	if (transhuge_head) {
+		/* Get the reference on the head to split it. */
+		if (get_page_unless_zero(transhuge_head)) {
+			/*
+			 * Recheck we got the reference while the head
+			 * was still anonymous.
+			 */
+			if (PageAnon(transhuge_head))
+				ret = split_huge_page(transhuge_head);
+			else
+				/*
+				 * Retry later if split_huge_page run
+				 * from under us.
+				 */
+				ret = 1;
+			put_page(transhuge_head);
+		} else
+			/* Retry later if split_huge_page run from under us. */
+			ret = 1;
+	}
+	return ret;
+}
+
+/*
+ * try_to_merge_one_page - take two pages and merge them into one
+ * @vma: the vma that holds the pte pointing to page
+ * @page: the PageAnon page that we want to replace with kpage
+ * @kpage: the PageKsm page that we want to map instead of page,
+ *         or NULL the first time when we want to use page as kpage.
+ *
+ * This function returns 0 if the pages were merged, -EFAULT otherwise.
+ */
+static int try_to_merge_one_page(struct vm_area_struct *vma,
+				 struct page *page, struct page *kpage)
+{
+	pte_t orig_pte = __pte(0);
+	int err = -EFAULT;
+
+	if (page == kpage)			/* ksm page forked */
+		return 0;
+
+	if (PageTransCompound(page) && page_trans_compound_anon_split(page))
+		goto out;
+	BUG_ON(PageTransCompound(page));
+	if (!PageAnon(page))
+		goto out;
+
+	/*
+	 * We need the page lock to read a stable PageSwapCache in
+	 * write_protect_page().  We use trylock_page() instead of
+	 * lock_page() because we don't want to wait here - we
+	 * prefer to continue scanning and merging different pages,
+	 * then come back to this page when it is unlocked.
+	 */
+	if (!trylock_page(page))
+		goto out;
+	/*
+	 * If this anonymous page is mapped only here, its pte may need
+	 * to be write-protected.  If it's mapped elsewhere, all of its
+	 * ptes are necessarily already write-protected.  But in either
+	 * case, we need to lock and check page_count is not raised.
+	 */
+	if (write_protect_page(vma, page, &orig_pte) == 0) {
+		if (!kpage) {
+			/*
+			 * While we hold page lock, upgrade page from
+			 * PageAnon+anon_vma to PageKsm+NULL stable_node:
+			 * stable_tree_insert() will update stable_node.
+			 */
+			set_page_stable_node(page, NULL);
+			mark_page_accessed(page);
+			err = 0;
+		} else if (pages_identical(page, kpage))
+			err = replace_page(vma, page, kpage, orig_pte);
+	}
+
+	if ((vma->vm_flags & VM_LOCKED) && kpage && !err) {
+		munlock_vma_page(page);
+		if (!PageMlocked(kpage)) {
+			unlock_page(page);
+			lock_page(kpage);
+			mlock_vma_page(kpage);
+			page = kpage;		/* for final unlock */
+		}
+	}
+
+	unlock_page(page);
+out:
+	return err;
+}
+
+/*
+ * try_to_merge_with_ksm_page - like try_to_merge_two_pages,
+ * but no new kernel page is allocated: kpage must already be a ksm page.
+ *
+ * This function returns 0 if the pages were merged, -EFAULT otherwise.
+ */
+static int try_to_merge_with_ksm_page(struct rmap_item *rmap_item,
+				      struct page *page, struct page *kpage)
+{
+	struct mm_struct *mm = rmap_item->mm;
+	struct vm_area_struct *vma;
+	int err = -EFAULT;
+
+	down_read(&mm->mmap_sem);
+	vma = find_mergeable_vma(mm, rmap_item->address);
+	if (!vma)
+		goto out;
+
+	err = try_to_merge_one_page(vma, page, kpage);
+	if (err)
+		goto out;
+
+	/* Unstable nid is in union with stable anon_vma: remove first */
+	remove_rmap_item_from_tree(rmap_item);
+
+	/* Must get reference to anon_vma while still holding mmap_sem */
+	rmap_item->anon_vma = vma->anon_vma;
+	get_anon_vma(vma->anon_vma);
+out:
+	up_read(&mm->mmap_sem);
+	return err;
+}
+
+/*
+ * try_to_merge_two_pages - take two identical pages and prepare them
+ * to be merged into one page.
+ *
+ * This function returns the kpage if we successfully merged two identical
+ * pages into one ksm page, NULL otherwise.
+ *
+ * Note that this function upgrades page to ksm page: if one of the pages
+ * is already a ksm page, try_to_merge_with_ksm_page should be used.
+ */
+static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item,
+					   struct page *page,
+					   struct rmap_item *tree_rmap_item,
+					   struct page *tree_page)
+{
+	int err;
+
+	err = try_to_merge_with_ksm_page(rmap_item, page, NULL);
+	if (!err) {
+		err = try_to_merge_with_ksm_page(tree_rmap_item,
+							tree_page, page);
+		/*
+		 * If that fails, we have a ksm page with only one pte
+		 * pointing to it: so break it.
+		 */
+		if (err)
+			break_cow(rmap_item);
+	}
+	return err ? NULL : page;
+}
+
+/*
+ * stable_tree_search - search for page inside the stable tree
+ *
+ * This function checks if there is a page inside the stable tree
+ * with identical content to the page that we are scanning right now.
+ *
+ * This function returns the stable tree node of identical content if found,
+ * NULL otherwise.
+ */
+static struct page *stable_tree_search(struct page *page)
+{
+	int nid;
+	struct rb_root *root;
+	struct rb_node **new;
+	struct rb_node *parent;
+	struct stable_node *stable_node;
+	struct stable_node *page_node;
+
+	page_node = page_stable_node(page);
+	if (page_node && page_node->head != &migrate_nodes) {
+		/* ksm page forked */
+		get_page(page);
+		return page;
+	}
+
+	nid = get_kpfn_nid(page_to_pfn(page));
+	root = root_stable_tree + nid;
+again:
+	new = &root->rb_node;
+	parent = NULL;
+
+	while (*new) {
+		struct page *tree_page;
+		int ret;
+
+		cond_resched();
+		stable_node = rb_entry(*new, struct stable_node, node);
+		tree_page = get_ksm_page(stable_node, false);
+		if (!tree_page) {
+			/*
+			 * If we walked over a stale stable_node,
+			 * get_ksm_page() will call rb_erase() and it
+			 * may rebalance the tree from under us. So
+			 * restart the search from scratch. Returning
+			 * NULL would be safe too, but we'd generate
+			 * false negative insertions just because some
+			 * stable_node was stale.
+			 */
+			goto again;
+		}
+
+		ret = memcmp_pages(page, tree_page);
+		put_page(tree_page);
+
+		parent = *new;
+		if (ret < 0)
+			new = &parent->rb_left;
+		else if (ret > 0)
+			new = &parent->rb_right;
+		else {
+			/*
+			 * Lock and unlock the stable_node's page (which
+			 * might already have been migrated) so that page
+			 * migration is sure to notice its raised count.
+			 * It would be more elegant to return stable_node
+			 * than kpage, but that involves more changes.
+			 */
+			tree_page = get_ksm_page(stable_node, true);
+			if (tree_page) {
+				unlock_page(tree_page);
+				if (get_kpfn_nid(stable_node->kpfn) !=
+						NUMA(stable_node->nid)) {
+					put_page(tree_page);
+					goto replace;
+				}
+				return tree_page;
+			}
+			/*
+			 * There is now a place for page_node, but the tree may
+			 * have been rebalanced, so re-evaluate parent and new.
+			 */
+			if (page_node)
+				goto again;
+			return NULL;
+		}
+	}
+
+	if (!page_node)
+		return NULL;
+
+	list_del(&page_node->list);
+	DO_NUMA(page_node->nid = nid);
+	rb_link_node(&page_node->node, parent, new);
+	rb_insert_color(&page_node->node, root);
+	get_page(page);
+	return page;
+
+replace:
+	if (page_node) {
+		list_del(&page_node->list);
+		DO_NUMA(page_node->nid = nid);
+		rb_replace_node(&stable_node->node, &page_node->node, root);
+		get_page(page);
+	} else {
+		rb_erase(&stable_node->node, root);
+		page = NULL;
+	}
+	stable_node->head = &migrate_nodes;
+	list_add(&stable_node->list, stable_node->head);
+	return page;
+}
+
+/*
+ * stable_tree_insert - insert stable tree node pointing to new ksm page
+ * into the stable tree.
+ *
+ * This function returns the stable tree node just allocated on success,
+ * NULL otherwise.
+ */
+static struct stable_node *stable_tree_insert(struct page *kpage)
+{
+	int nid;
+	unsigned long kpfn;
+	struct rb_root *root;
+	struct rb_node **new;
+	struct rb_node *parent;
+	struct stable_node *stable_node;
+
+	kpfn = page_to_pfn(kpage);
+	nid = get_kpfn_nid(kpfn);
+	root = root_stable_tree + nid;
+again:
+	parent = NULL;
+	new = &root->rb_node;
+
+	while (*new) {
+		struct page *tree_page;
+		int ret;
+
+		cond_resched();
+		stable_node = rb_entry(*new, struct stable_node, node);
+		tree_page = get_ksm_page(stable_node, false);
+		if (!tree_page) {
+			/*
+			 * If we walked over a stale stable_node,
+			 * get_ksm_page() will call rb_erase() and it
+			 * may rebalance the tree from under us. So
+			 * restart the search from scratch. Returning
+			 * NULL would be safe too, but we'd generate
+			 * false negative insertions just because some
+			 * stable_node was stale.
+			 */
+			goto again;
+		}
+
+		ret = memcmp_pages(kpage, tree_page);
+		put_page(tree_page);
+
+		parent = *new;
+		if (ret < 0)
+			new = &parent->rb_left;
+		else if (ret > 0)
+			new = &parent->rb_right;
+		else {
+			/*
+			 * It is not a bug that stable_tree_search() didn't
+			 * find this node: because at that time our page was
+			 * not yet write-protected, so may have changed since.
+			 */
+			return NULL;
+		}
+	}
+
+	stable_node = alloc_stable_node();
+	if (!stable_node)
+		return NULL;
+
+	INIT_HLIST_HEAD(&stable_node->hlist);
+	stable_node->kpfn = kpfn;
+	set_page_stable_node(kpage, stable_node);
+	DO_NUMA(stable_node->nid = nid);
+	rb_link_node(&stable_node->node, parent, new);
+	rb_insert_color(&stable_node->node, root);
+
+	return stable_node;
+}
+
+/*
+ * unstable_tree_search_insert - search for identical page,
+ * else insert rmap_item into the unstable tree.
+ *
+ * This function searches for a page in the unstable tree identical to the
+ * page currently being scanned; and if no identical page is found in the
+ * tree, we insert rmap_item as a new object into the unstable tree.
+ *
+ * This function returns pointer to rmap_item found to be identical
+ * to the currently scanned page, NULL otherwise.
+ *
+ * This function does both searching and inserting, because they share
+ * the same walking algorithm in an rbtree.
+ */
+static
+struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item,
+					      struct page *page,
+					      struct page **tree_pagep)
+{
+	struct rb_node **new;
+	struct rb_root *root;
+	struct rb_node *parent = NULL;
+	int nid;
+
+	nid = get_kpfn_nid(page_to_pfn(page));
+	root = root_unstable_tree + nid;
+	new = &root->rb_node;
+
+	while (*new) {
+		struct rmap_item *tree_rmap_item;
+		struct page *tree_page;
+		int ret;
+
+		cond_resched();
+		tree_rmap_item = rb_entry(*new, struct rmap_item, node);
+		tree_page = get_mergeable_page(tree_rmap_item);
+		if (!tree_page)
+			return NULL;
+
+		/*
+		 * Don't substitute a ksm page for a forked page.
+		 */
+		if (page == tree_page) {
+			put_page(tree_page);
+			return NULL;
+		}
+
+		ret = memcmp_pages(page, tree_page);
+
+		parent = *new;
+		if (ret < 0) {
+			put_page(tree_page);
+			new = &parent->rb_left;
+		} else if (ret > 0) {
+			put_page(tree_page);
+			new = &parent->rb_right;
+		} else if (!ksm_merge_across_nodes &&
+			   page_to_nid(tree_page) != nid) {
+			/*
+			 * If tree_page has been migrated to another NUMA node,
+			 * it will be flushed out and put in the right unstable
+			 * tree next time: only merge with it when across_nodes.
+			 */
+			put_page(tree_page);
+			return NULL;
+		} else {
+			*tree_pagep = tree_page;
+			return tree_rmap_item;
+		}
+	}
+
+	rmap_item->address |= UNSTABLE_FLAG;
+	rmap_item->address |= (ksm_scan.seqnr & SEQNR_MASK);
+	DO_NUMA(rmap_item->nid = nid);
+	rb_link_node(&rmap_item->node, parent, new);
+	rb_insert_color(&rmap_item->node, root);
+
+	ksm_pages_unshared++;
+	return NULL;
+}
+
+/*
+ * stable_tree_append - add another rmap_item to the linked list of
+ * rmap_items hanging off a given node of the stable tree, all sharing
+ * the same ksm page.
+ */
+static void stable_tree_append(struct rmap_item *rmap_item,
+			       struct stable_node *stable_node)
+{
+	rmap_item->head = stable_node;
+	rmap_item->address |= STABLE_FLAG;
+	hlist_add_head(&rmap_item->hlist, &stable_node->hlist);
+
+	if (rmap_item->hlist.next)
+		ksm_pages_sharing++;
+	else
+		ksm_pages_shared++;
+}
+
+/*
+ * cmp_and_merge_page - first see if page can be merged into the stable tree;
+ * if not, compare checksum to previous and if it's the same, see if page can
+ * be inserted into the unstable tree, or merged with a page already there and
+ * both transferred to the stable tree.
+ *
+ * @page: the page that we are searching identical page to.
+ * @rmap_item: the reverse mapping into the virtual address of this page
+ */
+static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
+{
+	struct rmap_item *tree_rmap_item;
+	struct page *tree_page = NULL;
+	struct stable_node *stable_node;
+	struct page *kpage;
+	unsigned int checksum;
+	int err;
+
+	stable_node = page_stable_node(page);
+	if (stable_node) {
+		if (stable_node->head != &migrate_nodes &&
+		    get_kpfn_nid(stable_node->kpfn) != NUMA(stable_node->nid)) {
+			rb_erase(&stable_node->node,
+				 root_stable_tree + NUMA(stable_node->nid));
+			stable_node->head = &migrate_nodes;
+			list_add(&stable_node->list, stable_node->head);
+		}
+		if (stable_node->head != &migrate_nodes &&
+		    rmap_item->head == stable_node)
+			return;
+	}
+
+	/* We first start with searching the page inside the stable tree */
+	kpage = stable_tree_search(page);
+	if (kpage == page && rmap_item->head == stable_node) {
+		put_page(kpage);
+		return;
+	}
+
+	remove_rmap_item_from_tree(rmap_item);
+
+	if (kpage) {
+		err = try_to_merge_with_ksm_page(rmap_item, page, kpage);
+		if (!err) {
+			/*
+			 * The page was successfully merged:
+			 * add its rmap_item to the stable tree.
+			 */
+			lock_page(kpage);
+			stable_tree_append(rmap_item, page_stable_node(kpage));
+			unlock_page(kpage);
+		}
+		put_page(kpage);
+		return;
+	}
+
+	/*
+	 * If the hash value of the page has changed from the last time
+	 * we calculated it, this page is changing frequently: therefore we
+	 * don't want to insert it in the unstable tree, and we don't want
+	 * to waste our time searching for something identical to it there.
+	 */
+	checksum = calc_checksum(page);
+	if (rmap_item->oldchecksum != checksum) {
+		rmap_item->oldchecksum = checksum;
+		return;
+	}
+
+	tree_rmap_item =
+		unstable_tree_search_insert(rmap_item, page, &tree_page);
+	if (tree_rmap_item) {
+		kpage = try_to_merge_two_pages(rmap_item, page,
+						tree_rmap_item, tree_page);
+		put_page(tree_page);
+		if (kpage) {
+			/*
+			 * The pages were successfully merged: insert new
+			 * node in the stable tree and add both rmap_items.
+			 */
+			lock_page(kpage);
+			stable_node = stable_tree_insert(kpage);
+			if (stable_node) {
+				stable_tree_append(tree_rmap_item, stable_node);
+				stable_tree_append(rmap_item, stable_node);
+			}
+			unlock_page(kpage);
+
+			/*
+			 * If we fail to insert the page into the stable tree,
+			 * we will have 2 virtual addresses that are pointing
+			 * to a ksm page left outside the stable tree,
+			 * in which case we need to break_cow on both.
+			 */
+			if (!stable_node) {
+				break_cow(tree_rmap_item);
+				break_cow(rmap_item);
+			}
+		}
+	}
+}
+
+static struct rmap_item *get_next_rmap_item(struct mm_slot *mm_slot,
+					    struct rmap_item **rmap_list,
+					    unsigned long addr)
+{
+	struct rmap_item *rmap_item;
+
+	while (*rmap_list) {
+		rmap_item = *rmap_list;
+		if ((rmap_item->address & PAGE_MASK) == addr)
+			return rmap_item;
+		if (rmap_item->address > addr)
+			break;
+		*rmap_list = rmap_item->rmap_list;
+		remove_rmap_item_from_tree(rmap_item);
+		free_rmap_item(rmap_item);
+	}
+
+	rmap_item = alloc_rmap_item();
+	if (rmap_item) {
+		/* It has already been zeroed */
+		rmap_item->mm = mm_slot->mm;
+		rmap_item->address = addr;
+		rmap_item->rmap_list = *rmap_list;
+		*rmap_list = rmap_item;
+	}
+	return rmap_item;
+}
+
+static struct rmap_item *scan_get_next_rmap_item(struct page **page)
+{
+	struct mm_struct *mm;
+	struct mm_slot *slot;
+	struct vm_area_struct *vma;
+	struct rmap_item *rmap_item;
+	int nid;
+
+	if (list_empty(&ksm_mm_head.mm_list))
+		return NULL;
+
+	slot = ksm_scan.mm_slot;
+	if (slot == &ksm_mm_head) {
+		/*
+		 * A number of pages can hang around indefinitely on per-cpu
+		 * pagevecs, raised page count preventing write_protect_page
+		 * from merging them.  Though it doesn't really matter much,
+		 * it is puzzling to see some stuck in pages_volatile until
+		 * other activity jostles them out, and they also prevented
+		 * LTP's KSM test from succeeding deterministically; so drain
+		 * them here (here rather than on entry to ksm_do_scan(),
+		 * so we don't IPI too often when pages_to_scan is set low).
+		 */
+		lru_add_drain_all();
+
+		/*
+		 * Whereas stale stable_nodes on the stable_tree itself
+		 * get pruned in the regular course of stable_tree_search(),
+		 * those moved out to the migrate_nodes list can accumulate:
+		 * so prune them once before each full scan.
+		 */
+		if (!ksm_merge_across_nodes) {
+			struct stable_node *stable_node;
+			struct list_head *this, *next;
+			struct page *page;
+
+			list_for_each_safe(this, next, &migrate_nodes) {
+				stable_node = list_entry(this,
+						struct stable_node, list);
+				page = get_ksm_page(stable_node, false);
+				if (page)
+					put_page(page);
+				cond_resched();
+			}
+		}
+
+		for (nid = 0; nid < ksm_nr_node_ids; nid++)
+			root_unstable_tree[nid] = RB_ROOT;
+
+		spin_lock(&ksm_mmlist_lock);
+		slot = list_entry(slot->mm_list.next, struct mm_slot, mm_list);
+		ksm_scan.mm_slot = slot;
+		spin_unlock(&ksm_mmlist_lock);
+		/*
+		 * Although we tested list_empty() above, a racing __ksm_exit
+		 * of the last mm on the list may have removed it since then.
+		 */
+		if (slot == &ksm_mm_head)
+			return NULL;
+next_mm:
+		ksm_scan.address = 0;
+		ksm_scan.rmap_list = &slot->rmap_list;
+	}
+
+	mm = slot->mm;
+	down_read(&mm->mmap_sem);
+	if (ksm_test_exit(mm))
+		vma = NULL;
+	else
+		vma = find_vma(mm, ksm_scan.address);
+
+	for (; vma; vma = vma->vm_next) {
+		if (!(vma->vm_flags & VM_MERGEABLE))
+			continue;
+		if (ksm_scan.address < vma->vm_start)
+			ksm_scan.address = vma->vm_start;
+		if (!vma->anon_vma)
+			ksm_scan.address = vma->vm_end;
+
+		while (ksm_scan.address < vma->vm_end) {
+			if (ksm_test_exit(mm))
+				break;
+			*page = follow_page(vma, ksm_scan.address, FOLL_GET);
+			if (IS_ERR_OR_NULL(*page)) {
+				ksm_scan.address += PAGE_SIZE;
+				cond_resched();
+				continue;
+			}
+			if (PageAnon(*page) ||
+			    page_trans_compound_anon(*page)) {
+				flush_anon_page(vma, *page, ksm_scan.address);
+				flush_dcache_page(*page);
+				rmap_item = get_next_rmap_item(slot,
+					ksm_scan.rmap_list, ksm_scan.address);
+				if (rmap_item) {
+					ksm_scan.rmap_list =
+							&rmap_item->rmap_list;
+					ksm_scan.address += PAGE_SIZE;
+				} else
+					put_page(*page);
+				up_read(&mm->mmap_sem);
+				return rmap_item;
+			}
+			put_page(*page);
+			ksm_scan.address += PAGE_SIZE;
+			cond_resched();
+		}
+	}
+
+	if (ksm_test_exit(mm)) {
+		ksm_scan.address = 0;
+		ksm_scan.rmap_list = &slot->rmap_list;
+	}
+	/*
+	 * Nuke all the rmap_items that are above this current rmap:
+	 * because there were no VM_MERGEABLE vmas with such addresses.
+	 */
+	remove_trailing_rmap_items(slot, ksm_scan.rmap_list);
+
+	spin_lock(&ksm_mmlist_lock);
+	ksm_scan.mm_slot = list_entry(slot->mm_list.next,
+						struct mm_slot, mm_list);
+	if (ksm_scan.address == 0) {
+		/*
+		 * We've completed a full scan of all vmas, holding mmap_sem
+		 * throughout, and found no VM_MERGEABLE: so do the same as
+		 * __ksm_exit does to remove this mm from all our lists now.
+		 * This applies either when cleaning up after __ksm_exit
+		 * (but beware: we can reach here even before __ksm_exit),
+		 * or when all VM_MERGEABLE areas have been unmapped (and
+		 * mmap_sem then protects against race with MADV_MERGEABLE).
+		 */
+		hash_del(&slot->link);
+		list_del(&slot->mm_list);
+		spin_unlock(&ksm_mmlist_lock);
+
+		free_mm_slot(slot);
+		clear_bit(MMF_VM_MERGEABLE, &mm->flags);
+		up_read(&mm->mmap_sem);
+		mmdrop(mm);
+	} else {
+		spin_unlock(&ksm_mmlist_lock);
+		up_read(&mm->mmap_sem);
+	}
+
+	/* Repeat until we've completed scanning the whole list */
+	slot = ksm_scan.mm_slot;
+	if (slot != &ksm_mm_head)
+		goto next_mm;
+
+	ksm_scan.seqnr++;
+	return NULL;
+}
+
+/**
+ * ksm_do_scan  - the ksm scanner main worker function.
+ * @scan_npages - number of pages we want to scan before we return.
+ */
+static void ksm_do_scan(unsigned int scan_npages)
+{
+	struct rmap_item *rmap_item;
+	struct page *uninitialized_var(page);
+
+	while (scan_npages-- && likely(!freezing(current))) {
+		cond_resched();
+		rmap_item = scan_get_next_rmap_item(&page);
+		if (!rmap_item)
+			return;
+		cmp_and_merge_page(page, rmap_item);
+		put_page(page);
+	}
+}
+
+static int ksmd_should_run(void)
+{
+	return (ksm_run & KSM_RUN_MERGE) && !list_empty(&ksm_mm_head.mm_list);
+}
+
+static int ksm_scan_thread(void *nothing)
+{
+	set_freezable();
+	set_user_nice(current, 5);
+
+	while (!kthread_should_stop()) {
+		mutex_lock(&ksm_thread_mutex);
+		wait_while_offlining();
+		if (ksmd_should_run())
+			ksm_do_scan(ksm_thread_pages_to_scan);
+		mutex_unlock(&ksm_thread_mutex);
+
+		try_to_freeze();
+
+		if (ksmd_should_run()) {
+			schedule_timeout_interruptible(
+				msecs_to_jiffies(ksm_thread_sleep_millisecs));
+		} else {
+			wait_event_freezable(ksm_thread_wait,
+				ksmd_should_run() || kthread_should_stop());
+		}
+	}
+	return 0;
+}
+
+int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
+		unsigned long end, int advice, unsigned long *vm_flags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int err;
+
+	switch (advice) {
+	case MADV_MERGEABLE:
+		/*
+		 * Be somewhat over-protective for now!
+		 */
+		if (*vm_flags & (VM_MERGEABLE | VM_SHARED  | VM_MAYSHARE   |
+				 VM_PFNMAP    | VM_IO      | VM_DONTEXPAND |
+				 VM_HUGETLB | VM_MIXEDMAP))
+			return 0;		/* just ignore the advice */
+
+#ifdef VM_SAO
+		if (*vm_flags & VM_SAO)
+			return 0;
+#endif
+
+		if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
+			err = __ksm_enter(mm);
+			if (err)
+				return err;
+		}
+
+		*vm_flags |= VM_MERGEABLE;
+		break;
+
+	case MADV_UNMERGEABLE:
+		if (!(*vm_flags & VM_MERGEABLE))
+			return 0;		/* just ignore the advice */
+
+		if (vma->anon_vma) {
+			err = unmerge_ksm_pages(vma, start, end);
+			if (err)
+				return err;
+		}
+
+		*vm_flags &= ~VM_MERGEABLE;
+		break;
+	}
+
+	return 0;
+}
+
+int __ksm_enter(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	int needs_wakeup;
+
+	mm_slot = alloc_mm_slot();
+	if (!mm_slot)
+		return -ENOMEM;
+
+	/* Check ksm_run too?  Would need tighter locking */
+	needs_wakeup = list_empty(&ksm_mm_head.mm_list);
+
+	spin_lock(&ksm_mmlist_lock);
+	insert_to_mm_slots_hash(mm, mm_slot);
+	/*
+	 * When KSM_RUN_MERGE (or KSM_RUN_STOP),
+	 * insert just behind the scanning cursor, to let the area settle
+	 * down a little; when fork is followed by immediate exec, we don't
+	 * want ksmd to waste time setting up and tearing down an rmap_list.
+	 *
+	 * But when KSM_RUN_UNMERGE, it's important to insert ahead of its
+	 * scanning cursor, otherwise KSM pages in newly forked mms will be
+	 * missed: then we might as well insert at the end of the list.
+	 */
+	if (ksm_run & KSM_RUN_UNMERGE)
+		list_add_tail(&mm_slot->mm_list, &ksm_mm_head.mm_list);
+	else
+		list_add_tail(&mm_slot->mm_list, &ksm_scan.mm_slot->mm_list);
+	spin_unlock(&ksm_mmlist_lock);
+
+	set_bit(MMF_VM_MERGEABLE, &mm->flags);
+	atomic_inc(&mm->mm_count);
+
+	if (needs_wakeup)
+		wake_up_interruptible(&ksm_thread_wait);
+
+	return 0;
+}
+
+void __ksm_exit(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	int easy_to_free = 0;
+
+	/*
+	 * This process is exiting: if it's straightforward (as is the
+	 * case when ksmd was never running), free mm_slot immediately.
+	 * But if it's at the cursor or has rmap_items linked to it, use
+	 * mmap_sem to synchronize with any break_cows before pagetables
+	 * are freed, and leave the mm_slot on the list for ksmd to free.
+	 * Beware: ksm may already have noticed it exiting and freed the slot.
+	 */
+
+	spin_lock(&ksm_mmlist_lock);
+	mm_slot = get_mm_slot(mm);
+	if (mm_slot && ksm_scan.mm_slot != mm_slot) {
+		if (!mm_slot->rmap_list) {
+			hash_del(&mm_slot->link);
+			list_del(&mm_slot->mm_list);
+			easy_to_free = 1;
+		} else {
+			list_move(&mm_slot->mm_list,
+				  &ksm_scan.mm_slot->mm_list);
+		}
+	}
+	spin_unlock(&ksm_mmlist_lock);
+
+	if (easy_to_free) {
+		free_mm_slot(mm_slot);
+		clear_bit(MMF_VM_MERGEABLE, &mm->flags);
+		mmdrop(mm);
+	} else if (mm_slot) {
+		down_write(&mm->mmap_sem);
+		up_write(&mm->mmap_sem);
+	}
+}
+
+struct page *ksm_might_need_to_copy(struct page *page,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	struct anon_vma *anon_vma = page_anon_vma(page);
+	struct page *new_page;
+
+	if (PageKsm(page)) {
+		if (page_stable_node(page) &&
+		    !(ksm_run & KSM_RUN_UNMERGE))
+			return page;	/* no need to copy it */
+	} else if (!anon_vma) {
+		return page;		/* no need to copy it */
+	} else if (anon_vma->root == vma->anon_vma->root &&
+		 page->index == linear_page_index(vma, address)) {
+		return page;		/* still no need to copy it */
+	}
+	if (!PageUptodate(page))
+		return page;		/* let do_swap_page report the error */
+
+	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+	if (new_page) {
+		copy_user_highpage(new_page, page, address, vma);
+
+		SetPageDirty(new_page);
+		__SetPageUptodate(new_page);
+		__set_page_locked(new_page);
+	}
+
+	return new_page;
+}
+
+int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
+{
+	struct stable_node *stable_node;
+	struct rmap_item *rmap_item;
+	int ret = SWAP_AGAIN;
+	int search_new_forks = 0;
+
+	VM_BUG_ON_PAGE(!PageKsm(page), page);
+
+	/*
+	 * Rely on the page lock to protect against concurrent modifications
+	 * to that page's node of the stable tree.
+	 */
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+	stable_node = page_stable_node(page);
+	if (!stable_node)
+		return ret;
+again:
+	hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
+		struct anon_vma *anon_vma = rmap_item->anon_vma;
+		struct anon_vma_chain *vmac;
+		struct vm_area_struct *vma;
+
+		cond_resched();
+		anon_vma_lock_read(anon_vma);
+		anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
+					       0, ULONG_MAX) {
+			cond_resched();
+			vma = vmac->vma;
+			if (rmap_item->address < vma->vm_start ||
+			    rmap_item->address >= vma->vm_end)
+				continue;
+			/*
+			 * Initially we examine only the vma which covers this
+			 * rmap_item; but later, if there is still work to do,
+			 * we examine covering vmas in other mms: in case they
+			 * were forked from the original since ksmd passed.
+			 */
+			if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
+				continue;
+
+			if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+				continue;
+
+			ret = rwc->rmap_one(page, vma,
+					rmap_item->address, rwc->arg);
+			if (ret != SWAP_AGAIN) {
+				anon_vma_unlock_read(anon_vma);
+				goto out;
+			}
+			if (rwc->done && rwc->done(page)) {
+				anon_vma_unlock_read(anon_vma);
+				goto out;
+			}
+		}
+		anon_vma_unlock_read(anon_vma);
+	}
+	if (!search_new_forks++)
+		goto again;
+out:
+	return ret;
+}
+
+#ifdef CONFIG_MIGRATION
+void ksm_migrate_page(struct page *newpage, struct page *oldpage)
+{
+	struct stable_node *stable_node;
+
+	VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+	VM_BUG_ON_PAGE(newpage->mapping != oldpage->mapping, newpage);
+
+	stable_node = page_stable_node(newpage);
+	if (stable_node) {
+		VM_BUG_ON_PAGE(stable_node->kpfn != page_to_pfn(oldpage), oldpage);
+		stable_node->kpfn = page_to_pfn(newpage);
+		/*
+		 * newpage->mapping was set in advance; now we need smp_wmb()
+		 * to make sure that the new stable_node->kpfn is visible
+		 * to get_ksm_page() before it can see that oldpage->mapping
+		 * has gone stale (or that PageSwapCache has been cleared).
+		 */
+		smp_wmb();
+		set_page_stable_node(oldpage, NULL);
+	}
+}
+#endif /* CONFIG_MIGRATION */
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static void wait_while_offlining(void)
+{
+	while (ksm_run & KSM_RUN_OFFLINE) {
+		mutex_unlock(&ksm_thread_mutex);
+		wait_on_bit(&ksm_run, ilog2(KSM_RUN_OFFLINE),
+			    TASK_UNINTERRUPTIBLE);
+		mutex_lock(&ksm_thread_mutex);
+	}
+}
+
+static void ksm_check_stable_tree(unsigned long start_pfn,
+				  unsigned long end_pfn)
+{
+	struct stable_node *stable_node;
+	struct list_head *this, *next;
+	struct rb_node *node;
+	int nid;
+
+	for (nid = 0; nid < ksm_nr_node_ids; nid++) {
+		node = rb_first(root_stable_tree + nid);
+		while (node) {
+			stable_node = rb_entry(node, struct stable_node, node);
+			if (stable_node->kpfn >= start_pfn &&
+			    stable_node->kpfn < end_pfn) {
+				/*
+				 * Don't get_ksm_page, page has already gone:
+				 * which is why we keep kpfn instead of page*
+				 */
+				remove_node_from_stable_tree(stable_node);
+				node = rb_first(root_stable_tree + nid);
+			} else
+				node = rb_next(node);
+			cond_resched();
+		}
+	}
+	list_for_each_safe(this, next, &migrate_nodes) {
+		stable_node = list_entry(this, struct stable_node, list);
+		if (stable_node->kpfn >= start_pfn &&
+		    stable_node->kpfn < end_pfn)
+			remove_node_from_stable_tree(stable_node);
+		cond_resched();
+	}
+}
+
+static int ksm_memory_callback(struct notifier_block *self,
+			       unsigned long action, void *arg)
+{
+	struct memory_notify *mn = arg;
+
+	switch (action) {
+	case MEM_GOING_OFFLINE:
+		/*
+		 * Prevent ksm_do_scan(), unmerge_and_remove_all_rmap_items()
+		 * and remove_all_stable_nodes() while memory is going offline:
+		 * it is unsafe for them to touch the stable tree at this time.
+		 * But unmerge_ksm_pages(), rmap lookups and other entry points
+		 * which do not need the ksm_thread_mutex are all safe.
+		 */
+		mutex_lock(&ksm_thread_mutex);
+		ksm_run |= KSM_RUN_OFFLINE;
+		mutex_unlock(&ksm_thread_mutex);
+		break;
+
+	case MEM_OFFLINE:
+		/*
+		 * Most of the work is done by page migration; but there might
+		 * be a few stable_nodes left over, still pointing to struct
+		 * pages which have been offlined: prune those from the tree,
+		 * otherwise get_ksm_page() might later try to access a
+		 * non-existent struct page.
+		 */
+		ksm_check_stable_tree(mn->start_pfn,
+				      mn->start_pfn + mn->nr_pages);
+		/* fallthrough */
+
+	case MEM_CANCEL_OFFLINE:
+		mutex_lock(&ksm_thread_mutex);
+		ksm_run &= ~KSM_RUN_OFFLINE;
+		mutex_unlock(&ksm_thread_mutex);
+
+		smp_mb();	/* wake_up_bit advises this */
+		wake_up_bit(&ksm_run, ilog2(KSM_RUN_OFFLINE));
+		break;
+	}
+	return NOTIFY_OK;
+}
+#else
+static void wait_while_offlining(void)
+{
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+#ifdef CONFIG_SYSFS
+/*
+ * This all compiles without CONFIG_SYSFS, but is a waste of space.
+ */
+
+#define KSM_ATTR_RO(_name) \
+	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+#define KSM_ATTR(_name) \
+	static struct kobj_attribute _name##_attr = \
+		__ATTR(_name, 0644, _name##_show, _name##_store)
+
+static ssize_t sleep_millisecs_show(struct kobject *kobj,
+				    struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", ksm_thread_sleep_millisecs);
+}
+
+static ssize_t sleep_millisecs_store(struct kobject *kobj,
+				     struct kobj_attribute *attr,
+				     const char *buf, size_t count)
+{
+	unsigned long msecs;
+	int err;
+
+	err = kstrtoul(buf, 10, &msecs);
+	if (err || msecs > UINT_MAX)
+		return -EINVAL;
+
+	ksm_thread_sleep_millisecs = msecs;
+
+	return count;
+}
+KSM_ATTR(sleep_millisecs);
+
+static ssize_t pages_to_scan_show(struct kobject *kobj,
+				  struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", ksm_thread_pages_to_scan);
+}
+
+static ssize_t pages_to_scan_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int err;
+	unsigned long nr_pages;
+
+	err = kstrtoul(buf, 10, &nr_pages);
+	if (err || nr_pages > UINT_MAX)
+		return -EINVAL;
+
+	ksm_thread_pages_to_scan = nr_pages;
+
+	return count;
+}
+KSM_ATTR(pages_to_scan);
+
+static ssize_t run_show(struct kobject *kobj, struct kobj_attribute *attr,
+			char *buf)
+{
+	return sprintf(buf, "%lu\n", ksm_run);
+}
+
+static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
+			 const char *buf, size_t count)
+{
+	int err;
+	unsigned long flags;
+
+	err = kstrtoul(buf, 10, &flags);
+	if (err || flags > UINT_MAX)
+		return -EINVAL;
+	if (flags > KSM_RUN_UNMERGE)
+		return -EINVAL;
+
+	/*
+	 * KSM_RUN_MERGE sets ksmd running, and 0 stops it running.
+	 * KSM_RUN_UNMERGE stops it running and unmerges all rmap_items,
+	 * breaking COW to free the pages_shared (but leaves mm_slots
+	 * on the list for when ksmd may be set running again).
+	 */
+
+	mutex_lock(&ksm_thread_mutex);
+	wait_while_offlining();
+	if (ksm_run != flags) {
+		ksm_run = flags;
+		if (flags & KSM_RUN_UNMERGE) {
+			set_current_oom_origin();
+			err = unmerge_and_remove_all_rmap_items();
+			clear_current_oom_origin();
+			if (err) {
+				ksm_run = KSM_RUN_STOP;
+				count = err;
+			}
+		}
+	}
+	mutex_unlock(&ksm_thread_mutex);
+
+	if (flags & KSM_RUN_MERGE)
+		wake_up_interruptible(&ksm_thread_wait);
+
+	return count;
+}
+KSM_ATTR(run);
+
+#ifdef CONFIG_NUMA
+static ssize_t merge_across_nodes_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", ksm_merge_across_nodes);
+}
+
+static ssize_t merge_across_nodes_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int err;
+	unsigned long knob;
+
+	err = kstrtoul(buf, 10, &knob);
+	if (err)
+		return err;
+	if (knob > 1)
+		return -EINVAL;
+
+	mutex_lock(&ksm_thread_mutex);
+	wait_while_offlining();
+	if (ksm_merge_across_nodes != knob) {
+		if (ksm_pages_shared || remove_all_stable_nodes())
+			err = -EBUSY;
+		else if (root_stable_tree == one_stable_tree) {
+			struct rb_root *buf;
+			/*
+			 * This is the first time that we switch away from the
+			 * default of merging across nodes: must now allocate
+			 * a buffer to hold as many roots as may be needed.
+			 * Allocate stable and unstable together:
+			 * MAXSMP NODES_SHIFT 10 will use 16kB.
+			 */
+			buf = kcalloc(nr_node_ids + nr_node_ids, sizeof(*buf),
+				      GFP_KERNEL);
+			/* Let us assume that RB_ROOT is NULL is zero */
+			if (!buf)
+				err = -ENOMEM;
+			else {
+				root_stable_tree = buf;
+				root_unstable_tree = buf + nr_node_ids;
+				/* Stable tree is empty but not the unstable */
+				root_unstable_tree[0] = one_unstable_tree[0];
+			}
+		}
+		if (!err) {
+			ksm_merge_across_nodes = knob;
+			ksm_nr_node_ids = knob ? 1 : nr_node_ids;
+		}
+	}
+	mutex_unlock(&ksm_thread_mutex);
+
+	return err ? err : count;
+}
+KSM_ATTR(merge_across_nodes);
+#endif
+
+static ssize_t pages_shared_show(struct kobject *kobj,
+				 struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", ksm_pages_shared);
+}
+KSM_ATTR_RO(pages_shared);
+
+static ssize_t pages_sharing_show(struct kobject *kobj,
+				  struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", ksm_pages_sharing);
+}
+KSM_ATTR_RO(pages_sharing);
+
+static ssize_t pages_unshared_show(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", ksm_pages_unshared);
+}
+KSM_ATTR_RO(pages_unshared);
+
+static ssize_t pages_volatile_show(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *buf)
+{
+	long ksm_pages_volatile;
+
+	ksm_pages_volatile = ksm_rmap_items - ksm_pages_shared
+				- ksm_pages_sharing - ksm_pages_unshared;
+	/*
+	 * It was not worth any locking to calculate that statistic,
+	 * but it might therefore sometimes be negative: conceal that.
+	 */
+	if (ksm_pages_volatile < 0)
+		ksm_pages_volatile = 0;
+	return sprintf(buf, "%ld\n", ksm_pages_volatile);
+}
+KSM_ATTR_RO(pages_volatile);
+
+static ssize_t full_scans_show(struct kobject *kobj,
+			       struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", ksm_scan.seqnr);
+}
+KSM_ATTR_RO(full_scans);
+
+static struct attribute *ksm_attrs[] = {
+	&sleep_millisecs_attr.attr,
+	&pages_to_scan_attr.attr,
+	&run_attr.attr,
+	&pages_shared_attr.attr,
+	&pages_sharing_attr.attr,
+	&pages_unshared_attr.attr,
+	&pages_volatile_attr.attr,
+	&full_scans_attr.attr,
+#ifdef CONFIG_NUMA
+	&merge_across_nodes_attr.attr,
+#endif
+	NULL,
+};
+
+static struct attribute_group ksm_attr_group = {
+	.attrs = ksm_attrs,
+	.name = "ksm",
+};
+#endif /* CONFIG_SYSFS */
+
+static int __init ksm_init(void)
+{
+	struct task_struct *ksm_thread;
+	int err;
+
+	err = ksm_slab_init();
+	if (err)
+		goto out;
+
+	ksm_thread = kthread_run(ksm_scan_thread, NULL, "ksmd");
+	if (IS_ERR(ksm_thread)) {
+		pr_err("ksm: creating kthread failed\n");
+		err = PTR_ERR(ksm_thread);
+		goto out_free;
+	}
+
+#ifdef CONFIG_SYSFS
+	err = sysfs_create_group(mm_kobj, &ksm_attr_group);
+	if (err) {
+		pr_err("ksm: register sysfs failed\n");
+		kthread_stop(ksm_thread);
+		goto out_free;
+	}
+#else
+	ksm_run = KSM_RUN_MERGE;	/* no way for user to start it */
+
+#endif /* CONFIG_SYSFS */
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+	/* There is no significance to this priority 100 */
+	hotplug_memory_notifier(ksm_memory_callback, 100);
+#endif
+	return 0;
+
+out_free:
+	ksm_slab_free();
+out:
+	return err;
+}
+subsys_initcall(ksm_init);
diff --git a/mm/list_lru.c b/mm/list_lru.c
new file mode 100644
index 0000000..786176b
--- /dev/null
+++ b/mm/list_lru.c
@@ -0,0 +1,583 @@
+/*
+ * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
+ * Authors: David Chinner and Glauber Costa
+ *
+ * Generic LRU infrastructure
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/list_lru.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/memcontrol.h>
+
+#ifdef CONFIG_MEMCG_KMEM
+static LIST_HEAD(list_lrus);
+static DEFINE_MUTEX(list_lrus_mutex);
+
+static void list_lru_register(struct list_lru *lru)
+{
+	mutex_lock(&list_lrus_mutex);
+	list_add(&lru->list, &list_lrus);
+	mutex_unlock(&list_lrus_mutex);
+}
+
+static void list_lru_unregister(struct list_lru *lru)
+{
+	mutex_lock(&list_lrus_mutex);
+	list_del(&lru->list);
+	mutex_unlock(&list_lrus_mutex);
+}
+#else
+static void list_lru_register(struct list_lru *lru)
+{
+}
+
+static void list_lru_unregister(struct list_lru *lru)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+#ifdef CONFIG_MEMCG_KMEM
+static inline bool list_lru_memcg_aware(struct list_lru *lru)
+{
+	/*
+	 * This needs node 0 to be always present, even
+	 * in the systems supporting sparse numa ids.
+	 */
+	return !!lru->node[0].memcg_lrus;
+}
+
+static inline struct list_lru_one *
+list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
+{
+	/*
+	 * The lock protects the array of per cgroup lists from relocation
+	 * (see memcg_update_list_lru_node).
+	 */
+	lockdep_assert_held(&nlru->lock);
+	if (nlru->memcg_lrus && idx >= 0)
+		return nlru->memcg_lrus->lru[idx];
+
+	return &nlru->lru;
+}
+
+static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
+{
+	struct page *page;
+
+	if (!memcg_kmem_enabled())
+		return NULL;
+	page = virt_to_head_page(ptr);
+	return page->mem_cgroup;
+}
+
+static inline struct list_lru_one *
+list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
+{
+	struct mem_cgroup *memcg;
+
+	if (!nlru->memcg_lrus)
+		return &nlru->lru;
+
+	memcg = mem_cgroup_from_kmem(ptr);
+	if (!memcg)
+		return &nlru->lru;
+
+	return list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
+}
+#else
+static inline bool list_lru_memcg_aware(struct list_lru *lru)
+{
+	return false;
+}
+
+static inline struct list_lru_one *
+list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
+{
+	return &nlru->lru;
+}
+
+static inline struct list_lru_one *
+list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
+{
+	return &nlru->lru;
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+bool list_lru_add(struct list_lru *lru, struct list_head *item)
+{
+	int nid = page_to_nid(virt_to_page(item));
+	struct list_lru_node *nlru = &lru->node[nid];
+	struct list_lru_one *l;
+
+	spin_lock(&nlru->lock);
+	if (list_empty(item)) {
+		l = list_lru_from_kmem(nlru, item);
+		list_add_tail(item, &l->list);
+		l->nr_items++;
+		nlru->nr_items++;
+		spin_unlock(&nlru->lock);
+		return true;
+	}
+	spin_unlock(&nlru->lock);
+	return false;
+}
+EXPORT_SYMBOL_GPL(list_lru_add);
+
+bool list_lru_del(struct list_lru *lru, struct list_head *item)
+{
+	int nid = page_to_nid(virt_to_page(item));
+	struct list_lru_node *nlru = &lru->node[nid];
+	struct list_lru_one *l;
+
+	spin_lock(&nlru->lock);
+	if (!list_empty(item)) {
+		l = list_lru_from_kmem(nlru, item);
+		list_del_init(item);
+		l->nr_items--;
+		nlru->nr_items--;
+		spin_unlock(&nlru->lock);
+		return true;
+	}
+	spin_unlock(&nlru->lock);
+	return false;
+}
+EXPORT_SYMBOL_GPL(list_lru_del);
+
+void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
+{
+	list_del_init(item);
+	list->nr_items--;
+}
+EXPORT_SYMBOL_GPL(list_lru_isolate);
+
+void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
+			   struct list_head *head)
+{
+	list_move(item, head);
+	list->nr_items--;
+}
+EXPORT_SYMBOL_GPL(list_lru_isolate_move);
+
+static unsigned long __list_lru_count_one(struct list_lru *lru,
+					  int nid, int memcg_idx)
+{
+	struct list_lru_node *nlru = &lru->node[nid];
+	struct list_lru_one *l;
+	unsigned long count;
+
+	spin_lock(&nlru->lock);
+	l = list_lru_from_memcg_idx(nlru, memcg_idx);
+	count = l->nr_items;
+	spin_unlock(&nlru->lock);
+
+	return count;
+}
+
+unsigned long list_lru_count_one(struct list_lru *lru,
+				 int nid, struct mem_cgroup *memcg)
+{
+	return __list_lru_count_one(lru, nid, memcg_cache_id(memcg));
+}
+EXPORT_SYMBOL_GPL(list_lru_count_one);
+
+unsigned long list_lru_count_node(struct list_lru *lru, int nid)
+{
+	struct list_lru_node *nlru;
+
+	nlru = &lru->node[nid];
+	return nlru->nr_items;
+}
+EXPORT_SYMBOL_GPL(list_lru_count_node);
+
+static unsigned long
+__list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
+		    list_lru_walk_cb isolate, void *cb_arg,
+		    unsigned long *nr_to_walk)
+{
+
+	struct list_lru_node *nlru = &lru->node[nid];
+	struct list_lru_one *l;
+	struct list_head *item, *n;
+	unsigned long isolated = 0;
+
+	spin_lock(&nlru->lock);
+	l = list_lru_from_memcg_idx(nlru, memcg_idx);
+restart:
+	list_for_each_safe(item, n, &l->list) {
+		enum lru_status ret;
+
+		/*
+		 * decrement nr_to_walk first so that we don't livelock if we
+		 * get stuck on large numbesr of LRU_RETRY items
+		 */
+		if (!*nr_to_walk)
+			break;
+		--*nr_to_walk;
+
+		ret = isolate(item, l, &nlru->lock, cb_arg);
+		switch (ret) {
+		case LRU_REMOVED_RETRY:
+			assert_spin_locked(&nlru->lock);
+		case LRU_REMOVED:
+			isolated++;
+			nlru->nr_items--;
+			/*
+			 * If the lru lock has been dropped, our list
+			 * traversal is now invalid and so we have to
+			 * restart from scratch.
+			 */
+			if (ret == LRU_REMOVED_RETRY)
+				goto restart;
+			break;
+		case LRU_ROTATE:
+			list_move_tail(item, &l->list);
+			break;
+		case LRU_SKIP:
+			break;
+		case LRU_RETRY:
+			/*
+			 * The lru lock has been dropped, our list traversal is
+			 * now invalid and so we have to restart from scratch.
+			 */
+			assert_spin_locked(&nlru->lock);
+			goto restart;
+		default:
+			BUG();
+		}
+	}
+
+	spin_unlock(&nlru->lock);
+	return isolated;
+}
+
+unsigned long
+list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
+		  list_lru_walk_cb isolate, void *cb_arg,
+		  unsigned long *nr_to_walk)
+{
+	return __list_lru_walk_one(lru, nid, memcg_cache_id(memcg),
+				   isolate, cb_arg, nr_to_walk);
+}
+EXPORT_SYMBOL_GPL(list_lru_walk_one);
+
+unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
+				 list_lru_walk_cb isolate, void *cb_arg,
+				 unsigned long *nr_to_walk)
+{
+	long isolated = 0;
+	int memcg_idx;
+
+	isolated += __list_lru_walk_one(lru, nid, -1, isolate, cb_arg,
+					nr_to_walk);
+	if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
+		for_each_memcg_cache_index(memcg_idx) {
+			isolated += __list_lru_walk_one(lru, nid, memcg_idx,
+						isolate, cb_arg, nr_to_walk);
+			if (*nr_to_walk <= 0)
+				break;
+		}
+	}
+	return isolated;
+}
+EXPORT_SYMBOL_GPL(list_lru_walk_node);
+
+static void init_one_lru(struct list_lru_one *l)
+{
+	INIT_LIST_HEAD(&l->list);
+	l->nr_items = 0;
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+static void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus,
+					  int begin, int end)
+{
+	int i;
+
+	for (i = begin; i < end; i++)
+		kfree(memcg_lrus->lru[i]);
+}
+
+static int __memcg_init_list_lru_node(struct list_lru_memcg *memcg_lrus,
+				      int begin, int end)
+{
+	int i;
+
+	for (i = begin; i < end; i++) {
+		struct list_lru_one *l;
+
+		l = kmalloc(sizeof(struct list_lru_one), GFP_KERNEL);
+		if (!l)
+			goto fail;
+
+		init_one_lru(l);
+		memcg_lrus->lru[i] = l;
+	}
+	return 0;
+fail:
+	__memcg_destroy_list_lru_node(memcg_lrus, begin, i - 1);
+	return -ENOMEM;
+}
+
+static int memcg_init_list_lru_node(struct list_lru_node *nlru)
+{
+	int size = memcg_nr_cache_ids;
+
+	nlru->memcg_lrus = kmalloc(size * sizeof(void *), GFP_KERNEL);
+	if (!nlru->memcg_lrus)
+		return -ENOMEM;
+
+	if (__memcg_init_list_lru_node(nlru->memcg_lrus, 0, size)) {
+		kfree(nlru->memcg_lrus);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void memcg_destroy_list_lru_node(struct list_lru_node *nlru)
+{
+	__memcg_destroy_list_lru_node(nlru->memcg_lrus, 0, memcg_nr_cache_ids);
+	kfree(nlru->memcg_lrus);
+}
+
+static int memcg_update_list_lru_node(struct list_lru_node *nlru,
+				      int old_size, int new_size)
+{
+	struct list_lru_memcg *old, *new;
+
+	BUG_ON(old_size > new_size);
+
+	old = nlru->memcg_lrus;
+	new = kmalloc(new_size * sizeof(void *), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	if (__memcg_init_list_lru_node(new, old_size, new_size)) {
+		kfree(new);
+		return -ENOMEM;
+	}
+
+	memcpy(new, old, old_size * sizeof(void *));
+
+	/*
+	 * The lock guarantees that we won't race with a reader
+	 * (see list_lru_from_memcg_idx).
+	 *
+	 * Since list_lru_{add,del} may be called under an IRQ-safe lock,
+	 * we have to use IRQ-safe primitives here to avoid deadlock.
+	 */
+	spin_lock_irq(&nlru->lock);
+	nlru->memcg_lrus = new;
+	spin_unlock_irq(&nlru->lock);
+
+	kfree(old);
+	return 0;
+}
+
+static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru,
+					      int old_size, int new_size)
+{
+	/* do not bother shrinking the array back to the old size, because we
+	 * cannot handle allocation failures here */
+	__memcg_destroy_list_lru_node(nlru->memcg_lrus, old_size, new_size);
+}
+
+static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
+{
+	int i;
+
+	if (!memcg_aware)
+		return 0;
+
+	for_each_node(i) {
+		if (memcg_init_list_lru_node(&lru->node[i]))
+			goto fail;
+	}
+	return 0;
+fail:
+	for (i = i - 1; i >= 0; i--) {
+		if (!lru->node[i].memcg_lrus)
+			continue;
+		memcg_destroy_list_lru_node(&lru->node[i]);
+	}
+	return -ENOMEM;
+}
+
+static void memcg_destroy_list_lru(struct list_lru *lru)
+{
+	int i;
+
+	if (!list_lru_memcg_aware(lru))
+		return;
+
+	for_each_node(i)
+		memcg_destroy_list_lru_node(&lru->node[i]);
+}
+
+static int memcg_update_list_lru(struct list_lru *lru,
+				 int old_size, int new_size)
+{
+	int i;
+
+	if (!list_lru_memcg_aware(lru))
+		return 0;
+
+	for_each_node(i) {
+		if (memcg_update_list_lru_node(&lru->node[i],
+					       old_size, new_size))
+			goto fail;
+	}
+	return 0;
+fail:
+	for (i = i - 1; i >= 0; i--) {
+		if (!lru->node[i].memcg_lrus)
+			continue;
+
+		memcg_cancel_update_list_lru_node(&lru->node[i],
+						  old_size, new_size);
+	}
+	return -ENOMEM;
+}
+
+static void memcg_cancel_update_list_lru(struct list_lru *lru,
+					 int old_size, int new_size)
+{
+	int i;
+
+	if (!list_lru_memcg_aware(lru))
+		return;
+
+	for_each_node(i)
+		memcg_cancel_update_list_lru_node(&lru->node[i],
+						  old_size, new_size);
+}
+
+int memcg_update_all_list_lrus(int new_size)
+{
+	int ret = 0;
+	struct list_lru *lru;
+	int old_size = memcg_nr_cache_ids;
+
+	mutex_lock(&list_lrus_mutex);
+	list_for_each_entry(lru, &list_lrus, list) {
+		ret = memcg_update_list_lru(lru, old_size, new_size);
+		if (ret)
+			goto fail;
+	}
+out:
+	mutex_unlock(&list_lrus_mutex);
+	return ret;
+fail:
+	list_for_each_entry_continue_reverse(lru, &list_lrus, list)
+		memcg_cancel_update_list_lru(lru, old_size, new_size);
+	goto out;
+}
+
+static void memcg_drain_list_lru_node(struct list_lru_node *nlru,
+				      int src_idx, int dst_idx)
+{
+	struct list_lru_one *src, *dst;
+
+	/*
+	 * Since list_lru_{add,del} may be called under an IRQ-safe lock,
+	 * we have to use IRQ-safe primitives here to avoid deadlock.
+	 */
+	spin_lock_irq(&nlru->lock);
+
+	src = list_lru_from_memcg_idx(nlru, src_idx);
+	dst = list_lru_from_memcg_idx(nlru, dst_idx);
+
+	list_splice_init(&src->list, &dst->list);
+	dst->nr_items += src->nr_items;
+	src->nr_items = 0;
+
+	spin_unlock_irq(&nlru->lock);
+}
+
+static void memcg_drain_list_lru(struct list_lru *lru,
+				 int src_idx, int dst_idx)
+{
+	int i;
+
+	if (!list_lru_memcg_aware(lru))
+		return;
+
+	for_each_node(i)
+		memcg_drain_list_lru_node(&lru->node[i], src_idx, dst_idx);
+}
+
+void memcg_drain_all_list_lrus(int src_idx, int dst_idx)
+{
+	struct list_lru *lru;
+
+	mutex_lock(&list_lrus_mutex);
+	list_for_each_entry(lru, &list_lrus, list)
+		memcg_drain_list_lru(lru, src_idx, dst_idx);
+	mutex_unlock(&list_lrus_mutex);
+}
+#else
+static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
+{
+	return 0;
+}
+
+static void memcg_destroy_list_lru(struct list_lru *lru)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+int __list_lru_init(struct list_lru *lru, bool memcg_aware,
+		    struct lock_class_key *key)
+{
+	int i;
+	size_t size = sizeof(*lru->node) * nr_node_ids;
+	int err = -ENOMEM;
+
+	memcg_get_cache_ids();
+
+	lru->node = kzalloc(size, GFP_KERNEL);
+	if (!lru->node)
+		goto out;
+
+	for_each_node(i) {
+		spin_lock_init(&lru->node[i].lock);
+		if (key)
+			lockdep_set_class(&lru->node[i].lock, key);
+		init_one_lru(&lru->node[i].lru);
+	}
+
+	err = memcg_init_list_lru(lru, memcg_aware);
+	if (err) {
+		kfree(lru->node);
+		/* Do this so a list_lru_destroy() doesn't crash: */
+		lru->node = NULL;
+		goto out;
+	}
+
+	list_lru_register(lru);
+out:
+	memcg_put_cache_ids();
+	return err;
+}
+EXPORT_SYMBOL_GPL(__list_lru_init);
+
+void list_lru_destroy(struct list_lru *lru)
+{
+	/* Already destroyed or not yet initialized? */
+	if (!lru->node)
+		return;
+
+	memcg_get_cache_ids();
+
+	list_lru_unregister(lru);
+
+	memcg_destroy_list_lru(lru);
+	kfree(lru->node);
+	lru->node = NULL;
+
+	memcg_put_cache_ids();
+}
+EXPORT_SYMBOL_GPL(list_lru_destroy);
diff --git a/mm/maccess.c b/mm/maccess.c
new file mode 100644
index 0000000..d159b1c
--- /dev/null
+++ b/mm/maccess.c
@@ -0,0 +1,108 @@
+/*
+ * Access kernel memory without faulting.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/uaccess.h>
+
+/**
+ * probe_kernel_read(): safely attempt to read from a location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from address @src to the buffer at @dst.  If a kernel fault
+ * happens, handle that and return -EFAULT.
+ *
+ * We ensure that the copy_from_user is executed in atomic context so that
+ * do_page_fault() doesn't attempt to take mmap_sem.  This makes
+ * probe_kernel_read() suitable for use within regions where the caller
+ * already holds mmap_sem, or other locks which nest inside mmap_sem.
+ */
+
+long __weak probe_kernel_read(void *dst, const void *src, size_t size)
+    __attribute__((alias("__probe_kernel_read")));
+
+long __probe_kernel_read(void *dst, const void *src, size_t size)
+{
+	long ret;
+	mm_segment_t old_fs = get_fs();
+
+	set_fs(KERNEL_DS);
+	pagefault_disable();
+	ret = __copy_from_user_inatomic(dst,
+			(__force const void __user *)src, size);
+	pagefault_enable();
+	set_fs(old_fs);
+
+	return ret ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
+
+/**
+ * probe_kernel_write(): safely attempt to write to a location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src.  If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long __weak probe_kernel_write(void *dst, const void *src, size_t size)
+    __attribute__((alias("__probe_kernel_write")));
+
+long __probe_kernel_write(void *dst, const void *src, size_t size)
+{
+	long ret;
+	mm_segment_t old_fs = get_fs();
+
+	set_fs(KERNEL_DS);
+	pagefault_disable();
+	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
+	pagefault_enable();
+	set_fs(old_fs);
+
+	return ret ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_write);
+
+/**
+ * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address.
+ * @dst:   Destination address, in kernel space.  This buffer must be at
+ *         least @count bytes long.
+ * @src:   Unsafe address.
+ * @count: Maximum number of bytes to copy, including the trailing NUL.
+ *
+ * Copies a NUL-terminated string from unsafe address to kernel buffer.
+ *
+ * On success, returns the length of the string INCLUDING the trailing NUL.
+ *
+ * If access fails, returns -EFAULT (some data may have been copied
+ * and the trailing NUL added).
+ *
+ * If @count is smaller than the length of the string, copies @count-1 bytes,
+ * sets the last byte of @dst buffer to NUL and returns @count.
+ */
+long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
+{
+	mm_segment_t old_fs = get_fs();
+	const void *src = unsafe_addr;
+	long ret;
+
+	if (unlikely(count <= 0))
+		return 0;
+
+	set_fs(KERNEL_DS);
+	pagefault_disable();
+
+	do {
+		ret = __copy_from_user_inatomic(dst++,
+						(const void __user __force *)src++, 1);
+	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
+
+	dst[-1] = '\0';
+	pagefault_enable();
+	set_fs(old_fs);
+
+	return ret ? -EFAULT : src - unsafe_addr;
+}
diff --git a/mm/madvise.c b/mm/madvise.c
new file mode 100644
index 0000000..c889fcb
--- /dev/null
+++ b/mm/madvise.c
@@ -0,0 +1,551 @@
+/*
+ *	linux/mm/madvise.c
+ *
+ * Copyright (C) 1999  Linus Torvalds
+ * Copyright (C) 2002  Christoph Hellwig
+ */
+
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/syscalls.h>
+#include <linux/mempolicy.h>
+#include <linux/page-isolation.h>
+#include <linux/hugetlb.h>
+#include <linux/falloc.h>
+#include <linux/sched.h>
+#include <linux/ksm.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+
+/*
+ * Any behaviour which results in changes to the vma->vm_flags needs to
+ * take mmap_sem for writing. Others, which simply traverse vmas, need
+ * to only take it for reading.
+ */
+static int madvise_need_mmap_write(int behavior)
+{
+	switch (behavior) {
+	case MADV_REMOVE:
+	case MADV_WILLNEED:
+	case MADV_DONTNEED:
+		return 0;
+	default:
+		/* be safe, default to 1. list exceptions explicitly */
+		return 1;
+	}
+}
+
+/*
+ * We can potentially split a vm area into separate
+ * areas, each area with its own behavior.
+ */
+static long madvise_behavior(struct vm_area_struct *vma,
+		     struct vm_area_struct **prev,
+		     unsigned long start, unsigned long end, int behavior)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int error = 0;
+	pgoff_t pgoff;
+	unsigned long new_flags = vma->vm_flags;
+
+	switch (behavior) {
+	case MADV_NORMAL:
+		new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
+		break;
+	case MADV_SEQUENTIAL:
+		new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
+		break;
+	case MADV_RANDOM:
+		new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
+		break;
+	case MADV_DONTFORK:
+		new_flags |= VM_DONTCOPY;
+		break;
+	case MADV_DOFORK:
+		if (vma->vm_flags & VM_IO) {
+			error = -EINVAL;
+			goto out;
+		}
+		new_flags &= ~VM_DONTCOPY;
+		break;
+	case MADV_DONTDUMP:
+		new_flags |= VM_DONTDUMP;
+		break;
+	case MADV_DODUMP:
+		if (new_flags & VM_SPECIAL) {
+			error = -EINVAL;
+			goto out;
+		}
+		new_flags &= ~VM_DONTDUMP;
+		break;
+	case MADV_MERGEABLE:
+	case MADV_UNMERGEABLE:
+		error = ksm_madvise(vma, start, end, behavior, &new_flags);
+		if (error)
+			goto out;
+		break;
+	case MADV_HUGEPAGE:
+	case MADV_NOHUGEPAGE:
+		error = hugepage_madvise(vma, &new_flags, behavior);
+		if (error)
+			goto out;
+		break;
+	}
+
+	if (new_flags == vma->vm_flags) {
+		*prev = vma;
+		goto out;
+	}
+
+	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+	*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
+			  vma->vm_file, pgoff, vma_policy(vma),
+			  vma->vm_userfaultfd_ctx);
+	if (*prev) {
+		vma = *prev;
+		goto success;
+	}
+
+	*prev = vma;
+
+	if (start != vma->vm_start) {
+		error = split_vma(mm, vma, start, 1);
+		if (error)
+			goto out;
+	}
+
+	if (end != vma->vm_end) {
+		error = split_vma(mm, vma, end, 0);
+		if (error)
+			goto out;
+	}
+
+success:
+	/*
+	 * vm_flags is protected by the mmap_sem held in write mode.
+	 */
+	vma->vm_flags = new_flags;
+
+out:
+	if (error == -ENOMEM)
+		error = -EAGAIN;
+	return error;
+}
+
+#ifdef CONFIG_SWAP
+static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
+	unsigned long end, struct mm_walk *walk)
+{
+	pte_t *orig_pte;
+	struct vm_area_struct *vma = walk->private;
+	unsigned long index;
+
+	if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+		return 0;
+
+	for (index = start; index != end; index += PAGE_SIZE) {
+		pte_t pte;
+		swp_entry_t entry;
+		struct page *page;
+		spinlock_t *ptl;
+
+		orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
+		pte = *(orig_pte + ((index - start) / PAGE_SIZE));
+		pte_unmap_unlock(orig_pte, ptl);
+
+		if (pte_present(pte) || pte_none(pte))
+			continue;
+		entry = pte_to_swp_entry(pte);
+		if (unlikely(non_swap_entry(entry)))
+			continue;
+
+		page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
+								vma, index);
+		if (page)
+			page_cache_release(page);
+	}
+
+	return 0;
+}
+
+static void force_swapin_readahead(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end)
+{
+	struct mm_walk walk = {
+		.mm = vma->vm_mm,
+		.pmd_entry = swapin_walk_pmd_entry,
+		.private = vma,
+	};
+
+	walk_page_range(start, end, &walk);
+
+	lru_add_drain();	/* Push any new pages onto the LRU now */
+}
+
+static void force_shm_swapin_readahead(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end,
+		struct address_space *mapping)
+{
+	pgoff_t index;
+	struct page *page;
+	swp_entry_t swap;
+
+	for (; start < end; start += PAGE_SIZE) {
+		index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+
+		page = find_get_entry(mapping, index);
+		if (!radix_tree_exceptional_entry(page)) {
+			if (page)
+				page_cache_release(page);
+			continue;
+		}
+		swap = radix_to_swp_entry(page);
+		page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
+								NULL, 0);
+		if (page)
+			page_cache_release(page);
+	}
+
+	lru_add_drain();	/* Push any new pages onto the LRU now */
+}
+#endif		/* CONFIG_SWAP */
+
+/*
+ * Schedule all required I/O operations.  Do not wait for completion.
+ */
+static long madvise_willneed(struct vm_area_struct *vma,
+			     struct vm_area_struct **prev,
+			     unsigned long start, unsigned long end)
+{
+	struct file *file = vma->vm_file;
+
+#ifdef CONFIG_SWAP
+	if (!file) {
+		*prev = vma;
+		force_swapin_readahead(vma, start, end);
+		return 0;
+	}
+
+	if (shmem_mapping(file->f_mapping)) {
+		*prev = vma;
+		force_shm_swapin_readahead(vma, start, end,
+					file->f_mapping);
+		return 0;
+	}
+#else
+	if (!file)
+		return -EBADF;
+#endif
+
+	if (IS_DAX(file_inode(file))) {
+		/* no bad return value, but ignore advice */
+		return 0;
+	}
+
+	*prev = vma;
+	start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+	if (end > vma->vm_end)
+		end = vma->vm_end;
+	end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+
+	force_page_cache_readahead(file->f_mapping, file, start, end - start);
+	return 0;
+}
+
+/*
+ * Application no longer needs these pages.  If the pages are dirty,
+ * it's OK to just throw them away.  The app will be more careful about
+ * data it wants to keep.  Be sure to free swap resources too.  The
+ * zap_page_range call sets things up for shrink_active_list to actually free
+ * these pages later if no one else has touched them in the meantime,
+ * although we could add these pages to a global reuse list for
+ * shrink_active_list to pick up before reclaiming other pages.
+ *
+ * NB: This interface discards data rather than pushes it out to swap,
+ * as some implementations do.  This has performance implications for
+ * applications like large transactional databases which want to discard
+ * pages in anonymous maps after committing to backing store the data
+ * that was kept in them.  There is no reason to write this data out to
+ * the swap area if the application is discarding it.
+ *
+ * An interface that causes the system to free clean pages and flush
+ * dirty pages is already available as msync(MS_INVALIDATE).
+ */
+static long madvise_dontneed(struct vm_area_struct *vma,
+			     struct vm_area_struct **prev,
+			     unsigned long start, unsigned long end)
+{
+	*prev = vma;
+	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
+		return -EINVAL;
+
+	zap_page_range(vma, start, end - start, NULL);
+	return 0;
+}
+
+/*
+ * Application wants to free up the pages and associated backing store.
+ * This is effectively punching a hole into the middle of a file.
+ */
+static long madvise_remove(struct vm_area_struct *vma,
+				struct vm_area_struct **prev,
+				unsigned long start, unsigned long end)
+{
+	loff_t offset;
+	int error;
+	struct file *f;
+
+	*prev = NULL;	/* tell sys_madvise we drop mmap_sem */
+
+	if (vma->vm_flags & VM_LOCKED)
+		return -EINVAL;
+
+	f = vma->vm_file;
+
+	if (!f || !f->f_mapping || !f->f_mapping->host) {
+			return -EINVAL;
+	}
+
+	if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
+		return -EACCES;
+
+	offset = (loff_t)(start - vma->vm_start)
+			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+
+	/*
+	 * Filesystem's fallocate may need to take i_mutex.  We need to
+	 * explicitly grab a reference because the vma (and hence the
+	 * vma's reference to the file) can go away as soon as we drop
+	 * mmap_sem.
+	 */
+	get_file(f);
+	up_read(&current->mm->mmap_sem);
+	error = vfs_fallocate(f,
+				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+				offset, end - start);
+	fput(f);
+	down_read(&current->mm->mmap_sem);
+	return error;
+}
+
+#ifdef CONFIG_MEMORY_FAILURE
+/*
+ * Error injection support for memory error handling.
+ */
+static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
+{
+	struct page *p;
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	for (; start < end; start += PAGE_SIZE <<
+				compound_order(compound_head(p))) {
+		int ret;
+
+		ret = get_user_pages_fast(start, 1, 0, &p);
+		if (ret != 1)
+			return ret;
+
+		if (PageHWPoison(p)) {
+			put_page(p);
+			continue;
+		}
+		if (bhv == MADV_SOFT_OFFLINE) {
+			pr_info("Soft offlining page %#lx at %#lx\n",
+				page_to_pfn(p), start);
+			ret = soft_offline_page(p, MF_COUNT_INCREASED);
+			if (ret)
+				return ret;
+			continue;
+		}
+		pr_info("Injecting memory failure for page %#lx at %#lx\n",
+		       page_to_pfn(p), start);
+		/* Ignore return value for now */
+		memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
+	}
+	return 0;
+}
+#endif
+
+static long
+madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
+		unsigned long start, unsigned long end, int behavior)
+{
+	switch (behavior) {
+	case MADV_REMOVE:
+		return madvise_remove(vma, prev, start, end);
+	case MADV_WILLNEED:
+		return madvise_willneed(vma, prev, start, end);
+	case MADV_DONTNEED:
+		return madvise_dontneed(vma, prev, start, end);
+	default:
+		return madvise_behavior(vma, prev, start, end, behavior);
+	}
+}
+
+static bool
+madvise_behavior_valid(int behavior)
+{
+	switch (behavior) {
+	case MADV_DOFORK:
+	case MADV_DONTFORK:
+	case MADV_NORMAL:
+	case MADV_SEQUENTIAL:
+	case MADV_RANDOM:
+	case MADV_REMOVE:
+	case MADV_WILLNEED:
+	case MADV_DONTNEED:
+#ifdef CONFIG_KSM
+	case MADV_MERGEABLE:
+	case MADV_UNMERGEABLE:
+#endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	case MADV_HUGEPAGE:
+	case MADV_NOHUGEPAGE:
+#endif
+	case MADV_DONTDUMP:
+	case MADV_DODUMP:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
+/*
+ * The madvise(2) system call.
+ *
+ * Applications can use madvise() to advise the kernel how it should
+ * handle paging I/O in this VM area.  The idea is to help the kernel
+ * use appropriate read-ahead and caching techniques.  The information
+ * provided is advisory only, and can be safely disregarded by the
+ * kernel without affecting the correct operation of the application.
+ *
+ * behavior values:
+ *  MADV_NORMAL - the default behavior is to read clusters.  This
+ *		results in some read-ahead and read-behind.
+ *  MADV_RANDOM - the system should read the minimum amount of data
+ *		on any access, since it is unlikely that the appli-
+ *		cation will need more than what it asks for.
+ *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
+ *		once, so they can be aggressively read ahead, and
+ *		can be freed soon after they are accessed.
+ *  MADV_WILLNEED - the application is notifying the system to read
+ *		some pages ahead.
+ *  MADV_DONTNEED - the application is finished with the given range,
+ *		so the kernel can free resources associated with it.
+ *  MADV_REMOVE - the application wants to free up the given range of
+ *		pages and associated backing store.
+ *  MADV_DONTFORK - omit this area from child's address space when forking:
+ *		typically, to avoid COWing pages pinned by get_user_pages().
+ *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
+ *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
+ *		this area with pages of identical content from other such areas.
+ *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
+ *
+ * return values:
+ *  zero    - success
+ *  -EINVAL - start + len < 0, start is not page-aligned,
+ *		"behavior" is not a valid value, or application
+ *		is attempting to release locked or shared pages.
+ *  -ENOMEM - addresses in the specified range are not currently
+ *		mapped, or are outside the AS of the process.
+ *  -EIO    - an I/O error occurred while paging in data.
+ *  -EBADF  - map exists, but area maps something that isn't a file.
+ *  -EAGAIN - a kernel resource was temporarily unavailable.
+ */
+SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
+{
+	unsigned long end, tmp;
+	struct vm_area_struct *vma, *prev;
+	int unmapped_error = 0;
+	int error = -EINVAL;
+	int write;
+	size_t len;
+	struct blk_plug plug;
+
+#ifdef CONFIG_MEMORY_FAILURE
+	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
+		return madvise_hwpoison(behavior, start, start+len_in);
+#endif
+	if (!madvise_behavior_valid(behavior))
+		return error;
+
+	if (start & ~PAGE_MASK)
+		return error;
+	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
+
+	/* Check to see whether len was rounded up from small -ve to zero */
+	if (len_in && !len)
+		return error;
+
+	end = start + len;
+	if (end < start)
+		return error;
+
+	error = 0;
+	if (end == start)
+		return error;
+
+	write = madvise_need_mmap_write(behavior);
+	if (write)
+		down_write(&current->mm->mmap_sem);
+	else
+		down_read(&current->mm->mmap_sem);
+
+	/*
+	 * If the interval [start,end) covers some unmapped address
+	 * ranges, just ignore them, but return -ENOMEM at the end.
+	 * - different from the way of handling in mlock etc.
+	 */
+	vma = find_vma_prev(current->mm, start, &prev);
+	if (vma && start > vma->vm_start)
+		prev = vma;
+
+	blk_start_plug(&plug);
+	for (;;) {
+		/* Still start < end. */
+		error = -ENOMEM;
+		if (!vma)
+			goto out;
+
+		/* Here start < (end|vma->vm_end). */
+		if (start < vma->vm_start) {
+			unmapped_error = -ENOMEM;
+			start = vma->vm_start;
+			if (start >= end)
+				goto out;
+		}
+
+		/* Here vma->vm_start <= start < (end|vma->vm_end) */
+		tmp = vma->vm_end;
+		if (end < tmp)
+			tmp = end;
+
+		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
+		error = madvise_vma(vma, &prev, start, tmp, behavior);
+		if (error)
+			goto out;
+		start = tmp;
+		if (prev && start < prev->vm_end)
+			start = prev->vm_end;
+		error = unmapped_error;
+		if (start >= end)
+			goto out;
+		if (prev)
+			vma = prev->vm_next;
+		else	/* madvise_remove dropped mmap_sem */
+			vma = find_vma(current->mm, start);
+	}
+out:
+	blk_finish_plug(&plug);
+	if (write)
+		up_write(&current->mm->mmap_sem);
+	else
+		up_read(&current->mm->mmap_sem);
+
+	return error;
+}
diff --git a/mm/memblock.c b/mm/memblock.c
new file mode 100644
index 0000000..f8fab45
--- /dev/null
+++ b/mm/memblock.c
@@ -0,0 +1,1736 @@
+/*
+ * Procedures for maintaining information about logical memory blocks.
+ *
+ * Peter Bergner, IBM Corp.	June 2001.
+ * Copyright (C) 2001 Peter Bergner.
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/bitops.h>
+#include <linux/poison.h>
+#include <linux/pfn.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/memblock.h>
+
+#include <asm-generic/sections.h>
+#include <linux/io.h>
+
+#include "internal.h"
+
+static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
+static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
+#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS] __initdata_memblock;
+#endif
+
+struct memblock memblock __initdata_memblock = {
+	.memory.regions		= memblock_memory_init_regions,
+	.memory.cnt		= 1,	/* empty dummy entry */
+	.memory.max		= INIT_MEMBLOCK_REGIONS,
+
+	.reserved.regions	= memblock_reserved_init_regions,
+	.reserved.cnt		= 1,	/* empty dummy entry */
+	.reserved.max		= INIT_MEMBLOCK_REGIONS,
+
+#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+	.physmem.regions	= memblock_physmem_init_regions,
+	.physmem.cnt		= 1,	/* empty dummy entry */
+	.physmem.max		= INIT_PHYSMEM_REGIONS,
+#endif
+
+	.bottom_up		= false,
+	.current_limit		= MEMBLOCK_ALLOC_ANYWHERE,
+};
+
+int memblock_debug __initdata_memblock;
+#ifdef CONFIG_MOVABLE_NODE
+bool movable_node_enabled __initdata_memblock = false;
+#endif
+static bool system_has_some_mirror __initdata_memblock = false;
+static int memblock_can_resize __initdata_memblock;
+static int memblock_memory_in_slab __initdata_memblock = 0;
+static int memblock_reserved_in_slab __initdata_memblock = 0;
+
+ulong __init_memblock choose_memblock_flags(void)
+{
+	return system_has_some_mirror ? MEMBLOCK_MIRROR : MEMBLOCK_NONE;
+}
+
+/* inline so we don't get a warning when pr_debug is compiled out */
+static __init_memblock const char *
+memblock_type_name(struct memblock_type *type)
+{
+	if (type == &memblock.memory)
+		return "memory";
+	else if (type == &memblock.reserved)
+		return "reserved";
+	else
+		return "unknown";
+}
+
+/* adjust *@size so that (@base + *@size) doesn't overflow, return new size */
+static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)
+{
+	return *size = min(*size, (phys_addr_t)ULLONG_MAX - base);
+}
+
+/*
+ * Address comparison utilities
+ */
+static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1,
+				       phys_addr_t base2, phys_addr_t size2)
+{
+	return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
+}
+
+bool __init_memblock memblock_overlaps_region(struct memblock_type *type,
+					phys_addr_t base, phys_addr_t size)
+{
+	unsigned long i;
+
+	for (i = 0; i < type->cnt; i++) {
+		phys_addr_t rgnbase = type->regions[i].base;
+		phys_addr_t rgnsize = type->regions[i].size;
+		if (memblock_addrs_overlap(base, size, rgnbase, rgnsize))
+			break;
+	}
+
+	return i < type->cnt;
+}
+
+/*
+ * __memblock_find_range_bottom_up - find free area utility in bottom-up
+ * @start: start of candidate range
+ * @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
+ * @size: size of free area to find
+ * @align: alignment of free area to find
+ * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ * @flags: pick from blocks based on memory attributes
+ *
+ * Utility called from memblock_find_in_range_node(), find free area bottom-up.
+ *
+ * RETURNS:
+ * Found address on success, 0 on failure.
+ */
+static phys_addr_t __init_memblock
+__memblock_find_range_bottom_up(phys_addr_t start, phys_addr_t end,
+				phys_addr_t size, phys_addr_t align, int nid,
+				ulong flags)
+{
+	phys_addr_t this_start, this_end, cand;
+	u64 i;
+
+	for_each_free_mem_range(i, nid, flags, &this_start, &this_end, NULL) {
+		this_start = clamp(this_start, start, end);
+		this_end = clamp(this_end, start, end);
+
+		cand = round_up(this_start, align);
+		if (cand < this_end && this_end - cand >= size)
+			return cand;
+	}
+
+	return 0;
+}
+
+/**
+ * __memblock_find_range_top_down - find free area utility, in top-down
+ * @start: start of candidate range
+ * @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
+ * @size: size of free area to find
+ * @align: alignment of free area to find
+ * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ * @flags: pick from blocks based on memory attributes
+ *
+ * Utility called from memblock_find_in_range_node(), find free area top-down.
+ *
+ * RETURNS:
+ * Found address on success, 0 on failure.
+ */
+static phys_addr_t __init_memblock
+__memblock_find_range_top_down(phys_addr_t start, phys_addr_t end,
+			       phys_addr_t size, phys_addr_t align, int nid,
+			       ulong flags)
+{
+	phys_addr_t this_start, this_end, cand;
+	u64 i;
+
+	for_each_free_mem_range_reverse(i, nid, flags, &this_start, &this_end,
+					NULL) {
+		this_start = clamp(this_start, start, end);
+		this_end = clamp(this_end, start, end);
+
+		if (this_end < size)
+			continue;
+
+		cand = round_down(this_end - size, align);
+		if (cand >= this_start)
+			return cand;
+	}
+
+	return 0;
+}
+
+/**
+ * memblock_find_in_range_node - find free area in given range and node
+ * @size: size of free area to find
+ * @align: alignment of free area to find
+ * @start: start of candidate range
+ * @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
+ * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ * @flags: pick from blocks based on memory attributes
+ *
+ * Find @size free area aligned to @align in the specified range and node.
+ *
+ * When allocation direction is bottom-up, the @start should be greater
+ * than the end of the kernel image. Otherwise, it will be trimmed. The
+ * reason is that we want the bottom-up allocation just near the kernel
+ * image so it is highly likely that the allocated memory and the kernel
+ * will reside in the same node.
+ *
+ * If bottom-up allocation failed, will try to allocate memory top-down.
+ *
+ * RETURNS:
+ * Found address on success, 0 on failure.
+ */
+phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size,
+					phys_addr_t align, phys_addr_t start,
+					phys_addr_t end, int nid, ulong flags)
+{
+	phys_addr_t kernel_end, ret;
+
+	/* pump up @end */
+	if (end == MEMBLOCK_ALLOC_ACCESSIBLE)
+		end = memblock.current_limit;
+
+	/* avoid allocating the first page */
+	start = max_t(phys_addr_t, start, PAGE_SIZE);
+	end = max(start, end);
+	kernel_end = __pa_symbol(_end);
+
+	/*
+	 * try bottom-up allocation only when bottom-up mode
+	 * is set and @end is above the kernel image.
+	 */
+	if (memblock_bottom_up() && end > kernel_end) {
+		phys_addr_t bottom_up_start;
+
+		/* make sure we will allocate above the kernel */
+		bottom_up_start = max(start, kernel_end);
+
+		/* ok, try bottom-up allocation first */
+		ret = __memblock_find_range_bottom_up(bottom_up_start, end,
+						      size, align, nid, flags);
+		if (ret)
+			return ret;
+
+		/*
+		 * we always limit bottom-up allocation above the kernel,
+		 * but top-down allocation doesn't have the limit, so
+		 * retrying top-down allocation may succeed when bottom-up
+		 * allocation failed.
+		 *
+		 * bottom-up allocation is expected to be fail very rarely,
+		 * so we use WARN_ONCE() here to see the stack trace if
+		 * fail happens.
+		 */
+		WARN_ONCE(1, "memblock: bottom-up allocation failed, "
+			     "memory hotunplug may be affected\n");
+	}
+
+	return __memblock_find_range_top_down(start, end, size, align, nid,
+					      flags);
+}
+
+/**
+ * memblock_find_in_range - find free area in given range
+ * @start: start of candidate range
+ * @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
+ * @size: size of free area to find
+ * @align: alignment of free area to find
+ *
+ * Find @size free area aligned to @align in the specified range.
+ *
+ * RETURNS:
+ * Found address on success, 0 on failure.
+ */
+phys_addr_t __init_memblock memblock_find_in_range(phys_addr_t start,
+					phys_addr_t end, phys_addr_t size,
+					phys_addr_t align)
+{
+	phys_addr_t ret;
+	ulong flags = choose_memblock_flags();
+
+again:
+	ret = memblock_find_in_range_node(size, align, start, end,
+					    NUMA_NO_NODE, flags);
+
+	if (!ret && (flags & MEMBLOCK_MIRROR)) {
+		pr_warn("Could not allocate %pap bytes of mirrored memory\n",
+			&size);
+		flags &= ~MEMBLOCK_MIRROR;
+		goto again;
+	}
+
+	return ret;
+}
+
+static void __init_memblock memblock_remove_region(struct memblock_type *type, unsigned long r)
+{
+	type->total_size -= type->regions[r].size;
+	memmove(&type->regions[r], &type->regions[r + 1],
+		(type->cnt - (r + 1)) * sizeof(type->regions[r]));
+	type->cnt--;
+
+	/* Special case for empty arrays */
+	if (type->cnt == 0) {
+		WARN_ON(type->total_size != 0);
+		type->cnt = 1;
+		type->regions[0].base = 0;
+		type->regions[0].size = 0;
+		type->regions[0].flags = 0;
+		memblock_set_region_node(&type->regions[0], MAX_NUMNODES);
+	}
+}
+
+#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
+
+phys_addr_t __init_memblock get_allocated_memblock_reserved_regions_info(
+					phys_addr_t *addr)
+{
+	if (memblock.reserved.regions == memblock_reserved_init_regions)
+		return 0;
+
+	*addr = __pa(memblock.reserved.regions);
+
+	return PAGE_ALIGN(sizeof(struct memblock_region) *
+			  memblock.reserved.max);
+}
+
+phys_addr_t __init_memblock get_allocated_memblock_memory_regions_info(
+					phys_addr_t *addr)
+{
+	if (memblock.memory.regions == memblock_memory_init_regions)
+		return 0;
+
+	*addr = __pa(memblock.memory.regions);
+
+	return PAGE_ALIGN(sizeof(struct memblock_region) *
+			  memblock.memory.max);
+}
+
+#endif
+
+/**
+ * memblock_double_array - double the size of the memblock regions array
+ * @type: memblock type of the regions array being doubled
+ * @new_area_start: starting address of memory range to avoid overlap with
+ * @new_area_size: size of memory range to avoid overlap with
+ *
+ * Double the size of the @type regions array. If memblock is being used to
+ * allocate memory for a new reserved regions array and there is a previously
+ * allocated memory range [@new_area_start,@new_area_start+@new_area_size]
+ * waiting to be reserved, ensure the memory used by the new array does
+ * not overlap.
+ *
+ * RETURNS:
+ * 0 on success, -1 on failure.
+ */
+static int __init_memblock memblock_double_array(struct memblock_type *type,
+						phys_addr_t new_area_start,
+						phys_addr_t new_area_size)
+{
+	struct memblock_region *new_array, *old_array;
+	phys_addr_t old_alloc_size, new_alloc_size;
+	phys_addr_t old_size, new_size, addr;
+	int use_slab = slab_is_available();
+	int *in_slab;
+
+	/* We don't allow resizing until we know about the reserved regions
+	 * of memory that aren't suitable for allocation
+	 */
+	if (!memblock_can_resize)
+		return -1;
+
+	/* Calculate new doubled size */
+	old_size = type->max * sizeof(struct memblock_region);
+	new_size = old_size << 1;
+	/*
+	 * We need to allocated new one align to PAGE_SIZE,
+	 *   so we can free them completely later.
+	 */
+	old_alloc_size = PAGE_ALIGN(old_size);
+	new_alloc_size = PAGE_ALIGN(new_size);
+
+	/* Retrieve the slab flag */
+	if (type == &memblock.memory)
+		in_slab = &memblock_memory_in_slab;
+	else
+		in_slab = &memblock_reserved_in_slab;
+
+	/* Try to find some space for it.
+	 *
+	 * WARNING: We assume that either slab_is_available() and we use it or
+	 * we use MEMBLOCK for allocations. That means that this is unsafe to
+	 * use when bootmem is currently active (unless bootmem itself is
+	 * implemented on top of MEMBLOCK which isn't the case yet)
+	 *
+	 * This should however not be an issue for now, as we currently only
+	 * call into MEMBLOCK while it's still active, or much later when slab
+	 * is active for memory hotplug operations
+	 */
+	if (use_slab) {
+		new_array = kmalloc(new_size, GFP_KERNEL);
+		addr = new_array ? __pa(new_array) : 0;
+	} else {
+		/* only exclude range when trying to double reserved.regions */
+		if (type != &memblock.reserved)
+			new_area_start = new_area_size = 0;
+
+		addr = memblock_find_in_range(new_area_start + new_area_size,
+						memblock.current_limit,
+						new_alloc_size, PAGE_SIZE);
+		if (!addr && new_area_size)
+			addr = memblock_find_in_range(0,
+				min(new_area_start, memblock.current_limit),
+				new_alloc_size, PAGE_SIZE);
+
+		new_array = addr ? __va(addr) : NULL;
+	}
+	if (!addr) {
+		pr_err("memblock: Failed to double %s array from %ld to %ld entries !\n",
+		       memblock_type_name(type), type->max, type->max * 2);
+		return -1;
+	}
+
+	memblock_dbg("memblock: %s is doubled to %ld at [%#010llx-%#010llx]",
+			memblock_type_name(type), type->max * 2, (u64)addr,
+			(u64)addr + new_size - 1);
+
+	/*
+	 * Found space, we now need to move the array over before we add the
+	 * reserved region since it may be our reserved array itself that is
+	 * full.
+	 */
+	memcpy(new_array, type->regions, old_size);
+	memset(new_array + type->max, 0, old_size);
+	old_array = type->regions;
+	type->regions = new_array;
+	type->max <<= 1;
+
+	/* Free old array. We needn't free it if the array is the static one */
+	if (*in_slab)
+		kfree(old_array);
+	else if (old_array != memblock_memory_init_regions &&
+		 old_array != memblock_reserved_init_regions)
+		memblock_free(__pa(old_array), old_alloc_size);
+
+	/*
+	 * Reserve the new array if that comes from the memblock.  Otherwise, we
+	 * needn't do it
+	 */
+	if (!use_slab)
+		BUG_ON(memblock_reserve(addr, new_alloc_size));
+
+	/* Update slab flag */
+	*in_slab = use_slab;
+
+	return 0;
+}
+
+/**
+ * memblock_merge_regions - merge neighboring compatible regions
+ * @type: memblock type to scan
+ *
+ * Scan @type and merge neighboring compatible regions.
+ */
+static void __init_memblock memblock_merge_regions(struct memblock_type *type)
+{
+	int i = 0;
+
+	/* cnt never goes below 1 */
+	while (i < type->cnt - 1) {
+		struct memblock_region *this = &type->regions[i];
+		struct memblock_region *next = &type->regions[i + 1];
+
+		if (this->base + this->size != next->base ||
+		    memblock_get_region_node(this) !=
+		    memblock_get_region_node(next) ||
+		    this->flags != next->flags) {
+			BUG_ON(this->base + this->size > next->base);
+			i++;
+			continue;
+		}
+
+		this->size += next->size;
+		/* move forward from next + 1, index of which is i + 2 */
+		memmove(next, next + 1, (type->cnt - (i + 2)) * sizeof(*next));
+		type->cnt--;
+	}
+}
+
+/**
+ * memblock_insert_region - insert new memblock region
+ * @type:	memblock type to insert into
+ * @idx:	index for the insertion point
+ * @base:	base address of the new region
+ * @size:	size of the new region
+ * @nid:	node id of the new region
+ * @flags:	flags of the new region
+ *
+ * Insert new memblock region [@base,@base+@size) into @type at @idx.
+ * @type must already have extra room to accomodate the new region.
+ */
+static void __init_memblock memblock_insert_region(struct memblock_type *type,
+						   int idx, phys_addr_t base,
+						   phys_addr_t size,
+						   int nid, unsigned long flags)
+{
+	struct memblock_region *rgn = &type->regions[idx];
+
+	BUG_ON(type->cnt >= type->max);
+	memmove(rgn + 1, rgn, (type->cnt - idx) * sizeof(*rgn));
+	rgn->base = base;
+	rgn->size = size;
+	rgn->flags = flags;
+	memblock_set_region_node(rgn, nid);
+	type->cnt++;
+	type->total_size += size;
+}
+
+/**
+ * memblock_add_range - add new memblock region
+ * @type: memblock type to add new region into
+ * @base: base address of the new region
+ * @size: size of the new region
+ * @nid: nid of the new region
+ * @flags: flags of the new region
+ *
+ * Add new memblock region [@base,@base+@size) into @type.  The new region
+ * is allowed to overlap with existing ones - overlaps don't affect already
+ * existing regions.  @type is guaranteed to be minimal (all neighbouring
+ * compatible regions are merged) after the addition.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init_memblock memblock_add_range(struct memblock_type *type,
+				phys_addr_t base, phys_addr_t size,
+				int nid, unsigned long flags)
+{
+	bool insert = false;
+	phys_addr_t obase = base;
+	phys_addr_t end = base + memblock_cap_size(base, &size);
+	int i, nr_new;
+
+	if (!size)
+		return 0;
+
+	/* special case for empty array */
+	if (type->regions[0].size == 0) {
+		WARN_ON(type->cnt != 1 || type->total_size);
+		type->regions[0].base = base;
+		type->regions[0].size = size;
+		type->regions[0].flags = flags;
+		memblock_set_region_node(&type->regions[0], nid);
+		type->total_size = size;
+		return 0;
+	}
+repeat:
+	/*
+	 * The following is executed twice.  Once with %false @insert and
+	 * then with %true.  The first counts the number of regions needed
+	 * to accomodate the new area.  The second actually inserts them.
+	 */
+	base = obase;
+	nr_new = 0;
+
+	for (i = 0; i < type->cnt; i++) {
+		struct memblock_region *rgn = &type->regions[i];
+		phys_addr_t rbase = rgn->base;
+		phys_addr_t rend = rbase + rgn->size;
+
+		if (rbase >= end)
+			break;
+		if (rend <= base)
+			continue;
+		/*
+		 * @rgn overlaps.  If it separates the lower part of new
+		 * area, insert that portion.
+		 */
+		if (rbase > base) {
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+			WARN_ON(nid != memblock_get_region_node(rgn));
+#endif
+			WARN_ON(flags != rgn->flags);
+			nr_new++;
+			if (insert)
+				memblock_insert_region(type, i++, base,
+						       rbase - base, nid,
+						       flags);
+		}
+		/* area below @rend is dealt with, forget about it */
+		base = min(rend, end);
+	}
+
+	/* insert the remaining portion */
+	if (base < end) {
+		nr_new++;
+		if (insert)
+			memblock_insert_region(type, i, base, end - base,
+					       nid, flags);
+	}
+
+	/*
+	 * If this was the first round, resize array and repeat for actual
+	 * insertions; otherwise, merge and return.
+	 */
+	if (!insert) {
+		while (type->cnt + nr_new > type->max)
+			if (memblock_double_array(type, obase, size) < 0)
+				return -ENOMEM;
+		insert = true;
+		goto repeat;
+	} else {
+		memblock_merge_regions(type);
+		return 0;
+	}
+}
+
+int __init_memblock memblock_add_node(phys_addr_t base, phys_addr_t size,
+				       int nid)
+{
+	return memblock_add_range(&memblock.memory, base, size, nid, 0);
+}
+
+static int __init_memblock memblock_add_region(phys_addr_t base,
+						phys_addr_t size,
+						int nid,
+						unsigned long flags)
+{
+	struct memblock_type *type = &memblock.memory;
+
+	memblock_dbg("memblock_add: [%#016llx-%#016llx] flags %#02lx %pF\n",
+		     (unsigned long long)base,
+		     (unsigned long long)base + size - 1,
+		     flags, (void *)_RET_IP_);
+
+	return memblock_add_range(type, base, size, nid, flags);
+}
+
+int __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
+{
+	return memblock_add_region(base, size, MAX_NUMNODES, 0);
+}
+
+/**
+ * memblock_isolate_range - isolate given range into disjoint memblocks
+ * @type: memblock type to isolate range for
+ * @base: base of range to isolate
+ * @size: size of range to isolate
+ * @start_rgn: out parameter for the start of isolated region
+ * @end_rgn: out parameter for the end of isolated region
+ *
+ * Walk @type and ensure that regions don't cross the boundaries defined by
+ * [@base,@base+@size).  Crossing regions are split at the boundaries,
+ * which may create at most two more regions.  The index of the first
+ * region inside the range is returned in *@start_rgn and end in *@end_rgn.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+static int __init_memblock memblock_isolate_range(struct memblock_type *type,
+					phys_addr_t base, phys_addr_t size,
+					int *start_rgn, int *end_rgn)
+{
+	phys_addr_t end = base + memblock_cap_size(base, &size);
+	int i;
+
+	*start_rgn = *end_rgn = 0;
+
+	if (!size)
+		return 0;
+
+	/* we'll create at most two more regions */
+	while (type->cnt + 2 > type->max)
+		if (memblock_double_array(type, base, size) < 0)
+			return -ENOMEM;
+
+	for (i = 0; i < type->cnt; i++) {
+		struct memblock_region *rgn = &type->regions[i];
+		phys_addr_t rbase = rgn->base;
+		phys_addr_t rend = rbase + rgn->size;
+
+		if (rbase >= end)
+			break;
+		if (rend <= base)
+			continue;
+
+		if (rbase < base) {
+			/*
+			 * @rgn intersects from below.  Split and continue
+			 * to process the next region - the new top half.
+			 */
+			rgn->base = base;
+			rgn->size -= base - rbase;
+			type->total_size -= base - rbase;
+			memblock_insert_region(type, i, rbase, base - rbase,
+					       memblock_get_region_node(rgn),
+					       rgn->flags);
+		} else if (rend > end) {
+			/*
+			 * @rgn intersects from above.  Split and redo the
+			 * current region - the new bottom half.
+			 */
+			rgn->base = end;
+			rgn->size -= end - rbase;
+			type->total_size -= end - rbase;
+			memblock_insert_region(type, i--, rbase, end - rbase,
+					       memblock_get_region_node(rgn),
+					       rgn->flags);
+		} else {
+			/* @rgn is fully contained, record it */
+			if (!*end_rgn)
+				*start_rgn = i;
+			*end_rgn = i + 1;
+		}
+	}
+
+	return 0;
+}
+
+static int __init_memblock memblock_remove_range(struct memblock_type *type,
+					  phys_addr_t base, phys_addr_t size)
+{
+	int start_rgn, end_rgn;
+	int i, ret;
+
+	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
+	if (ret)
+		return ret;
+
+	for (i = end_rgn - 1; i >= start_rgn; i--)
+		memblock_remove_region(type, i);
+	return 0;
+}
+
+int __init_memblock memblock_remove(phys_addr_t base, phys_addr_t size)
+{
+	return memblock_remove_range(&memblock.memory, base, size);
+}
+
+
+int __init_memblock memblock_free(phys_addr_t base, phys_addr_t size)
+{
+	memblock_dbg("   memblock_free: [%#016llx-%#016llx] %pF\n",
+		     (unsigned long long)base,
+		     (unsigned long long)base + size - 1,
+		     (void *)_RET_IP_);
+
+	kmemleak_free_part(__va(base), size);
+	return memblock_remove_range(&memblock.reserved, base, size);
+}
+
+static int __init_memblock memblock_reserve_region(phys_addr_t base,
+						   phys_addr_t size,
+						   int nid,
+						   unsigned long flags)
+{
+	struct memblock_type *type = &memblock.reserved;
+
+	memblock_dbg("memblock_reserve: [%#016llx-%#016llx] flags %#02lx %pF\n",
+		     (unsigned long long)base,
+		     (unsigned long long)base + size - 1,
+		     flags, (void *)_RET_IP_);
+
+	return memblock_add_range(type, base, size, nid, flags);
+}
+
+int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
+{
+	return memblock_reserve_region(base, size, MAX_NUMNODES, 0);
+}
+
+/**
+ *
+ * This function isolates region [@base, @base + @size), and sets/clears flag
+ *
+ * Return 0 on success, -errno on failure.
+ */
+static int __init_memblock memblock_setclr_flag(phys_addr_t base,
+				phys_addr_t size, int set, int flag)
+{
+	struct memblock_type *type = &memblock.memory;
+	int i, ret, start_rgn, end_rgn;
+
+	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
+	if (ret)
+		return ret;
+
+	for (i = start_rgn; i < end_rgn; i++)
+		if (set)
+			memblock_set_region_flags(&type->regions[i], flag);
+		else
+			memblock_clear_region_flags(&type->regions[i], flag);
+
+	memblock_merge_regions(type);
+	return 0;
+}
+
+/**
+ * memblock_mark_hotplug - Mark hotpluggable memory with flag MEMBLOCK_HOTPLUG.
+ * @base: the base phys addr of the region
+ * @size: the size of the region
+ *
+ * Return 0 on success, -errno on failure.
+ */
+int __init_memblock memblock_mark_hotplug(phys_addr_t base, phys_addr_t size)
+{
+	return memblock_setclr_flag(base, size, 1, MEMBLOCK_HOTPLUG);
+}
+
+/**
+ * memblock_clear_hotplug - Clear flag MEMBLOCK_HOTPLUG for a specified region.
+ * @base: the base phys addr of the region
+ * @size: the size of the region
+ *
+ * Return 0 on success, -errno on failure.
+ */
+int __init_memblock memblock_clear_hotplug(phys_addr_t base, phys_addr_t size)
+{
+	return memblock_setclr_flag(base, size, 0, MEMBLOCK_HOTPLUG);
+}
+
+/**
+ * memblock_mark_mirror - Mark mirrored memory with flag MEMBLOCK_MIRROR.
+ * @base: the base phys addr of the region
+ * @size: the size of the region
+ *
+ * Return 0 on success, -errno on failure.
+ */
+int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
+{
+	system_has_some_mirror = true;
+
+	return memblock_setclr_flag(base, size, 1, MEMBLOCK_MIRROR);
+}
+
+
+/**
+ * __next_reserved_mem_region - next function for for_each_reserved_region()
+ * @idx: pointer to u64 loop variable
+ * @out_start: ptr to phys_addr_t for start address of the region, can be %NULL
+ * @out_end: ptr to phys_addr_t for end address of the region, can be %NULL
+ *
+ * Iterate over all reserved memory regions.
+ */
+void __init_memblock __next_reserved_mem_region(u64 *idx,
+					   phys_addr_t *out_start,
+					   phys_addr_t *out_end)
+{
+	struct memblock_type *type = &memblock.reserved;
+
+	if (*idx >= 0 && *idx < type->cnt) {
+		struct memblock_region *r = &type->regions[*idx];
+		phys_addr_t base = r->base;
+		phys_addr_t size = r->size;
+
+		if (out_start)
+			*out_start = base;
+		if (out_end)
+			*out_end = base + size - 1;
+
+		*idx += 1;
+		return;
+	}
+
+	/* signal end of iteration */
+	*idx = ULLONG_MAX;
+}
+
+/**
+ * __next__mem_range - next function for for_each_free_mem_range() etc.
+ * @idx: pointer to u64 loop variable
+ * @nid: node selector, %NUMA_NO_NODE for all nodes
+ * @flags: pick from blocks based on memory attributes
+ * @type_a: pointer to memblock_type from where the range is taken
+ * @type_b: pointer to memblock_type which excludes memory from being taken
+ * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ * @out_nid: ptr to int for nid of the range, can be %NULL
+ *
+ * Find the first area from *@idx which matches @nid, fill the out
+ * parameters, and update *@idx for the next iteration.  The lower 32bit of
+ * *@idx contains index into type_a and the upper 32bit indexes the
+ * areas before each region in type_b.	For example, if type_b regions
+ * look like the following,
+ *
+ *	0:[0-16), 1:[32-48), 2:[128-130)
+ *
+ * The upper 32bit indexes the following regions.
+ *
+ *	0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
+ *
+ * As both region arrays are sorted, the function advances the two indices
+ * in lockstep and returns each intersection.
+ */
+void __init_memblock __next_mem_range(u64 *idx, int nid, ulong flags,
+				      struct memblock_type *type_a,
+				      struct memblock_type *type_b,
+				      phys_addr_t *out_start,
+				      phys_addr_t *out_end, int *out_nid)
+{
+	int idx_a = *idx & 0xffffffff;
+	int idx_b = *idx >> 32;
+
+	if (WARN_ONCE(nid == MAX_NUMNODES,
+	"Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
+		nid = NUMA_NO_NODE;
+
+	for (; idx_a < type_a->cnt; idx_a++) {
+		struct memblock_region *m = &type_a->regions[idx_a];
+
+		phys_addr_t m_start = m->base;
+		phys_addr_t m_end = m->base + m->size;
+		int	    m_nid = memblock_get_region_node(m);
+
+		/* only memory regions are associated with nodes, check it */
+		if (nid != NUMA_NO_NODE && nid != m_nid)
+			continue;
+
+		/* skip hotpluggable memory regions if needed */
+		if (movable_node_is_enabled() && memblock_is_hotpluggable(m))
+			continue;
+
+		/* if we want mirror memory skip non-mirror memory regions */
+		if ((flags & MEMBLOCK_MIRROR) && !memblock_is_mirror(m))
+			continue;
+
+		if (!type_b) {
+			if (out_start)
+				*out_start = m_start;
+			if (out_end)
+				*out_end = m_end;
+			if (out_nid)
+				*out_nid = m_nid;
+			idx_a++;
+			*idx = (u32)idx_a | (u64)idx_b << 32;
+			return;
+		}
+
+		/* scan areas before each reservation */
+		for (; idx_b < type_b->cnt + 1; idx_b++) {
+			struct memblock_region *r;
+			phys_addr_t r_start;
+			phys_addr_t r_end;
+
+			r = &type_b->regions[idx_b];
+			r_start = idx_b ? r[-1].base + r[-1].size : 0;
+			r_end = idx_b < type_b->cnt ?
+				r->base : ULLONG_MAX;
+
+			/*
+			 * if idx_b advanced past idx_a,
+			 * break out to advance idx_a
+			 */
+			if (r_start >= m_end)
+				break;
+			/* if the two regions intersect, we're done */
+			if (m_start < r_end) {
+				if (out_start)
+					*out_start =
+						max(m_start, r_start);
+				if (out_end)
+					*out_end = min(m_end, r_end);
+				if (out_nid)
+					*out_nid = m_nid;
+				/*
+				 * The region which ends first is
+				 * advanced for the next iteration.
+				 */
+				if (m_end <= r_end)
+					idx_a++;
+				else
+					idx_b++;
+				*idx = (u32)idx_a | (u64)idx_b << 32;
+				return;
+			}
+		}
+	}
+
+	/* signal end of iteration */
+	*idx = ULLONG_MAX;
+}
+
+/**
+ * __next_mem_range_rev - generic next function for for_each_*_range_rev()
+ *
+ * Finds the next range from type_a which is not marked as unsuitable
+ * in type_b.
+ *
+ * @idx: pointer to u64 loop variable
+ * @nid: node selector, %NUMA_NO_NODE for all nodes
+ * @flags: pick from blocks based on memory attributes
+ * @type_a: pointer to memblock_type from where the range is taken
+ * @type_b: pointer to memblock_type which excludes memory from being taken
+ * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ * @out_nid: ptr to int for nid of the range, can be %NULL
+ *
+ * Reverse of __next_mem_range().
+ */
+void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags,
+					  struct memblock_type *type_a,
+					  struct memblock_type *type_b,
+					  phys_addr_t *out_start,
+					  phys_addr_t *out_end, int *out_nid)
+{
+	int idx_a = *idx & 0xffffffff;
+	int idx_b = *idx >> 32;
+
+	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
+		nid = NUMA_NO_NODE;
+
+	if (*idx == (u64)ULLONG_MAX) {
+		idx_a = type_a->cnt - 1;
+		idx_b = type_b->cnt;
+	}
+
+	for (; idx_a >= 0; idx_a--) {
+		struct memblock_region *m = &type_a->regions[idx_a];
+
+		phys_addr_t m_start = m->base;
+		phys_addr_t m_end = m->base + m->size;
+		int m_nid = memblock_get_region_node(m);
+
+		/* only memory regions are associated with nodes, check it */
+		if (nid != NUMA_NO_NODE && nid != m_nid)
+			continue;
+
+		/* skip hotpluggable memory regions if needed */
+		if (movable_node_is_enabled() && memblock_is_hotpluggable(m))
+			continue;
+
+		/* if we want mirror memory skip non-mirror memory regions */
+		if ((flags & MEMBLOCK_MIRROR) && !memblock_is_mirror(m))
+			continue;
+
+		if (!type_b) {
+			if (out_start)
+				*out_start = m_start;
+			if (out_end)
+				*out_end = m_end;
+			if (out_nid)
+				*out_nid = m_nid;
+			idx_a++;
+			*idx = (u32)idx_a | (u64)idx_b << 32;
+			return;
+		}
+
+		/* scan areas before each reservation */
+		for (; idx_b >= 0; idx_b--) {
+			struct memblock_region *r;
+			phys_addr_t r_start;
+			phys_addr_t r_end;
+
+			r = &type_b->regions[idx_b];
+			r_start = idx_b ? r[-1].base + r[-1].size : 0;
+			r_end = idx_b < type_b->cnt ?
+				r->base : ULLONG_MAX;
+			/*
+			 * if idx_b advanced past idx_a,
+			 * break out to advance idx_a
+			 */
+
+			if (r_end <= m_start)
+				break;
+			/* if the two regions intersect, we're done */
+			if (m_end > r_start) {
+				if (out_start)
+					*out_start = max(m_start, r_start);
+				if (out_end)
+					*out_end = min(m_end, r_end);
+				if (out_nid)
+					*out_nid = m_nid;
+				if (m_start >= r_start)
+					idx_a--;
+				else
+					idx_b--;
+				*idx = (u32)idx_a | (u64)idx_b << 32;
+				return;
+			}
+		}
+	}
+	/* signal end of iteration */
+	*idx = ULLONG_MAX;
+}
+
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+/*
+ * Common iterator interface used to define for_each_mem_range().
+ */
+void __init_memblock __next_mem_pfn_range(int *idx, int nid,
+				unsigned long *out_start_pfn,
+				unsigned long *out_end_pfn, int *out_nid)
+{
+	struct memblock_type *type = &memblock.memory;
+	struct memblock_region *r;
+
+	while (++*idx < type->cnt) {
+		r = &type->regions[*idx];
+
+		if (PFN_UP(r->base) >= PFN_DOWN(r->base + r->size))
+			continue;
+		if (nid == MAX_NUMNODES || nid == r->nid)
+			break;
+	}
+	if (*idx >= type->cnt) {
+		*idx = -1;
+		return;
+	}
+
+	if (out_start_pfn)
+		*out_start_pfn = PFN_UP(r->base);
+	if (out_end_pfn)
+		*out_end_pfn = PFN_DOWN(r->base + r->size);
+	if (out_nid)
+		*out_nid = r->nid;
+}
+
+/**
+ * memblock_set_node - set node ID on memblock regions
+ * @base: base of area to set node ID for
+ * @size: size of area to set node ID for
+ * @type: memblock type to set node ID for
+ * @nid: node ID to set
+ *
+ * Set the nid of memblock @type regions in [@base,@base+@size) to @nid.
+ * Regions which cross the area boundaries are split as necessary.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,
+				      struct memblock_type *type, int nid)
+{
+	int start_rgn, end_rgn;
+	int i, ret;
+
+	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
+	if (ret)
+		return ret;
+
+	for (i = start_rgn; i < end_rgn; i++)
+		memblock_set_region_node(&type->regions[i], nid);
+
+	memblock_merge_regions(type);
+	return 0;
+}
+#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+
+static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
+					phys_addr_t align, phys_addr_t start,
+					phys_addr_t end, int nid, ulong flags)
+{
+	phys_addr_t found;
+
+	if (!align)
+		align = SMP_CACHE_BYTES;
+
+	found = memblock_find_in_range_node(size, align, start, end, nid,
+					    flags);
+	if (found && !memblock_reserve(found, size)) {
+		/*
+		 * The min_count is set to 0 so that memblock allocations are
+		 * never reported as leaks.
+		 */
+		kmemleak_alloc(__va(found), size, 0, 0);
+		return found;
+	}
+	return 0;
+}
+
+phys_addr_t __init memblock_alloc_range(phys_addr_t size, phys_addr_t align,
+					phys_addr_t start, phys_addr_t end,
+					ulong flags)
+{
+	return memblock_alloc_range_nid(size, align, start, end, NUMA_NO_NODE,
+					flags);
+}
+
+static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size,
+					phys_addr_t align, phys_addr_t max_addr,
+					int nid, ulong flags)
+{
+	return memblock_alloc_range_nid(size, align, 0, max_addr, nid, flags);
+}
+
+phys_addr_t __init memblock_alloc_nid(phys_addr_t size, phys_addr_t align, int nid)
+{
+	ulong flags = choose_memblock_flags();
+	phys_addr_t ret;
+
+again:
+	ret = memblock_alloc_base_nid(size, align, MEMBLOCK_ALLOC_ACCESSIBLE,
+				      nid, flags);
+
+	if (!ret && (flags & MEMBLOCK_MIRROR)) {
+		flags &= ~MEMBLOCK_MIRROR;
+		goto again;
+	}
+	return ret;
+}
+
+phys_addr_t __init __memblock_alloc_base(phys_addr_t size, phys_addr_t align, phys_addr_t max_addr)
+{
+	return memblock_alloc_base_nid(size, align, max_addr, NUMA_NO_NODE,
+				       MEMBLOCK_NONE);
+}
+
+phys_addr_t __init memblock_alloc_base(phys_addr_t size, phys_addr_t align, phys_addr_t max_addr)
+{
+	phys_addr_t alloc;
+
+	alloc = __memblock_alloc_base(size, align, max_addr);
+
+	if (alloc == 0)
+		panic("ERROR: Failed to allocate 0x%llx bytes below 0x%llx.\n",
+		      (unsigned long long) size, (unsigned long long) max_addr);
+
+	return alloc;
+}
+
+phys_addr_t __init memblock_alloc(phys_addr_t size, phys_addr_t align)
+{
+	return memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE);
+}
+
+phys_addr_t __init memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid)
+{
+	phys_addr_t res = memblock_alloc_nid(size, align, nid);
+
+	if (res)
+		return res;
+	return memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE);
+}
+
+/**
+ * memblock_virt_alloc_internal - allocate boot memory block
+ * @size: size of memory block to be allocated in bytes
+ * @align: alignment of the region and block's size
+ * @min_addr: the lower bound of the memory region to allocate (phys address)
+ * @max_addr: the upper bound of the memory region to allocate (phys address)
+ * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ *
+ * The @min_addr limit is dropped if it can not be satisfied and the allocation
+ * will fall back to memory below @min_addr. Also, allocation may fall back
+ * to any node in the system if the specified node can not
+ * hold the requested memory.
+ *
+ * The allocation is performed from memory region limited by
+ * memblock.current_limit if @max_addr == %BOOTMEM_ALLOC_ACCESSIBLE.
+ *
+ * The memory block is aligned on SMP_CACHE_BYTES if @align == 0.
+ *
+ * The phys address of allocated boot memory block is converted to virtual and
+ * allocated memory is reset to 0.
+ *
+ * In addition, function sets the min_count to 0 using kmemleak_alloc for
+ * allocated boot memory block, so that it is never reported as leaks.
+ *
+ * RETURNS:
+ * Virtual address of allocated memory block on success, NULL on failure.
+ */
+static void * __init memblock_virt_alloc_internal(
+				phys_addr_t size, phys_addr_t align,
+				phys_addr_t min_addr, phys_addr_t max_addr,
+				int nid)
+{
+	phys_addr_t alloc;
+	void *ptr;
+	ulong flags = choose_memblock_flags();
+
+	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
+		nid = NUMA_NO_NODE;
+
+	/*
+	 * Detect any accidental use of these APIs after slab is ready, as at
+	 * this moment memblock may be deinitialized already and its
+	 * internal data may be destroyed (after execution of free_all_bootmem)
+	 */
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, nid);
+
+	if (!align)
+		align = SMP_CACHE_BYTES;
+
+	if (max_addr > memblock.current_limit)
+		max_addr = memblock.current_limit;
+
+again:
+	alloc = memblock_find_in_range_node(size, align, min_addr, max_addr,
+					    nid, flags);
+	if (alloc)
+		goto done;
+
+	if (nid != NUMA_NO_NODE) {
+		alloc = memblock_find_in_range_node(size, align, min_addr,
+						    max_addr, NUMA_NO_NODE,
+						    flags);
+		if (alloc)
+			goto done;
+	}
+
+	if (min_addr) {
+		min_addr = 0;
+		goto again;
+	}
+
+	if (flags & MEMBLOCK_MIRROR) {
+		flags &= ~MEMBLOCK_MIRROR;
+		pr_warn("Could not allocate %pap bytes of mirrored memory\n",
+			&size);
+		goto again;
+	}
+
+	return NULL;
+done:
+	memblock_reserve(alloc, size);
+	ptr = phys_to_virt(alloc);
+	memset(ptr, 0, size);
+
+	/*
+	 * The min_count is set to 0 so that bootmem allocated blocks
+	 * are never reported as leaks. This is because many of these blocks
+	 * are only referred via the physical address which is not
+	 * looked up by kmemleak.
+	 */
+	kmemleak_alloc(ptr, size, 0, 0);
+
+	return ptr;
+}
+
+/**
+ * memblock_virt_alloc_try_nid_nopanic - allocate boot memory block
+ * @size: size of memory block to be allocated in bytes
+ * @align: alignment of the region and block's size
+ * @min_addr: the lower bound of the memory region from where the allocation
+ *	  is preferred (phys address)
+ * @max_addr: the upper bound of the memory region from where the allocation
+ *	      is preferred (phys address), or %BOOTMEM_ALLOC_ACCESSIBLE to
+ *	      allocate only from memory limited by memblock.current_limit value
+ * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ *
+ * Public version of _memblock_virt_alloc_try_nid_nopanic() which provides
+ * additional debug information (including caller info), if enabled.
+ *
+ * RETURNS:
+ * Virtual address of allocated memory block on success, NULL on failure.
+ */
+void * __init memblock_virt_alloc_try_nid_nopanic(
+				phys_addr_t size, phys_addr_t align,
+				phys_addr_t min_addr, phys_addr_t max_addr,
+				int nid)
+{
+	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=0x%llx max_addr=0x%llx %pF\n",
+		     __func__, (u64)size, (u64)align, nid, (u64)min_addr,
+		     (u64)max_addr, (void *)_RET_IP_);
+	return memblock_virt_alloc_internal(size, align, min_addr,
+					     max_addr, nid);
+}
+
+/**
+ * memblock_virt_alloc_try_nid - allocate boot memory block with panicking
+ * @size: size of memory block to be allocated in bytes
+ * @align: alignment of the region and block's size
+ * @min_addr: the lower bound of the memory region from where the allocation
+ *	  is preferred (phys address)
+ * @max_addr: the upper bound of the memory region from where the allocation
+ *	      is preferred (phys address), or %BOOTMEM_ALLOC_ACCESSIBLE to
+ *	      allocate only from memory limited by memblock.current_limit value
+ * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ *
+ * Public panicking version of _memblock_virt_alloc_try_nid_nopanic()
+ * which provides debug information (including caller info), if enabled,
+ * and panics if the request can not be satisfied.
+ *
+ * RETURNS:
+ * Virtual address of allocated memory block on success, NULL on failure.
+ */
+void * __init memblock_virt_alloc_try_nid(
+			phys_addr_t size, phys_addr_t align,
+			phys_addr_t min_addr, phys_addr_t max_addr,
+			int nid)
+{
+	void *ptr;
+
+	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=0x%llx max_addr=0x%llx %pF\n",
+		     __func__, (u64)size, (u64)align, nid, (u64)min_addr,
+		     (u64)max_addr, (void *)_RET_IP_);
+	ptr = memblock_virt_alloc_internal(size, align,
+					   min_addr, max_addr, nid);
+	if (ptr)
+		return ptr;
+
+	panic("%s: Failed to allocate %llu bytes align=0x%llx nid=%d from=0x%llx max_addr=0x%llx\n",
+	      __func__, (u64)size, (u64)align, nid, (u64)min_addr,
+	      (u64)max_addr);
+	return NULL;
+}
+
+/**
+ * __memblock_free_early - free boot memory block
+ * @base: phys starting address of the  boot memory block
+ * @size: size of the boot memory block in bytes
+ *
+ * Free boot memory block previously allocated by memblock_virt_alloc_xx() API.
+ * The freeing memory will not be released to the buddy allocator.
+ */
+void __init __memblock_free_early(phys_addr_t base, phys_addr_t size)
+{
+	memblock_dbg("%s: [%#016llx-%#016llx] %pF\n",
+		     __func__, (u64)base, (u64)base + size - 1,
+		     (void *)_RET_IP_);
+	kmemleak_free_part(__va(base), size);
+	memblock_remove_range(&memblock.reserved, base, size);
+}
+
+/*
+ * __memblock_free_late - free bootmem block pages directly to buddy allocator
+ * @addr: phys starting address of the  boot memory block
+ * @size: size of the boot memory block in bytes
+ *
+ * This is only useful when the bootmem allocator has already been torn
+ * down, but we are still initializing the system.  Pages are released directly
+ * to the buddy allocator, no bootmem metadata is updated because it is gone.
+ */
+void __init __memblock_free_late(phys_addr_t base, phys_addr_t size)
+{
+	u64 cursor, end;
+
+	memblock_dbg("%s: [%#016llx-%#016llx] %pF\n",
+		     __func__, (u64)base, (u64)base + size - 1,
+		     (void *)_RET_IP_);
+	kmemleak_free_part(__va(base), size);
+	cursor = PFN_UP(base);
+	end = PFN_DOWN(base + size);
+
+	for (; cursor < end; cursor++) {
+		__free_pages_bootmem(pfn_to_page(cursor), cursor, 0);
+		totalram_pages++;
+	}
+}
+
+/*
+ * Remaining API functions
+ */
+
+phys_addr_t __init memblock_phys_mem_size(void)
+{
+	return memblock.memory.total_size;
+}
+
+phys_addr_t __init memblock_mem_size(unsigned long limit_pfn)
+{
+	unsigned long pages = 0;
+	struct memblock_region *r;
+	unsigned long start_pfn, end_pfn;
+
+	for_each_memblock(memory, r) {
+		start_pfn = memblock_region_memory_base_pfn(r);
+		end_pfn = memblock_region_memory_end_pfn(r);
+		start_pfn = min_t(unsigned long, start_pfn, limit_pfn);
+		end_pfn = min_t(unsigned long, end_pfn, limit_pfn);
+		pages += end_pfn - start_pfn;
+	}
+
+	return PFN_PHYS(pages);
+}
+
+/* lowest address */
+phys_addr_t __init_memblock memblock_start_of_DRAM(void)
+{
+	return memblock.memory.regions[0].base;
+}
+
+phys_addr_t __init_memblock memblock_end_of_DRAM(void)
+{
+	int idx = memblock.memory.cnt - 1;
+
+	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
+}
+
+void __init memblock_enforce_memory_limit(phys_addr_t limit)
+{
+	phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
+	struct memblock_region *r;
+
+	if (!limit)
+		return;
+
+	/* find out max address */
+	for_each_memblock(memory, r) {
+		if (limit <= r->size) {
+			max_addr = r->base + limit;
+			break;
+		}
+		limit -= r->size;
+	}
+
+	/* truncate both memory and reserved regions */
+	memblock_remove_range(&memblock.memory, max_addr,
+			      (phys_addr_t)ULLONG_MAX);
+	memblock_remove_range(&memblock.reserved, max_addr,
+			      (phys_addr_t)ULLONG_MAX);
+}
+
+static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
+{
+	unsigned int left = 0, right = type->cnt;
+
+	do {
+		unsigned int mid = (right + left) / 2;
+
+		if (addr < type->regions[mid].base)
+			right = mid;
+		else if (addr >= (type->regions[mid].base +
+				  type->regions[mid].size))
+			left = mid + 1;
+		else
+			return mid;
+	} while (left < right);
+	return -1;
+}
+
+int __init memblock_is_reserved(phys_addr_t addr)
+{
+	return memblock_search(&memblock.reserved, addr) != -1;
+}
+
+int __init_memblock memblock_is_memory(phys_addr_t addr)
+{
+	return memblock_search(&memblock.memory, addr) != -1;
+}
+
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+int __init_memblock memblock_search_pfn_nid(unsigned long pfn,
+			 unsigned long *start_pfn, unsigned long *end_pfn)
+{
+	struct memblock_type *type = &memblock.memory;
+	int mid = memblock_search(type, PFN_PHYS(pfn));
+
+	if (mid == -1)
+		return -1;
+
+	*start_pfn = PFN_DOWN(type->regions[mid].base);
+	*end_pfn = PFN_DOWN(type->regions[mid].base + type->regions[mid].size);
+
+	return type->regions[mid].nid;
+}
+#endif
+
+/**
+ * memblock_is_region_memory - check if a region is a subset of memory
+ * @base: base of region to check
+ * @size: size of region to check
+ *
+ * Check if the region [@base, @base+@size) is a subset of a memory block.
+ *
+ * RETURNS:
+ * 0 if false, non-zero if true
+ */
+int __init_memblock memblock_is_region_memory(phys_addr_t base, phys_addr_t size)
+{
+	int idx = memblock_search(&memblock.memory, base);
+	phys_addr_t end = base + memblock_cap_size(base, &size);
+
+	if (idx == -1)
+		return 0;
+	return memblock.memory.regions[idx].base <= base &&
+		(memblock.memory.regions[idx].base +
+		 memblock.memory.regions[idx].size) >= end;
+}
+
+/**
+ * memblock_is_region_reserved - check if a region intersects reserved memory
+ * @base: base of region to check
+ * @size: size of region to check
+ *
+ * Check if the region [@base, @base+@size) intersects a reserved memory block.
+ *
+ * RETURNS:
+ * True if they intersect, false if not.
+ */
+bool __init_memblock memblock_is_region_reserved(phys_addr_t base, phys_addr_t size)
+{
+	memblock_cap_size(base, &size);
+	return memblock_overlaps_region(&memblock.reserved, base, size);
+}
+
+void __init_memblock memblock_trim_memory(phys_addr_t align)
+{
+	phys_addr_t start, end, orig_start, orig_end;
+	struct memblock_region *r;
+
+	for_each_memblock(memory, r) {
+		orig_start = r->base;
+		orig_end = r->base + r->size;
+		start = round_up(orig_start, align);
+		end = round_down(orig_end, align);
+
+		if (start == orig_start && end == orig_end)
+			continue;
+
+		if (start < end) {
+			r->base = start;
+			r->size = end - start;
+		} else {
+			memblock_remove_region(&memblock.memory,
+					       r - memblock.memory.regions);
+			r--;
+		}
+	}
+}
+
+void __init_memblock memblock_set_current_limit(phys_addr_t limit)
+{
+	memblock.current_limit = limit;
+}
+
+phys_addr_t __init_memblock memblock_get_current_limit(void)
+{
+	return memblock.current_limit;
+}
+
+static void __init_memblock memblock_dump(struct memblock_type *type, char *name)
+{
+	unsigned long long base, size;
+	unsigned long flags;
+	int i;
+
+	pr_info(" %s.cnt  = 0x%lx\n", name, type->cnt);
+
+	for (i = 0; i < type->cnt; i++) {
+		struct memblock_region *rgn = &type->regions[i];
+		char nid_buf[32] = "";
+
+		base = rgn->base;
+		size = rgn->size;
+		flags = rgn->flags;
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+		if (memblock_get_region_node(rgn) != MAX_NUMNODES)
+			snprintf(nid_buf, sizeof(nid_buf), " on node %d",
+				 memblock_get_region_node(rgn));
+#endif
+		pr_info(" %s[%#x]\t[%#016llx-%#016llx], %#llx bytes%s flags: %#lx\n",
+			name, i, base, base + size - 1, size, nid_buf, flags);
+	}
+}
+
+extern unsigned long __init_memblock
+memblock_reserved_memory_within(phys_addr_t start_addr, phys_addr_t end_addr)
+{
+	struct memblock_type *type = &memblock.reserved;
+	unsigned long size = 0;
+	int idx;
+
+	for (idx = 0; idx < type->cnt; idx++) {
+		struct memblock_region *rgn = &type->regions[idx];
+		phys_addr_t start, end;
+
+		if (rgn->base + rgn->size < start_addr)
+			continue;
+		if (rgn->base > end_addr)
+			continue;
+
+		start = rgn->base;
+		end = start + rgn->size;
+		size += end - start;
+	}
+
+	return size;
+}
+
+void __init_memblock __memblock_dump_all(void)
+{
+	pr_info("MEMBLOCK configuration:\n");
+	pr_info(" memory size = %#llx reserved size = %#llx\n",
+		(unsigned long long)memblock.memory.total_size,
+		(unsigned long long)memblock.reserved.total_size);
+
+	memblock_dump(&memblock.memory, "memory");
+	memblock_dump(&memblock.reserved, "reserved");
+}
+
+void __init memblock_allow_resize(void)
+{
+	memblock_can_resize = 1;
+}
+
+static int __init early_memblock(char *p)
+{
+	if (p && strstr(p, "debug"))
+		memblock_debug = 1;
+	return 0;
+}
+early_param("memblock", early_memblock);
+
+#if defined(CONFIG_DEBUG_FS) && !defined(CONFIG_ARCH_DISCARD_MEMBLOCK)
+
+static int memblock_debug_show(struct seq_file *m, void *private)
+{
+	struct memblock_type *type = m->private;
+	struct memblock_region *reg;
+	int i;
+
+	for (i = 0; i < type->cnt; i++) {
+		reg = &type->regions[i];
+		seq_printf(m, "%4d: ", i);
+		if (sizeof(phys_addr_t) == 4)
+			seq_printf(m, "0x%08lx..0x%08lx\n",
+				   (unsigned long)reg->base,
+				   (unsigned long)(reg->base + reg->size - 1));
+		else
+			seq_printf(m, "0x%016llx..0x%016llx\n",
+				   (unsigned long long)reg->base,
+				   (unsigned long long)(reg->base + reg->size - 1));
+
+	}
+	return 0;
+}
+
+static int memblock_debug_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, memblock_debug_show, inode->i_private);
+}
+
+static const struct file_operations memblock_debug_fops = {
+	.open = memblock_debug_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int __init memblock_init_debugfs(void)
+{
+	struct dentry *root = debugfs_create_dir("memblock", NULL);
+	if (!root)
+		return -ENXIO;
+	debugfs_create_file("memory", S_IRUGO, root, &memblock.memory, &memblock_debug_fops);
+	debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved, &memblock_debug_fops);
+#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+	debugfs_create_file("physmem", S_IRUGO, root, &memblock.physmem, &memblock_debug_fops);
+#endif
+
+	return 0;
+}
+__initcall(memblock_init_debugfs);
+
+#endif /* CONFIG_DEBUG_FS */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
new file mode 100644
index 0000000..e25b93a
--- /dev/null
+++ b/mm/memcontrol.c
@@ -0,0 +1,5894 @@
+/* memcontrol.c - Memory Controller
+ *
+ * Copyright IBM Corporation, 2007
+ * Author Balbir Singh <balbir@linux.vnet.ibm.com>
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ * Memory thresholds
+ * Copyright (C) 2009 Nokia Corporation
+ * Author: Kirill A. Shutemov
+ *
+ * Kernel Memory Controller
+ * Copyright (C) 2012 Parallels Inc. and Google Inc.
+ * Authors: Glauber Costa and Suleiman Souhlal
+ *
+ * Native page reclaim
+ * Charge lifetime sanitation
+ * Lockless page tracking & accounting
+ * Unified hierarchy configuration model
+ * Copyright (C) 2015 Red Hat, Inc., Johannes Weiner
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/page_counter.h>
+#include <linux/memcontrol.h>
+#include <linux/cgroup.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/pagemap.h>
+#include <linux/smp.h>
+#include <linux/page-flags.h>
+#include <linux/backing-dev.h>
+#include <linux/bit_spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/limits.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/rbtree.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/spinlock.h>
+#include <linux/eventfd.h>
+#include <linux/poll.h>
+#include <linux/sort.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/vmpressure.h>
+#include <linux/mm_inline.h>
+#include <linux/swap_cgroup.h>
+#include <linux/cpu.h>
+#include <linux/oom.h>
+#include <linux/lockdep.h>
+#include <linux/file.h>
+#include <linux/tracehook.h>
+#include "internal.h"
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/tcp_memcontrol.h>
+#include "slab.h"
+
+#include <asm/uaccess.h>
+
+#include <trace/events/vmscan.h>
+
+struct cgroup_subsys memory_cgrp_subsys __read_mostly;
+EXPORT_SYMBOL(memory_cgrp_subsys);
+
+#define MEM_CGROUP_RECLAIM_RETRIES	5
+static struct mem_cgroup *root_mem_cgroup __read_mostly;
+struct cgroup_subsys_state *mem_cgroup_root_css __read_mostly;
+
+/* Whether the swap controller is active */
+#ifdef CONFIG_MEMCG_SWAP
+int do_swap_account __read_mostly;
+#else
+#define do_swap_account		0
+#endif
+
+static const char * const mem_cgroup_stat_names[] = {
+	"cache",
+	"rss",
+	"rss_huge",
+	"mapped_file",
+	"dirty",
+	"writeback",
+	"swap",
+};
+
+static const char * const mem_cgroup_events_names[] = {
+	"pgpgin",
+	"pgpgout",
+	"pgfault",
+	"pgmajfault",
+};
+
+static const char * const mem_cgroup_lru_names[] = {
+	"inactive_anon",
+	"active_anon",
+	"inactive_file",
+	"active_file",
+	"unevictable",
+};
+
+#define THRESHOLDS_EVENTS_TARGET 128
+#define SOFTLIMIT_EVENTS_TARGET 1024
+#define NUMAINFO_EVENTS_TARGET	1024
+
+/*
+ * Cgroups above their limits are maintained in a RB-Tree, independent of
+ * their hierarchy representation
+ */
+
+struct mem_cgroup_tree_per_zone {
+	struct rb_root rb_root;
+	spinlock_t lock;
+};
+
+struct mem_cgroup_tree_per_node {
+	struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
+};
+
+struct mem_cgroup_tree {
+	struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
+};
+
+static struct mem_cgroup_tree soft_limit_tree __read_mostly;
+
+/* for OOM */
+struct mem_cgroup_eventfd_list {
+	struct list_head list;
+	struct eventfd_ctx *eventfd;
+};
+
+/*
+ * cgroup_event represents events which userspace want to receive.
+ */
+struct mem_cgroup_event {
+	/*
+	 * memcg which the event belongs to.
+	 */
+	struct mem_cgroup *memcg;
+	/*
+	 * eventfd to signal userspace about the event.
+	 */
+	struct eventfd_ctx *eventfd;
+	/*
+	 * Each of these stored in a list by the cgroup.
+	 */
+	struct list_head list;
+	/*
+	 * register_event() callback will be used to add new userspace
+	 * waiter for changes related to this event.  Use eventfd_signal()
+	 * on eventfd to send notification to userspace.
+	 */
+	int (*register_event)(struct mem_cgroup *memcg,
+			      struct eventfd_ctx *eventfd, const char *args);
+	/*
+	 * unregister_event() callback will be called when userspace closes
+	 * the eventfd or on cgroup removing.  This callback must be set,
+	 * if you want provide notification functionality.
+	 */
+	void (*unregister_event)(struct mem_cgroup *memcg,
+				 struct eventfd_ctx *eventfd);
+	/*
+	 * All fields below needed to unregister event when
+	 * userspace closes eventfd.
+	 */
+	poll_table pt;
+	wait_queue_head_t *wqh;
+	wait_queue_t wait;
+	struct work_struct remove;
+};
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg);
+static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
+
+/* Stuffs for move charges at task migration. */
+/*
+ * Types of charges to be moved.
+ */
+#define MOVE_ANON	0x1U
+#define MOVE_FILE	0x2U
+#define MOVE_MASK	(MOVE_ANON | MOVE_FILE)
+
+/* "mc" and its members are protected by cgroup_mutex */
+static struct move_charge_struct {
+	spinlock_t	  lock; /* for from, to */
+	struct mm_struct  *mm;
+	struct mem_cgroup *from;
+	struct mem_cgroup *to;
+	unsigned long flags;
+	unsigned long precharge;
+	unsigned long moved_charge;
+	unsigned long moved_swap;
+	struct task_struct *moving_task;	/* a task moving charges */
+	wait_queue_head_t waitq;		/* a waitq for other context */
+} mc = {
+	.lock = __SPIN_LOCK_UNLOCKED(mc.lock),
+	.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
+};
+
+/*
+ * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
+ * limit reclaim to prevent infinite loops, if they ever occur.
+ */
+#define	MEM_CGROUP_MAX_RECLAIM_LOOPS		100
+#define	MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS	2
+
+enum charge_type {
+	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
+	MEM_CGROUP_CHARGE_TYPE_ANON,
+	MEM_CGROUP_CHARGE_TYPE_SWAPOUT,	/* for accounting swapcache */
+	MEM_CGROUP_CHARGE_TYPE_DROP,	/* a page was unused swap cache */
+	NR_CHARGE_TYPE,
+};
+
+/* for encoding cft->private value on file */
+enum res_type {
+	_MEM,
+	_MEMSWAP,
+	_OOM_TYPE,
+	_KMEM,
+};
+
+#define MEMFILE_PRIVATE(x, val)	((x) << 16 | (val))
+#define MEMFILE_TYPE(val)	((val) >> 16 & 0xffff)
+#define MEMFILE_ATTR(val)	((val) & 0xffff)
+/* Used for OOM nofiier */
+#define OOM_CONTROL		(0)
+
+/*
+ * The memcg_create_mutex will be held whenever a new cgroup is created.
+ * As a consequence, any change that needs to protect against new child cgroups
+ * appearing has to hold it as well.
+ */
+static DEFINE_MUTEX(memcg_create_mutex);
+
+/* Some nice accessors for the vmpressure. */
+struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
+{
+	if (!memcg)
+		memcg = root_mem_cgroup;
+	return &memcg->vmpressure;
+}
+
+struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr)
+{
+	return &container_of(vmpr, struct mem_cgroup, vmpressure)->css;
+}
+
+static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
+{
+	return (memcg == root_mem_cgroup);
+}
+
+/*
+ * We restrict the id in the range of [1, 65535], so it can fit into
+ * an unsigned short.
+ */
+#define MEM_CGROUP_ID_MAX	USHRT_MAX
+
+static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
+{
+	return memcg->id.id;
+}
+
+/* Writing them here to avoid exposing memcg's inner layout */
+#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
+
+void sock_update_memcg(struct sock *sk)
+{
+	if (mem_cgroup_sockets_enabled) {
+		struct mem_cgroup *memcg;
+		struct cg_proto *cg_proto;
+
+		BUG_ON(!sk->sk_prot->proto_cgroup);
+
+		/* Socket cloning can throw us here with sk_cgrp already
+		 * filled. It won't however, necessarily happen from
+		 * process context. So the test for root memcg given
+		 * the current task's memcg won't help us in this case.
+		 *
+		 * Respecting the original socket's memcg is a better
+		 * decision in this case.
+		 */
+		if (sk->sk_cgrp) {
+			BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
+			css_get(&sk->sk_cgrp->memcg->css);
+			return;
+		}
+
+		rcu_read_lock();
+		memcg = mem_cgroup_from_task(current);
+		cg_proto = sk->sk_prot->proto_cgroup(memcg);
+		if (cg_proto && test_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags) &&
+		    css_tryget_online(&memcg->css)) {
+			sk->sk_cgrp = cg_proto;
+		}
+		rcu_read_unlock();
+	}
+}
+EXPORT_SYMBOL(sock_update_memcg);
+
+void sock_release_memcg(struct sock *sk)
+{
+	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
+		struct mem_cgroup *memcg;
+		WARN_ON(!sk->sk_cgrp->memcg);
+		memcg = sk->sk_cgrp->memcg;
+		css_put(&sk->sk_cgrp->memcg->css);
+	}
+}
+
+struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
+{
+	if (!memcg || mem_cgroup_is_root(memcg))
+		return NULL;
+
+	return &memcg->tcp_mem;
+}
+EXPORT_SYMBOL(tcp_proto_cgroup);
+
+#endif
+
+#ifdef CONFIG_MEMCG_KMEM
+/*
+ * This will be the memcg's index in each cache's ->memcg_params.memcg_caches.
+ * The main reason for not using cgroup id for this:
+ *  this works better in sparse environments, where we have a lot of memcgs,
+ *  but only a few kmem-limited. Or also, if we have, for instance, 200
+ *  memcgs, and none but the 200th is kmem-limited, we'd have to have a
+ *  200 entry array for that.
+ *
+ * The current size of the caches array is stored in memcg_nr_cache_ids. It
+ * will double each time we have to increase it.
+ */
+static DEFINE_IDA(memcg_cache_ida);
+int memcg_nr_cache_ids;
+
+/* Protects memcg_nr_cache_ids */
+static DECLARE_RWSEM(memcg_cache_ids_sem);
+
+void memcg_get_cache_ids(void)
+{
+	down_read(&memcg_cache_ids_sem);
+}
+
+void memcg_put_cache_ids(void)
+{
+	up_read(&memcg_cache_ids_sem);
+}
+
+/*
+ * MIN_SIZE is different than 1, because we would like to avoid going through
+ * the alloc/free process all the time. In a small machine, 4 kmem-limited
+ * cgroups is a reasonable guess. In the future, it could be a parameter or
+ * tunable, but that is strictly not necessary.
+ *
+ * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
+ * this constant directly from cgroup, but it is understandable that this is
+ * better kept as an internal representation in cgroup.c. In any case, the
+ * cgrp_id space is not getting any smaller, and we don't have to necessarily
+ * increase ours as well if it increases.
+ */
+#define MEMCG_CACHES_MIN_SIZE 4
+#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX
+
+/*
+ * A lot of the calls to the cache allocation functions are expected to be
+ * inlined by the compiler. Since the calls to memcg_kmem_get_cache are
+ * conditional to this static branch, we'll have to allow modules that does
+ * kmem_cache_alloc and the such to see this symbol as well
+ */
+struct static_key memcg_kmem_enabled_key;
+EXPORT_SYMBOL(memcg_kmem_enabled_key);
+
+#endif /* CONFIG_MEMCG_KMEM */
+
+static struct mem_cgroup_per_zone *
+mem_cgroup_zone_zoneinfo(struct mem_cgroup *memcg, struct zone *zone)
+{
+	int nid = zone_to_nid(zone);
+	int zid = zone_idx(zone);
+
+	return &memcg->nodeinfo[nid]->zoneinfo[zid];
+}
+
+/**
+ * mem_cgroup_css_from_page - css of the memcg associated with a page
+ * @page: page of interest
+ *
+ * If memcg is bound to the default hierarchy, css of the memcg associated
+ * with @page is returned.  The returned css remains associated with @page
+ * until it is released.
+ *
+ * If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup
+ * is returned.
+ *
+ * XXX: The above description of behavior on the default hierarchy isn't
+ * strictly true yet as replace_page_cache_page() can modify the
+ * association before @page is released even on the default hierarchy;
+ * however, the current and planned usages don't mix the the two functions
+ * and replace_page_cache_page() will soon be updated to make the invariant
+ * actually true.
+ */
+struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	rcu_read_lock();
+
+	memcg = page->mem_cgroup;
+
+	if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		memcg = root_mem_cgroup;
+
+	rcu_read_unlock();
+	return &memcg->css;
+}
+
+/**
+ * page_cgroup_ino - return inode number of the memcg a page is charged to
+ * @page: the page
+ *
+ * Look up the closest online ancestor of the memory cgroup @page is charged to
+ * and return its inode number or 0 if @page is not charged to any cgroup. It
+ * is safe to call this function without holding a reference to @page.
+ *
+ * Note, this function is inherently racy, because there is nothing to prevent
+ * the cgroup inode from getting torn down and potentially reallocated a moment
+ * after page_cgroup_ino() returns, so it only should be used by callers that
+ * do not care (such as procfs interfaces).
+ */
+ino_t page_cgroup_ino(struct page *page)
+{
+	struct mem_cgroup *memcg;
+	unsigned long ino = 0;
+
+	rcu_read_lock();
+	memcg = READ_ONCE(page->mem_cgroup);
+	while (memcg && !(memcg->css.flags & CSS_ONLINE))
+		memcg = parent_mem_cgroup(memcg);
+	if (memcg)
+		ino = cgroup_ino(memcg->css.cgroup);
+	rcu_read_unlock();
+	return ino;
+}
+
+static struct mem_cgroup_per_zone *
+mem_cgroup_page_zoneinfo(struct mem_cgroup *memcg, struct page *page)
+{
+	int nid = page_to_nid(page);
+	int zid = page_zonenum(page);
+
+	return &memcg->nodeinfo[nid]->zoneinfo[zid];
+}
+
+static struct mem_cgroup_tree_per_zone *
+soft_limit_tree_node_zone(int nid, int zid)
+{
+	return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
+}
+
+static struct mem_cgroup_tree_per_zone *
+soft_limit_tree_from_page(struct page *page)
+{
+	int nid = page_to_nid(page);
+	int zid = page_zonenum(page);
+
+	return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
+}
+
+static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_zone *mz,
+					 struct mem_cgroup_tree_per_zone *mctz,
+					 unsigned long new_usage_in_excess)
+{
+	struct rb_node **p = &mctz->rb_root.rb_node;
+	struct rb_node *parent = NULL;
+	struct mem_cgroup_per_zone *mz_node;
+
+	if (mz->on_tree)
+		return;
+
+	mz->usage_in_excess = new_usage_in_excess;
+	if (!mz->usage_in_excess)
+		return;
+	while (*p) {
+		parent = *p;
+		mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
+					tree_node);
+		if (mz->usage_in_excess < mz_node->usage_in_excess)
+			p = &(*p)->rb_left;
+		/*
+		 * We can't avoid mem cgroups that are over their soft
+		 * limit by the same amount
+		 */
+		else if (mz->usage_in_excess >= mz_node->usage_in_excess)
+			p = &(*p)->rb_right;
+	}
+	rb_link_node(&mz->tree_node, parent, p);
+	rb_insert_color(&mz->tree_node, &mctz->rb_root);
+	mz->on_tree = true;
+}
+
+static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_zone *mz,
+					 struct mem_cgroup_tree_per_zone *mctz)
+{
+	if (!mz->on_tree)
+		return;
+	rb_erase(&mz->tree_node, &mctz->rb_root);
+	mz->on_tree = false;
+}
+
+static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_zone *mz,
+				       struct mem_cgroup_tree_per_zone *mctz)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&mctz->lock, flags);
+	__mem_cgroup_remove_exceeded(mz, mctz);
+	spin_unlock_irqrestore(&mctz->lock, flags);
+}
+
+static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
+{
+	unsigned long nr_pages = page_counter_read(&memcg->memory);
+	unsigned long soft_limit = READ_ONCE(memcg->soft_limit);
+	unsigned long excess = 0;
+
+	if (nr_pages > soft_limit)
+		excess = nr_pages - soft_limit;
+
+	return excess;
+}
+
+static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
+{
+	unsigned long excess;
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup_tree_per_zone *mctz;
+
+	mctz = soft_limit_tree_from_page(page);
+	/*
+	 * Necessary to update all ancestors when hierarchy is used.
+	 * because their event counter is not touched.
+	 */
+	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
+		mz = mem_cgroup_page_zoneinfo(memcg, page);
+		excess = soft_limit_excess(memcg);
+		/*
+		 * We have to update the tree if mz is on RB-tree or
+		 * mem is over its softlimit.
+		 */
+		if (excess || mz->on_tree) {
+			unsigned long flags;
+
+			spin_lock_irqsave(&mctz->lock, flags);
+			/* if on-tree, remove it */
+			if (mz->on_tree)
+				__mem_cgroup_remove_exceeded(mz, mctz);
+			/*
+			 * Insert again. mz->usage_in_excess will be updated.
+			 * If excess is 0, no tree ops.
+			 */
+			__mem_cgroup_insert_exceeded(mz, mctz, excess);
+			spin_unlock_irqrestore(&mctz->lock, flags);
+		}
+	}
+}
+
+static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_tree_per_zone *mctz;
+	struct mem_cgroup_per_zone *mz;
+	int nid, zid;
+
+	for_each_node(nid) {
+		for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+			mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
+			mctz = soft_limit_tree_node_zone(nid, zid);
+			mem_cgroup_remove_exceeded(mz, mctz);
+		}
+	}
+}
+
+static struct mem_cgroup_per_zone *
+__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
+{
+	struct rb_node *rightmost = NULL;
+	struct mem_cgroup_per_zone *mz;
+
+retry:
+	mz = NULL;
+	rightmost = rb_last(&mctz->rb_root);
+	if (!rightmost)
+		goto done;		/* Nothing to reclaim from */
+
+	mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
+	/*
+	 * Remove the node now but someone else can add it back,
+	 * we will to add it back at the end of reclaim to its correct
+	 * position in the tree.
+	 */
+	__mem_cgroup_remove_exceeded(mz, mctz);
+	if (!soft_limit_excess(mz->memcg) ||
+	    !css_tryget_online(&mz->memcg->css))
+		goto retry;
+done:
+	return mz;
+}
+
+static struct mem_cgroup_per_zone *
+mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
+{
+	struct mem_cgroup_per_zone *mz;
+
+	spin_lock_irq(&mctz->lock);
+	mz = __mem_cgroup_largest_soft_limit_node(mctz);
+	spin_unlock_irq(&mctz->lock);
+	return mz;
+}
+
+/*
+ * Return page count for single (non recursive) @memcg.
+ *
+ * Implementation Note: reading percpu statistics for memcg.
+ *
+ * Both of vmstat[] and percpu_counter has threshold and do periodic
+ * synchronization to implement "quick" read. There are trade-off between
+ * reading cost and precision of value. Then, we may have a chance to implement
+ * a periodic synchronization of counter in memcg's counter.
+ *
+ * But this _read() function is used for user interface now. The user accounts
+ * memory usage by memory cgroup and he _always_ requires exact value because
+ * he accounts memory. Even if we provide quick-and-fuzzy read, we always
+ * have to visit all online cpus and make sum. So, for now, unnecessary
+ * synchronization is not implemented. (just implemented for cpu hotplug)
+ *
+ * If there are kernel internal actions which can make use of some not-exact
+ * value, and reading all cpu value can be performance bottleneck in some
+ * common workload, threshold and synchronization as vmstat[] should be
+ * implemented.
+ */
+static unsigned long
+mem_cgroup_read_stat(struct mem_cgroup *memcg, enum mem_cgroup_stat_index idx)
+{
+	long val = 0;
+	int cpu;
+
+	/* Per-cpu values can be negative, use a signed accumulator */
+	for_each_possible_cpu(cpu)
+		val += per_cpu(memcg->stat->count[idx], cpu);
+	/*
+	 * Summing races with updates, so val may be negative.  Avoid exposing
+	 * transient negative values.
+	 */
+	if (val < 0)
+		val = 0;
+	return val;
+}
+
+static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
+					    enum mem_cgroup_events_index idx)
+{
+	unsigned long val = 0;
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		val += per_cpu(memcg->stat->events[idx], cpu);
+	return val;
+}
+
+static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
+					 struct page *page,
+					 int nr_pages)
+{
+	/*
+	 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
+	 * counted as CACHE even if it's on ANON LRU.
+	 */
+	if (PageAnon(page))
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
+				nr_pages);
+	else
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
+				nr_pages);
+
+	if (PageTransHuge(page))
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
+				nr_pages);
+
+	/* pagein of a big page is an event. So, ignore page size */
+	if (nr_pages > 0)
+		__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
+	else {
+		__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
+		nr_pages = -nr_pages; /* for event */
+	}
+
+	__this_cpu_add(memcg->stat->nr_page_events, nr_pages);
+}
+
+static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
+						  int nid,
+						  unsigned int lru_mask)
+{
+	unsigned long nr = 0;
+	int zid;
+
+	VM_BUG_ON((unsigned)nid >= nr_node_ids);
+
+	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+		struct mem_cgroup_per_zone *mz;
+		enum lru_list lru;
+
+		for_each_lru(lru) {
+			if (!(BIT(lru) & lru_mask))
+				continue;
+			mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
+			nr += mz->lru_size[lru];
+		}
+	}
+	return nr;
+}
+
+static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
+			unsigned int lru_mask)
+{
+	unsigned long nr = 0;
+	int nid;
+
+	for_each_node_state(nid, N_MEMORY)
+		nr += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
+	return nr;
+}
+
+static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
+				       enum mem_cgroup_events_target target)
+{
+	unsigned long val, next;
+
+	val = __this_cpu_read(memcg->stat->nr_page_events);
+	next = __this_cpu_read(memcg->stat->targets[target]);
+	/* from time_after() in jiffies.h */
+	if ((long)next - (long)val < 0) {
+		switch (target) {
+		case MEM_CGROUP_TARGET_THRESH:
+			next = val + THRESHOLDS_EVENTS_TARGET;
+			break;
+		case MEM_CGROUP_TARGET_SOFTLIMIT:
+			next = val + SOFTLIMIT_EVENTS_TARGET;
+			break;
+		case MEM_CGROUP_TARGET_NUMAINFO:
+			next = val + NUMAINFO_EVENTS_TARGET;
+			break;
+		default:
+			break;
+		}
+		__this_cpu_write(memcg->stat->targets[target], next);
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Check events in order.
+ *
+ */
+static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
+{
+	/* threshold event is triggered in finer grain than soft limit */
+	if (unlikely(mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_THRESH))) {
+		bool do_softlimit;
+		bool do_numainfo __maybe_unused;
+
+		do_softlimit = mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_SOFTLIMIT);
+#if MAX_NUMNODES > 1
+		do_numainfo = mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_NUMAINFO);
+#endif
+		mem_cgroup_threshold(memcg);
+		if (unlikely(do_softlimit))
+			mem_cgroup_update_tree(memcg, page);
+#if MAX_NUMNODES > 1
+		if (unlikely(do_numainfo))
+			atomic_inc(&memcg->numainfo_events);
+#endif
+	}
+}
+
+struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
+{
+	/*
+	 * mm_update_next_owner() may clear mm->owner to NULL
+	 * if it races with swapoff, page migration, etc.
+	 * So this can be called with p == NULL.
+	 */
+	if (unlikely(!p))
+		return NULL;
+
+	return mem_cgroup_from_css(task_css(p, memory_cgrp_id));
+}
+EXPORT_SYMBOL(mem_cgroup_from_task);
+
+static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
+{
+	struct mem_cgroup *memcg = NULL;
+
+	rcu_read_lock();
+	do {
+		/*
+		 * Page cache insertions can happen withou an
+		 * actual mm context, e.g. during disk probing
+		 * on boot, loopback IO, acct() writes etc.
+		 */
+		if (unlikely(!mm))
+			memcg = root_mem_cgroup;
+		else {
+			memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+			if (unlikely(!memcg))
+				memcg = root_mem_cgroup;
+		}
+	} while (!css_tryget_online(&memcg->css));
+	rcu_read_unlock();
+	return memcg;
+}
+
+/**
+ * mem_cgroup_iter - iterate over memory cgroup hierarchy
+ * @root: hierarchy root
+ * @prev: previously returned memcg, NULL on first invocation
+ * @reclaim: cookie for shared reclaim walks, NULL for full walks
+ *
+ * Returns references to children of the hierarchy below @root, or
+ * @root itself, or %NULL after a full round-trip.
+ *
+ * Caller must pass the return value in @prev on subsequent
+ * invocations for reference counting, or use mem_cgroup_iter_break()
+ * to cancel a hierarchy walk before the round-trip is complete.
+ *
+ * Reclaimers can specify a zone and a priority level in @reclaim to
+ * divide up the memcgs in the hierarchy among all concurrent
+ * reclaimers operating on the same zone and priority.
+ */
+struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
+				   struct mem_cgroup *prev,
+				   struct mem_cgroup_reclaim_cookie *reclaim)
+{
+	struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
+	struct cgroup_subsys_state *css = NULL;
+	struct mem_cgroup *memcg = NULL;
+	struct mem_cgroup *pos = NULL;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	if (!root)
+		root = root_mem_cgroup;
+
+	if (prev && !reclaim)
+		pos = prev;
+
+	if (!root->use_hierarchy && root != root_mem_cgroup) {
+		if (prev)
+			goto out;
+		return root;
+	}
+
+	rcu_read_lock();
+
+	if (reclaim) {
+		struct mem_cgroup_per_zone *mz;
+
+		mz = mem_cgroup_zone_zoneinfo(root, reclaim->zone);
+		iter = &mz->iter[reclaim->priority];
+
+		if (prev && reclaim->generation != iter->generation)
+			goto out_unlock;
+
+		while (1) {
+			pos = READ_ONCE(iter->position);
+			if (!pos || css_tryget(&pos->css))
+				break;
+			/*
+			 * css reference reached zero, so iter->position will
+			 * be cleared by ->css_released. However, we should not
+			 * rely on this happening soon, because ->css_released
+			 * is called from a work queue, and by busy-waiting we
+			 * might block it. So we clear iter->position right
+			 * away.
+			 */
+			(void)cmpxchg(&iter->position, pos, NULL);
+		}
+	}
+
+	if (pos)
+		css = &pos->css;
+
+	for (;;) {
+		css = css_next_descendant_pre(css, &root->css);
+		if (!css) {
+			/*
+			 * Reclaimers share the hierarchy walk, and a
+			 * new one might jump in right at the end of
+			 * the hierarchy - make sure they see at least
+			 * one group and restart from the beginning.
+			 */
+			if (!prev)
+				continue;
+			break;
+		}
+
+		/*
+		 * Verify the css and acquire a reference.  The root
+		 * is provided by the caller, so we know it's alive
+		 * and kicking, and don't take an extra reference.
+		 */
+		memcg = mem_cgroup_from_css(css);
+
+		if (css == &root->css)
+			break;
+
+		if (css_tryget(css)) {
+			/*
+			 * Make sure the memcg is initialized:
+			 * mem_cgroup_css_online() orders the the
+			 * initialization against setting the flag.
+			 */
+			if (smp_load_acquire(&memcg->initialized))
+				break;
+
+			css_put(css);
+		}
+
+		memcg = NULL;
+	}
+
+	if (reclaim) {
+		/*
+		 * The position could have already been updated by a competing
+		 * thread, so check that the value hasn't changed since we read
+		 * it to avoid reclaiming from the same cgroup twice.
+		 */
+		(void)cmpxchg(&iter->position, pos, memcg);
+
+		if (pos)
+			css_put(&pos->css);
+
+		if (!memcg)
+			iter->generation++;
+		else if (!prev)
+			reclaim->generation = iter->generation;
+	}
+
+out_unlock:
+	rcu_read_unlock();
+out:
+	if (prev && prev != root)
+		css_put(&prev->css);
+
+	return memcg;
+}
+
+/**
+ * mem_cgroup_iter_break - abort a hierarchy walk prematurely
+ * @root: hierarchy root
+ * @prev: last visited hierarchy member as returned by mem_cgroup_iter()
+ */
+void mem_cgroup_iter_break(struct mem_cgroup *root,
+			   struct mem_cgroup *prev)
+{
+	if (!root)
+		root = root_mem_cgroup;
+	if (prev && prev != root)
+		css_put(&prev->css);
+}
+
+static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
+{
+	struct mem_cgroup *memcg = dead_memcg;
+	struct mem_cgroup_reclaim_iter *iter;
+	struct mem_cgroup_per_zone *mz;
+	int nid, zid;
+	int i;
+
+	while ((memcg = parent_mem_cgroup(memcg))) {
+		for_each_node(nid) {
+			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+				mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
+				for (i = 0; i <= DEF_PRIORITY; i++) {
+					iter = &mz->iter[i];
+					cmpxchg(&iter->position,
+						dead_memcg, NULL);
+				}
+			}
+		}
+	}
+}
+
+/*
+ * Iteration constructs for visiting all cgroups (under a tree).  If
+ * loops are exited prematurely (break), mem_cgroup_iter_break() must
+ * be used for reference counting.
+ */
+#define for_each_mem_cgroup_tree(iter, root)		\
+	for (iter = mem_cgroup_iter(root, NULL, NULL);	\
+	     iter != NULL;				\
+	     iter = mem_cgroup_iter(root, iter, NULL))
+
+#define for_each_mem_cgroup(iter)			\
+	for (iter = mem_cgroup_iter(NULL, NULL, NULL);	\
+	     iter != NULL;				\
+	     iter = mem_cgroup_iter(NULL, iter, NULL))
+
+/**
+ * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
+ * @zone: zone of the wanted lruvec
+ * @memcg: memcg of the wanted lruvec
+ *
+ * Returns the lru list vector holding pages for the given @zone and
+ * @mem.  This can be the global zone lruvec, if the memory controller
+ * is disabled.
+ */
+struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
+				      struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct lruvec *lruvec;
+
+	if (mem_cgroup_disabled()) {
+		lruvec = &zone->lruvec;
+		goto out;
+	}
+
+	mz = mem_cgroup_zone_zoneinfo(memcg, zone);
+	lruvec = &mz->lruvec;
+out:
+	/*
+	 * Since a node can be onlined after the mem_cgroup was created,
+	 * we have to be prepared to initialize lruvec->zone here;
+	 * and if offlined then reonlined, we need to reinitialize it.
+	 */
+	if (unlikely(lruvec->zone != zone))
+		lruvec->zone = zone;
+	return lruvec;
+}
+
+/**
+ * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
+ * @page: the page
+ * @zone: zone of the page
+ *
+ * This function is only safe when following the LRU page isolation
+ * and putback protocol: the LRU lock must be held, and the page must
+ * either be PageLRU() or the caller must have isolated/allocated it.
+ */
+struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup *memcg;
+	struct lruvec *lruvec;
+
+	if (mem_cgroup_disabled()) {
+		lruvec = &zone->lruvec;
+		goto out;
+	}
+
+	memcg = page->mem_cgroup;
+	/*
+	 * Swapcache readahead pages are added to the LRU - and
+	 * possibly migrated - before they are charged.
+	 */
+	if (!memcg)
+		memcg = root_mem_cgroup;
+
+	mz = mem_cgroup_page_zoneinfo(memcg, page);
+	lruvec = &mz->lruvec;
+out:
+	/*
+	 * Since a node can be onlined after the mem_cgroup was created,
+	 * we have to be prepared to initialize lruvec->zone here;
+	 * and if offlined then reonlined, we need to reinitialize it.
+	 */
+	if (unlikely(lruvec->zone != zone))
+		lruvec->zone = zone;
+	return lruvec;
+}
+
+/**
+ * mem_cgroup_update_lru_size - account for adding or removing an lru page
+ * @lruvec: mem_cgroup per zone lru vector
+ * @lru: index of lru list the page is sitting on
+ * @nr_pages: positive when adding or negative when removing
+ *
+ * This function must be called when a page is added to or removed from an
+ * lru list.
+ */
+void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
+				int nr_pages)
+{
+	struct mem_cgroup_per_zone *mz;
+	unsigned long *lru_size;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
+	lru_size = mz->lru_size + lru;
+	*lru_size += nr_pages;
+	VM_BUG_ON((long)(*lru_size) < 0);
+}
+
+bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *task_memcg;
+	struct task_struct *p;
+	bool ret;
+
+	p = find_lock_task_mm(task);
+	if (p) {
+		task_memcg = get_mem_cgroup_from_mm(p->mm);
+		task_unlock(p);
+	} else {
+		/*
+		 * All threads may have already detached their mm's, but the oom
+		 * killer still needs to detect if they have already been oom
+		 * killed to prevent needlessly killing additional tasks.
+		 */
+		rcu_read_lock();
+		task_memcg = mem_cgroup_from_task(task);
+		css_get(&task_memcg->css);
+		rcu_read_unlock();
+	}
+	ret = mem_cgroup_is_descendant(task_memcg, memcg);
+	css_put(&task_memcg->css);
+	return ret;
+}
+
+#define mem_cgroup_from_counter(counter, member)	\
+	container_of(counter, struct mem_cgroup, member)
+
+/**
+ * mem_cgroup_margin - calculate chargeable space of a memory cgroup
+ * @memcg: the memory cgroup
+ *
+ * Returns the maximum amount of memory @mem can be charged with, in
+ * pages.
+ */
+static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
+{
+	unsigned long margin = 0;
+	unsigned long count;
+	unsigned long limit;
+
+	count = page_counter_read(&memcg->memory);
+	limit = READ_ONCE(memcg->memory.limit);
+	if (count < limit)
+		margin = limit - count;
+
+	if (do_swap_account) {
+		count = page_counter_read(&memcg->memsw);
+		limit = READ_ONCE(memcg->memsw.limit);
+		if (count <= limit)
+			margin = min(margin, limit - count);
+	}
+
+	return margin;
+}
+
+/*
+ * A routine for checking "mem" is under move_account() or not.
+ *
+ * Checking a cgroup is mc.from or mc.to or under hierarchy of
+ * moving cgroups. This is for waiting at high-memory pressure
+ * caused by "move".
+ */
+static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *from;
+	struct mem_cgroup *to;
+	bool ret = false;
+	/*
+	 * Unlike task_move routines, we access mc.to, mc.from not under
+	 * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
+	 */
+	spin_lock(&mc.lock);
+	from = mc.from;
+	to = mc.to;
+	if (!from)
+		goto unlock;
+
+	ret = mem_cgroup_is_descendant(from, memcg) ||
+		mem_cgroup_is_descendant(to, memcg);
+unlock:
+	spin_unlock(&mc.lock);
+	return ret;
+}
+
+static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
+{
+	if (mc.moving_task && current != mc.moving_task) {
+		if (mem_cgroup_under_move(memcg)) {
+			DEFINE_WAIT(wait);
+			prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
+			/* moving charge context might have finished. */
+			if (mc.moving_task)
+				schedule();
+			finish_wait(&mc.waitq, &wait);
+			return true;
+		}
+	}
+	return false;
+}
+
+#define K(x) ((x) << (PAGE_SHIFT-10))
+/**
+ * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
+ * @memcg: The memory cgroup that went over limit
+ * @p: Task that is going to be killed
+ *
+ * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
+ * enabled
+ */
+void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
+{
+	/* oom_info_lock ensures that parallel ooms do not interleave */
+	static DEFINE_MUTEX(oom_info_lock);
+	struct mem_cgroup *iter;
+	unsigned int i;
+
+	mutex_lock(&oom_info_lock);
+	rcu_read_lock();
+
+	if (p) {
+		pr_info("Task in ");
+		pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
+		pr_cont(" killed as a result of limit of ");
+	} else {
+		pr_info("Memory limit reached of cgroup ");
+	}
+
+	pr_cont_cgroup_path(memcg->css.cgroup);
+	pr_cont("\n");
+
+	rcu_read_unlock();
+
+	pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
+		K((u64)page_counter_read(&memcg->memory)),
+		K((u64)memcg->memory.limit), memcg->memory.failcnt);
+	pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
+		K((u64)page_counter_read(&memcg->memsw)),
+		K((u64)memcg->memsw.limit), memcg->memsw.failcnt);
+	pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n",
+		K((u64)page_counter_read(&memcg->kmem)),
+		K((u64)memcg->kmem.limit), memcg->kmem.failcnt);
+
+	for_each_mem_cgroup_tree(iter, memcg) {
+		pr_info("Memory cgroup stats for ");
+		pr_cont_cgroup_path(iter->css.cgroup);
+		pr_cont(":");
+
+		for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
+			if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
+				continue;
+			pr_cont(" %s:%luKB", mem_cgroup_stat_names[i],
+				K(mem_cgroup_read_stat(iter, i)));
+		}
+
+		for (i = 0; i < NR_LRU_LISTS; i++)
+			pr_cont(" %s:%luKB", mem_cgroup_lru_names[i],
+				K(mem_cgroup_nr_lru_pages(iter, BIT(i))));
+
+		pr_cont("\n");
+	}
+	mutex_unlock(&oom_info_lock);
+}
+
+/*
+ * This function returns the number of memcg under hierarchy tree. Returns
+ * 1(self count) if no children.
+ */
+static int mem_cgroup_count_children(struct mem_cgroup *memcg)
+{
+	int num = 0;
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		num++;
+	return num;
+}
+
+/*
+ * Return the memory (and swap, if configured) limit for a memcg.
+ */
+static unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
+{
+	unsigned long limit;
+
+	limit = memcg->memory.limit;
+	if (mem_cgroup_swappiness(memcg)) {
+		unsigned long memsw_limit;
+
+		memsw_limit = memcg->memsw.limit;
+		limit = min(limit + total_swap_pages, memsw_limit);
+	}
+	return limit;
+}
+
+static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
+				     int order)
+{
+	struct oom_control oc = {
+		.zonelist = NULL,
+		.nodemask = NULL,
+		.gfp_mask = gfp_mask,
+		.order = order,
+	};
+	struct mem_cgroup *iter;
+	unsigned long chosen_points = 0;
+	unsigned long totalpages;
+	unsigned int points = 0;
+	struct task_struct *chosen = NULL;
+
+	mutex_lock(&oom_lock);
+
+	/*
+	 * If current has a pending SIGKILL or is exiting, then automatically
+	 * select it.  The goal is to allow it to allocate so that it may
+	 * quickly exit and free its memory.
+	 */
+	if (fatal_signal_pending(current) || task_will_free_mem(current)) {
+		mark_oom_victim(current);
+		goto unlock;
+	}
+
+	check_panic_on_oom(&oc, CONSTRAINT_MEMCG, memcg);
+	totalpages = mem_cgroup_get_limit(memcg) ? : 1;
+	for_each_mem_cgroup_tree(iter, memcg) {
+		struct css_task_iter it;
+		struct task_struct *task;
+
+		css_task_iter_start(&iter->css, &it);
+		while ((task = css_task_iter_next(&it))) {
+			switch (oom_scan_process_thread(&oc, task, totalpages)) {
+			case OOM_SCAN_SELECT:
+				if (chosen)
+					put_task_struct(chosen);
+				chosen = task;
+				chosen_points = ULONG_MAX;
+				get_task_struct(chosen);
+				/* fall through */
+			case OOM_SCAN_CONTINUE:
+				continue;
+			case OOM_SCAN_ABORT:
+				css_task_iter_end(&it);
+				mem_cgroup_iter_break(memcg, iter);
+				if (chosen)
+					put_task_struct(chosen);
+				goto unlock;
+			case OOM_SCAN_OK:
+				break;
+			};
+			points = oom_badness(task, memcg, NULL, totalpages);
+			if (!points || points < chosen_points)
+				continue;
+			/* Prefer thread group leaders for display purposes */
+			if (points == chosen_points &&
+			    thread_group_leader(chosen))
+				continue;
+
+			if (chosen)
+				put_task_struct(chosen);
+			chosen = task;
+			chosen_points = points;
+			get_task_struct(chosen);
+		}
+		css_task_iter_end(&it);
+	}
+
+	if (chosen) {
+		points = chosen_points * 1000 / totalpages;
+		oom_kill_process(&oc, chosen, points, totalpages, memcg,
+				 "Memory cgroup out of memory");
+	}
+unlock:
+	mutex_unlock(&oom_lock);
+	return chosen;
+}
+
+#if MAX_NUMNODES > 1
+
+/**
+ * test_mem_cgroup_node_reclaimable
+ * @memcg: the target memcg
+ * @nid: the node ID to be checked.
+ * @noswap : specify true here if the user wants flle only information.
+ *
+ * This function returns whether the specified memcg contains any
+ * reclaimable pages on a node. Returns true if there are any reclaimable
+ * pages in the node.
+ */
+static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
+		int nid, bool noswap)
+{
+	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
+		return true;
+	if (noswap || !total_swap_pages)
+		return false;
+	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
+		return true;
+	return false;
+
+}
+
+/*
+ * Always updating the nodemask is not very good - even if we have an empty
+ * list or the wrong list here, we can start from some node and traverse all
+ * nodes based on the zonelist. So update the list loosely once per 10 secs.
+ *
+ */
+static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
+{
+	int nid;
+	/*
+	 * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
+	 * pagein/pageout changes since the last update.
+	 */
+	if (!atomic_read(&memcg->numainfo_events))
+		return;
+	if (atomic_inc_return(&memcg->numainfo_updating) > 1)
+		return;
+
+	/* make a nodemask where this memcg uses memory from */
+	memcg->scan_nodes = node_states[N_MEMORY];
+
+	for_each_node_mask(nid, node_states[N_MEMORY]) {
+
+		if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
+			node_clear(nid, memcg->scan_nodes);
+	}
+
+	atomic_set(&memcg->numainfo_events, 0);
+	atomic_set(&memcg->numainfo_updating, 0);
+}
+
+/*
+ * Selecting a node where we start reclaim from. Because what we need is just
+ * reducing usage counter, start from anywhere is O,K. Considering
+ * memory reclaim from current node, there are pros. and cons.
+ *
+ * Freeing memory from current node means freeing memory from a node which
+ * we'll use or we've used. So, it may make LRU bad. And if several threads
+ * hit limits, it will see a contention on a node. But freeing from remote
+ * node means more costs for memory reclaim because of memory latency.
+ *
+ * Now, we use round-robin. Better algorithm is welcomed.
+ */
+int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
+{
+	int node;
+
+	mem_cgroup_may_update_nodemask(memcg);
+	node = memcg->last_scanned_node;
+
+	node = next_node(node, memcg->scan_nodes);
+	if (node == MAX_NUMNODES)
+		node = first_node(memcg->scan_nodes);
+	/*
+	 * We call this when we hit limit, not when pages are added to LRU.
+	 * No LRU may hold pages because all pages are UNEVICTABLE or
+	 * memcg is too small and all pages are not on LRU. In that case,
+	 * we use curret node.
+	 */
+	if (unlikely(node == MAX_NUMNODES))
+		node = numa_node_id();
+
+	memcg->last_scanned_node = node;
+	return node;
+}
+#else
+int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
+{
+	return 0;
+}
+#endif
+
+static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
+				   struct zone *zone,
+				   gfp_t gfp_mask,
+				   unsigned long *total_scanned)
+{
+	struct mem_cgroup *victim = NULL;
+	int total = 0;
+	int loop = 0;
+	unsigned long excess;
+	unsigned long nr_scanned;
+	struct mem_cgroup_reclaim_cookie reclaim = {
+		.zone = zone,
+		.priority = 0,
+	};
+
+	excess = soft_limit_excess(root_memcg);
+
+	while (1) {
+		victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
+		if (!victim) {
+			loop++;
+			if (loop >= 2) {
+				/*
+				 * If we have not been able to reclaim
+				 * anything, it might because there are
+				 * no reclaimable pages under this hierarchy
+				 */
+				if (!total)
+					break;
+				/*
+				 * We want to do more targeted reclaim.
+				 * excess >> 2 is not to excessive so as to
+				 * reclaim too much, nor too less that we keep
+				 * coming back to reclaim from this cgroup
+				 */
+				if (total >= (excess >> 2) ||
+					(loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
+					break;
+			}
+			continue;
+		}
+		total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
+						     zone, &nr_scanned);
+		*total_scanned += nr_scanned;
+		if (!soft_limit_excess(root_memcg))
+			break;
+	}
+	mem_cgroup_iter_break(root_memcg, victim);
+	return total;
+}
+
+#ifdef CONFIG_LOCKDEP
+static struct lockdep_map memcg_oom_lock_dep_map = {
+	.name = "memcg_oom_lock",
+};
+#endif
+
+static DEFINE_SPINLOCK(memcg_oom_lock);
+
+/*
+ * Check OOM-Killer is already running under our hierarchy.
+ * If someone is running, return false.
+ */
+static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter, *failed = NULL;
+
+	spin_lock(&memcg_oom_lock);
+
+	for_each_mem_cgroup_tree(iter, memcg) {
+		if (iter->oom_lock) {
+			/*
+			 * this subtree of our hierarchy is already locked
+			 * so we cannot give a lock.
+			 */
+			failed = iter;
+			mem_cgroup_iter_break(memcg, iter);
+			break;
+		} else
+			iter->oom_lock = true;
+	}
+
+	if (failed) {
+		/*
+		 * OK, we failed to lock the whole subtree so we have
+		 * to clean up what we set up to the failing subtree
+		 */
+		for_each_mem_cgroup_tree(iter, memcg) {
+			if (iter == failed) {
+				mem_cgroup_iter_break(memcg, iter);
+				break;
+			}
+			iter->oom_lock = false;
+		}
+	} else
+		mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
+
+	spin_unlock(&memcg_oom_lock);
+
+	return !failed;
+}
+
+static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	spin_lock(&memcg_oom_lock);
+	mutex_release(&memcg_oom_lock_dep_map, 1, _RET_IP_);
+	for_each_mem_cgroup_tree(iter, memcg)
+		iter->oom_lock = false;
+	spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	spin_lock(&memcg_oom_lock);
+	for_each_mem_cgroup_tree(iter, memcg)
+		iter->under_oom++;
+	spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	/*
+	 * When a new child is created while the hierarchy is under oom,
+	 * mem_cgroup_oom_lock() may not be called. Watch for underflow.
+	 */
+	spin_lock(&memcg_oom_lock);
+	for_each_mem_cgroup_tree(iter, memcg)
+		if (iter->under_oom > 0)
+			iter->under_oom--;
+	spin_unlock(&memcg_oom_lock);
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
+
+struct oom_wait_info {
+	struct mem_cgroup *memcg;
+	wait_queue_t	wait;
+};
+
+static int memcg_oom_wake_function(wait_queue_t *wait,
+	unsigned mode, int sync, void *arg)
+{
+	struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
+	struct mem_cgroup *oom_wait_memcg;
+	struct oom_wait_info *oom_wait_info;
+
+	oom_wait_info = container_of(wait, struct oom_wait_info, wait);
+	oom_wait_memcg = oom_wait_info->memcg;
+
+	if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
+	    !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
+		return 0;
+	return autoremove_wake_function(wait, mode, sync, arg);
+}
+
+static void memcg_oom_recover(struct mem_cgroup *memcg)
+{
+	/*
+	 * For the following lockless ->under_oom test, the only required
+	 * guarantee is that it must see the state asserted by an OOM when
+	 * this function is called as a result of userland actions
+	 * triggered by the notification of the OOM.  This is trivially
+	 * achieved by invoking mem_cgroup_mark_under_oom() before
+	 * triggering notification.
+	 */
+	if (memcg && memcg->under_oom)
+		__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
+}
+
+static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
+{
+	if (!current->memcg_may_oom)
+		return;
+	/*
+	 * We are in the middle of the charge context here, so we
+	 * don't want to block when potentially sitting on a callstack
+	 * that holds all kinds of filesystem and mm locks.
+	 *
+	 * Also, the caller may handle a failed allocation gracefully
+	 * (like optional page cache readahead) and so an OOM killer
+	 * invocation might not even be necessary.
+	 *
+	 * That's why we don't do anything here except remember the
+	 * OOM context and then deal with it at the end of the page
+	 * fault when the stack is unwound, the locks are released,
+	 * and when we know whether the fault was overall successful.
+	 */
+	css_get(&memcg->css);
+	current->memcg_in_oom = memcg;
+	current->memcg_oom_gfp_mask = mask;
+	current->memcg_oom_order = order;
+}
+
+/**
+ * mem_cgroup_oom_synchronize - complete memcg OOM handling
+ * @handle: actually kill/wait or just clean up the OOM state
+ *
+ * This has to be called at the end of a page fault if the memcg OOM
+ * handler was enabled.
+ *
+ * Memcg supports userspace OOM handling where failed allocations must
+ * sleep on a waitqueue until the userspace task resolves the
+ * situation.  Sleeping directly in the charge context with all kinds
+ * of locks held is not a good idea, instead we remember an OOM state
+ * in the task and mem_cgroup_oom_synchronize() has to be called at
+ * the end of the page fault to complete the OOM handling.
+ *
+ * Returns %true if an ongoing memcg OOM situation was detected and
+ * completed, %false otherwise.
+ */
+bool mem_cgroup_oom_synchronize(bool handle)
+{
+	struct mem_cgroup *memcg = current->memcg_in_oom;
+	struct oom_wait_info owait;
+	bool locked;
+
+	/* OOM is global, do not handle */
+	if (!memcg)
+		return false;
+
+	if (!handle || oom_killer_disabled)
+		goto cleanup;
+
+	owait.memcg = memcg;
+	owait.wait.flags = 0;
+	owait.wait.func = memcg_oom_wake_function;
+	owait.wait.private = current;
+	INIT_LIST_HEAD(&owait.wait.task_list);
+
+	prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
+	mem_cgroup_mark_under_oom(memcg);
+
+	locked = mem_cgroup_oom_trylock(memcg);
+
+	if (locked)
+		mem_cgroup_oom_notify(memcg);
+
+	if (locked && !memcg->oom_kill_disable) {
+		mem_cgroup_unmark_under_oom(memcg);
+		finish_wait(&memcg_oom_waitq, &owait.wait);
+		mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
+					 current->memcg_oom_order);
+	} else {
+		schedule();
+		mem_cgroup_unmark_under_oom(memcg);
+		finish_wait(&memcg_oom_waitq, &owait.wait);
+	}
+
+	if (locked) {
+		mem_cgroup_oom_unlock(memcg);
+		/*
+		 * There is no guarantee that an OOM-lock contender
+		 * sees the wakeups triggered by the OOM kill
+		 * uncharges.  Wake any sleepers explicitely.
+		 */
+		memcg_oom_recover(memcg);
+	}
+cleanup:
+	current->memcg_in_oom = NULL;
+	css_put(&memcg->css);
+	return true;
+}
+
+/**
+ * mem_cgroup_begin_page_stat - begin a page state statistics transaction
+ * @page: page that is going to change accounted state
+ *
+ * This function must mark the beginning of an accounted page state
+ * change to prevent double accounting when the page is concurrently
+ * being moved to another memcg:
+ *
+ *   memcg = mem_cgroup_begin_page_stat(page);
+ *   if (TestClearPageState(page))
+ *     mem_cgroup_update_page_stat(memcg, state, -1);
+ *   mem_cgroup_end_page_stat(memcg);
+ */
+struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page)
+{
+	struct mem_cgroup *memcg;
+	unsigned long flags;
+
+	/*
+	 * The RCU lock is held throughout the transaction.  The fast
+	 * path can get away without acquiring the memcg->move_lock
+	 * because page moving starts with an RCU grace period.
+	 *
+	 * The RCU lock also protects the memcg from being freed when
+	 * the page state that is going to change is the only thing
+	 * preventing the page from being uncharged.
+	 * E.g. end-writeback clearing PageWriteback(), which allows
+	 * migration to go ahead and uncharge the page before the
+	 * account transaction might be complete.
+	 */
+	rcu_read_lock();
+
+	if (mem_cgroup_disabled())
+		return NULL;
+again:
+	memcg = page->mem_cgroup;
+	if (unlikely(!memcg))
+		return NULL;
+
+	if (atomic_read(&memcg->moving_account) <= 0)
+		return memcg;
+
+	spin_lock_irqsave(&memcg->move_lock, flags);
+	if (memcg != page->mem_cgroup) {
+		spin_unlock_irqrestore(&memcg->move_lock, flags);
+		goto again;
+	}
+
+	/*
+	 * When charge migration first begins, we can have locked and
+	 * unlocked page stat updates happening concurrently.  Track
+	 * the task who has the lock for mem_cgroup_end_page_stat().
+	 */
+	memcg->move_lock_task = current;
+	memcg->move_lock_flags = flags;
+
+	return memcg;
+}
+EXPORT_SYMBOL(mem_cgroup_begin_page_stat);
+
+/**
+ * mem_cgroup_end_page_stat - finish a page state statistics transaction
+ * @memcg: the memcg that was accounted against
+ */
+void mem_cgroup_end_page_stat(struct mem_cgroup *memcg)
+{
+	if (memcg && memcg->move_lock_task == current) {
+		unsigned long flags = memcg->move_lock_flags;
+
+		memcg->move_lock_task = NULL;
+		memcg->move_lock_flags = 0;
+
+		spin_unlock_irqrestore(&memcg->move_lock, flags);
+	}
+
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(mem_cgroup_end_page_stat);
+
+/*
+ * size of first charge trial. "32" comes from vmscan.c's magic value.
+ * TODO: maybe necessary to use big numbers in big irons.
+ */
+#define CHARGE_BATCH	32U
+struct memcg_stock_pcp {
+	struct mem_cgroup *cached; /* this never be root cgroup */
+	unsigned int nr_pages;
+	struct work_struct work;
+	unsigned long flags;
+#define FLUSHING_CACHED_CHARGE	0
+};
+static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
+static DEFINE_MUTEX(percpu_charge_mutex);
+
+/**
+ * consume_stock: Try to consume stocked charge on this cpu.
+ * @memcg: memcg to consume from.
+ * @nr_pages: how many pages to charge.
+ *
+ * The charges will only happen if @memcg matches the current cpu's memcg
+ * stock, and at least @nr_pages are available in that stock.  Failure to
+ * service an allocation will refill the stock.
+ *
+ * returns true if successful, false otherwise.
+ */
+static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	struct memcg_stock_pcp *stock;
+	bool ret = false;
+
+	if (nr_pages > CHARGE_BATCH)
+		return ret;
+
+	stock = &get_cpu_var(memcg_stock);
+	if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
+		stock->nr_pages -= nr_pages;
+		ret = true;
+	}
+	put_cpu_var(memcg_stock);
+	return ret;
+}
+
+/*
+ * Returns stocks cached in percpu and reset cached information.
+ */
+static void drain_stock(struct memcg_stock_pcp *stock)
+{
+	struct mem_cgroup *old = stock->cached;
+
+	if (stock->nr_pages) {
+		page_counter_uncharge(&old->memory, stock->nr_pages);
+		if (do_swap_account)
+			page_counter_uncharge(&old->memsw, stock->nr_pages);
+		css_put_many(&old->css, stock->nr_pages);
+		stock->nr_pages = 0;
+	}
+	stock->cached = NULL;
+}
+
+/*
+ * This must be called under preempt disabled or must be called by
+ * a thread which is pinned to local cpu.
+ */
+static void drain_local_stock(struct work_struct *dummy)
+{
+	struct memcg_stock_pcp *stock = this_cpu_ptr(&memcg_stock);
+	drain_stock(stock);
+	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
+}
+
+/*
+ * Cache charges(val) to local per_cpu area.
+ * This will be consumed by consume_stock() function, later.
+ */
+static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
+
+	if (stock->cached != memcg) { /* reset if necessary */
+		drain_stock(stock);
+		stock->cached = memcg;
+	}
+	stock->nr_pages += nr_pages;
+	put_cpu_var(memcg_stock);
+}
+
+/*
+ * Drains all per-CPU charge caches for given root_memcg resp. subtree
+ * of the hierarchy under it.
+ */
+static void drain_all_stock(struct mem_cgroup *root_memcg)
+{
+	int cpu, curcpu;
+
+	/* If someone's already draining, avoid adding running more workers. */
+	if (!mutex_trylock(&percpu_charge_mutex))
+		return;
+	/* Notify other cpus that system-wide "drain" is running */
+	get_online_cpus();
+	curcpu = get_cpu();
+	for_each_online_cpu(cpu) {
+		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
+		struct mem_cgroup *memcg;
+
+		memcg = stock->cached;
+		if (!memcg || !stock->nr_pages)
+			continue;
+		if (!mem_cgroup_is_descendant(memcg, root_memcg))
+			continue;
+		if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
+			if (cpu == curcpu)
+				drain_local_stock(&stock->work);
+			else
+				schedule_work_on(cpu, &stock->work);
+		}
+	}
+	put_cpu();
+	put_online_cpus();
+	mutex_unlock(&percpu_charge_mutex);
+}
+
+static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
+					unsigned long action,
+					void *hcpu)
+{
+	int cpu = (unsigned long)hcpu;
+	struct memcg_stock_pcp *stock;
+
+	if (action == CPU_ONLINE)
+		return NOTIFY_OK;
+
+	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
+		return NOTIFY_OK;
+
+	stock = &per_cpu(memcg_stock, cpu);
+	drain_stock(stock);
+	return NOTIFY_OK;
+}
+
+/*
+ * Scheduled by try_charge() to be executed from the userland return path
+ * and reclaims memory over the high limit.
+ */
+void mem_cgroup_handle_over_high(void)
+{
+	unsigned int nr_pages = current->memcg_nr_pages_over_high;
+	struct mem_cgroup *memcg, *pos;
+
+	if (likely(!nr_pages))
+		return;
+
+	pos = memcg = get_mem_cgroup_from_mm(current->mm);
+
+	do {
+		if (page_counter_read(&pos->memory) <= pos->high)
+			continue;
+		mem_cgroup_events(pos, MEMCG_HIGH, 1);
+		try_to_free_mem_cgroup_pages(pos, nr_pages, GFP_KERNEL, true);
+	} while ((pos = parent_mem_cgroup(pos)));
+
+	css_put(&memcg->css);
+	current->memcg_nr_pages_over_high = 0;
+}
+
+static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
+		      unsigned int nr_pages)
+{
+	unsigned int batch = max(CHARGE_BATCH, nr_pages);
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+	struct mem_cgroup *mem_over_limit;
+	struct page_counter *counter;
+	unsigned long nr_reclaimed;
+	bool may_swap = true;
+	bool drained = false;
+
+	if (mem_cgroup_is_root(memcg))
+		return 0;
+retry:
+	if (consume_stock(memcg, nr_pages))
+		return 0;
+
+	if (!do_swap_account ||
+	    page_counter_try_charge(&memcg->memsw, batch, &counter)) {
+		if (page_counter_try_charge(&memcg->memory, batch, &counter))
+			goto done_restock;
+		if (do_swap_account)
+			page_counter_uncharge(&memcg->memsw, batch);
+		mem_over_limit = mem_cgroup_from_counter(counter, memory);
+	} else {
+		mem_over_limit = mem_cgroup_from_counter(counter, memsw);
+		may_swap = false;
+	}
+
+	if (batch > nr_pages) {
+		batch = nr_pages;
+		goto retry;
+	}
+
+	/*
+	 * Unlike in global OOM situations, memcg is not in a physical
+	 * memory shortage.  Allow dying and OOM-killed tasks to
+	 * bypass the last charges so that they can exit quickly and
+	 * free their memory.
+	 */
+	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
+		     fatal_signal_pending(current) ||
+		     current->flags & PF_EXITING))
+		goto force;
+
+	/*
+	 * Prevent unbounded recursion when reclaim operations need to
+	 * allocate memory. This might exceed the limits temporarily,
+	 * but we prefer facilitating memory reclaim and getting back
+	 * under the limit over triggering OOM kills in these cases.
+	 */
+	if (unlikely(current->flags & PF_MEMALLOC))
+		goto force;
+
+	if (unlikely(task_in_memcg_oom(current)))
+		goto nomem;
+
+	if (!gfpflags_allow_blocking(gfp_mask))
+		goto nomem;
+
+	mem_cgroup_events(mem_over_limit, MEMCG_MAX, 1);
+
+	nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages,
+						    gfp_mask, may_swap);
+
+	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
+		goto retry;
+
+	if (!drained) {
+		drain_all_stock(mem_over_limit);
+		drained = true;
+		goto retry;
+	}
+
+	if (gfp_mask & __GFP_NORETRY)
+		goto nomem;
+	/*
+	 * Even though the limit is exceeded at this point, reclaim
+	 * may have been able to free some pages.  Retry the charge
+	 * before killing the task.
+	 *
+	 * Only for regular pages, though: huge pages are rather
+	 * unlikely to succeed so close to the limit, and we fall back
+	 * to regular pages anyway in case of failure.
+	 */
+	if (nr_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER))
+		goto retry;
+	/*
+	 * At task move, charge accounts can be doubly counted. So, it's
+	 * better to wait until the end of task_move if something is going on.
+	 */
+	if (mem_cgroup_wait_acct_move(mem_over_limit))
+		goto retry;
+
+	if (nr_retries--)
+		goto retry;
+
+	if (gfp_mask & __GFP_NOFAIL)
+		goto force;
+
+	if (fatal_signal_pending(current))
+		goto force;
+
+	mem_cgroup_events(mem_over_limit, MEMCG_OOM, 1);
+
+	mem_cgroup_oom(mem_over_limit, gfp_mask,
+		       get_order(nr_pages * PAGE_SIZE));
+nomem:
+	if (!(gfp_mask & __GFP_NOFAIL))
+		return -ENOMEM;
+force:
+	/*
+	 * The allocation either can't fail or will lead to more memory
+	 * being freed very soon.  Allow memory usage go over the limit
+	 * temporarily by force charging it.
+	 */
+	page_counter_charge(&memcg->memory, nr_pages);
+	if (do_swap_account)
+		page_counter_charge(&memcg->memsw, nr_pages);
+	css_get_many(&memcg->css, nr_pages);
+
+	return 0;
+
+done_restock:
+	css_get_many(&memcg->css, batch);
+	if (batch > nr_pages)
+		refill_stock(memcg, batch - nr_pages);
+
+	/*
+	 * If the hierarchy is above the normal consumption range, schedule
+	 * reclaim on returning to userland.  We can perform reclaim here
+	 * if __GFP_RECLAIM but let's always punt for simplicity and so that
+	 * GFP_KERNEL can consistently be used during reclaim.  @memcg is
+	 * not recorded as it most likely matches current's and won't
+	 * change in the meantime.  As high limit is checked again before
+	 * reclaim, the cost of mismatch is negligible.
+	 */
+	do {
+		if (page_counter_read(&memcg->memory) > memcg->high) {
+			current->memcg_nr_pages_over_high += batch;
+			set_notify_resume(current);
+			break;
+		}
+	} while ((memcg = parent_mem_cgroup(memcg)));
+
+	return 0;
+}
+
+static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	if (mem_cgroup_is_root(memcg))
+		return;
+
+	page_counter_uncharge(&memcg->memory, nr_pages);
+	if (do_swap_account)
+		page_counter_uncharge(&memcg->memsw, nr_pages);
+
+	css_put_many(&memcg->css, nr_pages);
+}
+
+static void lock_page_lru(struct page *page, int *isolated)
+{
+	struct zone *zone = page_zone(page);
+
+	spin_lock_irq(&zone->lru_lock);
+	if (PageLRU(page)) {
+		struct lruvec *lruvec;
+
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+		ClearPageLRU(page);
+		del_page_from_lru_list(page, lruvec, page_lru(page));
+		*isolated = 1;
+	} else
+		*isolated = 0;
+}
+
+static void unlock_page_lru(struct page *page, int isolated)
+{
+	struct zone *zone = page_zone(page);
+
+	if (isolated) {
+		struct lruvec *lruvec;
+
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+		VM_BUG_ON_PAGE(PageLRU(page), page);
+		SetPageLRU(page);
+		add_page_to_lru_list(page, lruvec, page_lru(page));
+	}
+	spin_unlock_irq(&zone->lru_lock);
+}
+
+static void commit_charge(struct page *page, struct mem_cgroup *memcg,
+			  bool lrucare)
+{
+	int isolated;
+
+	VM_BUG_ON_PAGE(page->mem_cgroup, page);
+
+	/*
+	 * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
+	 * may already be on some other mem_cgroup's LRU.  Take care of it.
+	 */
+	if (lrucare)
+		lock_page_lru(page, &isolated);
+
+	/*
+	 * Nobody should be changing or seriously looking at
+	 * page->mem_cgroup at this point:
+	 *
+	 * - the page is uncharged
+	 *
+	 * - the page is off-LRU
+	 *
+	 * - an anonymous fault has exclusive page access, except for
+	 *   a locked page table
+	 *
+	 * - a page cache insertion, a swapin fault, or a migration
+	 *   have the page locked
+	 */
+	page->mem_cgroup = memcg;
+
+	if (lrucare)
+		unlock_page_lru(page, isolated);
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+static int memcg_alloc_cache_id(void)
+{
+	int id, size;
+	int err;
+
+	id = ida_simple_get(&memcg_cache_ida,
+			    0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	if (id < memcg_nr_cache_ids)
+		return id;
+
+	/*
+	 * There's no space for the new id in memcg_caches arrays,
+	 * so we have to grow them.
+	 */
+	down_write(&memcg_cache_ids_sem);
+
+	size = 2 * (id + 1);
+	if (size < MEMCG_CACHES_MIN_SIZE)
+		size = MEMCG_CACHES_MIN_SIZE;
+	else if (size > MEMCG_CACHES_MAX_SIZE)
+		size = MEMCG_CACHES_MAX_SIZE;
+
+	err = memcg_update_all_caches(size);
+	if (!err)
+		err = memcg_update_all_list_lrus(size);
+	if (!err)
+		memcg_nr_cache_ids = size;
+
+	up_write(&memcg_cache_ids_sem);
+
+	if (err) {
+		ida_simple_remove(&memcg_cache_ida, id);
+		return err;
+	}
+	return id;
+}
+
+static void memcg_free_cache_id(int id)
+{
+	ida_simple_remove(&memcg_cache_ida, id);
+}
+
+struct memcg_kmem_cache_create_work {
+	struct mem_cgroup *memcg;
+	struct kmem_cache *cachep;
+	struct work_struct work;
+};
+
+static void memcg_kmem_cache_create_func(struct work_struct *w)
+{
+	struct memcg_kmem_cache_create_work *cw =
+		container_of(w, struct memcg_kmem_cache_create_work, work);
+	struct mem_cgroup *memcg = cw->memcg;
+	struct kmem_cache *cachep = cw->cachep;
+
+	memcg_create_kmem_cache(memcg, cachep);
+
+	css_put(&memcg->css);
+	kfree(cw);
+}
+
+/*
+ * Enqueue the creation of a per-memcg kmem_cache.
+ */
+static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
+					       struct kmem_cache *cachep)
+{
+	struct memcg_kmem_cache_create_work *cw;
+
+	cw = kmalloc(sizeof(*cw), GFP_NOWAIT);
+	if (!cw)
+		return;
+
+	css_get(&memcg->css);
+
+	cw->memcg = memcg;
+	cw->cachep = cachep;
+	INIT_WORK(&cw->work, memcg_kmem_cache_create_func);
+
+	schedule_work(&cw->work);
+}
+
+static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
+					     struct kmem_cache *cachep)
+{
+	/*
+	 * We need to stop accounting when we kmalloc, because if the
+	 * corresponding kmalloc cache is not yet created, the first allocation
+	 * in __memcg_schedule_kmem_cache_create will recurse.
+	 *
+	 * However, it is better to enclose the whole function. Depending on
+	 * the debugging options enabled, INIT_WORK(), for instance, can
+	 * trigger an allocation. This too, will make us recurse. Because at
+	 * this point we can't allow ourselves back into memcg_kmem_get_cache,
+	 * the safest choice is to do it like this, wrapping the whole function.
+	 */
+	current->memcg_kmem_skip_account = 1;
+	__memcg_schedule_kmem_cache_create(memcg, cachep);
+	current->memcg_kmem_skip_account = 0;
+}
+
+/*
+ * Return the kmem_cache we're supposed to use for a slab allocation.
+ * We try to use the current memcg's version of the cache.
+ *
+ * If the cache does not exist yet, if we are the first user of it,
+ * we either create it immediately, if possible, or create it asynchronously
+ * in a workqueue.
+ * In the latter case, we will let the current allocation go through with
+ * the original cache.
+ *
+ * Can't be called in interrupt context or from kernel threads.
+ * This function needs to be called with rcu_read_lock() held.
+ */
+struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep)
+{
+	struct mem_cgroup *memcg;
+	struct kmem_cache *memcg_cachep;
+	int kmemcg_id;
+
+	VM_BUG_ON(!is_root_cache(cachep));
+
+	if (current->memcg_kmem_skip_account)
+		return cachep;
+
+	memcg = get_mem_cgroup_from_mm(current->mm);
+	kmemcg_id = READ_ONCE(memcg->kmemcg_id);
+	if (kmemcg_id < 0)
+		goto out;
+
+	memcg_cachep = cache_from_memcg_idx(cachep, kmemcg_id);
+	if (likely(memcg_cachep))
+		return memcg_cachep;
+
+	/*
+	 * If we are in a safe context (can wait, and not in interrupt
+	 * context), we could be be predictable and return right away.
+	 * This would guarantee that the allocation being performed
+	 * already belongs in the new cache.
+	 *
+	 * However, there are some clashes that can arrive from locking.
+	 * For instance, because we acquire the slab_mutex while doing
+	 * memcg_create_kmem_cache, this means no further allocation
+	 * could happen with the slab_mutex held. So it's better to
+	 * defer everything.
+	 */
+	memcg_schedule_kmem_cache_create(memcg, cachep);
+out:
+	css_put(&memcg->css);
+	return cachep;
+}
+
+void __memcg_kmem_put_cache(struct kmem_cache *cachep)
+{
+	if (!is_root_cache(cachep))
+		css_put(&cachep->memcg_params.memcg->css);
+}
+
+int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
+			      struct mem_cgroup *memcg)
+{
+	unsigned int nr_pages = 1 << order;
+	struct page_counter *counter;
+	int ret;
+
+	if (!memcg_kmem_is_active(memcg))
+		return 0;
+
+	if (!page_counter_try_charge(&memcg->kmem, nr_pages, &counter))
+		return -ENOMEM;
+
+	ret = try_charge(memcg, gfp, nr_pages);
+	if (ret) {
+		page_counter_uncharge(&memcg->kmem, nr_pages);
+		return ret;
+	}
+
+	page->mem_cgroup = memcg;
+
+	return 0;
+}
+
+int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
+{
+	struct mem_cgroup *memcg;
+	int ret;
+
+	memcg = get_mem_cgroup_from_mm(current->mm);
+	ret = __memcg_kmem_charge_memcg(page, gfp, order, memcg);
+	css_put(&memcg->css);
+	return ret;
+}
+
+void __memcg_kmem_uncharge(struct page *page, int order)
+{
+	struct mem_cgroup *memcg = page->mem_cgroup;
+	unsigned int nr_pages = 1 << order;
+
+	if (!memcg)
+		return;
+
+	VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
+
+	page_counter_uncharge(&memcg->kmem, nr_pages);
+	page_counter_uncharge(&memcg->memory, nr_pages);
+	if (do_swap_account)
+		page_counter_uncharge(&memcg->memsw, nr_pages);
+
+	page->mem_cgroup = NULL;
+	css_put_many(&memcg->css, nr_pages);
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+/*
+ * Because tail pages are not marked as "used", set it. We're under
+ * zone->lru_lock, 'splitting on pmd' and compound_lock.
+ * charge/uncharge will be never happen and move_account() is done under
+ * compound_lock(), so we don't have to take care of races.
+ */
+void mem_cgroup_split_huge_fixup(struct page *head)
+{
+	int i;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	for (i = 1; i < HPAGE_PMD_NR; i++)
+		head[i].mem_cgroup = head->mem_cgroup;
+
+	__this_cpu_sub(head->mem_cgroup->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
+		       HPAGE_PMD_NR);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+#ifdef CONFIG_MEMCG_SWAP
+static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
+					 bool charge)
+{
+	int val = (charge) ? 1 : -1;
+	this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val);
+}
+
+/**
+ * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
+ * @entry: swap entry to be moved
+ * @from:  mem_cgroup which the entry is moved from
+ * @to:  mem_cgroup which the entry is moved to
+ *
+ * It succeeds only when the swap_cgroup's record for this entry is the same
+ * as the mem_cgroup's id of @from.
+ *
+ * Returns 0 on success, -EINVAL on failure.
+ *
+ * The caller must have charged to @to, IOW, called page_counter_charge() about
+ * both res and memsw, and called css_get().
+ */
+static int mem_cgroup_move_swap_account(swp_entry_t entry,
+				struct mem_cgroup *from, struct mem_cgroup *to)
+{
+	unsigned short old_id, new_id;
+
+	old_id = mem_cgroup_id(from);
+	new_id = mem_cgroup_id(to);
+
+	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
+		mem_cgroup_swap_statistics(from, false);
+		mem_cgroup_swap_statistics(to, true);
+		return 0;
+	}
+	return -EINVAL;
+}
+#else
+static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
+				struct mem_cgroup *from, struct mem_cgroup *to)
+{
+	return -EINVAL;
+}
+#endif
+
+static DEFINE_MUTEX(memcg_limit_mutex);
+
+static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
+				   unsigned long limit)
+{
+	unsigned long curusage;
+	unsigned long oldusage;
+	bool enlarge = false;
+	int retry_count;
+	int ret;
+
+	/*
+	 * For keeping hierarchical_reclaim simple, how long we should retry
+	 * is depends on callers. We set our retry-count to be function
+	 * of # of children which we should visit in this loop.
+	 */
+	retry_count = MEM_CGROUP_RECLAIM_RETRIES *
+		      mem_cgroup_count_children(memcg);
+
+	oldusage = page_counter_read(&memcg->memory);
+
+	do {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+
+		mutex_lock(&memcg_limit_mutex);
+		if (limit > memcg->memsw.limit) {
+			mutex_unlock(&memcg_limit_mutex);
+			ret = -EINVAL;
+			break;
+		}
+		if (limit > memcg->memory.limit)
+			enlarge = true;
+		ret = page_counter_limit(&memcg->memory, limit);
+		mutex_unlock(&memcg_limit_mutex);
+
+		if (!ret)
+			break;
+
+		try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true);
+
+		curusage = page_counter_read(&memcg->memory);
+		/* Usage is reduced ? */
+		if (curusage >= oldusage)
+			retry_count--;
+		else
+			oldusage = curusage;
+	} while (retry_count);
+
+	if (!ret && enlarge)
+		memcg_oom_recover(memcg);
+
+	return ret;
+}
+
+static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
+					 unsigned long limit)
+{
+	unsigned long curusage;
+	unsigned long oldusage;
+	bool enlarge = false;
+	int retry_count;
+	int ret;
+
+	/* see mem_cgroup_resize_res_limit */
+	retry_count = MEM_CGROUP_RECLAIM_RETRIES *
+		      mem_cgroup_count_children(memcg);
+
+	oldusage = page_counter_read(&memcg->memsw);
+
+	do {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+
+		mutex_lock(&memcg_limit_mutex);
+		if (limit < memcg->memory.limit) {
+			mutex_unlock(&memcg_limit_mutex);
+			ret = -EINVAL;
+			break;
+		}
+		if (limit > memcg->memsw.limit)
+			enlarge = true;
+		ret = page_counter_limit(&memcg->memsw, limit);
+		mutex_unlock(&memcg_limit_mutex);
+
+		if (!ret)
+			break;
+
+		try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, false);
+
+		curusage = page_counter_read(&memcg->memsw);
+		/* Usage is reduced ? */
+		if (curusage >= oldusage)
+			retry_count--;
+		else
+			oldusage = curusage;
+	} while (retry_count);
+
+	if (!ret && enlarge)
+		memcg_oom_recover(memcg);
+
+	return ret;
+}
+
+unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
+					    gfp_t gfp_mask,
+					    unsigned long *total_scanned)
+{
+	unsigned long nr_reclaimed = 0;
+	struct mem_cgroup_per_zone *mz, *next_mz = NULL;
+	unsigned long reclaimed;
+	int loop = 0;
+	struct mem_cgroup_tree_per_zone *mctz;
+	unsigned long excess;
+	unsigned long nr_scanned;
+
+	if (order > 0)
+		return 0;
+
+	mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
+	/*
+	 * This loop can run a while, specially if mem_cgroup's continuously
+	 * keep exceeding their soft limit and putting the system under
+	 * pressure
+	 */
+	do {
+		if (next_mz)
+			mz = next_mz;
+		else
+			mz = mem_cgroup_largest_soft_limit_node(mctz);
+		if (!mz)
+			break;
+
+		nr_scanned = 0;
+		reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone,
+						    gfp_mask, &nr_scanned);
+		nr_reclaimed += reclaimed;
+		*total_scanned += nr_scanned;
+		spin_lock_irq(&mctz->lock);
+		__mem_cgroup_remove_exceeded(mz, mctz);
+
+		/*
+		 * If we failed to reclaim anything from this memory cgroup
+		 * it is time to move on to the next cgroup
+		 */
+		next_mz = NULL;
+		if (!reclaimed)
+			next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
+
+		excess = soft_limit_excess(mz->memcg);
+		/*
+		 * One school of thought says that we should not add
+		 * back the node to the tree if reclaim returns 0.
+		 * But our reclaim could return 0, simply because due
+		 * to priority we are exposing a smaller subset of
+		 * memory to reclaim from. Consider this as a longer
+		 * term TODO.
+		 */
+		/* If excess == 0, no tree ops */
+		__mem_cgroup_insert_exceeded(mz, mctz, excess);
+		spin_unlock_irq(&mctz->lock);
+		css_put(&mz->memcg->css);
+		loop++;
+		/*
+		 * Could not reclaim anything and there are no more
+		 * mem cgroups to try or we seem to be looping without
+		 * reclaiming anything.
+		 */
+		if (!nr_reclaimed &&
+			(next_mz == NULL ||
+			loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
+			break;
+	} while (!nr_reclaimed);
+	if (next_mz)
+		css_put(&next_mz->memcg->css);
+	return nr_reclaimed;
+}
+
+/*
+ * Test whether @memcg has children, dead or alive.  Note that this
+ * function doesn't care whether @memcg has use_hierarchy enabled and
+ * returns %true if there are child csses according to the cgroup
+ * hierarchy.  Testing use_hierarchy is the caller's responsiblity.
+ */
+static inline bool memcg_has_children(struct mem_cgroup *memcg)
+{
+	bool ret;
+
+	/*
+	 * The lock does not prevent addition or deletion of children, but
+	 * it prevents a new child from being initialized based on this
+	 * parent in css_online(), so it's enough to decide whether
+	 * hierarchically inherited attributes can still be changed or not.
+	 */
+	lockdep_assert_held(&memcg_create_mutex);
+
+	rcu_read_lock();
+	ret = css_next_child(NULL, &memcg->css);
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Reclaims as many pages from the given memcg as possible and moves
+ * the rest to the parent.
+ *
+ * Caller is responsible for holding css reference for memcg.
+ */
+static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
+{
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+
+	/* we call try-to-free pages for make this cgroup empty */
+	lru_add_drain_all();
+	/* try to free all pages in this cgroup */
+	while (nr_retries && page_counter_read(&memcg->memory)) {
+		int progress;
+
+		if (signal_pending(current))
+			return -EINTR;
+
+		progress = try_to_free_mem_cgroup_pages(memcg, 1,
+							GFP_KERNEL, true);
+		if (!progress) {
+			nr_retries--;
+			/* maybe some writeback is necessary */
+			congestion_wait(BLK_RW_ASYNC, HZ/10);
+		}
+
+	}
+
+	return 0;
+}
+
+static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
+					    char *buf, size_t nbytes,
+					    loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+
+	if (mem_cgroup_is_root(memcg))
+		return -EINVAL;
+	return mem_cgroup_force_empty(memcg) ?: nbytes;
+}
+
+static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
+				     struct cftype *cft)
+{
+	return mem_cgroup_from_css(css)->use_hierarchy;
+}
+
+static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
+				      struct cftype *cft, u64 val)
+{
+	int retval = 0;
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup *parent_memcg = mem_cgroup_from_css(memcg->css.parent);
+
+	mutex_lock(&memcg_create_mutex);
+
+	if (memcg->use_hierarchy == val)
+		goto out;
+
+	/*
+	 * If parent's use_hierarchy is set, we can't make any modifications
+	 * in the child subtrees. If it is unset, then the change can
+	 * occur, provided the current cgroup has no children.
+	 *
+	 * For the root cgroup, parent_mem is NULL, we allow value to be
+	 * set if there are no children.
+	 */
+	if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
+				(val == 1 || val == 0)) {
+		if (!memcg_has_children(memcg))
+			memcg->use_hierarchy = val;
+		else
+			retval = -EBUSY;
+	} else
+		retval = -EINVAL;
+
+out:
+	mutex_unlock(&memcg_create_mutex);
+
+	return retval;
+}
+
+static unsigned long tree_stat(struct mem_cgroup *memcg,
+			       enum mem_cgroup_stat_index idx)
+{
+	struct mem_cgroup *iter;
+	unsigned long val = 0;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		val += mem_cgroup_read_stat(iter, idx);
+
+	return val;
+}
+
+static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
+{
+	unsigned long val;
+
+	if (mem_cgroup_is_root(memcg)) {
+		val = tree_stat(memcg, MEM_CGROUP_STAT_CACHE);
+		val += tree_stat(memcg, MEM_CGROUP_STAT_RSS);
+		if (swap)
+			val += tree_stat(memcg, MEM_CGROUP_STAT_SWAP);
+	} else {
+		if (!swap)
+			val = page_counter_read(&memcg->memory);
+		else
+			val = page_counter_read(&memcg->memsw);
+	}
+	return val;
+}
+
+enum {
+	RES_USAGE,
+	RES_LIMIT,
+	RES_MAX_USAGE,
+	RES_FAILCNT,
+	RES_SOFT_LIMIT,
+};
+
+static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct page_counter *counter;
+
+	switch (MEMFILE_TYPE(cft->private)) {
+	case _MEM:
+		counter = &memcg->memory;
+		break;
+	case _MEMSWAP:
+		counter = &memcg->memsw;
+		break;
+	case _KMEM:
+		counter = &memcg->kmem;
+		break;
+	default:
+		BUG();
+	}
+
+	switch (MEMFILE_ATTR(cft->private)) {
+	case RES_USAGE:
+		if (counter == &memcg->memory)
+			return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE;
+		if (counter == &memcg->memsw)
+			return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
+		return (u64)page_counter_read(counter) * PAGE_SIZE;
+	case RES_LIMIT:
+		return (u64)counter->limit * PAGE_SIZE;
+	case RES_MAX_USAGE:
+		return (u64)counter->watermark * PAGE_SIZE;
+	case RES_FAILCNT:
+		return counter->failcnt;
+	case RES_SOFT_LIMIT:
+		return (u64)memcg->soft_limit * PAGE_SIZE;
+	default:
+		BUG();
+	}
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+static int memcg_activate_kmem(struct mem_cgroup *memcg,
+			       unsigned long nr_pages)
+{
+	int err = 0;
+	int memcg_id;
+
+	BUG_ON(memcg->kmemcg_id >= 0);
+	BUG_ON(memcg->kmem_acct_activated);
+	BUG_ON(memcg->kmem_acct_active);
+
+	/*
+	 * For simplicity, we won't allow this to be disabled.  It also can't
+	 * be changed if the cgroup has children already, or if tasks had
+	 * already joined.
+	 *
+	 * If tasks join before we set the limit, a person looking at
+	 * kmem.usage_in_bytes will have no way to determine when it took
+	 * place, which makes the value quite meaningless.
+	 *
+	 * After it first became limited, changes in the value of the limit are
+	 * of course permitted.
+	 */
+	mutex_lock(&memcg_create_mutex);
+	if (cgroup_is_populated(memcg->css.cgroup) ||
+	    (memcg->use_hierarchy && memcg_has_children(memcg)))
+		err = -EBUSY;
+	mutex_unlock(&memcg_create_mutex);
+	if (err)
+		goto out;
+
+	memcg_id = memcg_alloc_cache_id();
+	if (memcg_id < 0) {
+		err = memcg_id;
+		goto out;
+	}
+
+	/*
+	 * We couldn't have accounted to this cgroup, because it hasn't got
+	 * activated yet, so this should succeed.
+	 */
+	err = page_counter_limit(&memcg->kmem, nr_pages);
+	VM_BUG_ON(err);
+
+	static_key_slow_inc(&memcg_kmem_enabled_key);
+	/*
+	 * A memory cgroup is considered kmem-active as soon as it gets
+	 * kmemcg_id. Setting the id after enabling static branching will
+	 * guarantee no one starts accounting before all call sites are
+	 * patched.
+	 */
+	memcg->kmemcg_id = memcg_id;
+	memcg->kmem_acct_activated = true;
+	memcg->kmem_acct_active = true;
+out:
+	return err;
+}
+
+static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
+				   unsigned long limit)
+{
+	int ret;
+
+	mutex_lock(&memcg_limit_mutex);
+	if (!memcg_kmem_is_active(memcg))
+		ret = memcg_activate_kmem(memcg, limit);
+	else
+		ret = page_counter_limit(&memcg->kmem, limit);
+	mutex_unlock(&memcg_limit_mutex);
+	return ret;
+}
+
+static int memcg_propagate_kmem(struct mem_cgroup *memcg)
+{
+	int ret = 0;
+	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
+
+	if (!parent)
+		return 0;
+
+	mutex_lock(&memcg_limit_mutex);
+	/*
+	 * If the parent cgroup is not kmem-active now, it cannot be activated
+	 * after this point, because it has at least one child already.
+	 */
+	if (memcg_kmem_is_active(parent))
+		ret = memcg_activate_kmem(memcg, PAGE_COUNTER_MAX);
+	mutex_unlock(&memcg_limit_mutex);
+	return ret;
+}
+#else
+static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
+				   unsigned long limit)
+{
+	return -EINVAL;
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+/*
+ * The user of this function is...
+ * RES_LIMIT.
+ */
+static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long nr_pages;
+	int ret;
+
+	buf = strstrip(buf);
+	ret = page_counter_memparse(buf, "-1", &nr_pages);
+	if (ret)
+		return ret;
+
+	switch (MEMFILE_ATTR(of_cft(of)->private)) {
+	case RES_LIMIT:
+		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
+			ret = -EINVAL;
+			break;
+		}
+		switch (MEMFILE_TYPE(of_cft(of)->private)) {
+		case _MEM:
+			ret = mem_cgroup_resize_limit(memcg, nr_pages);
+			break;
+		case _MEMSWAP:
+			ret = mem_cgroup_resize_memsw_limit(memcg, nr_pages);
+			break;
+		case _KMEM:
+			ret = memcg_update_kmem_limit(memcg, nr_pages);
+			break;
+		}
+		break;
+	case RES_SOFT_LIMIT:
+		memcg->soft_limit = nr_pages;
+		ret = 0;
+		break;
+	}
+	return ret ?: nbytes;
+}
+
+static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
+				size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	struct page_counter *counter;
+
+	switch (MEMFILE_TYPE(of_cft(of)->private)) {
+	case _MEM:
+		counter = &memcg->memory;
+		break;
+	case _MEMSWAP:
+		counter = &memcg->memsw;
+		break;
+	case _KMEM:
+		counter = &memcg->kmem;
+		break;
+	default:
+		BUG();
+	}
+
+	switch (MEMFILE_ATTR(of_cft(of)->private)) {
+	case RES_MAX_USAGE:
+		page_counter_reset_watermark(counter);
+		break;
+	case RES_FAILCNT:
+		counter->failcnt = 0;
+		break;
+	default:
+		BUG();
+	}
+
+	return nbytes;
+}
+
+static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
+					struct cftype *cft)
+{
+	return mem_cgroup_from_css(css)->move_charge_at_immigrate;
+}
+
+#ifdef CONFIG_MMU
+static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+					struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	if (val & ~MOVE_MASK)
+		return -EINVAL;
+
+	/*
+	 * No kind of locking is needed in here, because ->can_attach() will
+	 * check this value once in the beginning of the process, and then carry
+	 * on with stale data. This means that changes to this value will only
+	 * affect task migrations starting after the change.
+	 */
+	memcg->move_charge_at_immigrate = val;
+	return 0;
+}
+#else
+static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+					struct cftype *cft, u64 val)
+{
+	return -ENOSYS;
+}
+#endif
+
+#ifdef CONFIG_NUMA
+static int memcg_numa_stat_show(struct seq_file *m, void *v)
+{
+	struct numa_stat {
+		const char *name;
+		unsigned int lru_mask;
+	};
+
+	static const struct numa_stat stats[] = {
+		{ "total", LRU_ALL },
+		{ "file", LRU_ALL_FILE },
+		{ "anon", LRU_ALL_ANON },
+		{ "unevictable", BIT(LRU_UNEVICTABLE) },
+	};
+	const struct numa_stat *stat;
+	int nid;
+	unsigned long nr;
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
+		nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask);
+		seq_printf(m, "%s=%lu", stat->name, nr);
+		for_each_node_state(nid, N_MEMORY) {
+			nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
+							  stat->lru_mask);
+			seq_printf(m, " N%d=%lu", nid, nr);
+		}
+		seq_putc(m, '\n');
+	}
+
+	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
+		struct mem_cgroup *iter;
+
+		nr = 0;
+		for_each_mem_cgroup_tree(iter, memcg)
+			nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask);
+		seq_printf(m, "hierarchical_%s=%lu", stat->name, nr);
+		for_each_node_state(nid, N_MEMORY) {
+			nr = 0;
+			for_each_mem_cgroup_tree(iter, memcg)
+				nr += mem_cgroup_node_nr_lru_pages(
+					iter, nid, stat->lru_mask);
+			seq_printf(m, " N%d=%lu", nid, nr);
+		}
+		seq_putc(m, '\n');
+	}
+
+	return 0;
+}
+#endif /* CONFIG_NUMA */
+
+static int memcg_stat_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long memory, memsw;
+	struct mem_cgroup *mi;
+	unsigned int i;
+
+	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_stat_names) !=
+		     MEM_CGROUP_STAT_NSTATS);
+	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_events_names) !=
+		     MEM_CGROUP_EVENTS_NSTATS);
+	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
+
+	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
+		if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
+			continue;
+		seq_printf(m, "%s %lu\n", mem_cgroup_stat_names[i],
+			   mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
+	}
+
+	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++)
+		seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i],
+			   mem_cgroup_read_events(memcg, i));
+
+	for (i = 0; i < NR_LRU_LISTS; i++)
+		seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i],
+			   mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);
+
+	/* Hierarchical information */
+	memory = memsw = PAGE_COUNTER_MAX;
+	for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
+		memory = min(memory, mi->memory.limit);
+		memsw = min(memsw, mi->memsw.limit);
+	}
+	seq_printf(m, "hierarchical_memory_limit %llu\n",
+		   (u64)memory * PAGE_SIZE);
+	if (do_swap_account)
+		seq_printf(m, "hierarchical_memsw_limit %llu\n",
+			   (u64)memsw * PAGE_SIZE);
+
+	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
+		unsigned long long val = 0;
+
+		if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
+			continue;
+		for_each_mem_cgroup_tree(mi, memcg)
+			val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE;
+		seq_printf(m, "total_%s %llu\n", mem_cgroup_stat_names[i], val);
+	}
+
+	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
+		unsigned long long val = 0;
+
+		for_each_mem_cgroup_tree(mi, memcg)
+			val += mem_cgroup_read_events(mi, i);
+		seq_printf(m, "total_%s %llu\n",
+			   mem_cgroup_events_names[i], val);
+	}
+
+	for (i = 0; i < NR_LRU_LISTS; i++) {
+		unsigned long long val = 0;
+
+		for_each_mem_cgroup_tree(mi, memcg)
+			val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE;
+		seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val);
+	}
+
+#ifdef CONFIG_DEBUG_VM
+	{
+		int nid, zid;
+		struct mem_cgroup_per_zone *mz;
+		struct zone_reclaim_stat *rstat;
+		unsigned long recent_rotated[2] = {0, 0};
+		unsigned long recent_scanned[2] = {0, 0};
+
+		for_each_online_node(nid)
+			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+				mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
+				rstat = &mz->lruvec.reclaim_stat;
+
+				recent_rotated[0] += rstat->recent_rotated[0];
+				recent_rotated[1] += rstat->recent_rotated[1];
+				recent_scanned[0] += rstat->recent_scanned[0];
+				recent_scanned[1] += rstat->recent_scanned[1];
+			}
+		seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]);
+		seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]);
+		seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]);
+		seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]);
+	}
+#endif
+
+	return 0;
+}
+
+static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
+				      struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	return mem_cgroup_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
+				       struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	if (val > 100)
+		return -EINVAL;
+
+	if (css->parent)
+		memcg->swappiness = val;
+	else
+		vm_swappiness = val;
+
+	return 0;
+}
+
+static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
+{
+	struct mem_cgroup_threshold_ary *t;
+	unsigned long usage;
+	int i;
+
+	rcu_read_lock();
+	if (!swap)
+		t = rcu_dereference(memcg->thresholds.primary);
+	else
+		t = rcu_dereference(memcg->memsw_thresholds.primary);
+
+	if (!t)
+		goto unlock;
+
+	usage = mem_cgroup_usage(memcg, swap);
+
+	/*
+	 * current_threshold points to threshold just below or equal to usage.
+	 * If it's not true, a threshold was crossed after last
+	 * call of __mem_cgroup_threshold().
+	 */
+	i = t->current_threshold;
+
+	/*
+	 * Iterate backward over array of thresholds starting from
+	 * current_threshold and check if a threshold is crossed.
+	 * If none of thresholds below usage is crossed, we read
+	 * only one element of the array here.
+	 */
+	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
+		eventfd_signal(t->entries[i].eventfd, 1);
+
+	/* i = current_threshold + 1 */
+	i++;
+
+	/*
+	 * Iterate forward over array of thresholds starting from
+	 * current_threshold+1 and check if a threshold is crossed.
+	 * If none of thresholds above usage is crossed, we read
+	 * only one element of the array here.
+	 */
+	for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
+		eventfd_signal(t->entries[i].eventfd, 1);
+
+	/* Update current_threshold */
+	t->current_threshold = i - 1;
+unlock:
+	rcu_read_unlock();
+}
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg)
+{
+	while (memcg) {
+		__mem_cgroup_threshold(memcg, false);
+		if (do_swap_account)
+			__mem_cgroup_threshold(memcg, true);
+
+		memcg = parent_mem_cgroup(memcg);
+	}
+}
+
+static int compare_thresholds(const void *a, const void *b)
+{
+	const struct mem_cgroup_threshold *_a = a;
+	const struct mem_cgroup_threshold *_b = b;
+
+	if (_a->threshold > _b->threshold)
+		return 1;
+
+	if (_a->threshold < _b->threshold)
+		return -1;
+
+	return 0;
+}
+
+static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_eventfd_list *ev;
+
+	spin_lock(&memcg_oom_lock);
+
+	list_for_each_entry(ev, &memcg->oom_notify, list)
+		eventfd_signal(ev->eventfd, 1);
+
+	spin_unlock(&memcg_oom_lock);
+	return 0;
+}
+
+static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		mem_cgroup_oom_notify_cb(iter);
+}
+
+static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
+{
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	unsigned long threshold;
+	unsigned long usage;
+	int i, size, ret;
+
+	ret = page_counter_memparse(args, "-1", &threshold);
+	if (ret)
+		return ret;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM) {
+		thresholds = &memcg->thresholds;
+		usage = mem_cgroup_usage(memcg, false);
+	} else if (type == _MEMSWAP) {
+		thresholds = &memcg->memsw_thresholds;
+		usage = mem_cgroup_usage(memcg, true);
+	} else
+		BUG();
+
+	/* Check if a threshold crossed before adding a new one */
+	if (thresholds->primary)
+		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
+
+	/* Allocate memory for new array of thresholds */
+	new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
+			GFP_KERNEL);
+	if (!new) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+	new->size = size;
+
+	/* Copy thresholds (if any) to new array */
+	if (thresholds->primary) {
+		memcpy(new->entries, thresholds->primary->entries, (size - 1) *
+				sizeof(struct mem_cgroup_threshold));
+	}
+
+	/* Add new threshold */
+	new->entries[size - 1].eventfd = eventfd;
+	new->entries[size - 1].threshold = threshold;
+
+	/* Sort thresholds. Registering of new threshold isn't time-critical */
+	sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
+			compare_thresholds, NULL);
+
+	/* Find current threshold */
+	new->current_threshold = -1;
+	for (i = 0; i < size; i++) {
+		if (new->entries[i].threshold <= usage) {
+			/*
+			 * new->current_threshold will not be used until
+			 * rcu_assign_pointer(), so it's safe to increment
+			 * it here.
+			 */
+			++new->current_threshold;
+		} else
+			break;
+	}
+
+	/* Free old spare buffer and save old primary buffer as spare */
+	kfree(thresholds->spare);
+	thresholds->spare = thresholds->primary;
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+
+	return ret;
+}
+
+static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
+}
+
+static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
+}
+
+static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, enum res_type type)
+{
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	unsigned long usage;
+	int i, j, size;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM) {
+		thresholds = &memcg->thresholds;
+		usage = mem_cgroup_usage(memcg, false);
+	} else if (type == _MEMSWAP) {
+		thresholds = &memcg->memsw_thresholds;
+		usage = mem_cgroup_usage(memcg, true);
+	} else
+		BUG();
+
+	if (!thresholds->primary)
+		goto unlock;
+
+	/* Check if a threshold crossed before removing */
+	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	/* Calculate new number of threshold */
+	size = 0;
+	for (i = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd != eventfd)
+			size++;
+	}
+
+	new = thresholds->spare;
+
+	/* Set thresholds array to NULL if we don't have thresholds */
+	if (!size) {
+		kfree(new);
+		new = NULL;
+		goto swap_buffers;
+	}
+
+	new->size = size;
+
+	/* Copy thresholds and find current threshold */
+	new->current_threshold = -1;
+	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd == eventfd)
+			continue;
+
+		new->entries[j] = thresholds->primary->entries[i];
+		if (new->entries[j].threshold <= usage) {
+			/*
+			 * new->current_threshold will not be used
+			 * until rcu_assign_pointer(), so it's safe to increment
+			 * it here.
+			 */
+			++new->current_threshold;
+		}
+		j++;
+	}
+
+swap_buffers:
+	/* Swap primary and spare array */
+	thresholds->spare = thresholds->primary;
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+
+	/* If all events are unregistered, free the spare array */
+	if (!new) {
+		kfree(thresholds->spare);
+		thresholds->spare = NULL;
+	}
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+}
+
+static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
+}
+
+static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
+}
+
+static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	struct mem_cgroup_eventfd_list *event;
+
+	event = kmalloc(sizeof(*event),	GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	spin_lock(&memcg_oom_lock);
+
+	event->eventfd = eventfd;
+	list_add(&event->list, &memcg->oom_notify);
+
+	/* already in OOM ? */
+	if (memcg->under_oom)
+		eventfd_signal(eventfd, 1);
+	spin_unlock(&memcg_oom_lock);
+
+	return 0;
+}
+
+static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	struct mem_cgroup_eventfd_list *ev, *tmp;
+
+	spin_lock(&memcg_oom_lock);
+
+	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
+		if (ev->eventfd == eventfd) {
+			list_del(&ev->list);
+			kfree(ev);
+		}
+	}
+
+	spin_unlock(&memcg_oom_lock);
+}
+
+static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf));
+
+	seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
+	seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
+	return 0;
+}
+
+static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
+	struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	/* cannot set to root cgroup and only 0 and 1 are allowed */
+	if (!css->parent || !((val == 0) || (val == 1)))
+		return -EINVAL;
+
+	memcg->oom_kill_disable = val;
+	if (!val)
+		memcg_oom_recover(memcg);
+
+	return 0;
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
+{
+	int ret;
+
+	ret = memcg_propagate_kmem(memcg);
+	if (ret)
+		return ret;
+
+	return mem_cgroup_sockets_init(memcg, ss);
+}
+
+static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
+{
+	struct cgroup_subsys_state *css;
+	struct mem_cgroup *parent, *child;
+	int kmemcg_id;
+
+	if (!memcg->kmem_acct_active)
+		return;
+
+	/*
+	 * Clear the 'active' flag before clearing memcg_caches arrays entries.
+	 * Since we take the slab_mutex in memcg_deactivate_kmem_caches(), it
+	 * guarantees no cache will be created for this cgroup after we are
+	 * done (see memcg_create_kmem_cache()).
+	 */
+	memcg->kmem_acct_active = false;
+
+	memcg_deactivate_kmem_caches(memcg);
+
+	kmemcg_id = memcg->kmemcg_id;
+	BUG_ON(kmemcg_id < 0);
+
+	parent = parent_mem_cgroup(memcg);
+	if (!parent)
+		parent = root_mem_cgroup;
+
+	/*
+	 * Change kmemcg_id of this cgroup and all its descendants to the
+	 * parent's id, and then move all entries from this cgroup's list_lrus
+	 * to ones of the parent. After we have finished, all list_lrus
+	 * corresponding to this cgroup are guaranteed to remain empty. The
+	 * ordering is imposed by list_lru_node->lock taken by
+	 * memcg_drain_all_list_lrus().
+	 */
+	rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */
+	css_for_each_descendant_pre(css, &memcg->css) {
+		child = mem_cgroup_from_css(css);
+		BUG_ON(child->kmemcg_id != kmemcg_id);
+		child->kmemcg_id = parent->kmemcg_id;
+		if (!memcg->use_hierarchy)
+			break;
+	}
+	rcu_read_unlock();
+
+	memcg_drain_all_list_lrus(kmemcg_id, parent->kmemcg_id);
+
+	memcg_free_cache_id(kmemcg_id);
+}
+
+static void memcg_destroy_kmem(struct mem_cgroup *memcg)
+{
+	if (memcg->kmem_acct_activated) {
+		memcg_destroy_kmem_caches(memcg);
+		static_key_slow_dec(&memcg_kmem_enabled_key);
+		WARN_ON(page_counter_read(&memcg->kmem));
+	}
+	mem_cgroup_sockets_destroy(memcg);
+}
+#else
+static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
+{
+	return 0;
+}
+
+static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
+{
+}
+
+static void memcg_destroy_kmem(struct mem_cgroup *memcg)
+{
+}
+#endif
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg)
+{
+	return &memcg->cgwb_list;
+}
+
+static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
+{
+	return wb_domain_init(&memcg->cgwb_domain, gfp);
+}
+
+static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
+{
+	wb_domain_exit(&memcg->cgwb_domain);
+}
+
+static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
+{
+	wb_domain_size_changed(&memcg->cgwb_domain);
+}
+
+struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
+
+	if (!memcg->css.parent)
+		return NULL;
+
+	return &memcg->cgwb_domain;
+}
+
+/**
+ * mem_cgroup_wb_stats - retrieve writeback related stats from its memcg
+ * @wb: bdi_writeback in question
+ * @pfilepages: out parameter for number of file pages
+ * @pheadroom: out parameter for number of allocatable pages according to memcg
+ * @pdirty: out parameter for number of dirty pages
+ * @pwriteback: out parameter for number of pages under writeback
+ *
+ * Determine the numbers of file, headroom, dirty, and writeback pages in
+ * @wb's memcg.  File, dirty and writeback are self-explanatory.  Headroom
+ * is a bit more involved.
+ *
+ * A memcg's headroom is "min(max, high) - used".  In the hierarchy, the
+ * headroom is calculated as the lowest headroom of itself and the
+ * ancestors.  Note that this doesn't consider the actual amount of
+ * available memory in the system.  The caller should further cap
+ * *@pheadroom accordingly.
+ */
+void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
+			 unsigned long *pheadroom, unsigned long *pdirty,
+			 unsigned long *pwriteback)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
+	struct mem_cgroup *parent;
+
+	*pdirty = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_DIRTY);
+
+	/* this should eventually include NR_UNSTABLE_NFS */
+	*pwriteback = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_WRITEBACK);
+	*pfilepages = mem_cgroup_nr_lru_pages(memcg, (1 << LRU_INACTIVE_FILE) |
+						     (1 << LRU_ACTIVE_FILE));
+	*pheadroom = PAGE_COUNTER_MAX;
+
+	while ((parent = parent_mem_cgroup(memcg))) {
+		unsigned long ceiling = min(memcg->memory.limit, memcg->high);
+		unsigned long used = page_counter_read(&memcg->memory);
+
+		*pheadroom = min(*pheadroom, ceiling - min(ceiling, used));
+		memcg = parent;
+	}
+}
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
+{
+	return 0;
+}
+
+static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
+{
+}
+
+static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
+{
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+
+/*
+ * DO NOT USE IN NEW FILES.
+ *
+ * "cgroup.event_control" implementation.
+ *
+ * This is way over-engineered.  It tries to support fully configurable
+ * events for each user.  Such level of flexibility is completely
+ * unnecessary especially in the light of the planned unified hierarchy.
+ *
+ * Please deprecate this and replace with something simpler if at all
+ * possible.
+ */
+
+/*
+ * Unregister event and free resources.
+ *
+ * Gets called from workqueue.
+ */
+static void memcg_event_remove(struct work_struct *work)
+{
+	struct mem_cgroup_event *event =
+		container_of(work, struct mem_cgroup_event, remove);
+	struct mem_cgroup *memcg = event->memcg;
+
+	remove_wait_queue(event->wqh, &event->wait);
+
+	event->unregister_event(memcg, event->eventfd);
+
+	/* Notify userspace the event is going away. */
+	eventfd_signal(event->eventfd, 1);
+
+	eventfd_ctx_put(event->eventfd);
+	kfree(event);
+	css_put(&memcg->css);
+}
+
+/*
+ * Gets called on POLLHUP on eventfd when user closes it.
+ *
+ * Called with wqh->lock held and interrupts disabled.
+ */
+static int memcg_event_wake(wait_queue_t *wait, unsigned mode,
+			    int sync, void *key)
+{
+	struct mem_cgroup_event *event =
+		container_of(wait, struct mem_cgroup_event, wait);
+	struct mem_cgroup *memcg = event->memcg;
+	unsigned long flags = (unsigned long)key;
+
+	if (flags & POLLHUP) {
+		/*
+		 * If the event has been detached at cgroup removal, we
+		 * can simply return knowing the other side will cleanup
+		 * for us.
+		 *
+		 * We can't race against event freeing since the other
+		 * side will require wqh->lock via remove_wait_queue(),
+		 * which we hold.
+		 */
+		spin_lock(&memcg->event_list_lock);
+		if (!list_empty(&event->list)) {
+			list_del_init(&event->list);
+			/*
+			 * We are in atomic context, but cgroup_event_remove()
+			 * may sleep, so we have to call it in workqueue.
+			 */
+			schedule_work(&event->remove);
+		}
+		spin_unlock(&memcg->event_list_lock);
+	}
+
+	return 0;
+}
+
+static void memcg_event_ptable_queue_proc(struct file *file,
+		wait_queue_head_t *wqh, poll_table *pt)
+{
+	struct mem_cgroup_event *event =
+		container_of(pt, struct mem_cgroup_event, pt);
+
+	event->wqh = wqh;
+	add_wait_queue(wqh, &event->wait);
+}
+
+/*
+ * DO NOT USE IN NEW FILES.
+ *
+ * Parse input and register new cgroup event handler.
+ *
+ * Input must be in format '<event_fd> <control_fd> <args>'.
+ * Interpretation of args is defined by control file implementation.
+ */
+static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
+					 char *buf, size_t nbytes, loff_t off)
+{
+	struct cgroup_subsys_state *css = of_css(of);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup_event *event;
+	struct cgroup_subsys_state *cfile_css;
+	unsigned int efd, cfd;
+	struct fd efile;
+	struct fd cfile;
+	const char *name;
+	char *endp;
+	int ret;
+
+	buf = strstrip(buf);
+
+	efd = simple_strtoul(buf, &endp, 10);
+	if (*endp != ' ')
+		return -EINVAL;
+	buf = endp + 1;
+
+	cfd = simple_strtoul(buf, &endp, 10);
+	if ((*endp != ' ') && (*endp != '\0'))
+		return -EINVAL;
+	buf = endp + 1;
+
+	event = kzalloc(sizeof(*event), GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	event->memcg = memcg;
+	INIT_LIST_HEAD(&event->list);
+	init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
+	init_waitqueue_func_entry(&event->wait, memcg_event_wake);
+	INIT_WORK(&event->remove, memcg_event_remove);
+
+	efile = fdget(efd);
+	if (!efile.file) {
+		ret = -EBADF;
+		goto out_kfree;
+	}
+
+	event->eventfd = eventfd_ctx_fileget(efile.file);
+	if (IS_ERR(event->eventfd)) {
+		ret = PTR_ERR(event->eventfd);
+		goto out_put_efile;
+	}
+
+	cfile = fdget(cfd);
+	if (!cfile.file) {
+		ret = -EBADF;
+		goto out_put_eventfd;
+	}
+
+	/* the process need read permission on control file */
+	/* AV: shouldn't we check that it's been opened for read instead? */
+	ret = inode_permission(file_inode(cfile.file), MAY_READ);
+	if (ret < 0)
+		goto out_put_cfile;
+
+	/*
+	 * Determine the event callbacks and set them in @event.  This used
+	 * to be done via struct cftype but cgroup core no longer knows
+	 * about these events.  The following is crude but the whole thing
+	 * is for compatibility anyway.
+	 *
+	 * DO NOT ADD NEW FILES.
+	 */
+	name = cfile.file->f_path.dentry->d_name.name;
+
+	if (!strcmp(name, "memory.usage_in_bytes")) {
+		event->register_event = mem_cgroup_usage_register_event;
+		event->unregister_event = mem_cgroup_usage_unregister_event;
+	} else if (!strcmp(name, "memory.oom_control")) {
+		event->register_event = mem_cgroup_oom_register_event;
+		event->unregister_event = mem_cgroup_oom_unregister_event;
+	} else if (!strcmp(name, "memory.pressure_level")) {
+		event->register_event = vmpressure_register_event;
+		event->unregister_event = vmpressure_unregister_event;
+	} else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
+		event->register_event = memsw_cgroup_usage_register_event;
+		event->unregister_event = memsw_cgroup_usage_unregister_event;
+	} else {
+		ret = -EINVAL;
+		goto out_put_cfile;
+	}
+
+	/*
+	 * Verify @cfile should belong to @css.  Also, remaining events are
+	 * automatically removed on cgroup destruction but the removal is
+	 * asynchronous, so take an extra ref on @css.
+	 */
+	cfile_css = css_tryget_online_from_dir(cfile.file->f_path.dentry->d_parent,
+					       &memory_cgrp_subsys);
+	ret = -EINVAL;
+	if (IS_ERR(cfile_css))
+		goto out_put_cfile;
+	if (cfile_css != css) {
+		css_put(cfile_css);
+		goto out_put_cfile;
+	}
+
+	ret = event->register_event(memcg, event->eventfd, buf);
+	if (ret)
+		goto out_put_css;
+
+	efile.file->f_op->poll(efile.file, &event->pt);
+
+	spin_lock(&memcg->event_list_lock);
+	list_add(&event->list, &memcg->event_list);
+	spin_unlock(&memcg->event_list_lock);
+
+	fdput(cfile);
+	fdput(efile);
+
+	return nbytes;
+
+out_put_css:
+	css_put(css);
+out_put_cfile:
+	fdput(cfile);
+out_put_eventfd:
+	eventfd_ctx_put(event->eventfd);
+out_put_efile:
+	fdput(efile);
+out_kfree:
+	kfree(event);
+
+	return ret;
+}
+
+static struct cftype mem_cgroup_legacy_files[] = {
+	{
+		.name = "usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "soft_limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "failcnt",
+		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "stat",
+		.seq_show = memcg_stat_show,
+	},
+	{
+		.name = "force_empty",
+		.write = mem_cgroup_force_empty_write,
+	},
+	{
+		.name = "use_hierarchy",
+		.write_u64 = mem_cgroup_hierarchy_write,
+		.read_u64 = mem_cgroup_hierarchy_read,
+	},
+	{
+		.name = "cgroup.event_control",		/* XXX: for compat */
+		.write = memcg_write_event_control,
+		.flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
+	},
+	{
+		.name = "swappiness",
+		.read_u64 = mem_cgroup_swappiness_read,
+		.write_u64 = mem_cgroup_swappiness_write,
+	},
+	{
+		.name = "move_charge_at_immigrate",
+		.read_u64 = mem_cgroup_move_charge_read,
+		.write_u64 = mem_cgroup_move_charge_write,
+	},
+	{
+		.name = "oom_control",
+		.seq_show = mem_cgroup_oom_control_read,
+		.write_u64 = mem_cgroup_oom_control_write,
+		.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
+	},
+	{
+		.name = "pressure_level",
+	},
+#ifdef CONFIG_NUMA
+	{
+		.name = "numa_stat",
+		.seq_show = memcg_numa_stat_show,
+	},
+#endif
+#ifdef CONFIG_MEMCG_KMEM
+	{
+		.name = "kmem.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.failcnt",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+#ifdef CONFIG_SLABINFO
+	{
+		.name = "kmem.slabinfo",
+		.seq_start = slab_start,
+		.seq_next = slab_next,
+		.seq_stop = slab_stop,
+		.seq_show = memcg_slab_show,
+	},
+#endif
+#endif
+	{ },	/* terminate */
+};
+
+/*
+ * Private memory cgroup IDR
+ *
+ * Swap-out records and page cache shadow entries need to store memcg
+ * references in constrained space, so we maintain an ID space that is
+ * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of
+ * memory-controlled cgroups to 64k.
+ *
+ * However, there usually are many references to the oflline CSS after
+ * the cgroup has been destroyed, such as page cache or reclaimable
+ * slab objects, that don't need to hang on to the ID. We want to keep
+ * those dead CSS from occupying IDs, or we might quickly exhaust the
+ * relatively small ID space and prevent the creation of new cgroups
+ * even when there are much fewer than 64k cgroups - possibly none.
+ *
+ * Maintain a private 16-bit ID space for memcg, and allow the ID to
+ * be freed and recycled when it's no longer needed, which is usually
+ * when the CSS is offlined.
+ *
+ * The only exception to that are records of swapped out tmpfs/shmem
+ * pages that need to be attributed to live ancestors on swapin. But
+ * those references are manageable from userspace.
+ */
+
+static DEFINE_IDR(mem_cgroup_idr);
+
+static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
+{
+	atomic_add(n, &memcg->id.ref);
+}
+
+static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
+{
+	if (atomic_sub_and_test(n, &memcg->id.ref)) {
+		idr_remove(&mem_cgroup_idr, memcg->id.id);
+		memcg->id.id = 0;
+
+		/* Memcg ID pins CSS */
+		css_put(&memcg->css);
+	}
+}
+
+static inline void mem_cgroup_id_get(struct mem_cgroup *memcg)
+{
+	mem_cgroup_id_get_many(memcg, 1);
+}
+
+static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)
+{
+	mem_cgroup_id_put_many(memcg, 1);
+}
+
+/**
+ * mem_cgroup_from_id - look up a memcg from a memcg id
+ * @id: the memcg id to look up
+ *
+ * Caller must hold rcu_read_lock().
+ */
+struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	return idr_find(&mem_cgroup_idr, id);
+}
+
+static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
+{
+	struct mem_cgroup_per_node *pn;
+	struct mem_cgroup_per_zone *mz;
+	int zone, tmp = node;
+	/*
+	 * This routine is called against possible nodes.
+	 * But it's BUG to call kmalloc() against offline node.
+	 *
+	 * TODO: this routine can waste much memory for nodes which will
+	 *       never be onlined. It's better to use memory hotplug callback
+	 *       function.
+	 */
+	if (!node_state(node, N_NORMAL_MEMORY))
+		tmp = -1;
+	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
+	if (!pn)
+		return 1;
+
+	for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+		mz = &pn->zoneinfo[zone];
+		lruvec_init(&mz->lruvec);
+		mz->usage_in_excess = 0;
+		mz->on_tree = false;
+		mz->memcg = memcg;
+	}
+	memcg->nodeinfo[node] = pn;
+	return 0;
+}
+
+static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
+{
+	kfree(memcg->nodeinfo[node]);
+}
+
+static struct mem_cgroup *mem_cgroup_alloc(void)
+{
+	struct mem_cgroup *memcg;
+	size_t size;
+
+	size = sizeof(struct mem_cgroup);
+	size += nr_node_ids * sizeof(struct mem_cgroup_per_node *);
+
+	memcg = kzalloc(size, GFP_KERNEL);
+	if (!memcg)
+		return NULL;
+
+	memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
+	if (!memcg->stat)
+		goto out_free;
+
+	if (memcg_wb_domain_init(memcg, GFP_KERNEL))
+		goto out_free_stat;
+
+	memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
+				 1, MEM_CGROUP_ID_MAX,
+				 GFP_KERNEL);
+	if (memcg->id.id < 0)
+		goto out_free_stat;
+
+	return memcg;
+
+out_free_stat:
+	free_percpu(memcg->stat);
+out_free:
+	kfree(memcg);
+	return NULL;
+}
+
+/*
+ * At destroying mem_cgroup, references from swap_cgroup can remain.
+ * (scanning all at force_empty is too costly...)
+ *
+ * Instead of clearing all references at force_empty, we remember
+ * the number of reference from swap_cgroup and free mem_cgroup when
+ * it goes down to 0.
+ *
+ * Removal of cgroup itself succeeds regardless of refs from swap.
+ */
+
+static void __mem_cgroup_free(struct mem_cgroup *memcg)
+{
+	int node;
+
+	mem_cgroup_remove_from_trees(memcg);
+
+	for_each_node(node)
+		free_mem_cgroup_per_zone_info(memcg, node);
+
+	free_percpu(memcg->stat);
+	memcg_wb_domain_exit(memcg);
+	kfree(memcg);
+}
+
+/*
+ * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
+ */
+struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
+{
+	if (!memcg->memory.parent)
+		return NULL;
+	return mem_cgroup_from_counter(memcg->memory.parent, memory);
+}
+EXPORT_SYMBOL(parent_mem_cgroup);
+
+static struct cgroup_subsys_state * __ref
+mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct mem_cgroup *memcg;
+	long error = -ENOMEM;
+	int node;
+
+	memcg = mem_cgroup_alloc();
+	if (!memcg)
+		return ERR_PTR(error);
+
+	for_each_node(node)
+		if (alloc_mem_cgroup_per_zone_info(memcg, node))
+			goto free_out;
+
+	/* root ? */
+	if (parent_css == NULL) {
+		root_mem_cgroup = memcg;
+		mem_cgroup_root_css = &memcg->css;
+		page_counter_init(&memcg->memory, NULL);
+		memcg->high = PAGE_COUNTER_MAX;
+		memcg->soft_limit = PAGE_COUNTER_MAX;
+		page_counter_init(&memcg->memsw, NULL);
+		page_counter_init(&memcg->kmem, NULL);
+	}
+
+	memcg->last_scanned_node = MAX_NUMNODES;
+	INIT_LIST_HEAD(&memcg->oom_notify);
+	memcg->move_charge_at_immigrate = 0;
+	mutex_init(&memcg->thresholds_lock);
+	spin_lock_init(&memcg->move_lock);
+	vmpressure_init(&memcg->vmpressure);
+	INIT_LIST_HEAD(&memcg->event_list);
+	spin_lock_init(&memcg->event_list_lock);
+#ifdef CONFIG_MEMCG_KMEM
+	memcg->kmemcg_id = -1;
+#endif
+#ifdef CONFIG_CGROUP_WRITEBACK
+	INIT_LIST_HEAD(&memcg->cgwb_list);
+#endif
+	idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
+	return &memcg->css;
+
+free_out:
+	idr_remove(&mem_cgroup_idr, memcg->id.id);
+	__mem_cgroup_free(memcg);
+	return ERR_PTR(error);
+}
+
+static int
+mem_cgroup_css_online(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup *parent = mem_cgroup_from_css(css->parent);
+	int ret;
+
+	/* Online state pins memcg ID, memcg ID pins CSS */
+	mem_cgroup_id_get(mem_cgroup_from_css(css));
+	css_get(css);
+
+	if (!parent)
+		return 0;
+
+	mutex_lock(&memcg_create_mutex);
+
+	memcg->use_hierarchy = parent->use_hierarchy;
+	memcg->oom_kill_disable = parent->oom_kill_disable;
+	memcg->swappiness = mem_cgroup_swappiness(parent);
+
+	if (parent->use_hierarchy) {
+		page_counter_init(&memcg->memory, &parent->memory);
+		memcg->high = PAGE_COUNTER_MAX;
+		memcg->soft_limit = PAGE_COUNTER_MAX;
+		page_counter_init(&memcg->memsw, &parent->memsw);
+		page_counter_init(&memcg->kmem, &parent->kmem);
+
+		/*
+		 * No need to take a reference to the parent because cgroup
+		 * core guarantees its existence.
+		 */
+	} else {
+		page_counter_init(&memcg->memory, NULL);
+		memcg->high = PAGE_COUNTER_MAX;
+		memcg->soft_limit = PAGE_COUNTER_MAX;
+		page_counter_init(&memcg->memsw, NULL);
+		page_counter_init(&memcg->kmem, NULL);
+		/*
+		 * Deeper hierachy with use_hierarchy == false doesn't make
+		 * much sense so let cgroup subsystem know about this
+		 * unfortunate state in our controller.
+		 */
+		if (parent != root_mem_cgroup)
+			memory_cgrp_subsys.broken_hierarchy = true;
+	}
+	mutex_unlock(&memcg_create_mutex);
+
+	ret = memcg_init_kmem(memcg, &memory_cgrp_subsys);
+	if (ret)
+		return ret;
+
+	/*
+	 * Make sure the memcg is initialized: mem_cgroup_iter()
+	 * orders reading memcg->initialized against its callers
+	 * reading the memcg members.
+	 */
+	smp_store_release(&memcg->initialized, 1);
+
+	return 0;
+}
+
+static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup_event *event, *tmp;
+
+	/*
+	 * Unregister events and notify userspace.
+	 * Notify userspace about cgroup removing only after rmdir of cgroup
+	 * directory to avoid race between userspace and kernelspace.
+	 */
+	spin_lock(&memcg->event_list_lock);
+	list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
+		list_del_init(&event->list);
+		schedule_work(&event->remove);
+	}
+	spin_unlock(&memcg->event_list_lock);
+
+	vmpressure_cleanup(&memcg->vmpressure);
+
+	memcg_deactivate_kmem(memcg);
+
+	wb_memcg_offline(memcg);
+
+	mem_cgroup_id_put(memcg);
+}
+
+static void mem_cgroup_css_released(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	invalidate_reclaim_iterators(memcg);
+}
+
+static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	memcg_destroy_kmem(memcg);
+	__mem_cgroup_free(memcg);
+}
+
+/**
+ * mem_cgroup_css_reset - reset the states of a mem_cgroup
+ * @css: the target css
+ *
+ * Reset the states of the mem_cgroup associated with @css.  This is
+ * invoked when the userland requests disabling on the default hierarchy
+ * but the memcg is pinned through dependency.  The memcg should stop
+ * applying policies and should revert to the vanilla state as it may be
+ * made visible again.
+ *
+ * The current implementation only resets the essential configurations.
+ * This needs to be expanded to cover all the visible parts.
+ */
+static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	mem_cgroup_resize_limit(memcg, PAGE_COUNTER_MAX);
+	mem_cgroup_resize_memsw_limit(memcg, PAGE_COUNTER_MAX);
+	memcg_update_kmem_limit(memcg, PAGE_COUNTER_MAX);
+	memcg->low = 0;
+	memcg->high = PAGE_COUNTER_MAX;
+	memcg->soft_limit = PAGE_COUNTER_MAX;
+	memcg_wb_domain_size_changed(memcg);
+}
+
+#ifdef CONFIG_MMU
+/* Handlers for move charge at task migration. */
+static int mem_cgroup_do_precharge(unsigned long count)
+{
+	int ret;
+
+	/* Try a single bulk charge without reclaim first, kswapd may wake */
+	ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count);
+	if (!ret) {
+		mc.precharge += count;
+		return ret;
+	}
+
+	/* Try charges one by one with reclaim, but do not retry */
+	while (count--) {
+		ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1);
+		if (ret)
+			return ret;
+		mc.precharge++;
+		cond_resched();
+	}
+	return 0;
+}
+
+/**
+ * get_mctgt_type - get target type of moving charge
+ * @vma: the vma the pte to be checked belongs
+ * @addr: the address corresponding to the pte to be checked
+ * @ptent: the pte to be checked
+ * @target: the pointer the target page or swap ent will be stored(can be NULL)
+ *
+ * Returns
+ *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
+ *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
+ *     move charge. if @target is not NULL, the page is stored in target->page
+ *     with extra refcnt got(Callers should handle it).
+ *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
+ *     target for charge migration. if @target is not NULL, the entry is stored
+ *     in target->ent.
+ *
+ * Called with pte lock held.
+ */
+union mc_target {
+	struct page	*page;
+	swp_entry_t	ent;
+};
+
+enum mc_target_type {
+	MC_TARGET_NONE = 0,
+	MC_TARGET_PAGE,
+	MC_TARGET_SWAP,
+};
+
+static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
+						unsigned long addr, pte_t ptent)
+{
+	struct page *page = vm_normal_page(vma, addr, ptent);
+
+	if (!page || !page_mapped(page))
+		return NULL;
+	if (PageAnon(page)) {
+		if (!(mc.flags & MOVE_ANON))
+			return NULL;
+	} else {
+		if (!(mc.flags & MOVE_FILE))
+			return NULL;
+	}
+	if (!get_page_unless_zero(page))
+		return NULL;
+
+	return page;
+}
+
+#ifdef CONFIG_SWAP
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+			unsigned long addr, pte_t ptent, swp_entry_t *entry)
+{
+	struct page *page = NULL;
+	swp_entry_t ent = pte_to_swp_entry(ptent);
+
+	if (!(mc.flags & MOVE_ANON) || non_swap_entry(ent))
+		return NULL;
+	/*
+	 * Because lookup_swap_cache() updates some statistics counter,
+	 * we call find_get_page() with swapper_space directly.
+	 */
+	page = find_get_page(swap_address_space(ent), ent.val);
+	if (do_swap_account)
+		entry->val = ent.val;
+
+	return page;
+}
+#else
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+			unsigned long addr, pte_t ptent, swp_entry_t *entry)
+{
+	return NULL;
+}
+#endif
+
+static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
+			unsigned long addr, pte_t ptent, swp_entry_t *entry)
+{
+	struct page *page = NULL;
+	struct address_space *mapping;
+	pgoff_t pgoff;
+
+	if (!vma->vm_file) /* anonymous vma */
+		return NULL;
+	if (!(mc.flags & MOVE_FILE))
+		return NULL;
+
+	mapping = vma->vm_file->f_mapping;
+	pgoff = linear_page_index(vma, addr);
+
+	/* page is moved even if it's not RSS of this task(page-faulted). */
+#ifdef CONFIG_SWAP
+	/* shmem/tmpfs may report page out on swap: account for that too. */
+	if (shmem_mapping(mapping)) {
+		page = find_get_entry(mapping, pgoff);
+		if (radix_tree_exceptional_entry(page)) {
+			swp_entry_t swp = radix_to_swp_entry(page);
+			if (do_swap_account)
+				*entry = swp;
+			page = find_get_page(swap_address_space(swp), swp.val);
+		}
+	} else
+		page = find_get_page(mapping, pgoff);
+#else
+	page = find_get_page(mapping, pgoff);
+#endif
+	return page;
+}
+
+/**
+ * mem_cgroup_move_account - move account of the page
+ * @page: the page
+ * @nr_pages: number of regular pages (>1 for huge pages)
+ * @from: mem_cgroup which the page is moved from.
+ * @to:	mem_cgroup which the page is moved to. @from != @to.
+ *
+ * The caller must confirm following.
+ * - page is not on LRU (isolate_page() is useful.)
+ * - compound_lock is held when nr_pages > 1
+ *
+ * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
+ * from old cgroup.
+ */
+static int mem_cgroup_move_account(struct page *page,
+				   unsigned int nr_pages,
+				   struct mem_cgroup *from,
+				   struct mem_cgroup *to)
+{
+	unsigned long flags;
+	int ret;
+	bool anon;
+
+	VM_BUG_ON(from == to);
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	/*
+	 * The page is isolated from LRU. So, collapse function
+	 * will not handle this page. But page splitting can happen.
+	 * Do this check under compound_page_lock(). The caller should
+	 * hold it.
+	 */
+	ret = -EBUSY;
+	if (nr_pages > 1 && !PageTransHuge(page))
+		goto out;
+
+	/*
+	 * Prevent mem_cgroup_replace_page() from looking at
+	 * page->mem_cgroup of its source page while we change it.
+	 */
+	if (!trylock_page(page))
+		goto out;
+
+	ret = -EINVAL;
+	if (page->mem_cgroup != from)
+		goto out_unlock;
+
+	anon = PageAnon(page);
+
+	spin_lock_irqsave(&from->move_lock, flags);
+
+	if (!anon && page_mapped(page)) {
+		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
+			       nr_pages);
+		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
+			       nr_pages);
+	}
+
+	/*
+	 * move_lock grabbed above and caller set from->moving_account, so
+	 * mem_cgroup_update_page_stat() will serialize updates to PageDirty.
+	 * So mapping should be stable for dirty pages.
+	 */
+	if (!anon && PageDirty(page)) {
+		struct address_space *mapping = page_mapping(page);
+
+		if (mapping_cap_account_dirty(mapping)) {
+			__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_DIRTY],
+				       nr_pages);
+			__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_DIRTY],
+				       nr_pages);
+		}
+	}
+
+	if (PageWriteback(page)) {
+		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK],
+			       nr_pages);
+		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK],
+			       nr_pages);
+	}
+
+	/*
+	 * It is safe to change page->mem_cgroup here because the page
+	 * is referenced, charged, and isolated - we can't race with
+	 * uncharging, charging, migration, or LRU putback.
+	 */
+
+	/* caller should have done css_get */
+	page->mem_cgroup = to;
+	spin_unlock_irqrestore(&from->move_lock, flags);
+
+	ret = 0;
+
+	local_irq_disable();
+	mem_cgroup_charge_statistics(to, page, nr_pages);
+	memcg_check_events(to, page);
+	mem_cgroup_charge_statistics(from, page, -nr_pages);
+	memcg_check_events(from, page);
+	local_irq_enable();
+out_unlock:
+	unlock_page(page);
+out:
+	return ret;
+}
+
+static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
+		unsigned long addr, pte_t ptent, union mc_target *target)
+{
+	struct page *page = NULL;
+	enum mc_target_type ret = MC_TARGET_NONE;
+	swp_entry_t ent = { .val = 0 };
+
+	if (pte_present(ptent))
+		page = mc_handle_present_pte(vma, addr, ptent);
+	else if (is_swap_pte(ptent))
+		page = mc_handle_swap_pte(vma, addr, ptent, &ent);
+	else if (pte_none(ptent))
+		page = mc_handle_file_pte(vma, addr, ptent, &ent);
+
+	if (!page && !ent.val)
+		return ret;
+	if (page) {
+		/*
+		 * Do only loose check w/o serialization.
+		 * mem_cgroup_move_account() checks the page is valid or
+		 * not under LRU exclusion.
+		 */
+		if (page->mem_cgroup == mc.from) {
+			ret = MC_TARGET_PAGE;
+			if (target)
+				target->page = page;
+		}
+		if (!ret || !target)
+			put_page(page);
+	}
+	/* There is a swap entry and a page doesn't exist or isn't charged */
+	if (ent.val && !ret &&
+	    mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
+		ret = MC_TARGET_SWAP;
+		if (target)
+			target->ent = ent;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * We don't consider swapping or file mapped pages because THP does not
+ * support them for now.
+ * Caller should make sure that pmd_trans_huge(pmd) is true.
+ */
+static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
+		unsigned long addr, pmd_t pmd, union mc_target *target)
+{
+	struct page *page = NULL;
+	enum mc_target_type ret = MC_TARGET_NONE;
+
+	page = pmd_page(pmd);
+	VM_BUG_ON_PAGE(!page || !PageHead(page), page);
+	if (!(mc.flags & MOVE_ANON))
+		return ret;
+	if (page->mem_cgroup == mc.from) {
+		ret = MC_TARGET_PAGE;
+		if (target) {
+			get_page(page);
+			target->page = page;
+		}
+	}
+	return ret;
+}
+#else
+static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
+		unsigned long addr, pmd_t pmd, union mc_target *target)
+{
+	return MC_TARGET_NONE;
+}
+#endif
+
+static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
+					unsigned long addr, unsigned long end,
+					struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
+			mc.precharge += HPAGE_PMD_NR;
+		spin_unlock(ptl);
+		return 0;
+	}
+
+	if (pmd_trans_unstable(pmd))
+		return 0;
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	for (; addr != end; pte++, addr += PAGE_SIZE)
+		if (get_mctgt_type(vma, addr, *pte, NULL))
+			mc.precharge++;	/* increment precharge temporarily */
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+
+	return 0;
+}
+
+static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
+{
+	unsigned long precharge;
+
+	struct mm_walk mem_cgroup_count_precharge_walk = {
+		.pmd_entry = mem_cgroup_count_precharge_pte_range,
+		.mm = mm,
+	};
+	down_read(&mm->mmap_sem);
+	walk_page_range(0, ~0UL, &mem_cgroup_count_precharge_walk);
+	up_read(&mm->mmap_sem);
+
+	precharge = mc.precharge;
+	mc.precharge = 0;
+
+	return precharge;
+}
+
+static int mem_cgroup_precharge_mc(struct mm_struct *mm)
+{
+	unsigned long precharge = mem_cgroup_count_precharge(mm);
+
+	VM_BUG_ON(mc.moving_task);
+	mc.moving_task = current;
+	return mem_cgroup_do_precharge(precharge);
+}
+
+/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
+static void __mem_cgroup_clear_mc(void)
+{
+	struct mem_cgroup *from = mc.from;
+	struct mem_cgroup *to = mc.to;
+
+	/* we must uncharge all the leftover precharges from mc.to */
+	if (mc.precharge) {
+		cancel_charge(mc.to, mc.precharge);
+		mc.precharge = 0;
+	}
+	/*
+	 * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
+	 * we must uncharge here.
+	 */
+	if (mc.moved_charge) {
+		cancel_charge(mc.from, mc.moved_charge);
+		mc.moved_charge = 0;
+	}
+	/* we must fixup refcnts and charges */
+	if (mc.moved_swap) {
+		/* uncharge swap account from the old cgroup */
+		if (!mem_cgroup_is_root(mc.from))
+			page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
+
+		mem_cgroup_id_put_many(mc.from, mc.moved_swap);
+
+		/*
+		 * we charged both to->memory and to->memsw, so we
+		 * should uncharge to->memory.
+		 */
+		if (!mem_cgroup_is_root(mc.to))
+			page_counter_uncharge(&mc.to->memory, mc.moved_swap);
+
+		mem_cgroup_id_get_many(mc.to, mc.moved_swap);
+		css_put_many(&mc.to->css, mc.moved_swap);
+
+		mc.moved_swap = 0;
+	}
+	memcg_oom_recover(from);
+	memcg_oom_recover(to);
+	wake_up_all(&mc.waitq);
+}
+
+static void mem_cgroup_clear_mc(void)
+{
+	struct mm_struct *mm = mc.mm;
+
+	/*
+	 * we must clear moving_task before waking up waiters at the end of
+	 * task migration.
+	 */
+	mc.moving_task = NULL;
+	__mem_cgroup_clear_mc();
+	spin_lock(&mc.lock);
+	mc.from = NULL;
+	mc.to = NULL;
+	mc.mm = NULL;
+	spin_unlock(&mc.lock);
+
+	mmput(mm);
+}
+
+static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+	struct cgroup_subsys_state *css;
+	struct mem_cgroup *memcg;
+	struct mem_cgroup *from;
+	struct task_struct *leader, *p;
+	struct mm_struct *mm;
+	unsigned long move_flags;
+	int ret = 0;
+
+	/* charge immigration isn't supported on the default hierarchy */
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return 0;
+
+	/*
+	 * Multi-process migrations only happen on the default hierarchy
+	 * where charge immigration is not used.  Perform charge
+	 * immigration if @tset contains a leader and whine if there are
+	 * multiple.
+	 */
+	p = NULL;
+	cgroup_taskset_for_each_leader(leader, css, tset) {
+		WARN_ON_ONCE(p);
+		p = leader;
+		memcg = mem_cgroup_from_css(css);
+	}
+	if (!p)
+		return 0;
+
+	/*
+	 * We are now commited to this value whatever it is. Changes in this
+	 * tunable will only affect upcoming migrations, not the current one.
+	 * So we need to save it, and keep it going.
+	 */
+	move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
+	if (!move_flags)
+		return 0;
+
+	from = mem_cgroup_from_task(p);
+
+	VM_BUG_ON(from == memcg);
+
+	mm = get_task_mm(p);
+	if (!mm)
+		return 0;
+	/* We move charges only when we move a owner of the mm */
+	if (mm->owner == p) {
+		VM_BUG_ON(mc.from);
+		VM_BUG_ON(mc.to);
+		VM_BUG_ON(mc.precharge);
+		VM_BUG_ON(mc.moved_charge);
+		VM_BUG_ON(mc.moved_swap);
+
+		spin_lock(&mc.lock);
+		mc.mm = mm;
+		mc.from = from;
+		mc.to = memcg;
+		mc.flags = move_flags;
+		spin_unlock(&mc.lock);
+		/* We set mc.moving_task later */
+
+		ret = mem_cgroup_precharge_mc(mm);
+		if (ret)
+			mem_cgroup_clear_mc();
+	} else {
+		mmput(mm);
+	}
+	return ret;
+}
+
+static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
+{
+	if (mc.to)
+		mem_cgroup_clear_mc();
+}
+
+static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
+				unsigned long addr, unsigned long end,
+				struct mm_walk *walk)
+{
+	int ret = 0;
+	struct vm_area_struct *vma = walk->vma;
+	pte_t *pte;
+	spinlock_t *ptl;
+	enum mc_target_type target_type;
+	union mc_target target;
+	struct page *page;
+
+	/*
+	 * We don't take compound_lock() here but no race with splitting thp
+	 * happens because:
+	 *  - if pmd_trans_huge_lock() returns 1, the relevant thp is not
+	 *    under splitting, which means there's no concurrent thp split,
+	 *  - if another thread runs into split_huge_page() just after we
+	 *    entered this if-block, the thread must wait for page table lock
+	 *    to be unlocked in __split_huge_page_splitting(), where the main
+	 *    part of thp split is not executed yet.
+	 */
+	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+		if (mc.precharge < HPAGE_PMD_NR) {
+			spin_unlock(ptl);
+			return 0;
+		}
+		target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
+		if (target_type == MC_TARGET_PAGE) {
+			page = target.page;
+			if (!isolate_lru_page(page)) {
+				if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
+							     mc.from, mc.to)) {
+					mc.precharge -= HPAGE_PMD_NR;
+					mc.moved_charge += HPAGE_PMD_NR;
+				}
+				putback_lru_page(page);
+			}
+			put_page(page);
+		}
+		spin_unlock(ptl);
+		return 0;
+	}
+
+	if (pmd_trans_unstable(pmd))
+		return 0;
+retry:
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	for (; addr != end; addr += PAGE_SIZE) {
+		pte_t ptent = *(pte++);
+		swp_entry_t ent;
+
+		if (!mc.precharge)
+			break;
+
+		switch (get_mctgt_type(vma, addr, ptent, &target)) {
+		case MC_TARGET_PAGE:
+			page = target.page;
+			if (isolate_lru_page(page))
+				goto put;
+			if (!mem_cgroup_move_account(page, 1, mc.from, mc.to)) {
+				mc.precharge--;
+				/* we uncharge from mc.from later. */
+				mc.moved_charge++;
+			}
+			putback_lru_page(page);
+put:			/* get_mctgt_type() gets the page */
+			put_page(page);
+			break;
+		case MC_TARGET_SWAP:
+			ent = target.ent;
+			if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
+				mc.precharge--;
+				/* we fixup refcnts and charges later. */
+				mc.moved_swap++;
+			}
+			break;
+		default:
+			break;
+		}
+	}
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+
+	if (addr != end) {
+		/*
+		 * We have consumed all precharges we got in can_attach().
+		 * We try charge one by one, but don't do any additional
+		 * charges to mc.to if we have failed in charge once in attach()
+		 * phase.
+		 */
+		ret = mem_cgroup_do_precharge(1);
+		if (!ret)
+			goto retry;
+	}
+
+	return ret;
+}
+
+static void mem_cgroup_move_charge(void)
+{
+	struct mm_walk mem_cgroup_move_charge_walk = {
+		.pmd_entry = mem_cgroup_move_charge_pte_range,
+		.mm = mc.mm,
+	};
+
+	lru_add_drain_all();
+	/*
+	 * Signal mem_cgroup_begin_page_stat() to take the memcg's
+	 * move_lock while we're moving its pages to another memcg.
+	 * Then wait for already started RCU-only updates to finish.
+	 */
+	atomic_inc(&mc.from->moving_account);
+	synchronize_rcu();
+retry:
+	if (unlikely(!down_read_trylock(&mc.mm->mmap_sem))) {
+		/*
+		 * Someone who are holding the mmap_sem might be waiting in
+		 * waitq. So we cancel all extra charges, wake up all waiters,
+		 * and retry. Because we cancel precharges, we might not be able
+		 * to move enough charges, but moving charge is a best-effort
+		 * feature anyway, so it wouldn't be a big problem.
+		 */
+		__mem_cgroup_clear_mc();
+		cond_resched();
+		goto retry;
+	}
+	/*
+	 * When we have consumed all precharges and failed in doing
+	 * additional charge, the page walk just aborts.
+	 */
+	walk_page_range(0, ~0UL, &mem_cgroup_move_charge_walk);
+	up_read(&mc.mm->mmap_sem);
+	atomic_dec(&mc.from->moving_account);
+}
+
+static void mem_cgroup_move_task(void)
+{
+	if (mc.to) {
+		mem_cgroup_move_charge();
+		mem_cgroup_clear_mc();
+	}
+}
+#else	/* !CONFIG_MMU */
+static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+	return 0;
+}
+static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
+{
+}
+static void mem_cgroup_move_task(void)
+{
+}
+#endif
+
+/*
+ * Cgroup retains root cgroups across [un]mount cycles making it necessary
+ * to verify whether we're attached to the default hierarchy on each mount
+ * attempt.
+ */
+static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
+{
+	/*
+	 * use_hierarchy is forced on the default hierarchy.  cgroup core
+	 * guarantees that @root doesn't have any children, so turning it
+	 * on for the root memcg is enough.
+	 */
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		root_mem_cgroup->use_hierarchy = true;
+	else
+		root_mem_cgroup->use_hierarchy = false;
+}
+
+static u64 memory_current_read(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	return (u64)page_counter_read(&memcg->memory) * PAGE_SIZE;
+}
+
+static int memory_low_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long low = READ_ONCE(memcg->low);
+
+	if (low == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)low * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_low_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long low;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &low);
+	if (err)
+		return err;
+
+	memcg->low = low;
+
+	return nbytes;
+}
+
+static int memory_high_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long high = READ_ONCE(memcg->high);
+
+	if (high == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)high * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_high_write(struct kernfs_open_file *of,
+				 char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long nr_pages;
+	unsigned long high;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &high);
+	if (err)
+		return err;
+
+	memcg->high = high;
+
+	nr_pages = page_counter_read(&memcg->memory);
+	if (nr_pages > high)
+		try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
+					     GFP_KERNEL, true);
+
+	memcg_wb_domain_size_changed(memcg);
+	return nbytes;
+}
+
+static int memory_max_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long max = READ_ONCE(memcg->memory.limit);
+
+	if (max == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_max_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES;
+	bool drained = false;
+	unsigned long max;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &max);
+	if (err)
+		return err;
+
+	xchg(&memcg->memory.limit, max);
+
+	for (;;) {
+		unsigned long nr_pages = page_counter_read(&memcg->memory);
+
+		if (nr_pages <= max)
+			break;
+
+		if (signal_pending(current)) {
+			err = -EINTR;
+			break;
+		}
+
+		if (!drained) {
+			drain_all_stock(memcg);
+			drained = true;
+			continue;
+		}
+
+		if (nr_reclaims) {
+			if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max,
+							  GFP_KERNEL, true))
+				nr_reclaims--;
+			continue;
+		}
+
+		mem_cgroup_events(memcg, MEMCG_OOM, 1);
+		if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0))
+			break;
+	}
+
+	memcg_wb_domain_size_changed(memcg);
+	return nbytes;
+}
+
+static int memory_events_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	seq_printf(m, "low %lu\n", mem_cgroup_read_events(memcg, MEMCG_LOW));
+	seq_printf(m, "high %lu\n", mem_cgroup_read_events(memcg, MEMCG_HIGH));
+	seq_printf(m, "max %lu\n", mem_cgroup_read_events(memcg, MEMCG_MAX));
+	seq_printf(m, "oom %lu\n", mem_cgroup_read_events(memcg, MEMCG_OOM));
+
+	return 0;
+}
+
+static struct cftype memory_files[] = {
+	{
+		.name = "current",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.read_u64 = memory_current_read,
+	},
+	{
+		.name = "low",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_low_show,
+		.write = memory_low_write,
+	},
+	{
+		.name = "high",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_high_show,
+		.write = memory_high_write,
+	},
+	{
+		.name = "max",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_max_show,
+		.write = memory_max_write,
+	},
+	{
+		.name = "events",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.file_offset = offsetof(struct mem_cgroup, events_file),
+		.seq_show = memory_events_show,
+	},
+	{ }	/* terminate */
+};
+
+struct cgroup_subsys memory_cgrp_subsys = {
+	.css_alloc = mem_cgroup_css_alloc,
+	.css_online = mem_cgroup_css_online,
+	.css_offline = mem_cgroup_css_offline,
+	.css_released = mem_cgroup_css_released,
+	.css_free = mem_cgroup_css_free,
+	.css_reset = mem_cgroup_css_reset,
+	.can_attach = mem_cgroup_can_attach,
+	.cancel_attach = mem_cgroup_cancel_attach,
+	.post_attach = mem_cgroup_move_task,
+	.bind = mem_cgroup_bind,
+	.dfl_cftypes = memory_files,
+	.legacy_cftypes = mem_cgroup_legacy_files,
+	.early_init = 0,
+};
+
+/**
+ * mem_cgroup_low - check if memory consumption is below the normal range
+ * @root: the highest ancestor to consider
+ * @memcg: the memory cgroup to check
+ *
+ * Returns %true if memory consumption of @memcg, and that of all
+ * configurable ancestors up to @root, is below the normal range.
+ */
+bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg)
+{
+	if (mem_cgroup_disabled())
+		return false;
+
+	/*
+	 * The toplevel group doesn't have a configurable range, so
+	 * it's never low when looked at directly, and it is not
+	 * considered an ancestor when assessing the hierarchy.
+	 */
+
+	if (memcg == root_mem_cgroup)
+		return false;
+
+	if (page_counter_read(&memcg->memory) >= memcg->low)
+		return false;
+
+	while (memcg != root) {
+		memcg = parent_mem_cgroup(memcg);
+
+		if (memcg == root_mem_cgroup)
+			break;
+
+		if (page_counter_read(&memcg->memory) >= memcg->low)
+			return false;
+	}
+	return true;
+}
+
+/**
+ * mem_cgroup_try_charge - try charging a page
+ * @page: page to charge
+ * @mm: mm context of the victim
+ * @gfp_mask: reclaim mode
+ * @memcgp: charged memcg return
+ *
+ * Try to charge @page to the memcg that @mm belongs to, reclaiming
+ * pages according to @gfp_mask if necessary.
+ *
+ * Returns 0 on success, with *@memcgp pointing to the charged memcg.
+ * Otherwise, an error code is returned.
+ *
+ * After page->mapping has been set up, the caller must finalize the
+ * charge with mem_cgroup_commit_charge().  Or abort the transaction
+ * with mem_cgroup_cancel_charge() in case page instantiation fails.
+ */
+int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
+			  gfp_t gfp_mask, struct mem_cgroup **memcgp)
+{
+	struct mem_cgroup *memcg = NULL;
+	unsigned int nr_pages = 1;
+	int ret = 0;
+
+	if (mem_cgroup_disabled())
+		goto out;
+
+	if (PageSwapCache(page)) {
+		/*
+		 * Every swap fault against a single page tries to charge the
+		 * page, bail as early as possible.  shmem_unuse() encounters
+		 * already charged pages, too.  The USED bit is protected by
+		 * the page lock, which serializes swap cache removal, which
+		 * in turn serializes uncharging.
+		 */
+		VM_BUG_ON_PAGE(!PageLocked(page), page);
+		if (page->mem_cgroup)
+			goto out;
+
+		if (do_swap_account) {
+			swp_entry_t ent = { .val = page_private(page), };
+			unsigned short id = lookup_swap_cgroup_id(ent);
+
+			rcu_read_lock();
+			memcg = mem_cgroup_from_id(id);
+			if (memcg && !css_tryget_online(&memcg->css))
+				memcg = NULL;
+			rcu_read_unlock();
+		}
+	}
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+	}
+
+	if (!memcg)
+		memcg = get_mem_cgroup_from_mm(mm);
+
+	ret = try_charge(memcg, gfp_mask, nr_pages);
+
+	css_put(&memcg->css);
+out:
+	*memcgp = memcg;
+	return ret;
+}
+
+/**
+ * mem_cgroup_commit_charge - commit a page charge
+ * @page: page to charge
+ * @memcg: memcg to charge the page to
+ * @lrucare: page might be on LRU already
+ *
+ * Finalize a charge transaction started by mem_cgroup_try_charge(),
+ * after page->mapping has been set up.  This must happen atomically
+ * as part of the page instantiation, i.e. under the page table lock
+ * for anonymous pages, under the page lock for page and swap cache.
+ *
+ * In addition, the page must not be on the LRU during the commit, to
+ * prevent racing with task migration.  If it might be, use @lrucare.
+ *
+ * Use mem_cgroup_cancel_charge() to cancel the transaction instead.
+ */
+void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
+			      bool lrucare)
+{
+	unsigned int nr_pages = 1;
+
+	VM_BUG_ON_PAGE(!page->mapping, page);
+	VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);
+
+	if (mem_cgroup_disabled())
+		return;
+	/*
+	 * Swap faults will attempt to charge the same page multiple
+	 * times.  But reuse_swap_page() might have removed the page
+	 * from swapcache already, so we can't check PageSwapCache().
+	 */
+	if (!memcg)
+		return;
+
+	commit_charge(page, memcg, lrucare);
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+	}
+
+	local_irq_disable();
+	mem_cgroup_charge_statistics(memcg, page, nr_pages);
+	memcg_check_events(memcg, page);
+	local_irq_enable();
+
+	if (do_swap_account && PageSwapCache(page)) {
+		swp_entry_t entry = { .val = page_private(page) };
+		/*
+		 * The swap entry might not get freed for a long time,
+		 * let's not wait for it.  The page already received a
+		 * memory+swap charge, drop the swap entry duplicate.
+		 */
+		mem_cgroup_uncharge_swap(entry);
+	}
+}
+
+/**
+ * mem_cgroup_cancel_charge - cancel a page charge
+ * @page: page to charge
+ * @memcg: memcg to charge the page to
+ *
+ * Cancel a charge transaction started by mem_cgroup_try_charge().
+ */
+void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg)
+{
+	unsigned int nr_pages = 1;
+
+	if (mem_cgroup_disabled())
+		return;
+	/*
+	 * Swap faults will attempt to charge the same page multiple
+	 * times.  But reuse_swap_page() might have removed the page
+	 * from swapcache already, so we can't check PageSwapCache().
+	 */
+	if (!memcg)
+		return;
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+	}
+
+	cancel_charge(memcg, nr_pages);
+}
+
+static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
+			   unsigned long nr_anon, unsigned long nr_file,
+			   unsigned long nr_huge, struct page *dummy_page)
+{
+	unsigned long nr_pages = nr_anon + nr_file;
+	unsigned long flags;
+
+	if (!mem_cgroup_is_root(memcg)) {
+		page_counter_uncharge(&memcg->memory, nr_pages);
+		if (do_swap_account)
+			page_counter_uncharge(&memcg->memsw, nr_pages);
+		memcg_oom_recover(memcg);
+	}
+
+	local_irq_save(flags);
+	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS], nr_anon);
+	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_CACHE], nr_file);
+	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], nr_huge);
+	__this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT], pgpgout);
+	__this_cpu_add(memcg->stat->nr_page_events, nr_pages);
+	memcg_check_events(memcg, dummy_page);
+	local_irq_restore(flags);
+
+	if (!mem_cgroup_is_root(memcg))
+		css_put_many(&memcg->css, nr_pages);
+}
+
+static void uncharge_list(struct list_head *page_list)
+{
+	struct mem_cgroup *memcg = NULL;
+	unsigned long nr_anon = 0;
+	unsigned long nr_file = 0;
+	unsigned long nr_huge = 0;
+	unsigned long pgpgout = 0;
+	struct list_head *next;
+	struct page *page;
+
+	next = page_list->next;
+	do {
+		unsigned int nr_pages = 1;
+
+		page = list_entry(next, struct page, lru);
+		next = page->lru.next;
+
+		VM_BUG_ON_PAGE(PageLRU(page), page);
+		VM_BUG_ON_PAGE(page_count(page), page);
+
+		if (!page->mem_cgroup)
+			continue;
+
+		/*
+		 * Nobody should be changing or seriously looking at
+		 * page->mem_cgroup at this point, we have fully
+		 * exclusive access to the page.
+		 */
+
+		if (memcg != page->mem_cgroup) {
+			if (memcg) {
+				uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
+					       nr_huge, page);
+				pgpgout = nr_anon = nr_file = nr_huge = 0;
+			}
+			memcg = page->mem_cgroup;
+		}
+
+		if (PageTransHuge(page)) {
+			nr_pages <<= compound_order(page);
+			VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+			nr_huge += nr_pages;
+		}
+
+		if (PageAnon(page))
+			nr_anon += nr_pages;
+		else
+			nr_file += nr_pages;
+
+		page->mem_cgroup = NULL;
+
+		pgpgout++;
+	} while (next != page_list);
+
+	if (memcg)
+		uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
+			       nr_huge, page);
+}
+
+/**
+ * mem_cgroup_uncharge - uncharge a page
+ * @page: page to uncharge
+ *
+ * Uncharge a page previously charged with mem_cgroup_try_charge() and
+ * mem_cgroup_commit_charge().
+ */
+void mem_cgroup_uncharge(struct page *page)
+{
+	if (mem_cgroup_disabled())
+		return;
+
+	/* Don't touch page->lru of any random page, pre-check: */
+	if (!page->mem_cgroup)
+		return;
+
+	INIT_LIST_HEAD(&page->lru);
+	uncharge_list(&page->lru);
+}
+
+/**
+ * mem_cgroup_uncharge_list - uncharge a list of page
+ * @page_list: list of pages to uncharge
+ *
+ * Uncharge a list of pages previously charged with
+ * mem_cgroup_try_charge() and mem_cgroup_commit_charge().
+ */
+void mem_cgroup_uncharge_list(struct list_head *page_list)
+{
+	if (mem_cgroup_disabled())
+		return;
+
+	if (!list_empty(page_list))
+		uncharge_list(page_list);
+}
+
+/**
+ * mem_cgroup_replace_page - migrate a charge to another page
+ * @oldpage: currently charged page
+ * @newpage: page to transfer the charge to
+ *
+ * Migrate the charge from @oldpage to @newpage.
+ *
+ * Both pages must be locked, @newpage->mapping must be set up.
+ * Either or both pages might be on the LRU already.
+ */
+void mem_cgroup_replace_page(struct page *oldpage, struct page *newpage)
+{
+	struct mem_cgroup *memcg;
+	int isolated;
+
+	VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+	VM_BUG_ON_PAGE(PageAnon(oldpage) != PageAnon(newpage), newpage);
+	VM_BUG_ON_PAGE(PageTransHuge(oldpage) != PageTransHuge(newpage),
+		       newpage);
+
+	if (mem_cgroup_disabled())
+		return;
+
+	/* Page cache replacement: new page already charged? */
+	if (newpage->mem_cgroup)
+		return;
+
+	/* Swapcache readahead pages can get replaced before being charged */
+	memcg = oldpage->mem_cgroup;
+	if (!memcg)
+		return;
+
+	lock_page_lru(oldpage, &isolated);
+	oldpage->mem_cgroup = NULL;
+	unlock_page_lru(oldpage, isolated);
+
+	commit_charge(newpage, memcg, true);
+}
+
+/*
+ * subsys_initcall() for memory controller.
+ *
+ * Some parts like hotcpu_notifier() have to be initialized from this context
+ * because of lock dependencies (cgroup_lock -> cpu hotplug) but basically
+ * everything that doesn't depend on a specific mem_cgroup structure should
+ * be initialized from here.
+ */
+static int __init mem_cgroup_init(void)
+{
+	int cpu, node;
+
+	hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
+
+	for_each_possible_cpu(cpu)
+		INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
+			  drain_local_stock);
+
+	for_each_node(node) {
+		struct mem_cgroup_tree_per_node *rtpn;
+		int zone;
+
+		rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
+				    node_online(node) ? node : NUMA_NO_NODE);
+
+		for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+			struct mem_cgroup_tree_per_zone *rtpz;
+
+			rtpz = &rtpn->rb_tree_per_zone[zone];
+			rtpz->rb_root = RB_ROOT;
+			spin_lock_init(&rtpz->lock);
+		}
+		soft_limit_tree.rb_tree_per_node[node] = rtpn;
+	}
+
+	return 0;
+}
+subsys_initcall(mem_cgroup_init);
+
+#ifdef CONFIG_MEMCG_SWAP
+static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
+{
+	while (!atomic_inc_not_zero(&memcg->id.ref)) {
+		/*
+		 * The root cgroup cannot be destroyed, so it's refcount must
+		 * always be >= 1.
+		 */
+		if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {
+			VM_BUG_ON(1);
+			break;
+		}
+		memcg = parent_mem_cgroup(memcg);
+		if (!memcg)
+			memcg = root_mem_cgroup;
+	}
+	return memcg;
+}
+
+/**
+ * mem_cgroup_swapout - transfer a memsw charge to swap
+ * @page: page whose memsw charge to transfer
+ * @entry: swap entry to move the charge to
+ *
+ * Transfer the memsw charge of @page to @entry.
+ */
+void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
+{
+	struct mem_cgroup *memcg, *swap_memcg;
+	unsigned short oldid;
+
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON_PAGE(page_count(page), page);
+
+	if (!do_swap_account)
+		return;
+
+	memcg = page->mem_cgroup;
+
+	/* Readahead page, never charged */
+	if (!memcg)
+		return;
+
+	/*
+	 * In case the memcg owning these pages has been offlined and doesn't
+	 * have an ID allocated to it anymore, charge the closest online
+	 * ancestor for the swap instead and transfer the memory+swap charge.
+	 */
+	swap_memcg = mem_cgroup_id_get_online(memcg);
+	oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg));
+	VM_BUG_ON_PAGE(oldid, page);
+	mem_cgroup_swap_statistics(swap_memcg, true);
+
+	page->mem_cgroup = NULL;
+
+	if (!mem_cgroup_is_root(memcg))
+		page_counter_uncharge(&memcg->memory, 1);
+
+	if (memcg != swap_memcg) {
+		if (!mem_cgroup_is_root(swap_memcg))
+			page_counter_charge(&swap_memcg->memsw, 1);
+		page_counter_uncharge(&memcg->memsw, 1);
+	}
+
+	/*
+	 * Interrupts should be disabled here because the caller holds the
+	 * mapping->tree_lock lock which is taken with interrupts-off. It is
+	 * important here to have the interrupts disabled because it is the
+	 * only synchronisation we have for udpating the per-CPU variables.
+	 */
+	VM_BUG_ON(!irqs_disabled());
+	mem_cgroup_charge_statistics(memcg, page, -1);
+	memcg_check_events(memcg, page);
+
+	if (!mem_cgroup_is_root(memcg))
+		css_put(&memcg->css);
+}
+
+/**
+ * mem_cgroup_uncharge_swap - uncharge a swap entry
+ * @entry: swap entry to uncharge
+ *
+ * Drop the memsw charge associated with @entry.
+ */
+void mem_cgroup_uncharge_swap(swp_entry_t entry)
+{
+	struct mem_cgroup *memcg;
+	unsigned short id;
+
+	if (!do_swap_account)
+		return;
+
+	id = swap_cgroup_record(entry, 0);
+	rcu_read_lock();
+	memcg = mem_cgroup_from_id(id);
+	if (memcg) {
+		if (!mem_cgroup_is_root(memcg))
+			page_counter_uncharge(&memcg->memsw, 1);
+		mem_cgroup_swap_statistics(memcg, false);
+		mem_cgroup_id_put(memcg);
+	}
+	rcu_read_unlock();
+}
+
+/* for remember boot option*/
+#ifdef CONFIG_MEMCG_SWAP_ENABLED
+static int really_do_swap_account __initdata = 1;
+#else
+static int really_do_swap_account __initdata;
+#endif
+
+static int __init enable_swap_account(char *s)
+{
+	if (!strcmp(s, "1"))
+		really_do_swap_account = 1;
+	else if (!strcmp(s, "0"))
+		really_do_swap_account = 0;
+	return 1;
+}
+__setup("swapaccount=", enable_swap_account);
+
+static struct cftype memsw_cgroup_files[] = {
+	{
+		.name = "memsw.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "memsw.max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "memsw.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "memsw.failcnt",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{ },	/* terminate */
+};
+
+static int __init mem_cgroup_swap_init(void)
+{
+	if (!mem_cgroup_disabled() && really_do_swap_account) {
+		do_swap_account = 1;
+		WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys,
+						  memsw_cgroup_files));
+	}
+	return 0;
+}
+subsys_initcall(mem_cgroup_swap_init);
+
+#endif /* CONFIG_MEMCG_SWAP */
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
new file mode 100644
index 0000000..091fe9b
--- /dev/null
+++ b/mm/memory-failure.c
@@ -0,0 +1,1782 @@
+/*
+ * Copyright (C) 2008, 2009 Intel Corporation
+ * Authors: Andi Kleen, Fengguang Wu
+ *
+ * This software may be redistributed and/or modified under the terms of
+ * the GNU General Public License ("GPL") version 2 only as published by the
+ * Free Software Foundation.
+ *
+ * High level machine check handler. Handles pages reported by the
+ * hardware as being corrupted usually due to a multi-bit ECC memory or cache
+ * failure.
+ * 
+ * In addition there is a "soft offline" entry point that allows stop using
+ * not-yet-corrupted-by-suspicious pages without killing anything.
+ *
+ * Handles page cache pages in various states.	The tricky part
+ * here is that we can access any page asynchronously in respect to 
+ * other VM users, because memory failures could happen anytime and 
+ * anywhere. This could violate some of their assumptions. This is why 
+ * this code has to be extremely careful. Generally it tries to use 
+ * normal locking rules, as in get the standard locks, even if that means 
+ * the error handling takes potentially a long time.
+ *
+ * It can be very tempting to add handling for obscure cases here.
+ * In general any code for handling new cases should only be added iff:
+ * - You know how to test it.
+ * - You have a test that can be added to mce-test
+ *   https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/
+ * - The case actually shows up as a frequent (top 10) page state in
+ *   tools/vm/page-types when running a real workload.
+ * 
+ * There are several operations here with exponential complexity because
+ * of unsuitable VM data structures. For example the operation to map back 
+ * from RMAP chains to processes has to walk the complete process list and 
+ * has non linear complexity with the number. But since memory corruptions
+ * are rare we hope to get away with this. This avoids impacting the core 
+ * VM.
+ */
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/page-flags.h>
+#include <linux/kernel-page-flags.h>
+#include <linux/sched.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/export.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/backing-dev.h>
+#include <linux/migrate.h>
+#include <linux/page-isolation.h>
+#include <linux/suspend.h>
+#include <linux/slab.h>
+#include <linux/swapops.h>
+#include <linux/hugetlb.h>
+#include <linux/memory_hotplug.h>
+#include <linux/mm_inline.h>
+#include <linux/kfifo.h>
+#include <linux/ratelimit.h>
+#include "internal.h"
+#include "ras/ras_event.h"
+
+int sysctl_memory_failure_early_kill __read_mostly = 0;
+
+int sysctl_memory_failure_recovery __read_mostly = 1;
+
+atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
+
+#if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
+
+u32 hwpoison_filter_enable = 0;
+u32 hwpoison_filter_dev_major = ~0U;
+u32 hwpoison_filter_dev_minor = ~0U;
+u64 hwpoison_filter_flags_mask;
+u64 hwpoison_filter_flags_value;
+EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
+EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
+EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
+EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
+EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
+
+static int hwpoison_filter_dev(struct page *p)
+{
+	struct address_space *mapping;
+	dev_t dev;
+
+	if (hwpoison_filter_dev_major == ~0U &&
+	    hwpoison_filter_dev_minor == ~0U)
+		return 0;
+
+	/*
+	 * page_mapping() does not accept slab pages.
+	 */
+	if (PageSlab(p))
+		return -EINVAL;
+
+	mapping = page_mapping(p);
+	if (mapping == NULL || mapping->host == NULL)
+		return -EINVAL;
+
+	dev = mapping->host->i_sb->s_dev;
+	if (hwpoison_filter_dev_major != ~0U &&
+	    hwpoison_filter_dev_major != MAJOR(dev))
+		return -EINVAL;
+	if (hwpoison_filter_dev_minor != ~0U &&
+	    hwpoison_filter_dev_minor != MINOR(dev))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int hwpoison_filter_flags(struct page *p)
+{
+	if (!hwpoison_filter_flags_mask)
+		return 0;
+
+	if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
+				    hwpoison_filter_flags_value)
+		return 0;
+	else
+		return -EINVAL;
+}
+
+/*
+ * This allows stress tests to limit test scope to a collection of tasks
+ * by putting them under some memcg. This prevents killing unrelated/important
+ * processes such as /sbin/init. Note that the target task may share clean
+ * pages with init (eg. libc text), which is harmless. If the target task
+ * share _dirty_ pages with another task B, the test scheme must make sure B
+ * is also included in the memcg. At last, due to race conditions this filter
+ * can only guarantee that the page either belongs to the memcg tasks, or is
+ * a freed page.
+ */
+#ifdef CONFIG_MEMCG
+u64 hwpoison_filter_memcg;
+EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
+static int hwpoison_filter_task(struct page *p)
+{
+	if (!hwpoison_filter_memcg)
+		return 0;
+
+	if (page_cgroup_ino(p) != hwpoison_filter_memcg)
+		return -EINVAL;
+
+	return 0;
+}
+#else
+static int hwpoison_filter_task(struct page *p) { return 0; }
+#endif
+
+int hwpoison_filter(struct page *p)
+{
+	if (!hwpoison_filter_enable)
+		return 0;
+
+	if (hwpoison_filter_dev(p))
+		return -EINVAL;
+
+	if (hwpoison_filter_flags(p))
+		return -EINVAL;
+
+	if (hwpoison_filter_task(p))
+		return -EINVAL;
+
+	return 0;
+}
+#else
+int hwpoison_filter(struct page *p)
+{
+	return 0;
+}
+#endif
+
+EXPORT_SYMBOL_GPL(hwpoison_filter);
+
+/*
+ * Send all the processes who have the page mapped a signal.
+ * ``action optional'' if they are not immediately affected by the error
+ * ``action required'' if error happened in current execution context
+ */
+static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
+			unsigned long pfn, struct page *page, int flags)
+{
+	struct siginfo si;
+	int ret;
+
+	printk(KERN_ERR
+		"MCE %#lx: Killing %s:%d due to hardware memory corruption\n",
+		pfn, t->comm, t->pid);
+	si.si_signo = SIGBUS;
+	si.si_errno = 0;
+	si.si_addr = (void *)addr;
+#ifdef __ARCH_SI_TRAPNO
+	si.si_trapno = trapno;
+#endif
+	si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT;
+
+	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
+		si.si_code = BUS_MCEERR_AR;
+		ret = force_sig_info(SIGBUS, &si, current);
+	} else {
+		/*
+		 * Don't use force here, it's convenient if the signal
+		 * can be temporarily blocked.
+		 * This could cause a loop when the user sets SIGBUS
+		 * to SIG_IGN, but hopefully no one will do that?
+		 */
+		si.si_code = BUS_MCEERR_AO;
+		ret = send_sig_info(SIGBUS, &si, t);  /* synchronous? */
+	}
+	if (ret < 0)
+		printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
+		       t->comm, t->pid, ret);
+	return ret;
+}
+
+/*
+ * When a unknown page type is encountered drain as many buffers as possible
+ * in the hope to turn the page into a LRU or free page, which we can handle.
+ */
+void shake_page(struct page *p, int access)
+{
+	if (!PageSlab(p)) {
+		lru_add_drain_all();
+		if (PageLRU(p))
+			return;
+		drain_all_pages(page_zone(p));
+		if (PageLRU(p) || is_free_buddy_page(p))
+			return;
+	}
+
+	/*
+	 * Only call shrink_node_slabs here (which would also shrink
+	 * other caches) if access is not potentially fatal.
+	 */
+	if (access)
+		drop_slab_node(page_to_nid(p));
+}
+EXPORT_SYMBOL_GPL(shake_page);
+
+/*
+ * Kill all processes that have a poisoned page mapped and then isolate
+ * the page.
+ *
+ * General strategy:
+ * Find all processes having the page mapped and kill them.
+ * But we keep a page reference around so that the page is not
+ * actually freed yet.
+ * Then stash the page away
+ *
+ * There's no convenient way to get back to mapped processes
+ * from the VMAs. So do a brute-force search over all
+ * running processes.
+ *
+ * Remember that machine checks are not common (or rather
+ * if they are common you have other problems), so this shouldn't
+ * be a performance issue.
+ *
+ * Also there are some races possible while we get from the
+ * error detection to actually handle it.
+ */
+
+struct to_kill {
+	struct list_head nd;
+	struct task_struct *tsk;
+	unsigned long addr;
+	char addr_valid;
+};
+
+/*
+ * Failure handling: if we can't find or can't kill a process there's
+ * not much we can do.	We just print a message and ignore otherwise.
+ */
+
+/*
+ * Schedule a process for later kill.
+ * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
+ * TBD would GFP_NOIO be enough?
+ */
+static void add_to_kill(struct task_struct *tsk, struct page *p,
+		       struct vm_area_struct *vma,
+		       struct list_head *to_kill,
+		       struct to_kill **tkc)
+{
+	struct to_kill *tk;
+
+	if (*tkc) {
+		tk = *tkc;
+		*tkc = NULL;
+	} else {
+		tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
+		if (!tk) {
+			printk(KERN_ERR
+		"MCE: Out of memory while machine check handling\n");
+			return;
+		}
+	}
+	tk->addr = page_address_in_vma(p, vma);
+	tk->addr_valid = 1;
+
+	/*
+	 * In theory we don't have to kill when the page was
+	 * munmaped. But it could be also a mremap. Since that's
+	 * likely very rare kill anyways just out of paranoia, but use
+	 * a SIGKILL because the error is not contained anymore.
+	 */
+	if (tk->addr == -EFAULT) {
+		pr_info("MCE: Unable to find user space address %lx in %s\n",
+			page_to_pfn(p), tsk->comm);
+		tk->addr_valid = 0;
+	}
+	get_task_struct(tsk);
+	tk->tsk = tsk;
+	list_add_tail(&tk->nd, to_kill);
+}
+
+/*
+ * Kill the processes that have been collected earlier.
+ *
+ * Only do anything when DOIT is set, otherwise just free the list
+ * (this is used for clean pages which do not need killing)
+ * Also when FAIL is set do a force kill because something went
+ * wrong earlier.
+ */
+static void kill_procs(struct list_head *to_kill, int forcekill, int trapno,
+			  int fail, struct page *page, unsigned long pfn,
+			  int flags)
+{
+	struct to_kill *tk, *next;
+
+	list_for_each_entry_safe (tk, next, to_kill, nd) {
+		if (forcekill) {
+			/*
+			 * In case something went wrong with munmapping
+			 * make sure the process doesn't catch the
+			 * signal and then access the memory. Just kill it.
+			 */
+			if (fail || tk->addr_valid == 0) {
+				printk(KERN_ERR
+		"MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
+					pfn, tk->tsk->comm, tk->tsk->pid);
+				force_sig(SIGKILL, tk->tsk);
+			}
+
+			/*
+			 * In theory the process could have mapped
+			 * something else on the address in-between. We could
+			 * check for that, but we need to tell the
+			 * process anyways.
+			 */
+			else if (kill_proc(tk->tsk, tk->addr, trapno,
+					      pfn, page, flags) < 0)
+				printk(KERN_ERR
+		"MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
+					pfn, tk->tsk->comm, tk->tsk->pid);
+		}
+		put_task_struct(tk->tsk);
+		kfree(tk);
+	}
+}
+
+/*
+ * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
+ * on behalf of the thread group. Return task_struct of the (first found)
+ * dedicated thread if found, and return NULL otherwise.
+ *
+ * We already hold read_lock(&tasklist_lock) in the caller, so we don't
+ * have to call rcu_read_lock/unlock() in this function.
+ */
+static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
+{
+	struct task_struct *t;
+
+	for_each_thread(tsk, t)
+		if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY))
+			return t;
+	return NULL;
+}
+
+/*
+ * Determine whether a given process is "early kill" process which expects
+ * to be signaled when some page under the process is hwpoisoned.
+ * Return task_struct of the dedicated thread (main thread unless explicitly
+ * specified) if the process is "early kill," and otherwise returns NULL.
+ */
+static struct task_struct *task_early_kill(struct task_struct *tsk,
+					   int force_early)
+{
+	struct task_struct *t;
+	if (!tsk->mm)
+		return NULL;
+	if (force_early)
+		return tsk;
+	t = find_early_kill_thread(tsk);
+	if (t)
+		return t;
+	if (sysctl_memory_failure_early_kill)
+		return tsk;
+	return NULL;
+}
+
+/*
+ * Collect processes when the error hit an anonymous page.
+ */
+static void collect_procs_anon(struct page *page, struct list_head *to_kill,
+			      struct to_kill **tkc, int force_early)
+{
+	struct vm_area_struct *vma;
+	struct task_struct *tsk;
+	struct anon_vma *av;
+	pgoff_t pgoff;
+
+	av = page_lock_anon_vma_read(page);
+	if (av == NULL)	/* Not actually mapped anymore */
+		return;
+
+	pgoff = page_to_pgoff(page);
+	read_lock(&tasklist_lock);
+	for_each_process (tsk) {
+		struct anon_vma_chain *vmac;
+		struct task_struct *t = task_early_kill(tsk, force_early);
+
+		if (!t)
+			continue;
+		anon_vma_interval_tree_foreach(vmac, &av->rb_root,
+					       pgoff, pgoff) {
+			vma = vmac->vma;
+			if (!page_mapped_in_vma(page, vma))
+				continue;
+			if (vma->vm_mm == t->mm)
+				add_to_kill(t, page, vma, to_kill, tkc);
+		}
+	}
+	read_unlock(&tasklist_lock);
+	page_unlock_anon_vma_read(av);
+}
+
+/*
+ * Collect processes when the error hit a file mapped page.
+ */
+static void collect_procs_file(struct page *page, struct list_head *to_kill,
+			      struct to_kill **tkc, int force_early)
+{
+	struct vm_area_struct *vma;
+	struct task_struct *tsk;
+	struct address_space *mapping = page->mapping;
+
+	i_mmap_lock_read(mapping);
+	read_lock(&tasklist_lock);
+	for_each_process(tsk) {
+		pgoff_t pgoff = page_to_pgoff(page);
+		struct task_struct *t = task_early_kill(tsk, force_early);
+
+		if (!t)
+			continue;
+		vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
+				      pgoff) {
+			/*
+			 * Send early kill signal to tasks where a vma covers
+			 * the page but the corrupted page is not necessarily
+			 * mapped it in its pte.
+			 * Assume applications who requested early kill want
+			 * to be informed of all such data corruptions.
+			 */
+			if (vma->vm_mm == t->mm)
+				add_to_kill(t, page, vma, to_kill, tkc);
+		}
+	}
+	read_unlock(&tasklist_lock);
+	i_mmap_unlock_read(mapping);
+}
+
+/*
+ * Collect the processes who have the corrupted page mapped to kill.
+ * This is done in two steps for locking reasons.
+ * First preallocate one tokill structure outside the spin locks,
+ * so that we can kill at least one process reasonably reliable.
+ */
+static void collect_procs(struct page *page, struct list_head *tokill,
+				int force_early)
+{
+	struct to_kill *tk;
+
+	if (!page->mapping)
+		return;
+
+	tk = kmalloc(sizeof(struct to_kill), GFP_NOIO);
+	if (!tk)
+		return;
+	if (PageAnon(page))
+		collect_procs_anon(page, tokill, &tk, force_early);
+	else
+		collect_procs_file(page, tokill, &tk, force_early);
+	kfree(tk);
+}
+
+static const char *action_name[] = {
+	[MF_IGNORED] = "Ignored",
+	[MF_FAILED] = "Failed",
+	[MF_DELAYED] = "Delayed",
+	[MF_RECOVERED] = "Recovered",
+};
+
+static const char * const action_page_types[] = {
+	[MF_MSG_KERNEL]			= "reserved kernel page",
+	[MF_MSG_KERNEL_HIGH_ORDER]	= "high-order kernel page",
+	[MF_MSG_SLAB]			= "kernel slab page",
+	[MF_MSG_DIFFERENT_COMPOUND]	= "different compound page after locking",
+	[MF_MSG_POISONED_HUGE]		= "huge page already hardware poisoned",
+	[MF_MSG_HUGE]			= "huge page",
+	[MF_MSG_FREE_HUGE]		= "free huge page",
+	[MF_MSG_UNMAP_FAILED]		= "unmapping failed page",
+	[MF_MSG_DIRTY_SWAPCACHE]	= "dirty swapcache page",
+	[MF_MSG_CLEAN_SWAPCACHE]	= "clean swapcache page",
+	[MF_MSG_DIRTY_MLOCKED_LRU]	= "dirty mlocked LRU page",
+	[MF_MSG_CLEAN_MLOCKED_LRU]	= "clean mlocked LRU page",
+	[MF_MSG_DIRTY_UNEVICTABLE_LRU]	= "dirty unevictable LRU page",
+	[MF_MSG_CLEAN_UNEVICTABLE_LRU]	= "clean unevictable LRU page",
+	[MF_MSG_DIRTY_LRU]		= "dirty LRU page",
+	[MF_MSG_CLEAN_LRU]		= "clean LRU page",
+	[MF_MSG_TRUNCATED_LRU]		= "already truncated LRU page",
+	[MF_MSG_BUDDY]			= "free buddy page",
+	[MF_MSG_BUDDY_2ND]		= "free buddy page (2nd try)",
+	[MF_MSG_UNKNOWN]		= "unknown page",
+};
+
+/*
+ * XXX: It is possible that a page is isolated from LRU cache,
+ * and then kept in swap cache or failed to remove from page cache.
+ * The page count will stop it from being freed by unpoison.
+ * Stress tests should be aware of this memory leak problem.
+ */
+static int delete_from_lru_cache(struct page *p)
+{
+	if (!isolate_lru_page(p)) {
+		/*
+		 * Clear sensible page flags, so that the buddy system won't
+		 * complain when the page is unpoison-and-freed.
+		 */
+		ClearPageActive(p);
+		ClearPageUnevictable(p);
+		/*
+		 * drop the page count elevated by isolate_lru_page()
+		 */
+		page_cache_release(p);
+		return 0;
+	}
+	return -EIO;
+}
+
+/*
+ * Error hit kernel page.
+ * Do nothing, try to be lucky and not touch this instead. For a few cases we
+ * could be more sophisticated.
+ */
+static int me_kernel(struct page *p, unsigned long pfn)
+{
+	return MF_IGNORED;
+}
+
+/*
+ * Page in unknown state. Do nothing.
+ */
+static int me_unknown(struct page *p, unsigned long pfn)
+{
+	printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn);
+	return MF_FAILED;
+}
+
+/*
+ * Clean (or cleaned) page cache page.
+ */
+static int me_pagecache_clean(struct page *p, unsigned long pfn)
+{
+	int err;
+	int ret = MF_FAILED;
+	struct address_space *mapping;
+
+	delete_from_lru_cache(p);
+
+	/*
+	 * For anonymous pages we're done the only reference left
+	 * should be the one m_f() holds.
+	 */
+	if (PageAnon(p))
+		return MF_RECOVERED;
+
+	/*
+	 * Now truncate the page in the page cache. This is really
+	 * more like a "temporary hole punch"
+	 * Don't do this for block devices when someone else
+	 * has a reference, because it could be file system metadata
+	 * and that's not safe to truncate.
+	 */
+	mapping = page_mapping(p);
+	if (!mapping) {
+		/*
+		 * Page has been teared down in the meanwhile
+		 */
+		return MF_FAILED;
+	}
+
+	/*
+	 * Truncation is a bit tricky. Enable it per file system for now.
+	 *
+	 * Open: to take i_mutex or not for this? Right now we don't.
+	 */
+	if (mapping->a_ops->error_remove_page) {
+		err = mapping->a_ops->error_remove_page(mapping, p);
+		if (err != 0) {
+			printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n",
+					pfn, err);
+		} else if (page_has_private(p) &&
+				!try_to_release_page(p, GFP_NOIO)) {
+			pr_info("MCE %#lx: failed to release buffers\n", pfn);
+		} else {
+			ret = MF_RECOVERED;
+		}
+	} else {
+		/*
+		 * If the file system doesn't support it just invalidate
+		 * This fails on dirty or anything with private pages
+		 */
+		if (invalidate_inode_page(p))
+			ret = MF_RECOVERED;
+		else
+			printk(KERN_INFO "MCE %#lx: Failed to invalidate\n",
+				pfn);
+	}
+	return ret;
+}
+
+/*
+ * Dirty pagecache page
+ * Issues: when the error hit a hole page the error is not properly
+ * propagated.
+ */
+static int me_pagecache_dirty(struct page *p, unsigned long pfn)
+{
+	struct address_space *mapping = page_mapping(p);
+
+	SetPageError(p);
+	/* TBD: print more information about the file. */
+	if (mapping) {
+		/*
+		 * IO error will be reported by write(), fsync(), etc.
+		 * who check the mapping.
+		 * This way the application knows that something went
+		 * wrong with its dirty file data.
+		 *
+		 * There's one open issue:
+		 *
+		 * The EIO will be only reported on the next IO
+		 * operation and then cleared through the IO map.
+		 * Normally Linux has two mechanisms to pass IO error
+		 * first through the AS_EIO flag in the address space
+		 * and then through the PageError flag in the page.
+		 * Since we drop pages on memory failure handling the
+		 * only mechanism open to use is through AS_AIO.
+		 *
+		 * This has the disadvantage that it gets cleared on
+		 * the first operation that returns an error, while
+		 * the PageError bit is more sticky and only cleared
+		 * when the page is reread or dropped.  If an
+		 * application assumes it will always get error on
+		 * fsync, but does other operations on the fd before
+		 * and the page is dropped between then the error
+		 * will not be properly reported.
+		 *
+		 * This can already happen even without hwpoisoned
+		 * pages: first on metadata IO errors (which only
+		 * report through AS_EIO) or when the page is dropped
+		 * at the wrong time.
+		 *
+		 * So right now we assume that the application DTRT on
+		 * the first EIO, but we're not worse than other parts
+		 * of the kernel.
+		 */
+		mapping_set_error(mapping, EIO);
+	}
+
+	return me_pagecache_clean(p, pfn);
+}
+
+/*
+ * Clean and dirty swap cache.
+ *
+ * Dirty swap cache page is tricky to handle. The page could live both in page
+ * cache and swap cache(ie. page is freshly swapped in). So it could be
+ * referenced concurrently by 2 types of PTEs:
+ * normal PTEs and swap PTEs. We try to handle them consistently by calling
+ * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
+ * and then
+ *      - clear dirty bit to prevent IO
+ *      - remove from LRU
+ *      - but keep in the swap cache, so that when we return to it on
+ *        a later page fault, we know the application is accessing
+ *        corrupted data and shall be killed (we installed simple
+ *        interception code in do_swap_page to catch it).
+ *
+ * Clean swap cache pages can be directly isolated. A later page fault will
+ * bring in the known good data from disk.
+ */
+static int me_swapcache_dirty(struct page *p, unsigned long pfn)
+{
+	ClearPageDirty(p);
+	/* Trigger EIO in shmem: */
+	ClearPageUptodate(p);
+
+	if (!delete_from_lru_cache(p))
+		return MF_DELAYED;
+	else
+		return MF_FAILED;
+}
+
+static int me_swapcache_clean(struct page *p, unsigned long pfn)
+{
+	delete_from_swap_cache(p);
+
+	if (!delete_from_lru_cache(p))
+		return MF_RECOVERED;
+	else
+		return MF_FAILED;
+}
+
+/*
+ * Huge pages. Needs work.
+ * Issues:
+ * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
+ *   To narrow down kill region to one page, we need to break up pmd.
+ */
+static int me_huge_page(struct page *p, unsigned long pfn)
+{
+	int res = 0;
+	struct page *hpage = compound_head(p);
+
+	if (!PageHuge(hpage))
+		return MF_DELAYED;
+
+	/*
+	 * We can safely recover from error on free or reserved (i.e.
+	 * not in-use) hugepage by dequeuing it from freelist.
+	 * To check whether a hugepage is in-use or not, we can't use
+	 * page->lru because it can be used in other hugepage operations,
+	 * such as __unmap_hugepage_range() and gather_surplus_pages().
+	 * So instead we use page_mapping() and PageAnon().
+	 * We assume that this function is called with page lock held,
+	 * so there is no race between isolation and mapping/unmapping.
+	 */
+	if (!(page_mapping(hpage) || PageAnon(hpage))) {
+		res = dequeue_hwpoisoned_huge_page(hpage);
+		if (!res)
+			return MF_RECOVERED;
+	}
+	return MF_DELAYED;
+}
+
+/*
+ * Various page states we can handle.
+ *
+ * A page state is defined by its current page->flags bits.
+ * The table matches them in order and calls the right handler.
+ *
+ * This is quite tricky because we can access page at any time
+ * in its live cycle, so all accesses have to be extremely careful.
+ *
+ * This is not complete. More states could be added.
+ * For any missing state don't attempt recovery.
+ */
+
+#define dirty		(1UL << PG_dirty)
+#define sc		(1UL << PG_swapcache)
+#define unevict		(1UL << PG_unevictable)
+#define mlock		(1UL << PG_mlocked)
+#define writeback	(1UL << PG_writeback)
+#define lru		(1UL << PG_lru)
+#define swapbacked	(1UL << PG_swapbacked)
+#define head		(1UL << PG_head)
+#define slab		(1UL << PG_slab)
+#define reserved	(1UL << PG_reserved)
+
+static struct page_state {
+	unsigned long mask;
+	unsigned long res;
+	enum mf_action_page_type type;
+	int (*action)(struct page *p, unsigned long pfn);
+} error_states[] = {
+	{ reserved,	reserved,	MF_MSG_KERNEL,	me_kernel },
+	/*
+	 * free pages are specially detected outside this table:
+	 * PG_buddy pages only make a small fraction of all free pages.
+	 */
+
+	/*
+	 * Could in theory check if slab page is free or if we can drop
+	 * currently unused objects without touching them. But just
+	 * treat it as standard kernel for now.
+	 */
+	{ slab,		slab,		MF_MSG_SLAB,	me_kernel },
+
+	{ head,		head,		MF_MSG_HUGE,		me_huge_page },
+
+	{ sc|dirty,	sc|dirty,	MF_MSG_DIRTY_SWAPCACHE,	me_swapcache_dirty },
+	{ sc|dirty,	sc,		MF_MSG_CLEAN_SWAPCACHE,	me_swapcache_clean },
+
+	{ mlock|dirty,	mlock|dirty,	MF_MSG_DIRTY_MLOCKED_LRU,	me_pagecache_dirty },
+	{ mlock|dirty,	mlock,		MF_MSG_CLEAN_MLOCKED_LRU,	me_pagecache_clean },
+
+	{ unevict|dirty, unevict|dirty,	MF_MSG_DIRTY_UNEVICTABLE_LRU,	me_pagecache_dirty },
+	{ unevict|dirty, unevict,	MF_MSG_CLEAN_UNEVICTABLE_LRU,	me_pagecache_clean },
+
+	{ lru|dirty,	lru|dirty,	MF_MSG_DIRTY_LRU,	me_pagecache_dirty },
+	{ lru|dirty,	lru,		MF_MSG_CLEAN_LRU,	me_pagecache_clean },
+
+	/*
+	 * Catchall entry: must be at end.
+	 */
+	{ 0,		0,		MF_MSG_UNKNOWN,	me_unknown },
+};
+
+#undef dirty
+#undef sc
+#undef unevict
+#undef mlock
+#undef writeback
+#undef lru
+#undef swapbacked
+#undef head
+#undef tail
+#undef compound
+#undef slab
+#undef reserved
+
+/*
+ * "Dirty/Clean" indication is not 100% accurate due to the possibility of
+ * setting PG_dirty outside page lock. See also comment above set_page_dirty().
+ */
+static void action_result(unsigned long pfn, enum mf_action_page_type type,
+			  enum mf_result result)
+{
+	trace_memory_failure_event(pfn, type, result);
+
+	pr_err("MCE %#lx: recovery action for %s: %s\n",
+		pfn, action_page_types[type], action_name[result]);
+}
+
+static int page_action(struct page_state *ps, struct page *p,
+			unsigned long pfn)
+{
+	int result;
+	int count;
+
+	result = ps->action(p, pfn);
+
+	count = page_count(p) - 1;
+	if (ps->action == me_swapcache_dirty && result == MF_DELAYED)
+		count--;
+	if (count != 0) {
+		printk(KERN_ERR
+		       "MCE %#lx: %s still referenced by %d users\n",
+		       pfn, action_page_types[ps->type], count);
+		result = MF_FAILED;
+	}
+	action_result(pfn, ps->type, result);
+
+	/* Could do more checks here if page looks ok */
+	/*
+	 * Could adjust zone counters here to correct for the missing page.
+	 */
+
+	return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
+}
+
+/**
+ * get_hwpoison_page() - Get refcount for memory error handling:
+ * @page:	raw error page (hit by memory error)
+ *
+ * Return: return 0 if failed to grab the refcount, otherwise true (some
+ * non-zero value.)
+ */
+int get_hwpoison_page(struct page *page)
+{
+	struct page *head = compound_head(page);
+
+	if (PageHuge(head))
+		return get_page_unless_zero(head);
+
+	/*
+	 * Thp tail page has special refcounting rule (refcount of tail pages
+	 * is stored in ->_mapcount,) so we can't call get_page_unless_zero()
+	 * directly for tail pages.
+	 */
+	if (PageTransHuge(head)) {
+		/*
+		 * Non anonymous thp exists only in allocation/free time. We
+		 * can't handle such a case correctly, so let's give it up.
+		 * This should be better than triggering BUG_ON when kernel
+		 * tries to touch the "partially handled" page.
+		 */
+		if (!PageAnon(head)) {
+			pr_err("MCE: %#lx: non anonymous thp\n",
+				page_to_pfn(page));
+			return 0;
+		}
+
+		if (get_page_unless_zero(head)) {
+			if (PageTail(page))
+				get_page(page);
+			return 1;
+		} else {
+			return 0;
+		}
+	}
+
+	return get_page_unless_zero(page);
+}
+EXPORT_SYMBOL_GPL(get_hwpoison_page);
+
+/**
+ * put_hwpoison_page() - Put refcount for memory error handling:
+ * @page:	raw error page (hit by memory error)
+ */
+void put_hwpoison_page(struct page *page)
+{
+	struct page *head = compound_head(page);
+
+	if (PageHuge(head)) {
+		put_page(head);
+		return;
+	}
+
+	if (PageTransHuge(head))
+		if (page != head)
+			put_page(head);
+
+	put_page(page);
+}
+EXPORT_SYMBOL_GPL(put_hwpoison_page);
+
+/*
+ * Do all that is necessary to remove user space mappings. Unmap
+ * the pages and send SIGBUS to the processes if the data was dirty.
+ */
+static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
+				  int trapno, int flags, struct page **hpagep)
+{
+	enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
+	struct address_space *mapping;
+	LIST_HEAD(tokill);
+	int ret;
+	int kill = 1, forcekill;
+	struct page *hpage = *hpagep;
+
+	/*
+	 * Here we are interested only in user-mapped pages, so skip any
+	 * other types of pages.
+	 */
+	if (PageReserved(p) || PageSlab(p))
+		return SWAP_SUCCESS;
+	if (!(PageLRU(hpage) || PageHuge(p)))
+		return SWAP_SUCCESS;
+
+	/*
+	 * This check implies we don't kill processes if their pages
+	 * are in the swap cache early. Those are always late kills.
+	 */
+	if (!page_mapped(hpage))
+		return SWAP_SUCCESS;
+
+	if (PageKsm(p)) {
+		pr_err("MCE %#lx: can't handle KSM pages.\n", pfn);
+		return SWAP_FAIL;
+	}
+
+	if (PageSwapCache(p)) {
+		printk(KERN_ERR
+		       "MCE %#lx: keeping poisoned page in swap cache\n", pfn);
+		ttu |= TTU_IGNORE_HWPOISON;
+	}
+
+	/*
+	 * Propagate the dirty bit from PTEs to struct page first, because we
+	 * need this to decide if we should kill or just drop the page.
+	 * XXX: the dirty test could be racy: set_page_dirty() may not always
+	 * be called inside page lock (it's recommended but not enforced).
+	 */
+	mapping = page_mapping(hpage);
+	if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
+	    mapping_cap_writeback_dirty(mapping)) {
+		if (page_mkclean(hpage)) {
+			SetPageDirty(hpage);
+		} else {
+			kill = 0;
+			ttu |= TTU_IGNORE_HWPOISON;
+			printk(KERN_INFO
+	"MCE %#lx: corrupted page was clean: dropped without side effects\n",
+				pfn);
+		}
+	}
+
+	/*
+	 * First collect all the processes that have the page
+	 * mapped in dirty form.  This has to be done before try_to_unmap,
+	 * because ttu takes the rmap data structures down.
+	 *
+	 * Error handling: We ignore errors here because
+	 * there's nothing that can be done.
+	 */
+	if (kill)
+		collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
+
+	ret = try_to_unmap(hpage, ttu);
+	if (ret != SWAP_SUCCESS)
+		printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
+				pfn, page_mapcount(hpage));
+
+	/*
+	 * Now that the dirty bit has been propagated to the
+	 * struct page and all unmaps done we can decide if
+	 * killing is needed or not.  Only kill when the page
+	 * was dirty or the process is not restartable,
+	 * otherwise the tokill list is merely
+	 * freed.  When there was a problem unmapping earlier
+	 * use a more force-full uncatchable kill to prevent
+	 * any accesses to the poisoned memory.
+	 */
+	forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
+	kill_procs(&tokill, forcekill, trapno,
+		      ret != SWAP_SUCCESS, p, pfn, flags);
+
+	return ret;
+}
+
+static void set_page_hwpoison_huge_page(struct page *hpage)
+{
+	int i;
+	int nr_pages = 1 << compound_order(hpage);
+	for (i = 0; i < nr_pages; i++)
+		SetPageHWPoison(hpage + i);
+}
+
+static void clear_page_hwpoison_huge_page(struct page *hpage)
+{
+	int i;
+	int nr_pages = 1 << compound_order(hpage);
+	for (i = 0; i < nr_pages; i++)
+		ClearPageHWPoison(hpage + i);
+}
+
+/**
+ * memory_failure - Handle memory failure of a page.
+ * @pfn: Page Number of the corrupted page
+ * @trapno: Trap number reported in the signal to user space.
+ * @flags: fine tune action taken
+ *
+ * This function is called by the low level machine check code
+ * of an architecture when it detects hardware memory corruption
+ * of a page. It tries its best to recover, which includes
+ * dropping pages, killing processes etc.
+ *
+ * The function is primarily of use for corruptions that
+ * happen outside the current execution context (e.g. when
+ * detected by a background scrubber)
+ *
+ * Must run in process context (e.g. a work queue) with interrupts
+ * enabled and no spinlocks hold.
+ */
+int memory_failure(unsigned long pfn, int trapno, int flags)
+{
+	struct page_state *ps;
+	struct page *p;
+	struct page *hpage;
+	struct page *orig_head;
+	int res;
+	unsigned int nr_pages;
+	unsigned long page_flags;
+
+	if (!sysctl_memory_failure_recovery)
+		panic("Memory failure from trap %d on page %lx", trapno, pfn);
+
+	if (!pfn_valid(pfn)) {
+		printk(KERN_ERR
+		       "MCE %#lx: memory outside kernel control\n",
+		       pfn);
+		return -ENXIO;
+	}
+
+	p = pfn_to_page(pfn);
+	orig_head = hpage = compound_head(p);
+	if (TestSetPageHWPoison(p)) {
+		printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
+		return 0;
+	}
+
+	/*
+	 * Currently errors on hugetlbfs pages are measured in hugepage units,
+	 * so nr_pages should be 1 << compound_order.  OTOH when errors are on
+	 * transparent hugepages, they are supposed to be split and error
+	 * measurement is done in normal page units.  So nr_pages should be one
+	 * in this case.
+	 */
+	if (PageHuge(p))
+		nr_pages = 1 << compound_order(hpage);
+	else /* normal page or thp */
+		nr_pages = 1;
+	num_poisoned_pages_add(nr_pages);
+
+	/*
+	 * We need/can do nothing about count=0 pages.
+	 * 1) it's a free page, and therefore in safe hand:
+	 *    prep_new_page() will be the gate keeper.
+	 * 2) it's a free hugepage, which is also safe:
+	 *    an affected hugepage will be dequeued from hugepage freelist,
+	 *    so there's no concern about reusing it ever after.
+	 * 3) it's part of a non-compound high order page.
+	 *    Implies some kernel user: cannot stop them from
+	 *    R/W the page; let's pray that the page has been
+	 *    used and will be freed some time later.
+	 * In fact it's dangerous to directly bump up page count from 0,
+	 * that may make page_freeze_refs()/page_unfreeze_refs() mismatch.
+	 */
+	if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
+		if (is_free_buddy_page(p)) {
+			action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
+			return 0;
+		} else if (PageHuge(hpage)) {
+			/*
+			 * Check "filter hit" and "race with other subpage."
+			 */
+			lock_page(hpage);
+			if (PageHWPoison(hpage)) {
+				if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
+				    || (p != hpage && TestSetPageHWPoison(hpage))) {
+					num_poisoned_pages_sub(nr_pages);
+					unlock_page(hpage);
+					return 0;
+				}
+			}
+			set_page_hwpoison_huge_page(hpage);
+			res = dequeue_hwpoisoned_huge_page(hpage);
+			action_result(pfn, MF_MSG_FREE_HUGE,
+				      res ? MF_IGNORED : MF_DELAYED);
+			unlock_page(hpage);
+			return res;
+		} else {
+			action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
+			return -EBUSY;
+		}
+	}
+
+	if (!PageHuge(p) && PageTransHuge(hpage)) {
+		if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) {
+			if (!PageAnon(hpage))
+				pr_err("MCE: %#lx: non anonymous thp\n", pfn);
+			else
+				pr_err("MCE: %#lx: thp split failed\n", pfn);
+			if (TestClearPageHWPoison(p))
+				num_poisoned_pages_sub(nr_pages);
+			put_hwpoison_page(p);
+			return -EBUSY;
+		}
+		VM_BUG_ON_PAGE(!page_count(p), p);
+		hpage = compound_head(p);
+	}
+
+	/*
+	 * We ignore non-LRU pages for good reasons.
+	 * - PG_locked is only well defined for LRU pages and a few others
+	 * - to avoid races with __set_page_locked()
+	 * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
+	 * The check (unnecessarily) ignores LRU pages being isolated and
+	 * walked by the page reclaim code, however that's not a big loss.
+	 */
+	if (!PageHuge(p)) {
+		if (!PageLRU(p))
+			shake_page(p, 0);
+		if (!PageLRU(p)) {
+			/*
+			 * shake_page could have turned it free.
+			 */
+			if (is_free_buddy_page(p)) {
+				if (flags & MF_COUNT_INCREASED)
+					action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
+				else
+					action_result(pfn, MF_MSG_BUDDY_2ND,
+						      MF_DELAYED);
+				return 0;
+			}
+		}
+	}
+
+	lock_page(hpage);
+
+	/*
+	 * The page could have changed compound pages during the locking.
+	 * If this happens just bail out.
+	 */
+	if (PageCompound(p) && compound_head(p) != orig_head) {
+		action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
+		res = -EBUSY;
+		goto out;
+	}
+
+	/*
+	 * We use page flags to determine what action should be taken, but
+	 * the flags can be modified by the error containment action.  One
+	 * example is an mlocked page, where PG_mlocked is cleared by
+	 * page_remove_rmap() in try_to_unmap_one(). So to determine page status
+	 * correctly, we save a copy of the page flags at this time.
+	 */
+	if (PageHuge(p))
+		page_flags = hpage->flags;
+	else
+		page_flags = p->flags;
+
+	/*
+	 * unpoison always clear PG_hwpoison inside page lock
+	 */
+	if (!PageHWPoison(p)) {
+		printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
+		num_poisoned_pages_sub(nr_pages);
+		unlock_page(hpage);
+		put_hwpoison_page(hpage);
+		return 0;
+	}
+	if (hwpoison_filter(p)) {
+		if (TestClearPageHWPoison(p))
+			num_poisoned_pages_sub(nr_pages);
+		unlock_page(hpage);
+		put_hwpoison_page(hpage);
+		return 0;
+	}
+
+	if (!PageHuge(p) && !PageTransTail(p) && !PageLRU(p))
+		goto identify_page_state;
+
+	/*
+	 * For error on the tail page, we should set PG_hwpoison
+	 * on the head page to show that the hugepage is hwpoisoned
+	 */
+	if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) {
+		action_result(pfn, MF_MSG_POISONED_HUGE, MF_IGNORED);
+		unlock_page(hpage);
+		put_hwpoison_page(hpage);
+		return 0;
+	}
+	/*
+	 * Set PG_hwpoison on all pages in an error hugepage,
+	 * because containment is done in hugepage unit for now.
+	 * Since we have done TestSetPageHWPoison() for the head page with
+	 * page lock held, we can safely set PG_hwpoison bits on tail pages.
+	 */
+	if (PageHuge(p))
+		set_page_hwpoison_huge_page(hpage);
+
+	/*
+	 * It's very difficult to mess with pages currently under IO
+	 * and in many cases impossible, so we just avoid it here.
+	 */
+	wait_on_page_writeback(p);
+
+	/*
+	 * Now take care of user space mappings.
+	 * Abort on fail: __delete_from_page_cache() assumes unmapped page.
+	 *
+	 * When the raw error page is thp tail page, hpage points to the raw
+	 * page after thp split.
+	 */
+	if (hwpoison_user_mappings(p, pfn, trapno, flags, &hpage)
+	    != SWAP_SUCCESS) {
+		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
+		res = -EBUSY;
+		goto out;
+	}
+
+	/*
+	 * Torn down by someone else?
+	 */
+	if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
+		action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
+		res = -EBUSY;
+		goto out;
+	}
+
+identify_page_state:
+	res = -EBUSY;
+	/*
+	 * The first check uses the current page flags which may not have any
+	 * relevant information. The second check with the saved page flagss is
+	 * carried out only if the first check can't determine the page status.
+	 */
+	for (ps = error_states;; ps++)
+		if ((p->flags & ps->mask) == ps->res)
+			break;
+
+	page_flags |= (p->flags & (1UL << PG_dirty));
+
+	if (!ps->mask)
+		for (ps = error_states;; ps++)
+			if ((page_flags & ps->mask) == ps->res)
+				break;
+	res = page_action(ps, p, pfn);
+out:
+	unlock_page(hpage);
+	return res;
+}
+EXPORT_SYMBOL_GPL(memory_failure);
+
+#define MEMORY_FAILURE_FIFO_ORDER	4
+#define MEMORY_FAILURE_FIFO_SIZE	(1 << MEMORY_FAILURE_FIFO_ORDER)
+
+struct memory_failure_entry {
+	unsigned long pfn;
+	int trapno;
+	int flags;
+};
+
+struct memory_failure_cpu {
+	DECLARE_KFIFO(fifo, struct memory_failure_entry,
+		      MEMORY_FAILURE_FIFO_SIZE);
+	spinlock_t lock;
+	struct work_struct work;
+};
+
+static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);
+
+/**
+ * memory_failure_queue - Schedule handling memory failure of a page.
+ * @pfn: Page Number of the corrupted page
+ * @trapno: Trap number reported in the signal to user space.
+ * @flags: Flags for memory failure handling
+ *
+ * This function is called by the low level hardware error handler
+ * when it detects hardware memory corruption of a page. It schedules
+ * the recovering of error page, including dropping pages, killing
+ * processes etc.
+ *
+ * The function is primarily of use for corruptions that
+ * happen outside the current execution context (e.g. when
+ * detected by a background scrubber)
+ *
+ * Can run in IRQ context.
+ */
+void memory_failure_queue(unsigned long pfn, int trapno, int flags)
+{
+	struct memory_failure_cpu *mf_cpu;
+	unsigned long proc_flags;
+	struct memory_failure_entry entry = {
+		.pfn =		pfn,
+		.trapno =	trapno,
+		.flags =	flags,
+	};
+
+	mf_cpu = &get_cpu_var(memory_failure_cpu);
+	spin_lock_irqsave(&mf_cpu->lock, proc_flags);
+	if (kfifo_put(&mf_cpu->fifo, entry))
+		schedule_work_on(smp_processor_id(), &mf_cpu->work);
+	else
+		pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n",
+		       pfn);
+	spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
+	put_cpu_var(memory_failure_cpu);
+}
+EXPORT_SYMBOL_GPL(memory_failure_queue);
+
+static void memory_failure_work_func(struct work_struct *work)
+{
+	struct memory_failure_cpu *mf_cpu;
+	struct memory_failure_entry entry = { 0, };
+	unsigned long proc_flags;
+	int gotten;
+
+	mf_cpu = this_cpu_ptr(&memory_failure_cpu);
+	for (;;) {
+		spin_lock_irqsave(&mf_cpu->lock, proc_flags);
+		gotten = kfifo_get(&mf_cpu->fifo, &entry);
+		spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
+		if (!gotten)
+			break;
+		if (entry.flags & MF_SOFT_OFFLINE)
+			soft_offline_page(pfn_to_page(entry.pfn), entry.flags);
+		else
+			memory_failure(entry.pfn, entry.trapno, entry.flags);
+	}
+}
+
+static int __init memory_failure_init(void)
+{
+	struct memory_failure_cpu *mf_cpu;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		mf_cpu = &per_cpu(memory_failure_cpu, cpu);
+		spin_lock_init(&mf_cpu->lock);
+		INIT_KFIFO(mf_cpu->fifo);
+		INIT_WORK(&mf_cpu->work, memory_failure_work_func);
+	}
+
+	return 0;
+}
+core_initcall(memory_failure_init);
+
+#define unpoison_pr_info(fmt, pfn, rs)			\
+({							\
+	if (__ratelimit(rs))				\
+		pr_info(fmt, pfn);			\
+})
+
+/**
+ * unpoison_memory - Unpoison a previously poisoned page
+ * @pfn: Page number of the to be unpoisoned page
+ *
+ * Software-unpoison a page that has been poisoned by
+ * memory_failure() earlier.
+ *
+ * This is only done on the software-level, so it only works
+ * for linux injected failures, not real hardware failures
+ *
+ * Returns 0 for success, otherwise -errno.
+ */
+int unpoison_memory(unsigned long pfn)
+{
+	struct page *page;
+	struct page *p;
+	int freeit = 0;
+	unsigned int nr_pages;
+	static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
+					DEFAULT_RATELIMIT_BURST);
+
+	if (!pfn_valid(pfn))
+		return -ENXIO;
+
+	p = pfn_to_page(pfn);
+	page = compound_head(p);
+
+	if (!PageHWPoison(p)) {
+		unpoison_pr_info("MCE: Page was already unpoisoned %#lx\n",
+				 pfn, &unpoison_rs);
+		return 0;
+	}
+
+	if (page_count(page) > 1) {
+		unpoison_pr_info("MCE: Someone grabs the hwpoison page %#lx\n",
+				 pfn, &unpoison_rs);
+		return 0;
+	}
+
+	if (page_mapped(page)) {
+		unpoison_pr_info("MCE: Someone maps the hwpoison page %#lx\n",
+				 pfn, &unpoison_rs);
+		return 0;
+	}
+
+	if (page_mapping(page)) {
+		unpoison_pr_info("MCE: the hwpoison page has non-NULL mapping %#lx\n",
+				 pfn, &unpoison_rs);
+		return 0;
+	}
+
+	/*
+	 * unpoison_memory() can encounter thp only when the thp is being
+	 * worked by memory_failure() and the page lock is not held yet.
+	 * In such case, we yield to memory_failure() and make unpoison fail.
+	 */
+	if (!PageHuge(page) && PageTransHuge(page)) {
+		unpoison_pr_info("MCE: Memory failure is now running on %#lx\n",
+				 pfn, &unpoison_rs);
+		return 0;
+	}
+
+	nr_pages = 1 << compound_order(page);
+
+	if (!get_hwpoison_page(p)) {
+		/*
+		 * Since HWPoisoned hugepage should have non-zero refcount,
+		 * race between memory failure and unpoison seems to happen.
+		 * In such case unpoison fails and memory failure runs
+		 * to the end.
+		 */
+		if (PageHuge(page)) {
+			unpoison_pr_info("MCE: Memory failure is now running on free hugepage %#lx\n",
+					 pfn, &unpoison_rs);
+			return 0;
+		}
+		if (TestClearPageHWPoison(p))
+			num_poisoned_pages_dec();
+		unpoison_pr_info("MCE: Software-unpoisoned free page %#lx\n",
+				 pfn, &unpoison_rs);
+		return 0;
+	}
+
+	lock_page(page);
+	/*
+	 * This test is racy because PG_hwpoison is set outside of page lock.
+	 * That's acceptable because that won't trigger kernel panic. Instead,
+	 * the PG_hwpoison page will be caught and isolated on the entrance to
+	 * the free buddy page pool.
+	 */
+	if (TestClearPageHWPoison(page)) {
+		unpoison_pr_info("MCE: Software-unpoisoned page %#lx\n",
+				 pfn, &unpoison_rs);
+		num_poisoned_pages_sub(nr_pages);
+		freeit = 1;
+		if (PageHuge(page))
+			clear_page_hwpoison_huge_page(page);
+	}
+	unlock_page(page);
+
+	put_hwpoison_page(page);
+	if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1))
+		put_hwpoison_page(page);
+
+	return 0;
+}
+EXPORT_SYMBOL(unpoison_memory);
+
+static struct page *new_page(struct page *p, unsigned long private, int **x)
+{
+	int nid = page_to_nid(p);
+	if (PageHuge(p))
+		return alloc_huge_page_node(page_hstate(compound_head(p)),
+						   nid);
+	else
+		return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0);
+}
+
+/*
+ * Safely get reference count of an arbitrary page.
+ * Returns 0 for a free page, -EIO for a zero refcount page
+ * that is not free, and 1 for any other page type.
+ * For 1 the page is returned with increased page count, otherwise not.
+ */
+static int __get_any_page(struct page *p, unsigned long pfn, int flags)
+{
+	int ret;
+
+	if (flags & MF_COUNT_INCREASED)
+		return 1;
+
+	/*
+	 * When the target page is a free hugepage, just remove it
+	 * from free hugepage list.
+	 */
+	if (!get_hwpoison_page(p)) {
+		if (PageHuge(p)) {
+			pr_info("%s: %#lx free huge page\n", __func__, pfn);
+			ret = 0;
+		} else if (is_free_buddy_page(p)) {
+			pr_info("%s: %#lx free buddy page\n", __func__, pfn);
+			ret = 0;
+		} else {
+			pr_info("%s: %#lx: unknown zero refcount page type %lx\n",
+				__func__, pfn, p->flags);
+			ret = -EIO;
+		}
+	} else {
+		/* Not a free page */
+		ret = 1;
+	}
+	return ret;
+}
+
+static int get_any_page(struct page *page, unsigned long pfn, int flags)
+{
+	int ret = __get_any_page(page, pfn, flags);
+
+	if (ret == 1 && !PageHuge(page) && !PageLRU(page)) {
+		/*
+		 * Try to free it.
+		 */
+		put_hwpoison_page(page);
+		shake_page(page, 1);
+
+		/*
+		 * Did it turn free?
+		 */
+		ret = __get_any_page(page, pfn, 0);
+		if (ret == 1 && !PageLRU(page)) {
+			/* Drop page reference which is from __get_any_page() */
+			put_hwpoison_page(page);
+			pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
+				pfn, page->flags);
+			return -EIO;
+		}
+	}
+	return ret;
+}
+
+static int soft_offline_huge_page(struct page *page, int flags)
+{
+	int ret;
+	unsigned long pfn = page_to_pfn(page);
+	struct page *hpage = compound_head(page);
+	LIST_HEAD(pagelist);
+
+	/*
+	 * This double-check of PageHWPoison is to avoid the race with
+	 * memory_failure(). See also comment in __soft_offline_page().
+	 */
+	lock_page(hpage);
+	if (PageHWPoison(hpage)) {
+		unlock_page(hpage);
+		put_hwpoison_page(hpage);
+		pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
+		return -EBUSY;
+	}
+	unlock_page(hpage);
+
+	ret = isolate_huge_page(hpage, &pagelist);
+	/*
+	 * get_any_page() and isolate_huge_page() takes a refcount each,
+	 * so need to drop one here.
+	 */
+	put_hwpoison_page(hpage);
+	if (!ret) {
+		pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
+		return -EBUSY;
+	}
+
+	ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
+				MIGRATE_SYNC, MR_MEMORY_FAILURE);
+	if (ret) {
+		pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
+			pfn, ret, page->flags);
+		if (!list_empty(&pagelist))
+			putback_movable_pages(&pagelist);
+		if (ret > 0)
+			ret = -EIO;
+	} else {
+		/* overcommit hugetlb page will be freed to buddy */
+		if (PageHuge(page)) {
+			set_page_hwpoison_huge_page(hpage);
+			dequeue_hwpoisoned_huge_page(hpage);
+			num_poisoned_pages_add(1 << compound_order(hpage));
+		} else {
+			SetPageHWPoison(page);
+			num_poisoned_pages_inc();
+		}
+	}
+	return ret;
+}
+
+static int __soft_offline_page(struct page *page, int flags)
+{
+	int ret;
+	unsigned long pfn = page_to_pfn(page);
+
+	/*
+	 * Check PageHWPoison again inside page lock because PageHWPoison
+	 * is set by memory_failure() outside page lock. Note that
+	 * memory_failure() also double-checks PageHWPoison inside page lock,
+	 * so there's no race between soft_offline_page() and memory_failure().
+	 */
+	lock_page(page);
+	wait_on_page_writeback(page);
+	if (PageHWPoison(page)) {
+		unlock_page(page);
+		put_hwpoison_page(page);
+		pr_info("soft offline: %#lx page already poisoned\n", pfn);
+		return -EBUSY;
+	}
+	/*
+	 * Try to invalidate first. This should work for
+	 * non dirty unmapped page cache pages.
+	 */
+	ret = invalidate_inode_page(page);
+	unlock_page(page);
+	/*
+	 * RED-PEN would be better to keep it isolated here, but we
+	 * would need to fix isolation locking first.
+	 */
+	if (ret == 1) {
+		put_hwpoison_page(page);
+		pr_info("soft_offline: %#lx: invalidated\n", pfn);
+		SetPageHWPoison(page);
+		num_poisoned_pages_inc();
+		return 0;
+	}
+
+	/*
+	 * Simple invalidation didn't work.
+	 * Try to migrate to a new page instead. migrate.c
+	 * handles a large number of cases for us.
+	 */
+	ret = isolate_lru_page(page);
+	/*
+	 * Drop page reference which is came from get_any_page()
+	 * successful isolate_lru_page() already took another one.
+	 */
+	put_hwpoison_page(page);
+	if (!ret) {
+		LIST_HEAD(pagelist);
+		inc_zone_page_state(page, NR_ISOLATED_ANON +
+					page_is_file_cache(page));
+		list_add(&page->lru, &pagelist);
+		ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
+					MIGRATE_SYNC, MR_MEMORY_FAILURE);
+		if (ret) {
+			if (!list_empty(&pagelist)) {
+				list_del(&page->lru);
+				dec_zone_page_state(page, NR_ISOLATED_ANON +
+						page_is_file_cache(page));
+				putback_lru_page(page);
+			}
+
+			pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
+				pfn, ret, page->flags);
+			if (ret > 0)
+				ret = -EIO;
+		}
+	} else {
+		pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
+			pfn, ret, page_count(page), page->flags);
+	}
+	return ret;
+}
+
+/**
+ * soft_offline_page - Soft offline a page.
+ * @page: page to offline
+ * @flags: flags. Same as memory_failure().
+ *
+ * Returns 0 on success, otherwise negated errno.
+ *
+ * Soft offline a page, by migration or invalidation,
+ * without killing anything. This is for the case when
+ * a page is not corrupted yet (so it's still valid to access),
+ * but has had a number of corrected errors and is better taken
+ * out.
+ *
+ * The actual policy on when to do that is maintained by
+ * user space.
+ *
+ * This should never impact any application or cause data loss,
+ * however it might take some time.
+ *
+ * This is not a 100% solution for all memory, but tries to be
+ * ``good enough'' for the majority of memory.
+ */
+int soft_offline_page(struct page *page, int flags)
+{
+	int ret;
+	unsigned long pfn = page_to_pfn(page);
+	struct page *hpage = compound_head(page);
+
+	if (PageHWPoison(page)) {
+		pr_info("soft offline: %#lx page already poisoned\n", pfn);
+		if (flags & MF_COUNT_INCREASED)
+			put_hwpoison_page(page);
+		return -EBUSY;
+	}
+	if (!PageHuge(page) && PageTransHuge(hpage)) {
+		if (PageAnon(hpage) && unlikely(split_huge_page(hpage))) {
+			pr_info("soft offline: %#lx: failed to split THP\n",
+				pfn);
+			if (flags & MF_COUNT_INCREASED)
+				put_hwpoison_page(page);
+			return -EBUSY;
+		}
+	}
+
+	get_online_mems();
+
+	ret = get_any_page(page, pfn, flags);
+	put_online_mems();
+	if (ret > 0) { /* for in-use pages */
+		if (PageHuge(page))
+			ret = soft_offline_huge_page(page, flags);
+		else
+			ret = __soft_offline_page(page, flags);
+	} else if (ret == 0) { /* for free pages */
+		if (PageHuge(page)) {
+			set_page_hwpoison_huge_page(hpage);
+			if (!dequeue_hwpoisoned_huge_page(hpage))
+				num_poisoned_pages_add(1 << compound_order(hpage));
+		} else {
+			if (!TestSetPageHWPoison(page))
+				num_poisoned_pages_inc();
+		}
+	}
+	return ret;
+}
diff --git a/mm/memory.c b/mm/memory.c
new file mode 100644
index 0000000..9ac5517
--- /dev/null
+++ b/mm/memory.c
@@ -0,0 +1,3912 @@
+/*
+ *  linux/mm/memory.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ */
+
+/*
+ * demand-loading started 01.12.91 - seems it is high on the list of
+ * things wanted, and it should be easy to implement. - Linus
+ */
+
+/*
+ * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
+ * pages started 02.12.91, seems to work. - Linus.
+ *
+ * Tested sharing by executing about 30 /bin/sh: under the old kernel it
+ * would have taken more than the 6M I have free, but it worked well as
+ * far as I could see.
+ *
+ * Also corrected some "invalidate()"s - I wasn't doing enough of them.
+ */
+
+/*
+ * Real VM (paging to/from disk) started 18.12.91. Much more work and
+ * thought has to go into this. Oh, well..
+ * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
+ *		Found it. Everything seems to work now.
+ * 20.12.91  -  Ok, making the swap-device changeable like the root.
+ */
+
+/*
+ * 05.04.94  -  Multi-page memory management added for v1.1.
+ * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
+ *
+ * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
+ *		(Gerhard.Wichert@pdb.siemens.de)
+ *
+ * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/export.h>
+#include <linux/delayacct.h>
+#include <linux/init.h>
+#include <linux/writeback.h>
+#include <linux/memcontrol.h>
+#include <linux/mmu_notifier.h>
+#include <linux/kallsyms.h>
+#include <linux/swapops.h>
+#include <linux/elf.h>
+#include <linux/gfp.h>
+#include <linux/migrate.h>
+#include <linux/string.h>
+#include <linux/dma-debug.h>
+#include <linux/debugfs.h>
+#include <linux/userfaultfd_k.h>
+
+#include <asm/io.h>
+#include <asm/pgalloc.h>
+#include <asm/uaccess.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/pgtable.h>
+
+#include "internal.h"
+
+#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
+#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
+#endif
+
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+/* use the per-pgdat data instead for discontigmem - mbligh */
+unsigned long max_mapnr;
+struct page *mem_map;
+
+EXPORT_SYMBOL(max_mapnr);
+EXPORT_SYMBOL(mem_map);
+#endif
+
+/*
+ * A number of key systems in x86 including ioremap() rely on the assumption
+ * that high_memory defines the upper bound on direct map memory, then end
+ * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
+ * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
+ * and ZONE_HIGHMEM.
+ */
+void * high_memory;
+
+EXPORT_SYMBOL(high_memory);
+
+/*
+ * Randomize the address space (stacks, mmaps, brk, etc.).
+ *
+ * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
+ *   as ancient (libc5 based) binaries can segfault. )
+ */
+int randomize_va_space __read_mostly =
+#ifdef CONFIG_COMPAT_BRK
+					1;
+#else
+					2;
+#endif
+
+static int __init disable_randmaps(char *s)
+{
+	randomize_va_space = 0;
+	return 1;
+}
+__setup("norandmaps", disable_randmaps);
+
+unsigned long zero_pfn __read_mostly;
+unsigned long highest_memmap_pfn __read_mostly;
+
+EXPORT_SYMBOL(zero_pfn);
+
+/*
+ * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
+ */
+static int __init init_zero_pfn(void)
+{
+	zero_pfn = page_to_pfn(ZERO_PAGE(0));
+	return 0;
+}
+core_initcall(init_zero_pfn);
+
+
+#if defined(SPLIT_RSS_COUNTING)
+
+void sync_mm_rss(struct mm_struct *mm)
+{
+	int i;
+
+	for (i = 0; i < NR_MM_COUNTERS; i++) {
+		if (current->rss_stat.count[i]) {
+			add_mm_counter(mm, i, current->rss_stat.count[i]);
+			current->rss_stat.count[i] = 0;
+		}
+	}
+	current->rss_stat.events = 0;
+}
+
+static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
+{
+	struct task_struct *task = current;
+
+	if (likely(task->mm == mm))
+		task->rss_stat.count[member] += val;
+	else
+		add_mm_counter(mm, member, val);
+}
+#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
+#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
+
+/* sync counter once per 64 page faults */
+#define TASK_RSS_EVENTS_THRESH	(64)
+static void check_sync_rss_stat(struct task_struct *task)
+{
+	if (unlikely(task != current))
+		return;
+	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
+		sync_mm_rss(task->mm);
+}
+#else /* SPLIT_RSS_COUNTING */
+
+#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
+#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
+
+static void check_sync_rss_stat(struct task_struct *task)
+{
+}
+
+#endif /* SPLIT_RSS_COUNTING */
+
+#ifdef HAVE_GENERIC_MMU_GATHER
+
+static bool tlb_next_batch(struct mmu_gather *tlb)
+{
+	struct mmu_gather_batch *batch;
+
+	batch = tlb->active;
+	if (batch->next) {
+		tlb->active = batch->next;
+		return true;
+	}
+
+	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
+		return false;
+
+	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+	if (!batch)
+		return false;
+
+	tlb->batch_count++;
+	batch->next = NULL;
+	batch->nr   = 0;
+	batch->max  = MAX_GATHER_BATCH;
+
+	tlb->active->next = batch;
+	tlb->active = batch;
+
+	return true;
+}
+
+/* tlb_gather_mmu
+ *	Called to initialize an (on-stack) mmu_gather structure for page-table
+ *	tear-down from @mm. The @fullmm argument is used when @mm is without
+ *	users and we're going to destroy the full address space (exit/execve).
+ */
+void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
+{
+	tlb->mm = mm;
+
+	/* Is it from 0 to ~0? */
+	tlb->fullmm     = !(start | (end+1));
+	tlb->need_flush_all = 0;
+	tlb->local.next = NULL;
+	tlb->local.nr   = 0;
+	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
+	tlb->active     = &tlb->local;
+	tlb->batch_count = 0;
+
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+	tlb->batch = NULL;
+#endif
+
+	__tlb_reset_range(tlb);
+}
+
+static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
+{
+	if (!tlb->end)
+		return;
+
+	tlb_flush(tlb);
+	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+	tlb_table_flush(tlb);
+#endif
+	__tlb_reset_range(tlb);
+}
+
+static void tlb_flush_mmu_free(struct mmu_gather *tlb)
+{
+	struct mmu_gather_batch *batch;
+
+	for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
+		free_pages_and_swap_cache(batch->pages, batch->nr);
+		batch->nr = 0;
+	}
+	tlb->active = &tlb->local;
+}
+
+void tlb_flush_mmu(struct mmu_gather *tlb)
+{
+	tlb_flush_mmu_tlbonly(tlb);
+	tlb_flush_mmu_free(tlb);
+}
+
+/* tlb_finish_mmu
+ *	Called at the end of the shootdown operation to free up any resources
+ *	that were required.
+ */
+void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
+{
+	struct mmu_gather_batch *batch, *next;
+
+	tlb_flush_mmu(tlb);
+
+	/* keep the page table cache within bounds */
+	check_pgt_cache();
+
+	for (batch = tlb->local.next; batch; batch = next) {
+		next = batch->next;
+		free_pages((unsigned long)batch, 0);
+	}
+	tlb->local.next = NULL;
+}
+
+/* __tlb_remove_page
+ *	Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
+ *	handling the additional races in SMP caused by other CPUs caching valid
+ *	mappings in their TLBs. Returns the number of free page slots left.
+ *	When out of page slots we must call tlb_flush_mmu().
+ */
+int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	struct mmu_gather_batch *batch;
+
+	VM_BUG_ON(!tlb->end);
+
+	batch = tlb->active;
+	batch->pages[batch->nr++] = page;
+	if (batch->nr == batch->max) {
+		if (!tlb_next_batch(tlb))
+			return 0;
+		batch = tlb->active;
+	}
+	VM_BUG_ON_PAGE(batch->nr > batch->max, page);
+
+	return batch->max - batch->nr;
+}
+
+#endif /* HAVE_GENERIC_MMU_GATHER */
+
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+
+/*
+ * See the comment near struct mmu_table_batch.
+ */
+
+static void tlb_remove_table_smp_sync(void *arg)
+{
+	/* Simply deliver the interrupt */
+}
+
+static void tlb_remove_table_one(void *table)
+{
+	/*
+	 * This isn't an RCU grace period and hence the page-tables cannot be
+	 * assumed to be actually RCU-freed.
+	 *
+	 * It is however sufficient for software page-table walkers that rely on
+	 * IRQ disabling. See the comment near struct mmu_table_batch.
+	 */
+	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
+	__tlb_remove_table(table);
+}
+
+static void tlb_remove_table_rcu(struct rcu_head *head)
+{
+	struct mmu_table_batch *batch;
+	int i;
+
+	batch = container_of(head, struct mmu_table_batch, rcu);
+
+	for (i = 0; i < batch->nr; i++)
+		__tlb_remove_table(batch->tables[i]);
+
+	free_page((unsigned long)batch);
+}
+
+void tlb_table_flush(struct mmu_gather *tlb)
+{
+	struct mmu_table_batch **batch = &tlb->batch;
+
+	if (*batch) {
+		call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
+		*batch = NULL;
+	}
+}
+
+void tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+	struct mmu_table_batch **batch = &tlb->batch;
+
+	/*
+	 * When there's less then two users of this mm there cannot be a
+	 * concurrent page-table walk.
+	 */
+	if (atomic_read(&tlb->mm->mm_users) < 2) {
+		__tlb_remove_table(table);
+		return;
+	}
+
+	if (*batch == NULL) {
+		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
+		if (*batch == NULL) {
+			tlb_remove_table_one(table);
+			return;
+		}
+		(*batch)->nr = 0;
+	}
+	(*batch)->tables[(*batch)->nr++] = table;
+	if ((*batch)->nr == MAX_TABLE_BATCH)
+		tlb_table_flush(tlb);
+}
+
+#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
+
+/*
+ * Note: this doesn't free the actual pages themselves. That
+ * has been handled earlier when unmapping all the memory regions.
+ */
+static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
+			   unsigned long addr)
+{
+	pgtable_t token = pmd_pgtable(*pmd);
+	pmd_clear(pmd);
+	pte_free_tlb(tlb, token, addr);
+	atomic_long_dec(&tlb->mm->nr_ptes);
+}
+
+static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
+				unsigned long addr, unsigned long end,
+				unsigned long floor, unsigned long ceiling)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	unsigned long start;
+
+	start = addr;
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_none_or_clear_bad(pmd))
+			continue;
+		free_pte_range(tlb, pmd, addr);
+	} while (pmd++, addr = next, addr != end);
+
+	start &= PUD_MASK;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= PUD_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	pmd = pmd_offset(pud, start);
+	pud_clear(pud);
+	pmd_free_tlb(tlb, pmd, start);
+	mm_dec_nr_pmds(tlb->mm);
+}
+
+static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
+				unsigned long addr, unsigned long end,
+				unsigned long floor, unsigned long ceiling)
+{
+	pud_t *pud;
+	unsigned long next;
+	unsigned long start;
+
+	start = addr;
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
+	} while (pud++, addr = next, addr != end);
+
+	start &= PGDIR_MASK;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= PGDIR_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	pud = pud_offset(pgd, start);
+	pgd_clear(pgd);
+	pud_free_tlb(tlb, pud, start);
+}
+
+/*
+ * This function frees user-level page tables of a process.
+ */
+void free_pgd_range(struct mmu_gather *tlb,
+			unsigned long addr, unsigned long end,
+			unsigned long floor, unsigned long ceiling)
+{
+	pgd_t *pgd;
+	unsigned long next;
+
+	/*
+	 * The next few lines have given us lots of grief...
+	 *
+	 * Why are we testing PMD* at this top level?  Because often
+	 * there will be no work to do at all, and we'd prefer not to
+	 * go all the way down to the bottom just to discover that.
+	 *
+	 * Why all these "- 1"s?  Because 0 represents both the bottom
+	 * of the address space and the top of it (using -1 for the
+	 * top wouldn't help much: the masks would do the wrong thing).
+	 * The rule is that addr 0 and floor 0 refer to the bottom of
+	 * the address space, but end 0 and ceiling 0 refer to the top
+	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
+	 * that end 0 case should be mythical).
+	 *
+	 * Wherever addr is brought up or ceiling brought down, we must
+	 * be careful to reject "the opposite 0" before it confuses the
+	 * subsequent tests.  But what about where end is brought down
+	 * by PMD_SIZE below? no, end can't go down to 0 there.
+	 *
+	 * Whereas we round start (addr) and ceiling down, by different
+	 * masks at different levels, in order to test whether a table
+	 * now has no other vmas using it, so can be freed, we don't
+	 * bother to round floor or end up - the tests don't need that.
+	 */
+
+	addr &= PMD_MASK;
+	if (addr < floor) {
+		addr += PMD_SIZE;
+		if (!addr)
+			return;
+	}
+	if (ceiling) {
+		ceiling &= PMD_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		end -= PMD_SIZE;
+	if (addr > end - 1)
+		return;
+
+	pgd = pgd_offset(tlb->mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		free_pud_range(tlb, pgd, addr, next, floor, ceiling);
+	} while (pgd++, addr = next, addr != end);
+}
+
+void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
+		unsigned long floor, unsigned long ceiling)
+{
+	while (vma) {
+		struct vm_area_struct *next = vma->vm_next;
+		unsigned long addr = vma->vm_start;
+
+		/*
+		 * Hide vma from rmap and truncate_pagecache before freeing
+		 * pgtables
+		 */
+		unlink_anon_vmas(vma);
+		unlink_file_vma(vma);
+
+		if (is_vm_hugetlb_page(vma)) {
+			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
+				floor, next? next->vm_start: ceiling);
+		} else {
+			/*
+			 * Optimization: gather nearby vmas into one call down
+			 */
+			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
+			       && !is_vm_hugetlb_page(next)) {
+				vma = next;
+				next = vma->vm_next;
+				unlink_anon_vmas(vma);
+				unlink_file_vma(vma);
+			}
+			free_pgd_range(tlb, addr, vma->vm_end,
+				floor, next? next->vm_start: ceiling);
+		}
+		vma = next;
+	}
+}
+
+int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
+		pmd_t *pmd, unsigned long address)
+{
+	spinlock_t *ptl;
+	pgtable_t new = pte_alloc_one(mm, address);
+	int wait_split_huge_page;
+	if (!new)
+		return -ENOMEM;
+
+	/*
+	 * Ensure all pte setup (eg. pte page lock and page clearing) are
+	 * visible before the pte is made visible to other CPUs by being
+	 * put into page tables.
+	 *
+	 * The other side of the story is the pointer chasing in the page
+	 * table walking code (when walking the page table without locking;
+	 * ie. most of the time). Fortunately, these data accesses consist
+	 * of a chain of data-dependent loads, meaning most CPUs (alpha
+	 * being the notable exception) will already guarantee loads are
+	 * seen in-order. See the alpha page table accessors for the
+	 * smp_read_barrier_depends() barriers in page table walking code.
+	 */
+	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
+
+	ptl = pmd_lock(mm, pmd);
+	wait_split_huge_page = 0;
+	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
+		atomic_long_inc(&mm->nr_ptes);
+		pmd_populate(mm, pmd, new);
+		new = NULL;
+	} else if (unlikely(pmd_trans_splitting(*pmd)))
+		wait_split_huge_page = 1;
+	spin_unlock(ptl);
+	if (new)
+		pte_free(mm, new);
+	if (wait_split_huge_page)
+		wait_split_huge_page(vma->anon_vma, pmd);
+	return 0;
+}
+
+int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
+{
+	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
+	if (!new)
+		return -ENOMEM;
+
+	smp_wmb(); /* See comment in __pte_alloc */
+
+	spin_lock(&init_mm.page_table_lock);
+	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
+		pmd_populate_kernel(&init_mm, pmd, new);
+		new = NULL;
+	} else
+		VM_BUG_ON(pmd_trans_splitting(*pmd));
+	spin_unlock(&init_mm.page_table_lock);
+	if (new)
+		pte_free_kernel(&init_mm, new);
+	return 0;
+}
+
+static inline void init_rss_vec(int *rss)
+{
+	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
+}
+
+static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
+{
+	int i;
+
+	if (current->mm == mm)
+		sync_mm_rss(mm);
+	for (i = 0; i < NR_MM_COUNTERS; i++)
+		if (rss[i])
+			add_mm_counter(mm, i, rss[i]);
+}
+
+/*
+ * This function is called to print an error when a bad pte
+ * is found. For example, we might have a PFN-mapped pte in
+ * a region that doesn't allow it.
+ *
+ * The calling function must still handle the error.
+ */
+static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
+			  pte_t pte, struct page *page)
+{
+	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
+	pud_t *pud = pud_offset(pgd, addr);
+	pmd_t *pmd = pmd_offset(pud, addr);
+	struct address_space *mapping;
+	pgoff_t index;
+	static unsigned long resume;
+	static unsigned long nr_shown;
+	static unsigned long nr_unshown;
+
+	/*
+	 * Allow a burst of 60 reports, then keep quiet for that minute;
+	 * or allow a steady drip of one report per second.
+	 */
+	if (nr_shown == 60) {
+		if (time_before(jiffies, resume)) {
+			nr_unshown++;
+			return;
+		}
+		if (nr_unshown) {
+			printk(KERN_ALERT
+				"BUG: Bad page map: %lu messages suppressed\n",
+				nr_unshown);
+			nr_unshown = 0;
+		}
+		nr_shown = 0;
+	}
+	if (nr_shown++ == 0)
+		resume = jiffies + 60 * HZ;
+
+	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
+	index = linear_page_index(vma, addr);
+
+	printk(KERN_ALERT
+		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
+		current->comm,
+		(long long)pte_val(pte), (long long)pmd_val(*pmd));
+	if (page)
+		dump_page(page, "bad pte");
+	printk(KERN_ALERT
+		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
+		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
+	/*
+	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
+	 */
+	pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
+		 vma->vm_file,
+		 vma->vm_ops ? vma->vm_ops->fault : NULL,
+		 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
+		 mapping ? mapping->a_ops->readpage : NULL);
+	dump_stack();
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+}
+
+/*
+ * vm_normal_page -- This function gets the "struct page" associated with a pte.
+ *
+ * "Special" mappings do not wish to be associated with a "struct page" (either
+ * it doesn't exist, or it exists but they don't want to touch it). In this
+ * case, NULL is returned here. "Normal" mappings do have a struct page.
+ *
+ * There are 2 broad cases. Firstly, an architecture may define a pte_special()
+ * pte bit, in which case this function is trivial. Secondly, an architecture
+ * may not have a spare pte bit, which requires a more complicated scheme,
+ * described below.
+ *
+ * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
+ * special mapping (even if there are underlying and valid "struct pages").
+ * COWed pages of a VM_PFNMAP are always normal.
+ *
+ * The way we recognize COWed pages within VM_PFNMAP mappings is through the
+ * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
+ * set, and the vm_pgoff will point to the first PFN mapped: thus every special
+ * mapping will always honor the rule
+ *
+ *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
+ *
+ * And for normal mappings this is false.
+ *
+ * This restricts such mappings to be a linear translation from virtual address
+ * to pfn. To get around this restriction, we allow arbitrary mappings so long
+ * as the vma is not a COW mapping; in that case, we know that all ptes are
+ * special (because none can have been COWed).
+ *
+ *
+ * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
+ *
+ * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
+ * page" backing, however the difference is that _all_ pages with a struct
+ * page (that is, those where pfn_valid is true) are refcounted and considered
+ * normal pages by the VM. The disadvantage is that pages are refcounted
+ * (which can be slower and simply not an option for some PFNMAP users). The
+ * advantage is that we don't have to follow the strict linearity rule of
+ * PFNMAP mappings in order to support COWable mappings.
+ *
+ */
+#ifdef __HAVE_ARCH_PTE_SPECIAL
+# define HAVE_PTE_SPECIAL 1
+#else
+# define HAVE_PTE_SPECIAL 0
+#endif
+struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
+				pte_t pte)
+{
+	unsigned long pfn = pte_pfn(pte);
+
+	if (HAVE_PTE_SPECIAL) {
+		if (likely(!pte_special(pte)))
+			goto check_pfn;
+		if (vma->vm_ops && vma->vm_ops->find_special_page)
+			return vma->vm_ops->find_special_page(vma, addr);
+		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
+			return NULL;
+		if (!is_zero_pfn(pfn))
+			print_bad_pte(vma, addr, pte, NULL);
+		return NULL;
+	}
+
+	/* !HAVE_PTE_SPECIAL case follows: */
+
+	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
+		if (vma->vm_flags & VM_MIXEDMAP) {
+			if (!pfn_valid(pfn))
+				return NULL;
+			goto out;
+		} else {
+			unsigned long off;
+			off = (addr - vma->vm_start) >> PAGE_SHIFT;
+			if (pfn == vma->vm_pgoff + off)
+				return NULL;
+			if (!is_cow_mapping(vma->vm_flags))
+				return NULL;
+		}
+	}
+
+	if (is_zero_pfn(pfn))
+		return NULL;
+check_pfn:
+	if (unlikely(pfn > highest_memmap_pfn)) {
+		print_bad_pte(vma, addr, pte, NULL);
+		return NULL;
+	}
+
+	/*
+	 * NOTE! We still have PageReserved() pages in the page tables.
+	 * eg. VDSO mappings can cause them to exist.
+	 */
+out:
+	return pfn_to_page(pfn);
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
+				pmd_t pmd)
+{
+	unsigned long pfn = pmd_pfn(pmd);
+
+	/*
+	 * There is no pmd_special() but there may be special pmds, e.g.
+	 * in a direct-access (dax) mapping, so let's just replicate the
+	 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
+	 */
+	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
+		if (vma->vm_flags & VM_MIXEDMAP) {
+			if (!pfn_valid(pfn))
+				return NULL;
+			goto out;
+		} else {
+			unsigned long off;
+			off = (addr - vma->vm_start) >> PAGE_SHIFT;
+			if (pfn == vma->vm_pgoff + off)
+				return NULL;
+			if (!is_cow_mapping(vma->vm_flags))
+				return NULL;
+		}
+	}
+
+	if (is_zero_pfn(pfn))
+		return NULL;
+	if (unlikely(pfn > highest_memmap_pfn))
+		return NULL;
+
+	/*
+	 * NOTE! We still have PageReserved() pages in the page tables.
+	 * eg. VDSO mappings can cause them to exist.
+	 */
+out:
+	return pfn_to_page(pfn);
+}
+#endif
+
+/*
+ * copy one vm_area from one task to the other. Assumes the page tables
+ * already present in the new task to be cleared in the whole range
+ * covered by this vma.
+ */
+
+static inline unsigned long
+copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
+		unsigned long addr, int *rss)
+{
+	unsigned long vm_flags = vma->vm_flags;
+	pte_t pte = *src_pte;
+	struct page *page;
+
+	/* pte contains position in swap or file, so copy. */
+	if (unlikely(!pte_present(pte))) {
+		swp_entry_t entry = pte_to_swp_entry(pte);
+
+		if (likely(!non_swap_entry(entry))) {
+			if (swap_duplicate(entry) < 0)
+				return entry.val;
+
+			/* make sure dst_mm is on swapoff's mmlist. */
+			if (unlikely(list_empty(&dst_mm->mmlist))) {
+				spin_lock(&mmlist_lock);
+				if (list_empty(&dst_mm->mmlist))
+					list_add(&dst_mm->mmlist,
+							&src_mm->mmlist);
+				spin_unlock(&mmlist_lock);
+			}
+			rss[MM_SWAPENTS]++;
+		} else if (is_migration_entry(entry)) {
+			page = migration_entry_to_page(entry);
+
+			if (PageAnon(page))
+				rss[MM_ANONPAGES]++;
+			else
+				rss[MM_FILEPAGES]++;
+
+			if (is_write_migration_entry(entry) &&
+					is_cow_mapping(vm_flags)) {
+				/*
+				 * COW mappings require pages in both
+				 * parent and child to be set to read.
+				 */
+				make_migration_entry_read(&entry);
+				pte = swp_entry_to_pte(entry);
+				if (pte_swp_soft_dirty(*src_pte))
+					pte = pte_swp_mksoft_dirty(pte);
+				set_pte_at(src_mm, addr, src_pte, pte);
+			}
+		}
+		goto out_set_pte;
+	}
+
+	/*
+	 * If it's a COW mapping, write protect it both
+	 * in the parent and the child
+	 */
+	if (is_cow_mapping(vm_flags)) {
+		ptep_set_wrprotect(src_mm, addr, src_pte);
+		pte = pte_wrprotect(pte);
+	}
+
+	/*
+	 * If it's a shared mapping, mark it clean in
+	 * the child
+	 */
+	if (vm_flags & VM_SHARED)
+		pte = pte_mkclean(pte);
+	pte = pte_mkold(pte);
+
+	page = vm_normal_page(vma, addr, pte);
+	if (page) {
+		get_page(page);
+		page_dup_rmap(page);
+		if (PageAnon(page))
+			rss[MM_ANONPAGES]++;
+		else
+			rss[MM_FILEPAGES]++;
+	}
+
+out_set_pte:
+	set_pte_at(dst_mm, addr, dst_pte, pte);
+	return 0;
+}
+
+static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
+		   unsigned long addr, unsigned long end)
+{
+	pte_t *orig_src_pte, *orig_dst_pte;
+	pte_t *src_pte, *dst_pte;
+	spinlock_t *src_ptl, *dst_ptl;
+	int progress = 0;
+	int rss[NR_MM_COUNTERS];
+	swp_entry_t entry = (swp_entry_t){0};
+
+again:
+	init_rss_vec(rss);
+
+	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
+	if (!dst_pte)
+		return -ENOMEM;
+	src_pte = pte_offset_map(src_pmd, addr);
+	src_ptl = pte_lockptr(src_mm, src_pmd);
+	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+	orig_src_pte = src_pte;
+	orig_dst_pte = dst_pte;
+	arch_enter_lazy_mmu_mode();
+
+	do {
+		/*
+		 * We are holding two locks at this point - either of them
+		 * could generate latencies in another task on another CPU.
+		 */
+		if (progress >= 32) {
+			progress = 0;
+			if (need_resched() ||
+			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
+				break;
+		}
+		if (pte_none(*src_pte)) {
+			progress++;
+			continue;
+		}
+		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
+							vma, addr, rss);
+		if (entry.val)
+			break;
+		progress += 8;
+	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
+
+	arch_leave_lazy_mmu_mode();
+	spin_unlock(src_ptl);
+	pte_unmap(orig_src_pte);
+	add_mm_rss_vec(dst_mm, rss);
+	pte_unmap_unlock(orig_dst_pte, dst_ptl);
+	cond_resched();
+
+	if (entry.val) {
+		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
+			return -ENOMEM;
+		progress = 0;
+	}
+	if (addr != end)
+		goto again;
+	return 0;
+}
+
+static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
+		unsigned long addr, unsigned long end)
+{
+	pmd_t *src_pmd, *dst_pmd;
+	unsigned long next;
+
+	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
+	if (!dst_pmd)
+		return -ENOMEM;
+	src_pmd = pmd_offset(src_pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_trans_huge(*src_pmd)) {
+			int err;
+			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
+			err = copy_huge_pmd(dst_mm, src_mm,
+					    dst_pmd, src_pmd, addr, vma);
+			if (err == -ENOMEM)
+				return -ENOMEM;
+			if (!err)
+				continue;
+			/* fall through */
+		}
+		if (pmd_none_or_clear_bad(src_pmd))
+			continue;
+		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
+						vma, addr, next))
+			return -ENOMEM;
+	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
+	return 0;
+}
+
+static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
+		unsigned long addr, unsigned long end)
+{
+	pud_t *src_pud, *dst_pud;
+	unsigned long next;
+
+	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
+	if (!dst_pud)
+		return -ENOMEM;
+	src_pud = pud_offset(src_pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(src_pud))
+			continue;
+		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
+						vma, addr, next))
+			return -ENOMEM;
+	} while (dst_pud++, src_pud++, addr = next, addr != end);
+	return 0;
+}
+
+int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		struct vm_area_struct *vma)
+{
+	pgd_t *src_pgd, *dst_pgd;
+	unsigned long next;
+	unsigned long addr = vma->vm_start;
+	unsigned long end = vma->vm_end;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+	bool is_cow;
+	int ret;
+
+	/*
+	 * Don't copy ptes where a page fault will fill them correctly.
+	 * Fork becomes much lighter when there are big shared or private
+	 * readonly mappings. The tradeoff is that copy_page_range is more
+	 * efficient than faulting.
+	 */
+	if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
+			!vma->anon_vma)
+		return 0;
+
+	if (is_vm_hugetlb_page(vma))
+		return copy_hugetlb_page_range(dst_mm, src_mm, vma);
+
+	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
+		/*
+		 * We do not free on error cases below as remove_vma
+		 * gets called on error from higher level routine
+		 */
+		ret = track_pfn_copy(vma);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * We need to invalidate the secondary MMU mappings only when
+	 * there could be a permission downgrade on the ptes of the
+	 * parent mm. And a permission downgrade will only happen if
+	 * is_cow_mapping() returns true.
+	 */
+	is_cow = is_cow_mapping(vma->vm_flags);
+	mmun_start = addr;
+	mmun_end   = end;
+	if (is_cow)
+		mmu_notifier_invalidate_range_start(src_mm, mmun_start,
+						    mmun_end);
+
+	ret = 0;
+	dst_pgd = pgd_offset(dst_mm, addr);
+	src_pgd = pgd_offset(src_mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(src_pgd))
+			continue;
+		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
+					    vma, addr, next))) {
+			ret = -ENOMEM;
+			break;
+		}
+	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
+
+	if (is_cow)
+		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
+	return ret;
+}
+
+static unsigned long zap_pte_range(struct mmu_gather *tlb,
+				struct vm_area_struct *vma, pmd_t *pmd,
+				unsigned long addr, unsigned long end,
+				struct zap_details *details)
+{
+	struct mm_struct *mm = tlb->mm;
+	int force_flush = 0;
+	int rss[NR_MM_COUNTERS];
+	spinlock_t *ptl;
+	pte_t *start_pte;
+	pte_t *pte;
+	swp_entry_t entry;
+
+again:
+	init_rss_vec(rss);
+	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	pte = start_pte;
+	flush_tlb_batched_pending(mm);
+	arch_enter_lazy_mmu_mode();
+	do {
+		pte_t ptent = *pte;
+		if (pte_none(ptent)) {
+			continue;
+		}
+
+		if (pte_present(ptent)) {
+			struct page *page;
+
+			page = vm_normal_page(vma, addr, ptent);
+			if (unlikely(details) && page) {
+				/*
+				 * unmap_shared_mapping_pages() wants to
+				 * invalidate cache without truncating:
+				 * unmap shared but keep private pages.
+				 */
+				if (details->check_mapping &&
+				    details->check_mapping != page->mapping)
+					continue;
+			}
+			ptent = ptep_get_and_clear_full(mm, addr, pte,
+							tlb->fullmm);
+			tlb_remove_tlb_entry(tlb, pte, addr);
+			if (unlikely(!page))
+				continue;
+			if (PageAnon(page))
+				rss[MM_ANONPAGES]--;
+			else {
+				if (pte_dirty(ptent)) {
+					force_flush = 1;
+					set_page_dirty(page);
+				}
+				if (pte_young(ptent) &&
+				    likely(!(vma->vm_flags & VM_SEQ_READ)))
+					mark_page_accessed(page);
+				rss[MM_FILEPAGES]--;
+			}
+			page_remove_rmap(page);
+			if (unlikely(page_mapcount(page) < 0))
+				print_bad_pte(vma, addr, ptent, page);
+			if (unlikely(!__tlb_remove_page(tlb, page))) {
+				force_flush = 1;
+				addr += PAGE_SIZE;
+				break;
+			}
+			continue;
+		}
+		/* If details->check_mapping, we leave swap entries. */
+		if (unlikely(details))
+			continue;
+
+		entry = pte_to_swp_entry(ptent);
+		if (!non_swap_entry(entry))
+			rss[MM_SWAPENTS]--;
+		else if (is_migration_entry(entry)) {
+			struct page *page;
+
+			page = migration_entry_to_page(entry);
+
+			if (PageAnon(page))
+				rss[MM_ANONPAGES]--;
+			else
+				rss[MM_FILEPAGES]--;
+		}
+		if (unlikely(!free_swap_and_cache(entry)))
+			print_bad_pte(vma, addr, ptent, NULL);
+		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+
+	add_mm_rss_vec(mm, rss);
+	arch_leave_lazy_mmu_mode();
+
+	/* Do the actual TLB flush before dropping ptl */
+	if (force_flush)
+		tlb_flush_mmu_tlbonly(tlb);
+	pte_unmap_unlock(start_pte, ptl);
+
+	/*
+	 * If we forced a TLB flush (either due to running out of
+	 * batch buffers or because we needed to flush dirty TLB
+	 * entries before releasing the ptl), free the batched
+	 * memory too. Restart if we didn't do everything.
+	 */
+	if (force_flush) {
+		force_flush = 0;
+		tlb_flush_mmu_free(tlb);
+
+		if (addr != end)
+			goto again;
+	}
+
+	return addr;
+}
+
+static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
+				struct vm_area_struct *vma, pud_t *pud,
+				unsigned long addr, unsigned long end,
+				struct zap_details *details)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_trans_huge(*pmd)) {
+			if (next - addr != HPAGE_PMD_SIZE) {
+#ifdef CONFIG_DEBUG_VM
+				if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
+					pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
+						__func__, addr, end,
+						vma->vm_start,
+						vma->vm_end);
+					BUG();
+				}
+#endif
+				split_huge_page_pmd(vma, addr, pmd);
+			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
+				goto next;
+			/* fall through */
+		}
+		/*
+		 * Here there can be other concurrent MADV_DONTNEED or
+		 * trans huge page faults running, and if the pmd is
+		 * none or trans huge it can change under us. This is
+		 * because MADV_DONTNEED holds the mmap_sem in read
+		 * mode.
+		 */
+		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+			goto next;
+		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
+next:
+		cond_resched();
+	} while (pmd++, addr = next, addr != end);
+
+	return addr;
+}
+
+static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
+				struct vm_area_struct *vma, pgd_t *pgd,
+				unsigned long addr, unsigned long end,
+				struct zap_details *details)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
+	} while (pud++, addr = next, addr != end);
+
+	return addr;
+}
+
+static void unmap_page_range(struct mmu_gather *tlb,
+			     struct vm_area_struct *vma,
+			     unsigned long addr, unsigned long end,
+			     struct zap_details *details)
+{
+	pgd_t *pgd;
+	unsigned long next;
+
+	if (details && !details->check_mapping)
+		details = NULL;
+
+	BUG_ON(addr >= end);
+	tlb_start_vma(tlb, vma);
+	pgd = pgd_offset(vma->vm_mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
+	} while (pgd++, addr = next, addr != end);
+	tlb_end_vma(tlb, vma);
+}
+
+
+static void unmap_single_vma(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, unsigned long start_addr,
+		unsigned long end_addr,
+		struct zap_details *details)
+{
+	unsigned long start = max(vma->vm_start, start_addr);
+	unsigned long end;
+
+	if (start >= vma->vm_end)
+		return;
+	end = min(vma->vm_end, end_addr);
+	if (end <= vma->vm_start)
+		return;
+
+	if (vma->vm_file)
+		uprobe_munmap(vma, start, end);
+
+	if (unlikely(vma->vm_flags & VM_PFNMAP))
+		untrack_pfn(vma, 0, 0);
+
+	if (start != end) {
+		if (unlikely(is_vm_hugetlb_page(vma))) {
+			/*
+			 * It is undesirable to test vma->vm_file as it
+			 * should be non-null for valid hugetlb area.
+			 * However, vm_file will be NULL in the error
+			 * cleanup path of mmap_region. When
+			 * hugetlbfs ->mmap method fails,
+			 * mmap_region() nullifies vma->vm_file
+			 * before calling this function to clean up.
+			 * Since no pte has actually been setup, it is
+			 * safe to do nothing in this case.
+			 */
+			if (vma->vm_file) {
+				i_mmap_lock_write(vma->vm_file->f_mapping);
+				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
+				i_mmap_unlock_write(vma->vm_file->f_mapping);
+			}
+		} else
+			unmap_page_range(tlb, vma, start, end, details);
+	}
+}
+
+/**
+ * unmap_vmas - unmap a range of memory covered by a list of vma's
+ * @tlb: address of the caller's struct mmu_gather
+ * @vma: the starting vma
+ * @start_addr: virtual address at which to start unmapping
+ * @end_addr: virtual address at which to end unmapping
+ *
+ * Unmap all pages in the vma list.
+ *
+ * Only addresses between `start' and `end' will be unmapped.
+ *
+ * The VMA list must be sorted in ascending virtual address order.
+ *
+ * unmap_vmas() assumes that the caller will flush the whole unmapped address
+ * range after unmap_vmas() returns.  So the only responsibility here is to
+ * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
+ * drops the lock and schedules.
+ */
+void unmap_vmas(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, unsigned long start_addr,
+		unsigned long end_addr)
+{
+	struct mm_struct *mm = vma->vm_mm;
+
+	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
+	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
+		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
+	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
+}
+
+/**
+ * zap_page_range - remove user pages in a given range
+ * @vma: vm_area_struct holding the applicable pages
+ * @start: starting address of pages to zap
+ * @size: number of bytes to zap
+ * @details: details of shared cache invalidation
+ *
+ * Caller must protect the VMA list
+ */
+void zap_page_range(struct vm_area_struct *vma, unsigned long start,
+		unsigned long size, struct zap_details *details)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
+	unsigned long end = start + size;
+
+	lru_add_drain();
+	tlb_gather_mmu(&tlb, mm, start, end);
+	update_hiwater_rss(mm);
+	mmu_notifier_invalidate_range_start(mm, start, end);
+	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
+		unmap_single_vma(&tlb, vma, start, end, details);
+	mmu_notifier_invalidate_range_end(mm, start, end);
+	tlb_finish_mmu(&tlb, start, end);
+}
+
+/**
+ * zap_page_range_single - remove user pages in a given range
+ * @vma: vm_area_struct holding the applicable pages
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ * @details: details of shared cache invalidation
+ *
+ * The range must fit into one VMA.
+ */
+static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
+		unsigned long size, struct zap_details *details)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
+	unsigned long end = address + size;
+
+	lru_add_drain();
+	tlb_gather_mmu(&tlb, mm, address, end);
+	update_hiwater_rss(mm);
+	mmu_notifier_invalidate_range_start(mm, address, end);
+	unmap_single_vma(&tlb, vma, address, end, details);
+	mmu_notifier_invalidate_range_end(mm, address, end);
+	tlb_finish_mmu(&tlb, address, end);
+}
+
+/**
+ * zap_vma_ptes - remove ptes mapping the vma
+ * @vma: vm_area_struct holding ptes to be zapped
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ *
+ * This function only unmaps ptes assigned to VM_PFNMAP vmas.
+ *
+ * The entire address range must be fully contained within the vma.
+ *
+ * Returns 0 if successful.
+ */
+int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
+		unsigned long size)
+{
+	if (address < vma->vm_start || address + size > vma->vm_end ||
+	    		!(vma->vm_flags & VM_PFNMAP))
+		return -1;
+	zap_page_range_single(vma, address, size, NULL);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(zap_vma_ptes);
+
+pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
+			spinlock_t **ptl)
+{
+	pgd_t * pgd = pgd_offset(mm, addr);
+	pud_t * pud = pud_alloc(mm, pgd, addr);
+	if (pud) {
+		pmd_t * pmd = pmd_alloc(mm, pud, addr);
+		if (pmd) {
+			VM_BUG_ON(pmd_trans_huge(*pmd));
+			return pte_alloc_map_lock(mm, pmd, addr, ptl);
+		}
+	}
+	return NULL;
+}
+
+/*
+ * This is the old fallback for page remapping.
+ *
+ * For historical reasons, it only allows reserved pages. Only
+ * old drivers should use this, and they needed to mark their
+ * pages reserved for the old functions anyway.
+ */
+static int insert_page(struct vm_area_struct *vma, unsigned long addr,
+			struct page *page, pgprot_t prot)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int retval;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	retval = -EINVAL;
+	if (PageAnon(page))
+		goto out;
+	retval = -ENOMEM;
+	flush_dcache_page(page);
+	pte = get_locked_pte(mm, addr, &ptl);
+	if (!pte)
+		goto out;
+	retval = -EBUSY;
+	if (!pte_none(*pte))
+		goto out_unlock;
+
+	/* Ok, finally just insert the thing.. */
+	get_page(page);
+	inc_mm_counter_fast(mm, MM_FILEPAGES);
+	page_add_file_rmap(page);
+	set_pte_at(mm, addr, pte, mk_pte(page, prot));
+
+	retval = 0;
+	pte_unmap_unlock(pte, ptl);
+	return retval;
+out_unlock:
+	pte_unmap_unlock(pte, ptl);
+out:
+	return retval;
+}
+
+/**
+ * vm_insert_page - insert single page into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @page: source kernel page
+ *
+ * This allows drivers to insert individual pages they've allocated
+ * into a user vma.
+ *
+ * The page has to be a nice clean _individual_ kernel allocation.
+ * If you allocate a compound page, you need to have marked it as
+ * such (__GFP_COMP), or manually just split the page up yourself
+ * (see split_page()).
+ *
+ * NOTE! Traditionally this was done with "remap_pfn_range()" which
+ * took an arbitrary page protection parameter. This doesn't allow
+ * that. Your vma protection will have to be set up correctly, which
+ * means that if you want a shared writable mapping, you'd better
+ * ask for a shared writable mapping!
+ *
+ * The page does not need to be reserved.
+ *
+ * Usually this function is called from f_op->mmap() handler
+ * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
+ * Caller must set VM_MIXEDMAP on vma if it wants to call this
+ * function from other places, for example from page-fault handler.
+ */
+int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
+			struct page *page)
+{
+	if (addr < vma->vm_start || addr >= vma->vm_end)
+		return -EFAULT;
+	if (!page_count(page))
+		return -EINVAL;
+	if (!(vma->vm_flags & VM_MIXEDMAP)) {
+		BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
+		BUG_ON(vma->vm_flags & VM_PFNMAP);
+		vma->vm_flags |= VM_MIXEDMAP;
+	}
+	return insert_page(vma, addr, page, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_insert_page);
+
+static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+			unsigned long pfn, pgprot_t prot)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int retval;
+	pte_t *pte, entry;
+	spinlock_t *ptl;
+
+	retval = -ENOMEM;
+	pte = get_locked_pte(mm, addr, &ptl);
+	if (!pte)
+		goto out;
+	retval = -EBUSY;
+	if (!pte_none(*pte))
+		goto out_unlock;
+
+	/* Ok, finally just insert the thing.. */
+	entry = pte_mkspecial(pfn_pte(pfn, prot));
+	set_pte_at(mm, addr, pte, entry);
+	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
+
+	retval = 0;
+out_unlock:
+	pte_unmap_unlock(pte, ptl);
+out:
+	return retval;
+}
+
+/**
+ * vm_insert_pfn - insert single pfn into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ *
+ * Similar to vm_insert_page, this allows drivers to insert individual pages
+ * they've allocated into a user vma. Same comments apply.
+ *
+ * This function should only be called from a vm_ops->fault handler, and
+ * in that case the handler should return NULL.
+ *
+ * vma cannot be a COW mapping.
+ *
+ * As this is called only for pages that do not currently exist, we
+ * do not need to flush old virtual caches or the TLB.
+ */
+int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+			unsigned long pfn)
+{
+	int ret;
+	pgprot_t pgprot = vma->vm_page_prot;
+	/*
+	 * Technically, architectures with pte_special can avoid all these
+	 * restrictions (same for remap_pfn_range).  However we would like
+	 * consistency in testing and feature parity among all, so we should
+	 * try to keep these invariants in place for everybody.
+	 */
+	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
+	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
+						(VM_PFNMAP|VM_MIXEDMAP));
+	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
+	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
+
+	if (addr < vma->vm_start || addr >= vma->vm_end)
+		return -EFAULT;
+	if (track_pfn_insert(vma, &pgprot, pfn))
+		return -EINVAL;
+
+	ret = insert_pfn(vma, addr, pfn, pgprot);
+
+	return ret;
+}
+EXPORT_SYMBOL(vm_insert_pfn);
+
+int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
+			unsigned long pfn)
+{
+	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
+
+	if (addr < vma->vm_start || addr >= vma->vm_end)
+		return -EFAULT;
+
+	/*
+	 * If we don't have pte special, then we have to use the pfn_valid()
+	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
+	 * refcount the page if pfn_valid is true (hence insert_page rather
+	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
+	 * without pte special, it would there be refcounted as a normal page.
+	 */
+	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
+		struct page *page;
+
+		page = pfn_to_page(pfn);
+		return insert_page(vma, addr, page, vma->vm_page_prot);
+	}
+	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_insert_mixed);
+
+/*
+ * maps a range of physical memory into the requested pages. the old
+ * mappings are removed. any references to nonexistent pages results
+ * in null mappings (currently treated as "copy-on-access")
+ */
+static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
+			unsigned long addr, unsigned long end,
+			unsigned long pfn, pgprot_t prot)
+{
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
+	if (!pte)
+		return -ENOMEM;
+	arch_enter_lazy_mmu_mode();
+	do {
+		BUG_ON(!pte_none(*pte));
+		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
+		pfn++;
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	arch_leave_lazy_mmu_mode();
+	pte_unmap_unlock(pte - 1, ptl);
+	return 0;
+}
+
+static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
+			unsigned long addr, unsigned long end,
+			unsigned long pfn, pgprot_t prot)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pfn -= addr >> PAGE_SHIFT;
+	pmd = pmd_alloc(mm, pud, addr);
+	if (!pmd)
+		return -ENOMEM;
+	VM_BUG_ON(pmd_trans_huge(*pmd));
+	do {
+		next = pmd_addr_end(addr, end);
+		if (remap_pte_range(mm, pmd, addr, next,
+				pfn + (addr >> PAGE_SHIFT), prot))
+			return -ENOMEM;
+	} while (pmd++, addr = next, addr != end);
+	return 0;
+}
+
+static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
+			unsigned long addr, unsigned long end,
+			unsigned long pfn, pgprot_t prot)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pfn -= addr >> PAGE_SHIFT;
+	pud = pud_alloc(mm, pgd, addr);
+	if (!pud)
+		return -ENOMEM;
+	do {
+		next = pud_addr_end(addr, end);
+		if (remap_pmd_range(mm, pud, addr, next,
+				pfn + (addr >> PAGE_SHIFT), prot))
+			return -ENOMEM;
+	} while (pud++, addr = next, addr != end);
+	return 0;
+}
+
+/**
+ * remap_pfn_range - remap kernel memory to userspace
+ * @vma: user vma to map to
+ * @addr: target user address to start at
+ * @pfn: physical address of kernel memory
+ * @size: size of map area
+ * @prot: page protection flags for this mapping
+ *
+ *  Note: this is only safe if the mm semaphore is held when called.
+ */
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+		    unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long end = addr + PAGE_ALIGN(size);
+	struct mm_struct *mm = vma->vm_mm;
+	int err;
+
+	/*
+	 * Physically remapped pages are special. Tell the
+	 * rest of the world about it:
+	 *   VM_IO tells people not to look at these pages
+	 *	(accesses can have side effects).
+	 *   VM_PFNMAP tells the core MM that the base pages are just
+	 *	raw PFN mappings, and do not have a "struct page" associated
+	 *	with them.
+	 *   VM_DONTEXPAND
+	 *      Disable vma merging and expanding with mremap().
+	 *   VM_DONTDUMP
+	 *      Omit vma from core dump, even when VM_IO turned off.
+	 *
+	 * There's a horrible special case to handle copy-on-write
+	 * behaviour that some programs depend on. We mark the "original"
+	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
+	 * See vm_normal_page() for details.
+	 */
+	if (is_cow_mapping(vma->vm_flags)) {
+		if (addr != vma->vm_start || end != vma->vm_end)
+			return -EINVAL;
+		vma->vm_pgoff = pfn;
+	}
+
+	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
+	if (err)
+		return -EINVAL;
+
+	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
+
+	BUG_ON(addr >= end);
+	pfn -= addr >> PAGE_SHIFT;
+	pgd = pgd_offset(mm, addr);
+	flush_cache_range(vma, addr, end);
+	do {
+		next = pgd_addr_end(addr, end);
+		err = remap_pud_range(mm, pgd, addr, next,
+				pfn + (addr >> PAGE_SHIFT), prot);
+		if (err)
+			break;
+	} while (pgd++, addr = next, addr != end);
+
+	if (err)
+		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
+
+	return err;
+}
+EXPORT_SYMBOL(remap_pfn_range);
+
+/**
+ * vm_iomap_memory - remap memory to userspace
+ * @vma: user vma to map to
+ * @start: start of area
+ * @len: size of area
+ *
+ * This is a simplified io_remap_pfn_range() for common driver use. The
+ * driver just needs to give us the physical memory range to be mapped,
+ * we'll figure out the rest from the vma information.
+ *
+ * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
+ * whatever write-combining details or similar.
+ */
+int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
+{
+	unsigned long vm_len, pfn, pages;
+
+	/* Check that the physical memory area passed in looks valid */
+	if (start + len < start)
+		return -EINVAL;
+	/*
+	 * You *really* shouldn't map things that aren't page-aligned,
+	 * but we've historically allowed it because IO memory might
+	 * just have smaller alignment.
+	 */
+	len += start & ~PAGE_MASK;
+	pfn = start >> PAGE_SHIFT;
+	pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
+	if (pfn + pages < pfn)
+		return -EINVAL;
+
+	/* We start the mapping 'vm_pgoff' pages into the area */
+	if (vma->vm_pgoff > pages)
+		return -EINVAL;
+	pfn += vma->vm_pgoff;
+	pages -= vma->vm_pgoff;
+
+	/* Can we fit all of the mapping? */
+	vm_len = vma->vm_end - vma->vm_start;
+	if (vm_len >> PAGE_SHIFT > pages)
+		return -EINVAL;
+
+	/* Ok, let it rip */
+	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_iomap_memory);
+
+static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
+				     unsigned long addr, unsigned long end,
+				     pte_fn_t fn, void *data)
+{
+	pte_t *pte;
+	int err;
+	pgtable_t token;
+	spinlock_t *uninitialized_var(ptl);
+
+	pte = (mm == &init_mm) ?
+		pte_alloc_kernel(pmd, addr) :
+		pte_alloc_map_lock(mm, pmd, addr, &ptl);
+	if (!pte)
+		return -ENOMEM;
+
+	BUG_ON(pmd_huge(*pmd));
+
+	arch_enter_lazy_mmu_mode();
+
+	token = pmd_pgtable(*pmd);
+
+	do {
+		err = fn(pte++, token, addr, data);
+		if (err)
+			break;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	arch_leave_lazy_mmu_mode();
+
+	if (mm != &init_mm)
+		pte_unmap_unlock(pte-1, ptl);
+	return err;
+}
+
+static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
+				     unsigned long addr, unsigned long end,
+				     pte_fn_t fn, void *data)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	int err;
+
+	BUG_ON(pud_huge(*pud));
+
+	pmd = pmd_alloc(mm, pud, addr);
+	if (!pmd)
+		return -ENOMEM;
+	do {
+		next = pmd_addr_end(addr, end);
+		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
+		if (err)
+			break;
+	} while (pmd++, addr = next, addr != end);
+	return err;
+}
+
+static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
+				     unsigned long addr, unsigned long end,
+				     pte_fn_t fn, void *data)
+{
+	pud_t *pud;
+	unsigned long next;
+	int err;
+
+	pud = pud_alloc(mm, pgd, addr);
+	if (!pud)
+		return -ENOMEM;
+	do {
+		next = pud_addr_end(addr, end);
+		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
+		if (err)
+			break;
+	} while (pud++, addr = next, addr != end);
+	return err;
+}
+
+/*
+ * Scan a region of virtual memory, filling in page tables as necessary
+ * and calling a provided function on each leaf page table.
+ */
+int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
+			unsigned long size, pte_fn_t fn, void *data)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long end = addr + size;
+	int err;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset(mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
+		if (err)
+			break;
+	} while (pgd++, addr = next, addr != end);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(apply_to_page_range);
+
+/*
+ * handle_pte_fault chooses page fault handler according to an entry which was
+ * read non-atomically.  Before making any commitment, on those architectures
+ * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
+ * parts, do_swap_page must check under lock before unmapping the pte and
+ * proceeding (but do_wp_page is only called after already making such a check;
+ * and do_anonymous_page can safely check later on).
+ */
+static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
+				pte_t *page_table, pte_t orig_pte)
+{
+	int same = 1;
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
+	if (sizeof(pte_t) > sizeof(unsigned long)) {
+		spinlock_t *ptl = pte_lockptr(mm, pmd);
+		spin_lock(ptl);
+		same = pte_same(*page_table, orig_pte);
+		spin_unlock(ptl);
+	}
+#endif
+	pte_unmap(page_table);
+	return same;
+}
+
+static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
+{
+	debug_dma_assert_idle(src);
+
+	/*
+	 * If the source page was a PFN mapping, we don't have
+	 * a "struct page" for it. We do a best-effort copy by
+	 * just copying from the original user address. If that
+	 * fails, we just zero-fill it. Live with it.
+	 */
+	if (unlikely(!src)) {
+		void *kaddr = kmap_atomic(dst);
+		void __user *uaddr = (void __user *)(va & PAGE_MASK);
+
+		/*
+		 * This really shouldn't fail, because the page is there
+		 * in the page tables. But it might just be unreadable,
+		 * in which case we just give up and fill the result with
+		 * zeroes.
+		 */
+		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
+			clear_page(kaddr);
+		kunmap_atomic(kaddr);
+		flush_dcache_page(dst);
+	} else
+		copy_user_highpage(dst, src, va, vma);
+}
+
+/*
+ * Notify the address space that the page is about to become writable so that
+ * it can prohibit this or wait for the page to get into an appropriate state.
+ *
+ * We do this without the lock held, so that it can sleep if it needs to.
+ */
+static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+	       unsigned long address)
+{
+	struct vm_fault vmf;
+	int ret;
+
+	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
+	vmf.pgoff = page->index;
+	vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
+	vmf.page = page;
+	vmf.cow_page = NULL;
+
+	ret = vma->vm_ops->page_mkwrite(vma, &vmf);
+	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+		return ret;
+	if (unlikely(!(ret & VM_FAULT_LOCKED))) {
+		lock_page(page);
+		if (!page->mapping) {
+			unlock_page(page);
+			return 0; /* retry */
+		}
+		ret |= VM_FAULT_LOCKED;
+	} else
+		VM_BUG_ON_PAGE(!PageLocked(page), page);
+	return ret;
+}
+
+/*
+ * Handle write page faults for pages that can be reused in the current vma
+ *
+ * This can happen either due to the mapping being with the VM_SHARED flag,
+ * or due to us being the last reference standing to the page. In either
+ * case, all we need to do here is to mark the page as writable and update
+ * any related book-keeping.
+ */
+static inline int wp_page_reuse(struct mm_struct *mm,
+			struct vm_area_struct *vma, unsigned long address,
+			pte_t *page_table, spinlock_t *ptl, pte_t orig_pte,
+			struct page *page, int page_mkwrite,
+			int dirty_shared)
+	__releases(ptl)
+{
+	pte_t entry;
+	/*
+	 * Clear the pages cpupid information as the existing
+	 * information potentially belongs to a now completely
+	 * unrelated process.
+	 */
+	if (page)
+		page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
+
+	flush_cache_page(vma, address, pte_pfn(orig_pte));
+	entry = pte_mkyoung(orig_pte);
+	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+	if (ptep_set_access_flags(vma, address, page_table, entry, 1))
+		update_mmu_cache(vma, address, page_table);
+	pte_unmap_unlock(page_table, ptl);
+
+	if (dirty_shared) {
+		struct address_space *mapping;
+		int dirtied;
+
+		if (!page_mkwrite)
+			lock_page(page);
+
+		dirtied = set_page_dirty(page);
+		VM_BUG_ON_PAGE(PageAnon(page), page);
+		mapping = page->mapping;
+		unlock_page(page);
+		page_cache_release(page);
+
+		if ((dirtied || page_mkwrite) && mapping) {
+			/*
+			 * Some device drivers do not set page.mapping
+			 * but still dirty their pages
+			 */
+			balance_dirty_pages_ratelimited(mapping);
+		}
+
+		if (!page_mkwrite)
+			file_update_time(vma->vm_file);
+	}
+
+	return VM_FAULT_WRITE;
+}
+
+/*
+ * Handle the case of a page which we actually need to copy to a new page.
+ *
+ * Called with mmap_sem locked and the old page referenced, but
+ * without the ptl held.
+ *
+ * High level logic flow:
+ *
+ * - Allocate a page, copy the content of the old page to the new one.
+ * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
+ * - Take the PTL. If the pte changed, bail out and release the allocated page
+ * - If the pte is still the way we remember it, update the page table and all
+ *   relevant references. This includes dropping the reference the page-table
+ *   held to the old page, as well as updating the rmap.
+ * - In any case, unlock the PTL and drop the reference we took to the old page.
+ */
+static int wp_page_copy(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pte_t *page_table, pmd_t *pmd,
+			pte_t orig_pte, struct page *old_page)
+{
+	struct page *new_page = NULL;
+	spinlock_t *ptl = NULL;
+	pte_t entry;
+	int page_copied = 0;
+	const unsigned long mmun_start = address & PAGE_MASK;	/* For mmu_notifiers */
+	const unsigned long mmun_end = mmun_start + PAGE_SIZE;	/* For mmu_notifiers */
+	struct mem_cgroup *memcg;
+
+	if (unlikely(anon_vma_prepare(vma)))
+		goto oom;
+
+	if (is_zero_pfn(pte_pfn(orig_pte))) {
+		new_page = alloc_zeroed_user_highpage_movable(vma, address);
+		if (!new_page)
+			goto oom;
+	} else {
+		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+		if (!new_page)
+			goto oom;
+		cow_user_page(new_page, old_page, address, vma);
+	}
+
+	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg))
+		goto oom_free_new;
+
+	__SetPageUptodate(new_page);
+
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+	/*
+	 * Re-check the pte - we dropped the lock
+	 */
+	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (likely(pte_same(*page_table, orig_pte))) {
+		if (old_page) {
+			if (!PageAnon(old_page)) {
+				dec_mm_counter_fast(mm, MM_FILEPAGES);
+				inc_mm_counter_fast(mm, MM_ANONPAGES);
+			}
+		} else {
+			inc_mm_counter_fast(mm, MM_ANONPAGES);
+		}
+		flush_cache_page(vma, address, pte_pfn(orig_pte));
+		entry = mk_pte(new_page, vma->vm_page_prot);
+		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+		/*
+		 * Clear the pte entry and flush it first, before updating the
+		 * pte with the new entry. This will avoid a race condition
+		 * seen in the presence of one thread doing SMC and another
+		 * thread doing COW.
+		 */
+		ptep_clear_flush_notify(vma, address, page_table);
+		page_add_new_anon_rmap(new_page, vma, address);
+		mem_cgroup_commit_charge(new_page, memcg, false);
+		lru_cache_add_active_or_unevictable(new_page, vma);
+		/*
+		 * We call the notify macro here because, when using secondary
+		 * mmu page tables (such as kvm shadow page tables), we want the
+		 * new page to be mapped directly into the secondary page table.
+		 */
+		set_pte_at_notify(mm, address, page_table, entry);
+		update_mmu_cache(vma, address, page_table);
+		if (old_page) {
+			/*
+			 * Only after switching the pte to the new page may
+			 * we remove the mapcount here. Otherwise another
+			 * process may come and find the rmap count decremented
+			 * before the pte is switched to the new page, and
+			 * "reuse" the old page writing into it while our pte
+			 * here still points into it and can be read by other
+			 * threads.
+			 *
+			 * The critical issue is to order this
+			 * page_remove_rmap with the ptp_clear_flush above.
+			 * Those stores are ordered by (if nothing else,)
+			 * the barrier present in the atomic_add_negative
+			 * in page_remove_rmap.
+			 *
+			 * Then the TLB flush in ptep_clear_flush ensures that
+			 * no process can access the old page before the
+			 * decremented mapcount is visible. And the old page
+			 * cannot be reused until after the decremented
+			 * mapcount is visible. So transitively, TLBs to
+			 * old page will be flushed before it can be reused.
+			 */
+			page_remove_rmap(old_page);
+		}
+
+		/* Free the old page.. */
+		new_page = old_page;
+		page_copied = 1;
+	} else {
+		mem_cgroup_cancel_charge(new_page, memcg);
+	}
+
+	if (new_page)
+		page_cache_release(new_page);
+
+	pte_unmap_unlock(page_table, ptl);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+	if (old_page) {
+		/*
+		 * Don't let another task, with possibly unlocked vma,
+		 * keep the mlocked page.
+		 */
+		if (page_copied && (vma->vm_flags & VM_LOCKED)) {
+			lock_page(old_page);	/* LRU manipulation */
+			munlock_vma_page(old_page);
+			unlock_page(old_page);
+		}
+		page_cache_release(old_page);
+	}
+	return page_copied ? VM_FAULT_WRITE : 0;
+oom_free_new:
+	page_cache_release(new_page);
+oom:
+	if (old_page)
+		page_cache_release(old_page);
+	return VM_FAULT_OOM;
+}
+
+/*
+ * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
+ * mapping
+ */
+static int wp_pfn_shared(struct mm_struct *mm,
+			struct vm_area_struct *vma, unsigned long address,
+			pte_t *page_table, spinlock_t *ptl, pte_t orig_pte,
+			pmd_t *pmd)
+{
+	if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
+		struct vm_fault vmf = {
+			.page = NULL,
+			.pgoff = linear_page_index(vma, address),
+			.virtual_address = (void __user *)(address & PAGE_MASK),
+			.flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
+		};
+		int ret;
+
+		pte_unmap_unlock(page_table, ptl);
+		ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
+		if (ret & VM_FAULT_ERROR)
+			return ret;
+		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+		/*
+		 * We might have raced with another page fault while we
+		 * released the pte_offset_map_lock.
+		 */
+		if (!pte_same(*page_table, orig_pte)) {
+			pte_unmap_unlock(page_table, ptl);
+			return 0;
+		}
+	}
+	return wp_page_reuse(mm, vma, address, page_table, ptl, orig_pte,
+			     NULL, 0, 0);
+}
+
+static int wp_page_shared(struct mm_struct *mm, struct vm_area_struct *vma,
+			  unsigned long address, pte_t *page_table,
+			  pmd_t *pmd, spinlock_t *ptl, pte_t orig_pte,
+			  struct page *old_page)
+	__releases(ptl)
+{
+	int page_mkwrite = 0;
+
+	page_cache_get(old_page);
+
+	/*
+	 * Only catch write-faults on shared writable pages,
+	 * read-only shared pages can get COWed by
+	 * get_user_pages(.write=1, .force=1).
+	 */
+	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
+		int tmp;
+
+		pte_unmap_unlock(page_table, ptl);
+		tmp = do_page_mkwrite(vma, old_page, address);
+		if (unlikely(!tmp || (tmp &
+				      (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
+			page_cache_release(old_page);
+			return tmp;
+		}
+		/*
+		 * Since we dropped the lock we need to revalidate
+		 * the PTE as someone else may have changed it.  If
+		 * they did, we just return, as we can count on the
+		 * MMU to tell us if they didn't also make it writable.
+		 */
+		page_table = pte_offset_map_lock(mm, pmd, address,
+						 &ptl);
+		if (!pte_same(*page_table, orig_pte)) {
+			unlock_page(old_page);
+			pte_unmap_unlock(page_table, ptl);
+			page_cache_release(old_page);
+			return 0;
+		}
+		page_mkwrite = 1;
+	}
+
+	return wp_page_reuse(mm, vma, address, page_table, ptl,
+			     orig_pte, old_page, page_mkwrite, 1);
+}
+
+/*
+ * This routine handles present pages, when users try to write
+ * to a shared page. It is done by copying the page to a new address
+ * and decrementing the shared-page counter for the old page.
+ *
+ * Note that this routine assumes that the protection checks have been
+ * done by the caller (the low-level page fault routine in most cases).
+ * Thus we can safely just mark it writable once we've done any necessary
+ * COW.
+ *
+ * We also mark the page dirty at this point even though the page will
+ * change only once the write actually happens. This avoids a few races,
+ * and potentially makes it more efficient.
+ *
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults), with pte both mapped and locked.
+ * We return with mmap_sem still held, but pte unmapped and unlocked.
+ */
+static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pte_t *page_table, pmd_t *pmd,
+		spinlock_t *ptl, pte_t orig_pte)
+	__releases(ptl)
+{
+	struct page *old_page;
+
+	old_page = vm_normal_page(vma, address, orig_pte);
+	if (!old_page) {
+		/*
+		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
+		 * VM_PFNMAP VMA.
+		 *
+		 * We should not cow pages in a shared writeable mapping.
+		 * Just mark the pages writable and/or call ops->pfn_mkwrite.
+		 */
+		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
+				     (VM_WRITE|VM_SHARED))
+			return wp_pfn_shared(mm, vma, address, page_table, ptl,
+					     orig_pte, pmd);
+
+		pte_unmap_unlock(page_table, ptl);
+		return wp_page_copy(mm, vma, address, page_table, pmd,
+				    orig_pte, old_page);
+	}
+
+	/*
+	 * Take out anonymous pages first, anonymous shared vmas are
+	 * not dirty accountable.
+	 */
+	if (PageAnon(old_page) && !PageKsm(old_page)) {
+		if (!trylock_page(old_page)) {
+			page_cache_get(old_page);
+			pte_unmap_unlock(page_table, ptl);
+			lock_page(old_page);
+			page_table = pte_offset_map_lock(mm, pmd, address,
+							 &ptl);
+			if (!pte_same(*page_table, orig_pte)) {
+				unlock_page(old_page);
+				pte_unmap_unlock(page_table, ptl);
+				page_cache_release(old_page);
+				return 0;
+			}
+			page_cache_release(old_page);
+		}
+		if (reuse_swap_page(old_page)) {
+			/*
+			 * The page is all ours.  Move it to our anon_vma so
+			 * the rmap code will not search our parent or siblings.
+			 * Protected against the rmap code by the page lock.
+			 */
+			page_move_anon_rmap(old_page, vma, address);
+			unlock_page(old_page);
+			return wp_page_reuse(mm, vma, address, page_table, ptl,
+					     orig_pte, old_page, 0, 0);
+		}
+		unlock_page(old_page);
+	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
+					(VM_WRITE|VM_SHARED))) {
+		return wp_page_shared(mm, vma, address, page_table, pmd,
+				      ptl, orig_pte, old_page);
+	}
+
+	/*
+	 * Ok, we need to copy. Oh, well..
+	 */
+	page_cache_get(old_page);
+
+	pte_unmap_unlock(page_table, ptl);
+	return wp_page_copy(mm, vma, address, page_table, pmd,
+			    orig_pte, old_page);
+}
+
+static void unmap_mapping_range_vma(struct vm_area_struct *vma,
+		unsigned long start_addr, unsigned long end_addr,
+		struct zap_details *details)
+{
+	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
+}
+
+static inline void unmap_mapping_range_tree(struct rb_root *root,
+					    struct zap_details *details)
+{
+	struct vm_area_struct *vma;
+	pgoff_t vba, vea, zba, zea;
+
+	vma_interval_tree_foreach(vma, root,
+			details->first_index, details->last_index) {
+
+		vba = vma->vm_pgoff;
+		vea = vba + vma_pages(vma) - 1;
+		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
+		zba = details->first_index;
+		if (zba < vba)
+			zba = vba;
+		zea = details->last_index;
+		if (zea > vea)
+			zea = vea;
+
+		unmap_mapping_range_vma(vma,
+			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
+			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
+				details);
+	}
+}
+
+/**
+ * unmap_mapping_range - unmap the portion of all mmaps in the specified
+ * address_space corresponding to the specified page range in the underlying
+ * file.
+ *
+ * @mapping: the address space containing mmaps to be unmapped.
+ * @holebegin: byte in first page to unmap, relative to the start of
+ * the underlying file.  This will be rounded down to a PAGE_SIZE
+ * boundary.  Note that this is different from truncate_pagecache(), which
+ * must keep the partial page.  In contrast, we must get rid of
+ * partial pages.
+ * @holelen: size of prospective hole in bytes.  This will be rounded
+ * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
+ * end of the file.
+ * @even_cows: 1 when truncating a file, unmap even private COWed pages;
+ * but 0 when invalidating pagecache, don't throw away private data.
+ */
+void unmap_mapping_range(struct address_space *mapping,
+		loff_t const holebegin, loff_t const holelen, int even_cows)
+{
+	struct zap_details details;
+	pgoff_t hba = holebegin >> PAGE_SHIFT;
+	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	/* Check for overflow. */
+	if (sizeof(holelen) > sizeof(hlen)) {
+		long long holeend =
+			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
+		if (holeend & ~(long long)ULONG_MAX)
+			hlen = ULONG_MAX - hba + 1;
+	}
+
+	details.check_mapping = even_cows? NULL: mapping;
+	details.first_index = hba;
+	details.last_index = hba + hlen - 1;
+	if (details.last_index < details.first_index)
+		details.last_index = ULONG_MAX;
+
+
+	/* DAX uses i_mmap_lock to serialise file truncate vs page fault */
+	i_mmap_lock_write(mapping);
+	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
+		unmap_mapping_range_tree(&mapping->i_mmap, &details);
+	i_mmap_unlock_write(mapping);
+}
+EXPORT_SYMBOL(unmap_mapping_range);
+
+/*
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with pte unmapped and unlocked.
+ *
+ * We return with the mmap_sem locked or unlocked in the same cases
+ * as does filemap_fault().
+ */
+static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pte_t *page_table, pmd_t *pmd,
+		unsigned int flags, pte_t orig_pte)
+{
+	spinlock_t *ptl;
+	struct page *page, *swapcache;
+	struct mem_cgroup *memcg;
+	swp_entry_t entry;
+	pte_t pte;
+	int locked;
+	int exclusive = 0;
+	int ret = 0;
+
+	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
+		goto out;
+
+	entry = pte_to_swp_entry(orig_pte);
+	if (unlikely(non_swap_entry(entry))) {
+		if (is_migration_entry(entry)) {
+			migration_entry_wait(mm, pmd, address);
+		} else if (is_hwpoison_entry(entry)) {
+			ret = VM_FAULT_HWPOISON;
+		} else {
+			print_bad_pte(vma, address, orig_pte, NULL);
+			ret = VM_FAULT_SIGBUS;
+		}
+		goto out;
+	}
+	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
+	page = lookup_swap_cache(entry);
+	if (!page) {
+		page = swapin_readahead(entry,
+					GFP_HIGHUSER_MOVABLE, vma, address);
+		if (!page) {
+			/*
+			 * Back out if somebody else faulted in this pte
+			 * while we released the pte lock.
+			 */
+			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+			if (likely(pte_same(*page_table, orig_pte)))
+				ret = VM_FAULT_OOM;
+			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+			goto unlock;
+		}
+
+		/* Had to read the page from swap area: Major fault */
+		ret = VM_FAULT_MAJOR;
+		count_vm_event(PGMAJFAULT);
+		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
+	} else if (PageHWPoison(page)) {
+		/*
+		 * hwpoisoned dirty swapcache pages are kept for killing
+		 * owner processes (which may be unknown at hwpoison time)
+		 */
+		ret = VM_FAULT_HWPOISON;
+		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+		swapcache = page;
+		goto out_release;
+	}
+
+	swapcache = page;
+	locked = lock_page_or_retry(page, mm, flags);
+
+	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+	if (!locked) {
+		ret |= VM_FAULT_RETRY;
+		goto out_release;
+	}
+
+	/*
+	 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
+	 * release the swapcache from under us.  The page pin, and pte_same
+	 * test below, are not enough to exclude that.  Even if it is still
+	 * swapcache, we need to check that the page's swap has not changed.
+	 */
+	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
+		goto out_page;
+
+	page = ksm_might_need_to_copy(page, vma, address);
+	if (unlikely(!page)) {
+		ret = VM_FAULT_OOM;
+		page = swapcache;
+		goto out_page;
+	}
+
+	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) {
+		ret = VM_FAULT_OOM;
+		goto out_page;
+	}
+
+	/*
+	 * Back out if somebody else already faulted in this pte.
+	 */
+	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (unlikely(!pte_same(*page_table, orig_pte)))
+		goto out_nomap;
+
+	if (unlikely(!PageUptodate(page))) {
+		ret = VM_FAULT_SIGBUS;
+		goto out_nomap;
+	}
+
+	/*
+	 * The page isn't present yet, go ahead with the fault.
+	 *
+	 * Be careful about the sequence of operations here.
+	 * To get its accounting right, reuse_swap_page() must be called
+	 * while the page is counted on swap but not yet in mapcount i.e.
+	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
+	 * must be called after the swap_free(), or it will never succeed.
+	 */
+
+	inc_mm_counter_fast(mm, MM_ANONPAGES);
+	dec_mm_counter_fast(mm, MM_SWAPENTS);
+	pte = mk_pte(page, vma->vm_page_prot);
+	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
+		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
+		flags &= ~FAULT_FLAG_WRITE;
+		ret |= VM_FAULT_WRITE;
+		exclusive = 1;
+	}
+	flush_icache_page(vma, page);
+	if (pte_swp_soft_dirty(orig_pte))
+		pte = pte_mksoft_dirty(pte);
+	set_pte_at(mm, address, page_table, pte);
+	if (page == swapcache) {
+		do_page_add_anon_rmap(page, vma, address, exclusive);
+		mem_cgroup_commit_charge(page, memcg, true);
+	} else { /* ksm created a completely new copy */
+		page_add_new_anon_rmap(page, vma, address);
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_active_or_unevictable(page, vma);
+	}
+
+	swap_free(entry);
+	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
+		try_to_free_swap(page);
+	unlock_page(page);
+	if (page != swapcache) {
+		/*
+		 * Hold the lock to avoid the swap entry to be reused
+		 * until we take the PT lock for the pte_same() check
+		 * (to avoid false positives from pte_same). For
+		 * further safety release the lock after the swap_free
+		 * so that the swap count won't change under a
+		 * parallel locked swapcache.
+		 */
+		unlock_page(swapcache);
+		page_cache_release(swapcache);
+	}
+
+	if (flags & FAULT_FLAG_WRITE) {
+		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
+		if (ret & VM_FAULT_ERROR)
+			ret &= VM_FAULT_ERROR;
+		goto out;
+	}
+
+	/* No need to invalidate - it was non-present before */
+	update_mmu_cache(vma, address, page_table);
+unlock:
+	pte_unmap_unlock(page_table, ptl);
+out:
+	return ret;
+out_nomap:
+	mem_cgroup_cancel_charge(page, memcg);
+	pte_unmap_unlock(page_table, ptl);
+out_page:
+	unlock_page(page);
+out_release:
+	page_cache_release(page);
+	if (page != swapcache) {
+		unlock_page(swapcache);
+		page_cache_release(swapcache);
+	}
+	return ret;
+}
+
+/*
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with mmap_sem still held, but pte unmapped and unlocked.
+ */
+static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pte_t *page_table, pmd_t *pmd,
+		unsigned int flags)
+{
+	struct mem_cgroup *memcg;
+	struct page *page;
+	spinlock_t *ptl;
+	pte_t entry;
+
+	pte_unmap(page_table);
+
+	/* File mapping without ->vm_ops ? */
+	if (vma->vm_flags & VM_SHARED)
+		return VM_FAULT_SIGBUS;
+
+	/* Use the zero-page for reads */
+	if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
+		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
+						vma->vm_page_prot));
+		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+		if (!pte_none(*page_table))
+			goto unlock;
+		/* Deliver the page fault to userland, check inside PT lock */
+		if (userfaultfd_missing(vma)) {
+			pte_unmap_unlock(page_table, ptl);
+			return handle_userfault(vma, address, flags,
+						VM_UFFD_MISSING);
+		}
+		goto setpte;
+	}
+
+	/* Allocate our own private page. */
+	if (unlikely(anon_vma_prepare(vma)))
+		goto oom;
+	page = alloc_zeroed_user_highpage_movable(vma, address);
+	if (!page)
+		goto oom;
+
+	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
+		goto oom_free_page;
+
+	/*
+	 * The memory barrier inside __SetPageUptodate makes sure that
+	 * preceeding stores to the page contents become visible before
+	 * the set_pte_at() write.
+	 */
+	__SetPageUptodate(page);
+
+	entry = mk_pte(page, vma->vm_page_prot);
+	if (vma->vm_flags & VM_WRITE)
+		entry = pte_mkwrite(pte_mkdirty(entry));
+
+	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (!pte_none(*page_table))
+		goto release;
+
+	/* Deliver the page fault to userland, check inside PT lock */
+	if (userfaultfd_missing(vma)) {
+		pte_unmap_unlock(page_table, ptl);
+		mem_cgroup_cancel_charge(page, memcg);
+		page_cache_release(page);
+		return handle_userfault(vma, address, flags,
+					VM_UFFD_MISSING);
+	}
+
+	inc_mm_counter_fast(mm, MM_ANONPAGES);
+	page_add_new_anon_rmap(page, vma, address);
+	mem_cgroup_commit_charge(page, memcg, false);
+	lru_cache_add_active_or_unevictable(page, vma);
+setpte:
+	set_pte_at(mm, address, page_table, entry);
+
+	/* No need to invalidate - it was non-present before */
+	update_mmu_cache(vma, address, page_table);
+unlock:
+	pte_unmap_unlock(page_table, ptl);
+	return 0;
+release:
+	mem_cgroup_cancel_charge(page, memcg);
+	page_cache_release(page);
+	goto unlock;
+oom_free_page:
+	page_cache_release(page);
+oom:
+	return VM_FAULT_OOM;
+}
+
+/*
+ * The mmap_sem must have been held on entry, and may have been
+ * released depending on flags and vma->vm_ops->fault() return value.
+ * See filemap_fault() and __lock_page_retry().
+ */
+static int __do_fault(struct vm_area_struct *vma, unsigned long address,
+			pgoff_t pgoff, unsigned int flags,
+			struct page *cow_page, struct page **page)
+{
+	struct vm_fault vmf;
+	int ret;
+
+	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
+	vmf.pgoff = pgoff;
+	vmf.flags = flags;
+	vmf.page = NULL;
+	vmf.cow_page = cow_page;
+
+	ret = vma->vm_ops->fault(vma, &vmf);
+	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+		return ret;
+	if (!vmf.page)
+		goto out;
+
+	if (unlikely(PageHWPoison(vmf.page))) {
+		if (ret & VM_FAULT_LOCKED)
+			unlock_page(vmf.page);
+		page_cache_release(vmf.page);
+		return VM_FAULT_HWPOISON;
+	}
+
+	if (unlikely(!(ret & VM_FAULT_LOCKED)))
+		lock_page(vmf.page);
+	else
+		VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
+
+ out:
+	*page = vmf.page;
+	return ret;
+}
+
+/**
+ * do_set_pte - setup new PTE entry for given page and add reverse page mapping.
+ *
+ * @vma: virtual memory area
+ * @address: user virtual address
+ * @page: page to map
+ * @pte: pointer to target page table entry
+ * @write: true, if new entry is writable
+ * @anon: true, if it's anonymous page
+ *
+ * Caller must hold page table lock relevant for @pte.
+ *
+ * Target users are page handler itself and implementations of
+ * vm_ops->map_pages.
+ */
+void do_set_pte(struct vm_area_struct *vma, unsigned long address,
+		struct page *page, pte_t *pte, bool write, bool anon)
+{
+	pte_t entry;
+
+	flush_icache_page(vma, page);
+	entry = mk_pte(page, vma->vm_page_prot);
+	if (write)
+		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+	if (anon) {
+		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
+		page_add_new_anon_rmap(page, vma, address);
+	} else {
+		inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
+		page_add_file_rmap(page);
+	}
+	set_pte_at(vma->vm_mm, address, pte, entry);
+
+	/* no need to invalidate: a not-present page won't be cached */
+	update_mmu_cache(vma, address, pte);
+}
+
+static unsigned long fault_around_bytes __read_mostly =
+	rounddown_pow_of_two(65536);
+
+#ifdef CONFIG_DEBUG_FS
+static int fault_around_bytes_get(void *data, u64 *val)
+{
+	*val = fault_around_bytes;
+	return 0;
+}
+
+/*
+ * fault_around_pages() and fault_around_mask() expects fault_around_bytes
+ * rounded down to nearest page order. It's what do_fault_around() expects to
+ * see.
+ */
+static int fault_around_bytes_set(void *data, u64 val)
+{
+	if (val / PAGE_SIZE > PTRS_PER_PTE)
+		return -EINVAL;
+	if (val > PAGE_SIZE)
+		fault_around_bytes = rounddown_pow_of_two(val);
+	else
+		fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
+		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
+
+static int __init fault_around_debugfs(void)
+{
+	void *ret;
+
+	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
+			&fault_around_bytes_fops);
+	if (!ret)
+		pr_warn("Failed to create fault_around_bytes in debugfs");
+	return 0;
+}
+late_initcall(fault_around_debugfs);
+#endif
+
+/*
+ * do_fault_around() tries to map few pages around the fault address. The hope
+ * is that the pages will be needed soon and this will lower the number of
+ * faults to handle.
+ *
+ * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
+ * not ready to be mapped: not up-to-date, locked, etc.
+ *
+ * This function is called with the page table lock taken. In the split ptlock
+ * case the page table lock only protects only those entries which belong to
+ * the page table corresponding to the fault address.
+ *
+ * This function doesn't cross the VMA boundaries, in order to call map_pages()
+ * only once.
+ *
+ * fault_around_pages() defines how many pages we'll try to map.
+ * do_fault_around() expects it to return a power of two less than or equal to
+ * PTRS_PER_PTE.
+ *
+ * The virtual address of the area that we map is naturally aligned to the
+ * fault_around_pages() value (and therefore to page order).  This way it's
+ * easier to guarantee that we don't cross page table boundaries.
+ */
+static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
+		pte_t *pte, pgoff_t pgoff, unsigned int flags)
+{
+	unsigned long start_addr, nr_pages, mask;
+	pgoff_t max_pgoff;
+	struct vm_fault vmf;
+	int off;
+
+	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
+	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
+
+	start_addr = max(address & mask, vma->vm_start);
+	off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
+	pte -= off;
+	pgoff -= off;
+
+	/*
+	 *  max_pgoff is either end of page table or end of vma
+	 *  or fault_around_pages() from pgoff, depending what is nearest.
+	 */
+	max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
+		PTRS_PER_PTE - 1;
+	max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
+			pgoff + nr_pages - 1);
+
+	/* Check if it makes any sense to call ->map_pages */
+	while (!pte_none(*pte)) {
+		if (++pgoff > max_pgoff)
+			return;
+		start_addr += PAGE_SIZE;
+		if (start_addr >= vma->vm_end)
+			return;
+		pte++;
+	}
+
+	vmf.virtual_address = (void __user *) start_addr;
+	vmf.pte = pte;
+	vmf.pgoff = pgoff;
+	vmf.max_pgoff = max_pgoff;
+	vmf.flags = flags;
+	vma->vm_ops->map_pages(vma, &vmf);
+}
+
+static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pmd_t *pmd,
+		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
+{
+	struct page *fault_page;
+	spinlock_t *ptl;
+	pte_t *pte;
+	int ret = 0;
+
+	/*
+	 * Let's call ->map_pages() first and use ->fault() as fallback
+	 * if page by the offset is not ready to be mapped (cold cache or
+	 * something).
+	 */
+	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
+		pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+		do_fault_around(vma, address, pte, pgoff, flags);
+		if (!pte_same(*pte, orig_pte))
+			goto unlock_out;
+		pte_unmap_unlock(pte, ptl);
+	}
+
+	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
+	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+		return ret;
+
+	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (unlikely(!pte_same(*pte, orig_pte))) {
+		pte_unmap_unlock(pte, ptl);
+		unlock_page(fault_page);
+		page_cache_release(fault_page);
+		return ret;
+	}
+	do_set_pte(vma, address, fault_page, pte, false, false);
+	unlock_page(fault_page);
+unlock_out:
+	pte_unmap_unlock(pte, ptl);
+	return ret;
+}
+
+static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pmd_t *pmd,
+		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
+{
+	struct page *fault_page, *new_page;
+	struct mem_cgroup *memcg;
+	spinlock_t *ptl;
+	pte_t *pte;
+	int ret;
+
+	if (unlikely(anon_vma_prepare(vma)))
+		return VM_FAULT_OOM;
+
+	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+	if (!new_page)
+		return VM_FAULT_OOM;
+
+	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) {
+		page_cache_release(new_page);
+		return VM_FAULT_OOM;
+	}
+
+	ret = __do_fault(vma, address, pgoff, flags, new_page, &fault_page);
+	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+		goto uncharge_out;
+
+	if (fault_page)
+		copy_user_highpage(new_page, fault_page, address, vma);
+	__SetPageUptodate(new_page);
+
+	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (unlikely(!pte_same(*pte, orig_pte))) {
+		pte_unmap_unlock(pte, ptl);
+		if (fault_page) {
+			unlock_page(fault_page);
+			page_cache_release(fault_page);
+		} else {
+			/*
+			 * The fault handler has no page to lock, so it holds
+			 * i_mmap_lock for read to protect against truncate.
+			 */
+			i_mmap_unlock_read(vma->vm_file->f_mapping);
+		}
+		goto uncharge_out;
+	}
+	do_set_pte(vma, address, new_page, pte, true, true);
+	mem_cgroup_commit_charge(new_page, memcg, false);
+	lru_cache_add_active_or_unevictable(new_page, vma);
+	pte_unmap_unlock(pte, ptl);
+	if (fault_page) {
+		unlock_page(fault_page);
+		page_cache_release(fault_page);
+	} else {
+		/*
+		 * The fault handler has no page to lock, so it holds
+		 * i_mmap_lock for read to protect against truncate.
+		 */
+		i_mmap_unlock_read(vma->vm_file->f_mapping);
+	}
+	return ret;
+uncharge_out:
+	mem_cgroup_cancel_charge(new_page, memcg);
+	page_cache_release(new_page);
+	return ret;
+}
+
+static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pmd_t *pmd,
+		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
+{
+	struct page *fault_page;
+	struct address_space *mapping;
+	spinlock_t *ptl;
+	pte_t *pte;
+	int dirtied = 0;
+	int ret, tmp;
+
+	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
+	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+		return ret;
+
+	/*
+	 * Check if the backing address space wants to know that the page is
+	 * about to become writable
+	 */
+	if (vma->vm_ops->page_mkwrite) {
+		unlock_page(fault_page);
+		tmp = do_page_mkwrite(vma, fault_page, address);
+		if (unlikely(!tmp ||
+				(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
+			page_cache_release(fault_page);
+			return tmp;
+		}
+	}
+
+	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (unlikely(!pte_same(*pte, orig_pte))) {
+		pte_unmap_unlock(pte, ptl);
+		unlock_page(fault_page);
+		page_cache_release(fault_page);
+		return ret;
+	}
+	do_set_pte(vma, address, fault_page, pte, true, false);
+	pte_unmap_unlock(pte, ptl);
+
+	if (set_page_dirty(fault_page))
+		dirtied = 1;
+	/*
+	 * Take a local copy of the address_space - page.mapping may be zeroed
+	 * by truncate after unlock_page().   The address_space itself remains
+	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
+	 * release semantics to prevent the compiler from undoing this copying.
+	 */
+	mapping = fault_page->mapping;
+	unlock_page(fault_page);
+	if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
+		/*
+		 * Some device drivers do not set page.mapping but still
+		 * dirty their pages
+		 */
+		balance_dirty_pages_ratelimited(mapping);
+	}
+
+	if (!vma->vm_ops->page_mkwrite)
+		file_update_time(vma->vm_file);
+
+	return ret;
+}
+
+/*
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults).
+ * The mmap_sem may have been released depending on flags and our
+ * return value.  See filemap_fault() and __lock_page_or_retry().
+ */
+static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+		unsigned long address, pte_t *page_table, pmd_t *pmd,
+		unsigned int flags, pte_t orig_pte)
+{
+	pgoff_t pgoff = (((address & PAGE_MASK)
+			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+
+	pte_unmap(page_table);
+	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
+	if (!vma->vm_ops->fault)
+		return VM_FAULT_SIGBUS;
+	if (!(flags & FAULT_FLAG_WRITE))
+		return do_read_fault(mm, vma, address, pmd, pgoff, flags,
+				orig_pte);
+	if (!(vma->vm_flags & VM_SHARED))
+		return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
+				orig_pte);
+	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
+}
+
+static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
+				unsigned long addr, int page_nid,
+				int *flags)
+{
+	get_page(page);
+
+	count_vm_numa_event(NUMA_HINT_FAULTS);
+	if (page_nid == numa_node_id()) {
+		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
+		*flags |= TNF_FAULT_LOCAL;
+	}
+
+	return mpol_misplaced(page, vma, addr);
+}
+
+static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
+		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
+{
+	struct page *page = NULL;
+	spinlock_t *ptl;
+	int page_nid = -1;
+	int last_cpupid;
+	int target_nid;
+	bool migrated = false;
+	bool was_writable = pte_write(pte);
+	int flags = 0;
+
+	/* A PROT_NONE fault should not end up here */
+	BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
+
+	/*
+	* The "pte" at this point cannot be used safely without
+	* validation through pte_unmap_same(). It's of NUMA type but
+	* the pfn may be screwed if the read is non atomic.
+	*
+	* We can safely just do a "set_pte_at()", because the old
+	* page table entry is not accessible, so there would be no
+	* concurrent hardware modifications to the PTE.
+	*/
+	ptl = pte_lockptr(mm, pmd);
+	spin_lock(ptl);
+	if (unlikely(!pte_same(*ptep, pte))) {
+		pte_unmap_unlock(ptep, ptl);
+		goto out;
+	}
+
+	/* Make it present again */
+	pte = pte_modify(pte, vma->vm_page_prot);
+	pte = pte_mkyoung(pte);
+	if (was_writable)
+		pte = pte_mkwrite(pte);
+	set_pte_at(mm, addr, ptep, pte);
+	update_mmu_cache(vma, addr, ptep);
+
+	page = vm_normal_page(vma, addr, pte);
+	if (!page) {
+		pte_unmap_unlock(ptep, ptl);
+		return 0;
+	}
+
+	/*
+	 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
+	 * much anyway since they can be in shared cache state. This misses
+	 * the case where a mapping is writable but the process never writes
+	 * to it but pte_write gets cleared during protection updates and
+	 * pte_dirty has unpredictable behaviour between PTE scan updates,
+	 * background writeback, dirty balancing and application behaviour.
+	 */
+	if (!(vma->vm_flags & VM_WRITE))
+		flags |= TNF_NO_GROUP;
+
+	/*
+	 * Flag if the page is shared between multiple address spaces. This
+	 * is later used when determining whether to group tasks together
+	 */
+	if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
+		flags |= TNF_SHARED;
+
+	last_cpupid = page_cpupid_last(page);
+	page_nid = page_to_nid(page);
+	target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
+	pte_unmap_unlock(ptep, ptl);
+	if (target_nid == -1) {
+		put_page(page);
+		goto out;
+	}
+
+	/* Migrate to the requested node */
+	migrated = migrate_misplaced_page(page, vma, target_nid);
+	if (migrated) {
+		page_nid = target_nid;
+		flags |= TNF_MIGRATED;
+	} else
+		flags |= TNF_MIGRATE_FAIL;
+
+out:
+	if (page_nid != -1)
+		task_numa_fault(last_cpupid, page_nid, 1, flags);
+	return 0;
+}
+
+static int create_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pmd_t *pmd, unsigned int flags)
+{
+	if (vma_is_anonymous(vma))
+		return do_huge_pmd_anonymous_page(mm, vma, address, pmd, flags);
+	if (vma->vm_ops->pmd_fault)
+		return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
+	return VM_FAULT_FALLBACK;
+}
+
+static int wp_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pmd_t *pmd, pmd_t orig_pmd,
+			unsigned int flags)
+{
+	if (vma_is_anonymous(vma))
+		return do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd);
+	if (vma->vm_ops->pmd_fault)
+		return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
+	return VM_FAULT_FALLBACK;
+}
+
+/*
+ * These routines also need to handle stuff like marking pages dirty
+ * and/or accessed for architectures that don't do it in hardware (most
+ * RISC architectures).  The early dirtying is also good on the i386.
+ *
+ * There is also a hook called "update_mmu_cache()" that architectures
+ * with external mmu caches can use to update those (ie the Sparc or
+ * PowerPC hashed page tables that act as extended TLBs).
+ *
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with pte unmapped and unlocked.
+ *
+ * The mmap_sem may have been released depending on flags and our
+ * return value.  See filemap_fault() and __lock_page_or_retry().
+ */
+static int handle_pte_fault(struct mm_struct *mm,
+		     struct vm_area_struct *vma, unsigned long address,
+		     pte_t *pte, pmd_t *pmd, unsigned int flags)
+{
+	pte_t entry;
+	spinlock_t *ptl;
+
+	/*
+	 * some architectures can have larger ptes than wordsize,
+	 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and CONFIG_32BIT=y,
+	 * so READ_ONCE or ACCESS_ONCE cannot guarantee atomic accesses.
+	 * The code below just needs a consistent view for the ifs and
+	 * we later double check anyway with the ptl lock held. So here
+	 * a barrier will do.
+	 */
+	entry = *pte;
+	barrier();
+	if (!pte_present(entry)) {
+		if (pte_none(entry)) {
+			if (vma_is_anonymous(vma))
+				return do_anonymous_page(mm, vma, address,
+							 pte, pmd, flags);
+			else
+				return do_fault(mm, vma, address, pte, pmd,
+						flags, entry);
+		}
+		return do_swap_page(mm, vma, address,
+					pte, pmd, flags, entry);
+	}
+
+	if (pte_protnone(entry))
+		return do_numa_page(mm, vma, address, entry, pte, pmd);
+
+	ptl = pte_lockptr(mm, pmd);
+	spin_lock(ptl);
+	if (unlikely(!pte_same(*pte, entry)))
+		goto unlock;
+	if (flags & FAULT_FLAG_WRITE) {
+		if (!pte_write(entry))
+			return do_wp_page(mm, vma, address,
+					pte, pmd, ptl, entry);
+		entry = pte_mkdirty(entry);
+	}
+	entry = pte_mkyoung(entry);
+	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
+		update_mmu_cache(vma, address, pte);
+	} else {
+		/*
+		 * This is needed only for protection faults but the arch code
+		 * is not yet telling us if this is a protection fault or not.
+		 * This still avoids useless tlb flushes for .text page faults
+		 * with threads.
+		 */
+		if (flags & FAULT_FLAG_WRITE)
+			flush_tlb_fix_spurious_fault(vma, address);
+	}
+unlock:
+	pte_unmap_unlock(pte, ptl);
+	return 0;
+}
+
+/*
+ * By the time we get here, we already hold the mm semaphore
+ *
+ * The mmap_sem may have been released depending on flags and our
+ * return value.  See filemap_fault() and __lock_page_or_retry().
+ */
+static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+			     unsigned long address, unsigned int flags)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	if (unlikely(is_vm_hugetlb_page(vma)))
+		return hugetlb_fault(mm, vma, address, flags);
+
+	pgd = pgd_offset(mm, address);
+	pud = pud_alloc(mm, pgd, address);
+	if (!pud)
+		return VM_FAULT_OOM;
+	pmd = pmd_alloc(mm, pud, address);
+	if (!pmd)
+		return VM_FAULT_OOM;
+	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
+		int ret = create_huge_pmd(mm, vma, address, pmd, flags);
+		if (!(ret & VM_FAULT_FALLBACK))
+			return ret;
+	} else {
+		pmd_t orig_pmd = *pmd;
+		int ret;
+
+		barrier();
+		if (pmd_trans_huge(orig_pmd)) {
+			unsigned int dirty = flags & FAULT_FLAG_WRITE;
+
+			/*
+			 * If the pmd is splitting, return and retry the
+			 * the fault.  Alternative: wait until the split
+			 * is done, and goto retry.
+			 */
+			if (pmd_trans_splitting(orig_pmd))
+				return 0;
+
+			if (pmd_protnone(orig_pmd))
+				return do_huge_pmd_numa_page(mm, vma, address,
+							     orig_pmd, pmd);
+
+			if (dirty && !pmd_write(orig_pmd)) {
+				ret = wp_huge_pmd(mm, vma, address, pmd,
+							orig_pmd, flags);
+				if (!(ret & VM_FAULT_FALLBACK))
+					return ret;
+			} else {
+				huge_pmd_set_accessed(mm, vma, address, pmd,
+						      orig_pmd, dirty);
+				return 0;
+			}
+		}
+	}
+
+	/*
+	 * Use __pte_alloc instead of pte_alloc_map, because we can't
+	 * run pte_offset_map on the pmd, if an huge pmd could
+	 * materialize from under us from a different thread.
+	 */
+	if (unlikely(pmd_none(*pmd)) &&
+	    unlikely(__pte_alloc(mm, vma, pmd, address)))
+		return VM_FAULT_OOM;
+	/*
+	 * If a huge pmd materialized under us just retry later.  Use
+	 * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
+	 * didn't become pmd_trans_huge under us and then back to pmd_none, as
+	 * a result of MADV_DONTNEED running immediately after a huge pmd fault
+	 * in a different thread of this mm, in turn leading to a misleading
+	 * pmd_trans_huge() retval.  All we have to ensure is that it is a
+	 * regular pmd that we can walk with pte_offset_map() and we can do that
+	 * through an atomic read in C, which is what pmd_trans_unstable()
+	 * provides.
+	 */
+	if (unlikely(pmd_trans_unstable(pmd)))
+		return 0;
+	/*
+	 * A regular pmd is established and it can't morph into a huge pmd
+	 * from under us anymore at this point because we hold the mmap_sem
+	 * read mode and khugepaged takes it in write mode. So now it's
+	 * safe to run pte_offset_map().
+	 */
+	pte = pte_offset_map(pmd, address);
+
+	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
+}
+
+/*
+ * By the time we get here, we already hold the mm semaphore
+ *
+ * The mmap_sem may have been released depending on flags and our
+ * return value.  See filemap_fault() and __lock_page_or_retry().
+ */
+int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+		    unsigned long address, unsigned int flags)
+{
+	int ret;
+
+	__set_current_state(TASK_RUNNING);
+
+	count_vm_event(PGFAULT);
+	mem_cgroup_count_vm_event(mm, PGFAULT);
+
+	/* do counter updates before entering really critical section. */
+	check_sync_rss_stat(current);
+
+	/*
+	 * Enable the memcg OOM handling for faults triggered in user
+	 * space.  Kernel faults are handled more gracefully.
+	 */
+	if (flags & FAULT_FLAG_USER)
+		mem_cgroup_oom_enable();
+
+	ret = __handle_mm_fault(mm, vma, address, flags);
+
+	if (flags & FAULT_FLAG_USER) {
+		mem_cgroup_oom_disable();
+                /*
+                 * The task may have entered a memcg OOM situation but
+                 * if the allocation error was handled gracefully (no
+                 * VM_FAULT_OOM), there is no need to kill anything.
+                 * Just clean up the OOM state peacefully.
+                 */
+                if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
+                        mem_cgroup_oom_synchronize(false);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(handle_mm_fault);
+
+#ifndef __PAGETABLE_PUD_FOLDED
+/*
+ * Allocate page upper directory.
+ * We've already handled the fast-path in-line.
+ */
+int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
+{
+	pud_t *new = pud_alloc_one(mm, address);
+	if (!new)
+		return -ENOMEM;
+
+	smp_wmb(); /* See comment in __pte_alloc */
+
+	spin_lock(&mm->page_table_lock);
+	if (pgd_present(*pgd))		/* Another has populated it */
+		pud_free(mm, new);
+	else
+		pgd_populate(mm, pgd, new);
+	spin_unlock(&mm->page_table_lock);
+	return 0;
+}
+#endif /* __PAGETABLE_PUD_FOLDED */
+
+#ifndef __PAGETABLE_PMD_FOLDED
+/*
+ * Allocate page middle directory.
+ * We've already handled the fast-path in-line.
+ */
+int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
+{
+	pmd_t *new = pmd_alloc_one(mm, address);
+	if (!new)
+		return -ENOMEM;
+
+	smp_wmb(); /* See comment in __pte_alloc */
+
+	spin_lock(&mm->page_table_lock);
+#ifndef __ARCH_HAS_4LEVEL_HACK
+	if (!pud_present(*pud)) {
+		mm_inc_nr_pmds(mm);
+		pud_populate(mm, pud, new);
+	} else	/* Another has populated it */
+		pmd_free(mm, new);
+#else
+	if (!pgd_present(*pud)) {
+		mm_inc_nr_pmds(mm);
+		pgd_populate(mm, pud, new);
+	} else /* Another has populated it */
+		pmd_free(mm, new);
+#endif /* __ARCH_HAS_4LEVEL_HACK */
+	spin_unlock(&mm->page_table_lock);
+	return 0;
+}
+#endif /* __PAGETABLE_PMD_FOLDED */
+
+static int __follow_pte(struct mm_struct *mm, unsigned long address,
+		pte_t **ptepp, spinlock_t **ptlp)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *ptep;
+
+	pgd = pgd_offset(mm, address);
+	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+		goto out;
+
+	pud = pud_offset(pgd, address);
+	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
+		goto out;
+
+	pmd = pmd_offset(pud, address);
+	VM_BUG_ON(pmd_trans_huge(*pmd));
+	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+		goto out;
+
+	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
+	if (pmd_huge(*pmd))
+		goto out;
+
+	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
+	if (!ptep)
+		goto out;
+	if (!pte_present(*ptep))
+		goto unlock;
+	*ptepp = ptep;
+	return 0;
+unlock:
+	pte_unmap_unlock(ptep, *ptlp);
+out:
+	return -EINVAL;
+}
+
+static inline int follow_pte(struct mm_struct *mm, unsigned long address,
+			     pte_t **ptepp, spinlock_t **ptlp)
+{
+	int res;
+
+	/* (void) is needed to make gcc happy */
+	(void) __cond_lock(*ptlp,
+			   !(res = __follow_pte(mm, address, ptepp, ptlp)));
+	return res;
+}
+
+/**
+ * follow_pfn - look up PFN at a user virtual address
+ * @vma: memory mapping
+ * @address: user virtual address
+ * @pfn: location to store found PFN
+ *
+ * Only IO mappings and raw PFN mappings are allowed.
+ *
+ * Returns zero and the pfn at @pfn on success, -ve otherwise.
+ */
+int follow_pfn(struct vm_area_struct *vma, unsigned long address,
+	unsigned long *pfn)
+{
+	int ret = -EINVAL;
+	spinlock_t *ptl;
+	pte_t *ptep;
+
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+		return ret;
+
+	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
+	if (ret)
+		return ret;
+	*pfn = pte_pfn(*ptep);
+	pte_unmap_unlock(ptep, ptl);
+	return 0;
+}
+EXPORT_SYMBOL(follow_pfn);
+
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+int follow_phys(struct vm_area_struct *vma,
+		unsigned long address, unsigned int flags,
+		unsigned long *prot, resource_size_t *phys)
+{
+	int ret = -EINVAL;
+	pte_t *ptep, pte;
+	spinlock_t *ptl;
+
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+		goto out;
+
+	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
+		goto out;
+	pte = *ptep;
+
+	if ((flags & FOLL_WRITE) && !pte_write(pte))
+		goto unlock;
+
+	*prot = pgprot_val(pte_pgprot(pte));
+	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
+
+	ret = 0;
+unlock:
+	pte_unmap_unlock(ptep, ptl);
+out:
+	return ret;
+}
+
+int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
+			void *buf, int len, int write)
+{
+	resource_size_t phys_addr;
+	unsigned long prot = 0;
+	void __iomem *maddr;
+	int offset = addr & (PAGE_SIZE-1);
+
+	if (follow_phys(vma, addr, write, &prot, &phys_addr))
+		return -EINVAL;
+
+	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
+	if (write)
+		memcpy_toio(maddr + offset, buf, len);
+	else
+		memcpy_fromio(buf, maddr + offset, len);
+	iounmap(maddr);
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(generic_access_phys);
+#endif
+
+/*
+ * Access another process' address space as given in mm.  If non-NULL, use the
+ * given task for page fault accounting.
+ */
+static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
+		unsigned long addr, void *buf, int len, int write)
+{
+	struct vm_area_struct *vma;
+	void *old_buf = buf;
+
+	down_read(&mm->mmap_sem);
+	/* ignore errors, just check how much was successfully transferred */
+	while (len) {
+		int bytes, ret, offset;
+		void *maddr;
+		struct page *page = NULL;
+
+		ret = get_user_pages(tsk, mm, addr, 1,
+				write, 1, &page, &vma);
+		if (ret <= 0) {
+#ifndef CONFIG_HAVE_IOREMAP_PROT
+			break;
+#else
+			/*
+			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
+			 * we can access using slightly different code.
+			 */
+			vma = find_vma(mm, addr);
+			if (!vma || vma->vm_start > addr)
+				break;
+			if (vma->vm_ops && vma->vm_ops->access)
+				ret = vma->vm_ops->access(vma, addr, buf,
+							  len, write);
+			if (ret <= 0)
+				break;
+			bytes = ret;
+#endif
+		} else {
+			bytes = len;
+			offset = addr & (PAGE_SIZE-1);
+			if (bytes > PAGE_SIZE-offset)
+				bytes = PAGE_SIZE-offset;
+
+			maddr = kmap(page);
+			if (write) {
+				copy_to_user_page(vma, page, addr,
+						  maddr + offset, buf, bytes);
+				set_page_dirty_lock(page);
+			} else {
+				copy_from_user_page(vma, page, addr,
+						    buf, maddr + offset, bytes);
+			}
+			kunmap(page);
+			page_cache_release(page);
+		}
+		len -= bytes;
+		buf += bytes;
+		addr += bytes;
+	}
+	up_read(&mm->mmap_sem);
+
+	return buf - old_buf;
+}
+
+/**
+ * access_remote_vm - access another process' address space
+ * @mm:		the mm_struct of the target address space
+ * @addr:	start address to access
+ * @buf:	source or destination buffer
+ * @len:	number of bytes to transfer
+ * @write:	whether the access is a write
+ *
+ * The caller must hold a reference on @mm.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+		void *buf, int len, int write)
+{
+	return __access_remote_vm(NULL, mm, addr, buf, len, write);
+}
+
+/*
+ * Access another process' address space.
+ * Source/target buffer must be kernel space,
+ * Do not walk the page table directly, use get_user_pages
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr,
+		void *buf, int len, int write)
+{
+	struct mm_struct *mm;
+	int ret;
+
+	mm = get_task_mm(tsk);
+	if (!mm)
+		return 0;
+
+	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
+	mmput(mm);
+
+	return ret;
+}
+
+/*
+ * Print the name of a VMA.
+ */
+void print_vma_addr(char *prefix, unsigned long ip)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+
+	/*
+	 * Do not print if we are in atomic
+	 * contexts (in exception stacks, etc.):
+	 */
+	if (preempt_count())
+		return;
+
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, ip);
+	if (vma && vma->vm_file) {
+		struct file *f = vma->vm_file;
+		char *buf = (char *)__get_free_page(GFP_KERNEL);
+		if (buf) {
+			char *p;
+
+			p = file_path(f, buf, PAGE_SIZE);
+			if (IS_ERR(p))
+				p = "?";
+			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
+					vma->vm_start,
+					vma->vm_end - vma->vm_start);
+			free_page((unsigned long)buf);
+		}
+	}
+	up_read(&mm->mmap_sem);
+}
+
+#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
+void __might_fault(const char *file, int line)
+{
+	/*
+	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
+	 * holding the mmap_sem, this is safe because kernel memory doesn't
+	 * get paged out, therefore we'll never actually fault, and the
+	 * below annotations will generate false positives.
+	 */
+	if (segment_eq(get_fs(), KERNEL_DS))
+		return;
+	if (pagefault_disabled())
+		return;
+	__might_sleep(file, line, 0);
+#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
+	if (current->mm)
+		might_lock_read(&current->mm->mmap_sem);
+#endif
+}
+EXPORT_SYMBOL(__might_fault);
+#endif
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
+static void clear_gigantic_page(struct page *page,
+				unsigned long addr,
+				unsigned int pages_per_huge_page)
+{
+	int i;
+	struct page *p = page;
+
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page;
+	     i++, p = mem_map_next(p, page, i)) {
+		cond_resched();
+		clear_user_highpage(p, addr + i * PAGE_SIZE);
+	}
+}
+void clear_huge_page(struct page *page,
+		     unsigned long addr, unsigned int pages_per_huge_page)
+{
+	int i;
+
+	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+		clear_gigantic_page(page, addr, pages_per_huge_page);
+		return;
+	}
+
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page; i++) {
+		cond_resched();
+		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
+	}
+}
+
+static void copy_user_gigantic_page(struct page *dst, struct page *src,
+				    unsigned long addr,
+				    struct vm_area_struct *vma,
+				    unsigned int pages_per_huge_page)
+{
+	int i;
+	struct page *dst_base = dst;
+	struct page *src_base = src;
+
+	for (i = 0; i < pages_per_huge_page; ) {
+		cond_resched();
+		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
+
+		i++;
+		dst = mem_map_next(dst, dst_base, i);
+		src = mem_map_next(src, src_base, i);
+	}
+}
+
+void copy_user_huge_page(struct page *dst, struct page *src,
+			 unsigned long addr, struct vm_area_struct *vma,
+			 unsigned int pages_per_huge_page)
+{
+	int i;
+
+	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+		copy_user_gigantic_page(dst, src, addr, vma,
+					pages_per_huge_page);
+		return;
+	}
+
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page; i++) {
+		cond_resched();
+		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
+	}
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
+
+#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
+
+static struct kmem_cache *page_ptl_cachep;
+
+void __init ptlock_cache_init(void)
+{
+	page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
+			SLAB_PANIC, NULL);
+}
+
+bool ptlock_alloc(struct page *page)
+{
+	spinlock_t *ptl;
+
+	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
+	if (!ptl)
+		return false;
+	page->ptl = ptl;
+	return true;
+}
+
+void ptlock_free(struct page *page)
+{
+	kmem_cache_free(page_ptl_cachep, page->ptl);
+}
+#endif
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
new file mode 100644
index 0000000..a18923e
--- /dev/null
+++ b/mm/memory_hotplug.c
@@ -0,0 +1,2077 @@
+/*
+ *  linux/mm/memory_hotplug.c
+ *
+ *  Copyright (C)
+ */
+
+#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/interrupt.h>
+#include <linux/pagemap.h>
+#include <linux/compiler.h>
+#include <linux/export.h>
+#include <linux/pagevec.h>
+#include <linux/writeback.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
+#include <linux/cpu.h>
+#include <linux/memory.h>
+#include <linux/memory_hotplug.h>
+#include <linux/highmem.h>
+#include <linux/vmalloc.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/migrate.h>
+#include <linux/page-isolation.h>
+#include <linux/pfn.h>
+#include <linux/suspend.h>
+#include <linux/mm_inline.h>
+#include <linux/firmware-map.h>
+#include <linux/stop_machine.h>
+#include <linux/hugetlb.h>
+#include <linux/memblock.h>
+#include <linux/bootmem.h>
+
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+
+/*
+ * online_page_callback contains pointer to current page onlining function.
+ * Initially it is generic_online_page(). If it is required it could be
+ * changed by calling set_online_page_callback() for callback registration
+ * and restore_online_page_callback() for generic callback restore.
+ */
+
+static void generic_online_page(struct page *page);
+
+static online_page_callback_t online_page_callback = generic_online_page;
+static DEFINE_MUTEX(online_page_callback_lock);
+
+/* The same as the cpu_hotplug lock, but for memory hotplug. */
+static struct {
+	struct task_struct *active_writer;
+	struct mutex lock; /* Synchronizes accesses to refcount, */
+	/*
+	 * Also blocks the new readers during
+	 * an ongoing mem hotplug operation.
+	 */
+	int refcount;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map dep_map;
+#endif
+} mem_hotplug = {
+	.active_writer = NULL,
+	.lock = __MUTEX_INITIALIZER(mem_hotplug.lock),
+	.refcount = 0,
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	.dep_map = {.name = "mem_hotplug.lock" },
+#endif
+};
+
+/* Lockdep annotations for get/put_online_mems() and mem_hotplug_begin/end() */
+#define memhp_lock_acquire_read() lock_map_acquire_read(&mem_hotplug.dep_map)
+#define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
+#define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
+
+void get_online_mems(void)
+{
+	might_sleep();
+	if (mem_hotplug.active_writer == current)
+		return;
+	memhp_lock_acquire_read();
+	mutex_lock(&mem_hotplug.lock);
+	mem_hotplug.refcount++;
+	mutex_unlock(&mem_hotplug.lock);
+
+}
+
+void put_online_mems(void)
+{
+	if (mem_hotplug.active_writer == current)
+		return;
+	mutex_lock(&mem_hotplug.lock);
+
+	if (WARN_ON(!mem_hotplug.refcount))
+		mem_hotplug.refcount++; /* try to fix things up */
+
+	if (!--mem_hotplug.refcount && unlikely(mem_hotplug.active_writer))
+		wake_up_process(mem_hotplug.active_writer);
+	mutex_unlock(&mem_hotplug.lock);
+	memhp_lock_release();
+
+}
+
+void mem_hotplug_begin(void)
+{
+	mem_hotplug.active_writer = current;
+
+	memhp_lock_acquire();
+	for (;;) {
+		mutex_lock(&mem_hotplug.lock);
+		if (likely(!mem_hotplug.refcount))
+			break;
+		__set_current_state(TASK_UNINTERRUPTIBLE);
+		mutex_unlock(&mem_hotplug.lock);
+		schedule();
+	}
+}
+
+void mem_hotplug_done(void)
+{
+	mem_hotplug.active_writer = NULL;
+	mutex_unlock(&mem_hotplug.lock);
+	memhp_lock_release();
+}
+
+/* add this memory to iomem resource */
+static struct resource *register_memory_resource(u64 start, u64 size)
+{
+	struct resource *res;
+	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+	BUG_ON(!res);
+
+	res->name = "System RAM";
+	res->start = start;
+	res->end = start + size - 1;
+	res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+	if (request_resource(&iomem_resource, res) < 0) {
+		pr_debug("System RAM resource %pR cannot be added\n", res);
+		kfree(res);
+		res = NULL;
+	}
+	return res;
+}
+
+static void release_memory_resource(struct resource *res)
+{
+	if (!res)
+		return;
+	release_resource(res);
+	kfree(res);
+	return;
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+void get_page_bootmem(unsigned long info,  struct page *page,
+		      unsigned long type)
+{
+	page->lru.next = (struct list_head *) type;
+	SetPagePrivate(page);
+	set_page_private(page, info);
+	atomic_inc(&page->_count);
+}
+
+void put_page_bootmem(struct page *page)
+{
+	unsigned long type;
+
+	type = (unsigned long) page->lru.next;
+	BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
+	       type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
+
+	if (atomic_dec_return(&page->_count) == 1) {
+		ClearPagePrivate(page);
+		set_page_private(page, 0);
+		INIT_LIST_HEAD(&page->lru);
+		free_reserved_page(page);
+	}
+}
+
+#ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+static void register_page_bootmem_info_section(unsigned long start_pfn)
+{
+	unsigned long *usemap, mapsize, section_nr, i;
+	struct mem_section *ms;
+	struct page *page, *memmap;
+
+	section_nr = pfn_to_section_nr(start_pfn);
+	ms = __nr_to_section(section_nr);
+
+	/* Get section's memmap address */
+	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+
+	/*
+	 * Get page for the memmap's phys address
+	 * XXX: need more consideration for sparse_vmemmap...
+	 */
+	page = virt_to_page(memmap);
+	mapsize = sizeof(struct page) * PAGES_PER_SECTION;
+	mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
+
+	/* remember memmap's page */
+	for (i = 0; i < mapsize; i++, page++)
+		get_page_bootmem(section_nr, page, SECTION_INFO);
+
+	usemap = __nr_to_section(section_nr)->pageblock_flags;
+	page = virt_to_page(usemap);
+
+	mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
+
+	for (i = 0; i < mapsize; i++, page++)
+		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
+
+}
+#else /* CONFIG_SPARSEMEM_VMEMMAP */
+static void register_page_bootmem_info_section(unsigned long start_pfn)
+{
+	unsigned long *usemap, mapsize, section_nr, i;
+	struct mem_section *ms;
+	struct page *page, *memmap;
+
+	if (!pfn_valid(start_pfn))
+		return;
+
+	section_nr = pfn_to_section_nr(start_pfn);
+	ms = __nr_to_section(section_nr);
+
+	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+
+	register_page_bootmem_memmap(section_nr, memmap, PAGES_PER_SECTION);
+
+	usemap = __nr_to_section(section_nr)->pageblock_flags;
+	page = virt_to_page(usemap);
+
+	mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
+
+	for (i = 0; i < mapsize; i++, page++)
+		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
+}
+#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+
+void register_page_bootmem_info_node(struct pglist_data *pgdat)
+{
+	unsigned long i, pfn, end_pfn, nr_pages;
+	int node = pgdat->node_id;
+	struct page *page;
+	struct zone *zone;
+
+	nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
+	page = virt_to_page(pgdat);
+
+	for (i = 0; i < nr_pages; i++, page++)
+		get_page_bootmem(node, page, NODE_INFO);
+
+	zone = &pgdat->node_zones[0];
+	for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
+		if (zone_is_initialized(zone)) {
+			nr_pages = zone->wait_table_hash_nr_entries
+				* sizeof(wait_queue_head_t);
+			nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
+			page = virt_to_page(zone->wait_table);
+
+			for (i = 0; i < nr_pages; i++, page++)
+				get_page_bootmem(node, page, NODE_INFO);
+		}
+	}
+
+	pfn = pgdat->node_start_pfn;
+	end_pfn = pgdat_end_pfn(pgdat);
+
+	/* register section info */
+	for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		/*
+		 * Some platforms can assign the same pfn to multiple nodes - on
+		 * node0 as well as nodeN.  To avoid registering a pfn against
+		 * multiple nodes we check that this pfn does not already
+		 * reside in some other nodes.
+		 */
+		if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
+			register_page_bootmem_info_section(pfn);
+	}
+}
+#endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
+
+static void __meminit grow_zone_span(struct zone *zone, unsigned long start_pfn,
+				     unsigned long end_pfn)
+{
+	unsigned long old_zone_end_pfn;
+
+	zone_span_writelock(zone);
+
+	old_zone_end_pfn = zone_end_pfn(zone);
+	if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
+		zone->zone_start_pfn = start_pfn;
+
+	zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
+				zone->zone_start_pfn;
+
+	zone_span_writeunlock(zone);
+}
+
+static void resize_zone(struct zone *zone, unsigned long start_pfn,
+		unsigned long end_pfn)
+{
+	zone_span_writelock(zone);
+
+	if (end_pfn - start_pfn) {
+		zone->zone_start_pfn = start_pfn;
+		zone->spanned_pages = end_pfn - start_pfn;
+	} else {
+		/*
+		 * make it consist as free_area_init_core(),
+		 * if spanned_pages = 0, then keep start_pfn = 0
+		 */
+		zone->zone_start_pfn = 0;
+		zone->spanned_pages = 0;
+	}
+
+	zone_span_writeunlock(zone);
+}
+
+static void fix_zone_id(struct zone *zone, unsigned long start_pfn,
+		unsigned long end_pfn)
+{
+	enum zone_type zid = zone_idx(zone);
+	int nid = zone->zone_pgdat->node_id;
+	unsigned long pfn;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn++)
+		set_page_links(pfn_to_page(pfn), zid, nid, pfn);
+}
+
+/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
+ * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
+static int __ref ensure_zone_is_initialized(struct zone *zone,
+			unsigned long start_pfn, unsigned long num_pages)
+{
+	if (!zone_is_initialized(zone))
+		return init_currently_empty_zone(zone, start_pfn, num_pages);
+
+	return 0;
+}
+
+static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
+		unsigned long start_pfn, unsigned long end_pfn)
+{
+	int ret;
+	unsigned long flags;
+	unsigned long z1_start_pfn;
+
+	ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
+	if (ret)
+		return ret;
+
+	pgdat_resize_lock(z1->zone_pgdat, &flags);
+
+	/* can't move pfns which are higher than @z2 */
+	if (end_pfn > zone_end_pfn(z2))
+		goto out_fail;
+	/* the move out part must be at the left most of @z2 */
+	if (start_pfn > z2->zone_start_pfn)
+		goto out_fail;
+	/* must included/overlap */
+	if (end_pfn <= z2->zone_start_pfn)
+		goto out_fail;
+
+	/* use start_pfn for z1's start_pfn if z1 is empty */
+	if (!zone_is_empty(z1))
+		z1_start_pfn = z1->zone_start_pfn;
+	else
+		z1_start_pfn = start_pfn;
+
+	resize_zone(z1, z1_start_pfn, end_pfn);
+	resize_zone(z2, end_pfn, zone_end_pfn(z2));
+
+	pgdat_resize_unlock(z1->zone_pgdat, &flags);
+
+	fix_zone_id(z1, start_pfn, end_pfn);
+
+	return 0;
+out_fail:
+	pgdat_resize_unlock(z1->zone_pgdat, &flags);
+	return -1;
+}
+
+static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
+		unsigned long start_pfn, unsigned long end_pfn)
+{
+	int ret;
+	unsigned long flags;
+	unsigned long z2_end_pfn;
+
+	ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
+	if (ret)
+		return ret;
+
+	pgdat_resize_lock(z1->zone_pgdat, &flags);
+
+	/* can't move pfns which are lower than @z1 */
+	if (z1->zone_start_pfn > start_pfn)
+		goto out_fail;
+	/* the move out part mast at the right most of @z1 */
+	if (zone_end_pfn(z1) >  end_pfn)
+		goto out_fail;
+	/* must included/overlap */
+	if (start_pfn >= zone_end_pfn(z1))
+		goto out_fail;
+
+	/* use end_pfn for z2's end_pfn if z2 is empty */
+	if (!zone_is_empty(z2))
+		z2_end_pfn = zone_end_pfn(z2);
+	else
+		z2_end_pfn = end_pfn;
+
+	resize_zone(z1, z1->zone_start_pfn, start_pfn);
+	resize_zone(z2, start_pfn, z2_end_pfn);
+
+	pgdat_resize_unlock(z1->zone_pgdat, &flags);
+
+	fix_zone_id(z2, start_pfn, end_pfn);
+
+	return 0;
+out_fail:
+	pgdat_resize_unlock(z1->zone_pgdat, &flags);
+	return -1;
+}
+
+static void __meminit grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
+				      unsigned long end_pfn)
+{
+	unsigned long old_pgdat_end_pfn = pgdat_end_pfn(pgdat);
+
+	if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
+		pgdat->node_start_pfn = start_pfn;
+
+	pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
+					pgdat->node_start_pfn;
+}
+
+static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	int nr_pages = PAGES_PER_SECTION;
+	int nid = pgdat->node_id;
+	int zone_type;
+	unsigned long flags, pfn;
+	int ret;
+
+	zone_type = zone - pgdat->node_zones;
+	ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
+	if (ret)
+		return ret;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
+	grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
+			phys_start_pfn + nr_pages);
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+	memmap_init_zone(nr_pages, nid, zone_type,
+			 phys_start_pfn, MEMMAP_HOTPLUG);
+
+	/* online_page_range is called later and expects pages reserved */
+	for (pfn = phys_start_pfn; pfn < phys_start_pfn + nr_pages; pfn++) {
+		if (!pfn_valid(pfn))
+			continue;
+
+		SetPageReserved(pfn_to_page(pfn));
+	}
+	return 0;
+}
+
+static int __meminit __add_section(int nid, struct zone *zone,
+					unsigned long phys_start_pfn)
+{
+	int ret;
+
+	if (pfn_valid(phys_start_pfn))
+		return -EEXIST;
+
+	ret = sparse_add_one_section(zone, phys_start_pfn);
+
+	if (ret < 0)
+		return ret;
+
+	ret = __add_zone(zone, phys_start_pfn);
+
+	if (ret < 0)
+		return ret;
+
+	return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
+}
+
+/*
+ * Reasonably generic function for adding memory.  It is
+ * expected that archs that support memory hotplug will
+ * call this function after deciding the zone to which to
+ * add the new pages.
+ */
+int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
+			unsigned long nr_pages)
+{
+	unsigned long i;
+	int err = 0;
+	int start_sec, end_sec;
+	/* during initialize mem_map, align hot-added range to section */
+	start_sec = pfn_to_section_nr(phys_start_pfn);
+	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
+
+	for (i = start_sec; i <= end_sec; i++) {
+		err = __add_section(nid, zone, section_nr_to_pfn(i));
+
+		/*
+		 * EEXIST is finally dealt with by ioresource collision
+		 * check. see add_memory() => register_memory_resource()
+		 * Warning will be printed if there is collision.
+		 */
+		if (err && (err != -EEXIST))
+			break;
+		err = 0;
+	}
+	vmemmap_populate_print_last();
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(__add_pages);
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/* find the smallest valid pfn in the range [start_pfn, end_pfn) */
+static int find_smallest_section_pfn(int nid, struct zone *zone,
+				     unsigned long start_pfn,
+				     unsigned long end_pfn)
+{
+	struct mem_section *ms;
+
+	for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) {
+		ms = __pfn_to_section(start_pfn);
+
+		if (unlikely(!valid_section(ms)))
+			continue;
+
+		if (unlikely(pfn_to_nid(start_pfn) != nid))
+			continue;
+
+		if (zone && zone != page_zone(pfn_to_page(start_pfn)))
+			continue;
+
+		return start_pfn;
+	}
+
+	return 0;
+}
+
+/* find the biggest valid pfn in the range [start_pfn, end_pfn). */
+static int find_biggest_section_pfn(int nid, struct zone *zone,
+				    unsigned long start_pfn,
+				    unsigned long end_pfn)
+{
+	struct mem_section *ms;
+	unsigned long pfn;
+
+	/* pfn is the end pfn of a memory section. */
+	pfn = end_pfn - 1;
+	for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) {
+		ms = __pfn_to_section(pfn);
+
+		if (unlikely(!valid_section(ms)))
+			continue;
+
+		if (unlikely(pfn_to_nid(pfn) != nid))
+			continue;
+
+		if (zone && zone != page_zone(pfn_to_page(pfn)))
+			continue;
+
+		return pfn;
+	}
+
+	return 0;
+}
+
+static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
+			     unsigned long end_pfn)
+{
+	unsigned long zone_start_pfn = zone->zone_start_pfn;
+	unsigned long z = zone_end_pfn(zone); /* zone_end_pfn namespace clash */
+	unsigned long zone_end_pfn = z;
+	unsigned long pfn;
+	struct mem_section *ms;
+	int nid = zone_to_nid(zone);
+
+	zone_span_writelock(zone);
+	if (zone_start_pfn == start_pfn) {
+		/*
+		 * If the section is smallest section in the zone, it need
+		 * shrink zone->zone_start_pfn and zone->zone_spanned_pages.
+		 * In this case, we find second smallest valid mem_section
+		 * for shrinking zone.
+		 */
+		pfn = find_smallest_section_pfn(nid, zone, end_pfn,
+						zone_end_pfn);
+		if (pfn) {
+			zone->zone_start_pfn = pfn;
+			zone->spanned_pages = zone_end_pfn - pfn;
+		}
+	} else if (zone_end_pfn == end_pfn) {
+		/*
+		 * If the section is biggest section in the zone, it need
+		 * shrink zone->spanned_pages.
+		 * In this case, we find second biggest valid mem_section for
+		 * shrinking zone.
+		 */
+		pfn = find_biggest_section_pfn(nid, zone, zone_start_pfn,
+					       start_pfn);
+		if (pfn)
+			zone->spanned_pages = pfn - zone_start_pfn + 1;
+	}
+
+	/*
+	 * The section is not biggest or smallest mem_section in the zone, it
+	 * only creates a hole in the zone. So in this case, we need not
+	 * change the zone. But perhaps, the zone has only hole data. Thus
+	 * it check the zone has only hole or not.
+	 */
+	pfn = zone_start_pfn;
+	for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
+		ms = __pfn_to_section(pfn);
+
+		if (unlikely(!valid_section(ms)))
+			continue;
+
+		if (page_zone(pfn_to_page(pfn)) != zone)
+			continue;
+
+		 /* If the section is current section, it continues the loop */
+		if (start_pfn == pfn)
+			continue;
+
+		/* If we find valid section, we have nothing to do */
+		zone_span_writeunlock(zone);
+		return;
+	}
+
+	/* The zone has no valid section */
+	zone->zone_start_pfn = 0;
+	zone->spanned_pages = 0;
+	zone_span_writeunlock(zone);
+}
+
+static void shrink_pgdat_span(struct pglist_data *pgdat,
+			      unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pgdat_start_pfn = pgdat->node_start_pfn;
+	unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
+	unsigned long pgdat_end_pfn = p;
+	unsigned long pfn;
+	struct mem_section *ms;
+	int nid = pgdat->node_id;
+
+	if (pgdat_start_pfn == start_pfn) {
+		/*
+		 * If the section is smallest section in the pgdat, it need
+		 * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages.
+		 * In this case, we find second smallest valid mem_section
+		 * for shrinking zone.
+		 */
+		pfn = find_smallest_section_pfn(nid, NULL, end_pfn,
+						pgdat_end_pfn);
+		if (pfn) {
+			pgdat->node_start_pfn = pfn;
+			pgdat->node_spanned_pages = pgdat_end_pfn - pfn;
+		}
+	} else if (pgdat_end_pfn == end_pfn) {
+		/*
+		 * If the section is biggest section in the pgdat, it need
+		 * shrink pgdat->node_spanned_pages.
+		 * In this case, we find second biggest valid mem_section for
+		 * shrinking zone.
+		 */
+		pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn,
+					       start_pfn);
+		if (pfn)
+			pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1;
+	}
+
+	/*
+	 * If the section is not biggest or smallest mem_section in the pgdat,
+	 * it only creates a hole in the pgdat. So in this case, we need not
+	 * change the pgdat.
+	 * But perhaps, the pgdat has only hole data. Thus it check the pgdat
+	 * has only hole or not.
+	 */
+	pfn = pgdat_start_pfn;
+	for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SECTION) {
+		ms = __pfn_to_section(pfn);
+
+		if (unlikely(!valid_section(ms)))
+			continue;
+
+		if (pfn_to_nid(pfn) != nid)
+			continue;
+
+		 /* If the section is current section, it continues the loop */
+		if (start_pfn == pfn)
+			continue;
+
+		/* If we find valid section, we have nothing to do */
+		return;
+	}
+
+	/* The pgdat has no valid section */
+	pgdat->node_start_pfn = 0;
+	pgdat->node_spanned_pages = 0;
+}
+
+static void __remove_zone(struct zone *zone, unsigned long start_pfn)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	int nr_pages = PAGES_PER_SECTION;
+	int zone_type;
+	unsigned long flags;
+
+	zone_type = zone - pgdat->node_zones;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
+	shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+}
+
+static int __remove_section(struct zone *zone, struct mem_section *ms)
+{
+	unsigned long start_pfn;
+	int scn_nr;
+	int ret = -EINVAL;
+
+	if (!valid_section(ms))
+		return ret;
+
+	ret = unregister_memory_section(ms);
+	if (ret)
+		return ret;
+
+	scn_nr = __section_nr(ms);
+	start_pfn = section_nr_to_pfn(scn_nr);
+	__remove_zone(zone, start_pfn);
+
+	sparse_remove_one_section(zone, ms);
+	return 0;
+}
+
+/**
+ * __remove_pages() - remove sections of pages from a zone
+ * @zone: zone from which pages need to be removed
+ * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
+ * @nr_pages: number of pages to remove (must be multiple of section size)
+ *
+ * Generic helper function to remove section mappings and sysfs entries
+ * for the section of the memory we are removing. Caller needs to make
+ * sure that pages are marked reserved and zones are adjust properly by
+ * calling offline_pages().
+ */
+int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
+		 unsigned long nr_pages)
+{
+	unsigned long i;
+	int sections_to_remove;
+	resource_size_t start, size;
+	int ret = 0;
+
+	/*
+	 * We can only remove entire sections
+	 */
+	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
+	BUG_ON(nr_pages % PAGES_PER_SECTION);
+
+	start = phys_start_pfn << PAGE_SHIFT;
+	size = nr_pages * PAGE_SIZE;
+
+	/* in the ZONE_DEVICE case device driver owns the memory region */
+	if (!is_dev_zone(zone))
+		ret = release_mem_region_adjustable(&iomem_resource, start, size);
+	if (ret) {
+		resource_size_t endres = start + size - 1;
+
+		pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
+				&start, &endres, ret);
+	}
+
+	sections_to_remove = nr_pages / PAGES_PER_SECTION;
+	for (i = 0; i < sections_to_remove; i++) {
+		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
+		ret = __remove_section(zone, __pfn_to_section(pfn));
+		if (ret)
+			break;
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__remove_pages);
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+int set_online_page_callback(online_page_callback_t callback)
+{
+	int rc = -EINVAL;
+
+	get_online_mems();
+	mutex_lock(&online_page_callback_lock);
+
+	if (online_page_callback == generic_online_page) {
+		online_page_callback = callback;
+		rc = 0;
+	}
+
+	mutex_unlock(&online_page_callback_lock);
+	put_online_mems();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(set_online_page_callback);
+
+int restore_online_page_callback(online_page_callback_t callback)
+{
+	int rc = -EINVAL;
+
+	get_online_mems();
+	mutex_lock(&online_page_callback_lock);
+
+	if (online_page_callback == callback) {
+		online_page_callback = generic_online_page;
+		rc = 0;
+	}
+
+	mutex_unlock(&online_page_callback_lock);
+	put_online_mems();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(restore_online_page_callback);
+
+void __online_page_set_limits(struct page *page)
+{
+}
+EXPORT_SYMBOL_GPL(__online_page_set_limits);
+
+void __online_page_increment_counters(struct page *page)
+{
+	adjust_managed_page_count(page, 1);
+}
+EXPORT_SYMBOL_GPL(__online_page_increment_counters);
+
+void __online_page_free(struct page *page)
+{
+	__free_reserved_page(page);
+}
+EXPORT_SYMBOL_GPL(__online_page_free);
+
+static void generic_online_page(struct page *page)
+{
+	__online_page_set_limits(page);
+	__online_page_increment_counters(page);
+	__online_page_free(page);
+}
+
+static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
+			void *arg)
+{
+	unsigned long i;
+	unsigned long onlined_pages = *(unsigned long *)arg;
+	struct page *page;
+	if (PageReserved(pfn_to_page(start_pfn)))
+		for (i = 0; i < nr_pages; i++) {
+			page = pfn_to_page(start_pfn + i);
+			(*online_page_callback)(page);
+			onlined_pages++;
+		}
+	*(unsigned long *)arg = onlined_pages;
+	return 0;
+}
+
+#ifdef CONFIG_MOVABLE_NODE
+/*
+ * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
+ * normal memory.
+ */
+static bool can_online_high_movable(struct zone *zone)
+{
+	return true;
+}
+#else /* CONFIG_MOVABLE_NODE */
+/* ensure every online node has NORMAL memory */
+static bool can_online_high_movable(struct zone *zone)
+{
+	return node_state(zone_to_nid(zone), N_NORMAL_MEMORY);
+}
+#endif /* CONFIG_MOVABLE_NODE */
+
+/* check which state of node_states will be changed when online memory */
+static void node_states_check_changes_online(unsigned long nr_pages,
+	struct zone *zone, struct memory_notify *arg)
+{
+	int nid = zone_to_nid(zone);
+	enum zone_type zone_last = ZONE_NORMAL;
+
+	/*
+	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_NORMAL,
+	 * set zone_last to ZONE_NORMAL.
+	 *
+	 * If we don't have HIGHMEM nor movable node,
+	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
+	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
+	 */
+	if (N_MEMORY == N_NORMAL_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	/*
+	 * if the memory to be online is in a zone of 0...zone_last, and
+	 * the zones of 0...zone_last don't have memory before online, we will
+	 * need to set the node to node_states[N_NORMAL_MEMORY] after
+	 * the memory is online.
+	 */
+	if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
+		arg->status_change_nid_normal = nid;
+	else
+		arg->status_change_nid_normal = -1;
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * If we have movable node, node_states[N_HIGH_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
+	 * set zone_last to ZONE_HIGHMEM.
+	 *
+	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_MOVABLE,
+	 * set zone_last to ZONE_MOVABLE.
+	 */
+	zone_last = ZONE_HIGHMEM;
+	if (N_MEMORY == N_HIGH_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY))
+		arg->status_change_nid_high = nid;
+	else
+		arg->status_change_nid_high = -1;
+#else
+	arg->status_change_nid_high = arg->status_change_nid_normal;
+#endif
+
+	/*
+	 * if the node don't have memory befor online, we will need to
+	 * set the node to node_states[N_MEMORY] after the memory
+	 * is online.
+	 */
+	if (!node_state(nid, N_MEMORY))
+		arg->status_change_nid = nid;
+	else
+		arg->status_change_nid = -1;
+}
+
+static void node_states_set_node(int node, struct memory_notify *arg)
+{
+	if (arg->status_change_nid_normal >= 0)
+		node_set_state(node, N_NORMAL_MEMORY);
+
+	if (arg->status_change_nid_high >= 0)
+		node_set_state(node, N_HIGH_MEMORY);
+
+	node_set_state(node, N_MEMORY);
+}
+
+
+/* Must be protected by mem_hotplug_begin() */
+int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
+{
+	unsigned long flags;
+	unsigned long onlined_pages = 0;
+	struct zone *zone;
+	int need_zonelists_rebuild = 0;
+	int nid;
+	int ret;
+	struct memory_notify arg;
+
+	/*
+	 * This doesn't need a lock to do pfn_to_page().
+	 * The section can't be removed here because of the
+	 * memory_block->state_mutex.
+	 */
+	zone = page_zone(pfn_to_page(pfn));
+
+	if ((zone_idx(zone) > ZONE_NORMAL ||
+	    online_type == MMOP_ONLINE_MOVABLE) &&
+	    !can_online_high_movable(zone))
+		return -EINVAL;
+
+	if (online_type == MMOP_ONLINE_KERNEL &&
+	    zone_idx(zone) == ZONE_MOVABLE) {
+		if (move_pfn_range_left(zone - 1, zone, pfn, pfn + nr_pages))
+			return -EINVAL;
+	}
+	if (online_type == MMOP_ONLINE_MOVABLE &&
+	    zone_idx(zone) == ZONE_MOVABLE - 1) {
+		if (move_pfn_range_right(zone, zone + 1, pfn, pfn + nr_pages))
+			return -EINVAL;
+	}
+
+	/* Previous code may changed the zone of the pfn range */
+	zone = page_zone(pfn_to_page(pfn));
+
+	arg.start_pfn = pfn;
+	arg.nr_pages = nr_pages;
+	node_states_check_changes_online(nr_pages, zone, &arg);
+
+	nid = pfn_to_nid(pfn);
+
+	ret = memory_notify(MEM_GOING_ONLINE, &arg);
+	ret = notifier_to_errno(ret);
+	if (ret) {
+		memory_notify(MEM_CANCEL_ONLINE, &arg);
+		return ret;
+	}
+	/*
+	 * If this zone is not populated, then it is not in zonelist.
+	 * This means the page allocator ignores this zone.
+	 * So, zonelist must be updated after online.
+	 */
+	mutex_lock(&zonelists_mutex);
+	if (!populated_zone(zone)) {
+		need_zonelists_rebuild = 1;
+		build_all_zonelists(NULL, zone);
+	}
+
+	ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
+		online_pages_range);
+	if (ret) {
+		if (need_zonelists_rebuild)
+			zone_pcp_reset(zone);
+		mutex_unlock(&zonelists_mutex);
+		printk(KERN_DEBUG "online_pages [mem %#010llx-%#010llx] failed\n",
+		       (unsigned long long) pfn << PAGE_SHIFT,
+		       (((unsigned long long) pfn + nr_pages)
+			    << PAGE_SHIFT) - 1);
+		memory_notify(MEM_CANCEL_ONLINE, &arg);
+		return ret;
+	}
+
+	zone->present_pages += onlined_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	zone->zone_pgdat->node_present_pages += onlined_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
+	if (onlined_pages) {
+		node_states_set_node(zone_to_nid(zone), &arg);
+		if (need_zonelists_rebuild)
+			build_all_zonelists(NULL, NULL);
+		else
+			zone_pcp_update(zone);
+	}
+
+	mutex_unlock(&zonelists_mutex);
+
+	init_per_zone_wmark_min();
+
+	if (onlined_pages)
+		kswapd_run(zone_to_nid(zone));
+
+	vm_total_pages = nr_free_pagecache_pages();
+
+	writeback_set_ratelimit();
+
+	if (onlined_pages)
+		memory_notify(MEM_ONLINE, &arg);
+	return 0;
+}
+#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
+
+static void reset_node_present_pages(pg_data_t *pgdat)
+{
+	struct zone *z;
+
+	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
+		z->present_pages = 0;
+
+	pgdat->node_present_pages = 0;
+}
+
+/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
+static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
+{
+	struct pglist_data *pgdat;
+	unsigned long zones_size[MAX_NR_ZONES] = {0};
+	unsigned long zholes_size[MAX_NR_ZONES] = {0};
+	unsigned long start_pfn = PFN_DOWN(start);
+
+	pgdat = NODE_DATA(nid);
+	if (!pgdat) {
+		pgdat = arch_alloc_nodedata(nid);
+		if (!pgdat)
+			return NULL;
+
+		arch_refresh_nodedata(nid, pgdat);
+	} else {
+		/* Reset the nr_zones and classzone_idx to 0 before reuse */
+		pgdat->nr_zones = 0;
+		pgdat->classzone_idx = 0;
+	}
+
+	/* we can use NODE_DATA(nid) from here */
+
+	/* init node's zones as empty zones, we don't have any present pages.*/
+	free_area_init_node(nid, zones_size, start_pfn, zholes_size);
+
+	/*
+	 * The node we allocated has no zone fallback lists. For avoiding
+	 * to access not-initialized zonelist, build here.
+	 */
+	mutex_lock(&zonelists_mutex);
+	build_all_zonelists(pgdat, NULL);
+	mutex_unlock(&zonelists_mutex);
+
+	/*
+	 * zone->managed_pages is set to an approximate value in
+	 * free_area_init_core(), which will cause
+	 * /sys/device/system/node/nodeX/meminfo has wrong data.
+	 * So reset it to 0 before any memory is onlined.
+	 */
+	reset_node_managed_pages(pgdat);
+
+	/*
+	 * When memory is hot-added, all the memory is in offline state. So
+	 * clear all zones' present_pages because they will be updated in
+	 * online_pages() and offline_pages().
+	 */
+	reset_node_present_pages(pgdat);
+
+	return pgdat;
+}
+
+static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
+{
+	arch_refresh_nodedata(nid, NULL);
+	arch_free_nodedata(pgdat);
+	return;
+}
+
+
+/**
+ * try_online_node - online a node if offlined
+ *
+ * called by cpu_up() to online a node without onlined memory.
+ */
+int try_online_node(int nid)
+{
+	pg_data_t	*pgdat;
+	int	ret;
+
+	if (node_online(nid))
+		return 0;
+
+	mem_hotplug_begin();
+	pgdat = hotadd_new_pgdat(nid, 0);
+	if (!pgdat) {
+		pr_err("Cannot online node %d due to NULL pgdat\n", nid);
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_set_online(nid);
+	ret = register_one_node(nid);
+	BUG_ON(ret);
+
+	if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
+		mutex_lock(&zonelists_mutex);
+		build_all_zonelists(NULL, NULL);
+		mutex_unlock(&zonelists_mutex);
+	}
+
+out:
+	mem_hotplug_done();
+	return ret;
+}
+
+static int check_hotplug_memory_range(u64 start, u64 size)
+{
+	u64 start_pfn = PFN_DOWN(start);
+	u64 nr_pages = size >> PAGE_SHIFT;
+
+	/* Memory range must be aligned with section */
+	if ((start_pfn & ~PAGE_SECTION_MASK) ||
+	    (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
+		pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
+				(unsigned long long)start,
+				(unsigned long long)size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * If movable zone has already been setup, newly added memory should be check.
+ * If its address is higher than movable zone, it should be added as movable.
+ * Without this check, movable zone may overlap with other zone.
+ */
+static int should_add_memory_movable(int nid, u64 start, u64 size)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	pg_data_t *pgdat = NODE_DATA(nid);
+	struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
+
+	if (zone_is_empty(movable_zone))
+		return 0;
+
+	if (movable_zone->zone_start_pfn <= start_pfn)
+		return 1;
+
+	return 0;
+}
+
+int zone_for_memory(int nid, u64 start, u64 size, int zone_default,
+		bool for_device)
+{
+#ifdef CONFIG_ZONE_DEVICE
+	if (for_device)
+		return ZONE_DEVICE;
+#endif
+	if (should_add_memory_movable(nid, start, size))
+		return ZONE_MOVABLE;
+
+	return zone_default;
+}
+
+/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
+int __ref add_memory_resource(int nid, struct resource *res)
+{
+	u64 start, size;
+	pg_data_t *pgdat = NULL;
+	bool new_pgdat;
+	bool new_node;
+	int ret;
+
+	start = res->start;
+	size = resource_size(res);
+
+	ret = check_hotplug_memory_range(start, size);
+	if (ret)
+		return ret;
+
+	{	/* Stupid hack to suppress address-never-null warning */
+		void *p = NODE_DATA(nid);
+		new_pgdat = !p;
+	}
+
+	mem_hotplug_begin();
+
+	/*
+	 * Add new range to memblock so that when hotadd_new_pgdat() is called
+	 * to allocate new pgdat, get_pfn_range_for_nid() will be able to find
+	 * this new range and calculate total pages correctly.  The range will
+	 * be removed at hot-remove time.
+	 */
+	memblock_add_node(start, size, nid);
+
+	new_node = !node_online(nid);
+	if (new_node) {
+		pgdat = hotadd_new_pgdat(nid, start);
+		ret = -ENOMEM;
+		if (!pgdat)
+			goto error;
+	}
+
+	/* call arch's memory hotadd */
+	ret = arch_add_memory(nid, start, size, false);
+
+	if (ret < 0)
+		goto error;
+
+	/* we online node here. we can't roll back from here. */
+	node_set_online(nid);
+
+	if (new_node) {
+		ret = register_one_node(nid);
+		/*
+		 * If sysfs file of new node can't create, cpu on the node
+		 * can't be hot-added. There is no rollback way now.
+		 * So, check by BUG_ON() to catch it reluctantly..
+		 */
+		BUG_ON(ret);
+	}
+
+	/* create new memmap entry */
+	firmware_map_add_hotplug(start, start + size, "System RAM");
+
+	goto out;
+
+error:
+	/* rollback pgdat allocation and others */
+	if (new_pgdat)
+		rollback_node_hotadd(nid, pgdat);
+	memblock_remove(start, size);
+
+out:
+	mem_hotplug_done();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(add_memory_resource);
+
+int __ref add_memory(int nid, u64 start, u64 size)
+{
+	struct resource *res;
+	int ret;
+
+	res = register_memory_resource(start, size);
+	if (!res)
+		return -EEXIST;
+
+	ret = add_memory_resource(nid, res);
+	if (ret < 0)
+		release_memory_resource(res);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(add_memory);
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
+ * set and the size of the free page is given by page_order(). Using this,
+ * the function determines if the pageblock contains only free pages.
+ * Due to buddy contraints, a free page at least the size of a pageblock will
+ * be located at the start of the pageblock
+ */
+static inline int pageblock_free(struct page *page)
+{
+	return PageBuddy(page) && page_order(page) >= pageblock_order;
+}
+
+/* Return the start of the next active pageblock after a given page */
+static struct page *next_active_pageblock(struct page *page)
+{
+	/* Ensure the starting page is pageblock-aligned */
+	BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
+
+	/* If the entire pageblock is free, move to the end of free page */
+	if (pageblock_free(page)) {
+		int order;
+		/* be careful. we don't have locks, page_order can be changed.*/
+		order = page_order(page);
+		if ((order < MAX_ORDER) && (order >= pageblock_order))
+			return page + (1 << order);
+	}
+
+	return page + pageblock_nr_pages;
+}
+
+/* Checks if this range of memory is likely to be hot-removable. */
+int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
+{
+	struct page *page = pfn_to_page(start_pfn);
+	struct page *end_page = page + nr_pages;
+
+	/* Check the starting page of each pageblock within the range */
+	for (; page < end_page; page = next_active_pageblock(page)) {
+		if (!is_pageblock_removable_nolock(page))
+			return 0;
+		cond_resched();
+	}
+
+	/* All pageblocks in the memory block are likely to be hot-removable */
+	return 1;
+}
+
+/*
+ * Confirm all pages in a range [start, end) belong to the same zone.
+ * When true, return its valid [start, end).
+ */
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
+			 unsigned long *valid_start, unsigned long *valid_end)
+{
+	unsigned long pfn, sec_end_pfn;
+	unsigned long start, end;
+	struct zone *zone = NULL;
+	struct page *page;
+	int i;
+	for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
+	     pfn < end_pfn;
+	     pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
+		/* Make sure the memory section is present first */
+		if (!present_section_nr(pfn_to_section_nr(pfn)))
+			continue;
+		for (; pfn < sec_end_pfn && pfn < end_pfn;
+		     pfn += MAX_ORDER_NR_PAGES) {
+			i = 0;
+			/* This is just a CONFIG_HOLES_IN_ZONE check.*/
+			while ((i < MAX_ORDER_NR_PAGES) &&
+				!pfn_valid_within(pfn + i))
+				i++;
+			if (i == MAX_ORDER_NR_PAGES)
+				continue;
+			page = pfn_to_page(pfn + i);
+			if (zone && page_zone(page) != zone)
+				return 0;
+			if (!zone)
+				start = pfn + i;
+			zone = page_zone(page);
+			end = pfn + MAX_ORDER_NR_PAGES;
+		}
+	}
+
+	if (zone) {
+		*valid_start = start;
+		*valid_end = end;
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+/*
+ * Scan pfn range [start,end) to find movable/migratable pages (LRU pages
+ * and hugepages). We scan pfn because it's much easier than scanning over
+ * linked list. This function returns the pfn of the first found movable
+ * page if it's found, otherwise 0.
+ */
+static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
+{
+	unsigned long pfn;
+	struct page *page;
+	for (pfn = start; pfn < end; pfn++) {
+		if (pfn_valid(pfn)) {
+			page = pfn_to_page(pfn);
+			if (PageLRU(page))
+				return pfn;
+			if (PageHuge(page)) {
+				if (page_huge_active(page))
+					return pfn;
+				else
+					pfn = round_up(pfn + 1,
+						1 << compound_order(page)) - 1;
+			}
+		}
+	}
+	return 0;
+}
+
+#define NR_OFFLINE_AT_ONCE_PAGES	(256)
+static int
+do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn;
+	struct page *page;
+	int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
+	int not_managed = 0;
+	int ret = 0;
+	LIST_HEAD(source);
+
+	for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
+		if (!pfn_valid(pfn))
+			continue;
+		page = pfn_to_page(pfn);
+
+		if (PageHuge(page)) {
+			struct page *head = compound_head(page);
+			pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
+			if (compound_order(head) > PFN_SECTION_SHIFT) {
+				ret = -EBUSY;
+				break;
+			}
+			if (isolate_huge_page(page, &source))
+				move_pages -= 1 << compound_order(head);
+			continue;
+		}
+
+		if (!get_page_unless_zero(page))
+			continue;
+		/*
+		 * We can skip free pages. And we can only deal with pages on
+		 * LRU.
+		 */
+		ret = isolate_lru_page(page);
+		if (!ret) { /* Success */
+			put_page(page);
+			list_add_tail(&page->lru, &source);
+			move_pages--;
+			inc_zone_page_state(page, NR_ISOLATED_ANON +
+					    page_is_file_cache(page));
+
+		} else {
+#ifdef CONFIG_DEBUG_VM
+			printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
+			       pfn);
+			dump_page(page, "failed to remove from LRU");
+#endif
+			put_page(page);
+			/* Because we don't have big zone->lock. we should
+			   check this again here. */
+			if (page_count(page)) {
+				not_managed++;
+				ret = -EBUSY;
+				break;
+			}
+		}
+	}
+	if (!list_empty(&source)) {
+		if (not_managed) {
+			putback_movable_pages(&source);
+			goto out;
+		}
+
+		/*
+		 * alloc_migrate_target should be improooooved!!
+		 * migrate_pages returns # of failed pages.
+		 */
+		ret = migrate_pages(&source, alloc_migrate_target, NULL, 0,
+					MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
+		if (ret)
+			putback_movable_pages(&source);
+	}
+out:
+	return ret;
+}
+
+/*
+ * remove from free_area[] and mark all as Reserved.
+ */
+static int
+offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
+			void *data)
+{
+	__offline_isolated_pages(start, start + nr_pages);
+	return 0;
+}
+
+static void
+offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
+{
+	walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
+				offline_isolated_pages_cb);
+}
+
+/*
+ * Check all pages in range, recoreded as memory resource, are isolated.
+ */
+static int
+check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
+			void *data)
+{
+	int ret;
+	long offlined = *(long *)data;
+	ret = test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
+	offlined = nr_pages;
+	if (!ret)
+		*(long *)data += offlined;
+	return ret;
+}
+
+static long
+check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
+{
+	long offlined = 0;
+	int ret;
+
+	ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
+			check_pages_isolated_cb);
+	if (ret < 0)
+		offlined = (long)ret;
+	return offlined;
+}
+
+#ifdef CONFIG_MOVABLE_NODE
+/*
+ * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
+ * normal memory.
+ */
+static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
+{
+	return true;
+}
+#else /* CONFIG_MOVABLE_NODE */
+/* ensure the node has NORMAL memory if it is still online */
+static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	unsigned long present_pages = 0;
+	enum zone_type zt;
+
+	for (zt = 0; zt <= ZONE_NORMAL; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+
+	if (present_pages > nr_pages)
+		return true;
+
+	present_pages = 0;
+	for (; zt <= ZONE_MOVABLE; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+
+	/*
+	 * we can't offline the last normal memory until all
+	 * higher memory is offlined.
+	 */
+	return present_pages == 0;
+}
+#endif /* CONFIG_MOVABLE_NODE */
+
+static int __init cmdline_parse_movable_node(char *p)
+{
+#ifdef CONFIG_MOVABLE_NODE
+	/*
+	 * Memory used by the kernel cannot be hot-removed because Linux
+	 * cannot migrate the kernel pages. When memory hotplug is
+	 * enabled, we should prevent memblock from allocating memory
+	 * for the kernel.
+	 *
+	 * ACPI SRAT records all hotpluggable memory ranges. But before
+	 * SRAT is parsed, we don't know about it.
+	 *
+	 * The kernel image is loaded into memory at very early time. We
+	 * cannot prevent this anyway. So on NUMA system, we set any
+	 * node the kernel resides in as un-hotpluggable.
+	 *
+	 * Since on modern servers, one node could have double-digit
+	 * gigabytes memory, we can assume the memory around the kernel
+	 * image is also un-hotpluggable. So before SRAT is parsed, just
+	 * allocate memory near the kernel image to try the best to keep
+	 * the kernel away from hotpluggable memory.
+	 */
+	memblock_set_bottom_up(true);
+	movable_node_enabled = true;
+#else
+	pr_warn("movable_node option not supported\n");
+#endif
+	return 0;
+}
+early_param("movable_node", cmdline_parse_movable_node);
+
+/* check which state of node_states will be changed when offline memory */
+static void node_states_check_changes_offline(unsigned long nr_pages,
+		struct zone *zone, struct memory_notify *arg)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	unsigned long present_pages = 0;
+	enum zone_type zt, zone_last = ZONE_NORMAL;
+
+	/*
+	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_NORMAL,
+	 * set zone_last to ZONE_NORMAL.
+	 *
+	 * If we don't have HIGHMEM nor movable node,
+	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
+	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
+	 */
+	if (N_MEMORY == N_NORMAL_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	/*
+	 * check whether node_states[N_NORMAL_MEMORY] will be changed.
+	 * If the memory to be offline is in a zone of 0...zone_last,
+	 * and it is the last present memory, 0...zone_last will
+	 * become empty after offline , thus we can determind we will
+	 * need to clear the node from node_states[N_NORMAL_MEMORY].
+	 */
+	for (zt = 0; zt <= zone_last; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
+		arg->status_change_nid_normal = zone_to_nid(zone);
+	else
+		arg->status_change_nid_normal = -1;
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * If we have movable node, node_states[N_HIGH_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
+	 * set zone_last to ZONE_HIGHMEM.
+	 *
+	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_MOVABLE,
+	 * set zone_last to ZONE_MOVABLE.
+	 */
+	zone_last = ZONE_HIGHMEM;
+	if (N_MEMORY == N_HIGH_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	for (; zt <= zone_last; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
+		arg->status_change_nid_high = zone_to_nid(zone);
+	else
+		arg->status_change_nid_high = -1;
+#else
+	arg->status_change_nid_high = arg->status_change_nid_normal;
+#endif
+
+	/*
+	 * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE
+	 */
+	zone_last = ZONE_MOVABLE;
+
+	/*
+	 * check whether node_states[N_HIGH_MEMORY] will be changed
+	 * If we try to offline the last present @nr_pages from the node,
+	 * we can determind we will need to clear the node from
+	 * node_states[N_HIGH_MEMORY].
+	 */
+	for (; zt <= zone_last; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (nr_pages >= present_pages)
+		arg->status_change_nid = zone_to_nid(zone);
+	else
+		arg->status_change_nid = -1;
+}
+
+static void node_states_clear_node(int node, struct memory_notify *arg)
+{
+	if (arg->status_change_nid_normal >= 0)
+		node_clear_state(node, N_NORMAL_MEMORY);
+
+	if ((N_MEMORY != N_NORMAL_MEMORY) &&
+	    (arg->status_change_nid_high >= 0))
+		node_clear_state(node, N_HIGH_MEMORY);
+
+	if ((N_MEMORY != N_HIGH_MEMORY) &&
+	    (arg->status_change_nid >= 0))
+		node_clear_state(node, N_MEMORY);
+}
+
+static int __ref __offline_pages(unsigned long start_pfn,
+		  unsigned long end_pfn, unsigned long timeout)
+{
+	unsigned long pfn, nr_pages, expire;
+	long offlined_pages;
+	int ret, drain, retry_max, node;
+	unsigned long flags;
+	unsigned long valid_start, valid_end;
+	struct zone *zone;
+	struct memory_notify arg;
+
+	/* at least, alignment against pageblock is necessary */
+	if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
+		return -EINVAL;
+	if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
+		return -EINVAL;
+	/* This makes hotplug much easier...and readable.
+	   we assume this for now. .*/
+	if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
+		return -EINVAL;
+
+	zone = page_zone(pfn_to_page(valid_start));
+	node = zone_to_nid(zone);
+	nr_pages = end_pfn - start_pfn;
+
+	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
+		return -EINVAL;
+
+	/* set above range as isolated */
+	ret = start_isolate_page_range(start_pfn, end_pfn,
+				       MIGRATE_MOVABLE, true);
+	if (ret)
+		return ret;
+
+	arg.start_pfn = start_pfn;
+	arg.nr_pages = nr_pages;
+	node_states_check_changes_offline(nr_pages, zone, &arg);
+
+	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
+	ret = notifier_to_errno(ret);
+	if (ret)
+		goto failed_removal;
+
+	pfn = start_pfn;
+	expire = jiffies + timeout;
+	drain = 0;
+	retry_max = 5;
+repeat:
+	/* start memory hot removal */
+	ret = -EAGAIN;
+	if (time_after(jiffies, expire))
+		goto failed_removal;
+	ret = -EINTR;
+	if (signal_pending(current))
+		goto failed_removal;
+	ret = 0;
+	if (drain) {
+		lru_add_drain_all();
+		cond_resched();
+		drain_all_pages(zone);
+	}
+
+	pfn = scan_movable_pages(start_pfn, end_pfn);
+	if (pfn) { /* We have movable pages */
+		ret = do_migrate_range(pfn, end_pfn);
+		if (!ret) {
+			drain = 1;
+			goto repeat;
+		} else {
+			if (ret < 0)
+				if (--retry_max == 0)
+					goto failed_removal;
+			yield();
+			drain = 1;
+			goto repeat;
+		}
+	}
+	/* drain all zone's lru pagevec, this is asynchronous... */
+	lru_add_drain_all();
+	yield();
+	/* drain pcp pages, this is synchronous. */
+	drain_all_pages(zone);
+	/*
+	 * dissolve free hugepages in the memory block before doing offlining
+	 * actually in order to make hugetlbfs's object counting consistent.
+	 */
+	dissolve_free_huge_pages(start_pfn, end_pfn);
+	/* check again */
+	offlined_pages = check_pages_isolated(start_pfn, end_pfn);
+	if (offlined_pages < 0) {
+		ret = -EBUSY;
+		goto failed_removal;
+	}
+	printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
+	/* Ok, all of our target is isolated.
+	   We cannot do rollback at this point. */
+	offline_isolated_pages(start_pfn, end_pfn);
+	/* reset pagetype flags and makes migrate type to be MOVABLE */
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	/* removal success */
+	adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
+	zone->present_pages -= offlined_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	zone->zone_pgdat->node_present_pages -= offlined_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
+	init_per_zone_wmark_min();
+
+	if (!populated_zone(zone)) {
+		zone_pcp_reset(zone);
+		mutex_lock(&zonelists_mutex);
+		build_all_zonelists(NULL, NULL);
+		mutex_unlock(&zonelists_mutex);
+	} else
+		zone_pcp_update(zone);
+
+	node_states_clear_node(node, &arg);
+	if (arg.status_change_nid >= 0)
+		kswapd_stop(node);
+
+	vm_total_pages = nr_free_pagecache_pages();
+	writeback_set_ratelimit();
+
+	memory_notify(MEM_OFFLINE, &arg);
+	return 0;
+
+failed_removal:
+	printk(KERN_INFO "memory offlining [mem %#010llx-%#010llx] failed\n",
+	       (unsigned long long) start_pfn << PAGE_SHIFT,
+	       ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
+	memory_notify(MEM_CANCEL_OFFLINE, &arg);
+	/* pushback to free area */
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	return ret;
+}
+
+/* Must be protected by mem_hotplug_begin() */
+int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
+{
+	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+/**
+ * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
+ * @start_pfn: start pfn of the memory range
+ * @end_pfn: end pfn of the memory range
+ * @arg: argument passed to func
+ * @func: callback for each memory section walked
+ *
+ * This function walks through all present mem sections in range
+ * [start_pfn, end_pfn) and call func on each mem section.
+ *
+ * Returns the return value of func.
+ */
+int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+		void *arg, int (*func)(struct memory_block *, void *))
+{
+	struct memory_block *mem = NULL;
+	struct mem_section *section;
+	unsigned long pfn, section_nr;
+	int ret;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		section_nr = pfn_to_section_nr(pfn);
+		if (!present_section_nr(section_nr))
+			continue;
+
+		section = __nr_to_section(section_nr);
+		/* same memblock? */
+		if (mem)
+			if ((section_nr >= mem->start_section_nr) &&
+			    (section_nr <= mem->end_section_nr))
+				continue;
+
+		mem = find_memory_block_hinted(section, mem);
+		if (!mem)
+			continue;
+
+		ret = func(mem, arg);
+		if (ret) {
+			kobject_put(&mem->dev.kobj);
+			return ret;
+		}
+	}
+
+	if (mem)
+		kobject_put(&mem->dev.kobj);
+
+	return 0;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
+{
+	int ret = !is_memblock_offlined(mem);
+
+	if (unlikely(ret)) {
+		phys_addr_t beginpa, endpa;
+
+		beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
+		endpa = PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1;
+		pr_warn("removing memory fails, because memory "
+			"[%pa-%pa] is onlined\n",
+			&beginpa, &endpa);
+	}
+
+	return ret;
+}
+
+static int check_cpu_on_node(pg_data_t *pgdat)
+{
+	int cpu;
+
+	for_each_present_cpu(cpu) {
+		if (cpu_to_node(cpu) == pgdat->node_id)
+			/*
+			 * the cpu on this node isn't removed, and we can't
+			 * offline this node.
+			 */
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+static void unmap_cpu_on_node(pg_data_t *pgdat)
+{
+#ifdef CONFIG_ACPI_NUMA
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		if (cpu_to_node(cpu) == pgdat->node_id)
+			numa_clear_node(cpu);
+#endif
+}
+
+static int check_and_unmap_cpu_on_node(pg_data_t *pgdat)
+{
+	int ret;
+
+	ret = check_cpu_on_node(pgdat);
+	if (ret)
+		return ret;
+
+	/*
+	 * the node will be offlined when we come here, so we can clear
+	 * the cpu_to_node() now.
+	 */
+
+	unmap_cpu_on_node(pgdat);
+	return 0;
+}
+
+/**
+ * try_offline_node
+ *
+ * Offline a node if all memory sections and cpus of the node are removed.
+ *
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations before this call.
+ */
+void try_offline_node(int nid)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+	unsigned long start_pfn = pgdat->node_start_pfn;
+	unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
+	unsigned long pfn;
+	int i;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		unsigned long section_nr = pfn_to_section_nr(pfn);
+
+		if (!present_section_nr(section_nr))
+			continue;
+
+		if (pfn_to_nid(pfn) != nid)
+			continue;
+
+		/*
+		 * some memory sections of this node are not removed, and we
+		 * can't offline node now.
+		 */
+		return;
+	}
+
+	if (check_and_unmap_cpu_on_node(pgdat))
+		return;
+
+	/*
+	 * all memory/cpu of this node are removed, we can offline this
+	 * node now.
+	 */
+	node_set_offline(nid);
+	unregister_one_node(nid);
+
+	/* free waittable in each zone */
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		struct zone *zone = pgdat->node_zones + i;
+
+		/*
+		 * wait_table may be allocated from boot memory,
+		 * here only free if it's allocated by vmalloc.
+		 */
+		if (is_vmalloc_addr(zone->wait_table)) {
+			vfree(zone->wait_table);
+			zone->wait_table = NULL;
+		}
+	}
+}
+EXPORT_SYMBOL(try_offline_node);
+
+/**
+ * remove_memory
+ *
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations before this call, as required by
+ * try_offline_node().
+ */
+void __ref remove_memory(int nid, u64 start, u64 size)
+{
+	int ret;
+
+	BUG_ON(check_hotplug_memory_range(start, size));
+
+	mem_hotplug_begin();
+
+	/*
+	 * All memory blocks must be offlined before removing memory.  Check
+	 * whether all memory blocks in question are offline and trigger a BUG()
+	 * if this is not the case.
+	 */
+	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
+				check_memblock_offlined_cb);
+	if (ret)
+		BUG();
+
+	/* remove memmap entry */
+	firmware_map_remove(start, start + size, "System RAM");
+	memblock_free(start, size);
+	memblock_remove(start, size);
+
+	arch_remove_memory(start, size);
+
+	try_offline_node(nid);
+
+	mem_hotplug_done();
+}
+EXPORT_SYMBOL_GPL(remove_memory);
+#endif /* CONFIG_MEMORY_HOTREMOVE */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
new file mode 100644
index 0000000..c947014
--- /dev/null
+++ b/mm/mempolicy.c
@@ -0,0 +1,2819 @@
+/*
+ * Simple NUMA memory policy for the Linux kernel.
+ *
+ * Copyright 2003,2004 Andi Kleen, SuSE Labs.
+ * (C) Copyright 2005 Christoph Lameter, Silicon Graphics, Inc.
+ * Subject to the GNU Public License, version 2.
+ *
+ * NUMA policy allows the user to give hints in which node(s) memory should
+ * be allocated.
+ *
+ * Support four policies per VMA and per process:
+ *
+ * The VMA policy has priority over the process policy for a page fault.
+ *
+ * interleave     Allocate memory interleaved over a set of nodes,
+ *                with normal fallback if it fails.
+ *                For VMA based allocations this interleaves based on the
+ *                offset into the backing object or offset into the mapping
+ *                for anonymous memory. For process policy an process counter
+ *                is used.
+ *
+ * bind           Only allocate memory on a specific set of nodes,
+ *                no fallback.
+ *                FIXME: memory is allocated starting with the first node
+ *                to the last. It would be better if bind would truly restrict
+ *                the allocation to memory nodes instead
+ *
+ * preferred       Try a specific node first before normal fallback.
+ *                As a special case NUMA_NO_NODE here means do the allocation
+ *                on the local CPU. This is normally identical to default,
+ *                but useful to set in a VMA when you have a non default
+ *                process policy.
+ *
+ * default        Allocate on the local node first, or when on a VMA
+ *                use the process policy. This is what Linux always did
+ *		  in a NUMA aware kernel and still does by, ahem, default.
+ *
+ * The process policy is applied for most non interrupt memory allocations
+ * in that process' context. Interrupts ignore the policies and always
+ * try to allocate on the local CPU. The VMA policy is only applied for memory
+ * allocations for a VMA in the VM.
+ *
+ * Currently there are a few corner cases in swapping where the policy
+ * is not applied, but the majority should be handled. When process policy
+ * is used it is not remembered over swap outs/swap ins.
+ *
+ * Only the highest zone in the zone hierarchy gets policied. Allocations
+ * requesting a lower zone just use default policy. This implies that
+ * on systems with highmem kernel lowmem allocation don't get policied.
+ * Same with GFP_DMA allocations.
+ *
+ * For shmfs/tmpfs/hugetlbfs shared memory the policy is shared between
+ * all users and remembered even when nobody has memory mapped.
+ */
+
+/* Notebook:
+   fix mmap readahead to honour policy and enable policy for any page cache
+   object
+   statistics for bigpages
+   global policy for page cache? currently it uses process policy. Requires
+   first item above.
+   handle mremap for shared memory (currently ignored for the policy)
+   grows down?
+   make bind policy root only? It can trigger oom much faster and the
+   kernel is not always grateful with that.
+*/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mempolicy.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/hugetlb.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/nodemask.h>
+#include <linux/cpuset.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/export.h>
+#include <linux/nsproxy.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/compat.h>
+#include <linux/swap.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <linux/migrate.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/ctype.h>
+#include <linux/mm_inline.h>
+#include <linux/mmu_notifier.h>
+#include <linux/printk.h>
+
+#include <asm/tlbflush.h>
+#include <asm/uaccess.h>
+#include <linux/random.h>
+
+#include "internal.h"
+
+/* Internal flags */
+#define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)	/* Skip checks for continuous vmas */
+#define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)		/* Invert check for nodemask */
+
+static struct kmem_cache *policy_cache;
+static struct kmem_cache *sn_cache;
+
+/* Highest zone. An specific allocation for a zone below that is not
+   policied. */
+enum zone_type policy_zone = 0;
+
+/*
+ * run-time system-wide default policy => local allocation
+ */
+static struct mempolicy default_policy = {
+	.refcnt = ATOMIC_INIT(1), /* never free it */
+	.mode = MPOL_PREFERRED,
+	.flags = MPOL_F_LOCAL,
+};
+
+static struct mempolicy preferred_node_policy[MAX_NUMNODES];
+
+struct mempolicy *get_task_policy(struct task_struct *p)
+{
+	struct mempolicy *pol = p->mempolicy;
+	int node;
+
+	if (pol)
+		return pol;
+
+	node = numa_node_id();
+	if (node != NUMA_NO_NODE) {
+		pol = &preferred_node_policy[node];
+		/* preferred_node_policy is not initialised early in boot */
+		if (pol->mode)
+			return pol;
+	}
+
+	return &default_policy;
+}
+
+static const struct mempolicy_operations {
+	int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
+	/*
+	 * If read-side task has no lock to protect task->mempolicy, write-side
+	 * task will rebind the task->mempolicy by two step. The first step is
+	 * setting all the newly nodes, and the second step is cleaning all the
+	 * disallowed nodes. In this way, we can avoid finding no node to alloc
+	 * page.
+	 * If we have a lock to protect task->mempolicy in read-side, we do
+	 * rebind directly.
+	 *
+	 * step:
+	 * 	MPOL_REBIND_ONCE - do rebind work at once
+	 * 	MPOL_REBIND_STEP1 - set all the newly nodes
+	 * 	MPOL_REBIND_STEP2 - clean all the disallowed nodes
+	 */
+	void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes,
+			enum mpol_rebind_step step);
+} mpol_ops[MPOL_MAX];
+
+static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
+{
+	return pol->flags & MPOL_MODE_FLAGS;
+}
+
+static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
+				   const nodemask_t *rel)
+{
+	nodemask_t tmp;
+	nodes_fold(tmp, *orig, nodes_weight(*rel));
+	nodes_onto(*ret, tmp, *rel);
+}
+
+static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
+{
+	if (nodes_empty(*nodes))
+		return -EINVAL;
+	pol->v.nodes = *nodes;
+	return 0;
+}
+
+static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
+{
+	if (!nodes)
+		pol->flags |= MPOL_F_LOCAL;	/* local allocation */
+	else if (nodes_empty(*nodes))
+		return -EINVAL;			/*  no allowed nodes */
+	else
+		pol->v.preferred_node = first_node(*nodes);
+	return 0;
+}
+
+static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
+{
+	if (nodes_empty(*nodes))
+		return -EINVAL;
+	pol->v.nodes = *nodes;
+	return 0;
+}
+
+/*
+ * mpol_set_nodemask is called after mpol_new() to set up the nodemask, if
+ * any, for the new policy.  mpol_new() has already validated the nodes
+ * parameter with respect to the policy mode and flags.  But, we need to
+ * handle an empty nodemask with MPOL_PREFERRED here.
+ *
+ * Must be called holding task's alloc_lock to protect task's mems_allowed
+ * and mempolicy.  May also be called holding the mmap_semaphore for write.
+ */
+static int mpol_set_nodemask(struct mempolicy *pol,
+		     const nodemask_t *nodes, struct nodemask_scratch *nsc)
+{
+	int ret;
+
+	/* if mode is MPOL_DEFAULT, pol is NULL. This is right. */
+	if (pol == NULL)
+		return 0;
+	/* Check N_MEMORY */
+	nodes_and(nsc->mask1,
+		  cpuset_current_mems_allowed, node_states[N_MEMORY]);
+
+	VM_BUG_ON(!nodes);
+	if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes))
+		nodes = NULL;	/* explicit local allocation */
+	else {
+		if (pol->flags & MPOL_F_RELATIVE_NODES)
+			mpol_relative_nodemask(&nsc->mask2, nodes, &nsc->mask1);
+		else
+			nodes_and(nsc->mask2, *nodes, nsc->mask1);
+
+		if (mpol_store_user_nodemask(pol))
+			pol->w.user_nodemask = *nodes;
+		else
+			pol->w.cpuset_mems_allowed =
+						cpuset_current_mems_allowed;
+	}
+
+	if (nodes)
+		ret = mpol_ops[pol->mode].create(pol, &nsc->mask2);
+	else
+		ret = mpol_ops[pol->mode].create(pol, NULL);
+	return ret;
+}
+
+/*
+ * This function just creates a new policy, does some check and simple
+ * initialization. You must invoke mpol_set_nodemask() to set nodes.
+ */
+static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
+				  nodemask_t *nodes)
+{
+	struct mempolicy *policy;
+
+	pr_debug("setting mode %d flags %d nodes[0] %lx\n",
+		 mode, flags, nodes ? nodes_addr(*nodes)[0] : NUMA_NO_NODE);
+
+	if (mode == MPOL_DEFAULT) {
+		if (nodes && !nodes_empty(*nodes))
+			return ERR_PTR(-EINVAL);
+		return NULL;
+	}
+	VM_BUG_ON(!nodes);
+
+	/*
+	 * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
+	 * MPOL_F_RELATIVE_NODES if the nodemask is empty (local allocation).
+	 * All other modes require a valid pointer to a non-empty nodemask.
+	 */
+	if (mode == MPOL_PREFERRED) {
+		if (nodes_empty(*nodes)) {
+			if (((flags & MPOL_F_STATIC_NODES) ||
+			     (flags & MPOL_F_RELATIVE_NODES)))
+				return ERR_PTR(-EINVAL);
+		}
+	} else if (mode == MPOL_LOCAL) {
+		if (!nodes_empty(*nodes))
+			return ERR_PTR(-EINVAL);
+		mode = MPOL_PREFERRED;
+	} else if (nodes_empty(*nodes))
+		return ERR_PTR(-EINVAL);
+	policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+	if (!policy)
+		return ERR_PTR(-ENOMEM);
+	atomic_set(&policy->refcnt, 1);
+	policy->mode = mode;
+	policy->flags = flags;
+
+	return policy;
+}
+
+/* Slow path of a mpol destructor. */
+void __mpol_put(struct mempolicy *p)
+{
+	if (!atomic_dec_and_test(&p->refcnt))
+		return;
+	kmem_cache_free(policy_cache, p);
+}
+
+static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes,
+				enum mpol_rebind_step step)
+{
+}
+
+/*
+ * step:
+ * 	MPOL_REBIND_ONCE  - do rebind work at once
+ * 	MPOL_REBIND_STEP1 - set all the newly nodes
+ * 	MPOL_REBIND_STEP2 - clean all the disallowed nodes
+ */
+static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes,
+				 enum mpol_rebind_step step)
+{
+	nodemask_t tmp;
+
+	if (pol->flags & MPOL_F_STATIC_NODES)
+		nodes_and(tmp, pol->w.user_nodemask, *nodes);
+	else if (pol->flags & MPOL_F_RELATIVE_NODES)
+		mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
+	else {
+		/*
+		 * if step == 1, we use ->w.cpuset_mems_allowed to cache the
+		 * result
+		 */
+		if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP1) {
+			nodes_remap(tmp, pol->v.nodes,
+					pol->w.cpuset_mems_allowed, *nodes);
+			pol->w.cpuset_mems_allowed = step ? tmp : *nodes;
+		} else if (step == MPOL_REBIND_STEP2) {
+			tmp = pol->w.cpuset_mems_allowed;
+			pol->w.cpuset_mems_allowed = *nodes;
+		} else
+			BUG();
+	}
+
+	if (nodes_empty(tmp))
+		tmp = *nodes;
+
+	if (step == MPOL_REBIND_STEP1)
+		nodes_or(pol->v.nodes, pol->v.nodes, tmp);
+	else if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP2)
+		pol->v.nodes = tmp;
+	else
+		BUG();
+
+	if (!node_isset(current->il_next, tmp)) {
+		current->il_next = next_node(current->il_next, tmp);
+		if (current->il_next >= MAX_NUMNODES)
+			current->il_next = first_node(tmp);
+		if (current->il_next >= MAX_NUMNODES)
+			current->il_next = numa_node_id();
+	}
+}
+
+static void mpol_rebind_preferred(struct mempolicy *pol,
+				  const nodemask_t *nodes,
+				  enum mpol_rebind_step step)
+{
+	nodemask_t tmp;
+
+	if (pol->flags & MPOL_F_STATIC_NODES) {
+		int node = first_node(pol->w.user_nodemask);
+
+		if (node_isset(node, *nodes)) {
+			pol->v.preferred_node = node;
+			pol->flags &= ~MPOL_F_LOCAL;
+		} else
+			pol->flags |= MPOL_F_LOCAL;
+	} else if (pol->flags & MPOL_F_RELATIVE_NODES) {
+		mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
+		pol->v.preferred_node = first_node(tmp);
+	} else if (!(pol->flags & MPOL_F_LOCAL)) {
+		pol->v.preferred_node = node_remap(pol->v.preferred_node,
+						   pol->w.cpuset_mems_allowed,
+						   *nodes);
+		pol->w.cpuset_mems_allowed = *nodes;
+	}
+}
+
+/*
+ * mpol_rebind_policy - Migrate a policy to a different set of nodes
+ *
+ * If read-side task has no lock to protect task->mempolicy, write-side
+ * task will rebind the task->mempolicy by two step. The first step is
+ * setting all the newly nodes, and the second step is cleaning all the
+ * disallowed nodes. In this way, we can avoid finding no node to alloc
+ * page.
+ * If we have a lock to protect task->mempolicy in read-side, we do
+ * rebind directly.
+ *
+ * step:
+ * 	MPOL_REBIND_ONCE  - do rebind work at once
+ * 	MPOL_REBIND_STEP1 - set all the newly nodes
+ * 	MPOL_REBIND_STEP2 - clean all the disallowed nodes
+ */
+static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask,
+				enum mpol_rebind_step step)
+{
+	if (!pol)
+		return;
+	if (!mpol_store_user_nodemask(pol) && step == MPOL_REBIND_ONCE &&
+	    nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
+		return;
+
+	if (step == MPOL_REBIND_STEP1 && (pol->flags & MPOL_F_REBINDING))
+		return;
+
+	if (step == MPOL_REBIND_STEP2 && !(pol->flags & MPOL_F_REBINDING))
+		BUG();
+
+	if (step == MPOL_REBIND_STEP1)
+		pol->flags |= MPOL_F_REBINDING;
+	else if (step == MPOL_REBIND_STEP2)
+		pol->flags &= ~MPOL_F_REBINDING;
+	else if (step >= MPOL_REBIND_NSTEP)
+		BUG();
+
+	mpol_ops[pol->mode].rebind(pol, newmask, step);
+}
+
+/*
+ * Wrapper for mpol_rebind_policy() that just requires task
+ * pointer, and updates task mempolicy.
+ *
+ * Called with task's alloc_lock held.
+ */
+
+void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
+			enum mpol_rebind_step step)
+{
+	mpol_rebind_policy(tsk->mempolicy, new, step);
+}
+
+/*
+ * Rebind each vma in mm to new nodemask.
+ *
+ * Call holding a reference to mm.  Takes mm->mmap_sem during call.
+ */
+
+void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
+{
+	struct vm_area_struct *vma;
+
+	down_write(&mm->mmap_sem);
+	for (vma = mm->mmap; vma; vma = vma->vm_next)
+		mpol_rebind_policy(vma->vm_policy, new, MPOL_REBIND_ONCE);
+	up_write(&mm->mmap_sem);
+}
+
+static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
+	[MPOL_DEFAULT] = {
+		.rebind = mpol_rebind_default,
+	},
+	[MPOL_INTERLEAVE] = {
+		.create = mpol_new_interleave,
+		.rebind = mpol_rebind_nodemask,
+	},
+	[MPOL_PREFERRED] = {
+		.create = mpol_new_preferred,
+		.rebind = mpol_rebind_preferred,
+	},
+	[MPOL_BIND] = {
+		.create = mpol_new_bind,
+		.rebind = mpol_rebind_nodemask,
+	},
+};
+
+static void migrate_page_add(struct page *page, struct list_head *pagelist,
+				unsigned long flags);
+
+struct queue_pages {
+	struct list_head *pagelist;
+	unsigned long flags;
+	nodemask_t *nmask;
+	struct vm_area_struct *prev;
+};
+
+/*
+ * Scan through pages checking if pages follow certain conditions,
+ * and move them to the pagelist if they do.
+ */
+static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
+			unsigned long end, struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+	struct page *page;
+	struct queue_pages *qp = walk->private;
+	unsigned long flags = qp->flags;
+	int nid;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	split_huge_page_pmd(vma, addr, pmd);
+	if (pmd_trans_unstable(pmd))
+		return 0;
+
+	pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+	for (; addr != end; pte++, addr += PAGE_SIZE) {
+		if (!pte_present(*pte))
+			continue;
+		page = vm_normal_page(vma, addr, *pte);
+		if (!page)
+			continue;
+		/*
+		 * vm_normal_page() filters out zero pages, but there might
+		 * still be PageReserved pages to skip, perhaps in a VDSO.
+		 */
+		if (PageReserved(page))
+			continue;
+		nid = page_to_nid(page);
+		if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
+			continue;
+
+		if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+			migrate_page_add(page, qp->pagelist, flags);
+	}
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+	return 0;
+}
+
+static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
+			       unsigned long addr, unsigned long end,
+			       struct mm_walk *walk)
+{
+#ifdef CONFIG_HUGETLB_PAGE
+	struct queue_pages *qp = walk->private;
+	unsigned long flags = qp->flags;
+	int nid;
+	struct page *page;
+	spinlock_t *ptl;
+	pte_t entry;
+
+	ptl = huge_pte_lock(hstate_vma(walk->vma), walk->mm, pte);
+	entry = huge_ptep_get(pte);
+	if (!pte_present(entry))
+		goto unlock;
+	page = pte_page(entry);
+	nid = page_to_nid(page);
+	if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
+		goto unlock;
+	/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
+	if (flags & (MPOL_MF_MOVE_ALL) ||
+	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
+		isolate_huge_page(page, qp->pagelist);
+unlock:
+	spin_unlock(ptl);
+#else
+	BUG();
+#endif
+	return 0;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+/*
+ * This is used to mark a range of virtual addresses to be inaccessible.
+ * These are later cleared by a NUMA hinting fault. Depending on these
+ * faults, pages may be migrated for better NUMA placement.
+ *
+ * This is assuming that NUMA faults are handled using PROT_NONE. If
+ * an architecture makes a different choice, it will need further
+ * changes to the core.
+ */
+unsigned long change_prot_numa(struct vm_area_struct *vma,
+			unsigned long addr, unsigned long end)
+{
+	int nr_updated;
+
+	nr_updated = change_protection(vma, addr, end, PAGE_NONE, 0, 1);
+	if (nr_updated)
+		count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated);
+
+	return nr_updated;
+}
+#else
+static unsigned long change_prot_numa(struct vm_area_struct *vma,
+			unsigned long addr, unsigned long end)
+{
+	return 0;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+static int queue_pages_test_walk(unsigned long start, unsigned long end,
+				struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+	struct queue_pages *qp = walk->private;
+	unsigned long endvma = vma->vm_end;
+	unsigned long flags = qp->flags;
+
+	if (vma->vm_flags & VM_PFNMAP)
+		return 1;
+
+	if (endvma > end)
+		endvma = end;
+	if (vma->vm_start > start)
+		start = vma->vm_start;
+
+	if (!(flags & MPOL_MF_DISCONTIG_OK)) {
+		if (!vma->vm_next && vma->vm_end < end)
+			return -EFAULT;
+		if (qp->prev && qp->prev->vm_end < vma->vm_start)
+			return -EFAULT;
+	}
+
+	qp->prev = vma;
+
+	if (flags & MPOL_MF_LAZY) {
+		/* Similar to task_numa_work, skip inaccessible VMAs */
+		if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
+			change_prot_numa(vma, start, endvma);
+		return 1;
+	}
+
+	if ((flags & MPOL_MF_STRICT) ||
+	    ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
+	     vma_migratable(vma)))
+		/* queue pages from current vma */
+		return 0;
+	return 1;
+}
+
+/*
+ * Walk through page tables and collect pages to be migrated.
+ *
+ * If pages found in a given range are on a set of nodes (determined by
+ * @nodes and @flags,) it's isolated and queued to the pagelist which is
+ * passed via @private.)
+ */
+static int
+queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
+		nodemask_t *nodes, unsigned long flags,
+		struct list_head *pagelist)
+{
+	struct queue_pages qp = {
+		.pagelist = pagelist,
+		.flags = flags,
+		.nmask = nodes,
+		.prev = NULL,
+	};
+	struct mm_walk queue_pages_walk = {
+		.hugetlb_entry = queue_pages_hugetlb,
+		.pmd_entry = queue_pages_pte_range,
+		.test_walk = queue_pages_test_walk,
+		.mm = mm,
+		.private = &qp,
+	};
+
+	return walk_page_range(start, end, &queue_pages_walk);
+}
+
+/*
+ * Apply policy to a single VMA
+ * This must be called with the mmap_sem held for writing.
+ */
+static int vma_replace_policy(struct vm_area_struct *vma,
+						struct mempolicy *pol)
+{
+	int err;
+	struct mempolicy *old;
+	struct mempolicy *new;
+
+	pr_debug("vma %lx-%lx/%lx vm_ops %p vm_file %p set_policy %p\n",
+		 vma->vm_start, vma->vm_end, vma->vm_pgoff,
+		 vma->vm_ops, vma->vm_file,
+		 vma->vm_ops ? vma->vm_ops->set_policy : NULL);
+
+	new = mpol_dup(pol);
+	if (IS_ERR(new))
+		return PTR_ERR(new);
+
+	if (vma->vm_ops && vma->vm_ops->set_policy) {
+		err = vma->vm_ops->set_policy(vma, new);
+		if (err)
+			goto err_out;
+	}
+
+	old = vma->vm_policy;
+	vma->vm_policy = new; /* protected by mmap_sem */
+	mpol_put(old);
+
+	return 0;
+ err_out:
+	mpol_put(new);
+	return err;
+}
+
+/* Step 2: apply policy to a range and do splits. */
+static int mbind_range(struct mm_struct *mm, unsigned long start,
+		       unsigned long end, struct mempolicy *new_pol)
+{
+	struct vm_area_struct *next;
+	struct vm_area_struct *prev;
+	struct vm_area_struct *vma;
+	int err = 0;
+	pgoff_t pgoff;
+	unsigned long vmstart;
+	unsigned long vmend;
+
+	vma = find_vma(mm, start);
+	if (!vma || vma->vm_start > start)
+		return -EFAULT;
+
+	prev = vma->vm_prev;
+	if (start > vma->vm_start)
+		prev = vma;
+
+	for (; vma && vma->vm_start < end; prev = vma, vma = next) {
+		next = vma->vm_next;
+		vmstart = max(start, vma->vm_start);
+		vmend   = min(end, vma->vm_end);
+
+		if (mpol_equal(vma_policy(vma), new_pol))
+			continue;
+
+		pgoff = vma->vm_pgoff +
+			((vmstart - vma->vm_start) >> PAGE_SHIFT);
+		prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
+				 vma->anon_vma, vma->vm_file, pgoff,
+				 new_pol, vma->vm_userfaultfd_ctx);
+		if (prev) {
+			vma = prev;
+			next = vma->vm_next;
+			if (mpol_equal(vma_policy(vma), new_pol))
+				continue;
+			/* vma_merge() joined vma && vma->next, case 8 */
+			goto replace;
+		}
+		if (vma->vm_start != vmstart) {
+			err = split_vma(vma->vm_mm, vma, vmstart, 1);
+			if (err)
+				goto out;
+		}
+		if (vma->vm_end != vmend) {
+			err = split_vma(vma->vm_mm, vma, vmend, 0);
+			if (err)
+				goto out;
+		}
+ replace:
+		err = vma_replace_policy(vma, new_pol);
+		if (err)
+			goto out;
+	}
+
+ out:
+	return err;
+}
+
+/* Set the process memory policy */
+static long do_set_mempolicy(unsigned short mode, unsigned short flags,
+			     nodemask_t *nodes)
+{
+	struct mempolicy *new, *old;
+	NODEMASK_SCRATCH(scratch);
+	int ret;
+
+	if (!scratch)
+		return -ENOMEM;
+
+	new = mpol_new(mode, flags, nodes);
+	if (IS_ERR(new)) {
+		ret = PTR_ERR(new);
+		goto out;
+	}
+
+	task_lock(current);
+	ret = mpol_set_nodemask(new, nodes, scratch);
+	if (ret) {
+		task_unlock(current);
+		mpol_put(new);
+		goto out;
+	}
+	old = current->mempolicy;
+	current->mempolicy = new;
+	if (new && new->mode == MPOL_INTERLEAVE &&
+	    nodes_weight(new->v.nodes))
+		current->il_next = first_node(new->v.nodes);
+	task_unlock(current);
+	mpol_put(old);
+	ret = 0;
+out:
+	NODEMASK_SCRATCH_FREE(scratch);
+	return ret;
+}
+
+/*
+ * Return nodemask for policy for get_mempolicy() query
+ *
+ * Called with task's alloc_lock held
+ */
+static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
+{
+	nodes_clear(*nodes);
+	if (p == &default_policy)
+		return;
+
+	switch (p->mode) {
+	case MPOL_BIND:
+		/* Fall through */
+	case MPOL_INTERLEAVE:
+		*nodes = p->v.nodes;
+		break;
+	case MPOL_PREFERRED:
+		if (!(p->flags & MPOL_F_LOCAL))
+			node_set(p->v.preferred_node, *nodes);
+		/* else return empty node mask for local allocation */
+		break;
+	default:
+		BUG();
+	}
+}
+
+static int lookup_node(struct mm_struct *mm, unsigned long addr)
+{
+	struct page *p;
+	int err;
+
+	err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, 0, &p, NULL);
+	if (err >= 0) {
+		err = page_to_nid(p);
+		put_page(p);
+	}
+	return err;
+}
+
+/* Retrieve NUMA policy */
+static long do_get_mempolicy(int *policy, nodemask_t *nmask,
+			     unsigned long addr, unsigned long flags)
+{
+	int err;
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma = NULL;
+	struct mempolicy *pol = current->mempolicy;
+
+	if (flags &
+		~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
+		return -EINVAL;
+
+	if (flags & MPOL_F_MEMS_ALLOWED) {
+		if (flags & (MPOL_F_NODE|MPOL_F_ADDR))
+			return -EINVAL;
+		*policy = 0;	/* just so it's initialized */
+		task_lock(current);
+		*nmask  = cpuset_current_mems_allowed;
+		task_unlock(current);
+		return 0;
+	}
+
+	if (flags & MPOL_F_ADDR) {
+		/*
+		 * Do NOT fall back to task policy if the
+		 * vma/shared policy at addr is NULL.  We
+		 * want to return MPOL_DEFAULT in this case.
+		 */
+		down_read(&mm->mmap_sem);
+		vma = find_vma_intersection(mm, addr, addr+1);
+		if (!vma) {
+			up_read(&mm->mmap_sem);
+			return -EFAULT;
+		}
+		if (vma->vm_ops && vma->vm_ops->get_policy)
+			pol = vma->vm_ops->get_policy(vma, addr);
+		else
+			pol = vma->vm_policy;
+	} else if (addr)
+		return -EINVAL;
+
+	if (!pol)
+		pol = &default_policy;	/* indicates default behavior */
+
+	if (flags & MPOL_F_NODE) {
+		if (flags & MPOL_F_ADDR) {
+			err = lookup_node(mm, addr);
+			if (err < 0)
+				goto out;
+			*policy = err;
+		} else if (pol == current->mempolicy &&
+				pol->mode == MPOL_INTERLEAVE) {
+			*policy = current->il_next;
+		} else {
+			err = -EINVAL;
+			goto out;
+		}
+	} else {
+		*policy = pol == &default_policy ? MPOL_DEFAULT :
+						pol->mode;
+		/*
+		 * Internal mempolicy flags must be masked off before exposing
+		 * the policy to userspace.
+		 */
+		*policy |= (pol->flags & MPOL_MODE_FLAGS);
+	}
+
+	err = 0;
+	if (nmask) {
+		if (mpol_store_user_nodemask(pol)) {
+			*nmask = pol->w.user_nodemask;
+		} else {
+			task_lock(current);
+			get_policy_nodemask(pol, nmask);
+			task_unlock(current);
+		}
+	}
+
+ out:
+	mpol_cond_put(pol);
+	if (vma)
+		up_read(&current->mm->mmap_sem);
+	return err;
+}
+
+#ifdef CONFIG_MIGRATION
+/*
+ * page migration
+ */
+static void migrate_page_add(struct page *page, struct list_head *pagelist,
+				unsigned long flags)
+{
+	/*
+	 * Avoid migrating a page that is shared with others.
+	 */
+	if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1) {
+		if (!isolate_lru_page(page)) {
+			list_add_tail(&page->lru, pagelist);
+			inc_zone_page_state(page, NR_ISOLATED_ANON +
+					    page_is_file_cache(page));
+		}
+	}
+}
+
+static struct page *new_node_page(struct page *page, unsigned long node, int **x)
+{
+	if (PageHuge(page))
+		return alloc_huge_page_node(page_hstate(compound_head(page)),
+					node);
+	else
+		return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
+						    __GFP_THISNODE, 0);
+}
+
+/*
+ * Migrate pages from one node to a target node.
+ * Returns error or the number of pages not migrated.
+ */
+static int migrate_to_node(struct mm_struct *mm, int source, int dest,
+			   int flags)
+{
+	nodemask_t nmask;
+	LIST_HEAD(pagelist);
+	int err = 0;
+
+	nodes_clear(nmask);
+	node_set(source, nmask);
+
+	/*
+	 * This does not "check" the range but isolates all pages that
+	 * need migration.  Between passing in the full user address
+	 * space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
+	 */
+	VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
+	queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
+			flags | MPOL_MF_DISCONTIG_OK, &pagelist);
+
+	if (!list_empty(&pagelist)) {
+		err = migrate_pages(&pagelist, new_node_page, NULL, dest,
+					MIGRATE_SYNC, MR_SYSCALL);
+		if (err)
+			putback_movable_pages(&pagelist);
+	}
+
+	return err;
+}
+
+/*
+ * Move pages between the two nodesets so as to preserve the physical
+ * layout as much as possible.
+ *
+ * Returns the number of page that could not be moved.
+ */
+int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
+		     const nodemask_t *to, int flags)
+{
+	int busy = 0;
+	int err;
+	nodemask_t tmp;
+
+	err = migrate_prep();
+	if (err)
+		return err;
+
+	down_read(&mm->mmap_sem);
+
+	/*
+	 * Find a 'source' bit set in 'tmp' whose corresponding 'dest'
+	 * bit in 'to' is not also set in 'tmp'.  Clear the found 'source'
+	 * bit in 'tmp', and return that <source, dest> pair for migration.
+	 * The pair of nodemasks 'to' and 'from' define the map.
+	 *
+	 * If no pair of bits is found that way, fallback to picking some
+	 * pair of 'source' and 'dest' bits that are not the same.  If the
+	 * 'source' and 'dest' bits are the same, this represents a node
+	 * that will be migrating to itself, so no pages need move.
+	 *
+	 * If no bits are left in 'tmp', or if all remaining bits left
+	 * in 'tmp' correspond to the same bit in 'to', return false
+	 * (nothing left to migrate).
+	 *
+	 * This lets us pick a pair of nodes to migrate between, such that
+	 * if possible the dest node is not already occupied by some other
+	 * source node, minimizing the risk of overloading the memory on a
+	 * node that would happen if we migrated incoming memory to a node
+	 * before migrating outgoing memory source that same node.
+	 *
+	 * A single scan of tmp is sufficient.  As we go, we remember the
+	 * most recent <s, d> pair that moved (s != d).  If we find a pair
+	 * that not only moved, but what's better, moved to an empty slot
+	 * (d is not set in tmp), then we break out then, with that pair.
+	 * Otherwise when we finish scanning from_tmp, we at least have the
+	 * most recent <s, d> pair that moved.  If we get all the way through
+	 * the scan of tmp without finding any node that moved, much less
+	 * moved to an empty node, then there is nothing left worth migrating.
+	 */
+
+	tmp = *from;
+	while (!nodes_empty(tmp)) {
+		int s,d;
+		int source = NUMA_NO_NODE;
+		int dest = 0;
+
+		for_each_node_mask(s, tmp) {
+
+			/*
+			 * do_migrate_pages() tries to maintain the relative
+			 * node relationship of the pages established between
+			 * threads and memory areas.
+                         *
+			 * However if the number of source nodes is not equal to
+			 * the number of destination nodes we can not preserve
+			 * this node relative relationship.  In that case, skip
+			 * copying memory from a node that is in the destination
+			 * mask.
+			 *
+			 * Example: [2,3,4] -> [3,4,5] moves everything.
+			 *          [0-7] - > [3,4,5] moves only 0,1,2,6,7.
+			 */
+
+			if ((nodes_weight(*from) != nodes_weight(*to)) &&
+						(node_isset(s, *to)))
+				continue;
+
+			d = node_remap(s, *from, *to);
+			if (s == d)
+				continue;
+
+			source = s;	/* Node moved. Memorize */
+			dest = d;
+
+			/* dest not in remaining from nodes? */
+			if (!node_isset(dest, tmp))
+				break;
+		}
+		if (source == NUMA_NO_NODE)
+			break;
+
+		node_clear(source, tmp);
+		err = migrate_to_node(mm, source, dest, flags);
+		if (err > 0)
+			busy += err;
+		if (err < 0)
+			break;
+	}
+	up_read(&mm->mmap_sem);
+	if (err < 0)
+		return err;
+	return busy;
+
+}
+
+/*
+ * Allocate a new page for page migration based on vma policy.
+ * Start by assuming the page is mapped by the same vma as contains @start.
+ * Search forward from there, if not.  N.B., this assumes that the
+ * list of pages handed to migrate_pages()--which is how we get here--
+ * is in virtual address order.
+ */
+static struct page *new_page(struct page *page, unsigned long start, int **x)
+{
+	struct vm_area_struct *vma;
+	unsigned long uninitialized_var(address);
+
+	vma = find_vma(current->mm, start);
+	while (vma) {
+		address = page_address_in_vma(page, vma);
+		if (address != -EFAULT)
+			break;
+		vma = vma->vm_next;
+	}
+
+	if (PageHuge(page)) {
+		BUG_ON(!vma);
+		return alloc_huge_page_noerr(vma, address, 1);
+	}
+	/*
+	 * if !vma, alloc_page_vma() will use task or system default policy
+	 */
+	return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+}
+#else
+
+static void migrate_page_add(struct page *page, struct list_head *pagelist,
+				unsigned long flags)
+{
+}
+
+int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
+		     const nodemask_t *to, int flags)
+{
+	return -ENOSYS;
+}
+
+static struct page *new_page(struct page *page, unsigned long start, int **x)
+{
+	return NULL;
+}
+#endif
+
+static long do_mbind(unsigned long start, unsigned long len,
+		     unsigned short mode, unsigned short mode_flags,
+		     nodemask_t *nmask, unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct mempolicy *new;
+	unsigned long end;
+	int err;
+	LIST_HEAD(pagelist);
+
+	if (flags & ~(unsigned long)MPOL_MF_VALID)
+		return -EINVAL;
+	if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
+		return -EPERM;
+
+	if (start & ~PAGE_MASK)
+		return -EINVAL;
+
+	if (mode == MPOL_DEFAULT)
+		flags &= ~MPOL_MF_STRICT;
+
+	len = (len + PAGE_SIZE - 1) & PAGE_MASK;
+	end = start + len;
+
+	if (end < start)
+		return -EINVAL;
+	if (end == start)
+		return 0;
+
+	new = mpol_new(mode, mode_flags, nmask);
+	if (IS_ERR(new))
+		return PTR_ERR(new);
+
+	if (flags & MPOL_MF_LAZY)
+		new->flags |= MPOL_F_MOF;
+
+	/*
+	 * If we are using the default policy then operation
+	 * on discontinuous address spaces is okay after all
+	 */
+	if (!new)
+		flags |= MPOL_MF_DISCONTIG_OK;
+
+	pr_debug("mbind %lx-%lx mode:%d flags:%d nodes:%lx\n",
+		 start, start + len, mode, mode_flags,
+		 nmask ? nodes_addr(*nmask)[0] : NUMA_NO_NODE);
+
+	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+
+		err = migrate_prep();
+		if (err)
+			goto mpol_out;
+	}
+	{
+		NODEMASK_SCRATCH(scratch);
+		if (scratch) {
+			down_write(&mm->mmap_sem);
+			task_lock(current);
+			err = mpol_set_nodemask(new, nmask, scratch);
+			task_unlock(current);
+			if (err)
+				up_write(&mm->mmap_sem);
+		} else
+			err = -ENOMEM;
+		NODEMASK_SCRATCH_FREE(scratch);
+	}
+	if (err)
+		goto mpol_out;
+
+	err = queue_pages_range(mm, start, end, nmask,
+			  flags | MPOL_MF_INVERT, &pagelist);
+	if (!err)
+		err = mbind_range(mm, start, end, new);
+
+	if (!err) {
+		int nr_failed = 0;
+
+		if (!list_empty(&pagelist)) {
+			WARN_ON_ONCE(flags & MPOL_MF_LAZY);
+			nr_failed = migrate_pages(&pagelist, new_page, NULL,
+				start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
+			if (nr_failed)
+				putback_movable_pages(&pagelist);
+		}
+
+		if (nr_failed && (flags & MPOL_MF_STRICT))
+			err = -EIO;
+	} else
+		putback_movable_pages(&pagelist);
+
+	up_write(&mm->mmap_sem);
+ mpol_out:
+	mpol_put(new);
+	return err;
+}
+
+/*
+ * User space interface with variable sized bitmaps for nodelists.
+ */
+
+/* Copy a node mask from user space. */
+static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
+		     unsigned long maxnode)
+{
+	unsigned long k;
+	unsigned long nlongs;
+	unsigned long endmask;
+
+	--maxnode;
+	nodes_clear(*nodes);
+	if (maxnode == 0 || !nmask)
+		return 0;
+	if (maxnode > PAGE_SIZE*BITS_PER_BYTE)
+		return -EINVAL;
+
+	nlongs = BITS_TO_LONGS(maxnode);
+	if ((maxnode % BITS_PER_LONG) == 0)
+		endmask = ~0UL;
+	else
+		endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1;
+
+	/* When the user specified more nodes than supported just check
+	   if the non supported part is all zero. */
+	if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
+		if (nlongs > PAGE_SIZE/sizeof(long))
+			return -EINVAL;
+		for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
+			unsigned long t;
+			if (get_user(t, nmask + k))
+				return -EFAULT;
+			if (k == nlongs - 1) {
+				if (t & endmask)
+					return -EINVAL;
+			} else if (t)
+				return -EINVAL;
+		}
+		nlongs = BITS_TO_LONGS(MAX_NUMNODES);
+		endmask = ~0UL;
+	}
+
+	if (copy_from_user(nodes_addr(*nodes), nmask, nlongs*sizeof(unsigned long)))
+		return -EFAULT;
+	nodes_addr(*nodes)[nlongs-1] &= endmask;
+	return 0;
+}
+
+/* Copy a kernel node mask to user space */
+static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
+			      nodemask_t *nodes)
+{
+	unsigned long copy = ALIGN(maxnode-1, 64) / 8;
+	const int nbytes = BITS_TO_LONGS(MAX_NUMNODES) * sizeof(long);
+
+	if (copy > nbytes) {
+		if (copy > PAGE_SIZE)
+			return -EINVAL;
+		if (clear_user((char __user *)mask + nbytes, copy - nbytes))
+			return -EFAULT;
+		copy = nbytes;
+	}
+	return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
+}
+
+SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
+		unsigned long, mode, const unsigned long __user *, nmask,
+		unsigned long, maxnode, unsigned, flags)
+{
+	nodemask_t nodes;
+	int err;
+	unsigned short mode_flags;
+
+	mode_flags = mode & MPOL_MODE_FLAGS;
+	mode &= ~MPOL_MODE_FLAGS;
+	if (mode >= MPOL_MAX)
+		return -EINVAL;
+	if ((mode_flags & MPOL_F_STATIC_NODES) &&
+	    (mode_flags & MPOL_F_RELATIVE_NODES))
+		return -EINVAL;
+	err = get_nodes(&nodes, nmask, maxnode);
+	if (err)
+		return err;
+	return do_mbind(start, len, mode, mode_flags, &nodes, flags);
+}
+
+/* Set the process memory policy */
+SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
+		unsigned long, maxnode)
+{
+	int err;
+	nodemask_t nodes;
+	unsigned short flags;
+
+	flags = mode & MPOL_MODE_FLAGS;
+	mode &= ~MPOL_MODE_FLAGS;
+	if ((unsigned int)mode >= MPOL_MAX)
+		return -EINVAL;
+	if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
+		return -EINVAL;
+	err = get_nodes(&nodes, nmask, maxnode);
+	if (err)
+		return err;
+	return do_set_mempolicy(mode, flags, &nodes);
+}
+
+SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
+		const unsigned long __user *, old_nodes,
+		const unsigned long __user *, new_nodes)
+{
+	const struct cred *cred = current_cred(), *tcred;
+	struct mm_struct *mm = NULL;
+	struct task_struct *task;
+	nodemask_t task_nodes;
+	int err;
+	nodemask_t *old;
+	nodemask_t *new;
+	NODEMASK_SCRATCH(scratch);
+
+	if (!scratch)
+		return -ENOMEM;
+
+	old = &scratch->mask1;
+	new = &scratch->mask2;
+
+	err = get_nodes(old, old_nodes, maxnode);
+	if (err)
+		goto out;
+
+	err = get_nodes(new, new_nodes, maxnode);
+	if (err)
+		goto out;
+
+	/* Find the mm_struct */
+	rcu_read_lock();
+	task = pid ? find_task_by_vpid(pid) : current;
+	if (!task) {
+		rcu_read_unlock();
+		err = -ESRCH;
+		goto out;
+	}
+	get_task_struct(task);
+
+	err = -EINVAL;
+
+	/*
+	 * Check if this process has the right to modify the specified
+	 * process. The right exists if the process has administrative
+	 * capabilities, superuser privileges or the same
+	 * userid as the target process.
+	 */
+	tcred = __task_cred(task);
+	if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
+	    !uid_eq(cred->uid,  tcred->suid) && !uid_eq(cred->uid,  tcred->uid) &&
+	    !capable(CAP_SYS_NICE)) {
+		rcu_read_unlock();
+		err = -EPERM;
+		goto out_put;
+	}
+	rcu_read_unlock();
+
+	task_nodes = cpuset_mems_allowed(task);
+	/* Is the user allowed to access the target nodes? */
+	if (!nodes_subset(*new, task_nodes) && !capable(CAP_SYS_NICE)) {
+		err = -EPERM;
+		goto out_put;
+	}
+
+	if (!nodes_subset(*new, node_states[N_MEMORY])) {
+		err = -EINVAL;
+		goto out_put;
+	}
+
+	err = security_task_movememory(task);
+	if (err)
+		goto out_put;
+
+	mm = get_task_mm(task);
+	put_task_struct(task);
+
+	if (!mm) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	err = do_migrate_pages(mm, old, new,
+		capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
+
+	mmput(mm);
+out:
+	NODEMASK_SCRATCH_FREE(scratch);
+
+	return err;
+
+out_put:
+	put_task_struct(task);
+	goto out;
+
+}
+
+
+/* Retrieve NUMA policy */
+SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
+		unsigned long __user *, nmask, unsigned long, maxnode,
+		unsigned long, addr, unsigned long, flags)
+{
+	int err;
+	int uninitialized_var(pval);
+	nodemask_t nodes;
+
+	if (nmask != NULL && maxnode < MAX_NUMNODES)
+		return -EINVAL;
+
+	err = do_get_mempolicy(&pval, &nodes, addr, flags);
+
+	if (err)
+		return err;
+
+	if (policy && put_user(pval, policy))
+		return -EFAULT;
+
+	if (nmask)
+		err = copy_nodes_to_user(nmask, maxnode, &nodes);
+
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+
+COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
+		       compat_ulong_t __user *, nmask,
+		       compat_ulong_t, maxnode,
+		       compat_ulong_t, addr, compat_ulong_t, flags)
+{
+	long err;
+	unsigned long __user *nm = NULL;
+	unsigned long nr_bits, alloc_size;
+	DECLARE_BITMAP(bm, MAX_NUMNODES);
+
+	nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
+	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+
+	if (nmask)
+		nm = compat_alloc_user_space(alloc_size);
+
+	err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
+
+	if (!err && nmask) {
+		unsigned long copy_size;
+		copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
+		err = copy_from_user(bm, nm, copy_size);
+		/* ensure entire bitmap is zeroed */
+		err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
+		err |= compat_put_bitmap(nmask, bm, nr_bits);
+	}
+
+	return err;
+}
+
+COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
+		       compat_ulong_t, maxnode)
+{
+	unsigned long __user *nm = NULL;
+	unsigned long nr_bits, alloc_size;
+	DECLARE_BITMAP(bm, MAX_NUMNODES);
+
+	nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
+	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+
+	if (nmask) {
+		if (compat_get_bitmap(bm, nmask, nr_bits))
+			return -EFAULT;
+		nm = compat_alloc_user_space(alloc_size);
+		if (copy_to_user(nm, bm, alloc_size))
+			return -EFAULT;
+	}
+
+	return sys_set_mempolicy(mode, nm, nr_bits+1);
+}
+
+COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
+		       compat_ulong_t, mode, compat_ulong_t __user *, nmask,
+		       compat_ulong_t, maxnode, compat_ulong_t, flags)
+{
+	unsigned long __user *nm = NULL;
+	unsigned long nr_bits, alloc_size;
+	nodemask_t bm;
+
+	nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
+	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+
+	if (nmask) {
+		if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))
+			return -EFAULT;
+		nm = compat_alloc_user_space(alloc_size);
+		if (copy_to_user(nm, nodes_addr(bm), alloc_size))
+			return -EFAULT;
+	}
+
+	return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
+}
+
+#endif
+
+struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
+						unsigned long addr)
+{
+	struct mempolicy *pol = NULL;
+
+	if (vma) {
+		if (vma->vm_ops && vma->vm_ops->get_policy) {
+			pol = vma->vm_ops->get_policy(vma, addr);
+		} else if (vma->vm_policy) {
+			pol = vma->vm_policy;
+
+			/*
+			 * shmem_alloc_page() passes MPOL_F_SHARED policy with
+			 * a pseudo vma whose vma->vm_ops=NULL. Take a reference
+			 * count on these policies which will be dropped by
+			 * mpol_cond_put() later
+			 */
+			if (mpol_needs_cond_ref(pol))
+				mpol_get(pol);
+		}
+	}
+
+	return pol;
+}
+
+/*
+ * get_vma_policy(@vma, @addr)
+ * @vma: virtual memory area whose policy is sought
+ * @addr: address in @vma for shared policy lookup
+ *
+ * Returns effective policy for a VMA at specified address.
+ * Falls back to current->mempolicy or system default policy, as necessary.
+ * Shared policies [those marked as MPOL_F_SHARED] require an extra reference
+ * count--added by the get_policy() vm_op, as appropriate--to protect against
+ * freeing by another task.  It is the caller's responsibility to free the
+ * extra reference for shared policies.
+ */
+static struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
+						unsigned long addr)
+{
+	struct mempolicy *pol = __get_vma_policy(vma, addr);
+
+	if (!pol)
+		pol = get_task_policy(current);
+
+	return pol;
+}
+
+bool vma_policy_mof(struct vm_area_struct *vma)
+{
+	struct mempolicy *pol;
+
+	if (vma->vm_ops && vma->vm_ops->get_policy) {
+		bool ret = false;
+
+		pol = vma->vm_ops->get_policy(vma, vma->vm_start);
+		if (pol && (pol->flags & MPOL_F_MOF))
+			ret = true;
+		mpol_cond_put(pol);
+
+		return ret;
+	}
+
+	pol = vma->vm_policy;
+	if (!pol)
+		pol = get_task_policy(current);
+
+	return pol->flags & MPOL_F_MOF;
+}
+
+static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
+{
+	enum zone_type dynamic_policy_zone = policy_zone;
+
+	BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);
+
+	/*
+	 * if policy->v.nodes has movable memory only,
+	 * we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
+	 *
+	 * policy->v.nodes is intersect with node_states[N_MEMORY].
+	 * so if the following test faile, it implies
+	 * policy->v.nodes has movable memory only.
+	 */
+	if (!nodes_intersects(policy->v.nodes, node_states[N_HIGH_MEMORY]))
+		dynamic_policy_zone = ZONE_MOVABLE;
+
+	return zone >= dynamic_policy_zone;
+}
+
+/*
+ * Return a nodemask representing a mempolicy for filtering nodes for
+ * page allocation
+ */
+static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
+{
+	/* Lower zones don't get a nodemask applied for MPOL_BIND */
+	if (unlikely(policy->mode == MPOL_BIND) &&
+			apply_policy_zone(policy, gfp_zone(gfp)) &&
+			cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
+		return &policy->v.nodes;
+
+	return NULL;
+}
+
+/* Return a zonelist indicated by gfp for node representing a mempolicy */
+static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
+	int nd)
+{
+	switch (policy->mode) {
+	case MPOL_PREFERRED:
+		if (!(policy->flags & MPOL_F_LOCAL))
+			nd = policy->v.preferred_node;
+		break;
+	case MPOL_BIND:
+		/*
+		 * Normally, MPOL_BIND allocations are node-local within the
+		 * allowed nodemask.  However, if __GFP_THISNODE is set and the
+		 * current node isn't part of the mask, we use the zonelist for
+		 * the first node in the mask instead.
+		 */
+		if (unlikely(gfp & __GFP_THISNODE) &&
+				unlikely(!node_isset(nd, policy->v.nodes)))
+			nd = first_node(policy->v.nodes);
+		break;
+	default:
+		BUG();
+	}
+	return node_zonelist(nd, gfp);
+}
+
+/* Do dynamic interleaving for a process */
+static unsigned interleave_nodes(struct mempolicy *policy)
+{
+	unsigned nid, next;
+	struct task_struct *me = current;
+
+	nid = me->il_next;
+	next = next_node(nid, policy->v.nodes);
+	if (next >= MAX_NUMNODES)
+		next = first_node(policy->v.nodes);
+	if (next < MAX_NUMNODES)
+		me->il_next = next;
+	return nid;
+}
+
+/*
+ * Depending on the memory policy provide a node from which to allocate the
+ * next slab entry.
+ */
+unsigned int mempolicy_slab_node(void)
+{
+	struct mempolicy *policy;
+	int node = numa_mem_id();
+
+	if (in_interrupt())
+		return node;
+
+	policy = current->mempolicy;
+	if (!policy || policy->flags & MPOL_F_LOCAL)
+		return node;
+
+	switch (policy->mode) {
+	case MPOL_PREFERRED:
+		/*
+		 * handled MPOL_F_LOCAL above
+		 */
+		return policy->v.preferred_node;
+
+	case MPOL_INTERLEAVE:
+		return interleave_nodes(policy);
+
+	case MPOL_BIND: {
+		/*
+		 * Follow bind policy behavior and start allocation at the
+		 * first node.
+		 */
+		struct zonelist *zonelist;
+		struct zone *zone;
+		enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
+		zonelist = &NODE_DATA(node)->node_zonelists[0];
+		(void)first_zones_zonelist(zonelist, highest_zoneidx,
+							&policy->v.nodes,
+							&zone);
+		return zone ? zone->node : node;
+	}
+
+	default:
+		BUG();
+	}
+}
+
+/* Do static interleaving for a VMA with known offset. */
+static unsigned offset_il_node(struct mempolicy *pol,
+		struct vm_area_struct *vma, unsigned long off)
+{
+	unsigned nnodes = nodes_weight(pol->v.nodes);
+	unsigned target;
+	int c;
+	int nid = NUMA_NO_NODE;
+
+	if (!nnodes)
+		return numa_node_id();
+	target = (unsigned int)off % nnodes;
+	c = 0;
+	do {
+		nid = next_node(nid, pol->v.nodes);
+		c++;
+	} while (c <= target);
+	return nid;
+}
+
+/* Determine a node number for interleave */
+static inline unsigned interleave_nid(struct mempolicy *pol,
+		 struct vm_area_struct *vma, unsigned long addr, int shift)
+{
+	if (vma) {
+		unsigned long off;
+
+		/*
+		 * for small pages, there is no difference between
+		 * shift and PAGE_SHIFT, so the bit-shift is safe.
+		 * for huge pages, since vm_pgoff is in units of small
+		 * pages, we need to shift off the always 0 bits to get
+		 * a useful offset.
+		 */
+		BUG_ON(shift < PAGE_SHIFT);
+		off = vma->vm_pgoff >> (shift - PAGE_SHIFT);
+		off += (addr - vma->vm_start) >> shift;
+		return offset_il_node(pol, vma, off);
+	} else
+		return interleave_nodes(pol);
+}
+
+/*
+ * Return the bit number of a random bit set in the nodemask.
+ * (returns NUMA_NO_NODE if nodemask is empty)
+ */
+int node_random(const nodemask_t *maskp)
+{
+	int w, bit = NUMA_NO_NODE;
+
+	w = nodes_weight(*maskp);
+	if (w)
+		bit = bitmap_ord_to_pos(maskp->bits,
+			get_random_int() % w, MAX_NUMNODES);
+	return bit;
+}
+
+#ifdef CONFIG_HUGETLBFS
+/*
+ * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
+ * @vma: virtual memory area whose policy is sought
+ * @addr: address in @vma for shared policy lookup and interleave policy
+ * @gfp_flags: for requested zone
+ * @mpol: pointer to mempolicy pointer for reference counted mempolicy
+ * @nodemask: pointer to nodemask pointer for MPOL_BIND nodemask
+ *
+ * Returns a zonelist suitable for a huge page allocation and a pointer
+ * to the struct mempolicy for conditional unref after allocation.
+ * If the effective policy is 'BIND, returns a pointer to the mempolicy's
+ * @nodemask for filtering the zonelist.
+ *
+ * Must be protected by read_mems_allowed_begin()
+ */
+struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
+				gfp_t gfp_flags, struct mempolicy **mpol,
+				nodemask_t **nodemask)
+{
+	struct zonelist *zl;
+
+	*mpol = get_vma_policy(vma, addr);
+	*nodemask = NULL;	/* assume !MPOL_BIND */
+
+	if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
+		zl = node_zonelist(interleave_nid(*mpol, vma, addr,
+				huge_page_shift(hstate_vma(vma))), gfp_flags);
+	} else {
+		zl = policy_zonelist(gfp_flags, *mpol, numa_node_id());
+		if ((*mpol)->mode == MPOL_BIND)
+			*nodemask = &(*mpol)->v.nodes;
+	}
+	return zl;
+}
+
+/*
+ * init_nodemask_of_mempolicy
+ *
+ * If the current task's mempolicy is "default" [NULL], return 'false'
+ * to indicate default policy.  Otherwise, extract the policy nodemask
+ * for 'bind' or 'interleave' policy into the argument nodemask, or
+ * initialize the argument nodemask to contain the single node for
+ * 'preferred' or 'local' policy and return 'true' to indicate presence
+ * of non-default mempolicy.
+ *
+ * We don't bother with reference counting the mempolicy [mpol_get/put]
+ * because the current task is examining it's own mempolicy and a task's
+ * mempolicy is only ever changed by the task itself.
+ *
+ * N.B., it is the caller's responsibility to free a returned nodemask.
+ */
+bool init_nodemask_of_mempolicy(nodemask_t *mask)
+{
+	struct mempolicy *mempolicy;
+	int nid;
+
+	if (!(mask && current->mempolicy))
+		return false;
+
+	task_lock(current);
+	mempolicy = current->mempolicy;
+	switch (mempolicy->mode) {
+	case MPOL_PREFERRED:
+		if (mempolicy->flags & MPOL_F_LOCAL)
+			nid = numa_node_id();
+		else
+			nid = mempolicy->v.preferred_node;
+		init_nodemask_of_node(mask, nid);
+		break;
+
+	case MPOL_BIND:
+		/* Fall through */
+	case MPOL_INTERLEAVE:
+		*mask =  mempolicy->v.nodes;
+		break;
+
+	default:
+		BUG();
+	}
+	task_unlock(current);
+
+	return true;
+}
+#endif
+
+/*
+ * mempolicy_nodemask_intersects
+ *
+ * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default
+ * policy.  Otherwise, check for intersection between mask and the policy
+ * nodemask for 'bind' or 'interleave' policy.  For 'perferred' or 'local'
+ * policy, always return true since it may allocate elsewhere on fallback.
+ *
+ * Takes task_lock(tsk) to prevent freeing of its mempolicy.
+ */
+bool mempolicy_nodemask_intersects(struct task_struct *tsk,
+					const nodemask_t *mask)
+{
+	struct mempolicy *mempolicy;
+	bool ret = true;
+
+	if (!mask)
+		return ret;
+	task_lock(tsk);
+	mempolicy = tsk->mempolicy;
+	if (!mempolicy)
+		goto out;
+
+	switch (mempolicy->mode) {
+	case MPOL_PREFERRED:
+		/*
+		 * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to
+		 * allocate from, they may fallback to other nodes when oom.
+		 * Thus, it's possible for tsk to have allocated memory from
+		 * nodes in mask.
+		 */
+		break;
+	case MPOL_BIND:
+	case MPOL_INTERLEAVE:
+		ret = nodes_intersects(mempolicy->v.nodes, *mask);
+		break;
+	default:
+		BUG();
+	}
+out:
+	task_unlock(tsk);
+	return ret;
+}
+
+/* Allocate a page in interleaved policy.
+   Own path because it needs to do special accounting. */
+static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
+					unsigned nid)
+{
+	struct zonelist *zl;
+	struct page *page;
+
+	zl = node_zonelist(nid, gfp);
+	page = __alloc_pages(gfp, order, zl);
+	if (page && page_zone(page) == zonelist_zone(&zl->_zonerefs[0]))
+		inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
+	return page;
+}
+
+/**
+ * 	alloc_pages_vma	- Allocate a page for a VMA.
+ *
+ * 	@gfp:
+ *      %GFP_USER    user allocation.
+ *      %GFP_KERNEL  kernel allocations,
+ *      %GFP_HIGHMEM highmem/user allocations,
+ *      %GFP_FS      allocation should not call back into a file system.
+ *      %GFP_ATOMIC  don't sleep.
+ *
+ *	@order:Order of the GFP allocation.
+ * 	@vma:  Pointer to VMA or NULL if not available.
+ *	@addr: Virtual Address of the allocation. Must be inside the VMA.
+ *	@node: Which node to prefer for allocation (modulo policy).
+ *	@hugepage: for hugepages try only the preferred node if possible
+ *
+ * 	This function allocates a page from the kernel page pool and applies
+ *	a NUMA policy associated with the VMA or the current process.
+ *	When VMA is not NULL caller must hold down_read on the mmap_sem of the
+ *	mm_struct of the VMA to prevent it from going away. Should be used for
+ *	all allocations for pages that will be mapped into user space. Returns
+ *	NULL when no page can be allocated.
+ */
+struct page *
+alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
+		unsigned long addr, int node, bool hugepage)
+{
+	struct mempolicy *pol;
+	struct page *page;
+	unsigned int cpuset_mems_cookie;
+	struct zonelist *zl;
+	nodemask_t *nmask;
+
+retry_cpuset:
+	pol = get_vma_policy(vma, addr);
+	cpuset_mems_cookie = read_mems_allowed_begin();
+
+	if (pol->mode == MPOL_INTERLEAVE) {
+		unsigned nid;
+
+		nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
+		mpol_cond_put(pol);
+		page = alloc_page_interleave(gfp, order, nid);
+		goto out;
+	}
+
+	if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
+		int hpage_node = node;
+
+		/*
+		 * For hugepage allocation and non-interleave policy which
+		 * allows the current node (or other explicitly preferred
+		 * node) we only try to allocate from the current/preferred
+		 * node and don't fall back to other nodes, as the cost of
+		 * remote accesses would likely offset THP benefits.
+		 *
+		 * If the policy is interleave, or does not allow the current
+		 * node in its nodemask, we allocate the standard way.
+		 */
+		if (pol->mode == MPOL_PREFERRED &&
+						!(pol->flags & MPOL_F_LOCAL))
+			hpage_node = pol->v.preferred_node;
+
+		nmask = policy_nodemask(gfp, pol);
+		if (!nmask || node_isset(hpage_node, *nmask)) {
+			mpol_cond_put(pol);
+			page = __alloc_pages_node(hpage_node,
+						gfp | __GFP_THISNODE, order);
+			goto out;
+		}
+	}
+
+	nmask = policy_nodemask(gfp, pol);
+	zl = policy_zonelist(gfp, pol, node);
+	page = __alloc_pages_nodemask(gfp, order, zl, nmask);
+	mpol_cond_put(pol);
+out:
+	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
+		goto retry_cpuset;
+	return page;
+}
+
+/**
+ * 	alloc_pages_current - Allocate pages.
+ *
+ *	@gfp:
+ *		%GFP_USER   user allocation,
+ *      	%GFP_KERNEL kernel allocation,
+ *      	%GFP_HIGHMEM highmem allocation,
+ *      	%GFP_FS     don't call back into a file system.
+ *      	%GFP_ATOMIC don't sleep.
+ *	@order: Power of two of allocation size in pages. 0 is a single page.
+ *
+ *	Allocate a page from the kernel page pool.  When not in
+ *	interrupt context and apply the current process NUMA policy.
+ *	Returns NULL when no page can be allocated.
+ *
+ *	Don't call cpuset_update_task_memory_state() unless
+ *	1) it's ok to take cpuset_sem (can WAIT), and
+ *	2) allocating for current task (not interrupt).
+ */
+struct page *alloc_pages_current(gfp_t gfp, unsigned order)
+{
+	struct mempolicy *pol = &default_policy;
+	struct page *page;
+	unsigned int cpuset_mems_cookie;
+
+	if (!in_interrupt() && !(gfp & __GFP_THISNODE))
+		pol = get_task_policy(current);
+
+retry_cpuset:
+	cpuset_mems_cookie = read_mems_allowed_begin();
+
+	/*
+	 * No reference counting needed for current->mempolicy
+	 * nor system default_policy
+	 */
+	if (pol->mode == MPOL_INTERLEAVE)
+		page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
+	else
+		page = __alloc_pages_nodemask(gfp, order,
+				policy_zonelist(gfp, pol, numa_node_id()),
+				policy_nodemask(gfp, pol));
+
+	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
+		goto retry_cpuset;
+
+	return page;
+}
+EXPORT_SYMBOL(alloc_pages_current);
+
+int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
+{
+	struct mempolicy *pol = mpol_dup(vma_policy(src));
+
+	if (IS_ERR(pol))
+		return PTR_ERR(pol);
+	dst->vm_policy = pol;
+	return 0;
+}
+
+/*
+ * If mpol_dup() sees current->cpuset == cpuset_being_rebound, then it
+ * rebinds the mempolicy its copying by calling mpol_rebind_policy()
+ * with the mems_allowed returned by cpuset_mems_allowed().  This
+ * keeps mempolicies cpuset relative after its cpuset moves.  See
+ * further kernel/cpuset.c update_nodemask().
+ *
+ * current's mempolicy may be rebinded by the other task(the task that changes
+ * cpuset's mems), so we needn't do rebind work for current task.
+ */
+
+/* Slow path of a mempolicy duplicate */
+struct mempolicy *__mpol_dup(struct mempolicy *old)
+{
+	struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	/* task's mempolicy is protected by alloc_lock */
+	if (old == current->mempolicy) {
+		task_lock(current);
+		*new = *old;
+		task_unlock(current);
+	} else
+		*new = *old;
+
+	if (current_cpuset_is_being_rebound()) {
+		nodemask_t mems = cpuset_mems_allowed(current);
+		if (new->flags & MPOL_F_REBINDING)
+			mpol_rebind_policy(new, &mems, MPOL_REBIND_STEP2);
+		else
+			mpol_rebind_policy(new, &mems, MPOL_REBIND_ONCE);
+	}
+	atomic_set(&new->refcnt, 1);
+	return new;
+}
+
+/* Slow path of a mempolicy comparison */
+bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
+{
+	if (!a || !b)
+		return false;
+	if (a->mode != b->mode)
+		return false;
+	if (a->flags != b->flags)
+		return false;
+	if (mpol_store_user_nodemask(a))
+		if (!nodes_equal(a->w.user_nodemask, b->w.user_nodemask))
+			return false;
+
+	switch (a->mode) {
+	case MPOL_BIND:
+		/* Fall through */
+	case MPOL_INTERLEAVE:
+		return !!nodes_equal(a->v.nodes, b->v.nodes);
+	case MPOL_PREFERRED:
+		return a->v.preferred_node == b->v.preferred_node;
+	default:
+		BUG();
+		return false;
+	}
+}
+
+/*
+ * Shared memory backing store policy support.
+ *
+ * Remember policies even when nobody has shared memory mapped.
+ * The policies are kept in Red-Black tree linked from the inode.
+ * They are protected by the sp->lock spinlock, which should be held
+ * for any accesses to the tree.
+ */
+
+/* lookup first element intersecting start-end */
+/* Caller holds sp->lock */
+static struct sp_node *
+sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
+{
+	struct rb_node *n = sp->root.rb_node;
+
+	while (n) {
+		struct sp_node *p = rb_entry(n, struct sp_node, nd);
+
+		if (start >= p->end)
+			n = n->rb_right;
+		else if (end <= p->start)
+			n = n->rb_left;
+		else
+			break;
+	}
+	if (!n)
+		return NULL;
+	for (;;) {
+		struct sp_node *w = NULL;
+		struct rb_node *prev = rb_prev(n);
+		if (!prev)
+			break;
+		w = rb_entry(prev, struct sp_node, nd);
+		if (w->end <= start)
+			break;
+		n = prev;
+	}
+	return rb_entry(n, struct sp_node, nd);
+}
+
+/* Insert a new shared policy into the list. */
+/* Caller holds sp->lock */
+static void sp_insert(struct shared_policy *sp, struct sp_node *new)
+{
+	struct rb_node **p = &sp->root.rb_node;
+	struct rb_node *parent = NULL;
+	struct sp_node *nd;
+
+	while (*p) {
+		parent = *p;
+		nd = rb_entry(parent, struct sp_node, nd);
+		if (new->start < nd->start)
+			p = &(*p)->rb_left;
+		else if (new->end > nd->end)
+			p = &(*p)->rb_right;
+		else
+			BUG();
+	}
+	rb_link_node(&new->nd, parent, p);
+	rb_insert_color(&new->nd, &sp->root);
+	pr_debug("inserting %lx-%lx: %d\n", new->start, new->end,
+		 new->policy ? new->policy->mode : 0);
+}
+
+/* Find shared policy intersecting idx */
+struct mempolicy *
+mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
+{
+	struct mempolicy *pol = NULL;
+	struct sp_node *sn;
+
+	if (!sp->root.rb_node)
+		return NULL;
+	spin_lock(&sp->lock);
+	sn = sp_lookup(sp, idx, idx+1);
+	if (sn) {
+		mpol_get(sn->policy);
+		pol = sn->policy;
+	}
+	spin_unlock(&sp->lock);
+	return pol;
+}
+
+static void sp_free(struct sp_node *n)
+{
+	mpol_put(n->policy);
+	kmem_cache_free(sn_cache, n);
+}
+
+/**
+ * mpol_misplaced - check whether current page node is valid in policy
+ *
+ * @page: page to be checked
+ * @vma: vm area where page mapped
+ * @addr: virtual address where page mapped
+ *
+ * Lookup current policy node id for vma,addr and "compare to" page's
+ * node id.
+ *
+ * Returns:
+ *	-1	- not misplaced, page is in the right node
+ *	node	- node id where the page should be
+ *
+ * Policy determination "mimics" alloc_page_vma().
+ * Called from fault path where we know the vma and faulting address.
+ */
+int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long addr)
+{
+	struct mempolicy *pol;
+	struct zone *zone;
+	int curnid = page_to_nid(page);
+	unsigned long pgoff;
+	int thiscpu = raw_smp_processor_id();
+	int thisnid = cpu_to_node(thiscpu);
+	int polnid = -1;
+	int ret = -1;
+
+	BUG_ON(!vma);
+
+	pol = get_vma_policy(vma, addr);
+	if (!(pol->flags & MPOL_F_MOF))
+		goto out;
+
+	switch (pol->mode) {
+	case MPOL_INTERLEAVE:
+		BUG_ON(addr >= vma->vm_end);
+		BUG_ON(addr < vma->vm_start);
+
+		pgoff = vma->vm_pgoff;
+		pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
+		polnid = offset_il_node(pol, vma, pgoff);
+		break;
+
+	case MPOL_PREFERRED:
+		if (pol->flags & MPOL_F_LOCAL)
+			polnid = numa_node_id();
+		else
+			polnid = pol->v.preferred_node;
+		break;
+
+	case MPOL_BIND:
+		/*
+		 * allows binding to multiple nodes.
+		 * use current page if in policy nodemask,
+		 * else select nearest allowed node, if any.
+		 * If no allowed nodes, use current [!misplaced].
+		 */
+		if (node_isset(curnid, pol->v.nodes))
+			goto out;
+		(void)first_zones_zonelist(
+				node_zonelist(numa_node_id(), GFP_HIGHUSER),
+				gfp_zone(GFP_HIGHUSER),
+				&pol->v.nodes, &zone);
+		polnid = zone->node;
+		break;
+
+	default:
+		BUG();
+	}
+
+	/* Migrate the page towards the node whose CPU is referencing it */
+	if (pol->flags & MPOL_F_MORON) {
+		polnid = thisnid;
+
+		if (!should_numa_migrate_memory(current, page, curnid, thiscpu))
+			goto out;
+	}
+
+	if (curnid != polnid)
+		ret = polnid;
+out:
+	mpol_cond_put(pol);
+
+	return ret;
+}
+
+static void sp_delete(struct shared_policy *sp, struct sp_node *n)
+{
+	pr_debug("deleting %lx-l%lx\n", n->start, n->end);
+	rb_erase(&n->nd, &sp->root);
+	sp_free(n);
+}
+
+static void sp_node_init(struct sp_node *node, unsigned long start,
+			unsigned long end, struct mempolicy *pol)
+{
+	node->start = start;
+	node->end = end;
+	node->policy = pol;
+}
+
+static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
+				struct mempolicy *pol)
+{
+	struct sp_node *n;
+	struct mempolicy *newpol;
+
+	n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
+	if (!n)
+		return NULL;
+
+	newpol = mpol_dup(pol);
+	if (IS_ERR(newpol)) {
+		kmem_cache_free(sn_cache, n);
+		return NULL;
+	}
+	newpol->flags |= MPOL_F_SHARED;
+	sp_node_init(n, start, end, newpol);
+
+	return n;
+}
+
+/* Replace a policy range. */
+static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
+				 unsigned long end, struct sp_node *new)
+{
+	struct sp_node *n;
+	struct sp_node *n_new = NULL;
+	struct mempolicy *mpol_new = NULL;
+	int ret = 0;
+
+restart:
+	spin_lock(&sp->lock);
+	n = sp_lookup(sp, start, end);
+	/* Take care of old policies in the same range. */
+	while (n && n->start < end) {
+		struct rb_node *next = rb_next(&n->nd);
+		if (n->start >= start) {
+			if (n->end <= end)
+				sp_delete(sp, n);
+			else
+				n->start = end;
+		} else {
+			/* Old policy spanning whole new range. */
+			if (n->end > end) {
+				if (!n_new)
+					goto alloc_new;
+
+				*mpol_new = *n->policy;
+				atomic_set(&mpol_new->refcnt, 1);
+				sp_node_init(n_new, end, n->end, mpol_new);
+				n->end = start;
+				sp_insert(sp, n_new);
+				n_new = NULL;
+				mpol_new = NULL;
+				break;
+			} else
+				n->end = start;
+		}
+		if (!next)
+			break;
+		n = rb_entry(next, struct sp_node, nd);
+	}
+	if (new)
+		sp_insert(sp, new);
+	spin_unlock(&sp->lock);
+	ret = 0;
+
+err_out:
+	if (mpol_new)
+		mpol_put(mpol_new);
+	if (n_new)
+		kmem_cache_free(sn_cache, n_new);
+
+	return ret;
+
+alloc_new:
+	spin_unlock(&sp->lock);
+	ret = -ENOMEM;
+	n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
+	if (!n_new)
+		goto err_out;
+	mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+	if (!mpol_new)
+		goto err_out;
+	goto restart;
+}
+
+/**
+ * mpol_shared_policy_init - initialize shared policy for inode
+ * @sp: pointer to inode shared policy
+ * @mpol:  struct mempolicy to install
+ *
+ * Install non-NULL @mpol in inode's shared policy rb-tree.
+ * On entry, the current task has a reference on a non-NULL @mpol.
+ * This must be released on exit.
+ * This is called at get_inode() calls and we can use GFP_KERNEL.
+ */
+void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
+{
+	int ret;
+
+	sp->root = RB_ROOT;		/* empty tree == default mempolicy */
+	spin_lock_init(&sp->lock);
+
+	if (mpol) {
+		struct vm_area_struct pvma;
+		struct mempolicy *new;
+		NODEMASK_SCRATCH(scratch);
+
+		if (!scratch)
+			goto put_mpol;
+		/* contextualize the tmpfs mount point mempolicy */
+		new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
+		if (IS_ERR(new))
+			goto free_scratch; /* no valid nodemask intersection */
+
+		task_lock(current);
+		ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
+		task_unlock(current);
+		if (ret)
+			goto put_new;
+
+		/* Create pseudo-vma that contains just the policy */
+		memset(&pvma, 0, sizeof(struct vm_area_struct));
+		pvma.vm_end = TASK_SIZE;	/* policy covers entire file */
+		mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
+
+put_new:
+		mpol_put(new);			/* drop initial ref */
+free_scratch:
+		NODEMASK_SCRATCH_FREE(scratch);
+put_mpol:
+		mpol_put(mpol);	/* drop our incoming ref on sb mpol */
+	}
+}
+
+int mpol_set_shared_policy(struct shared_policy *info,
+			struct vm_area_struct *vma, struct mempolicy *npol)
+{
+	int err;
+	struct sp_node *new = NULL;
+	unsigned long sz = vma_pages(vma);
+
+	pr_debug("set_shared_policy %lx sz %lu %d %d %lx\n",
+		 vma->vm_pgoff,
+		 sz, npol ? npol->mode : -1,
+		 npol ? npol->flags : -1,
+		 npol ? nodes_addr(npol->v.nodes)[0] : NUMA_NO_NODE);
+
+	if (npol) {
+		new = sp_alloc(vma->vm_pgoff, vma->vm_pgoff + sz, npol);
+		if (!new)
+			return -ENOMEM;
+	}
+	err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
+	if (err && new)
+		sp_free(new);
+	return err;
+}
+
+/* Free a backing policy store on inode delete. */
+void mpol_free_shared_policy(struct shared_policy *p)
+{
+	struct sp_node *n;
+	struct rb_node *next;
+
+	if (!p->root.rb_node)
+		return;
+	spin_lock(&p->lock);
+	next = rb_first(&p->root);
+	while (next) {
+		n = rb_entry(next, struct sp_node, nd);
+		next = rb_next(&n->nd);
+		sp_delete(p, n);
+	}
+	spin_unlock(&p->lock);
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+static int __initdata numabalancing_override;
+
+static void __init check_numabalancing_enable(void)
+{
+	bool numabalancing_default = false;
+
+	if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
+		numabalancing_default = true;
+
+	/* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
+	if (numabalancing_override)
+		set_numabalancing_state(numabalancing_override == 1);
+
+	if (num_online_nodes() > 1 && !numabalancing_override) {
+		pr_info("%s automatic NUMA balancing. "
+			"Configure with numa_balancing= or the "
+			"kernel.numa_balancing sysctl",
+			numabalancing_default ? "Enabling" : "Disabling");
+		set_numabalancing_state(numabalancing_default);
+	}
+}
+
+static int __init setup_numabalancing(char *str)
+{
+	int ret = 0;
+	if (!str)
+		goto out;
+
+	if (!strcmp(str, "enable")) {
+		numabalancing_override = 1;
+		ret = 1;
+	} else if (!strcmp(str, "disable")) {
+		numabalancing_override = -1;
+		ret = 1;
+	}
+out:
+	if (!ret)
+		pr_warn("Unable to parse numa_balancing=\n");
+
+	return ret;
+}
+__setup("numa_balancing=", setup_numabalancing);
+#else
+static inline void __init check_numabalancing_enable(void)
+{
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+/* assumes fs == KERNEL_DS */
+void __init numa_policy_init(void)
+{
+	nodemask_t interleave_nodes;
+	unsigned long largest = 0;
+	int nid, prefer = 0;
+
+	policy_cache = kmem_cache_create("numa_policy",
+					 sizeof(struct mempolicy),
+					 0, SLAB_PANIC, NULL);
+
+	sn_cache = kmem_cache_create("shared_policy_node",
+				     sizeof(struct sp_node),
+				     0, SLAB_PANIC, NULL);
+
+	for_each_node(nid) {
+		preferred_node_policy[nid] = (struct mempolicy) {
+			.refcnt = ATOMIC_INIT(1),
+			.mode = MPOL_PREFERRED,
+			.flags = MPOL_F_MOF | MPOL_F_MORON,
+			.v = { .preferred_node = nid, },
+		};
+	}
+
+	/*
+	 * Set interleaving policy for system init. Interleaving is only
+	 * enabled across suitably sized nodes (default is >= 16MB), or
+	 * fall back to the largest node if they're all smaller.
+	 */
+	nodes_clear(interleave_nodes);
+	for_each_node_state(nid, N_MEMORY) {
+		unsigned long total_pages = node_present_pages(nid);
+
+		/* Preserve the largest node */
+		if (largest < total_pages) {
+			largest = total_pages;
+			prefer = nid;
+		}
+
+		/* Interleave this node? */
+		if ((total_pages << PAGE_SHIFT) >= (16 << 20))
+			node_set(nid, interleave_nodes);
+	}
+
+	/* All too small, use the largest */
+	if (unlikely(nodes_empty(interleave_nodes)))
+		node_set(prefer, interleave_nodes);
+
+	if (do_set_mempolicy(MPOL_INTERLEAVE, 0, &interleave_nodes))
+		pr_err("%s: interleaving failed\n", __func__);
+
+	check_numabalancing_enable();
+}
+
+/* Reset policy of current process to default */
+void numa_default_policy(void)
+{
+	do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
+}
+
+/*
+ * Parse and format mempolicy from/to strings
+ */
+
+/*
+ * "local" is implemented internally by MPOL_PREFERRED with MPOL_F_LOCAL flag.
+ */
+static const char * const policy_modes[] =
+{
+	[MPOL_DEFAULT]    = "default",
+	[MPOL_PREFERRED]  = "prefer",
+	[MPOL_BIND]       = "bind",
+	[MPOL_INTERLEAVE] = "interleave",
+	[MPOL_LOCAL]      = "local",
+};
+
+
+#ifdef CONFIG_TMPFS
+/**
+ * mpol_parse_str - parse string to mempolicy, for tmpfs mpol mount option.
+ * @str:  string containing mempolicy to parse
+ * @mpol:  pointer to struct mempolicy pointer, returned on success.
+ *
+ * Format of input:
+ *	<mode>[=<flags>][:<nodelist>]
+ *
+ * On success, returns 0, else 1
+ */
+int mpol_parse_str(char *str, struct mempolicy **mpol)
+{
+	struct mempolicy *new = NULL;
+	unsigned short mode;
+	unsigned short mode_flags;
+	nodemask_t nodes;
+	char *nodelist = strchr(str, ':');
+	char *flags = strchr(str, '=');
+	int err = 1;
+
+	if (nodelist) {
+		/* NUL-terminate mode or flags string */
+		*nodelist++ = '\0';
+		if (nodelist_parse(nodelist, nodes))
+			goto out;
+		if (!nodes_subset(nodes, node_states[N_MEMORY]))
+			goto out;
+	} else
+		nodes_clear(nodes);
+
+	if (flags)
+		*flags++ = '\0';	/* terminate mode string */
+
+	for (mode = 0; mode < MPOL_MAX; mode++) {
+		if (!strcmp(str, policy_modes[mode])) {
+			break;
+		}
+	}
+	if (mode >= MPOL_MAX)
+		goto out;
+
+	switch (mode) {
+	case MPOL_PREFERRED:
+		/*
+		 * Insist on a nodelist of one node only
+		 */
+		if (nodelist) {
+			char *rest = nodelist;
+			while (isdigit(*rest))
+				rest++;
+			if (*rest)
+				goto out;
+		}
+		break;
+	case MPOL_INTERLEAVE:
+		/*
+		 * Default to online nodes with memory if no nodelist
+		 */
+		if (!nodelist)
+			nodes = node_states[N_MEMORY];
+		break;
+	case MPOL_LOCAL:
+		/*
+		 * Don't allow a nodelist;  mpol_new() checks flags
+		 */
+		if (nodelist)
+			goto out;
+		mode = MPOL_PREFERRED;
+		break;
+	case MPOL_DEFAULT:
+		/*
+		 * Insist on a empty nodelist
+		 */
+		if (!nodelist)
+			err = 0;
+		goto out;
+	case MPOL_BIND:
+		/*
+		 * Insist on a nodelist
+		 */
+		if (!nodelist)
+			goto out;
+	}
+
+	mode_flags = 0;
+	if (flags) {
+		/*
+		 * Currently, we only support two mutually exclusive
+		 * mode flags.
+		 */
+		if (!strcmp(flags, "static"))
+			mode_flags |= MPOL_F_STATIC_NODES;
+		else if (!strcmp(flags, "relative"))
+			mode_flags |= MPOL_F_RELATIVE_NODES;
+		else
+			goto out;
+	}
+
+	new = mpol_new(mode, mode_flags, &nodes);
+	if (IS_ERR(new))
+		goto out;
+
+	/*
+	 * Save nodes for mpol_to_str() to show the tmpfs mount options
+	 * for /proc/mounts, /proc/pid/mounts and /proc/pid/mountinfo.
+	 */
+	if (mode != MPOL_PREFERRED)
+		new->v.nodes = nodes;
+	else if (nodelist)
+		new->v.preferred_node = first_node(nodes);
+	else
+		new->flags |= MPOL_F_LOCAL;
+
+	/*
+	 * Save nodes for contextualization: this will be used to "clone"
+	 * the mempolicy in a specific context [cpuset] at a later time.
+	 */
+	new->w.user_nodemask = nodes;
+
+	err = 0;
+
+out:
+	/* Restore string for error message */
+	if (nodelist)
+		*--nodelist = ':';
+	if (flags)
+		*--flags = '=';
+	if (!err)
+		*mpol = new;
+	return err;
+}
+#endif /* CONFIG_TMPFS */
+
+/**
+ * mpol_to_str - format a mempolicy structure for printing
+ * @buffer:  to contain formatted mempolicy string
+ * @maxlen:  length of @buffer
+ * @pol:  pointer to mempolicy to be formatted
+ *
+ * Convert @pol into a string.  If @buffer is too short, truncate the string.
+ * Recommend a @maxlen of at least 32 for the longest mode, "interleave", the
+ * longest flag, "relative", and to display at least a few node ids.
+ */
+void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
+{
+	char *p = buffer;
+	nodemask_t nodes = NODE_MASK_NONE;
+	unsigned short mode = MPOL_DEFAULT;
+	unsigned short flags = 0;
+
+	if (pol && pol != &default_policy && !(pol->flags & MPOL_F_MORON)) {
+		mode = pol->mode;
+		flags = pol->flags;
+	}
+
+	switch (mode) {
+	case MPOL_DEFAULT:
+		break;
+	case MPOL_PREFERRED:
+		if (flags & MPOL_F_LOCAL)
+			mode = MPOL_LOCAL;
+		else
+			node_set(pol->v.preferred_node, nodes);
+		break;
+	case MPOL_BIND:
+	case MPOL_INTERLEAVE:
+		nodes = pol->v.nodes;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		snprintf(p, maxlen, "unknown");
+		return;
+	}
+
+	p += snprintf(p, maxlen, "%s", policy_modes[mode]);
+
+	if (flags & MPOL_MODE_FLAGS) {
+		p += snprintf(p, buffer + maxlen - p, "=");
+
+		/*
+		 * Currently, the only defined flags are mutually exclusive
+		 */
+		if (flags & MPOL_F_STATIC_NODES)
+			p += snprintf(p, buffer + maxlen - p, "static");
+		else if (flags & MPOL_F_RELATIVE_NODES)
+			p += snprintf(p, buffer + maxlen - p, "relative");
+	}
+
+	if (!nodes_empty(nodes))
+		p += scnprintf(p, buffer + maxlen - p, ":%*pbl",
+			       nodemask_pr_args(&nodes));
+}
diff --git a/mm/mempool.c b/mm/mempool.c
new file mode 100644
index 0000000..7924f4f
--- /dev/null
+++ b/mm/mempool.c
@@ -0,0 +1,497 @@
+/*
+ *  linux/mm/mempool.c
+ *
+ *  memory buffer pool support. Such pools are mostly used
+ *  for guaranteed, deadlock-free memory allocations during
+ *  extreme VM load.
+ *
+ *  started by Ingo Molnar, Copyright (C) 2001
+ *  debugging by David Rientjes, Copyright (C) 2015
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/kasan.h>
+#include <linux/kmemleak.h>
+#include <linux/export.h>
+#include <linux/mempool.h>
+#include <linux/blkdev.h>
+#include <linux/writeback.h>
+#include "slab.h"
+
+#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
+static void poison_error(mempool_t *pool, void *element, size_t size,
+			 size_t byte)
+{
+	const int nr = pool->curr_nr;
+	const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0);
+	const int end = min_t(int, byte + (BITS_PER_LONG / 8), size);
+	int i;
+
+	pr_err("BUG: mempool element poison mismatch\n");
+	pr_err("Mempool %p size %zu\n", pool, size);
+	pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : "");
+	for (i = start; i < end; i++)
+		pr_cont("%x ", *(u8 *)(element + i));
+	pr_cont("%s\n", end < size ? "..." : "");
+	dump_stack();
+}
+
+static void __check_element(mempool_t *pool, void *element, size_t size)
+{
+	u8 *obj = element;
+	size_t i;
+
+	for (i = 0; i < size; i++) {
+		u8 exp = (i < size - 1) ? POISON_FREE : POISON_END;
+
+		if (obj[i] != exp) {
+			poison_error(pool, element, size, i);
+			return;
+		}
+	}
+	memset(obj, POISON_INUSE, size);
+}
+
+static void check_element(mempool_t *pool, void *element)
+{
+	/* Mempools backed by slab allocator */
+	if (pool->free == mempool_free_slab || pool->free == mempool_kfree)
+		__check_element(pool, element, ksize(element));
+
+	/* Mempools backed by page allocator */
+	if (pool->free == mempool_free_pages) {
+		int order = (int)(long)pool->pool_data;
+		void *addr = kmap_atomic((struct page *)element);
+
+		__check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
+		kunmap_atomic(addr);
+	}
+}
+
+static void __poison_element(void *element, size_t size)
+{
+	u8 *obj = element;
+
+	memset(obj, POISON_FREE, size - 1);
+	obj[size - 1] = POISON_END;
+}
+
+static void poison_element(mempool_t *pool, void *element)
+{
+	/* Mempools backed by slab allocator */
+	if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
+		__poison_element(element, ksize(element));
+
+	/* Mempools backed by page allocator */
+	if (pool->alloc == mempool_alloc_pages) {
+		int order = (int)(long)pool->pool_data;
+		void *addr = kmap_atomic((struct page *)element);
+
+		__poison_element(addr, 1UL << (PAGE_SHIFT + order));
+		kunmap_atomic(addr);
+	}
+}
+#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
+static inline void check_element(mempool_t *pool, void *element)
+{
+}
+static inline void poison_element(mempool_t *pool, void *element)
+{
+}
+#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
+
+static void kasan_poison_element(mempool_t *pool, void *element)
+{
+	if (pool->alloc == mempool_alloc_slab)
+		kasan_slab_free(pool->pool_data, element);
+	if (pool->alloc == mempool_kmalloc)
+		kasan_kfree(element);
+	if (pool->alloc == mempool_alloc_pages)
+		kasan_free_pages(element, (unsigned long)pool->pool_data);
+}
+
+static void kasan_unpoison_element(mempool_t *pool, void *element)
+{
+	if (pool->alloc == mempool_alloc_slab)
+		kasan_slab_alloc(pool->pool_data, element);
+	if (pool->alloc == mempool_kmalloc)
+		kasan_krealloc(element, (size_t)pool->pool_data);
+	if (pool->alloc == mempool_alloc_pages)
+		kasan_alloc_pages(element, (unsigned long)pool->pool_data);
+}
+
+static void add_element(mempool_t *pool, void *element)
+{
+	BUG_ON(pool->curr_nr >= pool->min_nr);
+	poison_element(pool, element);
+	kasan_poison_element(pool, element);
+	pool->elements[pool->curr_nr++] = element;
+}
+
+static void *remove_element(mempool_t *pool)
+{
+	void *element = pool->elements[--pool->curr_nr];
+
+	BUG_ON(pool->curr_nr < 0);
+	kasan_unpoison_element(pool, element);
+	check_element(pool, element);
+	return element;
+}
+
+/**
+ * mempool_destroy - deallocate a memory pool
+ * @pool:      pointer to the memory pool which was allocated via
+ *             mempool_create().
+ *
+ * Free all reserved elements in @pool and @pool itself.  This function
+ * only sleeps if the free_fn() function sleeps.
+ */
+void mempool_destroy(mempool_t *pool)
+{
+	if (unlikely(!pool))
+		return;
+
+	while (pool->curr_nr) {
+		void *element = remove_element(pool);
+		pool->free(element, pool->pool_data);
+	}
+	kfree(pool->elements);
+	kfree(pool);
+}
+EXPORT_SYMBOL(mempool_destroy);
+
+/**
+ * mempool_create - create a memory pool
+ * @min_nr:    the minimum number of elements guaranteed to be
+ *             allocated for this pool.
+ * @alloc_fn:  user-defined element-allocation function.
+ * @free_fn:   user-defined element-freeing function.
+ * @pool_data: optional private data available to the user-defined functions.
+ *
+ * this function creates and allocates a guaranteed size, preallocated
+ * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
+ * functions. This function might sleep. Both the alloc_fn() and the free_fn()
+ * functions might sleep - as long as the mempool_alloc() function is not called
+ * from IRQ contexts.
+ */
+mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
+				mempool_free_t *free_fn, void *pool_data)
+{
+	return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
+				   GFP_KERNEL, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(mempool_create);
+
+mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
+			       mempool_free_t *free_fn, void *pool_data,
+			       gfp_t gfp_mask, int node_id)
+{
+	mempool_t *pool;
+	pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
+	if (!pool)
+		return NULL;
+	pool->elements = kmalloc_node(min_nr * sizeof(void *),
+				      gfp_mask, node_id);
+	if (!pool->elements) {
+		kfree(pool);
+		return NULL;
+	}
+	spin_lock_init(&pool->lock);
+	pool->min_nr = min_nr;
+	pool->pool_data = pool_data;
+	init_waitqueue_head(&pool->wait);
+	pool->alloc = alloc_fn;
+	pool->free = free_fn;
+
+	/*
+	 * First pre-allocate the guaranteed number of buffers.
+	 */
+	while (pool->curr_nr < pool->min_nr) {
+		void *element;
+
+		element = pool->alloc(gfp_mask, pool->pool_data);
+		if (unlikely(!element)) {
+			mempool_destroy(pool);
+			return NULL;
+		}
+		add_element(pool, element);
+	}
+	return pool;
+}
+EXPORT_SYMBOL(mempool_create_node);
+
+/**
+ * mempool_resize - resize an existing memory pool
+ * @pool:       pointer to the memory pool which was allocated via
+ *              mempool_create().
+ * @new_min_nr: the new minimum number of elements guaranteed to be
+ *              allocated for this pool.
+ *
+ * This function shrinks/grows the pool. In the case of growing,
+ * it cannot be guaranteed that the pool will be grown to the new
+ * size immediately, but new mempool_free() calls will refill it.
+ * This function may sleep.
+ *
+ * Note, the caller must guarantee that no mempool_destroy is called
+ * while this function is running. mempool_alloc() & mempool_free()
+ * might be called (eg. from IRQ contexts) while this function executes.
+ */
+int mempool_resize(mempool_t *pool, int new_min_nr)
+{
+	void *element;
+	void **new_elements;
+	unsigned long flags;
+
+	BUG_ON(new_min_nr <= 0);
+	might_sleep();
+
+	spin_lock_irqsave(&pool->lock, flags);
+	if (new_min_nr <= pool->min_nr) {
+		while (new_min_nr < pool->curr_nr) {
+			element = remove_element(pool);
+			spin_unlock_irqrestore(&pool->lock, flags);
+			pool->free(element, pool->pool_data);
+			spin_lock_irqsave(&pool->lock, flags);
+		}
+		pool->min_nr = new_min_nr;
+		goto out_unlock;
+	}
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	/* Grow the pool */
+	new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
+				     GFP_KERNEL);
+	if (!new_elements)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	if (unlikely(new_min_nr <= pool->min_nr)) {
+		/* Raced, other resize will do our work */
+		spin_unlock_irqrestore(&pool->lock, flags);
+		kfree(new_elements);
+		goto out;
+	}
+	memcpy(new_elements, pool->elements,
+			pool->curr_nr * sizeof(*new_elements));
+	kfree(pool->elements);
+	pool->elements = new_elements;
+	pool->min_nr = new_min_nr;
+
+	while (pool->curr_nr < pool->min_nr) {
+		spin_unlock_irqrestore(&pool->lock, flags);
+		element = pool->alloc(GFP_KERNEL, pool->pool_data);
+		if (!element)
+			goto out;
+		spin_lock_irqsave(&pool->lock, flags);
+		if (pool->curr_nr < pool->min_nr) {
+			add_element(pool, element);
+		} else {
+			spin_unlock_irqrestore(&pool->lock, flags);
+			pool->free(element, pool->pool_data);	/* Raced */
+			goto out;
+		}
+	}
+out_unlock:
+	spin_unlock_irqrestore(&pool->lock, flags);
+out:
+	return 0;
+}
+EXPORT_SYMBOL(mempool_resize);
+
+/**
+ * mempool_alloc - allocate an element from a specific memory pool
+ * @pool:      pointer to the memory pool which was allocated via
+ *             mempool_create().
+ * @gfp_mask:  the usual allocation bitmask.
+ *
+ * this function only sleeps if the alloc_fn() function sleeps or
+ * returns NULL. Note that due to preallocation, this function
+ * *never* fails when called from process contexts. (it might
+ * fail if called from an IRQ context.)
+ * Note: using __GFP_ZERO is not supported.
+ */
+void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
+{
+	void *element;
+	unsigned long flags;
+	wait_queue_t wait;
+	gfp_t gfp_temp;
+
+	VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
+	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
+
+	gfp_mask |= __GFP_NOMEMALLOC;	/* don't allocate emergency reserves */
+	gfp_mask |= __GFP_NORETRY;	/* don't loop in __alloc_pages */
+	gfp_mask |= __GFP_NOWARN;	/* failures are OK */
+
+	gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
+
+repeat_alloc:
+
+	element = pool->alloc(gfp_temp, pool->pool_data);
+	if (likely(element != NULL))
+		return element;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	if (likely(pool->curr_nr)) {
+		element = remove_element(pool);
+		spin_unlock_irqrestore(&pool->lock, flags);
+		/* paired with rmb in mempool_free(), read comment there */
+		smp_wmb();
+		/*
+		 * Update the allocation stack trace as this is more useful
+		 * for debugging.
+		 */
+		kmemleak_update_trace(element);
+		return element;
+	}
+
+	/*
+	 * We use gfp mask w/o direct reclaim or IO for the first round.  If
+	 * alloc failed with that and @pool was empty, retry immediately.
+	 */
+	if (gfp_temp != gfp_mask) {
+		spin_unlock_irqrestore(&pool->lock, flags);
+		gfp_temp = gfp_mask;
+		goto repeat_alloc;
+	}
+
+	/* We must not sleep if !__GFP_DIRECT_RECLAIM */
+	if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
+		spin_unlock_irqrestore(&pool->lock, flags);
+		return NULL;
+	}
+
+	/* Let's wait for someone else to return an element to @pool */
+	init_wait(&wait);
+	prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
+
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	/*
+	 * FIXME: this should be io_schedule().  The timeout is there as a
+	 * workaround for some DM problems in 2.6.18.
+	 */
+	io_schedule_timeout(5*HZ);
+
+	finish_wait(&pool->wait, &wait);
+	goto repeat_alloc;
+}
+EXPORT_SYMBOL(mempool_alloc);
+
+/**
+ * mempool_free - return an element to the pool.
+ * @element:   pool element pointer.
+ * @pool:      pointer to the memory pool which was allocated via
+ *             mempool_create().
+ *
+ * this function only sleeps if the free_fn() function sleeps.
+ */
+void mempool_free(void *element, mempool_t *pool)
+{
+	unsigned long flags;
+
+	if (unlikely(element == NULL))
+		return;
+
+	/*
+	 * Paired with the wmb in mempool_alloc().  The preceding read is
+	 * for @element and the following @pool->curr_nr.  This ensures
+	 * that the visible value of @pool->curr_nr is from after the
+	 * allocation of @element.  This is necessary for fringe cases
+	 * where @element was passed to this task without going through
+	 * barriers.
+	 *
+	 * For example, assume @p is %NULL at the beginning and one task
+	 * performs "p = mempool_alloc(...);" while another task is doing
+	 * "while (!p) cpu_relax(); mempool_free(p, ...);".  This function
+	 * may end up using curr_nr value which is from before allocation
+	 * of @p without the following rmb.
+	 */
+	smp_rmb();
+
+	/*
+	 * For correctness, we need a test which is guaranteed to trigger
+	 * if curr_nr + #allocated == min_nr.  Testing curr_nr < min_nr
+	 * without locking achieves that and refilling as soon as possible
+	 * is desirable.
+	 *
+	 * Because curr_nr visible here is always a value after the
+	 * allocation of @element, any task which decremented curr_nr below
+	 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
+	 * incremented to min_nr afterwards.  If curr_nr gets incremented
+	 * to min_nr after the allocation of @element, the elements
+	 * allocated after that are subject to the same guarantee.
+	 *
+	 * Waiters happen iff curr_nr is 0 and the above guarantee also
+	 * ensures that there will be frees which return elements to the
+	 * pool waking up the waiters.
+	 */
+	if (unlikely(pool->curr_nr < pool->min_nr)) {
+		spin_lock_irqsave(&pool->lock, flags);
+		if (likely(pool->curr_nr < pool->min_nr)) {
+			add_element(pool, element);
+			spin_unlock_irqrestore(&pool->lock, flags);
+			wake_up(&pool->wait);
+			return;
+		}
+		spin_unlock_irqrestore(&pool->lock, flags);
+	}
+	pool->free(element, pool->pool_data);
+}
+EXPORT_SYMBOL(mempool_free);
+
+/*
+ * A commonly used alloc and free fn.
+ */
+void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
+{
+	struct kmem_cache *mem = pool_data;
+	VM_BUG_ON(mem->ctor);
+	return kmem_cache_alloc(mem, gfp_mask);
+}
+EXPORT_SYMBOL(mempool_alloc_slab);
+
+void mempool_free_slab(void *element, void *pool_data)
+{
+	struct kmem_cache *mem = pool_data;
+	kmem_cache_free(mem, element);
+}
+EXPORT_SYMBOL(mempool_free_slab);
+
+/*
+ * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
+ * specified by pool_data
+ */
+void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
+{
+	size_t size = (size_t)pool_data;
+	return kmalloc(size, gfp_mask);
+}
+EXPORT_SYMBOL(mempool_kmalloc);
+
+void mempool_kfree(void *element, void *pool_data)
+{
+	kfree(element);
+}
+EXPORT_SYMBOL(mempool_kfree);
+
+/*
+ * A simple mempool-backed page allocator that allocates pages
+ * of the order specified by pool_data.
+ */
+void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
+{
+	int order = (int)(long)pool_data;
+	return alloc_pages(gfp_mask, order);
+}
+EXPORT_SYMBOL(mempool_alloc_pages);
+
+void mempool_free_pages(void *element, void *pool_data)
+{
+	int order = (int)(long)pool_data;
+	__free_pages(element, order);
+}
+EXPORT_SYMBOL(mempool_free_pages);
diff --git a/mm/memtest.c b/mm/memtest.c
new file mode 100644
index 0000000..8eaa4c3
--- /dev/null
+++ b/mm/memtest.c
@@ -0,0 +1,112 @@
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+
+static u64 patterns[] __initdata = {
+	/* The first entry has to be 0 to leave memtest with zeroed memory */
+	0,
+	0xffffffffffffffffULL,
+	0x5555555555555555ULL,
+	0xaaaaaaaaaaaaaaaaULL,
+	0x1111111111111111ULL,
+	0x2222222222222222ULL,
+	0x4444444444444444ULL,
+	0x8888888888888888ULL,
+	0x3333333333333333ULL,
+	0x6666666666666666ULL,
+	0x9999999999999999ULL,
+	0xccccccccccccccccULL,
+	0x7777777777777777ULL,
+	0xbbbbbbbbbbbbbbbbULL,
+	0xddddddddddddddddULL,
+	0xeeeeeeeeeeeeeeeeULL,
+	0x7a6c7258554e494cULL, /* yeah ;-) */
+};
+
+static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
+{
+	pr_info("  %016llx bad mem addr %pa - %pa reserved\n",
+		cpu_to_be64(pattern), &start_bad, &end_bad);
+	memblock_reserve(start_bad, end_bad - start_bad);
+}
+
+static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
+{
+	u64 *p, *start, *end;
+	phys_addr_t start_bad, last_bad;
+	phys_addr_t start_phys_aligned;
+	const size_t incr = sizeof(pattern);
+
+	start_phys_aligned = ALIGN(start_phys, incr);
+	start = __va(start_phys_aligned);
+	end = start + (size - (start_phys_aligned - start_phys)) / incr;
+	start_bad = 0;
+	last_bad = 0;
+
+	for (p = start; p < end; p++)
+		*p = pattern;
+
+	for (p = start; p < end; p++, start_phys_aligned += incr) {
+		if (*p == pattern)
+			continue;
+		if (start_phys_aligned == last_bad + incr) {
+			last_bad += incr;
+			continue;
+		}
+		if (start_bad)
+			reserve_bad_mem(pattern, start_bad, last_bad + incr);
+		start_bad = last_bad = start_phys_aligned;
+	}
+	if (start_bad)
+		reserve_bad_mem(pattern, start_bad, last_bad + incr);
+}
+
+static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
+{
+	u64 i;
+	phys_addr_t this_start, this_end;
+
+	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
+				&this_end, NULL) {
+		this_start = clamp(this_start, start, end);
+		this_end = clamp(this_end, start, end);
+		if (this_start < this_end) {
+			pr_info("  %pa - %pa pattern %016llx\n",
+				&this_start, &this_end, cpu_to_be64(pattern));
+			memtest(pattern, this_start, this_end - this_start);
+		}
+	}
+}
+
+/* default is disabled */
+static unsigned int memtest_pattern __initdata;
+
+static int __init parse_memtest(char *arg)
+{
+	int ret = 0;
+
+	if (arg)
+		ret = kstrtouint(arg, 0, &memtest_pattern);
+	else
+		memtest_pattern = ARRAY_SIZE(patterns);
+
+	return ret;
+}
+
+early_param("memtest", parse_memtest);
+
+void __init early_memtest(phys_addr_t start, phys_addr_t end)
+{
+	unsigned int i;
+	unsigned int idx = 0;
+
+	if (!memtest_pattern)
+		return;
+
+	pr_info("early_memtest: # of tests: %u\n", memtest_pattern);
+	for (i = memtest_pattern-1; i < UINT_MAX; --i) {
+		idx = i % ARRAY_SIZE(patterns);
+		do_one_pass(patterns[idx], start, end);
+	}
+}
diff --git a/mm/migrate.c b/mm/migrate.c
new file mode 100644
index 0000000..afedcfa
--- /dev/null
+++ b/mm/migrate.c
@@ -0,0 +1,1879 @@
+/*
+ * Memory Migration functionality - linux/mm/migrate.c
+ *
+ * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
+ *
+ * Page migration was first developed in the context of the memory hotplug
+ * project. The main authors of the migration code are:
+ *
+ * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
+ * Hirokazu Takahashi <taka@valinux.co.jp>
+ * Dave Hansen <haveblue@us.ibm.com>
+ * Christoph Lameter
+ */
+
+#include <linux/migrate.h>
+#include <linux/export.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>
+#include <linux/mm_inline.h>
+#include <linux/nsproxy.h>
+#include <linux/pagevec.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/topology.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/writeback.h>
+#include <linux/mempolicy.h>
+#include <linux/vmalloc.h>
+#include <linux/security.h>
+#include <linux/backing-dev.h>
+#include <linux/syscalls.h>
+#include <linux/hugetlb.h>
+#include <linux/hugetlb_cgroup.h>
+#include <linux/gfp.h>
+#include <linux/balloon_compaction.h>
+#include <linux/mmu_notifier.h>
+#include <linux/page_idle.h>
+#include <linux/ptrace.h>
+
+#include <asm/tlbflush.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/migrate.h>
+
+#include "internal.h"
+
+/*
+ * migrate_prep() needs to be called before we start compiling a list of pages
+ * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
+ * undesirable, use migrate_prep_local()
+ */
+int migrate_prep(void)
+{
+	/*
+	 * Clear the LRU lists so pages can be isolated.
+	 * Note that pages may be moved off the LRU after we have
+	 * drained them. Those pages will fail to migrate like other
+	 * pages that may be busy.
+	 */
+	lru_add_drain_all();
+
+	return 0;
+}
+
+/* Do the necessary work of migrate_prep but not if it involves other CPUs */
+int migrate_prep_local(void)
+{
+	lru_add_drain();
+
+	return 0;
+}
+
+/*
+ * Put previously isolated pages back onto the appropriate lists
+ * from where they were once taken off for compaction/migration.
+ *
+ * This function shall be used whenever the isolated pageset has been
+ * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
+ * and isolate_huge_page().
+ */
+void putback_movable_pages(struct list_head *l)
+{
+	struct page *page;
+	struct page *page2;
+
+	list_for_each_entry_safe(page, page2, l, lru) {
+		if (unlikely(PageHuge(page))) {
+			putback_active_hugepage(page);
+			continue;
+		}
+		list_del(&page->lru);
+		dec_zone_page_state(page, NR_ISOLATED_ANON +
+				page_is_file_cache(page));
+		if (unlikely(isolated_balloon_page(page)))
+			balloon_page_putback(page);
+		else
+			putback_lru_page(page);
+	}
+}
+
+/*
+ * Restore a potential migration pte to a working pte entry
+ */
+static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
+				 unsigned long addr, void *old)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	swp_entry_t entry;
+ 	pmd_t *pmd;
+	pte_t *ptep, pte;
+ 	spinlock_t *ptl;
+
+	if (unlikely(PageHuge(new))) {
+		ptep = huge_pte_offset(mm, addr);
+		if (!ptep)
+			goto out;
+		ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep);
+	} else {
+		pmd = mm_find_pmd(mm, addr);
+		if (!pmd)
+			goto out;
+
+		ptep = pte_offset_map(pmd, addr);
+
+		/*
+		 * Peek to check is_swap_pte() before taking ptlock?  No, we
+		 * can race mremap's move_ptes(), which skips anon_vma lock.
+		 */
+
+		ptl = pte_lockptr(mm, pmd);
+	}
+
+ 	spin_lock(ptl);
+	pte = *ptep;
+	if (!is_swap_pte(pte))
+		goto unlock;
+
+	entry = pte_to_swp_entry(pte);
+
+	if (!is_migration_entry(entry) ||
+	    migration_entry_to_page(entry) != old)
+		goto unlock;
+
+	get_page(new);
+	pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
+	if (pte_swp_soft_dirty(*ptep))
+		pte = pte_mksoft_dirty(pte);
+
+	/* Recheck VMA as permissions can change since migration started  */
+	if (is_write_migration_entry(entry))
+		pte = maybe_mkwrite(pte, vma);
+
+#ifdef CONFIG_HUGETLB_PAGE
+	if (PageHuge(new)) {
+		pte = pte_mkhuge(pte);
+		pte = arch_make_huge_pte(pte, vma, new, 0);
+	}
+#endif
+	flush_dcache_page(new);
+	set_pte_at(mm, addr, ptep, pte);
+
+	if (PageHuge(new)) {
+		if (PageAnon(new))
+			hugepage_add_anon_rmap(new, vma, addr);
+		else
+			page_dup_rmap(new);
+	} else if (PageAnon(new))
+		page_add_anon_rmap(new, vma, addr);
+	else
+		page_add_file_rmap(new);
+
+	if (vma->vm_flags & VM_LOCKED)
+		mlock_vma_page(new);
+
+	/* No need to invalidate - it was non-present before */
+	update_mmu_cache(vma, addr, ptep);
+unlock:
+	pte_unmap_unlock(ptep, ptl);
+out:
+	return SWAP_AGAIN;
+}
+
+/*
+ * Get rid of all migration entries and replace them by
+ * references to the indicated page.
+ */
+static void remove_migration_ptes(struct page *old, struct page *new)
+{
+	struct rmap_walk_control rwc = {
+		.rmap_one = remove_migration_pte,
+		.arg = old,
+	};
+
+	rmap_walk(new, &rwc);
+}
+
+/*
+ * Something used the pte of a page under migration. We need to
+ * get to the page and wait until migration is finished.
+ * When we return from this function the fault will be retried.
+ */
+void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
+				spinlock_t *ptl)
+{
+	pte_t pte;
+	swp_entry_t entry;
+	struct page *page;
+
+	spin_lock(ptl);
+	pte = *ptep;
+	if (!is_swap_pte(pte))
+		goto out;
+
+	entry = pte_to_swp_entry(pte);
+	if (!is_migration_entry(entry))
+		goto out;
+
+	page = migration_entry_to_page(entry);
+
+	/*
+	 * Once radix-tree replacement of page migration started, page_count
+	 * *must* be zero. And, we don't want to call wait_on_page_locked()
+	 * against a page without get_page().
+	 * So, we use get_page_unless_zero(), here. Even failed, page fault
+	 * will occur again.
+	 */
+	if (!get_page_unless_zero(page))
+		goto out;
+	pte_unmap_unlock(ptep, ptl);
+	wait_on_page_locked(page);
+	put_page(page);
+	return;
+out:
+	pte_unmap_unlock(ptep, ptl);
+}
+
+void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+				unsigned long address)
+{
+	spinlock_t *ptl = pte_lockptr(mm, pmd);
+	pte_t *ptep = pte_offset_map(pmd, address);
+	__migration_entry_wait(mm, ptep, ptl);
+}
+
+void migration_entry_wait_huge(struct vm_area_struct *vma,
+		struct mm_struct *mm, pte_t *pte)
+{
+	spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte);
+	__migration_entry_wait(mm, pte, ptl);
+}
+
+#ifdef CONFIG_BLOCK
+/* Returns true if all buffers are successfully locked */
+static bool buffer_migrate_lock_buffers(struct buffer_head *head,
+							enum migrate_mode mode)
+{
+	struct buffer_head *bh = head;
+
+	/* Simple case, sync compaction */
+	if (mode != MIGRATE_ASYNC) {
+		do {
+			get_bh(bh);
+			lock_buffer(bh);
+			bh = bh->b_this_page;
+
+		} while (bh != head);
+
+		return true;
+	}
+
+	/* async case, we cannot block on lock_buffer so use trylock_buffer */
+	do {
+		get_bh(bh);
+		if (!trylock_buffer(bh)) {
+			/*
+			 * We failed to lock the buffer and cannot stall in
+			 * async migration. Release the taken locks
+			 */
+			struct buffer_head *failed_bh = bh;
+			put_bh(failed_bh);
+			bh = head;
+			while (bh != failed_bh) {
+				unlock_buffer(bh);
+				put_bh(bh);
+				bh = bh->b_this_page;
+			}
+			return false;
+		}
+
+		bh = bh->b_this_page;
+	} while (bh != head);
+	return true;
+}
+#else
+static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
+							enum migrate_mode mode)
+{
+	return true;
+}
+#endif /* CONFIG_BLOCK */
+
+/*
+ * Replace the page in the mapping.
+ *
+ * The number of remaining references must be:
+ * 1 for anonymous pages without a mapping
+ * 2 for pages with a mapping
+ * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
+ */
+int migrate_page_move_mapping(struct address_space *mapping,
+		struct page *newpage, struct page *page,
+		struct buffer_head *head, enum migrate_mode mode,
+		int extra_count)
+{
+	struct zone *oldzone, *newzone;
+	int dirty;
+	int expected_count = 1 + extra_count;
+	void **pslot;
+
+	if (!mapping) {
+		/* Anonymous page without mapping */
+		if (page_count(page) != expected_count)
+			return -EAGAIN;
+
+		/* No turning back from here */
+		set_page_memcg(newpage, page_memcg(page));
+		newpage->index = page->index;
+		newpage->mapping = page->mapping;
+		if (PageSwapBacked(page))
+			SetPageSwapBacked(newpage);
+
+		return MIGRATEPAGE_SUCCESS;
+	}
+
+	oldzone = page_zone(page);
+	newzone = page_zone(newpage);
+
+	spin_lock_irq(&mapping->tree_lock);
+
+	pslot = radix_tree_lookup_slot(&mapping->page_tree,
+ 					page_index(page));
+
+	expected_count += 1 + page_has_private(page);
+	if (page_count(page) != expected_count ||
+		radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
+		spin_unlock_irq(&mapping->tree_lock);
+		return -EAGAIN;
+	}
+
+	if (!page_freeze_refs(page, expected_count)) {
+		spin_unlock_irq(&mapping->tree_lock);
+		return -EAGAIN;
+	}
+
+	/*
+	 * In the async migration case of moving a page with buffers, lock the
+	 * buffers using trylock before the mapping is moved. If the mapping
+	 * was moved, we later failed to lock the buffers and could not move
+	 * the mapping back due to an elevated page count, we would have to
+	 * block waiting on other references to be dropped.
+	 */
+	if (mode == MIGRATE_ASYNC && head &&
+			!buffer_migrate_lock_buffers(head, mode)) {
+		page_unfreeze_refs(page, expected_count);
+		spin_unlock_irq(&mapping->tree_lock);
+		return -EAGAIN;
+	}
+
+	/*
+	 * Now we know that no one else is looking at the page:
+	 * no turning back from here.
+	 */
+	set_page_memcg(newpage, page_memcg(page));
+	newpage->index = page->index;
+	newpage->mapping = page->mapping;
+	if (PageSwapBacked(page))
+		SetPageSwapBacked(newpage);
+
+	get_page(newpage);	/* add cache reference */
+	if (PageSwapCache(page)) {
+		SetPageSwapCache(newpage);
+		set_page_private(newpage, page_private(page));
+	}
+
+	/* Move dirty while page refs frozen and newpage not yet exposed */
+	dirty = PageDirty(page);
+	if (dirty) {
+		ClearPageDirty(page);
+		SetPageDirty(newpage);
+	}
+
+	radix_tree_replace_slot(pslot, newpage);
+
+	/*
+	 * Drop cache reference from old page by unfreezing
+	 * to one less reference.
+	 * We know this isn't the last reference.
+	 */
+	page_unfreeze_refs(page, expected_count - 1);
+
+	spin_unlock(&mapping->tree_lock);
+	/* Leave irq disabled to prevent preemption while updating stats */
+
+	/*
+	 * If moved to a different zone then also account
+	 * the page for that zone. Other VM counters will be
+	 * taken care of when we establish references to the
+	 * new page and drop references to the old page.
+	 *
+	 * Note that anonymous pages are accounted for
+	 * via NR_FILE_PAGES and NR_ANON_PAGES if they
+	 * are mapped to swap space.
+	 */
+	if (newzone != oldzone) {
+		__dec_zone_state(oldzone, NR_FILE_PAGES);
+		__inc_zone_state(newzone, NR_FILE_PAGES);
+		if (PageSwapBacked(page) && !PageSwapCache(page)) {
+			__dec_zone_state(oldzone, NR_SHMEM);
+			__inc_zone_state(newzone, NR_SHMEM);
+		}
+		if (dirty && mapping_cap_account_dirty(mapping)) {
+			__dec_zone_state(oldzone, NR_FILE_DIRTY);
+			__inc_zone_state(newzone, NR_FILE_DIRTY);
+		}
+	}
+	local_irq_enable();
+
+	return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL(migrate_page_move_mapping);
+
+/*
+ * The expected number of remaining references is the same as that
+ * of migrate_page_move_mapping().
+ */
+int migrate_huge_page_move_mapping(struct address_space *mapping,
+				   struct page *newpage, struct page *page)
+{
+	int expected_count;
+	void **pslot;
+
+	spin_lock_irq(&mapping->tree_lock);
+
+	pslot = radix_tree_lookup_slot(&mapping->page_tree,
+					page_index(page));
+
+	expected_count = 2 + page_has_private(page);
+	if (page_count(page) != expected_count ||
+		radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
+		spin_unlock_irq(&mapping->tree_lock);
+		return -EAGAIN;
+	}
+
+	if (!page_freeze_refs(page, expected_count)) {
+		spin_unlock_irq(&mapping->tree_lock);
+		return -EAGAIN;
+	}
+
+	set_page_memcg(newpage, page_memcg(page));
+	newpage->index = page->index;
+	newpage->mapping = page->mapping;
+	get_page(newpage);
+
+	radix_tree_replace_slot(pslot, newpage);
+
+	page_unfreeze_refs(page, expected_count - 1);
+
+	spin_unlock_irq(&mapping->tree_lock);
+	return MIGRATEPAGE_SUCCESS;
+}
+
+/*
+ * Gigantic pages are so large that we do not guarantee that page++ pointer
+ * arithmetic will work across the entire page.  We need something more
+ * specialized.
+ */
+static void __copy_gigantic_page(struct page *dst, struct page *src,
+				int nr_pages)
+{
+	int i;
+	struct page *dst_base = dst;
+	struct page *src_base = src;
+
+	for (i = 0; i < nr_pages; ) {
+		cond_resched();
+		copy_highpage(dst, src);
+
+		i++;
+		dst = mem_map_next(dst, dst_base, i);
+		src = mem_map_next(src, src_base, i);
+	}
+}
+
+static void copy_huge_page(struct page *dst, struct page *src)
+{
+	int i;
+	int nr_pages;
+
+	if (PageHuge(src)) {
+		/* hugetlbfs page */
+		struct hstate *h = page_hstate(src);
+		nr_pages = pages_per_huge_page(h);
+
+		if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) {
+			__copy_gigantic_page(dst, src, nr_pages);
+			return;
+		}
+	} else {
+		/* thp page */
+		BUG_ON(!PageTransHuge(src));
+		nr_pages = hpage_nr_pages(src);
+	}
+
+	for (i = 0; i < nr_pages; i++) {
+		cond_resched();
+		copy_highpage(dst + i, src + i);
+	}
+}
+
+/*
+ * Copy the page to its new location
+ */
+void migrate_page_copy(struct page *newpage, struct page *page)
+{
+	int cpupid;
+
+	if (PageHuge(page) || PageTransHuge(page))
+		copy_huge_page(newpage, page);
+	else
+		copy_highpage(newpage, page);
+
+	if (PageError(page))
+		SetPageError(newpage);
+	if (PageReferenced(page))
+		SetPageReferenced(newpage);
+	if (PageUptodate(page))
+		SetPageUptodate(newpage);
+	if (TestClearPageActive(page)) {
+		VM_BUG_ON_PAGE(PageUnevictable(page), page);
+		SetPageActive(newpage);
+	} else if (TestClearPageUnevictable(page))
+		SetPageUnevictable(newpage);
+	if (PageChecked(page))
+		SetPageChecked(newpage);
+	if (PageMappedToDisk(page))
+		SetPageMappedToDisk(newpage);
+
+	/* Move dirty on pages not done by migrate_page_move_mapping() */
+	if (PageDirty(page))
+		SetPageDirty(newpage);
+
+	if (page_is_young(page))
+		set_page_young(newpage);
+	if (page_is_idle(page))
+		set_page_idle(newpage);
+
+	/*
+	 * Copy NUMA information to the new page, to prevent over-eager
+	 * future migrations of this same page.
+	 */
+	cpupid = page_cpupid_xchg_last(page, -1);
+	page_cpupid_xchg_last(newpage, cpupid);
+
+	ksm_migrate_page(newpage, page);
+	/*
+	 * Please do not reorder this without considering how mm/ksm.c's
+	 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
+	 */
+	if (PageSwapCache(page))
+		ClearPageSwapCache(page);
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+
+	/*
+	 * If any waiters have accumulated on the new page then
+	 * wake them up.
+	 */
+	if (PageWriteback(newpage))
+		end_page_writeback(newpage);
+}
+EXPORT_SYMBOL(migrate_page_copy);
+
+/************************************************************
+ *                    Migration functions
+ ***********************************************************/
+
+/*
+ * Common logic to directly migrate a single page suitable for
+ * pages that do not use PagePrivate/PagePrivate2.
+ *
+ * Pages are locked upon entry and exit.
+ */
+int migrate_page(struct address_space *mapping,
+		struct page *newpage, struct page *page,
+		enum migrate_mode mode)
+{
+	int rc;
+
+	BUG_ON(PageWriteback(page));	/* Writeback must be complete */
+
+	rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
+
+	if (rc != MIGRATEPAGE_SUCCESS)
+		return rc;
+
+	migrate_page_copy(newpage, page);
+	return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL(migrate_page);
+
+#ifdef CONFIG_BLOCK
+/*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+int buffer_migrate_page(struct address_space *mapping,
+		struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+	struct buffer_head *bh, *head;
+	int rc;
+
+	if (!page_has_buffers(page))
+		return migrate_page(mapping, newpage, page, mode);
+
+	head = page_buffers(page);
+
+	rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0);
+
+	if (rc != MIGRATEPAGE_SUCCESS)
+		return rc;
+
+	/*
+	 * In the async case, migrate_page_move_mapping locked the buffers
+	 * with an IRQ-safe spinlock held. In the sync case, the buffers
+	 * need to be locked now
+	 */
+	if (mode != MIGRATE_ASYNC)
+		BUG_ON(!buffer_migrate_lock_buffers(head, mode));
+
+	ClearPagePrivate(page);
+	set_page_private(newpage, page_private(page));
+	set_page_private(page, 0);
+	put_page(page);
+	get_page(newpage);
+
+	bh = head;
+	do {
+		set_bh_page(bh, newpage, bh_offset(bh));
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	SetPagePrivate(newpage);
+
+	migrate_page_copy(newpage, page);
+
+	bh = head;
+	do {
+		unlock_buffer(bh);
+ 		put_bh(bh);
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL(buffer_migrate_page);
+#endif
+
+/*
+ * Writeback a page to clean the dirty state
+ */
+static int writeout(struct address_space *mapping, struct page *page)
+{
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_NONE,
+		.nr_to_write = 1,
+		.range_start = 0,
+		.range_end = LLONG_MAX,
+		.for_reclaim = 1
+	};
+	int rc;
+
+	if (!mapping->a_ops->writepage)
+		/* No write method for the address space */
+		return -EINVAL;
+
+	if (!clear_page_dirty_for_io(page))
+		/* Someone else already triggered a write */
+		return -EAGAIN;
+
+	/*
+	 * A dirty page may imply that the underlying filesystem has
+	 * the page on some queue. So the page must be clean for
+	 * migration. Writeout may mean we loose the lock and the
+	 * page state is no longer what we checked for earlier.
+	 * At this point we know that the migration attempt cannot
+	 * be successful.
+	 */
+	remove_migration_ptes(page, page);
+
+	rc = mapping->a_ops->writepage(page, &wbc);
+
+	if (rc != AOP_WRITEPAGE_ACTIVATE)
+		/* unlocked. Relock */
+		lock_page(page);
+
+	return (rc < 0) ? -EIO : -EAGAIN;
+}
+
+/*
+ * Default handling if a filesystem does not provide a migration function.
+ */
+static int fallback_migrate_page(struct address_space *mapping,
+	struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+	if (PageDirty(page)) {
+		/* Only writeback pages in full synchronous migration */
+		if (mode != MIGRATE_SYNC)
+			return -EBUSY;
+		return writeout(mapping, page);
+	}
+
+	/*
+	 * Buffers may be managed in a filesystem specific way.
+	 * We must have no buffers or drop them.
+	 */
+	if (page_has_private(page) &&
+	    !try_to_release_page(page, GFP_KERNEL))
+		return -EAGAIN;
+
+	return migrate_page(mapping, newpage, page, mode);
+}
+
+/*
+ * Move a page to a newly allocated page
+ * The page is locked and all ptes have been successfully removed.
+ *
+ * The new page will have replaced the old page if this function
+ * is successful.
+ *
+ * Return value:
+ *   < 0 - error code
+ *  MIGRATEPAGE_SUCCESS - success
+ */
+static int move_to_new_page(struct page *newpage, struct page *page,
+				enum migrate_mode mode)
+{
+	struct address_space *mapping;
+	int rc;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+
+	mapping = page_mapping(page);
+	if (!mapping)
+		rc = migrate_page(mapping, newpage, page, mode);
+	else if (mapping->a_ops->migratepage)
+		/*
+		 * Most pages have a mapping and most filesystems provide a
+		 * migratepage callback. Anonymous pages are part of swap
+		 * space which also has its own migratepage callback. This
+		 * is the most common path for page migration.
+		 */
+		rc = mapping->a_ops->migratepage(mapping, newpage, page, mode);
+	else
+		rc = fallback_migrate_page(mapping, newpage, page, mode);
+
+	/*
+	 * When successful, old pagecache page->mapping must be cleared before
+	 * page is freed; but stats require that PageAnon be left as PageAnon.
+	 */
+	if (rc == MIGRATEPAGE_SUCCESS) {
+		set_page_memcg(page, NULL);
+		if (!PageAnon(page))
+			page->mapping = NULL;
+	}
+	return rc;
+}
+
+static int __unmap_and_move(struct page *page, struct page *newpage,
+				int force, enum migrate_mode mode)
+{
+	int rc = -EAGAIN;
+	int page_was_mapped = 0;
+	struct anon_vma *anon_vma = NULL;
+
+	if (!trylock_page(page)) {
+		if (!force || mode == MIGRATE_ASYNC)
+			goto out;
+
+		/*
+		 * It's not safe for direct compaction to call lock_page.
+		 * For example, during page readahead pages are added locked
+		 * to the LRU. Later, when the IO completes the pages are
+		 * marked uptodate and unlocked. However, the queueing
+		 * could be merging multiple pages for one bio (e.g.
+		 * mpage_readpages). If an allocation happens for the
+		 * second or third page, the process can end up locking
+		 * the same page twice and deadlocking. Rather than
+		 * trying to be clever about what pages can be locked,
+		 * avoid the use of lock_page for direct compaction
+		 * altogether.
+		 */
+		if (current->flags & PF_MEMALLOC)
+			goto out;
+
+		lock_page(page);
+	}
+
+	if (PageWriteback(page)) {
+		/*
+		 * Only in the case of a full synchronous migration is it
+		 * necessary to wait for PageWriteback. In the async case,
+		 * the retry loop is too short and in the sync-light case,
+		 * the overhead of stalling is too much
+		 */
+		if (mode != MIGRATE_SYNC) {
+			rc = -EBUSY;
+			goto out_unlock;
+		}
+		if (!force)
+			goto out_unlock;
+		wait_on_page_writeback(page);
+	}
+
+	/*
+	 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
+	 * we cannot notice that anon_vma is freed while we migrates a page.
+	 * This get_anon_vma() delays freeing anon_vma pointer until the end
+	 * of migration. File cache pages are no problem because of page_lock()
+	 * File Caches may use write_page() or lock_page() in migration, then,
+	 * just care Anon page here.
+	 *
+	 * Only page_get_anon_vma() understands the subtleties of
+	 * getting a hold on an anon_vma from outside one of its mms.
+	 * But if we cannot get anon_vma, then we won't need it anyway,
+	 * because that implies that the anon page is no longer mapped
+	 * (and cannot be remapped so long as we hold the page lock).
+	 */
+	if (PageAnon(page) && !PageKsm(page))
+		anon_vma = page_get_anon_vma(page);
+
+	/*
+	 * Block others from accessing the new page when we get around to
+	 * establishing additional references. We are usually the only one
+	 * holding a reference to newpage at this point. We used to have a BUG
+	 * here if trylock_page(newpage) fails, but would like to allow for
+	 * cases where there might be a race with the previous use of newpage.
+	 * This is much like races on refcount of oldpage: just don't BUG().
+	 */
+	if (unlikely(!trylock_page(newpage)))
+		goto out_unlock;
+
+	if (unlikely(isolated_balloon_page(page))) {
+		/*
+		 * A ballooned page does not need any special attention from
+		 * physical to virtual reverse mapping procedures.
+		 * Skip any attempt to unmap PTEs or to remap swap cache,
+		 * in order to avoid burning cycles at rmap level, and perform
+		 * the page migration right away (proteced by page lock).
+		 */
+		rc = balloon_page_migrate(newpage, page, mode);
+		goto out_unlock_both;
+	}
+
+	/*
+	 * Corner case handling:
+	 * 1. When a new swap-cache page is read into, it is added to the LRU
+	 * and treated as swapcache but it has no rmap yet.
+	 * Calling try_to_unmap() against a page->mapping==NULL page will
+	 * trigger a BUG.  So handle it here.
+	 * 2. An orphaned page (see truncate_complete_page) might have
+	 * fs-private metadata. The page can be picked up due to memory
+	 * offlining.  Everywhere else except page reclaim, the page is
+	 * invisible to the vm, so the page can not be migrated.  So try to
+	 * free the metadata, so the page can be freed.
+	 */
+	if (!page->mapping) {
+		VM_BUG_ON_PAGE(PageAnon(page), page);
+		if (page_has_private(page)) {
+			try_to_free_buffers(page);
+			goto out_unlock_both;
+		}
+	} else if (page_mapped(page)) {
+		/* Establish migration ptes */
+		VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma,
+				page);
+		try_to_unmap(page,
+			TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+		page_was_mapped = 1;
+	}
+
+	if (!page_mapped(page))
+		rc = move_to_new_page(newpage, page, mode);
+
+	if (page_was_mapped)
+		remove_migration_ptes(page,
+			rc == MIGRATEPAGE_SUCCESS ? newpage : page);
+
+out_unlock_both:
+	unlock_page(newpage);
+out_unlock:
+	/* Drop an anon_vma reference if we took one */
+	if (anon_vma)
+		put_anon_vma(anon_vma);
+	unlock_page(page);
+out:
+	return rc;
+}
+
+/*
+ * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move().  Work
+ * around it.
+ */
+#if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM)
+#define ICE_noinline noinline
+#else
+#define ICE_noinline
+#endif
+
+/*
+ * Obtain the lock on page, remove all ptes and migrate the page
+ * to the newly allocated page in newpage.
+ */
+static ICE_noinline int unmap_and_move(new_page_t get_new_page,
+				   free_page_t put_new_page,
+				   unsigned long private, struct page *page,
+				   int force, enum migrate_mode mode,
+				   enum migrate_reason reason)
+{
+	int rc = MIGRATEPAGE_SUCCESS;
+	int *result = NULL;
+	struct page *newpage;
+
+	newpage = get_new_page(page, private, &result);
+	if (!newpage)
+		return -ENOMEM;
+
+	if (page_count(page) == 1) {
+		/* page was freed from under us. So we are done. */
+		goto out;
+	}
+
+	if (unlikely(PageTransHuge(page)))
+		if (unlikely(split_huge_page(page)))
+			goto out;
+
+	rc = __unmap_and_move(page, newpage, force, mode);
+	if (rc == MIGRATEPAGE_SUCCESS)
+		put_new_page = NULL;
+
+out:
+	if (rc != -EAGAIN) {
+		/*
+		 * A page that has been migrated has all references
+		 * removed and will be freed. A page that has not been
+		 * migrated will have kepts its references and be
+		 * restored.
+		 */
+		list_del(&page->lru);
+		dec_zone_page_state(page, NR_ISOLATED_ANON +
+				page_is_file_cache(page));
+		/* Soft-offlined page shouldn't go through lru cache list */
+		if (reason == MR_MEMORY_FAILURE && rc == MIGRATEPAGE_SUCCESS) {
+			/*
+			 * With this release, we free successfully migrated
+			 * page and set PG_HWPoison on just freed page
+			 * intentionally. Although it's rather weird, it's how
+			 * HWPoison flag works at the moment.
+			 */
+			put_page(page);
+			if (!test_set_page_hwpoison(page))
+				num_poisoned_pages_inc();
+		} else
+			putback_lru_page(page);
+	}
+
+	/*
+	 * If migration was not successful and there's a freeing callback, use
+	 * it.  Otherwise, putback_lru_page() will drop the reference grabbed
+	 * during isolation.
+	 */
+	if (put_new_page)
+		put_new_page(newpage, private);
+	else if (unlikely(__is_movable_balloon_page(newpage))) {
+		/* drop our reference, page already in the balloon */
+		put_page(newpage);
+	} else
+		putback_lru_page(newpage);
+
+	if (result) {
+		if (rc)
+			*result = rc;
+		else
+			*result = page_to_nid(newpage);
+	}
+	return rc;
+}
+
+/*
+ * Counterpart of unmap_and_move_page() for hugepage migration.
+ *
+ * This function doesn't wait the completion of hugepage I/O
+ * because there is no race between I/O and migration for hugepage.
+ * Note that currently hugepage I/O occurs only in direct I/O
+ * where no lock is held and PG_writeback is irrelevant,
+ * and writeback status of all subpages are counted in the reference
+ * count of the head page (i.e. if all subpages of a 2MB hugepage are
+ * under direct I/O, the reference of the head page is 512 and a bit more.)
+ * This means that when we try to migrate hugepage whose subpages are
+ * doing direct I/O, some references remain after try_to_unmap() and
+ * hugepage migration fails without data corruption.
+ *
+ * There is also no race when direct I/O is issued on the page under migration,
+ * because then pte is replaced with migration swap entry and direct I/O code
+ * will wait in the page fault for migration to complete.
+ */
+static int unmap_and_move_huge_page(new_page_t get_new_page,
+				free_page_t put_new_page, unsigned long private,
+				struct page *hpage, int force,
+				enum migrate_mode mode)
+{
+	int rc = -EAGAIN;
+	int *result = NULL;
+	int page_was_mapped = 0;
+	struct page *new_hpage;
+	struct anon_vma *anon_vma = NULL;
+
+	/*
+	 * Movability of hugepages depends on architectures and hugepage size.
+	 * This check is necessary because some callers of hugepage migration
+	 * like soft offline and memory hotremove don't walk through page
+	 * tables or check whether the hugepage is pmd-based or not before
+	 * kicking migration.
+	 */
+	if (!hugepage_migration_supported(page_hstate(hpage))) {
+		putback_active_hugepage(hpage);
+		return -ENOSYS;
+	}
+
+	new_hpage = get_new_page(hpage, private, &result);
+	if (!new_hpage)
+		return -ENOMEM;
+
+	if (!trylock_page(hpage)) {
+		if (!force || mode != MIGRATE_SYNC)
+			goto out;
+		lock_page(hpage);
+	}
+
+	if (PageAnon(hpage))
+		anon_vma = page_get_anon_vma(hpage);
+
+	if (unlikely(!trylock_page(new_hpage)))
+		goto put_anon;
+
+	if (page_mapped(hpage)) {
+		try_to_unmap(hpage,
+			TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+		page_was_mapped = 1;
+	}
+
+	if (!page_mapped(hpage))
+		rc = move_to_new_page(new_hpage, hpage, mode);
+
+	if (page_was_mapped)
+		remove_migration_ptes(hpage,
+			rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage);
+
+	unlock_page(new_hpage);
+
+put_anon:
+	if (anon_vma)
+		put_anon_vma(anon_vma);
+
+	if (rc == MIGRATEPAGE_SUCCESS) {
+		hugetlb_cgroup_migrate(hpage, new_hpage);
+		put_new_page = NULL;
+	}
+
+	unlock_page(hpage);
+out:
+	if (rc != -EAGAIN)
+		putback_active_hugepage(hpage);
+
+	/*
+	 * If migration was not successful and there's a freeing callback, use
+	 * it.  Otherwise, put_page() will drop the reference grabbed during
+	 * isolation.
+	 */
+	if (put_new_page)
+		put_new_page(new_hpage, private);
+	else
+		putback_active_hugepage(new_hpage);
+
+	if (result) {
+		if (rc)
+			*result = rc;
+		else
+			*result = page_to_nid(new_hpage);
+	}
+	return rc;
+}
+
+/*
+ * migrate_pages - migrate the pages specified in a list, to the free pages
+ *		   supplied as the target for the page migration
+ *
+ * @from:		The list of pages to be migrated.
+ * @get_new_page:	The function used to allocate free pages to be used
+ *			as the target of the page migration.
+ * @put_new_page:	The function used to free target pages if migration
+ *			fails, or NULL if no special handling is necessary.
+ * @private:		Private data to be passed on to get_new_page()
+ * @mode:		The migration mode that specifies the constraints for
+ *			page migration, if any.
+ * @reason:		The reason for page migration.
+ *
+ * The function returns after 10 attempts or if no pages are movable any more
+ * because the list has become empty or no retryable pages exist any more.
+ * The caller should call putback_movable_pages() to return pages to the LRU
+ * or free list only if ret != 0.
+ *
+ * Returns the number of pages that were not migrated, or an error code.
+ */
+int migrate_pages(struct list_head *from, new_page_t get_new_page,
+		free_page_t put_new_page, unsigned long private,
+		enum migrate_mode mode, int reason)
+{
+	int retry = 1;
+	int nr_failed = 0;
+	int nr_succeeded = 0;
+	int pass = 0;
+	struct page *page;
+	struct page *page2;
+	int swapwrite = current->flags & PF_SWAPWRITE;
+	int rc;
+
+	if (!swapwrite)
+		current->flags |= PF_SWAPWRITE;
+
+	for(pass = 0; pass < 10 && retry; pass++) {
+		retry = 0;
+
+		list_for_each_entry_safe(page, page2, from, lru) {
+			cond_resched();
+
+			if (PageHuge(page))
+				rc = unmap_and_move_huge_page(get_new_page,
+						put_new_page, private, page,
+						pass > 2, mode);
+			else
+				rc = unmap_and_move(get_new_page, put_new_page,
+						private, page, pass > 2, mode,
+						reason);
+
+			switch(rc) {
+			case -ENOMEM:
+				goto out;
+			case -EAGAIN:
+				retry++;
+				break;
+			case MIGRATEPAGE_SUCCESS:
+				nr_succeeded++;
+				break;
+			default:
+				/*
+				 * Permanent failure (-EBUSY, -ENOSYS, etc.):
+				 * unlike -EAGAIN case, the failed page is
+				 * removed from migration page list and not
+				 * retried in the next outer loop.
+				 */
+				nr_failed++;
+				break;
+			}
+		}
+	}
+	nr_failed += retry;
+	rc = nr_failed;
+out:
+	if (nr_succeeded)
+		count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
+	if (nr_failed)
+		count_vm_events(PGMIGRATE_FAIL, nr_failed);
+	trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason);
+
+	if (!swapwrite)
+		current->flags &= ~PF_SWAPWRITE;
+
+	return rc;
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * Move a list of individual pages
+ */
+struct page_to_node {
+	unsigned long addr;
+	struct page *page;
+	int node;
+	int status;
+};
+
+static struct page *new_page_node(struct page *p, unsigned long private,
+		int **result)
+{
+	struct page_to_node *pm = (struct page_to_node *)private;
+
+	while (pm->node != MAX_NUMNODES && pm->page != p)
+		pm++;
+
+	if (pm->node == MAX_NUMNODES)
+		return NULL;
+
+	*result = &pm->status;
+
+	if (PageHuge(p))
+		return alloc_huge_page_node(page_hstate(compound_head(p)),
+					pm->node);
+	else
+		return __alloc_pages_node(pm->node,
+				GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0);
+}
+
+/*
+ * Move a set of pages as indicated in the pm array. The addr
+ * field must be set to the virtual address of the page to be moved
+ * and the node number must contain a valid target node.
+ * The pm array ends with node = MAX_NUMNODES.
+ */
+static int do_move_page_to_node_array(struct mm_struct *mm,
+				      struct page_to_node *pm,
+				      int migrate_all)
+{
+	int err;
+	struct page_to_node *pp;
+	LIST_HEAD(pagelist);
+
+	down_read(&mm->mmap_sem);
+
+	/*
+	 * Build a list of pages to migrate
+	 */
+	for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
+		struct vm_area_struct *vma;
+		struct page *page;
+
+		err = -EFAULT;
+		vma = find_vma(mm, pp->addr);
+		if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
+			goto set_status;
+
+		/* FOLL_DUMP to ignore special (like zero) pages */
+		page = follow_page(vma, pp->addr,
+				FOLL_GET | FOLL_SPLIT | FOLL_DUMP);
+
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto set_status;
+
+		err = -ENOENT;
+		if (!page)
+			goto set_status;
+
+		pp->page = page;
+		err = page_to_nid(page);
+
+		if (err == pp->node)
+			/*
+			 * Node already in the right place
+			 */
+			goto put_and_set;
+
+		err = -EACCES;
+		if (page_mapcount(page) > 1 &&
+				!migrate_all)
+			goto put_and_set;
+
+		if (PageHuge(page)) {
+			if (PageHead(page))
+				isolate_huge_page(page, &pagelist);
+			goto put_and_set;
+		}
+
+		err = isolate_lru_page(page);
+		if (!err) {
+			list_add_tail(&page->lru, &pagelist);
+			inc_zone_page_state(page, NR_ISOLATED_ANON +
+					    page_is_file_cache(page));
+		}
+put_and_set:
+		/*
+		 * Either remove the duplicate refcount from
+		 * isolate_lru_page() or drop the page ref if it was
+		 * not isolated.
+		 */
+		put_page(page);
+set_status:
+		pp->status = err;
+	}
+
+	err = 0;
+	if (!list_empty(&pagelist)) {
+		err = migrate_pages(&pagelist, new_page_node, NULL,
+				(unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL);
+		if (err)
+			putback_movable_pages(&pagelist);
+	}
+
+	up_read(&mm->mmap_sem);
+	return err;
+}
+
+/*
+ * Migrate an array of page address onto an array of nodes and fill
+ * the corresponding array of status.
+ */
+static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
+			 unsigned long nr_pages,
+			 const void __user * __user *pages,
+			 const int __user *nodes,
+			 int __user *status, int flags)
+{
+	struct page_to_node *pm;
+	unsigned long chunk_nr_pages;
+	unsigned long chunk_start;
+	int err;
+
+	err = -ENOMEM;
+	pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
+	if (!pm)
+		goto out;
+
+	migrate_prep();
+
+	/*
+	 * Store a chunk of page_to_node array in a page,
+	 * but keep the last one as a marker
+	 */
+	chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
+
+	for (chunk_start = 0;
+	     chunk_start < nr_pages;
+	     chunk_start += chunk_nr_pages) {
+		int j;
+
+		if (chunk_start + chunk_nr_pages > nr_pages)
+			chunk_nr_pages = nr_pages - chunk_start;
+
+		/* fill the chunk pm with addrs and nodes from user-space */
+		for (j = 0; j < chunk_nr_pages; j++) {
+			const void __user *p;
+			int node;
+
+			err = -EFAULT;
+			if (get_user(p, pages + j + chunk_start))
+				goto out_pm;
+			pm[j].addr = (unsigned long) p;
+
+			if (get_user(node, nodes + j + chunk_start))
+				goto out_pm;
+
+			err = -ENODEV;
+			if (node < 0 || node >= MAX_NUMNODES)
+				goto out_pm;
+
+			if (!node_state(node, N_MEMORY))
+				goto out_pm;
+
+			err = -EACCES;
+			if (!node_isset(node, task_nodes))
+				goto out_pm;
+
+			pm[j].node = node;
+		}
+
+		/* End marker for this chunk */
+		pm[chunk_nr_pages].node = MAX_NUMNODES;
+
+		/* Migrate this chunk */
+		err = do_move_page_to_node_array(mm, pm,
+						 flags & MPOL_MF_MOVE_ALL);
+		if (err < 0)
+			goto out_pm;
+
+		/* Return status information */
+		for (j = 0; j < chunk_nr_pages; j++)
+			if (put_user(pm[j].status, status + j + chunk_start)) {
+				err = -EFAULT;
+				goto out_pm;
+			}
+	}
+	err = 0;
+
+out_pm:
+	free_page((unsigned long)pm);
+out:
+	return err;
+}
+
+/*
+ * Determine the nodes of an array of pages and store it in an array of status.
+ */
+static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
+				const void __user **pages, int *status)
+{
+	unsigned long i;
+
+	down_read(&mm->mmap_sem);
+
+	for (i = 0; i < nr_pages; i++) {
+		unsigned long addr = (unsigned long)(*pages);
+		struct vm_area_struct *vma;
+		struct page *page;
+		int err = -EFAULT;
+
+		vma = find_vma(mm, addr);
+		if (!vma || addr < vma->vm_start)
+			goto set_status;
+
+		/* FOLL_DUMP to ignore special (like zero) pages */
+		page = follow_page(vma, addr, FOLL_DUMP);
+
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto set_status;
+
+		err = page ? page_to_nid(page) : -ENOENT;
+set_status:
+		*status = err;
+
+		pages++;
+		status++;
+	}
+
+	up_read(&mm->mmap_sem);
+}
+
+/*
+ * Determine the nodes of a user array of pages and store it in
+ * a user array of status.
+ */
+static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
+			 const void __user * __user *pages,
+			 int __user *status)
+{
+#define DO_PAGES_STAT_CHUNK_NR 16
+	const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
+	int chunk_status[DO_PAGES_STAT_CHUNK_NR];
+
+	while (nr_pages) {
+		unsigned long chunk_nr;
+
+		chunk_nr = nr_pages;
+		if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
+			chunk_nr = DO_PAGES_STAT_CHUNK_NR;
+
+		if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
+			break;
+
+		do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
+
+		if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
+			break;
+
+		pages += chunk_nr;
+		status += chunk_nr;
+		nr_pages -= chunk_nr;
+	}
+	return nr_pages ? -EFAULT : 0;
+}
+
+/*
+ * Move a list of pages in the address space of the currently executing
+ * process.
+ */
+SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
+		const void __user * __user *, pages,
+		const int __user *, nodes,
+		int __user *, status, int, flags)
+{
+	struct task_struct *task;
+	struct mm_struct *mm;
+	int err;
+	nodemask_t task_nodes;
+
+	/* Check flags */
+	if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
+		return -EINVAL;
+
+	if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
+		return -EPERM;
+
+	/* Find the mm_struct */
+	rcu_read_lock();
+	task = pid ? find_task_by_vpid(pid) : current;
+	if (!task) {
+		rcu_read_unlock();
+		return -ESRCH;
+	}
+	get_task_struct(task);
+
+	/*
+	 * Check if this process has the right to modify the specified
+	 * process. Use the regular "ptrace_may_access()" checks.
+	 */
+	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
+		rcu_read_unlock();
+		err = -EPERM;
+		goto out;
+	}
+	rcu_read_unlock();
+
+ 	err = security_task_movememory(task);
+ 	if (err)
+		goto out;
+
+	task_nodes = cpuset_mems_allowed(task);
+	mm = get_task_mm(task);
+	put_task_struct(task);
+
+	if (!mm)
+		return -EINVAL;
+
+	if (nodes)
+		err = do_pages_move(mm, task_nodes, nr_pages, pages,
+				    nodes, status, flags);
+	else
+		err = do_pages_stat(mm, nr_pages, pages, status);
+
+	mmput(mm);
+	return err;
+
+out:
+	put_task_struct(task);
+	return err;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+/*
+ * Returns true if this is a safe migration target node for misplaced NUMA
+ * pages. Currently it only checks the watermarks which crude
+ */
+static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
+				   unsigned long nr_migrate_pages)
+{
+	int z;
+	for (z = pgdat->nr_zones - 1; z >= 0; z--) {
+		struct zone *zone = pgdat->node_zones + z;
+
+		if (!populated_zone(zone))
+			continue;
+
+		if (!zone_reclaimable(zone))
+			continue;
+
+		/* Avoid waking kswapd by allocating pages_to_migrate pages. */
+		if (!zone_watermark_ok(zone, 0,
+				       high_wmark_pages(zone) +
+				       nr_migrate_pages,
+				       0, 0))
+			continue;
+		return true;
+	}
+	return false;
+}
+
+static struct page *alloc_misplaced_dst_page(struct page *page,
+					   unsigned long data,
+					   int **result)
+{
+	int nid = (int) data;
+	struct page *newpage;
+
+	newpage = __alloc_pages_node(nid,
+					 (GFP_HIGHUSER_MOVABLE |
+					  __GFP_THISNODE | __GFP_NOMEMALLOC |
+					  __GFP_NORETRY | __GFP_NOWARN) &
+					 ~__GFP_RECLAIM, 0);
+
+	return newpage;
+}
+
+/*
+ * page migration rate limiting control.
+ * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs
+ * window of time. Default here says do not migrate more than 1280M per second.
+ */
+static unsigned int migrate_interval_millisecs __read_mostly = 100;
+static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT);
+
+/* Returns true if the node is migrate rate-limited after the update */
+static bool numamigrate_update_ratelimit(pg_data_t *pgdat,
+					unsigned long nr_pages)
+{
+	/*
+	 * Rate-limit the amount of data that is being migrated to a node.
+	 * Optimal placement is no good if the memory bus is saturated and
+	 * all the time is being spent migrating!
+	 */
+	if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) {
+		spin_lock(&pgdat->numabalancing_migrate_lock);
+		pgdat->numabalancing_migrate_nr_pages = 0;
+		pgdat->numabalancing_migrate_next_window = jiffies +
+			msecs_to_jiffies(migrate_interval_millisecs);
+		spin_unlock(&pgdat->numabalancing_migrate_lock);
+	}
+	if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) {
+		trace_mm_numa_migrate_ratelimit(current, pgdat->node_id,
+								nr_pages);
+		return true;
+	}
+
+	/*
+	 * This is an unlocked non-atomic update so errors are possible.
+	 * The consequences are failing to migrate when we potentiall should
+	 * have which is not severe enough to warrant locking. If it is ever
+	 * a problem, it can be converted to a per-cpu counter.
+	 */
+	pgdat->numabalancing_migrate_nr_pages += nr_pages;
+	return false;
+}
+
+static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
+{
+	int page_lru;
+
+	VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page);
+
+	/* Avoid migrating to a node that is nearly full */
+	if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page)))
+		return 0;
+
+	if (isolate_lru_page(page))
+		return 0;
+
+	/*
+	 * migrate_misplaced_transhuge_page() skips page migration's usual
+	 * check on page_count(), so we must do it here, now that the page
+	 * has been isolated: a GUP pin, or any other pin, prevents migration.
+	 * The expected page count is 3: 1 for page's mapcount and 1 for the
+	 * caller's pin and 1 for the reference taken by isolate_lru_page().
+	 */
+	if (PageTransHuge(page) && page_count(page) != 3) {
+		putback_lru_page(page);
+		return 0;
+	}
+
+	page_lru = page_is_file_cache(page);
+	mod_zone_page_state(page_zone(page), NR_ISOLATED_ANON + page_lru,
+				hpage_nr_pages(page));
+
+	/*
+	 * Isolating the page has taken another reference, so the
+	 * caller's reference can be safely dropped without the page
+	 * disappearing underneath us during migration.
+	 */
+	put_page(page);
+	return 1;
+}
+
+bool pmd_trans_migrating(pmd_t pmd)
+{
+	struct page *page = pmd_page(pmd);
+	return PageLocked(page);
+}
+
+/*
+ * Attempt to migrate a misplaced page to the specified destination
+ * node. Caller is expected to have an elevated reference count on
+ * the page that will be dropped by this function before returning.
+ */
+int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
+			   int node)
+{
+	pg_data_t *pgdat = NODE_DATA(node);
+	int isolated;
+	int nr_remaining;
+	LIST_HEAD(migratepages);
+
+	/*
+	 * Don't migrate file pages that are mapped in multiple processes
+	 * with execute permissions as they are probably shared libraries.
+	 */
+	if (page_mapcount(page) != 1 && page_is_file_cache(page) &&
+	    (vma->vm_flags & VM_EXEC))
+		goto out;
+
+	/*
+	 * Rate-limit the amount of data that is being migrated to a node.
+	 * Optimal placement is no good if the memory bus is saturated and
+	 * all the time is being spent migrating!
+	 */
+	if (numamigrate_update_ratelimit(pgdat, 1))
+		goto out;
+
+	isolated = numamigrate_isolate_page(pgdat, page);
+	if (!isolated)
+		goto out;
+
+	list_add(&page->lru, &migratepages);
+	nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
+				     NULL, node, MIGRATE_ASYNC,
+				     MR_NUMA_MISPLACED);
+	if (nr_remaining) {
+		if (!list_empty(&migratepages)) {
+			list_del(&page->lru);
+			dec_zone_page_state(page, NR_ISOLATED_ANON +
+					page_is_file_cache(page));
+			putback_lru_page(page);
+		}
+		isolated = 0;
+	} else
+		count_vm_numa_event(NUMA_PAGE_MIGRATE);
+	BUG_ON(!list_empty(&migratepages));
+	return isolated;
+
+out:
+	put_page(page);
+	return 0;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+/*
+ * Migrates a THP to a given target node. page must be locked and is unlocked
+ * before returning.
+ */
+int migrate_misplaced_transhuge_page(struct mm_struct *mm,
+				struct vm_area_struct *vma,
+				pmd_t *pmd, pmd_t entry,
+				unsigned long address,
+				struct page *page, int node)
+{
+	spinlock_t *ptl;
+	pg_data_t *pgdat = NODE_DATA(node);
+	int isolated = 0;
+	struct page *new_page = NULL;
+	int page_lru = page_is_file_cache(page);
+	unsigned long mmun_start = address & HPAGE_PMD_MASK;
+	unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE;
+	pmd_t orig_entry;
+
+	/*
+	 * Rate-limit the amount of data that is being migrated to a node.
+	 * Optimal placement is no good if the memory bus is saturated and
+	 * all the time is being spent migrating!
+	 */
+	if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR))
+		goto out_dropref;
+
+	new_page = alloc_pages_node(node,
+		(GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM,
+		HPAGE_PMD_ORDER);
+	if (!new_page)
+		goto out_fail;
+
+	isolated = numamigrate_isolate_page(pgdat, page);
+	if (!isolated) {
+		put_page(new_page);
+		goto out_fail;
+	}
+
+	if (mm_tlb_flush_pending(mm))
+		flush_tlb_range(vma, mmun_start, mmun_end);
+
+	/* Prepare a page as a migration target */
+	__set_page_locked(new_page);
+	SetPageSwapBacked(new_page);
+
+	/* anon mapping, we can simply copy page->mapping to the new page: */
+	new_page->mapping = page->mapping;
+	new_page->index = page->index;
+	migrate_page_copy(new_page, page);
+	WARN_ON(PageLRU(new_page));
+
+	/* Recheck the target PMD */
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	ptl = pmd_lock(mm, pmd);
+	if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) {
+fail_putback:
+		spin_unlock(ptl);
+		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+		/* Reverse changes made by migrate_page_copy() */
+		if (TestClearPageActive(new_page))
+			SetPageActive(page);
+		if (TestClearPageUnevictable(new_page))
+			SetPageUnevictable(page);
+
+		unlock_page(new_page);
+		put_page(new_page);		/* Free it */
+
+		/* Retake the callers reference and putback on LRU */
+		get_page(page);
+		putback_lru_page(page);
+		mod_zone_page_state(page_zone(page),
+			 NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR);
+
+		goto out_unlock;
+	}
+
+	orig_entry = *pmd;
+	entry = mk_pmd(new_page, vma->vm_page_prot);
+	entry = pmd_mkhuge(entry);
+	entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+
+	/*
+	 * Clear the old entry under pagetable lock and establish the new PTE.
+	 * Any parallel GUP will either observe the old page blocking on the
+	 * page lock, block on the page table lock or observe the new page.
+	 * The SetPageUptodate on the new page and page_add_new_anon_rmap
+	 * guarantee the copy is visible before the pagetable update.
+	 */
+	flush_cache_range(vma, mmun_start, mmun_end);
+	page_add_anon_rmap(new_page, vma, mmun_start);
+	pmdp_huge_clear_flush_notify(vma, mmun_start, pmd);
+	set_pmd_at(mm, mmun_start, pmd, entry);
+	flush_tlb_range(vma, mmun_start, mmun_end);
+	update_mmu_cache_pmd(vma, address, &entry);
+
+	if (page_count(page) != 2) {
+		set_pmd_at(mm, mmun_start, pmd, orig_entry);
+		flush_tlb_range(vma, mmun_start, mmun_end);
+		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
+		update_mmu_cache_pmd(vma, address, &entry);
+		page_remove_rmap(new_page);
+		goto fail_putback;
+	}
+
+	mlock_migrate_page(new_page, page);
+	set_page_memcg(new_page, page_memcg(page));
+	set_page_memcg(page, NULL);
+	page_remove_rmap(page);
+
+	spin_unlock(ptl);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+	/* Take an "isolate" reference and put new page on the LRU. */
+	get_page(new_page);
+	putback_lru_page(new_page);
+
+	unlock_page(new_page);
+	unlock_page(page);
+	put_page(page);			/* Drop the rmap reference */
+	put_page(page);			/* Drop the LRU isolation reference */
+
+	count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR);
+	count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR);
+
+	mod_zone_page_state(page_zone(page),
+			NR_ISOLATED_ANON + page_lru,
+			-HPAGE_PMD_NR);
+	return isolated;
+
+out_fail:
+	count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
+out_dropref:
+	ptl = pmd_lock(mm, pmd);
+	if (pmd_same(*pmd, entry)) {
+		entry = pmd_modify(entry, vma->vm_page_prot);
+		set_pmd_at(mm, mmun_start, pmd, entry);
+		update_mmu_cache_pmd(vma, address, &entry);
+	}
+	spin_unlock(ptl);
+
+out_unlock:
+	unlock_page(page);
+	put_page(page);
+	return 0;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+#endif /* CONFIG_NUMA */
diff --git a/mm/mincore.c b/mm/mincore.c
new file mode 100644
index 0000000..14bb9fb
--- /dev/null
+++ b/mm/mincore.c
@@ -0,0 +1,269 @@
+/*
+ *	linux/mm/mincore.c
+ *
+ * Copyright (C) 1994-2006  Linus Torvalds
+ */
+
+/*
+ * The mincore() system call.
+ */
+#include <linux/pagemap.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/syscalls.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/hugetlb.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+
+static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
+			unsigned long end, struct mm_walk *walk)
+{
+#ifdef CONFIG_HUGETLB_PAGE
+	unsigned char present;
+	unsigned char *vec = walk->private;
+
+	/*
+	 * Hugepages under user process are always in RAM and never
+	 * swapped out, but theoretically it needs to be checked.
+	 */
+	present = pte && !huge_pte_none(huge_ptep_get(pte));
+	for (; addr != end; vec++, addr += PAGE_SIZE)
+		*vec = present;
+	walk->private = vec;
+#else
+	BUG();
+#endif
+	return 0;
+}
+
+/*
+ * Later we can get more picky about what "in core" means precisely.
+ * For now, simply check to see if the page is in the page cache,
+ * and is up to date; i.e. that no page-in operation would be required
+ * at this time if an application were to map and access this page.
+ */
+static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
+{
+	unsigned char present = 0;
+	struct page *page;
+
+	/*
+	 * When tmpfs swaps out a page from a file, any process mapping that
+	 * file will not get a swp_entry_t in its pte, but rather it is like
+	 * any other file mapping (ie. marked !present and faulted in with
+	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
+	 */
+#ifdef CONFIG_SWAP
+	if (shmem_mapping(mapping)) {
+		page = find_get_entry(mapping, pgoff);
+		/*
+		 * shmem/tmpfs may return swap: account for swapcache
+		 * page too.
+		 */
+		if (radix_tree_exceptional_entry(page)) {
+			swp_entry_t swp = radix_to_swp_entry(page);
+			page = find_get_page(swap_address_space(swp), swp.val);
+		}
+	} else
+		page = find_get_page(mapping, pgoff);
+#else
+	page = find_get_page(mapping, pgoff);
+#endif
+	if (page) {
+		present = PageUptodate(page);
+		page_cache_release(page);
+	}
+
+	return present;
+}
+
+static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
+				struct vm_area_struct *vma, unsigned char *vec)
+{
+	unsigned long nr = (end - addr) >> PAGE_SHIFT;
+	int i;
+
+	if (vma->vm_file) {
+		pgoff_t pgoff;
+
+		pgoff = linear_page_index(vma, addr);
+		for (i = 0; i < nr; i++, pgoff++)
+			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
+	} else {
+		for (i = 0; i < nr; i++)
+			vec[i] = 0;
+	}
+	return nr;
+}
+
+static int mincore_unmapped_range(unsigned long addr, unsigned long end,
+				   struct mm_walk *walk)
+{
+	walk->private += __mincore_unmapped_range(addr, end,
+						  walk->vma, walk->private);
+	return 0;
+}
+
+static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+			struct mm_walk *walk)
+{
+	spinlock_t *ptl;
+	struct vm_area_struct *vma = walk->vma;
+	pte_t *ptep;
+	unsigned char *vec = walk->private;
+	int nr = (end - addr) >> PAGE_SHIFT;
+
+	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+		memset(vec, 1, nr);
+		spin_unlock(ptl);
+		goto out;
+	}
+
+	if (pmd_trans_unstable(pmd)) {
+		__mincore_unmapped_range(addr, end, vma, vec);
+		goto out;
+	}
+
+	ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+	for (; addr != end; ptep++, addr += PAGE_SIZE) {
+		pte_t pte = *ptep;
+
+		if (pte_none(pte))
+			__mincore_unmapped_range(addr, addr + PAGE_SIZE,
+						 vma, vec);
+		else if (pte_present(pte))
+			*vec = 1;
+		else { /* pte is a swap entry */
+			swp_entry_t entry = pte_to_swp_entry(pte);
+
+			if (non_swap_entry(entry)) {
+				/*
+				 * migration or hwpoison entries are always
+				 * uptodate
+				 */
+				*vec = 1;
+			} else {
+#ifdef CONFIG_SWAP
+				*vec = mincore_page(swap_address_space(entry),
+					entry.val);
+#else
+				WARN_ON(1);
+				*vec = 1;
+#endif
+			}
+		}
+		vec++;
+	}
+	pte_unmap_unlock(ptep - 1, ptl);
+out:
+	walk->private += nr;
+	cond_resched();
+	return 0;
+}
+
+/*
+ * Do a chunk of "sys_mincore()". We've already checked
+ * all the arguments, we hold the mmap semaphore: we should
+ * just return the amount of info we're asked for.
+ */
+static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
+{
+	struct vm_area_struct *vma;
+	unsigned long end;
+	int err;
+	struct mm_walk mincore_walk = {
+		.pmd_entry = mincore_pte_range,
+		.pte_hole = mincore_unmapped_range,
+		.hugetlb_entry = mincore_hugetlb,
+		.private = vec,
+	};
+
+	vma = find_vma(current->mm, addr);
+	if (!vma || addr < vma->vm_start)
+		return -ENOMEM;
+	mincore_walk.mm = vma->vm_mm;
+	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
+	err = walk_page_range(addr, end, &mincore_walk);
+	if (err < 0)
+		return err;
+	return (end - addr) >> PAGE_SHIFT;
+}
+
+/*
+ * The mincore(2) system call.
+ *
+ * mincore() returns the memory residency status of the pages in the
+ * current process's address space specified by [addr, addr + len).
+ * The status is returned in a vector of bytes.  The least significant
+ * bit of each byte is 1 if the referenced page is in memory, otherwise
+ * it is zero.
+ *
+ * Because the status of a page can change after mincore() checks it
+ * but before it returns to the application, the returned vector may
+ * contain stale information.  Only locked pages are guaranteed to
+ * remain in memory.
+ *
+ * return values:
+ *  zero    - success
+ *  -EFAULT - vec points to an illegal address
+ *  -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
+ *  -ENOMEM - Addresses in the range [addr, addr + len] are
+ *		invalid for the address space of this process, or
+ *		specify one or more pages which are not currently
+ *		mapped
+ *  -EAGAIN - A kernel resource was temporarily unavailable.
+ */
+SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
+		unsigned char __user *, vec)
+{
+	long retval;
+	unsigned long pages;
+	unsigned char *tmp;
+
+	/* Check the start address: needs to be page-aligned.. */
+ 	if (start & ~PAGE_CACHE_MASK)
+		return -EINVAL;
+
+	/* ..and we need to be passed a valid user-space range */
+	if (!access_ok(VERIFY_READ, (void __user *) start, len))
+		return -ENOMEM;
+
+	/* This also avoids any overflows on PAGE_CACHE_ALIGN */
+	pages = len >> PAGE_SHIFT;
+	pages += (offset_in_page(len)) != 0;
+
+	if (!access_ok(VERIFY_WRITE, vec, pages))
+		return -EFAULT;
+
+	tmp = (void *) __get_free_page(GFP_USER);
+	if (!tmp)
+		return -EAGAIN;
+
+	retval = 0;
+	while (pages) {
+		/*
+		 * Do at most PAGE_SIZE entries per iteration, due to
+		 * the temporary buffer size.
+		 */
+		down_read(&current->mm->mmap_sem);
+		retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
+		up_read(&current->mm->mmap_sem);
+
+		if (retval <= 0)
+			break;
+		if (copy_to_user(vec, tmp, retval)) {
+			retval = -EFAULT;
+			break;
+		}
+		pages -= retval;
+		vec += retval;
+		start += retval << PAGE_SHIFT;
+		retval = 0;
+	}
+	free_page((unsigned long) tmp);
+	return retval;
+}
diff --git a/mm/mlock.c b/mm/mlock.c
new file mode 100644
index 0000000..9d2e773
--- /dev/null
+++ b/mm/mlock.c
@@ -0,0 +1,796 @@
+/*
+ *	linux/mm/mlock.c
+ *
+ *  (C) Copyright 1995 Linus Torvalds
+ *  (C) Copyright 2002 Christoph Hellwig
+ */
+
+#include <linux/capability.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/mempolicy.h>
+#include <linux/syscalls.h>
+#include <linux/sched.h>
+#include <linux/export.h>
+#include <linux/rmap.h>
+#include <linux/mmzone.h>
+#include <linux/hugetlb.h>
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
+
+#include "internal.h"
+
+int can_do_mlock(void)
+{
+	if (rlimit(RLIMIT_MEMLOCK) != 0)
+		return 1;
+	if (capable(CAP_IPC_LOCK))
+		return 1;
+	return 0;
+}
+EXPORT_SYMBOL(can_do_mlock);
+
+/*
+ * Mlocked pages are marked with PageMlocked() flag for efficient testing
+ * in vmscan and, possibly, the fault path; and to support semi-accurate
+ * statistics.
+ *
+ * An mlocked page [PageMlocked(page)] is unevictable.  As such, it will
+ * be placed on the LRU "unevictable" list, rather than the [in]active lists.
+ * The unevictable list is an LRU sibling list to the [in]active lists.
+ * PageUnevictable is set to indicate the unevictable state.
+ *
+ * When lazy mlocking via vmscan, it is important to ensure that the
+ * vma's VM_LOCKED status is not concurrently being modified, otherwise we
+ * may have mlocked a page that is being munlocked. So lazy mlock must take
+ * the mmap_sem for read, and verify that the vma really is locked
+ * (see mm/rmap.c).
+ */
+
+/*
+ *  LRU accounting for clear_page_mlock()
+ */
+void clear_page_mlock(struct page *page)
+{
+	if (!TestClearPageMlocked(page))
+		return;
+
+	mod_zone_page_state(page_zone(page), NR_MLOCK,
+			    -hpage_nr_pages(page));
+	count_vm_event(UNEVICTABLE_PGCLEARED);
+	if (!isolate_lru_page(page)) {
+		putback_lru_page(page);
+	} else {
+		/*
+		 * We lost the race. the page already moved to evictable list.
+		 */
+		if (PageUnevictable(page))
+			count_vm_event(UNEVICTABLE_PGSTRANDED);
+	}
+}
+
+/*
+ * Mark page as mlocked if not already.
+ * If page on LRU, isolate and putback to move to unevictable list.
+ */
+void mlock_vma_page(struct page *page)
+{
+	/* Serialize with page migration */
+	BUG_ON(!PageLocked(page));
+
+	if (!TestSetPageMlocked(page)) {
+		mod_zone_page_state(page_zone(page), NR_MLOCK,
+				    hpage_nr_pages(page));
+		count_vm_event(UNEVICTABLE_PGMLOCKED);
+		if (!isolate_lru_page(page))
+			putback_lru_page(page);
+	}
+}
+
+/*
+ * Isolate a page from LRU with optional get_page() pin.
+ * Assumes lru_lock already held and page already pinned.
+ */
+static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
+{
+	if (PageLRU(page)) {
+		struct lruvec *lruvec;
+
+		lruvec = mem_cgroup_page_lruvec(page, page_zone(page));
+		if (getpage)
+			get_page(page);
+		ClearPageLRU(page);
+		del_page_from_lru_list(page, lruvec, page_lru(page));
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Finish munlock after successful page isolation
+ *
+ * Page must be locked. This is a wrapper for try_to_munlock()
+ * and putback_lru_page() with munlock accounting.
+ */
+static void __munlock_isolated_page(struct page *page)
+{
+	int ret = SWAP_AGAIN;
+
+	/*
+	 * Optimization: if the page was mapped just once, that's our mapping
+	 * and we don't need to check all the other vmas.
+	 */
+	if (page_mapcount(page) > 1)
+		ret = try_to_munlock(page);
+
+	/* Did try_to_unlock() succeed or punt? */
+	if (ret != SWAP_MLOCK)
+		count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
+	putback_lru_page(page);
+}
+
+/*
+ * Accounting for page isolation fail during munlock
+ *
+ * Performs accounting when page isolation fails in munlock. There is nothing
+ * else to do because it means some other task has already removed the page
+ * from the LRU. putback_lru_page() will take care of removing the page from
+ * the unevictable list, if necessary. vmscan [page_referenced()] will move
+ * the page back to the unevictable list if some other vma has it mlocked.
+ */
+static void __munlock_isolation_failed(struct page *page)
+{
+	if (PageUnevictable(page))
+		__count_vm_event(UNEVICTABLE_PGSTRANDED);
+	else
+		__count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+}
+
+/**
+ * munlock_vma_page - munlock a vma page
+ * @page - page to be unlocked, either a normal page or THP page head
+ *
+ * returns the size of the page as a page mask (0 for normal page,
+ *         HPAGE_PMD_NR - 1 for THP head page)
+ *
+ * called from munlock()/munmap() path with page supposedly on the LRU.
+ * When we munlock a page, because the vma where we found the page is being
+ * munlock()ed or munmap()ed, we want to check whether other vmas hold the
+ * page locked so that we can leave it on the unevictable lru list and not
+ * bother vmscan with it.  However, to walk the page's rmap list in
+ * try_to_munlock() we must isolate the page from the LRU.  If some other
+ * task has removed the page from the LRU, we won't be able to do that.
+ * So we clear the PageMlocked as we might not get another chance.  If we
+ * can't isolate the page, we leave it for putback_lru_page() and vmscan
+ * [page_referenced()/try_to_unmap()] to deal with.
+ */
+unsigned int munlock_vma_page(struct page *page)
+{
+	int nr_pages;
+	struct zone *zone = page_zone(page);
+
+	/* For try_to_munlock() and to serialize with page migration */
+	BUG_ON(!PageLocked(page));
+
+	/*
+	 * Serialize with any parallel __split_huge_page_refcount() which
+	 * might otherwise copy PageMlocked to part of the tail pages before
+	 * we clear it in the head page. It also stabilizes hpage_nr_pages().
+	 */
+	spin_lock_irq(&zone->lru_lock);
+
+	nr_pages = hpage_nr_pages(page);
+	if (!TestClearPageMlocked(page))
+		goto unlock_out;
+
+	__mod_zone_page_state(zone, NR_MLOCK, -nr_pages);
+
+	if (__munlock_isolate_lru_page(page, true)) {
+		spin_unlock_irq(&zone->lru_lock);
+		__munlock_isolated_page(page);
+		goto out;
+	}
+	__munlock_isolation_failed(page);
+
+unlock_out:
+	spin_unlock_irq(&zone->lru_lock);
+
+out:
+	return nr_pages - 1;
+}
+
+/*
+ * convert get_user_pages() return value to posix mlock() error
+ */
+static int __mlock_posix_error_return(long retval)
+{
+	if (retval == -EFAULT)
+		retval = -ENOMEM;
+	else if (retval == -ENOMEM)
+		retval = -EAGAIN;
+	return retval;
+}
+
+/*
+ * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
+ *
+ * The fast path is available only for evictable pages with single mapping.
+ * Then we can bypass the per-cpu pvec and get better performance.
+ * when mapcount > 1 we need try_to_munlock() which can fail.
+ * when !page_evictable(), we need the full redo logic of putback_lru_page to
+ * avoid leaving evictable page in unevictable list.
+ *
+ * In case of success, @page is added to @pvec and @pgrescued is incremented
+ * in case that the page was previously unevictable. @page is also unlocked.
+ */
+static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec,
+		int *pgrescued)
+{
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+	if (page_mapcount(page) <= 1 && page_evictable(page)) {
+		pagevec_add(pvec, page);
+		if (TestClearPageUnevictable(page))
+			(*pgrescued)++;
+		unlock_page(page);
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Putback multiple evictable pages to the LRU
+ *
+ * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
+ * the pages might have meanwhile become unevictable but that is OK.
+ */
+static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
+{
+	count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
+	/*
+	 *__pagevec_lru_add() calls release_pages() so we don't call
+	 * put_page() explicitly
+	 */
+	__pagevec_lru_add(pvec);
+	count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
+}
+
+/*
+ * Munlock a batch of pages from the same zone
+ *
+ * The work is split to two main phases. First phase clears the Mlocked flag
+ * and attempts to isolate the pages, all under a single zone lru lock.
+ * The second phase finishes the munlock only for pages where isolation
+ * succeeded.
+ *
+ * Note that the pagevec may be modified during the process.
+ */
+static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
+{
+	int i;
+	int nr = pagevec_count(pvec);
+	int delta_munlocked = -nr;
+	struct pagevec pvec_putback;
+	int pgrescued = 0;
+
+	pagevec_init(&pvec_putback, 0);
+
+	/* Phase 1: page isolation */
+	spin_lock_irq(&zone->lru_lock);
+	for (i = 0; i < nr; i++) {
+		struct page *page = pvec->pages[i];
+
+		if (TestClearPageMlocked(page)) {
+			/*
+			 * We already have pin from follow_page_mask()
+			 * so we can spare the get_page() here.
+			 */
+			if (__munlock_isolate_lru_page(page, false))
+				continue;
+			else
+				__munlock_isolation_failed(page);
+		} else {
+			delta_munlocked++;
+		}
+
+		/*
+		 * We won't be munlocking this page in the next phase
+		 * but we still need to release the follow_page_mask()
+		 * pin. We cannot do it under lru_lock however. If it's
+		 * the last pin, __page_cache_release() would deadlock.
+		 */
+		pagevec_add(&pvec_putback, pvec->pages[i]);
+		pvec->pages[i] = NULL;
+	}
+	__mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
+	spin_unlock_irq(&zone->lru_lock);
+
+	/* Now we can release pins of pages that we are not munlocking */
+	pagevec_release(&pvec_putback);
+
+	/* Phase 2: page munlock */
+	for (i = 0; i < nr; i++) {
+		struct page *page = pvec->pages[i];
+
+		if (page) {
+			lock_page(page);
+			if (!__putback_lru_fast_prepare(page, &pvec_putback,
+					&pgrescued)) {
+				/*
+				 * Slow path. We don't want to lose the last
+				 * pin before unlock_page()
+				 */
+				get_page(page); /* for putback_lru_page() */
+				__munlock_isolated_page(page);
+				unlock_page(page);
+				put_page(page); /* from follow_page_mask() */
+			}
+		}
+	}
+
+	/*
+	 * Phase 3: page putback for pages that qualified for the fast path
+	 * This will also call put_page() to return pin from follow_page_mask()
+	 */
+	if (pagevec_count(&pvec_putback))
+		__putback_lru_fast(&pvec_putback, pgrescued);
+}
+
+/*
+ * Fill up pagevec for __munlock_pagevec using pte walk
+ *
+ * The function expects that the struct page corresponding to @start address is
+ * a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
+ *
+ * The rest of @pvec is filled by subsequent pages within the same pmd and same
+ * zone, as long as the pte's are present and vm_normal_page() succeeds. These
+ * pages also get pinned.
+ *
+ * Returns the address of the next page that should be scanned. This equals
+ * @start + PAGE_SIZE when no page could be added by the pte walk.
+ */
+static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
+		struct vm_area_struct *vma, int zoneid,	unsigned long start,
+		unsigned long end)
+{
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	/*
+	 * Initialize pte walk starting at the already pinned page where we
+	 * are sure that there is a pte, as it was pinned under the same
+	 * mmap_sem write op.
+	 */
+	pte = get_locked_pte(vma->vm_mm, start,	&ptl);
+	/* Make sure we do not cross the page table boundary */
+	end = pgd_addr_end(start, end);
+	end = pud_addr_end(start, end);
+	end = pmd_addr_end(start, end);
+
+	/* The page next to the pinned page is the first we will try to get */
+	start += PAGE_SIZE;
+	while (start < end) {
+		struct page *page = NULL;
+		pte++;
+		if (pte_present(*pte))
+			page = vm_normal_page(vma, start, *pte);
+		/*
+		 * Break if page could not be obtained or the page's node+zone does not
+		 * match
+		 */
+		if (!page || page_zone_id(page) != zoneid)
+			break;
+
+		get_page(page);
+		/*
+		 * Increase the address that will be returned *before* the
+		 * eventual break due to pvec becoming full by adding the page
+		 */
+		start += PAGE_SIZE;
+		if (pagevec_add(pvec, page) == 0)
+			break;
+	}
+	pte_unmap_unlock(pte, ptl);
+	return start;
+}
+
+/*
+ * munlock_vma_pages_range() - munlock all pages in the vma range.'
+ * @vma - vma containing range to be munlock()ed.
+ * @start - start address in @vma of the range
+ * @end - end of range in @vma.
+ *
+ *  For mremap(), munmap() and exit().
+ *
+ * Called with @vma VM_LOCKED.
+ *
+ * Returns with VM_LOCKED cleared.  Callers must be prepared to
+ * deal with this.
+ *
+ * We don't save and restore VM_LOCKED here because pages are
+ * still on lru.  In unmap path, pages might be scanned by reclaim
+ * and re-mlocked by try_to_{munlock|unmap} before we unmap and
+ * free them.  This will result in freeing mlocked pages.
+ */
+void munlock_vma_pages_range(struct vm_area_struct *vma,
+			     unsigned long start, unsigned long end)
+{
+	vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+
+	while (start < end) {
+		struct page *page = NULL;
+		unsigned int page_mask;
+		unsigned long page_increm;
+		struct pagevec pvec;
+		struct zone *zone;
+		int zoneid;
+
+		pagevec_init(&pvec, 0);
+		/*
+		 * Although FOLL_DUMP is intended for get_dump_page(),
+		 * it just so happens that its special treatment of the
+		 * ZERO_PAGE (returning an error instead of doing get_page)
+		 * suits munlock very well (and if somehow an abnormal page
+		 * has sneaked into the range, we won't oops here: great).
+		 */
+		page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP,
+				&page_mask);
+
+		if (page && !IS_ERR(page)) {
+			if (PageTransHuge(page)) {
+				lock_page(page);
+				/*
+				 * Any THP page found by follow_page_mask() may
+				 * have gotten split before reaching
+				 * munlock_vma_page(), so we need to recompute
+				 * the page_mask here.
+				 */
+				page_mask = munlock_vma_page(page);
+				unlock_page(page);
+				put_page(page); /* follow_page_mask() */
+			} else {
+				/*
+				 * Non-huge pages are handled in batches via
+				 * pagevec. The pin from follow_page_mask()
+				 * prevents them from collapsing by THP.
+				 */
+				pagevec_add(&pvec, page);
+				zone = page_zone(page);
+				zoneid = page_zone_id(page);
+
+				/*
+				 * Try to fill the rest of pagevec using fast
+				 * pte walk. This will also update start to
+				 * the next page to process. Then munlock the
+				 * pagevec.
+				 */
+				start = __munlock_pagevec_fill(&pvec, vma,
+						zoneid, start, end);
+				__munlock_pagevec(&pvec, zone);
+				goto next;
+			}
+		}
+		/* It's a bug to munlock in the middle of a THP page */
+		VM_BUG_ON((start >> PAGE_SHIFT) & page_mask);
+		page_increm = 1 + page_mask;
+		start += page_increm * PAGE_SIZE;
+next:
+		cond_resched();
+	}
+}
+
+/*
+ * mlock_fixup  - handle mlock[all]/munlock[all] requests.
+ *
+ * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
+ * munlock is a no-op.  However, for some special vmas, we go ahead and
+ * populate the ptes.
+ *
+ * For vmas that pass the filters, merge/split as appropriate.
+ */
+static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
+	unsigned long start, unsigned long end, vm_flags_t newflags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pgoff_t pgoff;
+	int nr_pages;
+	int ret = 0;
+	int lock = !!(newflags & VM_LOCKED);
+
+	if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
+	    is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
+		/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
+		goto out;
+
+	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+	*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
+			  vma->vm_file, pgoff, vma_policy(vma),
+			  vma->vm_userfaultfd_ctx);
+	if (*prev) {
+		vma = *prev;
+		goto success;
+	}
+
+	if (start != vma->vm_start) {
+		ret = split_vma(mm, vma, start, 1);
+		if (ret)
+			goto out;
+	}
+
+	if (end != vma->vm_end) {
+		ret = split_vma(mm, vma, end, 0);
+		if (ret)
+			goto out;
+	}
+
+success:
+	/*
+	 * Keep track of amount of locked VM.
+	 */
+	nr_pages = (end - start) >> PAGE_SHIFT;
+	if (!lock)
+		nr_pages = -nr_pages;
+	mm->locked_vm += nr_pages;
+
+	/*
+	 * vm_flags is protected by the mmap_sem held in write mode.
+	 * It's okay if try_to_unmap_one unmaps a page just after we
+	 * set VM_LOCKED, populate_vma_page_range will bring it back.
+	 */
+
+	if (lock)
+		vma->vm_flags = newflags;
+	else
+		munlock_vma_pages_range(vma, start, end);
+
+out:
+	*prev = vma;
+	return ret;
+}
+
+static int apply_vma_lock_flags(unsigned long start, size_t len,
+				vm_flags_t flags)
+{
+	unsigned long nstart, end, tmp;
+	struct vm_area_struct * vma, * prev;
+	int error;
+
+	VM_BUG_ON(offset_in_page(start));
+	VM_BUG_ON(len != PAGE_ALIGN(len));
+	end = start + len;
+	if (end < start)
+		return -EINVAL;
+	if (end == start)
+		return 0;
+	vma = find_vma(current->mm, start);
+	if (!vma || vma->vm_start > start)
+		return -ENOMEM;
+
+	prev = vma->vm_prev;
+	if (start > vma->vm_start)
+		prev = vma;
+
+	for (nstart = start ; ; ) {
+		vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
+
+		newflags |= flags;
+
+		/* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
+		tmp = vma->vm_end;
+		if (tmp > end)
+			tmp = end;
+		error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
+		if (error)
+			break;
+		nstart = tmp;
+		if (nstart < prev->vm_end)
+			nstart = prev->vm_end;
+		if (nstart >= end)
+			break;
+
+		vma = prev->vm_next;
+		if (!vma || vma->vm_start != nstart) {
+			error = -ENOMEM;
+			break;
+		}
+	}
+	return error;
+}
+
+static int do_mlock(unsigned long start, size_t len, vm_flags_t flags)
+{
+	unsigned long locked;
+	unsigned long lock_limit;
+	int error = -ENOMEM;
+
+	if (!can_do_mlock())
+		return -EPERM;
+
+	lru_add_drain_all();	/* flush pagevec */
+
+	len = PAGE_ALIGN(len + (offset_in_page(start)));
+	start &= PAGE_MASK;
+
+	lock_limit = rlimit(RLIMIT_MEMLOCK);
+	lock_limit >>= PAGE_SHIFT;
+	locked = len >> PAGE_SHIFT;
+
+	down_write(&current->mm->mmap_sem);
+
+	locked += current->mm->locked_vm;
+
+	/* check against resource limits */
+	if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
+		error = apply_vma_lock_flags(start, len, flags);
+
+	up_write(&current->mm->mmap_sem);
+	if (error)
+		return error;
+
+	error = __mm_populate(start, len, 0);
+	if (error)
+		return __mlock_posix_error_return(error);
+	return 0;
+}
+
+SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
+{
+	return do_mlock(start, len, VM_LOCKED);
+}
+
+SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
+{
+	vm_flags_t vm_flags = VM_LOCKED;
+
+	if (flags & ~MLOCK_ONFAULT)
+		return -EINVAL;
+
+	if (flags & MLOCK_ONFAULT)
+		vm_flags |= VM_LOCKONFAULT;
+
+	return do_mlock(start, len, vm_flags);
+}
+
+SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
+{
+	int ret;
+
+	len = PAGE_ALIGN(len + (offset_in_page(start)));
+	start &= PAGE_MASK;
+
+	down_write(&current->mm->mmap_sem);
+	ret = apply_vma_lock_flags(start, len, 0);
+	up_write(&current->mm->mmap_sem);
+
+	return ret;
+}
+
+/*
+ * Take the MCL_* flags passed into mlockall (or 0 if called from munlockall)
+ * and translate into the appropriate modifications to mm->def_flags and/or the
+ * flags for all current VMAs.
+ *
+ * There are a couple of subtleties with this.  If mlockall() is called multiple
+ * times with different flags, the values do not necessarily stack.  If mlockall
+ * is called once including the MCL_FUTURE flag and then a second time without
+ * it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags.
+ */
+static int apply_mlockall_flags(int flags)
+{
+	struct vm_area_struct * vma, * prev = NULL;
+	vm_flags_t to_add = 0;
+
+	current->mm->def_flags &= VM_LOCKED_CLEAR_MASK;
+	if (flags & MCL_FUTURE) {
+		current->mm->def_flags |= VM_LOCKED;
+
+		if (flags & MCL_ONFAULT)
+			current->mm->def_flags |= VM_LOCKONFAULT;
+
+		if (!(flags & MCL_CURRENT))
+			goto out;
+	}
+
+	if (flags & MCL_CURRENT) {
+		to_add |= VM_LOCKED;
+		if (flags & MCL_ONFAULT)
+			to_add |= VM_LOCKONFAULT;
+	}
+
+	for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
+		vm_flags_t newflags;
+
+		newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
+		newflags |= to_add;
+
+		/* Ignore errors */
+		mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
+		cond_resched_rcu_qs();
+	}
+out:
+	return 0;
+}
+
+SYSCALL_DEFINE1(mlockall, int, flags)
+{
+	unsigned long lock_limit;
+	int ret;
+
+	if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)))
+		return -EINVAL;
+
+	if (!can_do_mlock())
+		return -EPERM;
+
+	if (flags & MCL_CURRENT)
+		lru_add_drain_all();	/* flush pagevec */
+
+	lock_limit = rlimit(RLIMIT_MEMLOCK);
+	lock_limit >>= PAGE_SHIFT;
+
+	ret = -ENOMEM;
+	down_write(&current->mm->mmap_sem);
+
+	if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
+	    capable(CAP_IPC_LOCK))
+		ret = apply_mlockall_flags(flags);
+	up_write(&current->mm->mmap_sem);
+	if (!ret && (flags & MCL_CURRENT))
+		mm_populate(0, TASK_SIZE);
+
+	return ret;
+}
+
+SYSCALL_DEFINE0(munlockall)
+{
+	int ret;
+
+	down_write(&current->mm->mmap_sem);
+	ret = apply_mlockall_flags(0);
+	up_write(&current->mm->mmap_sem);
+	return ret;
+}
+
+/*
+ * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
+ * shm segments) get accounted against the user_struct instead.
+ */
+static DEFINE_SPINLOCK(shmlock_user_lock);
+
+int user_shm_lock(size_t size, struct user_struct *user)
+{
+	unsigned long lock_limit, locked;
+	int allowed = 0;
+
+	locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	lock_limit = rlimit(RLIMIT_MEMLOCK);
+	if (lock_limit == RLIM_INFINITY)
+		allowed = 1;
+	lock_limit >>= PAGE_SHIFT;
+	spin_lock(&shmlock_user_lock);
+	if (!allowed &&
+	    locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
+		goto out;
+	get_uid(user);
+	user->locked_shm += locked;
+	allowed = 1;
+out:
+	spin_unlock(&shmlock_user_lock);
+	return allowed;
+}
+
+void user_shm_unlock(size_t size, struct user_struct *user)
+{
+	spin_lock(&shmlock_user_lock);
+	user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	spin_unlock(&shmlock_user_lock);
+	free_uid(user);
+}
diff --git a/mm/mm_init.c b/mm/mm_init.c
new file mode 100644
index 0000000..fdadf91
--- /dev/null
+++ b/mm/mm_init.c
@@ -0,0 +1,198 @@
+/*
+ * mm_init.c - Memory initialisation verification and debugging
+ *
+ * Copyright 2008 IBM Corporation, 2008
+ * Author Mel Gorman <mel@csn.ul.ie>
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/kobject.h>
+#include <linux/export.h>
+#include <linux/memory.h>
+#include <linux/notifier.h>
+#include <linux/sched.h>
+#include "internal.h"
+
+#ifdef CONFIG_DEBUG_MEMORY_INIT
+int __meminitdata mminit_loglevel;
+
+#ifndef SECTIONS_SHIFT
+#define SECTIONS_SHIFT	0
+#endif
+
+/* The zonelists are simply reported, validation is manual. */
+void __init mminit_verify_zonelist(void)
+{
+	int nid;
+
+	if (mminit_loglevel < MMINIT_VERIFY)
+		return;
+
+	for_each_online_node(nid) {
+		pg_data_t *pgdat = NODE_DATA(nid);
+		struct zone *zone;
+		struct zoneref *z;
+		struct zonelist *zonelist;
+		int i, listid, zoneid;
+
+		BUG_ON(MAX_ZONELISTS > 2);
+		for (i = 0; i < MAX_ZONELISTS * MAX_NR_ZONES; i++) {
+
+			/* Identify the zone and nodelist */
+			zoneid = i % MAX_NR_ZONES;
+			listid = i / MAX_NR_ZONES;
+			zonelist = &pgdat->node_zonelists[listid];
+			zone = &pgdat->node_zones[zoneid];
+			if (!populated_zone(zone))
+				continue;
+
+			/* Print information about the zonelist */
+			printk(KERN_DEBUG "mminit::zonelist %s %d:%s = ",
+				listid > 0 ? "thisnode" : "general", nid,
+				zone->name);
+
+			/* Iterate the zonelist */
+			for_each_zone_zonelist(zone, z, zonelist, zoneid) {
+#ifdef CONFIG_NUMA
+				printk(KERN_CONT "%d:%s ",
+					zone->node, zone->name);
+#else
+				printk(KERN_CONT "0:%s ", zone->name);
+#endif /* CONFIG_NUMA */
+			}
+			printk(KERN_CONT "\n");
+		}
+	}
+}
+
+void __init mminit_verify_pageflags_layout(void)
+{
+	int shift, width;
+	unsigned long or_mask, add_mask;
+
+	shift = 8 * sizeof(unsigned long);
+	width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH - LAST_CPUPID_SHIFT;
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths",
+		"Section %d Node %d Zone %d Lastcpupid %d Flags %d\n",
+		SECTIONS_WIDTH,
+		NODES_WIDTH,
+		ZONES_WIDTH,
+		LAST_CPUPID_WIDTH,
+		NR_PAGEFLAGS);
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
+		"Section %d Node %d Zone %d Lastcpupid %d\n",
+		SECTIONS_SHIFT,
+		NODES_SHIFT,
+		ZONES_SHIFT,
+		LAST_CPUPID_SHIFT);
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_pgshifts",
+		"Section %lu Node %lu Zone %lu Lastcpupid %lu\n",
+		(unsigned long)SECTIONS_PGSHIFT,
+		(unsigned long)NODES_PGSHIFT,
+		(unsigned long)ZONES_PGSHIFT,
+		(unsigned long)LAST_CPUPID_PGSHIFT);
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodezoneid",
+		"Node/Zone ID: %lu -> %lu\n",
+		(unsigned long)(ZONEID_PGOFF + ZONEID_SHIFT),
+		(unsigned long)ZONEID_PGOFF);
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_usage",
+		"location: %d -> %d layout %d -> %d unused %d -> %d page-flags\n",
+		shift, width, width, NR_PAGEFLAGS, NR_PAGEFLAGS, 0);
+#ifdef NODE_NOT_IN_PAGE_FLAGS
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodeflags",
+		"Node not in page flags");
+#endif
+#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
+	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodeflags",
+		"Last cpupid not in page flags");
+#endif
+
+	if (SECTIONS_WIDTH) {
+		shift -= SECTIONS_WIDTH;
+		BUG_ON(shift != SECTIONS_PGSHIFT);
+	}
+	if (NODES_WIDTH) {
+		shift -= NODES_WIDTH;
+		BUG_ON(shift != NODES_PGSHIFT);
+	}
+	if (ZONES_WIDTH) {
+		shift -= ZONES_WIDTH;
+		BUG_ON(shift != ZONES_PGSHIFT);
+	}
+
+	/* Check for bitmask overlaps */
+	or_mask = (ZONES_MASK << ZONES_PGSHIFT) |
+			(NODES_MASK << NODES_PGSHIFT) |
+			(SECTIONS_MASK << SECTIONS_PGSHIFT);
+	add_mask = (ZONES_MASK << ZONES_PGSHIFT) +
+			(NODES_MASK << NODES_PGSHIFT) +
+			(SECTIONS_MASK << SECTIONS_PGSHIFT);
+	BUG_ON(or_mask != add_mask);
+}
+
+static __init int set_mminit_loglevel(char *str)
+{
+	get_option(&str, &mminit_loglevel);
+	return 0;
+}
+early_param("mminit_loglevel", set_mminit_loglevel);
+#endif /* CONFIG_DEBUG_MEMORY_INIT */
+
+struct kobject *mm_kobj;
+EXPORT_SYMBOL_GPL(mm_kobj);
+
+#ifdef CONFIG_SMP
+s32 vm_committed_as_batch = 32;
+
+static void __meminit mm_compute_batch(void)
+{
+	u64 memsized_batch;
+	s32 nr = num_present_cpus();
+	s32 batch = max_t(s32, nr*2, 32);
+
+	/* batch size set to 0.4% of (total memory/#cpus), or max int32 */
+	memsized_batch = min_t(u64, (totalram_pages/nr)/256, 0x7fffffff);
+
+	vm_committed_as_batch = max_t(s32, memsized_batch, batch);
+}
+
+static int __meminit mm_compute_batch_notifier(struct notifier_block *self,
+					unsigned long action, void *arg)
+{
+	switch (action) {
+	case MEM_ONLINE:
+	case MEM_OFFLINE:
+		mm_compute_batch();
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block compute_batch_nb __meminitdata = {
+	.notifier_call = mm_compute_batch_notifier,
+	.priority = IPC_CALLBACK_PRI, /* use lowest priority */
+};
+
+static int __init mm_compute_batch_init(void)
+{
+	mm_compute_batch();
+	register_hotmemory_notifier(&compute_batch_nb);
+
+	return 0;
+}
+
+__initcall(mm_compute_batch_init);
+
+#endif
+
+static int __init mm_sysfs_init(void)
+{
+	mm_kobj = kobject_create_and_add("mm", kernel_kobj);
+	if (!mm_kobj)
+		return -ENOMEM;
+
+	return 0;
+}
+postcore_initcall(mm_sysfs_init);
diff --git a/mm/mmap.c b/mm/mmap.c
new file mode 100644
index 0000000..eaa460d
--- /dev/null
+++ b/mm/mmap.c
@@ -0,0 +1,3458 @@
+/*
+ * mm/mmap.c
+ *
+ * Written by obz.
+ *
+ * Address space accounting code	<alan@lxorguk.ukuu.org.uk>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <linux/mm.h>
+#include <linux/vmacache.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/capability.h>
+#include <linux/init.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/personality.h>
+#include <linux/security.h>
+#include <linux/hugetlb.h>
+#include <linux/profile.h>
+#include <linux/export.h>
+#include <linux/mount.h>
+#include <linux/mempolicy.h>
+#include <linux/rmap.h>
+#include <linux/mmu_notifier.h>
+#include <linux/mmdebug.h>
+#include <linux/perf_event.h>
+#include <linux/audit.h>
+#include <linux/khugepaged.h>
+#include <linux/uprobes.h>
+#include <linux/rbtree_augmented.h>
+#include <linux/sched/sysctl.h>
+#include <linux/notifier.h>
+#include <linux/memory.h>
+#include <linux/printk.h>
+#include <linux/userfaultfd_k.h>
+
+#include <asm/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+
+#include "internal.h"
+
+#ifndef arch_mmap_check
+#define arch_mmap_check(addr, len, flags)	(0)
+#endif
+
+#ifndef arch_rebalance_pgtables
+#define arch_rebalance_pgtables(addr, len)		(addr)
+#endif
+
+static void unmap_region(struct mm_struct *mm,
+		struct vm_area_struct *vma, struct vm_area_struct *prev,
+		unsigned long start, unsigned long end);
+
+/* description of effects of mapping type and prot in current implementation.
+ * this is due to the limited x86 page protection hardware.  The expected
+ * behavior is in parens:
+ *
+ * map_type	prot
+ *		PROT_NONE	PROT_READ	PROT_WRITE	PROT_EXEC
+ * MAP_SHARED	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
+ *		w: (no) no	w: (no) no	w: (yes) yes	w: (no) no
+ *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
+ *
+ * MAP_PRIVATE	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
+ *		w: (no) no	w: (no) no	w: (copy) copy	w: (no) no
+ *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
+ *
+ */
+pgprot_t protection_map[16] = {
+	__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
+	__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
+};
+
+pgprot_t vm_get_page_prot(unsigned long vm_flags)
+{
+	return __pgprot(pgprot_val(protection_map[vm_flags &
+				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
+			pgprot_val(arch_vm_get_page_prot(vm_flags)));
+}
+EXPORT_SYMBOL(vm_get_page_prot);
+
+static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
+{
+	return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
+}
+
+/* Update vma->vm_page_prot to reflect vma->vm_flags. */
+void vma_set_page_prot(struct vm_area_struct *vma)
+{
+	unsigned long vm_flags = vma->vm_flags;
+
+	vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
+	if (vma_wants_writenotify(vma)) {
+		vm_flags &= ~VM_SHARED;
+		vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
+						     vm_flags);
+	}
+}
+
+
+int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
+int sysctl_overcommit_ratio __read_mostly = 50;	/* default is 50% */
+unsigned long sysctl_overcommit_kbytes __read_mostly;
+int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
+unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
+unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
+/*
+ * Make sure vm_committed_as in one cacheline and not cacheline shared with
+ * other variables. It can be updated by several CPUs frequently.
+ */
+struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
+
+/*
+ * The global memory commitment made in the system can be a metric
+ * that can be used to drive ballooning decisions when Linux is hosted
+ * as a guest. On Hyper-V, the host implements a policy engine for dynamically
+ * balancing memory across competing virtual machines that are hosted.
+ * Several metrics drive this policy engine including the guest reported
+ * memory commitment.
+ */
+unsigned long vm_memory_committed(void)
+{
+	return percpu_counter_read_positive(&vm_committed_as);
+}
+EXPORT_SYMBOL_GPL(vm_memory_committed);
+
+/*
+ * Check that a process has enough memory to allocate a new virtual
+ * mapping. 0 means there is enough memory for the allocation to
+ * succeed and -ENOMEM implies there is not.
+ *
+ * We currently support three overcommit policies, which are set via the
+ * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
+ *
+ * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
+ * Additional code 2002 Jul 20 by Robert Love.
+ *
+ * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
+ *
+ * Note this is a helper function intended to be used by LSMs which
+ * wish to use this logic.
+ */
+int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
+{
+	long free, allowed, reserve;
+
+	VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
+			-(s64)vm_committed_as_batch * num_online_cpus(),
+			"memory commitment underflow");
+
+	vm_acct_memory(pages);
+
+	/*
+	 * Sometimes we want to use more memory than we have
+	 */
+	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
+		return 0;
+
+	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
+		free = global_page_state(NR_FREE_PAGES);
+		free += global_page_state(NR_FILE_PAGES);
+
+		/*
+		 * shmem pages shouldn't be counted as free in this
+		 * case, they can't be purged, only swapped out, and
+		 * that won't affect the overall amount of available
+		 * memory in the system.
+		 */
+		free -= global_page_state(NR_SHMEM);
+
+		free += get_nr_swap_pages();
+
+		/*
+		 * Any slabs which are created with the
+		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
+		 * which are reclaimable, under pressure.  The dentry
+		 * cache and most inode caches should fall into this
+		 */
+		free += global_page_state(NR_SLAB_RECLAIMABLE);
+
+		/*
+		 * Leave reserved pages. The pages are not for anonymous pages.
+		 */
+		if (free <= totalreserve_pages)
+			goto error;
+		else
+			free -= totalreserve_pages;
+
+		/*
+		 * Reserve some for root
+		 */
+		if (!cap_sys_admin)
+			free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
+
+		if (free > pages)
+			return 0;
+
+		goto error;
+	}
+
+	allowed = vm_commit_limit();
+	/*
+	 * Reserve some for root
+	 */
+	if (!cap_sys_admin)
+		allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
+
+	/*
+	 * Don't let a single process grow so big a user can't recover
+	 */
+	if (mm) {
+		reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
+		allowed -= min_t(long, mm->total_vm / 32, reserve);
+	}
+
+	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
+		return 0;
+error:
+	vm_unacct_memory(pages);
+
+	return -ENOMEM;
+}
+
+/*
+ * Requires inode->i_mapping->i_mmap_rwsem
+ */
+static void __remove_shared_vm_struct(struct vm_area_struct *vma,
+		struct file *file, struct address_space *mapping)
+{
+	if (vma->vm_flags & VM_DENYWRITE)
+		atomic_inc(&file_inode(file)->i_writecount);
+	if (vma->vm_flags & VM_SHARED)
+		mapping_unmap_writable(mapping);
+
+	flush_dcache_mmap_lock(mapping);
+	vma_interval_tree_remove(vma, &mapping->i_mmap);
+	flush_dcache_mmap_unlock(mapping);
+}
+
+/*
+ * Unlink a file-based vm structure from its interval tree, to hide
+ * vma from rmap and vmtruncate before freeing its page tables.
+ */
+void unlink_file_vma(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+
+	if (file) {
+		struct address_space *mapping = file->f_mapping;
+		i_mmap_lock_write(mapping);
+		__remove_shared_vm_struct(vma, file, mapping);
+		i_mmap_unlock_write(mapping);
+	}
+}
+
+/*
+ * Close a vm structure and free it, returning the next.
+ */
+static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
+{
+	struct vm_area_struct *next = vma->vm_next;
+
+	might_sleep();
+	if (vma->vm_ops && vma->vm_ops->close)
+		vma->vm_ops->close(vma);
+	if (vma->vm_file)
+		fput(vma->vm_file);
+	mpol_put(vma_policy(vma));
+	kmem_cache_free(vm_area_cachep, vma);
+	return next;
+}
+
+static unsigned long do_brk(unsigned long addr, unsigned long len);
+
+SYSCALL_DEFINE1(brk, unsigned long, brk)
+{
+	unsigned long retval;
+	unsigned long newbrk, oldbrk;
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *next;
+	unsigned long min_brk;
+	bool populate;
+
+	down_write(&mm->mmap_sem);
+
+#ifdef CONFIG_COMPAT_BRK
+	/*
+	 * CONFIG_COMPAT_BRK can still be overridden by setting
+	 * randomize_va_space to 2, which will still cause mm->start_brk
+	 * to be arbitrarily shifted
+	 */
+	if (current->brk_randomized)
+		min_brk = mm->start_brk;
+	else
+		min_brk = mm->end_data;
+#else
+	min_brk = mm->start_brk;
+#endif
+	if (brk < min_brk)
+		goto out;
+
+	/*
+	 * Check against rlimit here. If this check is done later after the test
+	 * of oldbrk with newbrk then it can escape the test and let the data
+	 * segment grow beyond its set limit the in case where the limit is
+	 * not page aligned -Ram Gupta
+	 */
+	if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
+			      mm->end_data, mm->start_data))
+		goto out;
+
+	newbrk = PAGE_ALIGN(brk);
+	oldbrk = PAGE_ALIGN(mm->brk);
+	if (oldbrk == newbrk)
+		goto set_brk;
+
+	/* Always allow shrinking brk. */
+	if (brk <= mm->brk) {
+		if (!do_munmap(mm, newbrk, oldbrk-newbrk))
+			goto set_brk;
+		goto out;
+	}
+
+	/* Check against existing mmap mappings. */
+	next = find_vma(mm, oldbrk);
+	if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
+		goto out;
+
+	/* Ok, looks good - let it rip. */
+	if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
+		goto out;
+
+set_brk:
+	mm->brk = brk;
+	populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
+	up_write(&mm->mmap_sem);
+	if (populate)
+		mm_populate(oldbrk, newbrk - oldbrk);
+	return brk;
+
+out:
+	retval = mm->brk;
+	up_write(&mm->mmap_sem);
+	return retval;
+}
+
+static long vma_compute_subtree_gap(struct vm_area_struct *vma)
+{
+	unsigned long max, prev_end, subtree_gap;
+
+	/*
+	 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
+	 * allow two stack_guard_gaps between them here, and when choosing
+	 * an unmapped area; whereas when expanding we only require one.
+	 * That's a little inconsistent, but keeps the code here simpler.
+	 */
+	max = vm_start_gap(vma);
+	if (vma->vm_prev) {
+		prev_end = vm_end_gap(vma->vm_prev);
+		if (max > prev_end)
+			max -= prev_end;
+		else
+			max = 0;
+	}
+	if (vma->vm_rb.rb_left) {
+		subtree_gap = rb_entry(vma->vm_rb.rb_left,
+				struct vm_area_struct, vm_rb)->rb_subtree_gap;
+		if (subtree_gap > max)
+			max = subtree_gap;
+	}
+	if (vma->vm_rb.rb_right) {
+		subtree_gap = rb_entry(vma->vm_rb.rb_right,
+				struct vm_area_struct, vm_rb)->rb_subtree_gap;
+		if (subtree_gap > max)
+			max = subtree_gap;
+	}
+	return max;
+}
+
+#ifdef CONFIG_DEBUG_VM_RB
+static int browse_rb(struct rb_root *root)
+{
+	int i = 0, j, bug = 0;
+	struct rb_node *nd, *pn = NULL;
+	unsigned long prev = 0, pend = 0;
+
+	for (nd = rb_first(root); nd; nd = rb_next(nd)) {
+		struct vm_area_struct *vma;
+		vma = rb_entry(nd, struct vm_area_struct, vm_rb);
+		if (vma->vm_start < prev) {
+			pr_emerg("vm_start %lx < prev %lx\n",
+				  vma->vm_start, prev);
+			bug = 1;
+		}
+		if (vma->vm_start < pend) {
+			pr_emerg("vm_start %lx < pend %lx\n",
+				  vma->vm_start, pend);
+			bug = 1;
+		}
+		if (vma->vm_start > vma->vm_end) {
+			pr_emerg("vm_start %lx > vm_end %lx\n",
+				  vma->vm_start, vma->vm_end);
+			bug = 1;
+		}
+		if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
+			pr_emerg("free gap %lx, correct %lx\n",
+			       vma->rb_subtree_gap,
+			       vma_compute_subtree_gap(vma));
+			bug = 1;
+		}
+		i++;
+		pn = nd;
+		prev = vma->vm_start;
+		pend = vma->vm_end;
+	}
+	j = 0;
+	for (nd = pn; nd; nd = rb_prev(nd))
+		j++;
+	if (i != j) {
+		pr_emerg("backwards %d, forwards %d\n", j, i);
+		bug = 1;
+	}
+	return bug ? -1 : i;
+}
+
+static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
+{
+	struct rb_node *nd;
+
+	for (nd = rb_first(root); nd; nd = rb_next(nd)) {
+		struct vm_area_struct *vma;
+		vma = rb_entry(nd, struct vm_area_struct, vm_rb);
+		VM_BUG_ON_VMA(vma != ignore &&
+			vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
+			vma);
+	}
+}
+
+static void validate_mm(struct mm_struct *mm)
+{
+	int bug = 0;
+	int i = 0;
+	unsigned long highest_address = 0;
+	struct vm_area_struct *vma = mm->mmap;
+
+	while (vma) {
+		struct anon_vma *anon_vma = vma->anon_vma;
+		struct anon_vma_chain *avc;
+
+		if (anon_vma) {
+			anon_vma_lock_read(anon_vma);
+			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+				anon_vma_interval_tree_verify(avc);
+			anon_vma_unlock_read(anon_vma);
+		}
+
+		highest_address = vm_end_gap(vma);
+		vma = vma->vm_next;
+		i++;
+	}
+	if (i != mm->map_count) {
+		pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
+		bug = 1;
+	}
+	if (highest_address != mm->highest_vm_end) {
+		pr_emerg("mm->highest_vm_end %lx, found %lx\n",
+			  mm->highest_vm_end, highest_address);
+		bug = 1;
+	}
+	i = browse_rb(&mm->mm_rb);
+	if (i != mm->map_count) {
+		if (i != -1)
+			pr_emerg("map_count %d rb %d\n", mm->map_count, i);
+		bug = 1;
+	}
+	VM_BUG_ON_MM(bug, mm);
+}
+#else
+#define validate_mm_rb(root, ignore) do { } while (0)
+#define validate_mm(mm) do { } while (0)
+#endif
+
+RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
+		     unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
+
+/*
+ * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
+ * vma->vm_prev->vm_end values changed, without modifying the vma's position
+ * in the rbtree.
+ */
+static void vma_gap_update(struct vm_area_struct *vma)
+{
+	/*
+	 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
+	 * function that does exacltly what we want.
+	 */
+	vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
+}
+
+static inline void vma_rb_insert(struct vm_area_struct *vma,
+				 struct rb_root *root)
+{
+	/* All rb_subtree_gap values must be consistent prior to insertion */
+	validate_mm_rb(root, NULL);
+
+	rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
+}
+
+static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
+{
+	/*
+	 * All rb_subtree_gap values must be consistent prior to erase,
+	 * with the possible exception of the vma being erased.
+	 */
+	validate_mm_rb(root, vma);
+
+	/*
+	 * Note rb_erase_augmented is a fairly large inline function,
+	 * so make sure we instantiate it only once with our desired
+	 * augmented rbtree callbacks.
+	 */
+	rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
+}
+
+/*
+ * vma has some anon_vma assigned, and is already inserted on that
+ * anon_vma's interval trees.
+ *
+ * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
+ * vma must be removed from the anon_vma's interval trees using
+ * anon_vma_interval_tree_pre_update_vma().
+ *
+ * After the update, the vma will be reinserted using
+ * anon_vma_interval_tree_post_update_vma().
+ *
+ * The entire update must be protected by exclusive mmap_sem and by
+ * the root anon_vma's mutex.
+ */
+static inline void
+anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
+{
+	struct anon_vma_chain *avc;
+
+	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+		anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
+}
+
+static inline void
+anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
+{
+	struct anon_vma_chain *avc;
+
+	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+		anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
+}
+
+static int find_vma_links(struct mm_struct *mm, unsigned long addr,
+		unsigned long end, struct vm_area_struct **pprev,
+		struct rb_node ***rb_link, struct rb_node **rb_parent)
+{
+	struct rb_node **__rb_link, *__rb_parent, *rb_prev;
+
+	__rb_link = &mm->mm_rb.rb_node;
+	rb_prev = __rb_parent = NULL;
+
+	while (*__rb_link) {
+		struct vm_area_struct *vma_tmp;
+
+		__rb_parent = *__rb_link;
+		vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
+
+		if (vma_tmp->vm_end > addr) {
+			/* Fail if an existing vma overlaps the area */
+			if (vma_tmp->vm_start < end)
+				return -ENOMEM;
+			__rb_link = &__rb_parent->rb_left;
+		} else {
+			rb_prev = __rb_parent;
+			__rb_link = &__rb_parent->rb_right;
+		}
+	}
+
+	*pprev = NULL;
+	if (rb_prev)
+		*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
+	*rb_link = __rb_link;
+	*rb_parent = __rb_parent;
+	return 0;
+}
+
+static unsigned long count_vma_pages_range(struct mm_struct *mm,
+		unsigned long addr, unsigned long end)
+{
+	unsigned long nr_pages = 0;
+	struct vm_area_struct *vma;
+
+	/* Find first overlaping mapping */
+	vma = find_vma_intersection(mm, addr, end);
+	if (!vma)
+		return 0;
+
+	nr_pages = (min(end, vma->vm_end) -
+		max(addr, vma->vm_start)) >> PAGE_SHIFT;
+
+	/* Iterate over the rest of the overlaps */
+	for (vma = vma->vm_next; vma; vma = vma->vm_next) {
+		unsigned long overlap_len;
+
+		if (vma->vm_start > end)
+			break;
+
+		overlap_len = min(end, vma->vm_end) - vma->vm_start;
+		nr_pages += overlap_len >> PAGE_SHIFT;
+	}
+
+	return nr_pages;
+}
+
+void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct rb_node **rb_link, struct rb_node *rb_parent)
+{
+	/* Update tracking information for the gap following the new vma. */
+	if (vma->vm_next)
+		vma_gap_update(vma->vm_next);
+	else
+		mm->highest_vm_end = vm_end_gap(vma);
+
+	/*
+	 * vma->vm_prev wasn't known when we followed the rbtree to find the
+	 * correct insertion point for that vma. As a result, we could not
+	 * update the vma vm_rb parents rb_subtree_gap values on the way down.
+	 * So, we first insert the vma with a zero rb_subtree_gap value
+	 * (to be consistent with what we did on the way down), and then
+	 * immediately update the gap to the correct value. Finally we
+	 * rebalance the rbtree after all augmented values have been set.
+	 */
+	rb_link_node(&vma->vm_rb, rb_parent, rb_link);
+	vma->rb_subtree_gap = 0;
+	vma_gap_update(vma);
+	vma_rb_insert(vma, &mm->mm_rb);
+}
+
+static void __vma_link_file(struct vm_area_struct *vma)
+{
+	struct file *file;
+
+	file = vma->vm_file;
+	if (file) {
+		struct address_space *mapping = file->f_mapping;
+
+		if (vma->vm_flags & VM_DENYWRITE)
+			atomic_dec(&file_inode(file)->i_writecount);
+		if (vma->vm_flags & VM_SHARED)
+			atomic_inc(&mapping->i_mmap_writable);
+
+		flush_dcache_mmap_lock(mapping);
+		vma_interval_tree_insert(vma, &mapping->i_mmap);
+		flush_dcache_mmap_unlock(mapping);
+	}
+}
+
+static void
+__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
+	struct vm_area_struct *prev, struct rb_node **rb_link,
+	struct rb_node *rb_parent)
+{
+	__vma_link_list(mm, vma, prev, rb_parent);
+	__vma_link_rb(mm, vma, rb_link, rb_parent);
+}
+
+static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
+			struct vm_area_struct *prev, struct rb_node **rb_link,
+			struct rb_node *rb_parent)
+{
+	struct address_space *mapping = NULL;
+
+	if (vma->vm_file) {
+		mapping = vma->vm_file->f_mapping;
+		i_mmap_lock_write(mapping);
+	}
+
+	__vma_link(mm, vma, prev, rb_link, rb_parent);
+	__vma_link_file(vma);
+
+	if (mapping)
+		i_mmap_unlock_write(mapping);
+
+	mm->map_count++;
+	validate_mm(mm);
+}
+
+/*
+ * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
+ * mm's list and rbtree.  It has already been inserted into the interval tree.
+ */
+static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	struct vm_area_struct *prev;
+	struct rb_node **rb_link, *rb_parent;
+
+	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
+			   &prev, &rb_link, &rb_parent))
+		BUG();
+	__vma_link(mm, vma, prev, rb_link, rb_parent);
+	mm->map_count++;
+}
+
+static inline void
+__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct vm_area_struct *prev)
+{
+	struct vm_area_struct *next;
+
+	vma_rb_erase(vma, &mm->mm_rb);
+	prev->vm_next = next = vma->vm_next;
+	if (next)
+		next->vm_prev = prev;
+
+	/* Kill the cache */
+	vmacache_invalidate(mm);
+}
+
+/*
+ * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
+ * is already present in an i_mmap tree without adjusting the tree.
+ * The following helper function should be used when such adjustments
+ * are necessary.  The "insert" vma (if any) is to be inserted
+ * before we drop the necessary locks.
+ */
+int vma_adjust(struct vm_area_struct *vma, unsigned long start,
+	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *next = vma->vm_next;
+	struct vm_area_struct *importer = NULL;
+	struct address_space *mapping = NULL;
+	struct rb_root *root = NULL;
+	struct anon_vma *anon_vma = NULL;
+	struct file *file = vma->vm_file;
+	bool start_changed = false, end_changed = false;
+	long adjust_next = 0;
+	int remove_next = 0;
+
+	if (next && !insert) {
+		struct vm_area_struct *exporter = NULL;
+
+		if (end >= next->vm_end) {
+			/*
+			 * vma expands, overlapping all the next, and
+			 * perhaps the one after too (mprotect case 6).
+			 */
+again:			remove_next = 1 + (end > next->vm_end);
+			end = next->vm_end;
+			exporter = next;
+			importer = vma;
+		} else if (end > next->vm_start) {
+			/*
+			 * vma expands, overlapping part of the next:
+			 * mprotect case 5 shifting the boundary up.
+			 */
+			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
+			exporter = next;
+			importer = vma;
+		} else if (end < vma->vm_end) {
+			/*
+			 * vma shrinks, and !insert tells it's not
+			 * split_vma inserting another: so it must be
+			 * mprotect case 4 shifting the boundary down.
+			 */
+			adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
+			exporter = vma;
+			importer = next;
+		}
+
+		/*
+		 * Easily overlooked: when mprotect shifts the boundary,
+		 * make sure the expanding vma has anon_vma set if the
+		 * shrinking vma had, to cover any anon pages imported.
+		 */
+		if (exporter && exporter->anon_vma && !importer->anon_vma) {
+			int error;
+
+			importer->anon_vma = exporter->anon_vma;
+			error = anon_vma_clone(importer, exporter);
+			if (error)
+				return error;
+		}
+	}
+
+	if (file) {
+		mapping = file->f_mapping;
+		root = &mapping->i_mmap;
+		uprobe_munmap(vma, vma->vm_start, vma->vm_end);
+
+		if (adjust_next)
+			uprobe_munmap(next, next->vm_start, next->vm_end);
+
+		i_mmap_lock_write(mapping);
+		if (insert) {
+			/*
+			 * Put into interval tree now, so instantiated pages
+			 * are visible to arm/parisc __flush_dcache_page
+			 * throughout; but we cannot insert into address
+			 * space until vma start or end is updated.
+			 */
+			__vma_link_file(insert);
+		}
+	}
+
+	vma_adjust_trans_huge(vma, start, end, adjust_next);
+
+	anon_vma = vma->anon_vma;
+	if (!anon_vma && adjust_next)
+		anon_vma = next->anon_vma;
+	if (anon_vma) {
+		VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
+			  anon_vma != next->anon_vma, next);
+		anon_vma_lock_write(anon_vma);
+		anon_vma_interval_tree_pre_update_vma(vma);
+		if (adjust_next)
+			anon_vma_interval_tree_pre_update_vma(next);
+	}
+
+	if (root) {
+		flush_dcache_mmap_lock(mapping);
+		vma_interval_tree_remove(vma, root);
+		if (adjust_next)
+			vma_interval_tree_remove(next, root);
+	}
+
+	if (start != vma->vm_start) {
+		vma->vm_start = start;
+		start_changed = true;
+	}
+	if (end != vma->vm_end) {
+		vma->vm_end = end;
+		end_changed = true;
+	}
+	vma->vm_pgoff = pgoff;
+	if (adjust_next) {
+		next->vm_start += adjust_next << PAGE_SHIFT;
+		next->vm_pgoff += adjust_next;
+	}
+
+	if (root) {
+		if (adjust_next)
+			vma_interval_tree_insert(next, root);
+		vma_interval_tree_insert(vma, root);
+		flush_dcache_mmap_unlock(mapping);
+	}
+
+	if (remove_next) {
+		/*
+		 * vma_merge has merged next into vma, and needs
+		 * us to remove next before dropping the locks.
+		 */
+		__vma_unlink(mm, next, vma);
+		if (file)
+			__remove_shared_vm_struct(next, file, mapping);
+	} else if (insert) {
+		/*
+		 * split_vma has split insert from vma, and needs
+		 * us to insert it before dropping the locks
+		 * (it may either follow vma or precede it).
+		 */
+		__insert_vm_struct(mm, insert);
+	} else {
+		if (start_changed)
+			vma_gap_update(vma);
+		if (end_changed) {
+			if (!next)
+				mm->highest_vm_end = vm_end_gap(vma);
+			else if (!adjust_next)
+				vma_gap_update(next);
+		}
+	}
+
+	if (anon_vma) {
+		anon_vma_interval_tree_post_update_vma(vma);
+		if (adjust_next)
+			anon_vma_interval_tree_post_update_vma(next);
+		anon_vma_unlock_write(anon_vma);
+	}
+	if (mapping)
+		i_mmap_unlock_write(mapping);
+
+	if (root) {
+		uprobe_mmap(vma);
+
+		if (adjust_next)
+			uprobe_mmap(next);
+	}
+
+	if (remove_next) {
+		if (file) {
+			uprobe_munmap(next, next->vm_start, next->vm_end);
+			fput(file);
+		}
+		if (next->anon_vma)
+			anon_vma_merge(vma, next);
+		mm->map_count--;
+		mpol_put(vma_policy(next));
+		kmem_cache_free(vm_area_cachep, next);
+		/*
+		 * In mprotect's case 6 (see comments on vma_merge),
+		 * we must remove another next too. It would clutter
+		 * up the code too much to do both in one go.
+		 */
+		next = vma->vm_next;
+		if (remove_next == 2)
+			goto again;
+		else if (next)
+			vma_gap_update(next);
+		else
+			VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
+	}
+	if (insert && file)
+		uprobe_mmap(insert);
+
+	validate_mm(mm);
+
+	return 0;
+}
+
+/*
+ * If the vma has a ->close operation then the driver probably needs to release
+ * per-vma resources, so we don't attempt to merge those.
+ */
+static inline int is_mergeable_vma(struct vm_area_struct *vma,
+				struct file *file, unsigned long vm_flags,
+				struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+	/*
+	 * VM_SOFTDIRTY should not prevent from VMA merging, if we
+	 * match the flags but dirty bit -- the caller should mark
+	 * merged VMA as dirty. If dirty bit won't be excluded from
+	 * comparison, we increase pressue on the memory system forcing
+	 * the kernel to generate new VMAs when old one could be
+	 * extended instead.
+	 */
+	if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
+		return 0;
+	if (vma->vm_file != file)
+		return 0;
+	if (vma->vm_ops && vma->vm_ops->close)
+		return 0;
+	if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
+		return 0;
+	return 1;
+}
+
+static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
+					struct anon_vma *anon_vma2,
+					struct vm_area_struct *vma)
+{
+	/*
+	 * The list_is_singular() test is to avoid merging VMA cloned from
+	 * parents. This can improve scalability caused by anon_vma lock.
+	 */
+	if ((!anon_vma1 || !anon_vma2) && (!vma ||
+		list_is_singular(&vma->anon_vma_chain)))
+		return 1;
+	return anon_vma1 == anon_vma2;
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * in front of (at a lower virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ *
+ * We don't check here for the merged mmap wrapping around the end of pagecache
+ * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
+ * wrap, nor mmaps which cover the final page at index -1UL.
+ */
+static int
+can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
+		     struct anon_vma *anon_vma, struct file *file,
+		     pgoff_t vm_pgoff,
+		     struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
+	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
+		if (vma->vm_pgoff == vm_pgoff)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * beyond (at a higher virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ */
+static int
+can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
+		    struct anon_vma *anon_vma, struct file *file,
+		    pgoff_t vm_pgoff,
+		    struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
+	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
+		pgoff_t vm_pglen;
+		vm_pglen = vma_pages(vma);
+		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
+ * whether that can be merged with its predecessor or its successor.
+ * Or both (it neatly fills a hole).
+ *
+ * In most cases - when called for mmap, brk or mremap - [addr,end) is
+ * certain not to be mapped by the time vma_merge is called; but when
+ * called for mprotect, it is certain to be already mapped (either at
+ * an offset within prev, or at the start of next), and the flags of
+ * this area are about to be changed to vm_flags - and the no-change
+ * case has already been eliminated.
+ *
+ * The following mprotect cases have to be considered, where AAAA is
+ * the area passed down from mprotect_fixup, never extending beyond one
+ * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
+ *
+ *     AAAA             AAAA                AAAA          AAAA
+ *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
+ *    cannot merge    might become    might become    might become
+ *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
+ *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
+ *    mremap move:                                    PPPPNNNNNNNN 8
+ *        AAAA
+ *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
+ *    might become    case 1 below    case 2 below    case 3 below
+ *
+ * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
+ * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
+ */
+struct vm_area_struct *vma_merge(struct mm_struct *mm,
+			struct vm_area_struct *prev, unsigned long addr,
+			unsigned long end, unsigned long vm_flags,
+			struct anon_vma *anon_vma, struct file *file,
+			pgoff_t pgoff, struct mempolicy *policy,
+			struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
+	struct vm_area_struct *area, *next;
+	int err;
+
+	/*
+	 * We later require that vma->vm_flags == vm_flags,
+	 * so this tests vma->vm_flags & VM_SPECIAL, too.
+	 */
+	if (vm_flags & VM_SPECIAL)
+		return NULL;
+
+	if (prev)
+		next = prev->vm_next;
+	else
+		next = mm->mmap;
+	area = next;
+	if (next && next->vm_end == end)		/* cases 6, 7, 8 */
+		next = next->vm_next;
+
+	/*
+	 * Can it merge with the predecessor?
+	 */
+	if (prev && prev->vm_end == addr &&
+			mpol_equal(vma_policy(prev), policy) &&
+			can_vma_merge_after(prev, vm_flags,
+					    anon_vma, file, pgoff,
+					    vm_userfaultfd_ctx)) {
+		/*
+		 * OK, it can.  Can we now merge in the successor as well?
+		 */
+		if (next && end == next->vm_start &&
+				mpol_equal(policy, vma_policy(next)) &&
+				can_vma_merge_before(next, vm_flags,
+						     anon_vma, file,
+						     pgoff+pglen,
+						     vm_userfaultfd_ctx) &&
+				is_mergeable_anon_vma(prev->anon_vma,
+						      next->anon_vma, NULL)) {
+							/* cases 1, 6 */
+			err = vma_adjust(prev, prev->vm_start,
+				next->vm_end, prev->vm_pgoff, NULL);
+		} else					/* cases 2, 5, 7 */
+			err = vma_adjust(prev, prev->vm_start,
+				end, prev->vm_pgoff, NULL);
+		if (err)
+			return NULL;
+		khugepaged_enter_vma_merge(prev, vm_flags);
+		return prev;
+	}
+
+	/*
+	 * Can this new request be merged in front of next?
+	 */
+	if (next && end == next->vm_start &&
+			mpol_equal(policy, vma_policy(next)) &&
+			can_vma_merge_before(next, vm_flags,
+					     anon_vma, file, pgoff+pglen,
+					     vm_userfaultfd_ctx)) {
+		if (prev && addr < prev->vm_end)	/* case 4 */
+			err = vma_adjust(prev, prev->vm_start,
+				addr, prev->vm_pgoff, NULL);
+		else					/* cases 3, 8 */
+			err = vma_adjust(area, addr, next->vm_end,
+				next->vm_pgoff - pglen, NULL);
+		if (err)
+			return NULL;
+		khugepaged_enter_vma_merge(area, vm_flags);
+		return area;
+	}
+
+	return NULL;
+}
+
+/*
+ * Rough compatbility check to quickly see if it's even worth looking
+ * at sharing an anon_vma.
+ *
+ * They need to have the same vm_file, and the flags can only differ
+ * in things that mprotect may change.
+ *
+ * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
+ * we can merge the two vma's. For example, we refuse to merge a vma if
+ * there is a vm_ops->close() function, because that indicates that the
+ * driver is doing some kind of reference counting. But that doesn't
+ * really matter for the anon_vma sharing case.
+ */
+static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
+{
+	return a->vm_end == b->vm_start &&
+		mpol_equal(vma_policy(a), vma_policy(b)) &&
+		a->vm_file == b->vm_file &&
+		!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
+		b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
+}
+
+/*
+ * Do some basic sanity checking to see if we can re-use the anon_vma
+ * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
+ * the same as 'old', the other will be the new one that is trying
+ * to share the anon_vma.
+ *
+ * NOTE! This runs with mm_sem held for reading, so it is possible that
+ * the anon_vma of 'old' is concurrently in the process of being set up
+ * by another page fault trying to merge _that_. But that's ok: if it
+ * is being set up, that automatically means that it will be a singleton
+ * acceptable for merging, so we can do all of this optimistically. But
+ * we do that READ_ONCE() to make sure that we never re-load the pointer.
+ *
+ * IOW: that the "list_is_singular()" test on the anon_vma_chain only
+ * matters for the 'stable anon_vma' case (ie the thing we want to avoid
+ * is to return an anon_vma that is "complex" due to having gone through
+ * a fork).
+ *
+ * We also make sure that the two vma's are compatible (adjacent,
+ * and with the same memory policies). That's all stable, even with just
+ * a read lock on the mm_sem.
+ */
+static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
+{
+	if (anon_vma_compatible(a, b)) {
+		struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
+
+		if (anon_vma && list_is_singular(&old->anon_vma_chain))
+			return anon_vma;
+	}
+	return NULL;
+}
+
+/*
+ * find_mergeable_anon_vma is used by anon_vma_prepare, to check
+ * neighbouring vmas for a suitable anon_vma, before it goes off
+ * to allocate a new anon_vma.  It checks because a repetitive
+ * sequence of mprotects and faults may otherwise lead to distinct
+ * anon_vmas being allocated, preventing vma merge in subsequent
+ * mprotect.
+ */
+struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
+{
+	struct anon_vma *anon_vma;
+	struct vm_area_struct *near;
+
+	near = vma->vm_next;
+	if (!near)
+		goto try_prev;
+
+	anon_vma = reusable_anon_vma(near, vma, near);
+	if (anon_vma)
+		return anon_vma;
+try_prev:
+	near = vma->vm_prev;
+	if (!near)
+		goto none;
+
+	anon_vma = reusable_anon_vma(near, near, vma);
+	if (anon_vma)
+		return anon_vma;
+none:
+	/*
+	 * There's no absolute need to look only at touching neighbours:
+	 * we could search further afield for "compatible" anon_vmas.
+	 * But it would probably just be a waste of time searching,
+	 * or lead to too many vmas hanging off the same anon_vma.
+	 * We're trying to allow mprotect remerging later on,
+	 * not trying to minimize memory used for anon_vmas.
+	 */
+	return NULL;
+}
+
+#ifdef CONFIG_PROC_FS
+void vm_stat_account(struct mm_struct *mm, unsigned long flags,
+						struct file *file, long pages)
+{
+	const unsigned long stack_flags
+		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
+
+	mm->total_vm += pages;
+
+	if (file) {
+		mm->shared_vm += pages;
+		if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
+			mm->exec_vm += pages;
+	} else if (flags & stack_flags)
+		mm->stack_vm += pages;
+}
+#endif /* CONFIG_PROC_FS */
+
+/*
+ * If a hint addr is less than mmap_min_addr change hint to be as
+ * low as possible but still greater than mmap_min_addr
+ */
+static inline unsigned long round_hint_to_min(unsigned long hint)
+{
+	hint &= PAGE_MASK;
+	if (((void *)hint != NULL) &&
+	    (hint < mmap_min_addr))
+		return PAGE_ALIGN(mmap_min_addr);
+	return hint;
+}
+
+static inline int mlock_future_check(struct mm_struct *mm,
+				     unsigned long flags,
+				     unsigned long len)
+{
+	unsigned long locked, lock_limit;
+
+	/*  mlock MCL_FUTURE? */
+	if (flags & VM_LOCKED) {
+		locked = len >> PAGE_SHIFT;
+		locked += mm->locked_vm;
+		lock_limit = rlimit(RLIMIT_MEMLOCK);
+		lock_limit >>= PAGE_SHIFT;
+		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+			return -EAGAIN;
+	}
+	return 0;
+}
+
+/*
+ * The caller must hold down_write(&current->mm->mmap_sem).
+ */
+unsigned long do_mmap(struct file *file, unsigned long addr,
+			unsigned long len, unsigned long prot,
+			unsigned long flags, vm_flags_t vm_flags,
+			unsigned long pgoff, unsigned long *populate)
+{
+	struct mm_struct *mm = current->mm;
+
+	*populate = 0;
+
+	if (!len)
+		return -EINVAL;
+
+	/*
+	 * Does the application expect PROT_READ to imply PROT_EXEC?
+	 *
+	 * (the exception is when the underlying filesystem is noexec
+	 *  mounted, in which case we dont add PROT_EXEC.)
+	 */
+	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+		if (!(file && path_noexec(&file->f_path)))
+			prot |= PROT_EXEC;
+
+	if (!(flags & MAP_FIXED))
+		addr = round_hint_to_min(addr);
+
+	/* Careful about overflows.. */
+	len = PAGE_ALIGN(len);
+	if (!len)
+		return -ENOMEM;
+
+	/* offset overflow? */
+	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
+		return -EOVERFLOW;
+
+	/* Too many mappings? */
+	if (mm->map_count > sysctl_max_map_count)
+		return -ENOMEM;
+
+	/* Obtain the address to map to. we verify (or select) it and ensure
+	 * that it represents a valid section of the address space.
+	 */
+	addr = get_unmapped_area(file, addr, len, pgoff, flags);
+	if (offset_in_page(addr))
+		return addr;
+
+	/* Do simple checking here so the lower-level routines won't have
+	 * to. we assume access permissions have been handled by the open
+	 * of the memory object, so we don't do any here.
+	 */
+	vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
+			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+
+	if (flags & MAP_LOCKED)
+		if (!can_do_mlock())
+			return -EPERM;
+
+	if (mlock_future_check(mm, vm_flags, len))
+		return -EAGAIN;
+
+	if (file) {
+		struct inode *inode = file_inode(file);
+
+		switch (flags & MAP_TYPE) {
+		case MAP_SHARED:
+			if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
+				return -EACCES;
+
+			/*
+			 * Make sure we don't allow writing to an append-only
+			 * file..
+			 */
+			if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
+				return -EACCES;
+
+			/*
+			 * Make sure there are no mandatory locks on the file.
+			 */
+			if (locks_verify_locked(file))
+				return -EAGAIN;
+
+			vm_flags |= VM_SHARED | VM_MAYSHARE;
+			if (!(file->f_mode & FMODE_WRITE))
+				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
+
+			/* fall through */
+		case MAP_PRIVATE:
+			if (!(file->f_mode & FMODE_READ))
+				return -EACCES;
+			if (path_noexec(&file->f_path)) {
+				if (vm_flags & VM_EXEC)
+					return -EPERM;
+				vm_flags &= ~VM_MAYEXEC;
+			}
+
+			if (!file->f_op->mmap)
+				return -ENODEV;
+			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+				return -EINVAL;
+			break;
+
+		default:
+			return -EINVAL;
+		}
+	} else {
+		switch (flags & MAP_TYPE) {
+		case MAP_SHARED:
+			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+				return -EINVAL;
+			/*
+			 * Ignore pgoff.
+			 */
+			pgoff = 0;
+			vm_flags |= VM_SHARED | VM_MAYSHARE;
+			break;
+		case MAP_PRIVATE:
+			/*
+			 * Set pgoff according to addr for anon_vma.
+			 */
+			pgoff = addr >> PAGE_SHIFT;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	/*
+	 * Set 'VM_NORESERVE' if we should not account for the
+	 * memory use of this mapping.
+	 */
+	if (flags & MAP_NORESERVE) {
+		/* We honor MAP_NORESERVE if allowed to overcommit */
+		if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
+			vm_flags |= VM_NORESERVE;
+
+		/* hugetlb applies strict overcommit unless MAP_NORESERVE */
+		if (file && is_file_hugepages(file))
+			vm_flags |= VM_NORESERVE;
+	}
+
+	addr = mmap_region(file, addr, len, vm_flags, pgoff);
+	if (!IS_ERR_VALUE(addr) &&
+	    ((vm_flags & VM_LOCKED) ||
+	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
+		*populate = len;
+	return addr;
+}
+
+SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
+		unsigned long, prot, unsigned long, flags,
+		unsigned long, fd, unsigned long, pgoff)
+{
+	struct file *file = NULL;
+	unsigned long retval;
+
+	if (!(flags & MAP_ANONYMOUS)) {
+		audit_mmap_fd(fd, flags);
+		file = fget(fd);
+		if (!file)
+			return -EBADF;
+		if (is_file_hugepages(file))
+			len = ALIGN(len, huge_page_size(hstate_file(file)));
+		retval = -EINVAL;
+		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
+			goto out_fput;
+	} else if (flags & MAP_HUGETLB) {
+		struct user_struct *user = NULL;
+		struct hstate *hs;
+
+		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
+		if (!hs)
+			return -EINVAL;
+
+		len = ALIGN(len, huge_page_size(hs));
+		/*
+		 * VM_NORESERVE is used because the reservations will be
+		 * taken when vm_ops->mmap() is called
+		 * A dummy user value is used because we are not locking
+		 * memory so no accounting is necessary
+		 */
+		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
+				VM_NORESERVE,
+				&user, HUGETLB_ANONHUGE_INODE,
+				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+		if (IS_ERR(file))
+			return PTR_ERR(file);
+	}
+
+	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
+
+	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
+out_fput:
+	if (file)
+		fput(file);
+	return retval;
+}
+
+#ifdef __ARCH_WANT_SYS_OLD_MMAP
+struct mmap_arg_struct {
+	unsigned long addr;
+	unsigned long len;
+	unsigned long prot;
+	unsigned long flags;
+	unsigned long fd;
+	unsigned long offset;
+};
+
+SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
+{
+	struct mmap_arg_struct a;
+
+	if (copy_from_user(&a, arg, sizeof(a)))
+		return -EFAULT;
+	if (offset_in_page(a.offset))
+		return -EINVAL;
+
+	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
+			      a.offset >> PAGE_SHIFT);
+}
+#endif /* __ARCH_WANT_SYS_OLD_MMAP */
+
+/*
+ * Some shared mappigns will want the pages marked read-only
+ * to track write events. If so, we'll downgrade vm_page_prot
+ * to the private version (using protection_map[] without the
+ * VM_SHARED bit).
+ */
+int vma_wants_writenotify(struct vm_area_struct *vma)
+{
+	vm_flags_t vm_flags = vma->vm_flags;
+	const struct vm_operations_struct *vm_ops = vma->vm_ops;
+
+	/* If it was private or non-writable, the write bit is already clear */
+	if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
+		return 0;
+
+	/* The backer wishes to know when pages are first written to? */
+	if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
+		return 1;
+
+	/* The open routine did something to the protections that pgprot_modify
+	 * won't preserve? */
+	if (pgprot_val(vma->vm_page_prot) !=
+	    pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
+		return 0;
+
+	/* Do we need to track softdirty? */
+	if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
+		return 1;
+
+	/* Specialty mapping? */
+	if (vm_flags & VM_PFNMAP)
+		return 0;
+
+	/* Can the mapping track the dirty pages? */
+	return vma->vm_file && vma->vm_file->f_mapping &&
+		mapping_cap_account_dirty(vma->vm_file->f_mapping);
+}
+
+/*
+ * We account for memory if it's a private writeable mapping,
+ * not hugepages and VM_NORESERVE wasn't set.
+ */
+static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
+{
+	/*
+	 * hugetlb has its own accounting separate from the core VM
+	 * VM_HUGETLB may not be set yet so we cannot check for that flag.
+	 */
+	if (file && is_file_hugepages(file))
+		return 0;
+
+	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
+}
+
+unsigned long mmap_region(struct file *file, unsigned long addr,
+		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma, *prev;
+	int error;
+	struct rb_node **rb_link, *rb_parent;
+	unsigned long charged = 0;
+
+	/* Check against address space limit. */
+	if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
+		unsigned long nr_pages;
+
+		/*
+		 * MAP_FIXED may remove pages of mappings that intersects with
+		 * requested mapping. Account for the pages it would unmap.
+		 */
+		if (!(vm_flags & MAP_FIXED))
+			return -ENOMEM;
+
+		nr_pages = count_vma_pages_range(mm, addr, addr + len);
+
+		if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
+			return -ENOMEM;
+	}
+
+	/* Clear old maps */
+	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
+			      &rb_parent)) {
+		if (do_munmap(mm, addr, len))
+			return -ENOMEM;
+	}
+
+	/*
+	 * Private writable mapping: check memory availability
+	 */
+	if (accountable_mapping(file, vm_flags)) {
+		charged = len >> PAGE_SHIFT;
+		if (security_vm_enough_memory_mm(mm, charged))
+			return -ENOMEM;
+		vm_flags |= VM_ACCOUNT;
+	}
+
+	/*
+	 * Can we just expand an old mapping?
+	 */
+	vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
+			NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
+	if (vma)
+		goto out;
+
+	/*
+	 * Determine the object being mapped and call the appropriate
+	 * specific mapper. the address has already been validated, but
+	 * not unmapped, but the maps are removed from the list.
+	 */
+	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+	if (!vma) {
+		error = -ENOMEM;
+		goto unacct_error;
+	}
+
+	vma->vm_mm = mm;
+	vma->vm_start = addr;
+	vma->vm_end = addr + len;
+	vma->vm_flags = vm_flags;
+	vma->vm_page_prot = vm_get_page_prot(vm_flags);
+	vma->vm_pgoff = pgoff;
+	INIT_LIST_HEAD(&vma->anon_vma_chain);
+
+	if (file) {
+		if (vm_flags & VM_DENYWRITE) {
+			error = deny_write_access(file);
+			if (error)
+				goto free_vma;
+		}
+		if (vm_flags & VM_SHARED) {
+			error = mapping_map_writable(file->f_mapping);
+			if (error)
+				goto allow_write_and_free_vma;
+		}
+
+		/* ->mmap() can change vma->vm_file, but must guarantee that
+		 * vma_link() below can deny write-access if VM_DENYWRITE is set
+		 * and map writably if VM_SHARED is set. This usually means the
+		 * new file must not have been exposed to user-space, yet.
+		 */
+		vma->vm_file = get_file(file);
+		error = file->f_op->mmap(file, vma);
+		if (error)
+			goto unmap_and_free_vma;
+
+		/* Can addr have changed??
+		 *
+		 * Answer: Yes, several device drivers can do it in their
+		 *         f_op->mmap method. -DaveM
+		 * Bug: If addr is changed, prev, rb_link, rb_parent should
+		 *      be updated for vma_link()
+		 */
+		WARN_ON_ONCE(addr != vma->vm_start);
+
+		addr = vma->vm_start;
+		vm_flags = vma->vm_flags;
+	} else if (vm_flags & VM_SHARED) {
+		error = shmem_zero_setup(vma);
+		if (error)
+			goto free_vma;
+	}
+
+	vma_link(mm, vma, prev, rb_link, rb_parent);
+	/* Once vma denies write, undo our temporary denial count */
+	if (file) {
+		if (vm_flags & VM_SHARED)
+			mapping_unmap_writable(file->f_mapping);
+		if (vm_flags & VM_DENYWRITE)
+			allow_write_access(file);
+	}
+	file = vma->vm_file;
+out:
+	perf_event_mmap(vma);
+
+	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
+	if (vm_flags & VM_LOCKED) {
+		if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
+					vma == get_gate_vma(current->mm)))
+			mm->locked_vm += (len >> PAGE_SHIFT);
+		else
+			vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+	}
+
+	if (file)
+		uprobe_mmap(vma);
+
+	/*
+	 * New (or expanded) vma always get soft dirty status.
+	 * Otherwise user-space soft-dirty page tracker won't
+	 * be able to distinguish situation when vma area unmapped,
+	 * then new mapped in-place (which must be aimed as
+	 * a completely new data area).
+	 */
+	vma->vm_flags |= VM_SOFTDIRTY;
+
+	vma_set_page_prot(vma);
+
+	return addr;
+
+unmap_and_free_vma:
+	vma->vm_file = NULL;
+	fput(file);
+
+	/* Undo any partial mapping done by a device driver. */
+	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
+	charged = 0;
+	if (vm_flags & VM_SHARED)
+		mapping_unmap_writable(file->f_mapping);
+allow_write_and_free_vma:
+	if (vm_flags & VM_DENYWRITE)
+		allow_write_access(file);
+free_vma:
+	kmem_cache_free(vm_area_cachep, vma);
+unacct_error:
+	if (charged)
+		vm_unacct_memory(charged);
+	return error;
+}
+
+unsigned long unmapped_area(struct vm_unmapped_area_info *info)
+{
+	/*
+	 * We implement the search by looking for an rbtree node that
+	 * immediately follows a suitable gap. That is,
+	 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
+	 * - gap_end   = vma->vm_start        >= info->low_limit  + length;
+	 * - gap_end - gap_start >= length
+	 */
+
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long length, low_limit, high_limit, gap_start, gap_end;
+
+	/* Adjust search length to account for worst case alignment overhead */
+	length = info->length + info->align_mask;
+	if (length < info->length)
+		return -ENOMEM;
+
+	/* Adjust search limits by the desired length */
+	if (info->high_limit < length)
+		return -ENOMEM;
+	high_limit = info->high_limit - length;
+
+	if (info->low_limit > high_limit)
+		return -ENOMEM;
+	low_limit = info->low_limit + length;
+
+	/* Check if rbtree root looks promising */
+	if (RB_EMPTY_ROOT(&mm->mm_rb))
+		goto check_highest;
+	vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
+	if (vma->rb_subtree_gap < length)
+		goto check_highest;
+
+	while (true) {
+		/* Visit left subtree if it looks promising */
+		gap_end = vm_start_gap(vma);
+		if (gap_end >= low_limit && vma->vm_rb.rb_left) {
+			struct vm_area_struct *left =
+				rb_entry(vma->vm_rb.rb_left,
+					 struct vm_area_struct, vm_rb);
+			if (left->rb_subtree_gap >= length) {
+				vma = left;
+				continue;
+			}
+		}
+
+		gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+check_current:
+		/* Check if current node has a suitable gap */
+		if (gap_start > high_limit)
+			return -ENOMEM;
+		if (gap_end >= low_limit &&
+		    gap_end > gap_start && gap_end - gap_start >= length)
+			goto found;
+
+		/* Visit right subtree if it looks promising */
+		if (vma->vm_rb.rb_right) {
+			struct vm_area_struct *right =
+				rb_entry(vma->vm_rb.rb_right,
+					 struct vm_area_struct, vm_rb);
+			if (right->rb_subtree_gap >= length) {
+				vma = right;
+				continue;
+			}
+		}
+
+		/* Go back up the rbtree to find next candidate node */
+		while (true) {
+			struct rb_node *prev = &vma->vm_rb;
+			if (!rb_parent(prev))
+				goto check_highest;
+			vma = rb_entry(rb_parent(prev),
+				       struct vm_area_struct, vm_rb);
+			if (prev == vma->vm_rb.rb_left) {
+				gap_start = vm_end_gap(vma->vm_prev);
+				gap_end = vm_start_gap(vma);
+				goto check_current;
+			}
+		}
+	}
+
+check_highest:
+	/* Check highest gap, which does not precede any rbtree node */
+	gap_start = mm->highest_vm_end;
+	gap_end = ULONG_MAX;  /* Only for VM_BUG_ON below */
+	if (gap_start > high_limit)
+		return -ENOMEM;
+
+found:
+	/* We found a suitable gap. Clip it with the original low_limit. */
+	if (gap_start < info->low_limit)
+		gap_start = info->low_limit;
+
+	/* Adjust gap address to the desired alignment */
+	gap_start += (info->align_offset - gap_start) & info->align_mask;
+
+	VM_BUG_ON(gap_start + info->length > info->high_limit);
+	VM_BUG_ON(gap_start + info->length > gap_end);
+	return gap_start;
+}
+
+unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long length, low_limit, high_limit, gap_start, gap_end;
+
+	/* Adjust search length to account for worst case alignment overhead */
+	length = info->length + info->align_mask;
+	if (length < info->length)
+		return -ENOMEM;
+
+	/*
+	 * Adjust search limits by the desired length.
+	 * See implementation comment at top of unmapped_area().
+	 */
+	gap_end = info->high_limit;
+	if (gap_end < length)
+		return -ENOMEM;
+	high_limit = gap_end - length;
+
+	if (info->low_limit > high_limit)
+		return -ENOMEM;
+	low_limit = info->low_limit + length;
+
+	/* Check highest gap, which does not precede any rbtree node */
+	gap_start = mm->highest_vm_end;
+	if (gap_start <= high_limit)
+		goto found_highest;
+
+	/* Check if rbtree root looks promising */
+	if (RB_EMPTY_ROOT(&mm->mm_rb))
+		return -ENOMEM;
+	vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
+	if (vma->rb_subtree_gap < length)
+		return -ENOMEM;
+
+	while (true) {
+		/* Visit right subtree if it looks promising */
+		gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+		if (gap_start <= high_limit && vma->vm_rb.rb_right) {
+			struct vm_area_struct *right =
+				rb_entry(vma->vm_rb.rb_right,
+					 struct vm_area_struct, vm_rb);
+			if (right->rb_subtree_gap >= length) {
+				vma = right;
+				continue;
+			}
+		}
+
+check_current:
+		/* Check if current node has a suitable gap */
+		gap_end = vm_start_gap(vma);
+		if (gap_end < low_limit)
+			return -ENOMEM;
+		if (gap_start <= high_limit &&
+		    gap_end > gap_start && gap_end - gap_start >= length)
+			goto found;
+
+		/* Visit left subtree if it looks promising */
+		if (vma->vm_rb.rb_left) {
+			struct vm_area_struct *left =
+				rb_entry(vma->vm_rb.rb_left,
+					 struct vm_area_struct, vm_rb);
+			if (left->rb_subtree_gap >= length) {
+				vma = left;
+				continue;
+			}
+		}
+
+		/* Go back up the rbtree to find next candidate node */
+		while (true) {
+			struct rb_node *prev = &vma->vm_rb;
+			if (!rb_parent(prev))
+				return -ENOMEM;
+			vma = rb_entry(rb_parent(prev),
+				       struct vm_area_struct, vm_rb);
+			if (prev == vma->vm_rb.rb_right) {
+				gap_start = vma->vm_prev ?
+					vm_end_gap(vma->vm_prev) : 0;
+				goto check_current;
+			}
+		}
+	}
+
+found:
+	/* We found a suitable gap. Clip it with the original high_limit. */
+	if (gap_end > info->high_limit)
+		gap_end = info->high_limit;
+
+found_highest:
+	/* Compute highest gap address at the desired alignment */
+	gap_end -= info->length;
+	gap_end -= (gap_end - info->align_offset) & info->align_mask;
+
+	VM_BUG_ON(gap_end < info->low_limit);
+	VM_BUG_ON(gap_end < gap_start);
+	return gap_end;
+}
+
+/* Get an address range which is currently unmapped.
+ * For shmat() with addr=0.
+ *
+ * Ugly calling convention alert:
+ * Return value with the low bits set means error value,
+ * ie
+ *	if (ret & ~PAGE_MASK)
+ *		error = ret;
+ *
+ * This function "knows" that -ENOMEM has the bits set.
+ */
+#ifndef HAVE_ARCH_UNMAPPED_AREA
+unsigned long
+arch_get_unmapped_area(struct file *filp, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma, *prev;
+	struct vm_unmapped_area_info info;
+
+	if (len > TASK_SIZE - mmap_min_addr)
+		return -ENOMEM;
+
+	if (flags & MAP_FIXED)
+		return addr;
+
+	if (addr) {
+		addr = PAGE_ALIGN(addr);
+		vma = find_vma_prev(mm, addr, &prev);
+		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		    (!vma || addr + len <= vm_start_gap(vma)) &&
+		    (!prev || addr >= vm_end_gap(prev)))
+			return addr;
+	}
+
+	info.flags = 0;
+	info.length = len;
+	info.low_limit = mm->mmap_base;
+	info.high_limit = TASK_SIZE;
+	info.align_mask = 0;
+	return vm_unmapped_area(&info);
+}
+#endif
+
+/*
+ * This mmap-allocator allocates new areas top-down from below the
+ * stack's low limit (the base):
+ */
+#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+			  const unsigned long len, const unsigned long pgoff,
+			  const unsigned long flags)
+{
+	struct vm_area_struct *vma, *prev;
+	struct mm_struct *mm = current->mm;
+	unsigned long addr = addr0;
+	struct vm_unmapped_area_info info;
+
+	/* requested length too big for entire address space */
+	if (len > TASK_SIZE - mmap_min_addr)
+		return -ENOMEM;
+
+	if (flags & MAP_FIXED)
+		return addr;
+
+	/* requesting a specific address */
+	if (addr) {
+		addr = PAGE_ALIGN(addr);
+		vma = find_vma_prev(mm, addr, &prev);
+		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+				(!vma || addr + len <= vm_start_gap(vma)) &&
+				(!prev || addr >= vm_end_gap(prev)))
+			return addr;
+	}
+
+	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+	info.length = len;
+	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+	info.high_limit = mm->mmap_base;
+	info.align_mask = 0;
+	addr = vm_unmapped_area(&info);
+
+	/*
+	 * A failed mmap() very likely causes application failure,
+	 * so fall back to the bottom-up function here. This scenario
+	 * can happen with large stack limits and large mmap()
+	 * allocations.
+	 */
+	if (offset_in_page(addr)) {
+		VM_BUG_ON(addr != -ENOMEM);
+		info.flags = 0;
+		info.low_limit = TASK_UNMAPPED_BASE;
+		info.high_limit = TASK_SIZE;
+		addr = vm_unmapped_area(&info);
+	}
+
+	return addr;
+}
+#endif
+
+unsigned long
+get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
+		unsigned long pgoff, unsigned long flags)
+{
+	unsigned long (*get_area)(struct file *, unsigned long,
+				  unsigned long, unsigned long, unsigned long);
+
+	unsigned long error = arch_mmap_check(addr, len, flags);
+	if (error)
+		return error;
+
+	/* Careful about overflows.. */
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	get_area = current->mm->get_unmapped_area;
+	if (file && file->f_op->get_unmapped_area)
+		get_area = file->f_op->get_unmapped_area;
+	addr = get_area(file, addr, len, pgoff, flags);
+	if (IS_ERR_VALUE(addr))
+		return addr;
+
+	if (addr > TASK_SIZE - len)
+		return -ENOMEM;
+	if (offset_in_page(addr))
+		return -EINVAL;
+
+	addr = arch_rebalance_pgtables(addr, len);
+	error = security_mmap_addr(addr);
+	return error ? error : addr;
+}
+
+EXPORT_SYMBOL(get_unmapped_area);
+
+/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
+struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+{
+	struct rb_node *rb_node;
+	struct vm_area_struct *vma;
+
+	/* Check the cache first. */
+	vma = vmacache_find(mm, addr);
+	if (likely(vma))
+		return vma;
+
+	rb_node = mm->mm_rb.rb_node;
+
+	while (rb_node) {
+		struct vm_area_struct *tmp;
+
+		tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
+
+		if (tmp->vm_end > addr) {
+			vma = tmp;
+			if (tmp->vm_start <= addr)
+				break;
+			rb_node = rb_node->rb_left;
+		} else
+			rb_node = rb_node->rb_right;
+	}
+
+	if (vma)
+		vmacache_update(addr, vma);
+	return vma;
+}
+
+EXPORT_SYMBOL(find_vma);
+
+/*
+ * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
+ */
+struct vm_area_struct *
+find_vma_prev(struct mm_struct *mm, unsigned long addr,
+			struct vm_area_struct **pprev)
+{
+	struct vm_area_struct *vma;
+
+	vma = find_vma(mm, addr);
+	if (vma) {
+		*pprev = vma->vm_prev;
+	} else {
+		struct rb_node *rb_node = mm->mm_rb.rb_node;
+		*pprev = NULL;
+		while (rb_node) {
+			*pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
+			rb_node = rb_node->rb_right;
+		}
+	}
+	return vma;
+}
+
+/*
+ * Verify that the stack growth is acceptable and
+ * update accounting. This is shared with both the
+ * grow-up and grow-down cases.
+ */
+static int acct_stack_growth(struct vm_area_struct *vma,
+			     unsigned long size, unsigned long grow)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct rlimit *rlim = current->signal->rlim;
+	unsigned long new_start;
+
+	/* address space limit tests */
+	if (!may_expand_vm(mm, grow))
+		return -ENOMEM;
+
+	/* Stack limit test */
+	if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+		return -ENOMEM;
+
+	/* mlock limit tests */
+	if (vma->vm_flags & VM_LOCKED) {
+		unsigned long locked;
+		unsigned long limit;
+		locked = mm->locked_vm + grow;
+		limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
+		limit >>= PAGE_SHIFT;
+		if (locked > limit && !capable(CAP_IPC_LOCK))
+			return -ENOMEM;
+	}
+
+	/* Check to ensure the stack will not grow into a hugetlb-only region */
+	new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
+			vma->vm_end - size;
+	if (is_hugepage_only_range(vma->vm_mm, new_start, size))
+		return -EFAULT;
+
+	/*
+	 * Overcommit..  This must be the final test, as it will
+	 * update security statistics.
+	 */
+	if (security_vm_enough_memory_mm(mm, grow))
+		return -ENOMEM;
+
+	return 0;
+}
+
+#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
+/*
+ * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
+ * vma is the last one with address > vma->vm_end.  Have to extend vma.
+ */
+int expand_upwards(struct vm_area_struct *vma, unsigned long address)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *next;
+	unsigned long gap_addr;
+	int error = 0;
+
+	if (!(vma->vm_flags & VM_GROWSUP))
+		return -EFAULT;
+
+	/* Guard against exceeding limits of the address space. */
+	address &= PAGE_MASK;
+	if (address >= (TASK_SIZE & PAGE_MASK))
+		return -ENOMEM;
+	address += PAGE_SIZE;
+
+	/* Enforce stack_guard_gap */
+	gap_addr = address + stack_guard_gap;
+
+	/* Guard against overflow */
+	if (gap_addr < address || gap_addr > TASK_SIZE)
+		gap_addr = TASK_SIZE;
+
+	next = vma->vm_next;
+	if (next && next->vm_start < gap_addr) {
+		if (!(next->vm_flags & VM_GROWSUP))
+			return -ENOMEM;
+		/* Check that both stack segments have the same anon_vma? */
+	}
+
+	/* We must make sure the anon_vma is allocated. */
+	if (unlikely(anon_vma_prepare(vma)))
+		return -ENOMEM;
+
+	/*
+	 * vma->vm_start/vm_end cannot change under us because the caller
+	 * is required to hold the mmap_sem in read mode.  We need the
+	 * anon_vma lock to serialize against concurrent expand_stacks.
+	 */
+	anon_vma_lock_write(vma->anon_vma);
+
+	/* Somebody else might have raced and expanded it already */
+	if (address > vma->vm_end) {
+		unsigned long size, grow;
+
+		size = address - vma->vm_start;
+		grow = (address - vma->vm_end) >> PAGE_SHIFT;
+
+		error = -ENOMEM;
+		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+			error = acct_stack_growth(vma, size, grow);
+			if (!error) {
+				/*
+				 * vma_gap_update() doesn't support concurrent
+				 * updates, but we only hold a shared mmap_sem
+				 * lock here, so we need to protect against
+				 * concurrent vma expansions.
+				 * anon_vma_lock_write() doesn't help here, as
+				 * we don't guarantee that all growable vmas
+				 * in a mm share the same root anon vma.
+				 * So, we reuse mm->page_table_lock to guard
+				 * against concurrent vma expansions.
+				 */
+				spin_lock(&mm->page_table_lock);
+				if (vma->vm_flags & VM_LOCKED)
+					mm->locked_vm += grow;
+				vm_stat_account(mm, vma->vm_flags,
+						vma->vm_file, grow);
+				anon_vma_interval_tree_pre_update_vma(vma);
+				vma->vm_end = address;
+				anon_vma_interval_tree_post_update_vma(vma);
+				if (vma->vm_next)
+					vma_gap_update(vma->vm_next);
+				else
+					mm->highest_vm_end = vm_end_gap(vma);
+				spin_unlock(&mm->page_table_lock);
+
+				perf_event_mmap(vma);
+			}
+		}
+	}
+	anon_vma_unlock_write(vma->anon_vma);
+	khugepaged_enter_vma_merge(vma, vma->vm_flags);
+	validate_mm(mm);
+	return error;
+}
+#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
+
+/*
+ * vma is the first one with address < vma->vm_start.  Have to extend vma.
+ */
+int expand_downwards(struct vm_area_struct *vma,
+				   unsigned long address)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *prev;
+	unsigned long gap_addr;
+	int error;
+
+	address &= PAGE_MASK;
+	error = security_mmap_addr(address);
+	if (error)
+		return error;
+
+	/* Enforce stack_guard_gap */
+	gap_addr = address - stack_guard_gap;
+	if (gap_addr > address)
+		return -ENOMEM;
+	prev = vma->vm_prev;
+	if (prev && prev->vm_end > gap_addr) {
+		if (!(prev->vm_flags & VM_GROWSDOWN))
+			return -ENOMEM;
+		/* Check that both stack segments have the same anon_vma? */
+	}
+
+	/* We must make sure the anon_vma is allocated. */
+	if (unlikely(anon_vma_prepare(vma)))
+		return -ENOMEM;
+
+	/*
+	 * vma->vm_start/vm_end cannot change under us because the caller
+	 * is required to hold the mmap_sem in read mode.  We need the
+	 * anon_vma lock to serialize against concurrent expand_stacks.
+	 */
+	anon_vma_lock_write(vma->anon_vma);
+
+	/* Somebody else might have raced and expanded it already */
+	if (address < vma->vm_start) {
+		unsigned long size, grow;
+
+		size = vma->vm_end - address;
+		grow = (vma->vm_start - address) >> PAGE_SHIFT;
+
+		error = -ENOMEM;
+		if (grow <= vma->vm_pgoff) {
+			error = acct_stack_growth(vma, size, grow);
+			if (!error) {
+				/*
+				 * vma_gap_update() doesn't support concurrent
+				 * updates, but we only hold a shared mmap_sem
+				 * lock here, so we need to protect against
+				 * concurrent vma expansions.
+				 * anon_vma_lock_write() doesn't help here, as
+				 * we don't guarantee that all growable vmas
+				 * in a mm share the same root anon vma.
+				 * So, we reuse mm->page_table_lock to guard
+				 * against concurrent vma expansions.
+				 */
+				spin_lock(&mm->page_table_lock);
+				if (vma->vm_flags & VM_LOCKED)
+					mm->locked_vm += grow;
+				vm_stat_account(mm, vma->vm_flags,
+						vma->vm_file, grow);
+				anon_vma_interval_tree_pre_update_vma(vma);
+				vma->vm_start = address;
+				vma->vm_pgoff -= grow;
+				anon_vma_interval_tree_post_update_vma(vma);
+				vma_gap_update(vma);
+				spin_unlock(&mm->page_table_lock);
+
+				perf_event_mmap(vma);
+			}
+		}
+	}
+	anon_vma_unlock_write(vma->anon_vma);
+	khugepaged_enter_vma_merge(vma, vma->vm_flags);
+	validate_mm(mm);
+	return error;
+}
+
+/* enforced gap between the expanding stack and other mappings. */
+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
+
+static int __init cmdline_parse_stack_guard_gap(char *p)
+{
+	unsigned long val;
+	char *endptr;
+
+	val = simple_strtoul(p, &endptr, 10);
+	if (!*endptr)
+		stack_guard_gap = val << PAGE_SHIFT;
+
+	return 0;
+}
+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
+
+#ifdef CONFIG_STACK_GROWSUP
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+	return expand_upwards(vma, address);
+}
+
+struct vm_area_struct *
+find_extend_vma(struct mm_struct *mm, unsigned long addr)
+{
+	struct vm_area_struct *vma, *prev;
+
+	addr &= PAGE_MASK;
+	vma = find_vma_prev(mm, addr, &prev);
+	if (vma && (vma->vm_start <= addr))
+		return vma;
+	if (!prev || expand_stack(prev, addr))
+		return NULL;
+	if (prev->vm_flags & VM_LOCKED)
+		populate_vma_page_range(prev, addr, prev->vm_end, NULL);
+	return prev;
+}
+#else
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+	return expand_downwards(vma, address);
+}
+
+struct vm_area_struct *
+find_extend_vma(struct mm_struct *mm, unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	unsigned long start;
+
+	addr &= PAGE_MASK;
+	vma = find_vma(mm, addr);
+	if (!vma)
+		return NULL;
+	if (vma->vm_start <= addr)
+		return vma;
+	if (!(vma->vm_flags & VM_GROWSDOWN))
+		return NULL;
+	start = vma->vm_start;
+	if (expand_stack(vma, addr))
+		return NULL;
+	if (vma->vm_flags & VM_LOCKED)
+		populate_vma_page_range(vma, addr, start, NULL);
+	return vma;
+}
+#endif
+
+EXPORT_SYMBOL_GPL(find_extend_vma);
+
+/*
+ * Ok - we have the memory areas we should free on the vma list,
+ * so release them, and do the vma updates.
+ *
+ * Called with the mm semaphore held.
+ */
+static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	unsigned long nr_accounted = 0;
+
+	/* Update high watermark before we lower total_vm */
+	update_hiwater_vm(mm);
+	do {
+		long nrpages = vma_pages(vma);
+
+		if (vma->vm_flags & VM_ACCOUNT)
+			nr_accounted += nrpages;
+		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
+		vma = remove_vma(vma);
+	} while (vma);
+	vm_unacct_memory(nr_accounted);
+	validate_mm(mm);
+}
+
+/*
+ * Get rid of page table information in the indicated region.
+ *
+ * Called with the mm semaphore held.
+ */
+static void unmap_region(struct mm_struct *mm,
+		struct vm_area_struct *vma, struct vm_area_struct *prev,
+		unsigned long start, unsigned long end)
+{
+	struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
+	struct mmu_gather tlb;
+
+	lru_add_drain();
+	tlb_gather_mmu(&tlb, mm, start, end);
+	update_hiwater_rss(mm);
+	unmap_vmas(&tlb, vma, start, end);
+	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
+				 next ? next->vm_start : USER_PGTABLES_CEILING);
+	tlb_finish_mmu(&tlb, start, end);
+}
+
+/*
+ * Create a list of vma's touched by the unmap, removing them from the mm's
+ * vma list as we go..
+ */
+static void
+detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
+	struct vm_area_struct *prev, unsigned long end)
+{
+	struct vm_area_struct **insertion_point;
+	struct vm_area_struct *tail_vma = NULL;
+
+	insertion_point = (prev ? &prev->vm_next : &mm->mmap);
+	vma->vm_prev = NULL;
+	do {
+		vma_rb_erase(vma, &mm->mm_rb);
+		mm->map_count--;
+		tail_vma = vma;
+		vma = vma->vm_next;
+	} while (vma && vma->vm_start < end);
+	*insertion_point = vma;
+	if (vma) {
+		vma->vm_prev = prev;
+		vma_gap_update(vma);
+	} else
+		mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
+	tail_vma->vm_next = NULL;
+
+	/* Kill the cache */
+	vmacache_invalidate(mm);
+}
+
+/*
+ * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
+ * munmap path where it doesn't make sense to fail.
+ */
+static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
+	      unsigned long addr, int new_below)
+{
+	struct vm_area_struct *new;
+	int err;
+
+	if (is_vm_hugetlb_page(vma) && (addr &
+					~(huge_page_mask(hstate_vma(vma)))))
+		return -EINVAL;
+
+	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	/* most fields are the same, copy all, and then fixup */
+	*new = *vma;
+
+	INIT_LIST_HEAD(&new->anon_vma_chain);
+
+	if (new_below)
+		new->vm_end = addr;
+	else {
+		new->vm_start = addr;
+		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
+	}
+
+	err = vma_dup_policy(vma, new);
+	if (err)
+		goto out_free_vma;
+
+	err = anon_vma_clone(new, vma);
+	if (err)
+		goto out_free_mpol;
+
+	if (new->vm_file)
+		get_file(new->vm_file);
+
+	if (new->vm_ops && new->vm_ops->open)
+		new->vm_ops->open(new);
+
+	if (new_below)
+		err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
+			((addr - new->vm_start) >> PAGE_SHIFT), new);
+	else
+		err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
+
+	/* Success. */
+	if (!err)
+		return 0;
+
+	/* Clean everything up if vma_adjust failed. */
+	if (new->vm_ops && new->vm_ops->close)
+		new->vm_ops->close(new);
+	if (new->vm_file)
+		fput(new->vm_file);
+	unlink_anon_vmas(new);
+ out_free_mpol:
+	mpol_put(vma_policy(new));
+ out_free_vma:
+	kmem_cache_free(vm_area_cachep, new);
+	return err;
+}
+
+/*
+ * Split a vma into two pieces at address 'addr', a new vma is allocated
+ * either for the first part or the tail.
+ */
+int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
+	      unsigned long addr, int new_below)
+{
+	if (mm->map_count >= sysctl_max_map_count)
+		return -ENOMEM;
+
+	return __split_vma(mm, vma, addr, new_below);
+}
+
+/* Munmap is split into 2 main parts -- this part which finds
+ * what needs doing, and the areas themselves, which do the
+ * work.  This now handles partial unmappings.
+ * Jeremy Fitzhardinge <jeremy@goop.org>
+ */
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+{
+	unsigned long end;
+	struct vm_area_struct *vma, *prev, *last;
+
+	if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
+		return -EINVAL;
+
+	len = PAGE_ALIGN(len);
+	if (len == 0)
+		return -EINVAL;
+
+	/* Find the first overlapping VMA */
+	vma = find_vma(mm, start);
+	if (!vma)
+		return 0;
+	prev = vma->vm_prev;
+	/* we have  start < vma->vm_end  */
+
+	/* if it doesn't overlap, we have nothing.. */
+	end = start + len;
+	if (vma->vm_start >= end)
+		return 0;
+
+	/*
+	 * If we need to split any vma, do it now to save pain later.
+	 *
+	 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
+	 * unmapped vm_area_struct will remain in use: so lower split_vma
+	 * places tmp vma above, and higher split_vma places tmp vma below.
+	 */
+	if (start > vma->vm_start) {
+		int error;
+
+		/*
+		 * Make sure that map_count on return from munmap() will
+		 * not exceed its limit; but let map_count go just above
+		 * its limit temporarily, to help free resources as expected.
+		 */
+		if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
+			return -ENOMEM;
+
+		error = __split_vma(mm, vma, start, 0);
+		if (error)
+			return error;
+		prev = vma;
+	}
+
+	/* Does it split the last one? */
+	last = find_vma(mm, end);
+	if (last && end > last->vm_start) {
+		int error = __split_vma(mm, last, end, 1);
+		if (error)
+			return error;
+	}
+	vma = prev ? prev->vm_next : mm->mmap;
+
+	/*
+	 * unlock any mlock()ed ranges before detaching vmas
+	 */
+	if (mm->locked_vm) {
+		struct vm_area_struct *tmp = vma;
+		while (tmp && tmp->vm_start < end) {
+			if (tmp->vm_flags & VM_LOCKED) {
+				mm->locked_vm -= vma_pages(tmp);
+				munlock_vma_pages_all(tmp);
+			}
+			tmp = tmp->vm_next;
+		}
+	}
+
+	/*
+	 * Remove the vma's, and unmap the actual pages
+	 */
+	detach_vmas_to_be_unmapped(mm, vma, prev, end);
+	unmap_region(mm, vma, prev, start, end);
+
+	arch_unmap(mm, vma, start, end);
+
+	/* Fix up all other VM information */
+	remove_vma_list(mm, vma);
+
+	return 0;
+}
+
+int vm_munmap(unsigned long start, size_t len)
+{
+	int ret;
+	struct mm_struct *mm = current->mm;
+
+	down_write(&mm->mmap_sem);
+	ret = do_munmap(mm, start, len);
+	up_write(&mm->mmap_sem);
+	return ret;
+}
+EXPORT_SYMBOL(vm_munmap);
+
+SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
+{
+	profile_munmap(addr);
+	return vm_munmap(addr, len);
+}
+
+
+/*
+ * Emulation of deprecated remap_file_pages() syscall.
+ */
+SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
+		unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
+{
+
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long populate = 0;
+	unsigned long ret = -EINVAL;
+	struct file *file;
+
+	pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
+			"See Documentation/vm/remap_file_pages.txt.\n",
+			current->comm, current->pid);
+
+	if (prot)
+		return ret;
+	start = start & PAGE_MASK;
+	size = size & PAGE_MASK;
+
+	if (start + size <= start)
+		return ret;
+
+	/* Does pgoff wrap? */
+	if (pgoff + (size >> PAGE_SHIFT) < pgoff)
+		return ret;
+
+	down_write(&mm->mmap_sem);
+	vma = find_vma(mm, start);
+
+	if (!vma || !(vma->vm_flags & VM_SHARED))
+		goto out;
+
+	if (start < vma->vm_start)
+		goto out;
+
+	if (start + size > vma->vm_end) {
+		struct vm_area_struct *next;
+
+		for (next = vma->vm_next; next; next = next->vm_next) {
+			/* hole between vmas ? */
+			if (next->vm_start != next->vm_prev->vm_end)
+				goto out;
+
+			if (next->vm_file != vma->vm_file)
+				goto out;
+
+			if (next->vm_flags != vma->vm_flags)
+				goto out;
+
+			if (start + size <= next->vm_end)
+				break;
+		}
+
+		if (!next)
+			goto out;
+	}
+
+	prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
+	prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
+	prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
+
+	flags &= MAP_NONBLOCK;
+	flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
+	if (vma->vm_flags & VM_LOCKED) {
+		struct vm_area_struct *tmp;
+		flags |= MAP_LOCKED;
+
+		/* drop PG_Mlocked flag for over-mapped range */
+		for (tmp = vma; tmp->vm_start >= start + size;
+				tmp = tmp->vm_next) {
+			munlock_vma_pages_range(tmp,
+					max(tmp->vm_start, start),
+					min(tmp->vm_end, start + size));
+		}
+	}
+
+	file = get_file(vma->vm_file);
+	ret = do_mmap_pgoff(vma->vm_file, start, size,
+			prot, flags, pgoff, &populate);
+	fput(file);
+out:
+	up_write(&mm->mmap_sem);
+	if (populate)
+		mm_populate(ret, populate);
+	if (!IS_ERR_VALUE(ret))
+		ret = 0;
+	return ret;
+}
+
+static inline void verify_mm_writelocked(struct mm_struct *mm)
+{
+#ifdef CONFIG_DEBUG_VM
+	if (unlikely(down_read_trylock(&mm->mmap_sem))) {
+		WARN_ON(1);
+		up_read(&mm->mmap_sem);
+	}
+#endif
+}
+
+/*
+ *  this is really a simplified "do_mmap".  it only handles
+ *  anonymous maps.  eventually we may be able to do some
+ *  brk-specific accounting here.
+ */
+static unsigned long do_brk(unsigned long addr, unsigned long len)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma, *prev;
+	unsigned long flags;
+	struct rb_node **rb_link, *rb_parent;
+	pgoff_t pgoff = addr >> PAGE_SHIFT;
+	int error;
+
+	len = PAGE_ALIGN(len);
+	if (!len)
+		return addr;
+
+	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
+
+	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
+	if (offset_in_page(error))
+		return error;
+
+	error = mlock_future_check(mm, mm->def_flags, len);
+	if (error)
+		return error;
+
+	/*
+	 * mm->mmap_sem is required to protect against another thread
+	 * changing the mappings in case we sleep.
+	 */
+	verify_mm_writelocked(mm);
+
+	/*
+	 * Clear old maps.  this also does some error checking for us
+	 */
+	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
+			      &rb_parent)) {
+		if (do_munmap(mm, addr, len))
+			return -ENOMEM;
+	}
+
+	/* Check against address space limits *after* clearing old maps... */
+	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
+		return -ENOMEM;
+
+	if (mm->map_count > sysctl_max_map_count)
+		return -ENOMEM;
+
+	if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
+		return -ENOMEM;
+
+	/* Can we just expand an old private anonymous mapping? */
+	vma = vma_merge(mm, prev, addr, addr + len, flags,
+			NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
+	if (vma)
+		goto out;
+
+	/*
+	 * create a vma struct for an anonymous mapping
+	 */
+	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+	if (!vma) {
+		vm_unacct_memory(len >> PAGE_SHIFT);
+		return -ENOMEM;
+	}
+
+	INIT_LIST_HEAD(&vma->anon_vma_chain);
+	vma->vm_mm = mm;
+	vma->vm_start = addr;
+	vma->vm_end = addr + len;
+	vma->vm_pgoff = pgoff;
+	vma->vm_flags = flags;
+	vma->vm_page_prot = vm_get_page_prot(flags);
+	vma_link(mm, vma, prev, rb_link, rb_parent);
+out:
+	perf_event_mmap(vma);
+	mm->total_vm += len >> PAGE_SHIFT;
+	if (flags & VM_LOCKED)
+		mm->locked_vm += (len >> PAGE_SHIFT);
+	vma->vm_flags |= VM_SOFTDIRTY;
+	return addr;
+}
+
+unsigned long vm_brk(unsigned long addr, unsigned long len)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long ret;
+	bool populate;
+
+	down_write(&mm->mmap_sem);
+	ret = do_brk(addr, len);
+	populate = ((mm->def_flags & VM_LOCKED) != 0);
+	up_write(&mm->mmap_sem);
+	if (populate)
+		mm_populate(addr, len);
+	return ret;
+}
+EXPORT_SYMBOL(vm_brk);
+
+/* Release all mmaps. */
+void exit_mmap(struct mm_struct *mm)
+{
+	struct mmu_gather tlb;
+	struct vm_area_struct *vma;
+	unsigned long nr_accounted = 0;
+
+	/* mm's last user has gone, and its about to be pulled down */
+	mmu_notifier_release(mm);
+
+	if (mm->locked_vm) {
+		vma = mm->mmap;
+		while (vma) {
+			if (vma->vm_flags & VM_LOCKED)
+				munlock_vma_pages_all(vma);
+			vma = vma->vm_next;
+		}
+	}
+
+	arch_exit_mmap(mm);
+
+	vma = mm->mmap;
+	if (!vma)	/* Can happen if dup_mmap() received an OOM */
+		return;
+
+	lru_add_drain();
+	flush_cache_mm(mm);
+	tlb_gather_mmu(&tlb, mm, 0, -1);
+	/* update_hiwater_rss(mm) here? but nobody should be looking */
+	/* Use -1 here to ensure all VMAs in the mm are unmapped */
+	unmap_vmas(&tlb, vma, 0, -1);
+
+	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
+	tlb_finish_mmu(&tlb, 0, -1);
+
+	/*
+	 * Walk the list again, actually closing and freeing it,
+	 * with preemption enabled, without holding any MM locks.
+	 */
+	while (vma) {
+		if (vma->vm_flags & VM_ACCOUNT)
+			nr_accounted += vma_pages(vma);
+		vma = remove_vma(vma);
+	}
+	vm_unacct_memory(nr_accounted);
+}
+
+/* Insert vm structure into process list sorted by address
+ * and into the inode's i_mmap tree.  If vm_file is non-NULL
+ * then i_mmap_rwsem is taken here.
+ */
+int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	struct vm_area_struct *prev;
+	struct rb_node **rb_link, *rb_parent;
+
+	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
+			   &prev, &rb_link, &rb_parent))
+		return -ENOMEM;
+	if ((vma->vm_flags & VM_ACCOUNT) &&
+	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
+		return -ENOMEM;
+
+	/*
+	 * The vm_pgoff of a purely anonymous vma should be irrelevant
+	 * until its first write fault, when page's anon_vma and index
+	 * are set.  But now set the vm_pgoff it will almost certainly
+	 * end up with (unless mremap moves it elsewhere before that
+	 * first wfault), so /proc/pid/maps tells a consistent story.
+	 *
+	 * By setting it to reflect the virtual start address of the
+	 * vma, merges and splits can happen in a seamless way, just
+	 * using the existing file pgoff checks and manipulations.
+	 * Similarly in do_mmap_pgoff and in do_brk.
+	 */
+	if (vma_is_anonymous(vma)) {
+		BUG_ON(vma->anon_vma);
+		vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
+	}
+
+	vma_link(mm, vma, prev, rb_link, rb_parent);
+	return 0;
+}
+
+/*
+ * Copy the vma structure to a new location in the same mm,
+ * prior to moving page table entries, to effect an mremap move.
+ */
+struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
+	unsigned long addr, unsigned long len, pgoff_t pgoff,
+	bool *need_rmap_locks)
+{
+	struct vm_area_struct *vma = *vmap;
+	unsigned long vma_start = vma->vm_start;
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *new_vma, *prev;
+	struct rb_node **rb_link, *rb_parent;
+	bool faulted_in_anon_vma = true;
+
+	/*
+	 * If anonymous vma has not yet been faulted, update new pgoff
+	 * to match new location, to increase its chance of merging.
+	 */
+	if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
+		pgoff = addr >> PAGE_SHIFT;
+		faulted_in_anon_vma = false;
+	}
+
+	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
+		return NULL;	/* should never get here */
+	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
+			    vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+			    vma->vm_userfaultfd_ctx);
+	if (new_vma) {
+		/*
+		 * Source vma may have been merged into new_vma
+		 */
+		if (unlikely(vma_start >= new_vma->vm_start &&
+			     vma_start < new_vma->vm_end)) {
+			/*
+			 * The only way we can get a vma_merge with
+			 * self during an mremap is if the vma hasn't
+			 * been faulted in yet and we were allowed to
+			 * reset the dst vma->vm_pgoff to the
+			 * destination address of the mremap to allow
+			 * the merge to happen. mremap must change the
+			 * vm_pgoff linearity between src and dst vmas
+			 * (in turn preventing a vma_merge) to be
+			 * safe. It is only safe to keep the vm_pgoff
+			 * linear if there are no pages mapped yet.
+			 */
+			VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
+			*vmap = vma = new_vma;
+		}
+		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
+	} else {
+		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+		if (!new_vma)
+			goto out;
+		*new_vma = *vma;
+		new_vma->vm_start = addr;
+		new_vma->vm_end = addr + len;
+		new_vma->vm_pgoff = pgoff;
+		if (vma_dup_policy(vma, new_vma))
+			goto out_free_vma;
+		INIT_LIST_HEAD(&new_vma->anon_vma_chain);
+		if (anon_vma_clone(new_vma, vma))
+			goto out_free_mempol;
+		if (new_vma->vm_file)
+			get_file(new_vma->vm_file);
+		if (new_vma->vm_ops && new_vma->vm_ops->open)
+			new_vma->vm_ops->open(new_vma);
+		vma_link(mm, new_vma, prev, rb_link, rb_parent);
+		*need_rmap_locks = false;
+	}
+	return new_vma;
+
+out_free_mempol:
+	mpol_put(vma_policy(new_vma));
+out_free_vma:
+	kmem_cache_free(vm_area_cachep, new_vma);
+out:
+	return NULL;
+}
+
+/*
+ * Return true if the calling process may expand its vm space by the passed
+ * number of pages
+ */
+int may_expand_vm(struct mm_struct *mm, unsigned long npages)
+{
+	unsigned long cur = mm->total_vm;	/* pages */
+	unsigned long lim;
+
+	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
+
+	if (cur + npages > lim)
+		return 0;
+	return 1;
+}
+
+static int special_mapping_fault(struct vm_area_struct *vma,
+				 struct vm_fault *vmf);
+
+/*
+ * Having a close hook prevents vma merging regardless of flags.
+ */
+static void special_mapping_close(struct vm_area_struct *vma)
+{
+}
+
+static const char *special_mapping_name(struct vm_area_struct *vma)
+{
+	return ((struct vm_special_mapping *)vma->vm_private_data)->name;
+}
+
+static const struct vm_operations_struct special_mapping_vmops = {
+	.close = special_mapping_close,
+	.fault = special_mapping_fault,
+	.name = special_mapping_name,
+};
+
+static const struct vm_operations_struct legacy_special_mapping_vmops = {
+	.close = special_mapping_close,
+	.fault = special_mapping_fault,
+};
+
+static int special_mapping_fault(struct vm_area_struct *vma,
+				struct vm_fault *vmf)
+{
+	pgoff_t pgoff;
+	struct page **pages;
+
+	if (vma->vm_ops == &legacy_special_mapping_vmops)
+		pages = vma->vm_private_data;
+	else
+		pages = ((struct vm_special_mapping *)vma->vm_private_data)->
+			pages;
+
+	for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
+		pgoff--;
+
+	if (*pages) {
+		struct page *page = *pages;
+		get_page(page);
+		vmf->page = page;
+		return 0;
+	}
+
+	return VM_FAULT_SIGBUS;
+}
+
+static struct vm_area_struct *__install_special_mapping(
+	struct mm_struct *mm,
+	unsigned long addr, unsigned long len,
+	unsigned long vm_flags, void *priv,
+	const struct vm_operations_struct *ops)
+{
+	int ret;
+	struct vm_area_struct *vma;
+
+	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+	if (unlikely(vma == NULL))
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&vma->anon_vma_chain);
+	vma->vm_mm = mm;
+	vma->vm_start = addr;
+	vma->vm_end = addr + len;
+
+	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
+	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+	vma->vm_ops = ops;
+	vma->vm_private_data = priv;
+
+	ret = insert_vm_struct(mm, vma);
+	if (ret)
+		goto out;
+
+	mm->total_vm += len >> PAGE_SHIFT;
+
+	perf_event_mmap(vma);
+
+	return vma;
+
+out:
+	kmem_cache_free(vm_area_cachep, vma);
+	return ERR_PTR(ret);
+}
+
+/*
+ * Called with mm->mmap_sem held for writing.
+ * Insert a new vma covering the given region, with the given flags.
+ * Its pages are supplied by the given array of struct page *.
+ * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
+ * The region past the last page supplied will always produce SIGBUS.
+ * The array pointer and the pages it points to are assumed to stay alive
+ * for as long as this mapping might exist.
+ */
+struct vm_area_struct *_install_special_mapping(
+	struct mm_struct *mm,
+	unsigned long addr, unsigned long len,
+	unsigned long vm_flags, const struct vm_special_mapping *spec)
+{
+	return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
+					&special_mapping_vmops);
+}
+
+int install_special_mapping(struct mm_struct *mm,
+			    unsigned long addr, unsigned long len,
+			    unsigned long vm_flags, struct page **pages)
+{
+	struct vm_area_struct *vma = __install_special_mapping(
+		mm, addr, len, vm_flags, (void *)pages,
+		&legacy_special_mapping_vmops);
+
+	return PTR_ERR_OR_ZERO(vma);
+}
+
+static DEFINE_MUTEX(mm_all_locks_mutex);
+
+static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
+{
+	if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
+		/*
+		 * The LSB of head.next can't change from under us
+		 * because we hold the mm_all_locks_mutex.
+		 */
+		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
+		/*
+		 * We can safely modify head.next after taking the
+		 * anon_vma->root->rwsem. If some other vma in this mm shares
+		 * the same anon_vma we won't take it again.
+		 *
+		 * No need of atomic instructions here, head.next
+		 * can't change from under us thanks to the
+		 * anon_vma->root->rwsem.
+		 */
+		if (__test_and_set_bit(0, (unsigned long *)
+				       &anon_vma->root->rb_root.rb_node))
+			BUG();
+	}
+}
+
+static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
+{
+	if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
+		/*
+		 * AS_MM_ALL_LOCKS can't change from under us because
+		 * we hold the mm_all_locks_mutex.
+		 *
+		 * Operations on ->flags have to be atomic because
+		 * even if AS_MM_ALL_LOCKS is stable thanks to the
+		 * mm_all_locks_mutex, there may be other cpus
+		 * changing other bitflags in parallel to us.
+		 */
+		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
+			BUG();
+		down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
+	}
+}
+
+/*
+ * This operation locks against the VM for all pte/vma/mm related
+ * operations that could ever happen on a certain mm. This includes
+ * vmtruncate, try_to_unmap, and all page faults.
+ *
+ * The caller must take the mmap_sem in write mode before calling
+ * mm_take_all_locks(). The caller isn't allowed to release the
+ * mmap_sem until mm_drop_all_locks() returns.
+ *
+ * mmap_sem in write mode is required in order to block all operations
+ * that could modify pagetables and free pages without need of
+ * altering the vma layout. It's also needed in write mode to avoid new
+ * anon_vmas to be associated with existing vmas.
+ *
+ * A single task can't take more than one mm_take_all_locks() in a row
+ * or it would deadlock.
+ *
+ * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
+ * mapping->flags avoid to take the same lock twice, if more than one
+ * vma in this mm is backed by the same anon_vma or address_space.
+ *
+ * We can take all the locks in random order because the VM code
+ * taking i_mmap_rwsem or anon_vma->rwsem outside the mmap_sem never
+ * takes more than one of them in a row. Secondly we're protected
+ * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
+ *
+ * mm_take_all_locks() and mm_drop_all_locks are expensive operations
+ * that may have to take thousand of locks.
+ *
+ * mm_take_all_locks() can fail if it's interrupted by signals.
+ */
+int mm_take_all_locks(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+	struct anon_vma_chain *avc;
+
+	BUG_ON(down_read_trylock(&mm->mmap_sem));
+
+	mutex_lock(&mm_all_locks_mutex);
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (signal_pending(current))
+			goto out_unlock;
+		if (vma->vm_file && vma->vm_file->f_mapping)
+			vm_lock_mapping(mm, vma->vm_file->f_mapping);
+	}
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (signal_pending(current))
+			goto out_unlock;
+		if (vma->anon_vma)
+			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+				vm_lock_anon_vma(mm, avc->anon_vma);
+	}
+
+	return 0;
+
+out_unlock:
+	mm_drop_all_locks(mm);
+	return -EINTR;
+}
+
+static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
+{
+	if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
+		/*
+		 * The LSB of head.next can't change to 0 from under
+		 * us because we hold the mm_all_locks_mutex.
+		 *
+		 * We must however clear the bitflag before unlocking
+		 * the vma so the users using the anon_vma->rb_root will
+		 * never see our bitflag.
+		 *
+		 * No need of atomic instructions here, head.next
+		 * can't change from under us until we release the
+		 * anon_vma->root->rwsem.
+		 */
+		if (!__test_and_clear_bit(0, (unsigned long *)
+					  &anon_vma->root->rb_root.rb_node))
+			BUG();
+		anon_vma_unlock_write(anon_vma);
+	}
+}
+
+static void vm_unlock_mapping(struct address_space *mapping)
+{
+	if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
+		/*
+		 * AS_MM_ALL_LOCKS can't change to 0 from under us
+		 * because we hold the mm_all_locks_mutex.
+		 */
+		i_mmap_unlock_write(mapping);
+		if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
+					&mapping->flags))
+			BUG();
+	}
+}
+
+/*
+ * The mmap_sem cannot be released by the caller until
+ * mm_drop_all_locks() returns.
+ */
+void mm_drop_all_locks(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+	struct anon_vma_chain *avc;
+
+	BUG_ON(down_read_trylock(&mm->mmap_sem));
+	BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (vma->anon_vma)
+			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+				vm_unlock_anon_vma(avc->anon_vma);
+		if (vma->vm_file && vma->vm_file->f_mapping)
+			vm_unlock_mapping(vma->vm_file->f_mapping);
+	}
+
+	mutex_unlock(&mm_all_locks_mutex);
+}
+
+/*
+ * initialise the VMA slab
+ */
+void __init mmap_init(void)
+{
+	int ret;
+
+	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
+	VM_BUG_ON(ret);
+}
+
+/*
+ * Initialise sysctl_user_reserve_kbytes.
+ *
+ * This is intended to prevent a user from starting a single memory hogging
+ * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
+ * mode.
+ *
+ * The default value is min(3% of free memory, 128MB)
+ * 128MB is enough to recover with sshd/login, bash, and top/kill.
+ */
+static int init_user_reserve(void)
+{
+	unsigned long free_kbytes;
+
+	free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+	sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
+	return 0;
+}
+subsys_initcall(init_user_reserve);
+
+/*
+ * Initialise sysctl_admin_reserve_kbytes.
+ *
+ * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
+ * to log in and kill a memory hogging process.
+ *
+ * Systems with more than 256MB will reserve 8MB, enough to recover
+ * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
+ * only reserve 3% of free pages by default.
+ */
+static int init_admin_reserve(void)
+{
+	unsigned long free_kbytes;
+
+	free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+	sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
+	return 0;
+}
+subsys_initcall(init_admin_reserve);
+
+/*
+ * Reinititalise user and admin reserves if memory is added or removed.
+ *
+ * The default user reserve max is 128MB, and the default max for the
+ * admin reserve is 8MB. These are usually, but not always, enough to
+ * enable recovery from a memory hogging process using login/sshd, a shell,
+ * and tools like top. It may make sense to increase or even disable the
+ * reserve depending on the existence of swap or variations in the recovery
+ * tools. So, the admin may have changed them.
+ *
+ * If memory is added and the reserves have been eliminated or increased above
+ * the default max, then we'll trust the admin.
+ *
+ * If memory is removed and there isn't enough free memory, then we
+ * need to reset the reserves.
+ *
+ * Otherwise keep the reserve set by the admin.
+ */
+static int reserve_mem_notifier(struct notifier_block *nb,
+			     unsigned long action, void *data)
+{
+	unsigned long tmp, free_kbytes;
+
+	switch (action) {
+	case MEM_ONLINE:
+		/* Default max is 128MB. Leave alone if modified by operator. */
+		tmp = sysctl_user_reserve_kbytes;
+		if (0 < tmp && tmp < (1UL << 17))
+			init_user_reserve();
+
+		/* Default max is 8MB.  Leave alone if modified by operator. */
+		tmp = sysctl_admin_reserve_kbytes;
+		if (0 < tmp && tmp < (1UL << 13))
+			init_admin_reserve();
+
+		break;
+	case MEM_OFFLINE:
+		free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+		if (sysctl_user_reserve_kbytes > free_kbytes) {
+			init_user_reserve();
+			pr_info("vm.user_reserve_kbytes reset to %lu\n",
+				sysctl_user_reserve_kbytes);
+		}
+
+		if (sysctl_admin_reserve_kbytes > free_kbytes) {
+			init_admin_reserve();
+			pr_info("vm.admin_reserve_kbytes reset to %lu\n",
+				sysctl_admin_reserve_kbytes);
+		}
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block reserve_mem_nb = {
+	.notifier_call = reserve_mem_notifier,
+};
+
+static int __meminit init_reserve_notifier(void)
+{
+	if (register_hotmemory_notifier(&reserve_mem_nb))
+		pr_err("Failed registering memory add/remove notifier for admin reserve\n");
+
+	return 0;
+}
+subsys_initcall(init_reserve_notifier);
diff --git a/mm/mmu_context.c b/mm/mmu_context.c
new file mode 100644
index 0000000..f802c2d
--- /dev/null
+++ b/mm/mmu_context.c
@@ -0,0 +1,62 @@
+/* Copyright (C) 2009 Red Hat, Inc.
+ *
+ * See ../COPYING for licensing terms.
+ */
+
+#include <linux/mm.h>
+#include <linux/mmu_context.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+
+#include <asm/mmu_context.h>
+
+/*
+ * use_mm
+ *	Makes the calling kernel thread take on the specified
+ *	mm context.
+ *	(Note: this routine is intended to be called only
+ *	from a kernel thread context)
+ */
+void use_mm(struct mm_struct *mm)
+{
+	struct mm_struct *active_mm;
+	struct task_struct *tsk = current;
+
+	task_lock(tsk);
+	active_mm = tsk->active_mm;
+	if (active_mm != mm) {
+		atomic_inc(&mm->mm_count);
+		tsk->active_mm = mm;
+	}
+	tsk->mm = mm;
+	switch_mm(active_mm, mm, tsk);
+	task_unlock(tsk);
+#ifdef finish_arch_post_lock_switch
+	finish_arch_post_lock_switch();
+#endif
+
+	if (active_mm != mm)
+		mmdrop(active_mm);
+}
+EXPORT_SYMBOL_GPL(use_mm);
+
+/*
+ * unuse_mm
+ *	Reverses the effect of use_mm, i.e. releases the
+ *	specified mm context which was earlier taken on
+ *	by the calling kernel thread
+ *	(Note: this routine is intended to be called only
+ *	from a kernel thread context)
+ */
+void unuse_mm(struct mm_struct *mm)
+{
+	struct task_struct *tsk = current;
+
+	task_lock(tsk);
+	sync_mm_rss(mm);
+	tsk->mm = NULL;
+	/* active_mm is still 'mm' */
+	enter_lazy_tlb(mm, tsk);
+	task_unlock(tsk);
+}
+EXPORT_SYMBOL_GPL(unuse_mm);
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
new file mode 100644
index 0000000..5fbdd36
--- /dev/null
+++ b/mm/mmu_notifier.c
@@ -0,0 +1,413 @@
+/*
+ *  linux/mm/mmu_notifier.c
+ *
+ *  Copyright (C) 2008  Qumranet, Inc.
+ *  Copyright (C) 2008  SGI
+ *             Christoph Lameter <clameter@sgi.com>
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2. See
+ *  the COPYING file in the top-level directory.
+ */
+
+#include <linux/rculist.h>
+#include <linux/mmu_notifier.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/srcu.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+/* global SRCU for all MMs */
+static struct srcu_struct srcu;
+
+/*
+ * This function allows mmu_notifier::release callback to delay a call to
+ * a function that will free appropriate resources. The function must be
+ * quick and must not block.
+ */
+void mmu_notifier_call_srcu(struct rcu_head *rcu,
+			    void (*func)(struct rcu_head *rcu))
+{
+	call_srcu(&srcu, rcu, func);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_call_srcu);
+
+void mmu_notifier_synchronize(void)
+{
+	/* Wait for any running method to finish. */
+	srcu_barrier(&srcu);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_synchronize);
+
+/*
+ * This function can't run concurrently against mmu_notifier_register
+ * because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
+ * runs with mm_users == 0. Other tasks may still invoke mmu notifiers
+ * in parallel despite there being no task using this mm any more,
+ * through the vmas outside of the exit_mmap context, such as with
+ * vmtruncate. This serializes against mmu_notifier_unregister with
+ * the mmu_notifier_mm->lock in addition to SRCU and it serializes
+ * against the other mmu notifiers with SRCU. struct mmu_notifier_mm
+ * can't go away from under us as exit_mmap holds an mm_count pin
+ * itself.
+ */
+void __mmu_notifier_release(struct mm_struct *mm)
+{
+	struct mmu_notifier *mn;
+	int id;
+
+	/*
+	 * SRCU here will block mmu_notifier_unregister until
+	 * ->release returns.
+	 */
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist)
+		/*
+		 * If ->release runs before mmu_notifier_unregister it must be
+		 * handled, as it's the only way for the driver to flush all
+		 * existing sptes and stop the driver from establishing any more
+		 * sptes before all the pages in the mm are freed.
+		 */
+		if (mn->ops->release)
+			mn->ops->release(mn, mm);
+
+	spin_lock(&mm->mmu_notifier_mm->lock);
+	while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) {
+		mn = hlist_entry(mm->mmu_notifier_mm->list.first,
+				 struct mmu_notifier,
+				 hlist);
+		/*
+		 * We arrived before mmu_notifier_unregister so
+		 * mmu_notifier_unregister will do nothing other than to wait
+		 * for ->release to finish and for mmu_notifier_unregister to
+		 * return.
+		 */
+		hlist_del_init_rcu(&mn->hlist);
+	}
+	spin_unlock(&mm->mmu_notifier_mm->lock);
+	srcu_read_unlock(&srcu, id);
+
+	/*
+	 * synchronize_srcu here prevents mmu_notifier_release from returning to
+	 * exit_mmap (which would proceed with freeing all pages in the mm)
+	 * until the ->release method returns, if it was invoked by
+	 * mmu_notifier_unregister.
+	 *
+	 * The mmu_notifier_mm can't go away from under us because one mm_count
+	 * is held by exit_mmap.
+	 */
+	synchronize_srcu(&srcu);
+}
+
+/*
+ * If no young bitflag is supported by the hardware, ->clear_flush_young can
+ * unmap the address and return 1 or 0 depending if the mapping previously
+ * existed or not.
+ */
+int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
+					unsigned long start,
+					unsigned long end)
+{
+	struct mmu_notifier *mn;
+	int young = 0, id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->clear_flush_young)
+			young |= mn->ops->clear_flush_young(mn, mm, start, end);
+	}
+	srcu_read_unlock(&srcu, id);
+
+	return young;
+}
+
+int __mmu_notifier_clear_young(struct mm_struct *mm,
+			       unsigned long start,
+			       unsigned long end)
+{
+	struct mmu_notifier *mn;
+	int young = 0, id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->clear_young)
+			young |= mn->ops->clear_young(mn, mm, start, end);
+	}
+	srcu_read_unlock(&srcu, id);
+
+	return young;
+}
+
+int __mmu_notifier_test_young(struct mm_struct *mm,
+			      unsigned long address)
+{
+	struct mmu_notifier *mn;
+	int young = 0, id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->test_young) {
+			young = mn->ops->test_young(mn, mm, address);
+			if (young)
+				break;
+		}
+	}
+	srcu_read_unlock(&srcu, id);
+
+	return young;
+}
+
+void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address,
+			       pte_t pte)
+{
+	struct mmu_notifier *mn;
+	int id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->change_pte)
+			mn->ops->change_pte(mn, mm, address, pte);
+	}
+	srcu_read_unlock(&srcu, id);
+}
+
+void __mmu_notifier_invalidate_page(struct mm_struct *mm,
+					  unsigned long address)
+{
+	struct mmu_notifier *mn;
+	int id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->invalidate_page)
+			mn->ops->invalidate_page(mn, mm, address);
+	}
+	srcu_read_unlock(&srcu, id);
+}
+
+void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+				  unsigned long start, unsigned long end)
+{
+	struct mmu_notifier *mn;
+	int id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->invalidate_range_start)
+			mn->ops->invalidate_range_start(mn, mm, start, end);
+	}
+	srcu_read_unlock(&srcu, id);
+}
+EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range_start);
+
+void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
+				  unsigned long start, unsigned long end)
+{
+	struct mmu_notifier *mn;
+	int id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		/*
+		 * Call invalidate_range here too to avoid the need for the
+		 * subsystem of having to register an invalidate_range_end
+		 * call-back when there is invalidate_range already. Usually a
+		 * subsystem registers either invalidate_range_start()/end() or
+		 * invalidate_range(), so this will be no additional overhead
+		 * (besides the pointer check).
+		 */
+		if (mn->ops->invalidate_range)
+			mn->ops->invalidate_range(mn, mm, start, end);
+		if (mn->ops->invalidate_range_end)
+			mn->ops->invalidate_range_end(mn, mm, start, end);
+	}
+	srcu_read_unlock(&srcu, id);
+}
+EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range_end);
+
+void __mmu_notifier_invalidate_range(struct mm_struct *mm,
+				  unsigned long start, unsigned long end)
+{
+	struct mmu_notifier *mn;
+	int id;
+
+	id = srcu_read_lock(&srcu);
+	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+		if (mn->ops->invalidate_range)
+			mn->ops->invalidate_range(mn, mm, start, end);
+	}
+	srcu_read_unlock(&srcu, id);
+}
+EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range);
+
+static int do_mmu_notifier_register(struct mmu_notifier *mn,
+				    struct mm_struct *mm,
+				    int take_mmap_sem)
+{
+	struct mmu_notifier_mm *mmu_notifier_mm;
+	int ret;
+
+	BUG_ON(atomic_read(&mm->mm_users) <= 0);
+
+	/*
+	 * Verify that mmu_notifier_init() already run and the global srcu is
+	 * initialized.
+	 */
+	BUG_ON(!srcu.per_cpu_ref);
+
+	ret = -ENOMEM;
+	mmu_notifier_mm = kmalloc(sizeof(struct mmu_notifier_mm), GFP_KERNEL);
+	if (unlikely(!mmu_notifier_mm))
+		goto out;
+
+	if (take_mmap_sem)
+		down_write(&mm->mmap_sem);
+	ret = mm_take_all_locks(mm);
+	if (unlikely(ret))
+		goto out_clean;
+
+	if (!mm_has_notifiers(mm)) {
+		INIT_HLIST_HEAD(&mmu_notifier_mm->list);
+		spin_lock_init(&mmu_notifier_mm->lock);
+
+		mm->mmu_notifier_mm = mmu_notifier_mm;
+		mmu_notifier_mm = NULL;
+	}
+	atomic_inc(&mm->mm_count);
+
+	/*
+	 * Serialize the update against mmu_notifier_unregister. A
+	 * side note: mmu_notifier_release can't run concurrently with
+	 * us because we hold the mm_users pin (either implicitly as
+	 * current->mm or explicitly with get_task_mm() or similar).
+	 * We can't race against any other mmu notifier method either
+	 * thanks to mm_take_all_locks().
+	 */
+	spin_lock(&mm->mmu_notifier_mm->lock);
+	hlist_add_head(&mn->hlist, &mm->mmu_notifier_mm->list);
+	spin_unlock(&mm->mmu_notifier_mm->lock);
+
+	mm_drop_all_locks(mm);
+out_clean:
+	if (take_mmap_sem)
+		up_write(&mm->mmap_sem);
+	kfree(mmu_notifier_mm);
+out:
+	BUG_ON(atomic_read(&mm->mm_users) <= 0);
+	return ret;
+}
+
+/*
+ * Must not hold mmap_sem nor any other VM related lock when calling
+ * this registration function. Must also ensure mm_users can't go down
+ * to zero while this runs to avoid races with mmu_notifier_release,
+ * so mm has to be current->mm or the mm should be pinned safely such
+ * as with get_task_mm(). If the mm is not current->mm, the mm_users
+ * pin should be released by calling mmput after mmu_notifier_register
+ * returns. mmu_notifier_unregister must be always called to
+ * unregister the notifier. mm_count is automatically pinned to allow
+ * mmu_notifier_unregister to safely run at any time later, before or
+ * after exit_mmap. ->release will always be called before exit_mmap
+ * frees the pages.
+ */
+int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+	return do_mmu_notifier_register(mn, mm, 1);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_register);
+
+/*
+ * Same as mmu_notifier_register but here the caller must hold the
+ * mmap_sem in write mode.
+ */
+int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+	return do_mmu_notifier_register(mn, mm, 0);
+}
+EXPORT_SYMBOL_GPL(__mmu_notifier_register);
+
+/* this is called after the last mmu_notifier_unregister() returned */
+void __mmu_notifier_mm_destroy(struct mm_struct *mm)
+{
+	BUG_ON(!hlist_empty(&mm->mmu_notifier_mm->list));
+	kfree(mm->mmu_notifier_mm);
+	mm->mmu_notifier_mm = LIST_POISON1; /* debug */
+}
+
+/*
+ * This releases the mm_count pin automatically and frees the mm
+ * structure if it was the last user of it. It serializes against
+ * running mmu notifiers with SRCU and against mmu_notifier_unregister
+ * with the unregister lock + SRCU. All sptes must be dropped before
+ * calling mmu_notifier_unregister. ->release or any other notifier
+ * method may be invoked concurrently with mmu_notifier_unregister,
+ * and only after mmu_notifier_unregister returned we're guaranteed
+ * that ->release or any other method can't run anymore.
+ */
+void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+	BUG_ON(atomic_read(&mm->mm_count) <= 0);
+
+	if (!hlist_unhashed(&mn->hlist)) {
+		/*
+		 * SRCU here will force exit_mmap to wait for ->release to
+		 * finish before freeing the pages.
+		 */
+		int id;
+
+		id = srcu_read_lock(&srcu);
+		/*
+		 * exit_mmap will block in mmu_notifier_release to guarantee
+		 * that ->release is called before freeing the pages.
+		 */
+		if (mn->ops->release)
+			mn->ops->release(mn, mm);
+		srcu_read_unlock(&srcu, id);
+
+		spin_lock(&mm->mmu_notifier_mm->lock);
+		/*
+		 * Can not use list_del_rcu() since __mmu_notifier_release
+		 * can delete it before we hold the lock.
+		 */
+		hlist_del_init_rcu(&mn->hlist);
+		spin_unlock(&mm->mmu_notifier_mm->lock);
+	}
+
+	/*
+	 * Wait for any running method to finish, of course including
+	 * ->release if it was run by mmu_notifier_release instead of us.
+	 */
+	synchronize_srcu(&srcu);
+
+	BUG_ON(atomic_read(&mm->mm_count) <= 0);
+
+	mmdrop(mm);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
+
+/*
+ * Same as mmu_notifier_unregister but no callback and no srcu synchronization.
+ */
+void mmu_notifier_unregister_no_release(struct mmu_notifier *mn,
+					struct mm_struct *mm)
+{
+	spin_lock(&mm->mmu_notifier_mm->lock);
+	/*
+	 * Can not use list_del_rcu() since __mmu_notifier_release
+	 * can delete it before we hold the lock.
+	 */
+	hlist_del_init_rcu(&mn->hlist);
+	spin_unlock(&mm->mmu_notifier_mm->lock);
+
+	BUG_ON(atomic_read(&mm->mm_count) <= 0);
+	mmdrop(mm);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release);
+
+static int __init mmu_notifier_init(void)
+{
+	return init_srcu_struct(&srcu);
+}
+subsys_initcall(mmu_notifier_init);
diff --git a/mm/mmzone.c b/mm/mmzone.c
new file mode 100644
index 0000000..7d87ebb
--- /dev/null
+++ b/mm/mmzone.c
@@ -0,0 +1,114 @@
+/*
+ * linux/mm/mmzone.c
+ *
+ * management codes for pgdats, zones and page flags
+ */
+
+
+#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+
+struct pglist_data *first_online_pgdat(void)
+{
+	return NODE_DATA(first_online_node);
+}
+
+struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
+{
+	int nid = next_online_node(pgdat->node_id);
+
+	if (nid == MAX_NUMNODES)
+		return NULL;
+	return NODE_DATA(nid);
+}
+
+/*
+ * next_zone - helper magic for for_each_zone()
+ */
+struct zone *next_zone(struct zone *zone)
+{
+	pg_data_t *pgdat = zone->zone_pgdat;
+
+	if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
+		zone++;
+	else {
+		pgdat = next_online_pgdat(pgdat);
+		if (pgdat)
+			zone = pgdat->node_zones;
+		else
+			zone = NULL;
+	}
+	return zone;
+}
+
+static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
+{
+#ifdef CONFIG_NUMA
+	return node_isset(zonelist_node_idx(zref), *nodes);
+#else
+	return 1;
+#endif /* CONFIG_NUMA */
+}
+
+/* Returns the next zone at or below highest_zoneidx in a zonelist */
+struct zoneref *next_zones_zonelist(struct zoneref *z,
+					enum zone_type highest_zoneidx,
+					nodemask_t *nodes)
+{
+	/*
+	 * Find the next suitable zone to use for the allocation.
+	 * Only filter based on nodemask if it's set
+	 */
+	if (likely(nodes == NULL))
+		while (zonelist_zone_idx(z) > highest_zoneidx)
+			z++;
+	else
+		while (zonelist_zone_idx(z) > highest_zoneidx ||
+				(z->zone && !zref_in_nodemask(z, nodes)))
+			z++;
+
+	return z;
+}
+
+#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
+int memmap_valid_within(unsigned long pfn,
+					struct page *page, struct zone *zone)
+{
+	if (page_to_pfn(page) != pfn)
+		return 0;
+
+	if (page_zone(page) != zone)
+		return 0;
+
+	return 1;
+}
+#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
+
+void lruvec_init(struct lruvec *lruvec)
+{
+	enum lru_list lru;
+
+	memset(lruvec, 0, sizeof(struct lruvec));
+
+	for_each_lru(lru)
+		INIT_LIST_HEAD(&lruvec->lists[lru]);
+}
+
+#if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)
+int page_cpupid_xchg_last(struct page *page, int cpupid)
+{
+	unsigned long old_flags, flags;
+	int last_cpupid;
+
+	do {
+		old_flags = flags = page->flags;
+		last_cpupid = page_cpupid_last(page);
+
+		flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
+		flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
+	} while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags));
+
+	return last_cpupid;
+}
+#endif
diff --git a/mm/mprotect.c b/mm/mprotect.c
new file mode 100644
index 0000000..c0b4b2a
--- /dev/null
+++ b/mm/mprotect.c
@@ -0,0 +1,446 @@
+/*
+ *  mm/mprotect.c
+ *
+ *  (C) Copyright 1994 Linus Torvalds
+ *  (C) Copyright 2002 Christoph Hellwig
+ *
+ *  Address space accounting code	<alan@lxorguk.ukuu.org.uk>
+ *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/security.h>
+#include <linux/mempolicy.h>
+#include <linux/personality.h>
+#include <linux/syscalls.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
+#include <linux/migrate.h>
+#include <linux/perf_event.h>
+#include <linux/ksm.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+
+/*
+ * For a prot_numa update we only hold mmap_sem for read so there is a
+ * potential race with faulting where a pmd was temporarily none. This
+ * function checks for a transhuge pmd under the appropriate lock. It
+ * returns a pte if it was successfully locked or NULL if it raced with
+ * a transhuge insertion.
+ */
+static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
+			unsigned long addr, int prot_numa, spinlock_t **ptl)
+{
+	pte_t *pte;
+	spinlock_t *pmdl;
+
+	/* !prot_numa is protected by mmap_sem held for write */
+	if (!prot_numa)
+		return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
+
+	pmdl = pmd_lock(vma->vm_mm, pmd);
+	if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
+		spin_unlock(pmdl);
+		return NULL;
+	}
+
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
+	spin_unlock(pmdl);
+	return pte;
+}
+
+static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+		unsigned long addr, unsigned long end, pgprot_t newprot,
+		int dirty_accountable, int prot_numa)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pte_t *pte, oldpte;
+	spinlock_t *ptl;
+	unsigned long pages = 0;
+
+	pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
+	if (!pte)
+		return 0;
+
+	flush_tlb_batched_pending(vma->vm_mm);
+	arch_enter_lazy_mmu_mode();
+	do {
+		oldpte = *pte;
+		if (pte_present(oldpte)) {
+			pte_t ptent;
+			bool preserve_write = prot_numa && pte_write(oldpte);
+
+			/*
+			 * Avoid trapping faults against the zero or KSM
+			 * pages. See similar comment in change_huge_pmd.
+			 */
+			if (prot_numa) {
+				struct page *page;
+
+				page = vm_normal_page(vma, addr, oldpte);
+				if (!page || PageKsm(page))
+					continue;
+
+				/* Avoid TLB flush if possible */
+				if (pte_protnone(oldpte))
+					continue;
+			}
+
+			ptent = ptep_modify_prot_start(mm, addr, pte);
+			ptent = pte_modify(ptent, newprot);
+			if (preserve_write)
+				ptent = pte_mkwrite(ptent);
+
+			/* Avoid taking write faults for known dirty pages */
+			if (dirty_accountable && pte_dirty(ptent) &&
+					(pte_soft_dirty(ptent) ||
+					 !(vma->vm_flags & VM_SOFTDIRTY))) {
+				ptent = pte_mkwrite(ptent);
+			}
+			ptep_modify_prot_commit(mm, addr, pte, ptent);
+			pages++;
+		} else if (IS_ENABLED(CONFIG_MIGRATION)) {
+			swp_entry_t entry = pte_to_swp_entry(oldpte);
+
+			if (is_write_migration_entry(entry)) {
+				pte_t newpte;
+				/*
+				 * A protection check is difficult so
+				 * just be safe and disable write
+				 */
+				make_migration_entry_read(&entry);
+				newpte = swp_entry_to_pte(entry);
+				if (pte_swp_soft_dirty(oldpte))
+					newpte = pte_swp_mksoft_dirty(newpte);
+				set_pte_at(mm, addr, pte, newpte);
+
+				pages++;
+			}
+		}
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	arch_leave_lazy_mmu_mode();
+	pte_unmap_unlock(pte - 1, ptl);
+
+	return pages;
+}
+
+static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
+		pud_t *pud, unsigned long addr, unsigned long end,
+		pgprot_t newprot, int dirty_accountable, int prot_numa)
+{
+	pmd_t *pmd;
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long next;
+	unsigned long pages = 0;
+	unsigned long nr_huge_updates = 0;
+	unsigned long mni_start = 0;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		unsigned long this_pages;
+
+		next = pmd_addr_end(addr, end);
+		if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
+			continue;
+
+		/* invoke the mmu notifier if the pmd is populated */
+		if (!mni_start) {
+			mni_start = addr;
+			mmu_notifier_invalidate_range_start(mm, mni_start, end);
+		}
+
+		if (pmd_trans_huge(*pmd)) {
+			if (next - addr != HPAGE_PMD_SIZE)
+				split_huge_page_pmd(vma, addr, pmd);
+			else {
+				int nr_ptes = change_huge_pmd(vma, pmd, addr,
+						newprot, prot_numa);
+
+				if (nr_ptes) {
+					if (nr_ptes == HPAGE_PMD_NR) {
+						pages += HPAGE_PMD_NR;
+						nr_huge_updates++;
+					}
+
+					/* huge pmd was handled */
+					continue;
+				}
+			}
+			/* fall through, the trans huge pmd just split */
+		}
+		this_pages = change_pte_range(vma, pmd, addr, next, newprot,
+				 dirty_accountable, prot_numa);
+		pages += this_pages;
+	} while (pmd++, addr = next, addr != end);
+
+	if (mni_start)
+		mmu_notifier_invalidate_range_end(mm, mni_start, end);
+
+	if (nr_huge_updates)
+		count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
+	return pages;
+}
+
+static inline unsigned long change_pud_range(struct vm_area_struct *vma,
+		pgd_t *pgd, unsigned long addr, unsigned long end,
+		pgprot_t newprot, int dirty_accountable, int prot_numa)
+{
+	pud_t *pud;
+	unsigned long next;
+	unsigned long pages = 0;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		pages += change_pmd_range(vma, pud, addr, next, newprot,
+				 dirty_accountable, prot_numa);
+	} while (pud++, addr = next, addr != end);
+
+	return pages;
+}
+
+static unsigned long change_protection_range(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long end, pgprot_t newprot,
+		int dirty_accountable, int prot_numa)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long start = addr;
+	unsigned long pages = 0;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset(mm, addr);
+	flush_cache_range(vma, addr, end);
+	set_tlb_flush_pending(mm);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		pages += change_pud_range(vma, pgd, addr, next, newprot,
+				 dirty_accountable, prot_numa);
+	} while (pgd++, addr = next, addr != end);
+
+	/* Only flush the TLB if we actually modified any entries: */
+	if (pages)
+		flush_tlb_range(vma, start, end);
+	clear_tlb_flush_pending(mm);
+
+	return pages;
+}
+
+unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
+		       unsigned long end, pgprot_t newprot,
+		       int dirty_accountable, int prot_numa)
+{
+	unsigned long pages;
+
+	if (is_vm_hugetlb_page(vma))
+		pages = hugetlb_change_protection(vma, start, end, newprot);
+	else
+		pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
+
+	return pages;
+}
+
+int
+mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
+	unsigned long start, unsigned long end, unsigned long newflags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long oldflags = vma->vm_flags;
+	long nrpages = (end - start) >> PAGE_SHIFT;
+	unsigned long charged = 0;
+	pgoff_t pgoff;
+	int error;
+	int dirty_accountable = 0;
+
+	if (newflags == oldflags) {
+		*pprev = vma;
+		return 0;
+	}
+
+	/*
+	 * If we make a private mapping writable we increase our commit;
+	 * but (without finer accounting) cannot reduce our commit if we
+	 * make it unwritable again. hugetlb mapping were accounted for
+	 * even if read-only so there is no need to account for them here
+	 */
+	if (newflags & VM_WRITE) {
+		if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
+						VM_SHARED|VM_NORESERVE))) {
+			charged = nrpages;
+			if (security_vm_enough_memory_mm(mm, charged))
+				return -ENOMEM;
+			newflags |= VM_ACCOUNT;
+		}
+	}
+
+	/*
+	 * First try to merge with previous and/or next vma.
+	 */
+	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+	*pprev = vma_merge(mm, *pprev, start, end, newflags,
+			   vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+			   vma->vm_userfaultfd_ctx);
+	if (*pprev) {
+		vma = *pprev;
+		goto success;
+	}
+
+	*pprev = vma;
+
+	if (start != vma->vm_start) {
+		error = split_vma(mm, vma, start, 1);
+		if (error)
+			goto fail;
+	}
+
+	if (end != vma->vm_end) {
+		error = split_vma(mm, vma, end, 0);
+		if (error)
+			goto fail;
+	}
+
+success:
+	/*
+	 * vm_flags and vm_page_prot are protected by the mmap_sem
+	 * held in write mode.
+	 */
+	vma->vm_flags = newflags;
+	dirty_accountable = vma_wants_writenotify(vma);
+	vma_set_page_prot(vma);
+
+	change_protection(vma, start, end, vma->vm_page_prot,
+			  dirty_accountable, 0);
+
+	/*
+	 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
+	 * fault on access.
+	 */
+	if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
+			(newflags & VM_WRITE)) {
+		populate_vma_page_range(vma, start, end, NULL);
+	}
+
+	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
+	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
+	perf_event_mmap(vma);
+	return 0;
+
+fail:
+	vm_unacct_memory(charged);
+	return error;
+}
+
+SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
+		unsigned long, prot)
+{
+	unsigned long vm_flags, nstart, end, tmp, reqprot;
+	struct vm_area_struct *vma, *prev;
+	int error = -EINVAL;
+	const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
+	prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
+	if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
+		return -EINVAL;
+
+	if (start & ~PAGE_MASK)
+		return -EINVAL;
+	if (!len)
+		return 0;
+	len = PAGE_ALIGN(len);
+	end = start + len;
+	if (end <= start)
+		return -ENOMEM;
+	if (!arch_validate_prot(prot))
+		return -EINVAL;
+
+	reqprot = prot;
+	/*
+	 * Does the application expect PROT_READ to imply PROT_EXEC:
+	 */
+	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+		prot |= PROT_EXEC;
+
+	vm_flags = calc_vm_prot_bits(prot);
+
+	down_write(&current->mm->mmap_sem);
+
+	vma = find_vma(current->mm, start);
+	error = -ENOMEM;
+	if (!vma)
+		goto out;
+	prev = vma->vm_prev;
+	if (unlikely(grows & PROT_GROWSDOWN)) {
+		if (vma->vm_start >= end)
+			goto out;
+		start = vma->vm_start;
+		error = -EINVAL;
+		if (!(vma->vm_flags & VM_GROWSDOWN))
+			goto out;
+	} else {
+		if (vma->vm_start > start)
+			goto out;
+		if (unlikely(grows & PROT_GROWSUP)) {
+			end = vma->vm_end;
+			error = -EINVAL;
+			if (!(vma->vm_flags & VM_GROWSUP))
+				goto out;
+		}
+	}
+	if (start > vma->vm_start)
+		prev = vma;
+
+	for (nstart = start ; ; ) {
+		unsigned long newflags;
+
+		/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
+
+		newflags = vm_flags;
+		newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
+
+		/* newflags >> 4 shift VM_MAY% in place of VM_% */
+		if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
+			error = -EACCES;
+			goto out;
+		}
+
+		error = security_file_mprotect(vma, reqprot, prot);
+		if (error)
+			goto out;
+
+		tmp = vma->vm_end;
+		if (tmp > end)
+			tmp = end;
+		error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
+		if (error)
+			goto out;
+		nstart = tmp;
+
+		if (nstart < prev->vm_end)
+			nstart = prev->vm_end;
+		if (nstart >= end)
+			goto out;
+
+		vma = prev->vm_next;
+		if (!vma || vma->vm_start != nstart) {
+			error = -ENOMEM;
+			goto out;
+		}
+	}
+out:
+	up_write(&current->mm->mmap_sem);
+	return error;
+}
diff --git a/mm/mremap.c b/mm/mremap.c
new file mode 100644
index 0000000..fe7b7f6
--- /dev/null
+++ b/mm/mremap.c
@@ -0,0 +1,586 @@
+/*
+ *	mm/mremap.c
+ *
+ *	(C) Copyright 1996 Linus Torvalds
+ *
+ *	Address space accounting code	<alan@lxorguk.ukuu.org.uk>
+ *	(C) Copyright 2002 Red Hat Inc, All Rights Reserved
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/shm.h>
+#include <linux/ksm.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/capability.h>
+#include <linux/fs.h>
+#include <linux/swapops.h>
+#include <linux/highmem.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/mmu_notifier.h>
+#include <linux/sched/sysctl.h>
+#include <linux/uaccess.h>
+#include <linux/mm-arch-hooks.h>
+
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+
+static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	pgd = pgd_offset(mm, addr);
+	if (pgd_none_or_clear_bad(pgd))
+		return NULL;
+
+	pud = pud_offset(pgd, addr);
+	if (pud_none_or_clear_bad(pud))
+		return NULL;
+
+	pmd = pmd_offset(pud, addr);
+	if (pmd_none(*pmd))
+		return NULL;
+
+	return pmd;
+}
+
+static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+			    unsigned long addr)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	pgd = pgd_offset(mm, addr);
+	pud = pud_alloc(mm, pgd, addr);
+	if (!pud)
+		return NULL;
+
+	pmd = pmd_alloc(mm, pud, addr);
+	if (!pmd)
+		return NULL;
+
+	VM_BUG_ON(pmd_trans_huge(*pmd));
+
+	return pmd;
+}
+
+static pte_t move_soft_dirty_pte(pte_t pte)
+{
+	/*
+	 * Set soft dirty bit so we can notice
+	 * in userspace the ptes were moved.
+	 */
+#ifdef CONFIG_MEM_SOFT_DIRTY
+	if (pte_present(pte))
+		pte = pte_mksoft_dirty(pte);
+	else if (is_swap_pte(pte))
+		pte = pte_swp_mksoft_dirty(pte);
+#endif
+	return pte;
+}
+
+static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
+		unsigned long old_addr, unsigned long old_end,
+		struct vm_area_struct *new_vma, pmd_t *new_pmd,
+		unsigned long new_addr, bool need_rmap_locks)
+{
+	struct address_space *mapping = NULL;
+	struct anon_vma *anon_vma = NULL;
+	struct mm_struct *mm = vma->vm_mm;
+	pte_t *old_pte, *new_pte, pte;
+	spinlock_t *old_ptl, *new_ptl;
+
+	/*
+	 * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
+	 * locks to ensure that rmap will always observe either the old or the
+	 * new ptes. This is the easiest way to avoid races with
+	 * truncate_pagecache(), page migration, etc...
+	 *
+	 * When need_rmap_locks is false, we use other ways to avoid
+	 * such races:
+	 *
+	 * - During exec() shift_arg_pages(), we use a specially tagged vma
+	 *   which rmap call sites look for using is_vma_temporary_stack().
+	 *
+	 * - During mremap(), new_vma is often known to be placed after vma
+	 *   in rmap traversal order. This ensures rmap will always observe
+	 *   either the old pte, or the new pte, or both (the page table locks
+	 *   serialize access to individual ptes, but only rmap traversal
+	 *   order guarantees that we won't miss both the old and new ptes).
+	 */
+	if (need_rmap_locks) {
+		if (vma->vm_file) {
+			mapping = vma->vm_file->f_mapping;
+			i_mmap_lock_write(mapping);
+		}
+		if (vma->anon_vma) {
+			anon_vma = vma->anon_vma;
+			anon_vma_lock_write(anon_vma);
+		}
+	}
+
+	/*
+	 * We don't have to worry about the ordering of src and dst
+	 * pte locks because exclusive mmap_sem prevents deadlock.
+	 */
+	old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
+	new_pte = pte_offset_map(new_pmd, new_addr);
+	new_ptl = pte_lockptr(mm, new_pmd);
+	if (new_ptl != old_ptl)
+		spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
+	flush_tlb_batched_pending(vma->vm_mm);
+	arch_enter_lazy_mmu_mode();
+
+	for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
+				   new_pte++, new_addr += PAGE_SIZE) {
+		if (pte_none(*old_pte))
+			continue;
+		pte = ptep_get_and_clear(mm, old_addr, old_pte);
+		pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
+		pte = move_soft_dirty_pte(pte);
+		set_pte_at(mm, new_addr, new_pte, pte);
+	}
+
+	arch_leave_lazy_mmu_mode();
+	if (new_ptl != old_ptl)
+		spin_unlock(new_ptl);
+	pte_unmap(new_pte - 1);
+	pte_unmap_unlock(old_pte - 1, old_ptl);
+	if (anon_vma)
+		anon_vma_unlock_write(anon_vma);
+	if (mapping)
+		i_mmap_unlock_write(mapping);
+}
+
+#define LATENCY_LIMIT	(64 * PAGE_SIZE)
+
+unsigned long move_page_tables(struct vm_area_struct *vma,
+		unsigned long old_addr, struct vm_area_struct *new_vma,
+		unsigned long new_addr, unsigned long len,
+		bool need_rmap_locks)
+{
+	unsigned long extent, next, old_end;
+	pmd_t *old_pmd, *new_pmd;
+	bool need_flush = false;
+	unsigned long mmun_start;	/* For mmu_notifiers */
+	unsigned long mmun_end;		/* For mmu_notifiers */
+
+	old_end = old_addr + len;
+	flush_cache_range(vma, old_addr, old_end);
+
+	mmun_start = old_addr;
+	mmun_end   = old_end;
+	mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
+
+	for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
+		cond_resched();
+		next = (old_addr + PMD_SIZE) & PMD_MASK;
+		/* even if next overflowed, extent below will be ok */
+		extent = next - old_addr;
+		if (extent > old_end - old_addr)
+			extent = old_end - old_addr;
+		old_pmd = get_old_pmd(vma->vm_mm, old_addr);
+		if (!old_pmd)
+			continue;
+		new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
+		if (!new_pmd)
+			break;
+		if (pmd_trans_huge(*old_pmd)) {
+			int err = 0;
+			if (extent == HPAGE_PMD_SIZE) {
+				VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma,
+					      vma);
+				/* See comment in move_ptes() */
+				if (need_rmap_locks)
+					anon_vma_lock_write(vma->anon_vma);
+				err = move_huge_pmd(vma, new_vma, old_addr,
+						    new_addr, old_end,
+						    old_pmd, new_pmd);
+				if (need_rmap_locks)
+					anon_vma_unlock_write(vma->anon_vma);
+			}
+			if (err > 0) {
+				need_flush = true;
+				continue;
+			} else if (!err) {
+				split_huge_page_pmd(vma, old_addr, old_pmd);
+			}
+			VM_BUG_ON(pmd_trans_huge(*old_pmd));
+		}
+		if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
+						      new_pmd, new_addr))
+			break;
+		next = (new_addr + PMD_SIZE) & PMD_MASK;
+		if (extent > next - new_addr)
+			extent = next - new_addr;
+		if (extent > LATENCY_LIMIT)
+			extent = LATENCY_LIMIT;
+		move_ptes(vma, old_pmd, old_addr, old_addr + extent,
+			  new_vma, new_pmd, new_addr, need_rmap_locks);
+		need_flush = true;
+	}
+	if (likely(need_flush))
+		flush_tlb_range(vma, old_end-len, old_addr);
+
+	mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
+
+	return len + old_addr - old_end;	/* how much done */
+}
+
+static unsigned long move_vma(struct vm_area_struct *vma,
+		unsigned long old_addr, unsigned long old_len,
+		unsigned long new_len, unsigned long new_addr, bool *locked)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *new_vma;
+	unsigned long vm_flags = vma->vm_flags;
+	unsigned long new_pgoff;
+	unsigned long moved_len;
+	unsigned long excess = 0;
+	unsigned long hiwater_vm;
+	int split = 0;
+	int err;
+	bool need_rmap_locks;
+
+	/*
+	 * We'd prefer to avoid failure later on in do_munmap:
+	 * which may split one vma into three before unmapping.
+	 */
+	if (mm->map_count >= sysctl_max_map_count - 3)
+		return -ENOMEM;
+
+	/*
+	 * Advise KSM to break any KSM pages in the area to be moved:
+	 * it would be confusing if they were to turn up at the new
+	 * location, where they happen to coincide with different KSM
+	 * pages recently unmapped.  But leave vma->vm_flags as it was,
+	 * so KSM can come around to merge on vma and new_vma afterwards.
+	 */
+	err = ksm_madvise(vma, old_addr, old_addr + old_len,
+						MADV_UNMERGEABLE, &vm_flags);
+	if (err)
+		return err;
+
+	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
+	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
+			   &need_rmap_locks);
+	if (!new_vma)
+		return -ENOMEM;
+
+	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
+				     need_rmap_locks);
+	if (moved_len < old_len) {
+		err = -ENOMEM;
+	} else if (vma->vm_ops && vma->vm_ops->mremap) {
+		err = vma->vm_ops->mremap(new_vma);
+	}
+
+	if (unlikely(err)) {
+		/*
+		 * On error, move entries back from new area to old,
+		 * which will succeed since page tables still there,
+		 * and then proceed to unmap new area instead of old.
+		 */
+		move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
+				 true);
+		vma = new_vma;
+		old_len = new_len;
+		old_addr = new_addr;
+		new_addr = err;
+	} else {
+		arch_remap(mm, old_addr, old_addr + old_len,
+			   new_addr, new_addr + new_len);
+	}
+
+	/* Conceal VM_ACCOUNT so old reservation is not undone */
+	if (vm_flags & VM_ACCOUNT) {
+		vma->vm_flags &= ~VM_ACCOUNT;
+		excess = vma->vm_end - vma->vm_start - old_len;
+		if (old_addr > vma->vm_start &&
+		    old_addr + old_len < vma->vm_end)
+			split = 1;
+	}
+
+	/*
+	 * If we failed to move page tables we still do total_vm increment
+	 * since do_munmap() will decrement it by old_len == new_len.
+	 *
+	 * Since total_vm is about to be raised artificially high for a
+	 * moment, we need to restore high watermark afterwards: if stats
+	 * are taken meanwhile, total_vm and hiwater_vm appear too high.
+	 * If this were a serious issue, we'd add a flag to do_munmap().
+	 */
+	hiwater_vm = mm->hiwater_vm;
+	vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
+
+	if (do_munmap(mm, old_addr, old_len) < 0) {
+		/* OOM: unable to split vma, just get accounts right */
+		vm_unacct_memory(excess >> PAGE_SHIFT);
+		excess = 0;
+	}
+	mm->hiwater_vm = hiwater_vm;
+
+	/* Restore VM_ACCOUNT if one or two pieces of vma left */
+	if (excess) {
+		vma->vm_flags |= VM_ACCOUNT;
+		if (split)
+			vma->vm_next->vm_flags |= VM_ACCOUNT;
+	}
+
+	if (vm_flags & VM_LOCKED) {
+		mm->locked_vm += new_len >> PAGE_SHIFT;
+		*locked = true;
+	}
+
+	return new_addr;
+}
+
+static struct vm_area_struct *vma_to_resize(unsigned long addr,
+	unsigned long old_len, unsigned long new_len, unsigned long *p)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma = find_vma(mm, addr);
+	unsigned long pgoff;
+
+	if (!vma || vma->vm_start > addr)
+		return ERR_PTR(-EFAULT);
+
+	if (is_vm_hugetlb_page(vma))
+		return ERR_PTR(-EINVAL);
+
+	/* We can't remap across vm area boundaries */
+	if (old_len > vma->vm_end - addr)
+		return ERR_PTR(-EFAULT);
+
+	if (new_len == old_len)
+		return vma;
+
+	/* Need to be careful about a growing mapping */
+	pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
+	pgoff += vma->vm_pgoff;
+	if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
+		return ERR_PTR(-EINVAL);
+
+	if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
+		return ERR_PTR(-EFAULT);
+
+	if (vma->vm_flags & VM_LOCKED) {
+		unsigned long locked, lock_limit;
+		locked = mm->locked_vm << PAGE_SHIFT;
+		lock_limit = rlimit(RLIMIT_MEMLOCK);
+		locked += new_len - old_len;
+		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+			return ERR_PTR(-EAGAIN);
+	}
+
+	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
+		return ERR_PTR(-ENOMEM);
+
+	if (vma->vm_flags & VM_ACCOUNT) {
+		unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
+		if (security_vm_enough_memory_mm(mm, charged))
+			return ERR_PTR(-ENOMEM);
+		*p = charged;
+	}
+
+	return vma;
+}
+
+static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
+		unsigned long new_addr, unsigned long new_len, bool *locked)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long ret = -EINVAL;
+	unsigned long charged = 0;
+	unsigned long map_flags;
+
+	if (offset_in_page(new_addr))
+		goto out;
+
+	if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
+		goto out;
+
+	/* Ensure the old/new locations do not overlap */
+	if (addr + old_len > new_addr && new_addr + new_len > addr)
+		goto out;
+
+	ret = do_munmap(mm, new_addr, new_len);
+	if (ret)
+		goto out;
+
+	if (old_len >= new_len) {
+		ret = do_munmap(mm, addr+new_len, old_len - new_len);
+		if (ret && old_len != new_len)
+			goto out;
+		old_len = new_len;
+	}
+
+	vma = vma_to_resize(addr, old_len, new_len, &charged);
+	if (IS_ERR(vma)) {
+		ret = PTR_ERR(vma);
+		goto out;
+	}
+
+	map_flags = MAP_FIXED;
+	if (vma->vm_flags & VM_MAYSHARE)
+		map_flags |= MAP_SHARED;
+
+	ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
+				((addr - vma->vm_start) >> PAGE_SHIFT),
+				map_flags);
+	if (offset_in_page(ret))
+		goto out1;
+
+	ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
+	if (!(offset_in_page(ret)))
+		goto out;
+out1:
+	vm_unacct_memory(charged);
+
+out:
+	return ret;
+}
+
+static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
+{
+	unsigned long end = vma->vm_end + delta;
+	if (end < vma->vm_end) /* overflow */
+		return 0;
+	if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
+		return 0;
+	if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
+			      0, MAP_FIXED) & ~PAGE_MASK)
+		return 0;
+	return 1;
+}
+
+/*
+ * Expand (or shrink) an existing mapping, potentially moving it at the
+ * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
+ *
+ * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
+ * This option implies MREMAP_MAYMOVE.
+ */
+SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
+		unsigned long, new_len, unsigned long, flags,
+		unsigned long, new_addr)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long ret = -EINVAL;
+	unsigned long charged = 0;
+	bool locked = false;
+
+	if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
+		return ret;
+
+	if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
+		return ret;
+
+	if (offset_in_page(addr))
+		return ret;
+
+	old_len = PAGE_ALIGN(old_len);
+	new_len = PAGE_ALIGN(new_len);
+
+	/*
+	 * We allow a zero old-len as a special case
+	 * for DOS-emu "duplicate shm area" thing. But
+	 * a zero new-len is nonsensical.
+	 */
+	if (!new_len)
+		return ret;
+
+	down_write(&current->mm->mmap_sem);
+
+	if (flags & MREMAP_FIXED) {
+		ret = mremap_to(addr, old_len, new_addr, new_len,
+				&locked);
+		goto out;
+	}
+
+	/*
+	 * Always allow a shrinking remap: that just unmaps
+	 * the unnecessary pages..
+	 * do_munmap does all the needed commit accounting
+	 */
+	if (old_len >= new_len) {
+		ret = do_munmap(mm, addr+new_len, old_len - new_len);
+		if (ret && old_len != new_len)
+			goto out;
+		ret = addr;
+		goto out;
+	}
+
+	/*
+	 * Ok, we need to grow..
+	 */
+	vma = vma_to_resize(addr, old_len, new_len, &charged);
+	if (IS_ERR(vma)) {
+		ret = PTR_ERR(vma);
+		goto out;
+	}
+
+	/* old_len exactly to the end of the area..
+	 */
+	if (old_len == vma->vm_end - addr) {
+		/* can we just expand the current mapping? */
+		if (vma_expandable(vma, new_len - old_len)) {
+			int pages = (new_len - old_len) >> PAGE_SHIFT;
+
+			if (vma_adjust(vma, vma->vm_start, addr + new_len,
+				       vma->vm_pgoff, NULL)) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
+			if (vma->vm_flags & VM_LOCKED) {
+				mm->locked_vm += pages;
+				locked = true;
+				new_addr = addr;
+			}
+			ret = addr;
+			goto out;
+		}
+	}
+
+	/*
+	 * We weren't able to just expand or shrink the area,
+	 * we need to create a new one and move it..
+	 */
+	ret = -ENOMEM;
+	if (flags & MREMAP_MAYMOVE) {
+		unsigned long map_flags = 0;
+		if (vma->vm_flags & VM_MAYSHARE)
+			map_flags |= MAP_SHARED;
+
+		new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
+					vma->vm_pgoff +
+					((addr - vma->vm_start) >> PAGE_SHIFT),
+					map_flags);
+		if (offset_in_page(new_addr)) {
+			ret = new_addr;
+			goto out;
+		}
+
+		ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
+	}
+out:
+	if (offset_in_page(ret)) {
+		vm_unacct_memory(charged);
+		locked = 0;
+	}
+	up_write(&current->mm->mmap_sem);
+	if (locked && new_len > old_len)
+		mm_populate(new_addr + old_len, new_len - old_len);
+	return ret;
+}
diff --git a/mm/msync.c b/mm/msync.c
new file mode 100644
index 0000000..24e612f
--- /dev/null
+++ b/mm/msync.c
@@ -0,0 +1,107 @@
+/*
+ *	linux/mm/msync.c
+ *
+ * Copyright (C) 1994-1999  Linus Torvalds
+ */
+
+/*
+ * The msync() system call.
+ */
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/file.h>
+#include <linux/syscalls.h>
+#include <linux/sched.h>
+
+/*
+ * MS_SYNC syncs the entire file - including mappings.
+ *
+ * MS_ASYNC does not start I/O (it used to, up to 2.5.67).
+ * Nor does it marks the relevant pages dirty (it used to up to 2.6.17).
+ * Now it doesn't do anything, since dirty pages are properly tracked.
+ *
+ * The application may now run fsync() to
+ * write out the dirty pages and wait on the writeout and check the result.
+ * Or the application may run fadvise(FADV_DONTNEED) against the fd to start
+ * async writeout immediately.
+ * So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
+ * applications.
+ */
+SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
+{
+	unsigned long end;
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	int unmapped_error = 0;
+	int error = -EINVAL;
+
+	if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
+		goto out;
+	if (offset_in_page(start))
+		goto out;
+	if ((flags & MS_ASYNC) && (flags & MS_SYNC))
+		goto out;
+	error = -ENOMEM;
+	len = (len + ~PAGE_MASK) & PAGE_MASK;
+	end = start + len;
+	if (end < start)
+		goto out;
+	error = 0;
+	if (end == start)
+		goto out;
+	/*
+	 * If the interval [start,end) covers some unmapped address ranges,
+	 * just ignore them, but return -ENOMEM at the end.
+	 */
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, start);
+	for (;;) {
+		struct file *file;
+		loff_t fstart, fend;
+
+		/* Still start < end. */
+		error = -ENOMEM;
+		if (!vma)
+			goto out_unlock;
+		/* Here start < vma->vm_end. */
+		if (start < vma->vm_start) {
+			start = vma->vm_start;
+			if (start >= end)
+				goto out_unlock;
+			unmapped_error = -ENOMEM;
+		}
+		/* Here vma->vm_start <= start < vma->vm_end. */
+		if ((flags & MS_INVALIDATE) &&
+				(vma->vm_flags & VM_LOCKED)) {
+			error = -EBUSY;
+			goto out_unlock;
+		}
+		file = vma->vm_file;
+		fstart = (start - vma->vm_start) +
+			 ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+		fend = fstart + (min(end, vma->vm_end) - start) - 1;
+		start = vma->vm_end;
+		if ((flags & MS_SYNC) && file &&
+				(vma->vm_flags & VM_SHARED)) {
+			get_file(file);
+			up_read(&mm->mmap_sem);
+			error = vfs_fsync_range(file, fstart, fend, 1);
+			fput(file);
+			if (error || start >= end)
+				goto out;
+			down_read(&mm->mmap_sem);
+			vma = find_vma(mm, start);
+		} else {
+			if (start >= end) {
+				error = 0;
+				goto out_unlock;
+			}
+			vma = vma->vm_next;
+		}
+	}
+out_unlock:
+	up_read(&mm->mmap_sem);
+out:
+	return error ? : unmapped_error;
+}
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
new file mode 100644
index 0000000..e57cf24
--- /dev/null
+++ b/mm/nobootmem.c
@@ -0,0 +1,451 @@
+/*
+ *  bootmem - A boot-time physical memory allocator and configurator
+ *
+ *  Copyright (C) 1999 Ingo Molnar
+ *                1999 Kanoj Sarcar, SGI
+ *                2008 Johannes Weiner
+ *
+ * Access to this subsystem has to be serialized externally (which is true
+ * for the boot process anyway).
+ */
+#include <linux/init.h>
+#include <linux/pfn.h>
+#include <linux/slab.h>
+#include <linux/bootmem.h>
+#include <linux/export.h>
+#include <linux/kmemleak.h>
+#include <linux/range.h>
+#include <linux/memblock.h>
+
+#include <asm/bug.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+
+#include "internal.h"
+
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+struct pglist_data __refdata contig_page_data;
+EXPORT_SYMBOL(contig_page_data);
+#endif
+
+unsigned long max_low_pfn;
+unsigned long min_low_pfn;
+unsigned long max_pfn;
+
+static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
+					u64 goal, u64 limit)
+{
+	void *ptr;
+	u64 addr;
+	ulong flags = choose_memblock_flags();
+
+	if (limit > memblock.current_limit)
+		limit = memblock.current_limit;
+
+again:
+	addr = memblock_find_in_range_node(size, align, goal, limit, nid,
+					   flags);
+	if (!addr && (flags & MEMBLOCK_MIRROR)) {
+		flags &= ~MEMBLOCK_MIRROR;
+		pr_warn("Could not allocate %pap bytes of mirrored memory\n",
+			&size);
+		goto again;
+	}
+	if (!addr)
+		return NULL;
+
+	if (memblock_reserve(addr, size))
+		return NULL;
+
+	ptr = phys_to_virt(addr);
+	memset(ptr, 0, size);
+	/*
+	 * The min_count is set to 0 so that bootmem allocated blocks
+	 * are never reported as leaks.
+	 */
+	kmemleak_alloc(ptr, size, 0, 0);
+	return ptr;
+}
+
+/*
+ * free_bootmem_late - free bootmem pages directly to page allocator
+ * @addr: starting address of the range
+ * @size: size of the range in bytes
+ *
+ * This is only useful when the bootmem allocator has already been torn
+ * down, but we are still initializing the system.  Pages are given directly
+ * to the page allocator, no bootmem metadata is updated because it is gone.
+ */
+void __init free_bootmem_late(unsigned long addr, unsigned long size)
+{
+	unsigned long cursor, end;
+
+	kmemleak_free_part(__va(addr), size);
+
+	cursor = PFN_UP(addr);
+	end = PFN_DOWN(addr + size);
+
+	for (; cursor < end; cursor++) {
+		__free_pages_bootmem(pfn_to_page(cursor), cursor, 0);
+		totalram_pages++;
+	}
+}
+
+static void __init __free_pages_memory(unsigned long start, unsigned long end)
+{
+	int order;
+
+	while (start < end) {
+		order = min(MAX_ORDER - 1UL, __ffs(start));
+
+		while (start + (1UL << order) > end)
+			order--;
+
+		__free_pages_bootmem(pfn_to_page(start), start, order);
+
+		start += (1UL << order);
+	}
+}
+
+static unsigned long __init __free_memory_core(phys_addr_t start,
+				 phys_addr_t end)
+{
+	unsigned long start_pfn = PFN_UP(start);
+	unsigned long end_pfn = min_t(unsigned long,
+				      PFN_DOWN(end), max_low_pfn);
+
+	if (start_pfn > end_pfn)
+		return 0;
+
+	__free_pages_memory(start_pfn, end_pfn);
+
+	return end_pfn - start_pfn;
+}
+
+static unsigned long __init free_low_memory_core_early(void)
+{
+	unsigned long count = 0;
+	phys_addr_t start, end;
+	u64 i;
+
+	memblock_clear_hotplug(0, -1);
+
+	for_each_reserved_mem_region(i, &start, &end)
+		reserve_bootmem_region(start, end);
+
+	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
+				NULL)
+		count += __free_memory_core(start, end);
+
+#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
+	{
+		phys_addr_t size;
+
+		/* Free memblock.reserved array if it was allocated */
+		size = get_allocated_memblock_reserved_regions_info(&start);
+		if (size)
+			count += __free_memory_core(start, start + size);
+
+		/* Free memblock.memory array if it was allocated */
+		size = get_allocated_memblock_memory_regions_info(&start);
+		if (size)
+			count += __free_memory_core(start, start + size);
+	}
+#endif
+
+	return count;
+}
+
+static int reset_managed_pages_done __initdata;
+
+void reset_node_managed_pages(pg_data_t *pgdat)
+{
+	struct zone *z;
+
+	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
+		z->managed_pages = 0;
+}
+
+void __init reset_all_zones_managed_pages(void)
+{
+	struct pglist_data *pgdat;
+
+	if (reset_managed_pages_done)
+		return;
+
+	for_each_online_pgdat(pgdat)
+		reset_node_managed_pages(pgdat);
+
+	reset_managed_pages_done = 1;
+}
+
+/**
+ * free_all_bootmem - release free pages to the buddy allocator
+ *
+ * Returns the number of pages actually released.
+ */
+unsigned long __init free_all_bootmem(void)
+{
+	unsigned long pages;
+
+	reset_all_zones_managed_pages();
+
+	/*
+	 * We need to use NUMA_NO_NODE instead of NODE_DATA(0)->node_id
+	 *  because in some case like Node0 doesn't have RAM installed
+	 *  low ram will be on Node1
+	 */
+	pages = free_low_memory_core_early();
+	totalram_pages += pages;
+
+	return pages;
+}
+
+/**
+ * free_bootmem_node - mark a page range as usable
+ * @pgdat: node the range resides on
+ * @physaddr: starting address of the range
+ * @size: size of the range in bytes
+ *
+ * Partial pages will be considered reserved and left as they are.
+ *
+ * The range must reside completely on the specified node.
+ */
+void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
+			      unsigned long size)
+{
+	memblock_free(physaddr, size);
+}
+
+/**
+ * free_bootmem - mark a page range as usable
+ * @addr: starting address of the range
+ * @size: size of the range in bytes
+ *
+ * Partial pages will be considered reserved and left as they are.
+ *
+ * The range must be contiguous but may span node boundaries.
+ */
+void __init free_bootmem(unsigned long addr, unsigned long size)
+{
+	memblock_free(addr, size);
+}
+
+static void * __init ___alloc_bootmem_nopanic(unsigned long size,
+					unsigned long align,
+					unsigned long goal,
+					unsigned long limit)
+{
+	void *ptr;
+
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc(size, GFP_NOWAIT);
+
+restart:
+
+	ptr = __alloc_memory_core_early(NUMA_NO_NODE, size, align, goal, limit);
+
+	if (ptr)
+		return ptr;
+
+	if (goal != 0) {
+		goal = 0;
+		goto restart;
+	}
+
+	return NULL;
+}
+
+/**
+ * __alloc_bootmem_nopanic - allocate boot memory without panicking
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may happen on any node in the system.
+ *
+ * Returns NULL on failure.
+ */
+void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
+					unsigned long goal)
+{
+	unsigned long limit = -1UL;
+
+	return ___alloc_bootmem_nopanic(size, align, goal, limit);
+}
+
+static void * __init ___alloc_bootmem(unsigned long size, unsigned long align,
+					unsigned long goal, unsigned long limit)
+{
+	void *mem = ___alloc_bootmem_nopanic(size, align, goal, limit);
+
+	if (mem)
+		return mem;
+	/*
+	 * Whoops, we cannot satisfy the allocation request.
+	 */
+	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
+	panic("Out of memory");
+	return NULL;
+}
+
+/**
+ * __alloc_bootmem - allocate boot memory
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may happen on any node in the system.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem(unsigned long size, unsigned long align,
+			      unsigned long goal)
+{
+	unsigned long limit = -1UL;
+
+	return ___alloc_bootmem(size, align, goal, limit);
+}
+
+void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
+						   unsigned long size,
+						   unsigned long align,
+						   unsigned long goal,
+						   unsigned long limit)
+{
+	void *ptr;
+
+again:
+	ptr = __alloc_memory_core_early(pgdat->node_id, size, align,
+					goal, limit);
+	if (ptr)
+		return ptr;
+
+	ptr = __alloc_memory_core_early(NUMA_NO_NODE, size, align,
+					goal, limit);
+	if (ptr)
+		return ptr;
+
+	if (goal) {
+		goal = 0;
+		goto again;
+	}
+
+	return NULL;
+}
+
+void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
+				   unsigned long align, unsigned long goal)
+{
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
+}
+
+static void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
+				    unsigned long align, unsigned long goal,
+				    unsigned long limit)
+{
+	void *ptr;
+
+	ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, limit);
+	if (ptr)
+		return ptr;
+
+	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
+	panic("Out of memory");
+	return NULL;
+}
+
+/**
+ * __alloc_bootmem_node - allocate boot memory from a specific node
+ * @pgdat: node to allocate from
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may fall back to any node in the system if the specified node
+ * can not hold the requested memory.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
+				   unsigned long align, unsigned long goal)
+{
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	return ___alloc_bootmem_node(pgdat, size, align, goal, 0);
+}
+
+void * __init __alloc_bootmem_node_high(pg_data_t *pgdat, unsigned long size,
+				   unsigned long align, unsigned long goal)
+{
+	return __alloc_bootmem_node(pgdat, size, align, goal);
+}
+
+#ifndef ARCH_LOW_ADDRESS_LIMIT
+#define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
+#endif
+
+/**
+ * __alloc_bootmem_low - allocate low boot memory
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may happen on any node in the system.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
+				  unsigned long goal)
+{
+	return ___alloc_bootmem(size, align, goal, ARCH_LOW_ADDRESS_LIMIT);
+}
+
+void * __init __alloc_bootmem_low_nopanic(unsigned long size,
+					  unsigned long align,
+					  unsigned long goal)
+{
+	return ___alloc_bootmem_nopanic(size, align, goal,
+					ARCH_LOW_ADDRESS_LIMIT);
+}
+
+/**
+ * __alloc_bootmem_low_node - allocate low boot memory from a specific node
+ * @pgdat: node to allocate from
+ * @size: size of the request in bytes
+ * @align: alignment of the region
+ * @goal: preferred starting address of the region
+ *
+ * The goal is dropped if it can not be satisfied and the allocation will
+ * fall back to memory below @goal.
+ *
+ * Allocation may fall back to any node in the system if the specified node
+ * can not hold the requested memory.
+ *
+ * The function panics if the request can not be satisfied.
+ */
+void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
+				       unsigned long align, unsigned long goal)
+{
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
+
+	return ___alloc_bootmem_node(pgdat, size, align, goal,
+				     ARCH_LOW_ADDRESS_LIMIT);
+}
diff --git a/mm/nommu.c b/mm/nommu.c
new file mode 100644
index 0000000..92be862
--- /dev/null
+++ b/mm/nommu.c
@@ -0,0 +1,2110 @@
+/*
+ *  linux/mm/nommu.c
+ *
+ *  Replacement code for mm functions to support CPU's that don't
+ *  have any form of memory management unit (thus no virtual memory).
+ *
+ *  See Documentation/nommu-mmap.txt
+ *
+ *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
+ *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
+ *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
+ *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
+ *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/vmacache.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/file.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/compiler.h>
+#include <linux/mount.h>
+#include <linux/personality.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <linux/sched/sysctl.h>
+#include <linux/printk.h>
+
+#include <asm/uaccess.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
+#include "internal.h"
+
+void *high_memory;
+EXPORT_SYMBOL(high_memory);
+struct page *mem_map;
+unsigned long max_mapnr;
+EXPORT_SYMBOL(max_mapnr);
+unsigned long highest_memmap_pfn;
+struct percpu_counter vm_committed_as;
+int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
+int sysctl_overcommit_ratio = 50; /* default is 50% */
+unsigned long sysctl_overcommit_kbytes __read_mostly;
+int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
+int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
+unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
+unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
+int heap_stack_gap = 0;
+
+atomic_long_t mmap_pages_allocated;
+
+/*
+ * The global memory commitment made in the system can be a metric
+ * that can be used to drive ballooning decisions when Linux is hosted
+ * as a guest. On Hyper-V, the host implements a policy engine for dynamically
+ * balancing memory across competing virtual machines that are hosted.
+ * Several metrics drive this policy engine including the guest reported
+ * memory commitment.
+ */
+unsigned long vm_memory_committed(void)
+{
+	return percpu_counter_read_positive(&vm_committed_as);
+}
+
+EXPORT_SYMBOL_GPL(vm_memory_committed);
+
+EXPORT_SYMBOL(mem_map);
+
+/* list of mapped, potentially shareable regions */
+static struct kmem_cache *vm_region_jar;
+struct rb_root nommu_region_tree = RB_ROOT;
+DECLARE_RWSEM(nommu_region_sem);
+
+const struct vm_operations_struct generic_file_vm_ops = {
+};
+
+/*
+ * Return the total memory allocated for this pointer, not
+ * just what the caller asked for.
+ *
+ * Doesn't have to be accurate, i.e. may have races.
+ */
+unsigned int kobjsize(const void *objp)
+{
+	struct page *page;
+
+	/*
+	 * If the object we have should not have ksize performed on it,
+	 * return size of 0
+	 */
+	if (!objp || !virt_addr_valid(objp))
+		return 0;
+
+	page = virt_to_head_page(objp);
+
+	/*
+	 * If the allocator sets PageSlab, we know the pointer came from
+	 * kmalloc().
+	 */
+	if (PageSlab(page))
+		return ksize(objp);
+
+	/*
+	 * If it's not a compound page, see if we have a matching VMA
+	 * region. This test is intentionally done in reverse order,
+	 * so if there's no VMA, we still fall through and hand back
+	 * PAGE_SIZE for 0-order pages.
+	 */
+	if (!PageCompound(page)) {
+		struct vm_area_struct *vma;
+
+		vma = find_vma(current->mm, (unsigned long)objp);
+		if (vma)
+			return vma->vm_end - vma->vm_start;
+	}
+
+	/*
+	 * The ksize() function is only guaranteed to work for pointers
+	 * returned by kmalloc(). So handle arbitrary pointers here.
+	 */
+	return PAGE_SIZE << compound_order(page);
+}
+
+long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		      unsigned long start, unsigned long nr_pages,
+		      unsigned int foll_flags, struct page **pages,
+		      struct vm_area_struct **vmas, int *nonblocking)
+{
+	struct vm_area_struct *vma;
+	unsigned long vm_flags;
+	int i;
+
+	/* calculate required read or write permissions.
+	 * If FOLL_FORCE is set, we only require the "MAY" flags.
+	 */
+	vm_flags  = (foll_flags & FOLL_WRITE) ?
+			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+	vm_flags &= (foll_flags & FOLL_FORCE) ?
+			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
+
+	for (i = 0; i < nr_pages; i++) {
+		vma = find_vma(mm, start);
+		if (!vma)
+			goto finish_or_fault;
+
+		/* protect what we can, including chardevs */
+		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
+		    !(vm_flags & vma->vm_flags))
+			goto finish_or_fault;
+
+		if (pages) {
+			pages[i] = virt_to_page(start);
+			if (pages[i])
+				page_cache_get(pages[i]);
+		}
+		if (vmas)
+			vmas[i] = vma;
+		start = (start + PAGE_SIZE) & PAGE_MASK;
+	}
+
+	return i;
+
+finish_or_fault:
+	return i ? : -EFAULT;
+}
+
+/*
+ * get a list of pages in an address range belonging to the specified process
+ * and indicate the VMA that covers each page
+ * - this is potentially dodgy as we may end incrementing the page count of a
+ *   slab page or a secondary page from a compound page
+ * - don't permit access to VMAs that don't support it, such as I/O mappings
+ */
+long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		    unsigned long start, unsigned long nr_pages,
+		    int write, int force, struct page **pages,
+		    struct vm_area_struct **vmas)
+{
+	int flags = 0;
+
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
+	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
+				NULL);
+}
+EXPORT_SYMBOL(get_user_pages);
+
+long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
+			   unsigned long start, unsigned long nr_pages,
+			   int write, int force, struct page **pages,
+			   int *locked)
+{
+	return get_user_pages(tsk, mm, start, nr_pages, write, force,
+			      pages, NULL);
+}
+EXPORT_SYMBOL(get_user_pages_locked);
+
+long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+			       unsigned long start, unsigned long nr_pages,
+			       int write, int force, struct page **pages,
+			       unsigned int gup_flags)
+{
+	long ret;
+	down_read(&mm->mmap_sem);
+	ret = get_user_pages(tsk, mm, start, nr_pages, write, force,
+			     pages, NULL);
+	up_read(&mm->mmap_sem);
+	return ret;
+}
+EXPORT_SYMBOL(__get_user_pages_unlocked);
+
+long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+			     unsigned long start, unsigned long nr_pages,
+			     int write, int force, struct page **pages)
+{
+	return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
+					 force, pages, 0);
+}
+EXPORT_SYMBOL(get_user_pages_unlocked);
+
+/**
+ * follow_pfn - look up PFN at a user virtual address
+ * @vma: memory mapping
+ * @address: user virtual address
+ * @pfn: location to store found PFN
+ *
+ * Only IO mappings and raw PFN mappings are allowed.
+ *
+ * Returns zero and the pfn at @pfn on success, -ve otherwise.
+ */
+int follow_pfn(struct vm_area_struct *vma, unsigned long address,
+	unsigned long *pfn)
+{
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+		return -EINVAL;
+
+	*pfn = address >> PAGE_SHIFT;
+	return 0;
+}
+EXPORT_SYMBOL(follow_pfn);
+
+LIST_HEAD(vmap_area_list);
+
+void vfree(const void *addr)
+{
+	kfree(addr);
+}
+EXPORT_SYMBOL(vfree);
+
+void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
+{
+	/*
+	 *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
+	 * returns only a logical address.
+	 */
+	return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
+}
+EXPORT_SYMBOL(__vmalloc);
+
+void *vmalloc_user(unsigned long size)
+{
+	void *ret;
+
+	ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+			PAGE_KERNEL);
+	if (ret) {
+		struct vm_area_struct *vma;
+
+		down_write(&current->mm->mmap_sem);
+		vma = find_vma(current->mm, (unsigned long)ret);
+		if (vma)
+			vma->vm_flags |= VM_USERMAP;
+		up_write(&current->mm->mmap_sem);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(vmalloc_user);
+
+struct page *vmalloc_to_page(const void *addr)
+{
+	return virt_to_page(addr);
+}
+EXPORT_SYMBOL(vmalloc_to_page);
+
+unsigned long vmalloc_to_pfn(const void *addr)
+{
+	return page_to_pfn(virt_to_page(addr));
+}
+EXPORT_SYMBOL(vmalloc_to_pfn);
+
+long vread(char *buf, char *addr, unsigned long count)
+{
+	/* Don't allow overflow */
+	if ((unsigned long) buf + count < count)
+		count = -(unsigned long) buf;
+
+	memcpy(buf, addr, count);
+	return count;
+}
+
+long vwrite(char *buf, char *addr, unsigned long count)
+{
+	/* Don't allow overflow */
+	if ((unsigned long) addr + count < count)
+		count = -(unsigned long) addr;
+
+	memcpy(addr, buf, count);
+	return count;
+}
+
+/*
+ *	vmalloc  -  allocate virtually contiguous memory
+ *
+ *	@size:		allocation size
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vmalloc(unsigned long size)
+{
+       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
+}
+EXPORT_SYMBOL(vmalloc);
+
+/*
+ *	vzalloc - allocate virtually contiguous memory with zero fill
+ *
+ *	@size:		allocation size
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *	The memory allocated is set to zero.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vzalloc(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+			PAGE_KERNEL);
+}
+EXPORT_SYMBOL(vzalloc);
+
+/**
+ * vmalloc_node - allocate memory on a specific node
+ * @size:	allocation size
+ * @node:	numa node
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ *
+ * For tight control over page level allocator and protection flags
+ * use __vmalloc() instead.
+ */
+void *vmalloc_node(unsigned long size, int node)
+{
+	return vmalloc(size);
+}
+EXPORT_SYMBOL(vmalloc_node);
+
+/**
+ * vzalloc_node - allocate memory on a specific node with zero fill
+ * @size:	allocation size
+ * @node:	numa node
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ * The memory allocated is set to zero.
+ *
+ * For tight control over page level allocator and protection flags
+ * use __vmalloc() instead.
+ */
+void *vzalloc_node(unsigned long size, int node)
+{
+	return vzalloc(size);
+}
+EXPORT_SYMBOL(vzalloc_node);
+
+#ifndef PAGE_KERNEL_EXEC
+# define PAGE_KERNEL_EXEC PAGE_KERNEL
+#endif
+
+/**
+ *	vmalloc_exec  -  allocate virtually contiguous, executable memory
+ *	@size:		allocation size
+ *
+ *	Kernel-internal function to allocate enough pages to cover @size
+ *	the page level allocator and map them into contiguous and
+ *	executable kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+
+void *vmalloc_exec(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
+}
+
+/**
+ * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
+ *	@size:		allocation size
+ *
+ *	Allocate enough 32bit PA addressable pages to cover @size from the
+ *	page level allocator and map them into contiguous kernel virtual space.
+ */
+void *vmalloc_32(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
+}
+EXPORT_SYMBOL(vmalloc_32);
+
+/**
+ * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
+ *	@size:		allocation size
+ *
+ * The resulting memory area is 32bit addressable and zeroed so it can be
+ * mapped to userspace without leaking data.
+ *
+ * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
+ * remap_vmalloc_range() are permissible.
+ */
+void *vmalloc_32_user(unsigned long size)
+{
+	/*
+	 * We'll have to sort out the ZONE_DMA bits for 64-bit,
+	 * but for now this can simply use vmalloc_user() directly.
+	 */
+	return vmalloc_user(size);
+}
+EXPORT_SYMBOL(vmalloc_32_user);
+
+void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
+{
+	BUG();
+	return NULL;
+}
+EXPORT_SYMBOL(vmap);
+
+void vunmap(const void *addr)
+{
+	BUG();
+}
+EXPORT_SYMBOL(vunmap);
+
+void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
+{
+	BUG();
+	return NULL;
+}
+EXPORT_SYMBOL(vm_map_ram);
+
+void vm_unmap_ram(const void *mem, unsigned int count)
+{
+	BUG();
+}
+EXPORT_SYMBOL(vm_unmap_ram);
+
+void vm_unmap_aliases(void)
+{
+}
+EXPORT_SYMBOL_GPL(vm_unmap_aliases);
+
+/*
+ * Implement a stub for vmalloc_sync_all() if the architecture chose not to
+ * have one.
+ */
+void __weak vmalloc_sync_all(void)
+{
+}
+
+/**
+ *	alloc_vm_area - allocate a range of kernel address space
+ *	@size:		size of the area
+ *
+ *	Returns:	NULL on failure, vm_struct on success
+ *
+ *	This function reserves a range of kernel address space, and
+ *	allocates pagetables to map that range.  No actual mappings
+ *	are created.  If the kernel address space is not shared
+ *	between processes, it syncs the pagetable across all
+ *	processes.
+ */
+struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
+{
+	BUG();
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(alloc_vm_area);
+
+void free_vm_area(struct vm_struct *area)
+{
+	BUG();
+}
+EXPORT_SYMBOL_GPL(free_vm_area);
+
+int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
+		   struct page *page)
+{
+	return -EINVAL;
+}
+EXPORT_SYMBOL(vm_insert_page);
+
+/*
+ *  sys_brk() for the most part doesn't need the global kernel
+ *  lock, except when an application is doing something nasty
+ *  like trying to un-brk an area that has already been mapped
+ *  to a regular file.  in this case, the unmapping will need
+ *  to invoke file system routines that need the global lock.
+ */
+SYSCALL_DEFINE1(brk, unsigned long, brk)
+{
+	struct mm_struct *mm = current->mm;
+
+	if (brk < mm->start_brk || brk > mm->context.end_brk)
+		return mm->brk;
+
+	if (mm->brk == brk)
+		return mm->brk;
+
+	/*
+	 * Always allow shrinking brk
+	 */
+	if (brk <= mm->brk) {
+		mm->brk = brk;
+		return brk;
+	}
+
+	/*
+	 * Ok, looks good - let it rip.
+	 */
+	flush_icache_range(mm->brk, brk);
+	return mm->brk = brk;
+}
+
+/*
+ * initialise the VMA and region record slabs
+ */
+void __init mmap_init(void)
+{
+	int ret;
+
+	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
+	VM_BUG_ON(ret);
+	vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
+}
+
+/*
+ * validate the region tree
+ * - the caller must hold the region lock
+ */
+#ifdef CONFIG_DEBUG_NOMMU_REGIONS
+static noinline void validate_nommu_regions(void)
+{
+	struct vm_region *region, *last;
+	struct rb_node *p, *lastp;
+
+	lastp = rb_first(&nommu_region_tree);
+	if (!lastp)
+		return;
+
+	last = rb_entry(lastp, struct vm_region, vm_rb);
+	BUG_ON(last->vm_end <= last->vm_start);
+	BUG_ON(last->vm_top < last->vm_end);
+
+	while ((p = rb_next(lastp))) {
+		region = rb_entry(p, struct vm_region, vm_rb);
+		last = rb_entry(lastp, struct vm_region, vm_rb);
+
+		BUG_ON(region->vm_end <= region->vm_start);
+		BUG_ON(region->vm_top < region->vm_end);
+		BUG_ON(region->vm_start < last->vm_top);
+
+		lastp = p;
+	}
+}
+#else
+static void validate_nommu_regions(void)
+{
+}
+#endif
+
+/*
+ * add a region into the global tree
+ */
+static void add_nommu_region(struct vm_region *region)
+{
+	struct vm_region *pregion;
+	struct rb_node **p, *parent;
+
+	validate_nommu_regions();
+
+	parent = NULL;
+	p = &nommu_region_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		pregion = rb_entry(parent, struct vm_region, vm_rb);
+		if (region->vm_start < pregion->vm_start)
+			p = &(*p)->rb_left;
+		else if (region->vm_start > pregion->vm_start)
+			p = &(*p)->rb_right;
+		else if (pregion == region)
+			return;
+		else
+			BUG();
+	}
+
+	rb_link_node(&region->vm_rb, parent, p);
+	rb_insert_color(&region->vm_rb, &nommu_region_tree);
+
+	validate_nommu_regions();
+}
+
+/*
+ * delete a region from the global tree
+ */
+static void delete_nommu_region(struct vm_region *region)
+{
+	BUG_ON(!nommu_region_tree.rb_node);
+
+	validate_nommu_regions();
+	rb_erase(&region->vm_rb, &nommu_region_tree);
+	validate_nommu_regions();
+}
+
+/*
+ * free a contiguous series of pages
+ */
+static void free_page_series(unsigned long from, unsigned long to)
+{
+	for (; from < to; from += PAGE_SIZE) {
+		struct page *page = virt_to_page(from);
+
+		atomic_long_dec(&mmap_pages_allocated);
+		put_page(page);
+	}
+}
+
+/*
+ * release a reference to a region
+ * - the caller must hold the region semaphore for writing, which this releases
+ * - the region may not have been added to the tree yet, in which case vm_top
+ *   will equal vm_start
+ */
+static void __put_nommu_region(struct vm_region *region)
+	__releases(nommu_region_sem)
+{
+	BUG_ON(!nommu_region_tree.rb_node);
+
+	if (--region->vm_usage == 0) {
+		if (region->vm_top > region->vm_start)
+			delete_nommu_region(region);
+		up_write(&nommu_region_sem);
+
+		if (region->vm_file)
+			fput(region->vm_file);
+
+		/* IO memory and memory shared directly out of the pagecache
+		 * from ramfs/tmpfs mustn't be released here */
+		if (region->vm_flags & VM_MAPPED_COPY)
+			free_page_series(region->vm_start, region->vm_top);
+		kmem_cache_free(vm_region_jar, region);
+	} else {
+		up_write(&nommu_region_sem);
+	}
+}
+
+/*
+ * release a reference to a region
+ */
+static void put_nommu_region(struct vm_region *region)
+{
+	down_write(&nommu_region_sem);
+	__put_nommu_region(region);
+}
+
+/*
+ * update protection on a vma
+ */
+static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
+{
+#ifdef CONFIG_MPU
+	struct mm_struct *mm = vma->vm_mm;
+	long start = vma->vm_start & PAGE_MASK;
+	while (start < vma->vm_end) {
+		protect_page(mm, start, flags);
+		start += PAGE_SIZE;
+	}
+	update_protections(mm);
+#endif
+}
+
+/*
+ * add a VMA into a process's mm_struct in the appropriate place in the list
+ * and tree and add to the address space's page tree also if not an anonymous
+ * page
+ * - should be called with mm->mmap_sem held writelocked
+ */
+static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	struct vm_area_struct *pvma, *prev;
+	struct address_space *mapping;
+	struct rb_node **p, *parent, *rb_prev;
+
+	BUG_ON(!vma->vm_region);
+
+	mm->map_count++;
+	vma->vm_mm = mm;
+
+	protect_vma(vma, vma->vm_flags);
+
+	/* add the VMA to the mapping */
+	if (vma->vm_file) {
+		mapping = vma->vm_file->f_mapping;
+
+		i_mmap_lock_write(mapping);
+		flush_dcache_mmap_lock(mapping);
+		vma_interval_tree_insert(vma, &mapping->i_mmap);
+		flush_dcache_mmap_unlock(mapping);
+		i_mmap_unlock_write(mapping);
+	}
+
+	/* add the VMA to the tree */
+	parent = rb_prev = NULL;
+	p = &mm->mm_rb.rb_node;
+	while (*p) {
+		parent = *p;
+		pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
+
+		/* sort by: start addr, end addr, VMA struct addr in that order
+		 * (the latter is necessary as we may get identical VMAs) */
+		if (vma->vm_start < pvma->vm_start)
+			p = &(*p)->rb_left;
+		else if (vma->vm_start > pvma->vm_start) {
+			rb_prev = parent;
+			p = &(*p)->rb_right;
+		} else if (vma->vm_end < pvma->vm_end)
+			p = &(*p)->rb_left;
+		else if (vma->vm_end > pvma->vm_end) {
+			rb_prev = parent;
+			p = &(*p)->rb_right;
+		} else if (vma < pvma)
+			p = &(*p)->rb_left;
+		else if (vma > pvma) {
+			rb_prev = parent;
+			p = &(*p)->rb_right;
+		} else
+			BUG();
+	}
+
+	rb_link_node(&vma->vm_rb, parent, p);
+	rb_insert_color(&vma->vm_rb, &mm->mm_rb);
+
+	/* add VMA to the VMA list also */
+	prev = NULL;
+	if (rb_prev)
+		prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
+
+	__vma_link_list(mm, vma, prev, parent);
+}
+
+/*
+ * delete a VMA from its owning mm_struct and address space
+ */
+static void delete_vma_from_mm(struct vm_area_struct *vma)
+{
+	int i;
+	struct address_space *mapping;
+	struct mm_struct *mm = vma->vm_mm;
+	struct task_struct *curr = current;
+
+	protect_vma(vma, 0);
+
+	mm->map_count--;
+	for (i = 0; i < VMACACHE_SIZE; i++) {
+		/* if the vma is cached, invalidate the entire cache */
+		if (curr->vmacache[i] == vma) {
+			vmacache_invalidate(mm);
+			break;
+		}
+	}
+
+	/* remove the VMA from the mapping */
+	if (vma->vm_file) {
+		mapping = vma->vm_file->f_mapping;
+
+		i_mmap_lock_write(mapping);
+		flush_dcache_mmap_lock(mapping);
+		vma_interval_tree_remove(vma, &mapping->i_mmap);
+		flush_dcache_mmap_unlock(mapping);
+		i_mmap_unlock_write(mapping);
+	}
+
+	/* remove from the MM's tree and list */
+	rb_erase(&vma->vm_rb, &mm->mm_rb);
+
+	if (vma->vm_prev)
+		vma->vm_prev->vm_next = vma->vm_next;
+	else
+		mm->mmap = vma->vm_next;
+
+	if (vma->vm_next)
+		vma->vm_next->vm_prev = vma->vm_prev;
+}
+
+/*
+ * destroy a VMA record
+ */
+static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	if (vma->vm_ops && vma->vm_ops->close)
+		vma->vm_ops->close(vma);
+	if (vma->vm_file)
+		fput(vma->vm_file);
+	put_nommu_region(vma->vm_region);
+	kmem_cache_free(vm_area_cachep, vma);
+}
+
+/*
+ * look up the first VMA in which addr resides, NULL if none
+ * - should be called with mm->mmap_sem at least held readlocked
+ */
+struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+{
+	struct vm_area_struct *vma;
+
+	/* check the cache first */
+	vma = vmacache_find(mm, addr);
+	if (likely(vma))
+		return vma;
+
+	/* trawl the list (there may be multiple mappings in which addr
+	 * resides) */
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (vma->vm_start > addr)
+			return NULL;
+		if (vma->vm_end > addr) {
+			vmacache_update(addr, vma);
+			return vma;
+		}
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(find_vma);
+
+/*
+ * find a VMA
+ * - we don't extend stack VMAs under NOMMU conditions
+ */
+struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
+{
+	return find_vma(mm, addr);
+}
+
+/*
+ * expand a stack to a given address
+ * - not supported under NOMMU conditions
+ */
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+	return -ENOMEM;
+}
+
+/*
+ * look up the first VMA exactly that exactly matches addr
+ * - should be called with mm->mmap_sem at least held readlocked
+ */
+static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
+					     unsigned long addr,
+					     unsigned long len)
+{
+	struct vm_area_struct *vma;
+	unsigned long end = addr + len;
+
+	/* check the cache first */
+	vma = vmacache_find_exact(mm, addr, end);
+	if (vma)
+		return vma;
+
+	/* trawl the list (there may be multiple mappings in which addr
+	 * resides) */
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (vma->vm_start < addr)
+			continue;
+		if (vma->vm_start > addr)
+			return NULL;
+		if (vma->vm_end == end) {
+			vmacache_update(addr, vma);
+			return vma;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * determine whether a mapping should be permitted and, if so, what sort of
+ * mapping we're capable of supporting
+ */
+static int validate_mmap_request(struct file *file,
+				 unsigned long addr,
+				 unsigned long len,
+				 unsigned long prot,
+				 unsigned long flags,
+				 unsigned long pgoff,
+				 unsigned long *_capabilities)
+{
+	unsigned long capabilities, rlen;
+	int ret;
+
+	/* do the simple checks first */
+	if (flags & MAP_FIXED)
+		return -EINVAL;
+
+	if ((flags & MAP_TYPE) != MAP_PRIVATE &&
+	    (flags & MAP_TYPE) != MAP_SHARED)
+		return -EINVAL;
+
+	if (!len)
+		return -EINVAL;
+
+	/* Careful about overflows.. */
+	rlen = PAGE_ALIGN(len);
+	if (!rlen || rlen > TASK_SIZE)
+		return -ENOMEM;
+
+	/* offset overflow? */
+	if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
+		return -EOVERFLOW;
+
+	if (file) {
+		/* files must support mmap */
+		if (!file->f_op->mmap)
+			return -ENODEV;
+
+		/* work out if what we've got could possibly be shared
+		 * - we support chardevs that provide their own "memory"
+		 * - we support files/blockdevs that are memory backed
+		 */
+		if (file->f_op->mmap_capabilities) {
+			capabilities = file->f_op->mmap_capabilities(file);
+		} else {
+			/* no explicit capabilities set, so assume some
+			 * defaults */
+			switch (file_inode(file)->i_mode & S_IFMT) {
+			case S_IFREG:
+			case S_IFBLK:
+				capabilities = NOMMU_MAP_COPY;
+				break;
+
+			case S_IFCHR:
+				capabilities =
+					NOMMU_MAP_DIRECT |
+					NOMMU_MAP_READ |
+					NOMMU_MAP_WRITE;
+				break;
+
+			default:
+				return -EINVAL;
+			}
+		}
+
+		/* eliminate any capabilities that we can't support on this
+		 * device */
+		if (!file->f_op->get_unmapped_area)
+			capabilities &= ~NOMMU_MAP_DIRECT;
+		if (!(file->f_mode & FMODE_CAN_READ))
+			capabilities &= ~NOMMU_MAP_COPY;
+
+		/* The file shall have been opened with read permission. */
+		if (!(file->f_mode & FMODE_READ))
+			return -EACCES;
+
+		if (flags & MAP_SHARED) {
+			/* do checks for writing, appending and locking */
+			if ((prot & PROT_WRITE) &&
+			    !(file->f_mode & FMODE_WRITE))
+				return -EACCES;
+
+			if (IS_APPEND(file_inode(file)) &&
+			    (file->f_mode & FMODE_WRITE))
+				return -EACCES;
+
+			if (locks_verify_locked(file))
+				return -EAGAIN;
+
+			if (!(capabilities & NOMMU_MAP_DIRECT))
+				return -ENODEV;
+
+			/* we mustn't privatise shared mappings */
+			capabilities &= ~NOMMU_MAP_COPY;
+		} else {
+			/* we're going to read the file into private memory we
+			 * allocate */
+			if (!(capabilities & NOMMU_MAP_COPY))
+				return -ENODEV;
+
+			/* we don't permit a private writable mapping to be
+			 * shared with the backing device */
+			if (prot & PROT_WRITE)
+				capabilities &= ~NOMMU_MAP_DIRECT;
+		}
+
+		if (capabilities & NOMMU_MAP_DIRECT) {
+			if (((prot & PROT_READ)  && !(capabilities & NOMMU_MAP_READ))  ||
+			    ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
+			    ((prot & PROT_EXEC)  && !(capabilities & NOMMU_MAP_EXEC))
+			    ) {
+				capabilities &= ~NOMMU_MAP_DIRECT;
+				if (flags & MAP_SHARED) {
+					pr_warn("MAP_SHARED not completely supported on !MMU\n");
+					return -EINVAL;
+				}
+			}
+		}
+
+		/* handle executable mappings and implied executable
+		 * mappings */
+		if (path_noexec(&file->f_path)) {
+			if (prot & PROT_EXEC)
+				return -EPERM;
+		} else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
+			/* handle implication of PROT_EXEC by PROT_READ */
+			if (current->personality & READ_IMPLIES_EXEC) {
+				if (capabilities & NOMMU_MAP_EXEC)
+					prot |= PROT_EXEC;
+			}
+		} else if ((prot & PROT_READ) &&
+			 (prot & PROT_EXEC) &&
+			 !(capabilities & NOMMU_MAP_EXEC)
+			 ) {
+			/* backing file is not executable, try to copy */
+			capabilities &= ~NOMMU_MAP_DIRECT;
+		}
+	} else {
+		/* anonymous mappings are always memory backed and can be
+		 * privately mapped
+		 */
+		capabilities = NOMMU_MAP_COPY;
+
+		/* handle PROT_EXEC implication by PROT_READ */
+		if ((prot & PROT_READ) &&
+		    (current->personality & READ_IMPLIES_EXEC))
+			prot |= PROT_EXEC;
+	}
+
+	/* allow the security API to have its say */
+	ret = security_mmap_addr(addr);
+	if (ret < 0)
+		return ret;
+
+	/* looks okay */
+	*_capabilities = capabilities;
+	return 0;
+}
+
+/*
+ * we've determined that we can make the mapping, now translate what we
+ * now know into VMA flags
+ */
+static unsigned long determine_vm_flags(struct file *file,
+					unsigned long prot,
+					unsigned long flags,
+					unsigned long capabilities)
+{
+	unsigned long vm_flags;
+
+	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
+	/* vm_flags |= mm->def_flags; */
+
+	if (!(capabilities & NOMMU_MAP_DIRECT)) {
+		/* attempt to share read-only copies of mapped file chunks */
+		vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+		if (file && !(prot & PROT_WRITE))
+			vm_flags |= VM_MAYSHARE;
+	} else {
+		/* overlay a shareable mapping on the backing device or inode
+		 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
+		 * romfs/cramfs */
+		vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
+		if (flags & MAP_SHARED)
+			vm_flags |= VM_SHARED;
+	}
+
+	/* refuse to let anyone share private mappings with this process if
+	 * it's being traced - otherwise breakpoints set in it may interfere
+	 * with another untraced process
+	 */
+	if ((flags & MAP_PRIVATE) && current->ptrace)
+		vm_flags &= ~VM_MAYSHARE;
+
+	return vm_flags;
+}
+
+/*
+ * set up a shared mapping on a file (the driver or filesystem provides and
+ * pins the storage)
+ */
+static int do_mmap_shared_file(struct vm_area_struct *vma)
+{
+	int ret;
+
+	ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
+	if (ret == 0) {
+		vma->vm_region->vm_top = vma->vm_region->vm_end;
+		return 0;
+	}
+	if (ret != -ENOSYS)
+		return ret;
+
+	/* getting -ENOSYS indicates that direct mmap isn't possible (as
+	 * opposed to tried but failed) so we can only give a suitable error as
+	 * it's not possible to make a private copy if MAP_SHARED was given */
+	return -ENODEV;
+}
+
+/*
+ * set up a private mapping or an anonymous shared mapping
+ */
+static int do_mmap_private(struct vm_area_struct *vma,
+			   struct vm_region *region,
+			   unsigned long len,
+			   unsigned long capabilities)
+{
+	unsigned long total, point;
+	void *base;
+	int ret, order;
+
+	/* invoke the file's mapping function so that it can keep track of
+	 * shared mappings on devices or memory
+	 * - VM_MAYSHARE will be set if it may attempt to share
+	 */
+	if (capabilities & NOMMU_MAP_DIRECT) {
+		ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
+		if (ret == 0) {
+			/* shouldn't return success if we're not sharing */
+			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
+			vma->vm_region->vm_top = vma->vm_region->vm_end;
+			return 0;
+		}
+		if (ret != -ENOSYS)
+			return ret;
+
+		/* getting an ENOSYS error indicates that direct mmap isn't
+		 * possible (as opposed to tried but failed) so we'll try to
+		 * make a private copy of the data and map that instead */
+	}
+
+
+	/* allocate some memory to hold the mapping
+	 * - note that this may not return a page-aligned address if the object
+	 *   we're allocating is smaller than a page
+	 */
+	order = get_order(len);
+	total = 1 << order;
+	point = len >> PAGE_SHIFT;
+
+	/* we don't want to allocate a power-of-2 sized page set */
+	if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
+		total = point;
+
+	base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
+	if (!base)
+		goto enomem;
+
+	atomic_long_add(total, &mmap_pages_allocated);
+
+	region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
+	region->vm_start = (unsigned long) base;
+	region->vm_end   = region->vm_start + len;
+	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
+
+	vma->vm_start = region->vm_start;
+	vma->vm_end   = region->vm_start + len;
+
+	if (vma->vm_file) {
+		/* read the contents of a file into the copy */
+		mm_segment_t old_fs;
+		loff_t fpos;
+
+		fpos = vma->vm_pgoff;
+		fpos <<= PAGE_SHIFT;
+
+		old_fs = get_fs();
+		set_fs(KERNEL_DS);
+		ret = __vfs_read(vma->vm_file, base, len, &fpos);
+		set_fs(old_fs);
+
+		if (ret < 0)
+			goto error_free;
+
+		/* clear the last little bit */
+		if (ret < len)
+			memset(base + ret, 0, len - ret);
+
+	}
+
+	return 0;
+
+error_free:
+	free_page_series(region->vm_start, region->vm_top);
+	region->vm_start = vma->vm_start = 0;
+	region->vm_end   = vma->vm_end = 0;
+	region->vm_top   = 0;
+	return ret;
+
+enomem:
+	pr_err("Allocation of length %lu from process %d (%s) failed\n",
+	       len, current->pid, current->comm);
+	show_free_areas(0);
+	return -ENOMEM;
+}
+
+/*
+ * handle mapping creation for uClinux
+ */
+unsigned long do_mmap(struct file *file,
+			unsigned long addr,
+			unsigned long len,
+			unsigned long prot,
+			unsigned long flags,
+			vm_flags_t vm_flags,
+			unsigned long pgoff,
+			unsigned long *populate)
+{
+	struct vm_area_struct *vma;
+	struct vm_region *region;
+	struct rb_node *rb;
+	unsigned long capabilities, result;
+	int ret;
+
+	*populate = 0;
+
+	/* decide whether we should attempt the mapping, and if so what sort of
+	 * mapping */
+	ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
+				    &capabilities);
+	if (ret < 0)
+		return ret;
+
+	/* we ignore the address hint */
+	addr = 0;
+	len = PAGE_ALIGN(len);
+
+	/* we've determined that we can make the mapping, now translate what we
+	 * now know into VMA flags */
+	vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
+
+	/* we're going to need to record the mapping */
+	region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
+	if (!region)
+		goto error_getting_region;
+
+	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+	if (!vma)
+		goto error_getting_vma;
+
+	region->vm_usage = 1;
+	region->vm_flags = vm_flags;
+	region->vm_pgoff = pgoff;
+
+	INIT_LIST_HEAD(&vma->anon_vma_chain);
+	vma->vm_flags = vm_flags;
+	vma->vm_pgoff = pgoff;
+
+	if (file) {
+		region->vm_file = get_file(file);
+		vma->vm_file = get_file(file);
+	}
+
+	down_write(&nommu_region_sem);
+
+	/* if we want to share, we need to check for regions created by other
+	 * mmap() calls that overlap with our proposed mapping
+	 * - we can only share with a superset match on most regular files
+	 * - shared mappings on character devices and memory backed files are
+	 *   permitted to overlap inexactly as far as we are concerned for in
+	 *   these cases, sharing is handled in the driver or filesystem rather
+	 *   than here
+	 */
+	if (vm_flags & VM_MAYSHARE) {
+		struct vm_region *pregion;
+		unsigned long pglen, rpglen, pgend, rpgend, start;
+
+		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+		pgend = pgoff + pglen;
+
+		for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
+			pregion = rb_entry(rb, struct vm_region, vm_rb);
+
+			if (!(pregion->vm_flags & VM_MAYSHARE))
+				continue;
+
+			/* search for overlapping mappings on the same file */
+			if (file_inode(pregion->vm_file) !=
+			    file_inode(file))
+				continue;
+
+			if (pregion->vm_pgoff >= pgend)
+				continue;
+
+			rpglen = pregion->vm_end - pregion->vm_start;
+			rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
+			rpgend = pregion->vm_pgoff + rpglen;
+			if (pgoff >= rpgend)
+				continue;
+
+			/* handle inexactly overlapping matches between
+			 * mappings */
+			if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
+			    !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
+				/* new mapping is not a subset of the region */
+				if (!(capabilities & NOMMU_MAP_DIRECT))
+					goto sharing_violation;
+				continue;
+			}
+
+			/* we've found a region we can share */
+			pregion->vm_usage++;
+			vma->vm_region = pregion;
+			start = pregion->vm_start;
+			start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
+			vma->vm_start = start;
+			vma->vm_end = start + len;
+
+			if (pregion->vm_flags & VM_MAPPED_COPY)
+				vma->vm_flags |= VM_MAPPED_COPY;
+			else {
+				ret = do_mmap_shared_file(vma);
+				if (ret < 0) {
+					vma->vm_region = NULL;
+					vma->vm_start = 0;
+					vma->vm_end = 0;
+					pregion->vm_usage--;
+					pregion = NULL;
+					goto error_just_free;
+				}
+			}
+			fput(region->vm_file);
+			kmem_cache_free(vm_region_jar, region);
+			region = pregion;
+			result = start;
+			goto share;
+		}
+
+		/* obtain the address at which to make a shared mapping
+		 * - this is the hook for quasi-memory character devices to
+		 *   tell us the location of a shared mapping
+		 */
+		if (capabilities & NOMMU_MAP_DIRECT) {
+			addr = file->f_op->get_unmapped_area(file, addr, len,
+							     pgoff, flags);
+			if (IS_ERR_VALUE(addr)) {
+				ret = addr;
+				if (ret != -ENOSYS)
+					goto error_just_free;
+
+				/* the driver refused to tell us where to site
+				 * the mapping so we'll have to attempt to copy
+				 * it */
+				ret = -ENODEV;
+				if (!(capabilities & NOMMU_MAP_COPY))
+					goto error_just_free;
+
+				capabilities &= ~NOMMU_MAP_DIRECT;
+			} else {
+				vma->vm_start = region->vm_start = addr;
+				vma->vm_end = region->vm_end = addr + len;
+			}
+		}
+	}
+
+	vma->vm_region = region;
+
+	/* set up the mapping
+	 * - the region is filled in if NOMMU_MAP_DIRECT is still set
+	 */
+	if (file && vma->vm_flags & VM_SHARED)
+		ret = do_mmap_shared_file(vma);
+	else
+		ret = do_mmap_private(vma, region, len, capabilities);
+	if (ret < 0)
+		goto error_just_free;
+	add_nommu_region(region);
+
+	/* clear anonymous mappings that don't ask for uninitialized data */
+	if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
+		memset((void *)region->vm_start, 0,
+		       region->vm_end - region->vm_start);
+
+	/* okay... we have a mapping; now we have to register it */
+	result = vma->vm_start;
+
+	current->mm->total_vm += len >> PAGE_SHIFT;
+
+share:
+	add_vma_to_mm(current->mm, vma);
+
+	/* we flush the region from the icache only when the first executable
+	 * mapping of it is made  */
+	if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
+		flush_icache_range(region->vm_start, region->vm_end);
+		region->vm_icache_flushed = true;
+	}
+
+	up_write(&nommu_region_sem);
+
+	return result;
+
+error_just_free:
+	up_write(&nommu_region_sem);
+error:
+	if (region->vm_file)
+		fput(region->vm_file);
+	kmem_cache_free(vm_region_jar, region);
+	if (vma->vm_file)
+		fput(vma->vm_file);
+	kmem_cache_free(vm_area_cachep, vma);
+	return ret;
+
+sharing_violation:
+	up_write(&nommu_region_sem);
+	pr_warn("Attempt to share mismatched mappings\n");
+	ret = -EINVAL;
+	goto error;
+
+error_getting_vma:
+	kmem_cache_free(vm_region_jar, region);
+	pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
+			len, current->pid);
+	show_free_areas(0);
+	return -ENOMEM;
+
+error_getting_region:
+	pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
+			len, current->pid);
+	show_free_areas(0);
+	return -ENOMEM;
+}
+
+SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
+		unsigned long, prot, unsigned long, flags,
+		unsigned long, fd, unsigned long, pgoff)
+{
+	struct file *file = NULL;
+	unsigned long retval = -EBADF;
+
+	audit_mmap_fd(fd, flags);
+	if (!(flags & MAP_ANONYMOUS)) {
+		file = fget(fd);
+		if (!file)
+			goto out;
+	}
+
+	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
+
+	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
+
+	if (file)
+		fput(file);
+out:
+	return retval;
+}
+
+#ifdef __ARCH_WANT_SYS_OLD_MMAP
+struct mmap_arg_struct {
+	unsigned long addr;
+	unsigned long len;
+	unsigned long prot;
+	unsigned long flags;
+	unsigned long fd;
+	unsigned long offset;
+};
+
+SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
+{
+	struct mmap_arg_struct a;
+
+	if (copy_from_user(&a, arg, sizeof(a)))
+		return -EFAULT;
+	if (offset_in_page(a.offset))
+		return -EINVAL;
+
+	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
+			      a.offset >> PAGE_SHIFT);
+}
+#endif /* __ARCH_WANT_SYS_OLD_MMAP */
+
+/*
+ * split a vma into two pieces at address 'addr', a new vma is allocated either
+ * for the first part or the tail.
+ */
+int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
+	      unsigned long addr, int new_below)
+{
+	struct vm_area_struct *new;
+	struct vm_region *region;
+	unsigned long npages;
+
+	/* we're only permitted to split anonymous regions (these should have
+	 * only a single usage on the region) */
+	if (vma->vm_file)
+		return -ENOMEM;
+
+	if (mm->map_count >= sysctl_max_map_count)
+		return -ENOMEM;
+
+	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
+	if (!region)
+		return -ENOMEM;
+
+	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+	if (!new) {
+		kmem_cache_free(vm_region_jar, region);
+		return -ENOMEM;
+	}
+
+	/* most fields are the same, copy all, and then fixup */
+	*new = *vma;
+	*region = *vma->vm_region;
+	new->vm_region = region;
+
+	npages = (addr - vma->vm_start) >> PAGE_SHIFT;
+
+	if (new_below) {
+		region->vm_top = region->vm_end = new->vm_end = addr;
+	} else {
+		region->vm_start = new->vm_start = addr;
+		region->vm_pgoff = new->vm_pgoff += npages;
+	}
+
+	if (new->vm_ops && new->vm_ops->open)
+		new->vm_ops->open(new);
+
+	delete_vma_from_mm(vma);
+	down_write(&nommu_region_sem);
+	delete_nommu_region(vma->vm_region);
+	if (new_below) {
+		vma->vm_region->vm_start = vma->vm_start = addr;
+		vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
+	} else {
+		vma->vm_region->vm_end = vma->vm_end = addr;
+		vma->vm_region->vm_top = addr;
+	}
+	add_nommu_region(vma->vm_region);
+	add_nommu_region(new->vm_region);
+	up_write(&nommu_region_sem);
+	add_vma_to_mm(mm, vma);
+	add_vma_to_mm(mm, new);
+	return 0;
+}
+
+/*
+ * shrink a VMA by removing the specified chunk from either the beginning or
+ * the end
+ */
+static int shrink_vma(struct mm_struct *mm,
+		      struct vm_area_struct *vma,
+		      unsigned long from, unsigned long to)
+{
+	struct vm_region *region;
+
+	/* adjust the VMA's pointers, which may reposition it in the MM's tree
+	 * and list */
+	delete_vma_from_mm(vma);
+	if (from > vma->vm_start)
+		vma->vm_end = from;
+	else
+		vma->vm_start = to;
+	add_vma_to_mm(mm, vma);
+
+	/* cut the backing region down to size */
+	region = vma->vm_region;
+	BUG_ON(region->vm_usage != 1);
+
+	down_write(&nommu_region_sem);
+	delete_nommu_region(region);
+	if (from > region->vm_start) {
+		to = region->vm_top;
+		region->vm_top = region->vm_end = from;
+	} else {
+		region->vm_start = to;
+	}
+	add_nommu_region(region);
+	up_write(&nommu_region_sem);
+
+	free_page_series(from, to);
+	return 0;
+}
+
+/*
+ * release a mapping
+ * - under NOMMU conditions the chunk to be unmapped must be backed by a single
+ *   VMA, though it need not cover the whole VMA
+ */
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+{
+	struct vm_area_struct *vma;
+	unsigned long end;
+	int ret;
+
+	len = PAGE_ALIGN(len);
+	if (len == 0)
+		return -EINVAL;
+
+	end = start + len;
+
+	/* find the first potentially overlapping VMA */
+	vma = find_vma(mm, start);
+	if (!vma) {
+		static int limit;
+		if (limit < 5) {
+			pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
+					current->pid, current->comm,
+					start, start + len - 1);
+			limit++;
+		}
+		return -EINVAL;
+	}
+
+	/* we're allowed to split an anonymous VMA but not a file-backed one */
+	if (vma->vm_file) {
+		do {
+			if (start > vma->vm_start)
+				return -EINVAL;
+			if (end == vma->vm_end)
+				goto erase_whole_vma;
+			vma = vma->vm_next;
+		} while (vma);
+		return -EINVAL;
+	} else {
+		/* the chunk must be a subset of the VMA found */
+		if (start == vma->vm_start && end == vma->vm_end)
+			goto erase_whole_vma;
+		if (start < vma->vm_start || end > vma->vm_end)
+			return -EINVAL;
+		if (offset_in_page(start))
+			return -EINVAL;
+		if (end != vma->vm_end && offset_in_page(end))
+			return -EINVAL;
+		if (start != vma->vm_start && end != vma->vm_end) {
+			ret = split_vma(mm, vma, start, 1);
+			if (ret < 0)
+				return ret;
+		}
+		return shrink_vma(mm, vma, start, end);
+	}
+
+erase_whole_vma:
+	delete_vma_from_mm(vma);
+	delete_vma(mm, vma);
+	return 0;
+}
+EXPORT_SYMBOL(do_munmap);
+
+int vm_munmap(unsigned long addr, size_t len)
+{
+	struct mm_struct *mm = current->mm;
+	int ret;
+
+	down_write(&mm->mmap_sem);
+	ret = do_munmap(mm, addr, len);
+	up_write(&mm->mmap_sem);
+	return ret;
+}
+EXPORT_SYMBOL(vm_munmap);
+
+SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
+{
+	return vm_munmap(addr, len);
+}
+
+/*
+ * release all the mappings made in a process's VM space
+ */
+void exit_mmap(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+
+	if (!mm)
+		return;
+
+	mm->total_vm = 0;
+
+	while ((vma = mm->mmap)) {
+		mm->mmap = vma->vm_next;
+		delete_vma_from_mm(vma);
+		delete_vma(mm, vma);
+		cond_resched();
+	}
+}
+
+unsigned long vm_brk(unsigned long addr, unsigned long len)
+{
+	return -ENOMEM;
+}
+
+/*
+ * expand (or shrink) an existing mapping, potentially moving it at the same
+ * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
+ *
+ * under NOMMU conditions, we only permit changing a mapping's size, and only
+ * as long as it stays within the region allocated by do_mmap_private() and the
+ * block is not shareable
+ *
+ * MREMAP_FIXED is not supported under NOMMU conditions
+ */
+static unsigned long do_mremap(unsigned long addr,
+			unsigned long old_len, unsigned long new_len,
+			unsigned long flags, unsigned long new_addr)
+{
+	struct vm_area_struct *vma;
+
+	/* insanity checks first */
+	old_len = PAGE_ALIGN(old_len);
+	new_len = PAGE_ALIGN(new_len);
+	if (old_len == 0 || new_len == 0)
+		return (unsigned long) -EINVAL;
+
+	if (offset_in_page(addr))
+		return -EINVAL;
+
+	if (flags & MREMAP_FIXED && new_addr != addr)
+		return (unsigned long) -EINVAL;
+
+	vma = find_vma_exact(current->mm, addr, old_len);
+	if (!vma)
+		return (unsigned long) -EINVAL;
+
+	if (vma->vm_end != vma->vm_start + old_len)
+		return (unsigned long) -EFAULT;
+
+	if (vma->vm_flags & VM_MAYSHARE)
+		return (unsigned long) -EPERM;
+
+	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
+		return (unsigned long) -ENOMEM;
+
+	/* all checks complete - do it */
+	vma->vm_end = vma->vm_start + new_len;
+	return vma->vm_start;
+}
+
+SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
+		unsigned long, new_len, unsigned long, flags,
+		unsigned long, new_addr)
+{
+	unsigned long ret;
+
+	down_write(&current->mm->mmap_sem);
+	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
+	up_write(&current->mm->mmap_sem);
+	return ret;
+}
+
+struct page *follow_page_mask(struct vm_area_struct *vma,
+			      unsigned long address, unsigned int flags,
+			      unsigned int *page_mask)
+{
+	*page_mask = 0;
+	return NULL;
+}
+
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+		unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+	if (addr != (pfn << PAGE_SHIFT))
+		return -EINVAL;
+
+	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
+	return 0;
+}
+EXPORT_SYMBOL(remap_pfn_range);
+
+int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
+{
+	unsigned long pfn = start >> PAGE_SHIFT;
+	unsigned long vm_len = vma->vm_end - vma->vm_start;
+
+	pfn += vma->vm_pgoff;
+	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_iomap_memory);
+
+int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
+			unsigned long pgoff)
+{
+	unsigned int size = vma->vm_end - vma->vm_start;
+
+	if (!(vma->vm_flags & VM_USERMAP))
+		return -EINVAL;
+
+	vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
+	vma->vm_end = vma->vm_start + size;
+
+	return 0;
+}
+EXPORT_SYMBOL(remap_vmalloc_range);
+
+unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	return -ENOMEM;
+}
+
+void unmap_mapping_range(struct address_space *mapping,
+			 loff_t const holebegin, loff_t const holelen,
+			 int even_cows)
+{
+}
+EXPORT_SYMBOL(unmap_mapping_range);
+
+/*
+ * Check that a process has enough memory to allocate a new virtual
+ * mapping. 0 means there is enough memory for the allocation to
+ * succeed and -ENOMEM implies there is not.
+ *
+ * We currently support three overcommit policies, which are set via the
+ * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
+ *
+ * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
+ * Additional code 2002 Jul 20 by Robert Love.
+ *
+ * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
+ *
+ * Note this is a helper function intended to be used by LSMs which
+ * wish to use this logic.
+ */
+int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
+{
+	long free, allowed, reserve;
+
+	vm_acct_memory(pages);
+
+	/*
+	 * Sometimes we want to use more memory than we have
+	 */
+	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
+		return 0;
+
+	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
+		free = global_page_state(NR_FREE_PAGES);
+		free += global_page_state(NR_FILE_PAGES);
+
+		/*
+		 * shmem pages shouldn't be counted as free in this
+		 * case, they can't be purged, only swapped out, and
+		 * that won't affect the overall amount of available
+		 * memory in the system.
+		 */
+		free -= global_page_state(NR_SHMEM);
+
+		free += get_nr_swap_pages();
+
+		/*
+		 * Any slabs which are created with the
+		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
+		 * which are reclaimable, under pressure.  The dentry
+		 * cache and most inode caches should fall into this
+		 */
+		free += global_page_state(NR_SLAB_RECLAIMABLE);
+
+		/*
+		 * Leave reserved pages. The pages are not for anonymous pages.
+		 */
+		if (free <= totalreserve_pages)
+			goto error;
+		else
+			free -= totalreserve_pages;
+
+		/*
+		 * Reserve some for root
+		 */
+		if (!cap_sys_admin)
+			free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
+
+		if (free > pages)
+			return 0;
+
+		goto error;
+	}
+
+	allowed = vm_commit_limit();
+	/*
+	 * Reserve some 3% for root
+	 */
+	if (!cap_sys_admin)
+		allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
+
+	/*
+	 * Don't let a single process grow so big a user can't recover
+	 */
+	if (mm) {
+		reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
+		allowed -= min_t(long, mm->total_vm / 32, reserve);
+	}
+
+	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
+		return 0;
+
+error:
+	vm_unacct_memory(pages);
+
+	return -ENOMEM;
+}
+
+int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	BUG();
+	return 0;
+}
+EXPORT_SYMBOL(filemap_fault);
+
+void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	BUG();
+}
+EXPORT_SYMBOL(filemap_map_pages);
+
+static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
+		unsigned long addr, void *buf, int len, int write)
+{
+	struct vm_area_struct *vma;
+
+	down_read(&mm->mmap_sem);
+
+	/* the access must start within one of the target process's mappings */
+	vma = find_vma(mm, addr);
+	if (vma) {
+		/* don't overrun this mapping */
+		if (addr + len >= vma->vm_end)
+			len = vma->vm_end - addr;
+
+		/* only read or write mappings where it is permitted */
+		if (write && vma->vm_flags & VM_MAYWRITE)
+			copy_to_user_page(vma, NULL, addr,
+					 (void *) addr, buf, len);
+		else if (!write && vma->vm_flags & VM_MAYREAD)
+			copy_from_user_page(vma, NULL, addr,
+					    buf, (void *) addr, len);
+		else
+			len = 0;
+	} else {
+		len = 0;
+	}
+
+	up_read(&mm->mmap_sem);
+
+	return len;
+}
+
+/**
+ * @access_remote_vm - access another process' address space
+ * @mm:		the mm_struct of the target address space
+ * @addr:	start address to access
+ * @buf:	source or destination buffer
+ * @len:	number of bytes to transfer
+ * @write:	whether the access is a write
+ *
+ * The caller must hold a reference on @mm.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+		void *buf, int len, int write)
+{
+	return __access_remote_vm(NULL, mm, addr, buf, len, write);
+}
+
+/*
+ * Access another process' address space.
+ * - source/target buffer must be kernel space
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+{
+	struct mm_struct *mm;
+
+	if (addr + len < addr)
+		return 0;
+
+	mm = get_task_mm(tsk);
+	if (!mm)
+		return 0;
+
+	len = __access_remote_vm(tsk, mm, addr, buf, len, write);
+
+	mmput(mm);
+	return len;
+}
+
+/**
+ * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
+ * @inode: The inode to check
+ * @size: The current filesize of the inode
+ * @newsize: The proposed filesize of the inode
+ *
+ * Check the shared mappings on an inode on behalf of a shrinking truncate to
+ * make sure that that any outstanding VMAs aren't broken and then shrink the
+ * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
+ * automatically grant mappings that are too large.
+ */
+int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
+				size_t newsize)
+{
+	struct vm_area_struct *vma;
+	struct vm_region *region;
+	pgoff_t low, high;
+	size_t r_size, r_top;
+
+	low = newsize >> PAGE_SHIFT;
+	high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	down_write(&nommu_region_sem);
+	i_mmap_lock_read(inode->i_mapping);
+
+	/* search for VMAs that fall within the dead zone */
+	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
+		/* found one - only interested if it's shared out of the page
+		 * cache */
+		if (vma->vm_flags & VM_SHARED) {
+			i_mmap_unlock_read(inode->i_mapping);
+			up_write(&nommu_region_sem);
+			return -ETXTBSY; /* not quite true, but near enough */
+		}
+	}
+
+	/* reduce any regions that overlap the dead zone - if in existence,
+	 * these will be pointed to by VMAs that don't overlap the dead zone
+	 *
+	 * we don't check for any regions that start beyond the EOF as there
+	 * shouldn't be any
+	 */
+	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
+		if (!(vma->vm_flags & VM_SHARED))
+			continue;
+
+		region = vma->vm_region;
+		r_size = region->vm_top - region->vm_start;
+		r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
+
+		if (r_top > newsize) {
+			region->vm_top -= r_top - newsize;
+			if (region->vm_end > region->vm_top)
+				region->vm_end = region->vm_top;
+		}
+	}
+
+	i_mmap_unlock_read(inode->i_mapping);
+	up_write(&nommu_region_sem);
+	return 0;
+}
+
+/*
+ * Initialise sysctl_user_reserve_kbytes.
+ *
+ * This is intended to prevent a user from starting a single memory hogging
+ * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
+ * mode.
+ *
+ * The default value is min(3% of free memory, 128MB)
+ * 128MB is enough to recover with sshd/login, bash, and top/kill.
+ */
+static int __meminit init_user_reserve(void)
+{
+	unsigned long free_kbytes;
+
+	free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+	sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
+	return 0;
+}
+subsys_initcall(init_user_reserve);
+
+/*
+ * Initialise sysctl_admin_reserve_kbytes.
+ *
+ * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
+ * to log in and kill a memory hogging process.
+ *
+ * Systems with more than 256MB will reserve 8MB, enough to recover
+ * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
+ * only reserve 3% of free pages by default.
+ */
+static int __meminit init_admin_reserve(void)
+{
+	unsigned long free_kbytes;
+
+	free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+	sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
+	return 0;
+}
+subsys_initcall(init_admin_reserve);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
new file mode 100644
index 0000000..c126809
--- /dev/null
+++ b/mm/oom_kill.c
@@ -0,0 +1,770 @@
+/*
+ *  linux/mm/oom_kill.c
+ * 
+ *  Copyright (C)  1998,2000  Rik van Riel
+ *	Thanks go out to Claus Fischer for some serious inspiration and
+ *	for goading me into coding this file...
+ *  Copyright (C)  2010  Google, Inc.
+ *	Rewritten by David Rientjes
+ *
+ *  The routines in this file are used to kill a process when
+ *  we're seriously out of memory. This gets called from __alloc_pages()
+ *  in mm/page_alloc.c when we really run out of memory.
+ *
+ *  Since we won't call these routines often (on a well-configured
+ *  machine) this file will double as a 'coding guide' and a signpost
+ *  for newbie kernel hackers. It features several pointers to major
+ *  kernel subsystems and hints as to where to find out what things do.
+ */
+
+#include <linux/oom.h>
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/gfp.h>
+#include <linux/sched.h>
+#include <linux/swap.h>
+#include <linux/timex.h>
+#include <linux/jiffies.h>
+#include <linux/cpuset.h>
+#include <linux/export.h>
+#include <linux/notifier.h>
+#include <linux/memcontrol.h>
+#include <linux/mempolicy.h>
+#include <linux/security.h>
+#include <linux/ptrace.h>
+#include <linux/freezer.h>
+#include <linux/ftrace.h>
+#include <linux/ratelimit.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/oom.h>
+
+int sysctl_panic_on_oom;
+int sysctl_oom_kill_allocating_task;
+int sysctl_oom_dump_tasks = 1;
+
+DEFINE_MUTEX(oom_lock);
+
+#ifdef CONFIG_NUMA
+/**
+ * has_intersects_mems_allowed() - check task eligiblity for kill
+ * @start: task struct of which task to consider
+ * @mask: nodemask passed to page allocator for mempolicy ooms
+ *
+ * Task eligibility is determined by whether or not a candidate task, @tsk,
+ * shares the same mempolicy nodes as current if it is bound by such a policy
+ * and whether or not it has the same set of allowed cpuset nodes.
+ */
+static bool has_intersects_mems_allowed(struct task_struct *start,
+					const nodemask_t *mask)
+{
+	struct task_struct *tsk;
+	bool ret = false;
+
+	rcu_read_lock();
+	for_each_thread(start, tsk) {
+		if (mask) {
+			/*
+			 * If this is a mempolicy constrained oom, tsk's
+			 * cpuset is irrelevant.  Only return true if its
+			 * mempolicy intersects current, otherwise it may be
+			 * needlessly killed.
+			 */
+			ret = mempolicy_nodemask_intersects(tsk, mask);
+		} else {
+			/*
+			 * This is not a mempolicy constrained oom, so only
+			 * check the mems of tsk's cpuset.
+			 */
+			ret = cpuset_mems_allowed_intersects(current, tsk);
+		}
+		if (ret)
+			break;
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+#else
+static bool has_intersects_mems_allowed(struct task_struct *tsk,
+					const nodemask_t *mask)
+{
+	return true;
+}
+#endif /* CONFIG_NUMA */
+
+/*
+ * The process p may have detached its own ->mm while exiting or through
+ * use_mm(), but one or more of its subthreads may still have a valid
+ * pointer.  Return p, or any of its subthreads with a valid ->mm, with
+ * task_lock() held.
+ */
+struct task_struct *find_lock_task_mm(struct task_struct *p)
+{
+	struct task_struct *t;
+
+	rcu_read_lock();
+
+	for_each_thread(p, t) {
+		task_lock(t);
+		if (likely(t->mm))
+			goto found;
+		task_unlock(t);
+	}
+	t = NULL;
+found:
+	rcu_read_unlock();
+
+	return t;
+}
+
+/*
+ * order == -1 means the oom kill is required by sysrq, otherwise only
+ * for display purposes.
+ */
+static inline bool is_sysrq_oom(struct oom_control *oc)
+{
+	return oc->order == -1;
+}
+
+/* return true if the task is not adequate as candidate victim task. */
+static bool oom_unkillable_task(struct task_struct *p,
+		struct mem_cgroup *memcg, const nodemask_t *nodemask)
+{
+	if (is_global_init(p))
+		return true;
+	if (p->flags & PF_KTHREAD)
+		return true;
+
+	/* When mem_cgroup_out_of_memory() and p is not member of the group */
+	if (memcg && !task_in_mem_cgroup(p, memcg))
+		return true;
+
+	/* p may not have freeable memory in nodemask */
+	if (!has_intersects_mems_allowed(p, nodemask))
+		return true;
+
+	return false;
+}
+
+/**
+ * oom_badness - heuristic function to determine which candidate task to kill
+ * @p: task struct of which task we should calculate
+ * @totalpages: total present RAM allowed for page allocation
+ *
+ * The heuristic for determining which task to kill is made to be as simple and
+ * predictable as possible.  The goal is to return the highest value for the
+ * task consuming the most memory to avoid subsequent oom failures.
+ */
+unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
+			  const nodemask_t *nodemask, unsigned long totalpages)
+{
+	long points;
+	long adj;
+
+	if (oom_unkillable_task(p, memcg, nodemask))
+		return 0;
+
+	p = find_lock_task_mm(p);
+	if (!p)
+		return 0;
+
+	adj = (long)p->signal->oom_score_adj;
+	if (adj == OOM_SCORE_ADJ_MIN) {
+		task_unlock(p);
+		return 0;
+	}
+
+	/*
+	 * The baseline for the badness score is the proportion of RAM that each
+	 * task's rss, pagetable and swap space use.
+	 */
+	points = get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) +
+		atomic_long_read(&p->mm->nr_ptes) + mm_nr_pmds(p->mm);
+	task_unlock(p);
+
+	/*
+	 * Root processes get 3% bonus, just like the __vm_enough_memory()
+	 * implementation used by LSMs.
+	 */
+	if (has_capability_noaudit(p, CAP_SYS_ADMIN))
+		points -= (points * 3) / 100;
+
+	/* Normalize to oom_score_adj units */
+	adj *= totalpages / 1000;
+	points += adj;
+
+	/*
+	 * Never return 0 for an eligible task regardless of the root bonus and
+	 * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
+	 */
+	return points > 0 ? points : 1;
+}
+
+/*
+ * Determine the type of allocation constraint.
+ */
+#ifdef CONFIG_NUMA
+static enum oom_constraint constrained_alloc(struct oom_control *oc,
+					     unsigned long *totalpages)
+{
+	struct zone *zone;
+	struct zoneref *z;
+	enum zone_type high_zoneidx = gfp_zone(oc->gfp_mask);
+	bool cpuset_limited = false;
+	int nid;
+
+	/* Default to all available memory */
+	*totalpages = totalram_pages + total_swap_pages;
+
+	if (!oc->zonelist)
+		return CONSTRAINT_NONE;
+	/*
+	 * Reach here only when __GFP_NOFAIL is used. So, we should avoid
+	 * to kill current.We have to random task kill in this case.
+	 * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
+	 */
+	if (oc->gfp_mask & __GFP_THISNODE)
+		return CONSTRAINT_NONE;
+
+	/*
+	 * This is not a __GFP_THISNODE allocation, so a truncated nodemask in
+	 * the page allocator means a mempolicy is in effect.  Cpuset policy
+	 * is enforced in get_page_from_freelist().
+	 */
+	if (oc->nodemask &&
+	    !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
+		*totalpages = total_swap_pages;
+		for_each_node_mask(nid, *oc->nodemask)
+			*totalpages += node_spanned_pages(nid);
+		return CONSTRAINT_MEMORY_POLICY;
+	}
+
+	/* Check this allocation failure is caused by cpuset's wall function */
+	for_each_zone_zonelist_nodemask(zone, z, oc->zonelist,
+			high_zoneidx, oc->nodemask)
+		if (!cpuset_zone_allowed(zone, oc->gfp_mask))
+			cpuset_limited = true;
+
+	if (cpuset_limited) {
+		*totalpages = total_swap_pages;
+		for_each_node_mask(nid, cpuset_current_mems_allowed)
+			*totalpages += node_spanned_pages(nid);
+		return CONSTRAINT_CPUSET;
+	}
+	return CONSTRAINT_NONE;
+}
+#else
+static enum oom_constraint constrained_alloc(struct oom_control *oc,
+					     unsigned long *totalpages)
+{
+	*totalpages = totalram_pages + total_swap_pages;
+	return CONSTRAINT_NONE;
+}
+#endif
+
+enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
+			struct task_struct *task, unsigned long totalpages)
+{
+	if (oom_unkillable_task(task, NULL, oc->nodemask))
+		return OOM_SCAN_CONTINUE;
+
+	/*
+	 * This task already has access to memory reserves and is being killed.
+	 * Don't allow any other task to have access to the reserves.
+	 */
+	if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
+		if (!is_sysrq_oom(oc))
+			return OOM_SCAN_ABORT;
+	}
+	if (!task->mm)
+		return OOM_SCAN_CONTINUE;
+
+	/*
+	 * If task is allocating a lot of memory and has been marked to be
+	 * killed first if it triggers an oom, then select it.
+	 */
+	if (oom_task_origin(task))
+		return OOM_SCAN_SELECT;
+
+	if (task_will_free_mem(task) && !is_sysrq_oom(oc))
+		return OOM_SCAN_ABORT;
+
+	return OOM_SCAN_OK;
+}
+
+/*
+ * Simple selection loop. We chose the process with the highest
+ * number of 'points'.  Returns -1 on scan abort.
+ */
+static struct task_struct *select_bad_process(struct oom_control *oc,
+		unsigned int *ppoints, unsigned long totalpages)
+{
+	struct task_struct *g, *p;
+	struct task_struct *chosen = NULL;
+	unsigned long chosen_points = 0;
+
+	rcu_read_lock();
+	for_each_process_thread(g, p) {
+		unsigned int points;
+
+		switch (oom_scan_process_thread(oc, p, totalpages)) {
+		case OOM_SCAN_SELECT:
+			chosen = p;
+			chosen_points = ULONG_MAX;
+			/* fall through */
+		case OOM_SCAN_CONTINUE:
+			continue;
+		case OOM_SCAN_ABORT:
+			rcu_read_unlock();
+			return (struct task_struct *)(-1UL);
+		case OOM_SCAN_OK:
+			break;
+		};
+		points = oom_badness(p, NULL, oc->nodemask, totalpages);
+		if (!points || points < chosen_points)
+			continue;
+		/* Prefer thread group leaders for display purposes */
+		if (points == chosen_points && thread_group_leader(chosen))
+			continue;
+
+		chosen = p;
+		chosen_points = points;
+	}
+	if (chosen)
+		get_task_struct(chosen);
+	rcu_read_unlock();
+
+	*ppoints = chosen_points * 1000 / totalpages;
+	return chosen;
+}
+
+/**
+ * dump_tasks - dump current memory state of all system tasks
+ * @memcg: current's memory controller, if constrained
+ * @nodemask: nodemask passed to page allocator for mempolicy ooms
+ *
+ * Dumps the current memory state of all eligible tasks.  Tasks not in the same
+ * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
+ * are not shown.
+ * State information includes task's pid, uid, tgid, vm size, rss, nr_ptes,
+ * swapents, oom_score_adj value, and name.
+ */
+static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
+{
+	struct task_struct *p;
+	struct task_struct *task;
+
+	pr_info("[ pid ]   uid  tgid total_vm      rss nr_ptes nr_pmds swapents oom_score_adj name\n");
+	rcu_read_lock();
+	for_each_process(p) {
+		if (oom_unkillable_task(p, memcg, nodemask))
+			continue;
+
+		task = find_lock_task_mm(p);
+		if (!task) {
+			/*
+			 * This is a kthread or all of p's threads have already
+			 * detached their mm's.  There's no need to report
+			 * them; they can't be oom killed anyway.
+			 */
+			continue;
+		}
+
+		pr_info("[%5d] %5d %5d %8lu %8lu %7ld %7ld %8lu         %5hd %s\n",
+			task->pid, from_kuid(&init_user_ns, task_uid(task)),
+			task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
+			atomic_long_read(&task->mm->nr_ptes),
+			mm_nr_pmds(task->mm),
+			get_mm_counter(task->mm, MM_SWAPENTS),
+			task->signal->oom_score_adj, task->comm);
+		task_unlock(task);
+	}
+	rcu_read_unlock();
+}
+
+static void dump_header(struct oom_control *oc, struct task_struct *p,
+			struct mem_cgroup *memcg)
+{
+	pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
+		"oom_score_adj=%hd\n",
+		current->comm, oc->gfp_mask, oc->order,
+		current->signal->oom_score_adj);
+	cpuset_print_current_mems_allowed();
+	dump_stack();
+	if (memcg)
+		mem_cgroup_print_oom_info(memcg, p);
+	else
+		show_mem(SHOW_MEM_FILTER_NODES);
+	if (sysctl_oom_dump_tasks)
+		dump_tasks(memcg, oc->nodemask);
+}
+
+/*
+ * Number of OOM victims in flight
+ */
+static atomic_t oom_victims = ATOMIC_INIT(0);
+static DECLARE_WAIT_QUEUE_HEAD(oom_victims_wait);
+
+bool oom_killer_disabled __read_mostly;
+
+/**
+ * mark_oom_victim - mark the given task as OOM victim
+ * @tsk: task to mark
+ *
+ * Has to be called with oom_lock held and never after
+ * oom has been disabled already.
+ */
+void mark_oom_victim(struct task_struct *tsk)
+{
+	WARN_ON(oom_killer_disabled);
+	/* OOM killer might race with memcg OOM */
+	if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
+		return;
+	/*
+	 * Make sure that the task is woken up from uninterruptible sleep
+	 * if it is frozen because OOM killer wouldn't be able to free
+	 * any memory and livelock. freezing_slow_path will tell the freezer
+	 * that TIF_MEMDIE tasks should be ignored.
+	 */
+	__thaw_task(tsk);
+	atomic_inc(&oom_victims);
+}
+
+/**
+ * exit_oom_victim - note the exit of an OOM victim
+ */
+void exit_oom_victim(void)
+{
+	clear_thread_flag(TIF_MEMDIE);
+
+	if (!atomic_dec_return(&oom_victims))
+		wake_up_all(&oom_victims_wait);
+}
+
+/**
+ * oom_killer_disable - disable OOM killer
+ *
+ * Forces all page allocations to fail rather than trigger OOM killer.
+ * Will block and wait until all OOM victims are killed.
+ *
+ * The function cannot be called when there are runnable user tasks because
+ * the userspace would see unexpected allocation failures as a result. Any
+ * new usage of this function should be consulted with MM people.
+ *
+ * Returns true if successful and false if the OOM killer cannot be
+ * disabled.
+ */
+bool oom_killer_disable(void)
+{
+	/*
+	 * Make sure to not race with an ongoing OOM killer
+	 * and that the current is not the victim.
+	 */
+	mutex_lock(&oom_lock);
+	if (test_thread_flag(TIF_MEMDIE)) {
+		mutex_unlock(&oom_lock);
+		return false;
+	}
+
+	oom_killer_disabled = true;
+	mutex_unlock(&oom_lock);
+
+	wait_event(oom_victims_wait, !atomic_read(&oom_victims));
+
+	return true;
+}
+
+/**
+ * oom_killer_enable - enable OOM killer
+ */
+void oom_killer_enable(void)
+{
+	oom_killer_disabled = false;
+}
+
+/*
+ * task->mm can be NULL if the task is the exited group leader.  So to
+ * determine whether the task is using a particular mm, we examine all the
+ * task's threads: if one of those is using this mm then this task was also
+ * using it.
+ */
+static bool process_shares_mm(struct task_struct *p, struct mm_struct *mm)
+{
+	struct task_struct *t;
+
+	for_each_thread(p, t) {
+		struct mm_struct *t_mm = READ_ONCE(t->mm);
+		if (t_mm)
+			return t_mm == mm;
+	}
+	return false;
+}
+
+#define K(x) ((x) << (PAGE_SHIFT-10))
+/*
+ * Must be called while holding a reference to p, which will be released upon
+ * returning.
+ */
+void oom_kill_process(struct oom_control *oc, struct task_struct *p,
+		      unsigned int points, unsigned long totalpages,
+		      struct mem_cgroup *memcg, const char *message)
+{
+	struct task_struct *victim = p;
+	struct task_struct *child;
+	struct task_struct *t;
+	struct mm_struct *mm;
+	unsigned int victim_points = 0;
+	static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
+					      DEFAULT_RATELIMIT_BURST);
+
+	/*
+	 * If the task is already exiting, don't alarm the sysadmin or kill
+	 * its children or threads, just set TIF_MEMDIE so it can die quickly
+	 */
+	task_lock(p);
+	if (p->mm && task_will_free_mem(p)) {
+		mark_oom_victim(p);
+		task_unlock(p);
+		put_task_struct(p);
+		return;
+	}
+	task_unlock(p);
+
+	if (__ratelimit(&oom_rs))
+		dump_header(oc, p, memcg);
+
+	pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
+		message, task_pid_nr(p), p->comm, points);
+
+	/*
+	 * If any of p's children has a different mm and is eligible for kill,
+	 * the one with the highest oom_badness() score is sacrificed for its
+	 * parent.  This attempts to lose the minimal amount of work done while
+	 * still freeing memory.
+	 */
+	read_lock(&tasklist_lock);
+	for_each_thread(p, t) {
+		list_for_each_entry(child, &t->children, sibling) {
+			unsigned int child_points;
+
+			if (process_shares_mm(child, p->mm))
+				continue;
+			/*
+			 * oom_badness() returns 0 if the thread is unkillable
+			 */
+			child_points = oom_badness(child, memcg, oc->nodemask,
+								totalpages);
+			if (child_points > victim_points) {
+				put_task_struct(victim);
+				victim = child;
+				victim_points = child_points;
+				get_task_struct(victim);
+			}
+		}
+	}
+	read_unlock(&tasklist_lock);
+
+	p = find_lock_task_mm(victim);
+	if (!p) {
+		put_task_struct(victim);
+		return;
+	} else if (victim != p) {
+		get_task_struct(p);
+		put_task_struct(victim);
+		victim = p;
+	}
+
+	/* Get a reference to safely compare mm after task_unlock(victim) */
+	mm = victim->mm;
+	atomic_inc(&mm->mm_count);
+	/*
+	 * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
+	 * the OOM victim from depleting the memory reserves from the user
+	 * space under its control.
+	 */
+	do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
+	mark_oom_victim(victim);
+	pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+		task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
+		K(get_mm_counter(victim->mm, MM_ANONPAGES)),
+		K(get_mm_counter(victim->mm, MM_FILEPAGES)));
+	task_unlock(victim);
+
+	/*
+	 * Kill all user processes sharing victim->mm in other thread groups, if
+	 * any.  They don't get access to memory reserves, though, to avoid
+	 * depletion of all memory.  This prevents mm->mmap_sem livelock when an
+	 * oom killed thread cannot exit because it requires the semaphore and
+	 * its contended by another thread trying to allocate memory itself.
+	 * That thread will now get access to memory reserves since it has a
+	 * pending fatal signal.
+	 */
+	rcu_read_lock();
+	for_each_process(p) {
+		if (!process_shares_mm(p, mm))
+			continue;
+		if (same_thread_group(p, victim))
+			continue;
+		if (unlikely(p->flags & PF_KTHREAD))
+			continue;
+		if (is_global_init(p))
+			continue;
+		if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
+			continue;
+
+		do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
+	}
+	rcu_read_unlock();
+
+	mmdrop(mm);
+	put_task_struct(victim);
+}
+#undef K
+
+/*
+ * Determines whether the kernel must panic because of the panic_on_oom sysctl.
+ */
+void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint,
+			struct mem_cgroup *memcg)
+{
+	if (likely(!sysctl_panic_on_oom))
+		return;
+	if (sysctl_panic_on_oom != 2) {
+		/*
+		 * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
+		 * does not panic for cpuset, mempolicy, or memcg allocation
+		 * failures.
+		 */
+		if (constraint != CONSTRAINT_NONE)
+			return;
+	}
+	/* Do not panic for oom kills triggered by sysrq */
+	if (is_sysrq_oom(oc))
+		return;
+	dump_header(oc, NULL, memcg);
+	panic("Out of memory: %s panic_on_oom is enabled\n",
+		sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
+}
+
+static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
+
+int register_oom_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&oom_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(register_oom_notifier);
+
+int unregister_oom_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&oom_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_oom_notifier);
+
+/**
+ * out_of_memory - kill the "best" process when we run out of memory
+ * @oc: pointer to struct oom_control
+ *
+ * If we run out of memory, we have the choice between either
+ * killing a random task (bad), letting the system crash (worse)
+ * OR try to be smart about which process to kill. Note that we
+ * don't have to be perfect here, we just have to be good.
+ */
+bool out_of_memory(struct oom_control *oc)
+{
+	struct task_struct *p;
+	unsigned long totalpages;
+	unsigned long freed = 0;
+	unsigned int uninitialized_var(points);
+	enum oom_constraint constraint = CONSTRAINT_NONE;
+
+	if (oom_killer_disabled)
+		return false;
+
+	blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
+	if (freed > 0)
+		/* Got some memory back in the last second. */
+		return true;
+
+	/*
+	 * If current has a pending SIGKILL or is exiting, then automatically
+	 * select it.  The goal is to allow it to allocate so that it may
+	 * quickly exit and free its memory.
+	 *
+	 * But don't select if current has already released its mm and cleared
+	 * TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
+	 */
+	if (current->mm &&
+	    (fatal_signal_pending(current) || task_will_free_mem(current))) {
+		mark_oom_victim(current);
+		return true;
+	}
+
+	/*
+	 * Check if there were limitations on the allocation (only relevant for
+	 * NUMA) that may require different handling.
+	 */
+	constraint = constrained_alloc(oc, &totalpages);
+	if (constraint != CONSTRAINT_MEMORY_POLICY)
+		oc->nodemask = NULL;
+	check_panic_on_oom(oc, constraint, NULL);
+
+	if (sysctl_oom_kill_allocating_task && current->mm &&
+	    !oom_unkillable_task(current, NULL, oc->nodemask) &&
+	    current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
+		get_task_struct(current);
+		oom_kill_process(oc, current, 0, totalpages, NULL,
+				 "Out of memory (oom_kill_allocating_task)");
+		return true;
+	}
+
+	p = select_bad_process(oc, &points, totalpages);
+	/* Found nothing?!?! Either we hang forever, or we panic. */
+	if (!p && !is_sysrq_oom(oc)) {
+		dump_header(oc, NULL, NULL);
+		panic("Out of memory and no killable processes...\n");
+	}
+	if (p && p != (void *)-1UL) {
+		oom_kill_process(oc, p, points, totalpages, NULL,
+				 "Out of memory");
+		/*
+		 * Give the killed process a good chance to exit before trying
+		 * to allocate memory again.
+		 */
+		schedule_timeout_killable(1);
+	}
+	return true;
+}
+
+/*
+ * The pagefault handler calls here because it is out of memory, so kill a
+ * memory-hogging task.  If any populated zone has ZONE_OOM_LOCKED set, a
+ * parallel oom killing is already in progress so do nothing.
+ */
+void pagefault_out_of_memory(void)
+{
+	struct oom_control oc = {
+		.zonelist = NULL,
+		.nodemask = NULL,
+		.gfp_mask = 0,
+		.order = 0,
+	};
+
+	if (mem_cgroup_oom_synchronize(true))
+		return;
+
+	if (!mutex_trylock(&oom_lock))
+		return;
+
+	if (!out_of_memory(&oc)) {
+		/*
+		 * There shouldn't be any user tasks runnable while the
+		 * OOM killer is disabled, so the current task has to
+		 * be a racing OOM victim for which oom_killer_disable()
+		 * is waiting for.
+		 */
+		WARN_ON(test_thread_flag(TIF_MEMDIE));
+	}
+
+	mutex_unlock(&oom_lock);
+}
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
new file mode 100644
index 0000000..fd51ebf
--- /dev/null
+++ b/mm/page-writeback.c
@@ -0,0 +1,2822 @@
+/*
+ * mm/page-writeback.c
+ *
+ * Copyright (C) 2002, Linus Torvalds.
+ * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
+ *
+ * Contains functions related to writing back dirty pages at the
+ * address_space level.
+ *
+ * 10Apr2002	Andrew Morton
+ *		Initial version
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/init.h>
+#include <linux/backing-dev.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/blkdev.h>
+#include <linux/mpage.h>
+#include <linux/rmap.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/smp.h>
+#include <linux/sysctl.h>
+#include <linux/cpu.h>
+#include <linux/syscalls.h>
+#include <linux/buffer_head.h> /* __set_page_dirty_buffers */
+#include <linux/pagevec.h>
+#include <linux/timer.h>
+#include <linux/sched/rt.h>
+#include <linux/mm_inline.h>
+#include <trace/events/writeback.h>
+
+#include "internal.h"
+
+/*
+ * Sleep at most 200ms at a time in balance_dirty_pages().
+ */
+#define MAX_PAUSE		max(HZ/5, 1)
+
+/*
+ * Try to keep balance_dirty_pages() call intervals higher than this many pages
+ * by raising pause time to max_pause when falls below it.
+ */
+#define DIRTY_POLL_THRESH	(128 >> (PAGE_SHIFT - 10))
+
+/*
+ * Estimate write bandwidth at 200ms intervals.
+ */
+#define BANDWIDTH_INTERVAL	max(HZ/5, 1)
+
+#define RATELIMIT_CALC_SHIFT	10
+
+/*
+ * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
+ * will look to see if it needs to force writeback or throttling.
+ */
+static long ratelimit_pages = 32;
+
+/* The following parameters are exported via /proc/sys/vm */
+
+/*
+ * Start background writeback (via writeback threads) at this percentage
+ */
+int dirty_background_ratio = 10;
+
+/*
+ * dirty_background_bytes starts at 0 (disabled) so that it is a function of
+ * dirty_background_ratio * the amount of dirtyable memory
+ */
+unsigned long dirty_background_bytes;
+
+/*
+ * free highmem will not be subtracted from the total free memory
+ * for calculating free ratios if vm_highmem_is_dirtyable is true
+ */
+int vm_highmem_is_dirtyable;
+
+/*
+ * The generator of dirty data starts writeback at this percentage
+ */
+int vm_dirty_ratio = 20;
+
+/*
+ * vm_dirty_bytes starts at 0 (disabled) so that it is a function of
+ * vm_dirty_ratio * the amount of dirtyable memory
+ */
+unsigned long vm_dirty_bytes;
+
+/*
+ * The interval between `kupdate'-style writebacks
+ */
+unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */
+
+EXPORT_SYMBOL_GPL(dirty_writeback_interval);
+
+/*
+ * The longest time for which data is allowed to remain dirty
+ */
+unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */
+
+/*
+ * Flag that makes the machine dump writes/reads and block dirtyings.
+ */
+int block_dump;
+
+/*
+ * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies:
+ * a full sync is triggered after this time elapses without any disk activity.
+ */
+int laptop_mode;
+
+EXPORT_SYMBOL(laptop_mode);
+
+/* End of sysctl-exported parameters */
+
+struct wb_domain global_wb_domain;
+
+/* consolidated parameters for balance_dirty_pages() and its subroutines */
+struct dirty_throttle_control {
+#ifdef CONFIG_CGROUP_WRITEBACK
+	struct wb_domain	*dom;
+	struct dirty_throttle_control *gdtc;	/* only set in memcg dtc's */
+#endif
+	struct bdi_writeback	*wb;
+	struct fprop_local_percpu *wb_completions;
+
+	unsigned long		avail;		/* dirtyable */
+	unsigned long		dirty;		/* file_dirty + write + nfs */
+	unsigned long		thresh;		/* dirty threshold */
+	unsigned long		bg_thresh;	/* dirty background threshold */
+
+	unsigned long		wb_dirty;	/* per-wb counterparts */
+	unsigned long		wb_thresh;
+	unsigned long		wb_bg_thresh;
+
+	unsigned long		pos_ratio;
+};
+
+/*
+ * Length of period for aging writeout fractions of bdis. This is an
+ * arbitrarily chosen number. The longer the period, the slower fractions will
+ * reflect changes in current writeout rate.
+ */
+#define VM_COMPLETIONS_PERIOD_LEN (3*HZ)
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+#define GDTC_INIT(__wb)		.wb = (__wb),				\
+				.dom = &global_wb_domain,		\
+				.wb_completions = &(__wb)->completions
+
+#define GDTC_INIT_NO_WB		.dom = &global_wb_domain
+
+#define MDTC_INIT(__wb, __gdtc)	.wb = (__wb),				\
+				.dom = mem_cgroup_wb_domain(__wb),	\
+				.wb_completions = &(__wb)->memcg_completions, \
+				.gdtc = __gdtc
+
+static bool mdtc_valid(struct dirty_throttle_control *dtc)
+{
+	return dtc->dom;
+}
+
+static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc)
+{
+	return dtc->dom;
+}
+
+static struct dirty_throttle_control *mdtc_gdtc(struct dirty_throttle_control *mdtc)
+{
+	return mdtc->gdtc;
+}
+
+static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb)
+{
+	return &wb->memcg_completions;
+}
+
+static void wb_min_max_ratio(struct bdi_writeback *wb,
+			     unsigned long *minp, unsigned long *maxp)
+{
+	unsigned long this_bw = wb->avg_write_bandwidth;
+	unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth);
+	unsigned long long min = wb->bdi->min_ratio;
+	unsigned long long max = wb->bdi->max_ratio;
+
+	/*
+	 * @wb may already be clean by the time control reaches here and
+	 * the total may not include its bw.
+	 */
+	if (this_bw < tot_bw) {
+		if (min) {
+			min *= this_bw;
+			do_div(min, tot_bw);
+		}
+		if (max < 100) {
+			max *= this_bw;
+			do_div(max, tot_bw);
+		}
+	}
+
+	*minp = min;
+	*maxp = max;
+}
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+#define GDTC_INIT(__wb)		.wb = (__wb),                           \
+				.wb_completions = &(__wb)->completions
+#define GDTC_INIT_NO_WB
+#define MDTC_INIT(__wb, __gdtc)
+
+static bool mdtc_valid(struct dirty_throttle_control *dtc)
+{
+	return false;
+}
+
+static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc)
+{
+	return &global_wb_domain;
+}
+
+static struct dirty_throttle_control *mdtc_gdtc(struct dirty_throttle_control *mdtc)
+{
+	return NULL;
+}
+
+static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb)
+{
+	return NULL;
+}
+
+static void wb_min_max_ratio(struct bdi_writeback *wb,
+			     unsigned long *minp, unsigned long *maxp)
+{
+	*minp = wb->bdi->min_ratio;
+	*maxp = wb->bdi->max_ratio;
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+
+/*
+ * In a memory zone, there is a certain amount of pages we consider
+ * available for the page cache, which is essentially the number of
+ * free and reclaimable pages, minus some zone reserves to protect
+ * lowmem and the ability to uphold the zone's watermarks without
+ * requiring writeback.
+ *
+ * This number of dirtyable pages is the base value of which the
+ * user-configurable dirty ratio is the effictive number of pages that
+ * are allowed to be actually dirtied.  Per individual zone, or
+ * globally by using the sum of dirtyable pages over all zones.
+ *
+ * Because the user is allowed to specify the dirty limit globally as
+ * absolute number of bytes, calculating the per-zone dirty limit can
+ * require translating the configured limit into a percentage of
+ * global dirtyable memory first.
+ */
+
+/**
+ * zone_dirtyable_memory - number of dirtyable pages in a zone
+ * @zone: the zone
+ *
+ * Returns the zone's number of pages potentially available for dirty
+ * page cache.  This is the base value for the per-zone dirty limits.
+ */
+static unsigned long zone_dirtyable_memory(struct zone *zone)
+{
+	unsigned long nr_pages;
+
+	nr_pages = zone_page_state(zone, NR_FREE_PAGES);
+	nr_pages -= min(nr_pages, zone->dirty_balance_reserve);
+
+	nr_pages += zone_page_state(zone, NR_INACTIVE_FILE);
+	nr_pages += zone_page_state(zone, NR_ACTIVE_FILE);
+
+	return nr_pages;
+}
+
+static unsigned long highmem_dirtyable_memory(unsigned long total)
+{
+#ifdef CONFIG_HIGHMEM
+	int node;
+	unsigned long x = 0;
+
+	for_each_node_state(node, N_HIGH_MEMORY) {
+		struct zone *z = &NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
+
+		x += zone_dirtyable_memory(z);
+	}
+	/*
+	 * Unreclaimable memory (kernel memory or anonymous memory
+	 * without swap) can bring down the dirtyable pages below
+	 * the zone's dirty balance reserve and the above calculation
+	 * will underflow.  However we still want to add in nodes
+	 * which are below threshold (negative values) to get a more
+	 * accurate calculation but make sure that the total never
+	 * underflows.
+	 */
+	if ((long)x < 0)
+		x = 0;
+
+	/*
+	 * Make sure that the number of highmem pages is never larger
+	 * than the number of the total dirtyable memory. This can only
+	 * occur in very strange VM situations but we want to make sure
+	 * that this does not occur.
+	 */
+	return min(x, total);
+#else
+	return 0;
+#endif
+}
+
+/**
+ * global_dirtyable_memory - number of globally dirtyable pages
+ *
+ * Returns the global number of pages potentially available for dirty
+ * page cache.  This is the base value for the global dirty limits.
+ */
+static unsigned long global_dirtyable_memory(void)
+{
+	unsigned long x;
+
+	x = global_page_state(NR_FREE_PAGES);
+	x -= min(x, dirty_balance_reserve);
+
+	x += global_page_state(NR_INACTIVE_FILE);
+	x += global_page_state(NR_ACTIVE_FILE);
+
+	if (!vm_highmem_is_dirtyable)
+		x -= highmem_dirtyable_memory(x);
+
+	return x + 1;	/* Ensure that we never return 0 */
+}
+
+/**
+ * domain_dirty_limits - calculate thresh and bg_thresh for a wb_domain
+ * @dtc: dirty_throttle_control of interest
+ *
+ * Calculate @dtc->thresh and ->bg_thresh considering
+ * vm_dirty_{bytes|ratio} and dirty_background_{bytes|ratio}.  The caller
+ * must ensure that @dtc->avail is set before calling this function.  The
+ * dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and
+ * real-time tasks.
+ */
+static void domain_dirty_limits(struct dirty_throttle_control *dtc)
+{
+	const unsigned long available_memory = dtc->avail;
+	struct dirty_throttle_control *gdtc = mdtc_gdtc(dtc);
+	unsigned long bytes = vm_dirty_bytes;
+	unsigned long bg_bytes = dirty_background_bytes;
+	/* convert ratios to per-PAGE_SIZE for higher precision */
+	unsigned long ratio = (vm_dirty_ratio * PAGE_SIZE) / 100;
+	unsigned long bg_ratio = (dirty_background_ratio * PAGE_SIZE) / 100;
+	unsigned long thresh;
+	unsigned long bg_thresh;
+	struct task_struct *tsk;
+
+	/* gdtc is !NULL iff @dtc is for memcg domain */
+	if (gdtc) {
+		unsigned long global_avail = gdtc->avail;
+
+		/*
+		 * The byte settings can't be applied directly to memcg
+		 * domains.  Convert them to ratios by scaling against
+		 * globally available memory.  As the ratios are in
+		 * per-PAGE_SIZE, they can be obtained by dividing bytes by
+		 * number of pages.
+		 */
+		if (bytes)
+			ratio = min(DIV_ROUND_UP(bytes, global_avail),
+				    PAGE_SIZE);
+		if (bg_bytes)
+			bg_ratio = min(DIV_ROUND_UP(bg_bytes, global_avail),
+				       PAGE_SIZE);
+		bytes = bg_bytes = 0;
+	}
+
+	if (bytes)
+		thresh = DIV_ROUND_UP(bytes, PAGE_SIZE);
+	else
+		thresh = (ratio * available_memory) / PAGE_SIZE;
+
+	if (bg_bytes)
+		bg_thresh = DIV_ROUND_UP(bg_bytes, PAGE_SIZE);
+	else
+		bg_thresh = (bg_ratio * available_memory) / PAGE_SIZE;
+
+	if (bg_thresh >= thresh)
+		bg_thresh = thresh / 2;
+	tsk = current;
+	if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
+		bg_thresh += bg_thresh / 4;
+		thresh += thresh / 4;
+	}
+	dtc->thresh = thresh;
+	dtc->bg_thresh = bg_thresh;
+
+	/* we should eventually report the domain in the TP */
+	if (!gdtc)
+		trace_global_dirty_state(bg_thresh, thresh);
+}
+
+/**
+ * global_dirty_limits - background-writeback and dirty-throttling thresholds
+ * @pbackground: out parameter for bg_thresh
+ * @pdirty: out parameter for thresh
+ *
+ * Calculate bg_thresh and thresh for global_wb_domain.  See
+ * domain_dirty_limits() for details.
+ */
+void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
+{
+	struct dirty_throttle_control gdtc = { GDTC_INIT_NO_WB };
+
+	gdtc.avail = global_dirtyable_memory();
+	domain_dirty_limits(&gdtc);
+
+	*pbackground = gdtc.bg_thresh;
+	*pdirty = gdtc.thresh;
+}
+
+/**
+ * zone_dirty_limit - maximum number of dirty pages allowed in a zone
+ * @zone: the zone
+ *
+ * Returns the maximum number of dirty pages allowed in a zone, based
+ * on the zone's dirtyable memory.
+ */
+static unsigned long zone_dirty_limit(struct zone *zone)
+{
+	unsigned long zone_memory = zone_dirtyable_memory(zone);
+	struct task_struct *tsk = current;
+	unsigned long dirty;
+
+	if (vm_dirty_bytes)
+		dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE) *
+			zone_memory / global_dirtyable_memory();
+	else
+		dirty = vm_dirty_ratio * zone_memory / 100;
+
+	if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk))
+		dirty += dirty / 4;
+
+	return dirty;
+}
+
+/**
+ * zone_dirty_ok - tells whether a zone is within its dirty limits
+ * @zone: the zone to check
+ *
+ * Returns %true when the dirty pages in @zone are within the zone's
+ * dirty limit, %false if the limit is exceeded.
+ */
+bool zone_dirty_ok(struct zone *zone)
+{
+	unsigned long limit = zone_dirty_limit(zone);
+
+	return zone_page_state(zone, NR_FILE_DIRTY) +
+	       zone_page_state(zone, NR_UNSTABLE_NFS) +
+	       zone_page_state(zone, NR_WRITEBACK) <= limit;
+}
+
+int dirty_background_ratio_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp,
+		loff_t *ppos)
+{
+	int ret;
+
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret == 0 && write)
+		dirty_background_bytes = 0;
+	return ret;
+}
+
+int dirty_background_bytes_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp,
+		loff_t *ppos)
+{
+	int ret;
+
+	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret == 0 && write)
+		dirty_background_ratio = 0;
+	return ret;
+}
+
+int dirty_ratio_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp,
+		loff_t *ppos)
+{
+	int old_ratio = vm_dirty_ratio;
+	int ret;
+
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
+		writeback_set_ratelimit();
+		vm_dirty_bytes = 0;
+	}
+	return ret;
+}
+
+int dirty_bytes_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp,
+		loff_t *ppos)
+{
+	unsigned long old_bytes = vm_dirty_bytes;
+	int ret;
+
+	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret == 0 && write && vm_dirty_bytes != old_bytes) {
+		writeback_set_ratelimit();
+		vm_dirty_ratio = 0;
+	}
+	return ret;
+}
+
+static unsigned long wp_next_time(unsigned long cur_time)
+{
+	cur_time += VM_COMPLETIONS_PERIOD_LEN;
+	/* 0 has a special meaning... */
+	if (!cur_time)
+		return 1;
+	return cur_time;
+}
+
+static void wb_domain_writeout_inc(struct wb_domain *dom,
+				   struct fprop_local_percpu *completions,
+				   unsigned int max_prop_frac)
+{
+	__fprop_inc_percpu_max(&dom->completions, completions,
+			       max_prop_frac);
+	/* First event after period switching was turned off? */
+	if (!unlikely(dom->period_time)) {
+		/*
+		 * We can race with other __bdi_writeout_inc calls here but
+		 * it does not cause any harm since the resulting time when
+		 * timer will fire and what is in writeout_period_time will be
+		 * roughly the same.
+		 */
+		dom->period_time = wp_next_time(jiffies);
+		mod_timer(&dom->period_timer, dom->period_time);
+	}
+}
+
+/*
+ * Increment @wb's writeout completion count and the global writeout
+ * completion count. Called from test_clear_page_writeback().
+ */
+static inline void __wb_writeout_inc(struct bdi_writeback *wb)
+{
+	struct wb_domain *cgdom;
+
+	__inc_wb_stat(wb, WB_WRITTEN);
+	wb_domain_writeout_inc(&global_wb_domain, &wb->completions,
+			       wb->bdi->max_prop_frac);
+
+	cgdom = mem_cgroup_wb_domain(wb);
+	if (cgdom)
+		wb_domain_writeout_inc(cgdom, wb_memcg_completions(wb),
+				       wb->bdi->max_prop_frac);
+}
+
+void wb_writeout_inc(struct bdi_writeback *wb)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__wb_writeout_inc(wb);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(wb_writeout_inc);
+
+/*
+ * On idle system, we can be called long after we scheduled because we use
+ * deferred timers so count with missed periods.
+ */
+static void writeout_period(unsigned long t)
+{
+	struct wb_domain *dom = (void *)t;
+	int miss_periods = (jiffies - dom->period_time) /
+						 VM_COMPLETIONS_PERIOD_LEN;
+
+	if (fprop_new_period(&dom->completions, miss_periods + 1)) {
+		dom->period_time = wp_next_time(dom->period_time +
+				miss_periods * VM_COMPLETIONS_PERIOD_LEN);
+		mod_timer(&dom->period_timer, dom->period_time);
+	} else {
+		/*
+		 * Aging has zeroed all fractions. Stop wasting CPU on period
+		 * updates.
+		 */
+		dom->period_time = 0;
+	}
+}
+
+int wb_domain_init(struct wb_domain *dom, gfp_t gfp)
+{
+	memset(dom, 0, sizeof(*dom));
+
+	spin_lock_init(&dom->lock);
+
+	init_timer_deferrable(&dom->period_timer);
+	dom->period_timer.function = writeout_period;
+	dom->period_timer.data = (unsigned long)dom;
+
+	dom->dirty_limit_tstamp = jiffies;
+
+	return fprop_global_init(&dom->completions, gfp);
+}
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+void wb_domain_exit(struct wb_domain *dom)
+{
+	del_timer_sync(&dom->period_timer);
+	fprop_global_destroy(&dom->completions);
+}
+#endif
+
+/*
+ * bdi_min_ratio keeps the sum of the minimum dirty shares of all
+ * registered backing devices, which, for obvious reasons, can not
+ * exceed 100%.
+ */
+static unsigned int bdi_min_ratio;
+
+int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
+{
+	int ret = 0;
+
+	spin_lock_bh(&bdi_lock);
+	if (min_ratio > bdi->max_ratio) {
+		ret = -EINVAL;
+	} else {
+		min_ratio -= bdi->min_ratio;
+		if (bdi_min_ratio + min_ratio < 100) {
+			bdi_min_ratio += min_ratio;
+			bdi->min_ratio += min_ratio;
+		} else {
+			ret = -EINVAL;
+		}
+	}
+	spin_unlock_bh(&bdi_lock);
+
+	return ret;
+}
+
+int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
+{
+	int ret = 0;
+
+	if (max_ratio > 100)
+		return -EINVAL;
+
+	spin_lock_bh(&bdi_lock);
+	if (bdi->min_ratio > max_ratio) {
+		ret = -EINVAL;
+	} else {
+		bdi->max_ratio = max_ratio;
+		bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100;
+	}
+	spin_unlock_bh(&bdi_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(bdi_set_max_ratio);
+
+static unsigned long dirty_freerun_ceiling(unsigned long thresh,
+					   unsigned long bg_thresh)
+{
+	return (thresh + bg_thresh) / 2;
+}
+
+static unsigned long hard_dirty_limit(struct wb_domain *dom,
+				      unsigned long thresh)
+{
+	return max(thresh, dom->dirty_limit);
+}
+
+/*
+ * Memory which can be further allocated to a memcg domain is capped by
+ * system-wide clean memory excluding the amount being used in the domain.
+ */
+static void mdtc_calc_avail(struct dirty_throttle_control *mdtc,
+			    unsigned long filepages, unsigned long headroom)
+{
+	struct dirty_throttle_control *gdtc = mdtc_gdtc(mdtc);
+	unsigned long clean = filepages - min(filepages, mdtc->dirty);
+	unsigned long global_clean = gdtc->avail - min(gdtc->avail, gdtc->dirty);
+	unsigned long other_clean = global_clean - min(global_clean, clean);
+
+	mdtc->avail = filepages + min(headroom, other_clean);
+}
+
+/**
+ * __wb_calc_thresh - @wb's share of dirty throttling threshold
+ * @dtc: dirty_throttle_context of interest
+ *
+ * Returns @wb's dirty limit in pages. The term "dirty" in the context of
+ * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages.
+ *
+ * Note that balance_dirty_pages() will only seriously take it as a hard limit
+ * when sleeping max_pause per page is not enough to keep the dirty pages under
+ * control. For example, when the device is completely stalled due to some error
+ * conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key.
+ * In the other normal situations, it acts more gently by throttling the tasks
+ * more (rather than completely block them) when the wb dirty pages go high.
+ *
+ * It allocates high/low dirty limits to fast/slow devices, in order to prevent
+ * - starving fast devices
+ * - piling up dirty pages (that will take long time to sync) on slow devices
+ *
+ * The wb's share of dirty limit will be adapting to its throughput and
+ * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.
+ */
+static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc)
+{
+	struct wb_domain *dom = dtc_dom(dtc);
+	unsigned long thresh = dtc->thresh;
+	u64 wb_thresh;
+	long numerator, denominator;
+	unsigned long wb_min_ratio, wb_max_ratio;
+
+	/*
+	 * Calculate this BDI's share of the thresh ratio.
+	 */
+	fprop_fraction_percpu(&dom->completions, dtc->wb_completions,
+			      &numerator, &denominator);
+
+	wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100;
+	wb_thresh *= numerator;
+	do_div(wb_thresh, denominator);
+
+	wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio);
+
+	wb_thresh += (thresh * wb_min_ratio) / 100;
+	if (wb_thresh > (thresh * wb_max_ratio) / 100)
+		wb_thresh = thresh * wb_max_ratio / 100;
+
+	return wb_thresh;
+}
+
+unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh)
+{
+	struct dirty_throttle_control gdtc = { GDTC_INIT(wb),
+					       .thresh = thresh };
+	return __wb_calc_thresh(&gdtc);
+}
+
+/*
+ *                           setpoint - dirty 3
+ *        f(dirty) := 1.0 + (----------------)
+ *                           limit - setpoint
+ *
+ * it's a 3rd order polynomial that subjects to
+ *
+ * (1) f(freerun)  = 2.0 => rampup dirty_ratelimit reasonably fast
+ * (2) f(setpoint) = 1.0 => the balance point
+ * (3) f(limit)    = 0   => the hard limit
+ * (4) df/dx      <= 0	 => negative feedback control
+ * (5) the closer to setpoint, the smaller |df/dx| (and the reverse)
+ *     => fast response on large errors; small oscillation near setpoint
+ */
+static long long pos_ratio_polynom(unsigned long setpoint,
+					  unsigned long dirty,
+					  unsigned long limit)
+{
+	long long pos_ratio;
+	long x;
+
+	x = div64_s64(((s64)setpoint - (s64)dirty) << RATELIMIT_CALC_SHIFT,
+		      (limit - setpoint) | 1);
+	pos_ratio = x;
+	pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT;
+	pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT;
+	pos_ratio += 1 << RATELIMIT_CALC_SHIFT;
+
+	return clamp(pos_ratio, 0LL, 2LL << RATELIMIT_CALC_SHIFT);
+}
+
+/*
+ * Dirty position control.
+ *
+ * (o) global/bdi setpoints
+ *
+ * We want the dirty pages be balanced around the global/wb setpoints.
+ * When the number of dirty pages is higher/lower than the setpoint, the
+ * dirty position control ratio (and hence task dirty ratelimit) will be
+ * decreased/increased to bring the dirty pages back to the setpoint.
+ *
+ *     pos_ratio = 1 << RATELIMIT_CALC_SHIFT
+ *
+ *     if (dirty < setpoint) scale up   pos_ratio
+ *     if (dirty > setpoint) scale down pos_ratio
+ *
+ *     if (wb_dirty < wb_setpoint) scale up   pos_ratio
+ *     if (wb_dirty > wb_setpoint) scale down pos_ratio
+ *
+ *     task_ratelimit = dirty_ratelimit * pos_ratio >> RATELIMIT_CALC_SHIFT
+ *
+ * (o) global control line
+ *
+ *     ^ pos_ratio
+ *     |
+ *     |            |<===== global dirty control scope ======>|
+ * 2.0 .............*
+ *     |            .*
+ *     |            . *
+ *     |            .   *
+ *     |            .     *
+ *     |            .        *
+ *     |            .            *
+ * 1.0 ................................*
+ *     |            .                  .     *
+ *     |            .                  .          *
+ *     |            .                  .              *
+ *     |            .                  .                 *
+ *     |            .                  .                    *
+ *   0 +------------.------------------.----------------------*------------->
+ *           freerun^          setpoint^                 limit^   dirty pages
+ *
+ * (o) wb control line
+ *
+ *     ^ pos_ratio
+ *     |
+ *     |            *
+ *     |              *
+ *     |                *
+ *     |                  *
+ *     |                    * |<=========== span ============>|
+ * 1.0 .......................*
+ *     |                      . *
+ *     |                      .   *
+ *     |                      .     *
+ *     |                      .       *
+ *     |                      .         *
+ *     |                      .           *
+ *     |                      .             *
+ *     |                      .               *
+ *     |                      .                 *
+ *     |                      .                   *
+ *     |                      .                     *
+ * 1/4 ...............................................* * * * * * * * * * * *
+ *     |                      .                         .
+ *     |                      .                           .
+ *     |                      .                             .
+ *   0 +----------------------.-------------------------------.------------->
+ *                wb_setpoint^                    x_intercept^
+ *
+ * The wb control line won't drop below pos_ratio=1/4, so that wb_dirty can
+ * be smoothly throttled down to normal if it starts high in situations like
+ * - start writing to a slow SD card and a fast disk at the same time. The SD
+ *   card's wb_dirty may rush to many times higher than wb_setpoint.
+ * - the wb dirty thresh drops quickly due to change of JBOD workload
+ */
+static void wb_position_ratio(struct dirty_throttle_control *dtc)
+{
+	struct bdi_writeback *wb = dtc->wb;
+	unsigned long write_bw = wb->avg_write_bandwidth;
+	unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh);
+	unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh);
+	unsigned long wb_thresh = dtc->wb_thresh;
+	unsigned long x_intercept;
+	unsigned long setpoint;		/* dirty pages' target balance point */
+	unsigned long wb_setpoint;
+	unsigned long span;
+	long long pos_ratio;		/* for scaling up/down the rate limit */
+	long x;
+
+	dtc->pos_ratio = 0;
+
+	if (unlikely(dtc->dirty >= limit))
+		return;
+
+	/*
+	 * global setpoint
+	 *
+	 * See comment for pos_ratio_polynom().
+	 */
+	setpoint = (freerun + limit) / 2;
+	pos_ratio = pos_ratio_polynom(setpoint, dtc->dirty, limit);
+
+	/*
+	 * The strictlimit feature is a tool preventing mistrusted filesystems
+	 * from growing a large number of dirty pages before throttling. For
+	 * such filesystems balance_dirty_pages always checks wb counters
+	 * against wb limits. Even if global "nr_dirty" is under "freerun".
+	 * This is especially important for fuse which sets bdi->max_ratio to
+	 * 1% by default. Without strictlimit feature, fuse writeback may
+	 * consume arbitrary amount of RAM because it is accounted in
+	 * NR_WRITEBACK_TEMP which is not involved in calculating "nr_dirty".
+	 *
+	 * Here, in wb_position_ratio(), we calculate pos_ratio based on
+	 * two values: wb_dirty and wb_thresh. Let's consider an example:
+	 * total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global
+	 * limits are set by default to 10% and 20% (background and throttle).
+	 * Then wb_thresh is 1% of 20% of 16GB. This amounts to ~8K pages.
+	 * wb_calc_thresh(wb, bg_thresh) is about ~4K pages. wb_setpoint is
+	 * about ~6K pages (as the average of background and throttle wb
+	 * limits). The 3rd order polynomial will provide positive feedback if
+	 * wb_dirty is under wb_setpoint and vice versa.
+	 *
+	 * Note, that we cannot use global counters in these calculations
+	 * because we want to throttle process writing to a strictlimit wb
+	 * much earlier than global "freerun" is reached (~23MB vs. ~2.3GB
+	 * in the example above).
+	 */
+	if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
+		long long wb_pos_ratio;
+
+		if (dtc->wb_dirty < 8) {
+			dtc->pos_ratio = min_t(long long, pos_ratio * 2,
+					   2 << RATELIMIT_CALC_SHIFT);
+			return;
+		}
+
+		if (dtc->wb_dirty >= wb_thresh)
+			return;
+
+		wb_setpoint = dirty_freerun_ceiling(wb_thresh,
+						    dtc->wb_bg_thresh);
+
+		if (wb_setpoint == 0 || wb_setpoint == wb_thresh)
+			return;
+
+		wb_pos_ratio = pos_ratio_polynom(wb_setpoint, dtc->wb_dirty,
+						 wb_thresh);
+
+		/*
+		 * Typically, for strictlimit case, wb_setpoint << setpoint
+		 * and pos_ratio >> wb_pos_ratio. In the other words global
+		 * state ("dirty") is not limiting factor and we have to
+		 * make decision based on wb counters. But there is an
+		 * important case when global pos_ratio should get precedence:
+		 * global limits are exceeded (e.g. due to activities on other
+		 * wb's) while given strictlimit wb is below limit.
+		 *
+		 * "pos_ratio * wb_pos_ratio" would work for the case above,
+		 * but it would look too non-natural for the case of all
+		 * activity in the system coming from a single strictlimit wb
+		 * with bdi->max_ratio == 100%.
+		 *
+		 * Note that min() below somewhat changes the dynamics of the
+		 * control system. Normally, pos_ratio value can be well over 3
+		 * (when globally we are at freerun and wb is well below wb
+		 * setpoint). Now the maximum pos_ratio in the same situation
+		 * is 2. We might want to tweak this if we observe the control
+		 * system is too slow to adapt.
+		 */
+		dtc->pos_ratio = min(pos_ratio, wb_pos_ratio);
+		return;
+	}
+
+	/*
+	 * We have computed basic pos_ratio above based on global situation. If
+	 * the wb is over/under its share of dirty pages, we want to scale
+	 * pos_ratio further down/up. That is done by the following mechanism.
+	 */
+
+	/*
+	 * wb setpoint
+	 *
+	 *        f(wb_dirty) := 1.0 + k * (wb_dirty - wb_setpoint)
+	 *
+	 *                        x_intercept - wb_dirty
+	 *                     := --------------------------
+	 *                        x_intercept - wb_setpoint
+	 *
+	 * The main wb control line is a linear function that subjects to
+	 *
+	 * (1) f(wb_setpoint) = 1.0
+	 * (2) k = - 1 / (8 * write_bw)  (in single wb case)
+	 *     or equally: x_intercept = wb_setpoint + 8 * write_bw
+	 *
+	 * For single wb case, the dirty pages are observed to fluctuate
+	 * regularly within range
+	 *        [wb_setpoint - write_bw/2, wb_setpoint + write_bw/2]
+	 * for various filesystems, where (2) can yield in a reasonable 12.5%
+	 * fluctuation range for pos_ratio.
+	 *
+	 * For JBOD case, wb_thresh (not wb_dirty!) could fluctuate up to its
+	 * own size, so move the slope over accordingly and choose a slope that
+	 * yields 100% pos_ratio fluctuation on suddenly doubled wb_thresh.
+	 */
+	if (unlikely(wb_thresh > dtc->thresh))
+		wb_thresh = dtc->thresh;
+	/*
+	 * It's very possible that wb_thresh is close to 0 not because the
+	 * device is slow, but that it has remained inactive for long time.
+	 * Honour such devices a reasonable good (hopefully IO efficient)
+	 * threshold, so that the occasional writes won't be blocked and active
+	 * writes can rampup the threshold quickly.
+	 */
+	wb_thresh = max(wb_thresh, (limit - dtc->dirty) / 8);
+	/*
+	 * scale global setpoint to wb's:
+	 *	wb_setpoint = setpoint * wb_thresh / thresh
+	 */
+	x = div_u64((u64)wb_thresh << 16, dtc->thresh | 1);
+	wb_setpoint = setpoint * (u64)x >> 16;
+	/*
+	 * Use span=(8*write_bw) in single wb case as indicated by
+	 * (thresh - wb_thresh ~= 0) and transit to wb_thresh in JBOD case.
+	 *
+	 *        wb_thresh                    thresh - wb_thresh
+	 * span = --------- * (8 * write_bw) + ------------------ * wb_thresh
+	 *         thresh                           thresh
+	 */
+	span = (dtc->thresh - wb_thresh + 8 * write_bw) * (u64)x >> 16;
+	x_intercept = wb_setpoint + span;
+
+	if (dtc->wb_dirty < x_intercept - span / 4) {
+		pos_ratio = div64_u64(pos_ratio * (x_intercept - dtc->wb_dirty),
+				      (x_intercept - wb_setpoint) | 1);
+	} else
+		pos_ratio /= 4;
+
+	/*
+	 * wb reserve area, safeguard against dirty pool underrun and disk idle
+	 * It may push the desired control point of global dirty pages higher
+	 * than setpoint.
+	 */
+	x_intercept = wb_thresh / 2;
+	if (dtc->wb_dirty < x_intercept) {
+		if (dtc->wb_dirty > x_intercept / 8)
+			pos_ratio = div_u64(pos_ratio * x_intercept,
+					    dtc->wb_dirty);
+		else
+			pos_ratio *= 8;
+	}
+
+	dtc->pos_ratio = pos_ratio;
+}
+
+static void wb_update_write_bandwidth(struct bdi_writeback *wb,
+				      unsigned long elapsed,
+				      unsigned long written)
+{
+	const unsigned long period = roundup_pow_of_two(3 * HZ);
+	unsigned long avg = wb->avg_write_bandwidth;
+	unsigned long old = wb->write_bandwidth;
+	u64 bw;
+
+	/*
+	 * bw = written * HZ / elapsed
+	 *
+	 *                   bw * elapsed + write_bandwidth * (period - elapsed)
+	 * write_bandwidth = ---------------------------------------------------
+	 *                                          period
+	 *
+	 * @written may have decreased due to account_page_redirty().
+	 * Avoid underflowing @bw calculation.
+	 */
+	bw = written - min(written, wb->written_stamp);
+	bw *= HZ;
+	if (unlikely(elapsed > period)) {
+		do_div(bw, elapsed);
+		avg = bw;
+		goto out;
+	}
+	bw += (u64)wb->write_bandwidth * (period - elapsed);
+	bw >>= ilog2(period);
+
+	/*
+	 * one more level of smoothing, for filtering out sudden spikes
+	 */
+	if (avg > old && old >= (unsigned long)bw)
+		avg -= (avg - old) >> 3;
+
+	if (avg < old && old <= (unsigned long)bw)
+		avg += (old - avg) >> 3;
+
+out:
+	/* keep avg > 0 to guarantee that tot > 0 if there are dirty wbs */
+	avg = max(avg, 1LU);
+	if (wb_has_dirty_io(wb)) {
+		long delta = avg - wb->avg_write_bandwidth;
+		WARN_ON_ONCE(atomic_long_add_return(delta,
+					&wb->bdi->tot_write_bandwidth) <= 0);
+	}
+	wb->write_bandwidth = bw;
+	wb->avg_write_bandwidth = avg;
+}
+
+static void update_dirty_limit(struct dirty_throttle_control *dtc)
+{
+	struct wb_domain *dom = dtc_dom(dtc);
+	unsigned long thresh = dtc->thresh;
+	unsigned long limit = dom->dirty_limit;
+
+	/*
+	 * Follow up in one step.
+	 */
+	if (limit < thresh) {
+		limit = thresh;
+		goto update;
+	}
+
+	/*
+	 * Follow down slowly. Use the higher one as the target, because thresh
+	 * may drop below dirty. This is exactly the reason to introduce
+	 * dom->dirty_limit which is guaranteed to lie above the dirty pages.
+	 */
+	thresh = max(thresh, dtc->dirty);
+	if (limit > thresh) {
+		limit -= (limit - thresh) >> 5;
+		goto update;
+	}
+	return;
+update:
+	dom->dirty_limit = limit;
+}
+
+static void domain_update_bandwidth(struct dirty_throttle_control *dtc,
+				    unsigned long now)
+{
+	struct wb_domain *dom = dtc_dom(dtc);
+
+	/*
+	 * check locklessly first to optimize away locking for the most time
+	 */
+	if (time_before(now, dom->dirty_limit_tstamp + BANDWIDTH_INTERVAL))
+		return;
+
+	spin_lock(&dom->lock);
+	if (time_after_eq(now, dom->dirty_limit_tstamp + BANDWIDTH_INTERVAL)) {
+		update_dirty_limit(dtc);
+		dom->dirty_limit_tstamp = now;
+	}
+	spin_unlock(&dom->lock);
+}
+
+/*
+ * Maintain wb->dirty_ratelimit, the base dirty throttle rate.
+ *
+ * Normal wb tasks will be curbed at or below it in long term.
+ * Obviously it should be around (write_bw / N) when there are N dd tasks.
+ */
+static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc,
+				      unsigned long dirtied,
+				      unsigned long elapsed)
+{
+	struct bdi_writeback *wb = dtc->wb;
+	unsigned long dirty = dtc->dirty;
+	unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh);
+	unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh);
+	unsigned long setpoint = (freerun + limit) / 2;
+	unsigned long write_bw = wb->avg_write_bandwidth;
+	unsigned long dirty_ratelimit = wb->dirty_ratelimit;
+	unsigned long dirty_rate;
+	unsigned long task_ratelimit;
+	unsigned long balanced_dirty_ratelimit;
+	unsigned long step;
+	unsigned long x;
+
+	/*
+	 * The dirty rate will match the writeout rate in long term, except
+	 * when dirty pages are truncated by userspace or re-dirtied by FS.
+	 */
+	dirty_rate = (dirtied - wb->dirtied_stamp) * HZ / elapsed;
+
+	/*
+	 * task_ratelimit reflects each dd's dirty rate for the past 200ms.
+	 */
+	task_ratelimit = (u64)dirty_ratelimit *
+					dtc->pos_ratio >> RATELIMIT_CALC_SHIFT;
+	task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */
+
+	/*
+	 * A linear estimation of the "balanced" throttle rate. The theory is,
+	 * if there are N dd tasks, each throttled at task_ratelimit, the wb's
+	 * dirty_rate will be measured to be (N * task_ratelimit). So the below
+	 * formula will yield the balanced rate limit (write_bw / N).
+	 *
+	 * Note that the expanded form is not a pure rate feedback:
+	 *	rate_(i+1) = rate_(i) * (write_bw / dirty_rate)		     (1)
+	 * but also takes pos_ratio into account:
+	 *	rate_(i+1) = rate_(i) * (write_bw / dirty_rate) * pos_ratio  (2)
+	 *
+	 * (1) is not realistic because pos_ratio also takes part in balancing
+	 * the dirty rate.  Consider the state
+	 *	pos_ratio = 0.5						     (3)
+	 *	rate = 2 * (write_bw / N)				     (4)
+	 * If (1) is used, it will stuck in that state! Because each dd will
+	 * be throttled at
+	 *	task_ratelimit = pos_ratio * rate = (write_bw / N)	     (5)
+	 * yielding
+	 *	dirty_rate = N * task_ratelimit = write_bw		     (6)
+	 * put (6) into (1) we get
+	 *	rate_(i+1) = rate_(i)					     (7)
+	 *
+	 * So we end up using (2) to always keep
+	 *	rate_(i+1) ~= (write_bw / N)				     (8)
+	 * regardless of the value of pos_ratio. As long as (8) is satisfied,
+	 * pos_ratio is able to drive itself to 1.0, which is not only where
+	 * the dirty count meet the setpoint, but also where the slope of
+	 * pos_ratio is most flat and hence task_ratelimit is least fluctuated.
+	 */
+	balanced_dirty_ratelimit = div_u64((u64)task_ratelimit * write_bw,
+					   dirty_rate | 1);
+	/*
+	 * balanced_dirty_ratelimit ~= (write_bw / N) <= write_bw
+	 */
+	if (unlikely(balanced_dirty_ratelimit > write_bw))
+		balanced_dirty_ratelimit = write_bw;
+
+	/*
+	 * We could safely do this and return immediately:
+	 *
+	 *	wb->dirty_ratelimit = balanced_dirty_ratelimit;
+	 *
+	 * However to get a more stable dirty_ratelimit, the below elaborated
+	 * code makes use of task_ratelimit to filter out singular points and
+	 * limit the step size.
+	 *
+	 * The below code essentially only uses the relative value of
+	 *
+	 *	task_ratelimit - dirty_ratelimit
+	 *	= (pos_ratio - 1) * dirty_ratelimit
+	 *
+	 * which reflects the direction and size of dirty position error.
+	 */
+
+	/*
+	 * dirty_ratelimit will follow balanced_dirty_ratelimit iff
+	 * task_ratelimit is on the same side of dirty_ratelimit, too.
+	 * For example, when
+	 * - dirty_ratelimit > balanced_dirty_ratelimit
+	 * - dirty_ratelimit > task_ratelimit (dirty pages are above setpoint)
+	 * lowering dirty_ratelimit will help meet both the position and rate
+	 * control targets. Otherwise, don't update dirty_ratelimit if it will
+	 * only help meet the rate target. After all, what the users ultimately
+	 * feel and care are stable dirty rate and small position error.
+	 *
+	 * |task_ratelimit - dirty_ratelimit| is used to limit the step size
+	 * and filter out the singular points of balanced_dirty_ratelimit. Which
+	 * keeps jumping around randomly and can even leap far away at times
+	 * due to the small 200ms estimation period of dirty_rate (we want to
+	 * keep that period small to reduce time lags).
+	 */
+	step = 0;
+
+	/*
+	 * For strictlimit case, calculations above were based on wb counters
+	 * and limits (starting from pos_ratio = wb_position_ratio() and up to
+	 * balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate).
+	 * Hence, to calculate "step" properly, we have to use wb_dirty as
+	 * "dirty" and wb_setpoint as "setpoint".
+	 *
+	 * We rampup dirty_ratelimit forcibly if wb_dirty is low because
+	 * it's possible that wb_thresh is close to zero due to inactivity
+	 * of backing device.
+	 */
+	if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
+		dirty = dtc->wb_dirty;
+		if (dtc->wb_dirty < 8)
+			setpoint = dtc->wb_dirty + 1;
+		else
+			setpoint = (dtc->wb_thresh + dtc->wb_bg_thresh) / 2;
+	}
+
+	if (dirty < setpoint) {
+		x = min3(wb->balanced_dirty_ratelimit,
+			 balanced_dirty_ratelimit, task_ratelimit);
+		if (dirty_ratelimit < x)
+			step = x - dirty_ratelimit;
+	} else {
+		x = max3(wb->balanced_dirty_ratelimit,
+			 balanced_dirty_ratelimit, task_ratelimit);
+		if (dirty_ratelimit > x)
+			step = dirty_ratelimit - x;
+	}
+
+	/*
+	 * Don't pursue 100% rate matching. It's impossible since the balanced
+	 * rate itself is constantly fluctuating. So decrease the track speed
+	 * when it gets close to the target. Helps eliminate pointless tremors.
+	 */
+	step >>= dirty_ratelimit / (2 * step + 1);
+	/*
+	 * Limit the tracking speed to avoid overshooting.
+	 */
+	step = (step + 7) / 8;
+
+	if (dirty_ratelimit < balanced_dirty_ratelimit)
+		dirty_ratelimit += step;
+	else
+		dirty_ratelimit -= step;
+
+	wb->dirty_ratelimit = max(dirty_ratelimit, 1UL);
+	wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit;
+
+	trace_bdi_dirty_ratelimit(wb, dirty_rate, task_ratelimit);
+}
+
+static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc,
+				  struct dirty_throttle_control *mdtc,
+				  unsigned long start_time,
+				  bool update_ratelimit)
+{
+	struct bdi_writeback *wb = gdtc->wb;
+	unsigned long now = jiffies;
+	unsigned long elapsed = now - wb->bw_time_stamp;
+	unsigned long dirtied;
+	unsigned long written;
+
+	lockdep_assert_held(&wb->list_lock);
+
+	/*
+	 * rate-limit, only update once every 200ms.
+	 */
+	if (elapsed < BANDWIDTH_INTERVAL)
+		return;
+
+	dirtied = percpu_counter_read(&wb->stat[WB_DIRTIED]);
+	written = percpu_counter_read(&wb->stat[WB_WRITTEN]);
+
+	/*
+	 * Skip quiet periods when disk bandwidth is under-utilized.
+	 * (at least 1s idle time between two flusher runs)
+	 */
+	if (elapsed > HZ && time_before(wb->bw_time_stamp, start_time))
+		goto snapshot;
+
+	if (update_ratelimit) {
+		domain_update_bandwidth(gdtc, now);
+		wb_update_dirty_ratelimit(gdtc, dirtied, elapsed);
+
+		/*
+		 * @mdtc is always NULL if !CGROUP_WRITEBACK but the
+		 * compiler has no way to figure that out.  Help it.
+		 */
+		if (IS_ENABLED(CONFIG_CGROUP_WRITEBACK) && mdtc) {
+			domain_update_bandwidth(mdtc, now);
+			wb_update_dirty_ratelimit(mdtc, dirtied, elapsed);
+		}
+	}
+	wb_update_write_bandwidth(wb, elapsed, written);
+
+snapshot:
+	wb->dirtied_stamp = dirtied;
+	wb->written_stamp = written;
+	wb->bw_time_stamp = now;
+}
+
+void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time)
+{
+	struct dirty_throttle_control gdtc = { GDTC_INIT(wb) };
+
+	__wb_update_bandwidth(&gdtc, NULL, start_time, false);
+}
+
+/*
+ * After a task dirtied this many pages, balance_dirty_pages_ratelimited()
+ * will look to see if it needs to start dirty throttling.
+ *
+ * If dirty_poll_interval is too low, big NUMA machines will call the expensive
+ * global_page_state() too often. So scale it near-sqrt to the safety margin
+ * (the number of pages we may dirty without exceeding the dirty limits).
+ */
+static unsigned long dirty_poll_interval(unsigned long dirty,
+					 unsigned long thresh)
+{
+	if (thresh > dirty)
+		return 1UL << (ilog2(thresh - dirty) >> 1);
+
+	return 1;
+}
+
+static unsigned long wb_max_pause(struct bdi_writeback *wb,
+				  unsigned long wb_dirty)
+{
+	unsigned long bw = wb->avg_write_bandwidth;
+	unsigned long t;
+
+	/*
+	 * Limit pause time for small memory systems. If sleeping for too long
+	 * time, a small pool of dirty/writeback pages may go empty and disk go
+	 * idle.
+	 *
+	 * 8 serves as the safety ratio.
+	 */
+	t = wb_dirty / (1 + bw / roundup_pow_of_two(1 + HZ / 8));
+	t++;
+
+	return min_t(unsigned long, t, MAX_PAUSE);
+}
+
+static long wb_min_pause(struct bdi_writeback *wb,
+			 long max_pause,
+			 unsigned long task_ratelimit,
+			 unsigned long dirty_ratelimit,
+			 int *nr_dirtied_pause)
+{
+	long hi = ilog2(wb->avg_write_bandwidth);
+	long lo = ilog2(wb->dirty_ratelimit);
+	long t;		/* target pause */
+	long pause;	/* estimated next pause */
+	int pages;	/* target nr_dirtied_pause */
+
+	/* target for 10ms pause on 1-dd case */
+	t = max(1, HZ / 100);
+
+	/*
+	 * Scale up pause time for concurrent dirtiers in order to reduce CPU
+	 * overheads.
+	 *
+	 * (N * 10ms) on 2^N concurrent tasks.
+	 */
+	if (hi > lo)
+		t += (hi - lo) * (10 * HZ) / 1024;
+
+	/*
+	 * This is a bit convoluted. We try to base the next nr_dirtied_pause
+	 * on the much more stable dirty_ratelimit. However the next pause time
+	 * will be computed based on task_ratelimit and the two rate limits may
+	 * depart considerably at some time. Especially if task_ratelimit goes
+	 * below dirty_ratelimit/2 and the target pause is max_pause, the next
+	 * pause time will be max_pause*2 _trimmed down_ to max_pause.  As a
+	 * result task_ratelimit won't be executed faithfully, which could
+	 * eventually bring down dirty_ratelimit.
+	 *
+	 * We apply two rules to fix it up:
+	 * 1) try to estimate the next pause time and if necessary, use a lower
+	 *    nr_dirtied_pause so as not to exceed max_pause. When this happens,
+	 *    nr_dirtied_pause will be "dancing" with task_ratelimit.
+	 * 2) limit the target pause time to max_pause/2, so that the normal
+	 *    small fluctuations of task_ratelimit won't trigger rule (1) and
+	 *    nr_dirtied_pause will remain as stable as dirty_ratelimit.
+	 */
+	t = min(t, 1 + max_pause / 2);
+	pages = dirty_ratelimit * t / roundup_pow_of_two(HZ);
+
+	/*
+	 * Tiny nr_dirtied_pause is found to hurt I/O performance in the test
+	 * case fio-mmap-randwrite-64k, which does 16*{sync read, async write}.
+	 * When the 16 consecutive reads are often interrupted by some dirty
+	 * throttling pause during the async writes, cfq will go into idles
+	 * (deadline is fine). So push nr_dirtied_pause as high as possible
+	 * until reaches DIRTY_POLL_THRESH=32 pages.
+	 */
+	if (pages < DIRTY_POLL_THRESH) {
+		t = max_pause;
+		pages = dirty_ratelimit * t / roundup_pow_of_two(HZ);
+		if (pages > DIRTY_POLL_THRESH) {
+			pages = DIRTY_POLL_THRESH;
+			t = HZ * DIRTY_POLL_THRESH / dirty_ratelimit;
+		}
+	}
+
+	pause = HZ * pages / (task_ratelimit + 1);
+	if (pause > max_pause) {
+		t = max_pause;
+		pages = task_ratelimit * t / roundup_pow_of_two(HZ);
+	}
+
+	*nr_dirtied_pause = pages;
+	/*
+	 * The minimal pause time will normally be half the target pause time.
+	 */
+	return pages >= DIRTY_POLL_THRESH ? 1 + t / 2 : t;
+}
+
+static inline void wb_dirty_limits(struct dirty_throttle_control *dtc)
+{
+	struct bdi_writeback *wb = dtc->wb;
+	unsigned long wb_reclaimable;
+
+	/*
+	 * wb_thresh is not treated as some limiting factor as
+	 * dirty_thresh, due to reasons
+	 * - in JBOD setup, wb_thresh can fluctuate a lot
+	 * - in a system with HDD and USB key, the USB key may somehow
+	 *   go into state (wb_dirty >> wb_thresh) either because
+	 *   wb_dirty starts high, or because wb_thresh drops low.
+	 *   In this case we don't want to hard throttle the USB key
+	 *   dirtiers for 100 seconds until wb_dirty drops under
+	 *   wb_thresh. Instead the auxiliary wb control line in
+	 *   wb_position_ratio() will let the dirtier task progress
+	 *   at some rate <= (write_bw / 2) for bringing down wb_dirty.
+	 */
+	dtc->wb_thresh = __wb_calc_thresh(dtc);
+	dtc->wb_bg_thresh = dtc->thresh ?
+		div_u64((u64)dtc->wb_thresh * dtc->bg_thresh, dtc->thresh) : 0;
+
+	/*
+	 * In order to avoid the stacked BDI deadlock we need
+	 * to ensure we accurately count the 'dirty' pages when
+	 * the threshold is low.
+	 *
+	 * Otherwise it would be possible to get thresh+n pages
+	 * reported dirty, even though there are thresh-m pages
+	 * actually dirty; with m+n sitting in the percpu
+	 * deltas.
+	 */
+	if (dtc->wb_thresh < 2 * wb_stat_error(wb)) {
+		wb_reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE);
+		dtc->wb_dirty = wb_reclaimable + wb_stat_sum(wb, WB_WRITEBACK);
+	} else {
+		wb_reclaimable = wb_stat(wb, WB_RECLAIMABLE);
+		dtc->wb_dirty = wb_reclaimable + wb_stat(wb, WB_WRITEBACK);
+	}
+}
+
+/*
+ * balance_dirty_pages() must be called by processes which are generating dirty
+ * data.  It looks at the number of dirty pages in the machine and will force
+ * the caller to wait once crossing the (background_thresh + dirty_thresh) / 2.
+ * If we're over `background_thresh' then the writeback threads are woken to
+ * perform some writeout.
+ */
+static void balance_dirty_pages(struct address_space *mapping,
+				struct bdi_writeback *wb,
+				unsigned long pages_dirtied)
+{
+	struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) };
+	struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) };
+	struct dirty_throttle_control * const gdtc = &gdtc_stor;
+	struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ?
+						     &mdtc_stor : NULL;
+	struct dirty_throttle_control *sdtc;
+	unsigned long nr_reclaimable;	/* = file_dirty + unstable_nfs */
+	long period;
+	long pause;
+	long max_pause;
+	long min_pause;
+	int nr_dirtied_pause;
+	bool dirty_exceeded = false;
+	unsigned long task_ratelimit;
+	unsigned long dirty_ratelimit;
+	struct backing_dev_info *bdi = wb->bdi;
+	bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT;
+	unsigned long start_time = jiffies;
+
+	for (;;) {
+		unsigned long now = jiffies;
+		unsigned long dirty, thresh, bg_thresh;
+		unsigned long m_dirty = 0;	/* stop bogus uninit warnings */
+		unsigned long m_thresh = 0;
+		unsigned long m_bg_thresh = 0;
+
+		/*
+		 * Unstable writes are a feature of certain networked
+		 * filesystems (i.e. NFS) in which data may have been
+		 * written to the server's write cache, but has not yet
+		 * been flushed to permanent storage.
+		 */
+		nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
+					global_page_state(NR_UNSTABLE_NFS);
+		gdtc->avail = global_dirtyable_memory();
+		gdtc->dirty = nr_reclaimable + global_page_state(NR_WRITEBACK);
+
+		domain_dirty_limits(gdtc);
+
+		if (unlikely(strictlimit)) {
+			wb_dirty_limits(gdtc);
+
+			dirty = gdtc->wb_dirty;
+			thresh = gdtc->wb_thresh;
+			bg_thresh = gdtc->wb_bg_thresh;
+		} else {
+			dirty = gdtc->dirty;
+			thresh = gdtc->thresh;
+			bg_thresh = gdtc->bg_thresh;
+		}
+
+		if (mdtc) {
+			unsigned long filepages, headroom, writeback;
+
+			/*
+			 * If @wb belongs to !root memcg, repeat the same
+			 * basic calculations for the memcg domain.
+			 */
+			mem_cgroup_wb_stats(wb, &filepages, &headroom,
+					    &mdtc->dirty, &writeback);
+			mdtc->dirty += writeback;
+			mdtc_calc_avail(mdtc, filepages, headroom);
+
+			domain_dirty_limits(mdtc);
+
+			if (unlikely(strictlimit)) {
+				wb_dirty_limits(mdtc);
+				m_dirty = mdtc->wb_dirty;
+				m_thresh = mdtc->wb_thresh;
+				m_bg_thresh = mdtc->wb_bg_thresh;
+			} else {
+				m_dirty = mdtc->dirty;
+				m_thresh = mdtc->thresh;
+				m_bg_thresh = mdtc->bg_thresh;
+			}
+		}
+
+		/*
+		 * Throttle it only when the background writeback cannot
+		 * catch-up. This avoids (excessively) small writeouts
+		 * when the wb limits are ramping up in case of !strictlimit.
+		 *
+		 * In strictlimit case make decision based on the wb counters
+		 * and limits. Small writeouts when the wb limits are ramping
+		 * up are the price we consciously pay for strictlimit-ing.
+		 *
+		 * If memcg domain is in effect, @dirty should be under
+		 * both global and memcg freerun ceilings.
+		 */
+		if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh) &&
+		    (!mdtc ||
+		     m_dirty <= dirty_freerun_ceiling(m_thresh, m_bg_thresh))) {
+			unsigned long intv = dirty_poll_interval(dirty, thresh);
+			unsigned long m_intv = ULONG_MAX;
+
+			current->dirty_paused_when = now;
+			current->nr_dirtied = 0;
+			if (mdtc)
+				m_intv = dirty_poll_interval(m_dirty, m_thresh);
+			current->nr_dirtied_pause = min(intv, m_intv);
+			break;
+		}
+
+		if (unlikely(!writeback_in_progress(wb)))
+			wb_start_background_writeback(wb);
+
+		/*
+		 * Calculate global domain's pos_ratio and select the
+		 * global dtc by default.
+		 */
+		if (!strictlimit)
+			wb_dirty_limits(gdtc);
+
+		dirty_exceeded = (gdtc->wb_dirty > gdtc->wb_thresh) &&
+			((gdtc->dirty > gdtc->thresh) || strictlimit);
+
+		wb_position_ratio(gdtc);
+		sdtc = gdtc;
+
+		if (mdtc) {
+			/*
+			 * If memcg domain is in effect, calculate its
+			 * pos_ratio.  @wb should satisfy constraints from
+			 * both global and memcg domains.  Choose the one
+			 * w/ lower pos_ratio.
+			 */
+			if (!strictlimit)
+				wb_dirty_limits(mdtc);
+
+			dirty_exceeded |= (mdtc->wb_dirty > mdtc->wb_thresh) &&
+				((mdtc->dirty > mdtc->thresh) || strictlimit);
+
+			wb_position_ratio(mdtc);
+			if (mdtc->pos_ratio < gdtc->pos_ratio)
+				sdtc = mdtc;
+		}
+
+		if (dirty_exceeded && !wb->dirty_exceeded)
+			wb->dirty_exceeded = 1;
+
+		if (time_is_before_jiffies(wb->bw_time_stamp +
+					   BANDWIDTH_INTERVAL)) {
+			spin_lock(&wb->list_lock);
+			__wb_update_bandwidth(gdtc, mdtc, start_time, true);
+			spin_unlock(&wb->list_lock);
+		}
+
+		/* throttle according to the chosen dtc */
+		dirty_ratelimit = wb->dirty_ratelimit;
+		task_ratelimit = ((u64)dirty_ratelimit * sdtc->pos_ratio) >>
+							RATELIMIT_CALC_SHIFT;
+		max_pause = wb_max_pause(wb, sdtc->wb_dirty);
+		min_pause = wb_min_pause(wb, max_pause,
+					 task_ratelimit, dirty_ratelimit,
+					 &nr_dirtied_pause);
+
+		if (unlikely(task_ratelimit == 0)) {
+			period = max_pause;
+			pause = max_pause;
+			goto pause;
+		}
+		period = HZ * pages_dirtied / task_ratelimit;
+		pause = period;
+		if (current->dirty_paused_when)
+			pause -= now - current->dirty_paused_when;
+		/*
+		 * For less than 1s think time (ext3/4 may block the dirtier
+		 * for up to 800ms from time to time on 1-HDD; so does xfs,
+		 * however at much less frequency), try to compensate it in
+		 * future periods by updating the virtual time; otherwise just
+		 * do a reset, as it may be a light dirtier.
+		 */
+		if (pause < min_pause) {
+			trace_balance_dirty_pages(wb,
+						  sdtc->thresh,
+						  sdtc->bg_thresh,
+						  sdtc->dirty,
+						  sdtc->wb_thresh,
+						  sdtc->wb_dirty,
+						  dirty_ratelimit,
+						  task_ratelimit,
+						  pages_dirtied,
+						  period,
+						  min(pause, 0L),
+						  start_time);
+			if (pause < -HZ) {
+				current->dirty_paused_when = now;
+				current->nr_dirtied = 0;
+			} else if (period) {
+				current->dirty_paused_when += period;
+				current->nr_dirtied = 0;
+			} else if (current->nr_dirtied_pause <= pages_dirtied)
+				current->nr_dirtied_pause += pages_dirtied;
+			break;
+		}
+		if (unlikely(pause > max_pause)) {
+			/* for occasional dropped task_ratelimit */
+			now += min(pause - max_pause, max_pause);
+			pause = max_pause;
+		}
+
+pause:
+		trace_balance_dirty_pages(wb,
+					  sdtc->thresh,
+					  sdtc->bg_thresh,
+					  sdtc->dirty,
+					  sdtc->wb_thresh,
+					  sdtc->wb_dirty,
+					  dirty_ratelimit,
+					  task_ratelimit,
+					  pages_dirtied,
+					  period,
+					  pause,
+					  start_time);
+		__set_current_state(TASK_KILLABLE);
+		io_schedule_timeout(pause);
+
+		current->dirty_paused_when = now + pause;
+		current->nr_dirtied = 0;
+		current->nr_dirtied_pause = nr_dirtied_pause;
+
+		/*
+		 * This is typically equal to (dirty < thresh) and can also
+		 * keep "1000+ dd on a slow USB stick" under control.
+		 */
+		if (task_ratelimit)
+			break;
+
+		/*
+		 * In the case of an unresponding NFS server and the NFS dirty
+		 * pages exceeds dirty_thresh, give the other good wb's a pipe
+		 * to go through, so that tasks on them still remain responsive.
+		 *
+		 * In theory 1 page is enough to keep the comsumer-producer
+		 * pipe going: the flusher cleans 1 page => the task dirties 1
+		 * more page. However wb_dirty has accounting errors.  So use
+		 * the larger and more IO friendly wb_stat_error.
+		 */
+		if (sdtc->wb_dirty <= wb_stat_error(wb))
+			break;
+
+		if (fatal_signal_pending(current))
+			break;
+	}
+
+	if (!dirty_exceeded && wb->dirty_exceeded)
+		wb->dirty_exceeded = 0;
+
+	if (writeback_in_progress(wb))
+		return;
+
+	/*
+	 * In laptop mode, we wait until hitting the higher threshold before
+	 * starting background writeout, and then write out all the way down
+	 * to the lower threshold.  So slow writers cause minimal disk activity.
+	 *
+	 * In normal mode, we start background writeout at the lower
+	 * background_thresh, to keep the amount of dirty memory low.
+	 */
+	if (laptop_mode)
+		return;
+
+	if (nr_reclaimable > gdtc->bg_thresh)
+		wb_start_background_writeback(wb);
+}
+
+static DEFINE_PER_CPU(int, bdp_ratelimits);
+
+/*
+ * Normal tasks are throttled by
+ *	loop {
+ *		dirty tsk->nr_dirtied_pause pages;
+ *		take a snap in balance_dirty_pages();
+ *	}
+ * However there is a worst case. If every task exit immediately when dirtied
+ * (tsk->nr_dirtied_pause - 1) pages, balance_dirty_pages() will never be
+ * called to throttle the page dirties. The solution is to save the not yet
+ * throttled page dirties in dirty_throttle_leaks on task exit and charge them
+ * randomly into the running tasks. This works well for the above worst case,
+ * as the new task will pick up and accumulate the old task's leaked dirty
+ * count and eventually get throttled.
+ */
+DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0;
+
+/**
+ * balance_dirty_pages_ratelimited - balance dirty memory state
+ * @mapping: address_space which was dirtied
+ *
+ * Processes which are dirtying memory should call in here once for each page
+ * which was newly dirtied.  The function will periodically check the system's
+ * dirty state and will initiate writeback if needed.
+ *
+ * On really big machines, get_writeback_state is expensive, so try to avoid
+ * calling it too often (ratelimiting).  But once we're over the dirty memory
+ * limit we decrease the ratelimiting by a lot, to prevent individual processes
+ * from overshooting the limit by (ratelimit_pages) each.
+ */
+void balance_dirty_pages_ratelimited(struct address_space *mapping)
+{
+	struct inode *inode = mapping->host;
+	struct backing_dev_info *bdi = inode_to_bdi(inode);
+	struct bdi_writeback *wb = NULL;
+	int ratelimit;
+	int *p;
+
+	if (!bdi_cap_account_dirty(bdi))
+		return;
+
+	if (inode_cgwb_enabled(inode))
+		wb = wb_get_create_current(bdi, GFP_KERNEL);
+	if (!wb)
+		wb = &bdi->wb;
+
+	ratelimit = current->nr_dirtied_pause;
+	if (wb->dirty_exceeded)
+		ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10));
+
+	preempt_disable();
+	/*
+	 * This prevents one CPU to accumulate too many dirtied pages without
+	 * calling into balance_dirty_pages(), which can happen when there are
+	 * 1000+ tasks, all of them start dirtying pages at exactly the same
+	 * time, hence all honoured too large initial task->nr_dirtied_pause.
+	 */
+	p =  this_cpu_ptr(&bdp_ratelimits);
+	if (unlikely(current->nr_dirtied >= ratelimit))
+		*p = 0;
+	else if (unlikely(*p >= ratelimit_pages)) {
+		*p = 0;
+		ratelimit = 0;
+	}
+	/*
+	 * Pick up the dirtied pages by the exited tasks. This avoids lots of
+	 * short-lived tasks (eg. gcc invocations in a kernel build) escaping
+	 * the dirty throttling and livelock other long-run dirtiers.
+	 */
+	p = this_cpu_ptr(&dirty_throttle_leaks);
+	if (*p > 0 && current->nr_dirtied < ratelimit) {
+		unsigned long nr_pages_dirtied;
+		nr_pages_dirtied = min(*p, ratelimit - current->nr_dirtied);
+		*p -= nr_pages_dirtied;
+		current->nr_dirtied += nr_pages_dirtied;
+	}
+	preempt_enable();
+
+	if (unlikely(current->nr_dirtied >= ratelimit))
+		balance_dirty_pages(mapping, wb, current->nr_dirtied);
+
+	wb_put(wb);
+}
+EXPORT_SYMBOL(balance_dirty_pages_ratelimited);
+
+/**
+ * wb_over_bg_thresh - does @wb need to be written back?
+ * @wb: bdi_writeback of interest
+ *
+ * Determines whether background writeback should keep writing @wb or it's
+ * clean enough.  Returns %true if writeback should continue.
+ */
+bool wb_over_bg_thresh(struct bdi_writeback *wb)
+{
+	struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) };
+	struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) };
+	struct dirty_throttle_control * const gdtc = &gdtc_stor;
+	struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ?
+						     &mdtc_stor : NULL;
+
+	/*
+	 * Similar to balance_dirty_pages() but ignores pages being written
+	 * as we're trying to decide whether to put more under writeback.
+	 */
+	gdtc->avail = global_dirtyable_memory();
+	gdtc->dirty = global_page_state(NR_FILE_DIRTY) +
+		      global_page_state(NR_UNSTABLE_NFS);
+	domain_dirty_limits(gdtc);
+
+	if (gdtc->dirty > gdtc->bg_thresh)
+		return true;
+
+	if (wb_stat(wb, WB_RECLAIMABLE) >
+	    wb_calc_thresh(gdtc->wb, gdtc->bg_thresh))
+		return true;
+
+	if (mdtc) {
+		unsigned long filepages, headroom, writeback;
+
+		mem_cgroup_wb_stats(wb, &filepages, &headroom, &mdtc->dirty,
+				    &writeback);
+		mdtc_calc_avail(mdtc, filepages, headroom);
+		domain_dirty_limits(mdtc);	/* ditto, ignore writeback */
+
+		if (mdtc->dirty > mdtc->bg_thresh)
+			return true;
+
+		if (wb_stat(wb, WB_RECLAIMABLE) >
+		    wb_calc_thresh(mdtc->wb, mdtc->bg_thresh))
+			return true;
+	}
+
+	return false;
+}
+
+void throttle_vm_writeout(gfp_t gfp_mask)
+{
+	unsigned long background_thresh;
+	unsigned long dirty_thresh;
+
+        for ( ; ; ) {
+		global_dirty_limits(&background_thresh, &dirty_thresh);
+		dirty_thresh = hard_dirty_limit(&global_wb_domain, dirty_thresh);
+
+                /*
+                 * Boost the allowable dirty threshold a bit for page
+                 * allocators so they don't get DoS'ed by heavy writers
+                 */
+                dirty_thresh += dirty_thresh / 10;      /* wheeee... */
+
+                if (global_page_state(NR_UNSTABLE_NFS) +
+			global_page_state(NR_WRITEBACK) <= dirty_thresh)
+                        	break;
+                congestion_wait(BLK_RW_ASYNC, HZ/10);
+
+		/*
+		 * The caller might hold locks which can prevent IO completion
+		 * or progress in the filesystem.  So we cannot just sit here
+		 * waiting for IO to complete.
+		 */
+		if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO))
+			break;
+        }
+}
+
+/*
+ * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
+ */
+int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
+	void __user *buffer, size_t *length, loff_t *ppos)
+{
+	proc_dointvec(table, write, buffer, length, ppos);
+	return 0;
+}
+
+#ifdef CONFIG_BLOCK
+void laptop_mode_timer_fn(unsigned long data)
+{
+	struct request_queue *q = (struct request_queue *)data;
+	int nr_pages = global_page_state(NR_FILE_DIRTY) +
+		global_page_state(NR_UNSTABLE_NFS);
+	struct bdi_writeback *wb;
+
+	/*
+	 * We want to write everything out, not just down to the dirty
+	 * threshold
+	 */
+	if (!bdi_has_dirty_io(&q->backing_dev_info))
+		return;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(wb, &q->backing_dev_info.wb_list, bdi_node)
+		if (wb_has_dirty_io(wb))
+			wb_start_writeback(wb, nr_pages, true,
+					   WB_REASON_LAPTOP_TIMER);
+	rcu_read_unlock();
+}
+
+/*
+ * We've spun up the disk and we're in laptop mode: schedule writeback
+ * of all dirty data a few seconds from now.  If the flush is already scheduled
+ * then push it back - the user is still using the disk.
+ */
+void laptop_io_completion(struct backing_dev_info *info)
+{
+	mod_timer(&info->laptop_mode_wb_timer, jiffies + laptop_mode);
+}
+
+/*
+ * We're in laptop mode and we've just synced. The sync's writes will have
+ * caused another writeback to be scheduled by laptop_io_completion.
+ * Nothing needs to be written back anymore, so we unschedule the writeback.
+ */
+void laptop_sync_completion(void)
+{
+	struct backing_dev_info *bdi;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
+		del_timer(&bdi->laptop_mode_wb_timer);
+
+	rcu_read_unlock();
+}
+#endif
+
+/*
+ * If ratelimit_pages is too high then we can get into dirty-data overload
+ * if a large number of processes all perform writes at the same time.
+ * If it is too low then SMP machines will call the (expensive)
+ * get_writeback_state too often.
+ *
+ * Here we set ratelimit_pages to a level which ensures that when all CPUs are
+ * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory
+ * thresholds.
+ */
+
+void writeback_set_ratelimit(void)
+{
+	struct wb_domain *dom = &global_wb_domain;
+	unsigned long background_thresh;
+	unsigned long dirty_thresh;
+
+	global_dirty_limits(&background_thresh, &dirty_thresh);
+	dom->dirty_limit = dirty_thresh;
+	ratelimit_pages = dirty_thresh / (num_online_cpus() * 32);
+	if (ratelimit_pages < 16)
+		ratelimit_pages = 16;
+}
+
+static int
+ratelimit_handler(struct notifier_block *self, unsigned long action,
+		  void *hcpu)
+{
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_ONLINE:
+	case CPU_DEAD:
+		writeback_set_ratelimit();
+		return NOTIFY_OK;
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static struct notifier_block ratelimit_nb = {
+	.notifier_call	= ratelimit_handler,
+	.next		= NULL,
+};
+
+/*
+ * Called early on to tune the page writeback dirty limits.
+ *
+ * We used to scale dirty pages according to how total memory
+ * related to pages that could be allocated for buffers (by
+ * comparing nr_free_buffer_pages() to vm_total_pages.
+ *
+ * However, that was when we used "dirty_ratio" to scale with
+ * all memory, and we don't do that any more. "dirty_ratio"
+ * is now applied to total non-HIGHPAGE memory (by subtracting
+ * totalhigh_pages from vm_total_pages), and as such we can't
+ * get into the old insane situation any more where we had
+ * large amounts of dirty pages compared to a small amount of
+ * non-HIGHMEM memory.
+ *
+ * But we might still want to scale the dirty_ratio by how
+ * much memory the box has..
+ */
+void __init page_writeback_init(void)
+{
+	BUG_ON(wb_domain_init(&global_wb_domain, GFP_KERNEL));
+
+	writeback_set_ratelimit();
+	register_cpu_notifier(&ratelimit_nb);
+}
+
+/**
+ * tag_pages_for_writeback - tag pages to be written by write_cache_pages
+ * @mapping: address space structure to write
+ * @start: starting page index
+ * @end: ending page index (inclusive)
+ *
+ * This function scans the page range from @start to @end (inclusive) and tags
+ * all pages that have DIRTY tag set with a special TOWRITE tag. The idea is
+ * that write_cache_pages (or whoever calls this function) will then use
+ * TOWRITE tag to identify pages eligible for writeback.  This mechanism is
+ * used to avoid livelocking of writeback by a process steadily creating new
+ * dirty pages in the file (thus it is important for this function to be quick
+ * so that it can tag pages faster than a dirtying process can create them).
+ */
+/*
+ * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce tree_lock latency.
+ */
+void tag_pages_for_writeback(struct address_space *mapping,
+			     pgoff_t start, pgoff_t end)
+{
+#define WRITEBACK_TAG_BATCH 4096
+	unsigned long tagged;
+
+	do {
+		spin_lock_irq(&mapping->tree_lock);
+		tagged = radix_tree_range_tag_if_tagged(&mapping->page_tree,
+				&start, end, WRITEBACK_TAG_BATCH,
+				PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE);
+		spin_unlock_irq(&mapping->tree_lock);
+		WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH);
+		cond_resched();
+		/* We check 'start' to handle wrapping when end == ~0UL */
+	} while (tagged >= WRITEBACK_TAG_BATCH && start);
+}
+EXPORT_SYMBOL(tag_pages_for_writeback);
+
+/**
+ * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
+ * @mapping: address space structure to write
+ * @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ * @writepage: function called for each page
+ * @data: data passed to writepage function
+ *
+ * If a page is already under I/O, write_cache_pages() skips it, even
+ * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
+ * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
+ * and msync() need to guarantee that all the data which was dirty at the time
+ * the call was made get new I/O started against them.  If wbc->sync_mode is
+ * WB_SYNC_ALL then we were called for data integrity and we must wait for
+ * existing IO to complete.
+ *
+ * To avoid livelocks (when other process dirties new pages), we first tag
+ * pages which should be written back with TOWRITE tag and only then start
+ * writing them. For data-integrity sync we have to be careful so that we do
+ * not miss some pages (e.g., because some other process has cleared TOWRITE
+ * tag we set). The rule we follow is that TOWRITE tag can be cleared only
+ * by the process clearing the DIRTY tag (and submitting the page for IO).
+ */
+int write_cache_pages(struct address_space *mapping,
+		      struct writeback_control *wbc, writepage_t writepage,
+		      void *data)
+{
+	int ret = 0;
+	int done = 0;
+	struct pagevec pvec;
+	int nr_pages;
+	pgoff_t uninitialized_var(writeback_index);
+	pgoff_t index;
+	pgoff_t end;		/* Inclusive */
+	pgoff_t done_index;
+	int cycled;
+	int range_whole = 0;
+	int tag;
+
+	pagevec_init(&pvec, 0);
+	if (wbc->range_cyclic) {
+		writeback_index = mapping->writeback_index; /* prev offset */
+		index = writeback_index;
+		if (index == 0)
+			cycled = 1;
+		else
+			cycled = 0;
+		end = -1;
+	} else {
+		index = wbc->range_start >> PAGE_CACHE_SHIFT;
+		end = wbc->range_end >> PAGE_CACHE_SHIFT;
+		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+			range_whole = 1;
+		cycled = 1; /* ignore range_cyclic tests */
+	}
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag = PAGECACHE_TAG_TOWRITE;
+	else
+		tag = PAGECACHE_TAG_DIRTY;
+retry:
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag_pages_for_writeback(mapping, index, end);
+	done_index = index;
+	while (!done && (index <= end)) {
+		int i;
+
+		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
+			      min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
+		if (nr_pages == 0)
+			break;
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			/*
+			 * At this point, the page may be truncated or
+			 * invalidated (changing page->mapping to NULL), or
+			 * even swizzled back from swapper_space to tmpfs file
+			 * mapping. However, page->index will not change
+			 * because we have a reference on the page.
+			 */
+			if (page->index > end) {
+				/*
+				 * can't be range_cyclic (1st pass) because
+				 * end == -1 in that case.
+				 */
+				done = 1;
+				break;
+			}
+
+			done_index = page->index;
+
+			lock_page(page);
+
+			/*
+			 * Page truncated or invalidated. We can freely skip it
+			 * then, even for data integrity operations: the page
+			 * has disappeared concurrently, so there could be no
+			 * real expectation of this data interity operation
+			 * even if there is now a new, dirty page at the same
+			 * pagecache address.
+			 */
+			if (unlikely(page->mapping != mapping)) {
+continue_unlock:
+				unlock_page(page);
+				continue;
+			}
+
+			if (!PageDirty(page)) {
+				/* someone wrote it for us */
+				goto continue_unlock;
+			}
+
+			if (PageWriteback(page)) {
+				if (wbc->sync_mode != WB_SYNC_NONE)
+					wait_on_page_writeback(page);
+				else
+					goto continue_unlock;
+			}
+
+			BUG_ON(PageWriteback(page));
+			if (!clear_page_dirty_for_io(page))
+				goto continue_unlock;
+
+			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
+			ret = (*writepage)(page, wbc, data);
+			if (unlikely(ret)) {
+				if (ret == AOP_WRITEPAGE_ACTIVATE) {
+					unlock_page(page);
+					ret = 0;
+				} else {
+					/*
+					 * done_index is set past this page,
+					 * so media errors will not choke
+					 * background writeout for the entire
+					 * file. This has consequences for
+					 * range_cyclic semantics (ie. it may
+					 * not be suitable for data integrity
+					 * writeout).
+					 */
+					done_index = page->index + 1;
+					done = 1;
+					break;
+				}
+			}
+
+			/*
+			 * We stop writing back only if we are not doing
+			 * integrity sync. In case of integrity sync we have to
+			 * keep going until we have written all the pages
+			 * we tagged for writeback prior to entering this loop.
+			 */
+			if (--wbc->nr_to_write <= 0 &&
+			    wbc->sync_mode == WB_SYNC_NONE) {
+				done = 1;
+				break;
+			}
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+	if (!cycled && !done) {
+		/*
+		 * range_cyclic:
+		 * We hit the last page and there is more work to be done: wrap
+		 * back to the start of the file
+		 */
+		cycled = 1;
+		index = 0;
+		end = writeback_index - 1;
+		goto retry;
+	}
+	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+		mapping->writeback_index = done_index;
+
+	return ret;
+}
+EXPORT_SYMBOL(write_cache_pages);
+
+/*
+ * Function used by generic_writepages to call the real writepage
+ * function and set the mapping flags on error
+ */
+static int __writepage(struct page *page, struct writeback_control *wbc,
+		       void *data)
+{
+	struct address_space *mapping = data;
+	int ret = mapping->a_ops->writepage(page, wbc);
+	mapping_set_error(mapping, ret);
+	return ret;
+}
+
+/**
+ * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
+ * @mapping: address space structure to write
+ * @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ *
+ * This is a library function, which implements the writepages()
+ * address_space_operation.
+ */
+int generic_writepages(struct address_space *mapping,
+		       struct writeback_control *wbc)
+{
+	struct blk_plug plug;
+	int ret;
+
+	/* deal with chardevs and other special file */
+	if (!mapping->a_ops->writepage)
+		return 0;
+
+	blk_start_plug(&plug);
+	ret = write_cache_pages(mapping, wbc, __writepage, mapping);
+	blk_finish_plug(&plug);
+	return ret;
+}
+
+EXPORT_SYMBOL(generic_writepages);
+
+int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+	int ret;
+
+	if (wbc->nr_to_write <= 0)
+		return 0;
+	if (mapping->a_ops->writepages)
+		ret = mapping->a_ops->writepages(mapping, wbc);
+	else
+		ret = generic_writepages(mapping, wbc);
+	return ret;
+}
+
+/**
+ * write_one_page - write out a single page and optionally wait on I/O
+ * @page: the page to write
+ * @wait: if true, wait on writeout
+ *
+ * The page must be locked by the caller and will be unlocked upon return.
+ *
+ * write_one_page() returns a negative error code if I/O failed.
+ */
+int write_one_page(struct page *page, int wait)
+{
+	struct address_space *mapping = page->mapping;
+	int ret = 0;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = 1,
+	};
+
+	BUG_ON(!PageLocked(page));
+
+	if (wait)
+		wait_on_page_writeback(page);
+
+	if (clear_page_dirty_for_io(page)) {
+		page_cache_get(page);
+		ret = mapping->a_ops->writepage(page, &wbc);
+		if (ret == 0 && wait) {
+			wait_on_page_writeback(page);
+			if (PageError(page))
+				ret = -EIO;
+		}
+		page_cache_release(page);
+	} else {
+		unlock_page(page);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(write_one_page);
+
+/*
+ * For address_spaces which do not use buffers nor write back.
+ */
+int __set_page_dirty_no_writeback(struct page *page)
+{
+	if (!PageDirty(page))
+		return !TestSetPageDirty(page);
+	return 0;
+}
+
+/*
+ * Helper function for set_page_dirty family.
+ *
+ * Caller must hold mem_cgroup_begin_page_stat().
+ *
+ * NOTE: This relies on being atomic wrt interrupts.
+ */
+void account_page_dirtied(struct page *page, struct address_space *mapping,
+			  struct mem_cgroup *memcg)
+{
+	struct inode *inode = mapping->host;
+
+	trace_writeback_dirty_page(page, mapping);
+
+	if (mapping_cap_account_dirty(mapping)) {
+		struct bdi_writeback *wb;
+
+		inode_attach_wb(inode, page);
+		wb = inode_to_wb(inode);
+
+		mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
+		__inc_zone_page_state(page, NR_FILE_DIRTY);
+		__inc_zone_page_state(page, NR_DIRTIED);
+		__inc_wb_stat(wb, WB_RECLAIMABLE);
+		__inc_wb_stat(wb, WB_DIRTIED);
+		task_io_account_write(PAGE_CACHE_SIZE);
+		current->nr_dirtied++;
+		this_cpu_inc(bdp_ratelimits);
+	}
+}
+EXPORT_SYMBOL(account_page_dirtied);
+
+/*
+ * Helper function for deaccounting dirty page without writeback.
+ *
+ * Caller must hold mem_cgroup_begin_page_stat().
+ */
+void account_page_cleaned(struct page *page, struct address_space *mapping,
+			  struct mem_cgroup *memcg, struct bdi_writeback *wb)
+{
+	if (mapping_cap_account_dirty(mapping)) {
+		mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
+		dec_zone_page_state(page, NR_FILE_DIRTY);
+		dec_wb_stat(wb, WB_RECLAIMABLE);
+		task_io_account_cancelled_write(PAGE_CACHE_SIZE);
+	}
+}
+
+/*
+ * For address_spaces which do not use buffers.  Just tag the page as dirty in
+ * its radix tree.
+ *
+ * This is also used when a single buffer is being dirtied: we want to set the
+ * page dirty in that case, but not all the buffers.  This is a "bottom-up"
+ * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying.
+ *
+ * The caller must ensure this doesn't race with truncation.  Most will simply
+ * hold the page lock, but e.g. zap_pte_range() calls with the page mapped and
+ * the pte lock held, which also locks out truncation.
+ */
+int __set_page_dirty_nobuffers(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	if (!TestSetPageDirty(page)) {
+		struct address_space *mapping = page_mapping(page);
+		unsigned long flags;
+
+		if (!mapping) {
+			mem_cgroup_end_page_stat(memcg);
+			return 1;
+		}
+
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		BUG_ON(page_mapping(page) != mapping);
+		WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
+		account_page_dirtied(page, mapping, memcg);
+		radix_tree_tag_set(&mapping->page_tree, page_index(page),
+				   PAGECACHE_TAG_DIRTY);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		mem_cgroup_end_page_stat(memcg);
+
+		if (mapping->host) {
+			/* !PageAnon && !swapper_space */
+			__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+		}
+		return 1;
+	}
+	mem_cgroup_end_page_stat(memcg);
+	return 0;
+}
+EXPORT_SYMBOL(__set_page_dirty_nobuffers);
+
+/*
+ * Call this whenever redirtying a page, to de-account the dirty counters
+ * (NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied), so that they match the written
+ * counters (NR_WRITTEN, BDI_WRITTEN) in long term. The mismatches will lead to
+ * systematic errors in balanced_dirty_ratelimit and the dirty pages position
+ * control.
+ */
+void account_page_redirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+
+	if (mapping && mapping_cap_account_dirty(mapping)) {
+		struct inode *inode = mapping->host;
+		struct bdi_writeback *wb;
+		bool locked;
+
+		wb = unlocked_inode_to_wb_begin(inode, &locked);
+		current->nr_dirtied--;
+		dec_zone_page_state(page, NR_DIRTIED);
+		dec_wb_stat(wb, WB_DIRTIED);
+		unlocked_inode_to_wb_end(inode, locked);
+	}
+}
+EXPORT_SYMBOL(account_page_redirty);
+
+/*
+ * When a writepage implementation decides that it doesn't want to write this
+ * page for some reason, it should redirty the locked page via
+ * redirty_page_for_writepage() and it should then unlock the page and return 0
+ */
+int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page)
+{
+	int ret;
+
+	wbc->pages_skipped++;
+	ret = __set_page_dirty_nobuffers(page);
+	account_page_redirty(page);
+	return ret;
+}
+EXPORT_SYMBOL(redirty_page_for_writepage);
+
+/*
+ * Dirty a page.
+ *
+ * For pages with a mapping this should be done under the page lock
+ * for the benefit of asynchronous memory errors who prefer a consistent
+ * dirty state. This rule can be broken in some special cases,
+ * but should be better not to.
+ *
+ * If the mapping doesn't provide a set_page_dirty a_op, then
+ * just fall through and assume that it wants buffer_heads.
+ */
+int set_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+
+	if (likely(mapping)) {
+		int (*spd)(struct page *) = mapping->a_ops->set_page_dirty;
+		/*
+		 * readahead/lru_deactivate_page could remain
+		 * PG_readahead/PG_reclaim due to race with end_page_writeback
+		 * About readahead, if the page is written, the flags would be
+		 * reset. So no problem.
+		 * About lru_deactivate_page, if the page is redirty, the flag
+		 * will be reset. So no problem. but if the page is used by readahead
+		 * it will confuse readahead and make it restart the size rampup
+		 * process. But it's a trivial problem.
+		 */
+		if (PageReclaim(page))
+			ClearPageReclaim(page);
+#ifdef CONFIG_BLOCK
+		if (!spd)
+			spd = __set_page_dirty_buffers;
+#endif
+		return (*spd)(page);
+	}
+	if (!PageDirty(page)) {
+		if (!TestSetPageDirty(page))
+			return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(set_page_dirty);
+
+/*
+ * set_page_dirty() is racy if the caller has no reference against
+ * page->mapping->host, and if the page is unlocked.  This is because another
+ * CPU could truncate the page off the mapping and then free the mapping.
+ *
+ * Usually, the page _is_ locked, or the caller is a user-space process which
+ * holds a reference on the inode by having an open file.
+ *
+ * In other cases, the page should be locked before running set_page_dirty().
+ */
+int set_page_dirty_lock(struct page *page)
+{
+	int ret;
+
+	lock_page(page);
+	ret = set_page_dirty(page);
+	unlock_page(page);
+	return ret;
+}
+EXPORT_SYMBOL(set_page_dirty_lock);
+
+/*
+ * This cancels just the dirty bit on the kernel page itself, it does NOT
+ * actually remove dirty bits on any mmap's that may be around. It also
+ * leaves the page tagged dirty, so any sync activity will still find it on
+ * the dirty lists, and in particular, clear_page_dirty_for_io() will still
+ * look at the dirty bits in the VM.
+ *
+ * Doing this should *normally* only ever be done when a page is truncated,
+ * and is not actually mapped anywhere at all. However, fs/buffer.c does
+ * this when it notices that somebody has cleaned out all the buffers on a
+ * page without actually doing it through the VM. Can you say "ext3 is
+ * horribly ugly"? Thought you could.
+ */
+void cancel_dirty_page(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+
+	if (mapping_cap_account_dirty(mapping)) {
+		struct inode *inode = mapping->host;
+		struct bdi_writeback *wb;
+		struct mem_cgroup *memcg;
+		bool locked;
+
+		memcg = mem_cgroup_begin_page_stat(page);
+		wb = unlocked_inode_to_wb_begin(inode, &locked);
+
+		if (TestClearPageDirty(page))
+			account_page_cleaned(page, mapping, memcg, wb);
+
+		unlocked_inode_to_wb_end(inode, locked);
+		mem_cgroup_end_page_stat(memcg);
+	} else {
+		ClearPageDirty(page);
+	}
+}
+EXPORT_SYMBOL(cancel_dirty_page);
+
+/*
+ * Clear a page's dirty flag, while caring for dirty memory accounting.
+ * Returns true if the page was previously dirty.
+ *
+ * This is for preparing to put the page under writeout.  We leave the page
+ * tagged as dirty in the radix tree so that a concurrent write-for-sync
+ * can discover it via a PAGECACHE_TAG_DIRTY walk.  The ->writepage
+ * implementation will run either set_page_writeback() or set_page_dirty(),
+ * at which stage we bring the page's dirty flag and radix-tree dirty tag
+ * back into sync.
+ *
+ * This incoherency between the page's dirty flag and radix-tree tag is
+ * unfortunate, but it only exists while the page is locked.
+ */
+int clear_page_dirty_for_io(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+	int ret = 0;
+
+	BUG_ON(!PageLocked(page));
+
+	if (mapping && mapping_cap_account_dirty(mapping)) {
+		struct inode *inode = mapping->host;
+		struct bdi_writeback *wb;
+		struct mem_cgroup *memcg;
+		bool locked;
+
+		/*
+		 * Yes, Virginia, this is indeed insane.
+		 *
+		 * We use this sequence to make sure that
+		 *  (a) we account for dirty stats properly
+		 *  (b) we tell the low-level filesystem to
+		 *      mark the whole page dirty if it was
+		 *      dirty in a pagetable. Only to then
+		 *  (c) clean the page again and return 1 to
+		 *      cause the writeback.
+		 *
+		 * This way we avoid all nasty races with the
+		 * dirty bit in multiple places and clearing
+		 * them concurrently from different threads.
+		 *
+		 * Note! Normally the "set_page_dirty(page)"
+		 * has no effect on the actual dirty bit - since
+		 * that will already usually be set. But we
+		 * need the side effects, and it can help us
+		 * avoid races.
+		 *
+		 * We basically use the page "master dirty bit"
+		 * as a serialization point for all the different
+		 * threads doing their things.
+		 */
+		if (page_mkclean(page))
+			set_page_dirty(page);
+		/*
+		 * We carefully synchronise fault handlers against
+		 * installing a dirty pte and marking the page dirty
+		 * at this point.  We do this by having them hold the
+		 * page lock while dirtying the page, and pages are
+		 * always locked coming in here, so we get the desired
+		 * exclusion.
+		 */
+		memcg = mem_cgroup_begin_page_stat(page);
+		wb = unlocked_inode_to_wb_begin(inode, &locked);
+		if (TestClearPageDirty(page)) {
+			mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
+			dec_zone_page_state(page, NR_FILE_DIRTY);
+			dec_wb_stat(wb, WB_RECLAIMABLE);
+			ret = 1;
+		}
+		unlocked_inode_to_wb_end(inode, locked);
+		mem_cgroup_end_page_stat(memcg);
+		return ret;
+	}
+	return TestClearPageDirty(page);
+}
+EXPORT_SYMBOL(clear_page_dirty_for_io);
+
+int test_clear_page_writeback(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+	struct mem_cgroup *memcg;
+	int ret;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	if (mapping) {
+		struct inode *inode = mapping->host;
+		struct backing_dev_info *bdi = inode_to_bdi(inode);
+		unsigned long flags;
+
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		ret = TestClearPageWriteback(page);
+		if (ret) {
+			radix_tree_tag_clear(&mapping->page_tree,
+						page_index(page),
+						PAGECACHE_TAG_WRITEBACK);
+			if (bdi_cap_account_writeback(bdi)) {
+				struct bdi_writeback *wb = inode_to_wb(inode);
+
+				__dec_wb_stat(wb, WB_WRITEBACK);
+				__wb_writeout_inc(wb);
+			}
+		}
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	} else {
+		ret = TestClearPageWriteback(page);
+	}
+	if (ret) {
+		mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_WRITEBACK);
+		dec_zone_page_state(page, NR_WRITEBACK);
+		inc_zone_page_state(page, NR_WRITTEN);
+	}
+	mem_cgroup_end_page_stat(memcg);
+	return ret;
+}
+
+int __test_set_page_writeback(struct page *page, bool keep_write)
+{
+	struct address_space *mapping = page_mapping(page);
+	struct mem_cgroup *memcg;
+	int ret;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	if (mapping) {
+		struct inode *inode = mapping->host;
+		struct backing_dev_info *bdi = inode_to_bdi(inode);
+		unsigned long flags;
+
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		ret = TestSetPageWriteback(page);
+		if (!ret) {
+			radix_tree_tag_set(&mapping->page_tree,
+						page_index(page),
+						PAGECACHE_TAG_WRITEBACK);
+			if (bdi_cap_account_writeback(bdi))
+				__inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);
+		}
+		if (!PageDirty(page))
+			radix_tree_tag_clear(&mapping->page_tree,
+						page_index(page),
+						PAGECACHE_TAG_DIRTY);
+		if (!keep_write)
+			radix_tree_tag_clear(&mapping->page_tree,
+						page_index(page),
+						PAGECACHE_TAG_TOWRITE);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	} else {
+		ret = TestSetPageWriteback(page);
+	}
+	if (!ret) {
+		mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_WRITEBACK);
+		inc_zone_page_state(page, NR_WRITEBACK);
+	}
+	mem_cgroup_end_page_stat(memcg);
+	return ret;
+
+}
+EXPORT_SYMBOL(__test_set_page_writeback);
+
+/*
+ * Return true if any of the pages in the mapping are marked with the
+ * passed tag.
+ */
+int mapping_tagged(struct address_space *mapping, int tag)
+{
+	return radix_tree_tagged(&mapping->page_tree, tag);
+}
+EXPORT_SYMBOL(mapping_tagged);
+
+/**
+ * wait_for_stable_page() - wait for writeback to finish, if necessary.
+ * @page:	The page to wait on.
+ *
+ * This function determines if the given page is related to a backing device
+ * that requires page contents to be held stable during writeback.  If so, then
+ * it will wait for any pending writeback to complete.
+ */
+void wait_for_stable_page(struct page *page)
+{
+	if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host)))
+		wait_on_page_writeback(page);
+}
+EXPORT_SYMBOL_GPL(wait_for_stable_page);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
new file mode 100644
index 0000000..6b5421a
--- /dev/null
+++ b/mm/page_alloc.c
@@ -0,0 +1,6967 @@
+/*
+ *  linux/mm/page_alloc.c
+ *
+ *  Manages the free list, the system allocates free pages here.
+ *  Note that kmalloc() lives in slab.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *  Swap reorganised 29.12.95, Stephen Tweedie
+ *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
+ *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
+ *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
+ *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
+ *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
+ */
+
+#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/interrupt.h>
+#include <linux/pagemap.h>
+#include <linux/jiffies.h>
+#include <linux/bootmem.h>
+#include <linux/memblock.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/kmemcheck.h>
+#include <linux/kasan.h>
+#include <linux/module.h>
+#include <linux/suspend.h>
+#include <linux/pagevec.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/ratelimit.h>
+#include <linux/oom.h>
+#include <linux/notifier.h>
+#include <linux/topology.h>
+#include <linux/sysctl.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/memory_hotplug.h>
+#include <linux/nodemask.h>
+#include <linux/vmalloc.h>
+#include <linux/vmstat.h>
+#include <linux/mempolicy.h>
+#include <linux/stop_machine.h>
+#include <linux/sort.h>
+#include <linux/pfn.h>
+#include <linux/backing-dev.h>
+#include <linux/fault-inject.h>
+#include <linux/page-isolation.h>
+#include <linux/page_ext.h>
+#include <linux/debugobjects.h>
+#include <linux/kmemleak.h>
+#include <linux/compaction.h>
+#include <trace/events/kmem.h>
+#include <linux/prefetch.h>
+#include <linux/mm_inline.h>
+#include <linux/migrate.h>
+#include <linux/page_ext.h>
+#include <linux/hugetlb.h>
+#include <linux/sched/rt.h>
+#include <linux/page_owner.h>
+#include <linux/kthread.h>
+
+#include <asm/sections.h>
+#include <asm/tlbflush.h>
+#include <asm/div64.h>
+#include "internal.h"
+
+/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
+static DEFINE_MUTEX(pcp_batch_high_lock);
+#define MIN_PERCPU_PAGELIST_FRACTION	(8)
+
+#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
+DEFINE_PER_CPU(int, numa_node);
+EXPORT_PER_CPU_SYMBOL(numa_node);
+#endif
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+/*
+ * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
+ * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
+ * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
+ * defined in <linux/topology.h>.
+ */
+DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
+EXPORT_PER_CPU_SYMBOL(_numa_mem_);
+int _node_numa_mem_[MAX_NUMNODES];
+#endif
+
+/*
+ * Array of node states.
+ */
+nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
+	[N_POSSIBLE] = NODE_MASK_ALL,
+	[N_ONLINE] = { { [0] = 1UL } },
+#ifndef CONFIG_NUMA
+	[N_NORMAL_MEMORY] = { { [0] = 1UL } },
+#ifdef CONFIG_HIGHMEM
+	[N_HIGH_MEMORY] = { { [0] = 1UL } },
+#endif
+#ifdef CONFIG_MOVABLE_NODE
+	[N_MEMORY] = { { [0] = 1UL } },
+#endif
+	[N_CPU] = { { [0] = 1UL } },
+#endif	/* NUMA */
+};
+EXPORT_SYMBOL(node_states);
+
+/* Protect totalram_pages and zone->managed_pages */
+static DEFINE_SPINLOCK(managed_page_count_lock);
+
+unsigned long totalram_pages __read_mostly;
+unsigned long totalreserve_pages __read_mostly;
+unsigned long totalcma_pages __read_mostly;
+/*
+ * When calculating the number of globally allowed dirty pages, there
+ * is a certain number of per-zone reserves that should not be
+ * considered dirtyable memory.  This is the sum of those reserves
+ * over all existing zones that contribute dirtyable memory.
+ */
+unsigned long dirty_balance_reserve __read_mostly;
+
+int percpu_pagelist_fraction;
+gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
+
+/*
+ * A cached value of the page's pageblock's migratetype, used when the page is
+ * put on a pcplist. Used to avoid the pageblock migratetype lookup when
+ * freeing from pcplists in most cases, at the cost of possibly becoming stale.
+ * Also the migratetype set in the page does not necessarily match the pcplist
+ * index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
+ * other index - this ensures that it will be put on the correct CMA freelist.
+ */
+static inline int get_pcppage_migratetype(struct page *page)
+{
+	return page->index;
+}
+
+static inline void set_pcppage_migratetype(struct page *page, int migratetype)
+{
+	page->index = migratetype;
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * The following functions are used by the suspend/hibernate code to temporarily
+ * change gfp_allowed_mask in order to avoid using I/O during memory allocations
+ * while devices are suspended.  To avoid races with the suspend/hibernate code,
+ * they should always be called with pm_mutex held (gfp_allowed_mask also should
+ * only be modified with pm_mutex held, unless the suspend/hibernate code is
+ * guaranteed not to run in parallel with that modification).
+ */
+
+static gfp_t saved_gfp_mask;
+
+void pm_restore_gfp_mask(void)
+{
+	WARN_ON(!mutex_is_locked(&pm_mutex));
+	if (saved_gfp_mask) {
+		gfp_allowed_mask = saved_gfp_mask;
+		saved_gfp_mask = 0;
+	}
+}
+
+void pm_restrict_gfp_mask(void)
+{
+	WARN_ON(!mutex_is_locked(&pm_mutex));
+	WARN_ON(saved_gfp_mask);
+	saved_gfp_mask = gfp_allowed_mask;
+	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
+}
+
+bool pm_suspended_storage(void)
+{
+	if ((gfp_allowed_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
+		return false;
+	return true;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+unsigned int pageblock_order __read_mostly;
+#endif
+
+static void __free_pages_ok(struct page *page, unsigned int order);
+
+/*
+ * results with 256, 32 in the lowmem_reserve sysctl:
+ *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
+ *	1G machine -> (16M dma, 784M normal, 224M high)
+ *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
+ *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
+ *	HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
+ *
+ * TBD: should special case ZONE_DMA32 machines here - in those we normally
+ * don't need any ZONE_NORMAL reservation
+ */
+int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
+#ifdef CONFIG_ZONE_DMA
+	 256,
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	 256,
+#endif
+#ifdef CONFIG_HIGHMEM
+	 32,
+#endif
+	 32,
+};
+
+EXPORT_SYMBOL(totalram_pages);
+
+static char * const zone_names[MAX_NR_ZONES] = {
+#ifdef CONFIG_ZONE_DMA
+	 "DMA",
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	 "DMA32",
+#endif
+	 "Normal",
+#ifdef CONFIG_HIGHMEM
+	 "HighMem",
+#endif
+	 "Movable",
+#ifdef CONFIG_ZONE_DEVICE
+	 "Device",
+#endif
+};
+
+static void free_compound_page(struct page *page);
+compound_page_dtor * const compound_page_dtors[] = {
+	NULL,
+	free_compound_page,
+#ifdef CONFIG_HUGETLB_PAGE
+	free_huge_page,
+#endif
+};
+
+int min_free_kbytes = 1024;
+int user_min_free_kbytes = -1;
+
+static unsigned long __meminitdata nr_kernel_pages;
+static unsigned long __meminitdata nr_all_pages;
+static unsigned long __meminitdata dma_reserve;
+
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
+static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
+static unsigned long __initdata required_kernelcore;
+static unsigned long __initdata required_movablecore;
+static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
+
+/* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
+int movable_zone;
+EXPORT_SYMBOL(movable_zone);
+#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+
+#if MAX_NUMNODES > 1
+int nr_node_ids __read_mostly = MAX_NUMNODES;
+int nr_online_nodes __read_mostly = 1;
+EXPORT_SYMBOL(nr_node_ids);
+EXPORT_SYMBOL(nr_online_nodes);
+#endif
+
+int page_group_by_mobility_disabled __read_mostly;
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+static inline void reset_deferred_meminit(pg_data_t *pgdat)
+{
+	unsigned long max_initialise;
+	unsigned long reserved_lowmem;
+
+	/*
+	 * Initialise at least 2G of a node but also take into account that
+	 * two large system hashes that can take up 1GB for 0.25TB/node.
+	 */
+	max_initialise = max(2UL << (30 - PAGE_SHIFT),
+		(pgdat->node_spanned_pages >> 8));
+
+	/*
+	 * Compensate the all the memblock reservations (e.g. crash kernel)
+	 * from the initial estimation to make sure we will initialize enough
+	 * memory to boot.
+	 */
+	reserved_lowmem = memblock_reserved_memory_within(pgdat->node_start_pfn,
+			pgdat->node_start_pfn + max_initialise);
+	max_initialise += reserved_lowmem;
+
+	pgdat->static_init_size = min(max_initialise, pgdat->node_spanned_pages);
+	pgdat->first_deferred_pfn = ULONG_MAX;
+}
+
+/* Returns true if the struct page for the pfn is uninitialised */
+static inline bool __meminit early_page_uninitialised(unsigned long pfn)
+{
+	int nid = early_pfn_to_nid(pfn);
+
+	if (node_online(nid) && pfn >= NODE_DATA(nid)->first_deferred_pfn)
+		return true;
+
+	return false;
+}
+
+static inline bool early_page_nid_uninitialised(unsigned long pfn, int nid)
+{
+	if (pfn >= NODE_DATA(nid)->first_deferred_pfn)
+		return true;
+
+	return false;
+}
+
+/*
+ * Returns false when the remaining initialisation should be deferred until
+ * later in the boot cycle when it can be parallelised.
+ */
+static inline bool update_defer_init(pg_data_t *pgdat,
+				unsigned long pfn, unsigned long zone_end,
+				unsigned long *nr_initialised)
+{
+	/* Always populate low zones for address-contrained allocations */
+	if (zone_end < pgdat_end_pfn(pgdat))
+		return true;
+	/* Initialise at least 2G of the highest zone */
+	(*nr_initialised)++;
+	if ((*nr_initialised > pgdat->static_init_size) &&
+	    (pfn & (PAGES_PER_SECTION - 1)) == 0) {
+		pgdat->first_deferred_pfn = pfn;
+		return false;
+	}
+
+	return true;
+}
+#else
+static inline void reset_deferred_meminit(pg_data_t *pgdat)
+{
+}
+
+static inline bool early_page_uninitialised(unsigned long pfn)
+{
+	return false;
+}
+
+static inline bool early_page_nid_uninitialised(unsigned long pfn, int nid)
+{
+	return false;
+}
+
+static inline bool update_defer_init(pg_data_t *pgdat,
+				unsigned long pfn, unsigned long zone_end,
+				unsigned long *nr_initialised)
+{
+	return true;
+}
+#endif
+
+
+void set_pageblock_migratetype(struct page *page, int migratetype)
+{
+	if (unlikely(page_group_by_mobility_disabled &&
+		     migratetype < MIGRATE_PCPTYPES))
+		migratetype = MIGRATE_UNMOVABLE;
+
+	set_pageblock_flags_group(page, (unsigned long)migratetype,
+					PB_migrate, PB_migrate_end);
+}
+
+#ifdef CONFIG_DEBUG_VM
+static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
+{
+	int ret = 0;
+	unsigned seq;
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long sp, start_pfn;
+
+	do {
+		seq = zone_span_seqbegin(zone);
+		start_pfn = zone->zone_start_pfn;
+		sp = zone->spanned_pages;
+		if (!zone_spans_pfn(zone, pfn))
+			ret = 1;
+	} while (zone_span_seqretry(zone, seq));
+
+	if (ret)
+		pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
+			pfn, zone_to_nid(zone), zone->name,
+			start_pfn, start_pfn + sp);
+
+	return ret;
+}
+
+static int page_is_consistent(struct zone *zone, struct page *page)
+{
+	if (!pfn_valid_within(page_to_pfn(page)))
+		return 0;
+	if (zone != page_zone(page))
+		return 0;
+
+	return 1;
+}
+/*
+ * Temporary debugging check for pages not lying within a given zone.
+ */
+static int bad_range(struct zone *zone, struct page *page)
+{
+	if (page_outside_zone_boundaries(zone, page))
+		return 1;
+	if (!page_is_consistent(zone, page))
+		return 1;
+
+	return 0;
+}
+#else
+static inline int bad_range(struct zone *zone, struct page *page)
+{
+	return 0;
+}
+#endif
+
+static void bad_page(struct page *page, const char *reason,
+		unsigned long bad_flags)
+{
+	static unsigned long resume;
+	static unsigned long nr_shown;
+	static unsigned long nr_unshown;
+
+	/* Don't complain about poisoned pages */
+	if (PageHWPoison(page)) {
+		page_mapcount_reset(page); /* remove PageBuddy */
+		return;
+	}
+
+	/*
+	 * Allow a burst of 60 reports, then keep quiet for that minute;
+	 * or allow a steady drip of one report per second.
+	 */
+	if (nr_shown == 60) {
+		if (time_before(jiffies, resume)) {
+			nr_unshown++;
+			goto out;
+		}
+		if (nr_unshown) {
+			printk(KERN_ALERT
+			      "BUG: Bad page state: %lu messages suppressed\n",
+				nr_unshown);
+			nr_unshown = 0;
+		}
+		nr_shown = 0;
+	}
+	if (nr_shown++ == 0)
+		resume = jiffies + 60 * HZ;
+
+	printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
+		current->comm, page_to_pfn(page));
+	dump_page_badflags(page, reason, bad_flags);
+
+	print_modules();
+	dump_stack();
+out:
+	/* Leave bad fields for debug, except PageBuddy could make trouble */
+	page_mapcount_reset(page); /* remove PageBuddy */
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+}
+
+/*
+ * Higher-order pages are called "compound pages".  They are structured thusly:
+ *
+ * The first PAGE_SIZE page is called the "head page" and have PG_head set.
+ *
+ * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
+ * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
+ *
+ * The first tail page's ->compound_dtor holds the offset in array of compound
+ * page destructors. See compound_page_dtors.
+ *
+ * The first tail page's ->compound_order holds the order of allocation.
+ * This usage means that zero-order pages may not be compound.
+ */
+
+static void free_compound_page(struct page *page)
+{
+	__free_pages_ok(page, compound_order(page));
+}
+
+void prep_compound_page(struct page *page, unsigned int order)
+{
+	int i;
+	int nr_pages = 1 << order;
+
+	set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
+	set_compound_order(page, order);
+	__SetPageHead(page);
+	for (i = 1; i < nr_pages; i++) {
+		struct page *p = page + i;
+		set_page_count(p, 0);
+		set_compound_head(p, page);
+	}
+}
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+unsigned int _debug_guardpage_minorder;
+bool _debug_pagealloc_enabled __read_mostly;
+bool _debug_guardpage_enabled __read_mostly;
+
+static int __init early_debug_pagealloc(char *buf)
+{
+	if (!buf)
+		return -EINVAL;
+
+	if (strcmp(buf, "on") == 0)
+		_debug_pagealloc_enabled = true;
+
+	return 0;
+}
+early_param("debug_pagealloc", early_debug_pagealloc);
+
+static bool need_debug_guardpage(void)
+{
+	/* If we don't use debug_pagealloc, we don't need guard page */
+	if (!debug_pagealloc_enabled())
+		return false;
+
+	return true;
+}
+
+static void init_debug_guardpage(void)
+{
+	if (!debug_pagealloc_enabled())
+		return;
+
+	_debug_guardpage_enabled = true;
+}
+
+struct page_ext_operations debug_guardpage_ops = {
+	.need = need_debug_guardpage,
+	.init = init_debug_guardpage,
+};
+
+static int __init debug_guardpage_minorder_setup(char *buf)
+{
+	unsigned long res;
+
+	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
+		printk(KERN_ERR "Bad debug_guardpage_minorder value\n");
+		return 0;
+	}
+	_debug_guardpage_minorder = res;
+	printk(KERN_INFO "Setting debug_guardpage_minorder to %lu\n", res);
+	return 0;
+}
+__setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
+
+static inline void set_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype)
+{
+	struct page_ext *page_ext;
+
+	if (!debug_guardpage_enabled())
+		return;
+
+	page_ext = lookup_page_ext(page);
+	__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
+
+	INIT_LIST_HEAD(&page->lru);
+	set_page_private(page, order);
+	/* Guard pages are not available for any usage */
+	__mod_zone_freepage_state(zone, -(1 << order), migratetype);
+}
+
+static inline void clear_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype)
+{
+	struct page_ext *page_ext;
+
+	if (!debug_guardpage_enabled())
+		return;
+
+	page_ext = lookup_page_ext(page);
+	__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
+
+	set_page_private(page, 0);
+	if (!is_migrate_isolate(migratetype))
+		__mod_zone_freepage_state(zone, (1 << order), migratetype);
+}
+#else
+struct page_ext_operations debug_guardpage_ops = { NULL, };
+static inline void set_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype) {}
+static inline void clear_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype) {}
+#endif
+
+static inline void set_page_order(struct page *page, unsigned int order)
+{
+	set_page_private(page, order);
+	__SetPageBuddy(page);
+}
+
+static inline void rmv_page_order(struct page *page)
+{
+	__ClearPageBuddy(page);
+	set_page_private(page, 0);
+}
+
+/*
+ * This function checks whether a page is free && is the buddy
+ * we can do coalesce a page and its buddy if
+ * (a) the buddy is not in a hole &&
+ * (b) the buddy is in the buddy system &&
+ * (c) a page and its buddy have the same order &&
+ * (d) a page and its buddy are in the same zone.
+ *
+ * For recording whether a page is in the buddy system, we set ->_mapcount
+ * PAGE_BUDDY_MAPCOUNT_VALUE.
+ * Setting, clearing, and testing _mapcount PAGE_BUDDY_MAPCOUNT_VALUE is
+ * serialized by zone->lock.
+ *
+ * For recording page's order, we use page_private(page).
+ */
+static inline int page_is_buddy(struct page *page, struct page *buddy,
+							unsigned int order)
+{
+	if (!pfn_valid_within(page_to_pfn(buddy)))
+		return 0;
+
+	if (page_is_guard(buddy) && page_order(buddy) == order) {
+		if (page_zone_id(page) != page_zone_id(buddy))
+			return 0;
+
+		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+		return 1;
+	}
+
+	if (PageBuddy(buddy) && page_order(buddy) == order) {
+		/*
+		 * zone check is done late to avoid uselessly
+		 * calculating zone/node ids for pages that could
+		 * never merge.
+		 */
+		if (page_zone_id(page) != page_zone_id(buddy))
+			return 0;
+
+		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Freeing function for a buddy system allocator.
+ *
+ * The concept of a buddy system is to maintain direct-mapped table
+ * (containing bit values) for memory blocks of various "orders".
+ * The bottom level table contains the map for the smallest allocatable
+ * units of memory (here, pages), and each level above it describes
+ * pairs of units from the levels below, hence, "buddies".
+ * At a high level, all that happens here is marking the table entry
+ * at the bottom level available, and propagating the changes upward
+ * as necessary, plus some accounting needed to play nicely with other
+ * parts of the VM system.
+ * At each level, we keep a list of pages, which are heads of continuous
+ * free pages of length of (1 << order) and marked with _mapcount
+ * PAGE_BUDDY_MAPCOUNT_VALUE. Page's order is recorded in page_private(page)
+ * field.
+ * So when we are allocating or freeing one, we can derive the state of the
+ * other.  That is, if we allocate a small block, and both were
+ * free, the remainder of the region must be split into blocks.
+ * If a block is freed, and its buddy is also free, then this
+ * triggers coalescing into a block of larger size.
+ *
+ * -- nyc
+ */
+
+static inline void __free_one_page(struct page *page,
+		unsigned long pfn,
+		struct zone *zone, unsigned int order,
+		int migratetype)
+{
+	unsigned long page_idx;
+	unsigned long combined_idx;
+	unsigned long uninitialized_var(buddy_idx);
+	struct page *buddy;
+	unsigned int max_order;
+
+	max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1);
+
+	VM_BUG_ON(!zone_is_initialized(zone));
+	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
+
+	VM_BUG_ON(migratetype == -1);
+	if (likely(!is_migrate_isolate(migratetype)))
+		__mod_zone_freepage_state(zone, 1 << order, migratetype);
+
+	page_idx = pfn & ((1 << MAX_ORDER) - 1);
+
+	VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page);
+	VM_BUG_ON_PAGE(bad_range(zone, page), page);
+
+continue_merging:
+	while (order < max_order - 1) {
+		buddy_idx = __find_buddy_index(page_idx, order);
+		buddy = page + (buddy_idx - page_idx);
+		if (!page_is_buddy(page, buddy, order))
+			goto done_merging;
+		/*
+		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
+		 * merge with it and move up one order.
+		 */
+		if (page_is_guard(buddy)) {
+			clear_page_guard(zone, buddy, order, migratetype);
+		} else {
+			list_del(&buddy->lru);
+			zone->free_area[order].nr_free--;
+			rmv_page_order(buddy);
+		}
+		combined_idx = buddy_idx & page_idx;
+		page = page + (combined_idx - page_idx);
+		page_idx = combined_idx;
+		order++;
+	}
+	if (max_order < MAX_ORDER) {
+		/* If we are here, it means order is >= pageblock_order.
+		 * We want to prevent merge between freepages on isolate
+		 * pageblock and normal pageblock. Without this, pageblock
+		 * isolation could cause incorrect freepage or CMA accounting.
+		 *
+		 * We don't want to hit this code for the more frequent
+		 * low-order merging.
+		 */
+		if (unlikely(has_isolate_pageblock(zone))) {
+			int buddy_mt;
+
+			buddy_idx = __find_buddy_index(page_idx, order);
+			buddy = page + (buddy_idx - page_idx);
+			buddy_mt = get_pageblock_migratetype(buddy);
+
+			if (migratetype != buddy_mt
+					&& (is_migrate_isolate(migratetype) ||
+						is_migrate_isolate(buddy_mt)))
+				goto done_merging;
+		}
+		max_order++;
+		goto continue_merging;
+	}
+
+done_merging:
+	set_page_order(page, order);
+
+	/*
+	 * If this is not the largest possible page, check if the buddy
+	 * of the next-highest order is free. If it is, it's possible
+	 * that pages are being freed that will coalesce soon. In case,
+	 * that is happening, add the free page to the tail of the list
+	 * so it's less likely to be used soon and more likely to be merged
+	 * as a higher order page
+	 */
+	if ((order < MAX_ORDER-2) && pfn_valid_within(page_to_pfn(buddy))) {
+		struct page *higher_page, *higher_buddy;
+		combined_idx = buddy_idx & page_idx;
+		higher_page = page + (combined_idx - page_idx);
+		buddy_idx = __find_buddy_index(combined_idx, order + 1);
+		higher_buddy = higher_page + (buddy_idx - combined_idx);
+		if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
+			list_add_tail(&page->lru,
+				&zone->free_area[order].free_list[migratetype]);
+			goto out;
+		}
+	}
+
+	list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
+out:
+	zone->free_area[order].nr_free++;
+}
+
+static inline int free_pages_check(struct page *page)
+{
+	const char *bad_reason = NULL;
+	unsigned long bad_flags = 0;
+
+	if (unlikely(page_mapcount(page)))
+		bad_reason = "nonzero mapcount";
+	if (unlikely(page->mapping != NULL))
+		bad_reason = "non-NULL mapping";
+	if (unlikely(atomic_read(&page->_count) != 0))
+		bad_reason = "nonzero _count";
+	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
+		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
+		bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
+	}
+#ifdef CONFIG_MEMCG
+	if (unlikely(page->mem_cgroup))
+		bad_reason = "page still charged to cgroup";
+#endif
+	if (unlikely(bad_reason)) {
+		bad_page(page, bad_reason, bad_flags);
+		return 1;
+	}
+	page_cpupid_reset_last(page);
+	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
+		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+	return 0;
+}
+
+/*
+ * Frees a number of pages from the PCP lists
+ * Assumes all pages on list are in same zone, and of same order.
+ * count is the number of pages to free.
+ *
+ * If the zone was previously in an "all pages pinned" state then look to
+ * see if this freeing clears that state.
+ *
+ * And clear the zone's pages_scanned counter, to hold off the "all pages are
+ * pinned" detection logic.
+ */
+static void free_pcppages_bulk(struct zone *zone, int count,
+					struct per_cpu_pages *pcp)
+{
+	int migratetype = 0;
+	int batch_free = 0;
+	int to_free = count;
+	unsigned long nr_scanned;
+
+	spin_lock(&zone->lock);
+	nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
+	if (nr_scanned)
+		__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
+
+	while (to_free) {
+		struct page *page;
+		struct list_head *list;
+
+		/*
+		 * Remove pages from lists in a round-robin fashion. A
+		 * batch_free count is maintained that is incremented when an
+		 * empty list is encountered.  This is so more pages are freed
+		 * off fuller lists instead of spinning excessively around empty
+		 * lists
+		 */
+		do {
+			batch_free++;
+			if (++migratetype == MIGRATE_PCPTYPES)
+				migratetype = 0;
+			list = &pcp->lists[migratetype];
+		} while (list_empty(list));
+
+		/* This is the only non-empty list. Free them all. */
+		if (batch_free == MIGRATE_PCPTYPES)
+			batch_free = to_free;
+
+		do {
+			int mt;	/* migratetype of the to-be-freed page */
+
+			page = list_entry(list->prev, struct page, lru);
+			/* must delete as __free_one_page list manipulates */
+			list_del(&page->lru);
+
+			mt = get_pcppage_migratetype(page);
+			/* MIGRATE_ISOLATE page should not go to pcplists */
+			VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
+			/* Pageblock could have been isolated meanwhile */
+			if (unlikely(has_isolate_pageblock(zone)))
+				mt = get_pageblock_migratetype(page);
+
+			__free_one_page(page, page_to_pfn(page), zone, 0, mt);
+			trace_mm_page_pcpu_drain(page, 0, mt);
+		} while (--to_free && --batch_free && !list_empty(list));
+	}
+	spin_unlock(&zone->lock);
+}
+
+static void free_one_page(struct zone *zone,
+				struct page *page, unsigned long pfn,
+				unsigned int order,
+				int migratetype)
+{
+	unsigned long nr_scanned;
+	spin_lock(&zone->lock);
+	nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
+	if (nr_scanned)
+		__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
+
+	if (unlikely(has_isolate_pageblock(zone) ||
+		is_migrate_isolate(migratetype))) {
+		migratetype = get_pfnblock_migratetype(page, pfn);
+	}
+	__free_one_page(page, pfn, zone, order, migratetype);
+	spin_unlock(&zone->lock);
+}
+
+static int free_tail_pages_check(struct page *head_page, struct page *page)
+{
+	int ret = 1;
+
+	/*
+	 * We rely page->lru.next never has bit 0 set, unless the page
+	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
+	 */
+	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
+
+	if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
+		ret = 0;
+		goto out;
+	}
+	if (unlikely(!PageTail(page))) {
+		bad_page(page, "PageTail not set", 0);
+		goto out;
+	}
+	if (unlikely(compound_head(page) != head_page)) {
+		bad_page(page, "compound_head not consistent", 0);
+		goto out;
+	}
+	ret = 0;
+out:
+	clear_compound_head(page);
+	return ret;
+}
+
+static void __meminit __init_single_page(struct page *page, unsigned long pfn,
+				unsigned long zone, int nid)
+{
+	set_page_links(page, zone, nid, pfn);
+	init_page_count(page);
+	page_mapcount_reset(page);
+	page_cpupid_reset_last(page);
+
+	INIT_LIST_HEAD(&page->lru);
+#ifdef WANT_PAGE_VIRTUAL
+	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
+	if (!is_highmem_idx(zone))
+		set_page_address(page, __va(pfn << PAGE_SHIFT));
+#endif
+}
+
+static void __meminit __init_single_pfn(unsigned long pfn, unsigned long zone,
+					int nid)
+{
+	return __init_single_page(pfn_to_page(pfn), pfn, zone, nid);
+}
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+static void init_reserved_page(unsigned long pfn)
+{
+	pg_data_t *pgdat;
+	int nid, zid;
+
+	if (!early_page_uninitialised(pfn))
+		return;
+
+	nid = early_pfn_to_nid(pfn);
+	pgdat = NODE_DATA(nid);
+
+	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+		struct zone *zone = &pgdat->node_zones[zid];
+
+		if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
+			break;
+	}
+	__init_single_pfn(pfn, zid, nid);
+}
+#else
+static inline void init_reserved_page(unsigned long pfn)
+{
+}
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
+/*
+ * Initialised pages do not have PageReserved set. This function is
+ * called for each range allocated by the bootmem allocator and
+ * marks the pages PageReserved. The remaining valid pages are later
+ * sent to the buddy page allocator.
+ */
+void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
+{
+	unsigned long start_pfn = PFN_DOWN(start);
+	unsigned long end_pfn = PFN_UP(end);
+
+	for (; start_pfn < end_pfn; start_pfn++) {
+		if (pfn_valid(start_pfn)) {
+			struct page *page = pfn_to_page(start_pfn);
+
+			init_reserved_page(start_pfn);
+
+			/* Avoid false-positive PageTail() */
+			INIT_LIST_HEAD(&page->lru);
+
+			SetPageReserved(page);
+		}
+	}
+}
+
+static bool free_pages_prepare(struct page *page, unsigned int order)
+{
+	bool compound = PageCompound(page);
+	int i, bad = 0;
+
+	VM_BUG_ON_PAGE(PageTail(page), page);
+	VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
+
+	trace_mm_page_free(page, order);
+	kmemcheck_free_shadow(page, order);
+	kasan_free_pages(page, order);
+
+	if (PageAnon(page))
+		page->mapping = NULL;
+	bad += free_pages_check(page);
+	for (i = 1; i < (1 << order); i++) {
+		if (compound)
+			bad += free_tail_pages_check(page, page + i);
+		bad += free_pages_check(page + i);
+	}
+	if (bad)
+		return false;
+
+	reset_page_owner(page, order);
+
+	if (!PageHighMem(page)) {
+		debug_check_no_locks_freed(page_address(page),
+					   PAGE_SIZE << order);
+		debug_check_no_obj_freed(page_address(page),
+					   PAGE_SIZE << order);
+	}
+	arch_free_page(page, order);
+	kernel_map_pages(page, 1 << order, 0);
+
+	return true;
+}
+
+static void __free_pages_ok(struct page *page, unsigned int order)
+{
+	unsigned long flags;
+	int migratetype;
+	unsigned long pfn = page_to_pfn(page);
+
+	if (!free_pages_prepare(page, order))
+		return;
+
+	migratetype = get_pfnblock_migratetype(page, pfn);
+	local_irq_save(flags);
+	__count_vm_events(PGFREE, 1 << order);
+	free_one_page(page_zone(page), page, pfn, order, migratetype);
+	local_irq_restore(flags);
+}
+
+static void __init __free_pages_boot_core(struct page *page,
+					unsigned long pfn, unsigned int order)
+{
+	unsigned int nr_pages = 1 << order;
+	struct page *p = page;
+	unsigned int loop;
+
+	prefetchw(p);
+	for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
+		prefetchw(p + 1);
+		__ClearPageReserved(p);
+		set_page_count(p, 0);
+	}
+	__ClearPageReserved(p);
+	set_page_count(p, 0);
+
+	page_zone(page)->managed_pages += nr_pages;
+	set_page_refcounted(page);
+	__free_pages(page, order);
+}
+
+#if defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) || \
+	defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
+
+static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
+
+int __meminit early_pfn_to_nid(unsigned long pfn)
+{
+	static DEFINE_SPINLOCK(early_pfn_lock);
+	int nid;
+
+	spin_lock(&early_pfn_lock);
+	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
+	if (nid < 0)
+		nid = first_online_node;
+	spin_unlock(&early_pfn_lock);
+
+	return nid;
+}
+#endif
+
+#ifdef CONFIG_NODES_SPAN_OTHER_NODES
+static inline bool __meminit meminit_pfn_in_nid(unsigned long pfn, int node,
+					struct mminit_pfnnid_cache *state)
+{
+	int nid;
+
+	nid = __early_pfn_to_nid(pfn, state);
+	if (nid >= 0 && nid != node)
+		return false;
+	return true;
+}
+
+/* Only safe to use early in boot when initialisation is single-threaded */
+static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
+{
+	return meminit_pfn_in_nid(pfn, node, &early_pfnnid_cache);
+}
+
+#else
+
+static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
+{
+	return true;
+}
+static inline bool __meminit meminit_pfn_in_nid(unsigned long pfn, int node,
+					struct mminit_pfnnid_cache *state)
+{
+	return true;
+}
+#endif
+
+
+void __init __free_pages_bootmem(struct page *page, unsigned long pfn,
+							unsigned int order)
+{
+	if (early_page_uninitialised(pfn))
+		return;
+	return __free_pages_boot_core(page, pfn, order);
+}
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+static void __init deferred_free_range(struct page *page,
+					unsigned long pfn, int nr_pages)
+{
+	int i;
+
+	if (!page)
+		return;
+
+	/* Free a large naturally-aligned chunk if possible */
+	if (nr_pages == MAX_ORDER_NR_PAGES &&
+	    (pfn & (MAX_ORDER_NR_PAGES-1)) == 0) {
+		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+		__free_pages_boot_core(page, pfn, MAX_ORDER-1);
+		return;
+	}
+
+	for (i = 0; i < nr_pages; i++, page++, pfn++)
+		__free_pages_boot_core(page, pfn, 0);
+}
+
+/* Completion tracking for deferred_init_memmap() threads */
+static atomic_t pgdat_init_n_undone __initdata;
+static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);
+
+static inline void __init pgdat_init_report_one_done(void)
+{
+	if (atomic_dec_and_test(&pgdat_init_n_undone))
+		complete(&pgdat_init_all_done_comp);
+}
+
+/* Initialise remaining memory on a node */
+static int __init deferred_init_memmap(void *data)
+{
+	pg_data_t *pgdat = data;
+	int nid = pgdat->node_id;
+	struct mminit_pfnnid_cache nid_init_state = { };
+	unsigned long start = jiffies;
+	unsigned long nr_pages = 0;
+	unsigned long walk_start, walk_end;
+	int i, zid;
+	struct zone *zone;
+	unsigned long first_init_pfn = pgdat->first_deferred_pfn;
+	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
+
+	if (first_init_pfn == ULONG_MAX) {
+		pgdat_init_report_one_done();
+		return 0;
+	}
+
+	/* Bind memory initialisation thread to a local node if possible */
+	if (!cpumask_empty(cpumask))
+		set_cpus_allowed_ptr(current, cpumask);
+
+	/* Sanity check boundaries */
+	BUG_ON(pgdat->first_deferred_pfn < pgdat->node_start_pfn);
+	BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat));
+	pgdat->first_deferred_pfn = ULONG_MAX;
+
+	/* Only the highest zone is deferred so find it */
+	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+		zone = pgdat->node_zones + zid;
+		if (first_init_pfn < zone_end_pfn(zone))
+			break;
+	}
+
+	for_each_mem_pfn_range(i, nid, &walk_start, &walk_end, NULL) {
+		unsigned long pfn, end_pfn;
+		struct page *page = NULL;
+		struct page *free_base_page = NULL;
+		unsigned long free_base_pfn = 0;
+		int nr_to_free = 0;
+
+		end_pfn = min(walk_end, zone_end_pfn(zone));
+		pfn = first_init_pfn;
+		if (pfn < walk_start)
+			pfn = walk_start;
+		if (pfn < zone->zone_start_pfn)
+			pfn = zone->zone_start_pfn;
+
+		for (; pfn < end_pfn; pfn++) {
+			if (!pfn_valid_within(pfn))
+				goto free_range;
+
+			/*
+			 * Ensure pfn_valid is checked every
+			 * MAX_ORDER_NR_PAGES for memory holes
+			 */
+			if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
+				if (!pfn_valid(pfn)) {
+					page = NULL;
+					goto free_range;
+				}
+			}
+
+			if (!meminit_pfn_in_nid(pfn, nid, &nid_init_state)) {
+				page = NULL;
+				goto free_range;
+			}
+
+			/* Minimise pfn page lookups and scheduler checks */
+			if (page && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) {
+				page++;
+			} else {
+				nr_pages += nr_to_free;
+				deferred_free_range(free_base_page,
+						free_base_pfn, nr_to_free);
+				free_base_page = NULL;
+				free_base_pfn = nr_to_free = 0;
+
+				page = pfn_to_page(pfn);
+				cond_resched();
+			}
+
+			if (page->flags) {
+				VM_BUG_ON(page_zone(page) != zone);
+				goto free_range;
+			}
+
+			__init_single_page(page, pfn, zid, nid);
+			if (!free_base_page) {
+				free_base_page = page;
+				free_base_pfn = pfn;
+				nr_to_free = 0;
+			}
+			nr_to_free++;
+
+			/* Where possible, batch up pages for a single free */
+			continue;
+free_range:
+			/* Free the current block of pages to allocator */
+			nr_pages += nr_to_free;
+			deferred_free_range(free_base_page, free_base_pfn,
+								nr_to_free);
+			free_base_page = NULL;
+			free_base_pfn = nr_to_free = 0;
+		}
+
+		first_init_pfn = max(end_pfn, first_init_pfn);
+	}
+
+	/* Sanity check that the next zone really is unpopulated */
+	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
+
+	pr_info("node %d initialised, %lu pages in %ums\n", nid, nr_pages,
+					jiffies_to_msecs(jiffies - start));
+
+	pgdat_init_report_one_done();
+	return 0;
+}
+
+void __init page_alloc_init_late(void)
+{
+	int nid;
+
+	/* There will be num_node_state(N_MEMORY) threads */
+	atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
+	for_each_node_state(nid, N_MEMORY) {
+		kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
+	}
+
+	/* Block until all are initialised */
+	wait_for_completion(&pgdat_init_all_done_comp);
+
+	/* Reinit limits that are based on free pages after the kernel is up */
+	files_maxfiles_init();
+}
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
+#ifdef CONFIG_CMA
+/* Free whole pageblock and set its migration type to MIGRATE_CMA. */
+void __init init_cma_reserved_pageblock(struct page *page)
+{
+	unsigned i = pageblock_nr_pages;
+	struct page *p = page;
+
+	do {
+		__ClearPageReserved(p);
+		set_page_count(p, 0);
+	} while (++p, --i);
+
+	set_pageblock_migratetype(page, MIGRATE_CMA);
+
+	if (pageblock_order >= MAX_ORDER) {
+		i = pageblock_nr_pages;
+		p = page;
+		do {
+			set_page_refcounted(p);
+			__free_pages(p, MAX_ORDER - 1);
+			p += MAX_ORDER_NR_PAGES;
+		} while (i -= MAX_ORDER_NR_PAGES);
+	} else {
+		set_page_refcounted(page);
+		__free_pages(page, pageblock_order);
+	}
+
+	adjust_managed_page_count(page, pageblock_nr_pages);
+}
+#endif
+
+/*
+ * The order of subdivision here is critical for the IO subsystem.
+ * Please do not alter this order without good reasons and regression
+ * testing. Specifically, as large blocks of memory are subdivided,
+ * the order in which smaller blocks are delivered depends on the order
+ * they're subdivided in this function. This is the primary factor
+ * influencing the order in which pages are delivered to the IO
+ * subsystem according to empirical testing, and this is also justified
+ * by considering the behavior of a buddy system containing a single
+ * large block of memory acted on by a series of small allocations.
+ * This behavior is a critical factor in sglist merging's success.
+ *
+ * -- nyc
+ */
+static inline void expand(struct zone *zone, struct page *page,
+	int low, int high, struct free_area *area,
+	int migratetype)
+{
+	unsigned long size = 1 << high;
+
+	while (high > low) {
+		area--;
+		high--;
+		size >>= 1;
+		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
+
+		if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) &&
+			debug_guardpage_enabled() &&
+			high < debug_guardpage_minorder()) {
+			/*
+			 * Mark as guard pages (or page), that will allow to
+			 * merge back to allocator when buddy will be freed.
+			 * Corresponding page table entries will not be touched,
+			 * pages will stay not present in virtual address space
+			 */
+			set_page_guard(zone, &page[size], high, migratetype);
+			continue;
+		}
+		list_add(&page[size].lru, &area->free_list[migratetype]);
+		area->nr_free++;
+		set_page_order(&page[size], high);
+	}
+}
+
+/*
+ * This page is about to be returned from the page allocator
+ */
+static inline int check_new_page(struct page *page)
+{
+	const char *bad_reason = NULL;
+	unsigned long bad_flags = 0;
+
+	if (unlikely(page_mapcount(page)))
+		bad_reason = "nonzero mapcount";
+	if (unlikely(page->mapping != NULL))
+		bad_reason = "non-NULL mapping";
+	if (unlikely(atomic_read(&page->_count) != 0))
+		bad_reason = "nonzero _count";
+	if (unlikely(page->flags & __PG_HWPOISON)) {
+		bad_reason = "HWPoisoned (hardware-corrupted)";
+		bad_flags = __PG_HWPOISON;
+	}
+	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) {
+		bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
+		bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
+	}
+#ifdef CONFIG_MEMCG
+	if (unlikely(page->mem_cgroup))
+		bad_reason = "page still charged to cgroup";
+#endif
+	if (unlikely(bad_reason)) {
+		bad_page(page, bad_reason, bad_flags);
+		return 1;
+	}
+	return 0;
+}
+
+static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
+								int alloc_flags)
+{
+	int i;
+
+	for (i = 0; i < (1 << order); i++) {
+		struct page *p = page + i;
+		if (unlikely(check_new_page(p)))
+			return 1;
+	}
+
+	set_page_private(page, 0);
+	set_page_refcounted(page);
+
+	arch_alloc_page(page, order);
+	kernel_map_pages(page, 1 << order, 1);
+	kasan_alloc_pages(page, order);
+
+	if (gfp_flags & __GFP_ZERO)
+		for (i = 0; i < (1 << order); i++)
+			clear_highpage(page + i);
+
+	if (order && (gfp_flags & __GFP_COMP))
+		prep_compound_page(page, order);
+
+	set_page_owner(page, order, gfp_flags);
+
+	/*
+	 * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
+	 * allocate the page. The expectation is that the caller is taking
+	 * steps that will free more memory. The caller should avoid the page
+	 * being used for !PFMEMALLOC purposes.
+	 */
+	if (alloc_flags & ALLOC_NO_WATERMARKS)
+		set_page_pfmemalloc(page);
+	else
+		clear_page_pfmemalloc(page);
+
+	return 0;
+}
+
+/*
+ * Go through the free lists for the given migratetype and remove
+ * the smallest available page from the freelists
+ */
+static inline
+struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
+						int migratetype)
+{
+	unsigned int current_order;
+	struct free_area *area;
+	struct page *page;
+
+	/* Find a page of the appropriate size in the preferred list */
+	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
+		area = &(zone->free_area[current_order]);
+		if (list_empty(&area->free_list[migratetype]))
+			continue;
+
+		page = list_entry(area->free_list[migratetype].next,
+							struct page, lru);
+		list_del(&page->lru);
+		rmv_page_order(page);
+		area->nr_free--;
+		expand(zone, page, order, current_order, area, migratetype);
+		set_pcppage_migratetype(page, migratetype);
+		return page;
+	}
+
+	return NULL;
+}
+
+
+/*
+ * This array describes the order lists are fallen back to when
+ * the free lists for the desirable migrate type are depleted
+ */
+static int fallbacks[MIGRATE_TYPES][4] = {
+	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_TYPES },
+	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_TYPES },
+	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
+#ifdef CONFIG_CMA
+	[MIGRATE_CMA]         = { MIGRATE_TYPES }, /* Never used */
+#endif
+#ifdef CONFIG_MEMORY_ISOLATION
+	[MIGRATE_ISOLATE]     = { MIGRATE_TYPES }, /* Never used */
+#endif
+};
+
+#ifdef CONFIG_CMA
+static struct page *__rmqueue_cma_fallback(struct zone *zone,
+					unsigned int order)
+{
+	return __rmqueue_smallest(zone, order, MIGRATE_CMA);
+}
+#else
+static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
+					unsigned int order) { return NULL; }
+#endif
+
+/*
+ * Move the free pages in a range to the free lists of the requested type.
+ * Note that start_page and end_pages are not aligned on a pageblock
+ * boundary. If alignment is required, use move_freepages_block()
+ */
+int move_freepages(struct zone *zone,
+			  struct page *start_page, struct page *end_page,
+			  int migratetype)
+{
+	struct page *page;
+	unsigned int order;
+	int pages_moved = 0;
+
+#ifndef CONFIG_HOLES_IN_ZONE
+	/*
+	 * page_zone is not safe to call in this context when
+	 * CONFIG_HOLES_IN_ZONE is set. This bug check is probably redundant
+	 * anyway as we check zone boundaries in move_freepages_block().
+	 * Remove at a later date when no bug reports exist related to
+	 * grouping pages by mobility
+	 */
+	VM_BUG_ON(page_zone(start_page) != page_zone(end_page));
+#endif
+
+	for (page = start_page; page <= end_page;) {
+		if (!pfn_valid_within(page_to_pfn(page))) {
+			page++;
+			continue;
+		}
+
+		/* Make sure we are not inadvertently changing nodes */
+		VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
+
+		if (!PageBuddy(page)) {
+			page++;
+			continue;
+		}
+
+		order = page_order(page);
+		list_move(&page->lru,
+			  &zone->free_area[order].free_list[migratetype]);
+		page += 1 << order;
+		pages_moved += 1 << order;
+	}
+
+	return pages_moved;
+}
+
+int move_freepages_block(struct zone *zone, struct page *page,
+				int migratetype)
+{
+	unsigned long start_pfn, end_pfn;
+	struct page *start_page, *end_page;
+
+	start_pfn = page_to_pfn(page);
+	start_pfn = start_pfn & ~(pageblock_nr_pages-1);
+	start_page = pfn_to_page(start_pfn);
+	end_page = start_page + pageblock_nr_pages - 1;
+	end_pfn = start_pfn + pageblock_nr_pages - 1;
+
+	/* Do not cross zone boundaries */
+	if (!zone_spans_pfn(zone, start_pfn))
+		start_page = page;
+	if (!zone_spans_pfn(zone, end_pfn))
+		return 0;
+
+	return move_freepages(zone, start_page, end_page, migratetype);
+}
+
+static void change_pageblock_range(struct page *pageblock_page,
+					int start_order, int migratetype)
+{
+	int nr_pageblocks = 1 << (start_order - pageblock_order);
+
+	while (nr_pageblocks--) {
+		set_pageblock_migratetype(pageblock_page, migratetype);
+		pageblock_page += pageblock_nr_pages;
+	}
+}
+
+/*
+ * When we are falling back to another migratetype during allocation, try to
+ * steal extra free pages from the same pageblocks to satisfy further
+ * allocations, instead of polluting multiple pageblocks.
+ *
+ * If we are stealing a relatively large buddy page, it is likely there will
+ * be more free pages in the pageblock, so try to steal them all. For
+ * reclaimable and unmovable allocations, we steal regardless of page size,
+ * as fragmentation caused by those allocations polluting movable pageblocks
+ * is worse than movable allocations stealing from unmovable and reclaimable
+ * pageblocks.
+ */
+static bool can_steal_fallback(unsigned int order, int start_mt)
+{
+	/*
+	 * Leaving this order check is intended, although there is
+	 * relaxed order check in next check. The reason is that
+	 * we can actually steal whole pageblock if this condition met,
+	 * but, below check doesn't guarantee it and that is just heuristic
+	 * so could be changed anytime.
+	 */
+	if (order >= pageblock_order)
+		return true;
+
+	if (order >= pageblock_order / 2 ||
+		start_mt == MIGRATE_RECLAIMABLE ||
+		start_mt == MIGRATE_UNMOVABLE ||
+		page_group_by_mobility_disabled)
+		return true;
+
+	return false;
+}
+
+/*
+ * This function implements actual steal behaviour. If order is large enough,
+ * we can steal whole pageblock. If not, we first move freepages in this
+ * pageblock and check whether half of pages are moved or not. If half of
+ * pages are moved, we can change migratetype of pageblock and permanently
+ * use it's pages as requested migratetype in the future.
+ */
+static void steal_suitable_fallback(struct zone *zone, struct page *page,
+							  int start_type)
+{
+	unsigned int current_order = page_order(page);
+	int pages;
+
+	/* Take ownership for orders >= pageblock_order */
+	if (current_order >= pageblock_order) {
+		change_pageblock_range(page, current_order, start_type);
+		return;
+	}
+
+	pages = move_freepages_block(zone, page, start_type);
+
+	/* Claim the whole block if over half of it is free */
+	if (pages >= (1 << (pageblock_order-1)) ||
+			page_group_by_mobility_disabled)
+		set_pageblock_migratetype(page, start_type);
+}
+
+/*
+ * Check whether there is a suitable fallback freepage with requested order.
+ * If only_stealable is true, this function returns fallback_mt only if
+ * we can steal other freepages all together. This would help to reduce
+ * fragmentation due to mixed migratetype pages in one pageblock.
+ */
+int find_suitable_fallback(struct free_area *area, unsigned int order,
+			int migratetype, bool only_stealable, bool *can_steal)
+{
+	int i;
+	int fallback_mt;
+
+	if (area->nr_free == 0)
+		return -1;
+
+	*can_steal = false;
+	for (i = 0;; i++) {
+		fallback_mt = fallbacks[migratetype][i];
+		if (fallback_mt == MIGRATE_TYPES)
+			break;
+
+		if (list_empty(&area->free_list[fallback_mt]))
+			continue;
+
+		if (can_steal_fallback(order, migratetype))
+			*can_steal = true;
+
+		if (!only_stealable)
+			return fallback_mt;
+
+		if (*can_steal)
+			return fallback_mt;
+	}
+
+	return -1;
+}
+
+/*
+ * Reserve a pageblock for exclusive use of high-order atomic allocations if
+ * there are no empty page blocks that contain a page with a suitable order
+ */
+static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
+				unsigned int alloc_order)
+{
+	int mt;
+	unsigned long max_managed, flags;
+
+	/*
+	 * Limit the number reserved to 1 pageblock or roughly 1% of a zone.
+	 * Check is race-prone but harmless.
+	 */
+	max_managed = (zone->managed_pages / 100) + pageblock_nr_pages;
+	if (zone->nr_reserved_highatomic >= max_managed)
+		return;
+
+	spin_lock_irqsave(&zone->lock, flags);
+
+	/* Recheck the nr_reserved_highatomic limit under the lock */
+	if (zone->nr_reserved_highatomic >= max_managed)
+		goto out_unlock;
+
+	/* Yoink! */
+	mt = get_pageblock_migratetype(page);
+	if (mt != MIGRATE_HIGHATOMIC &&
+			!is_migrate_isolate(mt) && !is_migrate_cma(mt)) {
+		zone->nr_reserved_highatomic += pageblock_nr_pages;
+		set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
+		move_freepages_block(zone, page, MIGRATE_HIGHATOMIC);
+	}
+
+out_unlock:
+	spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+/*
+ * Used when an allocation is about to fail under memory pressure. This
+ * potentially hurts the reliability of high-order allocations when under
+ * intense memory pressure but failed atomic allocations should be easier
+ * to recover from than an OOM.
+ */
+static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
+{
+	struct zonelist *zonelist = ac->zonelist;
+	unsigned long flags;
+	struct zoneref *z;
+	struct zone *zone;
+	struct page *page;
+	int order;
+
+	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
+								ac->nodemask) {
+		/* Preserve at least one pageblock */
+		if (zone->nr_reserved_highatomic <= pageblock_nr_pages)
+			continue;
+
+		spin_lock_irqsave(&zone->lock, flags);
+		for (order = 0; order < MAX_ORDER; order++) {
+			struct free_area *area = &(zone->free_area[order]);
+
+			if (list_empty(&area->free_list[MIGRATE_HIGHATOMIC]))
+				continue;
+
+			page = list_entry(area->free_list[MIGRATE_HIGHATOMIC].next,
+						struct page, lru);
+
+			/*
+			 * In page freeing path, migratetype change is racy so
+			 * we can counter several free pages in a pageblock
+			 * in this loop althoug we changed the pageblock type
+			 * from highatomic to ac->migratetype. So we should
+			 * adjust the count once.
+			 */
+			if (get_pageblock_migratetype(page) ==
+							MIGRATE_HIGHATOMIC) {
+				/*
+				 * It should never happen but changes to
+				 * locking could inadvertently allow a per-cpu
+				 * drain to add pages to MIGRATE_HIGHATOMIC
+				 * while unreserving so be safe and watch for
+				 * underflows.
+				 */
+				zone->nr_reserved_highatomic -= min(
+						pageblock_nr_pages,
+						zone->nr_reserved_highatomic);
+			}
+
+			/*
+			 * Convert to ac->migratetype and avoid the normal
+			 * pageblock stealing heuristics. Minimally, the caller
+			 * is doing the work and needs the pages. More
+			 * importantly, if the block was always converted to
+			 * MIGRATE_UNMOVABLE or another type then the number
+			 * of pageblocks that cannot be completely freed
+			 * may increase.
+			 */
+			set_pageblock_migratetype(page, ac->migratetype);
+			move_freepages_block(zone, page, ac->migratetype);
+			spin_unlock_irqrestore(&zone->lock, flags);
+			return;
+		}
+		spin_unlock_irqrestore(&zone->lock, flags);
+	}
+}
+
+/* Remove an element from the buddy allocator from the fallback list */
+static inline struct page *
+__rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype)
+{
+	struct free_area *area;
+	unsigned int current_order;
+	struct page *page;
+	int fallback_mt;
+	bool can_steal;
+
+	/* Find the largest possible block of pages in the other list */
+	for (current_order = MAX_ORDER-1;
+				current_order >= order && current_order <= MAX_ORDER-1;
+				--current_order) {
+		area = &(zone->free_area[current_order]);
+		fallback_mt = find_suitable_fallback(area, current_order,
+				start_migratetype, false, &can_steal);
+		if (fallback_mt == -1)
+			continue;
+
+		page = list_entry(area->free_list[fallback_mt].next,
+						struct page, lru);
+		if (can_steal)
+			steal_suitable_fallback(zone, page, start_migratetype);
+
+		/* Remove the page from the freelists */
+		area->nr_free--;
+		list_del(&page->lru);
+		rmv_page_order(page);
+
+		expand(zone, page, order, current_order, area,
+					start_migratetype);
+		/*
+		 * The pcppage_migratetype may differ from pageblock's
+		 * migratetype depending on the decisions in
+		 * find_suitable_fallback(). This is OK as long as it does not
+		 * differ for MIGRATE_CMA pageblocks. Those can be used as
+		 * fallback only via special __rmqueue_cma_fallback() function
+		 */
+		set_pcppage_migratetype(page, start_migratetype);
+
+		trace_mm_page_alloc_extfrag(page, order, current_order,
+			start_migratetype, fallback_mt);
+
+		return page;
+	}
+
+	return NULL;
+}
+
+/*
+ * Do the hard work of removing an element from the buddy allocator.
+ * Call me with the zone->lock already held.
+ */
+static struct page *__rmqueue(struct zone *zone, unsigned int order,
+				int migratetype, gfp_t gfp_flags)
+{
+	struct page *page;
+
+	page = __rmqueue_smallest(zone, order, migratetype);
+	if (unlikely(!page)) {
+		if (migratetype == MIGRATE_MOVABLE)
+			page = __rmqueue_cma_fallback(zone, order);
+
+		if (!page)
+			page = __rmqueue_fallback(zone, order, migratetype);
+	}
+
+	trace_mm_page_alloc_zone_locked(page, order, migratetype);
+	return page;
+}
+
+/*
+ * Obtain a specified number of elements from the buddy allocator, all under
+ * a single hold of the lock, for efficiency.  Add them to the supplied list.
+ * Returns the number of new pages which were placed at *list.
+ */
+static int rmqueue_bulk(struct zone *zone, unsigned int order,
+			unsigned long count, struct list_head *list,
+			int migratetype, bool cold)
+{
+	int i;
+
+	spin_lock(&zone->lock);
+	for (i = 0; i < count; ++i) {
+		struct page *page = __rmqueue(zone, order, migratetype, 0);
+		if (unlikely(page == NULL))
+			break;
+
+		/*
+		 * Split buddy pages returned by expand() are received here
+		 * in physical page order. The page is added to the callers and
+		 * list and the list head then moves forward. From the callers
+		 * perspective, the linked list is ordered by page number in
+		 * some conditions. This is useful for IO devices that can
+		 * merge IO requests if the physical pages are ordered
+		 * properly.
+		 */
+		if (likely(!cold))
+			list_add(&page->lru, list);
+		else
+			list_add_tail(&page->lru, list);
+		list = &page->lru;
+		if (is_migrate_cma(get_pcppage_migratetype(page)))
+			__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
+					      -(1 << order));
+	}
+	__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
+	spin_unlock(&zone->lock);
+	return i;
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * Called from the vmstat counter updater to drain pagesets of this
+ * currently executing processor on remote nodes after they have
+ * expired.
+ *
+ * Note that this function must be called with the thread pinned to
+ * a single processor.
+ */
+void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
+{
+	unsigned long flags;
+	int to_drain, batch;
+
+	local_irq_save(flags);
+	batch = READ_ONCE(pcp->batch);
+	to_drain = min(pcp->count, batch);
+	if (to_drain > 0) {
+		free_pcppages_bulk(zone, to_drain, pcp);
+		pcp->count -= to_drain;
+	}
+	local_irq_restore(flags);
+}
+#endif
+
+/*
+ * Drain pcplists of the indicated processor and zone.
+ *
+ * The processor must either be the current processor and the
+ * thread pinned to the current processor or a processor that
+ * is not online.
+ */
+static void drain_pages_zone(unsigned int cpu, struct zone *zone)
+{
+	unsigned long flags;
+	struct per_cpu_pageset *pset;
+	struct per_cpu_pages *pcp;
+
+	local_irq_save(flags);
+	pset = per_cpu_ptr(zone->pageset, cpu);
+
+	pcp = &pset->pcp;
+	if (pcp->count) {
+		free_pcppages_bulk(zone, pcp->count, pcp);
+		pcp->count = 0;
+	}
+	local_irq_restore(flags);
+}
+
+/*
+ * Drain pcplists of all zones on the indicated processor.
+ *
+ * The processor must either be the current processor and the
+ * thread pinned to the current processor or a processor that
+ * is not online.
+ */
+static void drain_pages(unsigned int cpu)
+{
+	struct zone *zone;
+
+	for_each_populated_zone(zone) {
+		drain_pages_zone(cpu, zone);
+	}
+}
+
+/*
+ * Spill all of this CPU's per-cpu pages back into the buddy allocator.
+ *
+ * The CPU has to be pinned. When zone parameter is non-NULL, spill just
+ * the single zone's pages.
+ */
+void drain_local_pages(struct zone *zone)
+{
+	int cpu = smp_processor_id();
+
+	if (zone)
+		drain_pages_zone(cpu, zone);
+	else
+		drain_pages(cpu);
+}
+
+/*
+ * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
+ *
+ * When zone parameter is non-NULL, spill just the single zone's pages.
+ *
+ * Note that this code is protected against sending an IPI to an offline
+ * CPU but does not guarantee sending an IPI to newly hotplugged CPUs:
+ * on_each_cpu_mask() blocks hotplug and won't talk to offlined CPUs but
+ * nothing keeps CPUs from showing up after we populated the cpumask and
+ * before the call to on_each_cpu_mask().
+ */
+void drain_all_pages(struct zone *zone)
+{
+	int cpu;
+
+	/*
+	 * Allocate in the BSS so we wont require allocation in
+	 * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
+	 */
+	static cpumask_t cpus_with_pcps;
+
+	/*
+	 * We don't care about racing with CPU hotplug event
+	 * as offline notification will cause the notified
+	 * cpu to drain that CPU pcps and on_each_cpu_mask
+	 * disables preemption as part of its processing
+	 */
+	for_each_online_cpu(cpu) {
+		struct per_cpu_pageset *pcp;
+		struct zone *z;
+		bool has_pcps = false;
+
+		if (zone) {
+			pcp = per_cpu_ptr(zone->pageset, cpu);
+			if (pcp->pcp.count)
+				has_pcps = true;
+		} else {
+			for_each_populated_zone(z) {
+				pcp = per_cpu_ptr(z->pageset, cpu);
+				if (pcp->pcp.count) {
+					has_pcps = true;
+					break;
+				}
+			}
+		}
+
+		if (has_pcps)
+			cpumask_set_cpu(cpu, &cpus_with_pcps);
+		else
+			cpumask_clear_cpu(cpu, &cpus_with_pcps);
+	}
+	on_each_cpu_mask(&cpus_with_pcps, (smp_call_func_t) drain_local_pages,
+								zone, 1);
+}
+
+#ifdef CONFIG_HIBERNATION
+
+void mark_free_pages(struct zone *zone)
+{
+	unsigned long pfn, max_zone_pfn;
+	unsigned long flags;
+	unsigned int order, t;
+	struct list_head *curr;
+
+	if (zone_is_empty(zone))
+		return;
+
+	spin_lock_irqsave(&zone->lock, flags);
+
+	max_zone_pfn = zone_end_pfn(zone);
+	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+		if (pfn_valid(pfn)) {
+			struct page *page = pfn_to_page(pfn);
+
+			if (!swsusp_page_is_forbidden(page))
+				swsusp_unset_page_free(page);
+		}
+
+	for_each_migratetype_order(order, t) {
+		list_for_each(curr, &zone->free_area[order].free_list[t]) {
+			unsigned long i;
+
+			pfn = page_to_pfn(list_entry(curr, struct page, lru));
+			for (i = 0; i < (1UL << order); i++)
+				swsusp_set_page_free(pfn_to_page(pfn + i));
+		}
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+}
+#endif /* CONFIG_PM */
+
+/*
+ * Free a 0-order page
+ * cold == true ? free a cold page : free a hot page
+ */
+void free_hot_cold_page(struct page *page, bool cold)
+{
+	struct zone *zone = page_zone(page);
+	struct per_cpu_pages *pcp;
+	unsigned long flags;
+	unsigned long pfn = page_to_pfn(page);
+	int migratetype;
+
+	if (!free_pages_prepare(page, 0))
+		return;
+
+	migratetype = get_pfnblock_migratetype(page, pfn);
+	set_pcppage_migratetype(page, migratetype);
+	local_irq_save(flags);
+	__count_vm_event(PGFREE);
+
+	/*
+	 * We only track unmovable, reclaimable and movable on pcp lists.
+	 * Free ISOLATE pages back to the allocator because they are being
+	 * offlined but treat RESERVE as movable pages so we can get those
+	 * areas back if necessary. Otherwise, we may have to free
+	 * excessively into the page allocator
+	 */
+	if (migratetype >= MIGRATE_PCPTYPES) {
+		if (unlikely(is_migrate_isolate(migratetype))) {
+			free_one_page(zone, page, pfn, 0, migratetype);
+			goto out;
+		}
+		migratetype = MIGRATE_MOVABLE;
+	}
+
+	pcp = &this_cpu_ptr(zone->pageset)->pcp;
+	if (!cold)
+		list_add(&page->lru, &pcp->lists[migratetype]);
+	else
+		list_add_tail(&page->lru, &pcp->lists[migratetype]);
+	pcp->count++;
+	if (pcp->count >= pcp->high) {
+		unsigned long batch = READ_ONCE(pcp->batch);
+		free_pcppages_bulk(zone, batch, pcp);
+		pcp->count -= batch;
+	}
+
+out:
+	local_irq_restore(flags);
+}
+
+/*
+ * Free a list of 0-order pages
+ */
+void free_hot_cold_page_list(struct list_head *list, bool cold)
+{
+	struct page *page, *next;
+
+	list_for_each_entry_safe(page, next, list, lru) {
+		trace_mm_page_free_batched(page, cold);
+		free_hot_cold_page(page, cold);
+	}
+}
+
+/*
+ * split_page takes a non-compound higher-order page, and splits it into
+ * n (1<<order) sub-pages: page[0..n]
+ * Each sub-page must be freed individually.
+ *
+ * Note: this is probably too low level an operation for use in drivers.
+ * Please consult with lkml before using this in your driver.
+ */
+void split_page(struct page *page, unsigned int order)
+{
+	int i;
+	gfp_t gfp_mask;
+
+	VM_BUG_ON_PAGE(PageCompound(page), page);
+	VM_BUG_ON_PAGE(!page_count(page), page);
+
+#ifdef CONFIG_KMEMCHECK
+	/*
+	 * Split shadow pages too, because free(page[0]) would
+	 * otherwise free the whole shadow.
+	 */
+	if (kmemcheck_page_is_tracked(page))
+		split_page(virt_to_page(page[0].shadow), order);
+#endif
+
+	gfp_mask = get_page_owner_gfp(page);
+	set_page_owner(page, 0, gfp_mask);
+	for (i = 1; i < (1 << order); i++) {
+		set_page_refcounted(page + i);
+		set_page_owner(page + i, 0, gfp_mask);
+	}
+}
+EXPORT_SYMBOL_GPL(split_page);
+
+int __isolate_free_page(struct page *page, unsigned int order)
+{
+	unsigned long watermark;
+	struct zone *zone;
+	int mt;
+
+	BUG_ON(!PageBuddy(page));
+
+	zone = page_zone(page);
+	mt = get_pageblock_migratetype(page);
+
+	if (!is_migrate_isolate(mt)) {
+		/* Obey watermarks as if the page was being allocated */
+		watermark = low_wmark_pages(zone) + (1 << order);
+		if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+			return 0;
+
+		__mod_zone_freepage_state(zone, -(1UL << order), mt);
+	}
+
+	/* Remove page from free list */
+	list_del(&page->lru);
+	zone->free_area[order].nr_free--;
+	rmv_page_order(page);
+
+	set_page_owner(page, order, __GFP_MOVABLE);
+
+	/* Set the pageblock if the isolated page is at least a pageblock */
+	if (order >= pageblock_order - 1) {
+		struct page *endpage = page + (1 << order) - 1;
+		for (; page < endpage; page += pageblock_nr_pages) {
+			int mt = get_pageblock_migratetype(page);
+			if (!is_migrate_isolate(mt) && !is_migrate_cma(mt))
+				set_pageblock_migratetype(page,
+							  MIGRATE_MOVABLE);
+		}
+	}
+
+
+	return 1UL << order;
+}
+
+/*
+ * Similar to split_page except the page is already free. As this is only
+ * being used for migration, the migratetype of the block also changes.
+ * As this is called with interrupts disabled, the caller is responsible
+ * for calling arch_alloc_page() and kernel_map_page() after interrupts
+ * are enabled.
+ *
+ * Note: this is probably too low level an operation for use in drivers.
+ * Please consult with lkml before using this in your driver.
+ */
+int split_free_page(struct page *page)
+{
+	unsigned int order;
+	int nr_pages;
+
+	order = page_order(page);
+
+	nr_pages = __isolate_free_page(page, order);
+	if (!nr_pages)
+		return 0;
+
+	/* Split into individual pages */
+	set_page_refcounted(page);
+	split_page(page, order);
+	return nr_pages;
+}
+
+/*
+ * Allocate a page from the given zone. Use pcplists for order-0 allocations.
+ */
+static inline
+struct page *buffered_rmqueue(struct zone *preferred_zone,
+			struct zone *zone, unsigned int order,
+			gfp_t gfp_flags, int alloc_flags, int migratetype)
+{
+	unsigned long flags;
+	struct page *page;
+	bool cold = ((gfp_flags & __GFP_COLD) != 0);
+
+	if (likely(order == 0)) {
+		struct per_cpu_pages *pcp;
+		struct list_head *list;
+
+		local_irq_save(flags);
+		pcp = &this_cpu_ptr(zone->pageset)->pcp;
+		list = &pcp->lists[migratetype];
+		if (list_empty(list)) {
+			pcp->count += rmqueue_bulk(zone, 0,
+					pcp->batch, list,
+					migratetype, cold);
+			if (unlikely(list_empty(list)))
+				goto failed;
+		}
+
+		if (cold)
+			page = list_entry(list->prev, struct page, lru);
+		else
+			page = list_entry(list->next, struct page, lru);
+
+		list_del(&page->lru);
+		pcp->count--;
+	} else {
+		if (unlikely(gfp_flags & __GFP_NOFAIL)) {
+			/*
+			 * __GFP_NOFAIL is not to be used in new code.
+			 *
+			 * All __GFP_NOFAIL callers should be fixed so that they
+			 * properly detect and handle allocation failures.
+			 *
+			 * We most definitely don't want callers attempting to
+			 * allocate greater than order-1 page units with
+			 * __GFP_NOFAIL.
+			 */
+			WARN_ON_ONCE(order > 1);
+		}
+		spin_lock_irqsave(&zone->lock, flags);
+
+		page = NULL;
+		if (alloc_flags & ALLOC_HARDER) {
+			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
+			if (page)
+				trace_mm_page_alloc_zone_locked(page, order, migratetype);
+		}
+		if (!page)
+			page = __rmqueue(zone, order, migratetype, gfp_flags);
+		spin_unlock(&zone->lock);
+		if (!page)
+			goto failed;
+		__mod_zone_freepage_state(zone, -(1 << order),
+					  get_pcppage_migratetype(page));
+	}
+
+	__mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
+	if (atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]) <= 0 &&
+	    !test_bit(ZONE_FAIR_DEPLETED, &zone->flags))
+		set_bit(ZONE_FAIR_DEPLETED, &zone->flags);
+
+	__count_zone_vm_events(PGALLOC, zone, 1 << order);
+	zone_statistics(preferred_zone, zone, gfp_flags);
+	local_irq_restore(flags);
+
+	VM_BUG_ON_PAGE(bad_range(zone, page), page);
+	return page;
+
+failed:
+	local_irq_restore(flags);
+	return NULL;
+}
+
+#ifdef CONFIG_FAIL_PAGE_ALLOC
+
+static struct {
+	struct fault_attr attr;
+
+	bool ignore_gfp_highmem;
+	bool ignore_gfp_reclaim;
+	u32 min_order;
+} fail_page_alloc = {
+	.attr = FAULT_ATTR_INITIALIZER,
+	.ignore_gfp_reclaim = true,
+	.ignore_gfp_highmem = true,
+	.min_order = 1,
+};
+
+static int __init setup_fail_page_alloc(char *str)
+{
+	return setup_fault_attr(&fail_page_alloc.attr, str);
+}
+__setup("fail_page_alloc=", setup_fail_page_alloc);
+
+static bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
+{
+	if (order < fail_page_alloc.min_order)
+		return false;
+	if (gfp_mask & __GFP_NOFAIL)
+		return false;
+	if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
+		return false;
+	if (fail_page_alloc.ignore_gfp_reclaim &&
+			(gfp_mask & __GFP_DIRECT_RECLAIM))
+		return false;
+
+	return should_fail(&fail_page_alloc.attr, 1 << order);
+}
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+static int __init fail_page_alloc_debugfs(void)
+{
+	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+	struct dentry *dir;
+
+	dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
+					&fail_page_alloc.attr);
+	if (IS_ERR(dir))
+		return PTR_ERR(dir);
+
+	if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
+				&fail_page_alloc.ignore_gfp_reclaim))
+		goto fail;
+	if (!debugfs_create_bool("ignore-gfp-highmem", mode, dir,
+				&fail_page_alloc.ignore_gfp_highmem))
+		goto fail;
+	if (!debugfs_create_u32("min-order", mode, dir,
+				&fail_page_alloc.min_order))
+		goto fail;
+
+	return 0;
+fail:
+	debugfs_remove_recursive(dir);
+
+	return -ENOMEM;
+}
+
+late_initcall(fail_page_alloc_debugfs);
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
+
+#else /* CONFIG_FAIL_PAGE_ALLOC */
+
+static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
+{
+	return false;
+}
+
+#endif /* CONFIG_FAIL_PAGE_ALLOC */
+
+/*
+ * Return true if free base pages are above 'mark'. For high-order checks it
+ * will return true of the order-0 watermark is reached and there is at least
+ * one free page of a suitable size. Checking now avoids taking the zone lock
+ * to check in the allocation paths if no pages are free.
+ */
+static bool __zone_watermark_ok(struct zone *z, unsigned int order,
+			unsigned long mark, int classzone_idx, int alloc_flags,
+			long free_pages)
+{
+	long min = mark;
+	int o;
+	const int alloc_harder = (alloc_flags & ALLOC_HARDER);
+
+	/* free_pages may go negative - that's OK */
+	free_pages -= (1 << order) - 1;
+
+	if (alloc_flags & ALLOC_HIGH)
+		min -= min / 2;
+
+	/*
+	 * If the caller does not have rights to ALLOC_HARDER then subtract
+	 * the high-atomic reserves. This will over-estimate the size of the
+	 * atomic reserve but it avoids a search.
+	 */
+	if (likely(!alloc_harder))
+		free_pages -= z->nr_reserved_highatomic;
+	else
+		min -= min / 4;
+
+#ifdef CONFIG_CMA
+	/* If allocation can't use CMA areas don't use free CMA pages */
+	if (!(alloc_flags & ALLOC_CMA))
+		free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
+#endif
+
+	/*
+	 * Check watermarks for an order-0 allocation request. If these
+	 * are not met, then a high-order request also cannot go ahead
+	 * even if a suitable page happened to be free.
+	 */
+	if (free_pages <= min + z->lowmem_reserve[classzone_idx])
+		return false;
+
+	/* If this is an order-0 request then the watermark is fine */
+	if (!order)
+		return true;
+
+	/* For a high-order request, check at least one suitable page is free */
+	for (o = order; o < MAX_ORDER; o++) {
+		struct free_area *area = &z->free_area[o];
+		int mt;
+
+		if (!area->nr_free)
+			continue;
+
+		if (alloc_harder)
+			return true;
+
+		for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
+			if (!list_empty(&area->free_list[mt]))
+				return true;
+		}
+
+#ifdef CONFIG_CMA
+		if ((alloc_flags & ALLOC_CMA) &&
+		    !list_empty(&area->free_list[MIGRATE_CMA])) {
+			return true;
+		}
+#endif
+	}
+	return false;
+}
+
+bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
+		      int classzone_idx, int alloc_flags)
+{
+	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
+					zone_page_state(z, NR_FREE_PAGES));
+}
+
+bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
+			unsigned long mark, int classzone_idx)
+{
+	long free_pages = zone_page_state(z, NR_FREE_PAGES);
+
+	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
+		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
+
+	return __zone_watermark_ok(z, order, mark, classzone_idx, 0,
+								free_pages);
+}
+
+#ifdef CONFIG_NUMA
+static bool zone_local(struct zone *local_zone, struct zone *zone)
+{
+	return local_zone->node == zone->node;
+}
+
+static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
+{
+	return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
+				RECLAIM_DISTANCE;
+}
+#else	/* CONFIG_NUMA */
+static bool zone_local(struct zone *local_zone, struct zone *zone)
+{
+	return true;
+}
+
+static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
+{
+	return true;
+}
+#endif	/* CONFIG_NUMA */
+
+static void reset_alloc_batches(struct zone *preferred_zone)
+{
+	struct zone *zone = preferred_zone->zone_pgdat->node_zones;
+
+	do {
+		mod_zone_page_state(zone, NR_ALLOC_BATCH,
+			high_wmark_pages(zone) - low_wmark_pages(zone) -
+			atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]));
+		clear_bit(ZONE_FAIR_DEPLETED, &zone->flags);
+	} while (zone++ != preferred_zone);
+}
+
+/*
+ * get_page_from_freelist goes through the zonelist trying to allocate
+ * a page.
+ */
+static struct page *
+get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
+						const struct alloc_context *ac)
+{
+	struct zonelist *zonelist = ac->zonelist;
+	struct zoneref *z;
+	struct page *page = NULL;
+	struct zone *zone;
+	int nr_fair_skipped = 0;
+	bool zonelist_rescan;
+
+zonelist_scan:
+	zonelist_rescan = false;
+
+	/*
+	 * Scan zonelist, looking for a zone with enough free.
+	 * See also __cpuset_node_allowed() comment in kernel/cpuset.c.
+	 */
+	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
+								ac->nodemask) {
+		unsigned long mark;
+
+		if (cpusets_enabled() &&
+			(alloc_flags & ALLOC_CPUSET) &&
+			!cpuset_zone_allowed(zone, gfp_mask))
+				continue;
+		/*
+		 * Distribute pages in proportion to the individual
+		 * zone size to ensure fair page aging.  The zone a
+		 * page was allocated in should have no effect on the
+		 * time the page has in memory before being reclaimed.
+		 */
+		if (alloc_flags & ALLOC_FAIR) {
+			if (!zone_local(ac->preferred_zone, zone))
+				break;
+			if (test_bit(ZONE_FAIR_DEPLETED, &zone->flags)) {
+				nr_fair_skipped++;
+				continue;
+			}
+		}
+		/*
+		 * When allocating a page cache page for writing, we
+		 * want to get it from a zone that is within its dirty
+		 * limit, such that no single zone holds more than its
+		 * proportional share of globally allowed dirty pages.
+		 * The dirty limits take into account the zone's
+		 * lowmem reserves and high watermark so that kswapd
+		 * should be able to balance it without having to
+		 * write pages from its LRU list.
+		 *
+		 * This may look like it could increase pressure on
+		 * lower zones by failing allocations in higher zones
+		 * before they are full.  But the pages that do spill
+		 * over are limited as the lower zones are protected
+		 * by this very same mechanism.  It should not become
+		 * a practical burden to them.
+		 *
+		 * XXX: For now, allow allocations to potentially
+		 * exceed the per-zone dirty limit in the slowpath
+		 * (spread_dirty_pages unset) before going into reclaim,
+		 * which is important when on a NUMA setup the allowed
+		 * zones are together not big enough to reach the
+		 * global limit.  The proper fix for these situations
+		 * will require awareness of zones in the
+		 * dirty-throttling and the flusher threads.
+		 */
+		if (ac->spread_dirty_pages && !zone_dirty_ok(zone))
+			continue;
+
+		mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
+		if (!zone_watermark_ok(zone, order, mark,
+				       ac->classzone_idx, alloc_flags)) {
+			int ret;
+
+			/* Checked here to keep the fast path fast */
+			BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
+			if (alloc_flags & ALLOC_NO_WATERMARKS)
+				goto try_this_zone;
+
+			if (zone_reclaim_mode == 0 ||
+			    !zone_allows_reclaim(ac->preferred_zone, zone))
+				continue;
+
+			ret = zone_reclaim(zone, gfp_mask, order);
+			switch (ret) {
+			case ZONE_RECLAIM_NOSCAN:
+				/* did not scan */
+				continue;
+			case ZONE_RECLAIM_FULL:
+				/* scanned but unreclaimable */
+				continue;
+			default:
+				/* did we reclaim enough */
+				if (zone_watermark_ok(zone, order, mark,
+						ac->classzone_idx, alloc_flags))
+					goto try_this_zone;
+
+				continue;
+			}
+		}
+
+try_this_zone:
+		page = buffered_rmqueue(ac->preferred_zone, zone, order,
+				gfp_mask, alloc_flags, ac->migratetype);
+		if (page) {
+			if (prep_new_page(page, order, gfp_mask, alloc_flags))
+				goto try_this_zone;
+
+			/*
+			 * If this is a high-order atomic allocation then check
+			 * if the pageblock should be reserved for the future
+			 */
+			if (unlikely(order && (alloc_flags & ALLOC_HARDER)))
+				reserve_highatomic_pageblock(page, zone, order);
+
+			return page;
+		}
+	}
+
+	/*
+	 * The first pass makes sure allocations are spread fairly within the
+	 * local node.  However, the local node might have free pages left
+	 * after the fairness batches are exhausted, and remote zones haven't
+	 * even been considered yet.  Try once more without fairness, and
+	 * include remote zones now, before entering the slowpath and waking
+	 * kswapd: prefer spilling to a remote zone over swapping locally.
+	 */
+	if (alloc_flags & ALLOC_FAIR) {
+		alloc_flags &= ~ALLOC_FAIR;
+		if (nr_fair_skipped) {
+			zonelist_rescan = true;
+			reset_alloc_batches(ac->preferred_zone);
+		}
+		if (nr_online_nodes > 1)
+			zonelist_rescan = true;
+	}
+
+	if (zonelist_rescan)
+		goto zonelist_scan;
+
+	return NULL;
+}
+
+/*
+ * Large machines with many possible nodes should not always dump per-node
+ * meminfo in irq context.
+ */
+static inline bool should_suppress_show_mem(void)
+{
+	bool ret = false;
+
+#if NODES_SHIFT > 8
+	ret = in_interrupt();
+#endif
+	return ret;
+}
+
+static DEFINE_RATELIMIT_STATE(nopage_rs,
+		DEFAULT_RATELIMIT_INTERVAL,
+		DEFAULT_RATELIMIT_BURST);
+
+void warn_alloc_failed(gfp_t gfp_mask, unsigned int order, const char *fmt, ...)
+{
+	unsigned int filter = SHOW_MEM_FILTER_NODES;
+
+	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) ||
+	    debug_guardpage_minorder() > 0)
+		return;
+
+	/*
+	 * This documents exceptions given to allocations in certain
+	 * contexts that are allowed to allocate outside current's set
+	 * of allowed nodes.
+	 */
+	if (!(gfp_mask & __GFP_NOMEMALLOC))
+		if (test_thread_flag(TIF_MEMDIE) ||
+		    (current->flags & (PF_MEMALLOC | PF_EXITING)))
+			filter &= ~SHOW_MEM_FILTER_NODES;
+	if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
+		filter &= ~SHOW_MEM_FILTER_NODES;
+
+	if (fmt) {
+		struct va_format vaf;
+		va_list args;
+
+		va_start(args, fmt);
+
+		vaf.fmt = fmt;
+		vaf.va = &args;
+
+		pr_warn("%pV", &vaf);
+
+		va_end(args);
+	}
+
+	pr_warn("%s: page allocation failure: order:%u, mode:0x%x\n",
+		current->comm, order, gfp_mask);
+
+	dump_stack();
+	if (!should_suppress_show_mem())
+		show_mem(filter);
+}
+
+static inline struct page *
+__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
+	const struct alloc_context *ac, unsigned long *did_some_progress)
+{
+	struct oom_control oc = {
+		.zonelist = ac->zonelist,
+		.nodemask = ac->nodemask,
+		.gfp_mask = gfp_mask,
+		.order = order,
+	};
+	struct page *page;
+
+	*did_some_progress = 0;
+
+	/*
+	 * Acquire the oom lock.  If that fails, somebody else is
+	 * making progress for us.
+	 */
+	if (!mutex_trylock(&oom_lock)) {
+		*did_some_progress = 1;
+		schedule_timeout_uninterruptible(1);
+		return NULL;
+	}
+
+	/*
+	 * Go through the zonelist yet one more time, keep very high watermark
+	 * here, this is only to catch a parallel oom killing, we must fail if
+	 * we're still under heavy pressure.
+	 */
+	page = get_page_from_freelist(gfp_mask | __GFP_HARDWALL, order,
+					ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
+	if (page)
+		goto out;
+
+	if (!(gfp_mask & __GFP_NOFAIL)) {
+		/* Coredumps can quickly deplete all memory reserves */
+		if (current->flags & PF_DUMPCORE)
+			goto out;
+		/* The OOM killer will not help higher order allocs */
+		if (order > PAGE_ALLOC_COSTLY_ORDER)
+			goto out;
+		/* The OOM killer does not needlessly kill tasks for lowmem */
+		if (ac->high_zoneidx < ZONE_NORMAL)
+			goto out;
+		/* The OOM killer does not compensate for IO-less reclaim */
+		if (!(gfp_mask & __GFP_FS)) {
+			/*
+			 * XXX: Page reclaim didn't yield anything,
+			 * and the OOM killer can't be invoked, but
+			 * keep looping as per tradition.
+			 */
+			*did_some_progress = 1;
+			goto out;
+		}
+		if (pm_suspended_storage())
+			goto out;
+		/* The OOM killer may not free memory on a specific node */
+		if (gfp_mask & __GFP_THISNODE)
+			goto out;
+	}
+	/* Exhausted what can be done so it's blamo time */
+	if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
+		*did_some_progress = 1;
+out:
+	mutex_unlock(&oom_lock);
+	return page;
+}
+
+#ifdef CONFIG_COMPACTION
+/* Try memory compaction for high-order allocations before reclaim */
+static struct page *
+__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
+		int alloc_flags, const struct alloc_context *ac,
+		enum migrate_mode mode, int *contended_compaction,
+		bool *deferred_compaction)
+{
+	unsigned long compact_result;
+	struct page *page;
+
+	if (!order)
+		return NULL;
+
+	current->flags |= PF_MEMALLOC;
+	compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
+						mode, contended_compaction);
+	current->flags &= ~PF_MEMALLOC;
+
+	switch (compact_result) {
+	case COMPACT_DEFERRED:
+		*deferred_compaction = true;
+		/* fall-through */
+	case COMPACT_SKIPPED:
+		return NULL;
+	default:
+		break;
+	}
+
+	/*
+	 * At least in one zone compaction wasn't deferred or skipped, so let's
+	 * count a compaction stall
+	 */
+	count_vm_event(COMPACTSTALL);
+
+	page = get_page_from_freelist(gfp_mask, order,
+					alloc_flags & ~ALLOC_NO_WATERMARKS, ac);
+
+	if (page) {
+		struct zone *zone = page_zone(page);
+
+		zone->compact_blockskip_flush = false;
+		compaction_defer_reset(zone, order, true);
+		count_vm_event(COMPACTSUCCESS);
+		return page;
+	}
+
+	/*
+	 * It's bad if compaction run occurs and fails. The most likely reason
+	 * is that pages exist, but not enough to satisfy watermarks.
+	 */
+	count_vm_event(COMPACTFAIL);
+
+	cond_resched();
+
+	return NULL;
+}
+#else
+static inline struct page *
+__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
+		int alloc_flags, const struct alloc_context *ac,
+		enum migrate_mode mode, int *contended_compaction,
+		bool *deferred_compaction)
+{
+	return NULL;
+}
+#endif /* CONFIG_COMPACTION */
+
+/* Perform direct synchronous page reclaim */
+static int
+__perform_reclaim(gfp_t gfp_mask, unsigned int order,
+					const struct alloc_context *ac)
+{
+	struct reclaim_state reclaim_state;
+	int progress;
+
+	cond_resched();
+
+	/* We now go into synchronous reclaim */
+	cpuset_memory_pressure_bump();
+	current->flags |= PF_MEMALLOC;
+	lockdep_set_current_reclaim_state(gfp_mask);
+	reclaim_state.reclaimed_slab = 0;
+	current->reclaim_state = &reclaim_state;
+
+	progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
+								ac->nodemask);
+
+	current->reclaim_state = NULL;
+	lockdep_clear_current_reclaim_state();
+	current->flags &= ~PF_MEMALLOC;
+
+	cond_resched();
+
+	return progress;
+}
+
+/* The really slow allocator path where we enter direct reclaim */
+static inline struct page *
+__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
+		int alloc_flags, const struct alloc_context *ac,
+		unsigned long *did_some_progress)
+{
+	struct page *page = NULL;
+	bool drained = false;
+
+	*did_some_progress = __perform_reclaim(gfp_mask, order, ac);
+	if (unlikely(!(*did_some_progress)))
+		return NULL;
+
+retry:
+	page = get_page_from_freelist(gfp_mask, order,
+					alloc_flags & ~ALLOC_NO_WATERMARKS, ac);
+
+	/*
+	 * If an allocation failed after direct reclaim, it could be because
+	 * pages are pinned on the per-cpu lists or in high alloc reserves.
+	 * Shrink them them and try again
+	 */
+	if (!page && !drained) {
+		unreserve_highatomic_pageblock(ac);
+		drain_all_pages(NULL);
+		drained = true;
+		goto retry;
+	}
+
+	return page;
+}
+
+/*
+ * This is called in the allocator slow-path if the allocation request is of
+ * sufficient urgency to ignore watermarks and take other desperate measures
+ */
+static inline struct page *
+__alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
+				const struct alloc_context *ac)
+{
+	struct page *page;
+
+	do {
+		page = get_page_from_freelist(gfp_mask, order,
+						ALLOC_NO_WATERMARKS, ac);
+
+		if (!page && gfp_mask & __GFP_NOFAIL)
+			wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC,
+									HZ/50);
+	} while (!page && (gfp_mask & __GFP_NOFAIL));
+
+	return page;
+}
+
+static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac)
+{
+	struct zoneref *z;
+	struct zone *zone;
+
+	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
+						ac->high_zoneidx, ac->nodemask)
+		wakeup_kswapd(zone, order, zone_idx(ac->preferred_zone));
+}
+
+static inline int
+gfp_to_alloc_flags(gfp_t gfp_mask)
+{
+	int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
+
+	/* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */
+	BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
+
+	/*
+	 * The caller may dip into page reserves a bit more if the caller
+	 * cannot run direct reclaim, or if the caller has realtime scheduling
+	 * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
+	 * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_HIGH (__GFP_HIGH).
+	 */
+	alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH);
+
+	if (gfp_mask & __GFP_ATOMIC) {
+		/*
+		 * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
+		 * if it can't schedule.
+		 */
+		if (!(gfp_mask & __GFP_NOMEMALLOC))
+			alloc_flags |= ALLOC_HARDER;
+		/*
+		 * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
+		 * comment for __cpuset_node_allowed().
+		 */
+		alloc_flags &= ~ALLOC_CPUSET;
+	} else if (unlikely(rt_task(current)) && !in_interrupt())
+		alloc_flags |= ALLOC_HARDER;
+
+	if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
+		if (gfp_mask & __GFP_MEMALLOC)
+			alloc_flags |= ALLOC_NO_WATERMARKS;
+		else if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
+			alloc_flags |= ALLOC_NO_WATERMARKS;
+		else if (!in_interrupt() &&
+				((current->flags & PF_MEMALLOC) ||
+				 unlikely(test_thread_flag(TIF_MEMDIE))))
+			alloc_flags |= ALLOC_NO_WATERMARKS;
+	}
+#ifdef CONFIG_CMA
+	if (gfpflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+#endif
+	return alloc_flags;
+}
+
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
+{
+	return !!(gfp_to_alloc_flags(gfp_mask) & ALLOC_NO_WATERMARKS);
+}
+
+static inline bool is_thp_gfp_mask(gfp_t gfp_mask)
+{
+	return (gfp_mask & (GFP_TRANSHUGE | __GFP_KSWAPD_RECLAIM)) == GFP_TRANSHUGE;
+}
+
+static inline struct page *
+__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
+						struct alloc_context *ac)
+{
+	bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
+	struct page *page = NULL;
+	int alloc_flags;
+	unsigned long pages_reclaimed = 0;
+	unsigned long did_some_progress;
+	enum migrate_mode migration_mode = MIGRATE_ASYNC;
+	bool deferred_compaction = false;
+	int contended_compaction = COMPACT_CONTENDED_NONE;
+
+	/*
+	 * In the slowpath, we sanity check order to avoid ever trying to
+	 * reclaim >= MAX_ORDER areas which will never succeed. Callers may
+	 * be using allocators in order of preference for an area that is
+	 * too large.
+	 */
+	if (order >= MAX_ORDER) {
+		WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
+		return NULL;
+	}
+
+	/*
+	 * We also sanity check to catch abuse of atomic reserves being used by
+	 * callers that are not in atomic context.
+	 */
+	if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
+				(__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
+		gfp_mask &= ~__GFP_ATOMIC;
+
+	/*
+	 * If this allocation cannot block and it is for a specific node, then
+	 * fail early.  There's no need to wakeup kswapd or retry for a
+	 * speculative node-specific allocation.
+	 */
+	if (IS_ENABLED(CONFIG_NUMA) && (gfp_mask & __GFP_THISNODE) && !can_direct_reclaim)
+		goto nopage;
+
+retry:
+	if (gfp_mask & __GFP_KSWAPD_RECLAIM)
+		wake_all_kswapds(order, ac);
+
+	/*
+	 * OK, we're below the kswapd watermark and have kicked background
+	 * reclaim. Now things get more complex, so set up alloc_flags according
+	 * to how we want to proceed.
+	 */
+	alloc_flags = gfp_to_alloc_flags(gfp_mask);
+
+	/*
+	 * Find the true preferred zone if the allocation is unconstrained by
+	 * cpusets.
+	 */
+	if (!(alloc_flags & ALLOC_CPUSET) && !ac->nodemask) {
+		struct zoneref *preferred_zoneref;
+		preferred_zoneref = first_zones_zonelist(ac->zonelist,
+				ac->high_zoneidx, NULL, &ac->preferred_zone);
+		ac->classzone_idx = zonelist_zone_idx(preferred_zoneref);
+	}
+
+	/* This is the last chance, in general, before the goto nopage. */
+	page = get_page_from_freelist(gfp_mask, order,
+				alloc_flags & ~ALLOC_NO_WATERMARKS, ac);
+	if (page)
+		goto got_pg;
+
+	/* Allocate without watermarks if the context allows */
+	if (alloc_flags & ALLOC_NO_WATERMARKS) {
+		/*
+		 * Ignore mempolicies if ALLOC_NO_WATERMARKS on the grounds
+		 * the allocation is high priority and these type of
+		 * allocations are system rather than user orientated
+		 */
+		ac->zonelist = node_zonelist(numa_node_id(), gfp_mask);
+
+		page = __alloc_pages_high_priority(gfp_mask, order, ac);
+
+		if (page) {
+			goto got_pg;
+		}
+	}
+
+	/* Caller is not willing to reclaim, we can't balance anything */
+	if (!can_direct_reclaim) {
+		/*
+		 * All existing users of the deprecated __GFP_NOFAIL are
+		 * blockable, so warn of any new users that actually allow this
+		 * type of allocation to fail.
+		 */
+		WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL);
+		goto nopage;
+	}
+
+	/* Avoid recursion of direct reclaim */
+	if (current->flags & PF_MEMALLOC)
+		goto nopage;
+
+	/* Avoid allocations with no watermarks from looping endlessly */
+	if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
+		goto nopage;
+
+	/*
+	 * Try direct compaction. The first pass is asynchronous. Subsequent
+	 * attempts after direct reclaim are synchronous
+	 */
+	page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
+					migration_mode,
+					&contended_compaction,
+					&deferred_compaction);
+	if (page)
+		goto got_pg;
+
+	/* Checks for THP-specific high-order allocations */
+	if (is_thp_gfp_mask(gfp_mask)) {
+		/*
+		 * If compaction is deferred for high-order allocations, it is
+		 * because sync compaction recently failed. If this is the case
+		 * and the caller requested a THP allocation, we do not want
+		 * to heavily disrupt the system, so we fail the allocation
+		 * instead of entering direct reclaim.
+		 */
+		if (deferred_compaction)
+			goto nopage;
+
+		/*
+		 * In all zones where compaction was attempted (and not
+		 * deferred or skipped), lock contention has been detected.
+		 * For THP allocation we do not want to disrupt the others
+		 * so we fallback to base pages instead.
+		 */
+		if (contended_compaction == COMPACT_CONTENDED_LOCK)
+			goto nopage;
+
+		/*
+		 * If compaction was aborted due to need_resched(), we do not
+		 * want to further increase allocation latency, unless it is
+		 * khugepaged trying to collapse.
+		 */
+		if (contended_compaction == COMPACT_CONTENDED_SCHED
+			&& !(current->flags & PF_KTHREAD))
+			goto nopage;
+	}
+
+	/*
+	 * It can become very expensive to allocate transparent hugepages at
+	 * fault, so use asynchronous memory compaction for THP unless it is
+	 * khugepaged trying to collapse.
+	 */
+	if (!is_thp_gfp_mask(gfp_mask) || (current->flags & PF_KTHREAD))
+		migration_mode = MIGRATE_SYNC_LIGHT;
+
+	/* Try direct reclaim and then allocating */
+	page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
+							&did_some_progress);
+	if (page)
+		goto got_pg;
+
+	/* Do not loop if specifically requested */
+	if (gfp_mask & __GFP_NORETRY)
+		goto noretry;
+
+	/* Keep reclaiming pages as long as there is reasonable progress */
+	pages_reclaimed += did_some_progress;
+	if ((did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER) ||
+	    ((gfp_mask & __GFP_REPEAT) && pages_reclaimed < (1 << order))) {
+		/* Wait for some write requests to complete then retry */
+		wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, HZ/50);
+		goto retry;
+	}
+
+	/* Reclaim has failed us, start killing things */
+	page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
+	if (page)
+		goto got_pg;
+
+	/* Retry as long as the OOM killer is making progress */
+	if (did_some_progress)
+		goto retry;
+
+noretry:
+	/*
+	 * High-order allocations do not necessarily loop after
+	 * direct reclaim and reclaim/compaction depends on compaction
+	 * being called after reclaim so call directly if necessary
+	 */
+	page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags,
+					    ac, migration_mode,
+					    &contended_compaction,
+					    &deferred_compaction);
+	if (page)
+		goto got_pg;
+nopage:
+	warn_alloc_failed(gfp_mask, order, NULL);
+got_pg:
+	return page;
+}
+
+/*
+ * This is the 'heart' of the zoned buddy allocator.
+ */
+struct page *
+__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
+			struct zonelist *zonelist, nodemask_t *nodemask)
+{
+	struct zoneref *preferred_zoneref;
+	struct page *page = NULL;
+	unsigned int cpuset_mems_cookie;
+	int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR;
+	gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
+	struct alloc_context ac = {
+		.high_zoneidx = gfp_zone(gfp_mask),
+		.nodemask = nodemask,
+		.migratetype = gfpflags_to_migratetype(gfp_mask),
+	};
+
+	gfp_mask &= gfp_allowed_mask;
+
+	lockdep_trace_alloc(gfp_mask);
+
+	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
+
+	if (should_fail_alloc_page(gfp_mask, order))
+		return NULL;
+
+	/*
+	 * Check the zones suitable for the gfp_mask contain at least one
+	 * valid zone. It's possible to have an empty zonelist as a result
+	 * of __GFP_THISNODE and a memoryless node
+	 */
+	if (unlikely(!zonelist->_zonerefs->zone))
+		return NULL;
+
+	if (IS_ENABLED(CONFIG_CMA) && ac.migratetype == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+
+retry_cpuset:
+	cpuset_mems_cookie = read_mems_allowed_begin();
+
+	/* We set it here, as __alloc_pages_slowpath might have changed it */
+	ac.zonelist = zonelist;
+
+	/* Dirty zone balancing only done in the fast path */
+	ac.spread_dirty_pages = (gfp_mask & __GFP_WRITE);
+
+	/* The preferred zone is used for statistics later */
+	preferred_zoneref = first_zones_zonelist(ac.zonelist, ac.high_zoneidx,
+				ac.nodemask ? : &cpuset_current_mems_allowed,
+				&ac.preferred_zone);
+	if (!ac.preferred_zone)
+		goto out;
+	ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);
+
+	/* First allocation attempt */
+	alloc_mask = gfp_mask|__GFP_HARDWALL;
+	page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
+	if (unlikely(!page)) {
+		/*
+		 * Runtime PM, block IO and its error handling path
+		 * can deadlock because I/O on the device might not
+		 * complete.
+		 */
+		alloc_mask = memalloc_noio_flags(gfp_mask);
+		ac.spread_dirty_pages = false;
+
+		page = __alloc_pages_slowpath(alloc_mask, order, &ac);
+	}
+
+	if (kmemcheck_enabled && page)
+		kmemcheck_pagealloc_alloc(page, order, gfp_mask);
+
+	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
+
+out:
+	/*
+	 * When updating a task's mems_allowed, it is possible to race with
+	 * parallel threads in such a way that an allocation can fail while
+	 * the mask is being updated. If a page allocation is about to fail,
+	 * check if the cpuset changed during allocation and if so, retry.
+	 */
+	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
+		goto retry_cpuset;
+
+	return page;
+}
+EXPORT_SYMBOL(__alloc_pages_nodemask);
+
+/*
+ * Common helper functions.
+ */
+unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
+{
+	struct page *page;
+
+	/*
+	 * __get_free_pages() returns a 32-bit address, which cannot represent
+	 * a highmem page
+	 */
+	VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
+
+	page = alloc_pages(gfp_mask, order);
+	if (!page)
+		return 0;
+	return (unsigned long) page_address(page);
+}
+EXPORT_SYMBOL(__get_free_pages);
+
+unsigned long get_zeroed_page(gfp_t gfp_mask)
+{
+	return __get_free_pages(gfp_mask | __GFP_ZERO, 0);
+}
+EXPORT_SYMBOL(get_zeroed_page);
+
+void __free_pages(struct page *page, unsigned int order)
+{
+	if (put_page_testzero(page)) {
+		if (order == 0)
+			free_hot_cold_page(page, false);
+		else
+			__free_pages_ok(page, order);
+	}
+}
+
+EXPORT_SYMBOL(__free_pages);
+
+void free_pages(unsigned long addr, unsigned int order)
+{
+	if (addr != 0) {
+		VM_BUG_ON(!virt_addr_valid((void *)addr));
+		__free_pages(virt_to_page((void *)addr), order);
+	}
+}
+
+EXPORT_SYMBOL(free_pages);
+
+/*
+ * Page Fragment:
+ *  An arbitrary-length arbitrary-offset area of memory which resides
+ *  within a 0 or higher order page.  Multiple fragments within that page
+ *  are individually refcounted, in the page's reference counter.
+ *
+ * The page_frag functions below provide a simple allocation framework for
+ * page fragments.  This is used by the network stack and network device
+ * drivers to provide a backing region of memory for use as either an
+ * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
+ */
+static struct page *__page_frag_refill(struct page_frag_cache *nc,
+				       gfp_t gfp_mask)
+{
+	struct page *page = NULL;
+	gfp_t gfp = gfp_mask;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
+		    __GFP_NOMEMALLOC;
+	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
+				PAGE_FRAG_CACHE_MAX_ORDER);
+	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
+#endif
+	if (unlikely(!page))
+		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
+
+	nc->va = page ? page_address(page) : NULL;
+
+	return page;
+}
+
+void *__alloc_page_frag(struct page_frag_cache *nc,
+			unsigned int fragsz, gfp_t gfp_mask)
+{
+	unsigned int size = PAGE_SIZE;
+	struct page *page;
+	int offset;
+
+	if (unlikely(!nc->va)) {
+refill:
+		page = __page_frag_refill(nc, gfp_mask);
+		if (!page)
+			return NULL;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+		/* if size can vary use size else just use PAGE_SIZE */
+		size = nc->size;
+#endif
+		/* Even if we own the page, we do not use atomic_set().
+		 * This would break get_page_unless_zero() users.
+		 */
+		atomic_add(size - 1, &page->_count);
+
+		/* reset page count bias and offset to start of new frag */
+		nc->pfmemalloc = page_is_pfmemalloc(page);
+		nc->pagecnt_bias = size;
+		nc->offset = size;
+	}
+
+	offset = nc->offset - fragsz;
+	if (unlikely(offset < 0)) {
+		page = virt_to_page(nc->va);
+
+		if (!atomic_sub_and_test(nc->pagecnt_bias, &page->_count))
+			goto refill;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+		/* if size can vary use size else just use PAGE_SIZE */
+		size = nc->size;
+#endif
+		/* OK, page count is 0, we can safely set it */
+		atomic_set(&page->_count, size);
+
+		/* reset page count bias and offset to start of new frag */
+		nc->pagecnt_bias = size;
+		offset = size - fragsz;
+	}
+
+	nc->pagecnt_bias--;
+	nc->offset = offset;
+
+	return nc->va + offset;
+}
+EXPORT_SYMBOL(__alloc_page_frag);
+
+/*
+ * Frees a page fragment allocated out of either a compound or order 0 page.
+ */
+void __free_page_frag(void *addr)
+{
+	struct page *page = virt_to_head_page(addr);
+
+	if (unlikely(put_page_testzero(page)))
+		__free_pages_ok(page, compound_order(page));
+}
+EXPORT_SYMBOL(__free_page_frag);
+
+/*
+ * alloc_kmem_pages charges newly allocated pages to the kmem resource counter
+ * of the current memory cgroup.
+ *
+ * It should be used when the caller would like to use kmalloc, but since the
+ * allocation is large, it has to fall back to the page allocator.
+ */
+struct page *alloc_kmem_pages(gfp_t gfp_mask, unsigned int order)
+{
+	struct page *page;
+
+	page = alloc_pages(gfp_mask, order);
+	if (page && memcg_kmem_charge(page, gfp_mask, order) != 0) {
+		__free_pages(page, order);
+		page = NULL;
+	}
+	return page;
+}
+
+struct page *alloc_kmem_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
+{
+	struct page *page;
+
+	page = alloc_pages_node(nid, gfp_mask, order);
+	if (page && memcg_kmem_charge(page, gfp_mask, order) != 0) {
+		__free_pages(page, order);
+		page = NULL;
+	}
+	return page;
+}
+
+/*
+ * __free_kmem_pages and free_kmem_pages will free pages allocated with
+ * alloc_kmem_pages.
+ */
+void __free_kmem_pages(struct page *page, unsigned int order)
+{
+	memcg_kmem_uncharge(page, order);
+	__free_pages(page, order);
+}
+
+void free_kmem_pages(unsigned long addr, unsigned int order)
+{
+	if (addr != 0) {
+		VM_BUG_ON(!virt_addr_valid((void *)addr));
+		__free_kmem_pages(virt_to_page((void *)addr), order);
+	}
+}
+
+static void *make_alloc_exact(unsigned long addr, unsigned int order,
+		size_t size)
+{
+	if (addr) {
+		unsigned long alloc_end = addr + (PAGE_SIZE << order);
+		unsigned long used = addr + PAGE_ALIGN(size);
+
+		split_page(virt_to_page((void *)addr), order);
+		while (used < alloc_end) {
+			free_page(used);
+			used += PAGE_SIZE;
+		}
+	}
+	return (void *)addr;
+}
+
+/**
+ * alloc_pages_exact - allocate an exact number physically-contiguous pages.
+ * @size: the number of bytes to allocate
+ * @gfp_mask: GFP flags for the allocation
+ *
+ * This function is similar to alloc_pages(), except that it allocates the
+ * minimum number of pages to satisfy the request.  alloc_pages() can only
+ * allocate memory in power-of-two pages.
+ *
+ * This function is also limited by MAX_ORDER.
+ *
+ * Memory allocated by this function must be released by free_pages_exact().
+ */
+void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
+{
+	unsigned int order = get_order(size);
+	unsigned long addr;
+
+	addr = __get_free_pages(gfp_mask, order);
+	return make_alloc_exact(addr, order, size);
+}
+EXPORT_SYMBOL(alloc_pages_exact);
+
+/**
+ * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
+ *			   pages on a node.
+ * @nid: the preferred node ID where memory should be allocated
+ * @size: the number of bytes to allocate
+ * @gfp_mask: GFP flags for the allocation
+ *
+ * Like alloc_pages_exact(), but try to allocate on node nid first before falling
+ * back.
+ */
+void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
+{
+	unsigned int order = get_order(size);
+	struct page *p = alloc_pages_node(nid, gfp_mask, order);
+	if (!p)
+		return NULL;
+	return make_alloc_exact((unsigned long)page_address(p), order, size);
+}
+
+/**
+ * free_pages_exact - release memory allocated via alloc_pages_exact()
+ * @virt: the value returned by alloc_pages_exact.
+ * @size: size of allocation, same value as passed to alloc_pages_exact().
+ *
+ * Release the memory allocated by a previous call to alloc_pages_exact.
+ */
+void free_pages_exact(void *virt, size_t size)
+{
+	unsigned long addr = (unsigned long)virt;
+	unsigned long end = addr + PAGE_ALIGN(size);
+
+	while (addr < end) {
+		free_page(addr);
+		addr += PAGE_SIZE;
+	}
+}
+EXPORT_SYMBOL(free_pages_exact);
+
+/**
+ * nr_free_zone_pages - count number of pages beyond high watermark
+ * @offset: The zone index of the highest zone
+ *
+ * nr_free_zone_pages() counts the number of counts pages which are beyond the
+ * high watermark within all zones at or below a given zone index.  For each
+ * zone, the number of pages is calculated as:
+ *     managed_pages - high_pages
+ */
+static unsigned long nr_free_zone_pages(int offset)
+{
+	struct zoneref *z;
+	struct zone *zone;
+
+	/* Just pick one node, since fallback list is circular */
+	unsigned long sum = 0;
+
+	struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
+
+	for_each_zone_zonelist(zone, z, zonelist, offset) {
+		unsigned long size = zone->managed_pages;
+		unsigned long high = high_wmark_pages(zone);
+		if (size > high)
+			sum += size - high;
+	}
+
+	return sum;
+}
+
+/**
+ * nr_free_buffer_pages - count number of pages beyond high watermark
+ *
+ * nr_free_buffer_pages() counts the number of pages which are beyond the high
+ * watermark within ZONE_DMA and ZONE_NORMAL.
+ */
+unsigned long nr_free_buffer_pages(void)
+{
+	return nr_free_zone_pages(gfp_zone(GFP_USER));
+}
+EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
+
+/**
+ * nr_free_pagecache_pages - count number of pages beyond high watermark
+ *
+ * nr_free_pagecache_pages() counts the number of pages which are beyond the
+ * high watermark within all zones.
+ */
+unsigned long nr_free_pagecache_pages(void)
+{
+	return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
+}
+
+static inline void show_node(struct zone *zone)
+{
+	if (IS_ENABLED(CONFIG_NUMA))
+		printk("Node %d ", zone_to_nid(zone));
+}
+
+void si_meminfo(struct sysinfo *val)
+{
+	val->totalram = totalram_pages;
+	val->sharedram = global_page_state(NR_SHMEM);
+	val->freeram = global_page_state(NR_FREE_PAGES);
+	val->bufferram = nr_blockdev_pages();
+	val->totalhigh = totalhigh_pages;
+	val->freehigh = nr_free_highpages();
+	val->mem_unit = PAGE_SIZE;
+}
+
+EXPORT_SYMBOL(si_meminfo);
+
+#ifdef CONFIG_NUMA
+void si_meminfo_node(struct sysinfo *val, int nid)
+{
+	int zone_type;		/* needs to be signed */
+	unsigned long managed_pages = 0;
+	pg_data_t *pgdat = NODE_DATA(nid);
+
+	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
+		managed_pages += pgdat->node_zones[zone_type].managed_pages;
+	val->totalram = managed_pages;
+	val->sharedram = node_page_state(nid, NR_SHMEM);
+	val->freeram = node_page_state(nid, NR_FREE_PAGES);
+#ifdef CONFIG_HIGHMEM
+	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].managed_pages;
+	val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
+			NR_FREE_PAGES);
+#else
+	val->totalhigh = 0;
+	val->freehigh = 0;
+#endif
+	val->mem_unit = PAGE_SIZE;
+}
+#endif
+
+/*
+ * Determine whether the node should be displayed or not, depending on whether
+ * SHOW_MEM_FILTER_NODES was passed to show_free_areas().
+ */
+bool skip_free_areas_node(unsigned int flags, int nid)
+{
+	bool ret = false;
+	unsigned int cpuset_mems_cookie;
+
+	if (!(flags & SHOW_MEM_FILTER_NODES))
+		goto out;
+
+	do {
+		cpuset_mems_cookie = read_mems_allowed_begin();
+		ret = !node_isset(nid, cpuset_current_mems_allowed);
+	} while (read_mems_allowed_retry(cpuset_mems_cookie));
+out:
+	return ret;
+}
+
+#define K(x) ((x) << (PAGE_SHIFT-10))
+
+static void show_migration_types(unsigned char type)
+{
+	static const char types[MIGRATE_TYPES] = {
+		[MIGRATE_UNMOVABLE]	= 'U',
+		[MIGRATE_MOVABLE]	= 'M',
+		[MIGRATE_RECLAIMABLE]	= 'E',
+		[MIGRATE_HIGHATOMIC]	= 'H',
+#ifdef CONFIG_CMA
+		[MIGRATE_CMA]		= 'C',
+#endif
+#ifdef CONFIG_MEMORY_ISOLATION
+		[MIGRATE_ISOLATE]	= 'I',
+#endif
+	};
+	char tmp[MIGRATE_TYPES + 1];
+	char *p = tmp;
+	int i;
+
+	for (i = 0; i < MIGRATE_TYPES; i++) {
+		if (type & (1 << i))
+			*p++ = types[i];
+	}
+
+	*p = '\0';
+	printk("(%s) ", tmp);
+}
+
+/*
+ * Show free area list (used inside shift_scroll-lock stuff)
+ * We also calculate the percentage fragmentation. We do this by counting the
+ * memory on each free list with the exception of the first item on the list.
+ *
+ * Bits in @filter:
+ * SHOW_MEM_FILTER_NODES: suppress nodes that are not allowed by current's
+ *   cpuset.
+ */
+void show_free_areas(unsigned int filter)
+{
+	unsigned long free_pcp = 0;
+	int cpu;
+	struct zone *zone;
+
+	for_each_populated_zone(zone) {
+		if (skip_free_areas_node(filter, zone_to_nid(zone)))
+			continue;
+
+		for_each_online_cpu(cpu)
+			free_pcp += per_cpu_ptr(zone->pageset, cpu)->pcp.count;
+	}
+
+	printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
+		" active_file:%lu inactive_file:%lu isolated_file:%lu\n"
+		" unevictable:%lu dirty:%lu writeback:%lu unstable:%lu\n"
+		" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
+		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
+		" free:%lu free_pcp:%lu free_cma:%lu\n",
+		global_page_state(NR_ACTIVE_ANON),
+		global_page_state(NR_INACTIVE_ANON),
+		global_page_state(NR_ISOLATED_ANON),
+		global_page_state(NR_ACTIVE_FILE),
+		global_page_state(NR_INACTIVE_FILE),
+		global_page_state(NR_ISOLATED_FILE),
+		global_page_state(NR_UNEVICTABLE),
+		global_page_state(NR_FILE_DIRTY),
+		global_page_state(NR_WRITEBACK),
+		global_page_state(NR_UNSTABLE_NFS),
+		global_page_state(NR_SLAB_RECLAIMABLE),
+		global_page_state(NR_SLAB_UNRECLAIMABLE),
+		global_page_state(NR_FILE_MAPPED),
+		global_page_state(NR_SHMEM),
+		global_page_state(NR_PAGETABLE),
+		global_page_state(NR_BOUNCE),
+		global_page_state(NR_FREE_PAGES),
+		free_pcp,
+		global_page_state(NR_FREE_CMA_PAGES));
+
+	for_each_populated_zone(zone) {
+		int i;
+
+		if (skip_free_areas_node(filter, zone_to_nid(zone)))
+			continue;
+
+		free_pcp = 0;
+		for_each_online_cpu(cpu)
+			free_pcp += per_cpu_ptr(zone->pageset, cpu)->pcp.count;
+
+		show_node(zone);
+		printk("%s"
+			" free:%lukB"
+			" min:%lukB"
+			" low:%lukB"
+			" high:%lukB"
+			" active_anon:%lukB"
+			" inactive_anon:%lukB"
+			" active_file:%lukB"
+			" inactive_file:%lukB"
+			" unevictable:%lukB"
+			" isolated(anon):%lukB"
+			" isolated(file):%lukB"
+			" present:%lukB"
+			" managed:%lukB"
+			" mlocked:%lukB"
+			" dirty:%lukB"
+			" writeback:%lukB"
+			" mapped:%lukB"
+			" shmem:%lukB"
+			" slab_reclaimable:%lukB"
+			" slab_unreclaimable:%lukB"
+			" kernel_stack:%lukB"
+			" pagetables:%lukB"
+			" unstable:%lukB"
+			" bounce:%lukB"
+			" free_pcp:%lukB"
+			" local_pcp:%ukB"
+			" free_cma:%lukB"
+			" writeback_tmp:%lukB"
+			" pages_scanned:%lu"
+			" all_unreclaimable? %s"
+			"\n",
+			zone->name,
+			K(zone_page_state(zone, NR_FREE_PAGES)),
+			K(min_wmark_pages(zone)),
+			K(low_wmark_pages(zone)),
+			K(high_wmark_pages(zone)),
+			K(zone_page_state(zone, NR_ACTIVE_ANON)),
+			K(zone_page_state(zone, NR_INACTIVE_ANON)),
+			K(zone_page_state(zone, NR_ACTIVE_FILE)),
+			K(zone_page_state(zone, NR_INACTIVE_FILE)),
+			K(zone_page_state(zone, NR_UNEVICTABLE)),
+			K(zone_page_state(zone, NR_ISOLATED_ANON)),
+			K(zone_page_state(zone, NR_ISOLATED_FILE)),
+			K(zone->present_pages),
+			K(zone->managed_pages),
+			K(zone_page_state(zone, NR_MLOCK)),
+			K(zone_page_state(zone, NR_FILE_DIRTY)),
+			K(zone_page_state(zone, NR_WRITEBACK)),
+			K(zone_page_state(zone, NR_FILE_MAPPED)),
+			K(zone_page_state(zone, NR_SHMEM)),
+			K(zone_page_state(zone, NR_SLAB_RECLAIMABLE)),
+			K(zone_page_state(zone, NR_SLAB_UNRECLAIMABLE)),
+			zone_page_state(zone, NR_KERNEL_STACK) *
+				THREAD_SIZE / 1024,
+			K(zone_page_state(zone, NR_PAGETABLE)),
+			K(zone_page_state(zone, NR_UNSTABLE_NFS)),
+			K(zone_page_state(zone, NR_BOUNCE)),
+			K(free_pcp),
+			K(this_cpu_read(zone->pageset->pcp.count)),
+			K(zone_page_state(zone, NR_FREE_CMA_PAGES)),
+			K(zone_page_state(zone, NR_WRITEBACK_TEMP)),
+			K(zone_page_state(zone, NR_PAGES_SCANNED)),
+			(!zone_reclaimable(zone) ? "yes" : "no")
+			);
+		printk("lowmem_reserve[]:");
+		for (i = 0; i < MAX_NR_ZONES; i++)
+			printk(" %ld", zone->lowmem_reserve[i]);
+		printk("\n");
+	}
+
+	for_each_populated_zone(zone) {
+		unsigned int order;
+		unsigned long nr[MAX_ORDER], flags, total = 0;
+		unsigned char types[MAX_ORDER];
+
+		if (skip_free_areas_node(filter, zone_to_nid(zone)))
+			continue;
+		show_node(zone);
+		printk("%s: ", zone->name);
+
+		spin_lock_irqsave(&zone->lock, flags);
+		for (order = 0; order < MAX_ORDER; order++) {
+			struct free_area *area = &zone->free_area[order];
+			int type;
+
+			nr[order] = area->nr_free;
+			total += nr[order] << order;
+
+			types[order] = 0;
+			for (type = 0; type < MIGRATE_TYPES; type++) {
+				if (!list_empty(&area->free_list[type]))
+					types[order] |= 1 << type;
+			}
+		}
+		spin_unlock_irqrestore(&zone->lock, flags);
+		for (order = 0; order < MAX_ORDER; order++) {
+			printk("%lu*%lukB ", nr[order], K(1UL) << order);
+			if (nr[order])
+				show_migration_types(types[order]);
+		}
+		printk("= %lukB\n", K(total));
+	}
+
+	hugetlb_show_meminfo();
+
+	printk("%ld total pagecache pages\n", global_page_state(NR_FILE_PAGES));
+
+	show_swap_cache_info();
+}
+
+static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
+{
+	zoneref->zone = zone;
+	zoneref->zone_idx = zone_idx(zone);
+}
+
+/*
+ * Builds allocation fallback zone lists.
+ *
+ * Add all populated zones of a node to the zonelist.
+ */
+static int build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist,
+				int nr_zones)
+{
+	struct zone *zone;
+	enum zone_type zone_type = MAX_NR_ZONES;
+
+	do {
+		zone_type--;
+		zone = pgdat->node_zones + zone_type;
+		if (populated_zone(zone)) {
+			zoneref_set_zone(zone,
+				&zonelist->_zonerefs[nr_zones++]);
+			check_highest_zone(zone_type);
+		}
+	} while (zone_type);
+
+	return nr_zones;
+}
+
+
+/*
+ *  zonelist_order:
+ *  0 = automatic detection of better ordering.
+ *  1 = order by ([node] distance, -zonetype)
+ *  2 = order by (-zonetype, [node] distance)
+ *
+ *  If not NUMA, ZONELIST_ORDER_ZONE and ZONELIST_ORDER_NODE will create
+ *  the same zonelist. So only NUMA can configure this param.
+ */
+#define ZONELIST_ORDER_DEFAULT  0
+#define ZONELIST_ORDER_NODE     1
+#define ZONELIST_ORDER_ZONE     2
+
+/* zonelist order in the kernel.
+ * set_zonelist_order() will set this to NODE or ZONE.
+ */
+static int current_zonelist_order = ZONELIST_ORDER_DEFAULT;
+static char zonelist_order_name[3][8] = {"Default", "Node", "Zone"};
+
+
+#ifdef CONFIG_NUMA
+/* The value user specified ....changed by config */
+static int user_zonelist_order = ZONELIST_ORDER_DEFAULT;
+/* string for sysctl */
+#define NUMA_ZONELIST_ORDER_LEN	16
+char numa_zonelist_order[16] = "default";
+
+/*
+ * interface for configure zonelist ordering.
+ * command line option "numa_zonelist_order"
+ *	= "[dD]efault	- default, automatic configuration.
+ *	= "[nN]ode 	- order by node locality, then by zone within node
+ *	= "[zZ]one      - order by zone, then by locality within zone
+ */
+
+static int __parse_numa_zonelist_order(char *s)
+{
+	if (*s == 'd' || *s == 'D') {
+		user_zonelist_order = ZONELIST_ORDER_DEFAULT;
+	} else if (*s == 'n' || *s == 'N') {
+		user_zonelist_order = ZONELIST_ORDER_NODE;
+	} else if (*s == 'z' || *s == 'Z') {
+		user_zonelist_order = ZONELIST_ORDER_ZONE;
+	} else {
+		printk(KERN_WARNING
+			"Ignoring invalid numa_zonelist_order value:  "
+			"%s\n", s);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static __init int setup_numa_zonelist_order(char *s)
+{
+	int ret;
+
+	if (!s)
+		return 0;
+
+	ret = __parse_numa_zonelist_order(s);
+	if (ret == 0)
+		strlcpy(numa_zonelist_order, s, NUMA_ZONELIST_ORDER_LEN);
+
+	return ret;
+}
+early_param("numa_zonelist_order", setup_numa_zonelist_order);
+
+/*
+ * sysctl handler for numa_zonelist_order
+ */
+int numa_zonelist_order_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *length,
+		loff_t *ppos)
+{
+	char saved_string[NUMA_ZONELIST_ORDER_LEN];
+	int ret;
+	static DEFINE_MUTEX(zl_order_mutex);
+
+	mutex_lock(&zl_order_mutex);
+	if (write) {
+		if (strlen((char *)table->data) >= NUMA_ZONELIST_ORDER_LEN) {
+			ret = -EINVAL;
+			goto out;
+		}
+		strcpy(saved_string, (char *)table->data);
+	}
+	ret = proc_dostring(table, write, buffer, length, ppos);
+	if (ret)
+		goto out;
+	if (write) {
+		int oldval = user_zonelist_order;
+
+		ret = __parse_numa_zonelist_order((char *)table->data);
+		if (ret) {
+			/*
+			 * bogus value.  restore saved string
+			 */
+			strncpy((char *)table->data, saved_string,
+				NUMA_ZONELIST_ORDER_LEN);
+			user_zonelist_order = oldval;
+		} else if (oldval != user_zonelist_order) {
+			mutex_lock(&zonelists_mutex);
+			build_all_zonelists(NULL, NULL);
+			mutex_unlock(&zonelists_mutex);
+		}
+	}
+out:
+	mutex_unlock(&zl_order_mutex);
+	return ret;
+}
+
+
+#define MAX_NODE_LOAD (nr_online_nodes)
+static int node_load[MAX_NUMNODES];
+
+/**
+ * find_next_best_node - find the next node that should appear in a given node's fallback list
+ * @node: node whose fallback list we're appending
+ * @used_node_mask: nodemask_t of already used nodes
+ *
+ * We use a number of factors to determine which is the next node that should
+ * appear on a given node's fallback list.  The node should not have appeared
+ * already in @node's fallback list, and it should be the next closest node
+ * according to the distance array (which contains arbitrary distance values
+ * from each node to each node in the system), and should also prefer nodes
+ * with no CPUs, since presumably they'll have very little allocation pressure
+ * on them otherwise.
+ * It returns -1 if no node is found.
+ */
+static int find_next_best_node(int node, nodemask_t *used_node_mask)
+{
+	int n, val;
+	int min_val = INT_MAX;
+	int best_node = NUMA_NO_NODE;
+	const struct cpumask *tmp = cpumask_of_node(0);
+
+	/* Use the local node if we haven't already */
+	if (!node_isset(node, *used_node_mask)) {
+		node_set(node, *used_node_mask);
+		return node;
+	}
+
+	for_each_node_state(n, N_MEMORY) {
+
+		/* Don't want a node to appear more than once */
+		if (node_isset(n, *used_node_mask))
+			continue;
+
+		/* Use the distance array to find the distance */
+		val = node_distance(node, n);
+
+		/* Penalize nodes under us ("prefer the next node") */
+		val += (n < node);
+
+		/* Give preference to headless and unused nodes */
+		tmp = cpumask_of_node(n);
+		if (!cpumask_empty(tmp))
+			val += PENALTY_FOR_NODE_WITH_CPUS;
+
+		/* Slight preference for less loaded node */
+		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
+		val += node_load[n];
+
+		if (val < min_val) {
+			min_val = val;
+			best_node = n;
+		}
+	}
+
+	if (best_node >= 0)
+		node_set(best_node, *used_node_mask);
+
+	return best_node;
+}
+
+
+/*
+ * Build zonelists ordered by node and zones within node.
+ * This results in maximum locality--normal zone overflows into local
+ * DMA zone, if any--but risks exhausting DMA zone.
+ */
+static void build_zonelists_in_node_order(pg_data_t *pgdat, int node)
+{
+	int j;
+	struct zonelist *zonelist;
+
+	zonelist = &pgdat->node_zonelists[0];
+	for (j = 0; zonelist->_zonerefs[j].zone != NULL; j++)
+		;
+	j = build_zonelists_node(NODE_DATA(node), zonelist, j);
+	zonelist->_zonerefs[j].zone = NULL;
+	zonelist->_zonerefs[j].zone_idx = 0;
+}
+
+/*
+ * Build gfp_thisnode zonelists
+ */
+static void build_thisnode_zonelists(pg_data_t *pgdat)
+{
+	int j;
+	struct zonelist *zonelist;
+
+	zonelist = &pgdat->node_zonelists[1];
+	j = build_zonelists_node(pgdat, zonelist, 0);
+	zonelist->_zonerefs[j].zone = NULL;
+	zonelist->_zonerefs[j].zone_idx = 0;
+}
+
+/*
+ * Build zonelists ordered by zone and nodes within zones.
+ * This results in conserving DMA zone[s] until all Normal memory is
+ * exhausted, but results in overflowing to remote node while memory
+ * may still exist in local DMA zone.
+ */
+static int node_order[MAX_NUMNODES];
+
+static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
+{
+	int pos, j, node;
+	int zone_type;		/* needs to be signed */
+	struct zone *z;
+	struct zonelist *zonelist;
+
+	zonelist = &pgdat->node_zonelists[0];
+	pos = 0;
+	for (zone_type = MAX_NR_ZONES - 1; zone_type >= 0; zone_type--) {
+		for (j = 0; j < nr_nodes; j++) {
+			node = node_order[j];
+			z = &NODE_DATA(node)->node_zones[zone_type];
+			if (populated_zone(z)) {
+				zoneref_set_zone(z,
+					&zonelist->_zonerefs[pos++]);
+				check_highest_zone(zone_type);
+			}
+		}
+	}
+	zonelist->_zonerefs[pos].zone = NULL;
+	zonelist->_zonerefs[pos].zone_idx = 0;
+}
+
+#if defined(CONFIG_64BIT)
+/*
+ * Devices that require DMA32/DMA are relatively rare and do not justify a
+ * penalty to every machine in case the specialised case applies. Default
+ * to Node-ordering on 64-bit NUMA machines
+ */
+static int default_zonelist_order(void)
+{
+	return ZONELIST_ORDER_NODE;
+}
+#else
+/*
+ * On 32-bit, the Normal zone needs to be preserved for allocations accessible
+ * by the kernel. If processes running on node 0 deplete the low memory zone
+ * then reclaim will occur more frequency increasing stalls and potentially
+ * be easier to OOM if a large percentage of the zone is under writeback or
+ * dirty. The problem is significantly worse if CONFIG_HIGHPTE is not set.
+ * Hence, default to zone ordering on 32-bit.
+ */
+static int default_zonelist_order(void)
+{
+	return ZONELIST_ORDER_ZONE;
+}
+#endif /* CONFIG_64BIT */
+
+static void set_zonelist_order(void)
+{
+	if (user_zonelist_order == ZONELIST_ORDER_DEFAULT)
+		current_zonelist_order = default_zonelist_order();
+	else
+		current_zonelist_order = user_zonelist_order;
+}
+
+static void build_zonelists(pg_data_t *pgdat)
+{
+	int j, node, load;
+	enum zone_type i;
+	nodemask_t used_mask;
+	int local_node, prev_node;
+	struct zonelist *zonelist;
+	unsigned int order = current_zonelist_order;
+
+	/* initialize zonelists */
+	for (i = 0; i < MAX_ZONELISTS; i++) {
+		zonelist = pgdat->node_zonelists + i;
+		zonelist->_zonerefs[0].zone = NULL;
+		zonelist->_zonerefs[0].zone_idx = 0;
+	}
+
+	/* NUMA-aware ordering of nodes */
+	local_node = pgdat->node_id;
+	load = nr_online_nodes;
+	prev_node = local_node;
+	nodes_clear(used_mask);
+
+	memset(node_order, 0, sizeof(node_order));
+	j = 0;
+
+	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
+		/*
+		 * We don't want to pressure a particular node.
+		 * So adding penalty to the first node in same
+		 * distance group to make it round-robin.
+		 */
+		if (node_distance(local_node, node) !=
+		    node_distance(local_node, prev_node))
+			node_load[node] = load;
+
+		prev_node = node;
+		load--;
+		if (order == ZONELIST_ORDER_NODE)
+			build_zonelists_in_node_order(pgdat, node);
+		else
+			node_order[j++] = node;	/* remember order */
+	}
+
+	if (order == ZONELIST_ORDER_ZONE) {
+		/* calculate node order -- i.e., DMA last! */
+		build_zonelists_in_zone_order(pgdat, j);
+	}
+
+	build_thisnode_zonelists(pgdat);
+}
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+/*
+ * Return node id of node used for "local" allocations.
+ * I.e., first node id of first zone in arg node's generic zonelist.
+ * Used for initializing percpu 'numa_mem', which is used primarily
+ * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
+ */
+int local_memory_node(int node)
+{
+	struct zone *zone;
+
+	(void)first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
+				   gfp_zone(GFP_KERNEL),
+				   NULL,
+				   &zone);
+	return zone->node;
+}
+#endif
+
+#else	/* CONFIG_NUMA */
+
+static void set_zonelist_order(void)
+{
+	current_zonelist_order = ZONELIST_ORDER_ZONE;
+}
+
+static void build_zonelists(pg_data_t *pgdat)
+{
+	int node, local_node;
+	enum zone_type j;
+	struct zonelist *zonelist;
+
+	local_node = pgdat->node_id;
+
+	zonelist = &pgdat->node_zonelists[0];
+	j = build_zonelists_node(pgdat, zonelist, 0);
+
+	/*
+	 * Now we build the zonelist so that it contains the zones
+	 * of all the other nodes.
+	 * We don't want to pressure a particular node, so when
+	 * building the zones for node N, we make sure that the
+	 * zones coming right after the local ones are those from
+	 * node N+1 (modulo N)
+	 */
+	for (node = local_node + 1; node < MAX_NUMNODES; node++) {
+		if (!node_online(node))
+			continue;
+		j = build_zonelists_node(NODE_DATA(node), zonelist, j);
+	}
+	for (node = 0; node < local_node; node++) {
+		if (!node_online(node))
+			continue;
+		j = build_zonelists_node(NODE_DATA(node), zonelist, j);
+	}
+
+	zonelist->_zonerefs[j].zone = NULL;
+	zonelist->_zonerefs[j].zone_idx = 0;
+}
+
+#endif	/* CONFIG_NUMA */
+
+/*
+ * Boot pageset table. One per cpu which is going to be used for all
+ * zones and all nodes. The parameters will be set in such a way
+ * that an item put on a list will immediately be handed over to
+ * the buddy list. This is safe since pageset manipulation is done
+ * with interrupts disabled.
+ *
+ * The boot_pagesets must be kept even after bootup is complete for
+ * unused processors and/or zones. They do play a role for bootstrapping
+ * hotplugged processors.
+ *
+ * zoneinfo_show() and maybe other functions do
+ * not check if the processor is online before following the pageset pointer.
+ * Other parts of the kernel may not check if the zone is available.
+ */
+static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
+static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
+static void setup_zone_pageset(struct zone *zone);
+
+/*
+ * Global mutex to protect against size modification of zonelists
+ * as well as to serialize pageset setup for the new populated zone.
+ */
+DEFINE_MUTEX(zonelists_mutex);
+
+/* return values int ....just for stop_machine() */
+static int __build_all_zonelists(void *data)
+{
+	int nid;
+	int cpu;
+	pg_data_t *self = data;
+
+#ifdef CONFIG_NUMA
+	memset(node_load, 0, sizeof(node_load));
+#endif
+
+	if (self && !node_online(self->node_id)) {
+		build_zonelists(self);
+	}
+
+	for_each_online_node(nid) {
+		pg_data_t *pgdat = NODE_DATA(nid);
+
+		build_zonelists(pgdat);
+	}
+
+	/*
+	 * Initialize the boot_pagesets that are going to be used
+	 * for bootstrapping processors. The real pagesets for
+	 * each zone will be allocated later when the per cpu
+	 * allocator is available.
+	 *
+	 * boot_pagesets are used also for bootstrapping offline
+	 * cpus if the system is already booted because the pagesets
+	 * are needed to initialize allocators on a specific cpu too.
+	 * F.e. the percpu allocator needs the page allocator which
+	 * needs the percpu allocator in order to allocate its pagesets
+	 * (a chicken-egg dilemma).
+	 */
+	for_each_possible_cpu(cpu) {
+		setup_pageset(&per_cpu(boot_pageset, cpu), 0);
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+		/*
+		 * We now know the "local memory node" for each node--
+		 * i.e., the node of the first zone in the generic zonelist.
+		 * Set up numa_mem percpu variable for on-line cpus.  During
+		 * boot, only the boot cpu should be on-line;  we'll init the
+		 * secondary cpus' numa_mem as they come on-line.  During
+		 * node/memory hotplug, we'll fixup all on-line cpus.
+		 */
+		if (cpu_online(cpu))
+			set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
+#endif
+	}
+
+	return 0;
+}
+
+static noinline void __init
+build_all_zonelists_init(void)
+{
+	__build_all_zonelists(NULL);
+	mminit_verify_zonelist();
+	cpuset_init_current_mems_allowed();
+}
+
+/*
+ * Called with zonelists_mutex held always
+ * unless system_state == SYSTEM_BOOTING.
+ *
+ * __ref due to (1) call of __meminit annotated setup_zone_pageset
+ * [we're only called with non-NULL zone through __meminit paths] and
+ * (2) call of __init annotated helper build_all_zonelists_init
+ * [protected by SYSTEM_BOOTING].
+ */
+void __ref build_all_zonelists(pg_data_t *pgdat, struct zone *zone)
+{
+	set_zonelist_order();
+
+	if (system_state == SYSTEM_BOOTING) {
+		build_all_zonelists_init();
+	} else {
+#ifdef CONFIG_MEMORY_HOTPLUG
+		if (zone)
+			setup_zone_pageset(zone);
+#endif
+		/* we have to stop all cpus to guarantee there is no user
+		   of zonelist */
+		stop_machine(__build_all_zonelists, pgdat, NULL);
+		/* cpuset refresh routine should be here */
+	}
+	vm_total_pages = nr_free_pagecache_pages();
+	/*
+	 * Disable grouping by mobility if the number of pages in the
+	 * system is too low to allow the mechanism to work. It would be
+	 * more accurate, but expensive to check per-zone. This check is
+	 * made on memory-hotadd so a system can start with mobility
+	 * disabled and enable it later
+	 */
+	if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
+		page_group_by_mobility_disabled = 1;
+	else
+		page_group_by_mobility_disabled = 0;
+
+	pr_info("Built %i zonelists in %s order, mobility grouping %s.  "
+		"Total pages: %ld\n",
+			nr_online_nodes,
+			zonelist_order_name[current_zonelist_order],
+			page_group_by_mobility_disabled ? "off" : "on",
+			vm_total_pages);
+#ifdef CONFIG_NUMA
+	pr_info("Policy zone: %s\n", zone_names[policy_zone]);
+#endif
+}
+
+/*
+ * Helper functions to size the waitqueue hash table.
+ * Essentially these want to choose hash table sizes sufficiently
+ * large so that collisions trying to wait on pages are rare.
+ * But in fact, the number of active page waitqueues on typical
+ * systems is ridiculously low, less than 200. So this is even
+ * conservative, even though it seems large.
+ *
+ * The constant PAGES_PER_WAITQUEUE specifies the ratio of pages to
+ * waitqueues, i.e. the size of the waitq table given the number of pages.
+ */
+#define PAGES_PER_WAITQUEUE	256
+
+#ifndef CONFIG_MEMORY_HOTPLUG
+static inline unsigned long wait_table_hash_nr_entries(unsigned long pages)
+{
+	unsigned long size = 1;
+
+	pages /= PAGES_PER_WAITQUEUE;
+
+	while (size < pages)
+		size <<= 1;
+
+	/*
+	 * Once we have dozens or even hundreds of threads sleeping
+	 * on IO we've got bigger problems than wait queue collision.
+	 * Limit the size of the wait table to a reasonable size.
+	 */
+	size = min(size, 4096UL);
+
+	return max(size, 4UL);
+}
+#else
+/*
+ * A zone's size might be changed by hot-add, so it is not possible to determine
+ * a suitable size for its wait_table.  So we use the maximum size now.
+ *
+ * The max wait table size = 4096 x sizeof(wait_queue_head_t).   ie:
+ *
+ *    i386 (preemption config)    : 4096 x 16 = 64Kbyte.
+ *    ia64, x86-64 (no preemption): 4096 x 20 = 80Kbyte.
+ *    ia64, x86-64 (preemption)   : 4096 x 24 = 96Kbyte.
+ *
+ * The maximum entries are prepared when a zone's memory is (512K + 256) pages
+ * or more by the traditional way. (See above).  It equals:
+ *
+ *    i386, x86-64, powerpc(4K page size) : =  ( 2G + 1M)byte.
+ *    ia64(16K page size)                 : =  ( 8G + 4M)byte.
+ *    powerpc (64K page size)             : =  (32G +16M)byte.
+ */
+static inline unsigned long wait_table_hash_nr_entries(unsigned long pages)
+{
+	return 4096UL;
+}
+#endif
+
+/*
+ * This is an integer logarithm so that shifts can be used later
+ * to extract the more random high bits from the multiplicative
+ * hash function before the remainder is taken.
+ */
+static inline unsigned long wait_table_bits(unsigned long size)
+{
+	return ffz(~size);
+}
+
+/*
+ * Initially all pages are reserved - free ones are freed
+ * up by free_all_bootmem() once the early boot process is
+ * done. Non-atomic initialization, single-pass.
+ */
+void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
+		unsigned long start_pfn, enum memmap_context context)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+	unsigned long end_pfn = start_pfn + size;
+	unsigned long pfn;
+	struct zone *z;
+	unsigned long nr_initialised = 0;
+
+	if (highest_memmap_pfn < end_pfn - 1)
+		highest_memmap_pfn = end_pfn - 1;
+
+	z = &pgdat->node_zones[zone];
+	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+		/*
+		 * There can be holes in boot-time mem_map[]s
+		 * handed to this function.  They do not
+		 * exist on hotplugged memory.
+		 */
+		if (context == MEMMAP_EARLY) {
+			if (!early_pfn_valid(pfn))
+				continue;
+			if (!early_pfn_in_nid(pfn, nid))
+				continue;
+			if (!update_defer_init(pgdat, pfn, end_pfn,
+						&nr_initialised))
+				break;
+		}
+
+		/*
+		 * Mark the block movable so that blocks are reserved for
+		 * movable at startup. This will force kernel allocations
+		 * to reserve their blocks rather than leaking throughout
+		 * the address space during boot when many long-lived
+		 * kernel allocations are made.
+		 *
+		 * bitmap is created for zone's valid pfn range. but memmap
+		 * can be created for invalid pages (for alignment)
+		 * check here not to call set_pageblock_migratetype() against
+		 * pfn out of zone.
+		 */
+		if (!(pfn & (pageblock_nr_pages - 1))) {
+			struct page *page = pfn_to_page(pfn);
+
+			__init_single_page(page, pfn, zone, nid);
+			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+		} else {
+			__init_single_pfn(pfn, zone, nid);
+		}
+	}
+}
+
+static void __meminit zone_init_free_lists(struct zone *zone)
+{
+	unsigned int order, t;
+	for_each_migratetype_order(order, t) {
+		INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
+		zone->free_area[order].nr_free = 0;
+	}
+}
+
+#ifndef __HAVE_ARCH_MEMMAP_INIT
+#define memmap_init(size, nid, zone, start_pfn) \
+	memmap_init_zone((size), (nid), (zone), (start_pfn), MEMMAP_EARLY)
+#endif
+
+static int zone_batchsize(struct zone *zone)
+{
+#ifdef CONFIG_MMU
+	int batch;
+
+	/*
+	 * The per-cpu-pages pools are set to around 1000th of the
+	 * size of the zone.  But no more than 1/2 of a meg.
+	 *
+	 * OK, so we don't know how big the cache is.  So guess.
+	 */
+	batch = zone->managed_pages / 1024;
+	if (batch * PAGE_SIZE > 512 * 1024)
+		batch = (512 * 1024) / PAGE_SIZE;
+	batch /= 4;		/* We effectively *= 4 below */
+	if (batch < 1)
+		batch = 1;
+
+	/*
+	 * Clamp the batch to a 2^n - 1 value. Having a power
+	 * of 2 value was found to be more likely to have
+	 * suboptimal cache aliasing properties in some cases.
+	 *
+	 * For example if 2 tasks are alternately allocating
+	 * batches of pages, one task can end up with a lot
+	 * of pages of one half of the possible page colors
+	 * and the other with pages of the other colors.
+	 */
+	batch = rounddown_pow_of_two(batch + batch/2) - 1;
+
+	return batch;
+
+#else
+	/* The deferral and batching of frees should be suppressed under NOMMU
+	 * conditions.
+	 *
+	 * The problem is that NOMMU needs to be able to allocate large chunks
+	 * of contiguous memory as there's no hardware page translation to
+	 * assemble apparent contiguous memory from discontiguous pages.
+	 *
+	 * Queueing large contiguous runs of pages for batching, however,
+	 * causes the pages to actually be freed in smaller chunks.  As there
+	 * can be a significant delay between the individual batches being
+	 * recycled, this leads to the once large chunks of space being
+	 * fragmented and becoming unavailable for high-order allocations.
+	 */
+	return 0;
+#endif
+}
+
+/*
+ * pcp->high and pcp->batch values are related and dependent on one another:
+ * ->batch must never be higher then ->high.
+ * The following function updates them in a safe manner without read side
+ * locking.
+ *
+ * Any new users of pcp->batch and pcp->high should ensure they can cope with
+ * those fields changing asynchronously (acording the the above rule).
+ *
+ * mutex_is_locked(&pcp_batch_high_lock) required when calling this function
+ * outside of boot time (or some other assurance that no concurrent updaters
+ * exist).
+ */
+static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
+		unsigned long batch)
+{
+       /* start with a fail safe value for batch */
+	pcp->batch = 1;
+	smp_wmb();
+
+       /* Update high, then batch, in order */
+	pcp->high = high;
+	smp_wmb();
+
+	pcp->batch = batch;
+}
+
+/* a companion to pageset_set_high() */
+static void pageset_set_batch(struct per_cpu_pageset *p, unsigned long batch)
+{
+	pageset_update(&p->pcp, 6 * batch, max(1UL, 1 * batch));
+}
+
+static void pageset_init(struct per_cpu_pageset *p)
+{
+	struct per_cpu_pages *pcp;
+	int migratetype;
+
+	memset(p, 0, sizeof(*p));
+
+	pcp = &p->pcp;
+	pcp->count = 0;
+	for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++)
+		INIT_LIST_HEAD(&pcp->lists[migratetype]);
+}
+
+static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
+{
+	pageset_init(p);
+	pageset_set_batch(p, batch);
+}
+
+/*
+ * pageset_set_high() sets the high water mark for hot per_cpu_pagelist
+ * to the value high for the pageset p.
+ */
+static void pageset_set_high(struct per_cpu_pageset *p,
+				unsigned long high)
+{
+	unsigned long batch = max(1UL, high / 4);
+	if ((high / 4) > (PAGE_SHIFT * 8))
+		batch = PAGE_SHIFT * 8;
+
+	pageset_update(&p->pcp, high, batch);
+}
+
+static void pageset_set_high_and_batch(struct zone *zone,
+				       struct per_cpu_pageset *pcp)
+{
+	if (percpu_pagelist_fraction)
+		pageset_set_high(pcp,
+			(zone->managed_pages /
+				percpu_pagelist_fraction));
+	else
+		pageset_set_batch(pcp, zone_batchsize(zone));
+}
+
+static void __meminit zone_pageset_init(struct zone *zone, int cpu)
+{
+	struct per_cpu_pageset *pcp = per_cpu_ptr(zone->pageset, cpu);
+
+	pageset_init(pcp);
+	pageset_set_high_and_batch(zone, pcp);
+}
+
+static void __meminit setup_zone_pageset(struct zone *zone)
+{
+	int cpu;
+	zone->pageset = alloc_percpu(struct per_cpu_pageset);
+	for_each_possible_cpu(cpu)
+		zone_pageset_init(zone, cpu);
+}
+
+/*
+ * Allocate per cpu pagesets and initialize them.
+ * Before this call only boot pagesets were available.
+ */
+void __init setup_per_cpu_pageset(void)
+{
+	struct zone *zone;
+
+	for_each_populated_zone(zone)
+		setup_zone_pageset(zone);
+}
+
+static noinline __init_refok
+int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
+{
+	int i;
+	size_t alloc_size;
+
+	/*
+	 * The per-page waitqueue mechanism uses hashed waitqueues
+	 * per zone.
+	 */
+	zone->wait_table_hash_nr_entries =
+		 wait_table_hash_nr_entries(zone_size_pages);
+	zone->wait_table_bits =
+		wait_table_bits(zone->wait_table_hash_nr_entries);
+	alloc_size = zone->wait_table_hash_nr_entries
+					* sizeof(wait_queue_head_t);
+
+	if (!slab_is_available()) {
+		zone->wait_table = (wait_queue_head_t *)
+			memblock_virt_alloc_node_nopanic(
+				alloc_size, zone->zone_pgdat->node_id);
+	} else {
+		/*
+		 * This case means that a zone whose size was 0 gets new memory
+		 * via memory hot-add.
+		 * But it may be the case that a new node was hot-added.  In
+		 * this case vmalloc() will not be able to use this new node's
+		 * memory - this wait_table must be initialized to use this new
+		 * node itself as well.
+		 * To use this new node's memory, further consideration will be
+		 * necessary.
+		 */
+		zone->wait_table = vmalloc(alloc_size);
+	}
+	if (!zone->wait_table)
+		return -ENOMEM;
+
+	for (i = 0; i < zone->wait_table_hash_nr_entries; ++i)
+		init_waitqueue_head(zone->wait_table + i);
+
+	return 0;
+}
+
+static __meminit void zone_pcp_init(struct zone *zone)
+{
+	/*
+	 * per cpu subsystem is not up at this point. The following code
+	 * relies on the ability of the linker to provide the
+	 * offset of a (static) per cpu variable into the per cpu area.
+	 */
+	zone->pageset = &boot_pageset;
+
+	if (populated_zone(zone))
+		printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%u\n",
+			zone->name, zone->present_pages,
+					 zone_batchsize(zone));
+}
+
+int __meminit init_currently_empty_zone(struct zone *zone,
+					unsigned long zone_start_pfn,
+					unsigned long size)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	int ret;
+	ret = zone_wait_table_init(zone, size);
+	if (ret)
+		return ret;
+	pgdat->nr_zones = zone_idx(zone) + 1;
+
+	zone->zone_start_pfn = zone_start_pfn;
+
+	mminit_dprintk(MMINIT_TRACE, "memmap_init",
+			"Initialising map node %d zone %lu pfns %lu -> %lu\n",
+			pgdat->node_id,
+			(unsigned long)zone_idx(zone),
+			zone_start_pfn, (zone_start_pfn + size));
+
+	zone_init_free_lists(zone);
+
+	return 0;
+}
+
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+#ifndef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
+
+/*
+ * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
+ */
+int __meminit __early_pfn_to_nid(unsigned long pfn,
+					struct mminit_pfnnid_cache *state)
+{
+	unsigned long start_pfn, end_pfn;
+	int nid;
+
+	if (state->last_start <= pfn && pfn < state->last_end)
+		return state->last_nid;
+
+	nid = memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);
+	if (nid != -1) {
+		state->last_start = start_pfn;
+		state->last_end = end_pfn;
+		state->last_nid = nid;
+	}
+
+	return nid;
+}
+#endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */
+
+/**
+ * free_bootmem_with_active_regions - Call memblock_free_early_nid for each active range
+ * @nid: The node to free memory on. If MAX_NUMNODES, all nodes are freed.
+ * @max_low_pfn: The highest PFN that will be passed to memblock_free_early_nid
+ *
+ * If an architecture guarantees that all ranges registered contain no holes
+ * and may be freed, this this function may be used instead of calling
+ * memblock_free_early_nid() manually.
+ */
+void __init free_bootmem_with_active_regions(int nid, unsigned long max_low_pfn)
+{
+	unsigned long start_pfn, end_pfn;
+	int i, this_nid;
+
+	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid) {
+		start_pfn = min(start_pfn, max_low_pfn);
+		end_pfn = min(end_pfn, max_low_pfn);
+
+		if (start_pfn < end_pfn)
+			memblock_free_early_nid(PFN_PHYS(start_pfn),
+					(end_pfn - start_pfn) << PAGE_SHIFT,
+					this_nid);
+	}
+}
+
+/**
+ * sparse_memory_present_with_active_regions - Call memory_present for each active range
+ * @nid: The node to call memory_present for. If MAX_NUMNODES, all nodes will be used.
+ *
+ * If an architecture guarantees that all ranges registered contain no holes and may
+ * be freed, this function may be used instead of calling memory_present() manually.
+ */
+void __init sparse_memory_present_with_active_regions(int nid)
+{
+	unsigned long start_pfn, end_pfn;
+	int i, this_nid;
+
+	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid)
+		memory_present(this_nid, start_pfn, end_pfn);
+}
+
+/**
+ * get_pfn_range_for_nid - Return the start and end page frames for a node
+ * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
+ * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
+ * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
+ *
+ * It returns the start and end page frame of a node based on information
+ * provided by memblock_set_node(). If called for a node
+ * with no available memory, a warning is printed and the start and end
+ * PFNs will be 0.
+ */
+void __meminit get_pfn_range_for_nid(unsigned int nid,
+			unsigned long *start_pfn, unsigned long *end_pfn)
+{
+	unsigned long this_start_pfn, this_end_pfn;
+	int i;
+
+	*start_pfn = -1UL;
+	*end_pfn = 0;
+
+	for_each_mem_pfn_range(i, nid, &this_start_pfn, &this_end_pfn, NULL) {
+		*start_pfn = min(*start_pfn, this_start_pfn);
+		*end_pfn = max(*end_pfn, this_end_pfn);
+	}
+
+	if (*start_pfn == -1UL)
+		*start_pfn = 0;
+}
+
+/*
+ * This finds a zone that can be used for ZONE_MOVABLE pages. The
+ * assumption is made that zones within a node are ordered in monotonic
+ * increasing memory addresses so that the "highest" populated zone is used
+ */
+static void __init find_usable_zone_for_movable(void)
+{
+	int zone_index;
+	for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
+		if (zone_index == ZONE_MOVABLE)
+			continue;
+
+		if (arch_zone_highest_possible_pfn[zone_index] >
+				arch_zone_lowest_possible_pfn[zone_index])
+			break;
+	}
+
+	VM_BUG_ON(zone_index == -1);
+	movable_zone = zone_index;
+}
+
+/*
+ * The zone ranges provided by the architecture do not include ZONE_MOVABLE
+ * because it is sized independent of architecture. Unlike the other zones,
+ * the starting point for ZONE_MOVABLE is not fixed. It may be different
+ * in each node depending on the size of each node and how evenly kernelcore
+ * is distributed. This helper function adjusts the zone ranges
+ * provided by the architecture for a given node by using the end of the
+ * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
+ * zones within a node are in order of monotonic increases memory addresses
+ */
+static void __meminit adjust_zone_range_for_zone_movable(int nid,
+					unsigned long zone_type,
+					unsigned long node_start_pfn,
+					unsigned long node_end_pfn,
+					unsigned long *zone_start_pfn,
+					unsigned long *zone_end_pfn)
+{
+	/* Only adjust if ZONE_MOVABLE is on this node */
+	if (zone_movable_pfn[nid]) {
+		/* Size ZONE_MOVABLE */
+		if (zone_type == ZONE_MOVABLE) {
+			*zone_start_pfn = zone_movable_pfn[nid];
+			*zone_end_pfn = min(node_end_pfn,
+				arch_zone_highest_possible_pfn[movable_zone]);
+
+		/* Adjust for ZONE_MOVABLE starting within this range */
+		} else if (*zone_start_pfn < zone_movable_pfn[nid] &&
+				*zone_end_pfn > zone_movable_pfn[nid]) {
+			*zone_end_pfn = zone_movable_pfn[nid];
+
+		/* Check if this whole range is within ZONE_MOVABLE */
+		} else if (*zone_start_pfn >= zone_movable_pfn[nid])
+			*zone_start_pfn = *zone_end_pfn;
+	}
+}
+
+/*
+ * Return the number of pages a zone spans in a node, including holes
+ * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
+ */
+static unsigned long __meminit zone_spanned_pages_in_node(int nid,
+					unsigned long zone_type,
+					unsigned long node_start_pfn,
+					unsigned long node_end_pfn,
+					unsigned long *ignored)
+{
+	unsigned long zone_start_pfn, zone_end_pfn;
+
+	/* When hotadd a new node from cpu_up(), the node should be empty */
+	if (!node_start_pfn && !node_end_pfn)
+		return 0;
+
+	/* Get the start and end of the zone */
+	zone_start_pfn = arch_zone_lowest_possible_pfn[zone_type];
+	zone_end_pfn = arch_zone_highest_possible_pfn[zone_type];
+	adjust_zone_range_for_zone_movable(nid, zone_type,
+				node_start_pfn, node_end_pfn,
+				&zone_start_pfn, &zone_end_pfn);
+
+	/* Check that this node has pages within the zone's required range */
+	if (zone_end_pfn < node_start_pfn || zone_start_pfn > node_end_pfn)
+		return 0;
+
+	/* Move the zone boundaries inside the node if necessary */
+	zone_end_pfn = min(zone_end_pfn, node_end_pfn);
+	zone_start_pfn = max(zone_start_pfn, node_start_pfn);
+
+	/* Return the spanned pages */
+	return zone_end_pfn - zone_start_pfn;
+}
+
+/*
+ * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
+ * then all holes in the requested range will be accounted for.
+ */
+unsigned long __meminit __absent_pages_in_range(int nid,
+				unsigned long range_start_pfn,
+				unsigned long range_end_pfn)
+{
+	unsigned long nr_absent = range_end_pfn - range_start_pfn;
+	unsigned long start_pfn, end_pfn;
+	int i;
+
+	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
+		start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
+		end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
+		nr_absent -= end_pfn - start_pfn;
+	}
+	return nr_absent;
+}
+
+/**
+ * absent_pages_in_range - Return number of page frames in holes within a range
+ * @start_pfn: The start PFN to start searching for holes
+ * @end_pfn: The end PFN to stop searching for holes
+ *
+ * It returns the number of pages frames in memory holes within a range.
+ */
+unsigned long __init absent_pages_in_range(unsigned long start_pfn,
+							unsigned long end_pfn)
+{
+	return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
+}
+
+/* Return the number of page frames in holes in a zone on a node */
+static unsigned long __meminit zone_absent_pages_in_node(int nid,
+					unsigned long zone_type,
+					unsigned long node_start_pfn,
+					unsigned long node_end_pfn,
+					unsigned long *ignored)
+{
+	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
+	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
+	unsigned long zone_start_pfn, zone_end_pfn;
+
+	/* When hotadd a new node from cpu_up(), the node should be empty */
+	if (!node_start_pfn && !node_end_pfn)
+		return 0;
+
+	zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
+	zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
+
+	adjust_zone_range_for_zone_movable(nid, zone_type,
+			node_start_pfn, node_end_pfn,
+			&zone_start_pfn, &zone_end_pfn);
+	return __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
+}
+
+#else /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+static inline unsigned long __meminit zone_spanned_pages_in_node(int nid,
+					unsigned long zone_type,
+					unsigned long node_start_pfn,
+					unsigned long node_end_pfn,
+					unsigned long *zones_size)
+{
+	return zones_size[zone_type];
+}
+
+static inline unsigned long __meminit zone_absent_pages_in_node(int nid,
+						unsigned long zone_type,
+						unsigned long node_start_pfn,
+						unsigned long node_end_pfn,
+						unsigned long *zholes_size)
+{
+	if (!zholes_size)
+		return 0;
+
+	return zholes_size[zone_type];
+}
+
+#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+
+static void __meminit calculate_node_totalpages(struct pglist_data *pgdat,
+						unsigned long node_start_pfn,
+						unsigned long node_end_pfn,
+						unsigned long *zones_size,
+						unsigned long *zholes_size)
+{
+	unsigned long realtotalpages = 0, totalpages = 0;
+	enum zone_type i;
+
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		struct zone *zone = pgdat->node_zones + i;
+		unsigned long size, real_size;
+
+		size = zone_spanned_pages_in_node(pgdat->node_id, i,
+						  node_start_pfn,
+						  node_end_pfn,
+						  zones_size);
+		real_size = size - zone_absent_pages_in_node(pgdat->node_id, i,
+						  node_start_pfn, node_end_pfn,
+						  zholes_size);
+		zone->spanned_pages = size;
+		zone->present_pages = real_size;
+
+		totalpages += size;
+		realtotalpages += real_size;
+	}
+
+	pgdat->node_spanned_pages = totalpages;
+	pgdat->node_present_pages = realtotalpages;
+	printk(KERN_DEBUG "On node %d totalpages: %lu\n", pgdat->node_id,
+							realtotalpages);
+}
+
+#ifndef CONFIG_SPARSEMEM
+/*
+ * Calculate the size of the zone->blockflags rounded to an unsigned long
+ * Start by making sure zonesize is a multiple of pageblock_order by rounding
+ * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
+ * round what is now in bits to nearest long in bits, then return it in
+ * bytes.
+ */
+static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned long zonesize)
+{
+	unsigned long usemapsize;
+
+	zonesize += zone_start_pfn & (pageblock_nr_pages-1);
+	usemapsize = roundup(zonesize, pageblock_nr_pages);
+	usemapsize = usemapsize >> pageblock_order;
+	usemapsize *= NR_PAGEBLOCK_BITS;
+	usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));
+
+	return usemapsize / 8;
+}
+
+static void __init setup_usemap(struct pglist_data *pgdat,
+				struct zone *zone,
+				unsigned long zone_start_pfn,
+				unsigned long zonesize)
+{
+	unsigned long usemapsize = usemap_size(zone_start_pfn, zonesize);
+	zone->pageblock_flags = NULL;
+	if (usemapsize)
+		zone->pageblock_flags =
+			memblock_virt_alloc_node_nopanic(usemapsize,
+							 pgdat->node_id);
+}
+#else
+static inline void setup_usemap(struct pglist_data *pgdat, struct zone *zone,
+				unsigned long zone_start_pfn, unsigned long zonesize) {}
+#endif /* CONFIG_SPARSEMEM */
+
+#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+
+/* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
+void __paginginit set_pageblock_order(void)
+{
+	unsigned int order;
+
+	/* Check that pageblock_nr_pages has not already been setup */
+	if (pageblock_order)
+		return;
+
+	if (HPAGE_SHIFT > PAGE_SHIFT)
+		order = HUGETLB_PAGE_ORDER;
+	else
+		order = MAX_ORDER - 1;
+
+	/*
+	 * Assume the largest contiguous order of interest is a huge page.
+	 * This value may be variable depending on boot parameters on IA64 and
+	 * powerpc.
+	 */
+	pageblock_order = order;
+}
+#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+
+/*
+ * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
+ * is unused as pageblock_order is set at compile-time. See
+ * include/linux/pageblock-flags.h for the values of pageblock_order based on
+ * the kernel config
+ */
+void __paginginit set_pageblock_order(void)
+{
+}
+
+#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+
+static unsigned long __paginginit calc_memmap_size(unsigned long spanned_pages,
+						   unsigned long present_pages)
+{
+	unsigned long pages = spanned_pages;
+
+	/*
+	 * Provide a more accurate estimation if there are holes within
+	 * the zone and SPARSEMEM is in use. If there are holes within the
+	 * zone, each populated memory region may cost us one or two extra
+	 * memmap pages due to alignment because memmap pages for each
+	 * populated regions may not naturally algined on page boundary.
+	 * So the (present_pages >> 4) heuristic is a tradeoff for that.
+	 */
+	if (spanned_pages > present_pages + (present_pages >> 4) &&
+	    IS_ENABLED(CONFIG_SPARSEMEM))
+		pages = present_pages;
+
+	return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT;
+}
+
+/*
+ * Set up the zone data structures:
+ *   - mark all pages reserved
+ *   - mark all memory queues empty
+ *   - clear the memory bitmaps
+ *
+ * NOTE: pgdat should get zeroed by caller.
+ */
+static void __paginginit free_area_init_core(struct pglist_data *pgdat)
+{
+	enum zone_type j;
+	int nid = pgdat->node_id;
+	unsigned long zone_start_pfn = pgdat->node_start_pfn;
+	int ret;
+
+	pgdat_resize_init(pgdat);
+#ifdef CONFIG_NUMA_BALANCING
+	spin_lock_init(&pgdat->numabalancing_migrate_lock);
+	pgdat->numabalancing_migrate_nr_pages = 0;
+	pgdat->numabalancing_migrate_next_window = jiffies;
+#endif
+	init_waitqueue_head(&pgdat->kswapd_wait);
+	init_waitqueue_head(&pgdat->pfmemalloc_wait);
+	pgdat_page_ext_init(pgdat);
+
+	for (j = 0; j < MAX_NR_ZONES; j++) {
+		struct zone *zone = pgdat->node_zones + j;
+		unsigned long size, realsize, freesize, memmap_pages;
+
+		size = zone->spanned_pages;
+		realsize = freesize = zone->present_pages;
+
+		/*
+		 * Adjust freesize so that it accounts for how much memory
+		 * is used by this zone for memmap. This affects the watermark
+		 * and per-cpu initialisations
+		 */
+		memmap_pages = calc_memmap_size(size, realsize);
+		if (!is_highmem_idx(j)) {
+			if (freesize >= memmap_pages) {
+				freesize -= memmap_pages;
+				if (memmap_pages)
+					printk(KERN_DEBUG
+					       "  %s zone: %lu pages used for memmap\n",
+					       zone_names[j], memmap_pages);
+			} else
+				printk(KERN_WARNING
+					"  %s zone: %lu pages exceeds freesize %lu\n",
+					zone_names[j], memmap_pages, freesize);
+		}
+
+		/* Account for reserved pages */
+		if (j == 0 && freesize > dma_reserve) {
+			freesize -= dma_reserve;
+			printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",
+					zone_names[0], dma_reserve);
+		}
+
+		if (!is_highmem_idx(j))
+			nr_kernel_pages += freesize;
+		/* Charge for highmem memmap if there are enough kernel pages */
+		else if (nr_kernel_pages > memmap_pages * 2)
+			nr_kernel_pages -= memmap_pages;
+		nr_all_pages += freesize;
+
+		/*
+		 * Set an approximate value for lowmem here, it will be adjusted
+		 * when the bootmem allocator frees pages into the buddy system.
+		 * And all highmem pages will be managed by the buddy system.
+		 */
+		zone->managed_pages = is_highmem_idx(j) ? realsize : freesize;
+#ifdef CONFIG_NUMA
+		zone->node = nid;
+		zone->min_unmapped_pages = (freesize*sysctl_min_unmapped_ratio)
+						/ 100;
+		zone->min_slab_pages = (freesize * sysctl_min_slab_ratio) / 100;
+#endif
+		zone->name = zone_names[j];
+		spin_lock_init(&zone->lock);
+		spin_lock_init(&zone->lru_lock);
+		zone_seqlock_init(zone);
+		zone->zone_pgdat = pgdat;
+		zone_pcp_init(zone);
+
+		/* For bootup, initialized properly in watermark setup */
+		mod_zone_page_state(zone, NR_ALLOC_BATCH, zone->managed_pages);
+
+		lruvec_init(&zone->lruvec);
+		if (!size)
+			continue;
+
+		set_pageblock_order();
+		setup_usemap(pgdat, zone, zone_start_pfn, size);
+		ret = init_currently_empty_zone(zone, zone_start_pfn, size);
+		BUG_ON(ret);
+		memmap_init(size, nid, j, zone_start_pfn);
+		zone_start_pfn += size;
+	}
+}
+
+static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
+{
+	unsigned long __maybe_unused start = 0;
+	unsigned long __maybe_unused offset = 0;
+
+	/* Skip empty nodes */
+	if (!pgdat->node_spanned_pages)
+		return;
+
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
+	start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
+	offset = pgdat->node_start_pfn - start;
+	/* ia64 gets its own node_mem_map, before this, without bootmem */
+	if (!pgdat->node_mem_map) {
+		unsigned long size, end;
+		struct page *map;
+
+		/*
+		 * The zone's endpoints aren't required to be MAX_ORDER
+		 * aligned but the node_mem_map endpoints must be in order
+		 * for the buddy allocator to function correctly.
+		 */
+		end = pgdat_end_pfn(pgdat);
+		end = ALIGN(end, MAX_ORDER_NR_PAGES);
+		size =  (end - start) * sizeof(struct page);
+		map = alloc_remap(pgdat->node_id, size);
+		if (!map)
+			map = memblock_virt_alloc_node_nopanic(size,
+							       pgdat->node_id);
+		pgdat->node_mem_map = map + offset;
+	}
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+	/*
+	 * With no DISCONTIG, the global mem_map is just set as node 0's
+	 */
+	if (pgdat == NODE_DATA(0)) {
+		mem_map = NODE_DATA(0)->node_mem_map;
+#if defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) || defined(CONFIG_FLATMEM)
+		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
+			mem_map -= offset;
+#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+	}
+#endif
+#endif /* CONFIG_FLAT_NODE_MEM_MAP */
+}
+
+void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
+		unsigned long node_start_pfn, unsigned long *zholes_size)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+	unsigned long start_pfn = 0;
+	unsigned long end_pfn = 0;
+
+	/* pg_data_t should be reset to zero when it's allocated */
+	WARN_ON(pgdat->nr_zones || pgdat->classzone_idx);
+
+	pgdat->node_id = nid;
+	pgdat->node_start_pfn = node_start_pfn;
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+	get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
+	pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
+		(u64)start_pfn << PAGE_SHIFT,
+		end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
+#endif
+	calculate_node_totalpages(pgdat, start_pfn, end_pfn,
+				  zones_size, zholes_size);
+
+	alloc_node_mem_map(pgdat);
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
+	printk(KERN_DEBUG "free_area_init_node: node %d, pgdat %08lx, node_mem_map %08lx\n",
+		nid, (unsigned long)pgdat,
+		(unsigned long)pgdat->node_mem_map);
+#endif
+
+	reset_deferred_meminit(pgdat);
+	free_area_init_core(pgdat);
+}
+
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+
+#if MAX_NUMNODES > 1
+/*
+ * Figure out the number of possible node ids.
+ */
+void __init setup_nr_node_ids(void)
+{
+	unsigned int highest;
+
+	highest = find_last_bit(node_possible_map.bits, MAX_NUMNODES);
+	nr_node_ids = highest + 1;
+}
+#endif
+
+/**
+ * node_map_pfn_alignment - determine the maximum internode alignment
+ *
+ * This function should be called after node map is populated and sorted.
+ * It calculates the maximum power of two alignment which can distinguish
+ * all the nodes.
+ *
+ * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
+ * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)).  If the
+ * nodes are shifted by 256MiB, 256MiB.  Note that if only the last node is
+ * shifted, 1GiB is enough and this function will indicate so.
+ *
+ * This is used to test whether pfn -> nid mapping of the chosen memory
+ * model has fine enough granularity to avoid incorrect mapping for the
+ * populated node map.
+ *
+ * Returns the determined alignment in pfn's.  0 if there is no alignment
+ * requirement (single node).
+ */
+unsigned long __init node_map_pfn_alignment(void)
+{
+	unsigned long accl_mask = 0, last_end = 0;
+	unsigned long start, end, mask;
+	int last_nid = -1;
+	int i, nid;
+
+	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {
+		if (!start || last_nid < 0 || last_nid == nid) {
+			last_nid = nid;
+			last_end = end;
+			continue;
+		}
+
+		/*
+		 * Start with a mask granular enough to pin-point to the
+		 * start pfn and tick off bits one-by-one until it becomes
+		 * too coarse to separate the current node from the last.
+		 */
+		mask = ~((1 << __ffs(start)) - 1);
+		while (mask && last_end <= (start & (mask << 1)))
+			mask <<= 1;
+
+		/* accumulate all internode masks */
+		accl_mask |= mask;
+	}
+
+	/* convert mask to number of pages */
+	return ~accl_mask + 1;
+}
+
+/* Find the lowest pfn for a node */
+static unsigned long __init find_min_pfn_for_node(int nid)
+{
+	unsigned long min_pfn = ULONG_MAX;
+	unsigned long start_pfn;
+	int i;
+
+	for_each_mem_pfn_range(i, nid, &start_pfn, NULL, NULL)
+		min_pfn = min(min_pfn, start_pfn);
+
+	if (min_pfn == ULONG_MAX) {
+		printk(KERN_WARNING
+			"Could not find start_pfn for node %d\n", nid);
+		return 0;
+	}
+
+	return min_pfn;
+}
+
+/**
+ * find_min_pfn_with_active_regions - Find the minimum PFN registered
+ *
+ * It returns the minimum PFN based on information provided via
+ * memblock_set_node().
+ */
+unsigned long __init find_min_pfn_with_active_regions(void)
+{
+	return find_min_pfn_for_node(MAX_NUMNODES);
+}
+
+/*
+ * early_calculate_totalpages()
+ * Sum pages in active regions for movable zone.
+ * Populate N_MEMORY for calculating usable_nodes.
+ */
+static unsigned long __init early_calculate_totalpages(void)
+{
+	unsigned long totalpages = 0;
+	unsigned long start_pfn, end_pfn;
+	int i, nid;
+
+	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
+		unsigned long pages = end_pfn - start_pfn;
+
+		totalpages += pages;
+		if (pages)
+			node_set_state(nid, N_MEMORY);
+	}
+	return totalpages;
+}
+
+/*
+ * Find the PFN the Movable zone begins in each node. Kernel memory
+ * is spread evenly between nodes as long as the nodes have enough
+ * memory. When they don't, some nodes will have more kernelcore than
+ * others
+ */
+static void __init find_zone_movable_pfns_for_nodes(void)
+{
+	int i, nid;
+	unsigned long usable_startpfn;
+	unsigned long kernelcore_node, kernelcore_remaining;
+	/* save the state before borrow the nodemask */
+	nodemask_t saved_node_state = node_states[N_MEMORY];
+	unsigned long totalpages = early_calculate_totalpages();
+	int usable_nodes = nodes_weight(node_states[N_MEMORY]);
+	struct memblock_region *r;
+
+	/* Need to find movable_zone earlier when movable_node is specified. */
+	find_usable_zone_for_movable();
+
+	/*
+	 * If movable_node is specified, ignore kernelcore and movablecore
+	 * options.
+	 */
+	if (movable_node_is_enabled()) {
+		for_each_memblock(memory, r) {
+			if (!memblock_is_hotpluggable(r))
+				continue;
+
+			nid = r->nid;
+
+			usable_startpfn = PFN_DOWN(r->base);
+			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
+				min(usable_startpfn, zone_movable_pfn[nid]) :
+				usable_startpfn;
+		}
+
+		goto out2;
+	}
+
+	/*
+	 * If movablecore=nn[KMG] was specified, calculate what size of
+	 * kernelcore that corresponds so that memory usable for
+	 * any allocation type is evenly spread. If both kernelcore
+	 * and movablecore are specified, then the value of kernelcore
+	 * will be used for required_kernelcore if it's greater than
+	 * what movablecore would have allowed.
+	 */
+	if (required_movablecore) {
+		unsigned long corepages;
+
+		/*
+		 * Round-up so that ZONE_MOVABLE is at least as large as what
+		 * was requested by the user
+		 */
+		required_movablecore =
+			roundup(required_movablecore, MAX_ORDER_NR_PAGES);
+		required_movablecore = min(totalpages, required_movablecore);
+		corepages = totalpages - required_movablecore;
+
+		required_kernelcore = max(required_kernelcore, corepages);
+	}
+
+	/*
+	 * If kernelcore was not specified or kernelcore size is larger
+	 * than totalpages, there is no ZONE_MOVABLE.
+	 */
+	if (!required_kernelcore || required_kernelcore >= totalpages)
+		goto out;
+
+	/* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
+	usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
+
+restart:
+	/* Spread kernelcore memory as evenly as possible throughout nodes */
+	kernelcore_node = required_kernelcore / usable_nodes;
+	for_each_node_state(nid, N_MEMORY) {
+		unsigned long start_pfn, end_pfn;
+
+		/*
+		 * Recalculate kernelcore_node if the division per node
+		 * now exceeds what is necessary to satisfy the requested
+		 * amount of memory for the kernel
+		 */
+		if (required_kernelcore < kernelcore_node)
+			kernelcore_node = required_kernelcore / usable_nodes;
+
+		/*
+		 * As the map is walked, we track how much memory is usable
+		 * by the kernel using kernelcore_remaining. When it is
+		 * 0, the rest of the node is usable by ZONE_MOVABLE
+		 */
+		kernelcore_remaining = kernelcore_node;
+
+		/* Go through each range of PFNs within this node */
+		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
+			unsigned long size_pages;
+
+			start_pfn = max(start_pfn, zone_movable_pfn[nid]);
+			if (start_pfn >= end_pfn)
+				continue;
+
+			/* Account for what is only usable for kernelcore */
+			if (start_pfn < usable_startpfn) {
+				unsigned long kernel_pages;
+				kernel_pages = min(end_pfn, usable_startpfn)
+								- start_pfn;
+
+				kernelcore_remaining -= min(kernel_pages,
+							kernelcore_remaining);
+				required_kernelcore -= min(kernel_pages,
+							required_kernelcore);
+
+				/* Continue if range is now fully accounted */
+				if (end_pfn <= usable_startpfn) {
+
+					/*
+					 * Push zone_movable_pfn to the end so
+					 * that if we have to rebalance
+					 * kernelcore across nodes, we will
+					 * not double account here
+					 */
+					zone_movable_pfn[nid] = end_pfn;
+					continue;
+				}
+				start_pfn = usable_startpfn;
+			}
+
+			/*
+			 * The usable PFN range for ZONE_MOVABLE is from
+			 * start_pfn->end_pfn. Calculate size_pages as the
+			 * number of pages used as kernelcore
+			 */
+			size_pages = end_pfn - start_pfn;
+			if (size_pages > kernelcore_remaining)
+				size_pages = kernelcore_remaining;
+			zone_movable_pfn[nid] = start_pfn + size_pages;
+
+			/*
+			 * Some kernelcore has been met, update counts and
+			 * break if the kernelcore for this node has been
+			 * satisfied
+			 */
+			required_kernelcore -= min(required_kernelcore,
+								size_pages);
+			kernelcore_remaining -= size_pages;
+			if (!kernelcore_remaining)
+				break;
+		}
+	}
+
+	/*
+	 * If there is still required_kernelcore, we do another pass with one
+	 * less node in the count. This will push zone_movable_pfn[nid] further
+	 * along on the nodes that still have memory until kernelcore is
+	 * satisfied
+	 */
+	usable_nodes--;
+	if (usable_nodes && required_kernelcore > usable_nodes)
+		goto restart;
+
+out2:
+	/* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
+	for (nid = 0; nid < MAX_NUMNODES; nid++)
+		zone_movable_pfn[nid] =
+			roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
+
+out:
+	/* restore the node_state */
+	node_states[N_MEMORY] = saved_node_state;
+}
+
+/* Any regular or high memory on that node ? */
+static void check_for_memory(pg_data_t *pgdat, int nid)
+{
+	enum zone_type zone_type;
+
+	if (N_MEMORY == N_NORMAL_MEMORY)
+		return;
+
+	for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
+		struct zone *zone = &pgdat->node_zones[zone_type];
+		if (populated_zone(zone)) {
+			node_set_state(nid, N_HIGH_MEMORY);
+			if (N_NORMAL_MEMORY != N_HIGH_MEMORY &&
+			    zone_type <= ZONE_NORMAL)
+				node_set_state(nid, N_NORMAL_MEMORY);
+			break;
+		}
+	}
+}
+
+/**
+ * free_area_init_nodes - Initialise all pg_data_t and zone data
+ * @max_zone_pfn: an array of max PFNs for each zone
+ *
+ * This will call free_area_init_node() for each active node in the system.
+ * Using the page ranges provided by memblock_set_node(), the size of each
+ * zone in each node and their holes is calculated. If the maximum PFN
+ * between two adjacent zones match, it is assumed that the zone is empty.
+ * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
+ * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
+ * starts where the previous one ended. For example, ZONE_DMA32 starts
+ * at arch_max_dma_pfn.
+ */
+void __init free_area_init_nodes(unsigned long *max_zone_pfn)
+{
+	unsigned long start_pfn, end_pfn;
+	int i, nid;
+
+	/* Record where the zone boundaries are */
+	memset(arch_zone_lowest_possible_pfn, 0,
+				sizeof(arch_zone_lowest_possible_pfn));
+	memset(arch_zone_highest_possible_pfn, 0,
+				sizeof(arch_zone_highest_possible_pfn));
+
+	start_pfn = find_min_pfn_with_active_regions();
+
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		if (i == ZONE_MOVABLE)
+			continue;
+
+		end_pfn = max(max_zone_pfn[i], start_pfn);
+		arch_zone_lowest_possible_pfn[i] = start_pfn;
+		arch_zone_highest_possible_pfn[i] = end_pfn;
+
+		start_pfn = end_pfn;
+	}
+	arch_zone_lowest_possible_pfn[ZONE_MOVABLE] = 0;
+	arch_zone_highest_possible_pfn[ZONE_MOVABLE] = 0;
+
+	/* Find the PFNs that ZONE_MOVABLE begins at in each node */
+	memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
+	find_zone_movable_pfns_for_nodes();
+
+	/* Print out the zone ranges */
+	pr_info("Zone ranges:\n");
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		if (i == ZONE_MOVABLE)
+			continue;
+		pr_info("  %-8s ", zone_names[i]);
+		if (arch_zone_lowest_possible_pfn[i] ==
+				arch_zone_highest_possible_pfn[i])
+			pr_cont("empty\n");
+		else
+			pr_cont("[mem %#018Lx-%#018Lx]\n",
+				(u64)arch_zone_lowest_possible_pfn[i]
+					<< PAGE_SHIFT,
+				((u64)arch_zone_highest_possible_pfn[i]
+					<< PAGE_SHIFT) - 1);
+	}
+
+	/* Print out the PFNs ZONE_MOVABLE begins at in each node */
+	pr_info("Movable zone start for each node\n");
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		if (zone_movable_pfn[i])
+			pr_info("  Node %d: %#018Lx\n", i,
+			       (u64)zone_movable_pfn[i] << PAGE_SHIFT);
+	}
+
+	/* Print out the early node map */
+	pr_info("Early memory node ranges\n");
+	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid)
+		pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
+			(u64)start_pfn << PAGE_SHIFT,
+			((u64)end_pfn << PAGE_SHIFT) - 1);
+
+	/* Initialise every node */
+	mminit_verify_pageflags_layout();
+	setup_nr_node_ids();
+	for_each_online_node(nid) {
+		pg_data_t *pgdat = NODE_DATA(nid);
+		free_area_init_node(nid, NULL,
+				find_min_pfn_for_node(nid), NULL);
+
+		/* Any memory on that node */
+		if (pgdat->node_present_pages)
+			node_set_state(nid, N_MEMORY);
+		check_for_memory(pgdat, nid);
+	}
+}
+
+static int __init cmdline_parse_core(char *p, unsigned long *core)
+{
+	unsigned long long coremem;
+	if (!p)
+		return -EINVAL;
+
+	coremem = memparse(p, &p);
+	*core = coremem >> PAGE_SHIFT;
+
+	/* Paranoid check that UL is enough for the coremem value */
+	WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);
+
+	return 0;
+}
+
+/*
+ * kernelcore=size sets the amount of memory for use for allocations that
+ * cannot be reclaimed or migrated.
+ */
+static int __init cmdline_parse_kernelcore(char *p)
+{
+	return cmdline_parse_core(p, &required_kernelcore);
+}
+
+/*
+ * movablecore=size sets the amount of memory for use for allocations that
+ * can be reclaimed or migrated.
+ */
+static int __init cmdline_parse_movablecore(char *p)
+{
+	return cmdline_parse_core(p, &required_movablecore);
+}
+
+early_param("kernelcore", cmdline_parse_kernelcore);
+early_param("movablecore", cmdline_parse_movablecore);
+
+#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+
+void adjust_managed_page_count(struct page *page, long count)
+{
+	spin_lock(&managed_page_count_lock);
+	page_zone(page)->managed_pages += count;
+	totalram_pages += count;
+#ifdef CONFIG_HIGHMEM
+	if (PageHighMem(page))
+		totalhigh_pages += count;
+#endif
+	spin_unlock(&managed_page_count_lock);
+}
+EXPORT_SYMBOL(adjust_managed_page_count);
+
+unsigned long free_reserved_area(void *start, void *end, int poison, char *s)
+{
+	void *pos;
+	unsigned long pages = 0;
+
+	start = (void *)PAGE_ALIGN((unsigned long)start);
+	end = (void *)((unsigned long)end & PAGE_MASK);
+	for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
+		if ((unsigned int)poison <= 0xFF)
+			memset(pos, poison, PAGE_SIZE);
+		free_reserved_page(virt_to_page(pos));
+	}
+
+	if (pages && s)
+		pr_info("Freeing %s memory: %ldK\n",
+			s, pages << (PAGE_SHIFT - 10));
+
+	return pages;
+}
+EXPORT_SYMBOL(free_reserved_area);
+
+#ifdef	CONFIG_HIGHMEM
+void free_highmem_page(struct page *page)
+{
+	__free_reserved_page(page);
+	totalram_pages++;
+	page_zone(page)->managed_pages++;
+	totalhigh_pages++;
+}
+#endif
+
+
+void __init mem_init_print_info(const char *str)
+{
+	unsigned long physpages, codesize, datasize, rosize, bss_size;
+	unsigned long init_code_size, init_data_size;
+
+	physpages = get_num_physpages();
+	codesize = _etext - _stext;
+	datasize = _edata - _sdata;
+	rosize = __end_rodata - __start_rodata;
+	bss_size = __bss_stop - __bss_start;
+	init_data_size = __init_end - __init_begin;
+	init_code_size = _einittext - _sinittext;
+
+	/*
+	 * Detect special cases and adjust section sizes accordingly:
+	 * 1) .init.* may be embedded into .data sections
+	 * 2) .init.text.* may be out of [__init_begin, __init_end],
+	 *    please refer to arch/tile/kernel/vmlinux.lds.S.
+	 * 3) .rodata.* may be embedded into .text or .data sections.
+	 */
+#define adj_init_size(start, end, size, pos, adj) \
+	do { \
+		if (start <= pos && pos < end && size > adj) \
+			size -= adj; \
+	} while (0)
+
+	adj_init_size(__init_begin, __init_end, init_data_size,
+		     _sinittext, init_code_size);
+	adj_init_size(_stext, _etext, codesize, _sinittext, init_code_size);
+	adj_init_size(_sdata, _edata, datasize, __init_begin, init_data_size);
+	adj_init_size(_stext, _etext, codesize, __start_rodata, rosize);
+	adj_init_size(_sdata, _edata, datasize, __start_rodata, rosize);
+
+#undef	adj_init_size
+
+	pr_info("Memory: %luK/%luK available "
+	       "(%luK kernel code, %luK rwdata, %luK rodata, "
+	       "%luK init, %luK bss, %luK reserved, %luK cma-reserved"
+#ifdef	CONFIG_HIGHMEM
+	       ", %luK highmem"
+#endif
+	       "%s%s)\n",
+	       nr_free_pages() << (PAGE_SHIFT-10), physpages << (PAGE_SHIFT-10),
+	       codesize >> 10, datasize >> 10, rosize >> 10,
+	       (init_data_size + init_code_size) >> 10, bss_size >> 10,
+	       (physpages - totalram_pages - totalcma_pages) << (PAGE_SHIFT-10),
+	       totalcma_pages << (PAGE_SHIFT-10),
+#ifdef	CONFIG_HIGHMEM
+	       totalhigh_pages << (PAGE_SHIFT-10),
+#endif
+	       str ? ", " : "", str ? str : "");
+}
+
+/**
+ * set_dma_reserve - set the specified number of pages reserved in the first zone
+ * @new_dma_reserve: The number of pages to mark reserved
+ *
+ * The per-cpu batchsize and zone watermarks are determined by managed_pages.
+ * In the DMA zone, a significant percentage may be consumed by kernel image
+ * and other unfreeable allocations which can skew the watermarks badly. This
+ * function may optionally be used to account for unfreeable pages in the
+ * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
+ * smaller per-cpu batchsize.
+ */
+void __init set_dma_reserve(unsigned long new_dma_reserve)
+{
+	dma_reserve = new_dma_reserve;
+}
+
+void __init free_area_init(unsigned long *zones_size)
+{
+	free_area_init_node(0, zones_size,
+			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
+}
+
+static int page_alloc_cpu_notify(struct notifier_block *self,
+				 unsigned long action, void *hcpu)
+{
+	int cpu = (unsigned long)hcpu;
+
+	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
+		lru_add_drain_cpu(cpu);
+		drain_pages(cpu);
+
+		/*
+		 * Spill the event counters of the dead processor
+		 * into the current processors event counters.
+		 * This artificially elevates the count of the current
+		 * processor.
+		 */
+		vm_events_fold_cpu(cpu);
+
+		/*
+		 * Zero the differential counters of the dead processor
+		 * so that the vm statistics are consistent.
+		 *
+		 * This is only okay since the processor is dead and cannot
+		 * race with what we are doing.
+		 */
+		cpu_vm_stats_fold(cpu);
+	}
+	return NOTIFY_OK;
+}
+
+void __init page_alloc_init(void)
+{
+	hotcpu_notifier(page_alloc_cpu_notify, 0);
+}
+
+/*
+ * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
+ *	or min_free_kbytes changes.
+ */
+static void calculate_totalreserve_pages(void)
+{
+	struct pglist_data *pgdat;
+	unsigned long reserve_pages = 0;
+	enum zone_type i, j;
+
+	for_each_online_pgdat(pgdat) {
+		for (i = 0; i < MAX_NR_ZONES; i++) {
+			struct zone *zone = pgdat->node_zones + i;
+			long max = 0;
+
+			/* Find valid and maximum lowmem_reserve in the zone */
+			for (j = i; j < MAX_NR_ZONES; j++) {
+				if (zone->lowmem_reserve[j] > max)
+					max = zone->lowmem_reserve[j];
+			}
+
+			/* we treat the high watermark as reserved pages. */
+			max += high_wmark_pages(zone);
+
+			if (max > zone->managed_pages)
+				max = zone->managed_pages;
+			reserve_pages += max;
+			/*
+			 * Lowmem reserves are not available to
+			 * GFP_HIGHUSER page cache allocations and
+			 * kswapd tries to balance zones to their high
+			 * watermark.  As a result, neither should be
+			 * regarded as dirtyable memory, to prevent a
+			 * situation where reclaim has to clean pages
+			 * in order to balance the zones.
+			 */
+			zone->dirty_balance_reserve = max;
+		}
+	}
+	dirty_balance_reserve = reserve_pages;
+	totalreserve_pages = reserve_pages;
+}
+
+/*
+ * setup_per_zone_lowmem_reserve - called whenever
+ *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
+ *	has a correct pages reserved value, so an adequate number of
+ *	pages are left in the zone after a successful __alloc_pages().
+ */
+static void setup_per_zone_lowmem_reserve(void)
+{
+	struct pglist_data *pgdat;
+	enum zone_type j, idx;
+
+	for_each_online_pgdat(pgdat) {
+		for (j = 0; j < MAX_NR_ZONES; j++) {
+			struct zone *zone = pgdat->node_zones + j;
+			unsigned long managed_pages = zone->managed_pages;
+
+			zone->lowmem_reserve[j] = 0;
+
+			idx = j;
+			while (idx) {
+				struct zone *lower_zone;
+
+				idx--;
+
+				if (sysctl_lowmem_reserve_ratio[idx] < 1)
+					sysctl_lowmem_reserve_ratio[idx] = 1;
+
+				lower_zone = pgdat->node_zones + idx;
+				lower_zone->lowmem_reserve[j] = managed_pages /
+					sysctl_lowmem_reserve_ratio[idx];
+				managed_pages += lower_zone->managed_pages;
+			}
+		}
+	}
+
+	/* update totalreserve_pages */
+	calculate_totalreserve_pages();
+}
+
+static void __setup_per_zone_wmarks(void)
+{
+	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
+	unsigned long lowmem_pages = 0;
+	struct zone *zone;
+	unsigned long flags;
+
+	/* Calculate total number of !ZONE_HIGHMEM pages */
+	for_each_zone(zone) {
+		if (!is_highmem(zone))
+			lowmem_pages += zone->managed_pages;
+	}
+
+	for_each_zone(zone) {
+		u64 tmp;
+
+		spin_lock_irqsave(&zone->lock, flags);
+		tmp = (u64)pages_min * zone->managed_pages;
+		do_div(tmp, lowmem_pages);
+		if (is_highmem(zone)) {
+			/*
+			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
+			 * need highmem pages, so cap pages_min to a small
+			 * value here.
+			 *
+			 * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
+			 * deltas control asynch page reclaim, and so should
+			 * not be capped for highmem.
+			 */
+			unsigned long min_pages;
+
+			min_pages = zone->managed_pages / 1024;
+			min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
+			zone->watermark[WMARK_MIN] = min_pages;
+		} else {
+			/*
+			 * If it's a lowmem zone, reserve a number of pages
+			 * proportionate to the zone's size.
+			 */
+			zone->watermark[WMARK_MIN] = tmp;
+		}
+
+		zone->watermark[WMARK_LOW]  = min_wmark_pages(zone) + (tmp >> 2);
+		zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1);
+
+		__mod_zone_page_state(zone, NR_ALLOC_BATCH,
+			high_wmark_pages(zone) - low_wmark_pages(zone) -
+			atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]));
+
+		spin_unlock_irqrestore(&zone->lock, flags);
+	}
+
+	/* update totalreserve_pages */
+	calculate_totalreserve_pages();
+}
+
+/**
+ * setup_per_zone_wmarks - called when min_free_kbytes changes
+ * or when memory is hot-{added|removed}
+ *
+ * Ensures that the watermark[min,low,high] values for each zone are set
+ * correctly with respect to min_free_kbytes.
+ */
+void setup_per_zone_wmarks(void)
+{
+	mutex_lock(&zonelists_mutex);
+	__setup_per_zone_wmarks();
+	mutex_unlock(&zonelists_mutex);
+}
+
+/*
+ * The inactive anon list should be small enough that the VM never has to
+ * do too much work, but large enough that each inactive page has a chance
+ * to be referenced again before it is swapped out.
+ *
+ * The inactive_anon ratio is the target ratio of ACTIVE_ANON to
+ * INACTIVE_ANON pages on this zone's LRU, maintained by the
+ * pageout code. A zone->inactive_ratio of 3 means 3:1 or 25% of
+ * the anonymous pages are kept on the inactive list.
+ *
+ * total     target    max
+ * memory    ratio     inactive anon
+ * -------------------------------------
+ *   10MB       1         5MB
+ *  100MB       1        50MB
+ *    1GB       3       250MB
+ *   10GB      10       0.9GB
+ *  100GB      31         3GB
+ *    1TB     101        10GB
+ *   10TB     320        32GB
+ */
+static void __meminit calculate_zone_inactive_ratio(struct zone *zone)
+{
+	unsigned int gb, ratio;
+
+	/* Zone size in gigabytes */
+	gb = zone->managed_pages >> (30 - PAGE_SHIFT);
+	if (gb)
+		ratio = int_sqrt(10 * gb);
+	else
+		ratio = 1;
+
+	zone->inactive_ratio = ratio;
+}
+
+static void __meminit setup_per_zone_inactive_ratio(void)
+{
+	struct zone *zone;
+
+	for_each_zone(zone)
+		calculate_zone_inactive_ratio(zone);
+}
+
+/*
+ * Initialise min_free_kbytes.
+ *
+ * For small machines we want it small (128k min).  For large machines
+ * we want it large (64MB max).  But it is not linear, because network
+ * bandwidth does not increase linearly with machine size.  We use
+ *
+ *	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
+ *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
+ *
+ * which yields
+ *
+ * 16MB:	512k
+ * 32MB:	724k
+ * 64MB:	1024k
+ * 128MB:	1448k
+ * 256MB:	2048k
+ * 512MB:	2896k
+ * 1024MB:	4096k
+ * 2048MB:	5792k
+ * 4096MB:	8192k
+ * 8192MB:	11584k
+ * 16384MB:	16384k
+ */
+int __meminit init_per_zone_wmark_min(void)
+{
+	unsigned long lowmem_kbytes;
+	int new_min_free_kbytes;
+
+	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
+	new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
+
+	if (new_min_free_kbytes > user_min_free_kbytes) {
+		min_free_kbytes = new_min_free_kbytes;
+		if (min_free_kbytes < 128)
+			min_free_kbytes = 128;
+		if (min_free_kbytes > 65536)
+			min_free_kbytes = 65536;
+	} else {
+		pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
+				new_min_free_kbytes, user_min_free_kbytes);
+	}
+	setup_per_zone_wmarks();
+	refresh_zone_stat_thresholds();
+	setup_per_zone_lowmem_reserve();
+	setup_per_zone_inactive_ratio();
+	return 0;
+}
+core_initcall(init_per_zone_wmark_min)
+
+/*
+ * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
+ *	that we can call two helper functions whenever min_free_kbytes
+ *	changes.
+ */
+int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
+	void __user *buffer, size_t *length, loff_t *ppos)
+{
+	int rc;
+
+	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+	if (rc)
+		return rc;
+
+	if (write) {
+		user_min_free_kbytes = min_free_kbytes;
+		setup_per_zone_wmarks();
+	}
+	return 0;
+}
+
+#ifdef CONFIG_NUMA
+int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *table, int write,
+	void __user *buffer, size_t *length, loff_t *ppos)
+{
+	struct zone *zone;
+	int rc;
+
+	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+	if (rc)
+		return rc;
+
+	for_each_zone(zone)
+		zone->min_unmapped_pages = (zone->managed_pages *
+				sysctl_min_unmapped_ratio) / 100;
+	return 0;
+}
+
+int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
+	void __user *buffer, size_t *length, loff_t *ppos)
+{
+	struct zone *zone;
+	int rc;
+
+	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+	if (rc)
+		return rc;
+
+	for_each_zone(zone)
+		zone->min_slab_pages = (zone->managed_pages *
+				sysctl_min_slab_ratio) / 100;
+	return 0;
+}
+#endif
+
+/*
+ * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
+ *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
+ *	whenever sysctl_lowmem_reserve_ratio changes.
+ *
+ * The reserve ratio obviously has absolutely no relation with the
+ * minimum watermarks. The lowmem reserve ratio can only make sense
+ * if in function of the boot time zone sizes.
+ */
+int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table, int write,
+	void __user *buffer, size_t *length, loff_t *ppos)
+{
+	proc_dointvec_minmax(table, write, buffer, length, ppos);
+	setup_per_zone_lowmem_reserve();
+	return 0;
+}
+
+/*
+ * percpu_pagelist_fraction - changes the pcp->high for each zone on each
+ * cpu.  It is the fraction of total pages in each zone that a hot per cpu
+ * pagelist can have before it gets flushed back to buddy allocator.
+ */
+int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *table, int write,
+	void __user *buffer, size_t *length, loff_t *ppos)
+{
+	struct zone *zone;
+	int old_percpu_pagelist_fraction;
+	int ret;
+
+	mutex_lock(&pcp_batch_high_lock);
+	old_percpu_pagelist_fraction = percpu_pagelist_fraction;
+
+	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+	if (!write || ret < 0)
+		goto out;
+
+	/* Sanity checking to avoid pcp imbalance */
+	if (percpu_pagelist_fraction &&
+	    percpu_pagelist_fraction < MIN_PERCPU_PAGELIST_FRACTION) {
+		percpu_pagelist_fraction = old_percpu_pagelist_fraction;
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* No change? */
+	if (percpu_pagelist_fraction == old_percpu_pagelist_fraction)
+		goto out;
+
+	for_each_populated_zone(zone) {
+		unsigned int cpu;
+
+		for_each_possible_cpu(cpu)
+			pageset_set_high_and_batch(zone,
+					per_cpu_ptr(zone->pageset, cpu));
+	}
+out:
+	mutex_unlock(&pcp_batch_high_lock);
+	return ret;
+}
+
+#ifdef CONFIG_NUMA
+int hashdist = HASHDIST_DEFAULT;
+
+static int __init set_hashdist(char *str)
+{
+	if (!str)
+		return 0;
+	hashdist = simple_strtoul(str, &str, 0);
+	return 1;
+}
+__setup("hashdist=", set_hashdist);
+#endif
+
+/*
+ * allocate a large system hash table from bootmem
+ * - it is assumed that the hash table must contain an exact power-of-2
+ *   quantity of entries
+ * - limit is the number of hash buckets, not the total allocation size
+ */
+void *__init alloc_large_system_hash(const char *tablename,
+				     unsigned long bucketsize,
+				     unsigned long numentries,
+				     int scale,
+				     int flags,
+				     unsigned int *_hash_shift,
+				     unsigned int *_hash_mask,
+				     unsigned long low_limit,
+				     unsigned long high_limit)
+{
+	unsigned long long max = high_limit;
+	unsigned long log2qty, size;
+	void *table = NULL;
+
+	/* allow the kernel cmdline to have a say */
+	if (!numentries) {
+		/* round applicable memory size up to nearest megabyte */
+		numentries = nr_kernel_pages;
+
+		/* It isn't necessary when PAGE_SIZE >= 1MB */
+		if (PAGE_SHIFT < 20)
+			numentries = round_up(numentries, (1<<20)/PAGE_SIZE);
+
+		/* limit to 1 bucket per 2^scale bytes of low memory */
+		if (scale > PAGE_SHIFT)
+			numentries >>= (scale - PAGE_SHIFT);
+		else
+			numentries <<= (PAGE_SHIFT - scale);
+
+		/* Make sure we've got at least a 0-order allocation.. */
+		if (unlikely(flags & HASH_SMALL)) {
+			/* Makes no sense without HASH_EARLY */
+			WARN_ON(!(flags & HASH_EARLY));
+			if (!(numentries >> *_hash_shift)) {
+				numentries = 1UL << *_hash_shift;
+				BUG_ON(!numentries);
+			}
+		} else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
+			numentries = PAGE_SIZE / bucketsize;
+	}
+	numentries = roundup_pow_of_two(numentries);
+
+	/* limit allocation size to 1/16 total memory by default */
+	if (max == 0) {
+		max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
+		do_div(max, bucketsize);
+	}
+	max = min(max, 0x80000000ULL);
+
+	if (numentries < low_limit)
+		numentries = low_limit;
+	if (numentries > max)
+		numentries = max;
+
+	log2qty = ilog2(numentries);
+
+	do {
+		size = bucketsize << log2qty;
+		if (flags & HASH_EARLY)
+			table = memblock_virt_alloc_nopanic(size, 0);
+		else if (hashdist)
+			table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
+		else {
+			/*
+			 * If bucketsize is not a power-of-two, we may free
+			 * some pages at the end of hash table which
+			 * alloc_pages_exact() automatically does
+			 */
+			if (get_order(size) < MAX_ORDER) {
+				table = alloc_pages_exact(size, GFP_ATOMIC);
+				kmemleak_alloc(table, size, 1, GFP_ATOMIC);
+			}
+		}
+	} while (!table && size > PAGE_SIZE && --log2qty);
+
+	if (!table)
+		panic("Failed to allocate %s hash table\n", tablename);
+
+	printk(KERN_INFO "%s hash table entries: %ld (order: %d, %lu bytes)\n",
+	       tablename,
+	       (1UL << log2qty),
+	       ilog2(size) - PAGE_SHIFT,
+	       size);
+
+	if (_hash_shift)
+		*_hash_shift = log2qty;
+	if (_hash_mask)
+		*_hash_mask = (1 << log2qty) - 1;
+
+	return table;
+}
+
+/* Return a pointer to the bitmap storing bits affecting a block of pages */
+static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
+							unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+	return __pfn_to_section(pfn)->pageblock_flags;
+#else
+	return zone->pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+	pfn &= (PAGES_PER_SECTION-1);
+	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+#else
+	pfn = pfn - round_down(zone->zone_start_pfn, pageblock_nr_pages);
+	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+/**
+ * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @pfn: The target page frame number
+ * @end_bitidx: The last bit of interest to retrieve
+ * @mask: mask of bits that the caller is interested in
+ *
+ * Return: pageblock_bits flags
+ */
+unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
+					unsigned long end_bitidx,
+					unsigned long mask)
+{
+	struct zone *zone;
+	unsigned long *bitmap;
+	unsigned long bitidx, word_bitidx;
+	unsigned long word;
+
+	zone = page_zone(page);
+	bitmap = get_pageblock_bitmap(zone, pfn);
+	bitidx = pfn_to_bitidx(zone, pfn);
+	word_bitidx = bitidx / BITS_PER_LONG;
+	bitidx &= (BITS_PER_LONG-1);
+
+	word = bitmap[word_bitidx];
+	bitidx += end_bitidx;
+	return (word >> (BITS_PER_LONG - bitidx - 1)) & mask;
+}
+
+/**
+ * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @flags: The flags to set
+ * @pfn: The target page frame number
+ * @end_bitidx: The last bit of interest
+ * @mask: mask of bits that the caller is interested in
+ */
+void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
+					unsigned long pfn,
+					unsigned long end_bitidx,
+					unsigned long mask)
+{
+	struct zone *zone;
+	unsigned long *bitmap;
+	unsigned long bitidx, word_bitidx;
+	unsigned long old_word, word;
+
+	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
+
+	zone = page_zone(page);
+	bitmap = get_pageblock_bitmap(zone, pfn);
+	bitidx = pfn_to_bitidx(zone, pfn);
+	word_bitidx = bitidx / BITS_PER_LONG;
+	bitidx &= (BITS_PER_LONG-1);
+
+	VM_BUG_ON_PAGE(!zone_spans_pfn(zone, pfn), page);
+
+	bitidx += end_bitidx;
+	mask <<= (BITS_PER_LONG - bitidx - 1);
+	flags <<= (BITS_PER_LONG - bitidx - 1);
+
+	word = READ_ONCE(bitmap[word_bitidx]);
+	for (;;) {
+		old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
+		if (word == old_word)
+			break;
+		word = old_word;
+	}
+}
+
+/*
+ * This function checks whether pageblock includes unmovable pages or not.
+ * If @count is not zero, it is okay to include less @count unmovable pages
+ *
+ * PageLRU check without isolation or lru_lock could race so that
+ * MIGRATE_MOVABLE block might include unmovable pages. It means you can't
+ * expect this function should be exact.
+ */
+bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
+			 bool skip_hwpoisoned_pages)
+{
+	unsigned long pfn, iter, found;
+	int mt;
+
+	/*
+	 * For avoiding noise data, lru_add_drain_all() should be called
+	 * If ZONE_MOVABLE, the zone never contains unmovable pages
+	 */
+	if (zone_idx(zone) == ZONE_MOVABLE)
+		return false;
+	mt = get_pageblock_migratetype(page);
+	if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
+		return false;
+
+	pfn = page_to_pfn(page);
+	for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
+		unsigned long check = pfn + iter;
+
+		if (!pfn_valid_within(check))
+			continue;
+
+		page = pfn_to_page(check);
+
+		/*
+		 * Hugepages are not in LRU lists, but they're movable.
+		 * We need not scan over tail pages bacause we don't
+		 * handle each tail page individually in migration.
+		 */
+		if (PageHuge(page)) {
+			iter = round_up(iter + 1, 1<<compound_order(page)) - 1;
+			continue;
+		}
+
+		/*
+		 * We can't use page_count without pin a page
+		 * because another CPU can free compound page.
+		 * This check already skips compound tails of THP
+		 * because their page->_count is zero at all time.
+		 */
+		if (!atomic_read(&page->_count)) {
+			if (PageBuddy(page))
+				iter += (1 << page_order(page)) - 1;
+			continue;
+		}
+
+		/*
+		 * The HWPoisoned page may be not in buddy system, and
+		 * page_count() is not 0.
+		 */
+		if (skip_hwpoisoned_pages && PageHWPoison(page))
+			continue;
+
+		if (!PageLRU(page))
+			found++;
+		/*
+		 * If there are RECLAIMABLE pages, we need to check
+		 * it.  But now, memory offline itself doesn't call
+		 * shrink_node_slabs() and it still to be fixed.
+		 */
+		/*
+		 * If the page is not RAM, page_count()should be 0.
+		 * we don't need more check. This is an _used_ not-movable page.
+		 *
+		 * The problematic thing here is PG_reserved pages. PG_reserved
+		 * is set to both of a memory hole page and a _used_ kernel
+		 * page at boot.
+		 */
+		if (found > count)
+			return true;
+	}
+	return false;
+}
+
+bool is_pageblock_removable_nolock(struct page *page)
+{
+	struct zone *zone;
+	unsigned long pfn;
+
+	/*
+	 * We have to be careful here because we are iterating over memory
+	 * sections which are not zone aware so we might end up outside of
+	 * the zone but still within the section.
+	 * We have to take care about the node as well. If the node is offline
+	 * its NODE_DATA will be NULL - see page_zone.
+	 */
+	if (!node_online(page_to_nid(page)))
+		return false;
+
+	zone = page_zone(page);
+	pfn = page_to_pfn(page);
+	if (!zone_spans_pfn(zone, pfn))
+		return false;
+
+	return !has_unmovable_pages(zone, page, 0, true);
+}
+
+#ifdef CONFIG_CMA
+
+static unsigned long pfn_max_align_down(unsigned long pfn)
+{
+	return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES,
+			     pageblock_nr_pages) - 1);
+}
+
+static unsigned long pfn_max_align_up(unsigned long pfn)
+{
+	return ALIGN(pfn, max_t(unsigned long, MAX_ORDER_NR_PAGES,
+				pageblock_nr_pages));
+}
+
+/* [start, end) must belong to a single zone. */
+static int __alloc_contig_migrate_range(struct compact_control *cc,
+					unsigned long start, unsigned long end)
+{
+	/* This function is based on compact_zone() from compaction.c. */
+	unsigned long nr_reclaimed;
+	unsigned long pfn = start;
+	unsigned int tries = 0;
+	int ret = 0;
+
+	migrate_prep();
+
+	while (pfn < end || !list_empty(&cc->migratepages)) {
+		if (fatal_signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+
+		if (list_empty(&cc->migratepages)) {
+			cc->nr_migratepages = 0;
+			pfn = isolate_migratepages_range(cc, pfn, end);
+			if (!pfn) {
+				ret = -EINTR;
+				break;
+			}
+			tries = 0;
+		} else if (++tries == 5) {
+			ret = ret < 0 ? ret : -EBUSY;
+			break;
+		}
+
+		nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
+							&cc->migratepages);
+		cc->nr_migratepages -= nr_reclaimed;
+
+		ret = migrate_pages(&cc->migratepages, alloc_migrate_target,
+				    NULL, 0, cc->mode, MR_CMA);
+	}
+	if (ret < 0) {
+		putback_movable_pages(&cc->migratepages);
+		return ret;
+	}
+	return 0;
+}
+
+/**
+ * alloc_contig_range() -- tries to allocate given range of pages
+ * @start:	start PFN to allocate
+ * @end:	one-past-the-last PFN to allocate
+ * @migratetype:	migratetype of the underlaying pageblocks (either
+ *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
+ *			in range must have the same migratetype and it must
+ *			be either of the two.
+ *
+ * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
+ * aligned, however it's the caller's responsibility to guarantee that
+ * we are the only thread that changes migrate type of pageblocks the
+ * pages fall in.
+ *
+ * The PFN range must belong to a single zone.
+ *
+ * Returns zero on success or negative error code.  On success all
+ * pages which PFN is in [start, end) are allocated for the caller and
+ * need to be freed with free_contig_range().
+ */
+int alloc_contig_range(unsigned long start, unsigned long end,
+		       unsigned migratetype)
+{
+	unsigned long outer_start, outer_end;
+	unsigned int order;
+	int ret = 0;
+
+	struct compact_control cc = {
+		.nr_migratepages = 0,
+		.order = -1,
+		.zone = page_zone(pfn_to_page(start)),
+		.mode = MIGRATE_SYNC,
+		.ignore_skip_hint = true,
+	};
+	INIT_LIST_HEAD(&cc.migratepages);
+
+	/*
+	 * What we do here is we mark all pageblocks in range as
+	 * MIGRATE_ISOLATE.  Because pageblock and max order pages may
+	 * have different sizes, and due to the way page allocator
+	 * work, we align the range to biggest of the two pages so
+	 * that page allocator won't try to merge buddies from
+	 * different pageblocks and change MIGRATE_ISOLATE to some
+	 * other migration type.
+	 *
+	 * Once the pageblocks are marked as MIGRATE_ISOLATE, we
+	 * migrate the pages from an unaligned range (ie. pages that
+	 * we are interested in).  This will put all the pages in
+	 * range back to page allocator as MIGRATE_ISOLATE.
+	 *
+	 * When this is done, we take the pages in range from page
+	 * allocator removing them from the buddy system.  This way
+	 * page allocator will never consider using them.
+	 *
+	 * This lets us mark the pageblocks back as
+	 * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
+	 * aligned range but not in the unaligned, original range are
+	 * put back to page allocator so that buddy can use them.
+	 */
+
+	ret = start_isolate_page_range(pfn_max_align_down(start),
+				       pfn_max_align_up(end), migratetype,
+				       false);
+	if (ret)
+		return ret;
+
+	ret = __alloc_contig_migrate_range(&cc, start, end);
+	if (ret)
+		goto done;
+
+	/*
+	 * Pages from [start, end) are within a MAX_ORDER_NR_PAGES
+	 * aligned blocks that are marked as MIGRATE_ISOLATE.  What's
+	 * more, all pages in [start, end) are free in page allocator.
+	 * What we are going to do is to allocate all pages from
+	 * [start, end) (that is remove them from page allocator).
+	 *
+	 * The only problem is that pages at the beginning and at the
+	 * end of interesting range may be not aligned with pages that
+	 * page allocator holds, ie. they can be part of higher order
+	 * pages.  Because of this, we reserve the bigger range and
+	 * once this is done free the pages we are not interested in.
+	 *
+	 * We don't have to hold zone->lock here because the pages are
+	 * isolated thus they won't get removed from buddy.
+	 */
+
+	lru_add_drain_all();
+	drain_all_pages(cc.zone);
+
+	order = 0;
+	outer_start = start;
+	while (!PageBuddy(pfn_to_page(outer_start))) {
+		if (++order >= MAX_ORDER) {
+			ret = -EBUSY;
+			goto done;
+		}
+		outer_start &= ~0UL << order;
+	}
+
+	/* Make sure the range is really isolated. */
+	if (test_pages_isolated(outer_start, end, false)) {
+		pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n",
+			__func__, outer_start, end);
+		ret = -EBUSY;
+		goto done;
+	}
+
+	/* Grab isolated pages from freelists. */
+	outer_end = isolate_freepages_range(&cc, outer_start, end);
+	if (!outer_end) {
+		ret = -EBUSY;
+		goto done;
+	}
+
+	/* Free head and tail (if any) */
+	if (start != outer_start)
+		free_contig_range(outer_start, start - outer_start);
+	if (end != outer_end)
+		free_contig_range(end, outer_end - end);
+
+done:
+	undo_isolate_page_range(pfn_max_align_down(start),
+				pfn_max_align_up(end), migratetype);
+	return ret;
+}
+
+void free_contig_range(unsigned long pfn, unsigned nr_pages)
+{
+	unsigned int count = 0;
+
+	for (; nr_pages--; pfn++) {
+		struct page *page = pfn_to_page(pfn);
+
+		count += page_count(page) != 1;
+		__free_page(page);
+	}
+	WARN(count != 0, "%d pages are still in use!\n", count);
+}
+#endif
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+/*
+ * The zone indicated has a new number of managed_pages; batch sizes and percpu
+ * page high values need to be recalulated.
+ */
+void __meminit zone_pcp_update(struct zone *zone)
+{
+	unsigned cpu;
+	mutex_lock(&pcp_batch_high_lock);
+	for_each_possible_cpu(cpu)
+		pageset_set_high_and_batch(zone,
+				per_cpu_ptr(zone->pageset, cpu));
+	mutex_unlock(&pcp_batch_high_lock);
+}
+#endif
+
+void zone_pcp_reset(struct zone *zone)
+{
+	unsigned long flags;
+	int cpu;
+	struct per_cpu_pageset *pset;
+
+	/* avoid races with drain_pages()  */
+	local_irq_save(flags);
+	if (zone->pageset != &boot_pageset) {
+		for_each_online_cpu(cpu) {
+			pset = per_cpu_ptr(zone->pageset, cpu);
+			drain_zonestat(zone, pset);
+		}
+		free_percpu(zone->pageset);
+		zone->pageset = &boot_pageset;
+	}
+	local_irq_restore(flags);
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * All pages in the range must be isolated before calling this.
+ */
+void
+__offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
+{
+	struct page *page;
+	struct zone *zone;
+	unsigned int order, i;
+	unsigned long pfn;
+	unsigned long flags;
+	/* find the first valid pfn */
+	for (pfn = start_pfn; pfn < end_pfn; pfn++)
+		if (pfn_valid(pfn))
+			break;
+	if (pfn == end_pfn)
+		return;
+	zone = page_zone(pfn_to_page(pfn));
+	spin_lock_irqsave(&zone->lock, flags);
+	pfn = start_pfn;
+	while (pfn < end_pfn) {
+		if (!pfn_valid(pfn)) {
+			pfn++;
+			continue;
+		}
+		page = pfn_to_page(pfn);
+		/*
+		 * The HWPoisoned page may be not in buddy system, and
+		 * page_count() is not 0.
+		 */
+		if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
+			pfn++;
+			SetPageReserved(page);
+			continue;
+		}
+
+		BUG_ON(page_count(page));
+		BUG_ON(!PageBuddy(page));
+		order = page_order(page);
+#ifdef CONFIG_DEBUG_VM
+		printk(KERN_INFO "remove from free list %lx %d %lx\n",
+		       pfn, 1 << order, end_pfn);
+#endif
+		list_del(&page->lru);
+		rmv_page_order(page);
+		zone->free_area[order].nr_free--;
+		for (i = 0; i < (1 << order); i++)
+			SetPageReserved((page+i));
+		pfn += (1 << order);
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+}
+#endif
+
+#ifdef CONFIG_MEMORY_FAILURE
+bool is_free_buddy_page(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long flags;
+	unsigned int order;
+
+	spin_lock_irqsave(&zone->lock, flags);
+	for (order = 0; order < MAX_ORDER; order++) {
+		struct page *page_head = page - (pfn & ((1 << order) - 1));
+
+		if (PageBuddy(page_head) && page_order(page_head) >= order)
+			break;
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+
+	return order < MAX_ORDER;
+}
+#endif
diff --git a/mm/page_counter.c b/mm/page_counter.c
new file mode 100644
index 0000000..7c6a63d
--- /dev/null
+++ b/mm/page_counter.c
@@ -0,0 +1,193 @@
+/*
+ * Lockless hierarchical page accounting & limiting
+ *
+ * Copyright (C) 2014 Red Hat, Inc., Johannes Weiner
+ */
+
+#include <linux/page_counter.h>
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/sched.h>
+#include <linux/bug.h>
+#include <asm/page.h>
+
+/**
+ * page_counter_cancel - take pages out of the local counter
+ * @counter: counter
+ * @nr_pages: number of pages to cancel
+ */
+void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages)
+{
+	long new;
+
+	new = atomic_long_sub_return(nr_pages, &counter->count);
+	/* More uncharges than charges? */
+	WARN_ON_ONCE(new < 0);
+}
+
+/**
+ * page_counter_charge - hierarchically charge pages
+ * @counter: counter
+ * @nr_pages: number of pages to charge
+ *
+ * NOTE: This does not consider any configured counter limits.
+ */
+void page_counter_charge(struct page_counter *counter, unsigned long nr_pages)
+{
+	struct page_counter *c;
+
+	for (c = counter; c; c = c->parent) {
+		long new;
+
+		new = atomic_long_add_return(nr_pages, &c->count);
+		/*
+		 * This is indeed racy, but we can live with some
+		 * inaccuracy in the watermark.
+		 */
+		if (new > c->watermark)
+			c->watermark = new;
+	}
+}
+
+/**
+ * page_counter_try_charge - try to hierarchically charge pages
+ * @counter: counter
+ * @nr_pages: number of pages to charge
+ * @fail: points first counter to hit its limit, if any
+ *
+ * Returns %true on success, or %false and @fail if the counter or one
+ * of its ancestors has hit its configured limit.
+ */
+bool page_counter_try_charge(struct page_counter *counter,
+			     unsigned long nr_pages,
+			     struct page_counter **fail)
+{
+	struct page_counter *c;
+
+	for (c = counter; c; c = c->parent) {
+		long new;
+		/*
+		 * Charge speculatively to avoid an expensive CAS.  If
+		 * a bigger charge fails, it might falsely lock out a
+		 * racing smaller charge and send it into reclaim
+		 * early, but the error is limited to the difference
+		 * between the two sizes, which is less than 2M/4M in
+		 * case of a THP locking out a regular page charge.
+		 *
+		 * The atomic_long_add_return() implies a full memory
+		 * barrier between incrementing the count and reading
+		 * the limit.  When racing with page_counter_limit(),
+		 * we either see the new limit or the setter sees the
+		 * counter has changed and retries.
+		 */
+		new = atomic_long_add_return(nr_pages, &c->count);
+		if (new > c->limit) {
+			atomic_long_sub(nr_pages, &c->count);
+			/*
+			 * This is racy, but we can live with some
+			 * inaccuracy in the failcnt.
+			 */
+			c->failcnt++;
+			*fail = c;
+			goto failed;
+		}
+		/*
+		 * Just like with failcnt, we can live with some
+		 * inaccuracy in the watermark.
+		 */
+		if (new > c->watermark)
+			c->watermark = new;
+	}
+	return true;
+
+failed:
+	for (c = counter; c != *fail; c = c->parent)
+		page_counter_cancel(c, nr_pages);
+
+	return false;
+}
+
+/**
+ * page_counter_uncharge - hierarchically uncharge pages
+ * @counter: counter
+ * @nr_pages: number of pages to uncharge
+ */
+void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages)
+{
+	struct page_counter *c;
+
+	for (c = counter; c; c = c->parent)
+		page_counter_cancel(c, nr_pages);
+}
+
+/**
+ * page_counter_limit - limit the number of pages allowed
+ * @counter: counter
+ * @limit: limit to set
+ *
+ * Returns 0 on success, -EBUSY if the current number of pages on the
+ * counter already exceeds the specified limit.
+ *
+ * The caller must serialize invocations on the same counter.
+ */
+int page_counter_limit(struct page_counter *counter, unsigned long limit)
+{
+	for (;;) {
+		unsigned long old;
+		long count;
+
+		/*
+		 * Update the limit while making sure that it's not
+		 * below the concurrently-changing counter value.
+		 *
+		 * The xchg implies two full memory barriers before
+		 * and after, so the read-swap-read is ordered and
+		 * ensures coherency with page_counter_try_charge():
+		 * that function modifies the count before checking
+		 * the limit, so if it sees the old limit, we see the
+		 * modified counter and retry.
+		 */
+		count = atomic_long_read(&counter->count);
+
+		if (count > limit)
+			return -EBUSY;
+
+		old = xchg(&counter->limit, limit);
+
+		if (atomic_long_read(&counter->count) <= count)
+			return 0;
+
+		counter->limit = old;
+		cond_resched();
+	}
+}
+
+/**
+ * page_counter_memparse - memparse() for page counter limits
+ * @buf: string to parse
+ * @max: string meaning maximum possible value
+ * @nr_pages: returns the result in number of pages
+ *
+ * Returns -EINVAL, or 0 and @nr_pages on success.  @nr_pages will be
+ * limited to %PAGE_COUNTER_MAX.
+ */
+int page_counter_memparse(const char *buf, const char *max,
+			  unsigned long *nr_pages)
+{
+	char *end;
+	u64 bytes;
+
+	if (!strcmp(buf, max)) {
+		*nr_pages = PAGE_COUNTER_MAX;
+		return 0;
+	}
+
+	bytes = memparse(buf, &end);
+	if (*end != '\0')
+		return -EINVAL;
+
+	*nr_pages = min(bytes / PAGE_SIZE, (u64)PAGE_COUNTER_MAX);
+
+	return 0;
+}
diff --git a/mm/page_ext.c b/mm/page_ext.c
new file mode 100644
index 0000000..292ca7b
--- /dev/null
+++ b/mm/page_ext.c
@@ -0,0 +1,407 @@
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/page_ext.h>
+#include <linux/memory.h>
+#include <linux/vmalloc.h>
+#include <linux/kmemleak.h>
+#include <linux/page_owner.h>
+#include <linux/page_idle.h>
+
+/*
+ * struct page extension
+ *
+ * This is the feature to manage memory for extended data per page.
+ *
+ * Until now, we must modify struct page itself to store extra data per page.
+ * This requires rebuilding the kernel and it is really time consuming process.
+ * And, sometimes, rebuild is impossible due to third party module dependency.
+ * At last, enlarging struct page could cause un-wanted system behaviour change.
+ *
+ * This feature is intended to overcome above mentioned problems. This feature
+ * allocates memory for extended data per page in certain place rather than
+ * the struct page itself. This memory can be accessed by the accessor
+ * functions provided by this code. During the boot process, it checks whether
+ * allocation of huge chunk of memory is needed or not. If not, it avoids
+ * allocating memory at all. With this advantage, we can include this feature
+ * into the kernel in default and can avoid rebuild and solve related problems.
+ *
+ * To help these things to work well, there are two callbacks for clients. One
+ * is the need callback which is mandatory if user wants to avoid useless
+ * memory allocation at boot-time. The other is optional, init callback, which
+ * is used to do proper initialization after memory is allocated.
+ *
+ * The need callback is used to decide whether extended memory allocation is
+ * needed or not. Sometimes users want to deactivate some features in this
+ * boot and extra memory would be unneccessary. In this case, to avoid
+ * allocating huge chunk of memory, each clients represent their need of
+ * extra memory through the need callback. If one of the need callbacks
+ * returns true, it means that someone needs extra memory so that
+ * page extension core should allocates memory for page extension. If
+ * none of need callbacks return true, memory isn't needed at all in this boot
+ * and page extension core can skip to allocate memory. As result,
+ * none of memory is wasted.
+ *
+ * The init callback is used to do proper initialization after page extension
+ * is completely initialized. In sparse memory system, extra memory is
+ * allocated some time later than memmap is allocated. In other words, lifetime
+ * of memory for page extension isn't same with memmap for struct page.
+ * Therefore, clients can't store extra data until page extension is
+ * initialized, even if pages are allocated and used freely. This could
+ * cause inadequate state of extra data per page, so, to prevent it, client
+ * can utilize this callback to initialize the state of it correctly.
+ */
+
+static struct page_ext_operations *page_ext_ops[] = {
+	&debug_guardpage_ops,
+#ifdef CONFIG_PAGE_POISONING
+	&page_poisoning_ops,
+#endif
+#ifdef CONFIG_PAGE_OWNER
+	&page_owner_ops,
+#endif
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+	&page_idle_ops,
+#endif
+};
+
+static unsigned long total_usage;
+
+static bool __init invoke_need_callbacks(void)
+{
+	int i;
+	int entries = ARRAY_SIZE(page_ext_ops);
+
+	for (i = 0; i < entries; i++) {
+		if (page_ext_ops[i]->need && page_ext_ops[i]->need())
+			return true;
+	}
+
+	return false;
+}
+
+static void __init invoke_init_callbacks(void)
+{
+	int i;
+	int entries = ARRAY_SIZE(page_ext_ops);
+
+	for (i = 0; i < entries; i++) {
+		if (page_ext_ops[i]->init)
+			page_ext_ops[i]->init();
+	}
+}
+
+#if !defined(CONFIG_SPARSEMEM)
+
+
+void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
+{
+	pgdat->node_page_ext = NULL;
+}
+
+struct page_ext *lookup_page_ext(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long offset;
+	struct page_ext *base;
+
+	base = NODE_DATA(page_to_nid(page))->node_page_ext;
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The sanity checks the page allocator does upon freeing a
+	 * page can reach here before the page_ext arrays are
+	 * allocated when feeding a range of pages to the allocator
+	 * for the first time during bootup or memory hotplug.
+	 */
+	if (unlikely(!base))
+		return NULL;
+#endif
+	offset = pfn - round_down(node_start_pfn(page_to_nid(page)),
+					MAX_ORDER_NR_PAGES);
+	return base + offset;
+}
+
+static int __init alloc_node_page_ext(int nid)
+{
+	struct page_ext *base;
+	unsigned long table_size;
+	unsigned long nr_pages;
+
+	nr_pages = NODE_DATA(nid)->node_spanned_pages;
+	if (!nr_pages)
+		return 0;
+
+	/*
+	 * Need extra space if node range is not aligned with
+	 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
+	 * checks buddy's status, range could be out of exact node range.
+	 */
+	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
+		!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
+		nr_pages += MAX_ORDER_NR_PAGES;
+
+	table_size = sizeof(struct page_ext) * nr_pages;
+
+	base = memblock_virt_alloc_try_nid_nopanic(
+			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
+			BOOTMEM_ALLOC_ACCESSIBLE, nid);
+	if (!base)
+		return -ENOMEM;
+	NODE_DATA(nid)->node_page_ext = base;
+	total_usage += table_size;
+	return 0;
+}
+
+void __init page_ext_init_flatmem(void)
+{
+
+	int nid, fail;
+
+	if (!invoke_need_callbacks())
+		return;
+
+	for_each_online_node(nid)  {
+		fail = alloc_node_page_ext(nid);
+		if (fail)
+			goto fail;
+	}
+	pr_info("allocated %ld bytes of page_ext\n", total_usage);
+	invoke_init_callbacks();
+	return;
+
+fail:
+	pr_crit("allocation of page_ext failed.\n");
+	panic("Out of memory");
+}
+
+#else /* CONFIG_FLAT_NODE_MEM_MAP */
+
+struct page_ext *lookup_page_ext(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	struct mem_section *section = __pfn_to_section(pfn);
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The sanity checks the page allocator does upon freeing a
+	 * page can reach here before the page_ext arrays are
+	 * allocated when feeding a range of pages to the allocator
+	 * for the first time during bootup or memory hotplug.
+	 */
+	if (!section->page_ext)
+		return NULL;
+#endif
+	return section->page_ext + pfn;
+}
+
+static void *__meminit alloc_page_ext(size_t size, int nid)
+{
+	gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
+	void *addr = NULL;
+
+	addr = alloc_pages_exact_nid(nid, size, flags);
+	if (addr) {
+		kmemleak_alloc(addr, size, 1, flags);
+		return addr;
+	}
+
+	if (node_state(nid, N_HIGH_MEMORY))
+		addr = vzalloc_node(size, nid);
+	else
+		addr = vzalloc(size);
+
+	return addr;
+}
+
+static int __meminit init_section_page_ext(unsigned long pfn, int nid)
+{
+	struct mem_section *section;
+	struct page_ext *base;
+	unsigned long table_size;
+
+	section = __pfn_to_section(pfn);
+
+	if (section->page_ext)
+		return 0;
+
+	table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
+	base = alloc_page_ext(table_size, nid);
+
+	/*
+	 * The value stored in section->page_ext is (base - pfn)
+	 * and it does not point to the memory block allocated above,
+	 * causing kmemleak false positives.
+	 */
+	kmemleak_not_leak(base);
+
+	if (!base) {
+		pr_err("page ext allocation failure\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * The passed "pfn" may not be aligned to SECTION.  For the calculation
+	 * we need to apply a mask.
+	 */
+	pfn &= PAGE_SECTION_MASK;
+	section->page_ext = base - pfn;
+	total_usage += table_size;
+	return 0;
+}
+#ifdef CONFIG_MEMORY_HOTPLUG
+static void free_page_ext(void *addr)
+{
+	if (is_vmalloc_addr(addr)) {
+		vfree(addr);
+	} else {
+		struct page *page = virt_to_page(addr);
+		size_t table_size;
+
+		table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
+
+		BUG_ON(PageReserved(page));
+		free_pages_exact(addr, table_size);
+	}
+}
+
+static void __free_page_ext(unsigned long pfn)
+{
+	struct mem_section *ms;
+	struct page_ext *base;
+
+	ms = __pfn_to_section(pfn);
+	if (!ms || !ms->page_ext)
+		return;
+	base = ms->page_ext + pfn;
+	free_page_ext(base);
+	ms->page_ext = NULL;
+}
+
+static int __meminit online_page_ext(unsigned long start_pfn,
+				unsigned long nr_pages,
+				int nid)
+{
+	unsigned long start, end, pfn;
+	int fail = 0;
+
+	start = SECTION_ALIGN_DOWN(start_pfn);
+	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
+
+	if (nid == -1) {
+		/*
+		 * In this case, "nid" already exists and contains valid memory.
+		 * "start_pfn" passed to us is a pfn which is an arg for
+		 * online__pages(), and start_pfn should exist.
+		 */
+		nid = pfn_to_nid(start_pfn);
+		VM_BUG_ON(!node_state(nid, N_ONLINE));
+	}
+
+	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_ext(pfn, nid);
+	}
+	if (!fail)
+		return 0;
+
+	/* rollback */
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+		__free_page_ext(pfn);
+
+	return -ENOMEM;
+}
+
+static int __meminit offline_page_ext(unsigned long start_pfn,
+				unsigned long nr_pages, int nid)
+{
+	unsigned long start, end, pfn;
+
+	start = SECTION_ALIGN_DOWN(start_pfn);
+	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
+
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+		__free_page_ext(pfn);
+	return 0;
+
+}
+
+static int __meminit page_ext_callback(struct notifier_block *self,
+			       unsigned long action, void *arg)
+{
+	struct memory_notify *mn = arg;
+	int ret = 0;
+
+	switch (action) {
+	case MEM_GOING_ONLINE:
+		ret = online_page_ext(mn->start_pfn,
+				   mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_OFFLINE:
+		offline_page_ext(mn->start_pfn,
+				mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_CANCEL_ONLINE:
+		offline_page_ext(mn->start_pfn,
+				mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_GOING_OFFLINE:
+		break;
+	case MEM_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+
+	return notifier_from_errno(ret);
+}
+
+#endif
+
+void __init page_ext_init(void)
+{
+	unsigned long pfn;
+	int nid;
+
+	if (!invoke_need_callbacks())
+		return;
+
+	for_each_node_state(nid, N_MEMORY) {
+		unsigned long start_pfn, end_pfn;
+
+		start_pfn = node_start_pfn(nid);
+		end_pfn = node_end_pfn(nid);
+		/*
+		 * start_pfn and end_pfn may not be aligned to SECTION and the
+		 * page->flags of out of node pages are not initialized.  So we
+		 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
+		 */
+		for (pfn = start_pfn; pfn < end_pfn;
+			pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
+
+			if (!pfn_valid(pfn))
+				continue;
+			/*
+			 * Nodes's pfns can be overlapping.
+			 * We know some arch can have a nodes layout such as
+			 * -------------pfn-------------->
+			 * N0 | N1 | N2 | N0 | N1 | N2|....
+			 */
+			if (pfn_to_nid(pfn) != nid)
+				continue;
+			if (init_section_page_ext(pfn, nid))
+				goto oom;
+		}
+	}
+	hotplug_memory_notifier(page_ext_callback, 0);
+	pr_info("allocated %ld bytes of page_ext\n", total_usage);
+	invoke_init_callbacks();
+	return;
+
+oom:
+	panic("Out of memory");
+}
+
+void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
+{
+}
+
+#endif
diff --git a/mm/page_idle.c b/mm/page_idle.c
new file mode 100644
index 0000000..d5dd790
--- /dev/null
+++ b/mm/page_idle.c
@@ -0,0 +1,232 @@
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/fs.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/pagemap.h>
+#include <linux/rmap.h>
+#include <linux/mmu_notifier.h>
+#include <linux/page_ext.h>
+#include <linux/page_idle.h>
+
+#define BITMAP_CHUNK_SIZE	sizeof(u64)
+#define BITMAP_CHUNK_BITS	(BITMAP_CHUNK_SIZE * BITS_PER_BYTE)
+
+/*
+ * Idle page tracking only considers user memory pages, for other types of
+ * pages the idle flag is always unset and an attempt to set it is silently
+ * ignored.
+ *
+ * We treat a page as a user memory page if it is on an LRU list, because it is
+ * always safe to pass such a page to rmap_walk(), which is essential for idle
+ * page tracking. With such an indicator of user pages we can skip isolated
+ * pages, but since there are not usually many of them, it will hardly affect
+ * the overall result.
+ *
+ * This function tries to get a user memory page by pfn as described above.
+ */
+static struct page *page_idle_get_page(unsigned long pfn)
+{
+	struct page *page;
+	struct zone *zone;
+
+	if (!pfn_valid(pfn))
+		return NULL;
+
+	page = pfn_to_page(pfn);
+	if (!page || !PageLRU(page) ||
+	    !get_page_unless_zero(page))
+		return NULL;
+
+	zone = page_zone(page);
+	spin_lock_irq(&zone->lru_lock);
+	if (unlikely(!PageLRU(page))) {
+		put_page(page);
+		page = NULL;
+	}
+	spin_unlock_irq(&zone->lru_lock);
+	return page;
+}
+
+static int page_idle_clear_pte_refs_one(struct page *page,
+					struct vm_area_struct *vma,
+					unsigned long addr, void *arg)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	spinlock_t *ptl;
+	pmd_t *pmd;
+	pte_t *pte;
+	bool referenced = false;
+
+	if (unlikely(PageTransHuge(page))) {
+		pmd = page_check_address_pmd(page, mm, addr,
+					     PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
+		if (pmd) {
+			referenced = pmdp_clear_young_notify(vma, addr, pmd);
+			spin_unlock(ptl);
+		}
+	} else {
+		pte = page_check_address(page, mm, addr, &ptl, 0);
+		if (pte) {
+			referenced = ptep_clear_young_notify(vma, addr, pte);
+			pte_unmap_unlock(pte, ptl);
+		}
+	}
+	if (referenced) {
+		clear_page_idle(page);
+		/*
+		 * We cleared the referenced bit in a mapping to this page. To
+		 * avoid interference with page reclaim, mark it young so that
+		 * page_referenced() will return > 0.
+		 */
+		set_page_young(page);
+	}
+	return SWAP_AGAIN;
+}
+
+static void page_idle_clear_pte_refs(struct page *page)
+{
+	/*
+	 * Since rwc.arg is unused, rwc is effectively immutable, so we
+	 * can make it static const to save some cycles and stack.
+	 */
+	static const struct rmap_walk_control rwc = {
+		.rmap_one = page_idle_clear_pte_refs_one,
+		.anon_lock = page_lock_anon_vma_read,
+	};
+	bool need_lock;
+
+	if (!page_mapped(page) ||
+	    !page_rmapping(page))
+		return;
+
+	need_lock = !PageAnon(page) || PageKsm(page);
+	if (need_lock && !trylock_page(page))
+		return;
+
+	rmap_walk(page, (struct rmap_walk_control *)&rwc);
+
+	if (need_lock)
+		unlock_page(page);
+}
+
+static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
+				     struct bin_attribute *attr, char *buf,
+				     loff_t pos, size_t count)
+{
+	u64 *out = (u64 *)buf;
+	struct page *page;
+	unsigned long pfn, end_pfn;
+	int bit;
+
+	if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE)
+		return -EINVAL;
+
+	pfn = pos * BITS_PER_BYTE;
+	if (pfn >= max_pfn)
+		return 0;
+
+	end_pfn = pfn + count * BITS_PER_BYTE;
+	if (end_pfn > max_pfn)
+		end_pfn = ALIGN(max_pfn, BITMAP_CHUNK_BITS);
+
+	for (; pfn < end_pfn; pfn++) {
+		bit = pfn % BITMAP_CHUNK_BITS;
+		if (!bit)
+			*out = 0ULL;
+		page = page_idle_get_page(pfn);
+		if (page) {
+			if (page_is_idle(page)) {
+				/*
+				 * The page might have been referenced via a
+				 * pte, in which case it is not idle. Clear
+				 * refs and recheck.
+				 */
+				page_idle_clear_pte_refs(page);
+				if (page_is_idle(page))
+					*out |= 1ULL << bit;
+			}
+			put_page(page);
+		}
+		if (bit == BITMAP_CHUNK_BITS - 1)
+			out++;
+		cond_resched();
+	}
+	return (char *)out - buf;
+}
+
+static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
+				      struct bin_attribute *attr, char *buf,
+				      loff_t pos, size_t count)
+{
+	const u64 *in = (u64 *)buf;
+	struct page *page;
+	unsigned long pfn, end_pfn;
+	int bit;
+
+	if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE)
+		return -EINVAL;
+
+	pfn = pos * BITS_PER_BYTE;
+	if (pfn >= max_pfn)
+		return -ENXIO;
+
+	end_pfn = pfn + count * BITS_PER_BYTE;
+	if (end_pfn > max_pfn)
+		end_pfn = ALIGN(max_pfn, BITMAP_CHUNK_BITS);
+
+	for (; pfn < end_pfn; pfn++) {
+		bit = pfn % BITMAP_CHUNK_BITS;
+		if ((*in >> bit) & 1) {
+			page = page_idle_get_page(pfn);
+			if (page) {
+				page_idle_clear_pte_refs(page);
+				set_page_idle(page);
+				put_page(page);
+			}
+		}
+		if (bit == BITMAP_CHUNK_BITS - 1)
+			in++;
+		cond_resched();
+	}
+	return (char *)in - buf;
+}
+
+static struct bin_attribute page_idle_bitmap_attr =
+		__BIN_ATTR(bitmap, S_IRUSR | S_IWUSR,
+			   page_idle_bitmap_read, page_idle_bitmap_write, 0);
+
+static struct bin_attribute *page_idle_bin_attrs[] = {
+	&page_idle_bitmap_attr,
+	NULL,
+};
+
+static struct attribute_group page_idle_attr_group = {
+	.bin_attrs = page_idle_bin_attrs,
+	.name = "page_idle",
+};
+
+#ifndef CONFIG_64BIT
+static bool need_page_idle(void)
+{
+	return true;
+}
+struct page_ext_operations page_idle_ops = {
+	.need = need_page_idle,
+};
+#endif
+
+static int __init page_idle_init(void)
+{
+	int err;
+
+	err = sysfs_create_group(mm_kobj, &page_idle_attr_group);
+	if (err) {
+		pr_err("page_idle: register sysfs failed\n");
+		return err;
+	}
+	return 0;
+}
+subsys_initcall(page_idle_init);
diff --git a/mm/page_io.c b/mm/page_io.c
new file mode 100644
index 0000000..b995a5b
--- /dev/null
+++ b/mm/page_io.c
@@ -0,0 +1,377 @@
+/*
+ *  linux/mm/page_io.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *
+ *  Swap reorganised 29.12.95, 
+ *  Asynchronous swapping added 30.12.95. Stephen Tweedie
+ *  Removed race in async swapping. 14.4.1996. Bruno Haible
+ *  Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
+ *  Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
+ */
+
+#include <linux/mm.h>
+#include <linux/kernel_stat.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/bio.h>
+#include <linux/swapops.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/frontswap.h>
+#include <linux/blkdev.h>
+#include <linux/uio.h>
+#include <asm/pgtable.h>
+
+static struct bio *get_swap_bio(gfp_t gfp_flags,
+				struct page *page, bio_end_io_t end_io)
+{
+	struct bio *bio;
+
+	bio = bio_alloc(gfp_flags, 1);
+	if (bio) {
+		bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);
+		bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
+		bio->bi_end_io = end_io;
+
+		bio_add_page(bio, page, PAGE_SIZE, 0);
+		BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE);
+	}
+	return bio;
+}
+
+void end_swap_bio_write(struct bio *bio)
+{
+	struct page *page = bio->bi_io_vec[0].bv_page;
+
+	if (bio->bi_error) {
+		SetPageError(page);
+		/*
+		 * We failed to write the page out to swap-space.
+		 * Re-dirty the page in order to avoid it being reclaimed.
+		 * Also print a dire warning that things will go BAD (tm)
+		 * very quickly.
+		 *
+		 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
+		 */
+		set_page_dirty(page);
+		printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
+				imajor(bio->bi_bdev->bd_inode),
+				iminor(bio->bi_bdev->bd_inode),
+				(unsigned long long)bio->bi_iter.bi_sector);
+		ClearPageReclaim(page);
+	}
+	end_page_writeback(page);
+	bio_put(bio);
+}
+
+static void end_swap_bio_read(struct bio *bio)
+{
+	struct page *page = bio->bi_io_vec[0].bv_page;
+
+	if (bio->bi_error) {
+		SetPageError(page);
+		ClearPageUptodate(page);
+		printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
+				imajor(bio->bi_bdev->bd_inode),
+				iminor(bio->bi_bdev->bd_inode),
+				(unsigned long long)bio->bi_iter.bi_sector);
+		goto out;
+	}
+
+	SetPageUptodate(page);
+
+	/*
+	 * There is no guarantee that the page is in swap cache - the software
+	 * suspend code (at least) uses end_swap_bio_read() against a non-
+	 * swapcache page.  So we must check PG_swapcache before proceeding with
+	 * this optimization.
+	 */
+	if (likely(PageSwapCache(page))) {
+		struct swap_info_struct *sis;
+
+		sis = page_swap_info(page);
+		if (sis->flags & SWP_BLKDEV) {
+			/*
+			 * The swap subsystem performs lazy swap slot freeing,
+			 * expecting that the page will be swapped out again.
+			 * So we can avoid an unnecessary write if the page
+			 * isn't redirtied.
+			 * This is good for real swap storage because we can
+			 * reduce unnecessary I/O and enhance wear-leveling
+			 * if an SSD is used as the as swap device.
+			 * But if in-memory swap device (eg zram) is used,
+			 * this causes a duplicated copy between uncompressed
+			 * data in VM-owned memory and compressed data in
+			 * zram-owned memory.  So let's free zram-owned memory
+			 * and make the VM-owned decompressed page *dirty*,
+			 * so the page should be swapped out somewhere again if
+			 * we again wish to reclaim it.
+			 */
+			struct gendisk *disk = sis->bdev->bd_disk;
+			if (disk->fops->swap_slot_free_notify) {
+				swp_entry_t entry;
+				unsigned long offset;
+
+				entry.val = page_private(page);
+				offset = swp_offset(entry);
+
+				SetPageDirty(page);
+				disk->fops->swap_slot_free_notify(sis->bdev,
+						offset);
+			}
+		}
+	}
+
+out:
+	unlock_page(page);
+	bio_put(bio);
+}
+
+int generic_swapfile_activate(struct swap_info_struct *sis,
+				struct file *swap_file,
+				sector_t *span)
+{
+	struct address_space *mapping = swap_file->f_mapping;
+	struct inode *inode = mapping->host;
+	unsigned blocks_per_page;
+	unsigned long page_no;
+	unsigned blkbits;
+	sector_t probe_block;
+	sector_t last_block;
+	sector_t lowest_block = -1;
+	sector_t highest_block = 0;
+	int nr_extents = 0;
+	int ret;
+
+	blkbits = inode->i_blkbits;
+	blocks_per_page = PAGE_SIZE >> blkbits;
+
+	/*
+	 * Map all the blocks into the extent list.  This code doesn't try
+	 * to be very smart.
+	 */
+	probe_block = 0;
+	page_no = 0;
+	last_block = i_size_read(inode) >> blkbits;
+	while ((probe_block + blocks_per_page) <= last_block &&
+			page_no < sis->max) {
+		unsigned block_in_page;
+		sector_t first_block;
+
+		first_block = bmap(inode, probe_block);
+		if (first_block == 0)
+			goto bad_bmap;
+
+		/*
+		 * It must be PAGE_SIZE aligned on-disk
+		 */
+		if (first_block & (blocks_per_page - 1)) {
+			probe_block++;
+			goto reprobe;
+		}
+
+		for (block_in_page = 1; block_in_page < blocks_per_page;
+					block_in_page++) {
+			sector_t block;
+
+			block = bmap(inode, probe_block + block_in_page);
+			if (block == 0)
+				goto bad_bmap;
+			if (block != first_block + block_in_page) {
+				/* Discontiguity */
+				probe_block++;
+				goto reprobe;
+			}
+		}
+
+		first_block >>= (PAGE_SHIFT - blkbits);
+		if (page_no) {	/* exclude the header page */
+			if (first_block < lowest_block)
+				lowest_block = first_block;
+			if (first_block > highest_block)
+				highest_block = first_block;
+		}
+
+		/*
+		 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
+		 */
+		ret = add_swap_extent(sis, page_no, 1, first_block);
+		if (ret < 0)
+			goto out;
+		nr_extents += ret;
+		page_no++;
+		probe_block += blocks_per_page;
+reprobe:
+		continue;
+	}
+	ret = nr_extents;
+	*span = 1 + highest_block - lowest_block;
+	if (page_no == 0)
+		page_no = 1;	/* force Empty message */
+	sis->max = page_no;
+	sis->pages = page_no - 1;
+	sis->highest_bit = page_no - 1;
+out:
+	return ret;
+bad_bmap:
+	printk(KERN_ERR "swapon: swapfile has holes\n");
+	ret = -EINVAL;
+	goto out;
+}
+
+/*
+ * We may have stale swap cache pages in memory: notice
+ * them here and get rid of the unnecessary final write.
+ */
+int swap_writepage(struct page *page, struct writeback_control *wbc)
+{
+	int ret = 0;
+
+	if (try_to_free_swap(page)) {
+		unlock_page(page);
+		goto out;
+	}
+	if (frontswap_store(page) == 0) {
+		set_page_writeback(page);
+		unlock_page(page);
+		end_page_writeback(page);
+		goto out;
+	}
+	ret = __swap_writepage(page, wbc, end_swap_bio_write);
+out:
+	return ret;
+}
+
+static sector_t swap_page_sector(struct page *page)
+{
+	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
+}
+
+int __swap_writepage(struct page *page, struct writeback_control *wbc,
+		bio_end_io_t end_write_func)
+{
+	struct bio *bio;
+	int ret, rw = WRITE;
+	struct swap_info_struct *sis = page_swap_info(page);
+
+	if (sis->flags & SWP_FILE) {
+		struct kiocb kiocb;
+		struct file *swap_file = sis->swap_file;
+		struct address_space *mapping = swap_file->f_mapping;
+		struct bio_vec bv = {
+			.bv_page = page,
+			.bv_len  = PAGE_SIZE,
+			.bv_offset = 0
+		};
+		struct iov_iter from;
+
+		iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE);
+		init_sync_kiocb(&kiocb, swap_file);
+		kiocb.ki_pos = page_file_offset(page);
+
+		set_page_writeback(page);
+		unlock_page(page);
+		ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos);
+		if (ret == PAGE_SIZE) {
+			count_vm_event(PSWPOUT);
+			ret = 0;
+		} else {
+			/*
+			 * In the case of swap-over-nfs, this can be a
+			 * temporary failure if the system has limited
+			 * memory for allocating transmit buffers.
+			 * Mark the page dirty and avoid
+			 * rotate_reclaimable_page but rate-limit the
+			 * messages but do not flag PageError like
+			 * the normal direct-to-bio case as it could
+			 * be temporary.
+			 */
+			set_page_dirty(page);
+			ClearPageReclaim(page);
+			pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
+				page_file_offset(page));
+		}
+		end_page_writeback(page);
+		return ret;
+	}
+
+	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
+	if (!ret) {
+		count_vm_event(PSWPOUT);
+		return 0;
+	}
+
+	ret = 0;
+	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
+	if (bio == NULL) {
+		set_page_dirty(page);
+		unlock_page(page);
+		ret = -ENOMEM;
+		goto out;
+	}
+	if (wbc->sync_mode == WB_SYNC_ALL)
+		rw |= REQ_SYNC;
+	count_vm_event(PSWPOUT);
+	set_page_writeback(page);
+	unlock_page(page);
+	submit_bio(rw, bio);
+out:
+	return ret;
+}
+
+int swap_readpage(struct page *page)
+{
+	struct bio *bio;
+	int ret = 0;
+	struct swap_info_struct *sis = page_swap_info(page);
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(PageUptodate(page), page);
+	if (frontswap_load(page) == 0) {
+		SetPageUptodate(page);
+		unlock_page(page);
+		goto out;
+	}
+
+	if (sis->flags & SWP_FILE) {
+		struct file *swap_file = sis->swap_file;
+		struct address_space *mapping = swap_file->f_mapping;
+
+		ret = mapping->a_ops->readpage(swap_file, page);
+		if (!ret)
+			count_vm_event(PSWPIN);
+		return ret;
+	}
+
+	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
+	if (!ret) {
+		count_vm_event(PSWPIN);
+		return 0;
+	}
+
+	ret = 0;
+	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
+	if (bio == NULL) {
+		unlock_page(page);
+		ret = -ENOMEM;
+		goto out;
+	}
+	count_vm_event(PSWPIN);
+	submit_bio(READ, bio);
+out:
+	return ret;
+}
+
+int swap_set_page_dirty(struct page *page)
+{
+	struct swap_info_struct *sis = page_swap_info(page);
+
+	if (sis->flags & SWP_FILE) {
+		struct address_space *mapping = sis->swap_file->f_mapping;
+		return mapping->a_ops->set_page_dirty(page);
+	} else {
+		return __set_page_dirty_no_writeback(page);
+	}
+}
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
new file mode 100644
index 0000000..00c9646
--- /dev/null
+++ b/mm/page_isolation.c
@@ -0,0 +1,297 @@
+/*
+ * linux/mm/page_isolation.c
+ */
+
+#include <linux/mm.h>
+#include <linux/page-isolation.h>
+#include <linux/pageblock-flags.h>
+#include <linux/memory.h>
+#include <linux/hugetlb.h>
+#include "internal.h"
+
+static int set_migratetype_isolate(struct page *page,
+				bool skip_hwpoisoned_pages)
+{
+	struct zone *zone;
+	unsigned long flags, pfn;
+	struct memory_isolate_notify arg;
+	int notifier_ret;
+	int ret = -EBUSY;
+
+	zone = page_zone(page);
+
+	spin_lock_irqsave(&zone->lock, flags);
+
+	pfn = page_to_pfn(page);
+	arg.start_pfn = pfn;
+	arg.nr_pages = pageblock_nr_pages;
+	arg.pages_found = 0;
+
+	/*
+	 * It may be possible to isolate a pageblock even if the
+	 * migratetype is not MIGRATE_MOVABLE. The memory isolation
+	 * notifier chain is used by balloon drivers to return the
+	 * number of pages in a range that are held by the balloon
+	 * driver to shrink memory. If all the pages are accounted for
+	 * by balloons, are free, or on the LRU, isolation can continue.
+	 * Later, for example, when memory hotplug notifier runs, these
+	 * pages reported as "can be isolated" should be isolated(freed)
+	 * by the balloon driver through the memory notifier chain.
+	 */
+	notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
+	notifier_ret = notifier_to_errno(notifier_ret);
+	if (notifier_ret)
+		goto out;
+	/*
+	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
+	 * We just check MOVABLE pages.
+	 */
+	if (!has_unmovable_pages(zone, page, arg.pages_found,
+				 skip_hwpoisoned_pages))
+		ret = 0;
+
+	/*
+	 * immobile means "not-on-lru" paes. If immobile is larger than
+	 * removable-by-driver pages reported by notifier, we'll fail.
+	 */
+
+out:
+	if (!ret) {
+		unsigned long nr_pages;
+		int migratetype = get_pageblock_migratetype(page);
+
+		set_pageblock_migratetype(page, MIGRATE_ISOLATE);
+		zone->nr_isolate_pageblock++;
+		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
+
+		__mod_zone_freepage_state(zone, -nr_pages, migratetype);
+	}
+
+	spin_unlock_irqrestore(&zone->lock, flags);
+	if (!ret)
+		drain_all_pages(zone);
+	return ret;
+}
+
+static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
+{
+	struct zone *zone;
+	unsigned long flags, nr_pages;
+	struct page *isolated_page = NULL;
+	unsigned int order;
+	unsigned long page_idx, buddy_idx;
+	struct page *buddy;
+
+	zone = page_zone(page);
+	spin_lock_irqsave(&zone->lock, flags);
+	if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+		goto out;
+
+	/*
+	 * Because freepage with more than pageblock_order on isolated
+	 * pageblock is restricted to merge due to freepage counting problem,
+	 * it is possible that there is free buddy page.
+	 * move_freepages_block() doesn't care of merge so we need other
+	 * approach in order to merge them. Isolation and free will make
+	 * these pages to be merged.
+	 */
+	if (PageBuddy(page)) {
+		order = page_order(page);
+		if (order >= pageblock_order) {
+			page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
+			buddy_idx = __find_buddy_index(page_idx, order);
+			buddy = page + (buddy_idx - page_idx);
+
+			if (pfn_valid_within(page_to_pfn(buddy)) &&
+			    !is_migrate_isolate_page(buddy)) {
+				__isolate_free_page(page, order);
+				kernel_map_pages(page, (1 << order), 1);
+				set_page_refcounted(page);
+				isolated_page = page;
+			}
+		}
+	}
+
+	/*
+	 * If we isolate freepage with more than pageblock_order, there
+	 * should be no freepage in the range, so we could avoid costly
+	 * pageblock scanning for freepage moving.
+	 */
+	if (!isolated_page) {
+		nr_pages = move_freepages_block(zone, page, migratetype);
+		__mod_zone_freepage_state(zone, nr_pages, migratetype);
+	}
+	set_pageblock_migratetype(page, migratetype);
+	zone->nr_isolate_pageblock--;
+out:
+	spin_unlock_irqrestore(&zone->lock, flags);
+	if (isolated_page)
+		__free_pages(isolated_page, order);
+}
+
+static inline struct page *
+__first_valid_page(unsigned long pfn, unsigned long nr_pages)
+{
+	int i;
+	for (i = 0; i < nr_pages; i++)
+		if (pfn_valid_within(pfn + i))
+			break;
+	if (unlikely(i == nr_pages))
+		return NULL;
+	return pfn_to_page(pfn + i);
+}
+
+/*
+ * start_isolate_page_range() -- make page-allocation-type of range of pages
+ * to be MIGRATE_ISOLATE.
+ * @start_pfn: The lower PFN of the range to be isolated.
+ * @end_pfn: The upper PFN of the range to be isolated.
+ * @migratetype: migrate type to set in error recovery.
+ *
+ * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
+ * the range will never be allocated. Any free pages and pages freed in the
+ * future will not be allocated again.
+ *
+ * start_pfn/end_pfn must be aligned to pageblock_order.
+ * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
+ */
+int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
+			     unsigned migratetype, bool skip_hwpoisoned_pages)
+{
+	unsigned long pfn;
+	unsigned long undo_pfn;
+	struct page *page;
+
+	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
+	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+
+	for (pfn = start_pfn;
+	     pfn < end_pfn;
+	     pfn += pageblock_nr_pages) {
+		page = __first_valid_page(pfn, pageblock_nr_pages);
+		if (page &&
+		    set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
+			undo_pfn = pfn;
+			goto undo;
+		}
+	}
+	return 0;
+undo:
+	for (pfn = start_pfn;
+	     pfn < undo_pfn;
+	     pfn += pageblock_nr_pages)
+		unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
+
+	return -EBUSY;
+}
+
+/*
+ * Make isolated pages available again.
+ */
+int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
+			    unsigned migratetype)
+{
+	unsigned long pfn;
+	struct page *page;
+	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
+	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+	for (pfn = start_pfn;
+	     pfn < end_pfn;
+	     pfn += pageblock_nr_pages) {
+		page = __first_valid_page(pfn, pageblock_nr_pages);
+		if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+			continue;
+		unset_migratetype_isolate(page, migratetype);
+	}
+	return 0;
+}
+/*
+ * Test all pages in the range is free(means isolated) or not.
+ * all pages in [start_pfn...end_pfn) must be in the same zone.
+ * zone->lock must be held before call this.
+ *
+ * Returns 1 if all pages in the range are isolated.
+ */
+static int
+__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
+				  bool skip_hwpoisoned_pages)
+{
+	struct page *page;
+
+	while (pfn < end_pfn) {
+		if (!pfn_valid_within(pfn)) {
+			pfn++;
+			continue;
+		}
+		page = pfn_to_page(pfn);
+		if (PageBuddy(page))
+			/*
+			 * If the page is on a free list, it has to be on
+			 * the correct MIGRATE_ISOLATE freelist. There is no
+			 * simple way to verify that as VM_BUG_ON(), though.
+			 */
+			pfn += 1 << page_order(page);
+		else if (skip_hwpoisoned_pages && PageHWPoison(page))
+			/* A HWPoisoned page cannot be also PageBuddy */
+			pfn++;
+		else
+			break;
+	}
+	if (pfn < end_pfn)
+		return 0;
+	return 1;
+}
+
+int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
+			bool skip_hwpoisoned_pages)
+{
+	unsigned long pfn, flags;
+	struct page *page;
+	struct zone *zone;
+	int ret;
+
+	/*
+	 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
+	 * are not aligned to pageblock_nr_pages.
+	 * Then we just check migratetype first.
+	 */
+	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+		page = __first_valid_page(pfn, pageblock_nr_pages);
+		if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+			break;
+	}
+	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
+	if ((pfn < end_pfn) || !page)
+		return -EBUSY;
+	/* Check all pages are free or marked as ISOLATED */
+	zone = page_zone(page);
+	spin_lock_irqsave(&zone->lock, flags);
+	ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
+						skip_hwpoisoned_pages);
+	spin_unlock_irqrestore(&zone->lock, flags);
+	return ret ? 0 : -EBUSY;
+}
+
+struct page *alloc_migrate_target(struct page *page, unsigned long private,
+				  int **resultp)
+{
+	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
+
+	/*
+	 * TODO: allocate a destination hugepage from a nearest neighbor node,
+	 * accordance with memory policy of the user process if possible. For
+	 * now as a simple work-around, we use the next node for destination.
+	 */
+	if (PageHuge(page)) {
+		int node = next_online_node(page_to_nid(page));
+		if (node == MAX_NUMNODES)
+			node = first_online_node;
+		return alloc_huge_page_node(page_hstate(compound_head(page)),
+					    node);
+	}
+
+	if (PageHighMem(page))
+		gfp_mask |= __GFP_HIGHMEM;
+
+	return alloc_page(gfp_mask);
+}
diff --git a/mm/page_owner.c b/mm/page_owner.c
new file mode 100644
index 0000000..983c3a1
--- /dev/null
+++ b/mm/page_owner.c
@@ -0,0 +1,320 @@
+#include <linux/debugfs.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/bootmem.h>
+#include <linux/stacktrace.h>
+#include <linux/page_owner.h>
+#include "internal.h"
+
+static bool page_owner_disabled = true;
+bool page_owner_inited __read_mostly;
+
+static void init_early_allocated_pages(void);
+
+static int early_page_owner_param(char *buf)
+{
+	if (!buf)
+		return -EINVAL;
+
+	if (strcmp(buf, "on") == 0)
+		page_owner_disabled = false;
+
+	return 0;
+}
+early_param("page_owner", early_page_owner_param);
+
+static bool need_page_owner(void)
+{
+	if (page_owner_disabled)
+		return false;
+
+	return true;
+}
+
+static void init_page_owner(void)
+{
+	if (page_owner_disabled)
+		return;
+
+	page_owner_inited = true;
+	init_early_allocated_pages();
+}
+
+struct page_ext_operations page_owner_ops = {
+	.need = need_page_owner,
+	.init = init_page_owner,
+};
+
+void __reset_page_owner(struct page *page, unsigned int order)
+{
+	int i;
+	struct page_ext *page_ext;
+
+	for (i = 0; i < (1 << order); i++) {
+		page_ext = lookup_page_ext(page + i);
+		__clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
+	}
+}
+
+void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
+{
+	struct page_ext *page_ext = lookup_page_ext(page);
+	struct stack_trace trace = {
+		.nr_entries = 0,
+		.max_entries = ARRAY_SIZE(page_ext->trace_entries),
+		.entries = &page_ext->trace_entries[0],
+		.skip = 3,
+	};
+
+	save_stack_trace(&trace);
+
+	page_ext->order = order;
+	page_ext->gfp_mask = gfp_mask;
+	page_ext->nr_entries = trace.nr_entries;
+
+	__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
+}
+
+gfp_t __get_page_owner_gfp(struct page *page)
+{
+	struct page_ext *page_ext = lookup_page_ext(page);
+
+	return page_ext->gfp_mask;
+}
+
+static ssize_t
+print_page_owner(char __user *buf, size_t count, unsigned long pfn,
+		struct page *page, struct page_ext *page_ext)
+{
+	int ret;
+	int pageblock_mt, page_mt;
+	char *kbuf;
+	struct stack_trace trace = {
+		.nr_entries = page_ext->nr_entries,
+		.entries = &page_ext->trace_entries[0],
+	};
+
+	kbuf = kmalloc(count, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	ret = snprintf(kbuf, count,
+			"Page allocated via order %u, mask 0x%x\n",
+			page_ext->order, page_ext->gfp_mask);
+
+	if (ret >= count)
+		goto err;
+
+	/* Print information relevant to grouping pages by mobility */
+	pageblock_mt = get_pfnblock_migratetype(page, pfn);
+	page_mt  = gfpflags_to_migratetype(page_ext->gfp_mask);
+	ret += snprintf(kbuf + ret, count - ret,
+			"PFN %lu Block %lu type %d %s Flags %s%s%s%s%s%s%s%s%s%s%s%s\n",
+			pfn,
+			pfn >> pageblock_order,
+			pageblock_mt,
+			pageblock_mt != page_mt ? "Fallback" : "        ",
+			PageLocked(page)	? "K" : " ",
+			PageError(page)		? "E" : " ",
+			PageReferenced(page)	? "R" : " ",
+			PageUptodate(page)	? "U" : " ",
+			PageDirty(page)		? "D" : " ",
+			PageLRU(page)		? "L" : " ",
+			PageActive(page)	? "A" : " ",
+			PageSlab(page)		? "S" : " ",
+			PageWriteback(page)	? "W" : " ",
+			PageCompound(page)	? "C" : " ",
+			PageSwapCache(page)	? "B" : " ",
+			PageMappedToDisk(page)	? "M" : " ");
+
+	if (ret >= count)
+		goto err;
+
+	ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
+	if (ret >= count)
+		goto err;
+
+	ret += snprintf(kbuf + ret, count - ret, "\n");
+	if (ret >= count)
+		goto err;
+
+	if (copy_to_user(buf, kbuf, ret))
+		ret = -EFAULT;
+
+	kfree(kbuf);
+	return ret;
+
+err:
+	kfree(kbuf);
+	return -ENOMEM;
+}
+
+static ssize_t
+read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	unsigned long pfn;
+	struct page *page;
+	struct page_ext *page_ext;
+
+	if (!page_owner_inited)
+		return -EINVAL;
+
+	page = NULL;
+	pfn = min_low_pfn + *ppos;
+
+	/* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
+	while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
+		pfn++;
+
+	drain_all_pages(NULL);
+
+	/* Find an allocated page */
+	for (; pfn < max_pfn; pfn++) {
+		/*
+		 * If the new page is in a new MAX_ORDER_NR_PAGES area,
+		 * validate the area as existing, skip it if not
+		 */
+		if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
+			pfn += MAX_ORDER_NR_PAGES - 1;
+			continue;
+		}
+
+		/* Check for holes within a MAX_ORDER area */
+		if (!pfn_valid_within(pfn))
+			continue;
+
+		page = pfn_to_page(pfn);
+		if (PageBuddy(page)) {
+			unsigned long freepage_order = page_order_unsafe(page);
+
+			if (freepage_order < MAX_ORDER)
+				pfn += (1UL << freepage_order) - 1;
+			continue;
+		}
+
+		page_ext = lookup_page_ext(page);
+
+		/*
+		 * Some pages could be missed by concurrent allocation or free,
+		 * because we don't hold the zone lock.
+		 */
+		if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
+			continue;
+
+		/* Record the next PFN to read in the file offset */
+		*ppos = (pfn - min_low_pfn) + 1;
+
+		return print_page_owner(buf, count, pfn, page, page_ext);
+	}
+
+	return 0;
+}
+
+static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
+{
+	struct page *page;
+	struct page_ext *page_ext;
+	unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
+	unsigned long end_pfn = pfn + zone->spanned_pages;
+	unsigned long count = 0;
+
+	/* Scan block by block. First and last block may be incomplete */
+	pfn = zone->zone_start_pfn;
+
+	/*
+	 * Walk the zone in pageblock_nr_pages steps. If a page block spans
+	 * a zone boundary, it will be double counted between zones. This does
+	 * not matter as the mixed block count will still be correct
+	 */
+	for (; pfn < end_pfn; ) {
+		if (!pfn_valid(pfn)) {
+			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
+			continue;
+		}
+
+		block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+		block_end_pfn = min(block_end_pfn, end_pfn);
+
+		page = pfn_to_page(pfn);
+
+		for (; pfn < block_end_pfn; pfn++) {
+			if (!pfn_valid_within(pfn))
+				continue;
+
+			page = pfn_to_page(pfn);
+
+			/*
+			 * We are safe to check buddy flag and order, because
+			 * this is init stage and only single thread runs.
+			 */
+			if (PageBuddy(page)) {
+				pfn += (1UL << page_order(page)) - 1;
+				continue;
+			}
+
+			if (PageReserved(page))
+				continue;
+
+			page_ext = lookup_page_ext(page);
+
+			/* Maybe overraping zone */
+			if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
+				continue;
+
+			/* Found early allocated page */
+			set_page_owner(page, 0, 0);
+			count++;
+		}
+	}
+
+	pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
+		pgdat->node_id, zone->name, count);
+}
+
+static void init_zones_in_node(pg_data_t *pgdat)
+{
+	struct zone *zone;
+	struct zone *node_zones = pgdat->node_zones;
+	unsigned long flags;
+
+	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
+		if (!populated_zone(zone))
+			continue;
+
+		spin_lock_irqsave(&zone->lock, flags);
+		init_pages_in_zone(pgdat, zone);
+		spin_unlock_irqrestore(&zone->lock, flags);
+	}
+}
+
+static void init_early_allocated_pages(void)
+{
+	pg_data_t *pgdat;
+
+	drain_all_pages(NULL);
+	for_each_online_pgdat(pgdat)
+		init_zones_in_node(pgdat);
+}
+
+static const struct file_operations proc_page_owner_operations = {
+	.read		= read_page_owner,
+};
+
+static int __init pageowner_init(void)
+{
+	struct dentry *dentry;
+
+	if (!page_owner_inited) {
+		pr_info("page_owner is disabled\n");
+		return 0;
+	}
+
+	dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
+			NULL, &proc_page_owner_operations);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	return 0;
+}
+late_initcall(pageowner_init)
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
new file mode 100644
index 0000000..29f2f8b
--- /dev/null
+++ b/mm/pagewalk.c
@@ -0,0 +1,304 @@
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/sched.h>
+#include <linux/hugetlb.h>
+
+static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+			  struct mm_walk *walk)
+{
+	pte_t *pte;
+	int err = 0;
+
+	pte = pte_offset_map(pmd, addr);
+	for (;;) {
+		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
+		if (err)
+		       break;
+		addr += PAGE_SIZE;
+		if (addr == end)
+			break;
+		pte++;
+	}
+
+	pte_unmap(pte);
+	return err;
+}
+
+static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
+			  struct mm_walk *walk)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	int err = 0;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+again:
+		next = pmd_addr_end(addr, end);
+		if (pmd_none(*pmd) || !walk->vma) {
+			if (walk->pte_hole)
+				err = walk->pte_hole(addr, next, walk);
+			if (err)
+				break;
+			continue;
+		}
+		/*
+		 * This implies that each ->pmd_entry() handler
+		 * needs to know about pmd_trans_huge() pmds
+		 */
+		if (walk->pmd_entry)
+			err = walk->pmd_entry(pmd, addr, next, walk);
+		if (err)
+			break;
+
+		/*
+		 * Check this here so we only break down trans_huge
+		 * pages when we _need_ to
+		 */
+		if (!walk->pte_entry)
+			continue;
+
+		split_huge_page_pmd_mm(walk->mm, addr, pmd);
+		if (pmd_trans_unstable(pmd))
+			goto again;
+		err = walk_pte_range(pmd, addr, next, walk);
+		if (err)
+			break;
+	} while (pmd++, addr = next, addr != end);
+
+	return err;
+}
+
+static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
+			  struct mm_walk *walk)
+{
+	pud_t *pud;
+	unsigned long next;
+	int err = 0;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud)) {
+			if (walk->pte_hole)
+				err = walk->pte_hole(addr, next, walk);
+			if (err)
+				break;
+			continue;
+		}
+		if (walk->pmd_entry || walk->pte_entry)
+			err = walk_pmd_range(pud, addr, next, walk);
+		if (err)
+			break;
+	} while (pud++, addr = next, addr != end);
+
+	return err;
+}
+
+static int walk_pgd_range(unsigned long addr, unsigned long end,
+			  struct mm_walk *walk)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	int err = 0;
+
+	pgd = pgd_offset(walk->mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd)) {
+			if (walk->pte_hole)
+				err = walk->pte_hole(addr, next, walk);
+			if (err)
+				break;
+			continue;
+		}
+		if (walk->pmd_entry || walk->pte_entry)
+			err = walk_pud_range(pgd, addr, next, walk);
+		if (err)
+			break;
+	} while (pgd++, addr = next, addr != end);
+
+	return err;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
+				       unsigned long end)
+{
+	unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
+	return boundary < end ? boundary : end;
+}
+
+static int walk_hugetlb_range(unsigned long addr, unsigned long end,
+			      struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+	struct hstate *h = hstate_vma(vma);
+	unsigned long next;
+	unsigned long hmask = huge_page_mask(h);
+	pte_t *pte;
+	int err = 0;
+
+	do {
+		next = hugetlb_entry_end(h, addr, end);
+		pte = huge_pte_offset(walk->mm, addr & hmask);
+		if (pte && walk->hugetlb_entry)
+			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+		if (err)
+			break;
+	} while (addr = next, addr != end);
+
+	return err;
+}
+
+#else /* CONFIG_HUGETLB_PAGE */
+static int walk_hugetlb_range(unsigned long addr, unsigned long end,
+			      struct mm_walk *walk)
+{
+	return 0;
+}
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+/*
+ * Decide whether we really walk over the current vma on [@start, @end)
+ * or skip it via the returned value. Return 0 if we do walk over the
+ * current vma, and return 1 if we skip the vma. Negative values means
+ * error, where we abort the current walk.
+ */
+static int walk_page_test(unsigned long start, unsigned long end,
+			struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+
+	if (walk->test_walk)
+		return walk->test_walk(start, end, walk);
+
+	/*
+	 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
+	 * range, so we don't walk over it as we do for normal vmas. However,
+	 * Some callers are interested in handling hole range and they don't
+	 * want to just ignore any single address range. Such users certainly
+	 * define their ->pte_hole() callbacks, so let's delegate them to handle
+	 * vma(VM_PFNMAP).
+	 */
+	if (vma->vm_flags & VM_PFNMAP) {
+		int err = 1;
+		if (walk->pte_hole)
+			err = walk->pte_hole(start, end, walk);
+		return err ? err : 1;
+	}
+	return 0;
+}
+
+static int __walk_page_range(unsigned long start, unsigned long end,
+			struct mm_walk *walk)
+{
+	int err = 0;
+	struct vm_area_struct *vma = walk->vma;
+
+	if (vma && is_vm_hugetlb_page(vma)) {
+		if (walk->hugetlb_entry)
+			err = walk_hugetlb_range(start, end, walk);
+	} else
+		err = walk_pgd_range(start, end, walk);
+
+	return err;
+}
+
+/**
+ * walk_page_range - walk page table with caller specific callbacks
+ *
+ * Recursively walk the page table tree of the process represented by @walk->mm
+ * within the virtual address range [@start, @end). During walking, we can do
+ * some caller-specific works for each entry, by setting up pmd_entry(),
+ * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
+ * callbacks, the associated entries/pages are just ignored.
+ * The return values of these callbacks are commonly defined like below:
+ *  - 0  : succeeded to handle the current entry, and if you don't reach the
+ *         end address yet, continue to walk.
+ *  - >0 : succeeded to handle the current entry, and return to the caller
+ *         with caller specific value.
+ *  - <0 : failed to handle the current entry, and return to the caller
+ *         with error code.
+ *
+ * Before starting to walk page table, some callers want to check whether
+ * they really want to walk over the current vma, typically by checking
+ * its vm_flags. walk_page_test() and @walk->test_walk() are used for this
+ * purpose.
+ *
+ * struct mm_walk keeps current values of some common data like vma and pmd,
+ * which are useful for the access from callbacks. If you want to pass some
+ * caller-specific data to callbacks, @walk->private should be helpful.
+ *
+ * Locking:
+ *   Callers of walk_page_range() and walk_page_vma() should hold
+ *   @walk->mm->mmap_sem, because these function traverse vma list and/or
+ *   access to vma's data.
+ */
+int walk_page_range(unsigned long start, unsigned long end,
+		    struct mm_walk *walk)
+{
+	int err = 0;
+	unsigned long next;
+	struct vm_area_struct *vma;
+
+	if (start >= end)
+		return -EINVAL;
+
+	if (!walk->mm)
+		return -EINVAL;
+
+	VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm);
+
+	vma = find_vma(walk->mm, start);
+	do {
+		if (!vma) { /* after the last vma */
+			walk->vma = NULL;
+			next = end;
+		} else if (start < vma->vm_start) { /* outside vma */
+			walk->vma = NULL;
+			next = min(end, vma->vm_start);
+		} else { /* inside vma */
+			walk->vma = vma;
+			next = min(end, vma->vm_end);
+			vma = vma->vm_next;
+
+			err = walk_page_test(start, next, walk);
+			if (err > 0) {
+				/*
+				 * positive return values are purely for
+				 * controlling the pagewalk, so should never
+				 * be passed to the callers.
+				 */
+				err = 0;
+				continue;
+			}
+			if (err < 0)
+				break;
+		}
+		if (walk->vma || walk->pte_hole)
+			err = __walk_page_range(start, next, walk);
+		if (err)
+			break;
+	} while (start = next, start < end);
+	return err;
+}
+
+int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk)
+{
+	int err;
+
+	if (!walk->mm)
+		return -EINVAL;
+
+	VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
+	VM_BUG_ON(!vma);
+	walk->vma = vma;
+	err = walk_page_test(vma->vm_start, vma->vm_end, walk);
+	if (err > 0)
+		return 0;
+	if (err < 0)
+		return err;
+	return __walk_page_range(vma->vm_start, vma->vm_end, walk);
+}
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
new file mode 100644
index 0000000..10e3d0b
--- /dev/null
+++ b/mm/percpu-km.c
@@ -0,0 +1,110 @@
+/*
+ * mm/percpu-km.c - kernel memory based chunk allocation
+ *
+ * Copyright (C) 2010		SUSE Linux Products GmbH
+ * Copyright (C) 2010		Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Chunks are allocated as a contiguous kernel memory using gfp
+ * allocation.  This is to be used on nommu architectures.
+ *
+ * To use percpu-km,
+ *
+ * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
+ *
+ * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined.  It's
+ *   not compatible with PER_CPU_KM.  EMBED_FIRST_CHUNK should work
+ *   fine.
+ *
+ * - NUMA is not supported.  When setting up the first chunk,
+ *   @cpu_distance_fn should be NULL or report all CPUs to be nearer
+ *   than or at LOCAL_DISTANCE.
+ *
+ * - It's best if the chunk size is power of two multiple of
+ *   PAGE_SIZE.  Because each chunk is allocated as a contiguous
+ *   kernel memory block using alloc_pages(), memory will be wasted if
+ *   chunk size is not aligned.  percpu-km code will whine about it.
+ */
+
+#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
+#error "contiguous percpu allocation is incompatible with paged first chunk"
+#endif
+
+#include <linux/log2.h>
+
+static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
+			       int page_start, int page_end)
+{
+	return 0;
+}
+
+static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
+				  int page_start, int page_end)
+{
+	/* nada */
+}
+
+static struct pcpu_chunk *pcpu_create_chunk(void)
+{
+	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
+	struct pcpu_chunk *chunk;
+	struct page *pages;
+	int i;
+
+	chunk = pcpu_alloc_chunk();
+	if (!chunk)
+		return NULL;
+
+	pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages));
+	if (!pages) {
+		pcpu_free_chunk(chunk);
+		return NULL;
+	}
+
+	for (i = 0; i < nr_pages; i++)
+		pcpu_set_page_chunk(nth_page(pages, i), chunk);
+
+	chunk->data = pages;
+	chunk->base_addr = page_address(pages) - pcpu_group_offsets[0];
+
+	spin_lock_irq(&pcpu_lock);
+	pcpu_chunk_populated(chunk, 0, nr_pages);
+	spin_unlock_irq(&pcpu_lock);
+
+	return chunk;
+}
+
+static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
+{
+	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
+
+	if (chunk && chunk->data)
+		__free_pages(chunk->data, order_base_2(nr_pages));
+	pcpu_free_chunk(chunk);
+}
+
+static struct page *pcpu_addr_to_page(void *addr)
+{
+	return virt_to_page(addr);
+}
+
+static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
+{
+	size_t nr_pages, alloc_pages;
+
+	/* all units must be in a single group */
+	if (ai->nr_groups != 1) {
+		printk(KERN_CRIT "percpu: can't handle more than one groups\n");
+		return -EINVAL;
+	}
+
+	nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
+	alloc_pages = roundup_pow_of_two(nr_pages);
+
+	if (alloc_pages > nr_pages)
+		printk(KERN_WARNING "percpu: wasting %zu pages per chunk\n",
+		       alloc_pages - nr_pages);
+
+	return 0;
+}
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
new file mode 100644
index 0000000..538998a
--- /dev/null
+++ b/mm/percpu-vm.c
@@ -0,0 +1,366 @@
+/*
+ * mm/percpu-vm.c - vmalloc area based chunk allocation
+ *
+ * Copyright (C) 2010		SUSE Linux Products GmbH
+ * Copyright (C) 2010		Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Chunks are mapped into vmalloc areas and populated page by page.
+ * This is the default chunk allocator.
+ */
+
+static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
+				    unsigned int cpu, int page_idx)
+{
+	/* must not be used on pre-mapped chunk */
+	WARN_ON(chunk->immutable);
+
+	return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
+}
+
+/**
+ * pcpu_get_pages - get temp pages array
+ * @chunk: chunk of interest
+ *
+ * Returns pointer to array of pointers to struct page which can be indexed
+ * with pcpu_page_idx().  Note that there is only one array and accesses
+ * should be serialized by pcpu_alloc_mutex.
+ *
+ * RETURNS:
+ * Pointer to temp pages array on success.
+ */
+static struct page **pcpu_get_pages(struct pcpu_chunk *chunk_alloc)
+{
+	static struct page **pages;
+	size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
+
+	lockdep_assert_held(&pcpu_alloc_mutex);
+
+	if (!pages)
+		pages = pcpu_mem_zalloc(pages_size);
+	return pages;
+}
+
+/**
+ * pcpu_free_pages - free pages which were allocated for @chunk
+ * @chunk: chunk pages were allocated for
+ * @pages: array of pages to be freed, indexed by pcpu_page_idx()
+ * @page_start: page index of the first page to be freed
+ * @page_end: page index of the last page to be freed + 1
+ *
+ * Free pages [@page_start and @page_end) in @pages for all units.
+ * The pages were allocated for @chunk.
+ */
+static void pcpu_free_pages(struct pcpu_chunk *chunk,
+			    struct page **pages, int page_start, int page_end)
+{
+	unsigned int cpu;
+	int i;
+
+	for_each_possible_cpu(cpu) {
+		for (i = page_start; i < page_end; i++) {
+			struct page *page = pages[pcpu_page_idx(cpu, i)];
+
+			if (page)
+				__free_page(page);
+		}
+	}
+}
+
+/**
+ * pcpu_alloc_pages - allocates pages for @chunk
+ * @chunk: target chunk
+ * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
+ * @page_start: page index of the first page to be allocated
+ * @page_end: page index of the last page to be allocated + 1
+ *
+ * Allocate pages [@page_start,@page_end) into @pages for all units.
+ * The allocation is for @chunk.  Percpu core doesn't care about the
+ * content of @pages and will pass it verbatim to pcpu_map_pages().
+ */
+static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
+			    struct page **pages, int page_start, int page_end)
+{
+	const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
+	unsigned int cpu, tcpu;
+	int i;
+
+	for_each_possible_cpu(cpu) {
+		for (i = page_start; i < page_end; i++) {
+			struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
+
+			*pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
+			if (!*pagep)
+				goto err;
+		}
+	}
+	return 0;
+
+err:
+	while (--i >= page_start)
+		__free_page(pages[pcpu_page_idx(cpu, i)]);
+
+	for_each_possible_cpu(tcpu) {
+		if (tcpu == cpu)
+			break;
+		for (i = page_start; i < page_end; i++)
+			__free_page(pages[pcpu_page_idx(tcpu, i)]);
+	}
+	return -ENOMEM;
+}
+
+/**
+ * pcpu_pre_unmap_flush - flush cache prior to unmapping
+ * @chunk: chunk the regions to be flushed belongs to
+ * @page_start: page index of the first page to be flushed
+ * @page_end: page index of the last page to be flushed + 1
+ *
+ * Pages in [@page_start,@page_end) of @chunk are about to be
+ * unmapped.  Flush cache.  As each flushing trial can be very
+ * expensive, issue flush on the whole region at once rather than
+ * doing it for each cpu.  This could be an overkill but is more
+ * scalable.
+ */
+static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
+				 int page_start, int page_end)
+{
+	flush_cache_vunmap(
+		pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
+		pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
+}
+
+static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
+{
+	unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
+}
+
+/**
+ * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
+ * @chunk: chunk of interest
+ * @pages: pages array which can be used to pass information to free
+ * @page_start: page index of the first page to unmap
+ * @page_end: page index of the last page to unmap + 1
+ *
+ * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
+ * Corresponding elements in @pages were cleared by the caller and can
+ * be used to carry information to pcpu_free_pages() which will be
+ * called after all unmaps are finished.  The caller should call
+ * proper pre/post flush functions.
+ */
+static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
+			     struct page **pages, int page_start, int page_end)
+{
+	unsigned int cpu;
+	int i;
+
+	for_each_possible_cpu(cpu) {
+		for (i = page_start; i < page_end; i++) {
+			struct page *page;
+
+			page = pcpu_chunk_page(chunk, cpu, i);
+			WARN_ON(!page);
+			pages[pcpu_page_idx(cpu, i)] = page;
+		}
+		__pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
+				   page_end - page_start);
+	}
+}
+
+/**
+ * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
+ * @chunk: pcpu_chunk the regions to be flushed belong to
+ * @page_start: page index of the first page to be flushed
+ * @page_end: page index of the last page to be flushed + 1
+ *
+ * Pages [@page_start,@page_end) of @chunk have been unmapped.  Flush
+ * TLB for the regions.  This can be skipped if the area is to be
+ * returned to vmalloc as vmalloc will handle TLB flushing lazily.
+ *
+ * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
+ * for the whole region.
+ */
+static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
+				      int page_start, int page_end)
+{
+	flush_tlb_kernel_range(
+		pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
+		pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
+}
+
+static int __pcpu_map_pages(unsigned long addr, struct page **pages,
+			    int nr_pages)
+{
+	return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
+					PAGE_KERNEL, pages);
+}
+
+/**
+ * pcpu_map_pages - map pages into a pcpu_chunk
+ * @chunk: chunk of interest
+ * @pages: pages array containing pages to be mapped
+ * @page_start: page index of the first page to map
+ * @page_end: page index of the last page to map + 1
+ *
+ * For each cpu, map pages [@page_start,@page_end) into @chunk.  The
+ * caller is responsible for calling pcpu_post_map_flush() after all
+ * mappings are complete.
+ *
+ * This function is responsible for setting up whatever is necessary for
+ * reverse lookup (addr -> chunk).
+ */
+static int pcpu_map_pages(struct pcpu_chunk *chunk,
+			  struct page **pages, int page_start, int page_end)
+{
+	unsigned int cpu, tcpu;
+	int i, err;
+
+	for_each_possible_cpu(cpu) {
+		err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
+				       &pages[pcpu_page_idx(cpu, page_start)],
+				       page_end - page_start);
+		if (err < 0)
+			goto err;
+
+		for (i = page_start; i < page_end; i++)
+			pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
+					    chunk);
+	}
+	return 0;
+err:
+	for_each_possible_cpu(tcpu) {
+		if (tcpu == cpu)
+			break;
+		__pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
+				   page_end - page_start);
+	}
+	pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
+	return err;
+}
+
+/**
+ * pcpu_post_map_flush - flush cache after mapping
+ * @chunk: pcpu_chunk the regions to be flushed belong to
+ * @page_start: page index of the first page to be flushed
+ * @page_end: page index of the last page to be flushed + 1
+ *
+ * Pages [@page_start,@page_end) of @chunk have been mapped.  Flush
+ * cache.
+ *
+ * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
+ * for the whole region.
+ */
+static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
+				int page_start, int page_end)
+{
+	flush_cache_vmap(
+		pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
+		pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
+}
+
+/**
+ * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
+ * @chunk: chunk of interest
+ * @page_start: the start page
+ * @page_end: the end page
+ *
+ * For each cpu, populate and map pages [@page_start,@page_end) into
+ * @chunk.
+ *
+ * CONTEXT:
+ * pcpu_alloc_mutex, does GFP_KERNEL allocation.
+ */
+static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
+			       int page_start, int page_end)
+{
+	struct page **pages;
+
+	pages = pcpu_get_pages(chunk);
+	if (!pages)
+		return -ENOMEM;
+
+	if (pcpu_alloc_pages(chunk, pages, page_start, page_end))
+		return -ENOMEM;
+
+	if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
+		pcpu_free_pages(chunk, pages, page_start, page_end);
+		return -ENOMEM;
+	}
+	pcpu_post_map_flush(chunk, page_start, page_end);
+
+	return 0;
+}
+
+/**
+ * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
+ * @chunk: chunk to depopulate
+ * @page_start: the start page
+ * @page_end: the end page
+ *
+ * For each cpu, depopulate and unmap pages [@page_start,@page_end)
+ * from @chunk.
+ *
+ * CONTEXT:
+ * pcpu_alloc_mutex.
+ */
+static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
+				  int page_start, int page_end)
+{
+	struct page **pages;
+
+	/*
+	 * If control reaches here, there must have been at least one
+	 * successful population attempt so the temp pages array must
+	 * be available now.
+	 */
+	pages = pcpu_get_pages(chunk);
+	BUG_ON(!pages);
+
+	/* unmap and free */
+	pcpu_pre_unmap_flush(chunk, page_start, page_end);
+
+	pcpu_unmap_pages(chunk, pages, page_start, page_end);
+
+	/* no need to flush tlb, vmalloc will handle it lazily */
+
+	pcpu_free_pages(chunk, pages, page_start, page_end);
+}
+
+static struct pcpu_chunk *pcpu_create_chunk(void)
+{
+	struct pcpu_chunk *chunk;
+	struct vm_struct **vms;
+
+	chunk = pcpu_alloc_chunk();
+	if (!chunk)
+		return NULL;
+
+	vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
+				pcpu_nr_groups, pcpu_atom_size);
+	if (!vms) {
+		pcpu_free_chunk(chunk);
+		return NULL;
+	}
+
+	chunk->data = vms;
+	chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
+	return chunk;
+}
+
+static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
+{
+	if (chunk && chunk->data)
+		pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
+	pcpu_free_chunk(chunk);
+}
+
+static struct page *pcpu_addr_to_page(void *addr)
+{
+	return vmalloc_to_page(addr);
+}
+
+static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
+{
+	/* no extra restriction */
+	return 0;
+}
diff --git a/mm/percpu.c b/mm/percpu.c
new file mode 100644
index 0000000..ef6353f
--- /dev/null
+++ b/mm/percpu.c
@@ -0,0 +1,2312 @@
+/*
+ * mm/percpu.c - percpu memory allocator
+ *
+ * Copyright (C) 2009		SUSE Linux Products GmbH
+ * Copyright (C) 2009		Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ *
+ * This is percpu allocator which can handle both static and dynamic
+ * areas.  Percpu areas are allocated in chunks.  Each chunk is
+ * consisted of boot-time determined number of units and the first
+ * chunk is used for static percpu variables in the kernel image
+ * (special boot time alloc/init handling necessary as these areas
+ * need to be brought up before allocation services are running).
+ * Unit grows as necessary and all units grow or shrink in unison.
+ * When a chunk is filled up, another chunk is allocated.
+ *
+ *  c0                           c1                         c2
+ *  -------------------          -------------------        ------------
+ * | u0 | u1 | u2 | u3 |        | u0 | u1 | u2 | u3 |      | u0 | u1 | u
+ *  -------------------  ......  -------------------  ....  ------------
+ *
+ * Allocation is done in offset-size areas of single unit space.  Ie,
+ * an area of 512 bytes at 6k in c1 occupies 512 bytes at 6k of c1:u0,
+ * c1:u1, c1:u2 and c1:u3.  On UMA, units corresponds directly to
+ * cpus.  On NUMA, the mapping can be non-linear and even sparse.
+ * Percpu access can be done by configuring percpu base registers
+ * according to cpu to unit mapping and pcpu_unit_size.
+ *
+ * There are usually many small percpu allocations many of them being
+ * as small as 4 bytes.  The allocator organizes chunks into lists
+ * according to free size and tries to allocate from the fullest one.
+ * Each chunk keeps the maximum contiguous area size hint which is
+ * guaranteed to be equal to or larger than the maximum contiguous
+ * area in the chunk.  This helps the allocator not to iterate the
+ * chunk maps unnecessarily.
+ *
+ * Allocation state in each chunk is kept using an array of integers
+ * on chunk->map.  A positive value in the map represents a free
+ * region and negative allocated.  Allocation inside a chunk is done
+ * by scanning this map sequentially and serving the first matching
+ * entry.  This is mostly copied from the percpu_modalloc() allocator.
+ * Chunks can be determined from the address using the index field
+ * in the page struct. The index field contains a pointer to the chunk.
+ *
+ * To use this allocator, arch code should do the followings.
+ *
+ * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
+ *   regular address to percpu pointer and back if they need to be
+ *   different from the default
+ *
+ * - use pcpu_setup_first_chunk() during percpu area initialization to
+ *   setup the first chunk containing the kernel static percpu area
+ */
+
+#include <linux/bitmap.h>
+#include <linux/bootmem.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/log2.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/pfn.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+#include <linux/kmemleak.h>
+
+#include <asm/cacheflush.h>
+#include <asm/sections.h>
+#include <asm/tlbflush.h>
+#include <asm/io.h>
+
+#define PCPU_SLOT_BASE_SHIFT		5	/* 1-31 shares the same slot */
+#define PCPU_DFL_MAP_ALLOC		16	/* start a map with 16 ents */
+#define PCPU_ATOMIC_MAP_MARGIN_LOW	32
+#define PCPU_ATOMIC_MAP_MARGIN_HIGH	64
+#define PCPU_EMPTY_POP_PAGES_LOW	2
+#define PCPU_EMPTY_POP_PAGES_HIGH	4
+
+#ifdef CONFIG_SMP
+/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
+#ifndef __addr_to_pcpu_ptr
+#define __addr_to_pcpu_ptr(addr)					\
+	(void __percpu *)((unsigned long)(addr) -			\
+			  (unsigned long)pcpu_base_addr	+		\
+			  (unsigned long)__per_cpu_start)
+#endif
+#ifndef __pcpu_ptr_to_addr
+#define __pcpu_ptr_to_addr(ptr)						\
+	(void __force *)((unsigned long)(ptr) +				\
+			 (unsigned long)pcpu_base_addr -		\
+			 (unsigned long)__per_cpu_start)
+#endif
+#else	/* CONFIG_SMP */
+/* on UP, it's always identity mapped */
+#define __addr_to_pcpu_ptr(addr)	(void __percpu *)(addr)
+#define __pcpu_ptr_to_addr(ptr)		(void __force *)(ptr)
+#endif	/* CONFIG_SMP */
+
+struct pcpu_chunk {
+	struct list_head	list;		/* linked to pcpu_slot lists */
+	int			free_size;	/* free bytes in the chunk */
+	int			contig_hint;	/* max contiguous size hint */
+	void			*base_addr;	/* base address of this chunk */
+
+	int			map_used;	/* # of map entries used before the sentry */
+	int			map_alloc;	/* # of map entries allocated */
+	int			*map;		/* allocation map */
+	struct list_head	map_extend_list;/* on pcpu_map_extend_chunks */
+
+	void			*data;		/* chunk data */
+	int			first_free;	/* no free below this */
+	bool			immutable;	/* no [de]population allowed */
+	int			nr_populated;	/* # of populated pages */
+	unsigned long		populated[];	/* populated bitmap */
+};
+
+static int pcpu_unit_pages __read_mostly;
+static int pcpu_unit_size __read_mostly;
+static int pcpu_nr_units __read_mostly;
+static int pcpu_atom_size __read_mostly;
+static int pcpu_nr_slots __read_mostly;
+static size_t pcpu_chunk_struct_size __read_mostly;
+
+/* cpus with the lowest and highest unit addresses */
+static unsigned int pcpu_low_unit_cpu __read_mostly;
+static unsigned int pcpu_high_unit_cpu __read_mostly;
+
+/* the address of the first chunk which starts with the kernel static area */
+void *pcpu_base_addr __read_mostly;
+EXPORT_SYMBOL_GPL(pcpu_base_addr);
+
+static const int *pcpu_unit_map __read_mostly;		/* cpu -> unit */
+const unsigned long *pcpu_unit_offsets __read_mostly;	/* cpu -> unit offset */
+
+/* group information, used for vm allocation */
+static int pcpu_nr_groups __read_mostly;
+static const unsigned long *pcpu_group_offsets __read_mostly;
+static const size_t *pcpu_group_sizes __read_mostly;
+
+/*
+ * The first chunk which always exists.  Note that unlike other
+ * chunks, this one can be allocated and mapped in several different
+ * ways and thus often doesn't live in the vmalloc area.
+ */
+static struct pcpu_chunk *pcpu_first_chunk;
+
+/*
+ * Optional reserved chunk.  This chunk reserves part of the first
+ * chunk and serves it for reserved allocations.  The amount of
+ * reserved offset is in pcpu_reserved_chunk_limit.  When reserved
+ * area doesn't exist, the following variables contain NULL and 0
+ * respectively.
+ */
+static struct pcpu_chunk *pcpu_reserved_chunk;
+static int pcpu_reserved_chunk_limit;
+
+static DEFINE_SPINLOCK(pcpu_lock);	/* all internal data structures */
+static DEFINE_MUTEX(pcpu_alloc_mutex);	/* chunk create/destroy, [de]pop, map ext */
+
+static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */
+
+/* chunks which need their map areas extended, protected by pcpu_lock */
+static LIST_HEAD(pcpu_map_extend_chunks);
+
+/*
+ * The number of empty populated pages, protected by pcpu_lock.  The
+ * reserved chunk doesn't contribute to the count.
+ */
+static int pcpu_nr_empty_pop_pages;
+
+/*
+ * Balance work is used to populate or destroy chunks asynchronously.  We
+ * try to keep the number of populated free pages between
+ * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
+ * empty chunk.
+ */
+static void pcpu_balance_workfn(struct work_struct *work);
+static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
+static bool pcpu_async_enabled __read_mostly;
+static bool pcpu_atomic_alloc_failed;
+
+static void pcpu_schedule_balance_work(void)
+{
+	if (pcpu_async_enabled)
+		schedule_work(&pcpu_balance_work);
+}
+
+static bool pcpu_addr_in_first_chunk(void *addr)
+{
+	void *first_start = pcpu_first_chunk->base_addr;
+
+	return addr >= first_start && addr < first_start + pcpu_unit_size;
+}
+
+static bool pcpu_addr_in_reserved_chunk(void *addr)
+{
+	void *first_start = pcpu_first_chunk->base_addr;
+
+	return addr >= first_start &&
+		addr < first_start + pcpu_reserved_chunk_limit;
+}
+
+static int __pcpu_size_to_slot(int size)
+{
+	int highbit = fls(size);	/* size is in bytes */
+	return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
+}
+
+static int pcpu_size_to_slot(int size)
+{
+	if (size == pcpu_unit_size)
+		return pcpu_nr_slots - 1;
+	return __pcpu_size_to_slot(size);
+}
+
+static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
+{
+	if (chunk->free_size < sizeof(int) || chunk->contig_hint < sizeof(int))
+		return 0;
+
+	return pcpu_size_to_slot(chunk->free_size);
+}
+
+/* set the pointer to a chunk in a page struct */
+static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
+{
+	page->index = (unsigned long)pcpu;
+}
+
+/* obtain pointer to a chunk from a page struct */
+static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
+{
+	return (struct pcpu_chunk *)page->index;
+}
+
+static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
+{
+	return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
+}
+
+static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
+				     unsigned int cpu, int page_idx)
+{
+	return (unsigned long)chunk->base_addr + pcpu_unit_offsets[cpu] +
+		(page_idx << PAGE_SHIFT);
+}
+
+static void __maybe_unused pcpu_next_unpop(struct pcpu_chunk *chunk,
+					   int *rs, int *re, int end)
+{
+	*rs = find_next_zero_bit(chunk->populated, end, *rs);
+	*re = find_next_bit(chunk->populated, end, *rs + 1);
+}
+
+static void __maybe_unused pcpu_next_pop(struct pcpu_chunk *chunk,
+					 int *rs, int *re, int end)
+{
+	*rs = find_next_bit(chunk->populated, end, *rs);
+	*re = find_next_zero_bit(chunk->populated, end, *rs + 1);
+}
+
+/*
+ * (Un)populated page region iterators.  Iterate over (un)populated
+ * page regions between @start and @end in @chunk.  @rs and @re should
+ * be integer variables and will be set to start and end page index of
+ * the current region.
+ */
+#define pcpu_for_each_unpop_region(chunk, rs, re, start, end)		    \
+	for ((rs) = (start), pcpu_next_unpop((chunk), &(rs), &(re), (end)); \
+	     (rs) < (re);						    \
+	     (rs) = (re) + 1, pcpu_next_unpop((chunk), &(rs), &(re), (end)))
+
+#define pcpu_for_each_pop_region(chunk, rs, re, start, end)		    \
+	for ((rs) = (start), pcpu_next_pop((chunk), &(rs), &(re), (end));   \
+	     (rs) < (re);						    \
+	     (rs) = (re) + 1, pcpu_next_pop((chunk), &(rs), &(re), (end)))
+
+/**
+ * pcpu_mem_zalloc - allocate memory
+ * @size: bytes to allocate
+ *
+ * Allocate @size bytes.  If @size is smaller than PAGE_SIZE,
+ * kzalloc() is used; otherwise, vzalloc() is used.  The returned
+ * memory is always zeroed.
+ *
+ * CONTEXT:
+ * Does GFP_KERNEL allocation.
+ *
+ * RETURNS:
+ * Pointer to the allocated area on success, NULL on failure.
+ */
+static void *pcpu_mem_zalloc(size_t size)
+{
+	if (WARN_ON_ONCE(!slab_is_available()))
+		return NULL;
+
+	if (size <= PAGE_SIZE)
+		return kzalloc(size, GFP_KERNEL);
+	else
+		return vzalloc(size);
+}
+
+/**
+ * pcpu_mem_free - free memory
+ * @ptr: memory to free
+ * @size: size of the area
+ *
+ * Free @ptr.  @ptr should have been allocated using pcpu_mem_zalloc().
+ */
+static void pcpu_mem_free(void *ptr, size_t size)
+{
+	if (size <= PAGE_SIZE)
+		kfree(ptr);
+	else
+		vfree(ptr);
+}
+
+/**
+ * pcpu_count_occupied_pages - count the number of pages an area occupies
+ * @chunk: chunk of interest
+ * @i: index of the area in question
+ *
+ * Count the number of pages chunk's @i'th area occupies.  When the area's
+ * start and/or end address isn't aligned to page boundary, the straddled
+ * page is included in the count iff the rest of the page is free.
+ */
+static int pcpu_count_occupied_pages(struct pcpu_chunk *chunk, int i)
+{
+	int off = chunk->map[i] & ~1;
+	int end = chunk->map[i + 1] & ~1;
+
+	if (!PAGE_ALIGNED(off) && i > 0) {
+		int prev = chunk->map[i - 1];
+
+		if (!(prev & 1) && prev <= round_down(off, PAGE_SIZE))
+			off = round_down(off, PAGE_SIZE);
+	}
+
+	if (!PAGE_ALIGNED(end) && i + 1 < chunk->map_used) {
+		int next = chunk->map[i + 1];
+		int nend = chunk->map[i + 2] & ~1;
+
+		if (!(next & 1) && nend >= round_up(end, PAGE_SIZE))
+			end = round_up(end, PAGE_SIZE);
+	}
+
+	return max_t(int, PFN_DOWN(end) - PFN_UP(off), 0);
+}
+
+/**
+ * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
+ * @chunk: chunk of interest
+ * @oslot: the previous slot it was on
+ *
+ * This function is called after an allocation or free changed @chunk.
+ * New slot according to the changed state is determined and @chunk is
+ * moved to the slot.  Note that the reserved chunk is never put on
+ * chunk slots.
+ *
+ * CONTEXT:
+ * pcpu_lock.
+ */
+static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
+{
+	int nslot = pcpu_chunk_slot(chunk);
+
+	if (chunk != pcpu_reserved_chunk && oslot != nslot) {
+		if (oslot < nslot)
+			list_move(&chunk->list, &pcpu_slot[nslot]);
+		else
+			list_move_tail(&chunk->list, &pcpu_slot[nslot]);
+	}
+}
+
+/**
+ * pcpu_need_to_extend - determine whether chunk area map needs to be extended
+ * @chunk: chunk of interest
+ * @is_atomic: the allocation context
+ *
+ * Determine whether area map of @chunk needs to be extended.  If
+ * @is_atomic, only the amount necessary for a new allocation is
+ * considered; however, async extension is scheduled if the left amount is
+ * low.  If !@is_atomic, it aims for more empty space.  Combined, this
+ * ensures that the map is likely to have enough available space to
+ * accomodate atomic allocations which can't extend maps directly.
+ *
+ * CONTEXT:
+ * pcpu_lock.
+ *
+ * RETURNS:
+ * New target map allocation length if extension is necessary, 0
+ * otherwise.
+ */
+static int pcpu_need_to_extend(struct pcpu_chunk *chunk, bool is_atomic)
+{
+	int margin, new_alloc;
+
+	lockdep_assert_held(&pcpu_lock);
+
+	if (is_atomic) {
+		margin = 3;
+
+		if (chunk->map_alloc <
+		    chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW) {
+			if (list_empty(&chunk->map_extend_list)) {
+				list_add_tail(&chunk->map_extend_list,
+					      &pcpu_map_extend_chunks);
+				pcpu_schedule_balance_work();
+			}
+		}
+	} else {
+		margin = PCPU_ATOMIC_MAP_MARGIN_HIGH;
+	}
+
+	if (chunk->map_alloc >= chunk->map_used + margin)
+		return 0;
+
+	new_alloc = PCPU_DFL_MAP_ALLOC;
+	while (new_alloc < chunk->map_used + margin)
+		new_alloc *= 2;
+
+	return new_alloc;
+}
+
+/**
+ * pcpu_extend_area_map - extend area map of a chunk
+ * @chunk: chunk of interest
+ * @new_alloc: new target allocation length of the area map
+ *
+ * Extend area map of @chunk to have @new_alloc entries.
+ *
+ * CONTEXT:
+ * Does GFP_KERNEL allocation.  Grabs and releases pcpu_lock.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
+{
+	int *old = NULL, *new = NULL;
+	size_t old_size = 0, new_size = new_alloc * sizeof(new[0]);
+	unsigned long flags;
+
+	lockdep_assert_held(&pcpu_alloc_mutex);
+
+	new = pcpu_mem_zalloc(new_size);
+	if (!new)
+		return -ENOMEM;
+
+	/* acquire pcpu_lock and switch to new area map */
+	spin_lock_irqsave(&pcpu_lock, flags);
+
+	if (new_alloc <= chunk->map_alloc)
+		goto out_unlock;
+
+	old_size = chunk->map_alloc * sizeof(chunk->map[0]);
+	old = chunk->map;
+
+	memcpy(new, old, old_size);
+
+	chunk->map_alloc = new_alloc;
+	chunk->map = new;
+	new = NULL;
+
+out_unlock:
+	spin_unlock_irqrestore(&pcpu_lock, flags);
+
+	/*
+	 * pcpu_mem_free() might end up calling vfree() which uses
+	 * IRQ-unsafe lock and thus can't be called under pcpu_lock.
+	 */
+	pcpu_mem_free(old, old_size);
+	pcpu_mem_free(new, new_size);
+
+	return 0;
+}
+
+/**
+ * pcpu_fit_in_area - try to fit the requested allocation in a candidate area
+ * @chunk: chunk the candidate area belongs to
+ * @off: the offset to the start of the candidate area
+ * @this_size: the size of the candidate area
+ * @size: the size of the target allocation
+ * @align: the alignment of the target allocation
+ * @pop_only: only allocate from already populated region
+ *
+ * We're trying to allocate @size bytes aligned at @align.  @chunk's area
+ * at @off sized @this_size is a candidate.  This function determines
+ * whether the target allocation fits in the candidate area and returns the
+ * number of bytes to pad after @off.  If the target area doesn't fit, -1
+ * is returned.
+ *
+ * If @pop_only is %true, this function only considers the already
+ * populated part of the candidate area.
+ */
+static int pcpu_fit_in_area(struct pcpu_chunk *chunk, int off, int this_size,
+			    int size, int align, bool pop_only)
+{
+	int cand_off = off;
+
+	while (true) {
+		int head = ALIGN(cand_off, align) - off;
+		int page_start, page_end, rs, re;
+
+		if (this_size < head + size)
+			return -1;
+
+		if (!pop_only)
+			return head;
+
+		/*
+		 * If the first unpopulated page is beyond the end of the
+		 * allocation, the whole allocation is populated;
+		 * otherwise, retry from the end of the unpopulated area.
+		 */
+		page_start = PFN_DOWN(head + off);
+		page_end = PFN_UP(head + off + size);
+
+		rs = page_start;
+		pcpu_next_unpop(chunk, &rs, &re, PFN_UP(off + this_size));
+		if (rs >= page_end)
+			return head;
+		cand_off = re * PAGE_SIZE;
+	}
+}
+
+/**
+ * pcpu_alloc_area - allocate area from a pcpu_chunk
+ * @chunk: chunk of interest
+ * @size: wanted size in bytes
+ * @align: wanted align
+ * @pop_only: allocate only from the populated area
+ * @occ_pages_p: out param for the number of pages the area occupies
+ *
+ * Try to allocate @size bytes area aligned at @align from @chunk.
+ * Note that this function only allocates the offset.  It doesn't
+ * populate or map the area.
+ *
+ * @chunk->map must have at least two free slots.
+ *
+ * CONTEXT:
+ * pcpu_lock.
+ *
+ * RETURNS:
+ * Allocated offset in @chunk on success, -1 if no matching area is
+ * found.
+ */
+static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align,
+			   bool pop_only, int *occ_pages_p)
+{
+	int oslot = pcpu_chunk_slot(chunk);
+	int max_contig = 0;
+	int i, off;
+	bool seen_free = false;
+	int *p;
+
+	for (i = chunk->first_free, p = chunk->map + i; i < chunk->map_used; i++, p++) {
+		int head, tail;
+		int this_size;
+
+		off = *p;
+		if (off & 1)
+			continue;
+
+		this_size = (p[1] & ~1) - off;
+
+		head = pcpu_fit_in_area(chunk, off, this_size, size, align,
+					pop_only);
+		if (head < 0) {
+			if (!seen_free) {
+				chunk->first_free = i;
+				seen_free = true;
+			}
+			max_contig = max(this_size, max_contig);
+			continue;
+		}
+
+		/*
+		 * If head is small or the previous block is free,
+		 * merge'em.  Note that 'small' is defined as smaller
+		 * than sizeof(int), which is very small but isn't too
+		 * uncommon for percpu allocations.
+		 */
+		if (head && (head < sizeof(int) || !(p[-1] & 1))) {
+			*p = off += head;
+			if (p[-1] & 1)
+				chunk->free_size -= head;
+			else
+				max_contig = max(*p - p[-1], max_contig);
+			this_size -= head;
+			head = 0;
+		}
+
+		/* if tail is small, just keep it around */
+		tail = this_size - head - size;
+		if (tail < sizeof(int)) {
+			tail = 0;
+			size = this_size - head;
+		}
+
+		/* split if warranted */
+		if (head || tail) {
+			int nr_extra = !!head + !!tail;
+
+			/* insert new subblocks */
+			memmove(p + nr_extra + 1, p + 1,
+				sizeof(chunk->map[0]) * (chunk->map_used - i));
+			chunk->map_used += nr_extra;
+
+			if (head) {
+				if (!seen_free) {
+					chunk->first_free = i;
+					seen_free = true;
+				}
+				*++p = off += head;
+				++i;
+				max_contig = max(head, max_contig);
+			}
+			if (tail) {
+				p[1] = off + size;
+				max_contig = max(tail, max_contig);
+			}
+		}
+
+		if (!seen_free)
+			chunk->first_free = i + 1;
+
+		/* update hint and mark allocated */
+		if (i + 1 == chunk->map_used)
+			chunk->contig_hint = max_contig; /* fully scanned */
+		else
+			chunk->contig_hint = max(chunk->contig_hint,
+						 max_contig);
+
+		chunk->free_size -= size;
+		*p |= 1;
+
+		*occ_pages_p = pcpu_count_occupied_pages(chunk, i);
+		pcpu_chunk_relocate(chunk, oslot);
+		return off;
+	}
+
+	chunk->contig_hint = max_contig;	/* fully scanned */
+	pcpu_chunk_relocate(chunk, oslot);
+
+	/* tell the upper layer that this chunk has no matching area */
+	return -1;
+}
+
+/**
+ * pcpu_free_area - free area to a pcpu_chunk
+ * @chunk: chunk of interest
+ * @freeme: offset of area to free
+ * @occ_pages_p: out param for the number of pages the area occupies
+ *
+ * Free area starting from @freeme to @chunk.  Note that this function
+ * only modifies the allocation map.  It doesn't depopulate or unmap
+ * the area.
+ *
+ * CONTEXT:
+ * pcpu_lock.
+ */
+static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme,
+			   int *occ_pages_p)
+{
+	int oslot = pcpu_chunk_slot(chunk);
+	int off = 0;
+	unsigned i, j;
+	int to_free = 0;
+	int *p;
+
+	freeme |= 1;	/* we are searching for <given offset, in use> pair */
+
+	i = 0;
+	j = chunk->map_used;
+	while (i != j) {
+		unsigned k = (i + j) / 2;
+		off = chunk->map[k];
+		if (off < freeme)
+			i = k + 1;
+		else if (off > freeme)
+			j = k;
+		else
+			i = j = k;
+	}
+	BUG_ON(off != freeme);
+
+	if (i < chunk->first_free)
+		chunk->first_free = i;
+
+	p = chunk->map + i;
+	*p = off &= ~1;
+	chunk->free_size += (p[1] & ~1) - off;
+
+	*occ_pages_p = pcpu_count_occupied_pages(chunk, i);
+
+	/* merge with next? */
+	if (!(p[1] & 1))
+		to_free++;
+	/* merge with previous? */
+	if (i > 0 && !(p[-1] & 1)) {
+		to_free++;
+		i--;
+		p--;
+	}
+	if (to_free) {
+		chunk->map_used -= to_free;
+		memmove(p + 1, p + 1 + to_free,
+			(chunk->map_used - i) * sizeof(chunk->map[0]));
+	}
+
+	chunk->contig_hint = max(chunk->map[i + 1] - chunk->map[i] - 1, chunk->contig_hint);
+	pcpu_chunk_relocate(chunk, oslot);
+}
+
+static struct pcpu_chunk *pcpu_alloc_chunk(void)
+{
+	struct pcpu_chunk *chunk;
+
+	chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size);
+	if (!chunk)
+		return NULL;
+
+	chunk->map = pcpu_mem_zalloc(PCPU_DFL_MAP_ALLOC *
+						sizeof(chunk->map[0]));
+	if (!chunk->map) {
+		pcpu_mem_free(chunk, pcpu_chunk_struct_size);
+		return NULL;
+	}
+
+	chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
+	chunk->map[0] = 0;
+	chunk->map[1] = pcpu_unit_size | 1;
+	chunk->map_used = 1;
+
+	INIT_LIST_HEAD(&chunk->list);
+	INIT_LIST_HEAD(&chunk->map_extend_list);
+	chunk->free_size = pcpu_unit_size;
+	chunk->contig_hint = pcpu_unit_size;
+
+	return chunk;
+}
+
+static void pcpu_free_chunk(struct pcpu_chunk *chunk)
+{
+	if (!chunk)
+		return;
+	pcpu_mem_free(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]));
+	pcpu_mem_free(chunk, pcpu_chunk_struct_size);
+}
+
+/**
+ * pcpu_chunk_populated - post-population bookkeeping
+ * @chunk: pcpu_chunk which got populated
+ * @page_start: the start page
+ * @page_end: the end page
+ *
+ * Pages in [@page_start,@page_end) have been populated to @chunk.  Update
+ * the bookkeeping information accordingly.  Must be called after each
+ * successful population.
+ */
+static void pcpu_chunk_populated(struct pcpu_chunk *chunk,
+				 int page_start, int page_end)
+{
+	int nr = page_end - page_start;
+
+	lockdep_assert_held(&pcpu_lock);
+
+	bitmap_set(chunk->populated, page_start, nr);
+	chunk->nr_populated += nr;
+	pcpu_nr_empty_pop_pages += nr;
+}
+
+/**
+ * pcpu_chunk_depopulated - post-depopulation bookkeeping
+ * @chunk: pcpu_chunk which got depopulated
+ * @page_start: the start page
+ * @page_end: the end page
+ *
+ * Pages in [@page_start,@page_end) have been depopulated from @chunk.
+ * Update the bookkeeping information accordingly.  Must be called after
+ * each successful depopulation.
+ */
+static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
+				   int page_start, int page_end)
+{
+	int nr = page_end - page_start;
+
+	lockdep_assert_held(&pcpu_lock);
+
+	bitmap_clear(chunk->populated, page_start, nr);
+	chunk->nr_populated -= nr;
+	pcpu_nr_empty_pop_pages -= nr;
+}
+
+/*
+ * Chunk management implementation.
+ *
+ * To allow different implementations, chunk alloc/free and
+ * [de]population are implemented in a separate file which is pulled
+ * into this file and compiled together.  The following functions
+ * should be implemented.
+ *
+ * pcpu_populate_chunk		- populate the specified range of a chunk
+ * pcpu_depopulate_chunk	- depopulate the specified range of a chunk
+ * pcpu_create_chunk		- create a new chunk
+ * pcpu_destroy_chunk		- destroy a chunk, always preceded by full depop
+ * pcpu_addr_to_page		- translate address to physical address
+ * pcpu_verify_alloc_info	- check alloc_info is acceptable during init
+ */
+static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size);
+static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size);
+static struct pcpu_chunk *pcpu_create_chunk(void);
+static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
+static struct page *pcpu_addr_to_page(void *addr);
+static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
+
+#ifdef CONFIG_NEED_PER_CPU_KM
+#include "percpu-km.c"
+#else
+#include "percpu-vm.c"
+#endif
+
+/**
+ * pcpu_chunk_addr_search - determine chunk containing specified address
+ * @addr: address for which the chunk needs to be determined.
+ *
+ * RETURNS:
+ * The address of the found chunk.
+ */
+static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
+{
+	/* is it in the first chunk? */
+	if (pcpu_addr_in_first_chunk(addr)) {
+		/* is it in the reserved area? */
+		if (pcpu_addr_in_reserved_chunk(addr))
+			return pcpu_reserved_chunk;
+		return pcpu_first_chunk;
+	}
+
+	/*
+	 * The address is relative to unit0 which might be unused and
+	 * thus unmapped.  Offset the address to the unit space of the
+	 * current processor before looking it up in the vmalloc
+	 * space.  Note that any possible cpu id can be used here, so
+	 * there's no need to worry about preemption or cpu hotplug.
+	 */
+	addr += pcpu_unit_offsets[raw_smp_processor_id()];
+	return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
+}
+
+/**
+ * pcpu_alloc - the percpu allocator
+ * @size: size of area to allocate in bytes
+ * @align: alignment of area (max PAGE_SIZE)
+ * @reserved: allocate from the reserved chunk if available
+ * @gfp: allocation flags
+ *
+ * Allocate percpu area of @size bytes aligned at @align.  If @gfp doesn't
+ * contain %GFP_KERNEL, the allocation is atomic.
+ *
+ * RETURNS:
+ * Percpu pointer to the allocated area on success, NULL on failure.
+ */
+static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
+				 gfp_t gfp)
+{
+	static int warn_limit = 10;
+	struct pcpu_chunk *chunk;
+	const char *err;
+	bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
+	int occ_pages = 0;
+	int slot, off, new_alloc, cpu, ret;
+	unsigned long flags;
+	void __percpu *ptr;
+
+	/*
+	 * We want the lowest bit of offset available for in-use/free
+	 * indicator, so force >= 16bit alignment and make size even.
+	 */
+	if (unlikely(align < 2))
+		align = 2;
+
+	size = ALIGN(size, 2);
+
+	if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
+		WARN(true, "illegal size (%zu) or align (%zu) for "
+		     "percpu allocation\n", size, align);
+		return NULL;
+	}
+
+	if (!is_atomic)
+		mutex_lock(&pcpu_alloc_mutex);
+
+	spin_lock_irqsave(&pcpu_lock, flags);
+
+	/* serve reserved allocations from the reserved chunk if available */
+	if (reserved && pcpu_reserved_chunk) {
+		chunk = pcpu_reserved_chunk;
+
+		if (size > chunk->contig_hint) {
+			err = "alloc from reserved chunk failed";
+			goto fail_unlock;
+		}
+
+		while ((new_alloc = pcpu_need_to_extend(chunk, is_atomic))) {
+			spin_unlock_irqrestore(&pcpu_lock, flags);
+			if (is_atomic ||
+			    pcpu_extend_area_map(chunk, new_alloc) < 0) {
+				err = "failed to extend area map of reserved chunk";
+				goto fail;
+			}
+			spin_lock_irqsave(&pcpu_lock, flags);
+		}
+
+		off = pcpu_alloc_area(chunk, size, align, is_atomic,
+				      &occ_pages);
+		if (off >= 0)
+			goto area_found;
+
+		err = "alloc from reserved chunk failed";
+		goto fail_unlock;
+	}
+
+restart:
+	/* search through normal chunks */
+	for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
+		list_for_each_entry(chunk, &pcpu_slot[slot], list) {
+			if (size > chunk->contig_hint)
+				continue;
+
+			new_alloc = pcpu_need_to_extend(chunk, is_atomic);
+			if (new_alloc) {
+				if (is_atomic)
+					continue;
+				spin_unlock_irqrestore(&pcpu_lock, flags);
+				if (pcpu_extend_area_map(chunk,
+							 new_alloc) < 0) {
+					err = "failed to extend area map";
+					goto fail;
+				}
+				spin_lock_irqsave(&pcpu_lock, flags);
+				/*
+				 * pcpu_lock has been dropped, need to
+				 * restart cpu_slot list walking.
+				 */
+				goto restart;
+			}
+
+			off = pcpu_alloc_area(chunk, size, align, is_atomic,
+					      &occ_pages);
+			if (off >= 0)
+				goto area_found;
+		}
+	}
+
+	spin_unlock_irqrestore(&pcpu_lock, flags);
+
+	/*
+	 * No space left.  Create a new chunk.  We don't want multiple
+	 * tasks to create chunks simultaneously.  Serialize and create iff
+	 * there's still no empty chunk after grabbing the mutex.
+	 */
+	if (is_atomic)
+		goto fail;
+
+	if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
+		chunk = pcpu_create_chunk();
+		if (!chunk) {
+			err = "failed to allocate new chunk";
+			goto fail;
+		}
+
+		spin_lock_irqsave(&pcpu_lock, flags);
+		pcpu_chunk_relocate(chunk, -1);
+	} else {
+		spin_lock_irqsave(&pcpu_lock, flags);
+	}
+
+	goto restart;
+
+area_found:
+	spin_unlock_irqrestore(&pcpu_lock, flags);
+
+	/* populate if not all pages are already there */
+	if (!is_atomic) {
+		int page_start, page_end, rs, re;
+
+		page_start = PFN_DOWN(off);
+		page_end = PFN_UP(off + size);
+
+		pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
+			WARN_ON(chunk->immutable);
+
+			ret = pcpu_populate_chunk(chunk, rs, re);
+
+			spin_lock_irqsave(&pcpu_lock, flags);
+			if (ret) {
+				pcpu_free_area(chunk, off, &occ_pages);
+				err = "failed to populate";
+				goto fail_unlock;
+			}
+			pcpu_chunk_populated(chunk, rs, re);
+			spin_unlock_irqrestore(&pcpu_lock, flags);
+		}
+
+		mutex_unlock(&pcpu_alloc_mutex);
+	}
+
+	if (chunk != pcpu_reserved_chunk) {
+		spin_lock_irqsave(&pcpu_lock, flags);
+		pcpu_nr_empty_pop_pages -= occ_pages;
+		spin_unlock_irqrestore(&pcpu_lock, flags);
+	}
+
+	if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
+		pcpu_schedule_balance_work();
+
+	/* clear the areas and return address relative to base address */
+	for_each_possible_cpu(cpu)
+		memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
+
+	ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
+	kmemleak_alloc_percpu(ptr, size, gfp);
+	return ptr;
+
+fail_unlock:
+	spin_unlock_irqrestore(&pcpu_lock, flags);
+fail:
+	if (!is_atomic && warn_limit) {
+		pr_warning("PERCPU: allocation failed, size=%zu align=%zu atomic=%d, %s\n",
+			   size, align, is_atomic, err);
+		dump_stack();
+		if (!--warn_limit)
+			pr_info("PERCPU: limit reached, disable warning\n");
+	}
+	if (is_atomic) {
+		/* see the flag handling in pcpu_blance_workfn() */
+		pcpu_atomic_alloc_failed = true;
+		pcpu_schedule_balance_work();
+	} else {
+		mutex_unlock(&pcpu_alloc_mutex);
+	}
+	return NULL;
+}
+
+/**
+ * __alloc_percpu_gfp - allocate dynamic percpu area
+ * @size: size of area to allocate in bytes
+ * @align: alignment of area (max PAGE_SIZE)
+ * @gfp: allocation flags
+ *
+ * Allocate zero-filled percpu area of @size bytes aligned at @align.  If
+ * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
+ * be called from any context but is a lot more likely to fail.
+ *
+ * RETURNS:
+ * Percpu pointer to the allocated area on success, NULL on failure.
+ */
+void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
+{
+	return pcpu_alloc(size, align, false, gfp);
+}
+EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
+
+/**
+ * __alloc_percpu - allocate dynamic percpu area
+ * @size: size of area to allocate in bytes
+ * @align: alignment of area (max PAGE_SIZE)
+ *
+ * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
+ */
+void __percpu *__alloc_percpu(size_t size, size_t align)
+{
+	return pcpu_alloc(size, align, false, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(__alloc_percpu);
+
+/**
+ * __alloc_reserved_percpu - allocate reserved percpu area
+ * @size: size of area to allocate in bytes
+ * @align: alignment of area (max PAGE_SIZE)
+ *
+ * Allocate zero-filled percpu area of @size bytes aligned at @align
+ * from reserved percpu area if arch has set it up; otherwise,
+ * allocation is served from the same dynamic area.  Might sleep.
+ * Might trigger writeouts.
+ *
+ * CONTEXT:
+ * Does GFP_KERNEL allocation.
+ *
+ * RETURNS:
+ * Percpu pointer to the allocated area on success, NULL on failure.
+ */
+void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
+{
+	return pcpu_alloc(size, align, true, GFP_KERNEL);
+}
+
+/**
+ * pcpu_balance_workfn - manage the amount of free chunks and populated pages
+ * @work: unused
+ *
+ * Reclaim all fully free chunks except for the first one.
+ */
+static void pcpu_balance_workfn(struct work_struct *work)
+{
+	LIST_HEAD(to_free);
+	struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
+	struct pcpu_chunk *chunk, *next;
+	int slot, nr_to_pop, ret;
+
+	/*
+	 * There's no reason to keep around multiple unused chunks and VM
+	 * areas can be scarce.  Destroy all free chunks except for one.
+	 */
+	mutex_lock(&pcpu_alloc_mutex);
+	spin_lock_irq(&pcpu_lock);
+
+	list_for_each_entry_safe(chunk, next, free_head, list) {
+		WARN_ON(chunk->immutable);
+
+		/* spare the first one */
+		if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
+			continue;
+
+		list_del_init(&chunk->map_extend_list);
+		list_move(&chunk->list, &to_free);
+	}
+
+	spin_unlock_irq(&pcpu_lock);
+
+	list_for_each_entry_safe(chunk, next, &to_free, list) {
+		int rs, re;
+
+		pcpu_for_each_pop_region(chunk, rs, re, 0, pcpu_unit_pages) {
+			pcpu_depopulate_chunk(chunk, rs, re);
+			spin_lock_irq(&pcpu_lock);
+			pcpu_chunk_depopulated(chunk, rs, re);
+			spin_unlock_irq(&pcpu_lock);
+		}
+		pcpu_destroy_chunk(chunk);
+	}
+
+	/* service chunks which requested async area map extension */
+	do {
+		int new_alloc = 0;
+
+		spin_lock_irq(&pcpu_lock);
+
+		chunk = list_first_entry_or_null(&pcpu_map_extend_chunks,
+					struct pcpu_chunk, map_extend_list);
+		if (chunk) {
+			list_del_init(&chunk->map_extend_list);
+			new_alloc = pcpu_need_to_extend(chunk, false);
+		}
+
+		spin_unlock_irq(&pcpu_lock);
+
+		if (new_alloc)
+			pcpu_extend_area_map(chunk, new_alloc);
+	} while (chunk);
+
+	/*
+	 * Ensure there are certain number of free populated pages for
+	 * atomic allocs.  Fill up from the most packed so that atomic
+	 * allocs don't increase fragmentation.  If atomic allocation
+	 * failed previously, always populate the maximum amount.  This
+	 * should prevent atomic allocs larger than PAGE_SIZE from keeping
+	 * failing indefinitely; however, large atomic allocs are not
+	 * something we support properly and can be highly unreliable and
+	 * inefficient.
+	 */
+retry_pop:
+	if (pcpu_atomic_alloc_failed) {
+		nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
+		/* best effort anyway, don't worry about synchronization */
+		pcpu_atomic_alloc_failed = false;
+	} else {
+		nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
+				  pcpu_nr_empty_pop_pages,
+				  0, PCPU_EMPTY_POP_PAGES_HIGH);
+	}
+
+	for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) {
+		int nr_unpop = 0, rs, re;
+
+		if (!nr_to_pop)
+			break;
+
+		spin_lock_irq(&pcpu_lock);
+		list_for_each_entry(chunk, &pcpu_slot[slot], list) {
+			nr_unpop = pcpu_unit_pages - chunk->nr_populated;
+			if (nr_unpop)
+				break;
+		}
+		spin_unlock_irq(&pcpu_lock);
+
+		if (!nr_unpop)
+			continue;
+
+		/* @chunk can't go away while pcpu_alloc_mutex is held */
+		pcpu_for_each_unpop_region(chunk, rs, re, 0, pcpu_unit_pages) {
+			int nr = min(re - rs, nr_to_pop);
+
+			ret = pcpu_populate_chunk(chunk, rs, rs + nr);
+			if (!ret) {
+				nr_to_pop -= nr;
+				spin_lock_irq(&pcpu_lock);
+				pcpu_chunk_populated(chunk, rs, rs + nr);
+				spin_unlock_irq(&pcpu_lock);
+			} else {
+				nr_to_pop = 0;
+			}
+
+			if (!nr_to_pop)
+				break;
+		}
+	}
+
+	if (nr_to_pop) {
+		/* ran out of chunks to populate, create a new one and retry */
+		chunk = pcpu_create_chunk();
+		if (chunk) {
+			spin_lock_irq(&pcpu_lock);
+			pcpu_chunk_relocate(chunk, -1);
+			spin_unlock_irq(&pcpu_lock);
+			goto retry_pop;
+		}
+	}
+
+	mutex_unlock(&pcpu_alloc_mutex);
+}
+
+/**
+ * free_percpu - free percpu area
+ * @ptr: pointer to area to free
+ *
+ * Free percpu area @ptr.
+ *
+ * CONTEXT:
+ * Can be called from atomic context.
+ */
+void free_percpu(void __percpu *ptr)
+{
+	void *addr;
+	struct pcpu_chunk *chunk;
+	unsigned long flags;
+	int off, occ_pages;
+
+	if (!ptr)
+		return;
+
+	kmemleak_free_percpu(ptr);
+
+	addr = __pcpu_ptr_to_addr(ptr);
+
+	spin_lock_irqsave(&pcpu_lock, flags);
+
+	chunk = pcpu_chunk_addr_search(addr);
+	off = addr - chunk->base_addr;
+
+	pcpu_free_area(chunk, off, &occ_pages);
+
+	if (chunk != pcpu_reserved_chunk)
+		pcpu_nr_empty_pop_pages += occ_pages;
+
+	/* if there are more than one fully free chunks, wake up grim reaper */
+	if (chunk->free_size == pcpu_unit_size) {
+		struct pcpu_chunk *pos;
+
+		list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
+			if (pos != chunk) {
+				pcpu_schedule_balance_work();
+				break;
+			}
+	}
+
+	spin_unlock_irqrestore(&pcpu_lock, flags);
+}
+EXPORT_SYMBOL_GPL(free_percpu);
+
+/**
+ * is_kernel_percpu_address - test whether address is from static percpu area
+ * @addr: address to test
+ *
+ * Test whether @addr belongs to in-kernel static percpu area.  Module
+ * static percpu areas are not considered.  For those, use
+ * is_module_percpu_address().
+ *
+ * RETURNS:
+ * %true if @addr is from in-kernel static percpu area, %false otherwise.
+ */
+bool is_kernel_percpu_address(unsigned long addr)
+{
+#ifdef CONFIG_SMP
+	const size_t static_size = __per_cpu_end - __per_cpu_start;
+	void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
+	unsigned int cpu;
+
+	for_each_possible_cpu(cpu) {
+		void *start = per_cpu_ptr(base, cpu);
+
+		if ((void *)addr >= start && (void *)addr < start + static_size)
+			return true;
+        }
+#endif
+	/* on UP, can't distinguish from other static vars, always false */
+	return false;
+}
+
+/**
+ * per_cpu_ptr_to_phys - convert translated percpu address to physical address
+ * @addr: the address to be converted to physical address
+ *
+ * Given @addr which is dereferenceable address obtained via one of
+ * percpu access macros, this function translates it into its physical
+ * address.  The caller is responsible for ensuring @addr stays valid
+ * until this function finishes.
+ *
+ * percpu allocator has special setup for the first chunk, which currently
+ * supports either embedding in linear address space or vmalloc mapping,
+ * and, from the second one, the backing allocator (currently either vm or
+ * km) provides translation.
+ *
+ * The addr can be translated simply without checking if it falls into the
+ * first chunk. But the current code reflects better how percpu allocator
+ * actually works, and the verification can discover both bugs in percpu
+ * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
+ * code.
+ *
+ * RETURNS:
+ * The physical address for @addr.
+ */
+phys_addr_t per_cpu_ptr_to_phys(void *addr)
+{
+	void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
+	bool in_first_chunk = false;
+	unsigned long first_low, first_high;
+	unsigned int cpu;
+
+	/*
+	 * The following test on unit_low/high isn't strictly
+	 * necessary but will speed up lookups of addresses which
+	 * aren't in the first chunk.
+	 */
+	first_low = pcpu_chunk_addr(pcpu_first_chunk, pcpu_low_unit_cpu, 0);
+	first_high = pcpu_chunk_addr(pcpu_first_chunk, pcpu_high_unit_cpu,
+				     pcpu_unit_pages);
+	if ((unsigned long)addr >= first_low &&
+	    (unsigned long)addr < first_high) {
+		for_each_possible_cpu(cpu) {
+			void *start = per_cpu_ptr(base, cpu);
+
+			if (addr >= start && addr < start + pcpu_unit_size) {
+				in_first_chunk = true;
+				break;
+			}
+		}
+	}
+
+	if (in_first_chunk) {
+		if (!is_vmalloc_addr(addr))
+			return __pa(addr);
+		else
+			return page_to_phys(vmalloc_to_page(addr)) +
+			       offset_in_page(addr);
+	} else
+		return page_to_phys(pcpu_addr_to_page(addr)) +
+		       offset_in_page(addr);
+}
+
+/**
+ * pcpu_alloc_alloc_info - allocate percpu allocation info
+ * @nr_groups: the number of groups
+ * @nr_units: the number of units
+ *
+ * Allocate ai which is large enough for @nr_groups groups containing
+ * @nr_units units.  The returned ai's groups[0].cpu_map points to the
+ * cpu_map array which is long enough for @nr_units and filled with
+ * NR_CPUS.  It's the caller's responsibility to initialize cpu_map
+ * pointer of other groups.
+ *
+ * RETURNS:
+ * Pointer to the allocated pcpu_alloc_info on success, NULL on
+ * failure.
+ */
+struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
+						      int nr_units)
+{
+	struct pcpu_alloc_info *ai;
+	size_t base_size, ai_size;
+	void *ptr;
+	int unit;
+
+	base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]),
+			  __alignof__(ai->groups[0].cpu_map[0]));
+	ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
+
+	ptr = memblock_virt_alloc_nopanic(PFN_ALIGN(ai_size), 0);
+	if (!ptr)
+		return NULL;
+	ai = ptr;
+	ptr += base_size;
+
+	ai->groups[0].cpu_map = ptr;
+
+	for (unit = 0; unit < nr_units; unit++)
+		ai->groups[0].cpu_map[unit] = NR_CPUS;
+
+	ai->nr_groups = nr_groups;
+	ai->__ai_size = PFN_ALIGN(ai_size);
+
+	return ai;
+}
+
+/**
+ * pcpu_free_alloc_info - free percpu allocation info
+ * @ai: pcpu_alloc_info to free
+ *
+ * Free @ai which was allocated by pcpu_alloc_alloc_info().
+ */
+void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
+{
+	memblock_free_early(__pa(ai), ai->__ai_size);
+}
+
+/**
+ * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
+ * @lvl: loglevel
+ * @ai: allocation info to dump
+ *
+ * Print out information about @ai using loglevel @lvl.
+ */
+static void pcpu_dump_alloc_info(const char *lvl,
+				 const struct pcpu_alloc_info *ai)
+{
+	int group_width = 1, cpu_width = 1, width;
+	char empty_str[] = "--------";
+	int alloc = 0, alloc_end = 0;
+	int group, v;
+	int upa, apl;	/* units per alloc, allocs per line */
+
+	v = ai->nr_groups;
+	while (v /= 10)
+		group_width++;
+
+	v = num_possible_cpus();
+	while (v /= 10)
+		cpu_width++;
+	empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
+
+	upa = ai->alloc_size / ai->unit_size;
+	width = upa * (cpu_width + 1) + group_width + 3;
+	apl = rounddown_pow_of_two(max(60 / width, 1));
+
+	printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
+	       lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
+	       ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
+
+	for (group = 0; group < ai->nr_groups; group++) {
+		const struct pcpu_group_info *gi = &ai->groups[group];
+		int unit = 0, unit_end = 0;
+
+		BUG_ON(gi->nr_units % upa);
+		for (alloc_end += gi->nr_units / upa;
+		     alloc < alloc_end; alloc++) {
+			if (!(alloc % apl)) {
+				printk(KERN_CONT "\n");
+				printk("%spcpu-alloc: ", lvl);
+			}
+			printk(KERN_CONT "[%0*d] ", group_width, group);
+
+			for (unit_end += upa; unit < unit_end; unit++)
+				if (gi->cpu_map[unit] != NR_CPUS)
+					printk(KERN_CONT "%0*d ", cpu_width,
+					       gi->cpu_map[unit]);
+				else
+					printk(KERN_CONT "%s ", empty_str);
+		}
+	}
+	printk(KERN_CONT "\n");
+}
+
+/**
+ * pcpu_setup_first_chunk - initialize the first percpu chunk
+ * @ai: pcpu_alloc_info describing how to percpu area is shaped
+ * @base_addr: mapped address
+ *
+ * Initialize the first percpu chunk which contains the kernel static
+ * perpcu area.  This function is to be called from arch percpu area
+ * setup path.
+ *
+ * @ai contains all information necessary to initialize the first
+ * chunk and prime the dynamic percpu allocator.
+ *
+ * @ai->static_size is the size of static percpu area.
+ *
+ * @ai->reserved_size, if non-zero, specifies the amount of bytes to
+ * reserve after the static area in the first chunk.  This reserves
+ * the first chunk such that it's available only through reserved
+ * percpu allocation.  This is primarily used to serve module percpu
+ * static areas on architectures where the addressing model has
+ * limited offset range for symbol relocations to guarantee module
+ * percpu symbols fall inside the relocatable range.
+ *
+ * @ai->dyn_size determines the number of bytes available for dynamic
+ * allocation in the first chunk.  The area between @ai->static_size +
+ * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
+ *
+ * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
+ * and equal to or larger than @ai->static_size + @ai->reserved_size +
+ * @ai->dyn_size.
+ *
+ * @ai->atom_size is the allocation atom size and used as alignment
+ * for vm areas.
+ *
+ * @ai->alloc_size is the allocation size and always multiple of
+ * @ai->atom_size.  This is larger than @ai->atom_size if
+ * @ai->unit_size is larger than @ai->atom_size.
+ *
+ * @ai->nr_groups and @ai->groups describe virtual memory layout of
+ * percpu areas.  Units which should be colocated are put into the
+ * same group.  Dynamic VM areas will be allocated according to these
+ * groupings.  If @ai->nr_groups is zero, a single group containing
+ * all units is assumed.
+ *
+ * The caller should have mapped the first chunk at @base_addr and
+ * copied static data to each unit.
+ *
+ * If the first chunk ends up with both reserved and dynamic areas, it
+ * is served by two chunks - one to serve the core static and reserved
+ * areas and the other for the dynamic area.  They share the same vm
+ * and page map but uses different area allocation map to stay away
+ * from each other.  The latter chunk is circulated in the chunk slots
+ * and available for dynamic allocation like any other chunks.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
+				  void *base_addr)
+{
+	static int smap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
+	static int dmap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
+	size_t dyn_size = ai->dyn_size;
+	size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
+	struct pcpu_chunk *schunk, *dchunk = NULL;
+	unsigned long *group_offsets;
+	size_t *group_sizes;
+	unsigned long *unit_off;
+	unsigned int cpu;
+	int *unit_map;
+	int group, unit, i;
+
+#define PCPU_SETUP_BUG_ON(cond)	do {					\
+	if (unlikely(cond)) {						\
+		pr_emerg("PERCPU: failed to initialize, %s", #cond);	\
+		pr_emerg("PERCPU: cpu_possible_mask=%*pb\n",		\
+			 cpumask_pr_args(cpu_possible_mask));		\
+		pcpu_dump_alloc_info(KERN_EMERG, ai);			\
+		BUG();							\
+	}								\
+} while (0)
+
+	/* sanity checks */
+	PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
+#ifdef CONFIG_SMP
+	PCPU_SETUP_BUG_ON(!ai->static_size);
+	PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
+#endif
+	PCPU_SETUP_BUG_ON(!base_addr);
+	PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
+	PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
+	PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
+	PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
+	PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
+	PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
+
+	/* process group information and build config tables accordingly */
+	group_offsets = memblock_virt_alloc(ai->nr_groups *
+					     sizeof(group_offsets[0]), 0);
+	group_sizes = memblock_virt_alloc(ai->nr_groups *
+					   sizeof(group_sizes[0]), 0);
+	unit_map = memblock_virt_alloc(nr_cpu_ids * sizeof(unit_map[0]), 0);
+	unit_off = memblock_virt_alloc(nr_cpu_ids * sizeof(unit_off[0]), 0);
+
+	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
+		unit_map[cpu] = UINT_MAX;
+
+	pcpu_low_unit_cpu = NR_CPUS;
+	pcpu_high_unit_cpu = NR_CPUS;
+
+	for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
+		const struct pcpu_group_info *gi = &ai->groups[group];
+
+		group_offsets[group] = gi->base_offset;
+		group_sizes[group] = gi->nr_units * ai->unit_size;
+
+		for (i = 0; i < gi->nr_units; i++) {
+			cpu = gi->cpu_map[i];
+			if (cpu == NR_CPUS)
+				continue;
+
+			PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
+			PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
+			PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
+
+			unit_map[cpu] = unit + i;
+			unit_off[cpu] = gi->base_offset + i * ai->unit_size;
+
+			/* determine low/high unit_cpu */
+			if (pcpu_low_unit_cpu == NR_CPUS ||
+			    unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
+				pcpu_low_unit_cpu = cpu;
+			if (pcpu_high_unit_cpu == NR_CPUS ||
+			    unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
+				pcpu_high_unit_cpu = cpu;
+		}
+	}
+	pcpu_nr_units = unit;
+
+	for_each_possible_cpu(cpu)
+		PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
+
+	/* we're done parsing the input, undefine BUG macro and dump config */
+#undef PCPU_SETUP_BUG_ON
+	pcpu_dump_alloc_info(KERN_DEBUG, ai);
+
+	pcpu_nr_groups = ai->nr_groups;
+	pcpu_group_offsets = group_offsets;
+	pcpu_group_sizes = group_sizes;
+	pcpu_unit_map = unit_map;
+	pcpu_unit_offsets = unit_off;
+
+	/* determine basic parameters */
+	pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
+	pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
+	pcpu_atom_size = ai->atom_size;
+	pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
+		BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
+
+	/*
+	 * Allocate chunk slots.  The additional last slot is for
+	 * empty chunks.
+	 */
+	pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
+	pcpu_slot = memblock_virt_alloc(
+			pcpu_nr_slots * sizeof(pcpu_slot[0]), 0);
+	for (i = 0; i < pcpu_nr_slots; i++)
+		INIT_LIST_HEAD(&pcpu_slot[i]);
+
+	/*
+	 * Initialize static chunk.  If reserved_size is zero, the
+	 * static chunk covers static area + dynamic allocation area
+	 * in the first chunk.  If reserved_size is not zero, it
+	 * covers static area + reserved area (mostly used for module
+	 * static percpu allocation).
+	 */
+	schunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0);
+	INIT_LIST_HEAD(&schunk->list);
+	INIT_LIST_HEAD(&schunk->map_extend_list);
+	schunk->base_addr = base_addr;
+	schunk->map = smap;
+	schunk->map_alloc = ARRAY_SIZE(smap);
+	schunk->immutable = true;
+	bitmap_fill(schunk->populated, pcpu_unit_pages);
+	schunk->nr_populated = pcpu_unit_pages;
+
+	if (ai->reserved_size) {
+		schunk->free_size = ai->reserved_size;
+		pcpu_reserved_chunk = schunk;
+		pcpu_reserved_chunk_limit = ai->static_size + ai->reserved_size;
+	} else {
+		schunk->free_size = dyn_size;
+		dyn_size = 0;			/* dynamic area covered */
+	}
+	schunk->contig_hint = schunk->free_size;
+
+	schunk->map[0] = 1;
+	schunk->map[1] = ai->static_size;
+	schunk->map_used = 1;
+	if (schunk->free_size)
+		schunk->map[++schunk->map_used] = ai->static_size + schunk->free_size;
+	schunk->map[schunk->map_used] |= 1;
+
+	/* init dynamic chunk if necessary */
+	if (dyn_size) {
+		dchunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0);
+		INIT_LIST_HEAD(&dchunk->list);
+		INIT_LIST_HEAD(&dchunk->map_extend_list);
+		dchunk->base_addr = base_addr;
+		dchunk->map = dmap;
+		dchunk->map_alloc = ARRAY_SIZE(dmap);
+		dchunk->immutable = true;
+		bitmap_fill(dchunk->populated, pcpu_unit_pages);
+		dchunk->nr_populated = pcpu_unit_pages;
+
+		dchunk->contig_hint = dchunk->free_size = dyn_size;
+		dchunk->map[0] = 1;
+		dchunk->map[1] = pcpu_reserved_chunk_limit;
+		dchunk->map[2] = (pcpu_reserved_chunk_limit + dchunk->free_size) | 1;
+		dchunk->map_used = 2;
+	}
+
+	/* link the first chunk in */
+	pcpu_first_chunk = dchunk ?: schunk;
+	pcpu_nr_empty_pop_pages +=
+		pcpu_count_occupied_pages(pcpu_first_chunk, 1);
+	pcpu_chunk_relocate(pcpu_first_chunk, -1);
+
+	/* we're done */
+	pcpu_base_addr = base_addr;
+	return 0;
+}
+
+#ifdef CONFIG_SMP
+
+const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
+	[PCPU_FC_AUTO]	= "auto",
+	[PCPU_FC_EMBED]	= "embed",
+	[PCPU_FC_PAGE]	= "page",
+};
+
+enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
+
+static int __init percpu_alloc_setup(char *str)
+{
+	if (!str)
+		return -EINVAL;
+
+	if (0)
+		/* nada */;
+#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
+	else if (!strcmp(str, "embed"))
+		pcpu_chosen_fc = PCPU_FC_EMBED;
+#endif
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+	else if (!strcmp(str, "page"))
+		pcpu_chosen_fc = PCPU_FC_PAGE;
+#endif
+	else
+		pr_warning("PERCPU: unknown allocator %s specified\n", str);
+
+	return 0;
+}
+early_param("percpu_alloc", percpu_alloc_setup);
+
+/*
+ * pcpu_embed_first_chunk() is used by the generic percpu setup.
+ * Build it if needed by the arch config or the generic setup is going
+ * to be used.
+ */
+#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
+	!defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
+#define BUILD_EMBED_FIRST_CHUNK
+#endif
+
+/* build pcpu_page_first_chunk() iff needed by the arch config */
+#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
+#define BUILD_PAGE_FIRST_CHUNK
+#endif
+
+/* pcpu_build_alloc_info() is used by both embed and page first chunk */
+#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
+/**
+ * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @dyn_size: minimum free size for dynamic allocation in bytes
+ * @atom_size: allocation atom size
+ * @cpu_distance_fn: callback to determine distance between cpus, optional
+ *
+ * This function determines grouping of units, their mappings to cpus
+ * and other parameters considering needed percpu size, allocation
+ * atom size and distances between CPUs.
+ *
+ * Groups are always multiples of atom size and CPUs which are of
+ * LOCAL_DISTANCE both ways are grouped together and share space for
+ * units in the same group.  The returned configuration is guaranteed
+ * to have CPUs on different nodes on different groups and >=75% usage
+ * of allocated virtual address space.
+ *
+ * RETURNS:
+ * On success, pointer to the new allocation_info is returned.  On
+ * failure, ERR_PTR value is returned.
+ */
+static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
+				size_t reserved_size, size_t dyn_size,
+				size_t atom_size,
+				pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
+{
+	static int group_map[NR_CPUS] __initdata;
+	static int group_cnt[NR_CPUS] __initdata;
+	const size_t static_size = __per_cpu_end - __per_cpu_start;
+	int nr_groups = 1, nr_units = 0;
+	size_t size_sum, min_unit_size, alloc_size;
+	int upa, max_upa, uninitialized_var(best_upa);	/* units_per_alloc */
+	int last_allocs, group, unit;
+	unsigned int cpu, tcpu;
+	struct pcpu_alloc_info *ai;
+	unsigned int *cpu_map;
+
+	/* this function may be called multiple times */
+	memset(group_map, 0, sizeof(group_map));
+	memset(group_cnt, 0, sizeof(group_cnt));
+
+	/* calculate size_sum and ensure dyn_size is enough for early alloc */
+	size_sum = PFN_ALIGN(static_size + reserved_size +
+			    max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
+	dyn_size = size_sum - static_size - reserved_size;
+
+	/*
+	 * Determine min_unit_size, alloc_size and max_upa such that
+	 * alloc_size is multiple of atom_size and is the smallest
+	 * which can accommodate 4k aligned segments which are equal to
+	 * or larger than min_unit_size.
+	 */
+	min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
+
+	alloc_size = roundup(min_unit_size, atom_size);
+	upa = alloc_size / min_unit_size;
+	while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
+		upa--;
+	max_upa = upa;
+
+	/* group cpus according to their proximity */
+	for_each_possible_cpu(cpu) {
+		group = 0;
+	next_group:
+		for_each_possible_cpu(tcpu) {
+			if (cpu == tcpu)
+				break;
+			if (group_map[tcpu] == group && cpu_distance_fn &&
+			    (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
+			     cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
+				group++;
+				nr_groups = max(nr_groups, group + 1);
+				goto next_group;
+			}
+		}
+		group_map[cpu] = group;
+		group_cnt[group]++;
+	}
+
+	/*
+	 * Expand unit size until address space usage goes over 75%
+	 * and then as much as possible without using more address
+	 * space.
+	 */
+	last_allocs = INT_MAX;
+	for (upa = max_upa; upa; upa--) {
+		int allocs = 0, wasted = 0;
+
+		if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
+			continue;
+
+		for (group = 0; group < nr_groups; group++) {
+			int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
+			allocs += this_allocs;
+			wasted += this_allocs * upa - group_cnt[group];
+		}
+
+		/*
+		 * Don't accept if wastage is over 1/3.  The
+		 * greater-than comparison ensures upa==1 always
+		 * passes the following check.
+		 */
+		if (wasted > num_possible_cpus() / 3)
+			continue;
+
+		/* and then don't consume more memory */
+		if (allocs > last_allocs)
+			break;
+		last_allocs = allocs;
+		best_upa = upa;
+	}
+	upa = best_upa;
+
+	/* allocate and fill alloc_info */
+	for (group = 0; group < nr_groups; group++)
+		nr_units += roundup(group_cnt[group], upa);
+
+	ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
+	if (!ai)
+		return ERR_PTR(-ENOMEM);
+	cpu_map = ai->groups[0].cpu_map;
+
+	for (group = 0; group < nr_groups; group++) {
+		ai->groups[group].cpu_map = cpu_map;
+		cpu_map += roundup(group_cnt[group], upa);
+	}
+
+	ai->static_size = static_size;
+	ai->reserved_size = reserved_size;
+	ai->dyn_size = dyn_size;
+	ai->unit_size = alloc_size / upa;
+	ai->atom_size = atom_size;
+	ai->alloc_size = alloc_size;
+
+	for (group = 0, unit = 0; group_cnt[group]; group++) {
+		struct pcpu_group_info *gi = &ai->groups[group];
+
+		/*
+		 * Initialize base_offset as if all groups are located
+		 * back-to-back.  The caller should update this to
+		 * reflect actual allocation.
+		 */
+		gi->base_offset = unit * ai->unit_size;
+
+		for_each_possible_cpu(cpu)
+			if (group_map[cpu] == group)
+				gi->cpu_map[gi->nr_units++] = cpu;
+		gi->nr_units = roundup(gi->nr_units, upa);
+		unit += gi->nr_units;
+	}
+	BUG_ON(unit != nr_units);
+
+	return ai;
+}
+#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
+
+#if defined(BUILD_EMBED_FIRST_CHUNK)
+/**
+ * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @dyn_size: minimum free size for dynamic allocation in bytes
+ * @atom_size: allocation atom size
+ * @cpu_distance_fn: callback to determine distance between cpus, optional
+ * @alloc_fn: function to allocate percpu page
+ * @free_fn: function to free percpu page
+ *
+ * This is a helper to ease setting up embedded first percpu chunk and
+ * can be called where pcpu_setup_first_chunk() is expected.
+ *
+ * If this function is used to setup the first chunk, it is allocated
+ * by calling @alloc_fn and used as-is without being mapped into
+ * vmalloc area.  Allocations are always whole multiples of @atom_size
+ * aligned to @atom_size.
+ *
+ * This enables the first chunk to piggy back on the linear physical
+ * mapping which often uses larger page size.  Please note that this
+ * can result in very sparse cpu->unit mapping on NUMA machines thus
+ * requiring large vmalloc address space.  Don't use this allocator if
+ * vmalloc space is not orders of magnitude larger than distances
+ * between node memory addresses (ie. 32bit NUMA machines).
+ *
+ * @dyn_size specifies the minimum dynamic area size.
+ *
+ * If the needed size is smaller than the minimum or specified unit
+ * size, the leftover is returned using @free_fn.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
+				  size_t atom_size,
+				  pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
+				  pcpu_fc_alloc_fn_t alloc_fn,
+				  pcpu_fc_free_fn_t free_fn)
+{
+	void *base = (void *)ULONG_MAX;
+	void **areas = NULL;
+	struct pcpu_alloc_info *ai;
+	size_t size_sum, areas_size, max_distance;
+	int group, i, rc;
+
+	ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
+				   cpu_distance_fn);
+	if (IS_ERR(ai))
+		return PTR_ERR(ai);
+
+	size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
+	areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
+
+	areas = memblock_virt_alloc_nopanic(areas_size, 0);
+	if (!areas) {
+		rc = -ENOMEM;
+		goto out_free;
+	}
+
+	/* allocate, copy and determine base address */
+	for (group = 0; group < ai->nr_groups; group++) {
+		struct pcpu_group_info *gi = &ai->groups[group];
+		unsigned int cpu = NR_CPUS;
+		void *ptr;
+
+		for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
+			cpu = gi->cpu_map[i];
+		BUG_ON(cpu == NR_CPUS);
+
+		/* allocate space for the whole group */
+		ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
+		if (!ptr) {
+			rc = -ENOMEM;
+			goto out_free_areas;
+		}
+		/* kmemleak tracks the percpu allocations separately */
+		kmemleak_free(ptr);
+		areas[group] = ptr;
+
+		base = min(ptr, base);
+	}
+
+	/*
+	 * Copy data and free unused parts.  This should happen after all
+	 * allocations are complete; otherwise, we may end up with
+	 * overlapping groups.
+	 */
+	for (group = 0; group < ai->nr_groups; group++) {
+		struct pcpu_group_info *gi = &ai->groups[group];
+		void *ptr = areas[group];
+
+		for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
+			if (gi->cpu_map[i] == NR_CPUS) {
+				/* unused unit, free whole */
+				free_fn(ptr, ai->unit_size);
+				continue;
+			}
+			/* copy and return the unused part */
+			memcpy(ptr, __per_cpu_load, ai->static_size);
+			free_fn(ptr + size_sum, ai->unit_size - size_sum);
+		}
+	}
+
+	/* base address is now known, determine group base offsets */
+	max_distance = 0;
+	for (group = 0; group < ai->nr_groups; group++) {
+		ai->groups[group].base_offset = areas[group] - base;
+		max_distance = max_t(size_t, max_distance,
+				     ai->groups[group].base_offset);
+	}
+	max_distance += ai->unit_size;
+
+	/* warn if maximum distance is further than 75% of vmalloc space */
+	if (max_distance > VMALLOC_TOTAL * 3 / 4) {
+		pr_warning("PERCPU: max_distance=0x%zx too large for vmalloc "
+			   "space 0x%lx\n", max_distance,
+			   VMALLOC_TOTAL);
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+		/* and fail if we have fallback */
+		rc = -EINVAL;
+		goto out_free;
+#endif
+	}
+
+	pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
+		PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,
+		ai->dyn_size, ai->unit_size);
+
+	rc = pcpu_setup_first_chunk(ai, base);
+	goto out_free;
+
+out_free_areas:
+	for (group = 0; group < ai->nr_groups; group++)
+		if (areas[group])
+			free_fn(areas[group],
+				ai->groups[group].nr_units * ai->unit_size);
+out_free:
+	pcpu_free_alloc_info(ai);
+	if (areas)
+		memblock_free_early(__pa(areas), areas_size);
+	return rc;
+}
+#endif /* BUILD_EMBED_FIRST_CHUNK */
+
+#ifdef BUILD_PAGE_FIRST_CHUNK
+/**
+ * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
+ * @free_fn: function to free percpu page, always called with PAGE_SIZE
+ * @populate_pte_fn: function to populate pte
+ *
+ * This is a helper to ease setting up page-remapped first percpu
+ * chunk and can be called where pcpu_setup_first_chunk() is expected.
+ *
+ * This is the basic allocator.  Static percpu area is allocated
+ * page-by-page into vmalloc area.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init pcpu_page_first_chunk(size_t reserved_size,
+				 pcpu_fc_alloc_fn_t alloc_fn,
+				 pcpu_fc_free_fn_t free_fn,
+				 pcpu_fc_populate_pte_fn_t populate_pte_fn)
+{
+	static struct vm_struct vm;
+	struct pcpu_alloc_info *ai;
+	char psize_str[16];
+	int unit_pages;
+	size_t pages_size;
+	struct page **pages;
+	int unit, i, j, rc;
+
+	snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
+
+	ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
+	if (IS_ERR(ai))
+		return PTR_ERR(ai);
+	BUG_ON(ai->nr_groups != 1);
+	BUG_ON(ai->groups[0].nr_units != num_possible_cpus());
+
+	unit_pages = ai->unit_size >> PAGE_SHIFT;
+
+	/* unaligned allocations can't be freed, round up to page size */
+	pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
+			       sizeof(pages[0]));
+	pages = memblock_virt_alloc(pages_size, 0);
+
+	/* allocate pages */
+	j = 0;
+	for (unit = 0; unit < num_possible_cpus(); unit++)
+		for (i = 0; i < unit_pages; i++) {
+			unsigned int cpu = ai->groups[0].cpu_map[unit];
+			void *ptr;
+
+			ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
+			if (!ptr) {
+				pr_warning("PERCPU: failed to allocate %s page "
+					   "for cpu%u\n", psize_str, cpu);
+				goto enomem;
+			}
+			/* kmemleak tracks the percpu allocations separately */
+			kmemleak_free(ptr);
+			pages[j++] = virt_to_page(ptr);
+		}
+
+	/* allocate vm area, map the pages and copy static data */
+	vm.flags = VM_ALLOC;
+	vm.size = num_possible_cpus() * ai->unit_size;
+	vm_area_register_early(&vm, PAGE_SIZE);
+
+	for (unit = 0; unit < num_possible_cpus(); unit++) {
+		unsigned long unit_addr =
+			(unsigned long)vm.addr + unit * ai->unit_size;
+
+		for (i = 0; i < unit_pages; i++)
+			populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
+
+		/* pte already populated, the following shouldn't fail */
+		rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
+				      unit_pages);
+		if (rc < 0)
+			panic("failed to map percpu area, err=%d\n", rc);
+
+		/*
+		 * FIXME: Archs with virtual cache should flush local
+		 * cache for the linear mapping here - something
+		 * equivalent to flush_cache_vmap() on the local cpu.
+		 * flush_cache_vmap() can't be used as most supporting
+		 * data structures are not set up yet.
+		 */
+
+		/* copy static data */
+		memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
+	}
+
+	/* we're ready, commit */
+	pr_info("PERCPU: %d %s pages/cpu @%p s%zu r%zu d%zu\n",
+		unit_pages, psize_str, vm.addr, ai->static_size,
+		ai->reserved_size, ai->dyn_size);
+
+	rc = pcpu_setup_first_chunk(ai, vm.addr);
+	goto out_free_ar;
+
+enomem:
+	while (--j >= 0)
+		free_fn(page_address(pages[j]), PAGE_SIZE);
+	rc = -ENOMEM;
+out_free_ar:
+	memblock_free_early(__pa(pages), pages_size);
+	pcpu_free_alloc_info(ai);
+	return rc;
+}
+#endif /* BUILD_PAGE_FIRST_CHUNK */
+
+#ifndef	CONFIG_HAVE_SETUP_PER_CPU_AREA
+/*
+ * Generic SMP percpu area setup.
+ *
+ * The embedding helper is used because its behavior closely resembles
+ * the original non-dynamic generic percpu area setup.  This is
+ * important because many archs have addressing restrictions and might
+ * fail if the percpu area is located far away from the previous
+ * location.  As an added bonus, in non-NUMA cases, embedding is
+ * generally a good idea TLB-wise because percpu area can piggy back
+ * on the physical linear memory mapping which uses large page
+ * mappings on applicable archs.
+ */
+unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL(__per_cpu_offset);
+
+static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
+				       size_t align)
+{
+	return  memblock_virt_alloc_from_nopanic(
+			size, align, __pa(MAX_DMA_ADDRESS));
+}
+
+static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
+{
+	memblock_free_early(__pa(ptr), size);
+}
+
+void __init setup_per_cpu_areas(void)
+{
+	unsigned long delta;
+	unsigned int cpu;
+	int rc;
+
+	/*
+	 * Always reserve area for module percpu variables.  That's
+	 * what the legacy allocator did.
+	 */
+	rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
+				    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
+				    pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
+	if (rc < 0)
+		panic("Failed to initialize percpu areas.");
+
+	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
+	for_each_possible_cpu(cpu)
+		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
+}
+#endif	/* CONFIG_HAVE_SETUP_PER_CPU_AREA */
+
+#else	/* CONFIG_SMP */
+
+/*
+ * UP percpu area setup.
+ *
+ * UP always uses km-based percpu allocator with identity mapping.
+ * Static percpu variables are indistinguishable from the usual static
+ * variables and don't require any special preparation.
+ */
+void __init setup_per_cpu_areas(void)
+{
+	const size_t unit_size =
+		roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
+					 PERCPU_DYNAMIC_RESERVE));
+	struct pcpu_alloc_info *ai;
+	void *fc;
+
+	ai = pcpu_alloc_alloc_info(1, 1);
+	fc = memblock_virt_alloc_from_nopanic(unit_size,
+					      PAGE_SIZE,
+					      __pa(MAX_DMA_ADDRESS));
+	if (!ai || !fc)
+		panic("Failed to allocate memory for percpu areas.");
+	/* kmemleak tracks the percpu allocations separately */
+	kmemleak_free(fc);
+
+	ai->dyn_size = unit_size;
+	ai->unit_size = unit_size;
+	ai->atom_size = unit_size;
+	ai->alloc_size = unit_size;
+	ai->groups[0].nr_units = 1;
+	ai->groups[0].cpu_map[0] = 0;
+
+	if (pcpu_setup_first_chunk(ai, fc) < 0)
+		panic("Failed to initialize percpu areas.");
+}
+
+#endif	/* CONFIG_SMP */
+
+/*
+ * First and reserved chunks are initialized with temporary allocation
+ * map in initdata so that they can be used before slab is online.
+ * This function is called after slab is brought up and replaces those
+ * with properly allocated maps.
+ */
+void __init percpu_init_late(void)
+{
+	struct pcpu_chunk *target_chunks[] =
+		{ pcpu_first_chunk, pcpu_reserved_chunk, NULL };
+	struct pcpu_chunk *chunk;
+	unsigned long flags;
+	int i;
+
+	for (i = 0; (chunk = target_chunks[i]); i++) {
+		int *map;
+		const size_t size = PERCPU_DYNAMIC_EARLY_SLOTS * sizeof(map[0]);
+
+		BUILD_BUG_ON(size > PAGE_SIZE);
+
+		map = pcpu_mem_zalloc(size);
+		BUG_ON(!map);
+
+		spin_lock_irqsave(&pcpu_lock, flags);
+		memcpy(map, chunk->map, size);
+		chunk->map = map;
+		spin_unlock_irqrestore(&pcpu_lock, flags);
+	}
+}
+
+/*
+ * Percpu allocator is initialized early during boot when neither slab or
+ * workqueue is available.  Plug async management until everything is up
+ * and running.
+ */
+static int __init percpu_enable_async(void)
+{
+	pcpu_async_enabled = true;
+	return 0;
+}
+subsys_initcall(percpu_enable_async);
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
new file mode 100644
index 0000000..1ba5821
--- /dev/null
+++ b/mm/pgtable-generic.c
@@ -0,0 +1,219 @@
+/*
+ *  mm/pgtable-generic.c
+ *
+ *  Generic pgtable methods declared in asm-generic/pgtable.h
+ *
+ *  Copyright (C) 2010  Linus Torvalds
+ */
+
+#include <linux/pagemap.h>
+#include <asm/tlb.h>
+#include <asm-generic/pgtable.h>
+
+/*
+ * If a p?d_bad entry is found while walking page tables, report
+ * the error, before resetting entry to p?d_none.  Usually (but
+ * very seldom) called out from the p?d_none_or_clear_bad macros.
+ */
+
+void pgd_clear_bad(pgd_t *pgd)
+{
+	pgd_ERROR(*pgd);
+	pgd_clear(pgd);
+}
+
+void pud_clear_bad(pud_t *pud)
+{
+	pud_ERROR(*pud);
+	pud_clear(pud);
+}
+
+void pmd_clear_bad(pmd_t *pmd)
+{
+	pmd_ERROR(*pmd);
+	pmd_clear(pmd);
+}
+
+#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
+/*
+ * Only sets the access flags (dirty, accessed), as well as write 
+ * permission. Furthermore, we know it always gets set to a "more
+ * permissive" setting, which allows most architectures to optimize
+ * this. We return whether the PTE actually changed, which in turn
+ * instructs the caller to do things like update__mmu_cache.  This
+ * used to be done in the caller, but sparc needs minor faults to
+ * force that call on sun4c so we changed this macro slightly
+ */
+int ptep_set_access_flags(struct vm_area_struct *vma,
+			  unsigned long address, pte_t *ptep,
+			  pte_t entry, int dirty)
+{
+	int changed = !pte_same(*ptep, entry);
+	if (changed) {
+		set_pte_at(vma->vm_mm, address, ptep, entry);
+		flush_tlb_fix_spurious_fault(vma, address);
+	}
+	return changed;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
+int ptep_clear_flush_young(struct vm_area_struct *vma,
+			   unsigned long address, pte_t *ptep)
+{
+	int young;
+	young = ptep_test_and_clear_young(vma, address, ptep);
+	if (young)
+		flush_tlb_page(vma, address);
+	return young;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
+pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
+		       pte_t *ptep)
+{
+	struct mm_struct *mm = (vma)->vm_mm;
+	pte_t pte;
+	pte = ptep_get_and_clear(mm, address, ptep);
+	if (pte_accessible(mm, pte))
+		flush_tlb_page(vma, address);
+	return pte;
+}
+#endif
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+#ifndef __HAVE_ARCH_FLUSH_PMD_TLB_RANGE
+
+/*
+ * ARCHes with special requirements for evicting THP backing TLB entries can
+ * implement this. Otherwise also, it can help optimize normal TLB flush in
+ * THP regime. stock flush_tlb_range() typically has optimization to nuke the
+ * entire TLB TLB if flush span is greater than a threshhold, which will
+ * likely be true for a single huge page. Thus a single thp flush will
+ * invalidate the entire TLB which is not desitable.
+ * e.g. see arch/arc: flush_pmd_tlb_range
+ */
+#define flush_pmd_tlb_range(vma, addr, end)	flush_tlb_range(vma, addr, end)
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
+int pmdp_set_access_flags(struct vm_area_struct *vma,
+			  unsigned long address, pmd_t *pmdp,
+			  pmd_t entry, int dirty)
+{
+	int changed = !pmd_same(*pmdp, entry);
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	if (changed) {
+		set_pmd_at(vma->vm_mm, address, pmdp, entry);
+		flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	}
+	return changed;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
+int pmdp_clear_flush_young(struct vm_area_struct *vma,
+			   unsigned long address, pmd_t *pmdp)
+{
+	int young;
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	young = pmdp_test_and_clear_young(vma, address, pmdp);
+	if (young)
+		flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	return young;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
+pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
+			    pmd_t *pmdp)
+{
+	pmd_t pmd;
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	VM_BUG_ON(!pmd_trans_huge(*pmdp));
+	pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
+	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	return pmd;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
+void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
+			  pmd_t *pmdp)
+{
+	pmd_t pmd = pmd_mksplitting(*pmdp);
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	set_pmd_at(vma->vm_mm, address, pmdp, pmd);
+	/* tlb flush only to serialize against gup-fast */
+	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+}
+#endif
+
+#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
+void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
+				pgtable_t pgtable)
+{
+	assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+	/* FIFO */
+	if (!pmd_huge_pte(mm, pmdp))
+		INIT_LIST_HEAD(&pgtable->lru);
+	else
+		list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
+	pmd_huge_pte(mm, pmdp) = pgtable;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
+/* no "address" argument so destroys page coloring of some arch */
+pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
+{
+	pgtable_t pgtable;
+
+	assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+	/* FIFO */
+	pgtable = pmd_huge_pte(mm, pmdp);
+	if (list_empty(&pgtable->lru))
+		pmd_huge_pte(mm, pmdp) = NULL;
+	else {
+		pmd_huge_pte(mm, pmdp) = list_entry(pgtable->lru.next,
+					      struct page, lru);
+		list_del(&pgtable->lru);
+	}
+	return pgtable;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_INVALIDATE
+void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
+		     pmd_t *pmdp)
+{
+	pmd_t entry = *pmdp;
+	set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry));
+	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+}
+#endif
+
+#ifndef pmdp_collapse_flush
+pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
+			  pmd_t *pmdp)
+{
+	/*
+	 * pmd and hugepage pte format are same. So we could
+	 * use the same function.
+	 */
+	pmd_t pmd;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	VM_BUG_ON(pmd_trans_huge(*pmdp));
+	pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
+
+	/* collapse entails shooting down ptes not pmd */
+	flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	return pmd;
+}
+#endif
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
new file mode 100644
index 0000000..5d453e5
--- /dev/null
+++ b/mm/process_vm_access.c
@@ -0,0 +1,365 @@
+/*
+ * linux/mm/process_vm_access.c
+ *
+ * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/mm.h>
+#include <linux/uio.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/ptrace.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+#endif
+
+/**
+ * process_vm_rw_pages - read/write pages from task specified
+ * @pages: array of pointers to pages we want to copy
+ * @start_offset: offset in page to start copying from/to
+ * @len: number of bytes to copy
+ * @iter: where to copy to/from locally
+ * @vm_write: 0 means copy from, 1 means copy to
+ * Returns 0 on success, error code otherwise
+ */
+static int process_vm_rw_pages(struct page **pages,
+			       unsigned offset,
+			       size_t len,
+			       struct iov_iter *iter,
+			       int vm_write)
+{
+	/* Do the copy for each page */
+	while (len && iov_iter_count(iter)) {
+		struct page *page = *pages++;
+		size_t copy = PAGE_SIZE - offset;
+		size_t copied;
+
+		if (copy > len)
+			copy = len;
+
+		if (vm_write) {
+			copied = copy_page_from_iter(page, offset, copy, iter);
+			set_page_dirty_lock(page);
+		} else {
+			copied = copy_page_to_iter(page, offset, copy, iter);
+		}
+		len -= copied;
+		if (copied < copy && iov_iter_count(iter))
+			return -EFAULT;
+		offset = 0;
+	}
+	return 0;
+}
+
+/* Maximum number of pages kmalloc'd to hold struct page's during copy */
+#define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)
+
+/**
+ * process_vm_rw_single_vec - read/write pages from task specified
+ * @addr: start memory address of target process
+ * @len: size of area to copy to/from
+ * @iter: where to copy to/from locally
+ * @process_pages: struct pages area that can store at least
+ *  nr_pages_to_copy struct page pointers
+ * @mm: mm for task
+ * @task: task to read/write from
+ * @vm_write: 0 means copy from, 1 means copy to
+ * Returns 0 on success or on failure error code
+ */
+static int process_vm_rw_single_vec(unsigned long addr,
+				    unsigned long len,
+				    struct iov_iter *iter,
+				    struct page **process_pages,
+				    struct mm_struct *mm,
+				    struct task_struct *task,
+				    int vm_write)
+{
+	unsigned long pa = addr & PAGE_MASK;
+	unsigned long start_offset = addr - pa;
+	unsigned long nr_pages;
+	ssize_t rc = 0;
+	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
+		/ sizeof(struct pages *);
+
+	/* Work out address and page range required */
+	if (len == 0)
+		return 0;
+	nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
+
+	while (!rc && nr_pages && iov_iter_count(iter)) {
+		int pages = min(nr_pages, max_pages_per_loop);
+		size_t bytes;
+
+		/* Get the pages we're interested in */
+		pages = get_user_pages_unlocked(task, mm, pa, pages,
+						vm_write, 0, process_pages);
+		if (pages <= 0)
+			return -EFAULT;
+
+		bytes = pages * PAGE_SIZE - start_offset;
+		if (bytes > len)
+			bytes = len;
+
+		rc = process_vm_rw_pages(process_pages,
+					 start_offset, bytes, iter,
+					 vm_write);
+		len -= bytes;
+		start_offset = 0;
+		nr_pages -= pages;
+		pa += pages * PAGE_SIZE;
+		while (pages)
+			put_page(process_pages[--pages]);
+	}
+
+	return rc;
+}
+
+/* Maximum number of entries for process pages array
+   which lives on stack */
+#define PVM_MAX_PP_ARRAY_COUNT 16
+
+/**
+ * process_vm_rw_core - core of reading/writing pages from task specified
+ * @pid: PID of process to read/write from/to
+ * @iter: where to copy to/from locally
+ * @rvec: iovec array specifying where to copy to/from in the other process
+ * @riovcnt: size of rvec array
+ * @flags: currently unused
+ * @vm_write: 0 if reading from other process, 1 if writing to other process
+ * Returns the number of bytes read/written or error code. May
+ *  return less bytes than expected if an error occurs during the copying
+ *  process.
+ */
+static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
+				  const struct iovec *rvec,
+				  unsigned long riovcnt,
+				  unsigned long flags, int vm_write)
+{
+	struct task_struct *task;
+	struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
+	struct page **process_pages = pp_stack;
+	struct mm_struct *mm;
+	unsigned long i;
+	ssize_t rc = 0;
+	unsigned long nr_pages = 0;
+	unsigned long nr_pages_iov;
+	ssize_t iov_len;
+	size_t total_len = iov_iter_count(iter);
+
+	/*
+	 * Work out how many pages of struct pages we're going to need
+	 * when eventually calling get_user_pages
+	 */
+	for (i = 0; i < riovcnt; i++) {
+		iov_len = rvec[i].iov_len;
+		if (iov_len > 0) {
+			nr_pages_iov = ((unsigned long)rvec[i].iov_base
+					+ iov_len)
+				/ PAGE_SIZE - (unsigned long)rvec[i].iov_base
+				/ PAGE_SIZE + 1;
+			nr_pages = max(nr_pages, nr_pages_iov);
+		}
+	}
+
+	if (nr_pages == 0)
+		return 0;
+
+	if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
+		/* For reliability don't try to kmalloc more than
+		   2 pages worth */
+		process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
+					      sizeof(struct pages *)*nr_pages),
+					GFP_KERNEL);
+
+		if (!process_pages)
+			return -ENOMEM;
+	}
+
+	/* Get process information */
+	rcu_read_lock();
+	task = find_task_by_vpid(pid);
+	if (task)
+		get_task_struct(task);
+	rcu_read_unlock();
+	if (!task) {
+		rc = -ESRCH;
+		goto free_proc_pages;
+	}
+
+	mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS);
+	if (!mm || IS_ERR(mm)) {
+		rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
+		/*
+		 * Explicitly map EACCES to EPERM as EPERM is a more a
+		 * appropriate error code for process_vw_readv/writev
+		 */
+		if (rc == -EACCES)
+			rc = -EPERM;
+		goto put_task_struct;
+	}
+
+	for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++)
+		rc = process_vm_rw_single_vec(
+			(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
+			iter, process_pages, mm, task, vm_write);
+
+	/* copied = space before - space after */
+	total_len -= iov_iter_count(iter);
+
+	/* If we have managed to copy any data at all then
+	   we return the number of bytes copied. Otherwise
+	   we return the error code */
+	if (total_len)
+		rc = total_len;
+
+	mmput(mm);
+
+put_task_struct:
+	put_task_struct(task);
+
+free_proc_pages:
+	if (process_pages != pp_stack)
+		kfree(process_pages);
+	return rc;
+}
+
+/**
+ * process_vm_rw - check iovecs before calling core routine
+ * @pid: PID of process to read/write from/to
+ * @lvec: iovec array specifying where to copy to/from locally
+ * @liovcnt: size of lvec array
+ * @rvec: iovec array specifying where to copy to/from in the other process
+ * @riovcnt: size of rvec array
+ * @flags: currently unused
+ * @vm_write: 0 if reading from other process, 1 if writing to other process
+ * Returns the number of bytes read/written or error code. May
+ *  return less bytes than expected if an error occurs during the copying
+ *  process.
+ */
+static ssize_t process_vm_rw(pid_t pid,
+			     const struct iovec __user *lvec,
+			     unsigned long liovcnt,
+			     const struct iovec __user *rvec,
+			     unsigned long riovcnt,
+			     unsigned long flags, int vm_write)
+{
+	struct iovec iovstack_l[UIO_FASTIOV];
+	struct iovec iovstack_r[UIO_FASTIOV];
+	struct iovec *iov_l = iovstack_l;
+	struct iovec *iov_r = iovstack_r;
+	struct iov_iter iter;
+	ssize_t rc;
+	int dir = vm_write ? WRITE : READ;
+
+	if (flags != 0)
+		return -EINVAL;
+
+	/* Check iovecs */
+	rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
+	if (rc < 0)
+		return rc;
+	if (!iov_iter_count(&iter))
+		goto free_iovecs;
+
+	rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
+				   iovstack_r, &iov_r);
+	if (rc <= 0)
+		goto free_iovecs;
+
+	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
+
+free_iovecs:
+	if (iov_r != iovstack_r)
+		kfree(iov_r);
+	kfree(iov_l);
+
+	return rc;
+}
+
+SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
+		unsigned long, liovcnt, const struct iovec __user *, rvec,
+		unsigned long, riovcnt,	unsigned long, flags)
+{
+	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
+}
+
+SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
+		const struct iovec __user *, lvec,
+		unsigned long, liovcnt, const struct iovec __user *, rvec,
+		unsigned long, riovcnt,	unsigned long, flags)
+{
+	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
+}
+
+#ifdef CONFIG_COMPAT
+
+static ssize_t
+compat_process_vm_rw(compat_pid_t pid,
+		     const struct compat_iovec __user *lvec,
+		     unsigned long liovcnt,
+		     const struct compat_iovec __user *rvec,
+		     unsigned long riovcnt,
+		     unsigned long flags, int vm_write)
+{
+	struct iovec iovstack_l[UIO_FASTIOV];
+	struct iovec iovstack_r[UIO_FASTIOV];
+	struct iovec *iov_l = iovstack_l;
+	struct iovec *iov_r = iovstack_r;
+	struct iov_iter iter;
+	ssize_t rc = -EFAULT;
+	int dir = vm_write ? WRITE : READ;
+
+	if (flags != 0)
+		return -EINVAL;
+
+	rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
+	if (rc < 0)
+		return rc;
+	if (!iov_iter_count(&iter))
+		goto free_iovecs;
+	rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
+					  UIO_FASTIOV, iovstack_r,
+					  &iov_r);
+	if (rc <= 0)
+		goto free_iovecs;
+
+	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
+
+free_iovecs:
+	if (iov_r != iovstack_r)
+		kfree(iov_r);
+	kfree(iov_l);
+	return rc;
+}
+
+COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid,
+		       const struct compat_iovec __user *, lvec,
+		       compat_ulong_t, liovcnt,
+		       const struct compat_iovec __user *, rvec,
+		       compat_ulong_t, riovcnt,
+		       compat_ulong_t, flags)
+{
+	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
+				    riovcnt, flags, 0);
+}
+
+COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid,
+		       const struct compat_iovec __user *, lvec,
+		       compat_ulong_t, liovcnt,
+		       const struct compat_iovec __user *, rvec,
+		       compat_ulong_t, riovcnt,
+		       compat_ulong_t, flags)
+{
+	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
+				    riovcnt, flags, 1);
+}
+
+#endif
diff --git a/mm/quicklist.c b/mm/quicklist.c
new file mode 100644
index 0000000..9422129
--- /dev/null
+++ b/mm/quicklist.c
@@ -0,0 +1,102 @@
+/*
+ * Quicklist support.
+ *
+ * Quicklists are light weight lists of pages that have a defined state
+ * on alloc and free. Pages must be in the quicklist specific defined state
+ * (zero by default) when the page is freed. It seems that the initial idea
+ * for such lists first came from Dave Miller and then various other people
+ * improved on it.
+ *
+ * Copyright (C) 2007 SGI,
+ * 	Christoph Lameter <clameter@sgi.com>
+ * 		Generalized, added support for multiple lists and
+ * 		constructors / destructors.
+ */
+#include <linux/kernel.h>
+
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/quicklist.h>
+
+DEFINE_PER_CPU(struct quicklist [CONFIG_NR_QUICK], quicklist);
+
+#define FRACTION_OF_NODE_MEM	16
+
+static unsigned long max_pages(unsigned long min_pages)
+{
+	unsigned long node_free_pages, max;
+	int node = numa_node_id();
+	struct zone *zones = NODE_DATA(node)->node_zones;
+	int num_cpus_on_node;
+
+	node_free_pages =
+#ifdef CONFIG_ZONE_DMA
+		zone_page_state(&zones[ZONE_DMA], NR_FREE_PAGES) +
+#endif
+#ifdef CONFIG_ZONE_DMA32
+		zone_page_state(&zones[ZONE_DMA32], NR_FREE_PAGES) +
+#endif
+		zone_page_state(&zones[ZONE_NORMAL], NR_FREE_PAGES);
+
+	max = node_free_pages / FRACTION_OF_NODE_MEM;
+
+	num_cpus_on_node = cpumask_weight(cpumask_of_node(node));
+	max /= num_cpus_on_node;
+
+	return max(max, min_pages);
+}
+
+static long min_pages_to_free(struct quicklist *q,
+	unsigned long min_pages, long max_free)
+{
+	long pages_to_free;
+
+	pages_to_free = q->nr_pages - max_pages(min_pages);
+
+	return min(pages_to_free, max_free);
+}
+
+/*
+ * Trim down the number of pages in the quicklist
+ */
+void quicklist_trim(int nr, void (*dtor)(void *),
+	unsigned long min_pages, unsigned long max_free)
+{
+	long pages_to_free;
+	struct quicklist *q;
+
+	q = &get_cpu_var(quicklist)[nr];
+	if (q->nr_pages > min_pages) {
+		pages_to_free = min_pages_to_free(q, min_pages, max_free);
+
+		while (pages_to_free > 0) {
+			/*
+			 * We pass a gfp_t of 0 to quicklist_alloc here
+			 * because we will never call into the page allocator.
+			 */
+			void *p = quicklist_alloc(nr, 0, NULL);
+
+			if (dtor)
+				dtor(p);
+			free_page((unsigned long)p);
+			pages_to_free--;
+		}
+	}
+	put_cpu_var(quicklist);
+}
+
+unsigned long quicklist_total_size(void)
+{
+	unsigned long count = 0;
+	int cpu;
+	struct quicklist *ql, *q;
+
+	for_each_online_cpu(cpu) {
+		ql = per_cpu(quicklist, cpu);
+		for (q = ql; q < ql + CONFIG_NR_QUICK; q++)
+			count += q->nr_pages;
+	}
+	return count;
+}
+
diff --git a/mm/readahead.c b/mm/readahead.c
new file mode 100644
index 0000000..ba22d7f
--- /dev/null
+++ b/mm/readahead.c
@@ -0,0 +1,570 @@
+/*
+ * mm/readahead.c - address_space-level file readahead.
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 09Apr2002	Andrew Morton
+ *		Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/pagevec.h>
+#include <linux/pagemap.h>
+#include <linux/syscalls.h>
+#include <linux/file.h>
+
+#include "internal.h"
+
+/*
+ * Initialise a struct file's readahead state.  Assumes that the caller has
+ * memset *ra to zero.
+ */
+void
+file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
+{
+	ra->ra_pages = inode_to_bdi(mapping->host)->ra_pages;
+	ra->prev_pos = -1;
+}
+EXPORT_SYMBOL_GPL(file_ra_state_init);
+
+#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
+
+/*
+ * see if a page needs releasing upon read_cache_pages() failure
+ * - the caller of read_cache_pages() may have set PG_private or PG_fscache
+ *   before calling, such as the NFS fs marking pages that are cached locally
+ *   on disk, thus we need to give the fs a chance to clean up in the event of
+ *   an error
+ */
+static void read_cache_pages_invalidate_page(struct address_space *mapping,
+					     struct page *page)
+{
+	if (page_has_private(page)) {
+		if (!trylock_page(page))
+			BUG();
+		page->mapping = mapping;
+		do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
+		page->mapping = NULL;
+		unlock_page(page);
+	}
+	page_cache_release(page);
+}
+
+/*
+ * release a list of pages, invalidating them first if need be
+ */
+static void read_cache_pages_invalidate_pages(struct address_space *mapping,
+					      struct list_head *pages)
+{
+	struct page *victim;
+
+	while (!list_empty(pages)) {
+		victim = list_to_page(pages);
+		list_del(&victim->lru);
+		read_cache_pages_invalidate_page(mapping, victim);
+	}
+}
+
+/**
+ * read_cache_pages - populate an address space with some pages & start reads against them
+ * @mapping: the address_space
+ * @pages: The address of a list_head which contains the target pages.  These
+ *   pages have their ->index populated and are otherwise uninitialised.
+ * @filler: callback routine for filling a single page.
+ * @data: private data for the callback routine.
+ *
+ * Hides the details of the LRU cache etc from the filesystems.
+ */
+int read_cache_pages(struct address_space *mapping, struct list_head *pages,
+			int (*filler)(void *, struct page *), void *data)
+{
+	struct page *page;
+	int ret = 0;
+
+	while (!list_empty(pages)) {
+		page = list_to_page(pages);
+		list_del(&page->lru);
+		if (add_to_page_cache_lru(page, mapping, page->index,
+				mapping_gfp_constraint(mapping, GFP_KERNEL))) {
+			read_cache_pages_invalidate_page(mapping, page);
+			continue;
+		}
+		page_cache_release(page);
+
+		ret = filler(data, page);
+		if (unlikely(ret)) {
+			read_cache_pages_invalidate_pages(mapping, pages);
+			break;
+		}
+		task_io_account_read(PAGE_CACHE_SIZE);
+	}
+	return ret;
+}
+
+EXPORT_SYMBOL(read_cache_pages);
+
+static int read_pages(struct address_space *mapping, struct file *filp,
+		struct list_head *pages, unsigned nr_pages)
+{
+	struct blk_plug plug;
+	unsigned page_idx;
+	int ret;
+
+	blk_start_plug(&plug);
+
+	if (mapping->a_ops->readpages) {
+		ret = mapping->a_ops->readpages(filp, mapping, pages, nr_pages);
+		/* Clean up the remaining pages */
+		put_pages_list(pages);
+		goto out;
+	}
+
+	for (page_idx = 0; page_idx < nr_pages; page_idx++) {
+		struct page *page = list_to_page(pages);
+		list_del(&page->lru);
+		if (!add_to_page_cache_lru(page, mapping, page->index,
+				mapping_gfp_constraint(mapping, GFP_KERNEL))) {
+			mapping->a_ops->readpage(filp, page);
+		}
+		page_cache_release(page);
+	}
+	ret = 0;
+
+out:
+	blk_finish_plug(&plug);
+
+	return ret;
+}
+
+/*
+ * __do_page_cache_readahead() actually reads a chunk of disk.  It allocates all
+ * the pages first, then submits them all for I/O. This avoids the very bad
+ * behaviour which would occur if page allocations are causing VM writeback.
+ * We really don't want to intermingle reads and writes like that.
+ *
+ * Returns the number of pages requested, or the maximum amount of I/O allowed.
+ */
+int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
+			pgoff_t offset, unsigned long nr_to_read,
+			unsigned long lookahead_size)
+{
+	struct inode *inode = mapping->host;
+	struct page *page;
+	unsigned long end_index;	/* The last page we want to read */
+	LIST_HEAD(page_pool);
+	int page_idx;
+	int ret = 0;
+	loff_t isize = i_size_read(inode);
+
+	if (isize == 0)
+		goto out;
+
+	end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
+
+	/*
+	 * Preallocate as many pages as we will need.
+	 */
+	for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
+		pgoff_t page_offset = offset + page_idx;
+
+		if (page_offset > end_index)
+			break;
+
+		rcu_read_lock();
+		page = radix_tree_lookup(&mapping->page_tree, page_offset);
+		rcu_read_unlock();
+		if (page && !radix_tree_exceptional_entry(page))
+			continue;
+
+		page = page_cache_alloc_readahead(mapping);
+		if (!page)
+			break;
+		page->index = page_offset;
+		list_add(&page->lru, &page_pool);
+		if (page_idx == nr_to_read - lookahead_size)
+			SetPageReadahead(page);
+		ret++;
+	}
+
+	/*
+	 * Now start the IO.  We ignore I/O errors - if the page is not
+	 * uptodate then the caller will launch readpage again, and
+	 * will then handle the error.
+	 */
+	if (ret)
+		read_pages(mapping, filp, &page_pool, ret);
+	BUG_ON(!list_empty(&page_pool));
+out:
+	return ret;
+}
+
+/*
+ * Chunk the readahead into 2 megabyte units, so that we don't pin too much
+ * memory at once.
+ */
+int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
+		pgoff_t offset, unsigned long nr_to_read)
+{
+	if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages))
+		return -EINVAL;
+
+	nr_to_read = min(nr_to_read, inode_to_bdi(mapping->host)->ra_pages);
+	while (nr_to_read) {
+		int err;
+
+		unsigned long this_chunk = (2 * 1024 * 1024) / PAGE_CACHE_SIZE;
+
+		if (this_chunk > nr_to_read)
+			this_chunk = nr_to_read;
+		err = __do_page_cache_readahead(mapping, filp,
+						offset, this_chunk, 0);
+		if (err < 0)
+			return err;
+
+		offset += this_chunk;
+		nr_to_read -= this_chunk;
+	}
+	return 0;
+}
+
+/*
+ * Set the initial window size, round to next power of 2 and square
+ * for small size, x 4 for medium, and x 2 for large
+ * for 128k (32 page) max ra
+ * 1-8 page = 32k initial, > 8 page = 128k initial
+ */
+static unsigned long get_init_ra_size(unsigned long size, unsigned long max)
+{
+	unsigned long newsize = roundup_pow_of_two(size);
+
+	if (newsize <= max / 32)
+		newsize = newsize * 4;
+	else if (newsize <= max / 4)
+		newsize = newsize * 2;
+	else
+		newsize = max;
+
+	return newsize;
+}
+
+/*
+ *  Get the previous window size, ramp it up, and
+ *  return it as the new window size.
+ */
+static unsigned long get_next_ra_size(struct file_ra_state *ra,
+						unsigned long max)
+{
+	unsigned long cur = ra->size;
+	unsigned long newsize;
+
+	if (cur < max / 16)
+		newsize = 4 * cur;
+	else
+		newsize = 2 * cur;
+
+	return min(newsize, max);
+}
+
+/*
+ * On-demand readahead design.
+ *
+ * The fields in struct file_ra_state represent the most-recently-executed
+ * readahead attempt:
+ *
+ *                        |<----- async_size ---------|
+ *     |------------------- size -------------------->|
+ *     |==================#===========================|
+ *     ^start             ^page marked with PG_readahead
+ *
+ * To overlap application thinking time and disk I/O time, we do
+ * `readahead pipelining': Do not wait until the application consumed all
+ * readahead pages and stalled on the missing page at readahead_index;
+ * Instead, submit an asynchronous readahead I/O as soon as there are
+ * only async_size pages left in the readahead window. Normally async_size
+ * will be equal to size, for maximum pipelining.
+ *
+ * In interleaved sequential reads, concurrent streams on the same fd can
+ * be invalidating each other's readahead state. So we flag the new readahead
+ * page at (start+size-async_size) with PG_readahead, and use it as readahead
+ * indicator. The flag won't be set on already cached pages, to avoid the
+ * readahead-for-nothing fuss, saving pointless page cache lookups.
+ *
+ * prev_pos tracks the last visited byte in the _previous_ read request.
+ * It should be maintained by the caller, and will be used for detecting
+ * small random reads. Note that the readahead algorithm checks loosely
+ * for sequential patterns. Hence interleaved reads might be served as
+ * sequential ones.
+ *
+ * There is a special-case: if the first page which the application tries to
+ * read happens to be the first page of the file, it is assumed that a linear
+ * read is about to happen and the window is immediately set to the initial size
+ * based on I/O request size and the max_readahead.
+ *
+ * The code ramps up the readahead size aggressively at first, but slow down as
+ * it approaches max_readhead.
+ */
+
+/*
+ * Count contiguously cached pages from @offset-1 to @offset-@max,
+ * this count is a conservative estimation of
+ * 	- length of the sequential read sequence, or
+ * 	- thrashing threshold in memory tight systems
+ */
+static pgoff_t count_history_pages(struct address_space *mapping,
+				   pgoff_t offset, unsigned long max)
+{
+	pgoff_t head;
+
+	rcu_read_lock();
+	head = page_cache_prev_hole(mapping, offset - 1, max);
+	rcu_read_unlock();
+
+	return offset - 1 - head;
+}
+
+/*
+ * page cache context based read-ahead
+ */
+static int try_context_readahead(struct address_space *mapping,
+				 struct file_ra_state *ra,
+				 pgoff_t offset,
+				 unsigned long req_size,
+				 unsigned long max)
+{
+	pgoff_t size;
+
+	size = count_history_pages(mapping, offset, max);
+
+	/*
+	 * not enough history pages:
+	 * it could be a random read
+	 */
+	if (size <= req_size)
+		return 0;
+
+	/*
+	 * starts from beginning of file:
+	 * it is a strong indication of long-run stream (or whole-file-read)
+	 */
+	if (size >= offset)
+		size *= 2;
+
+	ra->start = offset;
+	ra->size = min(size + req_size, max);
+	ra->async_size = 1;
+
+	return 1;
+}
+
+/*
+ * A minimal readahead algorithm for trivial sequential/random reads.
+ */
+static unsigned long
+ondemand_readahead(struct address_space *mapping,
+		   struct file_ra_state *ra, struct file *filp,
+		   bool hit_readahead_marker, pgoff_t offset,
+		   unsigned long req_size)
+{
+	unsigned long max = ra->ra_pages;
+	pgoff_t prev_offset;
+
+	/*
+	 * start of file
+	 */
+	if (!offset)
+		goto initial_readahead;
+
+	/*
+	 * It's the expected callback offset, assume sequential access.
+	 * Ramp up sizes, and push forward the readahead window.
+	 */
+	if ((offset == (ra->start + ra->size - ra->async_size) ||
+	     offset == (ra->start + ra->size))) {
+		ra->start += ra->size;
+		ra->size = get_next_ra_size(ra, max);
+		ra->async_size = ra->size;
+		goto readit;
+	}
+
+	/*
+	 * Hit a marked page without valid readahead state.
+	 * E.g. interleaved reads.
+	 * Query the pagecache for async_size, which normally equals to
+	 * readahead size. Ramp it up and use it as the new readahead size.
+	 */
+	if (hit_readahead_marker) {
+		pgoff_t start;
+
+		rcu_read_lock();
+		start = page_cache_next_hole(mapping, offset + 1, max);
+		rcu_read_unlock();
+
+		if (!start || start - offset > max)
+			return 0;
+
+		ra->start = start;
+		ra->size = start - offset;	/* old async_size */
+		ra->size += req_size;
+		ra->size = get_next_ra_size(ra, max);
+		ra->async_size = ra->size;
+		goto readit;
+	}
+
+	/*
+	 * oversize read
+	 */
+	if (req_size > max)
+		goto initial_readahead;
+
+	/*
+	 * sequential cache miss
+	 * trivial case: (offset - prev_offset) == 1
+	 * unaligned reads: (offset - prev_offset) == 0
+	 */
+	prev_offset = (unsigned long long)ra->prev_pos >> PAGE_CACHE_SHIFT;
+	if (offset - prev_offset <= 1UL)
+		goto initial_readahead;
+
+	/*
+	 * Query the page cache and look for the traces(cached history pages)
+	 * that a sequential stream would leave behind.
+	 */
+	if (try_context_readahead(mapping, ra, offset, req_size, max))
+		goto readit;
+
+	/*
+	 * standalone, small random read
+	 * Read as is, and do not pollute the readahead state.
+	 */
+	return __do_page_cache_readahead(mapping, filp, offset, req_size, 0);
+
+initial_readahead:
+	ra->start = offset;
+	ra->size = get_init_ra_size(req_size, max);
+	ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size;
+
+readit:
+	/*
+	 * Will this read hit the readahead marker made by itself?
+	 * If so, trigger the readahead marker hit now, and merge
+	 * the resulted next readahead window into the current one.
+	 */
+	if (offset == ra->start && ra->size == ra->async_size) {
+		ra->async_size = get_next_ra_size(ra, max);
+		ra->size += ra->async_size;
+	}
+
+	return ra_submit(ra, mapping, filp);
+}
+
+/**
+ * page_cache_sync_readahead - generic file readahead
+ * @mapping: address_space which holds the pagecache and I/O vectors
+ * @ra: file_ra_state which holds the readahead state
+ * @filp: passed on to ->readpage() and ->readpages()
+ * @offset: start offset into @mapping, in pagecache page-sized units
+ * @req_size: hint: total size of the read which the caller is performing in
+ *            pagecache pages
+ *
+ * page_cache_sync_readahead() should be called when a cache miss happened:
+ * it will submit the read.  The readahead logic may decide to piggyback more
+ * pages onto the read request if access patterns suggest it will improve
+ * performance.
+ */
+void page_cache_sync_readahead(struct address_space *mapping,
+			       struct file_ra_state *ra, struct file *filp,
+			       pgoff_t offset, unsigned long req_size)
+{
+	/* no read-ahead */
+	if (!ra->ra_pages)
+		return;
+
+	/* be dumb */
+	if (filp && (filp->f_mode & FMODE_RANDOM)) {
+		force_page_cache_readahead(mapping, filp, offset, req_size);
+		return;
+	}
+
+	/* do read-ahead */
+	ondemand_readahead(mapping, ra, filp, false, offset, req_size);
+}
+EXPORT_SYMBOL_GPL(page_cache_sync_readahead);
+
+/**
+ * page_cache_async_readahead - file readahead for marked pages
+ * @mapping: address_space which holds the pagecache and I/O vectors
+ * @ra: file_ra_state which holds the readahead state
+ * @filp: passed on to ->readpage() and ->readpages()
+ * @page: the page at @offset which has the PG_readahead flag set
+ * @offset: start offset into @mapping, in pagecache page-sized units
+ * @req_size: hint: total size of the read which the caller is performing in
+ *            pagecache pages
+ *
+ * page_cache_async_readahead() should be called when a page is used which
+ * has the PG_readahead flag; this is a marker to suggest that the application
+ * has used up enough of the readahead window that we should start pulling in
+ * more pages.
+ */
+void
+page_cache_async_readahead(struct address_space *mapping,
+			   struct file_ra_state *ra, struct file *filp,
+			   struct page *page, pgoff_t offset,
+			   unsigned long req_size)
+{
+	/* no read-ahead */
+	if (!ra->ra_pages)
+		return;
+
+	/*
+	 * Same bit is used for PG_readahead and PG_reclaim.
+	 */
+	if (PageWriteback(page))
+		return;
+
+	ClearPageReadahead(page);
+
+	/*
+	 * Defer asynchronous read-ahead on IO congestion.
+	 */
+	if (inode_read_congested(mapping->host))
+		return;
+
+	/* do read-ahead */
+	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
+}
+EXPORT_SYMBOL_GPL(page_cache_async_readahead);
+
+static ssize_t
+do_readahead(struct address_space *mapping, struct file *filp,
+	     pgoff_t index, unsigned long nr)
+{
+	if (!mapping || !mapping->a_ops)
+		return -EINVAL;
+
+	return force_page_cache_readahead(mapping, filp, index, nr);
+}
+
+SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count)
+{
+	ssize_t ret;
+	struct fd f;
+
+	ret = -EBADF;
+	f = fdget(fd);
+	if (f.file) {
+		if (f.file->f_mode & FMODE_READ) {
+			struct address_space *mapping = f.file->f_mapping;
+			pgoff_t start = offset >> PAGE_CACHE_SHIFT;
+			pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
+			unsigned long len = end - start + 1;
+			ret = do_readahead(mapping, f.file, start, len);
+		}
+		fdput(f);
+	}
+	return ret;
+}
diff --git a/mm/rmap.c b/mm/rmap.c
new file mode 100644
index 0000000..ede183c
--- /dev/null
+++ b/mm/rmap.c
@@ -0,0 +1,1753 @@
+/*
+ * mm/rmap.c - physical to virtual reverse mappings
+ *
+ * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
+ * Released under the General Public License (GPL).
+ *
+ * Simple, low overhead reverse mapping scheme.
+ * Please try to keep this thing as modular as possible.
+ *
+ * Provides methods for unmapping each kind of mapped page:
+ * the anon methods track anonymous pages, and
+ * the file methods track pages belonging to an inode.
+ *
+ * Original design by Rik van Riel <riel@conectiva.com.br> 2001
+ * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
+ * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
+ * Contributions by Hugh Dickins 2003, 2004
+ */
+
+/*
+ * Lock ordering in mm:
+ *
+ * inode->i_mutex	(while writing or truncating, not reading or faulting)
+ *   mm->mmap_sem
+ *     page->flags PG_locked (lock_page)
+ *       mapping->i_mmap_rwsem
+ *         anon_vma->rwsem
+ *           mm->page_table_lock or pte_lock
+ *             zone->lru_lock (in mark_page_accessed, isolate_lru_page)
+ *             swap_lock (in swap_duplicate, swap_info_get)
+ *               mmlist_lock (in mmput, drain_mmlist and others)
+ *               mapping->private_lock (in __set_page_dirty_buffers)
+ *                 mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
+ *                   mapping->tree_lock (widely used)
+ *               inode->i_lock (in set_page_dirty's __mark_inode_dirty)
+ *               bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
+ *                 sb_lock (within inode_lock in fs/fs-writeback.c)
+ *                 mapping->tree_lock (widely used, in set_page_dirty,
+ *                           in arch-dependent flush_dcache_mmap_lock,
+ *                           within bdi.wb->list_lock in __sync_single_inode)
+ *
+ * anon_vma->rwsem,mapping->i_mutex      (memory_failure, collect_procs_anon)
+ *   ->tasklist_lock
+ *     pte map lock
+ */
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/rcupdate.h>
+#include <linux/export.h>
+#include <linux/memcontrol.h>
+#include <linux/mmu_notifier.h>
+#include <linux/migrate.h>
+#include <linux/hugetlb.h>
+#include <linux/backing-dev.h>
+#include <linux/page_idle.h>
+
+#include <asm/tlbflush.h>
+
+#include <trace/events/tlb.h>
+
+#include "internal.h"
+
+static struct kmem_cache *anon_vma_cachep;
+static struct kmem_cache *anon_vma_chain_cachep;
+
+static inline struct anon_vma *anon_vma_alloc(void)
+{
+	struct anon_vma *anon_vma;
+
+	anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
+	if (anon_vma) {
+		atomic_set(&anon_vma->refcount, 1);
+		anon_vma->degree = 1;	/* Reference for first vma */
+		anon_vma->parent = anon_vma;
+		/*
+		 * Initialise the anon_vma root to point to itself. If called
+		 * from fork, the root will be reset to the parents anon_vma.
+		 */
+		anon_vma->root = anon_vma;
+	}
+
+	return anon_vma;
+}
+
+static inline void anon_vma_free(struct anon_vma *anon_vma)
+{
+	VM_BUG_ON(atomic_read(&anon_vma->refcount));
+
+	/*
+	 * Synchronize against page_lock_anon_vma_read() such that
+	 * we can safely hold the lock without the anon_vma getting
+	 * freed.
+	 *
+	 * Relies on the full mb implied by the atomic_dec_and_test() from
+	 * put_anon_vma() against the acquire barrier implied by
+	 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
+	 *
+	 * page_lock_anon_vma_read()	VS	put_anon_vma()
+	 *   down_read_trylock()		  atomic_dec_and_test()
+	 *   LOCK				  MB
+	 *   atomic_read()			  rwsem_is_locked()
+	 *
+	 * LOCK should suffice since the actual taking of the lock must
+	 * happen _before_ what follows.
+	 */
+	might_sleep();
+	if (rwsem_is_locked(&anon_vma->root->rwsem)) {
+		anon_vma_lock_write(anon_vma);
+		anon_vma_unlock_write(anon_vma);
+	}
+
+	kmem_cache_free(anon_vma_cachep, anon_vma);
+}
+
+static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
+{
+	return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
+}
+
+static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
+{
+	kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
+}
+
+static void anon_vma_chain_link(struct vm_area_struct *vma,
+				struct anon_vma_chain *avc,
+				struct anon_vma *anon_vma)
+{
+	avc->vma = vma;
+	avc->anon_vma = anon_vma;
+	list_add(&avc->same_vma, &vma->anon_vma_chain);
+	anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
+}
+
+/**
+ * anon_vma_prepare - attach an anon_vma to a memory region
+ * @vma: the memory region in question
+ *
+ * This makes sure the memory mapping described by 'vma' has
+ * an 'anon_vma' attached to it, so that we can associate the
+ * anonymous pages mapped into it with that anon_vma.
+ *
+ * The common case will be that we already have one, but if
+ * not we either need to find an adjacent mapping that we
+ * can re-use the anon_vma from (very common when the only
+ * reason for splitting a vma has been mprotect()), or we
+ * allocate a new one.
+ *
+ * Anon-vma allocations are very subtle, because we may have
+ * optimistically looked up an anon_vma in page_lock_anon_vma_read()
+ * and that may actually touch the spinlock even in the newly
+ * allocated vma (it depends on RCU to make sure that the
+ * anon_vma isn't actually destroyed).
+ *
+ * As a result, we need to do proper anon_vma locking even
+ * for the new allocation. At the same time, we do not want
+ * to do any locking for the common case of already having
+ * an anon_vma.
+ *
+ * This must be called with the mmap_sem held for reading.
+ */
+int anon_vma_prepare(struct vm_area_struct *vma)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+	struct anon_vma_chain *avc;
+
+	might_sleep();
+	if (unlikely(!anon_vma)) {
+		struct mm_struct *mm = vma->vm_mm;
+		struct anon_vma *allocated;
+
+		avc = anon_vma_chain_alloc(GFP_KERNEL);
+		if (!avc)
+			goto out_enomem;
+
+		anon_vma = find_mergeable_anon_vma(vma);
+		allocated = NULL;
+		if (!anon_vma) {
+			anon_vma = anon_vma_alloc();
+			if (unlikely(!anon_vma))
+				goto out_enomem_free_avc;
+			allocated = anon_vma;
+		}
+
+		anon_vma_lock_write(anon_vma);
+		/* page_table_lock to protect against threads */
+		spin_lock(&mm->page_table_lock);
+		if (likely(!vma->anon_vma)) {
+			vma->anon_vma = anon_vma;
+			anon_vma_chain_link(vma, avc, anon_vma);
+			/* vma reference or self-parent link for new root */
+			anon_vma->degree++;
+			allocated = NULL;
+			avc = NULL;
+		}
+		spin_unlock(&mm->page_table_lock);
+		anon_vma_unlock_write(anon_vma);
+
+		if (unlikely(allocated))
+			put_anon_vma(allocated);
+		if (unlikely(avc))
+			anon_vma_chain_free(avc);
+	}
+	return 0;
+
+ out_enomem_free_avc:
+	anon_vma_chain_free(avc);
+ out_enomem:
+	return -ENOMEM;
+}
+
+/*
+ * This is a useful helper function for locking the anon_vma root as
+ * we traverse the vma->anon_vma_chain, looping over anon_vma's that
+ * have the same vma.
+ *
+ * Such anon_vma's should have the same root, so you'd expect to see
+ * just a single mutex_lock for the whole traversal.
+ */
+static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
+{
+	struct anon_vma *new_root = anon_vma->root;
+	if (new_root != root) {
+		if (WARN_ON_ONCE(root))
+			up_write(&root->rwsem);
+		root = new_root;
+		down_write(&root->rwsem);
+	}
+	return root;
+}
+
+static inline void unlock_anon_vma_root(struct anon_vma *root)
+{
+	if (root)
+		up_write(&root->rwsem);
+}
+
+/*
+ * Attach the anon_vmas from src to dst.
+ * Returns 0 on success, -ENOMEM on failure.
+ *
+ * If dst->anon_vma is NULL this function tries to find and reuse existing
+ * anon_vma which has no vmas and only one child anon_vma. This prevents
+ * degradation of anon_vma hierarchy to endless linear chain in case of
+ * constantly forking task. On the other hand, an anon_vma with more than one
+ * child isn't reused even if there was no alive vma, thus rmap walker has a
+ * good chance of avoiding scanning the whole hierarchy when it searches where
+ * page is mapped.
+ */
+int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
+{
+	struct anon_vma_chain *avc, *pavc;
+	struct anon_vma *root = NULL;
+
+	list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
+		struct anon_vma *anon_vma;
+
+		avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
+		if (unlikely(!avc)) {
+			unlock_anon_vma_root(root);
+			root = NULL;
+			avc = anon_vma_chain_alloc(GFP_KERNEL);
+			if (!avc)
+				goto enomem_failure;
+		}
+		anon_vma = pavc->anon_vma;
+		root = lock_anon_vma_root(root, anon_vma);
+		anon_vma_chain_link(dst, avc, anon_vma);
+
+		/*
+		 * Reuse existing anon_vma if its degree lower than two,
+		 * that means it has no vma and only one anon_vma child.
+		 *
+		 * Do not chose parent anon_vma, otherwise first child
+		 * will always reuse it. Root anon_vma is never reused:
+		 * it has self-parent reference and at least one child.
+		 */
+		if (!dst->anon_vma && anon_vma != src->anon_vma &&
+				anon_vma->degree < 2)
+			dst->anon_vma = anon_vma;
+	}
+	if (dst->anon_vma)
+		dst->anon_vma->degree++;
+	unlock_anon_vma_root(root);
+	return 0;
+
+ enomem_failure:
+	/*
+	 * dst->anon_vma is dropped here otherwise its degree can be incorrectly
+	 * decremented in unlink_anon_vmas().
+	 * We can safely do this because callers of anon_vma_clone() don't care
+	 * about dst->anon_vma if anon_vma_clone() failed.
+	 */
+	dst->anon_vma = NULL;
+	unlink_anon_vmas(dst);
+	return -ENOMEM;
+}
+
+/*
+ * Attach vma to its own anon_vma, as well as to the anon_vmas that
+ * the corresponding VMA in the parent process is attached to.
+ * Returns 0 on success, non-zero on failure.
+ */
+int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
+{
+	struct anon_vma_chain *avc;
+	struct anon_vma *anon_vma;
+	int error;
+
+	/* Don't bother if the parent process has no anon_vma here. */
+	if (!pvma->anon_vma)
+		return 0;
+
+	/* Drop inherited anon_vma, we'll reuse existing or allocate new. */
+	vma->anon_vma = NULL;
+
+	/*
+	 * First, attach the new VMA to the parent VMA's anon_vmas,
+	 * so rmap can find non-COWed pages in child processes.
+	 */
+	error = anon_vma_clone(vma, pvma);
+	if (error)
+		return error;
+
+	/* An existing anon_vma has been reused, all done then. */
+	if (vma->anon_vma)
+		return 0;
+
+	/* Then add our own anon_vma. */
+	anon_vma = anon_vma_alloc();
+	if (!anon_vma)
+		goto out_error;
+	avc = anon_vma_chain_alloc(GFP_KERNEL);
+	if (!avc)
+		goto out_error_free_anon_vma;
+
+	/*
+	 * The root anon_vma's spinlock is the lock actually used when we
+	 * lock any of the anon_vmas in this anon_vma tree.
+	 */
+	anon_vma->root = pvma->anon_vma->root;
+	anon_vma->parent = pvma->anon_vma;
+	/*
+	 * With refcounts, an anon_vma can stay around longer than the
+	 * process it belongs to. The root anon_vma needs to be pinned until
+	 * this anon_vma is freed, because the lock lives in the root.
+	 */
+	get_anon_vma(anon_vma->root);
+	/* Mark this anon_vma as the one where our new (COWed) pages go. */
+	vma->anon_vma = anon_vma;
+	anon_vma_lock_write(anon_vma);
+	anon_vma_chain_link(vma, avc, anon_vma);
+	anon_vma->parent->degree++;
+	anon_vma_unlock_write(anon_vma);
+
+	return 0;
+
+ out_error_free_anon_vma:
+	put_anon_vma(anon_vma);
+ out_error:
+	unlink_anon_vmas(vma);
+	return -ENOMEM;
+}
+
+void unlink_anon_vmas(struct vm_area_struct *vma)
+{
+	struct anon_vma_chain *avc, *next;
+	struct anon_vma *root = NULL;
+
+	/*
+	 * Unlink each anon_vma chained to the VMA.  This list is ordered
+	 * from newest to oldest, ensuring the root anon_vma gets freed last.
+	 */
+	list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
+		struct anon_vma *anon_vma = avc->anon_vma;
+
+		root = lock_anon_vma_root(root, anon_vma);
+		anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
+
+		/*
+		 * Leave empty anon_vmas on the list - we'll need
+		 * to free them outside the lock.
+		 */
+		if (RB_EMPTY_ROOT(&anon_vma->rb_root)) {
+			anon_vma->parent->degree--;
+			continue;
+		}
+
+		list_del(&avc->same_vma);
+		anon_vma_chain_free(avc);
+	}
+	if (vma->anon_vma)
+		vma->anon_vma->degree--;
+	unlock_anon_vma_root(root);
+
+	/*
+	 * Iterate the list once more, it now only contains empty and unlinked
+	 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
+	 * needing to write-acquire the anon_vma->root->rwsem.
+	 */
+	list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
+		struct anon_vma *anon_vma = avc->anon_vma;
+
+		BUG_ON(anon_vma->degree);
+		put_anon_vma(anon_vma);
+
+		list_del(&avc->same_vma);
+		anon_vma_chain_free(avc);
+	}
+}
+
+static void anon_vma_ctor(void *data)
+{
+	struct anon_vma *anon_vma = data;
+
+	init_rwsem(&anon_vma->rwsem);
+	atomic_set(&anon_vma->refcount, 0);
+	anon_vma->rb_root = RB_ROOT;
+}
+
+void __init anon_vma_init(void)
+{
+	anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
+			0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
+	anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
+}
+
+/*
+ * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
+ *
+ * Since there is no serialization what so ever against page_remove_rmap()
+ * the best this function can do is return a locked anon_vma that might
+ * have been relevant to this page.
+ *
+ * The page might have been remapped to a different anon_vma or the anon_vma
+ * returned may already be freed (and even reused).
+ *
+ * In case it was remapped to a different anon_vma, the new anon_vma will be a
+ * child of the old anon_vma, and the anon_vma lifetime rules will therefore
+ * ensure that any anon_vma obtained from the page will still be valid for as
+ * long as we observe page_mapped() [ hence all those page_mapped() tests ].
+ *
+ * All users of this function must be very careful when walking the anon_vma
+ * chain and verify that the page in question is indeed mapped in it
+ * [ something equivalent to page_mapped_in_vma() ].
+ *
+ * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
+ * that the anon_vma pointer from page->mapping is valid if there is a
+ * mapcount, we can dereference the anon_vma after observing those.
+ */
+struct anon_vma *page_get_anon_vma(struct page *page)
+{
+	struct anon_vma *anon_vma = NULL;
+	unsigned long anon_mapping;
+
+	rcu_read_lock();
+	anon_mapping = (unsigned long)READ_ONCE(page->mapping);
+	if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+		goto out;
+	if (!page_mapped(page))
+		goto out;
+
+	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+	if (!atomic_inc_not_zero(&anon_vma->refcount)) {
+		anon_vma = NULL;
+		goto out;
+	}
+
+	/*
+	 * If this page is still mapped, then its anon_vma cannot have been
+	 * freed.  But if it has been unmapped, we have no security against the
+	 * anon_vma structure being freed and reused (for another anon_vma:
+	 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
+	 * above cannot corrupt).
+	 */
+	if (!page_mapped(page)) {
+		rcu_read_unlock();
+		put_anon_vma(anon_vma);
+		return NULL;
+	}
+out:
+	rcu_read_unlock();
+
+	return anon_vma;
+}
+
+/*
+ * Similar to page_get_anon_vma() except it locks the anon_vma.
+ *
+ * Its a little more complex as it tries to keep the fast path to a single
+ * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
+ * reference like with page_get_anon_vma() and then block on the mutex.
+ */
+struct anon_vma *page_lock_anon_vma_read(struct page *page)
+{
+	struct anon_vma *anon_vma = NULL;
+	struct anon_vma *root_anon_vma;
+	unsigned long anon_mapping;
+
+	rcu_read_lock();
+	anon_mapping = (unsigned long)READ_ONCE(page->mapping);
+	if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+		goto out;
+	if (!page_mapped(page))
+		goto out;
+
+	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+	root_anon_vma = READ_ONCE(anon_vma->root);
+	if (down_read_trylock(&root_anon_vma->rwsem)) {
+		/*
+		 * If the page is still mapped, then this anon_vma is still
+		 * its anon_vma, and holding the mutex ensures that it will
+		 * not go away, see anon_vma_free().
+		 */
+		if (!page_mapped(page)) {
+			up_read(&root_anon_vma->rwsem);
+			anon_vma = NULL;
+		}
+		goto out;
+	}
+
+	/* trylock failed, we got to sleep */
+	if (!atomic_inc_not_zero(&anon_vma->refcount)) {
+		anon_vma = NULL;
+		goto out;
+	}
+
+	if (!page_mapped(page)) {
+		rcu_read_unlock();
+		put_anon_vma(anon_vma);
+		return NULL;
+	}
+
+	/* we pinned the anon_vma, its safe to sleep */
+	rcu_read_unlock();
+	anon_vma_lock_read(anon_vma);
+
+	if (atomic_dec_and_test(&anon_vma->refcount)) {
+		/*
+		 * Oops, we held the last refcount, release the lock
+		 * and bail -- can't simply use put_anon_vma() because
+		 * we'll deadlock on the anon_vma_lock_write() recursion.
+		 */
+		anon_vma_unlock_read(anon_vma);
+		__put_anon_vma(anon_vma);
+		anon_vma = NULL;
+	}
+
+	return anon_vma;
+
+out:
+	rcu_read_unlock();
+	return anon_vma;
+}
+
+void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
+{
+	anon_vma_unlock_read(anon_vma);
+}
+
+/*
+ * At what user virtual address is page expected in @vma?
+ */
+static inline unsigned long
+__vma_address(struct page *page, struct vm_area_struct *vma)
+{
+	pgoff_t pgoff = page_to_pgoff(page);
+	return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+}
+
+inline unsigned long
+vma_address(struct page *page, struct vm_area_struct *vma)
+{
+	unsigned long address = __vma_address(page, vma);
+
+	/* page should be within @vma mapping range */
+	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+
+	return address;
+}
+
+#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
+static void percpu_flush_tlb_batch_pages(void *data)
+{
+	/*
+	 * All TLB entries are flushed on the assumption that it is
+	 * cheaper to flush all TLBs and let them be refilled than
+	 * flushing individual PFNs. Note that we do not track mm's
+	 * to flush as that might simply be multiple full TLB flushes
+	 * for no gain.
+	 */
+	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
+	flush_tlb_local();
+}
+
+/*
+ * Flush TLB entries for recently unmapped pages from remote CPUs. It is
+ * important if a PTE was dirty when it was unmapped that it's flushed
+ * before any IO is initiated on the page to prevent lost writes. Similarly,
+ * it must be flushed before freeing to prevent data leakage.
+ */
+void try_to_unmap_flush(void)
+{
+	struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
+	int cpu;
+
+	if (!tlb_ubc->flush_required)
+		return;
+
+	cpu = get_cpu();
+
+	trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, -1UL);
+
+	if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask))
+		percpu_flush_tlb_batch_pages(&tlb_ubc->cpumask);
+
+	if (cpumask_any_but(&tlb_ubc->cpumask, cpu) < nr_cpu_ids) {
+		smp_call_function_many(&tlb_ubc->cpumask,
+			percpu_flush_tlb_batch_pages, (void *)tlb_ubc, true);
+	}
+	cpumask_clear(&tlb_ubc->cpumask);
+	tlb_ubc->flush_required = false;
+	tlb_ubc->writable = false;
+	put_cpu();
+}
+
+/* Flush iff there are potentially writable TLB entries that can race with IO */
+void try_to_unmap_flush_dirty(void)
+{
+	struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
+
+	if (tlb_ubc->writable)
+		try_to_unmap_flush();
+}
+
+static void set_tlb_ubc_flush_pending(struct mm_struct *mm,
+		struct page *page, bool writable)
+{
+	struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
+
+	cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm));
+	tlb_ubc->flush_required = true;
+
+	/*
+	 * Ensure compiler does not re-order the setting of tlb_flush_batched
+	 * before the PTE is cleared.
+	 */
+	barrier();
+	mm->tlb_flush_batched = true;
+
+	/*
+	 * If the PTE was dirty then it's best to assume it's writable. The
+	 * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
+	 * before the page is queued for IO.
+	 */
+	if (writable)
+		tlb_ubc->writable = true;
+}
+
+/*
+ * Returns true if the TLB flush should be deferred to the end of a batch of
+ * unmap operations to reduce IPIs.
+ */
+static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
+{
+	bool should_defer = false;
+
+	if (!(flags & TTU_BATCH_FLUSH))
+		return false;
+
+	/* If remote CPUs need to be flushed then defer batch the flush */
+	if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
+		should_defer = true;
+	put_cpu();
+
+	return should_defer;
+}
+
+/*
+ * Reclaim unmaps pages under the PTL but do not flush the TLB prior to
+ * releasing the PTL if TLB flushes are batched. It's possible for a parallel
+ * operation such as mprotect or munmap to race between reclaim unmapping
+ * the page and flushing the page. If this race occurs, it potentially allows
+ * access to data via a stale TLB entry. Tracking all mm's that have TLB
+ * batching in flight would be expensive during reclaim so instead track
+ * whether TLB batching occurred in the past and if so then do a flush here
+ * if required. This will cost one additional flush per reclaim cycle paid
+ * by the first operation at risk such as mprotect and mumap.
+ *
+ * This must be called under the PTL so that an access to tlb_flush_batched
+ * that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise
+ * via the PTL.
+ */
+void flush_tlb_batched_pending(struct mm_struct *mm)
+{
+	if (mm->tlb_flush_batched) {
+		flush_tlb_mm(mm);
+
+		/*
+		 * Do not allow the compiler to re-order the clearing of
+		 * tlb_flush_batched before the tlb is flushed.
+		 */
+		barrier();
+		mm->tlb_flush_batched = false;
+	}
+}
+#else
+static void set_tlb_ubc_flush_pending(struct mm_struct *mm,
+		struct page *page, bool writable)
+{
+}
+
+static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
+{
+	return false;
+}
+#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
+
+/*
+ * At what user virtual address is page expected in vma?
+ * Caller should check the page is actually part of the vma.
+ */
+unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
+{
+	unsigned long address;
+	if (PageAnon(page)) {
+		struct anon_vma *page__anon_vma = page_anon_vma(page);
+		/*
+		 * Note: swapoff's unuse_vma() is more efficient with this
+		 * check, and needs it to match anon_vma when KSM is active.
+		 */
+		if (!vma->anon_vma || !page__anon_vma ||
+		    vma->anon_vma->root != page__anon_vma->root)
+			return -EFAULT;
+	} else if (page->mapping) {
+		if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
+			return -EFAULT;
+	} else
+		return -EFAULT;
+	address = __vma_address(page, vma);
+	if (unlikely(address < vma->vm_start || address >= vma->vm_end))
+		return -EFAULT;
+	return address;
+}
+
+pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd = NULL;
+	pmd_t pmde;
+
+	pgd = pgd_offset(mm, address);
+	if (!pgd_present(*pgd))
+		goto out;
+
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		goto out;
+
+	pmd = pmd_offset(pud, address);
+	/*
+	 * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
+	 * without holding anon_vma lock for write.  So when looking for a
+	 * genuine pmde (in which to find pte), test present and !THP together.
+	 */
+	pmde = *pmd;
+	barrier();
+	if (!pmd_present(pmde) || pmd_trans_huge(pmde))
+		pmd = NULL;
+out:
+	return pmd;
+}
+
+/*
+ * Check that @page is mapped at @address into @mm.
+ *
+ * If @sync is false, page_check_address may perform a racy check to avoid
+ * the page table lock when the pte is not present (helpful when reclaiming
+ * highly shared pages).
+ *
+ * On success returns with pte mapped and locked.
+ */
+pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
+			  unsigned long address, spinlock_t **ptlp, int sync)
+{
+	pmd_t *pmd;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	if (unlikely(PageHuge(page))) {
+		/* when pud is not present, pte will be NULL */
+		pte = huge_pte_offset(mm, address);
+		if (!pte)
+			return NULL;
+
+		ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
+		goto check;
+	}
+
+	pmd = mm_find_pmd(mm, address);
+	if (!pmd)
+		return NULL;
+
+	pte = pte_offset_map(pmd, address);
+	/* Make a quick check before getting the lock */
+	if (!sync && !pte_present(*pte)) {
+		pte_unmap(pte);
+		return NULL;
+	}
+
+	ptl = pte_lockptr(mm, pmd);
+check:
+	spin_lock(ptl);
+	if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
+		*ptlp = ptl;
+		return pte;
+	}
+	pte_unmap_unlock(pte, ptl);
+	return NULL;
+}
+
+/**
+ * page_mapped_in_vma - check whether a page is really mapped in a VMA
+ * @page: the page to test
+ * @vma: the VMA to test
+ *
+ * Returns 1 if the page is mapped into the page tables of the VMA, 0
+ * if the page is not mapped into the page tables of this VMA.  Only
+ * valid for normal file or anonymous VMAs.
+ */
+int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
+{
+	unsigned long address;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	address = __vma_address(page, vma);
+	if (unlikely(address < vma->vm_start || address >= vma->vm_end))
+		return 0;
+	pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
+	if (!pte)			/* the page is not in this mm */
+		return 0;
+	pte_unmap_unlock(pte, ptl);
+
+	return 1;
+}
+
+struct page_referenced_arg {
+	int mapcount;
+	int referenced;
+	unsigned long vm_flags;
+	struct mem_cgroup *memcg;
+};
+/*
+ * arg: page_referenced_arg will be passed
+ */
+static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
+			unsigned long address, void *arg)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	spinlock_t *ptl;
+	int referenced = 0;
+	struct page_referenced_arg *pra = arg;
+
+	if (unlikely(PageTransHuge(page))) {
+		pmd_t *pmd;
+
+		/*
+		 * rmap might return false positives; we must filter
+		 * these out using page_check_address_pmd().
+		 */
+		pmd = page_check_address_pmd(page, mm, address,
+					     PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
+		if (!pmd)
+			return SWAP_AGAIN;
+
+		if (vma->vm_flags & VM_LOCKED) {
+			spin_unlock(ptl);
+			pra->vm_flags |= VM_LOCKED;
+			return SWAP_FAIL; /* To break the loop */
+		}
+
+		/* go ahead even if the pmd is pmd_trans_splitting() */
+		if (pmdp_clear_flush_young_notify(vma, address, pmd))
+			referenced++;
+		spin_unlock(ptl);
+	} else {
+		pte_t *pte;
+
+		/*
+		 * rmap might return false positives; we must filter
+		 * these out using page_check_address().
+		 */
+		pte = page_check_address(page, mm, address, &ptl, 0);
+		if (!pte)
+			return SWAP_AGAIN;
+
+		if (vma->vm_flags & VM_LOCKED) {
+			pte_unmap_unlock(pte, ptl);
+			pra->vm_flags |= VM_LOCKED;
+			return SWAP_FAIL; /* To break the loop */
+		}
+
+		if (ptep_clear_flush_young_notify(vma, address, pte)) {
+			/*
+			 * Don't treat a reference through a sequentially read
+			 * mapping as such.  If the page has been used in
+			 * another mapping, we will catch it; if this other
+			 * mapping is already gone, the unmap path will have
+			 * set PG_referenced or activated the page.
+			 */
+			if (likely(!(vma->vm_flags & VM_SEQ_READ)))
+				referenced++;
+		}
+		pte_unmap_unlock(pte, ptl);
+	}
+
+	if (referenced)
+		clear_page_idle(page);
+	if (test_and_clear_page_young(page))
+		referenced++;
+
+	if (referenced) {
+		pra->referenced++;
+		pra->vm_flags |= vma->vm_flags;
+	}
+
+	pra->mapcount--;
+	if (!pra->mapcount)
+		return SWAP_SUCCESS; /* To break the loop */
+
+	return SWAP_AGAIN;
+}
+
+static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
+{
+	struct page_referenced_arg *pra = arg;
+	struct mem_cgroup *memcg = pra->memcg;
+
+	if (!mm_match_cgroup(vma->vm_mm, memcg))
+		return true;
+
+	return false;
+}
+
+/**
+ * page_referenced - test if the page was referenced
+ * @page: the page to test
+ * @is_locked: caller holds lock on the page
+ * @memcg: target memory cgroup
+ * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
+ *
+ * Quick test_and_clear_referenced for all mappings to a page,
+ * returns the number of ptes which referenced the page.
+ */
+int page_referenced(struct page *page,
+		    int is_locked,
+		    struct mem_cgroup *memcg,
+		    unsigned long *vm_flags)
+{
+	int ret;
+	int we_locked = 0;
+	struct page_referenced_arg pra = {
+		.mapcount = page_mapcount(page),
+		.memcg = memcg,
+	};
+	struct rmap_walk_control rwc = {
+		.rmap_one = page_referenced_one,
+		.arg = (void *)&pra,
+		.anon_lock = page_lock_anon_vma_read,
+	};
+
+	*vm_flags = 0;
+	if (!page_mapped(page))
+		return 0;
+
+	if (!page_rmapping(page))
+		return 0;
+
+	if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
+		we_locked = trylock_page(page);
+		if (!we_locked)
+			return 1;
+	}
+
+	/*
+	 * If we are reclaiming on behalf of a cgroup, skip
+	 * counting on behalf of references from different
+	 * cgroups
+	 */
+	if (memcg) {
+		rwc.invalid_vma = invalid_page_referenced_vma;
+	}
+
+	ret = rmap_walk(page, &rwc);
+	*vm_flags = pra.vm_flags;
+
+	if (we_locked)
+		unlock_page(page);
+
+	return pra.referenced;
+}
+
+static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
+			    unsigned long address, void *arg)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pte_t *pte;
+	spinlock_t *ptl;
+	int ret = 0;
+	int *cleaned = arg;
+
+	pte = page_check_address(page, mm, address, &ptl, 1);
+	if (!pte)
+		goto out;
+
+	if (pte_dirty(*pte) || pte_write(*pte)) {
+		pte_t entry;
+
+		flush_cache_page(vma, address, pte_pfn(*pte));
+		entry = ptep_clear_flush(vma, address, pte);
+		entry = pte_wrprotect(entry);
+		entry = pte_mkclean(entry);
+		set_pte_at(mm, address, pte, entry);
+		ret = 1;
+	}
+
+	pte_unmap_unlock(pte, ptl);
+
+	if (ret) {
+		mmu_notifier_invalidate_page(mm, address);
+		(*cleaned)++;
+	}
+out:
+	return SWAP_AGAIN;
+}
+
+static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
+{
+	if (vma->vm_flags & VM_SHARED)
+		return false;
+
+	return true;
+}
+
+int page_mkclean(struct page *page)
+{
+	int cleaned = 0;
+	struct address_space *mapping;
+	struct rmap_walk_control rwc = {
+		.arg = (void *)&cleaned,
+		.rmap_one = page_mkclean_one,
+		.invalid_vma = invalid_mkclean_vma,
+	};
+
+	BUG_ON(!PageLocked(page));
+
+	if (!page_mapped(page))
+		return 0;
+
+	mapping = page_mapping(page);
+	if (!mapping)
+		return 0;
+
+	rmap_walk(page, &rwc);
+
+	return cleaned;
+}
+EXPORT_SYMBOL_GPL(page_mkclean);
+
+/**
+ * page_move_anon_rmap - move a page to our anon_vma
+ * @page:	the page to move to our anon_vma
+ * @vma:	the vma the page belongs to
+ * @address:	the user virtual address mapped
+ *
+ * When a page belongs exclusively to one process after a COW event,
+ * that page can be moved into the anon_vma that belongs to just that
+ * process, so the rmap code will not search the parent or sibling
+ * processes.
+ */
+void page_move_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_VMA(!anon_vma, vma);
+	VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
+
+	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+	/*
+	 * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
+	 * simultaneously, so a concurrent reader (eg page_referenced()'s
+	 * PageAnon()) will not see one without the other.
+	 */
+	WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
+}
+
+/**
+ * __page_set_anon_rmap - set up new anonymous rmap
+ * @page:	Page to add to rmap	
+ * @vma:	VM area to add page to.
+ * @address:	User virtual address of the mapping	
+ * @exclusive:	the page is exclusively owned by the current process
+ */
+static void __page_set_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+
+	BUG_ON(!anon_vma);
+
+	if (PageAnon(page))
+		return;
+
+	/*
+	 * If the page isn't exclusively mapped into this vma,
+	 * we must use the _oldest_ possible anon_vma for the
+	 * page mapping!
+	 */
+	if (!exclusive)
+		anon_vma = anon_vma->root;
+
+	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+	page->mapping = (struct address_space *) anon_vma;
+	page->index = linear_page_index(vma, address);
+}
+
+/**
+ * __page_check_anon_rmap - sanity check anonymous rmap addition
+ * @page:	the page to add the mapping to
+ * @vma:	the vm area in which the mapping is added
+ * @address:	the user virtual address mapped
+ */
+static void __page_check_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address)
+{
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The page's anon-rmap details (mapping and index) are guaranteed to
+	 * be set up correctly at this point.
+	 *
+	 * We have exclusion against page_add_anon_rmap because the caller
+	 * always holds the page locked, except if called from page_dup_rmap,
+	 * in which case the page is already known to be setup.
+	 *
+	 * We have exclusion against page_add_new_anon_rmap because those pages
+	 * are initially only visible via the pagetables, and the pte is locked
+	 * over the call to page_add_new_anon_rmap.
+	 */
+	BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
+	BUG_ON(page->index != linear_page_index(vma, address));
+#endif
+}
+
+/**
+ * page_add_anon_rmap - add pte mapping to an anonymous page
+ * @page:	the page to add the mapping to
+ * @vma:	the vm area in which the mapping is added
+ * @address:	the user virtual address mapped
+ *
+ * The caller needs to hold the pte lock, and the page must be locked in
+ * the anon_vma case: to serialize mapping,index checking after setting,
+ * and to ensure that PageAnon is not being upgraded racily to PageKsm
+ * (but PageKsm is never downgraded to PageAnon).
+ */
+void page_add_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address)
+{
+	do_page_add_anon_rmap(page, vma, address, 0);
+}
+
+/*
+ * Special version of the above for do_swap_page, which often runs
+ * into pages that are exclusively owned by the current process.
+ * Everybody else should continue to use page_add_anon_rmap above.
+ */
+void do_page_add_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+	int first = atomic_inc_and_test(&page->_mapcount);
+	if (first) {
+		/*
+		 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+		 * these counters are not modified in interrupt context, and
+		 * pte lock(a spinlock) is held, which implies preemption
+		 * disabled.
+		 */
+		if (PageTransHuge(page))
+			__inc_zone_page_state(page,
+					      NR_ANON_TRANSPARENT_HUGEPAGES);
+		__mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
+				hpage_nr_pages(page));
+	}
+	if (unlikely(PageKsm(page)))
+		return;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	/* address might be in next vma when migration races vma_adjust */
+	if (first)
+		__page_set_anon_rmap(page, vma, address, exclusive);
+	else
+		__page_check_anon_rmap(page, vma, address);
+}
+
+/**
+ * page_add_new_anon_rmap - add pte mapping to a new anonymous page
+ * @page:	the page to add the mapping to
+ * @vma:	the vm area in which the mapping is added
+ * @address:	the user virtual address mapped
+ *
+ * Same as page_add_anon_rmap but must only be called on *new* pages.
+ * This means the inc-and-test can be bypassed.
+ * Page does not have to be locked.
+ */
+void page_add_new_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address)
+{
+	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+	SetPageSwapBacked(page);
+	atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
+	if (PageTransHuge(page))
+		__inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+	__mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
+			hpage_nr_pages(page));
+	__page_set_anon_rmap(page, vma, address, 1);
+}
+
+/**
+ * page_add_file_rmap - add pte mapping to a file page
+ * @page: the page to add the mapping to
+ *
+ * The caller needs to hold the pte lock.
+ */
+void page_add_file_rmap(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	if (atomic_inc_and_test(&page->_mapcount)) {
+		__inc_zone_page_state(page, NR_FILE_MAPPED);
+		mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
+	}
+	mem_cgroup_end_page_stat(memcg);
+}
+
+static void page_remove_file_rmap(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+
+	/* page still mapped by someone else? */
+	if (!atomic_add_negative(-1, &page->_mapcount))
+		goto out;
+
+	/* Hugepages are not counted in NR_FILE_MAPPED for now. */
+	if (unlikely(PageHuge(page)))
+		goto out;
+
+	/*
+	 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+	 * these counters are not modified in interrupt context, and
+	 * pte lock(a spinlock) is held, which implies preemption disabled.
+	 */
+	__dec_zone_page_state(page, NR_FILE_MAPPED);
+	mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
+
+	if (unlikely(PageMlocked(page)))
+		clear_page_mlock(page);
+out:
+	mem_cgroup_end_page_stat(memcg);
+}
+
+/**
+ * page_remove_rmap - take down pte mapping from a page
+ * @page: page to remove mapping from
+ *
+ * The caller needs to hold the pte lock.
+ */
+void page_remove_rmap(struct page *page)
+{
+	if (!PageAnon(page)) {
+		page_remove_file_rmap(page);
+		return;
+	}
+
+	/* page still mapped by someone else? */
+	if (!atomic_add_negative(-1, &page->_mapcount))
+		return;
+
+	/* Hugepages are not counted in NR_ANON_PAGES for now. */
+	if (unlikely(PageHuge(page)))
+		return;
+
+	/*
+	 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+	 * these counters are not modified in interrupt context, and
+	 * pte lock(a spinlock) is held, which implies preemption disabled.
+	 */
+	if (PageTransHuge(page))
+		__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+
+	__mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
+			      -hpage_nr_pages(page));
+
+	if (unlikely(PageMlocked(page)))
+		clear_page_mlock(page);
+
+	/*
+	 * It would be tidy to reset the PageAnon mapping here,
+	 * but that might overwrite a racing page_add_anon_rmap
+	 * which increments mapcount after us but sets mapping
+	 * before us: so leave the reset to free_hot_cold_page,
+	 * and remember that it's only reliable while mapped.
+	 * Leaving it set also helps swapoff to reinstate ptes
+	 * faster for those pages still in swapcache.
+	 */
+}
+
+/*
+ * @arg: enum ttu_flags will be passed to this argument
+ */
+static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
+		     unsigned long address, void *arg)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pte_t *pte;
+	pte_t pteval;
+	spinlock_t *ptl;
+	int ret = SWAP_AGAIN;
+	enum ttu_flags flags = (enum ttu_flags)arg;
+
+	/* munlock has nothing to gain from examining un-locked vmas */
+	if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
+		goto out;
+
+	pte = page_check_address(page, mm, address, &ptl, 0);
+	if (!pte)
+		goto out;
+
+	/*
+	 * If the page is mlock()d, we cannot swap it out.
+	 * If it's recently referenced (perhaps page_referenced
+	 * skipped over this mm) then we should reactivate it.
+	 */
+	if (!(flags & TTU_IGNORE_MLOCK)) {
+		if (vma->vm_flags & VM_LOCKED) {
+			/* Holding pte lock, we do *not* need mmap_sem here */
+			mlock_vma_page(page);
+			ret = SWAP_MLOCK;
+			goto out_unmap;
+		}
+		if (flags & TTU_MUNLOCK)
+			goto out_unmap;
+	}
+	if (!(flags & TTU_IGNORE_ACCESS)) {
+		if (ptep_clear_flush_young_notify(vma, address, pte)) {
+			ret = SWAP_FAIL;
+			goto out_unmap;
+		}
+  	}
+
+	/* Nuke the page table entry. */
+	flush_cache_page(vma, address, page_to_pfn(page));
+	if (should_defer_flush(mm, flags)) {
+		/*
+		 * We clear the PTE but do not flush so potentially a remote
+		 * CPU could still be writing to the page. If the entry was
+		 * previously clean then the architecture must guarantee that
+		 * a clear->dirty transition on a cached TLB entry is written
+		 * through and traps if the PTE is unmapped.
+		 */
+		pteval = ptep_get_and_clear(mm, address, pte);
+
+		set_tlb_ubc_flush_pending(mm, page, pte_dirty(pteval));
+	} else {
+		pteval = ptep_clear_flush(vma, address, pte);
+	}
+
+	/* Move the dirty bit to the physical page now the pte is gone. */
+	if (pte_dirty(pteval))
+		set_page_dirty(page);
+
+	/* Update high watermark before we lower rss */
+	update_hiwater_rss(mm);
+
+	if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
+		if (PageHuge(page)) {
+			hugetlb_count_sub(1 << compound_order(page), mm);
+		} else {
+			if (PageAnon(page))
+				dec_mm_counter(mm, MM_ANONPAGES);
+			else
+				dec_mm_counter(mm, MM_FILEPAGES);
+		}
+		set_pte_at(mm, address, pte,
+			   swp_entry_to_pte(make_hwpoison_entry(page)));
+	} else if (pte_unused(pteval)) {
+		/*
+		 * The guest indicated that the page content is of no
+		 * interest anymore. Simply discard the pte, vmscan
+		 * will take care of the rest.
+		 */
+		if (PageAnon(page))
+			dec_mm_counter(mm, MM_ANONPAGES);
+		else
+			dec_mm_counter(mm, MM_FILEPAGES);
+	} else if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION)) {
+		swp_entry_t entry;
+		pte_t swp_pte;
+		/*
+		 * Store the pfn of the page in a special migration
+		 * pte. do_swap_page() will wait until the migration
+		 * pte is removed and then restart fault handling.
+		 */
+		entry = make_migration_entry(page, pte_write(pteval));
+		swp_pte = swp_entry_to_pte(entry);
+		if (pte_soft_dirty(pteval))
+			swp_pte = pte_swp_mksoft_dirty(swp_pte);
+		set_pte_at(mm, address, pte, swp_pte);
+	} else if (PageAnon(page)) {
+		swp_entry_t entry = { .val = page_private(page) };
+		pte_t swp_pte;
+		/*
+		 * Store the swap location in the pte.
+		 * See handle_pte_fault() ...
+		 */
+		VM_BUG_ON_PAGE(!PageSwapCache(page), page);
+		if (swap_duplicate(entry) < 0) {
+			set_pte_at(mm, address, pte, pteval);
+			ret = SWAP_FAIL;
+			goto out_unmap;
+		}
+		if (list_empty(&mm->mmlist)) {
+			spin_lock(&mmlist_lock);
+			if (list_empty(&mm->mmlist))
+				list_add(&mm->mmlist, &init_mm.mmlist);
+			spin_unlock(&mmlist_lock);
+		}
+		dec_mm_counter(mm, MM_ANONPAGES);
+		inc_mm_counter(mm, MM_SWAPENTS);
+		swp_pte = swp_entry_to_pte(entry);
+		if (pte_soft_dirty(pteval))
+			swp_pte = pte_swp_mksoft_dirty(swp_pte);
+		set_pte_at(mm, address, pte, swp_pte);
+	} else
+		dec_mm_counter(mm, MM_FILEPAGES);
+
+	page_remove_rmap(page);
+	page_cache_release(page);
+
+out_unmap:
+	pte_unmap_unlock(pte, ptl);
+	if (ret != SWAP_FAIL && ret != SWAP_MLOCK && !(flags & TTU_MUNLOCK))
+		mmu_notifier_invalidate_page(mm, address);
+out:
+	return ret;
+}
+
+bool is_vma_temporary_stack(struct vm_area_struct *vma)
+{
+	int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
+
+	if (!maybe_stack)
+		return false;
+
+	if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
+						VM_STACK_INCOMPLETE_SETUP)
+		return true;
+
+	return false;
+}
+
+static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
+{
+	return is_vma_temporary_stack(vma);
+}
+
+static int page_not_mapped(struct page *page)
+{
+	return !page_mapped(page);
+};
+
+/**
+ * try_to_unmap - try to remove all page table mappings to a page
+ * @page: the page to get unmapped
+ * @flags: action and flags
+ *
+ * Tries to remove all the page table entries which are mapping this
+ * page, used in the pageout path.  Caller must hold the page lock.
+ * Return values are:
+ *
+ * SWAP_SUCCESS	- we succeeded in removing all mappings
+ * SWAP_AGAIN	- we missed a mapping, try again later
+ * SWAP_FAIL	- the page is unswappable
+ * SWAP_MLOCK	- page is mlocked.
+ */
+int try_to_unmap(struct page *page, enum ttu_flags flags)
+{
+	int ret;
+	struct rmap_walk_control rwc = {
+		.rmap_one = try_to_unmap_one,
+		.arg = (void *)flags,
+		.done = page_not_mapped,
+		.anon_lock = page_lock_anon_vma_read,
+	};
+
+	VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
+
+	/*
+	 * During exec, a temporary VMA is setup and later moved.
+	 * The VMA is moved under the anon_vma lock but not the
+	 * page tables leading to a race where migration cannot
+	 * find the migration ptes. Rather than increasing the
+	 * locking requirements of exec(), migration skips
+	 * temporary VMAs until after exec() completes.
+	 */
+	if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
+		rwc.invalid_vma = invalid_migration_vma;
+
+	ret = rmap_walk(page, &rwc);
+
+	if (ret != SWAP_MLOCK && !page_mapped(page))
+		ret = SWAP_SUCCESS;
+	return ret;
+}
+
+/**
+ * try_to_munlock - try to munlock a page
+ * @page: the page to be munlocked
+ *
+ * Called from munlock code.  Checks all of the VMAs mapping the page
+ * to make sure nobody else has this page mlocked. The page will be
+ * returned with PG_mlocked cleared if no other vmas have it mlocked.
+ *
+ * Return values are:
+ *
+ * SWAP_AGAIN	- no vma is holding page mlocked, or,
+ * SWAP_AGAIN	- page mapped in mlocked vma -- couldn't acquire mmap sem
+ * SWAP_FAIL	- page cannot be located at present
+ * SWAP_MLOCK	- page is now mlocked.
+ */
+int try_to_munlock(struct page *page)
+{
+	int ret;
+	struct rmap_walk_control rwc = {
+		.rmap_one = try_to_unmap_one,
+		.arg = (void *)TTU_MUNLOCK,
+		.done = page_not_mapped,
+		.anon_lock = page_lock_anon_vma_read,
+
+	};
+
+	VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
+
+	ret = rmap_walk(page, &rwc);
+	return ret;
+}
+
+void __put_anon_vma(struct anon_vma *anon_vma)
+{
+	struct anon_vma *root = anon_vma->root;
+
+	anon_vma_free(anon_vma);
+	if (root != anon_vma && atomic_dec_and_test(&root->refcount))
+		anon_vma_free(root);
+}
+
+static struct anon_vma *rmap_walk_anon_lock(struct page *page,
+					struct rmap_walk_control *rwc)
+{
+	struct anon_vma *anon_vma;
+
+	if (rwc->anon_lock)
+		return rwc->anon_lock(page);
+
+	/*
+	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
+	 * because that depends on page_mapped(); but not all its usages
+	 * are holding mmap_sem. Users without mmap_sem are required to
+	 * take a reference count to prevent the anon_vma disappearing
+	 */
+	anon_vma = page_anon_vma(page);
+	if (!anon_vma)
+		return NULL;
+
+	anon_vma_lock_read(anon_vma);
+	return anon_vma;
+}
+
+/*
+ * rmap_walk_anon - do something to anonymous page using the object-based
+ * rmap method
+ * @page: the page to be handled
+ * @rwc: control variable according to each walk type
+ *
+ * Find all the mappings of a page using the mapping pointer and the vma chains
+ * contained in the anon_vma struct it points to.
+ *
+ * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
+ * where the page was found will be held for write.  So, we won't recheck
+ * vm_flags for that VMA.  That should be OK, because that vma shouldn't be
+ * LOCKED.
+ */
+static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
+{
+	struct anon_vma *anon_vma;
+	pgoff_t pgoff;
+	struct anon_vma_chain *avc;
+	int ret = SWAP_AGAIN;
+
+	anon_vma = rmap_walk_anon_lock(page, rwc);
+	if (!anon_vma)
+		return ret;
+
+	pgoff = page_to_pgoff(page);
+	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
+		struct vm_area_struct *vma = avc->vma;
+		unsigned long address = vma_address(page, vma);
+
+		cond_resched();
+
+		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+			continue;
+
+		ret = rwc->rmap_one(page, vma, address, rwc->arg);
+		if (ret != SWAP_AGAIN)
+			break;
+		if (rwc->done && rwc->done(page))
+			break;
+	}
+	anon_vma_unlock_read(anon_vma);
+	return ret;
+}
+
+/*
+ * rmap_walk_file - do something to file page using the object-based rmap method
+ * @page: the page to be handled
+ * @rwc: control variable according to each walk type
+ *
+ * Find all the mappings of a page using the mapping pointer and the vma chains
+ * contained in the address_space struct it points to.
+ *
+ * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
+ * where the page was found will be held for write.  So, we won't recheck
+ * vm_flags for that VMA.  That should be OK, because that vma shouldn't be
+ * LOCKED.
+ */
+static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
+{
+	struct address_space *mapping = page->mapping;
+	pgoff_t pgoff;
+	struct vm_area_struct *vma;
+	int ret = SWAP_AGAIN;
+
+	/*
+	 * The page lock not only makes sure that page->mapping cannot
+	 * suddenly be NULLified by truncation, it makes sure that the
+	 * structure at mapping cannot be freed and reused yet,
+	 * so we can safely take mapping->i_mmap_rwsem.
+	 */
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+	if (!mapping)
+		return ret;
+
+	pgoff = page_to_pgoff(page);
+	i_mmap_lock_read(mapping);
+	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
+		unsigned long address = vma_address(page, vma);
+
+		cond_resched();
+
+		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+			continue;
+
+		ret = rwc->rmap_one(page, vma, address, rwc->arg);
+		if (ret != SWAP_AGAIN)
+			goto done;
+		if (rwc->done && rwc->done(page))
+			goto done;
+	}
+
+done:
+	i_mmap_unlock_read(mapping);
+	return ret;
+}
+
+int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
+{
+	if (unlikely(PageKsm(page)))
+		return rmap_walk_ksm(page, rwc);
+	else if (PageAnon(page))
+		return rmap_walk_anon(page, rwc);
+	else
+		return rmap_walk_file(page, rwc);
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * The following three functions are for anonymous (private mapped) hugepages.
+ * Unlike common anonymous pages, anonymous hugepages have no accounting code
+ * and no lru code, because we handle hugepages differently from common pages.
+ */
+static void __hugepage_set_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+
+	BUG_ON(!anon_vma);
+
+	if (PageAnon(page))
+		return;
+	if (!exclusive)
+		anon_vma = anon_vma->root;
+
+	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+	page->mapping = (struct address_space *) anon_vma;
+	page->index = linear_page_index(vma, address);
+}
+
+void hugepage_add_anon_rmap(struct page *page,
+			    struct vm_area_struct *vma, unsigned long address)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+	int first;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(!anon_vma);
+	/* address might be in next vma when migration races vma_adjust */
+	first = atomic_inc_and_test(&page->_mapcount);
+	if (first)
+		__hugepage_set_anon_rmap(page, vma, address, 0);
+}
+
+void hugepage_add_new_anon_rmap(struct page *page,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+	atomic_set(&page->_mapcount, 0);
+	__hugepage_set_anon_rmap(page, vma, address, 1);
+}
+#endif /* CONFIG_HUGETLB_PAGE */
diff --git a/mm/shmem.c b/mm/shmem.c
new file mode 100644
index 0000000..1b11ccc
--- /dev/null
+++ b/mm/shmem.c
@@ -0,0 +1,3471 @@
+/*
+ * Resizable virtual memory filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *		 2000 Transmeta Corp.
+ *		 2000-2001 Christoph Rohland
+ *		 2000-2001 SAP AG
+ *		 2002 Red Hat Inc.
+ * Copyright (C) 2002-2011 Hugh Dickins.
+ * Copyright (C) 2011 Google Inc.
+ * Copyright (C) 2002-2005 VERITAS Software Corporation.
+ * Copyright (C) 2004 Andi Kleen, SuSE Labs
+ *
+ * Extended attribute support for tmpfs:
+ * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
+ * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ *
+ * tiny-shmem:
+ * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/vfs.h>
+#include <linux/mount.h>
+#include <linux/ramfs.h>
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/swap.h>
+#include <linux/uio.h>
+
+static struct vfsmount *shm_mnt;
+
+#ifdef CONFIG_SHMEM
+/*
+ * This virtual memory filesystem is heavily based on the ramfs. It
+ * extends ramfs by the ability to use swap and honor resource limits
+ * which makes it a completely usable filesystem.
+ */
+
+#include <linux/xattr.h>
+#include <linux/exportfs.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/mman.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <linux/shmem_fs.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/pagevec.h>
+#include <linux/percpu_counter.h>
+#include <linux/falloc.h>
+#include <linux/splice.h>
+#include <linux/security.h>
+#include <linux/swapops.h>
+#include <linux/mempolicy.h>
+#include <linux/namei.h>
+#include <linux/ctype.h>
+#include <linux/migrate.h>
+#include <linux/highmem.h>
+#include <linux/seq_file.h>
+#include <linux/magic.h>
+#include <linux/syscalls.h>
+#include <linux/fcntl.h>
+#include <uapi/linux/memfd.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+
+#include "internal.h"
+
+#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
+#define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
+
+/* Pretend that each entry is of this size in directory's i_size */
+#define BOGO_DIRENT_SIZE 20
+
+/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
+#define SHORT_SYMLINK_LEN 128
+
+/*
+ * shmem_fallocate communicates with shmem_fault or shmem_writepage via
+ * inode->i_private (with i_mutex making sure that it has only one user at
+ * a time): we would prefer not to enlarge the shmem inode just for that.
+ */
+struct shmem_falloc {
+	wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
+	pgoff_t start;		/* start of range currently being fallocated */
+	pgoff_t next;		/* the next page offset to be fallocated */
+	pgoff_t nr_falloced;	/* how many new pages have been fallocated */
+	pgoff_t nr_unswapped;	/* how often writepage refused to swap out */
+};
+
+/* Flag allocation requirements to shmem_getpage */
+enum sgp_type {
+	SGP_READ,	/* don't exceed i_size, don't allocate page */
+	SGP_CACHE,	/* don't exceed i_size, may allocate page */
+	SGP_DIRTY,	/* like SGP_CACHE, but set new page dirty */
+	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */
+	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */
+};
+
+#ifdef CONFIG_TMPFS
+static unsigned long shmem_default_max_blocks(void)
+{
+	return totalram_pages / 2;
+}
+
+static unsigned long shmem_default_max_inodes(void)
+{
+	return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
+}
+#endif
+
+static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
+static int shmem_replace_page(struct page **pagep, gfp_t gfp,
+				struct shmem_inode_info *info, pgoff_t index);
+static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
+	struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
+
+static inline int shmem_getpage(struct inode *inode, pgoff_t index,
+	struct page **pagep, enum sgp_type sgp, int *fault_type)
+{
+	return shmem_getpage_gfp(inode, index, pagep, sgp,
+			mapping_gfp_mask(inode->i_mapping), fault_type);
+}
+
+static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+/*
+ * shmem_file_setup pre-accounts the whole fixed size of a VM object,
+ * for shared memory and for shared anonymous (/dev/zero) mappings
+ * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
+ * consistent with the pre-accounting of private mappings ...
+ */
+static inline int shmem_acct_size(unsigned long flags, loff_t size)
+{
+	return (flags & VM_NORESERVE) ?
+		0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
+}
+
+static inline void shmem_unacct_size(unsigned long flags, loff_t size)
+{
+	if (!(flags & VM_NORESERVE))
+		vm_unacct_memory(VM_ACCT(size));
+}
+
+static inline int shmem_reacct_size(unsigned long flags,
+		loff_t oldsize, loff_t newsize)
+{
+	if (!(flags & VM_NORESERVE)) {
+		if (VM_ACCT(newsize) > VM_ACCT(oldsize))
+			return security_vm_enough_memory_mm(current->mm,
+					VM_ACCT(newsize) - VM_ACCT(oldsize));
+		else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
+			vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
+	}
+	return 0;
+}
+
+/*
+ * ... whereas tmpfs objects are accounted incrementally as
+ * pages are allocated, in order to allow huge sparse files.
+ * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
+ * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
+ */
+static inline int shmem_acct_block(unsigned long flags)
+{
+	return (flags & VM_NORESERVE) ?
+		security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
+}
+
+static inline void shmem_unacct_blocks(unsigned long flags, long pages)
+{
+	if (flags & VM_NORESERVE)
+		vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
+}
+
+static const struct super_operations shmem_ops;
+static const struct address_space_operations shmem_aops;
+static const struct file_operations shmem_file_operations;
+static const struct inode_operations shmem_inode_operations;
+static const struct inode_operations shmem_dir_inode_operations;
+static const struct inode_operations shmem_special_inode_operations;
+static const struct vm_operations_struct shmem_vm_ops;
+
+static LIST_HEAD(shmem_swaplist);
+static DEFINE_MUTEX(shmem_swaplist_mutex);
+
+static int shmem_reserve_inode(struct super_block *sb)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+	if (sbinfo->max_inodes) {
+		spin_lock(&sbinfo->stat_lock);
+		if (!sbinfo->free_inodes) {
+			spin_unlock(&sbinfo->stat_lock);
+			return -ENOSPC;
+		}
+		sbinfo->free_inodes--;
+		spin_unlock(&sbinfo->stat_lock);
+	}
+	return 0;
+}
+
+static void shmem_free_inode(struct super_block *sb)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+	if (sbinfo->max_inodes) {
+		spin_lock(&sbinfo->stat_lock);
+		sbinfo->free_inodes++;
+		spin_unlock(&sbinfo->stat_lock);
+	}
+}
+
+/**
+ * shmem_recalc_inode - recalculate the block usage of an inode
+ * @inode: inode to recalc
+ *
+ * We have to calculate the free blocks since the mm can drop
+ * undirtied hole pages behind our back.
+ *
+ * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
+ * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
+ *
+ * It has to be called with the spinlock held.
+ */
+static void shmem_recalc_inode(struct inode *inode)
+{
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	long freed;
+
+	freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
+	if (freed > 0) {
+		struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+		if (sbinfo->max_blocks)
+			percpu_counter_add(&sbinfo->used_blocks, -freed);
+		info->alloced -= freed;
+		inode->i_blocks -= freed * BLOCKS_PER_PAGE;
+		shmem_unacct_blocks(info->flags, freed);
+	}
+}
+
+/*
+ * Replace item expected in radix tree by a new item, while holding tree lock.
+ */
+static int shmem_radix_tree_replace(struct address_space *mapping,
+			pgoff_t index, void *expected, void *replacement)
+{
+	void **pslot;
+	void *item;
+
+	VM_BUG_ON(!expected);
+	VM_BUG_ON(!replacement);
+	pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
+	if (!pslot)
+		return -ENOENT;
+	item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
+	if (item != expected)
+		return -ENOENT;
+	radix_tree_replace_slot(pslot, replacement);
+	return 0;
+}
+
+/*
+ * Sometimes, before we decide whether to proceed or to fail, we must check
+ * that an entry was not already brought back from swap by a racing thread.
+ *
+ * Checking page is not enough: by the time a SwapCache page is locked, it
+ * might be reused, and again be SwapCache, using the same swap as before.
+ */
+static bool shmem_confirm_swap(struct address_space *mapping,
+			       pgoff_t index, swp_entry_t swap)
+{
+	void *item;
+
+	rcu_read_lock();
+	item = radix_tree_lookup(&mapping->page_tree, index);
+	rcu_read_unlock();
+	return item == swp_to_radix_entry(swap);
+}
+
+/*
+ * Like add_to_page_cache_locked, but error if expected item has gone.
+ */
+static int shmem_add_to_page_cache(struct page *page,
+				   struct address_space *mapping,
+				   pgoff_t index, void *expected)
+{
+	int error;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+
+	page_cache_get(page);
+	page->mapping = mapping;
+	page->index = index;
+
+	spin_lock_irq(&mapping->tree_lock);
+	if (!expected)
+		error = radix_tree_insert(&mapping->page_tree, index, page);
+	else
+		error = shmem_radix_tree_replace(mapping, index, expected,
+								 page);
+	if (!error) {
+		mapping->nrpages++;
+		__inc_zone_page_state(page, NR_FILE_PAGES);
+		__inc_zone_page_state(page, NR_SHMEM);
+		spin_unlock_irq(&mapping->tree_lock);
+	} else {
+		page->mapping = NULL;
+		spin_unlock_irq(&mapping->tree_lock);
+		page_cache_release(page);
+	}
+	return error;
+}
+
+/*
+ * Like delete_from_page_cache, but substitutes swap for page.
+ */
+static void shmem_delete_from_page_cache(struct page *page, void *radswap)
+{
+	struct address_space *mapping = page->mapping;
+	int error;
+
+	spin_lock_irq(&mapping->tree_lock);
+	error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
+	page->mapping = NULL;
+	mapping->nrpages--;
+	__dec_zone_page_state(page, NR_FILE_PAGES);
+	__dec_zone_page_state(page, NR_SHMEM);
+	spin_unlock_irq(&mapping->tree_lock);
+	page_cache_release(page);
+	BUG_ON(error);
+}
+
+/*
+ * Remove swap entry from radix tree, free the swap and its page cache.
+ */
+static int shmem_free_swap(struct address_space *mapping,
+			   pgoff_t index, void *radswap)
+{
+	void *old;
+
+	spin_lock_irq(&mapping->tree_lock);
+	old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
+	spin_unlock_irq(&mapping->tree_lock);
+	if (old != radswap)
+		return -ENOENT;
+	free_swap_and_cache(radix_to_swp_entry(radswap));
+	return 0;
+}
+
+/*
+ * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
+ */
+void shmem_unlock_mapping(struct address_space *mapping)
+{
+	struct pagevec pvec;
+	pgoff_t indices[PAGEVEC_SIZE];
+	pgoff_t index = 0;
+
+	pagevec_init(&pvec, 0);
+	/*
+	 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
+	 */
+	while (!mapping_unevictable(mapping)) {
+		/*
+		 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
+		 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
+		 */
+		pvec.nr = find_get_entries(mapping, index,
+					   PAGEVEC_SIZE, pvec.pages, indices);
+		if (!pvec.nr)
+			break;
+		index = indices[pvec.nr - 1] + 1;
+		pagevec_remove_exceptionals(&pvec);
+		check_move_unevictable_pages(pvec.pages, pvec.nr);
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+}
+
+/*
+ * Remove range of pages and swap entries from radix tree, and free them.
+ * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
+ */
+static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
+								 bool unfalloc)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
+	unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
+	unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
+	struct pagevec pvec;
+	pgoff_t indices[PAGEVEC_SIZE];
+	long nr_swaps_freed = 0;
+	pgoff_t index;
+	int i;
+
+	if (lend == -1)
+		end = -1;	/* unsigned, so actually very big */
+
+	pagevec_init(&pvec, 0);
+	index = start;
+	while (index < end) {
+		pvec.nr = find_get_entries(mapping, index,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE),
+			pvec.pages, indices);
+		if (!pvec.nr)
+			break;
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+
+			index = indices[i];
+			if (index >= end)
+				break;
+
+			if (radix_tree_exceptional_entry(page)) {
+				if (unfalloc)
+					continue;
+				nr_swaps_freed += !shmem_free_swap(mapping,
+								index, page);
+				continue;
+			}
+
+			if (!trylock_page(page))
+				continue;
+			if (!unfalloc || !PageUptodate(page)) {
+				if (page->mapping == mapping) {
+					VM_BUG_ON_PAGE(PageWriteback(page), page);
+					truncate_inode_page(mapping, page);
+				}
+			}
+			unlock_page(page);
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		cond_resched();
+		index++;
+	}
+
+	if (partial_start) {
+		struct page *page = NULL;
+		shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
+		if (page) {
+			unsigned int top = PAGE_CACHE_SIZE;
+			if (start > end) {
+				top = partial_end;
+				partial_end = 0;
+			}
+			zero_user_segment(page, partial_start, top);
+			set_page_dirty(page);
+			unlock_page(page);
+			page_cache_release(page);
+		}
+	}
+	if (partial_end) {
+		struct page *page = NULL;
+		shmem_getpage(inode, end, &page, SGP_READ, NULL);
+		if (page) {
+			zero_user_segment(page, 0, partial_end);
+			set_page_dirty(page);
+			unlock_page(page);
+			page_cache_release(page);
+		}
+	}
+	if (start >= end)
+		return;
+
+	index = start;
+	while (index < end) {
+		cond_resched();
+
+		pvec.nr = find_get_entries(mapping, index,
+				min(end - index, (pgoff_t)PAGEVEC_SIZE),
+				pvec.pages, indices);
+		if (!pvec.nr) {
+			/* If all gone or hole-punch or unfalloc, we're done */
+			if (index == start || end != -1)
+				break;
+			/* But if truncating, restart to make sure all gone */
+			index = start;
+			continue;
+		}
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+
+			index = indices[i];
+			if (index >= end)
+				break;
+
+			if (radix_tree_exceptional_entry(page)) {
+				if (unfalloc)
+					continue;
+				if (shmem_free_swap(mapping, index, page)) {
+					/* Swap was replaced by page: retry */
+					index--;
+					break;
+				}
+				nr_swaps_freed++;
+				continue;
+			}
+
+			lock_page(page);
+			if (!unfalloc || !PageUptodate(page)) {
+				if (page->mapping == mapping) {
+					VM_BUG_ON_PAGE(PageWriteback(page), page);
+					truncate_inode_page(mapping, page);
+				} else {
+					/* Page was replaced by swap: retry */
+					unlock_page(page);
+					index--;
+					break;
+				}
+			}
+			unlock_page(page);
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		index++;
+	}
+
+	spin_lock(&info->lock);
+	info->swapped -= nr_swaps_freed;
+	shmem_recalc_inode(inode);
+	spin_unlock(&info->lock);
+}
+
+void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+	shmem_undo_range(inode, lstart, lend, false);
+	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+}
+EXPORT_SYMBOL_GPL(shmem_truncate_range);
+
+static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry,
+			 struct kstat *stat)
+{
+	struct inode *inode = dentry->d_inode;
+	struct shmem_inode_info *info = SHMEM_I(inode);
+
+	if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
+		spin_lock(&info->lock);
+		shmem_recalc_inode(inode);
+		spin_unlock(&info->lock);
+	}
+	generic_fillattr(inode, stat);
+	return 0;
+}
+
+static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = d_inode(dentry);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	int error;
+
+	error = inode_change_ok(inode, attr);
+	if (error)
+		return error;
+
+	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
+		loff_t oldsize = inode->i_size;
+		loff_t newsize = attr->ia_size;
+
+		/* protected by i_mutex */
+		if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
+		    (newsize > oldsize && (info->seals & F_SEAL_GROW)))
+			return -EPERM;
+
+		if (newsize != oldsize) {
+			error = shmem_reacct_size(SHMEM_I(inode)->flags,
+					oldsize, newsize);
+			if (error)
+				return error;
+			i_size_write(inode, newsize);
+			inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+		}
+		if (newsize <= oldsize) {
+			loff_t holebegin = round_up(newsize, PAGE_SIZE);
+			if (oldsize > holebegin)
+				unmap_mapping_range(inode->i_mapping,
+							holebegin, 0, 1);
+			if (info->alloced)
+				shmem_truncate_range(inode,
+							newsize, (loff_t)-1);
+			/* unmap again to remove racily COWed private pages */
+			if (oldsize > holebegin)
+				unmap_mapping_range(inode->i_mapping,
+							holebegin, 0, 1);
+		}
+	}
+
+	setattr_copy(inode, attr);
+	if (attr->ia_valid & ATTR_MODE)
+		error = posix_acl_chmod(inode, inode->i_mode);
+	return error;
+}
+
+static void shmem_evict_inode(struct inode *inode)
+{
+	struct shmem_inode_info *info = SHMEM_I(inode);
+
+	if (inode->i_mapping->a_ops == &shmem_aops) {
+		shmem_unacct_size(info->flags, inode->i_size);
+		inode->i_size = 0;
+		shmem_truncate_range(inode, 0, (loff_t)-1);
+		if (!list_empty(&info->swaplist)) {
+			mutex_lock(&shmem_swaplist_mutex);
+			list_del_init(&info->swaplist);
+			mutex_unlock(&shmem_swaplist_mutex);
+		}
+	}
+
+	simple_xattrs_free(&info->xattrs);
+	WARN_ON(inode->i_blocks);
+	shmem_free_inode(inode->i_sb);
+	clear_inode(inode);
+}
+
+/*
+ * If swap found in inode, free it and move page from swapcache to filecache.
+ */
+static int shmem_unuse_inode(struct shmem_inode_info *info,
+			     swp_entry_t swap, struct page **pagep)
+{
+	struct address_space *mapping = info->vfs_inode.i_mapping;
+	void *radswap;
+	pgoff_t index;
+	gfp_t gfp;
+	int error = 0;
+
+	radswap = swp_to_radix_entry(swap);
+	index = radix_tree_locate_item(&mapping->page_tree, radswap);
+	if (index == -1)
+		return -EAGAIN;	/* tell shmem_unuse we found nothing */
+
+	/*
+	 * Move _head_ to start search for next from here.
+	 * But be careful: shmem_evict_inode checks list_empty without taking
+	 * mutex, and there's an instant in list_move_tail when info->swaplist
+	 * would appear empty, if it were the only one on shmem_swaplist.
+	 */
+	if (shmem_swaplist.next != &info->swaplist)
+		list_move_tail(&shmem_swaplist, &info->swaplist);
+
+	gfp = mapping_gfp_mask(mapping);
+	if (shmem_should_replace_page(*pagep, gfp)) {
+		mutex_unlock(&shmem_swaplist_mutex);
+		error = shmem_replace_page(pagep, gfp, info, index);
+		mutex_lock(&shmem_swaplist_mutex);
+		/*
+		 * We needed to drop mutex to make that restrictive page
+		 * allocation, but the inode might have been freed while we
+		 * dropped it: although a racing shmem_evict_inode() cannot
+		 * complete without emptying the radix_tree, our page lock
+		 * on this swapcache page is not enough to prevent that -
+		 * free_swap_and_cache() of our swap entry will only
+		 * trylock_page(), removing swap from radix_tree whatever.
+		 *
+		 * We must not proceed to shmem_add_to_page_cache() if the
+		 * inode has been freed, but of course we cannot rely on
+		 * inode or mapping or info to check that.  However, we can
+		 * safely check if our swap entry is still in use (and here
+		 * it can't have got reused for another page): if it's still
+		 * in use, then the inode cannot have been freed yet, and we
+		 * can safely proceed (if it's no longer in use, that tells
+		 * nothing about the inode, but we don't need to unuse swap).
+		 */
+		if (!page_swapcount(*pagep))
+			error = -ENOENT;
+	}
+
+	/*
+	 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
+	 * but also to hold up shmem_evict_inode(): so inode cannot be freed
+	 * beneath us (pagelock doesn't help until the page is in pagecache).
+	 */
+	if (!error)
+		error = shmem_add_to_page_cache(*pagep, mapping, index,
+						radswap);
+	if (error != -ENOMEM) {
+		/*
+		 * Truncation and eviction use free_swap_and_cache(), which
+		 * only does trylock page: if we raced, best clean up here.
+		 */
+		delete_from_swap_cache(*pagep);
+		set_page_dirty(*pagep);
+		if (!error) {
+			spin_lock(&info->lock);
+			info->swapped--;
+			spin_unlock(&info->lock);
+			swap_free(swap);
+		}
+	}
+	return error;
+}
+
+/*
+ * Search through swapped inodes to find and replace swap by page.
+ */
+int shmem_unuse(swp_entry_t swap, struct page *page)
+{
+	struct list_head *this, *next;
+	struct shmem_inode_info *info;
+	struct mem_cgroup *memcg;
+	int error = 0;
+
+	/*
+	 * There's a faint possibility that swap page was replaced before
+	 * caller locked it: caller will come back later with the right page.
+	 */
+	if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
+		goto out;
+
+	/*
+	 * Charge page using GFP_KERNEL while we can wait, before taking
+	 * the shmem_swaplist_mutex which might hold up shmem_writepage().
+	 * Charged back to the user (not to caller) when swap account is used.
+	 */
+	error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg);
+	if (error)
+		goto out;
+	/* No radix_tree_preload: swap entry keeps a place for page in tree */
+	error = -EAGAIN;
+
+	mutex_lock(&shmem_swaplist_mutex);
+	list_for_each_safe(this, next, &shmem_swaplist) {
+		info = list_entry(this, struct shmem_inode_info, swaplist);
+		if (info->swapped)
+			error = shmem_unuse_inode(info, swap, &page);
+		else
+			list_del_init(&info->swaplist);
+		cond_resched();
+		if (error != -EAGAIN)
+			break;
+		/* found nothing in this: move on to search the next */
+	}
+	mutex_unlock(&shmem_swaplist_mutex);
+
+	if (error) {
+		if (error != -ENOMEM)
+			error = 0;
+		mem_cgroup_cancel_charge(page, memcg);
+	} else
+		mem_cgroup_commit_charge(page, memcg, true);
+out:
+	unlock_page(page);
+	page_cache_release(page);
+	return error;
+}
+
+/*
+ * Move the page from the page cache to the swap cache.
+ */
+static int shmem_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct shmem_inode_info *info;
+	struct address_space *mapping;
+	struct inode *inode;
+	swp_entry_t swap;
+	pgoff_t index;
+
+	BUG_ON(!PageLocked(page));
+	mapping = page->mapping;
+	index = page->index;
+	inode = mapping->host;
+	info = SHMEM_I(inode);
+	if (info->flags & VM_LOCKED)
+		goto redirty;
+	if (!total_swap_pages)
+		goto redirty;
+
+	/*
+	 * Our capabilities prevent regular writeback or sync from ever calling
+	 * shmem_writepage; but a stacking filesystem might use ->writepage of
+	 * its underlying filesystem, in which case tmpfs should write out to
+	 * swap only in response to memory pressure, and not for the writeback
+	 * threads or sync.
+	 */
+	if (!wbc->for_reclaim) {
+		WARN_ON_ONCE(1);	/* Still happens? Tell us about it! */
+		goto redirty;
+	}
+
+	/*
+	 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
+	 * value into swapfile.c, the only way we can correctly account for a
+	 * fallocated page arriving here is now to initialize it and write it.
+	 *
+	 * That's okay for a page already fallocated earlier, but if we have
+	 * not yet completed the fallocation, then (a) we want to keep track
+	 * of this page in case we have to undo it, and (b) it may not be a
+	 * good idea to continue anyway, once we're pushing into swap.  So
+	 * reactivate the page, and let shmem_fallocate() quit when too many.
+	 */
+	if (!PageUptodate(page)) {
+		if (inode->i_private) {
+			struct shmem_falloc *shmem_falloc;
+			spin_lock(&inode->i_lock);
+			shmem_falloc = inode->i_private;
+			if (shmem_falloc &&
+			    !shmem_falloc->waitq &&
+			    index >= shmem_falloc->start &&
+			    index < shmem_falloc->next)
+				shmem_falloc->nr_unswapped++;
+			else
+				shmem_falloc = NULL;
+			spin_unlock(&inode->i_lock);
+			if (shmem_falloc)
+				goto redirty;
+		}
+		clear_highpage(page);
+		flush_dcache_page(page);
+		SetPageUptodate(page);
+	}
+
+	swap = get_swap_page();
+	if (!swap.val)
+		goto redirty;
+
+	/*
+	 * Add inode to shmem_unuse()'s list of swapped-out inodes,
+	 * if it's not already there.  Do it now before the page is
+	 * moved to swap cache, when its pagelock no longer protects
+	 * the inode from eviction.  But don't unlock the mutex until
+	 * we've incremented swapped, because shmem_unuse_inode() will
+	 * prune a !swapped inode from the swaplist under this mutex.
+	 */
+	mutex_lock(&shmem_swaplist_mutex);
+	if (list_empty(&info->swaplist))
+		list_add_tail(&info->swaplist, &shmem_swaplist);
+
+	if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
+		spin_lock(&info->lock);
+		shmem_recalc_inode(inode);
+		info->swapped++;
+		spin_unlock(&info->lock);
+
+		swap_shmem_alloc(swap);
+		shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
+
+		mutex_unlock(&shmem_swaplist_mutex);
+		BUG_ON(page_mapped(page));
+		swap_writepage(page, wbc);
+		return 0;
+	}
+
+	mutex_unlock(&shmem_swaplist_mutex);
+	swapcache_free(swap);
+redirty:
+	set_page_dirty(page);
+	if (wbc->for_reclaim)
+		return AOP_WRITEPAGE_ACTIVATE;	/* Return with page locked */
+	unlock_page(page);
+	return 0;
+}
+
+#ifdef CONFIG_NUMA
+#ifdef CONFIG_TMPFS
+static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
+{
+	char buffer[64];
+
+	if (!mpol || mpol->mode == MPOL_DEFAULT)
+		return;		/* show nothing */
+
+	mpol_to_str(buffer, sizeof(buffer), mpol);
+
+	seq_printf(seq, ",mpol=%s", buffer);
+}
+
+static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
+{
+	struct mempolicy *mpol = NULL;
+	if (sbinfo->mpol) {
+		spin_lock(&sbinfo->stat_lock);	/* prevent replace/use races */
+		mpol = sbinfo->mpol;
+		mpol_get(mpol);
+		spin_unlock(&sbinfo->stat_lock);
+	}
+	return mpol;
+}
+#endif /* CONFIG_TMPFS */
+
+static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
+			struct shmem_inode_info *info, pgoff_t index)
+{
+	struct vm_area_struct pvma;
+	struct page *page;
+
+	/* Create a pseudo vma that just contains the policy */
+	pvma.vm_start = 0;
+	/* Bias interleave by inode number to distribute better across nodes */
+	pvma.vm_pgoff = index + info->vfs_inode.i_ino;
+	pvma.vm_ops = NULL;
+	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
+
+	page = swapin_readahead(swap, gfp, &pvma, 0);
+
+	/* Drop reference taken by mpol_shared_policy_lookup() */
+	mpol_cond_put(pvma.vm_policy);
+
+	return page;
+}
+
+static struct page *shmem_alloc_page(gfp_t gfp,
+			struct shmem_inode_info *info, pgoff_t index)
+{
+	struct vm_area_struct pvma;
+	struct page *page;
+
+	/* Create a pseudo vma that just contains the policy */
+	pvma.vm_start = 0;
+	/* Bias interleave by inode number to distribute better across nodes */
+	pvma.vm_pgoff = index + info->vfs_inode.i_ino;
+	pvma.vm_ops = NULL;
+	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
+
+	page = alloc_page_vma(gfp, &pvma, 0);
+
+	/* Drop reference taken by mpol_shared_policy_lookup() */
+	mpol_cond_put(pvma.vm_policy);
+
+	return page;
+}
+#else /* !CONFIG_NUMA */
+#ifdef CONFIG_TMPFS
+static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
+{
+}
+#endif /* CONFIG_TMPFS */
+
+static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
+			struct shmem_inode_info *info, pgoff_t index)
+{
+	return swapin_readahead(swap, gfp, NULL, 0);
+}
+
+static inline struct page *shmem_alloc_page(gfp_t gfp,
+			struct shmem_inode_info *info, pgoff_t index)
+{
+	return alloc_page(gfp);
+}
+#endif /* CONFIG_NUMA */
+
+#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
+static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
+{
+	return NULL;
+}
+#endif
+
+/*
+ * When a page is moved from swapcache to shmem filecache (either by the
+ * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
+ * shmem_unuse_inode()), it may have been read in earlier from swap, in
+ * ignorance of the mapping it belongs to.  If that mapping has special
+ * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
+ * we may need to copy to a suitable page before moving to filecache.
+ *
+ * In a future release, this may well be extended to respect cpuset and
+ * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
+ * but for now it is a simple matter of zone.
+ */
+static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
+{
+	return page_zonenum(page) > gfp_zone(gfp);
+}
+
+static int shmem_replace_page(struct page **pagep, gfp_t gfp,
+				struct shmem_inode_info *info, pgoff_t index)
+{
+	struct page *oldpage, *newpage;
+	struct address_space *swap_mapping;
+	pgoff_t swap_index;
+	int error;
+
+	oldpage = *pagep;
+	swap_index = page_private(oldpage);
+	swap_mapping = page_mapping(oldpage);
+
+	/*
+	 * We have arrived here because our zones are constrained, so don't
+	 * limit chance of success by further cpuset and node constraints.
+	 */
+	gfp &= ~GFP_CONSTRAINT_MASK;
+	newpage = shmem_alloc_page(gfp, info, index);
+	if (!newpage)
+		return -ENOMEM;
+
+	page_cache_get(newpage);
+	copy_highpage(newpage, oldpage);
+	flush_dcache_page(newpage);
+
+	__set_page_locked(newpage);
+	SetPageUptodate(newpage);
+	SetPageSwapBacked(newpage);
+	set_page_private(newpage, swap_index);
+	SetPageSwapCache(newpage);
+
+	/*
+	 * Our caller will very soon move newpage out of swapcache, but it's
+	 * a nice clean interface for us to replace oldpage by newpage there.
+	 */
+	spin_lock_irq(&swap_mapping->tree_lock);
+	error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
+								   newpage);
+	if (!error) {
+		__inc_zone_page_state(newpage, NR_FILE_PAGES);
+		__dec_zone_page_state(oldpage, NR_FILE_PAGES);
+	}
+	spin_unlock_irq(&swap_mapping->tree_lock);
+
+	if (unlikely(error)) {
+		/*
+		 * Is this possible?  I think not, now that our callers check
+		 * both PageSwapCache and page_private after getting page lock;
+		 * but be defensive.  Reverse old to newpage for clear and free.
+		 */
+		oldpage = newpage;
+	} else {
+		mem_cgroup_replace_page(oldpage, newpage);
+		lru_cache_add_anon(newpage);
+		*pagep = newpage;
+	}
+
+	ClearPageSwapCache(oldpage);
+	set_page_private(oldpage, 0);
+
+	unlock_page(oldpage);
+	page_cache_release(oldpage);
+	page_cache_release(oldpage);
+	return error;
+}
+
+/*
+ * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
+ *
+ * If we allocate a new one we do not mark it dirty. That's up to the
+ * vm. If we swap it in we mark it dirty since we also free the swap
+ * entry since a page cannot live in both the swap and page cache
+ */
+static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
+	struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct shmem_inode_info *info;
+	struct shmem_sb_info *sbinfo;
+	struct mem_cgroup *memcg;
+	struct page *page;
+	swp_entry_t swap;
+	int error;
+	int once = 0;
+	int alloced = 0;
+
+	if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
+		return -EFBIG;
+repeat:
+	swap.val = 0;
+	page = find_lock_entry(mapping, index);
+	if (radix_tree_exceptional_entry(page)) {
+		swap = radix_to_swp_entry(page);
+		page = NULL;
+	}
+
+	if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
+	    ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
+		error = -EINVAL;
+		goto unlock;
+	}
+
+	if (page && sgp == SGP_WRITE)
+		mark_page_accessed(page);
+
+	/* fallocated page? */
+	if (page && !PageUptodate(page)) {
+		if (sgp != SGP_READ)
+			goto clear;
+		unlock_page(page);
+		page_cache_release(page);
+		page = NULL;
+	}
+	if (page || (sgp == SGP_READ && !swap.val)) {
+		*pagep = page;
+		return 0;
+	}
+
+	/*
+	 * Fast cache lookup did not find it:
+	 * bring it back from swap or allocate.
+	 */
+	info = SHMEM_I(inode);
+	sbinfo = SHMEM_SB(inode->i_sb);
+
+	if (swap.val) {
+		/* Look it up and read it in.. */
+		page = lookup_swap_cache(swap);
+		if (!page) {
+			/* here we actually do the io */
+			if (fault_type)
+				*fault_type |= VM_FAULT_MAJOR;
+			page = shmem_swapin(swap, gfp, info, index);
+			if (!page) {
+				error = -ENOMEM;
+				goto failed;
+			}
+		}
+
+		/* We have to do this with page locked to prevent races */
+		lock_page(page);
+		if (!PageSwapCache(page) || page_private(page) != swap.val ||
+		    !shmem_confirm_swap(mapping, index, swap)) {
+			error = -EEXIST;	/* try again */
+			goto unlock;
+		}
+		if (!PageUptodate(page)) {
+			error = -EIO;
+			goto failed;
+		}
+		wait_on_page_writeback(page);
+
+		if (shmem_should_replace_page(page, gfp)) {
+			error = shmem_replace_page(&page, gfp, info, index);
+			if (error)
+				goto failed;
+		}
+
+		error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
+		if (!error) {
+			error = shmem_add_to_page_cache(page, mapping, index,
+						swp_to_radix_entry(swap));
+			/*
+			 * We already confirmed swap under page lock, and make
+			 * no memory allocation here, so usually no possibility
+			 * of error; but free_swap_and_cache() only trylocks a
+			 * page, so it is just possible that the entry has been
+			 * truncated or holepunched since swap was confirmed.
+			 * shmem_undo_range() will have done some of the
+			 * unaccounting, now delete_from_swap_cache() will do
+			 * the rest.
+			 * Reset swap.val? No, leave it so "failed" goes back to
+			 * "repeat": reading a hole and writing should succeed.
+			 */
+			if (error) {
+				mem_cgroup_cancel_charge(page, memcg);
+				delete_from_swap_cache(page);
+			}
+		}
+		if (error)
+			goto failed;
+
+		mem_cgroup_commit_charge(page, memcg, true);
+
+		spin_lock(&info->lock);
+		info->swapped--;
+		shmem_recalc_inode(inode);
+		spin_unlock(&info->lock);
+
+		if (sgp == SGP_WRITE)
+			mark_page_accessed(page);
+
+		delete_from_swap_cache(page);
+		set_page_dirty(page);
+		swap_free(swap);
+
+	} else {
+		if (shmem_acct_block(info->flags)) {
+			error = -ENOSPC;
+			goto failed;
+		}
+		if (sbinfo->max_blocks) {
+			if (percpu_counter_compare(&sbinfo->used_blocks,
+						sbinfo->max_blocks) >= 0) {
+				error = -ENOSPC;
+				goto unacct;
+			}
+			percpu_counter_inc(&sbinfo->used_blocks);
+		}
+
+		page = shmem_alloc_page(gfp, info, index);
+		if (!page) {
+			error = -ENOMEM;
+			goto decused;
+		}
+
+		__SetPageSwapBacked(page);
+		__set_page_locked(page);
+		if (sgp == SGP_WRITE)
+			__SetPageReferenced(page);
+
+		error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
+		if (error)
+			goto decused;
+		error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
+		if (!error) {
+			error = shmem_add_to_page_cache(page, mapping, index,
+							NULL);
+			radix_tree_preload_end();
+		}
+		if (error) {
+			mem_cgroup_cancel_charge(page, memcg);
+			goto decused;
+		}
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_anon(page);
+
+		spin_lock(&info->lock);
+		info->alloced++;
+		inode->i_blocks += BLOCKS_PER_PAGE;
+		shmem_recalc_inode(inode);
+		spin_unlock(&info->lock);
+		alloced = true;
+
+		/*
+		 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
+		 */
+		if (sgp == SGP_FALLOC)
+			sgp = SGP_WRITE;
+clear:
+		/*
+		 * Let SGP_WRITE caller clear ends if write does not fill page;
+		 * but SGP_FALLOC on a page fallocated earlier must initialize
+		 * it now, lest undo on failure cancel our earlier guarantee.
+		 */
+		if (sgp != SGP_WRITE) {
+			clear_highpage(page);
+			flush_dcache_page(page);
+			SetPageUptodate(page);
+		}
+		if (sgp == SGP_DIRTY)
+			set_page_dirty(page);
+	}
+
+	/* Perhaps the file has been truncated since we checked */
+	if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
+	    ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
+		if (alloced) {
+			ClearPageDirty(page);
+			delete_from_page_cache(page);
+			spin_lock(&info->lock);
+			shmem_recalc_inode(inode);
+			spin_unlock(&info->lock);
+		}
+		error = -EINVAL;
+		goto unlock;
+	}
+	*pagep = page;
+	return 0;
+
+	/*
+	 * Error recovery.
+	 */
+decused:
+	if (sbinfo->max_blocks)
+		percpu_counter_add(&sbinfo->used_blocks, -1);
+unacct:
+	shmem_unacct_blocks(info->flags, 1);
+failed:
+	if (swap.val && !shmem_confirm_swap(mapping, index, swap))
+		error = -EEXIST;
+unlock:
+	if (page) {
+		unlock_page(page);
+		page_cache_release(page);
+	}
+	if (error == -ENOSPC && !once++) {
+		info = SHMEM_I(inode);
+		spin_lock(&info->lock);
+		shmem_recalc_inode(inode);
+		spin_unlock(&info->lock);
+		goto repeat;
+	}
+	if (error == -EEXIST)	/* from above or from radix_tree_insert */
+		goto repeat;
+	return error;
+}
+
+static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vma->vm_file);
+	int error;
+	int ret = VM_FAULT_LOCKED;
+
+	/*
+	 * Trinity finds that probing a hole which tmpfs is punching can
+	 * prevent the hole-punch from ever completing: which in turn
+	 * locks writers out with its hold on i_mutex.  So refrain from
+	 * faulting pages into the hole while it's being punched.  Although
+	 * shmem_undo_range() does remove the additions, it may be unable to
+	 * keep up, as each new page needs its own unmap_mapping_range() call,
+	 * and the i_mmap tree grows ever slower to scan if new vmas are added.
+	 *
+	 * It does not matter if we sometimes reach this check just before the
+	 * hole-punch begins, so that one fault then races with the punch:
+	 * we just need to make racing faults a rare case.
+	 *
+	 * The implementation below would be much simpler if we just used a
+	 * standard mutex or completion: but we cannot take i_mutex in fault,
+	 * and bloating every shmem inode for this unlikely case would be sad.
+	 */
+	if (unlikely(inode->i_private)) {
+		struct shmem_falloc *shmem_falloc;
+
+		spin_lock(&inode->i_lock);
+		shmem_falloc = inode->i_private;
+		if (shmem_falloc &&
+		    shmem_falloc->waitq &&
+		    vmf->pgoff >= shmem_falloc->start &&
+		    vmf->pgoff < shmem_falloc->next) {
+			wait_queue_head_t *shmem_falloc_waitq;
+			DEFINE_WAIT(shmem_fault_wait);
+
+			ret = VM_FAULT_NOPAGE;
+			if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
+			   !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
+				/* It's polite to up mmap_sem if we can */
+				up_read(&vma->vm_mm->mmap_sem);
+				ret = VM_FAULT_RETRY;
+			}
+
+			shmem_falloc_waitq = shmem_falloc->waitq;
+			prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
+					TASK_UNINTERRUPTIBLE);
+			spin_unlock(&inode->i_lock);
+			schedule();
+
+			/*
+			 * shmem_falloc_waitq points into the shmem_fallocate()
+			 * stack of the hole-punching task: shmem_falloc_waitq
+			 * is usually invalid by the time we reach here, but
+			 * finish_wait() does not dereference it in that case;
+			 * though i_lock needed lest racing with wake_up_all().
+			 */
+			spin_lock(&inode->i_lock);
+			finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
+			spin_unlock(&inode->i_lock);
+			return ret;
+		}
+		spin_unlock(&inode->i_lock);
+	}
+
+	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
+	if (error)
+		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
+
+	if (ret & VM_FAULT_MAJOR) {
+		count_vm_event(PGMAJFAULT);
+		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+	}
+	return ret;
+}
+
+#ifdef CONFIG_NUMA
+static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
+{
+	struct inode *inode = file_inode(vma->vm_file);
+	return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
+}
+
+static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
+					  unsigned long addr)
+{
+	struct inode *inode = file_inode(vma->vm_file);
+	pgoff_t index;
+
+	index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+	return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
+}
+#endif
+
+int shmem_lock(struct file *file, int lock, struct user_struct *user)
+{
+	struct inode *inode = file_inode(file);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	int retval = -ENOMEM;
+
+	spin_lock(&info->lock);
+	if (lock && !(info->flags & VM_LOCKED)) {
+		if (!user_shm_lock(inode->i_size, user))
+			goto out_nomem;
+		info->flags |= VM_LOCKED;
+		mapping_set_unevictable(file->f_mapping);
+	}
+	if (!lock && (info->flags & VM_LOCKED) && user) {
+		user_shm_unlock(inode->i_size, user);
+		info->flags &= ~VM_LOCKED;
+		mapping_clear_unevictable(file->f_mapping);
+	}
+	retval = 0;
+
+out_nomem:
+	spin_unlock(&info->lock);
+	return retval;
+}
+
+static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	file_accessed(file);
+	vma->vm_ops = &shmem_vm_ops;
+	return 0;
+}
+
+static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
+				     umode_t mode, dev_t dev, unsigned long flags)
+{
+	struct inode *inode;
+	struct shmem_inode_info *info;
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+	if (shmem_reserve_inode(sb))
+		return NULL;
+
+	inode = new_inode(sb);
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode_init_owner(inode, dir, mode);
+		inode->i_blocks = 0;
+		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+		inode->i_generation = get_seconds();
+		info = SHMEM_I(inode);
+		memset(info, 0, (char *)inode - (char *)info);
+		spin_lock_init(&info->lock);
+		info->seals = F_SEAL_SEAL;
+		info->flags = flags & VM_NORESERVE;
+		INIT_LIST_HEAD(&info->swaplist);
+		simple_xattrs_init(&info->xattrs);
+		cache_no_acl(inode);
+
+		switch (mode & S_IFMT) {
+		default:
+			inode->i_op = &shmem_special_inode_operations;
+			init_special_inode(inode, mode, dev);
+			break;
+		case S_IFREG:
+			inode->i_mapping->a_ops = &shmem_aops;
+			inode->i_op = &shmem_inode_operations;
+			inode->i_fop = &shmem_file_operations;
+			mpol_shared_policy_init(&info->policy,
+						 shmem_get_sbmpol(sbinfo));
+			break;
+		case S_IFDIR:
+			inc_nlink(inode);
+			/* Some things misbehave if size == 0 on a directory */
+			inode->i_size = 2 * BOGO_DIRENT_SIZE;
+			inode->i_op = &shmem_dir_inode_operations;
+			inode->i_fop = &simple_dir_operations;
+			break;
+		case S_IFLNK:
+			/*
+			 * Must not load anything in the rbtree,
+			 * mpol_free_shared_policy will not be called.
+			 */
+			mpol_shared_policy_init(&info->policy, NULL);
+			break;
+		}
+	} else
+		shmem_free_inode(sb);
+	return inode;
+}
+
+bool shmem_mapping(struct address_space *mapping)
+{
+	if (!mapping->host)
+		return false;
+
+	return mapping->host->i_sb->s_op == &shmem_ops;
+}
+
+#ifdef CONFIG_TMPFS
+static const struct inode_operations shmem_symlink_inode_operations;
+static const struct inode_operations shmem_short_symlink_operations;
+
+#ifdef CONFIG_TMPFS_XATTR
+static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
+#else
+#define shmem_initxattrs NULL
+#endif
+
+static int
+shmem_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	struct inode *inode = mapping->host;
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+
+	/* i_mutex is held by caller */
+	if (unlikely(info->seals)) {
+		if (info->seals & F_SEAL_WRITE)
+			return -EPERM;
+		if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
+			return -EPERM;
+	}
+
+	return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
+}
+
+static int
+shmem_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+
+	if (pos + copied > inode->i_size)
+		i_size_write(inode, pos + copied);
+
+	if (!PageUptodate(page)) {
+		if (copied < PAGE_CACHE_SIZE) {
+			unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+			zero_user_segments(page, 0, from,
+					from + copied, PAGE_CACHE_SIZE);
+		}
+		SetPageUptodate(page);
+	}
+	set_page_dirty(page);
+	unlock_page(page);
+	page_cache_release(page);
+
+	return copied;
+}
+
+static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct address_space *mapping = inode->i_mapping;
+	pgoff_t index;
+	unsigned long offset;
+	enum sgp_type sgp = SGP_READ;
+	int error = 0;
+	ssize_t retval = 0;
+	loff_t *ppos = &iocb->ki_pos;
+
+	/*
+	 * Might this read be for a stacking filesystem?  Then when reading
+	 * holes of a sparse file, we actually need to allocate those pages,
+	 * and even mark them dirty, so it cannot exceed the max_blocks limit.
+	 */
+	if (!iter_is_iovec(to))
+		sgp = SGP_DIRTY;
+
+	index = *ppos >> PAGE_CACHE_SHIFT;
+	offset = *ppos & ~PAGE_CACHE_MASK;
+
+	for (;;) {
+		struct page *page = NULL;
+		pgoff_t end_index;
+		unsigned long nr, ret;
+		loff_t i_size = i_size_read(inode);
+
+		end_index = i_size >> PAGE_CACHE_SHIFT;
+		if (index > end_index)
+			break;
+		if (index == end_index) {
+			nr = i_size & ~PAGE_CACHE_MASK;
+			if (nr <= offset)
+				break;
+		}
+
+		error = shmem_getpage(inode, index, &page, sgp, NULL);
+		if (error) {
+			if (error == -EINVAL)
+				error = 0;
+			break;
+		}
+		if (page)
+			unlock_page(page);
+
+		/*
+		 * We must evaluate after, since reads (unlike writes)
+		 * are called without i_mutex protection against truncate
+		 */
+		nr = PAGE_CACHE_SIZE;
+		i_size = i_size_read(inode);
+		end_index = i_size >> PAGE_CACHE_SHIFT;
+		if (index == end_index) {
+			nr = i_size & ~PAGE_CACHE_MASK;
+			if (nr <= offset) {
+				if (page)
+					page_cache_release(page);
+				break;
+			}
+		}
+		nr -= offset;
+
+		if (page) {
+			/*
+			 * If users can be writing to this page using arbitrary
+			 * virtual addresses, take care about potential aliasing
+			 * before reading the page on the kernel side.
+			 */
+			if (mapping_writably_mapped(mapping))
+				flush_dcache_page(page);
+			/*
+			 * Mark the page accessed if we read the beginning.
+			 */
+			if (!offset)
+				mark_page_accessed(page);
+		} else {
+			page = ZERO_PAGE(0);
+			page_cache_get(page);
+		}
+
+		/*
+		 * Ok, we have the page, and it's up-to-date, so
+		 * now we can copy it to user space...
+		 */
+		ret = copy_page_to_iter(page, offset, nr, to);
+		retval += ret;
+		offset += ret;
+		index += offset >> PAGE_CACHE_SHIFT;
+		offset &= ~PAGE_CACHE_MASK;
+
+		page_cache_release(page);
+		if (!iov_iter_count(to))
+			break;
+		if (ret < nr) {
+			error = -EFAULT;
+			break;
+		}
+		cond_resched();
+	}
+
+	*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
+	file_accessed(file);
+	return retval ? retval : error;
+}
+
+static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
+				struct pipe_inode_info *pipe, size_t len,
+				unsigned int flags)
+{
+	struct address_space *mapping = in->f_mapping;
+	struct inode *inode = mapping->host;
+	unsigned int loff, nr_pages, req_pages;
+	struct page *pages[PIPE_DEF_BUFFERS];
+	struct partial_page partial[PIPE_DEF_BUFFERS];
+	struct page *page;
+	pgoff_t index, end_index;
+	loff_t isize, left;
+	int error, page_nr;
+	struct splice_pipe_desc spd = {
+		.pages = pages,
+		.partial = partial,
+		.nr_pages_max = PIPE_DEF_BUFFERS,
+		.flags = flags,
+		.ops = &page_cache_pipe_buf_ops,
+		.spd_release = spd_release_page,
+	};
+
+	isize = i_size_read(inode);
+	if (unlikely(*ppos >= isize))
+		return 0;
+
+	left = isize - *ppos;
+	if (unlikely(left < len))
+		len = left;
+
+	if (splice_grow_spd(pipe, &spd))
+		return -ENOMEM;
+
+	index = *ppos >> PAGE_CACHE_SHIFT;
+	loff = *ppos & ~PAGE_CACHE_MASK;
+	req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	nr_pages = min(req_pages, spd.nr_pages_max);
+
+	spd.nr_pages = find_get_pages_contig(mapping, index,
+						nr_pages, spd.pages);
+	index += spd.nr_pages;
+	error = 0;
+
+	while (spd.nr_pages < nr_pages) {
+		error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
+		if (error)
+			break;
+		unlock_page(page);
+		spd.pages[spd.nr_pages++] = page;
+		index++;
+	}
+
+	index = *ppos >> PAGE_CACHE_SHIFT;
+	nr_pages = spd.nr_pages;
+	spd.nr_pages = 0;
+
+	for (page_nr = 0; page_nr < nr_pages; page_nr++) {
+		unsigned int this_len;
+
+		if (!len)
+			break;
+
+		this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
+		page = spd.pages[page_nr];
+
+		if (!PageUptodate(page) || page->mapping != mapping) {
+			error = shmem_getpage(inode, index, &page,
+							SGP_CACHE, NULL);
+			if (error)
+				break;
+			unlock_page(page);
+			page_cache_release(spd.pages[page_nr]);
+			spd.pages[page_nr] = page;
+		}
+
+		isize = i_size_read(inode);
+		end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+		if (unlikely(!isize || index > end_index))
+			break;
+
+		if (end_index == index) {
+			unsigned int plen;
+
+			plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
+			if (plen <= loff)
+				break;
+
+			this_len = min(this_len, plen - loff);
+			len = this_len;
+		}
+
+		spd.partial[page_nr].offset = loff;
+		spd.partial[page_nr].len = this_len;
+		len -= this_len;
+		loff = 0;
+		spd.nr_pages++;
+		index++;
+	}
+
+	while (page_nr < nr_pages)
+		page_cache_release(spd.pages[page_nr++]);
+
+	if (spd.nr_pages)
+		error = splice_to_pipe(pipe, &spd);
+
+	splice_shrink_spd(&spd);
+
+	if (error > 0) {
+		*ppos += error;
+		file_accessed(in);
+	}
+	return error;
+}
+
+/*
+ * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
+ */
+static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
+				    pgoff_t index, pgoff_t end, int whence)
+{
+	struct page *page;
+	struct pagevec pvec;
+	pgoff_t indices[PAGEVEC_SIZE];
+	bool done = false;
+	int i;
+
+	pagevec_init(&pvec, 0);
+	pvec.nr = 1;		/* start small: we may be there already */
+	while (!done) {
+		pvec.nr = find_get_entries(mapping, index,
+					pvec.nr, pvec.pages, indices);
+		if (!pvec.nr) {
+			if (whence == SEEK_DATA)
+				index = end;
+			break;
+		}
+		for (i = 0; i < pvec.nr; i++, index++) {
+			if (index < indices[i]) {
+				if (whence == SEEK_HOLE) {
+					done = true;
+					break;
+				}
+				index = indices[i];
+			}
+			page = pvec.pages[i];
+			if (page && !radix_tree_exceptional_entry(page)) {
+				if (!PageUptodate(page))
+					page = NULL;
+			}
+			if (index >= end ||
+			    (page && whence == SEEK_DATA) ||
+			    (!page && whence == SEEK_HOLE)) {
+				done = true;
+				break;
+			}
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		pvec.nr = PAGEVEC_SIZE;
+		cond_resched();
+	}
+	return index;
+}
+
+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	pgoff_t start, end;
+	loff_t new_offset;
+
+	if (whence != SEEK_DATA && whence != SEEK_HOLE)
+		return generic_file_llseek_size(file, offset, whence,
+					MAX_LFS_FILESIZE, i_size_read(inode));
+	mutex_lock(&inode->i_mutex);
+	/* We're holding i_mutex so we can access i_size directly */
+
+	if (offset < 0)
+		offset = -EINVAL;
+	else if (offset >= inode->i_size)
+		offset = -ENXIO;
+	else {
+		start = offset >> PAGE_CACHE_SHIFT;
+		end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+		new_offset = shmem_seek_hole_data(mapping, start, end, whence);
+		new_offset <<= PAGE_CACHE_SHIFT;
+		if (new_offset > offset) {
+			if (new_offset < inode->i_size)
+				offset = new_offset;
+			else if (whence == SEEK_DATA)
+				offset = -ENXIO;
+			else
+				offset = inode->i_size;
+		}
+	}
+
+	if (offset >= 0)
+		offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
+	mutex_unlock(&inode->i_mutex);
+	return offset;
+}
+
+/*
+ * We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
+ * so reuse a tag which we firmly believe is never set or cleared on shmem.
+ */
+#define SHMEM_TAG_PINNED        PAGECACHE_TAG_TOWRITE
+#define LAST_SCAN               4       /* about 150ms max */
+
+static void shmem_tag_pins(struct address_space *mapping)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	pgoff_t start;
+	struct page *page;
+
+	lru_add_drain();
+	start = 0;
+	rcu_read_lock();
+
+restart:
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+		page = radix_tree_deref_slot(slot);
+		if (!page || radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page))
+				goto restart;
+		} else if (page_count(page) - page_mapcount(page) > 1) {
+			spin_lock_irq(&mapping->tree_lock);
+			radix_tree_tag_set(&mapping->page_tree, iter.index,
+					   SHMEM_TAG_PINNED);
+			spin_unlock_irq(&mapping->tree_lock);
+		}
+
+		if (need_resched()) {
+			cond_resched_rcu();
+			start = iter.index + 1;
+			goto restart;
+		}
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * Setting SEAL_WRITE requires us to verify there's no pending writer. However,
+ * via get_user_pages(), drivers might have some pending I/O without any active
+ * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages
+ * and see whether it has an elevated ref-count. If so, we tag them and wait for
+ * them to be dropped.
+ * The caller must guarantee that no new user will acquire writable references
+ * to those pages to avoid races.
+ */
+static int shmem_wait_for_pins(struct address_space *mapping)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	pgoff_t start;
+	struct page *page;
+	int error, scan;
+
+	shmem_tag_pins(mapping);
+
+	error = 0;
+	for (scan = 0; scan <= LAST_SCAN; scan++) {
+		if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED))
+			break;
+
+		if (!scan)
+			lru_add_drain_all();
+		else if (schedule_timeout_killable((HZ << scan) / 200))
+			scan = LAST_SCAN;
+
+		start = 0;
+		rcu_read_lock();
+restart:
+		radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
+					   start, SHMEM_TAG_PINNED) {
+
+			page = radix_tree_deref_slot(slot);
+			if (radix_tree_exception(page)) {
+				if (radix_tree_deref_retry(page))
+					goto restart;
+
+				page = NULL;
+			}
+
+			if (page &&
+			    page_count(page) - page_mapcount(page) != 1) {
+				if (scan < LAST_SCAN)
+					goto continue_resched;
+
+				/*
+				 * On the last scan, we clean up all those tags
+				 * we inserted; but make a note that we still
+				 * found pages pinned.
+				 */
+				error = -EBUSY;
+			}
+
+			spin_lock_irq(&mapping->tree_lock);
+			radix_tree_tag_clear(&mapping->page_tree,
+					     iter.index, SHMEM_TAG_PINNED);
+			spin_unlock_irq(&mapping->tree_lock);
+continue_resched:
+			if (need_resched()) {
+				cond_resched_rcu();
+				start = iter.index + 1;
+				goto restart;
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	return error;
+}
+
+#define F_ALL_SEALS (F_SEAL_SEAL | \
+		     F_SEAL_SHRINK | \
+		     F_SEAL_GROW | \
+		     F_SEAL_WRITE)
+
+int shmem_add_seals(struct file *file, unsigned int seals)
+{
+	struct inode *inode = file_inode(file);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	int error;
+
+	/*
+	 * SEALING
+	 * Sealing allows multiple parties to share a shmem-file but restrict
+	 * access to a specific subset of file operations. Seals can only be
+	 * added, but never removed. This way, mutually untrusted parties can
+	 * share common memory regions with a well-defined policy. A malicious
+	 * peer can thus never perform unwanted operations on a shared object.
+	 *
+	 * Seals are only supported on special shmem-files and always affect
+	 * the whole underlying inode. Once a seal is set, it may prevent some
+	 * kinds of access to the file. Currently, the following seals are
+	 * defined:
+	 *   SEAL_SEAL: Prevent further seals from being set on this file
+	 *   SEAL_SHRINK: Prevent the file from shrinking
+	 *   SEAL_GROW: Prevent the file from growing
+	 *   SEAL_WRITE: Prevent write access to the file
+	 *
+	 * As we don't require any trust relationship between two parties, we
+	 * must prevent seals from being removed. Therefore, sealing a file
+	 * only adds a given set of seals to the file, it never touches
+	 * existing seals. Furthermore, the "setting seals"-operation can be
+	 * sealed itself, which basically prevents any further seal from being
+	 * added.
+	 *
+	 * Semantics of sealing are only defined on volatile files. Only
+	 * anonymous shmem files support sealing. More importantly, seals are
+	 * never written to disk. Therefore, there's no plan to support it on
+	 * other file types.
+	 */
+
+	if (file->f_op != &shmem_file_operations)
+		return -EINVAL;
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EPERM;
+	if (seals & ~(unsigned int)F_ALL_SEALS)
+		return -EINVAL;
+
+	mutex_lock(&inode->i_mutex);
+
+	if (info->seals & F_SEAL_SEAL) {
+		error = -EPERM;
+		goto unlock;
+	}
+
+	if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) {
+		error = mapping_deny_writable(file->f_mapping);
+		if (error)
+			goto unlock;
+
+		error = shmem_wait_for_pins(file->f_mapping);
+		if (error) {
+			mapping_allow_writable(file->f_mapping);
+			goto unlock;
+		}
+	}
+
+	info->seals |= seals;
+	error = 0;
+
+unlock:
+	mutex_unlock(&inode->i_mutex);
+	return error;
+}
+EXPORT_SYMBOL_GPL(shmem_add_seals);
+
+int shmem_get_seals(struct file *file)
+{
+	if (file->f_op != &shmem_file_operations)
+		return -EINVAL;
+
+	return SHMEM_I(file_inode(file))->seals;
+}
+EXPORT_SYMBOL_GPL(shmem_get_seals);
+
+long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	long error;
+
+	switch (cmd) {
+	case F_ADD_SEALS:
+		/* disallow upper 32bit */
+		if (arg > UINT_MAX)
+			return -EINVAL;
+
+		error = shmem_add_seals(file, arg);
+		break;
+	case F_GET_SEALS:
+		error = shmem_get_seals(file);
+		break;
+	default:
+		error = -EINVAL;
+		break;
+	}
+
+	return error;
+}
+
+static long shmem_fallocate(struct file *file, int mode, loff_t offset,
+							 loff_t len)
+{
+	struct inode *inode = file_inode(file);
+	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	struct shmem_falloc shmem_falloc;
+	pgoff_t start, index, end;
+	int error;
+
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+
+	mutex_lock(&inode->i_mutex);
+
+	if (mode & FALLOC_FL_PUNCH_HOLE) {
+		struct address_space *mapping = file->f_mapping;
+		loff_t unmap_start = round_up(offset, PAGE_SIZE);
+		loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
+		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
+
+		/* protected by i_mutex */
+		if (info->seals & F_SEAL_WRITE) {
+			error = -EPERM;
+			goto out;
+		}
+
+		shmem_falloc.waitq = &shmem_falloc_waitq;
+		shmem_falloc.start = unmap_start >> PAGE_SHIFT;
+		shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
+		spin_lock(&inode->i_lock);
+		inode->i_private = &shmem_falloc;
+		spin_unlock(&inode->i_lock);
+
+		if ((u64)unmap_end > (u64)unmap_start)
+			unmap_mapping_range(mapping, unmap_start,
+					    1 + unmap_end - unmap_start, 0);
+		shmem_truncate_range(inode, offset, offset + len - 1);
+		/* No need to unmap again: hole-punching leaves COWed pages */
+
+		spin_lock(&inode->i_lock);
+		inode->i_private = NULL;
+		wake_up_all(&shmem_falloc_waitq);
+		spin_unlock(&inode->i_lock);
+		error = 0;
+		goto out;
+	}
+
+	/* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
+	error = inode_newsize_ok(inode, offset + len);
+	if (error)
+		goto out;
+
+	if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
+		error = -EPERM;
+		goto out;
+	}
+
+	start = offset >> PAGE_CACHE_SHIFT;
+	end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	/* Try to avoid a swapstorm if len is impossible to satisfy */
+	if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
+		error = -ENOSPC;
+		goto out;
+	}
+
+	shmem_falloc.waitq = NULL;
+	shmem_falloc.start = start;
+	shmem_falloc.next  = start;
+	shmem_falloc.nr_falloced = 0;
+	shmem_falloc.nr_unswapped = 0;
+	spin_lock(&inode->i_lock);
+	inode->i_private = &shmem_falloc;
+	spin_unlock(&inode->i_lock);
+
+	for (index = start; index < end; index++) {
+		struct page *page;
+
+		/*
+		 * Good, the fallocate(2) manpage permits EINTR: we may have
+		 * been interrupted because we are using up too much memory.
+		 */
+		if (signal_pending(current))
+			error = -EINTR;
+		else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
+			error = -ENOMEM;
+		else
+			error = shmem_getpage(inode, index, &page, SGP_FALLOC,
+									NULL);
+		if (error) {
+			/* Remove the !PageUptodate pages we added */
+			if (index > start) {
+				shmem_undo_range(inode,
+				 (loff_t)start << PAGE_CACHE_SHIFT,
+				 ((loff_t)index << PAGE_CACHE_SHIFT) - 1, true);
+			}
+			goto undone;
+		}
+
+		/*
+		 * Inform shmem_writepage() how far we have reached.
+		 * No need for lock or barrier: we have the page lock.
+		 */
+		shmem_falloc.next++;
+		if (!PageUptodate(page))
+			shmem_falloc.nr_falloced++;
+
+		/*
+		 * If !PageUptodate, leave it that way so that freeable pages
+		 * can be recognized if we need to rollback on error later.
+		 * But set_page_dirty so that memory pressure will swap rather
+		 * than free the pages we are allocating (and SGP_CACHE pages
+		 * might still be clean: we now need to mark those dirty too).
+		 */
+		set_page_dirty(page);
+		unlock_page(page);
+		page_cache_release(page);
+		cond_resched();
+	}
+
+	if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
+		i_size_write(inode, offset + len);
+	inode->i_ctime = CURRENT_TIME;
+undone:
+	spin_lock(&inode->i_lock);
+	inode->i_private = NULL;
+	spin_unlock(&inode->i_lock);
+out:
+	mutex_unlock(&inode->i_mutex);
+	return error;
+}
+
+static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
+
+	buf->f_type = TMPFS_MAGIC;
+	buf->f_bsize = PAGE_CACHE_SIZE;
+	buf->f_namelen = NAME_MAX;
+	if (sbinfo->max_blocks) {
+		buf->f_blocks = sbinfo->max_blocks;
+		buf->f_bavail =
+		buf->f_bfree  = sbinfo->max_blocks -
+				percpu_counter_sum(&sbinfo->used_blocks);
+	}
+	if (sbinfo->max_inodes) {
+		buf->f_files = sbinfo->max_inodes;
+		buf->f_ffree = sbinfo->free_inodes;
+	}
+	/* else leave those fields 0 like simple_statfs */
+	return 0;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+static int
+shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
+{
+	struct inode *inode;
+	int error = -ENOSPC;
+
+	inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
+	if (inode) {
+		error = simple_acl_create(dir, inode);
+		if (error)
+			goto out_iput;
+		error = security_inode_init_security(inode, dir,
+						     &dentry->d_name,
+						     shmem_initxattrs, NULL);
+		if (error && error != -EOPNOTSUPP)
+			goto out_iput;
+
+		error = 0;
+		dir->i_size += BOGO_DIRENT_SIZE;
+		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+		d_instantiate(dentry, inode);
+		dget(dentry); /* Extra count - pin the dentry in core */
+	}
+	return error;
+out_iput:
+	iput(inode);
+	return error;
+}
+
+static int
+shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	struct inode *inode;
+	int error = -ENOSPC;
+
+	inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
+	if (inode) {
+		error = security_inode_init_security(inode, dir,
+						     NULL,
+						     shmem_initxattrs, NULL);
+		if (error && error != -EOPNOTSUPP)
+			goto out_iput;
+		error = simple_acl_create(dir, inode);
+		if (error)
+			goto out_iput;
+		d_tmpfile(dentry, inode);
+	}
+	return error;
+out_iput:
+	iput(inode);
+	return error;
+}
+
+static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	int error;
+
+	if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
+		return error;
+	inc_nlink(dir);
+	return 0;
+}
+
+static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+		bool excl)
+{
+	return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
+}
+
+/*
+ * Link a file..
+ */
+static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(old_dentry);
+	int ret;
+
+	/*
+	 * No ordinary (disk based) filesystem counts links as inodes;
+	 * but each new link needs a new dentry, pinning lowmem, and
+	 * tmpfs dentries cannot be pruned until they are unlinked.
+	 */
+	ret = shmem_reserve_inode(inode->i_sb);
+	if (ret)
+		goto out;
+
+	dir->i_size += BOGO_DIRENT_SIZE;
+	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+	inc_nlink(inode);
+	ihold(inode);	/* New dentry reference */
+	dget(dentry);		/* Extra pinning count for the created dentry */
+	d_instantiate(dentry, inode);
+out:
+	return ret;
+}
+
+static int shmem_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+
+	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
+		shmem_free_inode(inode->i_sb);
+
+	dir->i_size -= BOGO_DIRENT_SIZE;
+	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+	drop_nlink(inode);
+	dput(dentry);	/* Undo the count from "create" - this does all the work */
+	return 0;
+}
+
+static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	if (!simple_empty(dentry))
+		return -ENOTEMPTY;
+
+	drop_nlink(d_inode(dentry));
+	drop_nlink(dir);
+	return shmem_unlink(dir, dentry);
+}
+
+static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
+{
+	bool old_is_dir = d_is_dir(old_dentry);
+	bool new_is_dir = d_is_dir(new_dentry);
+
+	if (old_dir != new_dir && old_is_dir != new_is_dir) {
+		if (old_is_dir) {
+			drop_nlink(old_dir);
+			inc_nlink(new_dir);
+		} else {
+			drop_nlink(new_dir);
+			inc_nlink(old_dir);
+		}
+	}
+	old_dir->i_ctime = old_dir->i_mtime =
+	new_dir->i_ctime = new_dir->i_mtime =
+	d_inode(old_dentry)->i_ctime =
+	d_inode(new_dentry)->i_ctime = CURRENT_TIME;
+
+	return 0;
+}
+
+static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
+{
+	struct dentry *whiteout;
+	int error;
+
+	whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
+	if (!whiteout)
+		return -ENOMEM;
+
+	error = shmem_mknod(old_dir, whiteout,
+			    S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+	dput(whiteout);
+	if (error)
+		return error;
+
+	/*
+	 * Cheat and hash the whiteout while the old dentry is still in
+	 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
+	 *
+	 * d_lookup() will consistently find one of them at this point,
+	 * not sure which one, but that isn't even important.
+	 */
+	d_rehash(whiteout);
+	return 0;
+}
+
+/*
+ * The VFS layer already does all the dentry stuff for rename,
+ * we just have to decrement the usage count for the target if
+ * it exists so that the VFS layer correctly free's it when it
+ * gets overwritten.
+ */
+static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
+{
+	struct inode *inode = d_inode(old_dentry);
+	int they_are_dirs = S_ISDIR(inode->i_mode);
+
+	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
+		return -EINVAL;
+
+	if (flags & RENAME_EXCHANGE)
+		return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
+
+	if (!simple_empty(new_dentry))
+		return -ENOTEMPTY;
+
+	if (flags & RENAME_WHITEOUT) {
+		int error;
+
+		error = shmem_whiteout(old_dir, old_dentry);
+		if (error)
+			return error;
+	}
+
+	if (d_really_is_positive(new_dentry)) {
+		(void) shmem_unlink(new_dir, new_dentry);
+		if (they_are_dirs) {
+			drop_nlink(d_inode(new_dentry));
+			drop_nlink(old_dir);
+		}
+	} else if (they_are_dirs) {
+		drop_nlink(old_dir);
+		inc_nlink(new_dir);
+	}
+
+	old_dir->i_size -= BOGO_DIRENT_SIZE;
+	new_dir->i_size += BOGO_DIRENT_SIZE;
+	old_dir->i_ctime = old_dir->i_mtime =
+	new_dir->i_ctime = new_dir->i_mtime =
+	inode->i_ctime = CURRENT_TIME;
+	return 0;
+}
+
+static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+	int error;
+	int len;
+	struct inode *inode;
+	struct page *page;
+	char *kaddr;
+	struct shmem_inode_info *info;
+
+	len = strlen(symname) + 1;
+	if (len > PAGE_CACHE_SIZE)
+		return -ENAMETOOLONG;
+
+	inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
+	if (!inode)
+		return -ENOSPC;
+
+	error = security_inode_init_security(inode, dir, &dentry->d_name,
+					     shmem_initxattrs, NULL);
+	if (error) {
+		if (error != -EOPNOTSUPP) {
+			iput(inode);
+			return error;
+		}
+		error = 0;
+	}
+
+	info = SHMEM_I(inode);
+	inode->i_size = len-1;
+	if (len <= SHORT_SYMLINK_LEN) {
+		inode->i_link = kmemdup(symname, len, GFP_KERNEL);
+		if (!inode->i_link) {
+			iput(inode);
+			return -ENOMEM;
+		}
+		inode->i_op = &shmem_short_symlink_operations;
+	} else {
+		error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
+		if (error) {
+			iput(inode);
+			return error;
+		}
+		inode->i_mapping->a_ops = &shmem_aops;
+		inode->i_op = &shmem_symlink_inode_operations;
+		kaddr = kmap_atomic(page);
+		memcpy(kaddr, symname, len);
+		kunmap_atomic(kaddr);
+		SetPageUptodate(page);
+		set_page_dirty(page);
+		unlock_page(page);
+		page_cache_release(page);
+	}
+	dir->i_size += BOGO_DIRENT_SIZE;
+	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+	d_instantiate(dentry, inode);
+	dget(dentry);
+	return 0;
+}
+
+static const char *shmem_follow_link(struct dentry *dentry, void **cookie)
+{
+	struct page *page = NULL;
+	int error = shmem_getpage(d_inode(dentry), 0, &page, SGP_READ, NULL);
+	if (error)
+		return ERR_PTR(error);
+	unlock_page(page);
+	*cookie = page;
+	return kmap(page);
+}
+
+static void shmem_put_link(struct inode *unused, void *cookie)
+{
+	struct page *page = cookie;
+	kunmap(page);
+	mark_page_accessed(page);
+	page_cache_release(page);
+}
+
+#ifdef CONFIG_TMPFS_XATTR
+/*
+ * Superblocks without xattr inode operations may get some security.* xattr
+ * support from the LSM "for free". As soon as we have any other xattrs
+ * like ACLs, we also need to implement the security.* handlers at
+ * filesystem level, though.
+ */
+
+/*
+ * Callback for security_inode_init_security() for acquiring xattrs.
+ */
+static int shmem_initxattrs(struct inode *inode,
+			    const struct xattr *xattr_array,
+			    void *fs_info)
+{
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	const struct xattr *xattr;
+	struct simple_xattr *new_xattr;
+	size_t len;
+
+	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+		new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
+		if (!new_xattr)
+			return -ENOMEM;
+
+		len = strlen(xattr->name) + 1;
+		new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
+					  GFP_KERNEL);
+		if (!new_xattr->name) {
+			kfree(new_xattr);
+			return -ENOMEM;
+		}
+
+		memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
+		       XATTR_SECURITY_PREFIX_LEN);
+		memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
+		       xattr->name, len);
+
+		simple_xattr_list_add(&info->xattrs, new_xattr);
+	}
+
+	return 0;
+}
+
+static const struct xattr_handler *shmem_xattr_handlers[] = {
+#ifdef CONFIG_TMPFS_POSIX_ACL
+	&posix_acl_access_xattr_handler,
+	&posix_acl_default_xattr_handler,
+#endif
+	NULL
+};
+
+static int shmem_xattr_validate(const char *name)
+{
+	struct { const char *prefix; size_t len; } arr[] = {
+		{ XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
+		{ XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
+	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(arr); i++) {
+		size_t preflen = arr[i].len;
+		if (strncmp(name, arr[i].prefix, preflen) == 0) {
+			if (!name[preflen])
+				return -EINVAL;
+			return 0;
+		}
+	}
+	return -EOPNOTSUPP;
+}
+
+static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
+			      void *buffer, size_t size)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+	int err;
+
+	/*
+	 * If this is a request for a synthetic attribute in the system.*
+	 * namespace use the generic infrastructure to resolve a handler
+	 * for it via sb->s_xattr.
+	 */
+	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return generic_getxattr(dentry, name, buffer, size);
+
+	err = shmem_xattr_validate(name);
+	if (err)
+		return err;
+
+	return simple_xattr_get(&info->xattrs, name, buffer, size);
+}
+
+static int shmem_setxattr(struct dentry *dentry, const char *name,
+			  const void *value, size_t size, int flags)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+	int err;
+
+	/*
+	 * If this is a request for a synthetic attribute in the system.*
+	 * namespace use the generic infrastructure to resolve a handler
+	 * for it via sb->s_xattr.
+	 */
+	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return generic_setxattr(dentry, name, value, size, flags);
+
+	err = shmem_xattr_validate(name);
+	if (err)
+		return err;
+
+	return simple_xattr_set(&info->xattrs, name, value, size, flags);
+}
+
+static int shmem_removexattr(struct dentry *dentry, const char *name)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+	int err;
+
+	/*
+	 * If this is a request for a synthetic attribute in the system.*
+	 * namespace use the generic infrastructure to resolve a handler
+	 * for it via sb->s_xattr.
+	 */
+	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return generic_removexattr(dentry, name);
+
+	err = shmem_xattr_validate(name);
+	if (err)
+		return err;
+
+	return simple_xattr_remove(&info->xattrs, name);
+}
+
+static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+	return simple_xattr_list(&info->xattrs, buffer, size);
+}
+#endif /* CONFIG_TMPFS_XATTR */
+
+static const struct inode_operations shmem_short_symlink_operations = {
+	.readlink	= generic_readlink,
+	.follow_link	= simple_follow_link,
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+};
+
+static const struct inode_operations shmem_symlink_inode_operations = {
+	.readlink	= generic_readlink,
+	.follow_link	= shmem_follow_link,
+	.put_link	= shmem_put_link,
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+};
+
+static struct dentry *shmem_get_parent(struct dentry *child)
+{
+	return ERR_PTR(-ESTALE);
+}
+
+static int shmem_match(struct inode *ino, void *vfh)
+{
+	__u32 *fh = vfh;
+	__u64 inum = fh[2];
+	inum = (inum << 32) | fh[1];
+	return ino->i_ino == inum && fh[0] == ino->i_generation;
+}
+
+static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
+		struct fid *fid, int fh_len, int fh_type)
+{
+	struct inode *inode;
+	struct dentry *dentry = NULL;
+	u64 inum;
+
+	if (fh_len < 3)
+		return NULL;
+
+	inum = fid->raw[2];
+	inum = (inum << 32) | fid->raw[1];
+
+	inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
+			shmem_match, fid->raw);
+	if (inode) {
+		dentry = d_find_alias(inode);
+		iput(inode);
+	}
+
+	return dentry;
+}
+
+static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
+				struct inode *parent)
+{
+	if (*len < 3) {
+		*len = 3;
+		return FILEID_INVALID;
+	}
+
+	if (inode_unhashed(inode)) {
+		/* Unfortunately insert_inode_hash is not idempotent,
+		 * so as we hash inodes here rather than at creation
+		 * time, we need a lock to ensure we only try
+		 * to do it once
+		 */
+		static DEFINE_SPINLOCK(lock);
+		spin_lock(&lock);
+		if (inode_unhashed(inode))
+			__insert_inode_hash(inode,
+					    inode->i_ino + inode->i_generation);
+		spin_unlock(&lock);
+	}
+
+	fh[0] = inode->i_generation;
+	fh[1] = inode->i_ino;
+	fh[2] = ((__u64)inode->i_ino) >> 32;
+
+	*len = 3;
+	return 1;
+}
+
+static const struct export_operations shmem_export_ops = {
+	.get_parent     = shmem_get_parent,
+	.encode_fh      = shmem_encode_fh,
+	.fh_to_dentry	= shmem_fh_to_dentry,
+};
+
+static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
+			       bool remount)
+{
+	char *this_char, *value, *rest;
+	struct mempolicy *mpol = NULL;
+	uid_t uid;
+	gid_t gid;
+
+	while (options != NULL) {
+		this_char = options;
+		for (;;) {
+			/*
+			 * NUL-terminate this option: unfortunately,
+			 * mount options form a comma-separated list,
+			 * but mpol's nodelist may also contain commas.
+			 */
+			options = strchr(options, ',');
+			if (options == NULL)
+				break;
+			options++;
+			if (!isdigit(*options)) {
+				options[-1] = '\0';
+				break;
+			}
+		}
+		if (!*this_char)
+			continue;
+		if ((value = strchr(this_char,'=')) != NULL) {
+			*value++ = 0;
+		} else {
+			printk(KERN_ERR
+			    "tmpfs: No value for mount option '%s'\n",
+			    this_char);
+			goto error;
+		}
+
+		if (!strcmp(this_char,"size")) {
+			unsigned long long size;
+			size = memparse(value,&rest);
+			if (*rest == '%') {
+				size <<= PAGE_SHIFT;
+				size *= totalram_pages;
+				do_div(size, 100);
+				rest++;
+			}
+			if (*rest)
+				goto bad_val;
+			sbinfo->max_blocks =
+				DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
+		} else if (!strcmp(this_char,"nr_blocks")) {
+			sbinfo->max_blocks = memparse(value, &rest);
+			if (*rest)
+				goto bad_val;
+		} else if (!strcmp(this_char,"nr_inodes")) {
+			sbinfo->max_inodes = memparse(value, &rest);
+			if (*rest)
+				goto bad_val;
+		} else if (!strcmp(this_char,"mode")) {
+			if (remount)
+				continue;
+			sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
+			if (*rest)
+				goto bad_val;
+		} else if (!strcmp(this_char,"uid")) {
+			if (remount)
+				continue;
+			uid = simple_strtoul(value, &rest, 0);
+			if (*rest)
+				goto bad_val;
+			sbinfo->uid = make_kuid(current_user_ns(), uid);
+			if (!uid_valid(sbinfo->uid))
+				goto bad_val;
+		} else if (!strcmp(this_char,"gid")) {
+			if (remount)
+				continue;
+			gid = simple_strtoul(value, &rest, 0);
+			if (*rest)
+				goto bad_val;
+			sbinfo->gid = make_kgid(current_user_ns(), gid);
+			if (!gid_valid(sbinfo->gid))
+				goto bad_val;
+		} else if (!strcmp(this_char,"mpol")) {
+			mpol_put(mpol);
+			mpol = NULL;
+			if (mpol_parse_str(value, &mpol))
+				goto bad_val;
+		} else {
+			printk(KERN_ERR "tmpfs: Bad mount option %s\n",
+			       this_char);
+			goto error;
+		}
+	}
+	sbinfo->mpol = mpol;
+	return 0;
+
+bad_val:
+	printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
+	       value, this_char);
+error:
+	mpol_put(mpol);
+	return 1;
+
+}
+
+static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+	struct shmem_sb_info config = *sbinfo;
+	unsigned long inodes;
+	int error = -EINVAL;
+
+	config.mpol = NULL;
+	if (shmem_parse_options(data, &config, true))
+		return error;
+
+	spin_lock(&sbinfo->stat_lock);
+	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
+	if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
+		goto out;
+	if (config.max_inodes < inodes)
+		goto out;
+	/*
+	 * Those tests disallow limited->unlimited while any are in use;
+	 * but we must separately disallow unlimited->limited, because
+	 * in that case we have no record of how much is already in use.
+	 */
+	if (config.max_blocks && !sbinfo->max_blocks)
+		goto out;
+	if (config.max_inodes && !sbinfo->max_inodes)
+		goto out;
+
+	error = 0;
+	sbinfo->max_blocks  = config.max_blocks;
+	sbinfo->max_inodes  = config.max_inodes;
+	sbinfo->free_inodes = config.max_inodes - inodes;
+
+	/*
+	 * Preserve previous mempolicy unless mpol remount option was specified.
+	 */
+	if (config.mpol) {
+		mpol_put(sbinfo->mpol);
+		sbinfo->mpol = config.mpol;	/* transfers initial ref */
+	}
+out:
+	spin_unlock(&sbinfo->stat_lock);
+	return error;
+}
+
+static int shmem_show_options(struct seq_file *seq, struct dentry *root)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
+
+	if (sbinfo->max_blocks != shmem_default_max_blocks())
+		seq_printf(seq, ",size=%luk",
+			sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
+	if (sbinfo->max_inodes != shmem_default_max_inodes())
+		seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
+	if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
+		seq_printf(seq, ",mode=%03ho", sbinfo->mode);
+	if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
+		seq_printf(seq, ",uid=%u",
+				from_kuid_munged(&init_user_ns, sbinfo->uid));
+	if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
+		seq_printf(seq, ",gid=%u",
+				from_kgid_munged(&init_user_ns, sbinfo->gid));
+	shmem_show_mpol(seq, sbinfo->mpol);
+	return 0;
+}
+
+#define MFD_NAME_PREFIX "memfd:"
+#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
+#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
+
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
+
+SYSCALL_DEFINE2(memfd_create,
+		const char __user *, uname,
+		unsigned int, flags)
+{
+	struct shmem_inode_info *info;
+	struct file *file;
+	int fd, error;
+	char *name;
+	long len;
+
+	if (flags & ~(unsigned int)MFD_ALL_FLAGS)
+		return -EINVAL;
+
+	/* length includes terminating zero */
+	len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
+	if (len <= 0)
+		return -EFAULT;
+	if (len > MFD_NAME_MAX_LEN + 1)
+		return -EINVAL;
+
+	name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
+	if (!name)
+		return -ENOMEM;
+
+	strcpy(name, MFD_NAME_PREFIX);
+	if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
+		error = -EFAULT;
+		goto err_name;
+	}
+
+	/* terminating-zero may have changed after strnlen_user() returned */
+	if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
+		error = -EFAULT;
+		goto err_name;
+	}
+
+	fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
+	if (fd < 0) {
+		error = fd;
+		goto err_name;
+	}
+
+	file = shmem_file_setup(name, 0, VM_NORESERVE);
+	if (IS_ERR(file)) {
+		error = PTR_ERR(file);
+		goto err_fd;
+	}
+	info = SHMEM_I(file_inode(file));
+	file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
+	file->f_flags |= O_RDWR | O_LARGEFILE;
+	if (flags & MFD_ALLOW_SEALING)
+		info->seals &= ~F_SEAL_SEAL;
+
+	fd_install(fd, file);
+	kfree(name);
+	return fd;
+
+err_fd:
+	put_unused_fd(fd);
+err_name:
+	kfree(name);
+	return error;
+}
+
+#endif /* CONFIG_TMPFS */
+
+static void shmem_put_super(struct super_block *sb)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+	percpu_counter_destroy(&sbinfo->used_blocks);
+	mpol_put(sbinfo->mpol);
+	kfree(sbinfo);
+	sb->s_fs_info = NULL;
+}
+
+int shmem_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+	struct shmem_sb_info *sbinfo;
+	int err = -ENOMEM;
+
+	/* Round up to L1_CACHE_BYTES to resist false sharing */
+	sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
+				L1_CACHE_BYTES), GFP_KERNEL);
+	if (!sbinfo)
+		return -ENOMEM;
+
+	sbinfo->mode = S_IRWXUGO | S_ISVTX;
+	sbinfo->uid = current_fsuid();
+	sbinfo->gid = current_fsgid();
+	sb->s_fs_info = sbinfo;
+
+#ifdef CONFIG_TMPFS
+	/*
+	 * Per default we only allow half of the physical ram per
+	 * tmpfs instance, limiting inodes to one per page of lowmem;
+	 * but the internal instance is left unlimited.
+	 */
+	if (!(sb->s_flags & MS_KERNMOUNT)) {
+		sbinfo->max_blocks = shmem_default_max_blocks();
+		sbinfo->max_inodes = shmem_default_max_inodes();
+		if (shmem_parse_options(data, sbinfo, false)) {
+			err = -EINVAL;
+			goto failed;
+		}
+	} else {
+		sb->s_flags |= MS_NOUSER;
+	}
+	sb->s_export_op = &shmem_export_ops;
+	sb->s_flags |= MS_NOSEC;
+#else
+	sb->s_flags |= MS_NOUSER;
+#endif
+
+	spin_lock_init(&sbinfo->stat_lock);
+	if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
+		goto failed;
+	sbinfo->free_inodes = sbinfo->max_inodes;
+
+	sb->s_maxbytes = MAX_LFS_FILESIZE;
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = TMPFS_MAGIC;
+	sb->s_op = &shmem_ops;
+	sb->s_time_gran = 1;
+#ifdef CONFIG_TMPFS_XATTR
+	sb->s_xattr = shmem_xattr_handlers;
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+	sb->s_flags |= MS_POSIXACL;
+#endif
+
+	inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
+	if (!inode)
+		goto failed;
+	inode->i_uid = sbinfo->uid;
+	inode->i_gid = sbinfo->gid;
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		goto failed;
+	return 0;
+
+failed:
+	shmem_put_super(sb);
+	return err;
+}
+
+static struct kmem_cache *shmem_inode_cachep;
+
+static struct inode *shmem_alloc_inode(struct super_block *sb)
+{
+	struct shmem_inode_info *info;
+	info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
+	if (!info)
+		return NULL;
+	return &info->vfs_inode;
+}
+
+static void shmem_destroy_callback(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	kfree(inode->i_link);
+	kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
+}
+
+static void shmem_destroy_inode(struct inode *inode)
+{
+	if (S_ISREG(inode->i_mode))
+		mpol_free_shared_policy(&SHMEM_I(inode)->policy);
+	call_rcu(&inode->i_rcu, shmem_destroy_callback);
+}
+
+static void shmem_init_inode(void *foo)
+{
+	struct shmem_inode_info *info = foo;
+	inode_init_once(&info->vfs_inode);
+}
+
+static int shmem_init_inodecache(void)
+{
+	shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
+				sizeof(struct shmem_inode_info),
+				0, SLAB_PANIC, shmem_init_inode);
+	return 0;
+}
+
+static void shmem_destroy_inodecache(void)
+{
+	kmem_cache_destroy(shmem_inode_cachep);
+}
+
+static const struct address_space_operations shmem_aops = {
+	.writepage	= shmem_writepage,
+	.set_page_dirty	= __set_page_dirty_no_writeback,
+#ifdef CONFIG_TMPFS
+	.write_begin	= shmem_write_begin,
+	.write_end	= shmem_write_end,
+#endif
+#ifdef CONFIG_MIGRATION
+	.migratepage	= migrate_page,
+#endif
+	.error_remove_page = generic_error_remove_page,
+};
+
+static const struct file_operations shmem_file_operations = {
+	.mmap		= shmem_mmap,
+#ifdef CONFIG_TMPFS
+	.llseek		= shmem_file_llseek,
+	.read_iter	= shmem_file_read_iter,
+	.write_iter	= generic_file_write_iter,
+	.fsync		= noop_fsync,
+	.splice_read	= shmem_file_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.fallocate	= shmem_fallocate,
+#endif
+};
+
+static const struct inode_operations shmem_inode_operations = {
+	.getattr	= shmem_getattr,
+	.setattr	= shmem_setattr,
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+	.set_acl	= simple_set_acl,
+#endif
+};
+
+static const struct inode_operations shmem_dir_inode_operations = {
+#ifdef CONFIG_TMPFS
+	.create		= shmem_create,
+	.lookup		= simple_lookup,
+	.link		= shmem_link,
+	.unlink		= shmem_unlink,
+	.symlink	= shmem_symlink,
+	.mkdir		= shmem_mkdir,
+	.rmdir		= shmem_rmdir,
+	.mknod		= shmem_mknod,
+	.rename2	= shmem_rename2,
+	.tmpfile	= shmem_tmpfile,
+#endif
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+	.setattr	= shmem_setattr,
+	.set_acl	= simple_set_acl,
+#endif
+};
+
+static const struct inode_operations shmem_special_inode_operations = {
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+	.setattr	= shmem_setattr,
+	.set_acl	= simple_set_acl,
+#endif
+};
+
+static const struct super_operations shmem_ops = {
+	.alloc_inode	= shmem_alloc_inode,
+	.destroy_inode	= shmem_destroy_inode,
+#ifdef CONFIG_TMPFS
+	.statfs		= shmem_statfs,
+	.remount_fs	= shmem_remount_fs,
+	.show_options	= shmem_show_options,
+#endif
+	.evict_inode	= shmem_evict_inode,
+	.drop_inode	= generic_delete_inode,
+	.put_super	= shmem_put_super,
+};
+
+static const struct vm_operations_struct shmem_vm_ops = {
+	.fault		= shmem_fault,
+	.map_pages	= filemap_map_pages,
+#ifdef CONFIG_NUMA
+	.set_policy     = shmem_set_policy,
+	.get_policy     = shmem_get_policy,
+#endif
+};
+
+static struct dentry *shmem_mount(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	return mount_nodev(fs_type, flags, data, shmem_fill_super);
+}
+
+static struct file_system_type shmem_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "tmpfs",
+	.mount		= shmem_mount,
+	.kill_sb	= kill_litter_super,
+	.fs_flags	= FS_USERNS_MOUNT,
+};
+
+int __init shmem_init(void)
+{
+	int error;
+
+	/* If rootfs called this, don't re-init */
+	if (shmem_inode_cachep)
+		return 0;
+
+	error = shmem_init_inodecache();
+	if (error)
+		goto out3;
+
+	error = register_filesystem(&shmem_fs_type);
+	if (error) {
+		printk(KERN_ERR "Could not register tmpfs\n");
+		goto out2;
+	}
+
+	shm_mnt = kern_mount(&shmem_fs_type);
+	if (IS_ERR(shm_mnt)) {
+		error = PTR_ERR(shm_mnt);
+		printk(KERN_ERR "Could not kern_mount tmpfs\n");
+		goto out1;
+	}
+	return 0;
+
+out1:
+	unregister_filesystem(&shmem_fs_type);
+out2:
+	shmem_destroy_inodecache();
+out3:
+	shm_mnt = ERR_PTR(error);
+	return error;
+}
+
+#else /* !CONFIG_SHMEM */
+
+/*
+ * tiny-shmem: simple shmemfs and tmpfs using ramfs code
+ *
+ * This is intended for small system where the benefits of the full
+ * shmem code (swap-backed and resource-limited) are outweighed by
+ * their complexity. On systems without swap this code should be
+ * effectively equivalent, but much lighter weight.
+ */
+
+static struct file_system_type shmem_fs_type = {
+	.name		= "tmpfs",
+	.mount		= ramfs_mount,
+	.kill_sb	= kill_litter_super,
+	.fs_flags	= FS_USERNS_MOUNT,
+};
+
+int __init shmem_init(void)
+{
+	BUG_ON(register_filesystem(&shmem_fs_type) != 0);
+
+	shm_mnt = kern_mount(&shmem_fs_type);
+	BUG_ON(IS_ERR(shm_mnt));
+
+	return 0;
+}
+
+int shmem_unuse(swp_entry_t swap, struct page *page)
+{
+	return 0;
+}
+
+int shmem_lock(struct file *file, int lock, struct user_struct *user)
+{
+	return 0;
+}
+
+void shmem_unlock_mapping(struct address_space *mapping)
+{
+}
+
+void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+	truncate_inode_pages_range(inode->i_mapping, lstart, lend);
+}
+EXPORT_SYMBOL_GPL(shmem_truncate_range);
+
+#define shmem_vm_ops				generic_file_vm_ops
+#define shmem_file_operations			ramfs_file_operations
+#define shmem_get_inode(sb, dir, mode, dev, flags)	ramfs_get_inode(sb, dir, mode, dev)
+#define shmem_acct_size(flags, size)		0
+#define shmem_unacct_size(flags, size)		do {} while (0)
+
+#endif /* CONFIG_SHMEM */
+
+/* common code */
+
+static struct dentry_operations anon_ops = {
+	.d_dname = simple_dname
+};
+
+static struct file *__shmem_file_setup(const char *name, loff_t size,
+				       unsigned long flags, unsigned int i_flags)
+{
+	struct file *res;
+	struct inode *inode;
+	struct path path;
+	struct super_block *sb;
+	struct qstr this;
+
+	if (IS_ERR(shm_mnt))
+		return ERR_CAST(shm_mnt);
+
+	if (size < 0 || size > MAX_LFS_FILESIZE)
+		return ERR_PTR(-EINVAL);
+
+	if (shmem_acct_size(flags, size))
+		return ERR_PTR(-ENOMEM);
+
+	res = ERR_PTR(-ENOMEM);
+	this.name = name;
+	this.len = strlen(name);
+	this.hash = 0; /* will go */
+	sb = shm_mnt->mnt_sb;
+	path.mnt = mntget(shm_mnt);
+	path.dentry = d_alloc_pseudo(sb, &this);
+	if (!path.dentry)
+		goto put_memory;
+	d_set_d_op(path.dentry, &anon_ops);
+
+	res = ERR_PTR(-ENOSPC);
+	inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
+	if (!inode)
+		goto put_memory;
+
+	inode->i_flags |= i_flags;
+	d_instantiate(path.dentry, inode);
+	inode->i_size = size;
+	clear_nlink(inode);	/* It is unlinked */
+	res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
+	if (IS_ERR(res))
+		goto put_path;
+
+	res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
+		  &shmem_file_operations);
+	if (IS_ERR(res))
+		goto put_path;
+
+	return res;
+
+put_memory:
+	shmem_unacct_size(flags, size);
+put_path:
+	path_put(&path);
+	return res;
+}
+
+/**
+ * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
+ * 	kernel internal.  There will be NO LSM permission checks against the
+ * 	underlying inode.  So users of this interface must do LSM checks at a
+ *	higher layer.  The users are the big_key and shm implementations.  LSM
+ *	checks are provided at the key or shm level rather than the inode.
+ * @name: name for dentry (to be seen in /proc/<pid>/maps
+ * @size: size to be set for the file
+ * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
+ */
+struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
+{
+	return __shmem_file_setup(name, size, flags, S_PRIVATE);
+}
+
+/**
+ * shmem_file_setup - get an unlinked file living in tmpfs
+ * @name: name for dentry (to be seen in /proc/<pid>/maps
+ * @size: size to be set for the file
+ * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
+ */
+struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
+{
+	return __shmem_file_setup(name, size, flags, 0);
+}
+EXPORT_SYMBOL_GPL(shmem_file_setup);
+
+/**
+ * shmem_zero_setup - setup a shared anonymous mapping
+ * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
+ */
+int shmem_zero_setup(struct vm_area_struct *vma)
+{
+	struct file *file;
+	loff_t size = vma->vm_end - vma->vm_start;
+
+	/*
+	 * Cloning a new file under mmap_sem leads to a lock ordering conflict
+	 * between XFS directory reading and selinux: since this file is only
+	 * accessible to the user through its mapping, use S_PRIVATE flag to
+	 * bypass file security, in the same way as shmem_kernel_file_setup().
+	 */
+	file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	if (vma->vm_file)
+		fput(vma->vm_file);
+	vma->vm_file = file;
+	vma->vm_ops = &shmem_vm_ops;
+	return 0;
+}
+
+/**
+ * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
+ * @mapping:	the page's address_space
+ * @index:	the page index
+ * @gfp:	the page allocator flags to use if allocating
+ *
+ * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
+ * with any new page allocations done using the specified allocation flags.
+ * But read_cache_page_gfp() uses the ->readpage() method: which does not
+ * suit tmpfs, since it may have pages in swapcache, and needs to find those
+ * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
+ *
+ * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
+ * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
+ */
+struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
+					 pgoff_t index, gfp_t gfp)
+{
+#ifdef CONFIG_SHMEM
+	struct inode *inode = mapping->host;
+	struct page *page;
+	int error;
+
+	BUG_ON(mapping->a_ops != &shmem_aops);
+	error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
+	if (error)
+		page = ERR_PTR(error);
+	else
+		unlock_page(page);
+	return page;
+#else
+	/*
+	 * The tiny !SHMEM case uses ramfs without swap
+	 */
+	return read_cache_page_gfp(mapping, index, gfp);
+#endif
+}
+EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
diff --git a/mm/slab.c b/mm/slab.c
new file mode 100644
index 0000000..4765c97
--- /dev/null
+++ b/mm/slab.c
@@ -0,0 +1,4251 @@
+/*
+ * linux/mm/slab.c
+ * Written by Mark Hemment, 1996/97.
+ * (markhe@nextd.demon.co.uk)
+ *
+ * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
+ *
+ * Major cleanup, different bufctl logic, per-cpu arrays
+ *	(c) 2000 Manfred Spraul
+ *
+ * Cleanup, make the head arrays unconditional, preparation for NUMA
+ * 	(c) 2002 Manfred Spraul
+ *
+ * An implementation of the Slab Allocator as described in outline in;
+ *	UNIX Internals: The New Frontiers by Uresh Vahalia
+ *	Pub: Prentice Hall	ISBN 0-13-101908-2
+ * or with a little more detail in;
+ *	The Slab Allocator: An Object-Caching Kernel Memory Allocator
+ *	Jeff Bonwick (Sun Microsystems).
+ *	Presented at: USENIX Summer 1994 Technical Conference
+ *
+ * The memory is organized in caches, one cache for each object type.
+ * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
+ * Each cache consists out of many slabs (they are small (usually one
+ * page long) and always contiguous), and each slab contains multiple
+ * initialized objects.
+ *
+ * This means, that your constructor is used only for newly allocated
+ * slabs and you must pass objects with the same initializations to
+ * kmem_cache_free.
+ *
+ * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
+ * normal). If you need a special memory type, then must create a new
+ * cache for that memory type.
+ *
+ * In order to reduce fragmentation, the slabs are sorted in 3 groups:
+ *   full slabs with 0 free objects
+ *   partial slabs
+ *   empty slabs with no allocated objects
+ *
+ * If partial slabs exist, then new allocations come from these slabs,
+ * otherwise from empty slabs or new slabs are allocated.
+ *
+ * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
+ * during kmem_cache_destroy(). The caller must prevent concurrent allocs.
+ *
+ * Each cache has a short per-cpu head array, most allocs
+ * and frees go into that array, and if that array overflows, then 1/2
+ * of the entries in the array are given back into the global cache.
+ * The head array is strictly LIFO and should improve the cache hit rates.
+ * On SMP, it additionally reduces the spinlock operations.
+ *
+ * The c_cpuarray may not be read with enabled local interrupts -
+ * it's changed with a smp_call_function().
+ *
+ * SMP synchronization:
+ *  constructors and destructors are called without any locking.
+ *  Several members in struct kmem_cache and struct slab never change, they
+ *	are accessed without any locking.
+ *  The per-cpu arrays are never accessed from the wrong cpu, no locking,
+ *  	and local interrupts are disabled so slab code is preempt-safe.
+ *  The non-constant members are protected with a per-cache irq spinlock.
+ *
+ * Many thanks to Mark Hemment, who wrote another per-cpu slab patch
+ * in 2000 - many ideas in the current implementation are derived from
+ * his patch.
+ *
+ * Further notes from the original documentation:
+ *
+ * 11 April '97.  Started multi-threading - markhe
+ *	The global cache-chain is protected by the mutex 'slab_mutex'.
+ *	The sem is only needed when accessing/extending the cache-chain, which
+ *	can never happen inside an interrupt (kmem_cache_create(),
+ *	kmem_cache_shrink() and kmem_cache_reap()).
+ *
+ *	At present, each engine can be growing a cache.  This should be blocked.
+ *
+ * 15 March 2005. NUMA slab allocator.
+ *	Shai Fultheim <shai@scalex86.org>.
+ *	Shobhit Dayal <shobhit@calsoftinc.com>
+ *	Alok N Kataria <alokk@calsoftinc.com>
+ *	Christoph Lameter <christoph@lameter.com>
+ *
+ *	Modified the slab allocator to be node aware on NUMA systems.
+ *	Each node has its own list of partial, free and full slabs.
+ *	All object allocations for a node occur from node specific slab lists.
+ */
+
+#include	<linux/slab.h>
+#include	<linux/mm.h>
+#include	<linux/poison.h>
+#include	<linux/swap.h>
+#include	<linux/cache.h>
+#include	<linux/interrupt.h>
+#include	<linux/init.h>
+#include	<linux/compiler.h>
+#include	<linux/cpuset.h>
+#include	<linux/proc_fs.h>
+#include	<linux/seq_file.h>
+#include	<linux/notifier.h>
+#include	<linux/kallsyms.h>
+#include	<linux/cpu.h>
+#include	<linux/sysctl.h>
+#include	<linux/module.h>
+#include	<linux/rcupdate.h>
+#include	<linux/string.h>
+#include	<linux/uaccess.h>
+#include	<linux/nodemask.h>
+#include	<linux/kmemleak.h>
+#include	<linux/mempolicy.h>
+#include	<linux/mutex.h>
+#include	<linux/fault-inject.h>
+#include	<linux/rtmutex.h>
+#include	<linux/reciprocal_div.h>
+#include	<linux/debugobjects.h>
+#include	<linux/kmemcheck.h>
+#include	<linux/memory.h>
+#include	<linux/prefetch.h>
+
+#include	<net/sock.h>
+
+#include	<asm/cacheflush.h>
+#include	<asm/tlbflush.h>
+#include	<asm/page.h>
+
+#include <trace/events/kmem.h>
+
+#include	"internal.h"
+
+#include	"slab.h"
+
+/*
+ * DEBUG	- 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
+ *		  0 for faster, smaller code (especially in the critical paths).
+ *
+ * STATS	- 1 to collect stats for /proc/slabinfo.
+ *		  0 for faster, smaller code (especially in the critical paths).
+ *
+ * FORCED_DEBUG	- 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
+ */
+
+#ifdef CONFIG_DEBUG_SLAB
+#define	DEBUG		1
+#define	STATS		1
+#define	FORCED_DEBUG	1
+#else
+#define	DEBUG		0
+#define	STATS		0
+#define	FORCED_DEBUG	0
+#endif
+
+/* Shouldn't this be in a header file somewhere? */
+#define	BYTES_PER_WORD		sizeof(void *)
+#define	REDZONE_ALIGN		max(BYTES_PER_WORD, __alignof__(unsigned long long))
+
+#ifndef ARCH_KMALLOC_FLAGS
+#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
+#endif
+
+#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
+				<= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
+
+#if FREELIST_BYTE_INDEX
+typedef unsigned char freelist_idx_t;
+#else
+typedef unsigned short freelist_idx_t;
+#endif
+
+#define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
+
+/*
+ * true if a page was allocated from pfmemalloc reserves for network-based
+ * swap
+ */
+static bool pfmemalloc_active __read_mostly;
+
+/*
+ * struct array_cache
+ *
+ * Purpose:
+ * - LIFO ordering, to hand out cache-warm objects from _alloc
+ * - reduce the number of linked list operations
+ * - reduce spinlock operations
+ *
+ * The limit is stored in the per-cpu structure to reduce the data cache
+ * footprint.
+ *
+ */
+struct array_cache {
+	unsigned int avail;
+	unsigned int limit;
+	unsigned int batchcount;
+	unsigned int touched;
+	void *entry[];	/*
+			 * Must have this definition in here for the proper
+			 * alignment of array_cache. Also simplifies accessing
+			 * the entries.
+			 *
+			 * Entries should not be directly dereferenced as
+			 * entries belonging to slabs marked pfmemalloc will
+			 * have the lower bits set SLAB_OBJ_PFMEMALLOC
+			 */
+};
+
+struct alien_cache {
+	spinlock_t lock;
+	struct array_cache ac;
+};
+
+#define SLAB_OBJ_PFMEMALLOC	1
+static inline bool is_obj_pfmemalloc(void *objp)
+{
+	return (unsigned long)objp & SLAB_OBJ_PFMEMALLOC;
+}
+
+static inline void set_obj_pfmemalloc(void **objp)
+{
+	*objp = (void *)((unsigned long)*objp | SLAB_OBJ_PFMEMALLOC);
+	return;
+}
+
+static inline void clear_obj_pfmemalloc(void **objp)
+{
+	*objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
+}
+
+/*
+ * bootstrap: The caches do not work without cpuarrays anymore, but the
+ * cpuarrays are allocated from the generic caches...
+ */
+#define BOOT_CPUCACHE_ENTRIES	1
+struct arraycache_init {
+	struct array_cache cache;
+	void *entries[BOOT_CPUCACHE_ENTRIES];
+};
+
+/*
+ * Need this for bootstrapping a per node allocator.
+ */
+#define NUM_INIT_LISTS (2 * MAX_NUMNODES)
+static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
+#define	CACHE_CACHE 0
+#define	SIZE_NODE (MAX_NUMNODES)
+
+static int drain_freelist(struct kmem_cache *cache,
+			struct kmem_cache_node *n, int tofree);
+static void free_block(struct kmem_cache *cachep, void **objpp, int len,
+			int node, struct list_head *list);
+static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
+static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
+static void cache_reap(struct work_struct *unused);
+
+static int slab_early_init = 1;
+
+#define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
+
+static void kmem_cache_node_init(struct kmem_cache_node *parent)
+{
+	INIT_LIST_HEAD(&parent->slabs_full);
+	INIT_LIST_HEAD(&parent->slabs_partial);
+	INIT_LIST_HEAD(&parent->slabs_free);
+	parent->shared = NULL;
+	parent->alien = NULL;
+	parent->colour_next = 0;
+	spin_lock_init(&parent->list_lock);
+	parent->free_objects = 0;
+	parent->free_touched = 0;
+}
+
+#define MAKE_LIST(cachep, listp, slab, nodeid)				\
+	do {								\
+		INIT_LIST_HEAD(listp);					\
+		list_splice(&get_node(cachep, nodeid)->slab, listp);	\
+	} while (0)
+
+#define	MAKE_ALL_LISTS(cachep, ptr, nodeid)				\
+	do {								\
+	MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid);	\
+	MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
+	MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid);	\
+	} while (0)
+
+#define CFLGS_OFF_SLAB		(0x80000000UL)
+#define	OFF_SLAB(x)	((x)->flags & CFLGS_OFF_SLAB)
+#define OFF_SLAB_MIN_SIZE (max_t(size_t, PAGE_SIZE >> 5, KMALLOC_MIN_SIZE + 1))
+
+#define BATCHREFILL_LIMIT	16
+/*
+ * Optimization question: fewer reaps means less probability for unnessary
+ * cpucache drain/refill cycles.
+ *
+ * OTOH the cpuarrays can contain lots of objects,
+ * which could lock up otherwise freeable slabs.
+ */
+#define REAPTIMEOUT_AC		(2*HZ)
+#define REAPTIMEOUT_NODE	(4*HZ)
+
+#if STATS
+#define	STATS_INC_ACTIVE(x)	((x)->num_active++)
+#define	STATS_DEC_ACTIVE(x)	((x)->num_active--)
+#define	STATS_INC_ALLOCED(x)	((x)->num_allocations++)
+#define	STATS_INC_GROWN(x)	((x)->grown++)
+#define	STATS_ADD_REAPED(x,y)	((x)->reaped += (y))
+#define	STATS_SET_HIGH(x)						\
+	do {								\
+		if ((x)->num_active > (x)->high_mark)			\
+			(x)->high_mark = (x)->num_active;		\
+	} while (0)
+#define	STATS_INC_ERR(x)	((x)->errors++)
+#define	STATS_INC_NODEALLOCS(x)	((x)->node_allocs++)
+#define	STATS_INC_NODEFREES(x)	((x)->node_frees++)
+#define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
+#define	STATS_SET_FREEABLE(x, i)					\
+	do {								\
+		if ((x)->max_freeable < i)				\
+			(x)->max_freeable = i;				\
+	} while (0)
+#define STATS_INC_ALLOCHIT(x)	atomic_inc(&(x)->allochit)
+#define STATS_INC_ALLOCMISS(x)	atomic_inc(&(x)->allocmiss)
+#define STATS_INC_FREEHIT(x)	atomic_inc(&(x)->freehit)
+#define STATS_INC_FREEMISS(x)	atomic_inc(&(x)->freemiss)
+#else
+#define	STATS_INC_ACTIVE(x)	do { } while (0)
+#define	STATS_DEC_ACTIVE(x)	do { } while (0)
+#define	STATS_INC_ALLOCED(x)	do { } while (0)
+#define	STATS_INC_GROWN(x)	do { } while (0)
+#define	STATS_ADD_REAPED(x,y)	do { (void)(y); } while (0)
+#define	STATS_SET_HIGH(x)	do { } while (0)
+#define	STATS_INC_ERR(x)	do { } while (0)
+#define	STATS_INC_NODEALLOCS(x)	do { } while (0)
+#define	STATS_INC_NODEFREES(x)	do { } while (0)
+#define STATS_INC_ACOVERFLOW(x)   do { } while (0)
+#define	STATS_SET_FREEABLE(x, i) do { } while (0)
+#define STATS_INC_ALLOCHIT(x)	do { } while (0)
+#define STATS_INC_ALLOCMISS(x)	do { } while (0)
+#define STATS_INC_FREEHIT(x)	do { } while (0)
+#define STATS_INC_FREEMISS(x)	do { } while (0)
+#endif
+
+#if DEBUG
+
+/*
+ * memory layout of objects:
+ * 0		: objp
+ * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
+ * 		the end of an object is aligned with the end of the real
+ * 		allocation. Catches writes behind the end of the allocation.
+ * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
+ * 		redzone word.
+ * cachep->obj_offset: The real object.
+ * cachep->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
+ * cachep->size - 1* BYTES_PER_WORD: last caller address
+ *					[BYTES_PER_WORD long]
+ */
+static int obj_offset(struct kmem_cache *cachep)
+{
+	return cachep->obj_offset;
+}
+
+static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
+{
+	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
+	return (unsigned long long*) (objp + obj_offset(cachep) -
+				      sizeof(unsigned long long));
+}
+
+static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
+{
+	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
+	if (cachep->flags & SLAB_STORE_USER)
+		return (unsigned long long *)(objp + cachep->size -
+					      sizeof(unsigned long long) -
+					      REDZONE_ALIGN);
+	return (unsigned long long *) (objp + cachep->size -
+				       sizeof(unsigned long long));
+}
+
+static void **dbg_userword(struct kmem_cache *cachep, void *objp)
+{
+	BUG_ON(!(cachep->flags & SLAB_STORE_USER));
+	return (void **)(objp + cachep->size - BYTES_PER_WORD);
+}
+
+#else
+
+#define obj_offset(x)			0
+#define dbg_redzone1(cachep, objp)	({BUG(); (unsigned long long *)NULL;})
+#define dbg_redzone2(cachep, objp)	({BUG(); (unsigned long long *)NULL;})
+#define dbg_userword(cachep, objp)	({BUG(); (void **)NULL;})
+
+#endif
+
+#define OBJECT_FREE (0)
+#define OBJECT_ACTIVE (1)
+
+#ifdef CONFIG_DEBUG_SLAB_LEAK
+
+static void set_obj_status(struct page *page, int idx, int val)
+{
+	int freelist_size;
+	char *status;
+	struct kmem_cache *cachep = page->slab_cache;
+
+	freelist_size = cachep->num * sizeof(freelist_idx_t);
+	status = (char *)page->freelist + freelist_size;
+	status[idx] = val;
+}
+
+static inline unsigned int get_obj_status(struct page *page, int idx)
+{
+	int freelist_size;
+	char *status;
+	struct kmem_cache *cachep = page->slab_cache;
+
+	freelist_size = cachep->num * sizeof(freelist_idx_t);
+	status = (char *)page->freelist + freelist_size;
+
+	return status[idx];
+}
+
+#else
+static inline void set_obj_status(struct page *page, int idx, int val) {}
+
+#endif
+
+/*
+ * Do not go above this order unless 0 objects fit into the slab or
+ * overridden on the command line.
+ */
+#define	SLAB_MAX_ORDER_HI	1
+#define	SLAB_MAX_ORDER_LO	0
+static int slab_max_order = SLAB_MAX_ORDER_LO;
+static bool slab_max_order_set __initdata;
+
+static inline struct kmem_cache *virt_to_cache(const void *obj)
+{
+	struct page *page = virt_to_head_page(obj);
+	return page->slab_cache;
+}
+
+static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
+				 unsigned int idx)
+{
+	return page->s_mem + cache->size * idx;
+}
+
+/*
+ * We want to avoid an expensive divide : (offset / cache->size)
+ *   Using the fact that size is a constant for a particular cache,
+ *   we can replace (offset / cache->size) by
+ *   reciprocal_divide(offset, cache->reciprocal_buffer_size)
+ */
+static inline unsigned int obj_to_index(const struct kmem_cache *cache,
+					const struct page *page, void *obj)
+{
+	u32 offset = (obj - page->s_mem);
+	return reciprocal_divide(offset, cache->reciprocal_buffer_size);
+}
+
+/* internal cache of cache description objs */
+static struct kmem_cache kmem_cache_boot = {
+	.batchcount = 1,
+	.limit = BOOT_CPUCACHE_ENTRIES,
+	.shared = 1,
+	.size = sizeof(struct kmem_cache),
+	.name = "kmem_cache",
+};
+
+#define BAD_ALIEN_MAGIC 0x01020304ul
+
+static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
+
+static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
+{
+	return this_cpu_ptr(cachep->cpu_cache);
+}
+
+static size_t calculate_freelist_size(int nr_objs, size_t align)
+{
+	size_t freelist_size;
+
+	freelist_size = nr_objs * sizeof(freelist_idx_t);
+	if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK))
+		freelist_size += nr_objs * sizeof(char);
+
+	if (align)
+		freelist_size = ALIGN(freelist_size, align);
+
+	return freelist_size;
+}
+
+static int calculate_nr_objs(size_t slab_size, size_t buffer_size,
+				size_t idx_size, size_t align)
+{
+	int nr_objs;
+	size_t remained_size;
+	size_t freelist_size;
+	int extra_space = 0;
+
+	if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK))
+		extra_space = sizeof(char);
+	/*
+	 * Ignore padding for the initial guess. The padding
+	 * is at most @align-1 bytes, and @buffer_size is at
+	 * least @align. In the worst case, this result will
+	 * be one greater than the number of objects that fit
+	 * into the memory allocation when taking the padding
+	 * into account.
+	 */
+	nr_objs = slab_size / (buffer_size + idx_size + extra_space);
+
+	/*
+	 * This calculated number will be either the right
+	 * amount, or one greater than what we want.
+	 */
+	remained_size = slab_size - nr_objs * buffer_size;
+	freelist_size = calculate_freelist_size(nr_objs, align);
+	if (remained_size < freelist_size)
+		nr_objs--;
+
+	return nr_objs;
+}
+
+/*
+ * Calculate the number of objects and left-over bytes for a given buffer size.
+ */
+static void cache_estimate(unsigned long gfporder, size_t buffer_size,
+			   size_t align, int flags, size_t *left_over,
+			   unsigned int *num)
+{
+	int nr_objs;
+	size_t mgmt_size;
+	size_t slab_size = PAGE_SIZE << gfporder;
+
+	/*
+	 * The slab management structure can be either off the slab or
+	 * on it. For the latter case, the memory allocated for a
+	 * slab is used for:
+	 *
+	 * - One unsigned int for each object
+	 * - Padding to respect alignment of @align
+	 * - @buffer_size bytes for each object
+	 *
+	 * If the slab management structure is off the slab, then the
+	 * alignment will already be calculated into the size. Because
+	 * the slabs are all pages aligned, the objects will be at the
+	 * correct alignment when allocated.
+	 */
+	if (flags & CFLGS_OFF_SLAB) {
+		mgmt_size = 0;
+		nr_objs = slab_size / buffer_size;
+
+	} else {
+		nr_objs = calculate_nr_objs(slab_size, buffer_size,
+					sizeof(freelist_idx_t), align);
+		mgmt_size = calculate_freelist_size(nr_objs, align);
+	}
+	*num = nr_objs;
+	*left_over = slab_size - nr_objs*buffer_size - mgmt_size;
+}
+
+#if DEBUG
+#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
+
+static void __slab_error(const char *function, struct kmem_cache *cachep,
+			char *msg)
+{
+	printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
+	       function, cachep->name, msg);
+	dump_stack();
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+}
+#endif
+
+/*
+ * By default on NUMA we use alien caches to stage the freeing of
+ * objects allocated from other nodes. This causes massive memory
+ * inefficiencies when using fake NUMA setup to split memory into a
+ * large number of small nodes, so it can be disabled on the command
+ * line
+  */
+
+static int use_alien_caches __read_mostly = 1;
+static int __init noaliencache_setup(char *s)
+{
+	use_alien_caches = 0;
+	return 1;
+}
+__setup("noaliencache", noaliencache_setup);
+
+static int __init slab_max_order_setup(char *str)
+{
+	get_option(&str, &slab_max_order);
+	slab_max_order = slab_max_order < 0 ? 0 :
+				min(slab_max_order, MAX_ORDER - 1);
+	slab_max_order_set = true;
+
+	return 1;
+}
+__setup("slab_max_order=", slab_max_order_setup);
+
+#ifdef CONFIG_NUMA
+/*
+ * Special reaping functions for NUMA systems called from cache_reap().
+ * These take care of doing round robin flushing of alien caches (containing
+ * objects freed on different nodes from which they were allocated) and the
+ * flushing of remote pcps by calling drain_node_pages.
+ */
+static DEFINE_PER_CPU(unsigned long, slab_reap_node);
+
+static void init_reap_node(int cpu)
+{
+	int node;
+
+	node = next_node(cpu_to_mem(cpu), node_online_map);
+	if (node == MAX_NUMNODES)
+		node = first_node(node_online_map);
+
+	per_cpu(slab_reap_node, cpu) = node;
+}
+
+static void next_reap_node(void)
+{
+	int node = __this_cpu_read(slab_reap_node);
+
+	node = next_node(node, node_online_map);
+	if (unlikely(node >= MAX_NUMNODES))
+		node = first_node(node_online_map);
+	__this_cpu_write(slab_reap_node, node);
+}
+
+#else
+#define init_reap_node(cpu) do { } while (0)
+#define next_reap_node(void) do { } while (0)
+#endif
+
+/*
+ * Initiate the reap timer running on the target CPU.  We run at around 1 to 2Hz
+ * via the workqueue/eventd.
+ * Add the CPU number into the expiration time to minimize the possibility of
+ * the CPUs getting into lockstep and contending for the global cache chain
+ * lock.
+ */
+static void start_cpu_timer(int cpu)
+{
+	struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
+
+	/*
+	 * When this gets called from do_initcalls via cpucache_init(),
+	 * init_workqueues() has already run, so keventd will be setup
+	 * at that time.
+	 */
+	if (keventd_up() && reap_work->work.func == NULL) {
+		init_reap_node(cpu);
+		INIT_DEFERRABLE_WORK(reap_work, cache_reap);
+		schedule_delayed_work_on(cpu, reap_work,
+					__round_jiffies_relative(HZ, cpu));
+	}
+}
+
+static void init_arraycache(struct array_cache *ac, int limit, int batch)
+{
+	/*
+	 * The array_cache structures contain pointers to free object.
+	 * However, when such objects are allocated or transferred to another
+	 * cache the pointers are not cleared and they could be counted as
+	 * valid references during a kmemleak scan. Therefore, kmemleak must
+	 * not scan such objects.
+	 */
+	kmemleak_no_scan(ac);
+	if (ac) {
+		ac->avail = 0;
+		ac->limit = limit;
+		ac->batchcount = batch;
+		ac->touched = 0;
+	}
+}
+
+static struct array_cache *alloc_arraycache(int node, int entries,
+					    int batchcount, gfp_t gfp)
+{
+	size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache);
+	struct array_cache *ac = NULL;
+
+	ac = kmalloc_node(memsize, gfp, node);
+	init_arraycache(ac, entries, batchcount);
+	return ac;
+}
+
+static inline bool is_slab_pfmemalloc(struct page *page)
+{
+	return PageSlabPfmemalloc(page);
+}
+
+/* Clears pfmemalloc_active if no slabs have pfmalloc set */
+static void recheck_pfmemalloc_active(struct kmem_cache *cachep,
+						struct array_cache *ac)
+{
+	struct kmem_cache_node *n = get_node(cachep, numa_mem_id());
+	struct page *page;
+	unsigned long flags;
+
+	if (!pfmemalloc_active)
+		return;
+
+	spin_lock_irqsave(&n->list_lock, flags);
+	list_for_each_entry(page, &n->slabs_full, lru)
+		if (is_slab_pfmemalloc(page))
+			goto out;
+
+	list_for_each_entry(page, &n->slabs_partial, lru)
+		if (is_slab_pfmemalloc(page))
+			goto out;
+
+	list_for_each_entry(page, &n->slabs_free, lru)
+		if (is_slab_pfmemalloc(page))
+			goto out;
+
+	pfmemalloc_active = false;
+out:
+	spin_unlock_irqrestore(&n->list_lock, flags);
+}
+
+static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+						gfp_t flags, bool force_refill)
+{
+	int i;
+	void *objp = ac->entry[--ac->avail];
+
+	/* Ensure the caller is allowed to use objects from PFMEMALLOC slab */
+	if (unlikely(is_obj_pfmemalloc(objp))) {
+		struct kmem_cache_node *n;
+
+		if (gfp_pfmemalloc_allowed(flags)) {
+			clear_obj_pfmemalloc(&objp);
+			return objp;
+		}
+
+		/* The caller cannot use PFMEMALLOC objects, find another one */
+		for (i = 0; i < ac->avail; i++) {
+			/* If a !PFMEMALLOC object is found, swap them */
+			if (!is_obj_pfmemalloc(ac->entry[i])) {
+				objp = ac->entry[i];
+				ac->entry[i] = ac->entry[ac->avail];
+				ac->entry[ac->avail] = objp;
+				return objp;
+			}
+		}
+
+		/*
+		 * If there are empty slabs on the slabs_free list and we are
+		 * being forced to refill the cache, mark this one !pfmemalloc.
+		 */
+		n = get_node(cachep, numa_mem_id());
+		if (!list_empty(&n->slabs_free) && force_refill) {
+			struct page *page = virt_to_head_page(objp);
+			ClearPageSlabPfmemalloc(page);
+			clear_obj_pfmemalloc(&objp);
+			recheck_pfmemalloc_active(cachep, ac);
+			return objp;
+		}
+
+		/* No !PFMEMALLOC objects available */
+		ac->avail++;
+		objp = NULL;
+	}
+
+	return objp;
+}
+
+static inline void *ac_get_obj(struct kmem_cache *cachep,
+			struct array_cache *ac, gfp_t flags, bool force_refill)
+{
+	void *objp;
+
+	if (unlikely(sk_memalloc_socks()))
+		objp = __ac_get_obj(cachep, ac, flags, force_refill);
+	else
+		objp = ac->entry[--ac->avail];
+
+	return objp;
+}
+
+static noinline void *__ac_put_obj(struct kmem_cache *cachep,
+			struct array_cache *ac, void *objp)
+{
+	if (unlikely(pfmemalloc_active)) {
+		/* Some pfmemalloc slabs exist, check if this is one */
+		struct page *page = virt_to_head_page(objp);
+		if (PageSlabPfmemalloc(page))
+			set_obj_pfmemalloc(&objp);
+	}
+
+	return objp;
+}
+
+static inline void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+								void *objp)
+{
+	if (unlikely(sk_memalloc_socks()))
+		objp = __ac_put_obj(cachep, ac, objp);
+
+	ac->entry[ac->avail++] = objp;
+}
+
+/*
+ * Transfer objects in one arraycache to another.
+ * Locking must be handled by the caller.
+ *
+ * Return the number of entries transferred.
+ */
+static int transfer_objects(struct array_cache *to,
+		struct array_cache *from, unsigned int max)
+{
+	/* Figure out how many entries to transfer */
+	int nr = min3(from->avail, max, to->limit - to->avail);
+
+	if (!nr)
+		return 0;
+
+	memcpy(to->entry + to->avail, from->entry + from->avail -nr,
+			sizeof(void *) *nr);
+
+	from->avail -= nr;
+	to->avail += nr;
+	return nr;
+}
+
+#ifndef CONFIG_NUMA
+
+#define drain_alien_cache(cachep, alien) do { } while (0)
+#define reap_alien(cachep, n) do { } while (0)
+
+static inline struct alien_cache **alloc_alien_cache(int node,
+						int limit, gfp_t gfp)
+{
+	return (struct alien_cache **)BAD_ALIEN_MAGIC;
+}
+
+static inline void free_alien_cache(struct alien_cache **ac_ptr)
+{
+}
+
+static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
+{
+	return 0;
+}
+
+static inline void *alternate_node_alloc(struct kmem_cache *cachep,
+		gfp_t flags)
+{
+	return NULL;
+}
+
+static inline void *____cache_alloc_node(struct kmem_cache *cachep,
+		 gfp_t flags, int nodeid)
+{
+	return NULL;
+}
+
+static inline gfp_t gfp_exact_node(gfp_t flags)
+{
+	return flags;
+}
+
+#else	/* CONFIG_NUMA */
+
+static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
+static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
+
+static struct alien_cache *__alloc_alien_cache(int node, int entries,
+						int batch, gfp_t gfp)
+{
+	size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
+	struct alien_cache *alc = NULL;
+
+	alc = kmalloc_node(memsize, gfp, node);
+	init_arraycache(&alc->ac, entries, batch);
+	spin_lock_init(&alc->lock);
+	return alc;
+}
+
+static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
+{
+	struct alien_cache **alc_ptr;
+	size_t memsize = sizeof(void *) * nr_node_ids;
+	int i;
+
+	if (limit > 1)
+		limit = 12;
+	alc_ptr = kzalloc_node(memsize, gfp, node);
+	if (!alc_ptr)
+		return NULL;
+
+	for_each_node(i) {
+		if (i == node || !node_online(i))
+			continue;
+		alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
+		if (!alc_ptr[i]) {
+			for (i--; i >= 0; i--)
+				kfree(alc_ptr[i]);
+			kfree(alc_ptr);
+			return NULL;
+		}
+	}
+	return alc_ptr;
+}
+
+static void free_alien_cache(struct alien_cache **alc_ptr)
+{
+	int i;
+
+	if (!alc_ptr)
+		return;
+	for_each_node(i)
+	    kfree(alc_ptr[i]);
+	kfree(alc_ptr);
+}
+
+static void __drain_alien_cache(struct kmem_cache *cachep,
+				struct array_cache *ac, int node,
+				struct list_head *list)
+{
+	struct kmem_cache_node *n = get_node(cachep, node);
+
+	if (ac->avail) {
+		spin_lock(&n->list_lock);
+		/*
+		 * Stuff objects into the remote nodes shared array first.
+		 * That way we could avoid the overhead of putting the objects
+		 * into the free lists and getting them back later.
+		 */
+		if (n->shared)
+			transfer_objects(n->shared, ac, ac->limit);
+
+		free_block(cachep, ac->entry, ac->avail, node, list);
+		ac->avail = 0;
+		spin_unlock(&n->list_lock);
+	}
+}
+
+/*
+ * Called from cache_reap() to regularly drain alien caches round robin.
+ */
+static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
+{
+	int node = __this_cpu_read(slab_reap_node);
+
+	if (n->alien) {
+		struct alien_cache *alc = n->alien[node];
+		struct array_cache *ac;
+
+		if (alc) {
+			ac = &alc->ac;
+			if (ac->avail && spin_trylock_irq(&alc->lock)) {
+				LIST_HEAD(list);
+
+				__drain_alien_cache(cachep, ac, node, &list);
+				spin_unlock_irq(&alc->lock);
+				slabs_destroy(cachep, &list);
+			}
+		}
+	}
+}
+
+static void drain_alien_cache(struct kmem_cache *cachep,
+				struct alien_cache **alien)
+{
+	int i = 0;
+	struct alien_cache *alc;
+	struct array_cache *ac;
+	unsigned long flags;
+
+	for_each_online_node(i) {
+		alc = alien[i];
+		if (alc) {
+			LIST_HEAD(list);
+
+			ac = &alc->ac;
+			spin_lock_irqsave(&alc->lock, flags);
+			__drain_alien_cache(cachep, ac, i, &list);
+			spin_unlock_irqrestore(&alc->lock, flags);
+			slabs_destroy(cachep, &list);
+		}
+	}
+}
+
+static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
+				int node, int page_node)
+{
+	struct kmem_cache_node *n;
+	struct alien_cache *alien = NULL;
+	struct array_cache *ac;
+	LIST_HEAD(list);
+
+	n = get_node(cachep, node);
+	STATS_INC_NODEFREES(cachep);
+	if (n->alien && n->alien[page_node]) {
+		alien = n->alien[page_node];
+		ac = &alien->ac;
+		spin_lock(&alien->lock);
+		if (unlikely(ac->avail == ac->limit)) {
+			STATS_INC_ACOVERFLOW(cachep);
+			__drain_alien_cache(cachep, ac, page_node, &list);
+		}
+		ac_put_obj(cachep, ac, objp);
+		spin_unlock(&alien->lock);
+		slabs_destroy(cachep, &list);
+	} else {
+		n = get_node(cachep, page_node);
+		spin_lock(&n->list_lock);
+		free_block(cachep, &objp, 1, page_node, &list);
+		spin_unlock(&n->list_lock);
+		slabs_destroy(cachep, &list);
+	}
+	return 1;
+}
+
+static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
+{
+	int page_node = page_to_nid(virt_to_page(objp));
+	int node = numa_mem_id();
+	/*
+	 * Make sure we are not freeing a object from another node to the array
+	 * cache on this cpu.
+	 */
+	if (likely(node == page_node))
+		return 0;
+
+	return __cache_free_alien(cachep, objp, node, page_node);
+}
+
+/*
+ * Construct gfp mask to allocate from a specific node but do not direct reclaim
+ * or warn about failures. kswapd may still wake to reclaim in the background.
+ */
+static inline gfp_t gfp_exact_node(gfp_t flags)
+{
+	return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM;
+}
+#endif
+
+/*
+ * Allocates and initializes node for a node on each slab cache, used for
+ * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
+ * will be allocated off-node since memory is not yet online for the new node.
+ * When hotplugging memory or a cpu, existing node are not replaced if
+ * already in use.
+ *
+ * Must hold slab_mutex.
+ */
+static int init_cache_node_node(int node)
+{
+	struct kmem_cache *cachep;
+	struct kmem_cache_node *n;
+	const size_t memsize = sizeof(struct kmem_cache_node);
+
+	list_for_each_entry(cachep, &slab_caches, list) {
+		/*
+		 * Set up the kmem_cache_node for cpu before we can
+		 * begin anything. Make sure some other cpu on this
+		 * node has not already allocated this
+		 */
+		n = get_node(cachep, node);
+		if (!n) {
+			n = kmalloc_node(memsize, GFP_KERNEL, node);
+			if (!n)
+				return -ENOMEM;
+			kmem_cache_node_init(n);
+			n->next_reap = jiffies + REAPTIMEOUT_NODE +
+			    ((unsigned long)cachep) % REAPTIMEOUT_NODE;
+
+			/*
+			 * The kmem_cache_nodes don't come and go as CPUs
+			 * come and go.  slab_mutex is sufficient
+			 * protection here.
+			 */
+			cachep->node[node] = n;
+		}
+
+		spin_lock_irq(&n->list_lock);
+		n->free_limit =
+			(1 + nr_cpus_node(node)) *
+			cachep->batchcount + cachep->num;
+		spin_unlock_irq(&n->list_lock);
+	}
+	return 0;
+}
+
+static inline int slabs_tofree(struct kmem_cache *cachep,
+						struct kmem_cache_node *n)
+{
+	return (n->free_objects + cachep->num - 1) / cachep->num;
+}
+
+static void cpuup_canceled(long cpu)
+{
+	struct kmem_cache *cachep;
+	struct kmem_cache_node *n = NULL;
+	int node = cpu_to_mem(cpu);
+	const struct cpumask *mask = cpumask_of_node(node);
+
+	list_for_each_entry(cachep, &slab_caches, list) {
+		struct array_cache *nc;
+		struct array_cache *shared;
+		struct alien_cache **alien;
+		LIST_HEAD(list);
+
+		n = get_node(cachep, node);
+		if (!n)
+			continue;
+
+		spin_lock_irq(&n->list_lock);
+
+		/* Free limit for this kmem_cache_node */
+		n->free_limit -= cachep->batchcount;
+
+		/* cpu is dead; no one can alloc from it. */
+		nc = per_cpu_ptr(cachep->cpu_cache, cpu);
+		if (nc) {
+			free_block(cachep, nc->entry, nc->avail, node, &list);
+			nc->avail = 0;
+		}
+
+		if (!cpumask_empty(mask)) {
+			spin_unlock_irq(&n->list_lock);
+			goto free_slab;
+		}
+
+		shared = n->shared;
+		if (shared) {
+			free_block(cachep, shared->entry,
+				   shared->avail, node, &list);
+			n->shared = NULL;
+		}
+
+		alien = n->alien;
+		n->alien = NULL;
+
+		spin_unlock_irq(&n->list_lock);
+
+		kfree(shared);
+		if (alien) {
+			drain_alien_cache(cachep, alien);
+			free_alien_cache(alien);
+		}
+
+free_slab:
+		slabs_destroy(cachep, &list);
+	}
+	/*
+	 * In the previous loop, all the objects were freed to
+	 * the respective cache's slabs,  now we can go ahead and
+	 * shrink each nodelist to its limit.
+	 */
+	list_for_each_entry(cachep, &slab_caches, list) {
+		n = get_node(cachep, node);
+		if (!n)
+			continue;
+		drain_freelist(cachep, n, slabs_tofree(cachep, n));
+	}
+}
+
+static int cpuup_prepare(long cpu)
+{
+	struct kmem_cache *cachep;
+	struct kmem_cache_node *n = NULL;
+	int node = cpu_to_mem(cpu);
+	int err;
+
+	/*
+	 * We need to do this right in the beginning since
+	 * alloc_arraycache's are going to use this list.
+	 * kmalloc_node allows us to add the slab to the right
+	 * kmem_cache_node and not this cpu's kmem_cache_node
+	 */
+	err = init_cache_node_node(node);
+	if (err < 0)
+		goto bad;
+
+	/*
+	 * Now we can go ahead with allocating the shared arrays and
+	 * array caches
+	 */
+	list_for_each_entry(cachep, &slab_caches, list) {
+		struct array_cache *shared = NULL;
+		struct alien_cache **alien = NULL;
+
+		if (cachep->shared) {
+			shared = alloc_arraycache(node,
+				cachep->shared * cachep->batchcount,
+				0xbaadf00d, GFP_KERNEL);
+			if (!shared)
+				goto bad;
+		}
+		if (use_alien_caches) {
+			alien = alloc_alien_cache(node, cachep->limit, GFP_KERNEL);
+			if (!alien) {
+				kfree(shared);
+				goto bad;
+			}
+		}
+		n = get_node(cachep, node);
+		BUG_ON(!n);
+
+		spin_lock_irq(&n->list_lock);
+		if (!n->shared) {
+			/*
+			 * We are serialised from CPU_DEAD or
+			 * CPU_UP_CANCELLED by the cpucontrol lock
+			 */
+			n->shared = shared;
+			shared = NULL;
+		}
+#ifdef CONFIG_NUMA
+		if (!n->alien) {
+			n->alien = alien;
+			alien = NULL;
+		}
+#endif
+		spin_unlock_irq(&n->list_lock);
+		kfree(shared);
+		free_alien_cache(alien);
+	}
+
+	return 0;
+bad:
+	cpuup_canceled(cpu);
+	return -ENOMEM;
+}
+
+static int cpuup_callback(struct notifier_block *nfb,
+				    unsigned long action, void *hcpu)
+{
+	long cpu = (long)hcpu;
+	int err = 0;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		mutex_lock(&slab_mutex);
+		err = cpuup_prepare(cpu);
+		mutex_unlock(&slab_mutex);
+		break;
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		start_cpu_timer(cpu);
+		break;
+#ifdef CONFIG_HOTPLUG_CPU
+  	case CPU_DOWN_PREPARE:
+  	case CPU_DOWN_PREPARE_FROZEN:
+		/*
+		 * Shutdown cache reaper. Note that the slab_mutex is
+		 * held so that if cache_reap() is invoked it cannot do
+		 * anything expensive but will only modify reap_work
+		 * and reschedule the timer.
+		*/
+		cancel_delayed_work_sync(&per_cpu(slab_reap_work, cpu));
+		/* Now the cache_reaper is guaranteed to be not running. */
+		per_cpu(slab_reap_work, cpu).work.func = NULL;
+  		break;
+  	case CPU_DOWN_FAILED:
+  	case CPU_DOWN_FAILED_FROZEN:
+		start_cpu_timer(cpu);
+  		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		/*
+		 * Even if all the cpus of a node are down, we don't free the
+		 * kmem_cache_node of any cache. This to avoid a race between
+		 * cpu_down, and a kmalloc allocation from another cpu for
+		 * memory from the node of the cpu going down.  The node
+		 * structure is usually allocated from kmem_cache_create() and
+		 * gets destroyed at kmem_cache_destroy().
+		 */
+		/* fall through */
+#endif
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
+		mutex_lock(&slab_mutex);
+		cpuup_canceled(cpu);
+		mutex_unlock(&slab_mutex);
+		break;
+	}
+	return notifier_from_errno(err);
+}
+
+static struct notifier_block cpucache_notifier = {
+	&cpuup_callback, NULL, 0
+};
+
+#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
+/*
+ * Drains freelist for a node on each slab cache, used for memory hot-remove.
+ * Returns -EBUSY if all objects cannot be drained so that the node is not
+ * removed.
+ *
+ * Must hold slab_mutex.
+ */
+static int __meminit drain_cache_node_node(int node)
+{
+	struct kmem_cache *cachep;
+	int ret = 0;
+
+	list_for_each_entry(cachep, &slab_caches, list) {
+		struct kmem_cache_node *n;
+
+		n = get_node(cachep, node);
+		if (!n)
+			continue;
+
+		drain_freelist(cachep, n, slabs_tofree(cachep, n));
+
+		if (!list_empty(&n->slabs_full) ||
+		    !list_empty(&n->slabs_partial)) {
+			ret = -EBUSY;
+			break;
+		}
+	}
+	return ret;
+}
+
+static int __meminit slab_memory_callback(struct notifier_block *self,
+					unsigned long action, void *arg)
+{
+	struct memory_notify *mnb = arg;
+	int ret = 0;
+	int nid;
+
+	nid = mnb->status_change_nid;
+	if (nid < 0)
+		goto out;
+
+	switch (action) {
+	case MEM_GOING_ONLINE:
+		mutex_lock(&slab_mutex);
+		ret = init_cache_node_node(nid);
+		mutex_unlock(&slab_mutex);
+		break;
+	case MEM_GOING_OFFLINE:
+		mutex_lock(&slab_mutex);
+		ret = drain_cache_node_node(nid);
+		mutex_unlock(&slab_mutex);
+		break;
+	case MEM_ONLINE:
+	case MEM_OFFLINE:
+	case MEM_CANCEL_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+out:
+	return notifier_from_errno(ret);
+}
+#endif /* CONFIG_NUMA && CONFIG_MEMORY_HOTPLUG */
+
+/*
+ * swap the static kmem_cache_node with kmalloced memory
+ */
+static void __init init_list(struct kmem_cache *cachep, struct kmem_cache_node *list,
+				int nodeid)
+{
+	struct kmem_cache_node *ptr;
+
+	ptr = kmalloc_node(sizeof(struct kmem_cache_node), GFP_NOWAIT, nodeid);
+	BUG_ON(!ptr);
+
+	memcpy(ptr, list, sizeof(struct kmem_cache_node));
+	/*
+	 * Do not assume that spinlocks can be initialized via memcpy:
+	 */
+	spin_lock_init(&ptr->list_lock);
+
+	MAKE_ALL_LISTS(cachep, ptr, nodeid);
+	cachep->node[nodeid] = ptr;
+}
+
+/*
+ * For setting up all the kmem_cache_node for cache whose buffer_size is same as
+ * size of kmem_cache_node.
+ */
+static void __init set_up_node(struct kmem_cache *cachep, int index)
+{
+	int node;
+
+	for_each_online_node(node) {
+		cachep->node[node] = &init_kmem_cache_node[index + node];
+		cachep->node[node]->next_reap = jiffies +
+		    REAPTIMEOUT_NODE +
+		    ((unsigned long)cachep) % REAPTIMEOUT_NODE;
+	}
+}
+
+/*
+ * Initialisation.  Called after the page allocator have been initialised and
+ * before smp_init().
+ */
+void __init kmem_cache_init(void)
+{
+	int i;
+
+	BUILD_BUG_ON(sizeof(((struct page *)NULL)->lru) <
+					sizeof(struct rcu_head));
+	kmem_cache = &kmem_cache_boot;
+
+	if (num_possible_nodes() == 1)
+		use_alien_caches = 0;
+
+	for (i = 0; i < NUM_INIT_LISTS; i++)
+		kmem_cache_node_init(&init_kmem_cache_node[i]);
+
+	/*
+	 * Fragmentation resistance on low memory - only use bigger
+	 * page orders on machines with more than 32MB of memory if
+	 * not overridden on the command line.
+	 */
+	if (!slab_max_order_set && totalram_pages > (32 << 20) >> PAGE_SHIFT)
+		slab_max_order = SLAB_MAX_ORDER_HI;
+
+	/* Bootstrap is tricky, because several objects are allocated
+	 * from caches that do not exist yet:
+	 * 1) initialize the kmem_cache cache: it contains the struct
+	 *    kmem_cache structures of all caches, except kmem_cache itself:
+	 *    kmem_cache is statically allocated.
+	 *    Initially an __init data area is used for the head array and the
+	 *    kmem_cache_node structures, it's replaced with a kmalloc allocated
+	 *    array at the end of the bootstrap.
+	 * 2) Create the first kmalloc cache.
+	 *    The struct kmem_cache for the new cache is allocated normally.
+	 *    An __init data area is used for the head array.
+	 * 3) Create the remaining kmalloc caches, with minimally sized
+	 *    head arrays.
+	 * 4) Replace the __init data head arrays for kmem_cache and the first
+	 *    kmalloc cache with kmalloc allocated arrays.
+	 * 5) Replace the __init data for kmem_cache_node for kmem_cache and
+	 *    the other cache's with kmalloc allocated memory.
+	 * 6) Resize the head arrays of the kmalloc caches to their final sizes.
+	 */
+
+	/* 1) create the kmem_cache */
+
+	/*
+	 * struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
+	 */
+	create_boot_cache(kmem_cache, "kmem_cache",
+		offsetof(struct kmem_cache, node) +
+				  nr_node_ids * sizeof(struct kmem_cache_node *),
+				  SLAB_HWCACHE_ALIGN);
+	list_add(&kmem_cache->list, &slab_caches);
+	slab_state = PARTIAL;
+
+	/*
+	 * Initialize the caches that provide memory for the  kmem_cache_node
+	 * structures first.  Without this, further allocations will bug.
+	 */
+	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache("kmalloc-node",
+				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
+	slab_state = PARTIAL_NODE;
+	setup_kmalloc_cache_index_table();
+
+	slab_early_init = 0;
+
+	/* 5) Replace the bootstrap kmem_cache_node */
+	{
+		int nid;
+
+		for_each_online_node(nid) {
+			init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid);
+
+			init_list(kmalloc_caches[INDEX_NODE],
+					  &init_kmem_cache_node[SIZE_NODE + nid], nid);
+		}
+	}
+
+	create_kmalloc_caches(ARCH_KMALLOC_FLAGS);
+}
+
+void __init kmem_cache_init_late(void)
+{
+	struct kmem_cache *cachep;
+
+	slab_state = UP;
+
+	/* 6) resize the head arrays to their final sizes */
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(cachep, &slab_caches, list)
+		if (enable_cpucache(cachep, GFP_NOWAIT))
+			BUG();
+	mutex_unlock(&slab_mutex);
+
+	/* Done! */
+	slab_state = FULL;
+
+	/*
+	 * Register a cpu startup notifier callback that initializes
+	 * cpu_cache_get for all new cpus
+	 */
+	register_cpu_notifier(&cpucache_notifier);
+
+#ifdef CONFIG_NUMA
+	/*
+	 * Register a memory hotplug callback that initializes and frees
+	 * node.
+	 */
+	hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
+#endif
+
+	/*
+	 * The reap timers are started later, with a module init call: That part
+	 * of the kernel is not yet operational.
+	 */
+}
+
+static int __init cpucache_init(void)
+{
+	int cpu;
+
+	/*
+	 * Register the timers that return unneeded pages to the page allocator
+	 */
+	for_each_online_cpu(cpu)
+		start_cpu_timer(cpu);
+
+	/* Done! */
+	slab_state = FULL;
+	return 0;
+}
+__initcall(cpucache_init);
+
+static noinline void
+slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
+{
+#if DEBUG
+	struct kmem_cache_node *n;
+	struct page *page;
+	unsigned long flags;
+	int node;
+	static DEFINE_RATELIMIT_STATE(slab_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
+				      DEFAULT_RATELIMIT_BURST);
+
+	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs))
+		return;
+
+	printk(KERN_WARNING
+		"SLAB: Unable to allocate memory on node %d (gfp=0x%x)\n",
+		nodeid, gfpflags);
+	printk(KERN_WARNING "  cache: %s, object size: %d, order: %d\n",
+		cachep->name, cachep->size, cachep->gfporder);
+
+	for_each_kmem_cache_node(cachep, node, n) {
+		unsigned long active_objs = 0, num_objs = 0, free_objects = 0;
+		unsigned long active_slabs = 0, num_slabs = 0;
+
+		spin_lock_irqsave(&n->list_lock, flags);
+		list_for_each_entry(page, &n->slabs_full, lru) {
+			active_objs += cachep->num;
+			active_slabs++;
+		}
+		list_for_each_entry(page, &n->slabs_partial, lru) {
+			active_objs += page->active;
+			active_slabs++;
+		}
+		list_for_each_entry(page, &n->slabs_free, lru)
+			num_slabs++;
+
+		free_objects += n->free_objects;
+		spin_unlock_irqrestore(&n->list_lock, flags);
+
+		num_slabs += active_slabs;
+		num_objs = num_slabs * cachep->num;
+		printk(KERN_WARNING
+			"  node %d: slabs: %ld/%ld, objs: %ld/%ld, free: %ld\n",
+			node, active_slabs, num_slabs, active_objs, num_objs,
+			free_objects);
+	}
+#endif
+}
+
+/*
+ * Interface to system's page allocator. No need to hold the
+ * kmem_cache_node ->list_lock.
+ *
+ * If we requested dmaable memory, we will get it. Even if we
+ * did not request dmaable memory, we might get it, but that
+ * would be relatively rare and ignorable.
+ */
+static struct page *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
+								int nodeid)
+{
+	struct page *page;
+	int nr_pages;
+
+	flags |= cachep->allocflags;
+	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+		flags |= __GFP_RECLAIMABLE;
+
+	page = __alloc_pages_node(nodeid, flags | __GFP_NOTRACK, cachep->gfporder);
+	if (!page) {
+		slab_out_of_memory(cachep, flags, nodeid);
+		return NULL;
+	}
+
+	if (memcg_charge_slab(page, flags, cachep->gfporder, cachep)) {
+		__free_pages(page, cachep->gfporder);
+		return NULL;
+	}
+
+	/* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
+	if (page_is_pfmemalloc(page))
+		pfmemalloc_active = true;
+
+	nr_pages = (1 << cachep->gfporder);
+	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+		add_zone_page_state(page_zone(page),
+			NR_SLAB_RECLAIMABLE, nr_pages);
+	else
+		add_zone_page_state(page_zone(page),
+			NR_SLAB_UNRECLAIMABLE, nr_pages);
+	__SetPageSlab(page);
+	if (page_is_pfmemalloc(page))
+		SetPageSlabPfmemalloc(page);
+
+	if (kmemcheck_enabled && !(cachep->flags & SLAB_NOTRACK)) {
+		kmemcheck_alloc_shadow(page, cachep->gfporder, flags, nodeid);
+
+		if (cachep->ctor)
+			kmemcheck_mark_uninitialized_pages(page, nr_pages);
+		else
+			kmemcheck_mark_unallocated_pages(page, nr_pages);
+	}
+
+	return page;
+}
+
+/*
+ * Interface to system's page release.
+ */
+static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
+{
+	const unsigned long nr_freed = (1 << cachep->gfporder);
+
+	kmemcheck_free_shadow(page, cachep->gfporder);
+
+	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+		sub_zone_page_state(page_zone(page),
+				NR_SLAB_RECLAIMABLE, nr_freed);
+	else
+		sub_zone_page_state(page_zone(page),
+				NR_SLAB_UNRECLAIMABLE, nr_freed);
+
+	BUG_ON(!PageSlab(page));
+	__ClearPageSlabPfmemalloc(page);
+	__ClearPageSlab(page);
+	page_mapcount_reset(page);
+	page->mapping = NULL;
+
+	if (current->reclaim_state)
+		current->reclaim_state->reclaimed_slab += nr_freed;
+	__free_kmem_pages(page, cachep->gfporder);
+}
+
+static void kmem_rcu_free(struct rcu_head *head)
+{
+	struct kmem_cache *cachep;
+	struct page *page;
+
+	page = container_of(head, struct page, rcu_head);
+	cachep = page->slab_cache;
+
+	kmem_freepages(cachep, page);
+}
+
+#if DEBUG
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
+			    unsigned long caller)
+{
+	int size = cachep->object_size;
+
+	addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];
+
+	if (size < 5 * sizeof(unsigned long))
+		return;
+
+	*addr++ = 0x12345678;
+	*addr++ = caller;
+	*addr++ = smp_processor_id();
+	size -= 3 * sizeof(unsigned long);
+	{
+		unsigned long *sptr = &caller;
+		unsigned long svalue;
+
+		while (!kstack_end(sptr)) {
+			svalue = *sptr++;
+			if (kernel_text_address(svalue)) {
+				*addr++ = svalue;
+				size -= sizeof(unsigned long);
+				if (size <= sizeof(unsigned long))
+					break;
+			}
+		}
+
+	}
+	*addr++ = 0x87654321;
+}
+#endif
+
+static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
+{
+	int size = cachep->object_size;
+	addr = &((char *)addr)[obj_offset(cachep)];
+
+	memset(addr, val, size);
+	*(unsigned char *)(addr + size - 1) = POISON_END;
+}
+
+static void dump_line(char *data, int offset, int limit)
+{
+	int i;
+	unsigned char error = 0;
+	int bad_count = 0;
+
+	printk(KERN_ERR "%03x: ", offset);
+	for (i = 0; i < limit; i++) {
+		if (data[offset + i] != POISON_FREE) {
+			error = data[offset + i];
+			bad_count++;
+		}
+	}
+	print_hex_dump(KERN_CONT, "", 0, 16, 1,
+			&data[offset], limit, 1);
+
+	if (bad_count == 1) {
+		error ^= POISON_FREE;
+		if (!(error & (error - 1))) {
+			printk(KERN_ERR "Single bit error detected. Probably "
+					"bad RAM.\n");
+#ifdef CONFIG_X86
+			printk(KERN_ERR "Run memtest86+ or a similar memory "
+					"test tool.\n");
+#else
+			printk(KERN_ERR "Run a memory test tool.\n");
+#endif
+		}
+	}
+}
+#endif
+
+#if DEBUG
+
+static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines)
+{
+	int i, size;
+	char *realobj;
+
+	if (cachep->flags & SLAB_RED_ZONE) {
+		printk(KERN_ERR "Redzone: 0x%llx/0x%llx.\n",
+			*dbg_redzone1(cachep, objp),
+			*dbg_redzone2(cachep, objp));
+	}
+
+	if (cachep->flags & SLAB_STORE_USER) {
+		printk(KERN_ERR "Last user: [<%p>](%pSR)\n",
+		       *dbg_userword(cachep, objp),
+		       *dbg_userword(cachep, objp));
+	}
+	realobj = (char *)objp + obj_offset(cachep);
+	size = cachep->object_size;
+	for (i = 0; i < size && lines; i += 16, lines--) {
+		int limit;
+		limit = 16;
+		if (i + limit > size)
+			limit = size - i;
+		dump_line(realobj, i, limit);
+	}
+}
+
+static void check_poison_obj(struct kmem_cache *cachep, void *objp)
+{
+	char *realobj;
+	int size, i;
+	int lines = 0;
+
+	realobj = (char *)objp + obj_offset(cachep);
+	size = cachep->object_size;
+
+	for (i = 0; i < size; i++) {
+		char exp = POISON_FREE;
+		if (i == size - 1)
+			exp = POISON_END;
+		if (realobj[i] != exp) {
+			int limit;
+			/* Mismatch ! */
+			/* Print header */
+			if (lines == 0) {
+				printk(KERN_ERR
+					"Slab corruption (%s): %s start=%p, len=%d\n",
+					print_tainted(), cachep->name, realobj, size);
+				print_objinfo(cachep, objp, 0);
+			}
+			/* Hexdump the affected line */
+			i = (i / 16) * 16;
+			limit = 16;
+			if (i + limit > size)
+				limit = size - i;
+			dump_line(realobj, i, limit);
+			i += 16;
+			lines++;
+			/* Limit to 5 lines */
+			if (lines > 5)
+				break;
+		}
+	}
+	if (lines != 0) {
+		/* Print some data about the neighboring objects, if they
+		 * exist:
+		 */
+		struct page *page = virt_to_head_page(objp);
+		unsigned int objnr;
+
+		objnr = obj_to_index(cachep, page, objp);
+		if (objnr) {
+			objp = index_to_obj(cachep, page, objnr - 1);
+			realobj = (char *)objp + obj_offset(cachep);
+			printk(KERN_ERR "Prev obj: start=%p, len=%d\n",
+			       realobj, size);
+			print_objinfo(cachep, objp, 2);
+		}
+		if (objnr + 1 < cachep->num) {
+			objp = index_to_obj(cachep, page, objnr + 1);
+			realobj = (char *)objp + obj_offset(cachep);
+			printk(KERN_ERR "Next obj: start=%p, len=%d\n",
+			       realobj, size);
+			print_objinfo(cachep, objp, 2);
+		}
+	}
+}
+#endif
+
+#if DEBUG
+static void slab_destroy_debugcheck(struct kmem_cache *cachep,
+						struct page *page)
+{
+	int i;
+	for (i = 0; i < cachep->num; i++) {
+		void *objp = index_to_obj(cachep, page, i);
+
+		if (cachep->flags & SLAB_POISON) {
+#ifdef CONFIG_DEBUG_PAGEALLOC
+			if (cachep->size % PAGE_SIZE == 0 &&
+					OFF_SLAB(cachep))
+				kernel_map_pages(virt_to_page(objp),
+					cachep->size / PAGE_SIZE, 1);
+			else
+				check_poison_obj(cachep, objp);
+#else
+			check_poison_obj(cachep, objp);
+#endif
+		}
+		if (cachep->flags & SLAB_RED_ZONE) {
+			if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
+				slab_error(cachep, "start of a freed object "
+					   "was overwritten");
+			if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
+				slab_error(cachep, "end of a freed object "
+					   "was overwritten");
+		}
+	}
+}
+#else
+static void slab_destroy_debugcheck(struct kmem_cache *cachep,
+						struct page *page)
+{
+}
+#endif
+
+/**
+ * slab_destroy - destroy and release all objects in a slab
+ * @cachep: cache pointer being destroyed
+ * @page: page pointer being destroyed
+ *
+ * Destroy all the objs in a slab page, and release the mem back to the system.
+ * Before calling the slab page must have been unlinked from the cache. The
+ * kmem_cache_node ->list_lock is not held/needed.
+ */
+static void slab_destroy(struct kmem_cache *cachep, struct page *page)
+{
+	void *freelist;
+
+	freelist = page->freelist;
+	slab_destroy_debugcheck(cachep, page);
+	if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
+		call_rcu(&page->rcu_head, kmem_rcu_free);
+	else
+		kmem_freepages(cachep, page);
+
+	/*
+	 * From now on, we don't use freelist
+	 * although actual page can be freed in rcu context
+	 */
+	if (OFF_SLAB(cachep))
+		kmem_cache_free(cachep->freelist_cache, freelist);
+}
+
+static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list)
+{
+	struct page *page, *n;
+
+	list_for_each_entry_safe(page, n, list, lru) {
+		list_del(&page->lru);
+		slab_destroy(cachep, page);
+	}
+}
+
+/**
+ * calculate_slab_order - calculate size (page order) of slabs
+ * @cachep: pointer to the cache that is being created
+ * @size: size of objects to be created in this cache.
+ * @align: required alignment for the objects.
+ * @flags: slab allocation flags
+ *
+ * Also calculates the number of objects per slab.
+ *
+ * This could be made much more intelligent.  For now, try to avoid using
+ * high order pages for slabs.  When the gfp() functions are more friendly
+ * towards high-order requests, this should be changed.
+ */
+static size_t calculate_slab_order(struct kmem_cache *cachep,
+			size_t size, size_t align, unsigned long flags)
+{
+	unsigned long offslab_limit;
+	size_t left_over = 0;
+	int gfporder;
+
+	for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
+		unsigned int num;
+		size_t remainder;
+
+		cache_estimate(gfporder, size, align, flags, &remainder, &num);
+		if (!num)
+			continue;
+
+		/* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */
+		if (num > SLAB_OBJ_MAX_NUM)
+			break;
+
+		if (flags & CFLGS_OFF_SLAB) {
+			size_t freelist_size_per_obj = sizeof(freelist_idx_t);
+			/*
+			 * Max number of objs-per-slab for caches which
+			 * use off-slab slabs. Needed to avoid a possible
+			 * looping condition in cache_grow().
+			 */
+			if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK))
+				freelist_size_per_obj += sizeof(char);
+			offslab_limit = size;
+			offslab_limit /= freelist_size_per_obj;
+
+ 			if (num > offslab_limit)
+				break;
+		}
+
+		/* Found something acceptable - save it away */
+		cachep->num = num;
+		cachep->gfporder = gfporder;
+		left_over = remainder;
+
+		/*
+		 * A VFS-reclaimable slab tends to have most allocations
+		 * as GFP_NOFS and we really don't want to have to be allocating
+		 * higher-order pages when we are unable to shrink dcache.
+		 */
+		if (flags & SLAB_RECLAIM_ACCOUNT)
+			break;
+
+		/*
+		 * Large number of objects is good, but very large slabs are
+		 * currently bad for the gfp()s.
+		 */
+		if (gfporder >= slab_max_order)
+			break;
+
+		/*
+		 * Acceptable internal fragmentation?
+		 */
+		if (left_over * 8 <= (PAGE_SIZE << gfporder))
+			break;
+	}
+	return left_over;
+}
+
+static struct array_cache __percpu *alloc_kmem_cache_cpus(
+		struct kmem_cache *cachep, int entries, int batchcount)
+{
+	int cpu;
+	size_t size;
+	struct array_cache __percpu *cpu_cache;
+
+	size = sizeof(void *) * entries + sizeof(struct array_cache);
+	cpu_cache = __alloc_percpu(size, sizeof(void *));
+
+	if (!cpu_cache)
+		return NULL;
+
+	for_each_possible_cpu(cpu) {
+		init_arraycache(per_cpu_ptr(cpu_cache, cpu),
+				entries, batchcount);
+	}
+
+	return cpu_cache;
+}
+
+static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
+{
+	if (slab_state >= FULL)
+		return enable_cpucache(cachep, gfp);
+
+	cachep->cpu_cache = alloc_kmem_cache_cpus(cachep, 1, 1);
+	if (!cachep->cpu_cache)
+		return 1;
+
+	if (slab_state == DOWN) {
+		/* Creation of first cache (kmem_cache). */
+		set_up_node(kmem_cache, CACHE_CACHE);
+	} else if (slab_state == PARTIAL) {
+		/* For kmem_cache_node */
+		set_up_node(cachep, SIZE_NODE);
+	} else {
+		int node;
+
+		for_each_online_node(node) {
+			cachep->node[node] = kmalloc_node(
+				sizeof(struct kmem_cache_node), gfp, node);
+			BUG_ON(!cachep->node[node]);
+			kmem_cache_node_init(cachep->node[node]);
+		}
+	}
+
+	cachep->node[numa_mem_id()]->next_reap =
+			jiffies + REAPTIMEOUT_NODE +
+			((unsigned long)cachep) % REAPTIMEOUT_NODE;
+
+	cpu_cache_get(cachep)->avail = 0;
+	cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
+	cpu_cache_get(cachep)->batchcount = 1;
+	cpu_cache_get(cachep)->touched = 0;
+	cachep->batchcount = 1;
+	cachep->limit = BOOT_CPUCACHE_ENTRIES;
+	return 0;
+}
+
+unsigned long kmem_cache_flags(unsigned long object_size,
+	unsigned long flags, const char *name,
+	void (*ctor)(void *))
+{
+	return flags;
+}
+
+struct kmem_cache *
+__kmem_cache_alias(const char *name, size_t size, size_t align,
+		   unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *cachep;
+
+	cachep = find_mergeable(size, align, flags, name, ctor);
+	if (cachep) {
+		cachep->refcount++;
+
+		/*
+		 * Adjust the object sizes so that we clear
+		 * the complete object on kzalloc.
+		 */
+		cachep->object_size = max_t(int, cachep->object_size, size);
+	}
+	return cachep;
+}
+
+/**
+ * __kmem_cache_create - Create a cache.
+ * @cachep: cache management descriptor
+ * @flags: SLAB flags
+ *
+ * Returns a ptr to the cache on success, NULL on failure.
+ * Cannot be called within a int, but can be interrupted.
+ * The @ctor is run when new pages are allocated by the cache.
+ *
+ * The flags are
+ *
+ * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
+ * to catch references to uninitialised memory.
+ *
+ * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
+ * for buffer overruns.
+ *
+ * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
+ * cacheline.  This can be beneficial if you're counting cycles as closely
+ * as davem.
+ */
+int
+__kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
+{
+	size_t left_over, freelist_size;
+	size_t ralign = BYTES_PER_WORD;
+	gfp_t gfp;
+	int err;
+	size_t size = cachep->size;
+
+#if DEBUG
+#if FORCED_DEBUG
+	/*
+	 * Enable redzoning and last user accounting, except for caches with
+	 * large objects, if the increased size would increase the object size
+	 * above the next power of two: caches with object sizes just above a
+	 * power of two have a significant amount of internal fragmentation.
+	 */
+	if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
+						2 * sizeof(unsigned long long)))
+		flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
+	if (!(flags & SLAB_DESTROY_BY_RCU))
+		flags |= SLAB_POISON;
+#endif
+	if (flags & SLAB_DESTROY_BY_RCU)
+		BUG_ON(flags & SLAB_POISON);
+#endif
+
+	/*
+	 * Check that size is in terms of words.  This is needed to avoid
+	 * unaligned accesses for some archs when redzoning is used, and makes
+	 * sure any on-slab bufctl's are also correctly aligned.
+	 */
+	if (size & (BYTES_PER_WORD - 1)) {
+		size += (BYTES_PER_WORD - 1);
+		size &= ~(BYTES_PER_WORD - 1);
+	}
+
+	if (flags & SLAB_RED_ZONE) {
+		ralign = REDZONE_ALIGN;
+		/* If redzoning, ensure that the second redzone is suitably
+		 * aligned, by adjusting the object size accordingly. */
+		size += REDZONE_ALIGN - 1;
+		size &= ~(REDZONE_ALIGN - 1);
+	}
+
+	/* 3) caller mandated alignment */
+	if (ralign < cachep->align) {
+		ralign = cachep->align;
+	}
+	/* disable debug if necessary */
+	if (ralign > __alignof__(unsigned long long))
+		flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
+	/*
+	 * 4) Store it.
+	 */
+	cachep->align = ralign;
+
+	if (slab_is_available())
+		gfp = GFP_KERNEL;
+	else
+		gfp = GFP_NOWAIT;
+
+#if DEBUG
+
+	/*
+	 * Both debugging options require word-alignment which is calculated
+	 * into align above.
+	 */
+	if (flags & SLAB_RED_ZONE) {
+		/* add space for red zone words */
+		cachep->obj_offset += sizeof(unsigned long long);
+		size += 2 * sizeof(unsigned long long);
+	}
+	if (flags & SLAB_STORE_USER) {
+		/* user store requires one word storage behind the end of
+		 * the real object. But if the second red zone needs to be
+		 * aligned to 64 bits, we must allow that much space.
+		 */
+		if (flags & SLAB_RED_ZONE)
+			size += REDZONE_ALIGN;
+		else
+			size += BYTES_PER_WORD;
+	}
+#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)
+	/*
+	 * To activate debug pagealloc, off-slab management is necessary
+	 * requirement. In early phase of initialization, small sized slab
+	 * doesn't get initialized so it would not be possible. So, we need
+	 * to check size >= 256. It guarantees that all necessary small
+	 * sized slab is initialized in current slab initialization sequence.
+	 */
+	if (!slab_early_init && size >= kmalloc_size(INDEX_NODE) &&
+		size >= 256 && cachep->object_size > cache_line_size() &&
+		ALIGN(size, cachep->align) < PAGE_SIZE) {
+		cachep->obj_offset += PAGE_SIZE - ALIGN(size, cachep->align);
+		size = PAGE_SIZE;
+	}
+#endif
+#endif
+
+	/*
+	 * Determine if the slab management is 'on' or 'off' slab.
+	 * (bootstrapping cannot cope with offslab caches so don't do
+	 * it too early on. Always use on-slab management when
+	 * SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak)
+	 */
+	if (size >= OFF_SLAB_MIN_SIZE && !slab_early_init &&
+	    !(flags & SLAB_NOLEAKTRACE))
+		/*
+		 * Size is large, assume best to place the slab management obj
+		 * off-slab (should allow better packing of objs).
+		 */
+		flags |= CFLGS_OFF_SLAB;
+
+	size = ALIGN(size, cachep->align);
+	/*
+	 * We should restrict the number of objects in a slab to implement
+	 * byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition.
+	 */
+	if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE)
+		size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align);
+
+	left_over = calculate_slab_order(cachep, size, cachep->align, flags);
+
+	if (!cachep->num)
+		return -E2BIG;
+
+	freelist_size = calculate_freelist_size(cachep->num, cachep->align);
+
+	/*
+	 * If the slab has been placed off-slab, and we have enough space then
+	 * move it on-slab. This is at the expense of any extra colouring.
+	 */
+	if (flags & CFLGS_OFF_SLAB && left_over >= freelist_size) {
+		flags &= ~CFLGS_OFF_SLAB;
+		left_over -= freelist_size;
+	}
+
+	if (flags & CFLGS_OFF_SLAB) {
+		/* really off slab. No need for manual alignment */
+		freelist_size = calculate_freelist_size(cachep->num, 0);
+
+#ifdef CONFIG_PAGE_POISONING
+		/* If we're going to use the generic kernel_map_pages()
+		 * poisoning, then it's going to smash the contents of
+		 * the redzone and userword anyhow, so switch them off.
+		 */
+		if (size % PAGE_SIZE == 0 && flags & SLAB_POISON)
+			flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
+#endif
+	}
+
+	cachep->colour_off = cache_line_size();
+	/* Offset must be a multiple of the alignment. */
+	if (cachep->colour_off < cachep->align)
+		cachep->colour_off = cachep->align;
+	cachep->colour = left_over / cachep->colour_off;
+	cachep->freelist_size = freelist_size;
+	cachep->flags = flags;
+	cachep->allocflags = __GFP_COMP;
+	if (CONFIG_ZONE_DMA_FLAG && (flags & SLAB_CACHE_DMA))
+		cachep->allocflags |= GFP_DMA;
+	cachep->size = size;
+	cachep->reciprocal_buffer_size = reciprocal_value(size);
+
+	if (flags & CFLGS_OFF_SLAB) {
+		cachep->freelist_cache = kmalloc_slab(freelist_size, 0u);
+		/*
+		 * This is a possibility for one of the kmalloc_{dma,}_caches.
+		 * But since we go off slab only for object size greater than
+		 * OFF_SLAB_MIN_SIZE, and kmalloc_{dma,}_caches get created
+		 * in ascending order,this should not happen at all.
+		 * But leave a BUG_ON for some lucky dude.
+		 */
+		BUG_ON(ZERO_OR_NULL_PTR(cachep->freelist_cache));
+	}
+
+	err = setup_cpu_cache(cachep, gfp);
+	if (err) {
+		__kmem_cache_shutdown(cachep);
+		return err;
+	}
+
+	return 0;
+}
+
+#if DEBUG
+static void check_irq_off(void)
+{
+	BUG_ON(!irqs_disabled());
+}
+
+static void check_irq_on(void)
+{
+	BUG_ON(irqs_disabled());
+}
+
+static void check_spinlock_acquired(struct kmem_cache *cachep)
+{
+#ifdef CONFIG_SMP
+	check_irq_off();
+	assert_spin_locked(&get_node(cachep, numa_mem_id())->list_lock);
+#endif
+}
+
+static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
+{
+#ifdef CONFIG_SMP
+	check_irq_off();
+	assert_spin_locked(&get_node(cachep, node)->list_lock);
+#endif
+}
+
+#else
+#define check_irq_off()	do { } while(0)
+#define check_irq_on()	do { } while(0)
+#define check_spinlock_acquired(x) do { } while(0)
+#define check_spinlock_acquired_node(x, y) do { } while(0)
+#endif
+
+static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n,
+			struct array_cache *ac,
+			int force, int node);
+
+static void do_drain(void *arg)
+{
+	struct kmem_cache *cachep = arg;
+	struct array_cache *ac;
+	int node = numa_mem_id();
+	struct kmem_cache_node *n;
+	LIST_HEAD(list);
+
+	check_irq_off();
+	ac = cpu_cache_get(cachep);
+	n = get_node(cachep, node);
+	spin_lock(&n->list_lock);
+	free_block(cachep, ac->entry, ac->avail, node, &list);
+	spin_unlock(&n->list_lock);
+	slabs_destroy(cachep, &list);
+	ac->avail = 0;
+}
+
+static void drain_cpu_caches(struct kmem_cache *cachep)
+{
+	struct kmem_cache_node *n;
+	int node;
+
+	on_each_cpu(do_drain, cachep, 1);
+	check_irq_on();
+	for_each_kmem_cache_node(cachep, node, n)
+		if (n->alien)
+			drain_alien_cache(cachep, n->alien);
+
+	for_each_kmem_cache_node(cachep, node, n)
+		drain_array(cachep, n, n->shared, 1, node);
+}
+
+/*
+ * Remove slabs from the list of free slabs.
+ * Specify the number of slabs to drain in tofree.
+ *
+ * Returns the actual number of slabs released.
+ */
+static int drain_freelist(struct kmem_cache *cache,
+			struct kmem_cache_node *n, int tofree)
+{
+	struct list_head *p;
+	int nr_freed;
+	struct page *page;
+
+	nr_freed = 0;
+	while (nr_freed < tofree && !list_empty(&n->slabs_free)) {
+
+		spin_lock_irq(&n->list_lock);
+		p = n->slabs_free.prev;
+		if (p == &n->slabs_free) {
+			spin_unlock_irq(&n->list_lock);
+			goto out;
+		}
+
+		page = list_entry(p, struct page, lru);
+#if DEBUG
+		BUG_ON(page->active);
+#endif
+		list_del(&page->lru);
+		/*
+		 * Safe to drop the lock. The slab is no longer linked
+		 * to the cache.
+		 */
+		n->free_objects -= cache->num;
+		spin_unlock_irq(&n->list_lock);
+		slab_destroy(cache, page);
+		nr_freed++;
+	}
+out:
+	return nr_freed;
+}
+
+int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate)
+{
+	int ret = 0;
+	int node;
+	struct kmem_cache_node *n;
+
+	drain_cpu_caches(cachep);
+
+	check_irq_on();
+	for_each_kmem_cache_node(cachep, node, n) {
+		drain_freelist(cachep, n, slabs_tofree(cachep, n));
+
+		ret += !list_empty(&n->slabs_full) ||
+			!list_empty(&n->slabs_partial);
+	}
+	return (ret ? 1 : 0);
+}
+
+int __kmem_cache_shutdown(struct kmem_cache *cachep)
+{
+	int i;
+	struct kmem_cache_node *n;
+	int rc = __kmem_cache_shrink(cachep, false);
+
+	if (rc)
+		return rc;
+
+	free_percpu(cachep->cpu_cache);
+
+	/* NUMA: free the node structures */
+	for_each_kmem_cache_node(cachep, i, n) {
+		kfree(n->shared);
+		free_alien_cache(n->alien);
+		kfree(n);
+		cachep->node[i] = NULL;
+	}
+	return 0;
+}
+
+/*
+ * Get the memory for a slab management obj.
+ *
+ * For a slab cache when the slab descriptor is off-slab, the
+ * slab descriptor can't come from the same cache which is being created,
+ * Because if it is the case, that means we defer the creation of
+ * the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point.
+ * And we eventually call down to __kmem_cache_create(), which
+ * in turn looks up in the kmalloc_{dma,}_caches for the disired-size one.
+ * This is a "chicken-and-egg" problem.
+ *
+ * So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches,
+ * which are all initialized during kmem_cache_init().
+ */
+static void *alloc_slabmgmt(struct kmem_cache *cachep,
+				   struct page *page, int colour_off,
+				   gfp_t local_flags, int nodeid)
+{
+	void *freelist;
+	void *addr = page_address(page);
+
+	if (OFF_SLAB(cachep)) {
+		/* Slab management obj is off-slab. */
+		freelist = kmem_cache_alloc_node(cachep->freelist_cache,
+					      local_flags, nodeid);
+		if (!freelist)
+			return NULL;
+	} else {
+		freelist = addr + colour_off;
+		colour_off += cachep->freelist_size;
+	}
+	page->active = 0;
+	page->s_mem = addr + colour_off;
+	return freelist;
+}
+
+static inline freelist_idx_t get_free_obj(struct page *page, unsigned int idx)
+{
+	return ((freelist_idx_t *)page->freelist)[idx];
+}
+
+static inline void set_free_obj(struct page *page,
+					unsigned int idx, freelist_idx_t val)
+{
+	((freelist_idx_t *)(page->freelist))[idx] = val;
+}
+
+static void cache_init_objs(struct kmem_cache *cachep,
+			    struct page *page)
+{
+	int i;
+
+	for (i = 0; i < cachep->num; i++) {
+		void *objp = index_to_obj(cachep, page, i);
+#if DEBUG
+		/* need to poison the objs? */
+		if (cachep->flags & SLAB_POISON)
+			poison_obj(cachep, objp, POISON_FREE);
+		if (cachep->flags & SLAB_STORE_USER)
+			*dbg_userword(cachep, objp) = NULL;
+
+		if (cachep->flags & SLAB_RED_ZONE) {
+			*dbg_redzone1(cachep, objp) = RED_INACTIVE;
+			*dbg_redzone2(cachep, objp) = RED_INACTIVE;
+		}
+		/*
+		 * Constructors are not allowed to allocate memory from the same
+		 * cache which they are a constructor for.  Otherwise, deadlock.
+		 * They must also be threaded.
+		 */
+		if (cachep->ctor && !(cachep->flags & SLAB_POISON))
+			cachep->ctor(objp + obj_offset(cachep));
+
+		if (cachep->flags & SLAB_RED_ZONE) {
+			if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
+				slab_error(cachep, "constructor overwrote the"
+					   " end of an object");
+			if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
+				slab_error(cachep, "constructor overwrote the"
+					   " start of an object");
+		}
+		if ((cachep->size % PAGE_SIZE) == 0 &&
+			    OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
+			kernel_map_pages(virt_to_page(objp),
+					 cachep->size / PAGE_SIZE, 0);
+#else
+		if (cachep->ctor)
+			cachep->ctor(objp);
+#endif
+		set_obj_status(page, i, OBJECT_FREE);
+		set_free_obj(page, i, i);
+	}
+}
+
+static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags)
+{
+	if (CONFIG_ZONE_DMA_FLAG) {
+		if (flags & GFP_DMA)
+			BUG_ON(!(cachep->allocflags & GFP_DMA));
+		else
+			BUG_ON(cachep->allocflags & GFP_DMA);
+	}
+}
+
+static void *slab_get_obj(struct kmem_cache *cachep, struct page *page,
+				int nodeid)
+{
+	void *objp;
+
+	objp = index_to_obj(cachep, page, get_free_obj(page, page->active));
+	page->active++;
+#if DEBUG
+	WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
+#endif
+
+	return objp;
+}
+
+static void slab_put_obj(struct kmem_cache *cachep, struct page *page,
+				void *objp, int nodeid)
+{
+	unsigned int objnr = obj_to_index(cachep, page, objp);
+#if DEBUG
+	unsigned int i;
+
+	/* Verify that the slab belongs to the intended node */
+	WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
+
+	/* Verify double free bug */
+	for (i = page->active; i < cachep->num; i++) {
+		if (get_free_obj(page, i) == objnr) {
+			printk(KERN_ERR "slab: double free detected in cache "
+					"'%s', objp %p\n", cachep->name, objp);
+			BUG();
+		}
+	}
+#endif
+	page->active--;
+	set_free_obj(page, page->active, objnr);
+}
+
+/*
+ * Map pages beginning at addr to the given cache and slab. This is required
+ * for the slab allocator to be able to lookup the cache and slab of a
+ * virtual address for kfree, ksize, and slab debugging.
+ */
+static void slab_map_pages(struct kmem_cache *cache, struct page *page,
+			   void *freelist)
+{
+	page->slab_cache = cache;
+	page->freelist = freelist;
+}
+
+/*
+ * Grow (by 1) the number of slabs within a cache.  This is called by
+ * kmem_cache_alloc() when there are no active objs left in a cache.
+ */
+static int cache_grow(struct kmem_cache *cachep,
+		gfp_t flags, int nodeid, struct page *page)
+{
+	void *freelist;
+	size_t offset;
+	gfp_t local_flags;
+	struct kmem_cache_node *n;
+
+	/*
+	 * Be lazy and only check for valid flags here,  keeping it out of the
+	 * critical path in kmem_cache_alloc().
+	 */
+	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
+		pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK);
+		BUG();
+	}
+	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
+
+	/* Take the node list lock to change the colour_next on this node */
+	check_irq_off();
+	n = get_node(cachep, nodeid);
+	spin_lock(&n->list_lock);
+
+	/* Get colour for the slab, and cal the next value. */
+	offset = n->colour_next;
+	n->colour_next++;
+	if (n->colour_next >= cachep->colour)
+		n->colour_next = 0;
+	spin_unlock(&n->list_lock);
+
+	offset *= cachep->colour_off;
+
+	if (gfpflags_allow_blocking(local_flags))
+		local_irq_enable();
+
+	/*
+	 * The test for missing atomic flag is performed here, rather than
+	 * the more obvious place, simply to reduce the critical path length
+	 * in kmem_cache_alloc(). If a caller is seriously mis-behaving they
+	 * will eventually be caught here (where it matters).
+	 */
+	kmem_flagcheck(cachep, flags);
+
+	/*
+	 * Get mem for the objs.  Attempt to allocate a physical page from
+	 * 'nodeid'.
+	 */
+	if (!page)
+		page = kmem_getpages(cachep, local_flags, nodeid);
+	if (!page)
+		goto failed;
+
+	/* Get slab management. */
+	freelist = alloc_slabmgmt(cachep, page, offset,
+			local_flags & ~GFP_CONSTRAINT_MASK, nodeid);
+	if (!freelist)
+		goto opps1;
+
+	slab_map_pages(cachep, page, freelist);
+
+	cache_init_objs(cachep, page);
+
+	if (gfpflags_allow_blocking(local_flags))
+		local_irq_disable();
+	check_irq_off();
+	spin_lock(&n->list_lock);
+
+	/* Make slab active. */
+	list_add_tail(&page->lru, &(n->slabs_free));
+	STATS_INC_GROWN(cachep);
+	n->free_objects += cachep->num;
+	spin_unlock(&n->list_lock);
+	return 1;
+opps1:
+	kmem_freepages(cachep, page);
+failed:
+	if (gfpflags_allow_blocking(local_flags))
+		local_irq_disable();
+	return 0;
+}
+
+#if DEBUG
+
+/*
+ * Perform extra freeing checks:
+ * - detect bad pointers.
+ * - POISON/RED_ZONE checking
+ */
+static void kfree_debugcheck(const void *objp)
+{
+	if (!virt_addr_valid(objp)) {
+		printk(KERN_ERR "kfree_debugcheck: out of range ptr %lxh.\n",
+		       (unsigned long)objp);
+		BUG();
+	}
+}
+
+static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
+{
+	unsigned long long redzone1, redzone2;
+
+	redzone1 = *dbg_redzone1(cache, obj);
+	redzone2 = *dbg_redzone2(cache, obj);
+
+	/*
+	 * Redzone is ok.
+	 */
+	if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
+		return;
+
+	if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
+		slab_error(cache, "double free detected");
+	else
+		slab_error(cache, "memory outside object was overwritten");
+
+	printk(KERN_ERR "%p: redzone 1:0x%llx, redzone 2:0x%llx.\n",
+			obj, redzone1, redzone2);
+}
+
+static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
+				   unsigned long caller)
+{
+	unsigned int objnr;
+	struct page *page;
+
+	BUG_ON(virt_to_cache(objp) != cachep);
+
+	objp -= obj_offset(cachep);
+	kfree_debugcheck(objp);
+	page = virt_to_head_page(objp);
+
+	if (cachep->flags & SLAB_RED_ZONE) {
+		verify_redzone_free(cachep, objp);
+		*dbg_redzone1(cachep, objp) = RED_INACTIVE;
+		*dbg_redzone2(cachep, objp) = RED_INACTIVE;
+	}
+	if (cachep->flags & SLAB_STORE_USER)
+		*dbg_userword(cachep, objp) = (void *)caller;
+
+	objnr = obj_to_index(cachep, page, objp);
+
+	BUG_ON(objnr >= cachep->num);
+	BUG_ON(objp != index_to_obj(cachep, page, objnr));
+
+	set_obj_status(page, objnr, OBJECT_FREE);
+	if (cachep->flags & SLAB_POISON) {
+#ifdef CONFIG_DEBUG_PAGEALLOC
+		if ((cachep->size % PAGE_SIZE)==0 && OFF_SLAB(cachep)) {
+			store_stackinfo(cachep, objp, caller);
+			kernel_map_pages(virt_to_page(objp),
+					 cachep->size / PAGE_SIZE, 0);
+		} else {
+			poison_obj(cachep, objp, POISON_FREE);
+		}
+#else
+		poison_obj(cachep, objp, POISON_FREE);
+#endif
+	}
+	return objp;
+}
+
+#else
+#define kfree_debugcheck(x) do { } while(0)
+#define cache_free_debugcheck(x,objp,z) (objp)
+#endif
+
+static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags,
+							bool force_refill)
+{
+	int batchcount;
+	struct kmem_cache_node *n;
+	struct array_cache *ac;
+	int node;
+
+	check_irq_off();
+	node = numa_mem_id();
+	if (unlikely(force_refill))
+		goto force_grow;
+retry:
+	ac = cpu_cache_get(cachep);
+	batchcount = ac->batchcount;
+	if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
+		/*
+		 * If there was little recent activity on this cache, then
+		 * perform only a partial refill.  Otherwise we could generate
+		 * refill bouncing.
+		 */
+		batchcount = BATCHREFILL_LIMIT;
+	}
+	n = get_node(cachep, node);
+
+	BUG_ON(ac->avail > 0 || !n);
+	spin_lock(&n->list_lock);
+
+	/* See if we can refill from the shared array */
+	if (n->shared && transfer_objects(ac, n->shared, batchcount)) {
+		n->shared->touched = 1;
+		goto alloc_done;
+	}
+
+	while (batchcount > 0) {
+		struct list_head *entry;
+		struct page *page;
+		/* Get slab alloc is to come from. */
+		entry = n->slabs_partial.next;
+		if (entry == &n->slabs_partial) {
+			n->free_touched = 1;
+			entry = n->slabs_free.next;
+			if (entry == &n->slabs_free)
+				goto must_grow;
+		}
+
+		page = list_entry(entry, struct page, lru);
+		check_spinlock_acquired(cachep);
+
+		/*
+		 * The slab was either on partial or free list so
+		 * there must be at least one object available for
+		 * allocation.
+		 */
+		BUG_ON(page->active >= cachep->num);
+
+		while (page->active < cachep->num && batchcount--) {
+			STATS_INC_ALLOCED(cachep);
+			STATS_INC_ACTIVE(cachep);
+			STATS_SET_HIGH(cachep);
+
+			ac_put_obj(cachep, ac, slab_get_obj(cachep, page,
+									node));
+		}
+
+		/* move slabp to correct slabp list: */
+		list_del(&page->lru);
+		if (page->active == cachep->num)
+			list_add(&page->lru, &n->slabs_full);
+		else
+			list_add(&page->lru, &n->slabs_partial);
+	}
+
+must_grow:
+	n->free_objects -= ac->avail;
+alloc_done:
+	spin_unlock(&n->list_lock);
+
+	if (unlikely(!ac->avail)) {
+		int x;
+force_grow:
+		x = cache_grow(cachep, gfp_exact_node(flags), node, NULL);
+
+		/* cache_grow can reenable interrupts, then ac could change. */
+		ac = cpu_cache_get(cachep);
+		node = numa_mem_id();
+
+		/* no objects in sight? abort */
+		if (!x && (ac->avail == 0 || force_refill))
+			return NULL;
+
+		if (!ac->avail)		/* objects refilled by interrupt? */
+			goto retry;
+	}
+	ac->touched = 1;
+
+	return ac_get_obj(cachep, ac, flags, force_refill);
+}
+
+static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
+						gfp_t flags)
+{
+	might_sleep_if(gfpflags_allow_blocking(flags));
+#if DEBUG
+	kmem_flagcheck(cachep, flags);
+#endif
+}
+
+#if DEBUG
+static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
+				gfp_t flags, void *objp, unsigned long caller)
+{
+	struct page *page;
+
+	if (!objp)
+		return objp;
+	if (cachep->flags & SLAB_POISON) {
+#ifdef CONFIG_DEBUG_PAGEALLOC
+		if ((cachep->size % PAGE_SIZE) == 0 && OFF_SLAB(cachep))
+			kernel_map_pages(virt_to_page(objp),
+					 cachep->size / PAGE_SIZE, 1);
+		else
+			check_poison_obj(cachep, objp);
+#else
+		check_poison_obj(cachep, objp);
+#endif
+		poison_obj(cachep, objp, POISON_INUSE);
+	}
+	if (cachep->flags & SLAB_STORE_USER)
+		*dbg_userword(cachep, objp) = (void *)caller;
+
+	if (cachep->flags & SLAB_RED_ZONE) {
+		if (*dbg_redzone1(cachep, objp) != RED_INACTIVE ||
+				*dbg_redzone2(cachep, objp) != RED_INACTIVE) {
+			slab_error(cachep, "double free, or memory outside"
+						" object was overwritten");
+			printk(KERN_ERR
+				"%p: redzone 1:0x%llx, redzone 2:0x%llx\n",
+				objp, *dbg_redzone1(cachep, objp),
+				*dbg_redzone2(cachep, objp));
+		}
+		*dbg_redzone1(cachep, objp) = RED_ACTIVE;
+		*dbg_redzone2(cachep, objp) = RED_ACTIVE;
+	}
+
+	page = virt_to_head_page(objp);
+	set_obj_status(page, obj_to_index(cachep, page, objp), OBJECT_ACTIVE);
+	objp += obj_offset(cachep);
+	if (cachep->ctor && cachep->flags & SLAB_POISON)
+		cachep->ctor(objp);
+	if (ARCH_SLAB_MINALIGN &&
+	    ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) {
+		printk(KERN_ERR "0x%p: not aligned to ARCH_SLAB_MINALIGN=%d\n",
+		       objp, (int)ARCH_SLAB_MINALIGN);
+	}
+	return objp;
+}
+#else
+#define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
+#endif
+
+static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
+{
+	if (unlikely(cachep == kmem_cache))
+		return false;
+
+	return should_failslab(cachep->object_size, flags, cachep->flags);
+}
+
+static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+	void *objp;
+	struct array_cache *ac;
+	bool force_refill = false;
+
+	check_irq_off();
+
+	ac = cpu_cache_get(cachep);
+	if (likely(ac->avail)) {
+		ac->touched = 1;
+		objp = ac_get_obj(cachep, ac, flags, false);
+
+		/*
+		 * Allow for the possibility all avail objects are not allowed
+		 * by the current flags
+		 */
+		if (objp) {
+			STATS_INC_ALLOCHIT(cachep);
+			goto out;
+		}
+		force_refill = true;
+	}
+
+	STATS_INC_ALLOCMISS(cachep);
+	objp = cache_alloc_refill(cachep, flags, force_refill);
+	/*
+	 * the 'ac' may be updated by cache_alloc_refill(),
+	 * and kmemleak_erase() requires its correct value.
+	 */
+	ac = cpu_cache_get(cachep);
+
+out:
+	/*
+	 * To avoid a false negative, if an object that is in one of the
+	 * per-CPU caches is leaked, we need to make sure kmemleak doesn't
+	 * treat the array pointers as a reference to the object.
+	 */
+	if (objp)
+		kmemleak_erase(&ac->entry[ac->avail]);
+	return objp;
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
+ *
+ * If we are in_interrupt, then process context, including cpusets and
+ * mempolicy, may not apply and should not be used for allocation policy.
+ */
+static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+	int nid_alloc, nid_here;
+
+	if (in_interrupt() || (flags & __GFP_THISNODE))
+		return NULL;
+	nid_alloc = nid_here = numa_mem_id();
+	if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
+		nid_alloc = cpuset_slab_spread_node();
+	else if (current->mempolicy)
+		nid_alloc = mempolicy_slab_node();
+	if (nid_alloc != nid_here)
+		return ____cache_alloc_node(cachep, flags, nid_alloc);
+	return NULL;
+}
+
+/*
+ * Fallback function if there was no memory available and no objects on a
+ * certain node and fall back is permitted. First we scan all the
+ * available node for available objects. If that fails then we
+ * perform an allocation without specifying a node. This allows the page
+ * allocator to do its reclaim / fallback magic. We then insert the
+ * slab into the proper nodelist and then allocate from it.
+ */
+static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
+{
+	struct zonelist *zonelist;
+	gfp_t local_flags;
+	struct zoneref *z;
+	struct zone *zone;
+	enum zone_type high_zoneidx = gfp_zone(flags);
+	void *obj = NULL;
+	int nid;
+	unsigned int cpuset_mems_cookie;
+
+	if (flags & __GFP_THISNODE)
+		return NULL;
+
+	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
+
+retry_cpuset:
+	cpuset_mems_cookie = read_mems_allowed_begin();
+	zonelist = node_zonelist(mempolicy_slab_node(), flags);
+
+retry:
+	/*
+	 * Look through allowed nodes for objects available
+	 * from existing per node queues.
+	 */
+	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
+		nid = zone_to_nid(zone);
+
+		if (cpuset_zone_allowed(zone, flags) &&
+			get_node(cache, nid) &&
+			get_node(cache, nid)->free_objects) {
+				obj = ____cache_alloc_node(cache,
+					gfp_exact_node(flags), nid);
+				if (obj)
+					break;
+		}
+	}
+
+	if (!obj) {
+		/*
+		 * This allocation will be performed within the constraints
+		 * of the current cpuset / memory policy requirements.
+		 * We may trigger various forms of reclaim on the allowed
+		 * set and go into memory reserves if necessary.
+		 */
+		struct page *page;
+
+		if (gfpflags_allow_blocking(local_flags))
+			local_irq_enable();
+		kmem_flagcheck(cache, flags);
+		page = kmem_getpages(cache, local_flags, numa_mem_id());
+		if (gfpflags_allow_blocking(local_flags))
+			local_irq_disable();
+		if (page) {
+			/*
+			 * Insert into the appropriate per node queues
+			 */
+			nid = page_to_nid(page);
+			if (cache_grow(cache, flags, nid, page)) {
+				obj = ____cache_alloc_node(cache,
+					gfp_exact_node(flags), nid);
+				if (!obj)
+					/*
+					 * Another processor may allocate the
+					 * objects in the slab since we are
+					 * not holding any locks.
+					 */
+					goto retry;
+			} else {
+				/* cache_grow already freed obj */
+				obj = NULL;
+			}
+		}
+	}
+
+	if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie)))
+		goto retry_cpuset;
+	return obj;
+}
+
+/*
+ * A interface to enable slab creation on nodeid
+ */
+static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
+				int nodeid)
+{
+	struct list_head *entry;
+	struct page *page;
+	struct kmem_cache_node *n;
+	void *obj;
+	int x;
+
+	VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
+	n = get_node(cachep, nodeid);
+	BUG_ON(!n);
+
+retry:
+	check_irq_off();
+	spin_lock(&n->list_lock);
+	entry = n->slabs_partial.next;
+	if (entry == &n->slabs_partial) {
+		n->free_touched = 1;
+		entry = n->slabs_free.next;
+		if (entry == &n->slabs_free)
+			goto must_grow;
+	}
+
+	page = list_entry(entry, struct page, lru);
+	check_spinlock_acquired_node(cachep, nodeid);
+
+	STATS_INC_NODEALLOCS(cachep);
+	STATS_INC_ACTIVE(cachep);
+	STATS_SET_HIGH(cachep);
+
+	BUG_ON(page->active == cachep->num);
+
+	obj = slab_get_obj(cachep, page, nodeid);
+	n->free_objects--;
+	/* move slabp to correct slabp list: */
+	list_del(&page->lru);
+
+	if (page->active == cachep->num)
+		list_add(&page->lru, &n->slabs_full);
+	else
+		list_add(&page->lru, &n->slabs_partial);
+
+	spin_unlock(&n->list_lock);
+	goto done;
+
+must_grow:
+	spin_unlock(&n->list_lock);
+	x = cache_grow(cachep, gfp_exact_node(flags), nodeid, NULL);
+	if (x)
+		goto retry;
+
+	return fallback_alloc(cachep, flags);
+
+done:
+	return obj;
+}
+
+static __always_inline void *
+slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
+		   unsigned long caller)
+{
+	unsigned long save_flags;
+	void *ptr;
+	int slab_node = numa_mem_id();
+
+	flags &= gfp_allowed_mask;
+
+	lockdep_trace_alloc(flags);
+
+	if (slab_should_failslab(cachep, flags))
+		return NULL;
+
+	cachep = memcg_kmem_get_cache(cachep, flags);
+
+	cache_alloc_debugcheck_before(cachep, flags);
+	local_irq_save(save_flags);
+
+	if (nodeid == NUMA_NO_NODE)
+		nodeid = slab_node;
+
+	if (unlikely(!get_node(cachep, nodeid))) {
+		/* Node not bootstrapped yet */
+		ptr = fallback_alloc(cachep, flags);
+		goto out;
+	}
+
+	if (nodeid == slab_node) {
+		/*
+		 * Use the locally cached objects if possible.
+		 * However ____cache_alloc does not allow fallback
+		 * to other nodes. It may fail while we still have
+		 * objects on other nodes available.
+		 */
+		ptr = ____cache_alloc(cachep, flags);
+		if (ptr)
+			goto out;
+	}
+	/* ___cache_alloc_node can fall back to other nodes */
+	ptr = ____cache_alloc_node(cachep, flags, nodeid);
+  out:
+	local_irq_restore(save_flags);
+	ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
+	kmemleak_alloc_recursive(ptr, cachep->object_size, 1, cachep->flags,
+				 flags);
+
+	if (likely(ptr)) {
+		kmemcheck_slab_alloc(cachep, flags, ptr, cachep->object_size);
+		if (unlikely(flags & __GFP_ZERO))
+			memset(ptr, 0, cachep->object_size);
+	}
+
+	memcg_kmem_put_cache(cachep);
+	return ptr;
+}
+
+static __always_inline void *
+__do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
+{
+	void *objp;
+
+	if (current->mempolicy || cpuset_do_slab_mem_spread()) {
+		objp = alternate_node_alloc(cache, flags);
+		if (objp)
+			goto out;
+	}
+	objp = ____cache_alloc(cache, flags);
+
+	/*
+	 * We may just have run out of memory on the local node.
+	 * ____cache_alloc_node() knows how to locate memory on other nodes
+	 */
+	if (!objp)
+		objp = ____cache_alloc_node(cache, flags, numa_mem_id());
+
+  out:
+	return objp;
+}
+#else
+
+static __always_inline void *
+__do_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+	return ____cache_alloc(cachep, flags);
+}
+
+#endif /* CONFIG_NUMA */
+
+static __always_inline void *
+slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
+{
+	unsigned long save_flags;
+	void *objp;
+
+	flags &= gfp_allowed_mask;
+
+	lockdep_trace_alloc(flags);
+
+	if (slab_should_failslab(cachep, flags))
+		return NULL;
+
+	cachep = memcg_kmem_get_cache(cachep, flags);
+
+	cache_alloc_debugcheck_before(cachep, flags);
+	local_irq_save(save_flags);
+	objp = __do_cache_alloc(cachep, flags);
+	local_irq_restore(save_flags);
+	objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
+	kmemleak_alloc_recursive(objp, cachep->object_size, 1, cachep->flags,
+				 flags);
+	prefetchw(objp);
+
+	if (likely(objp)) {
+		kmemcheck_slab_alloc(cachep, flags, objp, cachep->object_size);
+		if (unlikely(flags & __GFP_ZERO))
+			memset(objp, 0, cachep->object_size);
+	}
+
+	memcg_kmem_put_cache(cachep);
+	return objp;
+}
+
+/*
+ * Caller needs to acquire correct kmem_cache_node's list_lock
+ * @list: List of detached free slabs should be freed by caller
+ */
+static void free_block(struct kmem_cache *cachep, void **objpp,
+			int nr_objects, int node, struct list_head *list)
+{
+	int i;
+	struct kmem_cache_node *n = get_node(cachep, node);
+
+	for (i = 0; i < nr_objects; i++) {
+		void *objp;
+		struct page *page;
+
+		clear_obj_pfmemalloc(&objpp[i]);
+		objp = objpp[i];
+
+		page = virt_to_head_page(objp);
+		list_del(&page->lru);
+		check_spinlock_acquired_node(cachep, node);
+		slab_put_obj(cachep, page, objp, node);
+		STATS_DEC_ACTIVE(cachep);
+		n->free_objects++;
+
+		/* fixup slab chains */
+		if (page->active == 0) {
+			if (n->free_objects > n->free_limit) {
+				n->free_objects -= cachep->num;
+				list_add_tail(&page->lru, list);
+			} else {
+				list_add(&page->lru, &n->slabs_free);
+			}
+		} else {
+			/* Unconditionally move a slab to the end of the
+			 * partial list on free - maximum time for the
+			 * other objects to be freed, too.
+			 */
+			list_add_tail(&page->lru, &n->slabs_partial);
+		}
+	}
+}
+
+static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
+{
+	int batchcount;
+	struct kmem_cache_node *n;
+	int node = numa_mem_id();
+	LIST_HEAD(list);
+
+	batchcount = ac->batchcount;
+#if DEBUG
+	BUG_ON(!batchcount || batchcount > ac->avail);
+#endif
+	check_irq_off();
+	n = get_node(cachep, node);
+	spin_lock(&n->list_lock);
+	if (n->shared) {
+		struct array_cache *shared_array = n->shared;
+		int max = shared_array->limit - shared_array->avail;
+		if (max) {
+			if (batchcount > max)
+				batchcount = max;
+			memcpy(&(shared_array->entry[shared_array->avail]),
+			       ac->entry, sizeof(void *) * batchcount);
+			shared_array->avail += batchcount;
+			goto free_done;
+		}
+	}
+
+	free_block(cachep, ac->entry, batchcount, node, &list);
+free_done:
+#if STATS
+	{
+		int i = 0;
+		struct list_head *p;
+
+		p = n->slabs_free.next;
+		while (p != &(n->slabs_free)) {
+			struct page *page;
+
+			page = list_entry(p, struct page, lru);
+			BUG_ON(page->active);
+
+			i++;
+			p = p->next;
+		}
+		STATS_SET_FREEABLE(cachep, i);
+	}
+#endif
+	spin_unlock(&n->list_lock);
+	slabs_destroy(cachep, &list);
+	ac->avail -= batchcount;
+	memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
+}
+
+/*
+ * Release an obj back to its cache. If the obj has a constructed state, it must
+ * be in this state _before_ it is released.  Called with disabled ints.
+ */
+static inline void __cache_free(struct kmem_cache *cachep, void *objp,
+				unsigned long caller)
+{
+	struct array_cache *ac = cpu_cache_get(cachep);
+
+	check_irq_off();
+	kmemleak_free_recursive(objp, cachep->flags);
+	objp = cache_free_debugcheck(cachep, objp, caller);
+
+	kmemcheck_slab_free(cachep, objp, cachep->object_size);
+
+	/*
+	 * Skip calling cache_free_alien() when the platform is not numa.
+	 * This will avoid cache misses that happen while accessing slabp (which
+	 * is per page memory  reference) to get nodeid. Instead use a global
+	 * variable to skip the call, which is mostly likely to be present in
+	 * the cache.
+	 */
+	if (nr_online_nodes > 1 && cache_free_alien(cachep, objp))
+		return;
+
+	if (ac->avail < ac->limit) {
+		STATS_INC_FREEHIT(cachep);
+	} else {
+		STATS_INC_FREEMISS(cachep);
+		cache_flusharray(cachep, ac);
+	}
+
+	ac_put_obj(cachep, ac, objp);
+}
+
+/**
+ * kmem_cache_alloc - Allocate an object
+ * @cachep: The cache to allocate from.
+ * @flags: See kmalloc().
+ *
+ * Allocate an object from this cache.  The flags are only relevant
+ * if the cache has no available objects.
+ */
+void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+	void *ret = slab_alloc(cachep, flags, _RET_IP_);
+
+	trace_kmem_cache_alloc(_RET_IP_, ret,
+			       cachep->object_size, cachep->size, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc);
+
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
+{
+	__kmem_cache_free_bulk(s, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_free_bulk);
+
+int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
+								void **p)
+{
+	return __kmem_cache_alloc_bulk(s, flags, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_bulk);
+
+#ifdef CONFIG_TRACING
+void *
+kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size)
+{
+	void *ret;
+
+	ret = slab_alloc(cachep, flags, _RET_IP_);
+
+	trace_kmalloc(_RET_IP_, ret,
+		      size, cachep->size, flags);
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_trace);
+#endif
+
+#ifdef CONFIG_NUMA
+/**
+ * kmem_cache_alloc_node - Allocate an object on the specified node
+ * @cachep: The cache to allocate from.
+ * @flags: See kmalloc().
+ * @nodeid: node number of the target node.
+ *
+ * Identical to kmem_cache_alloc but it will allocate memory on the given
+ * node, which can improve the performance for cpu bound structures.
+ *
+ * Fallback to other node is possible if __GFP_THISNODE is not set.
+ */
+void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
+{
+	void *ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
+
+	trace_kmem_cache_alloc_node(_RET_IP_, ret,
+				    cachep->object_size, cachep->size,
+				    flags, nodeid);
+
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_node);
+
+#ifdef CONFIG_TRACING
+void *kmem_cache_alloc_node_trace(struct kmem_cache *cachep,
+				  gfp_t flags,
+				  int nodeid,
+				  size_t size)
+{
+	void *ret;
+
+	ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
+
+	trace_kmalloc_node(_RET_IP_, ret,
+			   size, cachep->size,
+			   flags, nodeid);
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
+#endif
+
+static __always_inline void *
+__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
+{
+	struct kmem_cache *cachep;
+
+	cachep = kmalloc_slab(size, flags);
+	if (unlikely(ZERO_OR_NULL_PTR(cachep)))
+		return cachep;
+	return kmem_cache_alloc_node_trace(cachep, flags, node, size);
+}
+
+void *__kmalloc_node(size_t size, gfp_t flags, int node)
+{
+	return __do_kmalloc_node(size, flags, node, _RET_IP_);
+}
+EXPORT_SYMBOL(__kmalloc_node);
+
+void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
+		int node, unsigned long caller)
+{
+	return __do_kmalloc_node(size, flags, node, caller);
+}
+EXPORT_SYMBOL(__kmalloc_node_track_caller);
+#endif /* CONFIG_NUMA */
+
+/**
+ * __do_kmalloc - allocate memory
+ * @size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate (see kmalloc).
+ * @caller: function caller for debug tracking of the caller
+ */
+static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
+					  unsigned long caller)
+{
+	struct kmem_cache *cachep;
+	void *ret;
+
+	cachep = kmalloc_slab(size, flags);
+	if (unlikely(ZERO_OR_NULL_PTR(cachep)))
+		return cachep;
+	ret = slab_alloc(cachep, flags, caller);
+
+	trace_kmalloc(caller, ret,
+		      size, cachep->size, flags);
+
+	return ret;
+}
+
+void *__kmalloc(size_t size, gfp_t flags)
+{
+	return __do_kmalloc(size, flags, _RET_IP_);
+}
+EXPORT_SYMBOL(__kmalloc);
+
+void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller)
+{
+	return __do_kmalloc(size, flags, caller);
+}
+EXPORT_SYMBOL(__kmalloc_track_caller);
+
+/**
+ * kmem_cache_free - Deallocate an object
+ * @cachep: The cache the allocation was from.
+ * @objp: The previously allocated object.
+ *
+ * Free an object which was previously allocated from this
+ * cache.
+ */
+void kmem_cache_free(struct kmem_cache *cachep, void *objp)
+{
+	unsigned long flags;
+	cachep = cache_from_obj(cachep, objp);
+	if (!cachep)
+		return;
+
+	local_irq_save(flags);
+	debug_check_no_locks_freed(objp, cachep->object_size);
+	if (!(cachep->flags & SLAB_DEBUG_OBJECTS))
+		debug_check_no_obj_freed(objp, cachep->object_size);
+	__cache_free(cachep, objp, _RET_IP_);
+	local_irq_restore(flags);
+
+	trace_kmem_cache_free(_RET_IP_, objp);
+}
+EXPORT_SYMBOL(kmem_cache_free);
+
+/**
+ * kfree - free previously allocated memory
+ * @objp: pointer returned by kmalloc.
+ *
+ * If @objp is NULL, no operation is performed.
+ *
+ * Don't free memory not originally allocated by kmalloc()
+ * or you will run into trouble.
+ */
+void kfree(const void *objp)
+{
+	struct kmem_cache *c;
+	unsigned long flags;
+
+	trace_kfree(_RET_IP_, objp);
+
+	if (unlikely(ZERO_OR_NULL_PTR(objp)))
+		return;
+	local_irq_save(flags);
+	kfree_debugcheck(objp);
+	c = virt_to_cache(objp);
+	debug_check_no_locks_freed(objp, c->object_size);
+
+	debug_check_no_obj_freed(objp, c->object_size);
+	__cache_free(c, (void *)objp, _RET_IP_);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(kfree);
+
+/*
+ * This initializes kmem_cache_node or resizes various caches for all nodes.
+ */
+static int alloc_kmem_cache_node(struct kmem_cache *cachep, gfp_t gfp)
+{
+	int node;
+	struct kmem_cache_node *n;
+	struct array_cache *new_shared;
+	struct alien_cache **new_alien = NULL;
+
+	for_each_online_node(node) {
+
+		if (use_alien_caches) {
+			new_alien = alloc_alien_cache(node, cachep->limit, gfp);
+			if (!new_alien)
+				goto fail;
+		}
+
+		new_shared = NULL;
+		if (cachep->shared) {
+			new_shared = alloc_arraycache(node,
+				cachep->shared*cachep->batchcount,
+					0xbaadf00d, gfp);
+			if (!new_shared) {
+				free_alien_cache(new_alien);
+				goto fail;
+			}
+		}
+
+		n = get_node(cachep, node);
+		if (n) {
+			struct array_cache *shared = n->shared;
+			LIST_HEAD(list);
+
+			spin_lock_irq(&n->list_lock);
+
+			if (shared)
+				free_block(cachep, shared->entry,
+						shared->avail, node, &list);
+
+			n->shared = new_shared;
+			if (!n->alien) {
+				n->alien = new_alien;
+				new_alien = NULL;
+			}
+			n->free_limit = (1 + nr_cpus_node(node)) *
+					cachep->batchcount + cachep->num;
+			spin_unlock_irq(&n->list_lock);
+			slabs_destroy(cachep, &list);
+			kfree(shared);
+			free_alien_cache(new_alien);
+			continue;
+		}
+		n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
+		if (!n) {
+			free_alien_cache(new_alien);
+			kfree(new_shared);
+			goto fail;
+		}
+
+		kmem_cache_node_init(n);
+		n->next_reap = jiffies + REAPTIMEOUT_NODE +
+				((unsigned long)cachep) % REAPTIMEOUT_NODE;
+		n->shared = new_shared;
+		n->alien = new_alien;
+		n->free_limit = (1 + nr_cpus_node(node)) *
+					cachep->batchcount + cachep->num;
+		cachep->node[node] = n;
+	}
+	return 0;
+
+fail:
+	if (!cachep->list.next) {
+		/* Cache is not active yet. Roll back what we did */
+		node--;
+		while (node >= 0) {
+			n = get_node(cachep, node);
+			if (n) {
+				kfree(n->shared);
+				free_alien_cache(n->alien);
+				kfree(n);
+				cachep->node[node] = NULL;
+			}
+			node--;
+		}
+	}
+	return -ENOMEM;
+}
+
+/* Always called with the slab_mutex held */
+static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
+				int batchcount, int shared, gfp_t gfp)
+{
+	struct array_cache __percpu *cpu_cache, *prev;
+	int cpu;
+
+	cpu_cache = alloc_kmem_cache_cpus(cachep, limit, batchcount);
+	if (!cpu_cache)
+		return -ENOMEM;
+
+	prev = cachep->cpu_cache;
+	cachep->cpu_cache = cpu_cache;
+	kick_all_cpus_sync();
+
+	check_irq_on();
+	cachep->batchcount = batchcount;
+	cachep->limit = limit;
+	cachep->shared = shared;
+
+	if (!prev)
+		goto alloc_node;
+
+	for_each_online_cpu(cpu) {
+		LIST_HEAD(list);
+		int node;
+		struct kmem_cache_node *n;
+		struct array_cache *ac = per_cpu_ptr(prev, cpu);
+
+		node = cpu_to_mem(cpu);
+		n = get_node(cachep, node);
+		spin_lock_irq(&n->list_lock);
+		free_block(cachep, ac->entry, ac->avail, node, &list);
+		spin_unlock_irq(&n->list_lock);
+		slabs_destroy(cachep, &list);
+	}
+	free_percpu(prev);
+
+alloc_node:
+	return alloc_kmem_cache_node(cachep, gfp);
+}
+
+static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
+				int batchcount, int shared, gfp_t gfp)
+{
+	int ret;
+	struct kmem_cache *c;
+
+	ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
+
+	if (slab_state < FULL)
+		return ret;
+
+	if ((ret < 0) || !is_root_cache(cachep))
+		return ret;
+
+	lockdep_assert_held(&slab_mutex);
+	for_each_memcg_cache(c, cachep) {
+		/* return value determined by the root cache only */
+		__do_tune_cpucache(c, limit, batchcount, shared, gfp);
+	}
+
+	return ret;
+}
+
+/* Called with slab_mutex held always */
+static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
+{
+	int err;
+	int limit = 0;
+	int shared = 0;
+	int batchcount = 0;
+
+	if (!is_root_cache(cachep)) {
+		struct kmem_cache *root = memcg_root_cache(cachep);
+		limit = root->limit;
+		shared = root->shared;
+		batchcount = root->batchcount;
+	}
+
+	if (limit && shared && batchcount)
+		goto skip_setup;
+	/*
+	 * The head array serves three purposes:
+	 * - create a LIFO ordering, i.e. return objects that are cache-warm
+	 * - reduce the number of spinlock operations.
+	 * - reduce the number of linked list operations on the slab and
+	 *   bufctl chains: array operations are cheaper.
+	 * The numbers are guessed, we should auto-tune as described by
+	 * Bonwick.
+	 */
+	if (cachep->size > 131072)
+		limit = 1;
+	else if (cachep->size > PAGE_SIZE)
+		limit = 8;
+	else if (cachep->size > 1024)
+		limit = 24;
+	else if (cachep->size > 256)
+		limit = 54;
+	else
+		limit = 120;
+
+	/*
+	 * CPU bound tasks (e.g. network routing) can exhibit cpu bound
+	 * allocation behaviour: Most allocs on one cpu, most free operations
+	 * on another cpu. For these cases, an efficient object passing between
+	 * cpus is necessary. This is provided by a shared array. The array
+	 * replaces Bonwick's magazine layer.
+	 * On uniprocessor, it's functionally equivalent (but less efficient)
+	 * to a larger limit. Thus disabled by default.
+	 */
+	shared = 0;
+	if (cachep->size <= PAGE_SIZE && num_possible_cpus() > 1)
+		shared = 8;
+
+#if DEBUG
+	/*
+	 * With debugging enabled, large batchcount lead to excessively long
+	 * periods with disabled local interrupts. Limit the batchcount
+	 */
+	if (limit > 32)
+		limit = 32;
+#endif
+	batchcount = (limit + 1) / 2;
+skip_setup:
+	err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
+	if (err)
+		printk(KERN_ERR "enable_cpucache failed for %s, error %d.\n",
+		       cachep->name, -err);
+	return err;
+}
+
+/*
+ * Drain an array if it contains any elements taking the node lock only if
+ * necessary. Note that the node listlock also protects the array_cache
+ * if drain_array() is used on the shared array.
+ */
+static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n,
+			 struct array_cache *ac, int force, int node)
+{
+	LIST_HEAD(list);
+	int tofree;
+
+	if (!ac || !ac->avail)
+		return;
+	if (ac->touched && !force) {
+		ac->touched = 0;
+	} else {
+		spin_lock_irq(&n->list_lock);
+		if (ac->avail) {
+			tofree = force ? ac->avail : (ac->limit + 4) / 5;
+			if (tofree > ac->avail)
+				tofree = (ac->avail + 1) / 2;
+			free_block(cachep, ac->entry, tofree, node, &list);
+			ac->avail -= tofree;
+			memmove(ac->entry, &(ac->entry[tofree]),
+				sizeof(void *) * ac->avail);
+		}
+		spin_unlock_irq(&n->list_lock);
+		slabs_destroy(cachep, &list);
+	}
+}
+
+/**
+ * cache_reap - Reclaim memory from caches.
+ * @w: work descriptor
+ *
+ * Called from workqueue/eventd every few seconds.
+ * Purpose:
+ * - clear the per-cpu caches for this CPU.
+ * - return freeable pages to the main free memory pool.
+ *
+ * If we cannot acquire the cache chain mutex then just give up - we'll try
+ * again on the next iteration.
+ */
+static void cache_reap(struct work_struct *w)
+{
+	struct kmem_cache *searchp;
+	struct kmem_cache_node *n;
+	int node = numa_mem_id();
+	struct delayed_work *work = to_delayed_work(w);
+
+	if (!mutex_trylock(&slab_mutex))
+		/* Give up. Setup the next iteration. */
+		goto out;
+
+	list_for_each_entry(searchp, &slab_caches, list) {
+		check_irq_on();
+
+		/*
+		 * We only take the node lock if absolutely necessary and we
+		 * have established with reasonable certainty that
+		 * we can do some work if the lock was obtained.
+		 */
+		n = get_node(searchp, node);
+
+		reap_alien(searchp, n);
+
+		drain_array(searchp, n, cpu_cache_get(searchp), 0, node);
+
+		/*
+		 * These are racy checks but it does not matter
+		 * if we skip one check or scan twice.
+		 */
+		if (time_after(n->next_reap, jiffies))
+			goto next;
+
+		n->next_reap = jiffies + REAPTIMEOUT_NODE;
+
+		drain_array(searchp, n, n->shared, 0, node);
+
+		if (n->free_touched)
+			n->free_touched = 0;
+		else {
+			int freed;
+
+			freed = drain_freelist(searchp, n, (n->free_limit +
+				5 * searchp->num - 1) / (5 * searchp->num));
+			STATS_ADD_REAPED(searchp, freed);
+		}
+next:
+		cond_resched();
+	}
+	check_irq_on();
+	mutex_unlock(&slab_mutex);
+	next_reap_node();
+out:
+	/* Set up the next iteration */
+	schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC));
+}
+
+#ifdef CONFIG_SLABINFO
+void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
+{
+	struct page *page;
+	unsigned long active_objs;
+	unsigned long num_objs;
+	unsigned long active_slabs = 0;
+	unsigned long num_slabs, free_objects = 0, shared_avail = 0;
+	const char *name;
+	char *error = NULL;
+	int node;
+	struct kmem_cache_node *n;
+
+	active_objs = 0;
+	num_slabs = 0;
+	for_each_kmem_cache_node(cachep, node, n) {
+
+		check_irq_on();
+		spin_lock_irq(&n->list_lock);
+
+		list_for_each_entry(page, &n->slabs_full, lru) {
+			if (page->active != cachep->num && !error)
+				error = "slabs_full accounting error";
+			active_objs += cachep->num;
+			active_slabs++;
+		}
+		list_for_each_entry(page, &n->slabs_partial, lru) {
+			if (page->active == cachep->num && !error)
+				error = "slabs_partial accounting error";
+			if (!page->active && !error)
+				error = "slabs_partial accounting error";
+			active_objs += page->active;
+			active_slabs++;
+		}
+		list_for_each_entry(page, &n->slabs_free, lru) {
+			if (page->active && !error)
+				error = "slabs_free accounting error";
+			num_slabs++;
+		}
+		free_objects += n->free_objects;
+		if (n->shared)
+			shared_avail += n->shared->avail;
+
+		spin_unlock_irq(&n->list_lock);
+	}
+	num_slabs += active_slabs;
+	num_objs = num_slabs * cachep->num;
+	if (num_objs - active_objs != free_objects && !error)
+		error = "free_objects accounting error";
+
+	name = cachep->name;
+	if (error)
+		printk(KERN_ERR "slab: cache %s error: %s\n", name, error);
+
+	sinfo->active_objs = active_objs;
+	sinfo->num_objs = num_objs;
+	sinfo->active_slabs = active_slabs;
+	sinfo->num_slabs = num_slabs;
+	sinfo->shared_avail = shared_avail;
+	sinfo->limit = cachep->limit;
+	sinfo->batchcount = cachep->batchcount;
+	sinfo->shared = cachep->shared;
+	sinfo->objects_per_slab = cachep->num;
+	sinfo->cache_order = cachep->gfporder;
+}
+
+void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep)
+{
+#if STATS
+	{			/* node stats */
+		unsigned long high = cachep->high_mark;
+		unsigned long allocs = cachep->num_allocations;
+		unsigned long grown = cachep->grown;
+		unsigned long reaped = cachep->reaped;
+		unsigned long errors = cachep->errors;
+		unsigned long max_freeable = cachep->max_freeable;
+		unsigned long node_allocs = cachep->node_allocs;
+		unsigned long node_frees = cachep->node_frees;
+		unsigned long overflows = cachep->node_overflow;
+
+		seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu "
+			   "%4lu %4lu %4lu %4lu %4lu",
+			   allocs, high, grown,
+			   reaped, errors, max_freeable, node_allocs,
+			   node_frees, overflows);
+	}
+	/* cpu stats */
+	{
+		unsigned long allochit = atomic_read(&cachep->allochit);
+		unsigned long allocmiss = atomic_read(&cachep->allocmiss);
+		unsigned long freehit = atomic_read(&cachep->freehit);
+		unsigned long freemiss = atomic_read(&cachep->freemiss);
+
+		seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
+			   allochit, allocmiss, freehit, freemiss);
+	}
+#endif
+}
+
+#define MAX_SLABINFO_WRITE 128
+/**
+ * slabinfo_write - Tuning for the slab allocator
+ * @file: unused
+ * @buffer: user buffer
+ * @count: data length
+ * @ppos: unused
+ */
+ssize_t slabinfo_write(struct file *file, const char __user *buffer,
+		       size_t count, loff_t *ppos)
+{
+	char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
+	int limit, batchcount, shared, res;
+	struct kmem_cache *cachep;
+
+	if (count > MAX_SLABINFO_WRITE)
+		return -EINVAL;
+	if (copy_from_user(&kbuf, buffer, count))
+		return -EFAULT;
+	kbuf[MAX_SLABINFO_WRITE] = '\0';
+
+	tmp = strchr(kbuf, ' ');
+	if (!tmp)
+		return -EINVAL;
+	*tmp = '\0';
+	tmp++;
+	if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3)
+		return -EINVAL;
+
+	/* Find the cache in the chain of caches. */
+	mutex_lock(&slab_mutex);
+	res = -EINVAL;
+	list_for_each_entry(cachep, &slab_caches, list) {
+		if (!strcmp(cachep->name, kbuf)) {
+			if (limit < 1 || batchcount < 1 ||
+					batchcount > limit || shared < 0) {
+				res = 0;
+			} else {
+				res = do_tune_cpucache(cachep, limit,
+						       batchcount, shared,
+						       GFP_KERNEL);
+			}
+			break;
+		}
+	}
+	mutex_unlock(&slab_mutex);
+	if (res >= 0)
+		res = count;
+	return res;
+}
+
+#ifdef CONFIG_DEBUG_SLAB_LEAK
+
+static inline int add_caller(unsigned long *n, unsigned long v)
+{
+	unsigned long *p;
+	int l;
+	if (!v)
+		return 1;
+	l = n[1];
+	p = n + 2;
+	while (l) {
+		int i = l/2;
+		unsigned long *q = p + 2 * i;
+		if (*q == v) {
+			q[1]++;
+			return 1;
+		}
+		if (*q > v) {
+			l = i;
+		} else {
+			p = q + 2;
+			l -= i + 1;
+		}
+	}
+	if (++n[1] == n[0])
+		return 0;
+	memmove(p + 2, p, n[1] * 2 * sizeof(unsigned long) - ((void *)p - (void *)n));
+	p[0] = v;
+	p[1] = 1;
+	return 1;
+}
+
+static void handle_slab(unsigned long *n, struct kmem_cache *c,
+						struct page *page)
+{
+	void *p;
+	int i;
+
+	if (n[0] == n[1])
+		return;
+	for (i = 0, p = page->s_mem; i < c->num; i++, p += c->size) {
+		if (get_obj_status(page, i) != OBJECT_ACTIVE)
+			continue;
+
+		if (!add_caller(n, (unsigned long)*dbg_userword(c, p)))
+			return;
+	}
+}
+
+static void show_symbol(struct seq_file *m, unsigned long address)
+{
+#ifdef CONFIG_KALLSYMS
+	unsigned long offset, size;
+	char modname[MODULE_NAME_LEN], name[KSYM_NAME_LEN];
+
+	if (lookup_symbol_attrs(address, &size, &offset, modname, name) == 0) {
+		seq_printf(m, "%s+%#lx/%#lx", name, offset, size);
+		if (modname[0])
+			seq_printf(m, " [%s]", modname);
+		return;
+	}
+#endif
+	seq_printf(m, "%p", (void *)address);
+}
+
+static int leaks_show(struct seq_file *m, void *p)
+{
+	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
+	struct page *page;
+	struct kmem_cache_node *n;
+	const char *name;
+	unsigned long *x = m->private;
+	int node;
+	int i;
+
+	if (!(cachep->flags & SLAB_STORE_USER))
+		return 0;
+	if (!(cachep->flags & SLAB_RED_ZONE))
+		return 0;
+
+	/* OK, we can do it */
+
+	x[1] = 0;
+
+	for_each_kmem_cache_node(cachep, node, n) {
+
+		check_irq_on();
+		spin_lock_irq(&n->list_lock);
+
+		list_for_each_entry(page, &n->slabs_full, lru)
+			handle_slab(x, cachep, page);
+		list_for_each_entry(page, &n->slabs_partial, lru)
+			handle_slab(x, cachep, page);
+		spin_unlock_irq(&n->list_lock);
+	}
+	name = cachep->name;
+	if (x[0] == x[1]) {
+		/* Increase the buffer size */
+		mutex_unlock(&slab_mutex);
+		m->private = kzalloc(x[0] * 4 * sizeof(unsigned long), GFP_KERNEL);
+		if (!m->private) {
+			/* Too bad, we are really out */
+			m->private = x;
+			mutex_lock(&slab_mutex);
+			return -ENOMEM;
+		}
+		*(unsigned long *)m->private = x[0] * 2;
+		kfree(x);
+		mutex_lock(&slab_mutex);
+		/* Now make sure this entry will be retried */
+		m->count = m->size;
+		return 0;
+	}
+	for (i = 0; i < x[1]; i++) {
+		seq_printf(m, "%s: %lu ", name, x[2*i+3]);
+		show_symbol(m, x[2*i+2]);
+		seq_putc(m, '\n');
+	}
+
+	return 0;
+}
+
+static const struct seq_operations slabstats_op = {
+	.start = slab_start,
+	.next = slab_next,
+	.stop = slab_stop,
+	.show = leaks_show,
+};
+
+static int slabstats_open(struct inode *inode, struct file *file)
+{
+	unsigned long *n;
+
+	n = __seq_open_private(file, &slabstats_op, PAGE_SIZE);
+	if (!n)
+		return -ENOMEM;
+
+	*n = PAGE_SIZE / (2 * sizeof(unsigned long));
+
+	return 0;
+}
+
+static const struct file_operations proc_slabstats_operations = {
+	.open		= slabstats_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release_private,
+};
+#endif
+
+static int __init slab_proc_init(void)
+{
+#ifdef CONFIG_DEBUG_SLAB_LEAK
+	proc_create("slab_allocators", 0, NULL, &proc_slabstats_operations);
+#endif
+	return 0;
+}
+module_init(slab_proc_init);
+#endif
+
+/**
+ * ksize - get the actual amount of memory allocated for a given object
+ * @objp: Pointer to the object
+ *
+ * kmalloc may internally round up allocations and return more memory
+ * than requested. ksize() can be used to determine the actual amount of
+ * memory allocated. The caller may use this additional memory, even though
+ * a smaller amount of memory was initially specified with the kmalloc call.
+ * The caller must guarantee that objp points to a valid object previously
+ * allocated with either kmalloc() or kmem_cache_alloc(). The object
+ * must not be freed during the duration of the call.
+ */
+size_t ksize(const void *objp)
+{
+	BUG_ON(!objp);
+	if (unlikely(objp == ZERO_SIZE_PTR))
+		return 0;
+
+	return virt_to_cache(objp)->object_size;
+}
+EXPORT_SYMBOL(ksize);
diff --git a/mm/slab.h b/mm/slab.h
new file mode 100644
index 0000000..7b60871
--- /dev/null
+++ b/mm/slab.h
@@ -0,0 +1,374 @@
+#ifndef MM_SLAB_H
+#define MM_SLAB_H
+/*
+ * Internal slab definitions
+ */
+
+#ifdef CONFIG_SLOB
+/*
+ * Common fields provided in kmem_cache by all slab allocators
+ * This struct is either used directly by the allocator (SLOB)
+ * or the allocator must include definitions for all fields
+ * provided in kmem_cache_common in their definition of kmem_cache.
+ *
+ * Once we can do anonymous structs (C11 standard) we could put a
+ * anonymous struct definition in these allocators so that the
+ * separate allocations in the kmem_cache structure of SLAB and
+ * SLUB is no longer needed.
+ */
+struct kmem_cache {
+	unsigned int object_size;/* The original size of the object */
+	unsigned int size;	/* The aligned/padded/added on size  */
+	unsigned int align;	/* Alignment as calculated */
+	unsigned long flags;	/* Active flags on the slab */
+	const char *name;	/* Slab name for sysfs */
+	int refcount;		/* Use counter */
+	void (*ctor)(void *);	/* Called on object slot creation */
+	struct list_head list;	/* List of all slab caches on the system */
+};
+
+#endif /* CONFIG_SLOB */
+
+#ifdef CONFIG_SLAB
+#include <linux/slab_def.h>
+#endif
+
+#ifdef CONFIG_SLUB
+#include <linux/slub_def.h>
+#endif
+
+#include <linux/memcontrol.h>
+
+/*
+ * State of the slab allocator.
+ *
+ * This is used to describe the states of the allocator during bootup.
+ * Allocators use this to gradually bootstrap themselves. Most allocators
+ * have the problem that the structures used for managing slab caches are
+ * allocated from slab caches themselves.
+ */
+enum slab_state {
+	DOWN,			/* No slab functionality yet */
+	PARTIAL,		/* SLUB: kmem_cache_node available */
+	PARTIAL_NODE,		/* SLAB: kmalloc size for node struct available */
+	UP,			/* Slab caches usable but not all extras yet */
+	FULL			/* Everything is working */
+};
+
+extern enum slab_state slab_state;
+
+/* The slab cache mutex protects the management structures during changes */
+extern struct mutex slab_mutex;
+
+/* The list of all slab caches on the system */
+extern struct list_head slab_caches;
+
+/* The slab cache that manages slab cache information */
+extern struct kmem_cache *kmem_cache;
+
+unsigned long calculate_alignment(unsigned long flags,
+		unsigned long align, unsigned long size);
+
+#ifndef CONFIG_SLOB
+/* Kmalloc array related functions */
+void setup_kmalloc_cache_index_table(void);
+void create_kmalloc_caches(unsigned long);
+
+/* Find the kmalloc slab corresponding for a certain size */
+struct kmem_cache *kmalloc_slab(size_t, gfp_t);
+#endif
+
+
+/* Functions provided by the slab allocators */
+extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);
+
+extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
+			unsigned long flags);
+extern void create_boot_cache(struct kmem_cache *, const char *name,
+			size_t size, unsigned long flags);
+
+int slab_unmergeable(struct kmem_cache *s);
+struct kmem_cache *find_mergeable(size_t size, size_t align,
+		unsigned long flags, const char *name, void (*ctor)(void *));
+#ifndef CONFIG_SLOB
+struct kmem_cache *
+__kmem_cache_alias(const char *name, size_t size, size_t align,
+		   unsigned long flags, void (*ctor)(void *));
+
+unsigned long kmem_cache_flags(unsigned long object_size,
+	unsigned long flags, const char *name,
+	void (*ctor)(void *));
+#else
+static inline struct kmem_cache *
+__kmem_cache_alias(const char *name, size_t size, size_t align,
+		   unsigned long flags, void (*ctor)(void *))
+{ return NULL; }
+
+static inline unsigned long kmem_cache_flags(unsigned long object_size,
+	unsigned long flags, const char *name,
+	void (*ctor)(void *))
+{
+	return flags;
+}
+#endif
+
+
+/* Legal flag mask for kmem_cache_create(), for various configurations */
+#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
+			 SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS )
+
+#if defined(CONFIG_DEBUG_SLAB)
+#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
+#elif defined(CONFIG_SLUB_DEBUG)
+#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
+			  SLAB_TRACE | SLAB_DEBUG_FREE)
+#else
+#define SLAB_DEBUG_FLAGS (0)
+#endif
+
+#if defined(CONFIG_SLAB)
+#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
+			  SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | SLAB_NOTRACK)
+#elif defined(CONFIG_SLUB)
+#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
+			  SLAB_TEMPORARY | SLAB_NOTRACK)
+#else
+#define SLAB_CACHE_FLAGS (0)
+#endif
+
+#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
+
+int __kmem_cache_shutdown(struct kmem_cache *);
+int __kmem_cache_shrink(struct kmem_cache *, bool);
+void slab_kmem_cache_release(struct kmem_cache *);
+
+struct seq_file;
+struct file;
+
+struct slabinfo {
+	unsigned long active_objs;
+	unsigned long num_objs;
+	unsigned long active_slabs;
+	unsigned long num_slabs;
+	unsigned long shared_avail;
+	unsigned int limit;
+	unsigned int batchcount;
+	unsigned int shared;
+	unsigned int objects_per_slab;
+	unsigned int cache_order;
+};
+
+void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
+void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
+ssize_t slabinfo_write(struct file *file, const char __user *buffer,
+		       size_t count, loff_t *ppos);
+
+/*
+ * Generic implementation of bulk operations
+ * These are useful for situations in which the allocator cannot
+ * perform optimizations. In that case segments of the objecct listed
+ * may be allocated or freed using these operations.
+ */
+void __kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
+int __kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
+
+#ifdef CONFIG_MEMCG_KMEM
+/*
+ * Iterate over all memcg caches of the given root cache. The caller must hold
+ * slab_mutex.
+ */
+#define for_each_memcg_cache(iter, root) \
+	list_for_each_entry(iter, &(root)->memcg_params.list, \
+			    memcg_params.list)
+
+static inline bool is_root_cache(struct kmem_cache *s)
+{
+	return s->memcg_params.is_root_cache;
+}
+
+static inline bool slab_equal_or_root(struct kmem_cache *s,
+				      struct kmem_cache *p)
+{
+	return p == s || p == s->memcg_params.root_cache;
+}
+
+/*
+ * We use suffixes to the name in memcg because we can't have caches
+ * created in the system with the same name. But when we print them
+ * locally, better refer to them with the base name
+ */
+static inline const char *cache_name(struct kmem_cache *s)
+{
+	if (!is_root_cache(s))
+		s = s->memcg_params.root_cache;
+	return s->name;
+}
+
+/*
+ * Note, we protect with RCU only the memcg_caches array, not per-memcg caches.
+ * That said the caller must assure the memcg's cache won't go away by either
+ * taking a css reference to the owner cgroup, or holding the slab_mutex.
+ */
+static inline struct kmem_cache *
+cache_from_memcg_idx(struct kmem_cache *s, int idx)
+{
+	struct kmem_cache *cachep;
+	struct memcg_cache_array *arr;
+
+	rcu_read_lock();
+	arr = rcu_dereference(s->memcg_params.memcg_caches);
+
+	/*
+	 * Make sure we will access the up-to-date value. The code updating
+	 * memcg_caches issues a write barrier to match this (see
+	 * memcg_create_kmem_cache()).
+	 */
+	cachep = lockless_dereference(arr->entries[idx]);
+	rcu_read_unlock();
+
+	return cachep;
+}
+
+static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
+{
+	if (is_root_cache(s))
+		return s;
+	return s->memcg_params.root_cache;
+}
+
+static __always_inline int memcg_charge_slab(struct page *page,
+					     gfp_t gfp, int order,
+					     struct kmem_cache *s)
+{
+	if (!memcg_kmem_enabled())
+		return 0;
+	if (is_root_cache(s))
+		return 0;
+	return __memcg_kmem_charge_memcg(page, gfp, order,
+					 s->memcg_params.memcg);
+}
+
+extern void slab_init_memcg_params(struct kmem_cache *);
+
+#else /* !CONFIG_MEMCG_KMEM */
+
+#define for_each_memcg_cache(iter, root) \
+	for ((void)(iter), (void)(root); 0; )
+
+static inline bool is_root_cache(struct kmem_cache *s)
+{
+	return true;
+}
+
+static inline bool slab_equal_or_root(struct kmem_cache *s,
+				      struct kmem_cache *p)
+{
+	return true;
+}
+
+static inline const char *cache_name(struct kmem_cache *s)
+{
+	return s->name;
+}
+
+static inline struct kmem_cache *
+cache_from_memcg_idx(struct kmem_cache *s, int idx)
+{
+	return NULL;
+}
+
+static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
+{
+	return s;
+}
+
+static inline int memcg_charge_slab(struct page *page, gfp_t gfp, int order,
+				    struct kmem_cache *s)
+{
+	return 0;
+}
+
+static inline void slab_init_memcg_params(struct kmem_cache *s)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
+{
+	struct kmem_cache *cachep;
+	struct page *page;
+
+	/*
+	 * When kmemcg is not being used, both assignments should return the
+	 * same value. but we don't want to pay the assignment price in that
+	 * case. If it is not compiled in, the compiler should be smart enough
+	 * to not do even the assignment. In that case, slab_equal_or_root
+	 * will also be a constant.
+	 */
+	if (!memcg_kmem_enabled() && !unlikely(s->flags & SLAB_DEBUG_FREE))
+		return s;
+
+	page = virt_to_head_page(x);
+	cachep = page->slab_cache;
+	if (slab_equal_or_root(cachep, s))
+		return cachep;
+
+	pr_err("%s: Wrong slab cache. %s but object is from %s\n",
+	       __func__, s->name, cachep->name);
+	WARN_ON_ONCE(1);
+	return s;
+}
+
+#ifndef CONFIG_SLOB
+/*
+ * The slab lists for all objects.
+ */
+struct kmem_cache_node {
+	spinlock_t list_lock;
+
+#ifdef CONFIG_SLAB
+	struct list_head slabs_partial;	/* partial list first, better asm code */
+	struct list_head slabs_full;
+	struct list_head slabs_free;
+	unsigned long free_objects;
+	unsigned int free_limit;
+	unsigned int colour_next;	/* Per-node cache coloring */
+	struct array_cache *shared;	/* shared per node */
+	struct alien_cache **alien;	/* on other nodes */
+	unsigned long next_reap;	/* updated without locking */
+	int free_touched;		/* updated without locking */
+#endif
+
+#ifdef CONFIG_SLUB
+	unsigned long nr_partial;
+	struct list_head partial;
+#ifdef CONFIG_SLUB_DEBUG
+	atomic_long_t nr_slabs;
+	atomic_long_t total_objects;
+	struct list_head full;
+#endif
+#endif
+
+};
+
+static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
+{
+	return s->node[node];
+}
+
+/*
+ * Iterator over all nodes. The body will be executed for each node that has
+ * a kmem_cache_node structure allocated (which is true for all online nodes)
+ */
+#define for_each_kmem_cache_node(__s, __node, __n) \
+	for (__node = 0; __node < nr_node_ids; __node++) \
+		 if ((__n = get_node(__s, __node)))
+
+#endif
+
+void *slab_start(struct seq_file *m, loff_t *pos);
+void *slab_next(struct seq_file *m, void *p, loff_t *pos);
+void slab_stop(struct seq_file *m, void *p);
+int memcg_slab_show(struct seq_file *m, void *p);
+
+#endif /* MM_SLAB_H */
diff --git a/mm/slab_common.c b/mm/slab_common.c
new file mode 100644
index 0000000..01e7246
--- /dev/null
+++ b/mm/slab_common.c
@@ -0,0 +1,1283 @@
+/*
+ * Slab allocator functions that are independent of the allocator strategy
+ *
+ * (C) 2012 Christoph Lameter <cl@linux.com>
+ */
+#include <linux/slab.h>
+
+#include <linux/mm.h>
+#include <linux/poison.h>
+#include <linux/interrupt.h>
+#include <linux/memory.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/cpu.h>
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+#include <linux/memcontrol.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/kmem.h>
+
+#include "slab.h"
+
+enum slab_state slab_state;
+LIST_HEAD(slab_caches);
+DEFINE_MUTEX(slab_mutex);
+struct kmem_cache *kmem_cache;
+
+/*
+ * Set of flags that will prevent slab merging
+ */
+#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
+		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+		SLAB_FAILSLAB)
+
+#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | SLAB_NOTRACK)
+
+/*
+ * Merge control. If this is set then no merging of slab caches will occur.
+ * (Could be removed. This was introduced to pacify the merge skeptics.)
+ */
+static int slab_nomerge;
+
+static int __init setup_slab_nomerge(char *str)
+{
+	slab_nomerge = 1;
+	return 1;
+}
+
+#ifdef CONFIG_SLUB
+__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
+#endif
+
+__setup("slab_nomerge", setup_slab_nomerge);
+
+/*
+ * Determine the size of a slab object
+ */
+unsigned int kmem_cache_size(struct kmem_cache *s)
+{
+	return s->object_size;
+}
+EXPORT_SYMBOL(kmem_cache_size);
+
+#ifdef CONFIG_DEBUG_VM
+static int kmem_cache_sanity_check(const char *name, size_t size)
+{
+	struct kmem_cache *s = NULL;
+
+	if (!name || in_interrupt() || size < sizeof(void *) ||
+		size > KMALLOC_MAX_SIZE) {
+		pr_err("kmem_cache_create(%s) integrity check failed\n", name);
+		return -EINVAL;
+	}
+
+	list_for_each_entry(s, &slab_caches, list) {
+		char tmp;
+		int res;
+
+		/*
+		 * This happens when the module gets unloaded and doesn't
+		 * destroy its slab cache and no-one else reuses the vmalloc
+		 * area of the module.  Print a warning.
+		 */
+		res = probe_kernel_address(s->name, tmp);
+		if (res) {
+			pr_err("Slab cache with size %d has lost its name\n",
+			       s->object_size);
+			continue;
+		}
+	}
+
+	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
+	return 0;
+}
+#else
+static inline int kmem_cache_sanity_check(const char *name, size_t size)
+{
+	return 0;
+}
+#endif
+
+void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
+{
+	size_t i;
+
+	for (i = 0; i < nr; i++)
+		kmem_cache_free(s, p[i]);
+}
+
+int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
+								void **p)
+{
+	size_t i;
+
+	for (i = 0; i < nr; i++) {
+		void *x = p[i] = kmem_cache_alloc(s, flags);
+		if (!x) {
+			__kmem_cache_free_bulk(s, i, p);
+			return 0;
+		}
+	}
+	return i;
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+void slab_init_memcg_params(struct kmem_cache *s)
+{
+	s->memcg_params.is_root_cache = true;
+	INIT_LIST_HEAD(&s->memcg_params.list);
+	RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
+}
+
+static int init_memcg_params(struct kmem_cache *s,
+		struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+	struct memcg_cache_array *arr;
+
+	if (memcg) {
+		s->memcg_params.is_root_cache = false;
+		s->memcg_params.memcg = memcg;
+		s->memcg_params.root_cache = root_cache;
+		return 0;
+	}
+
+	slab_init_memcg_params(s);
+
+	if (!memcg_nr_cache_ids)
+		return 0;
+
+	arr = kzalloc(sizeof(struct memcg_cache_array) +
+		      memcg_nr_cache_ids * sizeof(void *),
+		      GFP_KERNEL);
+	if (!arr)
+		return -ENOMEM;
+
+	RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);
+	return 0;
+}
+
+static void destroy_memcg_params(struct kmem_cache *s)
+{
+	if (is_root_cache(s))
+		kfree(rcu_access_pointer(s->memcg_params.memcg_caches));
+}
+
+static int update_memcg_params(struct kmem_cache *s, int new_array_size)
+{
+	struct memcg_cache_array *old, *new;
+
+	if (!is_root_cache(s))
+		return 0;
+
+	new = kzalloc(sizeof(struct memcg_cache_array) +
+		      new_array_size * sizeof(void *), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	old = rcu_dereference_protected(s->memcg_params.memcg_caches,
+					lockdep_is_held(&slab_mutex));
+	if (old)
+		memcpy(new->entries, old->entries,
+		       memcg_nr_cache_ids * sizeof(void *));
+
+	rcu_assign_pointer(s->memcg_params.memcg_caches, new);
+	if (old)
+		kfree_rcu(old, rcu);
+	return 0;
+}
+
+int memcg_update_all_caches(int num_memcgs)
+{
+	struct kmem_cache *s;
+	int ret = 0;
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list) {
+		ret = update_memcg_params(s, num_memcgs);
+		/*
+		 * Instead of freeing the memory, we'll just leave the caches
+		 * up to this point in an updated state.
+		 */
+		if (ret)
+			break;
+	}
+	mutex_unlock(&slab_mutex);
+	return ret;
+}
+#else
+static inline int init_memcg_params(struct kmem_cache *s,
+		struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+	return 0;
+}
+
+static inline void destroy_memcg_params(struct kmem_cache *s)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+/*
+ * Find a mergeable slab cache
+ */
+int slab_unmergeable(struct kmem_cache *s)
+{
+	if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
+		return 1;
+
+	if (!is_root_cache(s))
+		return 1;
+
+	if (s->ctor)
+		return 1;
+
+	/*
+	 * We may have set a slab to be unmergeable during bootstrap.
+	 */
+	if (s->refcount < 0)
+		return 1;
+
+	return 0;
+}
+
+struct kmem_cache *find_mergeable(size_t size, size_t align,
+		unsigned long flags, const char *name, void (*ctor)(void *))
+{
+	struct kmem_cache *s;
+
+	if (slab_nomerge)
+		return NULL;
+
+	if (ctor)
+		return NULL;
+
+	size = ALIGN(size, sizeof(void *));
+	align = calculate_alignment(flags, align, size);
+	size = ALIGN(size, align);
+	flags = kmem_cache_flags(size, flags, name, NULL);
+
+	if (flags & SLAB_NEVER_MERGE)
+		return NULL;
+
+	list_for_each_entry_reverse(s, &slab_caches, list) {
+		if (slab_unmergeable(s))
+			continue;
+
+		if (size > s->size)
+			continue;
+
+		if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
+			continue;
+		/*
+		 * Check if alignment is compatible.
+		 * Courtesy of Adrian Drzewiecki
+		 */
+		if ((s->size & ~(align - 1)) != s->size)
+			continue;
+
+		if (s->size - size >= sizeof(void *))
+			continue;
+
+		if (IS_ENABLED(CONFIG_SLAB) && align &&
+			(align > s->align || s->align % align))
+			continue;
+
+		return s;
+	}
+	return NULL;
+}
+
+/*
+ * Figure out what the alignment of the objects will be given a set of
+ * flags, a user specified alignment and the size of the objects.
+ */
+unsigned long calculate_alignment(unsigned long flags,
+		unsigned long align, unsigned long size)
+{
+	/*
+	 * If the user wants hardware cache aligned objects then follow that
+	 * suggestion if the object is sufficiently large.
+	 *
+	 * The hardware cache alignment cannot override the specified
+	 * alignment though. If that is greater then use it.
+	 */
+	if (flags & SLAB_HWCACHE_ALIGN) {
+		unsigned long ralign = cache_line_size();
+		while (size <= ralign / 2)
+			ralign /= 2;
+		align = max(align, ralign);
+	}
+
+	if (align < ARCH_SLAB_MINALIGN)
+		align = ARCH_SLAB_MINALIGN;
+
+	return ALIGN(align, sizeof(void *));
+}
+
+static struct kmem_cache *create_cache(const char *name,
+		size_t object_size, size_t size, size_t align,
+		unsigned long flags, void (*ctor)(void *),
+		struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+	struct kmem_cache *s;
+	int err;
+
+	err = -ENOMEM;
+	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
+	if (!s)
+		goto out;
+
+	s->name = name;
+	s->object_size = object_size;
+	s->size = size;
+	s->align = align;
+	s->ctor = ctor;
+
+	err = init_memcg_params(s, memcg, root_cache);
+	if (err)
+		goto out_free_cache;
+
+	err = __kmem_cache_create(s, flags);
+	if (err)
+		goto out_free_cache;
+
+	s->refcount = 1;
+	list_add(&s->list, &slab_caches);
+out:
+	if (err)
+		return ERR_PTR(err);
+	return s;
+
+out_free_cache:
+	destroy_memcg_params(s);
+	kmem_cache_free(kmem_cache, s);
+	goto out;
+}
+
+/*
+ * kmem_cache_create - Create a cache.
+ * @name: A string which is used in /proc/slabinfo to identify this cache.
+ * @size: The size of objects to be created in this cache.
+ * @align: The required alignment for the objects.
+ * @flags: SLAB flags
+ * @ctor: A constructor for the objects.
+ *
+ * Returns a ptr to the cache on success, NULL on failure.
+ * Cannot be called within a interrupt, but can be interrupted.
+ * The @ctor is run when new pages are allocated by the cache.
+ *
+ * The flags are
+ *
+ * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
+ * to catch references to uninitialised memory.
+ *
+ * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
+ * for buffer overruns.
+ *
+ * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
+ * cacheline.  This can be beneficial if you're counting cycles as closely
+ * as davem.
+ */
+struct kmem_cache *
+kmem_cache_create(const char *name, size_t size, size_t align,
+		  unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *s = NULL;
+	const char *cache_name;
+	int err;
+
+	get_online_cpus();
+	get_online_mems();
+	memcg_get_cache_ids();
+
+	mutex_lock(&slab_mutex);
+
+	err = kmem_cache_sanity_check(name, size);
+	if (err) {
+		goto out_unlock;
+	}
+
+	/*
+	 * Some allocators will constraint the set of valid flags to a subset
+	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
+	 * case, and we'll just provide them with a sanitized version of the
+	 * passed flags.
+	 */
+	flags &= CACHE_CREATE_MASK;
+
+	s = __kmem_cache_alias(name, size, align, flags, ctor);
+	if (s)
+		goto out_unlock;
+
+	cache_name = kstrdup_const(name, GFP_KERNEL);
+	if (!cache_name) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
+	s = create_cache(cache_name, size, size,
+			 calculate_alignment(flags, align, size),
+			 flags, ctor, NULL, NULL);
+	if (IS_ERR(s)) {
+		err = PTR_ERR(s);
+		kfree_const(cache_name);
+	}
+
+out_unlock:
+	mutex_unlock(&slab_mutex);
+
+	memcg_put_cache_ids();
+	put_online_mems();
+	put_online_cpus();
+
+	if (err) {
+		if (flags & SLAB_PANIC)
+			panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
+				name, err);
+		else {
+			printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
+				name, err);
+			dump_stack();
+		}
+		return NULL;
+	}
+	return s;
+}
+EXPORT_SYMBOL(kmem_cache_create);
+
+static int shutdown_cache(struct kmem_cache *s,
+		struct list_head *release, bool *need_rcu_barrier)
+{
+	if (__kmem_cache_shutdown(s) != 0)
+		return -EBUSY;
+
+	if (s->flags & SLAB_DESTROY_BY_RCU)
+		*need_rcu_barrier = true;
+
+	list_move(&s->list, release);
+	return 0;
+}
+
+static void release_caches(struct list_head *release, bool need_rcu_barrier)
+{
+	struct kmem_cache *s, *s2;
+
+	if (need_rcu_barrier)
+		rcu_barrier();
+
+	list_for_each_entry_safe(s, s2, release, list) {
+#ifdef SLAB_SUPPORTS_SYSFS
+		sysfs_slab_remove(s);
+#else
+		slab_kmem_cache_release(s);
+#endif
+	}
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+/*
+ * memcg_create_kmem_cache - Create a cache for a memory cgroup.
+ * @memcg: The memory cgroup the new cache is for.
+ * @root_cache: The parent of the new cache.
+ *
+ * This function attempts to create a kmem cache that will serve allocation
+ * requests going from @memcg to @root_cache. The new cache inherits properties
+ * from its parent.
+ */
+void memcg_create_kmem_cache(struct mem_cgroup *memcg,
+			     struct kmem_cache *root_cache)
+{
+	static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
+	struct cgroup_subsys_state *css = &memcg->css;
+	struct memcg_cache_array *arr;
+	struct kmem_cache *s = NULL;
+	char *cache_name;
+	int idx;
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+
+	/*
+	 * The memory cgroup could have been deactivated while the cache
+	 * creation work was pending.
+	 */
+	if (!memcg_kmem_is_active(memcg))
+		goto out_unlock;
+
+	idx = memcg_cache_id(memcg);
+	arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
+					lockdep_is_held(&slab_mutex));
+
+	/*
+	 * Since per-memcg caches are created asynchronously on first
+	 * allocation (see memcg_kmem_get_cache()), several threads can try to
+	 * create the same cache, but only one of them may succeed.
+	 */
+	if (arr->entries[idx])
+		goto out_unlock;
+
+	cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
+	cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
+			       css->serial_nr, memcg_name_buf);
+	if (!cache_name)
+		goto out_unlock;
+
+	s = create_cache(cache_name, root_cache->object_size,
+			 root_cache->size, root_cache->align,
+			 root_cache->flags, root_cache->ctor,
+			 memcg, root_cache);
+	/*
+	 * If we could not create a memcg cache, do not complain, because
+	 * that's not critical at all as we can always proceed with the root
+	 * cache.
+	 */
+	if (IS_ERR(s)) {
+		kfree(cache_name);
+		goto out_unlock;
+	}
+
+	list_add(&s->memcg_params.list, &root_cache->memcg_params.list);
+
+	/*
+	 * Since readers won't lock (see cache_from_memcg_idx()), we need a
+	 * barrier here to ensure nobody will see the kmem_cache partially
+	 * initialized.
+	 */
+	smp_wmb();
+	arr->entries[idx] = s;
+
+out_unlock:
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+}
+
+void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
+{
+	int idx;
+	struct memcg_cache_array *arr;
+	struct kmem_cache *s, *c;
+
+	idx = memcg_cache_id(memcg);
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list) {
+		if (!is_root_cache(s))
+			continue;
+
+		arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
+						lockdep_is_held(&slab_mutex));
+		c = arr->entries[idx];
+		if (!c)
+			continue;
+
+		__kmem_cache_shrink(c, true);
+		arr->entries[idx] = NULL;
+	}
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+}
+
+static int __shutdown_memcg_cache(struct kmem_cache *s,
+		struct list_head *release, bool *need_rcu_barrier)
+{
+	BUG_ON(is_root_cache(s));
+
+	if (shutdown_cache(s, release, need_rcu_barrier))
+		return -EBUSY;
+
+	list_del(&s->memcg_params.list);
+	return 0;
+}
+
+void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
+{
+	LIST_HEAD(release);
+	bool need_rcu_barrier = false;
+	struct kmem_cache *s, *s2;
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry_safe(s, s2, &slab_caches, list) {
+		if (is_root_cache(s) || s->memcg_params.memcg != memcg)
+			continue;
+		/*
+		 * The cgroup is about to be freed and therefore has no charges
+		 * left. Hence, all its caches must be empty by now.
+		 */
+		BUG_ON(__shutdown_memcg_cache(s, &release, &need_rcu_barrier));
+	}
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+
+	release_caches(&release, need_rcu_barrier);
+}
+
+static int shutdown_memcg_caches(struct kmem_cache *s,
+		struct list_head *release, bool *need_rcu_barrier)
+{
+	struct memcg_cache_array *arr;
+	struct kmem_cache *c, *c2;
+	LIST_HEAD(busy);
+	int i;
+
+	BUG_ON(!is_root_cache(s));
+
+	/*
+	 * First, shutdown active caches, i.e. caches that belong to online
+	 * memory cgroups.
+	 */
+	arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
+					lockdep_is_held(&slab_mutex));
+	for_each_memcg_cache_index(i) {
+		c = arr->entries[i];
+		if (!c)
+			continue;
+		if (__shutdown_memcg_cache(c, release, need_rcu_barrier))
+			/*
+			 * The cache still has objects. Move it to a temporary
+			 * list so as not to try to destroy it for a second
+			 * time while iterating over inactive caches below.
+			 */
+			list_move(&c->memcg_params.list, &busy);
+		else
+			/*
+			 * The cache is empty and will be destroyed soon. Clear
+			 * the pointer to it in the memcg_caches array so that
+			 * it will never be accessed even if the root cache
+			 * stays alive.
+			 */
+			arr->entries[i] = NULL;
+	}
+
+	/*
+	 * Second, shutdown all caches left from memory cgroups that are now
+	 * offline.
+	 */
+	list_for_each_entry_safe(c, c2, &s->memcg_params.list,
+				 memcg_params.list)
+		__shutdown_memcg_cache(c, release, need_rcu_barrier);
+
+	list_splice(&busy, &s->memcg_params.list);
+
+	/*
+	 * A cache being destroyed must be empty. In particular, this means
+	 * that all per memcg caches attached to it must be empty too.
+	 */
+	if (!list_empty(&s->memcg_params.list))
+		return -EBUSY;
+	return 0;
+}
+#else
+static inline int shutdown_memcg_caches(struct kmem_cache *s,
+		struct list_head *release, bool *need_rcu_barrier)
+{
+	return 0;
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+void slab_kmem_cache_release(struct kmem_cache *s)
+{
+	destroy_memcg_params(s);
+	kfree_const(s->name);
+	kmem_cache_free(kmem_cache, s);
+}
+
+void kmem_cache_destroy(struct kmem_cache *s)
+{
+	LIST_HEAD(release);
+	bool need_rcu_barrier = false;
+	int err;
+
+	if (unlikely(!s))
+		return;
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+
+	s->refcount--;
+	if (s->refcount)
+		goto out_unlock;
+
+	err = shutdown_memcg_caches(s, &release, &need_rcu_barrier);
+	if (!err)
+		err = shutdown_cache(s, &release, &need_rcu_barrier);
+
+	if (err) {
+		pr_err("kmem_cache_destroy %s: "
+		       "Slab cache still has objects\n", s->name);
+		dump_stack();
+	}
+out_unlock:
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+
+	release_caches(&release, need_rcu_barrier);
+}
+EXPORT_SYMBOL(kmem_cache_destroy);
+
+/**
+ * kmem_cache_shrink - Shrink a cache.
+ * @cachep: The cache to shrink.
+ *
+ * Releases as many slabs as possible for a cache.
+ * To help debugging, a zero exit status indicates all slabs were released.
+ */
+int kmem_cache_shrink(struct kmem_cache *cachep)
+{
+	int ret;
+
+	get_online_cpus();
+	get_online_mems();
+	ret = __kmem_cache_shrink(cachep, false);
+	put_online_mems();
+	put_online_cpus();
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_shrink);
+
+bool slab_is_available(void)
+{
+	return slab_state >= UP;
+}
+
+#ifndef CONFIG_SLOB
+/* Create a cache during boot when no slab services are available yet */
+void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
+		unsigned long flags)
+{
+	int err;
+
+	s->name = name;
+	s->size = s->object_size = size;
+	s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
+
+	slab_init_memcg_params(s);
+
+	err = __kmem_cache_create(s, flags);
+
+	if (err)
+		panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
+					name, size, err);
+
+	s->refcount = -1;	/* Exempt from merging for now */
+}
+
+struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
+				unsigned long flags)
+{
+	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
+
+	if (!s)
+		panic("Out of memory when creating slab %s\n", name);
+
+	create_boot_cache(s, name, size, flags);
+	list_add(&s->list, &slab_caches);
+	s->refcount = 1;
+	return s;
+}
+
+struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
+EXPORT_SYMBOL(kmalloc_caches);
+
+#ifdef CONFIG_ZONE_DMA
+struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
+EXPORT_SYMBOL(kmalloc_dma_caches);
+#endif
+
+/*
+ * Conversion table for small slabs sizes / 8 to the index in the
+ * kmalloc array. This is necessary for slabs < 192 since we have non power
+ * of two cache sizes there. The size of larger slabs can be determined using
+ * fls.
+ */
+static s8 size_index[24] = {
+	3,	/* 8 */
+	4,	/* 16 */
+	5,	/* 24 */
+	5,	/* 32 */
+	6,	/* 40 */
+	6,	/* 48 */
+	6,	/* 56 */
+	6,	/* 64 */
+	1,	/* 72 */
+	1,	/* 80 */
+	1,	/* 88 */
+	1,	/* 96 */
+	7,	/* 104 */
+	7,	/* 112 */
+	7,	/* 120 */
+	7,	/* 128 */
+	2,	/* 136 */
+	2,	/* 144 */
+	2,	/* 152 */
+	2,	/* 160 */
+	2,	/* 168 */
+	2,	/* 176 */
+	2,	/* 184 */
+	2	/* 192 */
+};
+
+static inline int size_index_elem(size_t bytes)
+{
+	return (bytes - 1) / 8;
+}
+
+/*
+ * Find the kmem_cache structure that serves a given size of
+ * allocation
+ */
+struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
+{
+	int index;
+
+	if (unlikely(size > KMALLOC_MAX_SIZE)) {
+		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
+		return NULL;
+	}
+
+	if (size <= 192) {
+		if (!size)
+			return ZERO_SIZE_PTR;
+
+		index = size_index[size_index_elem(size)];
+	} else
+		index = fls(size - 1);
+
+#ifdef CONFIG_ZONE_DMA
+	if (unlikely((flags & GFP_DMA)))
+		return kmalloc_dma_caches[index];
+
+#endif
+	return kmalloc_caches[index];
+}
+
+/*
+ * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
+ * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
+ * kmalloc-67108864.
+ */
+static struct {
+	const char *name;
+	unsigned long size;
+} const kmalloc_info[] __initconst = {
+	{NULL,                      0},		{"kmalloc-96",             96},
+	{"kmalloc-192",           192},		{"kmalloc-8",               8},
+	{"kmalloc-16",             16},		{"kmalloc-32",             32},
+	{"kmalloc-64",             64},		{"kmalloc-128",           128},
+	{"kmalloc-256",           256},		{"kmalloc-512",           512},
+	{"kmalloc-1024",         1024},		{"kmalloc-2048",         2048},
+	{"kmalloc-4096",         4096},		{"kmalloc-8192",         8192},
+	{"kmalloc-16384",       16384},		{"kmalloc-32768",       32768},
+	{"kmalloc-65536",       65536},		{"kmalloc-131072",     131072},
+	{"kmalloc-262144",     262144},		{"kmalloc-524288",     524288},
+	{"kmalloc-1048576",   1048576},		{"kmalloc-2097152",   2097152},
+	{"kmalloc-4194304",   4194304},		{"kmalloc-8388608",   8388608},
+	{"kmalloc-16777216", 16777216},		{"kmalloc-33554432", 33554432},
+	{"kmalloc-67108864", 67108864}
+};
+
+/*
+ * Patch up the size_index table if we have strange large alignment
+ * requirements for the kmalloc array. This is only the case for
+ * MIPS it seems. The standard arches will not generate any code here.
+ *
+ * Largest permitted alignment is 256 bytes due to the way we
+ * handle the index determination for the smaller caches.
+ *
+ * Make sure that nothing crazy happens if someone starts tinkering
+ * around with ARCH_KMALLOC_MINALIGN
+ */
+void __init setup_kmalloc_cache_index_table(void)
+{
+	int i;
+
+	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
+		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
+
+	for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
+		int elem = size_index_elem(i);
+
+		if (elem >= ARRAY_SIZE(size_index))
+			break;
+		size_index[elem] = KMALLOC_SHIFT_LOW;
+	}
+
+	if (KMALLOC_MIN_SIZE >= 64) {
+		/*
+		 * The 96 byte size cache is not used if the alignment
+		 * is 64 byte.
+		 */
+		for (i = 64 + 8; i <= 96; i += 8)
+			size_index[size_index_elem(i)] = 7;
+
+	}
+
+	if (KMALLOC_MIN_SIZE >= 128) {
+		/*
+		 * The 192 byte sized cache is not used if the alignment
+		 * is 128 byte. Redirect kmalloc to use the 256 byte cache
+		 * instead.
+		 */
+		for (i = 128 + 8; i <= 192; i += 8)
+			size_index[size_index_elem(i)] = 8;
+	}
+}
+
+static void __init new_kmalloc_cache(int idx, unsigned long flags)
+{
+	kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
+					kmalloc_info[idx].size, flags);
+}
+
+/*
+ * Create the kmalloc array. Some of the regular kmalloc arrays
+ * may already have been created because they were needed to
+ * enable allocations for slab creation.
+ */
+void __init create_kmalloc_caches(unsigned long flags)
+{
+	int i;
+
+	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
+		if (!kmalloc_caches[i])
+			new_kmalloc_cache(i, flags);
+
+		/*
+		 * Caches that are not of the two-to-the-power-of size.
+		 * These have to be created immediately after the
+		 * earlier power of two caches
+		 */
+		if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
+			new_kmalloc_cache(1, flags);
+		if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
+			new_kmalloc_cache(2, flags);
+	}
+
+	/* Kmalloc array is now usable */
+	slab_state = UP;
+
+#ifdef CONFIG_ZONE_DMA
+	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
+		struct kmem_cache *s = kmalloc_caches[i];
+
+		if (s) {
+			int size = kmalloc_size(i);
+			char *n = kasprintf(GFP_NOWAIT,
+				 "dma-kmalloc-%d", size);
+
+			BUG_ON(!n);
+			kmalloc_dma_caches[i] = create_kmalloc_cache(n,
+				size, SLAB_CACHE_DMA | flags);
+		}
+	}
+#endif
+}
+#endif /* !CONFIG_SLOB */
+
+/*
+ * To avoid unnecessary overhead, we pass through large allocation requests
+ * directly to the page allocator. We use __GFP_COMP, because we will need to
+ * know the allocation order to free the pages properly in kfree.
+ */
+void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
+{
+	void *ret;
+	struct page *page;
+
+	flags |= __GFP_COMP;
+	page = alloc_kmem_pages(flags, order);
+	ret = page ? page_address(page) : NULL;
+	kmemleak_alloc(ret, size, 1, flags);
+	kasan_kmalloc_large(ret, size);
+	return ret;
+}
+EXPORT_SYMBOL(kmalloc_order);
+
+#ifdef CONFIG_TRACING
+void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
+{
+	void *ret = kmalloc_order(size, flags, order);
+	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
+	return ret;
+}
+EXPORT_SYMBOL(kmalloc_order_trace);
+#endif
+
+#ifdef CONFIG_SLABINFO
+
+#ifdef CONFIG_SLAB
+#define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
+#else
+#define SLABINFO_RIGHTS S_IRUSR
+#endif
+
+static void print_slabinfo_header(struct seq_file *m)
+{
+	/*
+	 * Output format version, so at least we can change it
+	 * without _too_ many complaints.
+	 */
+#ifdef CONFIG_DEBUG_SLAB
+	seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
+#else
+	seq_puts(m, "slabinfo - version: 2.1\n");
+#endif
+	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
+		 "<objperslab> <pagesperslab>");
+	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
+	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
+#ifdef CONFIG_DEBUG_SLAB
+	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
+		 "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
+	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
+#endif
+	seq_putc(m, '\n');
+}
+
+void *slab_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&slab_mutex);
+	return seq_list_start(&slab_caches, *pos);
+}
+
+void *slab_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	return seq_list_next(p, &slab_caches, pos);
+}
+
+void slab_stop(struct seq_file *m, void *p)
+{
+	mutex_unlock(&slab_mutex);
+}
+
+static void
+memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
+{
+	struct kmem_cache *c;
+	struct slabinfo sinfo;
+
+	if (!is_root_cache(s))
+		return;
+
+	for_each_memcg_cache(c, s) {
+		memset(&sinfo, 0, sizeof(sinfo));
+		get_slabinfo(c, &sinfo);
+
+		info->active_slabs += sinfo.active_slabs;
+		info->num_slabs += sinfo.num_slabs;
+		info->shared_avail += sinfo.shared_avail;
+		info->active_objs += sinfo.active_objs;
+		info->num_objs += sinfo.num_objs;
+	}
+}
+
+static void cache_show(struct kmem_cache *s, struct seq_file *m)
+{
+	struct slabinfo sinfo;
+
+	memset(&sinfo, 0, sizeof(sinfo));
+	get_slabinfo(s, &sinfo);
+
+	memcg_accumulate_slabinfo(s, &sinfo);
+
+	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
+		   cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
+		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
+
+	seq_printf(m, " : tunables %4u %4u %4u",
+		   sinfo.limit, sinfo.batchcount, sinfo.shared);
+	seq_printf(m, " : slabdata %6lu %6lu %6lu",
+		   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
+	slabinfo_show_stats(m, s);
+	seq_putc(m, '\n');
+}
+
+static int slab_show(struct seq_file *m, void *p)
+{
+	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
+
+	if (p == slab_caches.next)
+		print_slabinfo_header(m);
+	if (is_root_cache(s))
+		cache_show(s, m);
+	return 0;
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+int memcg_slab_show(struct seq_file *m, void *p)
+{
+	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	if (p == slab_caches.next)
+		print_slabinfo_header(m);
+	if (!is_root_cache(s) && s->memcg_params.memcg == memcg)
+		cache_show(s, m);
+	return 0;
+}
+#endif
+
+/*
+ * slabinfo_op - iterator that generates /proc/slabinfo
+ *
+ * Output layout:
+ * cache-name
+ * num-active-objs
+ * total-objs
+ * object size
+ * num-active-slabs
+ * total-slabs
+ * num-pages-per-slab
+ * + further values on SMP and with statistics enabled
+ */
+static const struct seq_operations slabinfo_op = {
+	.start = slab_start,
+	.next = slab_next,
+	.stop = slab_stop,
+	.show = slab_show,
+};
+
+static int slabinfo_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &slabinfo_op);
+}
+
+static const struct file_operations proc_slabinfo_operations = {
+	.open		= slabinfo_open,
+	.read		= seq_read,
+	.write          = slabinfo_write,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static int __init slab_proc_init(void)
+{
+	proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
+						&proc_slabinfo_operations);
+	return 0;
+}
+module_init(slab_proc_init);
+#endif /* CONFIG_SLABINFO */
+
+static __always_inline void *__do_krealloc(const void *p, size_t new_size,
+					   gfp_t flags)
+{
+	void *ret;
+	size_t ks = 0;
+
+	if (p)
+		ks = ksize(p);
+
+	if (ks >= new_size) {
+		kasan_krealloc((void *)p, new_size);
+		return (void *)p;
+	}
+
+	ret = kmalloc_track_caller(new_size, flags);
+	if (ret && p)
+		memcpy(ret, p, ks);
+
+	return ret;
+}
+
+/**
+ * __krealloc - like krealloc() but don't free @p.
+ * @p: object to reallocate memory for.
+ * @new_size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate.
+ *
+ * This function is like krealloc() except it never frees the originally
+ * allocated buffer. Use this if you don't want to free the buffer immediately
+ * like, for example, with RCU.
+ */
+void *__krealloc(const void *p, size_t new_size, gfp_t flags)
+{
+	if (unlikely(!new_size))
+		return ZERO_SIZE_PTR;
+
+	return __do_krealloc(p, new_size, flags);
+
+}
+EXPORT_SYMBOL(__krealloc);
+
+/**
+ * krealloc - reallocate memory. The contents will remain unchanged.
+ * @p: object to reallocate memory for.
+ * @new_size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate.
+ *
+ * The contents of the object pointed to are preserved up to the
+ * lesser of the new and old sizes.  If @p is %NULL, krealloc()
+ * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
+ * %NULL pointer, the object pointed to is freed.
+ */
+void *krealloc(const void *p, size_t new_size, gfp_t flags)
+{
+	void *ret;
+
+	if (unlikely(!new_size)) {
+		kfree(p);
+		return ZERO_SIZE_PTR;
+	}
+
+	ret = __do_krealloc(p, new_size, flags);
+	if (ret && p != ret)
+		kfree(p);
+
+	return ret;
+}
+EXPORT_SYMBOL(krealloc);
+
+/**
+ * kzfree - like kfree but zero memory
+ * @p: object to free memory of
+ *
+ * The memory of the object @p points to is zeroed before freed.
+ * If @p is %NULL, kzfree() does nothing.
+ *
+ * Note: this function zeroes the whole allocated buffer which can be a good
+ * deal bigger than the requested buffer size passed to kmalloc(). So be
+ * careful when using this function in performance sensitive code.
+ */
+void kzfree(const void *p)
+{
+	size_t ks;
+	void *mem = (void *)p;
+
+	if (unlikely(ZERO_OR_NULL_PTR(mem)))
+		return;
+	ks = ksize(mem);
+	memset(mem, 0, ks);
+	kfree(mem);
+}
+EXPORT_SYMBOL(kzfree);
+
+/* Tracepoints definitions. */
+EXPORT_TRACEPOINT_SYMBOL(kmalloc);
+EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
+EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
+EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
+EXPORT_TRACEPOINT_SYMBOL(kfree);
+EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
diff --git a/mm/slob.c b/mm/slob.c
new file mode 100644
index 0000000..17e8f8c
--- /dev/null
+++ b/mm/slob.c
@@ -0,0 +1,654 @@
+/*
+ * SLOB Allocator: Simple List Of Blocks
+ *
+ * Matt Mackall <mpm@selenic.com> 12/30/03
+ *
+ * NUMA support by Paul Mundt, 2007.
+ *
+ * How SLOB works:
+ *
+ * The core of SLOB is a traditional K&R style heap allocator, with
+ * support for returning aligned objects. The granularity of this
+ * allocator is as little as 2 bytes, however typically most architectures
+ * will require 4 bytes on 32-bit and 8 bytes on 64-bit.
+ *
+ * The slob heap is a set of linked list of pages from alloc_pages(),
+ * and within each page, there is a singly-linked list of free blocks
+ * (slob_t). The heap is grown on demand. To reduce fragmentation,
+ * heap pages are segregated into three lists, with objects less than
+ * 256 bytes, objects less than 1024 bytes, and all other objects.
+ *
+ * Allocation from heap involves first searching for a page with
+ * sufficient free blocks (using a next-fit-like approach) followed by
+ * a first-fit scan of the page. Deallocation inserts objects back
+ * into the free list in address order, so this is effectively an
+ * address-ordered first fit.
+ *
+ * Above this is an implementation of kmalloc/kfree. Blocks returned
+ * from kmalloc are prepended with a 4-byte header with the kmalloc size.
+ * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
+ * alloc_pages() directly, allocating compound pages so the page order
+ * does not have to be separately tracked.
+ * These objects are detected in kfree() because PageSlab()
+ * is false for them.
+ *
+ * SLAB is emulated on top of SLOB by simply calling constructors and
+ * destructors for every SLAB allocation. Objects are returned with the
+ * 4-byte alignment unless the SLAB_HWCACHE_ALIGN flag is set, in which
+ * case the low-level allocator will fragment blocks to create the proper
+ * alignment. Again, objects of page-size or greater are allocated by
+ * calling alloc_pages(). As SLAB objects know their size, no separate
+ * size bookkeeping is necessary and there is essentially no allocation
+ * space overhead, and compound pages aren't needed for multi-page
+ * allocations.
+ *
+ * NUMA support in SLOB is fairly simplistic, pushing most of the real
+ * logic down to the page allocator, and simply doing the node accounting
+ * on the upper levels. In the event that a node id is explicitly
+ * provided, __alloc_pages_node() with the specified node id is used
+ * instead. The common case (or when the node id isn't explicitly provided)
+ * will default to the current node, as per numa_node_id().
+ *
+ * Node aware pages are still inserted in to the global freelist, and
+ * these are scanned for by matching against the node id encoded in the
+ * page flags. As a result, block allocations that can be satisfied from
+ * the freelist will only be done so on pages residing on the same node,
+ * in order to prevent random node placement.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include <linux/mm.h>
+#include <linux/swap.h> /* struct reclaim_state */
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/kmemleak.h>
+
+#include <trace/events/kmem.h>
+
+#include <linux/atomic.h>
+
+#include "slab.h"
+/*
+ * slob_block has a field 'units', which indicates size of block if +ve,
+ * or offset of next block if -ve (in SLOB_UNITs).
+ *
+ * Free blocks of size 1 unit simply contain the offset of the next block.
+ * Those with larger size contain their size in the first SLOB_UNIT of
+ * memory, and the offset of the next free block in the second SLOB_UNIT.
+ */
+#if PAGE_SIZE <= (32767 * 2)
+typedef s16 slobidx_t;
+#else
+typedef s32 slobidx_t;
+#endif
+
+struct slob_block {
+	slobidx_t units;
+};
+typedef struct slob_block slob_t;
+
+/*
+ * All partially free slob pages go on these lists.
+ */
+#define SLOB_BREAK1 256
+#define SLOB_BREAK2 1024
+static LIST_HEAD(free_slob_small);
+static LIST_HEAD(free_slob_medium);
+static LIST_HEAD(free_slob_large);
+
+/*
+ * slob_page_free: true for pages on free_slob_pages list.
+ */
+static inline int slob_page_free(struct page *sp)
+{
+	return PageSlobFree(sp);
+}
+
+static void set_slob_page_free(struct page *sp, struct list_head *list)
+{
+	list_add(&sp->lru, list);
+	__SetPageSlobFree(sp);
+}
+
+static inline void clear_slob_page_free(struct page *sp)
+{
+	list_del(&sp->lru);
+	__ClearPageSlobFree(sp);
+}
+
+#define SLOB_UNIT sizeof(slob_t)
+#define SLOB_UNITS(size) DIV_ROUND_UP(size, SLOB_UNIT)
+
+/*
+ * struct slob_rcu is inserted at the tail of allocated slob blocks, which
+ * were created with a SLAB_DESTROY_BY_RCU slab. slob_rcu is used to free
+ * the block using call_rcu.
+ */
+struct slob_rcu {
+	struct rcu_head head;
+	int size;
+};
+
+/*
+ * slob_lock protects all slob allocator structures.
+ */
+static DEFINE_SPINLOCK(slob_lock);
+
+/*
+ * Encode the given size and next info into a free slob block s.
+ */
+static void set_slob(slob_t *s, slobidx_t size, slob_t *next)
+{
+	slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK);
+	slobidx_t offset = next - base;
+
+	if (size > 1) {
+		s[0].units = size;
+		s[1].units = offset;
+	} else
+		s[0].units = -offset;
+}
+
+/*
+ * Return the size of a slob block.
+ */
+static slobidx_t slob_units(slob_t *s)
+{
+	if (s->units > 0)
+		return s->units;
+	return 1;
+}
+
+/*
+ * Return the next free slob block pointer after this one.
+ */
+static slob_t *slob_next(slob_t *s)
+{
+	slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK);
+	slobidx_t next;
+
+	if (s[0].units < 0)
+		next = -s[0].units;
+	else
+		next = s[1].units;
+	return base+next;
+}
+
+/*
+ * Returns true if s is the last free block in its page.
+ */
+static int slob_last(slob_t *s)
+{
+	return !((unsigned long)slob_next(s) & ~PAGE_MASK);
+}
+
+static void *slob_new_pages(gfp_t gfp, int order, int node)
+{
+	void *page;
+
+#ifdef CONFIG_NUMA
+	if (node != NUMA_NO_NODE)
+		page = __alloc_pages_node(node, gfp, order);
+	else
+#endif
+		page = alloc_pages(gfp, order);
+
+	if (!page)
+		return NULL;
+
+	return page_address(page);
+}
+
+static void slob_free_pages(void *b, int order)
+{
+	if (current->reclaim_state)
+		current->reclaim_state->reclaimed_slab += 1 << order;
+	free_pages((unsigned long)b, order);
+}
+
+/*
+ * Allocate a slob block within a given slob_page sp.
+ */
+static void *slob_page_alloc(struct page *sp, size_t size, int align)
+{
+	slob_t *prev, *cur, *aligned = NULL;
+	int delta = 0, units = SLOB_UNITS(size);
+
+	for (prev = NULL, cur = sp->freelist; ; prev = cur, cur = slob_next(cur)) {
+		slobidx_t avail = slob_units(cur);
+
+		if (align) {
+			aligned = (slob_t *)ALIGN((unsigned long)cur, align);
+			delta = aligned - cur;
+		}
+		if (avail >= units + delta) { /* room enough? */
+			slob_t *next;
+
+			if (delta) { /* need to fragment head to align? */
+				next = slob_next(cur);
+				set_slob(aligned, avail - delta, next);
+				set_slob(cur, delta, aligned);
+				prev = cur;
+				cur = aligned;
+				avail = slob_units(cur);
+			}
+
+			next = slob_next(cur);
+			if (avail == units) { /* exact fit? unlink. */
+				if (prev)
+					set_slob(prev, slob_units(prev), next);
+				else
+					sp->freelist = next;
+			} else { /* fragment */
+				if (prev)
+					set_slob(prev, slob_units(prev), cur + units);
+				else
+					sp->freelist = cur + units;
+				set_slob(cur + units, avail - units, next);
+			}
+
+			sp->units -= units;
+			if (!sp->units)
+				clear_slob_page_free(sp);
+			return cur;
+		}
+		if (slob_last(cur))
+			return NULL;
+	}
+}
+
+/*
+ * slob_alloc: entry point into the slob allocator.
+ */
+static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
+{
+	struct page *sp;
+	struct list_head *prev;
+	struct list_head *slob_list;
+	slob_t *b = NULL;
+	unsigned long flags;
+
+	if (size < SLOB_BREAK1)
+		slob_list = &free_slob_small;
+	else if (size < SLOB_BREAK2)
+		slob_list = &free_slob_medium;
+	else
+		slob_list = &free_slob_large;
+
+	spin_lock_irqsave(&slob_lock, flags);
+	/* Iterate through each partially free page, try to find room */
+	list_for_each_entry(sp, slob_list, lru) {
+#ifdef CONFIG_NUMA
+		/*
+		 * If there's a node specification, search for a partial
+		 * page with a matching node id in the freelist.
+		 */
+		if (node != NUMA_NO_NODE && page_to_nid(sp) != node)
+			continue;
+#endif
+		/* Enough room on this page? */
+		if (sp->units < SLOB_UNITS(size))
+			continue;
+
+		/* Attempt to alloc */
+		prev = sp->lru.prev;
+		b = slob_page_alloc(sp, size, align);
+		if (!b)
+			continue;
+
+		/* Improve fragment distribution and reduce our average
+		 * search time by starting our next search here. (see
+		 * Knuth vol 1, sec 2.5, pg 449) */
+		if (prev != slob_list->prev &&
+				slob_list->next != prev->next)
+			list_move_tail(slob_list, prev->next);
+		break;
+	}
+	spin_unlock_irqrestore(&slob_lock, flags);
+
+	/* Not enough space: must allocate a new page */
+	if (!b) {
+		b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node);
+		if (!b)
+			return NULL;
+		sp = virt_to_page(b);
+		__SetPageSlab(sp);
+
+		spin_lock_irqsave(&slob_lock, flags);
+		sp->units = SLOB_UNITS(PAGE_SIZE);
+		sp->freelist = b;
+		INIT_LIST_HEAD(&sp->lru);
+		set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
+		set_slob_page_free(sp, slob_list);
+		b = slob_page_alloc(sp, size, align);
+		BUG_ON(!b);
+		spin_unlock_irqrestore(&slob_lock, flags);
+	}
+	if (unlikely((gfp & __GFP_ZERO) && b))
+		memset(b, 0, size);
+	return b;
+}
+
+/*
+ * slob_free: entry point into the slob allocator.
+ */
+static void slob_free(void *block, int size)
+{
+	struct page *sp;
+	slob_t *prev, *next, *b = (slob_t *)block;
+	slobidx_t units;
+	unsigned long flags;
+	struct list_head *slob_list;
+
+	if (unlikely(ZERO_OR_NULL_PTR(block)))
+		return;
+	BUG_ON(!size);
+
+	sp = virt_to_page(block);
+	units = SLOB_UNITS(size);
+
+	spin_lock_irqsave(&slob_lock, flags);
+
+	if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) {
+		/* Go directly to page allocator. Do not pass slob allocator */
+		if (slob_page_free(sp))
+			clear_slob_page_free(sp);
+		spin_unlock_irqrestore(&slob_lock, flags);
+		__ClearPageSlab(sp);
+		page_mapcount_reset(sp);
+		slob_free_pages(b, 0);
+		return;
+	}
+
+	if (!slob_page_free(sp)) {
+		/* This slob page is about to become partially free. Easy! */
+		sp->units = units;
+		sp->freelist = b;
+		set_slob(b, units,
+			(void *)((unsigned long)(b +
+					SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK));
+		if (size < SLOB_BREAK1)
+			slob_list = &free_slob_small;
+		else if (size < SLOB_BREAK2)
+			slob_list = &free_slob_medium;
+		else
+			slob_list = &free_slob_large;
+		set_slob_page_free(sp, slob_list);
+		goto out;
+	}
+
+	/*
+	 * Otherwise the page is already partially free, so find reinsertion
+	 * point.
+	 */
+	sp->units += units;
+
+	if (b < (slob_t *)sp->freelist) {
+		if (b + units == sp->freelist) {
+			units += slob_units(sp->freelist);
+			sp->freelist = slob_next(sp->freelist);
+		}
+		set_slob(b, units, sp->freelist);
+		sp->freelist = b;
+	} else {
+		prev = sp->freelist;
+		next = slob_next(prev);
+		while (b > next) {
+			prev = next;
+			next = slob_next(prev);
+		}
+
+		if (!slob_last(prev) && b + units == next) {
+			units += slob_units(next);
+			set_slob(b, units, slob_next(next));
+		} else
+			set_slob(b, units, next);
+
+		if (prev + slob_units(prev) == b) {
+			units = slob_units(b) + slob_units(prev);
+			set_slob(prev, units, slob_next(b));
+		} else
+			set_slob(prev, slob_units(prev), b);
+	}
+out:
+	spin_unlock_irqrestore(&slob_lock, flags);
+}
+
+/*
+ * End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend.
+ */
+
+static __always_inline void *
+__do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
+{
+	unsigned int *m;
+	int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+	void *ret;
+
+	gfp &= gfp_allowed_mask;
+
+	lockdep_trace_alloc(gfp);
+
+	if (size < PAGE_SIZE - align) {
+		if (!size)
+			return ZERO_SIZE_PTR;
+
+		m = slob_alloc(size + align, gfp, align, node);
+
+		if (!m)
+			return NULL;
+		*m = size;
+		ret = (void *)m + align;
+
+		trace_kmalloc_node(caller, ret,
+				   size, size + align, gfp, node);
+	} else {
+		unsigned int order = get_order(size);
+
+		if (likely(order))
+			gfp |= __GFP_COMP;
+		ret = slob_new_pages(gfp, order, node);
+
+		trace_kmalloc_node(caller, ret,
+				   size, PAGE_SIZE << order, gfp, node);
+	}
+
+	kmemleak_alloc(ret, size, 1, gfp);
+	return ret;
+}
+
+void *__kmalloc(size_t size, gfp_t gfp)
+{
+	return __do_kmalloc_node(size, gfp, NUMA_NO_NODE, _RET_IP_);
+}
+EXPORT_SYMBOL(__kmalloc);
+
+void *__kmalloc_track_caller(size_t size, gfp_t gfp, unsigned long caller)
+{
+	return __do_kmalloc_node(size, gfp, NUMA_NO_NODE, caller);
+}
+
+#ifdef CONFIG_NUMA
+void *__kmalloc_node_track_caller(size_t size, gfp_t gfp,
+					int node, unsigned long caller)
+{
+	return __do_kmalloc_node(size, gfp, node, caller);
+}
+#endif
+
+void kfree(const void *block)
+{
+	struct page *sp;
+
+	trace_kfree(_RET_IP_, block);
+
+	if (unlikely(ZERO_OR_NULL_PTR(block)))
+		return;
+	kmemleak_free(block);
+
+	sp = virt_to_page(block);
+	if (PageSlab(sp)) {
+		int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+		unsigned int *m = (unsigned int *)(block - align);
+		slob_free(m, *m + align);
+	} else
+		__free_pages(sp, compound_order(sp));
+}
+EXPORT_SYMBOL(kfree);
+
+/* can't use ksize for kmem_cache_alloc memory, only kmalloc */
+size_t ksize(const void *block)
+{
+	struct page *sp;
+	int align;
+	unsigned int *m;
+
+	BUG_ON(!block);
+	if (unlikely(block == ZERO_SIZE_PTR))
+		return 0;
+
+	sp = virt_to_page(block);
+	if (unlikely(!PageSlab(sp)))
+		return PAGE_SIZE << compound_order(sp);
+
+	align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+	m = (unsigned int *)(block - align);
+	return SLOB_UNITS(*m) * SLOB_UNIT;
+}
+EXPORT_SYMBOL(ksize);
+
+int __kmem_cache_create(struct kmem_cache *c, unsigned long flags)
+{
+	if (flags & SLAB_DESTROY_BY_RCU) {
+		/* leave room for rcu footer at the end of object */
+		c->size += sizeof(struct slob_rcu);
+	}
+	c->flags = flags;
+	return 0;
+}
+
+static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
+{
+	void *b;
+
+	flags &= gfp_allowed_mask;
+
+	lockdep_trace_alloc(flags);
+
+	if (c->size < PAGE_SIZE) {
+		b = slob_alloc(c->size, flags, c->align, node);
+		trace_kmem_cache_alloc_node(_RET_IP_, b, c->object_size,
+					    SLOB_UNITS(c->size) * SLOB_UNIT,
+					    flags, node);
+	} else {
+		b = slob_new_pages(flags, get_order(c->size), node);
+		trace_kmem_cache_alloc_node(_RET_IP_, b, c->object_size,
+					    PAGE_SIZE << get_order(c->size),
+					    flags, node);
+	}
+
+	if (b && c->ctor)
+		c->ctor(b);
+
+	kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags);
+	return b;
+}
+
+void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+	return slob_alloc_node(cachep, flags, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(kmem_cache_alloc);
+
+#ifdef CONFIG_NUMA
+void *__kmalloc_node(size_t size, gfp_t gfp, int node)
+{
+	return __do_kmalloc_node(size, gfp, node, _RET_IP_);
+}
+EXPORT_SYMBOL(__kmalloc_node);
+
+void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t gfp, int node)
+{
+	return slob_alloc_node(cachep, gfp, node);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_node);
+#endif
+
+static void __kmem_cache_free(void *b, int size)
+{
+	if (size < PAGE_SIZE)
+		slob_free(b, size);
+	else
+		slob_free_pages(b, get_order(size));
+}
+
+static void kmem_rcu_free(struct rcu_head *head)
+{
+	struct slob_rcu *slob_rcu = (struct slob_rcu *)head;
+	void *b = (void *)slob_rcu - (slob_rcu->size - sizeof(struct slob_rcu));
+
+	__kmem_cache_free(b, slob_rcu->size);
+}
+
+void kmem_cache_free(struct kmem_cache *c, void *b)
+{
+	kmemleak_free_recursive(b, c->flags);
+	if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
+		struct slob_rcu *slob_rcu;
+		slob_rcu = b + (c->size - sizeof(struct slob_rcu));
+		slob_rcu->size = c->size;
+		call_rcu(&slob_rcu->head, kmem_rcu_free);
+	} else {
+		__kmem_cache_free(b, c->size);
+	}
+
+	trace_kmem_cache_free(_RET_IP_, b);
+}
+EXPORT_SYMBOL(kmem_cache_free);
+
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
+{
+	__kmem_cache_free_bulk(s, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_free_bulk);
+
+int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
+								void **p)
+{
+	return __kmem_cache_alloc_bulk(s, flags, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_bulk);
+
+int __kmem_cache_shutdown(struct kmem_cache *c)
+{
+	/* No way to check for remaining objects */
+	return 0;
+}
+
+int __kmem_cache_shrink(struct kmem_cache *d, bool deactivate)
+{
+	return 0;
+}
+
+struct kmem_cache kmem_cache_boot = {
+	.name = "kmem_cache",
+	.size = sizeof(struct kmem_cache),
+	.flags = SLAB_PANIC,
+	.align = ARCH_KMALLOC_MINALIGN,
+};
+
+void __init kmem_cache_init(void)
+{
+	kmem_cache = &kmem_cache_boot;
+	slab_state = UP;
+}
+
+void __init kmem_cache_init_late(void)
+{
+	slab_state = FULL;
+}
diff --git a/mm/slub.c b/mm/slub.c
new file mode 100644
index 0000000..4cf3a9c
--- /dev/null
+++ b/mm/slub.c
@@ -0,0 +1,5559 @@
+/*
+ * SLUB: A slab allocator that limits cache line use instead of queuing
+ * objects in per cpu and per node lists.
+ *
+ * The allocator synchronizes using per slab locks or atomic operatios
+ * and only uses a centralized lock to manage a pool of partial slabs.
+ *
+ * (C) 2007 SGI, Christoph Lameter
+ * (C) 2011 Linux Foundation, Christoph Lameter
+ */
+
+#include <linux/mm.h>
+#include <linux/swap.h> /* struct reclaim_state */
+#include <linux/module.h>
+#include <linux/bit_spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include "slab.h"
+#include <linux/proc_fs.h>
+#include <linux/notifier.h>
+#include <linux/seq_file.h>
+#include <linux/kasan.h>
+#include <linux/kmemcheck.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/mempolicy.h>
+#include <linux/ctype.h>
+#include <linux/debugobjects.h>
+#include <linux/kallsyms.h>
+#include <linux/memory.h>
+#include <linux/math64.h>
+#include <linux/fault-inject.h>
+#include <linux/stacktrace.h>
+#include <linux/prefetch.h>
+#include <linux/memcontrol.h>
+
+#include <trace/events/kmem.h>
+
+#include "internal.h"
+
+/*
+ * Lock order:
+ *   1. slab_mutex (Global Mutex)
+ *   2. node->list_lock
+ *   3. slab_lock(page) (Only on some arches and for debugging)
+ *
+ *   slab_mutex
+ *
+ *   The role of the slab_mutex is to protect the list of all the slabs
+ *   and to synchronize major metadata changes to slab cache structures.
+ *
+ *   The slab_lock is only used for debugging and on arches that do not
+ *   have the ability to do a cmpxchg_double. It only protects the second
+ *   double word in the page struct. Meaning
+ *	A. page->freelist	-> List of object free in a page
+ *	B. page->counters	-> Counters of objects
+ *	C. page->frozen		-> frozen state
+ *
+ *   If a slab is frozen then it is exempt from list management. It is not
+ *   on any list. The processor that froze the slab is the one who can
+ *   perform list operations on the page. Other processors may put objects
+ *   onto the freelist but the processor that froze the slab is the only
+ *   one that can retrieve the objects from the page's freelist.
+ *
+ *   The list_lock protects the partial and full list on each node and
+ *   the partial slab counter. If taken then no new slabs may be added or
+ *   removed from the lists nor make the number of partial slabs be modified.
+ *   (Note that the total number of slabs is an atomic value that may be
+ *   modified without taking the list lock).
+ *
+ *   The list_lock is a centralized lock and thus we avoid taking it as
+ *   much as possible. As long as SLUB does not have to handle partial
+ *   slabs, operations can continue without any centralized lock. F.e.
+ *   allocating a long series of objects that fill up slabs does not require
+ *   the list lock.
+ *   Interrupts are disabled during allocation and deallocation in order to
+ *   make the slab allocator safe to use in the context of an irq. In addition
+ *   interrupts are disabled to ensure that the processor does not change
+ *   while handling per_cpu slabs, due to kernel preemption.
+ *
+ * SLUB assigns one slab for allocation to each processor.
+ * Allocations only occur from these slabs called cpu slabs.
+ *
+ * Slabs with free elements are kept on a partial list and during regular
+ * operations no list for full slabs is used. If an object in a full slab is
+ * freed then the slab will show up again on the partial lists.
+ * We track full slabs for debugging purposes though because otherwise we
+ * cannot scan all objects.
+ *
+ * Slabs are freed when they become empty. Teardown and setup is
+ * minimal so we rely on the page allocators per cpu caches for
+ * fast frees and allocs.
+ *
+ * Overloading of page flags that are otherwise used for LRU management.
+ *
+ * PageActive 		The slab is frozen and exempt from list processing.
+ * 			This means that the slab is dedicated to a purpose
+ * 			such as satisfying allocations for a specific
+ * 			processor. Objects may be freed in the slab while
+ * 			it is frozen but slab_free will then skip the usual
+ * 			list operations. It is up to the processor holding
+ * 			the slab to integrate the slab into the slab lists
+ * 			when the slab is no longer needed.
+ *
+ * 			One use of this flag is to mark slabs that are
+ * 			used for allocations. Then such a slab becomes a cpu
+ * 			slab. The cpu slab may be equipped with an additional
+ * 			freelist that allows lockless access to
+ * 			free objects in addition to the regular freelist
+ * 			that requires the slab lock.
+ *
+ * PageError		Slab requires special handling due to debug
+ * 			options set. This moves	slab handling out of
+ * 			the fast path and disables lockless freelists.
+ */
+
+static inline int kmem_cache_debug(struct kmem_cache *s)
+{
+#ifdef CONFIG_SLUB_DEBUG
+	return unlikely(s->flags & SLAB_DEBUG_FLAGS);
+#else
+	return 0;
+#endif
+}
+
+static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
+{
+#ifdef CONFIG_SLUB_CPU_PARTIAL
+	return !kmem_cache_debug(s);
+#else
+	return false;
+#endif
+}
+
+/*
+ * Issues still to be resolved:
+ *
+ * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
+ *
+ * - Variable sizing of the per node arrays
+ */
+
+/* Enable to test recovery from slab corruption on boot */
+#undef SLUB_RESILIENCY_TEST
+
+/* Enable to log cmpxchg failures */
+#undef SLUB_DEBUG_CMPXCHG
+
+/*
+ * Mininum number of partial slabs. These will be left on the partial
+ * lists even if they are empty. kmem_cache_shrink may reclaim them.
+ */
+#define MIN_PARTIAL 5
+
+/*
+ * Maximum number of desirable partial slabs.
+ * The existence of more partial slabs makes kmem_cache_shrink
+ * sort the partial list by the number of objects in use.
+ */
+#define MAX_PARTIAL 10
+
+#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
+				SLAB_POISON | SLAB_STORE_USER)
+
+/*
+ * Debugging flags that require metadata to be stored in the slab.  These get
+ * disabled when slub_debug=O is used and a cache's min order increases with
+ * metadata.
+ */
+#define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
+
+#define OO_SHIFT	16
+#define OO_MASK		((1 << OO_SHIFT) - 1)
+#define MAX_OBJS_PER_PAGE	32767 /* since page.objects is u15 */
+
+/* Internal SLUB flags */
+#define __OBJECT_POISON		0x80000000UL /* Poison object */
+#define __CMPXCHG_DOUBLE	0x40000000UL /* Use cmpxchg_double */
+
+#ifdef CONFIG_SMP
+static struct notifier_block slab_notifier;
+#endif
+
+/*
+ * Tracking user of a slab.
+ */
+#define TRACK_ADDRS_COUNT 16
+struct track {
+	unsigned long addr;	/* Called from address */
+#ifdef CONFIG_STACKTRACE
+	unsigned long addrs[TRACK_ADDRS_COUNT];	/* Called from address */
+#endif
+	int cpu;		/* Was running on cpu */
+	int pid;		/* Pid context */
+	unsigned long when;	/* When did the operation occur */
+};
+
+enum track_item { TRACK_ALLOC, TRACK_FREE };
+
+#ifdef CONFIG_SYSFS
+static int sysfs_slab_add(struct kmem_cache *);
+static int sysfs_slab_alias(struct kmem_cache *, const char *);
+static void memcg_propagate_slab_attrs(struct kmem_cache *s);
+#else
+static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
+static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
+							{ return 0; }
+static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
+#endif
+
+static inline void stat(const struct kmem_cache *s, enum stat_item si)
+{
+#ifdef CONFIG_SLUB_STATS
+	/*
+	 * The rmw is racy on a preemptible kernel but this is acceptable, so
+	 * avoid this_cpu_add()'s irq-disable overhead.
+	 */
+	raw_cpu_inc(s->cpu_slab->stat[si]);
+#endif
+}
+
+/********************************************************************
+ * 			Core slab cache functions
+ *******************************************************************/
+
+/* Verify that a pointer has an address that is valid within a slab page */
+static inline int check_valid_pointer(struct kmem_cache *s,
+				struct page *page, const void *object)
+{
+	void *base;
+
+	if (!object)
+		return 1;
+
+	base = page_address(page);
+	if (object < base || object >= base + page->objects * s->size ||
+		(object - base) % s->size) {
+		return 0;
+	}
+
+	return 1;
+}
+
+static inline void *get_freepointer(struct kmem_cache *s, void *object)
+{
+	return *(void **)(object + s->offset);
+}
+
+static void prefetch_freepointer(const struct kmem_cache *s, void *object)
+{
+	prefetch(object + s->offset);
+}
+
+static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
+{
+	void *p;
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+	probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p));
+#else
+	p = get_freepointer(s, object);
+#endif
+	return p;
+}
+
+static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
+{
+	*(void **)(object + s->offset) = fp;
+}
+
+/* Loop over all objects in a slab */
+#define for_each_object(__p, __s, __addr, __objects) \
+	for (__p = (__addr); __p < (__addr) + (__objects) * (__s)->size;\
+			__p += (__s)->size)
+
+#define for_each_object_idx(__p, __idx, __s, __addr, __objects) \
+	for (__p = (__addr), __idx = 1; __idx <= __objects;\
+			__p += (__s)->size, __idx++)
+
+/* Determine object index from a given position */
+static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
+{
+	return (p - addr) / s->size;
+}
+
+static inline size_t slab_ksize(const struct kmem_cache *s)
+{
+#ifdef CONFIG_SLUB_DEBUG
+	/*
+	 * Debugging requires use of the padding between object
+	 * and whatever may come after it.
+	 */
+	if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
+		return s->object_size;
+
+#endif
+	/*
+	 * If we have the need to store the freelist pointer
+	 * back there or track user information then we can
+	 * only use the space before that information.
+	 */
+	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
+		return s->inuse;
+	/*
+	 * Else we can use all the padding etc for the allocation
+	 */
+	return s->size;
+}
+
+static inline int order_objects(int order, unsigned long size, int reserved)
+{
+	return ((PAGE_SIZE << order) - reserved) / size;
+}
+
+static inline struct kmem_cache_order_objects oo_make(int order,
+		unsigned long size, int reserved)
+{
+	struct kmem_cache_order_objects x = {
+		(order << OO_SHIFT) + order_objects(order, size, reserved)
+	};
+
+	return x;
+}
+
+static inline int oo_order(struct kmem_cache_order_objects x)
+{
+	return x.x >> OO_SHIFT;
+}
+
+static inline int oo_objects(struct kmem_cache_order_objects x)
+{
+	return x.x & OO_MASK;
+}
+
+/*
+ * Per slab locking using the pagelock
+ */
+static __always_inline void slab_lock(struct page *page)
+{
+	bit_spin_lock(PG_locked, &page->flags);
+}
+
+static __always_inline void slab_unlock(struct page *page)
+{
+	__bit_spin_unlock(PG_locked, &page->flags);
+}
+
+static inline void set_page_slub_counters(struct page *page, unsigned long counters_new)
+{
+	struct page tmp;
+	tmp.counters = counters_new;
+	/*
+	 * page->counters can cover frozen/inuse/objects as well
+	 * as page->_count.  If we assign to ->counters directly
+	 * we run the risk of losing updates to page->_count, so
+	 * be careful and only assign to the fields we need.
+	 */
+	page->frozen  = tmp.frozen;
+	page->inuse   = tmp.inuse;
+	page->objects = tmp.objects;
+}
+
+/* Interrupts must be disabled (for the fallback code to work right) */
+static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
+		void *freelist_old, unsigned long counters_old,
+		void *freelist_new, unsigned long counters_new,
+		const char *n)
+{
+	VM_BUG_ON(!irqs_disabled());
+#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
+    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
+	if (s->flags & __CMPXCHG_DOUBLE) {
+		if (cmpxchg_double(&page->freelist, &page->counters,
+				   freelist_old, counters_old,
+				   freelist_new, counters_new))
+			return true;
+	} else
+#endif
+	{
+		slab_lock(page);
+		if (page->freelist == freelist_old &&
+					page->counters == counters_old) {
+			page->freelist = freelist_new;
+			set_page_slub_counters(page, counters_new);
+			slab_unlock(page);
+			return true;
+		}
+		slab_unlock(page);
+	}
+
+	cpu_relax();
+	stat(s, CMPXCHG_DOUBLE_FAIL);
+
+#ifdef SLUB_DEBUG_CMPXCHG
+	pr_info("%s %s: cmpxchg double redo ", n, s->name);
+#endif
+
+	return false;
+}
+
+static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
+		void *freelist_old, unsigned long counters_old,
+		void *freelist_new, unsigned long counters_new,
+		const char *n)
+{
+#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
+    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
+	if (s->flags & __CMPXCHG_DOUBLE) {
+		if (cmpxchg_double(&page->freelist, &page->counters,
+				   freelist_old, counters_old,
+				   freelist_new, counters_new))
+			return true;
+	} else
+#endif
+	{
+		unsigned long flags;
+
+		local_irq_save(flags);
+		slab_lock(page);
+		if (page->freelist == freelist_old &&
+					page->counters == counters_old) {
+			page->freelist = freelist_new;
+			set_page_slub_counters(page, counters_new);
+			slab_unlock(page);
+			local_irq_restore(flags);
+			return true;
+		}
+		slab_unlock(page);
+		local_irq_restore(flags);
+	}
+
+	cpu_relax();
+	stat(s, CMPXCHG_DOUBLE_FAIL);
+
+#ifdef SLUB_DEBUG_CMPXCHG
+	pr_info("%s %s: cmpxchg double redo ", n, s->name);
+#endif
+
+	return false;
+}
+
+#ifdef CONFIG_SLUB_DEBUG
+/*
+ * Determine a map of object in use on a page.
+ *
+ * Node listlock must be held to guarantee that the page does
+ * not vanish from under us.
+ */
+static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
+{
+	void *p;
+	void *addr = page_address(page);
+
+	for (p = page->freelist; p; p = get_freepointer(s, p))
+		set_bit(slab_index(p, s, addr), map);
+}
+
+/*
+ * Debug settings:
+ */
+#if defined(CONFIG_SLUB_DEBUG_ON)
+static int slub_debug = DEBUG_DEFAULT_FLAGS;
+#elif defined(CONFIG_KASAN)
+static int slub_debug = SLAB_STORE_USER;
+#else
+static int slub_debug;
+#endif
+
+static char *slub_debug_slabs;
+static int disable_higher_order_debug;
+
+/*
+ * slub is about to manipulate internal object metadata.  This memory lies
+ * outside the range of the allocated object, so accessing it would normally
+ * be reported by kasan as a bounds error.  metadata_access_enable() is used
+ * to tell kasan that these accesses are OK.
+ */
+static inline void metadata_access_enable(void)
+{
+	kasan_disable_current();
+}
+
+static inline void metadata_access_disable(void)
+{
+	kasan_enable_current();
+}
+
+/*
+ * Object debugging
+ */
+static void print_section(char *text, u8 *addr, unsigned int length)
+{
+	metadata_access_enable();
+	print_hex_dump(KERN_ERR, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
+			length, 1);
+	metadata_access_disable();
+}
+
+static struct track *get_track(struct kmem_cache *s, void *object,
+	enum track_item alloc)
+{
+	struct track *p;
+
+	if (s->offset)
+		p = object + s->offset + sizeof(void *);
+	else
+		p = object + s->inuse;
+
+	return p + alloc;
+}
+
+static void set_track(struct kmem_cache *s, void *object,
+			enum track_item alloc, unsigned long addr)
+{
+	struct track *p = get_track(s, object, alloc);
+
+	if (addr) {
+#ifdef CONFIG_STACKTRACE
+		struct stack_trace trace;
+		int i;
+
+		trace.nr_entries = 0;
+		trace.max_entries = TRACK_ADDRS_COUNT;
+		trace.entries = p->addrs;
+		trace.skip = 3;
+		metadata_access_enable();
+		save_stack_trace(&trace);
+		metadata_access_disable();
+
+		/* See rant in lockdep.c */
+		if (trace.nr_entries != 0 &&
+		    trace.entries[trace.nr_entries - 1] == ULONG_MAX)
+			trace.nr_entries--;
+
+		for (i = trace.nr_entries; i < TRACK_ADDRS_COUNT; i++)
+			p->addrs[i] = 0;
+#endif
+		p->addr = addr;
+		p->cpu = smp_processor_id();
+		p->pid = current->pid;
+		p->when = jiffies;
+	} else
+		memset(p, 0, sizeof(struct track));
+}
+
+static void init_tracking(struct kmem_cache *s, void *object)
+{
+	if (!(s->flags & SLAB_STORE_USER))
+		return;
+
+	set_track(s, object, TRACK_FREE, 0UL);
+	set_track(s, object, TRACK_ALLOC, 0UL);
+}
+
+static void print_track(const char *s, struct track *t)
+{
+	if (!t->addr)
+		return;
+
+	pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
+	       s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid);
+#ifdef CONFIG_STACKTRACE
+	{
+		int i;
+		for (i = 0; i < TRACK_ADDRS_COUNT; i++)
+			if (t->addrs[i])
+				pr_err("\t%pS\n", (void *)t->addrs[i]);
+			else
+				break;
+	}
+#endif
+}
+
+static void print_tracking(struct kmem_cache *s, void *object)
+{
+	if (!(s->flags & SLAB_STORE_USER))
+		return;
+
+	print_track("Allocated", get_track(s, object, TRACK_ALLOC));
+	print_track("Freed", get_track(s, object, TRACK_FREE));
+}
+
+static void print_page_info(struct page *page)
+{
+	pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n",
+	       page, page->objects, page->inuse, page->freelist, page->flags);
+
+}
+
+static void slab_bug(struct kmem_cache *s, char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	pr_err("=============================================================================\n");
+	pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
+	pr_err("-----------------------------------------------------------------------------\n\n");
+
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+	va_end(args);
+}
+
+static void slab_fix(struct kmem_cache *s, char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	pr_err("FIX %s: %pV\n", s->name, &vaf);
+	va_end(args);
+}
+
+static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
+{
+	unsigned int off;	/* Offset of last byte */
+	u8 *addr = page_address(page);
+
+	print_tracking(s, p);
+
+	print_page_info(page);
+
+	pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
+	       p, p - addr, get_freepointer(s, p));
+
+	if (p > addr + 16)
+		print_section("Bytes b4 ", p - 16, 16);
+
+	print_section("Object ", p, min_t(unsigned long, s->object_size,
+				PAGE_SIZE));
+	if (s->flags & SLAB_RED_ZONE)
+		print_section("Redzone ", p + s->object_size,
+			s->inuse - s->object_size);
+
+	if (s->offset)
+		off = s->offset + sizeof(void *);
+	else
+		off = s->inuse;
+
+	if (s->flags & SLAB_STORE_USER)
+		off += 2 * sizeof(struct track);
+
+	if (off != s->size)
+		/* Beginning of the filler is the free pointer */
+		print_section("Padding ", p + off, s->size - off);
+
+	dump_stack();
+}
+
+void object_err(struct kmem_cache *s, struct page *page,
+			u8 *object, char *reason)
+{
+	slab_bug(s, "%s", reason);
+	print_trailer(s, page, object);
+}
+
+static void slab_err(struct kmem_cache *s, struct page *page,
+			const char *fmt, ...)
+{
+	va_list args;
+	char buf[100];
+
+	va_start(args, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, args);
+	va_end(args);
+	slab_bug(s, "%s", buf);
+	print_page_info(page);
+	dump_stack();
+}
+
+static void init_object(struct kmem_cache *s, void *object, u8 val)
+{
+	u8 *p = object;
+
+	if (s->flags & __OBJECT_POISON) {
+		memset(p, POISON_FREE, s->object_size - 1);
+		p[s->object_size - 1] = POISON_END;
+	}
+
+	if (s->flags & SLAB_RED_ZONE)
+		memset(p + s->object_size, val, s->inuse - s->object_size);
+}
+
+static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
+						void *from, void *to)
+{
+	slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
+	memset(from, data, to - from);
+}
+
+static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
+			u8 *object, char *what,
+			u8 *start, unsigned int value, unsigned int bytes)
+{
+	u8 *fault;
+	u8 *end;
+
+	metadata_access_enable();
+	fault = memchr_inv(start, value, bytes);
+	metadata_access_disable();
+	if (!fault)
+		return 1;
+
+	end = start + bytes;
+	while (end > fault && end[-1] == value)
+		end--;
+
+	slab_bug(s, "%s overwritten", what);
+	pr_err("INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n",
+					fault, end - 1, fault[0], value);
+	print_trailer(s, page, object);
+
+	restore_bytes(s, what, value, fault, end);
+	return 0;
+}
+
+/*
+ * Object layout:
+ *
+ * object address
+ * 	Bytes of the object to be managed.
+ * 	If the freepointer may overlay the object then the free
+ * 	pointer is the first word of the object.
+ *
+ * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
+ * 	0xa5 (POISON_END)
+ *
+ * object + s->object_size
+ * 	Padding to reach word boundary. This is also used for Redzoning.
+ * 	Padding is extended by another word if Redzoning is enabled and
+ * 	object_size == inuse.
+ *
+ * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
+ * 	0xcc (RED_ACTIVE) for objects in use.
+ *
+ * object + s->inuse
+ * 	Meta data starts here.
+ *
+ * 	A. Free pointer (if we cannot overwrite object on free)
+ * 	B. Tracking data for SLAB_STORE_USER
+ * 	C. Padding to reach required alignment boundary or at mininum
+ * 		one word if debugging is on to be able to detect writes
+ * 		before the word boundary.
+ *
+ *	Padding is done using 0x5a (POISON_INUSE)
+ *
+ * object + s->size
+ * 	Nothing is used beyond s->size.
+ *
+ * If slabcaches are merged then the object_size and inuse boundaries are mostly
+ * ignored. And therefore no slab options that rely on these boundaries
+ * may be used with merged slabcaches.
+ */
+
+static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
+{
+	unsigned long off = s->inuse;	/* The end of info */
+
+	if (s->offset)
+		/* Freepointer is placed after the object. */
+		off += sizeof(void *);
+
+	if (s->flags & SLAB_STORE_USER)
+		/* We also have user information there */
+		off += 2 * sizeof(struct track);
+
+	if (s->size == off)
+		return 1;
+
+	return check_bytes_and_report(s, page, p, "Object padding",
+				p + off, POISON_INUSE, s->size - off);
+}
+
+/* Check the pad bytes at the end of a slab page */
+static int slab_pad_check(struct kmem_cache *s, struct page *page)
+{
+	u8 *start;
+	u8 *fault;
+	u8 *end;
+	int length;
+	int remainder;
+
+	if (!(s->flags & SLAB_POISON))
+		return 1;
+
+	start = page_address(page);
+	length = (PAGE_SIZE << compound_order(page)) - s->reserved;
+	end = start + length;
+	remainder = length % s->size;
+	if (!remainder)
+		return 1;
+
+	metadata_access_enable();
+	fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
+	metadata_access_disable();
+	if (!fault)
+		return 1;
+	while (end > fault && end[-1] == POISON_INUSE)
+		end--;
+
+	slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
+	print_section("Padding ", end - remainder, remainder);
+
+	restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
+	return 0;
+}
+
+static int check_object(struct kmem_cache *s, struct page *page,
+					void *object, u8 val)
+{
+	u8 *p = object;
+	u8 *endobject = object + s->object_size;
+
+	if (s->flags & SLAB_RED_ZONE) {
+		if (!check_bytes_and_report(s, page, object, "Redzone",
+			endobject, val, s->inuse - s->object_size))
+			return 0;
+	} else {
+		if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
+			check_bytes_and_report(s, page, p, "Alignment padding",
+				endobject, POISON_INUSE,
+				s->inuse - s->object_size);
+		}
+	}
+
+	if (s->flags & SLAB_POISON) {
+		if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
+			(!check_bytes_and_report(s, page, p, "Poison", p,
+					POISON_FREE, s->object_size - 1) ||
+			 !check_bytes_and_report(s, page, p, "Poison",
+				p + s->object_size - 1, POISON_END, 1)))
+			return 0;
+		/*
+		 * check_pad_bytes cleans up on its own.
+		 */
+		check_pad_bytes(s, page, p);
+	}
+
+	if (!s->offset && val == SLUB_RED_ACTIVE)
+		/*
+		 * Object and freepointer overlap. Cannot check
+		 * freepointer while object is allocated.
+		 */
+		return 1;
+
+	/* Check free pointer validity */
+	if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+		object_err(s, page, p, "Freepointer corrupt");
+		/*
+		 * No choice but to zap it and thus lose the remainder
+		 * of the free objects in this slab. May cause
+		 * another error because the object count is now wrong.
+		 */
+		set_freepointer(s, p, NULL);
+		return 0;
+	}
+	return 1;
+}
+
+static int check_slab(struct kmem_cache *s, struct page *page)
+{
+	int maxobj;
+
+	VM_BUG_ON(!irqs_disabled());
+
+	if (!PageSlab(page)) {
+		slab_err(s, page, "Not a valid slab page");
+		return 0;
+	}
+
+	maxobj = order_objects(compound_order(page), s->size, s->reserved);
+	if (page->objects > maxobj) {
+		slab_err(s, page, "objects %u > max %u",
+			page->objects, maxobj);
+		return 0;
+	}
+	if (page->inuse > page->objects) {
+		slab_err(s, page, "inuse %u > max %u",
+			page->inuse, page->objects);
+		return 0;
+	}
+	/* Slab_pad_check fixes things up after itself */
+	slab_pad_check(s, page);
+	return 1;
+}
+
+/*
+ * Determine if a certain object on a page is on the freelist. Must hold the
+ * slab lock to guarantee that the chains are in a consistent state.
+ */
+static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
+{
+	int nr = 0;
+	void *fp;
+	void *object = NULL;
+	int max_objects;
+
+	fp = page->freelist;
+	while (fp && nr <= page->objects) {
+		if (fp == search)
+			return 1;
+		if (!check_valid_pointer(s, page, fp)) {
+			if (object) {
+				object_err(s, page, object,
+					"Freechain corrupt");
+				set_freepointer(s, object, NULL);
+			} else {
+				slab_err(s, page, "Freepointer corrupt");
+				page->freelist = NULL;
+				page->inuse = page->objects;
+				slab_fix(s, "Freelist cleared");
+				return 0;
+			}
+			break;
+		}
+		object = fp;
+		fp = get_freepointer(s, object);
+		nr++;
+	}
+
+	max_objects = order_objects(compound_order(page), s->size, s->reserved);
+	if (max_objects > MAX_OBJS_PER_PAGE)
+		max_objects = MAX_OBJS_PER_PAGE;
+
+	if (page->objects != max_objects) {
+		slab_err(s, page, "Wrong number of objects. Found %d but "
+			"should be %d", page->objects, max_objects);
+		page->objects = max_objects;
+		slab_fix(s, "Number of objects adjusted.");
+	}
+	if (page->inuse != page->objects - nr) {
+		slab_err(s, page, "Wrong object count. Counter is %d but "
+			"counted were %d", page->inuse, page->objects - nr);
+		page->inuse = page->objects - nr;
+		slab_fix(s, "Object count adjusted.");
+	}
+	return search == NULL;
+}
+
+static void trace(struct kmem_cache *s, struct page *page, void *object,
+								int alloc)
+{
+	if (s->flags & SLAB_TRACE) {
+		pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
+			s->name,
+			alloc ? "alloc" : "free",
+			object, page->inuse,
+			page->freelist);
+
+		if (!alloc)
+			print_section("Object ", (void *)object,
+					s->object_size);
+
+		dump_stack();
+	}
+}
+
+/*
+ * Tracking of fully allocated slabs for debugging purposes.
+ */
+static void add_full(struct kmem_cache *s,
+	struct kmem_cache_node *n, struct page *page)
+{
+	if (!(s->flags & SLAB_STORE_USER))
+		return;
+
+	lockdep_assert_held(&n->list_lock);
+	list_add(&page->lru, &n->full);
+}
+
+static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page)
+{
+	if (!(s->flags & SLAB_STORE_USER))
+		return;
+
+	lockdep_assert_held(&n->list_lock);
+	list_del(&page->lru);
+}
+
+/* Tracking of the number of slabs for debugging purposes */
+static inline unsigned long slabs_node(struct kmem_cache *s, int node)
+{
+	struct kmem_cache_node *n = get_node(s, node);
+
+	return atomic_long_read(&n->nr_slabs);
+}
+
+static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
+{
+	return atomic_long_read(&n->nr_slabs);
+}
+
+static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
+{
+	struct kmem_cache_node *n = get_node(s, node);
+
+	/*
+	 * May be called early in order to allocate a slab for the
+	 * kmem_cache_node structure. Solve the chicken-egg
+	 * dilemma by deferring the increment of the count during
+	 * bootstrap (see early_kmem_cache_node_alloc).
+	 */
+	if (likely(n)) {
+		atomic_long_inc(&n->nr_slabs);
+		atomic_long_add(objects, &n->total_objects);
+	}
+}
+static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
+{
+	struct kmem_cache_node *n = get_node(s, node);
+
+	atomic_long_dec(&n->nr_slabs);
+	atomic_long_sub(objects, &n->total_objects);
+}
+
+/* Object debug checks for alloc/free paths */
+static void setup_object_debug(struct kmem_cache *s, struct page *page,
+								void *object)
+{
+	if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
+		return;
+
+	init_object(s, object, SLUB_RED_INACTIVE);
+	init_tracking(s, object);
+}
+
+static noinline int alloc_debug_processing(struct kmem_cache *s,
+					struct page *page,
+					void *object, unsigned long addr)
+{
+	if (!check_slab(s, page))
+		goto bad;
+
+	if (!check_valid_pointer(s, page, object)) {
+		object_err(s, page, object, "Freelist Pointer check fails");
+		goto bad;
+	}
+
+	if (!check_object(s, page, object, SLUB_RED_INACTIVE))
+		goto bad;
+
+	/* Success perform special debug activities for allocs */
+	if (s->flags & SLAB_STORE_USER)
+		set_track(s, object, TRACK_ALLOC, addr);
+	trace(s, page, object, 1);
+	init_object(s, object, SLUB_RED_ACTIVE);
+	return 1;
+
+bad:
+	if (PageSlab(page)) {
+		/*
+		 * If this is a slab page then lets do the best we can
+		 * to avoid issues in the future. Marking all objects
+		 * as used avoids touching the remaining objects.
+		 */
+		slab_fix(s, "Marking all objects used");
+		page->inuse = page->objects;
+		page->freelist = NULL;
+	}
+	return 0;
+}
+
+/* Supports checking bulk free of a constructed freelist */
+static noinline struct kmem_cache_node *free_debug_processing(
+	struct kmem_cache *s, struct page *page,
+	void *head, void *tail, int bulk_cnt,
+	unsigned long addr, unsigned long *flags)
+{
+	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+	void *object = head;
+	int cnt = 0;
+
+	spin_lock_irqsave(&n->list_lock, *flags);
+	slab_lock(page);
+
+	if (!check_slab(s, page))
+		goto fail;
+
+next_object:
+	cnt++;
+
+	if (!check_valid_pointer(s, page, object)) {
+		slab_err(s, page, "Invalid object pointer 0x%p", object);
+		goto fail;
+	}
+
+	if (on_freelist(s, page, object)) {
+		object_err(s, page, object, "Object already free");
+		goto fail;
+	}
+
+	if (!check_object(s, page, object, SLUB_RED_ACTIVE))
+		goto out;
+
+	if (unlikely(s != page->slab_cache)) {
+		if (!PageSlab(page)) {
+			slab_err(s, page, "Attempt to free object(0x%p) "
+				"outside of slab", object);
+		} else if (!page->slab_cache) {
+			pr_err("SLUB <none>: no slab for object 0x%p.\n",
+			       object);
+			dump_stack();
+		} else
+			object_err(s, page, object,
+					"page slab pointer corrupt.");
+		goto fail;
+	}
+
+	if (s->flags & SLAB_STORE_USER)
+		set_track(s, object, TRACK_FREE, addr);
+	trace(s, page, object, 0);
+	/* Freepointer not overwritten by init_object(), SLAB_POISON moved it */
+	init_object(s, object, SLUB_RED_INACTIVE);
+
+	/* Reached end of constructed freelist yet? */
+	if (object != tail) {
+		object = get_freepointer(s, object);
+		goto next_object;
+	}
+out:
+	if (cnt != bulk_cnt)
+		slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n",
+			 bulk_cnt, cnt);
+
+	slab_unlock(page);
+	/*
+	 * Keep node_lock to preserve integrity
+	 * until the object is actually freed
+	 */
+	return n;
+
+fail:
+	slab_unlock(page);
+	spin_unlock_irqrestore(&n->list_lock, *flags);
+	slab_fix(s, "Object at 0x%p not freed", object);
+	return NULL;
+}
+
+static int __init setup_slub_debug(char *str)
+{
+	slub_debug = DEBUG_DEFAULT_FLAGS;
+	if (*str++ != '=' || !*str)
+		/*
+		 * No options specified. Switch on full debugging.
+		 */
+		goto out;
+
+	if (*str == ',')
+		/*
+		 * No options but restriction on slabs. This means full
+		 * debugging for slabs matching a pattern.
+		 */
+		goto check_slabs;
+
+	slub_debug = 0;
+	if (*str == '-')
+		/*
+		 * Switch off all debugging measures.
+		 */
+		goto out;
+
+	/*
+	 * Determine which debug features should be switched on
+	 */
+	for (; *str && *str != ','; str++) {
+		switch (tolower(*str)) {
+		case 'f':
+			slub_debug |= SLAB_DEBUG_FREE;
+			break;
+		case 'z':
+			slub_debug |= SLAB_RED_ZONE;
+			break;
+		case 'p':
+			slub_debug |= SLAB_POISON;
+			break;
+		case 'u':
+			slub_debug |= SLAB_STORE_USER;
+			break;
+		case 't':
+			slub_debug |= SLAB_TRACE;
+			break;
+		case 'a':
+			slub_debug |= SLAB_FAILSLAB;
+			break;
+		case 'o':
+			/*
+			 * Avoid enabling debugging on caches if its minimum
+			 * order would increase as a result.
+			 */
+			disable_higher_order_debug = 1;
+			break;
+		default:
+			pr_err("slub_debug option '%c' unknown. skipped\n",
+			       *str);
+		}
+	}
+
+check_slabs:
+	if (*str == ',')
+		slub_debug_slabs = str + 1;
+out:
+	return 1;
+}
+
+__setup("slub_debug", setup_slub_debug);
+
+unsigned long kmem_cache_flags(unsigned long object_size,
+	unsigned long flags, const char *name,
+	void (*ctor)(void *))
+{
+	/*
+	 * Enable debugging if selected on the kernel commandline.
+	 */
+	if (slub_debug && (!slub_debug_slabs || (name &&
+		!strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)))))
+		flags |= slub_debug;
+
+	return flags;
+}
+#else /* !CONFIG_SLUB_DEBUG */
+static inline void setup_object_debug(struct kmem_cache *s,
+			struct page *page, void *object) {}
+
+static inline int alloc_debug_processing(struct kmem_cache *s,
+	struct page *page, void *object, unsigned long addr) { return 0; }
+
+static inline struct kmem_cache_node *free_debug_processing(
+	struct kmem_cache *s, struct page *page,
+	void *head, void *tail, int bulk_cnt,
+	unsigned long addr, unsigned long *flags) { return NULL; }
+
+static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
+			{ return 1; }
+static inline int check_object(struct kmem_cache *s, struct page *page,
+			void *object, u8 val) { return 1; }
+static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
+					struct page *page) {}
+static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
+					struct page *page) {}
+unsigned long kmem_cache_flags(unsigned long object_size,
+	unsigned long flags, const char *name,
+	void (*ctor)(void *))
+{
+	return flags;
+}
+#define slub_debug 0
+
+#define disable_higher_order_debug 0
+
+static inline unsigned long slabs_node(struct kmem_cache *s, int node)
+							{ return 0; }
+static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
+							{ return 0; }
+static inline void inc_slabs_node(struct kmem_cache *s, int node,
+							int objects) {}
+static inline void dec_slabs_node(struct kmem_cache *s, int node,
+							int objects) {}
+
+#endif /* CONFIG_SLUB_DEBUG */
+
+/*
+ * Hooks for other subsystems that check memory allocations. In a typical
+ * production configuration these hooks all should produce no code at all.
+ */
+static inline void kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
+{
+	kmemleak_alloc(ptr, size, 1, flags);
+	kasan_kmalloc_large(ptr, size);
+}
+
+static inline void kfree_hook(const void *x)
+{
+	kmemleak_free(x);
+	kasan_kfree_large(x);
+}
+
+static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
+						     gfp_t flags)
+{
+	flags &= gfp_allowed_mask;
+	lockdep_trace_alloc(flags);
+	might_sleep_if(gfpflags_allow_blocking(flags));
+
+	if (should_failslab(s->object_size, flags, s->flags))
+		return NULL;
+
+	return memcg_kmem_get_cache(s, flags);
+}
+
+static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
+					size_t size, void **p)
+{
+	size_t i;
+
+	flags &= gfp_allowed_mask;
+	for (i = 0; i < size; i++) {
+		void *object = p[i];
+
+		kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
+		kmemleak_alloc_recursive(object, s->object_size, 1,
+					 s->flags, flags);
+		kasan_slab_alloc(s, object);
+	}
+	memcg_kmem_put_cache(s);
+}
+
+static inline void slab_free_hook(struct kmem_cache *s, void *x)
+{
+	kmemleak_free_recursive(x, s->flags);
+
+	/*
+	 * Trouble is that we may no longer disable interrupts in the fast path
+	 * So in order to make the debug calls that expect irqs to be
+	 * disabled we need to disable interrupts temporarily.
+	 */
+#if defined(CONFIG_KMEMCHECK) || defined(CONFIG_LOCKDEP)
+	{
+		unsigned long flags;
+
+		local_irq_save(flags);
+		kmemcheck_slab_free(s, x, s->object_size);
+		debug_check_no_locks_freed(x, s->object_size);
+		local_irq_restore(flags);
+	}
+#endif
+	if (!(s->flags & SLAB_DEBUG_OBJECTS))
+		debug_check_no_obj_freed(x, s->object_size);
+
+	kasan_slab_free(s, x);
+}
+
+static inline void slab_free_freelist_hook(struct kmem_cache *s,
+					   void *head, void *tail)
+{
+/*
+ * Compiler cannot detect this function can be removed if slab_free_hook()
+ * evaluates to nothing.  Thus, catch all relevant config debug options here.
+ */
+#if defined(CONFIG_KMEMCHECK) ||		\
+	defined(CONFIG_LOCKDEP)	||		\
+	defined(CONFIG_DEBUG_KMEMLEAK) ||	\
+	defined(CONFIG_DEBUG_OBJECTS_FREE) ||	\
+	defined(CONFIG_KASAN)
+
+	void *object = head;
+	void *tail_obj = tail ? : head;
+
+	do {
+		slab_free_hook(s, object);
+	} while ((object != tail_obj) &&
+		 (object = get_freepointer(s, object)));
+#endif
+}
+
+static void setup_object(struct kmem_cache *s, struct page *page,
+				void *object)
+{
+	setup_object_debug(s, page, object);
+	if (unlikely(s->ctor)) {
+		kasan_unpoison_object_data(s, object);
+		s->ctor(object);
+		kasan_poison_object_data(s, object);
+	}
+}
+
+/*
+ * Slab allocation and freeing
+ */
+static inline struct page *alloc_slab_page(struct kmem_cache *s,
+		gfp_t flags, int node, struct kmem_cache_order_objects oo)
+{
+	struct page *page;
+	int order = oo_order(oo);
+
+	flags |= __GFP_NOTRACK;
+
+	if (node == NUMA_NO_NODE)
+		page = alloc_pages(flags, order);
+	else
+		page = __alloc_pages_node(node, flags, order);
+
+	if (page && memcg_charge_slab(page, flags, order, s)) {
+		__free_pages(page, order);
+		page = NULL;
+	}
+
+	return page;
+}
+
+static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
+{
+	struct page *page;
+	struct kmem_cache_order_objects oo = s->oo;
+	gfp_t alloc_gfp;
+	void *start, *p;
+	int idx, order;
+
+	flags &= gfp_allowed_mask;
+
+	if (gfpflags_allow_blocking(flags))
+		local_irq_enable();
+
+	flags |= s->allocflags;
+
+	/*
+	 * Let the initial higher-order allocation fail under memory pressure
+	 * so we fall-back to the minimum order allocation.
+	 */
+	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
+	if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
+		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_DIRECT_RECLAIM;
+
+	page = alloc_slab_page(s, alloc_gfp, node, oo);
+	if (unlikely(!page)) {
+		oo = s->min;
+		alloc_gfp = flags;
+		/*
+		 * Allocation may have failed due to fragmentation.
+		 * Try a lower order alloc if possible
+		 */
+		page = alloc_slab_page(s, alloc_gfp, node, oo);
+		if (unlikely(!page))
+			goto out;
+		stat(s, ORDER_FALLBACK);
+	}
+
+	if (kmemcheck_enabled &&
+	    !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
+		int pages = 1 << oo_order(oo);
+
+		kmemcheck_alloc_shadow(page, oo_order(oo), alloc_gfp, node);
+
+		/*
+		 * Objects from caches that have a constructor don't get
+		 * cleared when they're allocated, so we need to do it here.
+		 */
+		if (s->ctor)
+			kmemcheck_mark_uninitialized_pages(page, pages);
+		else
+			kmemcheck_mark_unallocated_pages(page, pages);
+	}
+
+	page->objects = oo_objects(oo);
+
+	order = compound_order(page);
+	page->slab_cache = s;
+	__SetPageSlab(page);
+	if (page_is_pfmemalloc(page))
+		SetPageSlabPfmemalloc(page);
+
+	start = page_address(page);
+
+	if (unlikely(s->flags & SLAB_POISON))
+		memset(start, POISON_INUSE, PAGE_SIZE << order);
+
+	kasan_poison_slab(page);
+
+	for_each_object_idx(p, idx, s, start, page->objects) {
+		setup_object(s, page, p);
+		if (likely(idx < page->objects))
+			set_freepointer(s, p, p + s->size);
+		else
+			set_freepointer(s, p, NULL);
+	}
+
+	page->freelist = start;
+	page->inuse = page->objects;
+	page->frozen = 1;
+
+out:
+	if (gfpflags_allow_blocking(flags))
+		local_irq_disable();
+	if (!page)
+		return NULL;
+
+	mod_zone_page_state(page_zone(page),
+		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
+		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
+		1 << oo_order(oo));
+
+	inc_slabs_node(s, page_to_nid(page), page->objects);
+
+	return page;
+}
+
+static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
+{
+	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
+		pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK);
+		BUG();
+	}
+
+	return allocate_slab(s,
+		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
+}
+
+static void __free_slab(struct kmem_cache *s, struct page *page)
+{
+	int order = compound_order(page);
+	int pages = 1 << order;
+
+	if (kmem_cache_debug(s)) {
+		void *p;
+
+		slab_pad_check(s, page);
+		for_each_object(p, s, page_address(page),
+						page->objects)
+			check_object(s, page, p, SLUB_RED_INACTIVE);
+	}
+
+	kmemcheck_free_shadow(page, compound_order(page));
+
+	mod_zone_page_state(page_zone(page),
+		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
+		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
+		-pages);
+
+	__ClearPageSlabPfmemalloc(page);
+	__ClearPageSlab(page);
+
+	page_mapcount_reset(page);
+	if (current->reclaim_state)
+		current->reclaim_state->reclaimed_slab += pages;
+	__free_kmem_pages(page, order);
+}
+
+#define need_reserve_slab_rcu						\
+	(sizeof(((struct page *)NULL)->lru) < sizeof(struct rcu_head))
+
+static void rcu_free_slab(struct rcu_head *h)
+{
+	struct page *page;
+
+	if (need_reserve_slab_rcu)
+		page = virt_to_head_page(h);
+	else
+		page = container_of((struct list_head *)h, struct page, lru);
+
+	__free_slab(page->slab_cache, page);
+}
+
+static void free_slab(struct kmem_cache *s, struct page *page)
+{
+	if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
+		struct rcu_head *head;
+
+		if (need_reserve_slab_rcu) {
+			int order = compound_order(page);
+			int offset = (PAGE_SIZE << order) - s->reserved;
+
+			VM_BUG_ON(s->reserved != sizeof(*head));
+			head = page_address(page) + offset;
+		} else {
+			head = &page->rcu_head;
+		}
+
+		call_rcu(head, rcu_free_slab);
+	} else
+		__free_slab(s, page);
+}
+
+static void discard_slab(struct kmem_cache *s, struct page *page)
+{
+	dec_slabs_node(s, page_to_nid(page), page->objects);
+	free_slab(s, page);
+}
+
+/*
+ * Management of partially allocated slabs.
+ */
+static inline void
+__add_partial(struct kmem_cache_node *n, struct page *page, int tail)
+{
+	n->nr_partial++;
+	if (tail == DEACTIVATE_TO_TAIL)
+		list_add_tail(&page->lru, &n->partial);
+	else
+		list_add(&page->lru, &n->partial);
+}
+
+static inline void add_partial(struct kmem_cache_node *n,
+				struct page *page, int tail)
+{
+	lockdep_assert_held(&n->list_lock);
+	__add_partial(n, page, tail);
+}
+
+static inline void
+__remove_partial(struct kmem_cache_node *n, struct page *page)
+{
+	list_del(&page->lru);
+	n->nr_partial--;
+}
+
+static inline void remove_partial(struct kmem_cache_node *n,
+					struct page *page)
+{
+	lockdep_assert_held(&n->list_lock);
+	__remove_partial(n, page);
+}
+
+/*
+ * Remove slab from the partial list, freeze it and
+ * return the pointer to the freelist.
+ *
+ * Returns a list of objects or NULL if it fails.
+ */
+static inline void *acquire_slab(struct kmem_cache *s,
+		struct kmem_cache_node *n, struct page *page,
+		int mode, int *objects)
+{
+	void *freelist;
+	unsigned long counters;
+	struct page new;
+
+	lockdep_assert_held(&n->list_lock);
+
+	/*
+	 * Zap the freelist and set the frozen bit.
+	 * The old freelist is the list of objects for the
+	 * per cpu allocation list.
+	 */
+	freelist = page->freelist;
+	counters = page->counters;
+	new.counters = counters;
+	*objects = new.objects - new.inuse;
+	if (mode) {
+		new.inuse = page->objects;
+		new.freelist = NULL;
+	} else {
+		new.freelist = freelist;
+	}
+
+	VM_BUG_ON(new.frozen);
+	new.frozen = 1;
+
+	if (!__cmpxchg_double_slab(s, page,
+			freelist, counters,
+			new.freelist, new.counters,
+			"acquire_slab"))
+		return NULL;
+
+	remove_partial(n, page);
+	WARN_ON(!freelist);
+	return freelist;
+}
+
+static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
+static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
+
+/*
+ * Try to allocate a partial slab from a specific node.
+ */
+static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
+				struct kmem_cache_cpu *c, gfp_t flags)
+{
+	struct page *page, *page2;
+	void *object = NULL;
+	int available = 0;
+	int objects;
+
+	/*
+	 * Racy check. If we mistakenly see no partial slabs then we
+	 * just allocate an empty slab. If we mistakenly try to get a
+	 * partial slab and there is none available then get_partials()
+	 * will return NULL.
+	 */
+	if (!n || !n->nr_partial)
+		return NULL;
+
+	spin_lock(&n->list_lock);
+	list_for_each_entry_safe(page, page2, &n->partial, lru) {
+		void *t;
+
+		if (!pfmemalloc_match(page, flags))
+			continue;
+
+		t = acquire_slab(s, n, page, object == NULL, &objects);
+		if (!t)
+			break;
+
+		available += objects;
+		if (!object) {
+			c->page = page;
+			stat(s, ALLOC_FROM_PARTIAL);
+			object = t;
+		} else {
+			put_cpu_partial(s, page, 0);
+			stat(s, CPU_PARTIAL_NODE);
+		}
+		if (!kmem_cache_has_cpu_partial(s)
+			|| available > s->cpu_partial / 2)
+			break;
+
+	}
+	spin_unlock(&n->list_lock);
+	return object;
+}
+
+/*
+ * Get a page from somewhere. Search in increasing NUMA distances.
+ */
+static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
+		struct kmem_cache_cpu *c)
+{
+#ifdef CONFIG_NUMA
+	struct zonelist *zonelist;
+	struct zoneref *z;
+	struct zone *zone;
+	enum zone_type high_zoneidx = gfp_zone(flags);
+	void *object;
+	unsigned int cpuset_mems_cookie;
+
+	/*
+	 * The defrag ratio allows a configuration of the tradeoffs between
+	 * inter node defragmentation and node local allocations. A lower
+	 * defrag_ratio increases the tendency to do local allocations
+	 * instead of attempting to obtain partial slabs from other nodes.
+	 *
+	 * If the defrag_ratio is set to 0 then kmalloc() always
+	 * returns node local objects. If the ratio is higher then kmalloc()
+	 * may return off node objects because partial slabs are obtained
+	 * from other nodes and filled up.
+	 *
+	 * If /sys/kernel/slab/xx/defrag_ratio is set to 100 (which makes
+	 * defrag_ratio = 1000) then every (well almost) allocation will
+	 * first attempt to defrag slab caches on other nodes. This means
+	 * scanning over all nodes to look for partial slabs which may be
+	 * expensive if we do it every time we are trying to find a slab
+	 * with available objects.
+	 */
+	if (!s->remote_node_defrag_ratio ||
+			get_cycles() % 1024 > s->remote_node_defrag_ratio)
+		return NULL;
+
+	do {
+		cpuset_mems_cookie = read_mems_allowed_begin();
+		zonelist = node_zonelist(mempolicy_slab_node(), flags);
+		for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
+			struct kmem_cache_node *n;
+
+			n = get_node(s, zone_to_nid(zone));
+
+			if (n && cpuset_zone_allowed(zone, flags) &&
+					n->nr_partial > s->min_partial) {
+				object = get_partial_node(s, n, c, flags);
+				if (object) {
+					/*
+					 * Don't check read_mems_allowed_retry()
+					 * here - if mems_allowed was updated in
+					 * parallel, that was a harmless race
+					 * between allocation and the cpuset
+					 * update
+					 */
+					return object;
+				}
+			}
+		}
+	} while (read_mems_allowed_retry(cpuset_mems_cookie));
+#endif
+	return NULL;
+}
+
+/*
+ * Get a partial page, lock it and return it.
+ */
+static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
+		struct kmem_cache_cpu *c)
+{
+	void *object;
+	int searchnode = node;
+
+	if (node == NUMA_NO_NODE)
+		searchnode = numa_mem_id();
+	else if (!node_present_pages(node))
+		searchnode = node_to_mem_node(node);
+
+	object = get_partial_node(s, get_node(s, searchnode), c, flags);
+	if (object || node != NUMA_NO_NODE)
+		return object;
+
+	return get_any_partial(s, flags, c);
+}
+
+#ifdef CONFIG_PREEMPT
+/*
+ * Calculate the next globally unique transaction for disambiguiation
+ * during cmpxchg. The transactions start with the cpu number and are then
+ * incremented by CONFIG_NR_CPUS.
+ */
+#define TID_STEP  roundup_pow_of_two(CONFIG_NR_CPUS)
+#else
+/*
+ * No preemption supported therefore also no need to check for
+ * different cpus.
+ */
+#define TID_STEP 1
+#endif
+
+static inline unsigned long next_tid(unsigned long tid)
+{
+	return tid + TID_STEP;
+}
+
+static inline unsigned int tid_to_cpu(unsigned long tid)
+{
+	return tid % TID_STEP;
+}
+
+static inline unsigned long tid_to_event(unsigned long tid)
+{
+	return tid / TID_STEP;
+}
+
+static inline unsigned int init_tid(int cpu)
+{
+	return cpu;
+}
+
+static inline void note_cmpxchg_failure(const char *n,
+		const struct kmem_cache *s, unsigned long tid)
+{
+#ifdef SLUB_DEBUG_CMPXCHG
+	unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);
+
+	pr_info("%s %s: cmpxchg redo ", n, s->name);
+
+#ifdef CONFIG_PREEMPT
+	if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
+		pr_warn("due to cpu change %d -> %d\n",
+			tid_to_cpu(tid), tid_to_cpu(actual_tid));
+	else
+#endif
+	if (tid_to_event(tid) != tid_to_event(actual_tid))
+		pr_warn("due to cpu running other code. Event %ld->%ld\n",
+			tid_to_event(tid), tid_to_event(actual_tid));
+	else
+		pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
+			actual_tid, tid, next_tid(tid));
+#endif
+	stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
+}
+
+static void init_kmem_cache_cpus(struct kmem_cache *s)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu);
+}
+
+/*
+ * Remove the cpu slab
+ */
+static void deactivate_slab(struct kmem_cache *s, struct page *page,
+				void *freelist)
+{
+	enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
+	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+	int lock = 0;
+	enum slab_modes l = M_NONE, m = M_NONE;
+	void *nextfree;
+	int tail = DEACTIVATE_TO_HEAD;
+	struct page new;
+	struct page old;
+
+	if (page->freelist) {
+		stat(s, DEACTIVATE_REMOTE_FREES);
+		tail = DEACTIVATE_TO_TAIL;
+	}
+
+	/*
+	 * Stage one: Free all available per cpu objects back
+	 * to the page freelist while it is still frozen. Leave the
+	 * last one.
+	 *
+	 * There is no need to take the list->lock because the page
+	 * is still frozen.
+	 */
+	while (freelist && (nextfree = get_freepointer(s, freelist))) {
+		void *prior;
+		unsigned long counters;
+
+		do {
+			prior = page->freelist;
+			counters = page->counters;
+			set_freepointer(s, freelist, prior);
+			new.counters = counters;
+			new.inuse--;
+			VM_BUG_ON(!new.frozen);
+
+		} while (!__cmpxchg_double_slab(s, page,
+			prior, counters,
+			freelist, new.counters,
+			"drain percpu freelist"));
+
+		freelist = nextfree;
+	}
+
+	/*
+	 * Stage two: Ensure that the page is unfrozen while the
+	 * list presence reflects the actual number of objects
+	 * during unfreeze.
+	 *
+	 * We setup the list membership and then perform a cmpxchg
+	 * with the count. If there is a mismatch then the page
+	 * is not unfrozen but the page is on the wrong list.
+	 *
+	 * Then we restart the process which may have to remove
+	 * the page from the list that we just put it on again
+	 * because the number of objects in the slab may have
+	 * changed.
+	 */
+redo:
+
+	old.freelist = page->freelist;
+	old.counters = page->counters;
+	VM_BUG_ON(!old.frozen);
+
+	/* Determine target state of the slab */
+	new.counters = old.counters;
+	if (freelist) {
+		new.inuse--;
+		set_freepointer(s, freelist, old.freelist);
+		new.freelist = freelist;
+	} else
+		new.freelist = old.freelist;
+
+	new.frozen = 0;
+
+	if (!new.inuse && n->nr_partial >= s->min_partial)
+		m = M_FREE;
+	else if (new.freelist) {
+		m = M_PARTIAL;
+		if (!lock) {
+			lock = 1;
+			/*
+			 * Taking the spinlock removes the possiblity
+			 * that acquire_slab() will see a slab page that
+			 * is frozen
+			 */
+			spin_lock(&n->list_lock);
+		}
+	} else {
+		m = M_FULL;
+		if (kmem_cache_debug(s) && !lock) {
+			lock = 1;
+			/*
+			 * This also ensures that the scanning of full
+			 * slabs from diagnostic functions will not see
+			 * any frozen slabs.
+			 */
+			spin_lock(&n->list_lock);
+		}
+	}
+
+	if (l != m) {
+
+		if (l == M_PARTIAL)
+
+			remove_partial(n, page);
+
+		else if (l == M_FULL)
+
+			remove_full(s, n, page);
+
+		if (m == M_PARTIAL) {
+
+			add_partial(n, page, tail);
+			stat(s, tail);
+
+		} else if (m == M_FULL) {
+
+			stat(s, DEACTIVATE_FULL);
+			add_full(s, n, page);
+
+		}
+	}
+
+	l = m;
+	if (!__cmpxchg_double_slab(s, page,
+				old.freelist, old.counters,
+				new.freelist, new.counters,
+				"unfreezing slab"))
+		goto redo;
+
+	if (lock)
+		spin_unlock(&n->list_lock);
+
+	if (m == M_FREE) {
+		stat(s, DEACTIVATE_EMPTY);
+		discard_slab(s, page);
+		stat(s, FREE_SLAB);
+	}
+}
+
+/*
+ * Unfreeze all the cpu partial slabs.
+ *
+ * This function must be called with interrupts disabled
+ * for the cpu using c (or some other guarantee must be there
+ * to guarantee no concurrent accesses).
+ */
+static void unfreeze_partials(struct kmem_cache *s,
+		struct kmem_cache_cpu *c)
+{
+#ifdef CONFIG_SLUB_CPU_PARTIAL
+	struct kmem_cache_node *n = NULL, *n2 = NULL;
+	struct page *page, *discard_page = NULL;
+
+	while ((page = c->partial)) {
+		struct page new;
+		struct page old;
+
+		c->partial = page->next;
+
+		n2 = get_node(s, page_to_nid(page));
+		if (n != n2) {
+			if (n)
+				spin_unlock(&n->list_lock);
+
+			n = n2;
+			spin_lock(&n->list_lock);
+		}
+
+		do {
+
+			old.freelist = page->freelist;
+			old.counters = page->counters;
+			VM_BUG_ON(!old.frozen);
+
+			new.counters = old.counters;
+			new.freelist = old.freelist;
+
+			new.frozen = 0;
+
+		} while (!__cmpxchg_double_slab(s, page,
+				old.freelist, old.counters,
+				new.freelist, new.counters,
+				"unfreezing slab"));
+
+		if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
+			page->next = discard_page;
+			discard_page = page;
+		} else {
+			add_partial(n, page, DEACTIVATE_TO_TAIL);
+			stat(s, FREE_ADD_PARTIAL);
+		}
+	}
+
+	if (n)
+		spin_unlock(&n->list_lock);
+
+	while (discard_page) {
+		page = discard_page;
+		discard_page = discard_page->next;
+
+		stat(s, DEACTIVATE_EMPTY);
+		discard_slab(s, page);
+		stat(s, FREE_SLAB);
+	}
+#endif
+}
+
+/*
+ * Put a page that was just frozen (in __slab_free) into a partial page
+ * slot if available. This is done without interrupts disabled and without
+ * preemption disabled. The cmpxchg is racy and may put the partial page
+ * onto a random cpus partial slot.
+ *
+ * If we did not find a slot then simply move all the partials to the
+ * per node partial list.
+ */
+static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
+{
+#ifdef CONFIG_SLUB_CPU_PARTIAL
+	struct page *oldpage;
+	int pages;
+	int pobjects;
+
+	preempt_disable();
+	do {
+		pages = 0;
+		pobjects = 0;
+		oldpage = this_cpu_read(s->cpu_slab->partial);
+
+		if (oldpage) {
+			pobjects = oldpage->pobjects;
+			pages = oldpage->pages;
+			if (drain && pobjects > s->cpu_partial) {
+				unsigned long flags;
+				/*
+				 * partial array is full. Move the existing
+				 * set to the per node partial list.
+				 */
+				local_irq_save(flags);
+				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
+				local_irq_restore(flags);
+				oldpage = NULL;
+				pobjects = 0;
+				pages = 0;
+				stat(s, CPU_PARTIAL_DRAIN);
+			}
+		}
+
+		pages++;
+		pobjects += page->objects - page->inuse;
+
+		page->pages = pages;
+		page->pobjects = pobjects;
+		page->next = oldpage;
+
+	} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page)
+								!= oldpage);
+	if (unlikely(!s->cpu_partial)) {
+		unsigned long flags;
+
+		local_irq_save(flags);
+		unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
+		local_irq_restore(flags);
+	}
+	preempt_enable();
+#endif
+}
+
+static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
+{
+	stat(s, CPUSLAB_FLUSH);
+	deactivate_slab(s, c->page, c->freelist);
+
+	c->tid = next_tid(c->tid);
+	c->page = NULL;
+	c->freelist = NULL;
+}
+
+/*
+ * Flush cpu slab.
+ *
+ * Called from IPI handler with interrupts disabled.
+ */
+static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
+{
+	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+
+	if (likely(c)) {
+		if (c->page)
+			flush_slab(s, c);
+
+		unfreeze_partials(s, c);
+	}
+}
+
+static void flush_cpu_slab(void *d)
+{
+	struct kmem_cache *s = d;
+
+	__flush_cpu_slab(s, smp_processor_id());
+}
+
+static bool has_cpu_slab(int cpu, void *info)
+{
+	struct kmem_cache *s = info;
+	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+
+	return c->page || c->partial;
+}
+
+static void flush_all(struct kmem_cache *s)
+{
+	on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1, GFP_ATOMIC);
+}
+
+/*
+ * Check if the objects in a per cpu structure fit numa
+ * locality expectations.
+ */
+static inline int node_match(struct page *page, int node)
+{
+#ifdef CONFIG_NUMA
+	if (!page || (node != NUMA_NO_NODE && page_to_nid(page) != node))
+		return 0;
+#endif
+	return 1;
+}
+
+#ifdef CONFIG_SLUB_DEBUG
+static int count_free(struct page *page)
+{
+	return page->objects - page->inuse;
+}
+
+static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
+{
+	return atomic_long_read(&n->total_objects);
+}
+#endif /* CONFIG_SLUB_DEBUG */
+
+#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
+static unsigned long count_partial(struct kmem_cache_node *n,
+					int (*get_count)(struct page *))
+{
+	unsigned long flags;
+	unsigned long x = 0;
+	struct page *page;
+
+	spin_lock_irqsave(&n->list_lock, flags);
+	list_for_each_entry(page, &n->partial, lru)
+		x += get_count(page);
+	spin_unlock_irqrestore(&n->list_lock, flags);
+	return x;
+}
+#endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */
+
+static noinline void
+slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
+{
+#ifdef CONFIG_SLUB_DEBUG
+	static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
+				      DEFAULT_RATELIMIT_BURST);
+	int node;
+	struct kmem_cache_node *n;
+
+	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
+		return;
+
+	pr_warn("SLUB: Unable to allocate memory on node %d (gfp=0x%x)\n",
+		nid, gfpflags);
+	pr_warn("  cache: %s, object size: %d, buffer size: %d, default order: %d, min order: %d\n",
+		s->name, s->object_size, s->size, oo_order(s->oo),
+		oo_order(s->min));
+
+	if (oo_order(s->min) > get_order(s->object_size))
+		pr_warn("  %s debugging increased min order, use slub_debug=O to disable.\n",
+			s->name);
+
+	for_each_kmem_cache_node(s, node, n) {
+		unsigned long nr_slabs;
+		unsigned long nr_objs;
+		unsigned long nr_free;
+
+		nr_free  = count_partial(n, count_free);
+		nr_slabs = node_nr_slabs(n);
+		nr_objs  = node_nr_objs(n);
+
+		pr_warn("  node %d: slabs: %ld, objs: %ld, free: %ld\n",
+			node, nr_slabs, nr_objs, nr_free);
+	}
+#endif
+}
+
+static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
+			int node, struct kmem_cache_cpu **pc)
+{
+	void *freelist;
+	struct kmem_cache_cpu *c = *pc;
+	struct page *page;
+
+	freelist = get_partial(s, flags, node, c);
+
+	if (freelist)
+		return freelist;
+
+	page = new_slab(s, flags, node);
+	if (page) {
+		c = raw_cpu_ptr(s->cpu_slab);
+		if (c->page)
+			flush_slab(s, c);
+
+		/*
+		 * No other reference to the page yet so we can
+		 * muck around with it freely without cmpxchg
+		 */
+		freelist = page->freelist;
+		page->freelist = NULL;
+
+		stat(s, ALLOC_SLAB);
+		c->page = page;
+		*pc = c;
+	} else
+		freelist = NULL;
+
+	return freelist;
+}
+
+static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags)
+{
+	if (unlikely(PageSlabPfmemalloc(page)))
+		return gfp_pfmemalloc_allowed(gfpflags);
+
+	return true;
+}
+
+/*
+ * Check the page->freelist of a page and either transfer the freelist to the
+ * per cpu freelist or deactivate the page.
+ *
+ * The page is still frozen if the return value is not NULL.
+ *
+ * If this function returns NULL then the page has been unfrozen.
+ *
+ * This function must be called with interrupt disabled.
+ */
+static inline void *get_freelist(struct kmem_cache *s, struct page *page)
+{
+	struct page new;
+	unsigned long counters;
+	void *freelist;
+
+	do {
+		freelist = page->freelist;
+		counters = page->counters;
+
+		new.counters = counters;
+		VM_BUG_ON(!new.frozen);
+
+		new.inuse = page->objects;
+		new.frozen = freelist != NULL;
+
+	} while (!__cmpxchg_double_slab(s, page,
+		freelist, counters,
+		NULL, new.counters,
+		"get_freelist"));
+
+	return freelist;
+}
+
+/*
+ * Slow path. The lockless freelist is empty or we need to perform
+ * debugging duties.
+ *
+ * Processing is still very fast if new objects have been freed to the
+ * regular freelist. In that case we simply take over the regular freelist
+ * as the lockless freelist and zap the regular freelist.
+ *
+ * If that is not working then we fall back to the partial lists. We take the
+ * first element of the freelist as the object to allocate now and move the
+ * rest of the freelist to the lockless freelist.
+ *
+ * And if we were unable to get a new slab from the partial slab lists then
+ * we need to allocate a new slab. This is the slowest path since it involves
+ * a call to the page allocator and the setup of a new slab.
+ *
+ * Version of __slab_alloc to use when we know that interrupts are
+ * already disabled (which is the case for bulk allocation).
+ */
+static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
+			  unsigned long addr, struct kmem_cache_cpu *c)
+{
+	void *freelist;
+	struct page *page;
+
+	page = c->page;
+	if (!page)
+		goto new_slab;
+redo:
+
+	if (unlikely(!node_match(page, node))) {
+		int searchnode = node;
+
+		if (node != NUMA_NO_NODE && !node_present_pages(node))
+			searchnode = node_to_mem_node(node);
+
+		if (unlikely(!node_match(page, searchnode))) {
+			stat(s, ALLOC_NODE_MISMATCH);
+			deactivate_slab(s, page, c->freelist);
+			c->page = NULL;
+			c->freelist = NULL;
+			goto new_slab;
+		}
+	}
+
+	/*
+	 * By rights, we should be searching for a slab page that was
+	 * PFMEMALLOC but right now, we are losing the pfmemalloc
+	 * information when the page leaves the per-cpu allocator
+	 */
+	if (unlikely(!pfmemalloc_match(page, gfpflags))) {
+		deactivate_slab(s, page, c->freelist);
+		c->page = NULL;
+		c->freelist = NULL;
+		goto new_slab;
+	}
+
+	/* must check again c->freelist in case of cpu migration or IRQ */
+	freelist = c->freelist;
+	if (freelist)
+		goto load_freelist;
+
+	freelist = get_freelist(s, page);
+
+	if (!freelist) {
+		c->page = NULL;
+		stat(s, DEACTIVATE_BYPASS);
+		goto new_slab;
+	}
+
+	stat(s, ALLOC_REFILL);
+
+load_freelist:
+	/*
+	 * freelist is pointing to the list of objects to be used.
+	 * page is pointing to the page from which the objects are obtained.
+	 * That page must be frozen for per cpu allocations to work.
+	 */
+	VM_BUG_ON(!c->page->frozen);
+	c->freelist = get_freepointer(s, freelist);
+	c->tid = next_tid(c->tid);
+	return freelist;
+
+new_slab:
+
+	if (c->partial) {
+		page = c->page = c->partial;
+		c->partial = page->next;
+		stat(s, CPU_PARTIAL_ALLOC);
+		c->freelist = NULL;
+		goto redo;
+	}
+
+	freelist = new_slab_objects(s, gfpflags, node, &c);
+
+	if (unlikely(!freelist)) {
+		slab_out_of_memory(s, gfpflags, node);
+		return NULL;
+	}
+
+	page = c->page;
+	if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags)))
+		goto load_freelist;
+
+	/* Only entered in the debug case */
+	if (kmem_cache_debug(s) &&
+			!alloc_debug_processing(s, page, freelist, addr))
+		goto new_slab;	/* Slab failed checks. Next slab needed */
+
+	deactivate_slab(s, page, get_freepointer(s, freelist));
+	c->page = NULL;
+	c->freelist = NULL;
+	return freelist;
+}
+
+/*
+ * Another one that disabled interrupt and compensates for possible
+ * cpu changes by refetching the per cpu area pointer.
+ */
+static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
+			  unsigned long addr, struct kmem_cache_cpu *c)
+{
+	void *p;
+	unsigned long flags;
+
+	local_irq_save(flags);
+#ifdef CONFIG_PREEMPT
+	/*
+	 * We may have been preempted and rescheduled on a different
+	 * cpu before disabling interrupts. Need to reload cpu area
+	 * pointer.
+	 */
+	c = this_cpu_ptr(s->cpu_slab);
+#endif
+
+	p = ___slab_alloc(s, gfpflags, node, addr, c);
+	local_irq_restore(flags);
+	return p;
+}
+
+/*
+ * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
+ * have the fastpath folded into their functions. So no function call
+ * overhead for requests that can be satisfied on the fastpath.
+ *
+ * The fastpath works by first checking if the lockless freelist can be used.
+ * If not then __slab_alloc is called for slow processing.
+ *
+ * Otherwise we can simply pick the next object from the lockless free list.
+ */
+static __always_inline void *slab_alloc_node(struct kmem_cache *s,
+		gfp_t gfpflags, int node, unsigned long addr)
+{
+	void *object;
+	struct kmem_cache_cpu *c;
+	struct page *page;
+	unsigned long tid;
+
+	s = slab_pre_alloc_hook(s, gfpflags);
+	if (!s)
+		return NULL;
+redo:
+	/*
+	 * Must read kmem_cache cpu data via this cpu ptr. Preemption is
+	 * enabled. We may switch back and forth between cpus while
+	 * reading from one cpu area. That does not matter as long
+	 * as we end up on the original cpu again when doing the cmpxchg.
+	 *
+	 * We should guarantee that tid and kmem_cache are retrieved on
+	 * the same cpu. It could be different if CONFIG_PREEMPT so we need
+	 * to check if it is matched or not.
+	 */
+	do {
+		tid = this_cpu_read(s->cpu_slab->tid);
+		c = raw_cpu_ptr(s->cpu_slab);
+	} while (IS_ENABLED(CONFIG_PREEMPT) &&
+		 unlikely(tid != READ_ONCE(c->tid)));
+
+	/*
+	 * Irqless object alloc/free algorithm used here depends on sequence
+	 * of fetching cpu_slab's data. tid should be fetched before anything
+	 * on c to guarantee that object and page associated with previous tid
+	 * won't be used with current tid. If we fetch tid first, object and
+	 * page could be one associated with next tid and our alloc/free
+	 * request will be failed. In this case, we will retry. So, no problem.
+	 */
+	barrier();
+
+	/*
+	 * The transaction ids are globally unique per cpu and per operation on
+	 * a per cpu queue. Thus they can be guarantee that the cmpxchg_double
+	 * occurs on the right processor and that there was no operation on the
+	 * linked list in between.
+	 */
+
+	object = c->freelist;
+	page = c->page;
+	if (unlikely(!object || !node_match(page, node))) {
+		object = __slab_alloc(s, gfpflags, node, addr, c);
+		stat(s, ALLOC_SLOWPATH);
+	} else {
+		void *next_object = get_freepointer_safe(s, object);
+
+		/*
+		 * The cmpxchg will only match if there was no additional
+		 * operation and if we are on the right processor.
+		 *
+		 * The cmpxchg does the following atomically (without lock
+		 * semantics!)
+		 * 1. Relocate first pointer to the current per cpu area.
+		 * 2. Verify that tid and freelist have not been changed
+		 * 3. If they were not changed replace tid and freelist
+		 *
+		 * Since this is without lock semantics the protection is only
+		 * against code executing on this cpu *not* from access by
+		 * other cpus.
+		 */
+		if (unlikely(!this_cpu_cmpxchg_double(
+				s->cpu_slab->freelist, s->cpu_slab->tid,
+				object, tid,
+				next_object, next_tid(tid)))) {
+
+			note_cmpxchg_failure("slab_alloc", s, tid);
+			goto redo;
+		}
+		prefetch_freepointer(s, next_object);
+		stat(s, ALLOC_FASTPATH);
+	}
+
+	if (unlikely(gfpflags & __GFP_ZERO) && object)
+		memset(object, 0, s->object_size);
+
+	slab_post_alloc_hook(s, gfpflags, 1, &object);
+
+	return object;
+}
+
+static __always_inline void *slab_alloc(struct kmem_cache *s,
+		gfp_t gfpflags, unsigned long addr)
+{
+	return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr);
+}
+
+void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
+{
+	void *ret = slab_alloc(s, gfpflags, _RET_IP_);
+
+	trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size,
+				s->size, gfpflags);
+
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc);
+
+#ifdef CONFIG_TRACING
+void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
+{
+	void *ret = slab_alloc(s, gfpflags, _RET_IP_);
+	trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags);
+	kasan_kmalloc(s, ret, size);
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_trace);
+#endif
+
+#ifdef CONFIG_NUMA
+void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
+{
+	void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
+
+	trace_kmem_cache_alloc_node(_RET_IP_, ret,
+				    s->object_size, s->size, gfpflags, node);
+
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_node);
+
+#ifdef CONFIG_TRACING
+void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
+				    gfp_t gfpflags,
+				    int node, size_t size)
+{
+	void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
+
+	trace_kmalloc_node(_RET_IP_, ret,
+			   size, s->size, gfpflags, node);
+
+	kasan_kmalloc(s, ret, size);
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
+#endif
+#endif
+
+/*
+ * Slow path handling. This may still be called frequently since objects
+ * have a longer lifetime than the cpu slabs in most processing loads.
+ *
+ * So we still attempt to reduce cache line usage. Just take the slab
+ * lock and free the item. If there is no additional partial page
+ * handling required then we can return immediately.
+ */
+static void __slab_free(struct kmem_cache *s, struct page *page,
+			void *head, void *tail, int cnt,
+			unsigned long addr)
+
+{
+	void *prior;
+	int was_frozen;
+	struct page new;
+	unsigned long counters;
+	struct kmem_cache_node *n = NULL;
+	unsigned long uninitialized_var(flags);
+
+	stat(s, FREE_SLOWPATH);
+
+	if (kmem_cache_debug(s) &&
+	    !(n = free_debug_processing(s, page, head, tail, cnt,
+					addr, &flags)))
+		return;
+
+	do {
+		if (unlikely(n)) {
+			spin_unlock_irqrestore(&n->list_lock, flags);
+			n = NULL;
+		}
+		prior = page->freelist;
+		counters = page->counters;
+		set_freepointer(s, tail, prior);
+		new.counters = counters;
+		was_frozen = new.frozen;
+		new.inuse -= cnt;
+		if ((!new.inuse || !prior) && !was_frozen) {
+
+			if (kmem_cache_has_cpu_partial(s) && !prior) {
+
+				/*
+				 * Slab was on no list before and will be
+				 * partially empty
+				 * We can defer the list move and instead
+				 * freeze it.
+				 */
+				new.frozen = 1;
+
+			} else { /* Needs to be taken off a list */
+
+				n = get_node(s, page_to_nid(page));
+				/*
+				 * Speculatively acquire the list_lock.
+				 * If the cmpxchg does not succeed then we may
+				 * drop the list_lock without any processing.
+				 *
+				 * Otherwise the list_lock will synchronize with
+				 * other processors updating the list of slabs.
+				 */
+				spin_lock_irqsave(&n->list_lock, flags);
+
+			}
+		}
+
+	} while (!cmpxchg_double_slab(s, page,
+		prior, counters,
+		head, new.counters,
+		"__slab_free"));
+
+	if (likely(!n)) {
+
+		/*
+		 * If we just froze the page then put it onto the
+		 * per cpu partial list.
+		 */
+		if (new.frozen && !was_frozen) {
+			put_cpu_partial(s, page, 1);
+			stat(s, CPU_PARTIAL_FREE);
+		}
+		/*
+		 * The list lock was not taken therefore no list
+		 * activity can be necessary.
+		 */
+		if (was_frozen)
+			stat(s, FREE_FROZEN);
+		return;
+	}
+
+	if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
+		goto slab_empty;
+
+	/*
+	 * Objects left in the slab. If it was not on the partial list before
+	 * then add it.
+	 */
+	if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
+		if (kmem_cache_debug(s))
+			remove_full(s, n, page);
+		add_partial(n, page, DEACTIVATE_TO_TAIL);
+		stat(s, FREE_ADD_PARTIAL);
+	}
+	spin_unlock_irqrestore(&n->list_lock, flags);
+	return;
+
+slab_empty:
+	if (prior) {
+		/*
+		 * Slab on the partial list.
+		 */
+		remove_partial(n, page);
+		stat(s, FREE_REMOVE_PARTIAL);
+	} else {
+		/* Slab must be on the full list */
+		remove_full(s, n, page);
+	}
+
+	spin_unlock_irqrestore(&n->list_lock, flags);
+	stat(s, FREE_SLAB);
+	discard_slab(s, page);
+}
+
+/*
+ * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
+ * can perform fastpath freeing without additional function calls.
+ *
+ * The fastpath is only possible if we are freeing to the current cpu slab
+ * of this processor. This typically the case if we have just allocated
+ * the item before.
+ *
+ * If fastpath is not possible then fall back to __slab_free where we deal
+ * with all sorts of special processing.
+ *
+ * Bulk free of a freelist with several objects (all pointing to the
+ * same page) possible by specifying head and tail ptr, plus objects
+ * count (cnt). Bulk free indicated by tail pointer being set.
+ */
+static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
+				      void *head, void *tail, int cnt,
+				      unsigned long addr)
+{
+	void *tail_obj = tail ? : head;
+	struct kmem_cache_cpu *c;
+	unsigned long tid;
+
+	slab_free_freelist_hook(s, head, tail);
+
+redo:
+	/*
+	 * Determine the currently cpus per cpu slab.
+	 * The cpu may change afterward. However that does not matter since
+	 * data is retrieved via this pointer. If we are on the same cpu
+	 * during the cmpxchg then the free will succeed.
+	 */
+	do {
+		tid = this_cpu_read(s->cpu_slab->tid);
+		c = raw_cpu_ptr(s->cpu_slab);
+	} while (IS_ENABLED(CONFIG_PREEMPT) &&
+		 unlikely(tid != READ_ONCE(c->tid)));
+
+	/* Same with comment on barrier() in slab_alloc_node() */
+	barrier();
+
+	if (likely(page == c->page)) {
+		set_freepointer(s, tail_obj, c->freelist);
+
+		if (unlikely(!this_cpu_cmpxchg_double(
+				s->cpu_slab->freelist, s->cpu_slab->tid,
+				c->freelist, tid,
+				head, next_tid(tid)))) {
+
+			note_cmpxchg_failure("slab_free", s, tid);
+			goto redo;
+		}
+		stat(s, FREE_FASTPATH);
+	} else
+		__slab_free(s, page, head, tail_obj, cnt, addr);
+
+}
+
+void kmem_cache_free(struct kmem_cache *s, void *x)
+{
+	s = cache_from_obj(s, x);
+	if (!s)
+		return;
+	slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_);
+	trace_kmem_cache_free(_RET_IP_, x);
+}
+EXPORT_SYMBOL(kmem_cache_free);
+
+struct detached_freelist {
+	struct page *page;
+	void *tail;
+	void *freelist;
+	int cnt;
+	struct kmem_cache *s;
+};
+
+/*
+ * This function progressively scans the array with free objects (with
+ * a limited look ahead) and extract objects belonging to the same
+ * page.  It builds a detached freelist directly within the given
+ * page/objects.  This can happen without any need for
+ * synchronization, because the objects are owned by running process.
+ * The freelist is build up as a single linked list in the objects.
+ * The idea is, that this detached freelist can then be bulk
+ * transferred to the real freelist(s), but only requiring a single
+ * synchronization primitive.  Look ahead in the array is limited due
+ * to performance reasons.
+ */
+static inline
+int build_detached_freelist(struct kmem_cache *s, size_t size,
+			    void **p, struct detached_freelist *df)
+{
+	size_t first_skipped_index = 0;
+	int lookahead = 3;
+	void *object;
+
+	/* Always re-init detached_freelist */
+	df->page = NULL;
+
+	do {
+		object = p[--size];
+	} while (!object && size);
+
+	if (!object)
+		return 0;
+
+	/* Support for memcg, compiler can optimize this out */
+	df->s = cache_from_obj(s, object);
+
+	/* Start new detached freelist */
+	set_freepointer(df->s, object, NULL);
+	df->page = virt_to_head_page(object);
+	df->tail = object;
+	df->freelist = object;
+	p[size] = NULL; /* mark object processed */
+	df->cnt = 1;
+
+	while (size) {
+		object = p[--size];
+		if (!object)
+			continue; /* Skip processed objects */
+
+		/* df->page is always set at this point */
+		if (df->page == virt_to_head_page(object)) {
+			/* Opportunity build freelist */
+			set_freepointer(df->s, object, df->freelist);
+			df->freelist = object;
+			df->cnt++;
+			p[size] = NULL; /* mark object processed */
+
+			continue;
+		}
+
+		/* Limit look ahead search */
+		if (!--lookahead)
+			break;
+
+		if (!first_skipped_index)
+			first_skipped_index = size + 1;
+	}
+
+	return first_skipped_index;
+}
+
+/* Note that interrupts must be enabled when calling this function. */
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
+{
+	if (WARN_ON(!size))
+		return;
+
+	do {
+		struct detached_freelist df;
+
+		size = build_detached_freelist(s, size, p, &df);
+		if (unlikely(!df.page))
+			continue;
+
+		slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_);
+	} while (likely(size));
+}
+EXPORT_SYMBOL(kmem_cache_free_bulk);
+
+/* Note that interrupts must be enabled when calling this function. */
+int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
+			  void **p)
+{
+	struct kmem_cache_cpu *c;
+	int i;
+
+	/* memcg and kmem_cache debug support */
+	s = slab_pre_alloc_hook(s, flags);
+	if (unlikely(!s))
+		return false;
+	/*
+	 * Drain objects in the per cpu slab, while disabling local
+	 * IRQs, which protects against PREEMPT and interrupts
+	 * handlers invoking normal fastpath.
+	 */
+	local_irq_disable();
+	c = this_cpu_ptr(s->cpu_slab);
+
+	for (i = 0; i < size; i++) {
+		void *object = c->freelist;
+
+		if (unlikely(!object)) {
+			/*
+			 * Invoking slow path likely have side-effect
+			 * of re-populating per CPU c->freelist
+			 */
+			p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE,
+					    _RET_IP_, c);
+			if (unlikely(!p[i]))
+				goto error;
+
+			c = this_cpu_ptr(s->cpu_slab);
+			continue; /* goto for-loop */
+		}
+		c->freelist = get_freepointer(s, object);
+		p[i] = object;
+	}
+	c->tid = next_tid(c->tid);
+	local_irq_enable();
+
+	/* Clear memory outside IRQ disabled fastpath loop */
+	if (unlikely(flags & __GFP_ZERO)) {
+		int j;
+
+		for (j = 0; j < i; j++)
+			memset(p[j], 0, s->object_size);
+	}
+
+	/* memcg and kmem_cache debug support */
+	slab_post_alloc_hook(s, flags, size, p);
+	return i;
+error:
+	local_irq_enable();
+	slab_post_alloc_hook(s, flags, i, p);
+	__kmem_cache_free_bulk(s, i, p);
+	return 0;
+}
+EXPORT_SYMBOL(kmem_cache_alloc_bulk);
+
+
+/*
+ * Object placement in a slab is made very easy because we always start at
+ * offset 0. If we tune the size of the object to the alignment then we can
+ * get the required alignment by putting one properly sized object after
+ * another.
+ *
+ * Notice that the allocation order determines the sizes of the per cpu
+ * caches. Each processor has always one slab available for allocations.
+ * Increasing the allocation order reduces the number of times that slabs
+ * must be moved on and off the partial lists and is therefore a factor in
+ * locking overhead.
+ */
+
+/*
+ * Mininum / Maximum order of slab pages. This influences locking overhead
+ * and slab fragmentation. A higher order reduces the number of partial slabs
+ * and increases the number of allocations possible without having to
+ * take the list_lock.
+ */
+static int slub_min_order;
+static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
+static int slub_min_objects;
+
+/*
+ * Calculate the order of allocation given an slab object size.
+ *
+ * The order of allocation has significant impact on performance and other
+ * system components. Generally order 0 allocations should be preferred since
+ * order 0 does not cause fragmentation in the page allocator. Larger objects
+ * be problematic to put into order 0 slabs because there may be too much
+ * unused space left. We go to a higher order if more than 1/16th of the slab
+ * would be wasted.
+ *
+ * In order to reach satisfactory performance we must ensure that a minimum
+ * number of objects is in one slab. Otherwise we may generate too much
+ * activity on the partial lists which requires taking the list_lock. This is
+ * less a concern for large slabs though which are rarely used.
+ *
+ * slub_max_order specifies the order where we begin to stop considering the
+ * number of objects in a slab as critical. If we reach slub_max_order then
+ * we try to keep the page order as low as possible. So we accept more waste
+ * of space in favor of a small page order.
+ *
+ * Higher order allocations also allow the placement of more objects in a
+ * slab and thereby reduce object handling overhead. If the user has
+ * requested a higher mininum order then we start with that one instead of
+ * the smallest order which will fit the object.
+ */
+static inline int slab_order(int size, int min_objects,
+				int max_order, int fract_leftover, int reserved)
+{
+	int order;
+	int rem;
+	int min_order = slub_min_order;
+
+	if (order_objects(min_order, size, reserved) > MAX_OBJS_PER_PAGE)
+		return get_order(size * MAX_OBJS_PER_PAGE) - 1;
+
+	for (order = max(min_order, get_order(min_objects * size + reserved));
+			order <= max_order; order++) {
+
+		unsigned long slab_size = PAGE_SIZE << order;
+
+		rem = (slab_size - reserved) % size;
+
+		if (rem <= slab_size / fract_leftover)
+			break;
+	}
+
+	return order;
+}
+
+static inline int calculate_order(int size, int reserved)
+{
+	int order;
+	int min_objects;
+	int fraction;
+	int max_objects;
+
+	/*
+	 * Attempt to find best configuration for a slab. This
+	 * works by first attempting to generate a layout with
+	 * the best configuration and backing off gradually.
+	 *
+	 * First we increase the acceptable waste in a slab. Then
+	 * we reduce the minimum objects required in a slab.
+	 */
+	min_objects = slub_min_objects;
+	if (!min_objects)
+		min_objects = 4 * (fls(nr_cpu_ids) + 1);
+	max_objects = order_objects(slub_max_order, size, reserved);
+	min_objects = min(min_objects, max_objects);
+
+	while (min_objects > 1) {
+		fraction = 16;
+		while (fraction >= 4) {
+			order = slab_order(size, min_objects,
+					slub_max_order, fraction, reserved);
+			if (order <= slub_max_order)
+				return order;
+			fraction /= 2;
+		}
+		min_objects--;
+	}
+
+	/*
+	 * We were unable to place multiple objects in a slab. Now
+	 * lets see if we can place a single object there.
+	 */
+	order = slab_order(size, 1, slub_max_order, 1, reserved);
+	if (order <= slub_max_order)
+		return order;
+
+	/*
+	 * Doh this slab cannot be placed using slub_max_order.
+	 */
+	order = slab_order(size, 1, MAX_ORDER, 1, reserved);
+	if (order < MAX_ORDER)
+		return order;
+	return -ENOSYS;
+}
+
+static void
+init_kmem_cache_node(struct kmem_cache_node *n)
+{
+	n->nr_partial = 0;
+	spin_lock_init(&n->list_lock);
+	INIT_LIST_HEAD(&n->partial);
+#ifdef CONFIG_SLUB_DEBUG
+	atomic_long_set(&n->nr_slabs, 0);
+	atomic_long_set(&n->total_objects, 0);
+	INIT_LIST_HEAD(&n->full);
+#endif
+}
+
+static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
+{
+	BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
+			KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
+
+	/*
+	 * Must align to double word boundary for the double cmpxchg
+	 * instructions to work; see __pcpu_double_call_return_bool().
+	 */
+	s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu),
+				     2 * sizeof(void *));
+
+	if (!s->cpu_slab)
+		return 0;
+
+	init_kmem_cache_cpus(s);
+
+	return 1;
+}
+
+static struct kmem_cache *kmem_cache_node;
+
+/*
+ * No kmalloc_node yet so do it by hand. We know that this is the first
+ * slab on the node for this slabcache. There are no concurrent accesses
+ * possible.
+ *
+ * Note that this function only works on the kmem_cache_node
+ * when allocating for the kmem_cache_node. This is used for bootstrapping
+ * memory on a fresh node that has no slab structures yet.
+ */
+static void early_kmem_cache_node_alloc(int node)
+{
+	struct page *page;
+	struct kmem_cache_node *n;
+
+	BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
+
+	page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
+
+	BUG_ON(!page);
+	if (page_to_nid(page) != node) {
+		pr_err("SLUB: Unable to allocate memory from node %d\n", node);
+		pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n");
+	}
+
+	n = page->freelist;
+	BUG_ON(!n);
+	page->freelist = get_freepointer(kmem_cache_node, n);
+	page->inuse = 1;
+	page->frozen = 0;
+	kmem_cache_node->node[node] = n;
+#ifdef CONFIG_SLUB_DEBUG
+	init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
+	init_tracking(kmem_cache_node, n);
+#endif
+	kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node));
+	init_kmem_cache_node(n);
+	inc_slabs_node(kmem_cache_node, node, page->objects);
+
+	/*
+	 * No locks need to be taken here as it has just been
+	 * initialized and there is no concurrent access.
+	 */
+	__add_partial(n, page, DEACTIVATE_TO_HEAD);
+}
+
+static void free_kmem_cache_nodes(struct kmem_cache *s)
+{
+	int node;
+	struct kmem_cache_node *n;
+
+	for_each_kmem_cache_node(s, node, n) {
+		kmem_cache_free(kmem_cache_node, n);
+		s->node[node] = NULL;
+	}
+}
+
+static int init_kmem_cache_nodes(struct kmem_cache *s)
+{
+	int node;
+
+	for_each_node_state(node, N_NORMAL_MEMORY) {
+		struct kmem_cache_node *n;
+
+		if (slab_state == DOWN) {
+			early_kmem_cache_node_alloc(node);
+			continue;
+		}
+		n = kmem_cache_alloc_node(kmem_cache_node,
+						GFP_KERNEL, node);
+
+		if (!n) {
+			free_kmem_cache_nodes(s);
+			return 0;
+		}
+
+		s->node[node] = n;
+		init_kmem_cache_node(n);
+	}
+	return 1;
+}
+
+static void set_min_partial(struct kmem_cache *s, unsigned long min)
+{
+	if (min < MIN_PARTIAL)
+		min = MIN_PARTIAL;
+	else if (min > MAX_PARTIAL)
+		min = MAX_PARTIAL;
+	s->min_partial = min;
+}
+
+/*
+ * calculate_sizes() determines the order and the distribution of data within
+ * a slab object.
+ */
+static int calculate_sizes(struct kmem_cache *s, int forced_order)
+{
+	unsigned long flags = s->flags;
+	unsigned long size = s->object_size;
+	int order;
+
+	/*
+	 * Round up object size to the next word boundary. We can only
+	 * place the free pointer at word boundaries and this determines
+	 * the possible location of the free pointer.
+	 */
+	size = ALIGN(size, sizeof(void *));
+
+#ifdef CONFIG_SLUB_DEBUG
+	/*
+	 * Determine if we can poison the object itself. If the user of
+	 * the slab may touch the object after free or before allocation
+	 * then we should never poison the object itself.
+	 */
+	if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
+			!s->ctor)
+		s->flags |= __OBJECT_POISON;
+	else
+		s->flags &= ~__OBJECT_POISON;
+
+
+	/*
+	 * If we are Redzoning then check if there is some space between the
+	 * end of the object and the free pointer. If not then add an
+	 * additional word to have some bytes to store Redzone information.
+	 */
+	if ((flags & SLAB_RED_ZONE) && size == s->object_size)
+		size += sizeof(void *);
+#endif
+
+	/*
+	 * With that we have determined the number of bytes in actual use
+	 * by the object. This is the potential offset to the free pointer.
+	 */
+	s->inuse = size;
+
+	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
+		s->ctor)) {
+		/*
+		 * Relocate free pointer after the object if it is not
+		 * permitted to overwrite the first word of the object on
+		 * kmem_cache_free.
+		 *
+		 * This is the case if we do RCU, have a constructor or
+		 * destructor or are poisoning the objects.
+		 */
+		s->offset = size;
+		size += sizeof(void *);
+	}
+
+#ifdef CONFIG_SLUB_DEBUG
+	if (flags & SLAB_STORE_USER)
+		/*
+		 * Need to store information about allocs and frees after
+		 * the object.
+		 */
+		size += 2 * sizeof(struct track);
+
+	if (flags & SLAB_RED_ZONE)
+		/*
+		 * Add some empty padding so that we can catch
+		 * overwrites from earlier objects rather than let
+		 * tracking information or the free pointer be
+		 * corrupted if a user writes before the start
+		 * of the object.
+		 */
+		size += sizeof(void *);
+#endif
+
+	/*
+	 * SLUB stores one object immediately after another beginning from
+	 * offset 0. In order to align the objects we have to simply size
+	 * each object to conform to the alignment.
+	 */
+	size = ALIGN(size, s->align);
+	s->size = size;
+	if (forced_order >= 0)
+		order = forced_order;
+	else
+		order = calculate_order(size, s->reserved);
+
+	if (order < 0)
+		return 0;
+
+	s->allocflags = 0;
+	if (order)
+		s->allocflags |= __GFP_COMP;
+
+	if (s->flags & SLAB_CACHE_DMA)
+		s->allocflags |= GFP_DMA;
+
+	if (s->flags & SLAB_RECLAIM_ACCOUNT)
+		s->allocflags |= __GFP_RECLAIMABLE;
+
+	/*
+	 * Determine the number of objects per slab
+	 */
+	s->oo = oo_make(order, size, s->reserved);
+	s->min = oo_make(get_order(size), size, s->reserved);
+	if (oo_objects(s->oo) > oo_objects(s->max))
+		s->max = s->oo;
+
+	return !!oo_objects(s->oo);
+}
+
+static int kmem_cache_open(struct kmem_cache *s, unsigned long flags)
+{
+	s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor);
+	s->reserved = 0;
+
+	if (need_reserve_slab_rcu && (s->flags & SLAB_DESTROY_BY_RCU))
+		s->reserved = sizeof(struct rcu_head);
+
+	if (!calculate_sizes(s, -1))
+		goto error;
+	if (disable_higher_order_debug) {
+		/*
+		 * Disable debugging flags that store metadata if the min slab
+		 * order increased.
+		 */
+		if (get_order(s->size) > get_order(s->object_size)) {
+			s->flags &= ~DEBUG_METADATA_FLAGS;
+			s->offset = 0;
+			if (!calculate_sizes(s, -1))
+				goto error;
+		}
+	}
+
+#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
+    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
+	if (system_has_cmpxchg_double() && (s->flags & SLAB_DEBUG_FLAGS) == 0)
+		/* Enable fast mode */
+		s->flags |= __CMPXCHG_DOUBLE;
+#endif
+
+	/*
+	 * The larger the object size is, the more pages we want on the partial
+	 * list to avoid pounding the page allocator excessively.
+	 */
+	set_min_partial(s, ilog2(s->size) / 2);
+
+	/*
+	 * cpu_partial determined the maximum number of objects kept in the
+	 * per cpu partial lists of a processor.
+	 *
+	 * Per cpu partial lists mainly contain slabs that just have one
+	 * object freed. If they are used for allocation then they can be
+	 * filled up again with minimal effort. The slab will never hit the
+	 * per node partial lists and therefore no locking will be required.
+	 *
+	 * This setting also determines
+	 *
+	 * A) The number of objects from per cpu partial slabs dumped to the
+	 *    per node list when we reach the limit.
+	 * B) The number of objects in cpu partial slabs to extract from the
+	 *    per node list when we run out of per cpu objects. We only fetch
+	 *    50% to keep some capacity around for frees.
+	 */
+	if (!kmem_cache_has_cpu_partial(s))
+		s->cpu_partial = 0;
+	else if (s->size >= PAGE_SIZE)
+		s->cpu_partial = 2;
+	else if (s->size >= 1024)
+		s->cpu_partial = 6;
+	else if (s->size >= 256)
+		s->cpu_partial = 13;
+	else
+		s->cpu_partial = 30;
+
+#ifdef CONFIG_NUMA
+	s->remote_node_defrag_ratio = 1000;
+#endif
+	if (!init_kmem_cache_nodes(s))
+		goto error;
+
+	if (alloc_kmem_cache_cpus(s))
+		return 0;
+
+	free_kmem_cache_nodes(s);
+error:
+	if (flags & SLAB_PANIC)
+		panic("Cannot create slab %s size=%lu realsize=%u "
+			"order=%u offset=%u flags=%lx\n",
+			s->name, (unsigned long)s->size, s->size,
+			oo_order(s->oo), s->offset, flags);
+	return -EINVAL;
+}
+
+static void list_slab_objects(struct kmem_cache *s, struct page *page,
+							const char *text)
+{
+#ifdef CONFIG_SLUB_DEBUG
+	void *addr = page_address(page);
+	void *p;
+	unsigned long *map = kzalloc(BITS_TO_LONGS(page->objects) *
+				     sizeof(long), GFP_ATOMIC);
+	if (!map)
+		return;
+	slab_err(s, page, text, s->name);
+	slab_lock(page);
+
+	get_map(s, page, map);
+	for_each_object(p, s, addr, page->objects) {
+
+		if (!test_bit(slab_index(p, s, addr), map)) {
+			pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr);
+			print_tracking(s, p);
+		}
+	}
+	slab_unlock(page);
+	kfree(map);
+#endif
+}
+
+/*
+ * Attempt to free all partial slabs on a node.
+ * This is called from kmem_cache_close(). We must be the last thread
+ * using the cache and therefore we do not need to lock anymore.
+ */
+static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
+{
+	struct page *page, *h;
+
+	list_for_each_entry_safe(page, h, &n->partial, lru) {
+		if (!page->inuse) {
+			__remove_partial(n, page);
+			discard_slab(s, page);
+		} else {
+			list_slab_objects(s, page,
+			"Objects remaining in %s on kmem_cache_close()");
+		}
+	}
+}
+
+/*
+ * Release all resources used by a slab cache.
+ */
+static inline int kmem_cache_close(struct kmem_cache *s)
+{
+	int node;
+	struct kmem_cache_node *n;
+
+	flush_all(s);
+	/* Attempt to free all objects */
+	for_each_kmem_cache_node(s, node, n) {
+		free_partial(s, n);
+		if (n->nr_partial || slabs_node(s, node))
+			return 1;
+	}
+	free_percpu(s->cpu_slab);
+	free_kmem_cache_nodes(s);
+	return 0;
+}
+
+int __kmem_cache_shutdown(struct kmem_cache *s)
+{
+	return kmem_cache_close(s);
+}
+
+/********************************************************************
+ *		Kmalloc subsystem
+ *******************************************************************/
+
+static int __init setup_slub_min_order(char *str)
+{
+	get_option(&str, &slub_min_order);
+
+	return 1;
+}
+
+__setup("slub_min_order=", setup_slub_min_order);
+
+static int __init setup_slub_max_order(char *str)
+{
+	get_option(&str, &slub_max_order);
+	slub_max_order = min(slub_max_order, MAX_ORDER - 1);
+
+	return 1;
+}
+
+__setup("slub_max_order=", setup_slub_max_order);
+
+static int __init setup_slub_min_objects(char *str)
+{
+	get_option(&str, &slub_min_objects);
+
+	return 1;
+}
+
+__setup("slub_min_objects=", setup_slub_min_objects);
+
+void *__kmalloc(size_t size, gfp_t flags)
+{
+	struct kmem_cache *s;
+	void *ret;
+
+	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
+		return kmalloc_large(size, flags);
+
+	s = kmalloc_slab(size, flags);
+
+	if (unlikely(ZERO_OR_NULL_PTR(s)))
+		return s;
+
+	ret = slab_alloc(s, flags, _RET_IP_);
+
+	trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
+
+	kasan_kmalloc(s, ret, size);
+
+	return ret;
+}
+EXPORT_SYMBOL(__kmalloc);
+
+#ifdef CONFIG_NUMA
+static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
+{
+	struct page *page;
+	void *ptr = NULL;
+
+	flags |= __GFP_COMP | __GFP_NOTRACK;
+	page = alloc_kmem_pages_node(node, flags, get_order(size));
+	if (page)
+		ptr = page_address(page);
+
+	kmalloc_large_node_hook(ptr, size, flags);
+	return ptr;
+}
+
+void *__kmalloc_node(size_t size, gfp_t flags, int node)
+{
+	struct kmem_cache *s;
+	void *ret;
+
+	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
+		ret = kmalloc_large_node(size, flags, node);
+
+		trace_kmalloc_node(_RET_IP_, ret,
+				   size, PAGE_SIZE << get_order(size),
+				   flags, node);
+
+		return ret;
+	}
+
+	s = kmalloc_slab(size, flags);
+
+	if (unlikely(ZERO_OR_NULL_PTR(s)))
+		return s;
+
+	ret = slab_alloc_node(s, flags, node, _RET_IP_);
+
+	trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node);
+
+	kasan_kmalloc(s, ret, size);
+
+	return ret;
+}
+EXPORT_SYMBOL(__kmalloc_node);
+#endif
+
+static size_t __ksize(const void *object)
+{
+	struct page *page;
+
+	if (unlikely(object == ZERO_SIZE_PTR))
+		return 0;
+
+	page = virt_to_head_page(object);
+
+	if (unlikely(!PageSlab(page))) {
+		WARN_ON(!PageCompound(page));
+		return PAGE_SIZE << compound_order(page);
+	}
+
+	return slab_ksize(page->slab_cache);
+}
+
+size_t ksize(const void *object)
+{
+	size_t size = __ksize(object);
+	/* We assume that ksize callers could use whole allocated area,
+	   so we need unpoison this area. */
+	kasan_krealloc(object, size);
+	return size;
+}
+EXPORT_SYMBOL(ksize);
+
+void kfree(const void *x)
+{
+	struct page *page;
+	void *object = (void *)x;
+
+	trace_kfree(_RET_IP_, x);
+
+	if (unlikely(ZERO_OR_NULL_PTR(x)))
+		return;
+
+	page = virt_to_head_page(x);
+	if (unlikely(!PageSlab(page))) {
+		BUG_ON(!PageCompound(page));
+		kfree_hook(x);
+		__free_kmem_pages(page, compound_order(page));
+		return;
+	}
+	slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_);
+}
+EXPORT_SYMBOL(kfree);
+
+#define SHRINK_PROMOTE_MAX 32
+
+/*
+ * kmem_cache_shrink discards empty slabs and promotes the slabs filled
+ * up most to the head of the partial lists. New allocations will then
+ * fill those up and thus they can be removed from the partial lists.
+ *
+ * The slabs with the least items are placed last. This results in them
+ * being allocated from last increasing the chance that the last objects
+ * are freed in them.
+ */
+int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate)
+{
+	int node;
+	int i;
+	struct kmem_cache_node *n;
+	struct page *page;
+	struct page *t;
+	struct list_head discard;
+	struct list_head promote[SHRINK_PROMOTE_MAX];
+	unsigned long flags;
+	int ret = 0;
+
+	if (deactivate) {
+		/*
+		 * Disable empty slabs caching. Used to avoid pinning offline
+		 * memory cgroups by kmem pages that can be freed.
+		 */
+		s->cpu_partial = 0;
+		s->min_partial = 0;
+
+		/*
+		 * s->cpu_partial is checked locklessly (see put_cpu_partial),
+		 * so we have to make sure the change is visible.
+		 */
+		kick_all_cpus_sync();
+	}
+
+	flush_all(s);
+	for_each_kmem_cache_node(s, node, n) {
+		INIT_LIST_HEAD(&discard);
+		for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
+			INIT_LIST_HEAD(promote + i);
+
+		spin_lock_irqsave(&n->list_lock, flags);
+
+		/*
+		 * Build lists of slabs to discard or promote.
+		 *
+		 * Note that concurrent frees may occur while we hold the
+		 * list_lock. page->inuse here is the upper limit.
+		 */
+		list_for_each_entry_safe(page, t, &n->partial, lru) {
+			int free = page->objects - page->inuse;
+
+			/* Do not reread page->inuse */
+			barrier();
+
+			/* We do not keep full slabs on the list */
+			BUG_ON(free <= 0);
+
+			if (free == page->objects) {
+				list_move(&page->lru, &discard);
+				n->nr_partial--;
+			} else if (free <= SHRINK_PROMOTE_MAX)
+				list_move(&page->lru, promote + free - 1);
+		}
+
+		/*
+		 * Promote the slabs filled up most to the head of the
+		 * partial list.
+		 */
+		for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
+			list_splice(promote + i, &n->partial);
+
+		spin_unlock_irqrestore(&n->list_lock, flags);
+
+		/* Release empty slabs */
+		list_for_each_entry_safe(page, t, &discard, lru)
+			discard_slab(s, page);
+
+		if (slabs_node(s, node))
+			ret = 1;
+	}
+
+	return ret;
+}
+
+static int slab_mem_going_offline_callback(void *arg)
+{
+	struct kmem_cache *s;
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list)
+		__kmem_cache_shrink(s, false);
+	mutex_unlock(&slab_mutex);
+
+	return 0;
+}
+
+static void slab_mem_offline_callback(void *arg)
+{
+	struct kmem_cache_node *n;
+	struct kmem_cache *s;
+	struct memory_notify *marg = arg;
+	int offline_node;
+
+	offline_node = marg->status_change_nid_normal;
+
+	/*
+	 * If the node still has available memory. we need kmem_cache_node
+	 * for it yet.
+	 */
+	if (offline_node < 0)
+		return;
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list) {
+		n = get_node(s, offline_node);
+		if (n) {
+			/*
+			 * if n->nr_slabs > 0, slabs still exist on the node
+			 * that is going down. We were unable to free them,
+			 * and offline_pages() function shouldn't call this
+			 * callback. So, we must fail.
+			 */
+			BUG_ON(slabs_node(s, offline_node));
+
+			s->node[offline_node] = NULL;
+			kmem_cache_free(kmem_cache_node, n);
+		}
+	}
+	mutex_unlock(&slab_mutex);
+}
+
+static int slab_mem_going_online_callback(void *arg)
+{
+	struct kmem_cache_node *n;
+	struct kmem_cache *s;
+	struct memory_notify *marg = arg;
+	int nid = marg->status_change_nid_normal;
+	int ret = 0;
+
+	/*
+	 * If the node's memory is already available, then kmem_cache_node is
+	 * already created. Nothing to do.
+	 */
+	if (nid < 0)
+		return 0;
+
+	/*
+	 * We are bringing a node online. No memory is available yet. We must
+	 * allocate a kmem_cache_node structure in order to bring the node
+	 * online.
+	 */
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list) {
+		/*
+		 * XXX: kmem_cache_alloc_node will fallback to other nodes
+		 *      since memory is not yet available from the node that
+		 *      is brought up.
+		 */
+		n = kmem_cache_alloc(kmem_cache_node, GFP_KERNEL);
+		if (!n) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		init_kmem_cache_node(n);
+		s->node[nid] = n;
+	}
+out:
+	mutex_unlock(&slab_mutex);
+	return ret;
+}
+
+static int slab_memory_callback(struct notifier_block *self,
+				unsigned long action, void *arg)
+{
+	int ret = 0;
+
+	switch (action) {
+	case MEM_GOING_ONLINE:
+		ret = slab_mem_going_online_callback(arg);
+		break;
+	case MEM_GOING_OFFLINE:
+		ret = slab_mem_going_offline_callback(arg);
+		break;
+	case MEM_OFFLINE:
+	case MEM_CANCEL_ONLINE:
+		slab_mem_offline_callback(arg);
+		break;
+	case MEM_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	if (ret)
+		ret = notifier_from_errno(ret);
+	else
+		ret = NOTIFY_OK;
+	return ret;
+}
+
+static struct notifier_block slab_memory_callback_nb = {
+	.notifier_call = slab_memory_callback,
+	.priority = SLAB_CALLBACK_PRI,
+};
+
+/********************************************************************
+ *			Basic setup of slabs
+ *******************************************************************/
+
+/*
+ * Used for early kmem_cache structures that were allocated using
+ * the page allocator. Allocate them properly then fix up the pointers
+ * that may be pointing to the wrong kmem_cache structure.
+ */
+
+static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
+{
+	int node;
+	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
+	struct kmem_cache_node *n;
+
+	memcpy(s, static_cache, kmem_cache->object_size);
+
+	/*
+	 * This runs very early, and only the boot processor is supposed to be
+	 * up.  Even if it weren't true, IRQs are not up so we couldn't fire
+	 * IPIs around.
+	 */
+	__flush_cpu_slab(s, smp_processor_id());
+	for_each_kmem_cache_node(s, node, n) {
+		struct page *p;
+
+		list_for_each_entry(p, &n->partial, lru)
+			p->slab_cache = s;
+
+#ifdef CONFIG_SLUB_DEBUG
+		list_for_each_entry(p, &n->full, lru)
+			p->slab_cache = s;
+#endif
+	}
+	slab_init_memcg_params(s);
+	list_add(&s->list, &slab_caches);
+	return s;
+}
+
+void __init kmem_cache_init(void)
+{
+	static __initdata struct kmem_cache boot_kmem_cache,
+		boot_kmem_cache_node;
+
+	if (debug_guardpage_minorder())
+		slub_max_order = 0;
+
+	kmem_cache_node = &boot_kmem_cache_node;
+	kmem_cache = &boot_kmem_cache;
+
+	create_boot_cache(kmem_cache_node, "kmem_cache_node",
+		sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN);
+
+	register_hotmemory_notifier(&slab_memory_callback_nb);
+
+	/* Able to allocate the per node structures */
+	slab_state = PARTIAL;
+
+	create_boot_cache(kmem_cache, "kmem_cache",
+			offsetof(struct kmem_cache, node) +
+				nr_node_ids * sizeof(struct kmem_cache_node *),
+		       SLAB_HWCACHE_ALIGN);
+
+	kmem_cache = bootstrap(&boot_kmem_cache);
+
+	/*
+	 * Allocate kmem_cache_node properly from the kmem_cache slab.
+	 * kmem_cache_node is separately allocated so no need to
+	 * update any list pointers.
+	 */
+	kmem_cache_node = bootstrap(&boot_kmem_cache_node);
+
+	/* Now we can use the kmem_cache to allocate kmalloc slabs */
+	setup_kmalloc_cache_index_table();
+	create_kmalloc_caches(0);
+
+#ifdef CONFIG_SMP
+	register_cpu_notifier(&slab_notifier);
+#endif
+
+	pr_info("SLUB: HWalign=%d, Order=%d-%d, MinObjects=%d, CPUs=%d, Nodes=%d\n",
+		cache_line_size(),
+		slub_min_order, slub_max_order, slub_min_objects,
+		nr_cpu_ids, nr_node_ids);
+}
+
+void __init kmem_cache_init_late(void)
+{
+}
+
+struct kmem_cache *
+__kmem_cache_alias(const char *name, size_t size, size_t align,
+		   unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *s, *c;
+
+	s = find_mergeable(size, align, flags, name, ctor);
+	if (s) {
+		s->refcount++;
+
+		/*
+		 * Adjust the object sizes so that we clear
+		 * the complete object on kzalloc.
+		 */
+		s->object_size = max(s->object_size, (int)size);
+		s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
+
+		for_each_memcg_cache(c, s) {
+			c->object_size = s->object_size;
+			c->inuse = max_t(int, c->inuse,
+					 ALIGN(size, sizeof(void *)));
+		}
+
+		if (sysfs_slab_alias(s, name)) {
+			s->refcount--;
+			s = NULL;
+		}
+	}
+
+	return s;
+}
+
+int __kmem_cache_create(struct kmem_cache *s, unsigned long flags)
+{
+	int err;
+
+	err = kmem_cache_open(s, flags);
+	if (err)
+		return err;
+
+	/* Mutex is not taken during early boot */
+	if (slab_state <= UP)
+		return 0;
+
+	memcg_propagate_slab_attrs(s);
+	err = sysfs_slab_add(s);
+	if (err)
+		kmem_cache_close(s);
+
+	return err;
+}
+
+#ifdef CONFIG_SMP
+/*
+ * Use the cpu notifier to insure that the cpu slabs are flushed when
+ * necessary.
+ */
+static int slab_cpuup_callback(struct notifier_block *nfb,
+		unsigned long action, void *hcpu)
+{
+	long cpu = (long)hcpu;
+	struct kmem_cache *s;
+	unsigned long flags;
+
+	switch (action) {
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		mutex_lock(&slab_mutex);
+		list_for_each_entry(s, &slab_caches, list) {
+			local_irq_save(flags);
+			__flush_cpu_slab(s, cpu);
+			local_irq_restore(flags);
+		}
+		mutex_unlock(&slab_mutex);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block slab_notifier = {
+	.notifier_call = slab_cpuup_callback
+};
+
+#endif
+
+void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)
+{
+	struct kmem_cache *s;
+	void *ret;
+
+	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
+		return kmalloc_large(size, gfpflags);
+
+	s = kmalloc_slab(size, gfpflags);
+
+	if (unlikely(ZERO_OR_NULL_PTR(s)))
+		return s;
+
+	ret = slab_alloc(s, gfpflags, caller);
+
+	/* Honor the call site pointer we received. */
+	trace_kmalloc(caller, ret, size, s->size, gfpflags);
+
+	return ret;
+}
+
+#ifdef CONFIG_NUMA
+void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
+					int node, unsigned long caller)
+{
+	struct kmem_cache *s;
+	void *ret;
+
+	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
+		ret = kmalloc_large_node(size, gfpflags, node);
+
+		trace_kmalloc_node(caller, ret,
+				   size, PAGE_SIZE << get_order(size),
+				   gfpflags, node);
+
+		return ret;
+	}
+
+	s = kmalloc_slab(size, gfpflags);
+
+	if (unlikely(ZERO_OR_NULL_PTR(s)))
+		return s;
+
+	ret = slab_alloc_node(s, gfpflags, node, caller);
+
+	/* Honor the call site pointer we received. */
+	trace_kmalloc_node(caller, ret, size, s->size, gfpflags, node);
+
+	return ret;
+}
+#endif
+
+#ifdef CONFIG_SYSFS
+static int count_inuse(struct page *page)
+{
+	return page->inuse;
+}
+
+static int count_total(struct page *page)
+{
+	return page->objects;
+}
+#endif
+
+#ifdef CONFIG_SLUB_DEBUG
+static int validate_slab(struct kmem_cache *s, struct page *page,
+						unsigned long *map)
+{
+	void *p;
+	void *addr = page_address(page);
+
+	if (!check_slab(s, page) ||
+			!on_freelist(s, page, NULL))
+		return 0;
+
+	/* Now we know that a valid freelist exists */
+	bitmap_zero(map, page->objects);
+
+	get_map(s, page, map);
+	for_each_object(p, s, addr, page->objects) {
+		if (test_bit(slab_index(p, s, addr), map))
+			if (!check_object(s, page, p, SLUB_RED_INACTIVE))
+				return 0;
+	}
+
+	for_each_object(p, s, addr, page->objects)
+		if (!test_bit(slab_index(p, s, addr), map))
+			if (!check_object(s, page, p, SLUB_RED_ACTIVE))
+				return 0;
+	return 1;
+}
+
+static void validate_slab_slab(struct kmem_cache *s, struct page *page,
+						unsigned long *map)
+{
+	slab_lock(page);
+	validate_slab(s, page, map);
+	slab_unlock(page);
+}
+
+static int validate_slab_node(struct kmem_cache *s,
+		struct kmem_cache_node *n, unsigned long *map)
+{
+	unsigned long count = 0;
+	struct page *page;
+	unsigned long flags;
+
+	spin_lock_irqsave(&n->list_lock, flags);
+
+	list_for_each_entry(page, &n->partial, lru) {
+		validate_slab_slab(s, page, map);
+		count++;
+	}
+	if (count != n->nr_partial)
+		pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
+		       s->name, count, n->nr_partial);
+
+	if (!(s->flags & SLAB_STORE_USER))
+		goto out;
+
+	list_for_each_entry(page, &n->full, lru) {
+		validate_slab_slab(s, page, map);
+		count++;
+	}
+	if (count != atomic_long_read(&n->nr_slabs))
+		pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
+		       s->name, count, atomic_long_read(&n->nr_slabs));
+
+out:
+	spin_unlock_irqrestore(&n->list_lock, flags);
+	return count;
+}
+
+static long validate_slab_cache(struct kmem_cache *s)
+{
+	int node;
+	unsigned long count = 0;
+	unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
+				sizeof(unsigned long), GFP_KERNEL);
+	struct kmem_cache_node *n;
+
+	if (!map)
+		return -ENOMEM;
+
+	flush_all(s);
+	for_each_kmem_cache_node(s, node, n)
+		count += validate_slab_node(s, n, map);
+	kfree(map);
+	return count;
+}
+/*
+ * Generate lists of code addresses where slabcache objects are allocated
+ * and freed.
+ */
+
+struct location {
+	unsigned long count;
+	unsigned long addr;
+	long long sum_time;
+	long min_time;
+	long max_time;
+	long min_pid;
+	long max_pid;
+	DECLARE_BITMAP(cpus, NR_CPUS);
+	nodemask_t nodes;
+};
+
+struct loc_track {
+	unsigned long max;
+	unsigned long count;
+	struct location *loc;
+};
+
+static void free_loc_track(struct loc_track *t)
+{
+	if (t->max)
+		free_pages((unsigned long)t->loc,
+			get_order(sizeof(struct location) * t->max));
+}
+
+static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
+{
+	struct location *l;
+	int order;
+
+	order = get_order(sizeof(struct location) * max);
+
+	l = (void *)__get_free_pages(flags, order);
+	if (!l)
+		return 0;
+
+	if (t->count) {
+		memcpy(l, t->loc, sizeof(struct location) * t->count);
+		free_loc_track(t);
+	}
+	t->max = max;
+	t->loc = l;
+	return 1;
+}
+
+static int add_location(struct loc_track *t, struct kmem_cache *s,
+				const struct track *track)
+{
+	long start, end, pos;
+	struct location *l;
+	unsigned long caddr;
+	unsigned long age = jiffies - track->when;
+
+	start = -1;
+	end = t->count;
+
+	for ( ; ; ) {
+		pos = start + (end - start + 1) / 2;
+
+		/*
+		 * There is nothing at "end". If we end up there
+		 * we need to add something to before end.
+		 */
+		if (pos == end)
+			break;
+
+		caddr = t->loc[pos].addr;
+		if (track->addr == caddr) {
+
+			l = &t->loc[pos];
+			l->count++;
+			if (track->when) {
+				l->sum_time += age;
+				if (age < l->min_time)
+					l->min_time = age;
+				if (age > l->max_time)
+					l->max_time = age;
+
+				if (track->pid < l->min_pid)
+					l->min_pid = track->pid;
+				if (track->pid > l->max_pid)
+					l->max_pid = track->pid;
+
+				cpumask_set_cpu(track->cpu,
+						to_cpumask(l->cpus));
+			}
+			node_set(page_to_nid(virt_to_page(track)), l->nodes);
+			return 1;
+		}
+
+		if (track->addr < caddr)
+			end = pos;
+		else
+			start = pos;
+	}
+
+	/*
+	 * Not found. Insert new tracking element.
+	 */
+	if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
+		return 0;
+
+	l = t->loc + pos;
+	if (pos < t->count)
+		memmove(l + 1, l,
+			(t->count - pos) * sizeof(struct location));
+	t->count++;
+	l->count = 1;
+	l->addr = track->addr;
+	l->sum_time = age;
+	l->min_time = age;
+	l->max_time = age;
+	l->min_pid = track->pid;
+	l->max_pid = track->pid;
+	cpumask_clear(to_cpumask(l->cpus));
+	cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
+	nodes_clear(l->nodes);
+	node_set(page_to_nid(virt_to_page(track)), l->nodes);
+	return 1;
+}
+
+static void process_slab(struct loc_track *t, struct kmem_cache *s,
+		struct page *page, enum track_item alloc,
+		unsigned long *map)
+{
+	void *addr = page_address(page);
+	void *p;
+
+	bitmap_zero(map, page->objects);
+	get_map(s, page, map);
+
+	for_each_object(p, s, addr, page->objects)
+		if (!test_bit(slab_index(p, s, addr), map))
+			add_location(t, s, get_track(s, p, alloc));
+}
+
+static int list_locations(struct kmem_cache *s, char *buf,
+					enum track_item alloc)
+{
+	int len = 0;
+	unsigned long i;
+	struct loc_track t = { 0, 0, NULL };
+	int node;
+	unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
+				     sizeof(unsigned long), GFP_KERNEL);
+	struct kmem_cache_node *n;
+
+	if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
+				     GFP_TEMPORARY)) {
+		kfree(map);
+		return sprintf(buf, "Out of memory\n");
+	}
+	/* Push back cpu slabs */
+	flush_all(s);
+
+	for_each_kmem_cache_node(s, node, n) {
+		unsigned long flags;
+		struct page *page;
+
+		if (!atomic_long_read(&n->nr_slabs))
+			continue;
+
+		spin_lock_irqsave(&n->list_lock, flags);
+		list_for_each_entry(page, &n->partial, lru)
+			process_slab(&t, s, page, alloc, map);
+		list_for_each_entry(page, &n->full, lru)
+			process_slab(&t, s, page, alloc, map);
+		spin_unlock_irqrestore(&n->list_lock, flags);
+	}
+
+	for (i = 0; i < t.count; i++) {
+		struct location *l = &t.loc[i];
+
+		if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100)
+			break;
+		len += sprintf(buf + len, "%7ld ", l->count);
+
+		if (l->addr)
+			len += sprintf(buf + len, "%pS", (void *)l->addr);
+		else
+			len += sprintf(buf + len, "<not-available>");
+
+		if (l->sum_time != l->min_time) {
+			len += sprintf(buf + len, " age=%ld/%ld/%ld",
+				l->min_time,
+				(long)div_u64(l->sum_time, l->count),
+				l->max_time);
+		} else
+			len += sprintf(buf + len, " age=%ld",
+				l->min_time);
+
+		if (l->min_pid != l->max_pid)
+			len += sprintf(buf + len, " pid=%ld-%ld",
+				l->min_pid, l->max_pid);
+		else
+			len += sprintf(buf + len, " pid=%ld",
+				l->min_pid);
+
+		if (num_online_cpus() > 1 &&
+				!cpumask_empty(to_cpumask(l->cpus)) &&
+				len < PAGE_SIZE - 60)
+			len += scnprintf(buf + len, PAGE_SIZE - len - 50,
+					 " cpus=%*pbl",
+					 cpumask_pr_args(to_cpumask(l->cpus)));
+
+		if (nr_online_nodes > 1 && !nodes_empty(l->nodes) &&
+				len < PAGE_SIZE - 60)
+			len += scnprintf(buf + len, PAGE_SIZE - len - 50,
+					 " nodes=%*pbl",
+					 nodemask_pr_args(&l->nodes));
+
+		len += sprintf(buf + len, "\n");
+	}
+
+	free_loc_track(&t);
+	kfree(map);
+	if (!t.count)
+		len += sprintf(buf, "No data\n");
+	return len;
+}
+#endif
+
+#ifdef SLUB_RESILIENCY_TEST
+static void __init resiliency_test(void)
+{
+	u8 *p;
+
+	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
+
+	pr_err("SLUB resiliency testing\n");
+	pr_err("-----------------------\n");
+	pr_err("A. Corruption after allocation\n");
+
+	p = kzalloc(16, GFP_KERNEL);
+	p[16] = 0x12;
+	pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n",
+	       p + 16);
+
+	validate_slab_cache(kmalloc_caches[4]);
+
+	/* Hmmm... The next two are dangerous */
+	p = kzalloc(32, GFP_KERNEL);
+	p[32 + sizeof(void *)] = 0x34;
+	pr_err("\n2. kmalloc-32: Clobber next pointer/next slab 0x34 -> -0x%p\n",
+	       p);
+	pr_err("If allocated object is overwritten then not detectable\n\n");
+
+	validate_slab_cache(kmalloc_caches[5]);
+	p = kzalloc(64, GFP_KERNEL);
+	p += 64 + (get_cycles() & 0xff) * sizeof(void *);
+	*p = 0x56;
+	pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
+	       p);
+	pr_err("If allocated object is overwritten then not detectable\n\n");
+	validate_slab_cache(kmalloc_caches[6]);
+
+	pr_err("\nB. Corruption after free\n");
+	p = kzalloc(128, GFP_KERNEL);
+	kfree(p);
+	*p = 0x78;
+	pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
+	validate_slab_cache(kmalloc_caches[7]);
+
+	p = kzalloc(256, GFP_KERNEL);
+	kfree(p);
+	p[50] = 0x9a;
+	pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
+	validate_slab_cache(kmalloc_caches[8]);
+
+	p = kzalloc(512, GFP_KERNEL);
+	kfree(p);
+	p[512] = 0xab;
+	pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
+	validate_slab_cache(kmalloc_caches[9]);
+}
+#else
+#ifdef CONFIG_SYSFS
+static void resiliency_test(void) {};
+#endif
+#endif
+
+#ifdef CONFIG_SYSFS
+enum slab_stat_type {
+	SL_ALL,			/* All slabs */
+	SL_PARTIAL,		/* Only partially allocated slabs */
+	SL_CPU,			/* Only slabs used for cpu caches */
+	SL_OBJECTS,		/* Determine allocated objects not slabs */
+	SL_TOTAL		/* Determine object capacity not slabs */
+};
+
+#define SO_ALL		(1 << SL_ALL)
+#define SO_PARTIAL	(1 << SL_PARTIAL)
+#define SO_CPU		(1 << SL_CPU)
+#define SO_OBJECTS	(1 << SL_OBJECTS)
+#define SO_TOTAL	(1 << SL_TOTAL)
+
+static ssize_t show_slab_objects(struct kmem_cache *s,
+			    char *buf, unsigned long flags)
+{
+	unsigned long total = 0;
+	int node;
+	int x;
+	unsigned long *nodes;
+
+	nodes = kzalloc(sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
+	if (!nodes)
+		return -ENOMEM;
+
+	if (flags & SO_CPU) {
+		int cpu;
+
+		for_each_possible_cpu(cpu) {
+			struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
+							       cpu);
+			int node;
+			struct page *page;
+
+			page = READ_ONCE(c->page);
+			if (!page)
+				continue;
+
+			node = page_to_nid(page);
+			if (flags & SO_TOTAL)
+				x = page->objects;
+			else if (flags & SO_OBJECTS)
+				x = page->inuse;
+			else
+				x = 1;
+
+			total += x;
+			nodes[node] += x;
+
+			page = READ_ONCE(c->partial);
+			if (page) {
+				node = page_to_nid(page);
+				if (flags & SO_TOTAL)
+					WARN_ON_ONCE(1);
+				else if (flags & SO_OBJECTS)
+					WARN_ON_ONCE(1);
+				else
+					x = page->pages;
+				total += x;
+				nodes[node] += x;
+			}
+		}
+	}
+
+	get_online_mems();
+#ifdef CONFIG_SLUB_DEBUG
+	if (flags & SO_ALL) {
+		struct kmem_cache_node *n;
+
+		for_each_kmem_cache_node(s, node, n) {
+
+			if (flags & SO_TOTAL)
+				x = atomic_long_read(&n->total_objects);
+			else if (flags & SO_OBJECTS)
+				x = atomic_long_read(&n->total_objects) -
+					count_partial(n, count_free);
+			else
+				x = atomic_long_read(&n->nr_slabs);
+			total += x;
+			nodes[node] += x;
+		}
+
+	} else
+#endif
+	if (flags & SO_PARTIAL) {
+		struct kmem_cache_node *n;
+
+		for_each_kmem_cache_node(s, node, n) {
+			if (flags & SO_TOTAL)
+				x = count_partial(n, count_total);
+			else if (flags & SO_OBJECTS)
+				x = count_partial(n, count_inuse);
+			else
+				x = n->nr_partial;
+			total += x;
+			nodes[node] += x;
+		}
+	}
+	x = sprintf(buf, "%lu", total);
+#ifdef CONFIG_NUMA
+	for (node = 0; node < nr_node_ids; node++)
+		if (nodes[node])
+			x += sprintf(buf + x, " N%d=%lu",
+					node, nodes[node]);
+#endif
+	put_online_mems();
+	kfree(nodes);
+	return x + sprintf(buf + x, "\n");
+}
+
+#ifdef CONFIG_SLUB_DEBUG
+static int any_slab_objects(struct kmem_cache *s)
+{
+	int node;
+	struct kmem_cache_node *n;
+
+	for_each_kmem_cache_node(s, node, n)
+		if (atomic_long_read(&n->total_objects))
+			return 1;
+
+	return 0;
+}
+#endif
+
+#define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
+#define to_slab(n) container_of(n, struct kmem_cache, kobj)
+
+struct slab_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct kmem_cache *s, char *buf);
+	ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
+};
+
+#define SLAB_ATTR_RO(_name) \
+	static struct slab_attribute _name##_attr = \
+	__ATTR(_name, 0400, _name##_show, NULL)
+
+#define SLAB_ATTR(_name) \
+	static struct slab_attribute _name##_attr =  \
+	__ATTR(_name, 0600, _name##_show, _name##_store)
+
+static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->size);
+}
+SLAB_ATTR_RO(slab_size);
+
+static ssize_t align_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->align);
+}
+SLAB_ATTR_RO(align);
+
+static ssize_t object_size_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->object_size);
+}
+SLAB_ATTR_RO(object_size);
+
+static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", oo_objects(s->oo));
+}
+SLAB_ATTR_RO(objs_per_slab);
+
+static ssize_t order_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	unsigned long order;
+	int err;
+
+	err = kstrtoul(buf, 10, &order);
+	if (err)
+		return err;
+
+	if (order > slub_max_order || order < slub_min_order)
+		return -EINVAL;
+
+	calculate_sizes(s, order);
+	return length;
+}
+
+static ssize_t order_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", oo_order(s->oo));
+}
+SLAB_ATTR(order);
+
+static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%lu\n", s->min_partial);
+}
+
+static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
+				 size_t length)
+{
+	unsigned long min;
+	int err;
+
+	err = kstrtoul(buf, 10, &min);
+	if (err)
+		return err;
+
+	set_min_partial(s, min);
+	return length;
+}
+SLAB_ATTR(min_partial);
+
+static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%u\n", s->cpu_partial);
+}
+
+static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
+				 size_t length)
+{
+	unsigned long objects;
+	int err;
+
+	err = kstrtoul(buf, 10, &objects);
+	if (err)
+		return err;
+	if (objects && !kmem_cache_has_cpu_partial(s))
+		return -EINVAL;
+
+	s->cpu_partial = objects;
+	flush_all(s);
+	return length;
+}
+SLAB_ATTR(cpu_partial);
+
+static ssize_t ctor_show(struct kmem_cache *s, char *buf)
+{
+	if (!s->ctor)
+		return 0;
+	return sprintf(buf, "%pS\n", s->ctor);
+}
+SLAB_ATTR_RO(ctor);
+
+static ssize_t aliases_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1);
+}
+SLAB_ATTR_RO(aliases);
+
+static ssize_t partial_show(struct kmem_cache *s, char *buf)
+{
+	return show_slab_objects(s, buf, SO_PARTIAL);
+}
+SLAB_ATTR_RO(partial);
+
+static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
+{
+	return show_slab_objects(s, buf, SO_CPU);
+}
+SLAB_ATTR_RO(cpu_slabs);
+
+static ssize_t objects_show(struct kmem_cache *s, char *buf)
+{
+	return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS);
+}
+SLAB_ATTR_RO(objects);
+
+static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
+{
+	return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS);
+}
+SLAB_ATTR_RO(objects_partial);
+
+static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
+{
+	int objects = 0;
+	int pages = 0;
+	int cpu;
+	int len;
+
+	for_each_online_cpu(cpu) {
+		struct page *page = per_cpu_ptr(s->cpu_slab, cpu)->partial;
+
+		if (page) {
+			pages += page->pages;
+			objects += page->pobjects;
+		}
+	}
+
+	len = sprintf(buf, "%d(%d)", objects, pages);
+
+#ifdef CONFIG_SMP
+	for_each_online_cpu(cpu) {
+		struct page *page = per_cpu_ptr(s->cpu_slab, cpu) ->partial;
+
+		if (page && len < PAGE_SIZE - 20)
+			len += sprintf(buf + len, " C%d=%d(%d)", cpu,
+				page->pobjects, page->pages);
+	}
+#endif
+	return len + sprintf(buf + len, "\n");
+}
+SLAB_ATTR_RO(slabs_cpu_partial);
+
+static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
+}
+
+static ssize_t reclaim_account_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	s->flags &= ~SLAB_RECLAIM_ACCOUNT;
+	if (buf[0] == '1')
+		s->flags |= SLAB_RECLAIM_ACCOUNT;
+	return length;
+}
+SLAB_ATTR(reclaim_account);
+
+static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
+}
+SLAB_ATTR_RO(hwcache_align);
+
+#ifdef CONFIG_ZONE_DMA
+static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
+}
+SLAB_ATTR_RO(cache_dma);
+#endif
+
+static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
+}
+SLAB_ATTR_RO(destroy_by_rcu);
+
+static ssize_t reserved_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->reserved);
+}
+SLAB_ATTR_RO(reserved);
+
+#ifdef CONFIG_SLUB_DEBUG
+static ssize_t slabs_show(struct kmem_cache *s, char *buf)
+{
+	return show_slab_objects(s, buf, SO_ALL);
+}
+SLAB_ATTR_RO(slabs);
+
+static ssize_t total_objects_show(struct kmem_cache *s, char *buf)
+{
+	return show_slab_objects(s, buf, SO_ALL|SO_TOTAL);
+}
+SLAB_ATTR_RO(total_objects);
+
+static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DEBUG_FREE));
+}
+
+static ssize_t sanity_checks_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	s->flags &= ~SLAB_DEBUG_FREE;
+	if (buf[0] == '1') {
+		s->flags &= ~__CMPXCHG_DOUBLE;
+		s->flags |= SLAB_DEBUG_FREE;
+	}
+	return length;
+}
+SLAB_ATTR(sanity_checks);
+
+static ssize_t trace_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
+}
+
+static ssize_t trace_store(struct kmem_cache *s, const char *buf,
+							size_t length)
+{
+	/*
+	 * Tracing a merged cache is going to give confusing results
+	 * as well as cause other issues like converting a mergeable
+	 * cache into an umergeable one.
+	 */
+	if (s->refcount > 1)
+		return -EINVAL;
+
+	s->flags &= ~SLAB_TRACE;
+	if (buf[0] == '1') {
+		s->flags &= ~__CMPXCHG_DOUBLE;
+		s->flags |= SLAB_TRACE;
+	}
+	return length;
+}
+SLAB_ATTR(trace);
+
+static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
+}
+
+static ssize_t red_zone_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	if (any_slab_objects(s))
+		return -EBUSY;
+
+	s->flags &= ~SLAB_RED_ZONE;
+	if (buf[0] == '1') {
+		s->flags &= ~__CMPXCHG_DOUBLE;
+		s->flags |= SLAB_RED_ZONE;
+	}
+	calculate_sizes(s, -1);
+	return length;
+}
+SLAB_ATTR(red_zone);
+
+static ssize_t poison_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
+}
+
+static ssize_t poison_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	if (any_slab_objects(s))
+		return -EBUSY;
+
+	s->flags &= ~SLAB_POISON;
+	if (buf[0] == '1') {
+		s->flags &= ~__CMPXCHG_DOUBLE;
+		s->flags |= SLAB_POISON;
+	}
+	calculate_sizes(s, -1);
+	return length;
+}
+SLAB_ATTR(poison);
+
+static ssize_t store_user_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
+}
+
+static ssize_t store_user_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	if (any_slab_objects(s))
+		return -EBUSY;
+
+	s->flags &= ~SLAB_STORE_USER;
+	if (buf[0] == '1') {
+		s->flags &= ~__CMPXCHG_DOUBLE;
+		s->flags |= SLAB_STORE_USER;
+	}
+	calculate_sizes(s, -1);
+	return length;
+}
+SLAB_ATTR(store_user);
+
+static ssize_t validate_show(struct kmem_cache *s, char *buf)
+{
+	return 0;
+}
+
+static ssize_t validate_store(struct kmem_cache *s,
+			const char *buf, size_t length)
+{
+	int ret = -EINVAL;
+
+	if (buf[0] == '1') {
+		ret = validate_slab_cache(s);
+		if (ret >= 0)
+			ret = length;
+	}
+	return ret;
+}
+SLAB_ATTR(validate);
+
+static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
+{
+	if (!(s->flags & SLAB_STORE_USER))
+		return -ENOSYS;
+	return list_locations(s, buf, TRACK_ALLOC);
+}
+SLAB_ATTR_RO(alloc_calls);
+
+static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
+{
+	if (!(s->flags & SLAB_STORE_USER))
+		return -ENOSYS;
+	return list_locations(s, buf, TRACK_FREE);
+}
+SLAB_ATTR_RO(free_calls);
+#endif /* CONFIG_SLUB_DEBUG */
+
+#ifdef CONFIG_FAILSLAB
+static ssize_t failslab_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
+}
+
+static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
+							size_t length)
+{
+	if (s->refcount > 1)
+		return -EINVAL;
+
+	s->flags &= ~SLAB_FAILSLAB;
+	if (buf[0] == '1')
+		s->flags |= SLAB_FAILSLAB;
+	return length;
+}
+SLAB_ATTR(failslab);
+#endif
+
+static ssize_t shrink_show(struct kmem_cache *s, char *buf)
+{
+	return 0;
+}
+
+static ssize_t shrink_store(struct kmem_cache *s,
+			const char *buf, size_t length)
+{
+	if (buf[0] == '1')
+		kmem_cache_shrink(s);
+	else
+		return -EINVAL;
+	return length;
+}
+SLAB_ATTR(shrink);
+
+#ifdef CONFIG_NUMA
+static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->remote_node_defrag_ratio / 10);
+}
+
+static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	unsigned long ratio;
+	int err;
+
+	err = kstrtoul(buf, 10, &ratio);
+	if (err)
+		return err;
+
+	if (ratio <= 100)
+		s->remote_node_defrag_ratio = ratio * 10;
+
+	return length;
+}
+SLAB_ATTR(remote_node_defrag_ratio);
+#endif
+
+#ifdef CONFIG_SLUB_STATS
+static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
+{
+	unsigned long sum  = 0;
+	int cpu;
+	int len;
+	int *data = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
+
+	if (!data)
+		return -ENOMEM;
+
+	for_each_online_cpu(cpu) {
+		unsigned x = per_cpu_ptr(s->cpu_slab, cpu)->stat[si];
+
+		data[cpu] = x;
+		sum += x;
+	}
+
+	len = sprintf(buf, "%lu", sum);
+
+#ifdef CONFIG_SMP
+	for_each_online_cpu(cpu) {
+		if (data[cpu] && len < PAGE_SIZE - 20)
+			len += sprintf(buf + len, " C%d=%u", cpu, data[cpu]);
+	}
+#endif
+	kfree(data);
+	return len + sprintf(buf + len, "\n");
+}
+
+static void clear_stat(struct kmem_cache *s, enum stat_item si)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0;
+}
+
+#define STAT_ATTR(si, text) 					\
+static ssize_t text##_show(struct kmem_cache *s, char *buf)	\
+{								\
+	return show_stat(s, buf, si);				\
+}								\
+static ssize_t text##_store(struct kmem_cache *s,		\
+				const char *buf, size_t length)	\
+{								\
+	if (buf[0] != '0')					\
+		return -EINVAL;					\
+	clear_stat(s, si);					\
+	return length;						\
+}								\
+SLAB_ATTR(text);						\
+
+STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
+STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);
+STAT_ATTR(FREE_FASTPATH, free_fastpath);
+STAT_ATTR(FREE_SLOWPATH, free_slowpath);
+STAT_ATTR(FREE_FROZEN, free_frozen);
+STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);
+STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
+STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
+STAT_ATTR(ALLOC_SLAB, alloc_slab);
+STAT_ATTR(ALLOC_REFILL, alloc_refill);
+STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
+STAT_ATTR(FREE_SLAB, free_slab);
+STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
+STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
+STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
+STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
+STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
+STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
+STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
+STAT_ATTR(ORDER_FALLBACK, order_fallback);
+STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
+STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
+STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
+STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
+STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
+STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
+#endif
+
+static struct attribute *slab_attrs[] = {
+	&slab_size_attr.attr,
+	&object_size_attr.attr,
+	&objs_per_slab_attr.attr,
+	&order_attr.attr,
+	&min_partial_attr.attr,
+	&cpu_partial_attr.attr,
+	&objects_attr.attr,
+	&objects_partial_attr.attr,
+	&partial_attr.attr,
+	&cpu_slabs_attr.attr,
+	&ctor_attr.attr,
+	&aliases_attr.attr,
+	&align_attr.attr,
+	&hwcache_align_attr.attr,
+	&reclaim_account_attr.attr,
+	&destroy_by_rcu_attr.attr,
+	&shrink_attr.attr,
+	&reserved_attr.attr,
+	&slabs_cpu_partial_attr.attr,
+#ifdef CONFIG_SLUB_DEBUG
+	&total_objects_attr.attr,
+	&slabs_attr.attr,
+	&sanity_checks_attr.attr,
+	&trace_attr.attr,
+	&red_zone_attr.attr,
+	&poison_attr.attr,
+	&store_user_attr.attr,
+	&validate_attr.attr,
+	&alloc_calls_attr.attr,
+	&free_calls_attr.attr,
+#endif
+#ifdef CONFIG_ZONE_DMA
+	&cache_dma_attr.attr,
+#endif
+#ifdef CONFIG_NUMA
+	&remote_node_defrag_ratio_attr.attr,
+#endif
+#ifdef CONFIG_SLUB_STATS
+	&alloc_fastpath_attr.attr,
+	&alloc_slowpath_attr.attr,
+	&free_fastpath_attr.attr,
+	&free_slowpath_attr.attr,
+	&free_frozen_attr.attr,
+	&free_add_partial_attr.attr,
+	&free_remove_partial_attr.attr,
+	&alloc_from_partial_attr.attr,
+	&alloc_slab_attr.attr,
+	&alloc_refill_attr.attr,
+	&alloc_node_mismatch_attr.attr,
+	&free_slab_attr.attr,
+	&cpuslab_flush_attr.attr,
+	&deactivate_full_attr.attr,
+	&deactivate_empty_attr.attr,
+	&deactivate_to_head_attr.attr,
+	&deactivate_to_tail_attr.attr,
+	&deactivate_remote_frees_attr.attr,
+	&deactivate_bypass_attr.attr,
+	&order_fallback_attr.attr,
+	&cmpxchg_double_fail_attr.attr,
+	&cmpxchg_double_cpu_fail_attr.attr,
+	&cpu_partial_alloc_attr.attr,
+	&cpu_partial_free_attr.attr,
+	&cpu_partial_node_attr.attr,
+	&cpu_partial_drain_attr.attr,
+#endif
+#ifdef CONFIG_FAILSLAB
+	&failslab_attr.attr,
+#endif
+
+	NULL
+};
+
+static struct attribute_group slab_attr_group = {
+	.attrs = slab_attrs,
+};
+
+static ssize_t slab_attr_show(struct kobject *kobj,
+				struct attribute *attr,
+				char *buf)
+{
+	struct slab_attribute *attribute;
+	struct kmem_cache *s;
+	int err;
+
+	attribute = to_slab_attr(attr);
+	s = to_slab(kobj);
+
+	if (!attribute->show)
+		return -EIO;
+
+	err = attribute->show(s, buf);
+
+	return err;
+}
+
+static ssize_t slab_attr_store(struct kobject *kobj,
+				struct attribute *attr,
+				const char *buf, size_t len)
+{
+	struct slab_attribute *attribute;
+	struct kmem_cache *s;
+	int err;
+
+	attribute = to_slab_attr(attr);
+	s = to_slab(kobj);
+
+	if (!attribute->store)
+		return -EIO;
+
+	err = attribute->store(s, buf, len);
+#ifdef CONFIG_MEMCG_KMEM
+	if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
+		struct kmem_cache *c;
+
+		mutex_lock(&slab_mutex);
+		if (s->max_attr_size < len)
+			s->max_attr_size = len;
+
+		/*
+		 * This is a best effort propagation, so this function's return
+		 * value will be determined by the parent cache only. This is
+		 * basically because not all attributes will have a well
+		 * defined semantics for rollbacks - most of the actions will
+		 * have permanent effects.
+		 *
+		 * Returning the error value of any of the children that fail
+		 * is not 100 % defined, in the sense that users seeing the
+		 * error code won't be able to know anything about the state of
+		 * the cache.
+		 *
+		 * Only returning the error code for the parent cache at least
+		 * has well defined semantics. The cache being written to
+		 * directly either failed or succeeded, in which case we loop
+		 * through the descendants with best-effort propagation.
+		 */
+		for_each_memcg_cache(c, s)
+			attribute->store(c, buf, len);
+		mutex_unlock(&slab_mutex);
+	}
+#endif
+	return err;
+}
+
+static void memcg_propagate_slab_attrs(struct kmem_cache *s)
+{
+#ifdef CONFIG_MEMCG_KMEM
+	int i;
+	char *buffer = NULL;
+	struct kmem_cache *root_cache;
+
+	if (is_root_cache(s))
+		return;
+
+	root_cache = s->memcg_params.root_cache;
+
+	/*
+	 * This mean this cache had no attribute written. Therefore, no point
+	 * in copying default values around
+	 */
+	if (!root_cache->max_attr_size)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
+		char mbuf[64];
+		char *buf;
+		struct slab_attribute *attr = to_slab_attr(slab_attrs[i]);
+		ssize_t len;
+
+		if (!attr || !attr->store || !attr->show)
+			continue;
+
+		/*
+		 * It is really bad that we have to allocate here, so we will
+		 * do it only as a fallback. If we actually allocate, though,
+		 * we can just use the allocated buffer until the end.
+		 *
+		 * Most of the slub attributes will tend to be very small in
+		 * size, but sysfs allows buffers up to a page, so they can
+		 * theoretically happen.
+		 */
+		if (buffer)
+			buf = buffer;
+		else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf))
+			buf = mbuf;
+		else {
+			buffer = (char *) get_zeroed_page(GFP_KERNEL);
+			if (WARN_ON(!buffer))
+				continue;
+			buf = buffer;
+		}
+
+		len = attr->show(root_cache, buf);
+		if (len > 0)
+			attr->store(s, buf, len);
+	}
+
+	if (buffer)
+		free_page((unsigned long)buffer);
+#endif
+}
+
+static void kmem_cache_release(struct kobject *k)
+{
+	slab_kmem_cache_release(to_slab(k));
+}
+
+static const struct sysfs_ops slab_sysfs_ops = {
+	.show = slab_attr_show,
+	.store = slab_attr_store,
+};
+
+static struct kobj_type slab_ktype = {
+	.sysfs_ops = &slab_sysfs_ops,
+	.release = kmem_cache_release,
+};
+
+static int uevent_filter(struct kset *kset, struct kobject *kobj)
+{
+	struct kobj_type *ktype = get_ktype(kobj);
+
+	if (ktype == &slab_ktype)
+		return 1;
+	return 0;
+}
+
+static const struct kset_uevent_ops slab_uevent_ops = {
+	.filter = uevent_filter,
+};
+
+static struct kset *slab_kset;
+
+static inline struct kset *cache_kset(struct kmem_cache *s)
+{
+#ifdef CONFIG_MEMCG_KMEM
+	if (!is_root_cache(s))
+		return s->memcg_params.root_cache->memcg_kset;
+#endif
+	return slab_kset;
+}
+
+#define ID_STR_LENGTH 64
+
+/* Create a unique string id for a slab cache:
+ *
+ * Format	:[flags-]size
+ */
+static char *create_unique_id(struct kmem_cache *s)
+{
+	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
+	char *p = name;
+
+	BUG_ON(!name);
+
+	*p++ = ':';
+	/*
+	 * First flags affecting slabcache operations. We will only
+	 * get here for aliasable slabs so we do not need to support
+	 * too many flags. The flags here must cover all flags that
+	 * are matched during merging to guarantee that the id is
+	 * unique.
+	 */
+	if (s->flags & SLAB_CACHE_DMA)
+		*p++ = 'd';
+	if (s->flags & SLAB_RECLAIM_ACCOUNT)
+		*p++ = 'a';
+	if (s->flags & SLAB_DEBUG_FREE)
+		*p++ = 'F';
+	if (!(s->flags & SLAB_NOTRACK))
+		*p++ = 't';
+	if (p != name + 1)
+		*p++ = '-';
+	p += sprintf(p, "%07d", s->size);
+
+	BUG_ON(p > name + ID_STR_LENGTH - 1);
+	return name;
+}
+
+static int sysfs_slab_add(struct kmem_cache *s)
+{
+	int err;
+	const char *name;
+	int unmergeable = slab_unmergeable(s);
+
+	if (unmergeable) {
+		/*
+		 * Slabcache can never be merged so we can use the name proper.
+		 * This is typically the case for debug situations. In that
+		 * case we can catch duplicate names easily.
+		 */
+		sysfs_remove_link(&slab_kset->kobj, s->name);
+		name = s->name;
+	} else {
+		/*
+		 * Create a unique name for the slab as a target
+		 * for the symlinks.
+		 */
+		name = create_unique_id(s);
+	}
+
+	s->kobj.kset = cache_kset(s);
+	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
+	if (err)
+		goto out;
+
+	err = sysfs_create_group(&s->kobj, &slab_attr_group);
+	if (err)
+		goto out_del_kobj;
+
+#ifdef CONFIG_MEMCG_KMEM
+	if (is_root_cache(s)) {
+		s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj);
+		if (!s->memcg_kset) {
+			err = -ENOMEM;
+			goto out_del_kobj;
+		}
+	}
+#endif
+
+	kobject_uevent(&s->kobj, KOBJ_ADD);
+	if (!unmergeable) {
+		/* Setup first alias */
+		sysfs_slab_alias(s, s->name);
+	}
+out:
+	if (!unmergeable)
+		kfree(name);
+	return err;
+out_del_kobj:
+	kobject_del(&s->kobj);
+	goto out;
+}
+
+void sysfs_slab_remove(struct kmem_cache *s)
+{
+	if (slab_state < FULL)
+		/*
+		 * Sysfs has not been setup yet so no need to remove the
+		 * cache from sysfs.
+		 */
+		return;
+
+#ifdef CONFIG_MEMCG_KMEM
+	kset_unregister(s->memcg_kset);
+#endif
+	kobject_uevent(&s->kobj, KOBJ_REMOVE);
+	kobject_del(&s->kobj);
+	kobject_put(&s->kobj);
+}
+
+/*
+ * Need to buffer aliases during bootup until sysfs becomes
+ * available lest we lose that information.
+ */
+struct saved_alias {
+	struct kmem_cache *s;
+	const char *name;
+	struct saved_alias *next;
+};
+
+static struct saved_alias *alias_list;
+
+static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
+{
+	struct saved_alias *al;
+
+	if (slab_state == FULL) {
+		/*
+		 * If we have a leftover link then remove it.
+		 */
+		sysfs_remove_link(&slab_kset->kobj, name);
+		return sysfs_create_link(&slab_kset->kobj, &s->kobj, name);
+	}
+
+	al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
+	if (!al)
+		return -ENOMEM;
+
+	al->s = s;
+	al->name = name;
+	al->next = alias_list;
+	alias_list = al;
+	return 0;
+}
+
+static int __init slab_sysfs_init(void)
+{
+	struct kmem_cache *s;
+	int err;
+
+	mutex_lock(&slab_mutex);
+
+	slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
+	if (!slab_kset) {
+		mutex_unlock(&slab_mutex);
+		pr_err("Cannot register slab subsystem.\n");
+		return -ENOSYS;
+	}
+
+	slab_state = FULL;
+
+	list_for_each_entry(s, &slab_caches, list) {
+		err = sysfs_slab_add(s);
+		if (err)
+			pr_err("SLUB: Unable to add boot slab %s to sysfs\n",
+			       s->name);
+	}
+
+	while (alias_list) {
+		struct saved_alias *al = alias_list;
+
+		alias_list = alias_list->next;
+		err = sysfs_slab_alias(al->s, al->name);
+		if (err)
+			pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n",
+			       al->name);
+		kfree(al);
+	}
+
+	mutex_unlock(&slab_mutex);
+	resiliency_test();
+	return 0;
+}
+
+__initcall(slab_sysfs_init);
+#endif /* CONFIG_SYSFS */
+
+/*
+ * The /proc/slabinfo ABI
+ */
+#ifdef CONFIG_SLABINFO
+void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
+{
+	unsigned long nr_slabs = 0;
+	unsigned long nr_objs = 0;
+	unsigned long nr_free = 0;
+	int node;
+	struct kmem_cache_node *n;
+
+	for_each_kmem_cache_node(s, node, n) {
+		nr_slabs += node_nr_slabs(n);
+		nr_objs += node_nr_objs(n);
+		nr_free += count_partial(n, count_free);
+	}
+
+	sinfo->active_objs = nr_objs - nr_free;
+	sinfo->num_objs = nr_objs;
+	sinfo->active_slabs = nr_slabs;
+	sinfo->num_slabs = nr_slabs;
+	sinfo->objects_per_slab = oo_objects(s->oo);
+	sinfo->cache_order = oo_order(s->oo);
+}
+
+void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
+{
+}
+
+ssize_t slabinfo_write(struct file *file, const char __user *buffer,
+		       size_t count, loff_t *ppos)
+{
+	return -EIO;
+}
+#endif /* CONFIG_SLABINFO */
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
new file mode 100644
index 0000000..4cba9c2
--- /dev/null
+++ b/mm/sparse-vmemmap.c
@@ -0,0 +1,235 @@
+/*
+ * Virtual Memory Map support
+ *
+ * (C) 2007 sgi. Christoph Lameter.
+ *
+ * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
+ * virt_to_page, page_address() to be implemented as a base offset
+ * calculation without memory access.
+ *
+ * However, virtual mappings need a page table and TLBs. Many Linux
+ * architectures already map their physical space using 1-1 mappings
+ * via TLBs. For those arches the virtual memory map is essentially
+ * for free if we use the same page size as the 1-1 mappings. In that
+ * case the overhead consists of a few additional pages that are
+ * allocated to create a view of memory for vmemmap.
+ *
+ * The architecture is expected to provide a vmemmap_populate() function
+ * to instantiate the mapping.
+ */
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+#include <asm/dma.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+/*
+ * Allocate a block of memory to be used to back the virtual memory map
+ * or to back the page tables that are used to create the mapping.
+ * Uses the main allocators if they are available, else bootmem.
+ */
+
+static void * __init_refok __earlyonly_bootmem_alloc(int node,
+				unsigned long size,
+				unsigned long align,
+				unsigned long goal)
+{
+	return memblock_virt_alloc_try_nid(size, align, goal,
+					    BOOTMEM_ALLOC_ACCESSIBLE, node);
+}
+
+static void *vmemmap_buf;
+static void *vmemmap_buf_end;
+
+void * __meminit vmemmap_alloc_block(unsigned long size, int node)
+{
+	/* If the main allocator is up use that, fallback to bootmem. */
+	if (slab_is_available()) {
+		struct page *page;
+
+		if (node_state(node, N_HIGH_MEMORY))
+			page = alloc_pages_node(
+				node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
+				get_order(size));
+		else
+			page = alloc_pages(
+				GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
+				get_order(size));
+		if (page)
+			return page_address(page);
+		return NULL;
+	} else
+		return __earlyonly_bootmem_alloc(node, size, size,
+				__pa(MAX_DMA_ADDRESS));
+}
+
+/* need to make sure size is all the same during early stage */
+void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
+{
+	void *ptr;
+
+	if (!vmemmap_buf)
+		return vmemmap_alloc_block(size, node);
+
+	/* take the from buf */
+	ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
+	if (ptr + size > vmemmap_buf_end)
+		return vmemmap_alloc_block(size, node);
+
+	vmemmap_buf = ptr + size;
+
+	return ptr;
+}
+
+void __meminit vmemmap_verify(pte_t *pte, int node,
+				unsigned long start, unsigned long end)
+{
+	unsigned long pfn = pte_pfn(*pte);
+	int actual_node = early_pfn_to_nid(pfn);
+
+	if (node_distance(actual_node, node) > LOCAL_DISTANCE)
+		printk(KERN_WARNING "[%lx-%lx] potential offnode "
+			"page_structs\n", start, end - 1);
+}
+
+pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
+{
+	pte_t *pte = pte_offset_kernel(pmd, addr);
+	if (pte_none(*pte)) {
+		pte_t entry;
+		void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
+		set_pte_at(&init_mm, addr, pte, entry);
+	}
+	return pte;
+}
+
+pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
+{
+	pmd_t *pmd = pmd_offset(pud, addr);
+	if (pmd_none(*pmd)) {
+		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		pmd_populate_kernel(&init_mm, pmd, p);
+	}
+	return pmd;
+}
+
+pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
+{
+	pud_t *pud = pud_offset(pgd, addr);
+	if (pud_none(*pud)) {
+		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		pud_populate(&init_mm, pud, p);
+	}
+	return pud;
+}
+
+pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
+{
+	pgd_t *pgd = pgd_offset_k(addr);
+	if (pgd_none(*pgd)) {
+		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		pgd_populate(&init_mm, pgd, p);
+	}
+	return pgd;
+}
+
+int __meminit vmemmap_populate_basepages(unsigned long start,
+					 unsigned long end, int node)
+{
+	unsigned long addr = start;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	for (; addr < end; addr += PAGE_SIZE) {
+		pgd = vmemmap_pgd_populate(addr, node);
+		if (!pgd)
+			return -ENOMEM;
+		pud = vmemmap_pud_populate(pgd, addr, node);
+		if (!pud)
+			return -ENOMEM;
+		pmd = vmemmap_pmd_populate(pud, addr, node);
+		if (!pmd)
+			return -ENOMEM;
+		pte = vmemmap_pte_populate(pmd, addr, node);
+		if (!pte)
+			return -ENOMEM;
+		vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
+	}
+
+	return 0;
+}
+
+struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
+{
+	unsigned long start;
+	unsigned long end;
+	struct page *map;
+
+	map = pfn_to_page(pnum * PAGES_PER_SECTION);
+	start = (unsigned long)map;
+	end = (unsigned long)(map + PAGES_PER_SECTION);
+
+	if (vmemmap_populate(start, end, nid))
+		return NULL;
+
+	return map;
+}
+
+void __init sparse_mem_maps_populate_node(struct page **map_map,
+					  unsigned long pnum_begin,
+					  unsigned long pnum_end,
+					  unsigned long map_count, int nodeid)
+{
+	unsigned long pnum;
+	unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
+	void *vmemmap_buf_start;
+
+	size = ALIGN(size, PMD_SIZE);
+	vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
+			 PMD_SIZE, __pa(MAX_DMA_ADDRESS));
+
+	if (vmemmap_buf_start) {
+		vmemmap_buf = vmemmap_buf_start;
+		vmemmap_buf_end = vmemmap_buf_start + size * map_count;
+	}
+
+	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+		struct mem_section *ms;
+
+		if (!present_section_nr(pnum))
+			continue;
+
+		map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
+		if (map_map[pnum])
+			continue;
+		ms = __nr_to_section(pnum);
+		printk(KERN_ERR "%s: sparsemem memory map backing failed "
+			"some memory will not be available.\n", __func__);
+		ms->section_mem_map = 0;
+	}
+
+	if (vmemmap_buf_start) {
+		/* need to free left buf */
+		memblock_free_early(__pa(vmemmap_buf),
+				    vmemmap_buf_end - vmemmap_buf);
+		vmemmap_buf = NULL;
+		vmemmap_buf_end = NULL;
+	}
+}
diff --git a/mm/sparse.c b/mm/sparse.c
new file mode 100644
index 0000000..d1b48b6
--- /dev/null
+++ b/mm/sparse.c
@@ -0,0 +1,811 @@
+/*
+ * sparse memory mappings.
+ */
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/compiler.h>
+#include <linux/highmem.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+
+#include "internal.h"
+#include <asm/dma.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+/*
+ * Permanent SPARSEMEM data:
+ *
+ * 1) mem_section	- memory sections, mem_map's for valid memory
+ */
+#ifdef CONFIG_SPARSEMEM_EXTREME
+struct mem_section *mem_section[NR_SECTION_ROOTS]
+	____cacheline_internodealigned_in_smp;
+#else
+struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
+	____cacheline_internodealigned_in_smp;
+#endif
+EXPORT_SYMBOL(mem_section);
+
+#ifdef NODE_NOT_IN_PAGE_FLAGS
+/*
+ * If we did not store the node number in the page then we have to
+ * do a lookup in the section_to_node_table in order to find which
+ * node the page belongs to.
+ */
+#if MAX_NUMNODES <= 256
+static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
+#else
+static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
+#endif
+
+int page_to_nid(const struct page *page)
+{
+	return section_to_node_table[page_to_section(page)];
+}
+EXPORT_SYMBOL(page_to_nid);
+
+static void set_section_nid(unsigned long section_nr, int nid)
+{
+	section_to_node_table[section_nr] = nid;
+}
+#else /* !NODE_NOT_IN_PAGE_FLAGS */
+static inline void set_section_nid(unsigned long section_nr, int nid)
+{
+}
+#endif
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
+{
+	struct mem_section *section = NULL;
+	unsigned long array_size = SECTIONS_PER_ROOT *
+				   sizeof(struct mem_section);
+
+	if (slab_is_available()) {
+		if (node_state(nid, N_HIGH_MEMORY))
+			section = kzalloc_node(array_size, GFP_KERNEL, nid);
+		else
+			section = kzalloc(array_size, GFP_KERNEL);
+	} else {
+		section = memblock_virt_alloc_node(array_size, nid);
+	}
+
+	return section;
+}
+
+static int __meminit sparse_index_init(unsigned long section_nr, int nid)
+{
+	unsigned long root = SECTION_NR_TO_ROOT(section_nr);
+	struct mem_section *section;
+
+	if (mem_section[root])
+		return -EEXIST;
+
+	section = sparse_index_alloc(nid);
+	if (!section)
+		return -ENOMEM;
+
+	mem_section[root] = section;
+
+	return 0;
+}
+#else /* !SPARSEMEM_EXTREME */
+static inline int sparse_index_init(unsigned long section_nr, int nid)
+{
+	return 0;
+}
+#endif
+
+/*
+ * Although written for the SPARSEMEM_EXTREME case, this happens
+ * to also work for the flat array case because
+ * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
+ */
+int __section_nr(struct mem_section* ms)
+{
+	unsigned long root_nr;
+	struct mem_section* root;
+
+	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
+		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
+		if (!root)
+			continue;
+
+		if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
+		     break;
+	}
+
+	VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
+
+	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
+}
+
+/*
+ * During early boot, before section_mem_map is used for an actual
+ * mem_map, we use section_mem_map to store the section's NUMA
+ * node.  This keeps us from having to use another data structure.  The
+ * node information is cleared just before we store the real mem_map.
+ */
+static inline unsigned long sparse_encode_early_nid(int nid)
+{
+	return (nid << SECTION_NID_SHIFT);
+}
+
+static inline int sparse_early_nid(struct mem_section *section)
+{
+	return (section->section_mem_map >> SECTION_NID_SHIFT);
+}
+
+/* Validate the physical addressing limitations of the model */
+void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
+						unsigned long *end_pfn)
+{
+	unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
+
+	/*
+	 * Sanity checks - do not allow an architecture to pass
+	 * in larger pfns than the maximum scope of sparsemem:
+	 */
+	if (*start_pfn > max_sparsemem_pfn) {
+		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
+			"Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
+			*start_pfn, *end_pfn, max_sparsemem_pfn);
+		WARN_ON_ONCE(1);
+		*start_pfn = max_sparsemem_pfn;
+		*end_pfn = max_sparsemem_pfn;
+	} else if (*end_pfn > max_sparsemem_pfn) {
+		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
+			"End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
+			*start_pfn, *end_pfn, max_sparsemem_pfn);
+		WARN_ON_ONCE(1);
+		*end_pfn = max_sparsemem_pfn;
+	}
+}
+
+/* Record a memory area against a node. */
+void __init memory_present(int nid, unsigned long start, unsigned long end)
+{
+	unsigned long pfn;
+
+	start &= PAGE_SECTION_MASK;
+	mminit_validate_memmodel_limits(&start, &end);
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
+		unsigned long section = pfn_to_section_nr(pfn);
+		struct mem_section *ms;
+
+		sparse_index_init(section, nid);
+		set_section_nid(section, nid);
+
+		ms = __nr_to_section(section);
+		if (!ms->section_mem_map)
+			ms->section_mem_map = sparse_encode_early_nid(nid) |
+							SECTION_MARKED_PRESENT;
+	}
+}
+
+/*
+ * Only used by the i386 NUMA architecures, but relatively
+ * generic code.
+ */
+unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
+						     unsigned long end_pfn)
+{
+	unsigned long pfn;
+	unsigned long nr_pages = 0;
+
+	mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
+	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		if (nid != early_pfn_to_nid(pfn))
+			continue;
+
+		if (pfn_present(pfn))
+			nr_pages += PAGES_PER_SECTION;
+	}
+
+	return nr_pages * sizeof(struct page);
+}
+
+/*
+ * Subtle, we encode the real pfn into the mem_map such that
+ * the identity pfn - section_mem_map will return the actual
+ * physical page frame number.
+ */
+static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
+{
+	return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
+}
+
+/*
+ * Decode mem_map from the coded memmap
+ */
+struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
+{
+	/* mask off the extra low bits of information */
+	coded_mem_map &= SECTION_MAP_MASK;
+	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
+}
+
+static int __meminit sparse_init_one_section(struct mem_section *ms,
+		unsigned long pnum, struct page *mem_map,
+		unsigned long *pageblock_bitmap)
+{
+	if (!present_section(ms))
+		return -EINVAL;
+
+	ms->section_mem_map &= ~SECTION_MAP_MASK;
+	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
+							SECTION_HAS_MEM_MAP;
+ 	ms->pageblock_flags = pageblock_bitmap;
+
+	return 1;
+}
+
+unsigned long usemap_size(void)
+{
+	unsigned long size_bytes;
+	size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
+	size_bytes = roundup(size_bytes, sizeof(unsigned long));
+	return size_bytes;
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static unsigned long *__kmalloc_section_usemap(void)
+{
+	return kmalloc(usemap_size(), GFP_KERNEL);
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static unsigned long * __init
+sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
+					 unsigned long size)
+{
+	unsigned long goal, limit;
+	unsigned long *p;
+	int nid;
+	/*
+	 * A page may contain usemaps for other sections preventing the
+	 * page being freed and making a section unremovable while
+	 * other sections referencing the usemap remain active. Similarly,
+	 * a pgdat can prevent a section being removed. If section A
+	 * contains a pgdat and section B contains the usemap, both
+	 * sections become inter-dependent. This allocates usemaps
+	 * from the same section as the pgdat where possible to avoid
+	 * this problem.
+	 */
+	goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
+	limit = goal + (1UL << PA_SECTION_SHIFT);
+	nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
+again:
+	p = memblock_virt_alloc_try_nid_nopanic(size,
+						SMP_CACHE_BYTES, goal, limit,
+						nid);
+	if (!p && limit) {
+		limit = 0;
+		goto again;
+	}
+	return p;
+}
+
+static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
+{
+	unsigned long usemap_snr, pgdat_snr;
+	static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
+	static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
+	struct pglist_data *pgdat = NODE_DATA(nid);
+	int usemap_nid;
+
+	usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
+	pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
+	if (usemap_snr == pgdat_snr)
+		return;
+
+	if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
+		/* skip redundant message */
+		return;
+
+	old_usemap_snr = usemap_snr;
+	old_pgdat_snr = pgdat_snr;
+
+	usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
+	if (usemap_nid != nid) {
+		printk(KERN_INFO
+		       "node %d must be removed before remove section %ld\n",
+		       nid, usemap_snr);
+		return;
+	}
+	/*
+	 * There is a circular dependency.
+	 * Some platforms allow un-removable section because they will just
+	 * gather other removable sections for dynamic partitioning.
+	 * Just notify un-removable section's number here.
+	 */
+	printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
+	       pgdat_snr, nid);
+	printk(KERN_CONT
+	       " have a circular dependency on usemap and pgdat allocations\n");
+}
+#else
+static unsigned long * __init
+sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
+					 unsigned long size)
+{
+	return memblock_virt_alloc_node_nopanic(size, pgdat->node_id);
+}
+
+static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
+{
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+static void __init sparse_early_usemaps_alloc_node(void *data,
+				 unsigned long pnum_begin,
+				 unsigned long pnum_end,
+				 unsigned long usemap_count, int nodeid)
+{
+	void *usemap;
+	unsigned long pnum;
+	unsigned long **usemap_map = (unsigned long **)data;
+	int size = usemap_size();
+
+	usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
+							  size * usemap_count);
+	if (!usemap) {
+		printk(KERN_WARNING "%s: allocation failed\n", __func__);
+		return;
+	}
+
+	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+		if (!present_section_nr(pnum))
+			continue;
+		usemap_map[pnum] = usemap;
+		usemap += size;
+		check_usemap_section_nr(nodeid, usemap_map[pnum]);
+	}
+}
+
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
+{
+	struct page *map;
+	unsigned long size;
+
+	map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
+	if (map)
+		return map;
+
+	size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
+	map = memblock_virt_alloc_try_nid(size,
+					  PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
+					  BOOTMEM_ALLOC_ACCESSIBLE, nid);
+	return map;
+}
+void __init sparse_mem_maps_populate_node(struct page **map_map,
+					  unsigned long pnum_begin,
+					  unsigned long pnum_end,
+					  unsigned long map_count, int nodeid)
+{
+	void *map;
+	unsigned long pnum;
+	unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
+
+	map = alloc_remap(nodeid, size * map_count);
+	if (map) {
+		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+			if (!present_section_nr(pnum))
+				continue;
+			map_map[pnum] = map;
+			map += size;
+		}
+		return;
+	}
+
+	size = PAGE_ALIGN(size);
+	map = memblock_virt_alloc_try_nid(size * map_count,
+					  PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
+					  BOOTMEM_ALLOC_ACCESSIBLE, nodeid);
+	if (map) {
+		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+			if (!present_section_nr(pnum))
+				continue;
+			map_map[pnum] = map;
+			map += size;
+		}
+		return;
+	}
+
+	/* fallback */
+	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+		struct mem_section *ms;
+
+		if (!present_section_nr(pnum))
+			continue;
+		map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
+		if (map_map[pnum])
+			continue;
+		ms = __nr_to_section(pnum);
+		printk(KERN_ERR "%s: sparsemem memory map backing failed "
+			"some memory will not be available.\n", __func__);
+		ms->section_mem_map = 0;
+	}
+}
+#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+
+#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
+static void __init sparse_early_mem_maps_alloc_node(void *data,
+				 unsigned long pnum_begin,
+				 unsigned long pnum_end,
+				 unsigned long map_count, int nodeid)
+{
+	struct page **map_map = (struct page **)data;
+	sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
+					 map_count, nodeid);
+}
+#else
+static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
+{
+	struct page *map;
+	struct mem_section *ms = __nr_to_section(pnum);
+	int nid = sparse_early_nid(ms);
+
+	map = sparse_mem_map_populate(pnum, nid);
+	if (map)
+		return map;
+
+	printk(KERN_ERR "%s: sparsemem memory map backing failed "
+			"some memory will not be available.\n", __func__);
+	ms->section_mem_map = 0;
+	return NULL;
+}
+#endif
+
+void __weak __meminit vmemmap_populate_print_last(void)
+{
+}
+
+/**
+ *  alloc_usemap_and_memmap - memory alloction for pageblock flags and vmemmap
+ *  @map: usemap_map for pageblock flags or mmap_map for vmemmap
+ */
+static void __init alloc_usemap_and_memmap(void (*alloc_func)
+					(void *, unsigned long, unsigned long,
+					unsigned long, int), void *data)
+{
+	unsigned long pnum;
+	unsigned long map_count;
+	int nodeid_begin = 0;
+	unsigned long pnum_begin = 0;
+
+	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
+		struct mem_section *ms;
+
+		if (!present_section_nr(pnum))
+			continue;
+		ms = __nr_to_section(pnum);
+		nodeid_begin = sparse_early_nid(ms);
+		pnum_begin = pnum;
+		break;
+	}
+	map_count = 1;
+	for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
+		struct mem_section *ms;
+		int nodeid;
+
+		if (!present_section_nr(pnum))
+			continue;
+		ms = __nr_to_section(pnum);
+		nodeid = sparse_early_nid(ms);
+		if (nodeid == nodeid_begin) {
+			map_count++;
+			continue;
+		}
+		/* ok, we need to take cake of from pnum_begin to pnum - 1*/
+		alloc_func(data, pnum_begin, pnum,
+						map_count, nodeid_begin);
+		/* new start, update count etc*/
+		nodeid_begin = nodeid;
+		pnum_begin = pnum;
+		map_count = 1;
+	}
+	/* ok, last chunk */
+	alloc_func(data, pnum_begin, NR_MEM_SECTIONS,
+						map_count, nodeid_begin);
+}
+
+/*
+ * Allocate the accumulated non-linear sections, allocate a mem_map
+ * for each and record the physical to section mapping.
+ */
+void __init sparse_init(void)
+{
+	unsigned long pnum;
+	struct page *map;
+	unsigned long *usemap;
+	unsigned long **usemap_map;
+	int size;
+#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
+	int size2;
+	struct page **map_map;
+#endif
+
+	/* see include/linux/mmzone.h 'struct mem_section' definition */
+	BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section)));
+
+	/* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
+	set_pageblock_order();
+
+	/*
+	 * map is using big page (aka 2M in x86 64 bit)
+	 * usemap is less one page (aka 24 bytes)
+	 * so alloc 2M (with 2M align) and 24 bytes in turn will
+	 * make next 2M slip to one more 2M later.
+	 * then in big system, the memory will have a lot of holes...
+	 * here try to allocate 2M pages continuously.
+	 *
+	 * powerpc need to call sparse_init_one_section right after each
+	 * sparse_early_mem_map_alloc, so allocate usemap_map at first.
+	 */
+	size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
+	usemap_map = memblock_virt_alloc(size, 0);
+	if (!usemap_map)
+		panic("can not allocate usemap_map\n");
+	alloc_usemap_and_memmap(sparse_early_usemaps_alloc_node,
+							(void *)usemap_map);
+
+#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
+	size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
+	map_map = memblock_virt_alloc(size2, 0);
+	if (!map_map)
+		panic("can not allocate map_map\n");
+	alloc_usemap_and_memmap(sparse_early_mem_maps_alloc_node,
+							(void *)map_map);
+#endif
+
+	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
+		if (!present_section_nr(pnum))
+			continue;
+
+		usemap = usemap_map[pnum];
+		if (!usemap)
+			continue;
+
+#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
+		map = map_map[pnum];
+#else
+		map = sparse_early_mem_map_alloc(pnum);
+#endif
+		if (!map)
+			continue;
+
+		sparse_init_one_section(__nr_to_section(pnum), pnum, map,
+								usemap);
+	}
+
+	vmemmap_populate_print_last();
+
+#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
+	memblock_free_early(__pa(map_map), size2);
+#endif
+	memblock_free_early(__pa(usemap_map), size);
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
+{
+	/* This will make the necessary allocations eventually. */
+	return sparse_mem_map_populate(pnum, nid);
+}
+static void __kfree_section_memmap(struct page *memmap)
+{
+	unsigned long start = (unsigned long)memmap;
+	unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
+
+	vmemmap_free(start, end);
+}
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static void free_map_bootmem(struct page *memmap)
+{
+	unsigned long start = (unsigned long)memmap;
+	unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
+
+	vmemmap_free(start, end);
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#else
+static struct page *__kmalloc_section_memmap(void)
+{
+	struct page *page, *ret;
+	unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
+
+	page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
+	if (page)
+		goto got_map_page;
+
+	ret = vmalloc(memmap_size);
+	if (ret)
+		goto got_map_ptr;
+
+	return NULL;
+got_map_page:
+	ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
+got_map_ptr:
+
+	return ret;
+}
+
+static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
+{
+	return __kmalloc_section_memmap();
+}
+
+static void __kfree_section_memmap(struct page *memmap)
+{
+	if (is_vmalloc_addr(memmap))
+		vfree(memmap);
+	else
+		free_pages((unsigned long)memmap,
+			   get_order(sizeof(struct page) * PAGES_PER_SECTION));
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static void free_map_bootmem(struct page *memmap)
+{
+	unsigned long maps_section_nr, removing_section_nr, i;
+	unsigned long magic, nr_pages;
+	struct page *page = virt_to_page(memmap);
+
+	nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
+		>> PAGE_SHIFT;
+
+	for (i = 0; i < nr_pages; i++, page++) {
+		magic = (unsigned long) page->lru.next;
+
+		BUG_ON(magic == NODE_INFO);
+
+		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
+		removing_section_nr = page->private;
+
+		/*
+		 * When this function is called, the removing section is
+		 * logical offlined state. This means all pages are isolated
+		 * from page allocator. If removing section's memmap is placed
+		 * on the same section, it must not be freed.
+		 * If it is freed, page allocator may allocate it which will
+		 * be removed physically soon.
+		 */
+		if (maps_section_nr != removing_section_nr)
+			put_page_bootmem(page);
+	}
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
+/*
+ * returns the number of sections whose mem_maps were properly
+ * set.  If this is <=0, then that means that the passed-in
+ * map was not consumed and must be freed.
+ */
+int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn)
+{
+	unsigned long section_nr = pfn_to_section_nr(start_pfn);
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	struct mem_section *ms;
+	struct page *memmap;
+	unsigned long *usemap;
+	unsigned long flags;
+	int ret;
+
+	/*
+	 * no locking for this, because it does its own
+	 * plus, it does a kmalloc
+	 */
+	ret = sparse_index_init(section_nr, pgdat->node_id);
+	if (ret < 0 && ret != -EEXIST)
+		return ret;
+	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id);
+	if (!memmap)
+		return -ENOMEM;
+	usemap = __kmalloc_section_usemap();
+	if (!usemap) {
+		__kfree_section_memmap(memmap);
+		return -ENOMEM;
+	}
+
+	pgdat_resize_lock(pgdat, &flags);
+
+	ms = __pfn_to_section(start_pfn);
+	if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
+		ret = -EEXIST;
+		goto out;
+	}
+
+	memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
+
+	ms->section_mem_map |= SECTION_MARKED_PRESENT;
+
+	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
+
+out:
+	pgdat_resize_unlock(pgdat, &flags);
+	if (ret <= 0) {
+		kfree(usemap);
+		__kfree_section_memmap(memmap);
+	}
+	return ret;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+#ifdef CONFIG_MEMORY_FAILURE
+static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+	int i;
+
+	if (!memmap)
+		return;
+
+	for (i = 0; i < PAGES_PER_SECTION; i++) {
+		if (PageHWPoison(&memmap[i])) {
+			atomic_long_sub(1, &num_poisoned_pages);
+			ClearPageHWPoison(&memmap[i]);
+		}
+	}
+}
+#else
+static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+}
+#endif
+
+static void free_section_usemap(struct page *memmap, unsigned long *usemap)
+{
+	struct page *usemap_page;
+
+	if (!usemap)
+		return;
+
+	usemap_page = virt_to_page(usemap);
+	/*
+	 * Check to see if allocation came from hot-plug-add
+	 */
+	if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
+		kfree(usemap);
+		if (memmap)
+			__kfree_section_memmap(memmap);
+		return;
+	}
+
+	/*
+	 * The usemap came from bootmem. This is packed with other usemaps
+	 * on the section which has pgdat at boot time. Just keep it as is now.
+	 */
+
+	if (memmap)
+		free_map_bootmem(memmap);
+}
+
+void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
+{
+	struct page *memmap = NULL;
+	unsigned long *usemap = NULL, flags;
+	struct pglist_data *pgdat = zone->zone_pgdat;
+
+	pgdat_resize_lock(pgdat, &flags);
+	if (ms->section_mem_map) {
+		usemap = ms->pageblock_flags;
+		memmap = sparse_decode_mem_map(ms->section_mem_map,
+						__section_nr(ms));
+		ms->section_mem_map = 0;
+		ms->pageblock_flags = NULL;
+	}
+	pgdat_resize_unlock(pgdat, &flags);
+
+	clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
+	free_section_usemap(memmap, usemap);
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/mm/swap.c b/mm/swap.c
new file mode 100644
index 0000000..39395fb
--- /dev/null
+++ b/mm/swap.c
@@ -0,0 +1,1164 @@
+/*
+ *  linux/mm/swap.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ */
+
+/*
+ * This file contains the default values for the operation of the
+ * Linux VM subsystem. Fine-tuning documentation can be found in
+ * Documentation/sysctl/vm.txt.
+ * Started 18.12.91
+ * Swap aging added 23.2.95, Stephen Tweedie.
+ * Buffermem limits added 12.3.98, Rik van Riel.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/mm_inline.h>
+#include <linux/percpu_counter.h>
+#include <linux/percpu.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/backing-dev.h>
+#include <linux/memcontrol.h>
+#include <linux/gfp.h>
+#include <linux/uio.h>
+#include <linux/hugetlb.h>
+#include <linux/page_idle.h>
+
+#include "internal.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/pagemap.h>
+
+/* How many pages do we try to swap or page in/out together? */
+int page_cluster;
+
+static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
+static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
+static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
+
+/*
+ * This path almost never happens for VM activity - pages are normally
+ * freed via pagevecs.  But it gets used by networking.
+ */
+static void __page_cache_release(struct page *page)
+{
+	if (PageLRU(page)) {
+		struct zone *zone = page_zone(page);
+		struct lruvec *lruvec;
+		unsigned long flags;
+
+		spin_lock_irqsave(&zone->lru_lock, flags);
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+		VM_BUG_ON_PAGE(!PageLRU(page), page);
+		__ClearPageLRU(page);
+		del_page_from_lru_list(page, lruvec, page_off_lru(page));
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+	}
+	mem_cgroup_uncharge(page);
+}
+
+static void __put_single_page(struct page *page)
+{
+	__page_cache_release(page);
+	free_hot_cold_page(page, false);
+}
+
+static void __put_compound_page(struct page *page)
+{
+	compound_page_dtor *dtor;
+
+	/*
+	 * __page_cache_release() is supposed to be called for thp, not for
+	 * hugetlb. This is because hugetlb page does never have PageLRU set
+	 * (it's never listed to any LRU lists) and no memcg routines should
+	 * be called for hugetlb (it has a separate hugetlb_cgroup.)
+	 */
+	if (!PageHuge(page))
+		__page_cache_release(page);
+	dtor = get_compound_page_dtor(page);
+	(*dtor)(page);
+}
+
+/**
+ * Two special cases here: we could avoid taking compound_lock_irqsave
+ * and could skip the tail refcounting(in _mapcount).
+ *
+ * 1. Hugetlbfs page:
+ *
+ *    PageHeadHuge will remain true until the compound page
+ *    is released and enters the buddy allocator, and it could
+ *    not be split by __split_huge_page_refcount().
+ *
+ *    So if we see PageHeadHuge set, and we have the tail page pin,
+ *    then we could safely put head page.
+ *
+ * 2. Slab THP page:
+ *
+ *    PG_slab is cleared before the slab frees the head page, and
+ *    tail pin cannot be the last reference left on the head page,
+ *    because the slab code is free to reuse the compound page
+ *    after a kfree/kmem_cache_free without having to check if
+ *    there's any tail pin left.  In turn all tail pinsmust be always
+ *    released while the head is still pinned by the slab code
+ *    and so we know PG_slab will be still set too.
+ *
+ *    So if we see PageSlab set, and we have the tail page pin,
+ *    then we could safely put head page.
+ */
+static __always_inline
+void put_unrefcounted_compound_page(struct page *page_head, struct page *page)
+{
+	/*
+	 * If @page is a THP tail, we must read the tail page
+	 * flags after the head page flags. The
+	 * __split_huge_page_refcount side enforces write memory barriers
+	 * between clearing PageTail and before the head page
+	 * can be freed and reallocated.
+	 */
+	smp_rmb();
+	if (likely(PageTail(page))) {
+		/*
+		 * __split_huge_page_refcount cannot race
+		 * here, see the comment above this function.
+		 */
+		VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
+		if (put_page_testzero(page_head)) {
+			/*
+			 * If this is the tail of a slab THP page,
+			 * the tail pin must not be the last reference
+			 * held on the page, because the PG_slab cannot
+			 * be cleared before all tail pins (which skips
+			 * the _mapcount tail refcounting) have been
+			 * released.
+			 *
+			 * If this is the tail of a hugetlbfs page,
+			 * the tail pin may be the last reference on
+			 * the page instead, because PageHeadHuge will
+			 * not go away until the compound page enters
+			 * the buddy allocator.
+			 */
+			VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
+			__put_compound_page(page_head);
+		}
+	} else
+		/*
+		 * __split_huge_page_refcount run before us,
+		 * @page was a THP tail. The split @page_head
+		 * has been freed and reallocated as slab or
+		 * hugetlbfs page of smaller order (only
+		 * possible if reallocated as slab on x86).
+		 */
+		if (put_page_testzero(page))
+			__put_single_page(page);
+}
+
+static __always_inline
+void put_refcounted_compound_page(struct page *page_head, struct page *page)
+{
+	if (likely(page != page_head && get_page_unless_zero(page_head))) {
+		unsigned long flags;
+
+		/*
+		 * @page_head wasn't a dangling pointer but it may not
+		 * be a head page anymore by the time we obtain the
+		 * lock. That is ok as long as it can't be freed from
+		 * under us.
+		 */
+		flags = compound_lock_irqsave(page_head);
+		if (unlikely(!PageTail(page))) {
+			/* __split_huge_page_refcount run before us */
+			compound_unlock_irqrestore(page_head, flags);
+			if (put_page_testzero(page_head)) {
+				/*
+				 * The @page_head may have been freed
+				 * and reallocated as a compound page
+				 * of smaller order and then freed
+				 * again.  All we know is that it
+				 * cannot have become: a THP page, a
+				 * compound page of higher order, a
+				 * tail page.  That is because we
+				 * still hold the refcount of the
+				 * split THP tail and page_head was
+				 * the THP head before the split.
+				 */
+				if (PageHead(page_head))
+					__put_compound_page(page_head);
+				else
+					__put_single_page(page_head);
+			}
+out_put_single:
+			if (put_page_testzero(page))
+				__put_single_page(page);
+			return;
+		}
+		VM_BUG_ON_PAGE(page_head != compound_head(page), page);
+		/*
+		 * We can release the refcount taken by
+		 * get_page_unless_zero() now that
+		 * __split_huge_page_refcount() is blocked on the
+		 * compound_lock.
+		 */
+		if (put_page_testzero(page_head))
+			VM_BUG_ON_PAGE(1, page_head);
+		/* __split_huge_page_refcount will wait now */
+		VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
+		atomic_dec(&page->_mapcount);
+		VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
+		VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
+		compound_unlock_irqrestore(page_head, flags);
+
+		if (put_page_testzero(page_head)) {
+			if (PageHead(page_head))
+				__put_compound_page(page_head);
+			else
+				__put_single_page(page_head);
+		}
+	} else {
+		/* @page_head is a dangling pointer */
+		VM_BUG_ON_PAGE(PageTail(page), page);
+		goto out_put_single;
+	}
+}
+
+static void put_compound_page(struct page *page)
+{
+	struct page *page_head;
+
+	/*
+	 * We see the PageCompound set and PageTail not set, so @page maybe:
+	 *  1. hugetlbfs head page, or
+	 *  2. THP head page.
+	 */
+	if (likely(!PageTail(page))) {
+		if (put_page_testzero(page)) {
+			/*
+			 * By the time all refcounts have been released
+			 * split_huge_page cannot run anymore from under us.
+			 */
+			if (PageHead(page))
+				__put_compound_page(page);
+			else
+				__put_single_page(page);
+		}
+		return;
+	}
+
+	/*
+	 * We see the PageCompound set and PageTail set, so @page maybe:
+	 *  1. a tail hugetlbfs page, or
+	 *  2. a tail THP page, or
+	 *  3. a split THP page.
+	 *
+	 *  Case 3 is possible, as we may race with
+	 *  __split_huge_page_refcount tearing down a THP page.
+	 */
+	page_head = compound_head(page);
+	if (!__compound_tail_refcounted(page_head))
+		put_unrefcounted_compound_page(page_head, page);
+	else
+		put_refcounted_compound_page(page_head, page);
+}
+
+void put_page(struct page *page)
+{
+	if (unlikely(PageCompound(page)))
+		put_compound_page(page);
+	else if (put_page_testzero(page))
+		__put_single_page(page);
+}
+EXPORT_SYMBOL(put_page);
+
+/*
+ * This function is exported but must not be called by anything other
+ * than get_page(). It implements the slow path of get_page().
+ */
+bool __get_page_tail(struct page *page)
+{
+	/*
+	 * This takes care of get_page() if run on a tail page
+	 * returned by one of the get_user_pages/follow_page variants.
+	 * get_user_pages/follow_page itself doesn't need the compound
+	 * lock because it runs __get_page_tail_foll() under the
+	 * proper PT lock that already serializes against
+	 * split_huge_page().
+	 */
+	unsigned long flags;
+	bool got;
+	struct page *page_head = compound_head(page);
+
+	/* Ref to put_compound_page() comment. */
+	if (!__compound_tail_refcounted(page_head)) {
+		smp_rmb();
+		if (likely(PageTail(page))) {
+			/*
+			 * This is a hugetlbfs page or a slab
+			 * page. __split_huge_page_refcount
+			 * cannot race here.
+			 */
+			VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
+			__get_page_tail_foll(page, true);
+			return true;
+		} else {
+			/*
+			 * __split_huge_page_refcount run
+			 * before us, "page" was a THP
+			 * tail. The split page_head has been
+			 * freed and reallocated as slab or
+			 * hugetlbfs page of smaller order
+			 * (only possible if reallocated as
+			 * slab on x86).
+			 */
+			return false;
+		}
+	}
+
+	got = false;
+	if (likely(page != page_head && get_page_unless_zero(page_head))) {
+		/*
+		 * page_head wasn't a dangling pointer but it
+		 * may not be a head page anymore by the time
+		 * we obtain the lock. That is ok as long as it
+		 * can't be freed from under us.
+		 */
+		flags = compound_lock_irqsave(page_head);
+		/* here __split_huge_page_refcount won't run anymore */
+		if (likely(PageTail(page))) {
+			__get_page_tail_foll(page, false);
+			got = true;
+		}
+		compound_unlock_irqrestore(page_head, flags);
+		if (unlikely(!got))
+			put_page(page_head);
+	}
+	return got;
+}
+EXPORT_SYMBOL(__get_page_tail);
+
+/**
+ * put_pages_list() - release a list of pages
+ * @pages: list of pages threaded on page->lru
+ *
+ * Release a list of pages which are strung together on page.lru.  Currently
+ * used by read_cache_pages() and related error recovery code.
+ */
+void put_pages_list(struct list_head *pages)
+{
+	while (!list_empty(pages)) {
+		struct page *victim;
+
+		victim = list_entry(pages->prev, struct page, lru);
+		list_del(&victim->lru);
+		page_cache_release(victim);
+	}
+}
+EXPORT_SYMBOL(put_pages_list);
+
+/*
+ * get_kernel_pages() - pin kernel pages in memory
+ * @kiov:	An array of struct kvec structures
+ * @nr_segs:	number of segments to pin
+ * @write:	pinning for read/write, currently ignored
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_segs long.
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno. Each page returned must be released
+ * with a put_page() call when it is finished with.
+ */
+int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
+		struct page **pages)
+{
+	int seg;
+
+	for (seg = 0; seg < nr_segs; seg++) {
+		if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
+			return seg;
+
+		pages[seg] = kmap_to_page(kiov[seg].iov_base);
+		page_cache_get(pages[seg]);
+	}
+
+	return seg;
+}
+EXPORT_SYMBOL_GPL(get_kernel_pages);
+
+/*
+ * get_kernel_page() - pin a kernel page in memory
+ * @start:	starting kernel address
+ * @write:	pinning for read/write, currently ignored
+ * @pages:	array that receives pointer to the page pinned.
+ *		Must be at least nr_segs long.
+ *
+ * Returns 1 if page is pinned. If the page was not pinned, returns
+ * -errno. The page returned must be released with a put_page() call
+ * when it is finished with.
+ */
+int get_kernel_page(unsigned long start, int write, struct page **pages)
+{
+	const struct kvec kiov = {
+		.iov_base = (void *)start,
+		.iov_len = PAGE_SIZE
+	};
+
+	return get_kernel_pages(&kiov, 1, write, pages);
+}
+EXPORT_SYMBOL_GPL(get_kernel_page);
+
+static void pagevec_lru_move_fn(struct pagevec *pvec,
+	void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
+	void *arg)
+{
+	int i;
+	struct zone *zone = NULL;
+	struct lruvec *lruvec;
+	unsigned long flags = 0;
+
+	for (i = 0; i < pagevec_count(pvec); i++) {
+		struct page *page = pvec->pages[i];
+		struct zone *pagezone = page_zone(page);
+
+		if (pagezone != zone) {
+			if (zone)
+				spin_unlock_irqrestore(&zone->lru_lock, flags);
+			zone = pagezone;
+			spin_lock_irqsave(&zone->lru_lock, flags);
+		}
+
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+		(*move_fn)(page, lruvec, arg);
+	}
+	if (zone)
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+	release_pages(pvec->pages, pvec->nr, pvec->cold);
+	pagevec_reinit(pvec);
+}
+
+static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
+				 void *arg)
+{
+	int *pgmoved = arg;
+
+	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
+		enum lru_list lru = page_lru_base_type(page);
+		list_move_tail(&page->lru, &lruvec->lists[lru]);
+		(*pgmoved)++;
+	}
+}
+
+/*
+ * pagevec_move_tail() must be called with IRQ disabled.
+ * Otherwise this may cause nasty races.
+ */
+static void pagevec_move_tail(struct pagevec *pvec)
+{
+	int pgmoved = 0;
+
+	pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
+	__count_vm_events(PGROTATED, pgmoved);
+}
+
+/*
+ * Writeback is about to end against a page which has been marked for immediate
+ * reclaim.  If it still appears to be reclaimable, move it to the tail of the
+ * inactive list.
+ */
+void rotate_reclaimable_page(struct page *page)
+{
+	if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
+	    !PageUnevictable(page) && PageLRU(page)) {
+		struct pagevec *pvec;
+		unsigned long flags;
+
+		page_cache_get(page);
+		local_irq_save(flags);
+		pvec = this_cpu_ptr(&lru_rotate_pvecs);
+		if (!pagevec_add(pvec, page))
+			pagevec_move_tail(pvec);
+		local_irq_restore(flags);
+	}
+}
+
+static void update_page_reclaim_stat(struct lruvec *lruvec,
+				     int file, int rotated)
+{
+	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
+
+	reclaim_stat->recent_scanned[file]++;
+	if (rotated)
+		reclaim_stat->recent_rotated[file]++;
+}
+
+static void __activate_page(struct page *page, struct lruvec *lruvec,
+			    void *arg)
+{
+	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
+		int file = page_is_file_cache(page);
+		int lru = page_lru_base_type(page);
+
+		del_page_from_lru_list(page, lruvec, lru);
+		SetPageActive(page);
+		lru += LRU_ACTIVE;
+		add_page_to_lru_list(page, lruvec, lru);
+		trace_mm_lru_activate(page);
+
+		__count_vm_event(PGACTIVATE);
+		update_page_reclaim_stat(lruvec, file, 1);
+	}
+}
+
+#ifdef CONFIG_SMP
+static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
+
+static void activate_page_drain(int cpu)
+{
+	struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
+
+	if (pagevec_count(pvec))
+		pagevec_lru_move_fn(pvec, __activate_page, NULL);
+}
+
+static bool need_activate_page_drain(int cpu)
+{
+	return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
+}
+
+void activate_page(struct page *page)
+{
+	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
+		struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
+
+		page_cache_get(page);
+		if (!pagevec_add(pvec, page))
+			pagevec_lru_move_fn(pvec, __activate_page, NULL);
+		put_cpu_var(activate_page_pvecs);
+	}
+}
+
+#else
+static inline void activate_page_drain(int cpu)
+{
+}
+
+static bool need_activate_page_drain(int cpu)
+{
+	return false;
+}
+
+void activate_page(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+
+	spin_lock_irq(&zone->lru_lock);
+	__activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
+	spin_unlock_irq(&zone->lru_lock);
+}
+#endif
+
+static void __lru_cache_activate_page(struct page *page)
+{
+	struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
+	int i;
+
+	/*
+	 * Search backwards on the optimistic assumption that the page being
+	 * activated has just been added to this pagevec. Note that only
+	 * the local pagevec is examined as a !PageLRU page could be in the
+	 * process of being released, reclaimed, migrated or on a remote
+	 * pagevec that is currently being drained. Furthermore, marking
+	 * a remote pagevec's page PageActive potentially hits a race where
+	 * a page is marked PageActive just after it is added to the inactive
+	 * list causing accounting errors and BUG_ON checks to trigger.
+	 */
+	for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
+		struct page *pagevec_page = pvec->pages[i];
+
+		if (pagevec_page == page) {
+			SetPageActive(page);
+			break;
+		}
+	}
+
+	put_cpu_var(lru_add_pvec);
+}
+
+/*
+ * Mark a page as having seen activity.
+ *
+ * inactive,unreferenced	->	inactive,referenced
+ * inactive,referenced		->	active,unreferenced
+ * active,unreferenced		->	active,referenced
+ *
+ * When a newly allocated page is not yet visible, so safe for non-atomic ops,
+ * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
+ */
+void mark_page_accessed(struct page *page)
+{
+	if (!PageActive(page) && !PageUnevictable(page) &&
+			PageReferenced(page)) {
+
+		/*
+		 * If the page is on the LRU, queue it for activation via
+		 * activate_page_pvecs. Otherwise, assume the page is on a
+		 * pagevec, mark it active and it'll be moved to the active
+		 * LRU on the next drain.
+		 */
+		if (PageLRU(page))
+			activate_page(page);
+		else
+			__lru_cache_activate_page(page);
+		ClearPageReferenced(page);
+		if (page_is_file_cache(page))
+			workingset_activation(page);
+	} else if (!PageReferenced(page)) {
+		SetPageReferenced(page);
+	}
+	if (page_is_idle(page))
+		clear_page_idle(page);
+}
+EXPORT_SYMBOL(mark_page_accessed);
+
+static void __lru_cache_add(struct page *page)
+{
+	struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
+
+	page_cache_get(page);
+	if (!pagevec_space(pvec))
+		__pagevec_lru_add(pvec);
+	pagevec_add(pvec, page);
+	put_cpu_var(lru_add_pvec);
+}
+
+/**
+ * lru_cache_add: add a page to the page lists
+ * @page: the page to add
+ */
+void lru_cache_add_anon(struct page *page)
+{
+	if (PageActive(page))
+		ClearPageActive(page);
+	__lru_cache_add(page);
+}
+
+void lru_cache_add_file(struct page *page)
+{
+	if (PageActive(page))
+		ClearPageActive(page);
+	__lru_cache_add(page);
+}
+EXPORT_SYMBOL(lru_cache_add_file);
+
+/**
+ * lru_cache_add - add a page to a page list
+ * @page: the page to be added to the LRU.
+ *
+ * Queue the page for addition to the LRU via pagevec. The decision on whether
+ * to add the page to the [in]active [file|anon] list is deferred until the
+ * pagevec is drained. This gives a chance for the caller of lru_cache_add()
+ * have the page added to the active list using mark_page_accessed().
+ */
+void lru_cache_add(struct page *page)
+{
+	VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	__lru_cache_add(page);
+}
+
+/**
+ * add_page_to_unevictable_list - add a page to the unevictable list
+ * @page:  the page to be added to the unevictable list
+ *
+ * Add page directly to its zone's unevictable list.  To avoid races with
+ * tasks that might be making the page evictable, through eg. munlock,
+ * munmap or exit, while it's not on the lru, we want to add the page
+ * while it's locked or otherwise "invisible" to other tasks.  This is
+ * difficult to do when using the pagevec cache, so bypass that.
+ */
+void add_page_to_unevictable_list(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+	struct lruvec *lruvec;
+
+	spin_lock_irq(&zone->lru_lock);
+	lruvec = mem_cgroup_page_lruvec(page, zone);
+	ClearPageActive(page);
+	SetPageUnevictable(page);
+	SetPageLRU(page);
+	add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
+	spin_unlock_irq(&zone->lru_lock);
+}
+
+/**
+ * lru_cache_add_active_or_unevictable
+ * @page:  the page to be added to LRU
+ * @vma:   vma in which page is mapped for determining reclaimability
+ *
+ * Place @page on the active or unevictable LRU list, depending on its
+ * evictability.  Note that if the page is not evictable, it goes
+ * directly back onto it's zone's unevictable list, it does NOT use a
+ * per cpu pagevec.
+ */
+void lru_cache_add_active_or_unevictable(struct page *page,
+					 struct vm_area_struct *vma)
+{
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+
+	if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
+		SetPageActive(page);
+		lru_cache_add(page);
+		return;
+	}
+
+	if (!TestSetPageMlocked(page)) {
+		/*
+		 * We use the irq-unsafe __mod_zone_page_stat because this
+		 * counter is not modified from interrupt context, and the pte
+		 * lock is held(spinlock), which implies preemption disabled.
+		 */
+		__mod_zone_page_state(page_zone(page), NR_MLOCK,
+				    hpage_nr_pages(page));
+		count_vm_event(UNEVICTABLE_PGMLOCKED);
+	}
+	add_page_to_unevictable_list(page);
+}
+
+/*
+ * If the page can not be invalidated, it is moved to the
+ * inactive list to speed up its reclaim.  It is moved to the
+ * head of the list, rather than the tail, to give the flusher
+ * threads some time to write it out, as this is much more
+ * effective than the single-page writeout from reclaim.
+ *
+ * If the page isn't page_mapped and dirty/writeback, the page
+ * could reclaim asap using PG_reclaim.
+ *
+ * 1. active, mapped page -> none
+ * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
+ * 3. inactive, mapped page -> none
+ * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
+ * 5. inactive, clean -> inactive, tail
+ * 6. Others -> none
+ *
+ * In 4, why it moves inactive's head, the VM expects the page would
+ * be write it out by flusher threads as this is much more effective
+ * than the single-page writeout from reclaim.
+ */
+static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
+			      void *arg)
+{
+	int lru, file;
+	bool active;
+
+	if (!PageLRU(page))
+		return;
+
+	if (PageUnevictable(page))
+		return;
+
+	/* Some processes are using the page */
+	if (page_mapped(page))
+		return;
+
+	active = PageActive(page);
+	file = page_is_file_cache(page);
+	lru = page_lru_base_type(page);
+
+	del_page_from_lru_list(page, lruvec, lru + active);
+	ClearPageActive(page);
+	ClearPageReferenced(page);
+	add_page_to_lru_list(page, lruvec, lru);
+
+	if (PageWriteback(page) || PageDirty(page)) {
+		/*
+		 * PG_reclaim could be raced with end_page_writeback
+		 * It can make readahead confusing.  But race window
+		 * is _really_ small and  it's non-critical problem.
+		 */
+		SetPageReclaim(page);
+	} else {
+		/*
+		 * The page's writeback ends up during pagevec
+		 * We moves tha page into tail of inactive.
+		 */
+		list_move_tail(&page->lru, &lruvec->lists[lru]);
+		__count_vm_event(PGROTATED);
+	}
+
+	if (active)
+		__count_vm_event(PGDEACTIVATE);
+	update_page_reclaim_stat(lruvec, file, 0);
+}
+
+/*
+ * Drain pages out of the cpu's pagevecs.
+ * Either "cpu" is the current CPU, and preemption has already been
+ * disabled; or "cpu" is being hot-unplugged, and is already dead.
+ */
+void lru_add_drain_cpu(int cpu)
+{
+	struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
+
+	if (pagevec_count(pvec))
+		__pagevec_lru_add(pvec);
+
+	pvec = &per_cpu(lru_rotate_pvecs, cpu);
+	if (pagevec_count(pvec)) {
+		unsigned long flags;
+
+		/* No harm done if a racing interrupt already did this */
+		local_irq_save(flags);
+		pagevec_move_tail(pvec);
+		local_irq_restore(flags);
+	}
+
+	pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
+	if (pagevec_count(pvec))
+		pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
+
+	activate_page_drain(cpu);
+}
+
+/**
+ * deactivate_file_page - forcefully deactivate a file page
+ * @page: page to deactivate
+ *
+ * This function hints the VM that @page is a good reclaim candidate,
+ * for example if its invalidation fails due to the page being dirty
+ * or under writeback.
+ */
+void deactivate_file_page(struct page *page)
+{
+	/*
+	 * In a workload with many unevictable page such as mprotect,
+	 * unevictable page deactivation for accelerating reclaim is pointless.
+	 */
+	if (PageUnevictable(page))
+		return;
+
+	if (likely(get_page_unless_zero(page))) {
+		struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
+
+		if (!pagevec_add(pvec, page))
+			pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
+		put_cpu_var(lru_deactivate_file_pvecs);
+	}
+}
+
+void lru_add_drain(void)
+{
+	lru_add_drain_cpu(get_cpu());
+	put_cpu();
+}
+
+static void lru_add_drain_per_cpu(struct work_struct *dummy)
+{
+	lru_add_drain();
+}
+
+static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
+
+void lru_add_drain_all(void)
+{
+	static DEFINE_MUTEX(lock);
+	static struct cpumask has_work;
+	int cpu;
+
+	mutex_lock(&lock);
+	get_online_cpus();
+	cpumask_clear(&has_work);
+
+	for_each_online_cpu(cpu) {
+		struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
+
+		if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
+		    pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
+		    pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
+		    need_activate_page_drain(cpu)) {
+			INIT_WORK(work, lru_add_drain_per_cpu);
+			schedule_work_on(cpu, work);
+			cpumask_set_cpu(cpu, &has_work);
+		}
+	}
+
+	for_each_cpu(cpu, &has_work)
+		flush_work(&per_cpu(lru_add_drain_work, cpu));
+
+	put_online_cpus();
+	mutex_unlock(&lock);
+}
+
+/**
+ * release_pages - batched page_cache_release()
+ * @pages: array of pages to release
+ * @nr: number of pages
+ * @cold: whether the pages are cache cold
+ *
+ * Decrement the reference count on all the pages in @pages.  If it
+ * fell to zero, remove the page from the LRU and free it.
+ */
+void release_pages(struct page **pages, int nr, bool cold)
+{
+	int i;
+	LIST_HEAD(pages_to_free);
+	struct zone *zone = NULL;
+	struct lruvec *lruvec;
+	unsigned long uninitialized_var(flags);
+	unsigned int uninitialized_var(lock_batch);
+
+	for (i = 0; i < nr; i++) {
+		struct page *page = pages[i];
+
+		if (unlikely(PageCompound(page))) {
+			if (zone) {
+				spin_unlock_irqrestore(&zone->lru_lock, flags);
+				zone = NULL;
+			}
+			put_compound_page(page);
+			continue;
+		}
+
+		/*
+		 * Make sure the IRQ-safe lock-holding time does not get
+		 * excessive with a continuous string of pages from the
+		 * same zone. The lock is held only if zone != NULL.
+		 */
+		if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
+			spin_unlock_irqrestore(&zone->lru_lock, flags);
+			zone = NULL;
+		}
+
+		if (!put_page_testzero(page))
+			continue;
+
+		if (PageLRU(page)) {
+			struct zone *pagezone = page_zone(page);
+
+			if (pagezone != zone) {
+				if (zone)
+					spin_unlock_irqrestore(&zone->lru_lock,
+									flags);
+				lock_batch = 0;
+				zone = pagezone;
+				spin_lock_irqsave(&zone->lru_lock, flags);
+			}
+
+			lruvec = mem_cgroup_page_lruvec(page, zone);
+			VM_BUG_ON_PAGE(!PageLRU(page), page);
+			__ClearPageLRU(page);
+			del_page_from_lru_list(page, lruvec, page_off_lru(page));
+		}
+
+		/* Clear Active bit in case of parallel mark_page_accessed */
+		__ClearPageActive(page);
+
+		list_add(&page->lru, &pages_to_free);
+	}
+	if (zone)
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+
+	mem_cgroup_uncharge_list(&pages_to_free);
+	free_hot_cold_page_list(&pages_to_free, cold);
+}
+EXPORT_SYMBOL(release_pages);
+
+/*
+ * The pages which we're about to release may be in the deferred lru-addition
+ * queues.  That would prevent them from really being freed right now.  That's
+ * OK from a correctness point of view but is inefficient - those pages may be
+ * cache-warm and we want to give them back to the page allocator ASAP.
+ *
+ * So __pagevec_release() will drain those queues here.  __pagevec_lru_add()
+ * and __pagevec_lru_add_active() call release_pages() directly to avoid
+ * mutual recursion.
+ */
+void __pagevec_release(struct pagevec *pvec)
+{
+	lru_add_drain();
+	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
+	pagevec_reinit(pvec);
+}
+EXPORT_SYMBOL(__pagevec_release);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/* used by __split_huge_page_refcount() */
+void lru_add_page_tail(struct page *page, struct page *page_tail,
+		       struct lruvec *lruvec, struct list_head *list)
+{
+	const int file = 0;
+
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+	VM_BUG_ON_PAGE(PageCompound(page_tail), page);
+	VM_BUG_ON_PAGE(PageLRU(page_tail), page);
+	VM_BUG_ON(NR_CPUS != 1 &&
+		  !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
+
+	if (!list)
+		SetPageLRU(page_tail);
+
+	if (likely(PageLRU(page)))
+		list_add_tail(&page_tail->lru, &page->lru);
+	else if (list) {
+		/* page reclaim is reclaiming a huge page */
+		get_page(page_tail);
+		list_add_tail(&page_tail->lru, list);
+	} else {
+		struct list_head *list_head;
+		/*
+		 * Head page has not yet been counted, as an hpage,
+		 * so we must account for each subpage individually.
+		 *
+		 * Use the standard add function to put page_tail on the list,
+		 * but then correct its position so they all end up in order.
+		 */
+		add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
+		list_head = page_tail->lru.prev;
+		list_move_tail(&page_tail->lru, list_head);
+	}
+
+	if (!PageUnevictable(page))
+		update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
+				 void *arg)
+{
+	int file = page_is_file_cache(page);
+	int active = PageActive(page);
+	enum lru_list lru = page_lru(page);
+
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+
+	SetPageLRU(page);
+	add_page_to_lru_list(page, lruvec, lru);
+	update_page_reclaim_stat(lruvec, file, active);
+	trace_mm_lru_insertion(page, lru);
+}
+
+/*
+ * Add the passed pages to the LRU, then drop the caller's refcount
+ * on them.  Reinitialises the caller's pagevec.
+ */
+void __pagevec_lru_add(struct pagevec *pvec)
+{
+	pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
+}
+EXPORT_SYMBOL(__pagevec_lru_add);
+
+/**
+ * pagevec_lookup_entries - gang pagecache lookup
+ * @pvec:	Where the resulting entries are placed
+ * @mapping:	The address_space to search
+ * @start:	The starting entry index
+ * @nr_entries:	The maximum number of entries
+ * @indices:	The cache indices corresponding to the entries in @pvec
+ *
+ * pagevec_lookup_entries() will search for and return a group of up
+ * to @nr_entries pages and shadow entries in the mapping.  All
+ * entries are placed in @pvec.  pagevec_lookup_entries() takes a
+ * reference against actual pages in @pvec.
+ *
+ * The search returns a group of mapping-contiguous entries with
+ * ascending indexes.  There may be holes in the indices due to
+ * not-present entries.
+ *
+ * pagevec_lookup_entries() returns the number of entries which were
+ * found.
+ */
+unsigned pagevec_lookup_entries(struct pagevec *pvec,
+				struct address_space *mapping,
+				pgoff_t start, unsigned nr_pages,
+				pgoff_t *indices)
+{
+	pvec->nr = find_get_entries(mapping, start, nr_pages,
+				    pvec->pages, indices);
+	return pagevec_count(pvec);
+}
+
+/**
+ * pagevec_remove_exceptionals - pagevec exceptionals pruning
+ * @pvec:	The pagevec to prune
+ *
+ * pagevec_lookup_entries() fills both pages and exceptional radix
+ * tree entries into the pagevec.  This function prunes all
+ * exceptionals from @pvec without leaving holes, so that it can be
+ * passed on to page-only pagevec operations.
+ */
+void pagevec_remove_exceptionals(struct pagevec *pvec)
+{
+	int i, j;
+
+	for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
+		struct page *page = pvec->pages[i];
+		if (!radix_tree_exceptional_entry(page))
+			pvec->pages[j++] = page;
+	}
+	pvec->nr = j;
+}
+
+/**
+ * pagevec_lookup - gang pagecache lookup
+ * @pvec:	Where the resulting pages are placed
+ * @mapping:	The address_space to search
+ * @start:	The starting page index
+ * @nr_pages:	The maximum number of pages
+ *
+ * pagevec_lookup() will search for and return a group of up to @nr_pages pages
+ * in the mapping.  The pages are placed in @pvec.  pagevec_lookup() takes a
+ * reference against the pages in @pvec.
+ *
+ * The search returns a group of mapping-contiguous pages with ascending
+ * indexes.  There may be holes in the indices due to not-present pages.
+ *
+ * pagevec_lookup() returns the number of pages which were found.
+ */
+unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
+		pgoff_t start, unsigned nr_pages)
+{
+	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
+	return pagevec_count(pvec);
+}
+EXPORT_SYMBOL(pagevec_lookup);
+
+unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
+		pgoff_t *index, int tag, unsigned nr_pages)
+{
+	pvec->nr = find_get_pages_tag(mapping, index, tag,
+					nr_pages, pvec->pages);
+	return pagevec_count(pvec);
+}
+EXPORT_SYMBOL(pagevec_lookup_tag);
+
+/*
+ * Perform any setup for the swap system
+ */
+void __init swap_setup(void)
+{
+	unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
+#ifdef CONFIG_SWAP
+	int i;
+
+	for (i = 0; i < MAX_SWAPFILES; i++)
+		spin_lock_init(&swapper_spaces[i].tree_lock);
+#endif
+
+	/* Use a smaller cluster for small-memory machines */
+	if (megs < 16)
+		page_cluster = 2;
+	else
+		page_cluster = 3;
+	/*
+	 * Right now other parts of the system means that we
+	 * _really_ don't want to cluster much more
+	 */
+}
diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
new file mode 100644
index 0000000..09f733b
--- /dev/null
+++ b/mm/swap_cgroup.c
@@ -0,0 +1,213 @@
+#include <linux/swap_cgroup.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+
+#include <linux/swapops.h> /* depends on mm.h include */
+
+static DEFINE_MUTEX(swap_cgroup_mutex);
+struct swap_cgroup_ctrl {
+	struct page **map;
+	unsigned long length;
+	spinlock_t	lock;
+};
+
+static struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
+
+struct swap_cgroup {
+	unsigned short		id;
+};
+#define SC_PER_PAGE	(PAGE_SIZE/sizeof(struct swap_cgroup))
+
+/*
+ * SwapCgroup implements "lookup" and "exchange" operations.
+ * In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
+ * against SwapCache. At swap_free(), this is accessed directly from swap.
+ *
+ * This means,
+ *  - we have no race in "exchange" when we're accessed via SwapCache because
+ *    SwapCache(and its swp_entry) is under lock.
+ *  - When called via swap_free(), there is no user of this entry and no race.
+ * Then, we don't need lock around "exchange".
+ *
+ * TODO: we can push these buffers out to HIGHMEM.
+ */
+
+/*
+ * allocate buffer for swap_cgroup.
+ */
+static int swap_cgroup_prepare(int type)
+{
+	struct page *page;
+	struct swap_cgroup_ctrl *ctrl;
+	unsigned long idx, max;
+
+	ctrl = &swap_cgroup_ctrl[type];
+
+	for (idx = 0; idx < ctrl->length; idx++) {
+		page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+		if (!page)
+			goto not_enough_page;
+		ctrl->map[idx] = page;
+
+		if (!(idx % SWAP_CLUSTER_MAX))
+			cond_resched();
+	}
+	return 0;
+not_enough_page:
+	max = idx;
+	for (idx = 0; idx < max; idx++)
+		__free_page(ctrl->map[idx]);
+
+	return -ENOMEM;
+}
+
+static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
+					struct swap_cgroup_ctrl **ctrlp)
+{
+	pgoff_t offset = swp_offset(ent);
+	struct swap_cgroup_ctrl *ctrl;
+	struct page *mappage;
+	struct swap_cgroup *sc;
+
+	ctrl = &swap_cgroup_ctrl[swp_type(ent)];
+	if (ctrlp)
+		*ctrlp = ctrl;
+
+	mappage = ctrl->map[offset / SC_PER_PAGE];
+	sc = page_address(mappage);
+	return sc + offset % SC_PER_PAGE;
+}
+
+/**
+ * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
+ * @ent: swap entry to be cmpxchged
+ * @old: old id
+ * @new: new id
+ *
+ * Returns old id at success, 0 at failure.
+ * (There is no mem_cgroup using 0 as its id)
+ */
+unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
+					unsigned short old, unsigned short new)
+{
+	struct swap_cgroup_ctrl *ctrl;
+	struct swap_cgroup *sc;
+	unsigned long flags;
+	unsigned short retval;
+
+	sc = lookup_swap_cgroup(ent, &ctrl);
+
+	spin_lock_irqsave(&ctrl->lock, flags);
+	retval = sc->id;
+	if (retval == old)
+		sc->id = new;
+	else
+		retval = 0;
+	spin_unlock_irqrestore(&ctrl->lock, flags);
+	return retval;
+}
+
+/**
+ * swap_cgroup_record - record mem_cgroup for this swp_entry.
+ * @ent: swap entry to be recorded into
+ * @id: mem_cgroup to be recorded
+ *
+ * Returns old value at success, 0 at failure.
+ * (Of course, old value can be 0.)
+ */
+unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
+{
+	struct swap_cgroup_ctrl *ctrl;
+	struct swap_cgroup *sc;
+	unsigned short old;
+	unsigned long flags;
+
+	sc = lookup_swap_cgroup(ent, &ctrl);
+
+	spin_lock_irqsave(&ctrl->lock, flags);
+	old = sc->id;
+	sc->id = id;
+	spin_unlock_irqrestore(&ctrl->lock, flags);
+
+	return old;
+}
+
+/**
+ * lookup_swap_cgroup_id - lookup mem_cgroup id tied to swap entry
+ * @ent: swap entry to be looked up.
+ *
+ * Returns ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)
+ */
+unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
+{
+	return lookup_swap_cgroup(ent, NULL)->id;
+}
+
+int swap_cgroup_swapon(int type, unsigned long max_pages)
+{
+	void *array;
+	unsigned long array_size;
+	unsigned long length;
+	struct swap_cgroup_ctrl *ctrl;
+
+	if (!do_swap_account)
+		return 0;
+
+	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
+	array_size = length * sizeof(void *);
+
+	array = vzalloc(array_size);
+	if (!array)
+		goto nomem;
+
+	ctrl = &swap_cgroup_ctrl[type];
+	mutex_lock(&swap_cgroup_mutex);
+	ctrl->length = length;
+	ctrl->map = array;
+	spin_lock_init(&ctrl->lock);
+	if (swap_cgroup_prepare(type)) {
+		/* memory shortage */
+		ctrl->map = NULL;
+		ctrl->length = 0;
+		mutex_unlock(&swap_cgroup_mutex);
+		vfree(array);
+		goto nomem;
+	}
+	mutex_unlock(&swap_cgroup_mutex);
+
+	return 0;
+nomem:
+	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
+	printk(KERN_INFO
+		"swap_cgroup can be disabled by swapaccount=0 boot option\n");
+	return -ENOMEM;
+}
+
+void swap_cgroup_swapoff(int type)
+{
+	struct page **map;
+	unsigned long i, length;
+	struct swap_cgroup_ctrl *ctrl;
+
+	if (!do_swap_account)
+		return;
+
+	mutex_lock(&swap_cgroup_mutex);
+	ctrl = &swap_cgroup_ctrl[type];
+	map = ctrl->map;
+	length = ctrl->length;
+	ctrl->map = NULL;
+	ctrl->length = 0;
+	mutex_unlock(&swap_cgroup_mutex);
+
+	if (map) {
+		for (i = 0; i < length; i++) {
+			struct page *page = map[i];
+			if (page)
+				__free_page(page);
+			if (!(i % SWAP_CLUSTER_MAX))
+				cond_resched();
+		}
+		vfree(map);
+	}
+}
diff --git a/mm/swap_state.c b/mm/swap_state.c
new file mode 100644
index 0000000..d504adb
--- /dev/null
+++ b/mm/swap_state.c
@@ -0,0 +1,501 @@
+/*
+ *  linux/mm/swap_state.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *  Swap reorganised 29.12.95, Stephen Tweedie
+ *
+ *  Rewritten to use page cache, (C) 1998 Stephen Tweedie
+ */
+#include <linux/mm.h>
+#include <linux/gfp.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/blkdev.h>
+#include <linux/pagevec.h>
+#include <linux/migrate.h>
+
+#include <asm/pgtable.h>
+
+/*
+ * swapper_space is a fiction, retained to simplify the path through
+ * vmscan's shrink_page_list.
+ */
+static const struct address_space_operations swap_aops = {
+	.writepage	= swap_writepage,
+	.set_page_dirty	= swap_set_page_dirty,
+#ifdef CONFIG_MIGRATION
+	.migratepage	= migrate_page,
+#endif
+};
+
+struct address_space swapper_spaces[MAX_SWAPFILES] = {
+	[0 ... MAX_SWAPFILES - 1] = {
+		.page_tree	= RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
+		.i_mmap_writable = ATOMIC_INIT(0),
+		.a_ops		= &swap_aops,
+	}
+};
+
+#define INC_CACHE_INFO(x)	do { swap_cache_info.x++; } while (0)
+
+static struct {
+	unsigned long add_total;
+	unsigned long del_total;
+	unsigned long find_success;
+	unsigned long find_total;
+} swap_cache_info;
+
+unsigned long total_swapcache_pages(void)
+{
+	int i;
+	unsigned long ret = 0;
+
+	for (i = 0; i < MAX_SWAPFILES; i++)
+		ret += swapper_spaces[i].nrpages;
+	return ret;
+}
+
+static atomic_t swapin_readahead_hits = ATOMIC_INIT(4);
+
+void show_swap_cache_info(void)
+{
+	printk("%lu pages in swap cache\n", total_swapcache_pages());
+	printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
+		swap_cache_info.add_total, swap_cache_info.del_total,
+		swap_cache_info.find_success, swap_cache_info.find_total);
+	printk("Free swap  = %ldkB\n",
+		get_nr_swap_pages() << (PAGE_SHIFT - 10));
+	printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
+}
+
+/*
+ * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
+ * but sets SwapCache flag and private instead of mapping and index.
+ */
+int __add_to_swap_cache(struct page *page, swp_entry_t entry)
+{
+	int error;
+	struct address_space *address_space;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(PageSwapCache(page), page);
+	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+
+	page_cache_get(page);
+	SetPageSwapCache(page);
+	set_page_private(page, entry.val);
+
+	address_space = swap_address_space(entry);
+	spin_lock_irq(&address_space->tree_lock);
+	error = radix_tree_insert(&address_space->page_tree,
+					entry.val, page);
+	if (likely(!error)) {
+		address_space->nrpages++;
+		__inc_zone_page_state(page, NR_FILE_PAGES);
+		INC_CACHE_INFO(add_total);
+	}
+	spin_unlock_irq(&address_space->tree_lock);
+
+	if (unlikely(error)) {
+		/*
+		 * Only the context which have set SWAP_HAS_CACHE flag
+		 * would call add_to_swap_cache().
+		 * So add_to_swap_cache() doesn't returns -EEXIST.
+		 */
+		VM_BUG_ON(error == -EEXIST);
+		set_page_private(page, 0UL);
+		ClearPageSwapCache(page);
+		page_cache_release(page);
+	}
+
+	return error;
+}
+
+
+int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
+{
+	int error;
+
+	error = radix_tree_maybe_preload(gfp_mask);
+	if (!error) {
+		error = __add_to_swap_cache(page, entry);
+		radix_tree_preload_end();
+	}
+	return error;
+}
+
+/*
+ * This must be called only on pages that have
+ * been verified to be in the swap cache.
+ */
+void __delete_from_swap_cache(struct page *page)
+{
+	swp_entry_t entry;
+	struct address_space *address_space;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
+	VM_BUG_ON_PAGE(PageWriteback(page), page);
+
+	entry.val = page_private(page);
+	address_space = swap_address_space(entry);
+	radix_tree_delete(&address_space->page_tree, page_private(page));
+	set_page_private(page, 0);
+	ClearPageSwapCache(page);
+	address_space->nrpages--;
+	__dec_zone_page_state(page, NR_FILE_PAGES);
+	INC_CACHE_INFO(del_total);
+}
+
+/**
+ * add_to_swap - allocate swap space for a page
+ * @page: page we want to move to swap
+ *
+ * Allocate swap space for the page and add the page to the
+ * swap cache.  Caller needs to hold the page lock. 
+ */
+int add_to_swap(struct page *page, struct list_head *list)
+{
+	swp_entry_t entry;
+	int err;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(!PageUptodate(page), page);
+
+	entry = get_swap_page();
+	if (!entry.val)
+		return 0;
+
+	if (unlikely(PageTransHuge(page)))
+		if (unlikely(split_huge_page_to_list(page, list))) {
+			swapcache_free(entry);
+			return 0;
+		}
+
+	/*
+	 * Radix-tree node allocations from PF_MEMALLOC contexts could
+	 * completely exhaust the page allocator. __GFP_NOMEMALLOC
+	 * stops emergency reserves from being allocated.
+	 *
+	 * TODO: this could cause a theoretical memory reclaim
+	 * deadlock in the swap out path.
+	 */
+	/*
+	 * Add it to the swap cache and mark it dirty
+	 */
+	err = add_to_swap_cache(page, entry,
+			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
+
+	if (!err) {	/* Success */
+		SetPageDirty(page);
+		return 1;
+	} else {	/* -ENOMEM radix-tree allocation failure */
+		/*
+		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
+		 * clear SWAP_HAS_CACHE flag.
+		 */
+		swapcache_free(entry);
+		return 0;
+	}
+}
+
+/*
+ * This must be called only on pages that have
+ * been verified to be in the swap cache and locked.
+ * It will never put the page into the free list,
+ * the caller has a reference on the page.
+ */
+void delete_from_swap_cache(struct page *page)
+{
+	swp_entry_t entry;
+	struct address_space *address_space;
+
+	entry.val = page_private(page);
+
+	address_space = swap_address_space(entry);
+	spin_lock_irq(&address_space->tree_lock);
+	__delete_from_swap_cache(page);
+	spin_unlock_irq(&address_space->tree_lock);
+
+	swapcache_free(entry);
+	page_cache_release(page);
+}
+
+/* 
+ * If we are the only user, then try to free up the swap cache. 
+ * 
+ * Its ok to check for PageSwapCache without the page lock
+ * here because we are going to recheck again inside
+ * try_to_free_swap() _with_ the lock.
+ * 					- Marcelo
+ */
+static inline void free_swap_cache(struct page *page)
+{
+	if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) {
+		try_to_free_swap(page);
+		unlock_page(page);
+	}
+}
+
+/* 
+ * Perform a free_page(), also freeing any swap cache associated with
+ * this page if it is the last user of the page.
+ */
+void free_page_and_swap_cache(struct page *page)
+{
+	free_swap_cache(page);
+	page_cache_release(page);
+}
+
+/*
+ * Passed an array of pages, drop them all from swapcache and then release
+ * them.  They are removed from the LRU and freed if this is their last use.
+ */
+void free_pages_and_swap_cache(struct page **pages, int nr)
+{
+	struct page **pagep = pages;
+	int i;
+
+	lru_add_drain();
+	for (i = 0; i < nr; i++)
+		free_swap_cache(pagep[i]);
+	release_pages(pagep, nr, false);
+}
+
+/*
+ * Lookup a swap entry in the swap cache. A found page will be returned
+ * unlocked and with its refcount incremented - we rely on the kernel
+ * lock getting page table operations atomic even if we drop the page
+ * lock before returning.
+ */
+struct page * lookup_swap_cache(swp_entry_t entry)
+{
+	struct page *page;
+
+	page = find_get_page(swap_address_space(entry), entry.val);
+
+	if (page) {
+		INC_CACHE_INFO(find_success);
+		if (TestClearPageReadahead(page))
+			atomic_inc(&swapin_readahead_hits);
+	}
+
+	INC_CACHE_INFO(find_total);
+	return page;
+}
+
+struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
+			struct vm_area_struct *vma, unsigned long addr,
+			bool *new_page_allocated)
+{
+	struct page *found_page, *new_page = NULL;
+	struct address_space *swapper_space = swap_address_space(entry);
+	int err;
+	*new_page_allocated = false;
+
+	do {
+		/*
+		 * First check the swap cache.  Since this is normally
+		 * called after lookup_swap_cache() failed, re-calling
+		 * that would confuse statistics.
+		 */
+		found_page = find_get_page(swapper_space, entry.val);
+		if (found_page)
+			break;
+
+		/*
+		 * Get a new page to read into from swap.
+		 */
+		if (!new_page) {
+			new_page = alloc_page_vma(gfp_mask, vma, addr);
+			if (!new_page)
+				break;		/* Out of memory */
+		}
+
+		/*
+		 * call radix_tree_preload() while we can wait.
+		 */
+		err = radix_tree_maybe_preload(gfp_mask & GFP_KERNEL);
+		if (err)
+			break;
+
+		/*
+		 * Swap entry may have been freed since our caller observed it.
+		 */
+		err = swapcache_prepare(entry);
+		if (err == -EEXIST) {
+			radix_tree_preload_end();
+			/*
+			 * We might race against get_swap_page() and stumble
+			 * across a SWAP_HAS_CACHE swap_map entry whose page
+			 * has not been brought into the swapcache yet, while
+			 * the other end is scheduled away waiting on discard
+			 * I/O completion at scan_swap_map().
+			 *
+			 * In order to avoid turning this transitory state
+			 * into a permanent loop around this -EEXIST case
+			 * if !CONFIG_PREEMPT and the I/O completion happens
+			 * to be waiting on the CPU waitqueue where we are now
+			 * busy looping, we just conditionally invoke the
+			 * scheduler here, if there are some more important
+			 * tasks to run.
+			 */
+			cond_resched();
+			continue;
+		}
+		if (err) {		/* swp entry is obsolete ? */
+			radix_tree_preload_end();
+			break;
+		}
+
+		/* May fail (-ENOMEM) if radix-tree node allocation failed. */
+		__set_page_locked(new_page);
+		SetPageSwapBacked(new_page);
+		err = __add_to_swap_cache(new_page, entry);
+		if (likely(!err)) {
+			radix_tree_preload_end();
+			/*
+			 * Initiate read into locked page and return.
+			 */
+			lru_cache_add_anon(new_page);
+			*new_page_allocated = true;
+			return new_page;
+		}
+		radix_tree_preload_end();
+		ClearPageSwapBacked(new_page);
+		__clear_page_locked(new_page);
+		/*
+		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
+		 * clear SWAP_HAS_CACHE flag.
+		 */
+		swapcache_free(entry);
+	} while (err != -ENOMEM);
+
+	if (new_page)
+		page_cache_release(new_page);
+	return found_page;
+}
+
+/*
+ * Locate a page of swap in physical memory, reserving swap cache space
+ * and reading the disk if it is not already cached.
+ * A failure return means that either the page allocation failed or that
+ * the swap entry is no longer in use.
+ */
+struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	bool page_was_allocated;
+	struct page *retpage = __read_swap_cache_async(entry, gfp_mask,
+			vma, addr, &page_was_allocated);
+
+	if (page_was_allocated)
+		swap_readpage(retpage);
+
+	return retpage;
+}
+
+static unsigned long swapin_nr_pages(unsigned long offset)
+{
+	static unsigned long prev_offset;
+	unsigned int pages, max_pages, last_ra;
+	static atomic_t last_readahead_pages;
+
+	max_pages = 1 << READ_ONCE(page_cluster);
+	if (max_pages <= 1)
+		return 1;
+
+	/*
+	 * This heuristic has been found to work well on both sequential and
+	 * random loads, swapping to hard disk or to SSD: please don't ask
+	 * what the "+ 2" means, it just happens to work well, that's all.
+	 */
+	pages = atomic_xchg(&swapin_readahead_hits, 0) + 2;
+	if (pages == 2) {
+		/*
+		 * We can have no readahead hits to judge by: but must not get
+		 * stuck here forever, so check for an adjacent offset instead
+		 * (and don't even bother to check whether swap type is same).
+		 */
+		if (offset != prev_offset + 1 && offset != prev_offset - 1)
+			pages = 1;
+		prev_offset = offset;
+	} else {
+		unsigned int roundup = 4;
+		while (roundup < pages)
+			roundup <<= 1;
+		pages = roundup;
+	}
+
+	if (pages > max_pages)
+		pages = max_pages;
+
+	/* Don't shrink readahead too fast */
+	last_ra = atomic_read(&last_readahead_pages) / 2;
+	if (pages < last_ra)
+		pages = last_ra;
+	atomic_set(&last_readahead_pages, pages);
+
+	return pages;
+}
+
+/**
+ * swapin_readahead - swap in pages in hope we need them soon
+ * @entry: swap entry of this memory
+ * @gfp_mask: memory allocation flags
+ * @vma: user vma this address belongs to
+ * @addr: target address for mempolicy
+ *
+ * Returns the struct page for entry and addr, after queueing swapin.
+ *
+ * Primitive swap readahead code. We simply read an aligned block of
+ * (1 << page_cluster) entries in the swap area. This method is chosen
+ * because it doesn't cost us any seek time.  We also make sure to queue
+ * the 'original' request together with the readahead ones...
+ *
+ * This has been extended to use the NUMA policies from the mm triggering
+ * the readahead.
+ *
+ * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
+ */
+struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	struct page *page;
+	unsigned long entry_offset = swp_offset(entry);
+	unsigned long offset = entry_offset;
+	unsigned long start_offset, end_offset;
+	unsigned long mask;
+	struct blk_plug plug;
+
+	mask = swapin_nr_pages(offset) - 1;
+	if (!mask)
+		goto skip;
+
+	/* Read a page_cluster sized and aligned cluster around offset. */
+	start_offset = offset & ~mask;
+	end_offset = offset | mask;
+	if (!start_offset)	/* First page is swap header. */
+		start_offset++;
+
+	blk_start_plug(&plug);
+	for (offset = start_offset; offset <= end_offset ; offset++) {
+		/* Ok, do the async read-ahead now */
+		page = read_swap_cache_async(swp_entry(swp_type(entry), offset),
+						gfp_mask, vma, addr);
+		if (!page)
+			continue;
+		if (offset != entry_offset)
+			SetPageReadahead(page);
+		page_cache_release(page);
+	}
+	blk_finish_plug(&plug);
+
+	lru_add_drain();	/* Push any new pages onto the LRU now */
+skip:
+	return read_swap_cache_async(entry, gfp_mask, vma, addr);
+}
diff --git a/mm/swapfile.c b/mm/swapfile.c
new file mode 100644
index 0000000..c1a0f3d
--- /dev/null
+++ b/mm/swapfile.c
@@ -0,0 +1,2973 @@
+/*
+ *  linux/mm/swapfile.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *  Swap reorganised 29.12.95, Stephen Tweedie
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/vmalloc.h>
+#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/shmem_fs.h>
+#include <linux/blkdev.h>
+#include <linux/random.h>
+#include <linux/writeback.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/security.h>
+#include <linux/backing-dev.h>
+#include <linux/mutex.h>
+#include <linux/capability.h>
+#include <linux/syscalls.h>
+#include <linux/memcontrol.h>
+#include <linux/poll.h>
+#include <linux/oom.h>
+#include <linux/frontswap.h>
+#include <linux/swapfile.h>
+#include <linux/export.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <linux/swapops.h>
+#include <linux/swap_cgroup.h>
+
+static bool swap_count_continued(struct swap_info_struct *, pgoff_t,
+				 unsigned char);
+static void free_swap_count_continuations(struct swap_info_struct *);
+static sector_t map_swap_entry(swp_entry_t, struct block_device**);
+
+DEFINE_SPINLOCK(swap_lock);
+static unsigned int nr_swapfiles;
+atomic_long_t nr_swap_pages;
+/* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
+long total_swap_pages;
+static int least_priority;
+
+static const char Bad_file[] = "Bad swap file entry ";
+static const char Unused_file[] = "Unused swap file entry ";
+static const char Bad_offset[] = "Bad swap offset entry ";
+static const char Unused_offset[] = "Unused swap offset entry ";
+
+/*
+ * all active swap_info_structs
+ * protected with swap_lock, and ordered by priority.
+ */
+PLIST_HEAD(swap_active_head);
+
+/*
+ * all available (active, not full) swap_info_structs
+ * protected with swap_avail_lock, ordered by priority.
+ * This is used by get_swap_page() instead of swap_active_head
+ * because swap_active_head includes all swap_info_structs,
+ * but get_swap_page() doesn't need to look at full ones.
+ * This uses its own lock instead of swap_lock because when a
+ * swap_info_struct changes between not-full/full, it needs to
+ * add/remove itself to/from this list, but the swap_info_struct->lock
+ * is held and the locking order requires swap_lock to be taken
+ * before any swap_info_struct->lock.
+ */
+static PLIST_HEAD(swap_avail_head);
+static DEFINE_SPINLOCK(swap_avail_lock);
+
+struct swap_info_struct *swap_info[MAX_SWAPFILES];
+
+static DEFINE_MUTEX(swapon_mutex);
+
+static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait);
+/* Activity counter to indicate that a swapon or swapoff has occurred */
+static atomic_t proc_poll_event = ATOMIC_INIT(0);
+
+static inline unsigned char swap_count(unsigned char ent)
+{
+	return ent & ~SWAP_HAS_CACHE;	/* may include SWAP_HAS_CONT flag */
+}
+
+/* returns 1 if swap entry is freed */
+static int
+__try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
+{
+	swp_entry_t entry = swp_entry(si->type, offset);
+	struct page *page;
+	int ret = 0;
+
+	page = find_get_page(swap_address_space(entry), entry.val);
+	if (!page)
+		return 0;
+	/*
+	 * This function is called from scan_swap_map() and it's called
+	 * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here.
+	 * We have to use trylock for avoiding deadlock. This is a special
+	 * case and you should use try_to_free_swap() with explicit lock_page()
+	 * in usual operations.
+	 */
+	if (trylock_page(page)) {
+		ret = try_to_free_swap(page);
+		unlock_page(page);
+	}
+	page_cache_release(page);
+	return ret;
+}
+
+/*
+ * swapon tell device that all the old swap contents can be discarded,
+ * to allow the swap device to optimize its wear-levelling.
+ */
+static int discard_swap(struct swap_info_struct *si)
+{
+	struct swap_extent *se;
+	sector_t start_block;
+	sector_t nr_blocks;
+	int err = 0;
+
+	/* Do not discard the swap header page! */
+	se = &si->first_swap_extent;
+	start_block = (se->start_block + 1) << (PAGE_SHIFT - 9);
+	nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
+	if (nr_blocks) {
+		err = blkdev_issue_discard(si->bdev, start_block,
+				nr_blocks, GFP_KERNEL, 0);
+		if (err)
+			return err;
+		cond_resched();
+	}
+
+	list_for_each_entry(se, &si->first_swap_extent.list, list) {
+		start_block = se->start_block << (PAGE_SHIFT - 9);
+		nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
+
+		err = blkdev_issue_discard(si->bdev, start_block,
+				nr_blocks, GFP_KERNEL, 0);
+		if (err)
+			break;
+
+		cond_resched();
+	}
+	return err;		/* That will often be -EOPNOTSUPP */
+}
+
+/*
+ * swap allocation tell device that a cluster of swap can now be discarded,
+ * to allow the swap device to optimize its wear-levelling.
+ */
+static void discard_swap_cluster(struct swap_info_struct *si,
+				 pgoff_t start_page, pgoff_t nr_pages)
+{
+	struct swap_extent *se = si->curr_swap_extent;
+	int found_extent = 0;
+
+	while (nr_pages) {
+		struct list_head *lh;
+
+		if (se->start_page <= start_page &&
+		    start_page < se->start_page + se->nr_pages) {
+			pgoff_t offset = start_page - se->start_page;
+			sector_t start_block = se->start_block + offset;
+			sector_t nr_blocks = se->nr_pages - offset;
+
+			if (nr_blocks > nr_pages)
+				nr_blocks = nr_pages;
+			start_page += nr_blocks;
+			nr_pages -= nr_blocks;
+
+			if (!found_extent++)
+				si->curr_swap_extent = se;
+
+			start_block <<= PAGE_SHIFT - 9;
+			nr_blocks <<= PAGE_SHIFT - 9;
+			if (blkdev_issue_discard(si->bdev, start_block,
+				    nr_blocks, GFP_NOIO, 0))
+				break;
+		}
+
+		lh = se->list.next;
+		se = list_entry(lh, struct swap_extent, list);
+	}
+}
+
+#define SWAPFILE_CLUSTER	256
+#define LATENCY_LIMIT		256
+
+static inline void cluster_set_flag(struct swap_cluster_info *info,
+	unsigned int flag)
+{
+	info->flags = flag;
+}
+
+static inline unsigned int cluster_count(struct swap_cluster_info *info)
+{
+	return info->data;
+}
+
+static inline void cluster_set_count(struct swap_cluster_info *info,
+				     unsigned int c)
+{
+	info->data = c;
+}
+
+static inline void cluster_set_count_flag(struct swap_cluster_info *info,
+					 unsigned int c, unsigned int f)
+{
+	info->flags = f;
+	info->data = c;
+}
+
+static inline unsigned int cluster_next(struct swap_cluster_info *info)
+{
+	return info->data;
+}
+
+static inline void cluster_set_next(struct swap_cluster_info *info,
+				    unsigned int n)
+{
+	info->data = n;
+}
+
+static inline void cluster_set_next_flag(struct swap_cluster_info *info,
+					 unsigned int n, unsigned int f)
+{
+	info->flags = f;
+	info->data = n;
+}
+
+static inline bool cluster_is_free(struct swap_cluster_info *info)
+{
+	return info->flags & CLUSTER_FLAG_FREE;
+}
+
+static inline bool cluster_is_null(struct swap_cluster_info *info)
+{
+	return info->flags & CLUSTER_FLAG_NEXT_NULL;
+}
+
+static inline void cluster_set_null(struct swap_cluster_info *info)
+{
+	info->flags = CLUSTER_FLAG_NEXT_NULL;
+	info->data = 0;
+}
+
+/* Add a cluster to discard list and schedule it to do discard */
+static void swap_cluster_schedule_discard(struct swap_info_struct *si,
+		unsigned int idx)
+{
+	/*
+	 * If scan_swap_map() can't find a free cluster, it will check
+	 * si->swap_map directly. To make sure the discarding cluster isn't
+	 * taken by scan_swap_map(), mark the swap entries bad (occupied). It
+	 * will be cleared after discard
+	 */
+	memset(si->swap_map + idx * SWAPFILE_CLUSTER,
+			SWAP_MAP_BAD, SWAPFILE_CLUSTER);
+
+	if (cluster_is_null(&si->discard_cluster_head)) {
+		cluster_set_next_flag(&si->discard_cluster_head,
+						idx, 0);
+		cluster_set_next_flag(&si->discard_cluster_tail,
+						idx, 0);
+	} else {
+		unsigned int tail = cluster_next(&si->discard_cluster_tail);
+		cluster_set_next(&si->cluster_info[tail], idx);
+		cluster_set_next_flag(&si->discard_cluster_tail,
+						idx, 0);
+	}
+
+	schedule_work(&si->discard_work);
+}
+
+/*
+ * Doing discard actually. After a cluster discard is finished, the cluster
+ * will be added to free cluster list. caller should hold si->lock.
+*/
+static void swap_do_scheduled_discard(struct swap_info_struct *si)
+{
+	struct swap_cluster_info *info;
+	unsigned int idx;
+
+	info = si->cluster_info;
+
+	while (!cluster_is_null(&si->discard_cluster_head)) {
+		idx = cluster_next(&si->discard_cluster_head);
+
+		cluster_set_next_flag(&si->discard_cluster_head,
+						cluster_next(&info[idx]), 0);
+		if (cluster_next(&si->discard_cluster_tail) == idx) {
+			cluster_set_null(&si->discard_cluster_head);
+			cluster_set_null(&si->discard_cluster_tail);
+		}
+		spin_unlock(&si->lock);
+
+		discard_swap_cluster(si, idx * SWAPFILE_CLUSTER,
+				SWAPFILE_CLUSTER);
+
+		spin_lock(&si->lock);
+		cluster_set_flag(&info[idx], CLUSTER_FLAG_FREE);
+		if (cluster_is_null(&si->free_cluster_head)) {
+			cluster_set_next_flag(&si->free_cluster_head,
+						idx, 0);
+			cluster_set_next_flag(&si->free_cluster_tail,
+						idx, 0);
+		} else {
+			unsigned int tail;
+
+			tail = cluster_next(&si->free_cluster_tail);
+			cluster_set_next(&info[tail], idx);
+			cluster_set_next_flag(&si->free_cluster_tail,
+						idx, 0);
+		}
+		memset(si->swap_map + idx * SWAPFILE_CLUSTER,
+				0, SWAPFILE_CLUSTER);
+	}
+}
+
+static void swap_discard_work(struct work_struct *work)
+{
+	struct swap_info_struct *si;
+
+	si = container_of(work, struct swap_info_struct, discard_work);
+
+	spin_lock(&si->lock);
+	swap_do_scheduled_discard(si);
+	spin_unlock(&si->lock);
+}
+
+/*
+ * The cluster corresponding to page_nr will be used. The cluster will be
+ * removed from free cluster list and its usage counter will be increased.
+ */
+static void inc_cluster_info_page(struct swap_info_struct *p,
+	struct swap_cluster_info *cluster_info, unsigned long page_nr)
+{
+	unsigned long idx = page_nr / SWAPFILE_CLUSTER;
+
+	if (!cluster_info)
+		return;
+	if (cluster_is_free(&cluster_info[idx])) {
+		VM_BUG_ON(cluster_next(&p->free_cluster_head) != idx);
+		cluster_set_next_flag(&p->free_cluster_head,
+			cluster_next(&cluster_info[idx]), 0);
+		if (cluster_next(&p->free_cluster_tail) == idx) {
+			cluster_set_null(&p->free_cluster_tail);
+			cluster_set_null(&p->free_cluster_head);
+		}
+		cluster_set_count_flag(&cluster_info[idx], 0, 0);
+	}
+
+	VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER);
+	cluster_set_count(&cluster_info[idx],
+		cluster_count(&cluster_info[idx]) + 1);
+}
+
+/*
+ * The cluster corresponding to page_nr decreases one usage. If the usage
+ * counter becomes 0, which means no page in the cluster is in using, we can
+ * optionally discard the cluster and add it to free cluster list.
+ */
+static void dec_cluster_info_page(struct swap_info_struct *p,
+	struct swap_cluster_info *cluster_info, unsigned long page_nr)
+{
+	unsigned long idx = page_nr / SWAPFILE_CLUSTER;
+
+	if (!cluster_info)
+		return;
+
+	VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0);
+	cluster_set_count(&cluster_info[idx],
+		cluster_count(&cluster_info[idx]) - 1);
+
+	if (cluster_count(&cluster_info[idx]) == 0) {
+		/*
+		 * If the swap is discardable, prepare discard the cluster
+		 * instead of free it immediately. The cluster will be freed
+		 * after discard.
+		 */
+		if ((p->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) ==
+				 (SWP_WRITEOK | SWP_PAGE_DISCARD)) {
+			swap_cluster_schedule_discard(p, idx);
+			return;
+		}
+
+		cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE);
+		if (cluster_is_null(&p->free_cluster_head)) {
+			cluster_set_next_flag(&p->free_cluster_head, idx, 0);
+			cluster_set_next_flag(&p->free_cluster_tail, idx, 0);
+		} else {
+			unsigned int tail = cluster_next(&p->free_cluster_tail);
+			cluster_set_next(&cluster_info[tail], idx);
+			cluster_set_next_flag(&p->free_cluster_tail, idx, 0);
+		}
+	}
+}
+
+/*
+ * It's possible scan_swap_map() uses a free cluster in the middle of free
+ * cluster list. Avoiding such abuse to avoid list corruption.
+ */
+static bool
+scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si,
+	unsigned long offset)
+{
+	struct percpu_cluster *percpu_cluster;
+	bool conflict;
+
+	offset /= SWAPFILE_CLUSTER;
+	conflict = !cluster_is_null(&si->free_cluster_head) &&
+		offset != cluster_next(&si->free_cluster_head) &&
+		cluster_is_free(&si->cluster_info[offset]);
+
+	if (!conflict)
+		return false;
+
+	percpu_cluster = this_cpu_ptr(si->percpu_cluster);
+	cluster_set_null(&percpu_cluster->index);
+	return true;
+}
+
+/*
+ * Try to get a swap entry from current cpu's swap entry pool (a cluster). This
+ * might involve allocating a new cluster for current CPU too.
+ */
+static void scan_swap_map_try_ssd_cluster(struct swap_info_struct *si,
+	unsigned long *offset, unsigned long *scan_base)
+{
+	struct percpu_cluster *cluster;
+	bool found_free;
+	unsigned long tmp;
+
+new_cluster:
+	cluster = this_cpu_ptr(si->percpu_cluster);
+	if (cluster_is_null(&cluster->index)) {
+		if (!cluster_is_null(&si->free_cluster_head)) {
+			cluster->index = si->free_cluster_head;
+			cluster->next = cluster_next(&cluster->index) *
+					SWAPFILE_CLUSTER;
+		} else if (!cluster_is_null(&si->discard_cluster_head)) {
+			/*
+			 * we don't have free cluster but have some clusters in
+			 * discarding, do discard now and reclaim them
+			 */
+			swap_do_scheduled_discard(si);
+			*scan_base = *offset = si->cluster_next;
+			goto new_cluster;
+		} else
+			return;
+	}
+
+	found_free = false;
+
+	/*
+	 * Other CPUs can use our cluster if they can't find a free cluster,
+	 * check if there is still free entry in the cluster
+	 */
+	tmp = cluster->next;
+	while (tmp < si->max && tmp < (cluster_next(&cluster->index) + 1) *
+	       SWAPFILE_CLUSTER) {
+		if (!si->swap_map[tmp]) {
+			found_free = true;
+			break;
+		}
+		tmp++;
+	}
+	if (!found_free) {
+		cluster_set_null(&cluster->index);
+		goto new_cluster;
+	}
+	cluster->next = tmp + 1;
+	*offset = tmp;
+	*scan_base = tmp;
+}
+
+static unsigned long scan_swap_map(struct swap_info_struct *si,
+				   unsigned char usage)
+{
+	unsigned long offset;
+	unsigned long scan_base;
+	unsigned long last_in_cluster = 0;
+	int latency_ration = LATENCY_LIMIT;
+
+	/*
+	 * We try to cluster swap pages by allocating them sequentially
+	 * in swap.  Once we've allocated SWAPFILE_CLUSTER pages this
+	 * way, however, we resort to first-free allocation, starting
+	 * a new cluster.  This prevents us from scattering swap pages
+	 * all over the entire swap partition, so that we reduce
+	 * overall disk seek times between swap pages.  -- sct
+	 * But we do now try to find an empty cluster.  -Andrea
+	 * And we let swap pages go all over an SSD partition.  Hugh
+	 */
+
+	si->flags += SWP_SCANNING;
+	scan_base = offset = si->cluster_next;
+
+	/* SSD algorithm */
+	if (si->cluster_info) {
+		scan_swap_map_try_ssd_cluster(si, &offset, &scan_base);
+		goto checks;
+	}
+
+	if (unlikely(!si->cluster_nr--)) {
+		if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) {
+			si->cluster_nr = SWAPFILE_CLUSTER - 1;
+			goto checks;
+		}
+
+		spin_unlock(&si->lock);
+
+		/*
+		 * If seek is expensive, start searching for new cluster from
+		 * start of partition, to minimize the span of allocated swap.
+		 * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
+		 * case, just handled by scan_swap_map_try_ssd_cluster() above.
+		 */
+		scan_base = offset = si->lowest_bit;
+		last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
+
+		/* Locate the first empty (unaligned) cluster */
+		for (; last_in_cluster <= si->highest_bit; offset++) {
+			if (si->swap_map[offset])
+				last_in_cluster = offset + SWAPFILE_CLUSTER;
+			else if (offset == last_in_cluster) {
+				spin_lock(&si->lock);
+				offset -= SWAPFILE_CLUSTER - 1;
+				si->cluster_next = offset;
+				si->cluster_nr = SWAPFILE_CLUSTER - 1;
+				goto checks;
+			}
+			if (unlikely(--latency_ration < 0)) {
+				cond_resched();
+				latency_ration = LATENCY_LIMIT;
+			}
+		}
+
+		offset = scan_base;
+		spin_lock(&si->lock);
+		si->cluster_nr = SWAPFILE_CLUSTER - 1;
+	}
+
+checks:
+	if (si->cluster_info) {
+		while (scan_swap_map_ssd_cluster_conflict(si, offset))
+			scan_swap_map_try_ssd_cluster(si, &offset, &scan_base);
+	}
+	if (!(si->flags & SWP_WRITEOK))
+		goto no_page;
+	if (!si->highest_bit)
+		goto no_page;
+	if (offset > si->highest_bit)
+		scan_base = offset = si->lowest_bit;
+
+	/* reuse swap entry of cache-only swap if not busy. */
+	if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+		int swap_was_freed;
+		spin_unlock(&si->lock);
+		swap_was_freed = __try_to_reclaim_swap(si, offset);
+		spin_lock(&si->lock);
+		/* entry was freed successfully, try to use this again */
+		if (swap_was_freed)
+			goto checks;
+		goto scan; /* check next one */
+	}
+
+	if (si->swap_map[offset])
+		goto scan;
+
+	if (offset == si->lowest_bit)
+		si->lowest_bit++;
+	if (offset == si->highest_bit)
+		si->highest_bit--;
+	si->inuse_pages++;
+	if (si->inuse_pages == si->pages) {
+		si->lowest_bit = si->max;
+		si->highest_bit = 0;
+		spin_lock(&swap_avail_lock);
+		plist_del(&si->avail_list, &swap_avail_head);
+		spin_unlock(&swap_avail_lock);
+	}
+	si->swap_map[offset] = usage;
+	inc_cluster_info_page(si, si->cluster_info, offset);
+	si->cluster_next = offset + 1;
+	si->flags -= SWP_SCANNING;
+
+	return offset;
+
+scan:
+	spin_unlock(&si->lock);
+	while (++offset <= si->highest_bit) {
+		if (!si->swap_map[offset]) {
+			spin_lock(&si->lock);
+			goto checks;
+		}
+		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+			spin_lock(&si->lock);
+			goto checks;
+		}
+		if (unlikely(--latency_ration < 0)) {
+			cond_resched();
+			latency_ration = LATENCY_LIMIT;
+		}
+	}
+	offset = si->lowest_bit;
+	while (offset < scan_base) {
+		if (!si->swap_map[offset]) {
+			spin_lock(&si->lock);
+			goto checks;
+		}
+		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+			spin_lock(&si->lock);
+			goto checks;
+		}
+		if (unlikely(--latency_ration < 0)) {
+			cond_resched();
+			latency_ration = LATENCY_LIMIT;
+		}
+		offset++;
+	}
+	spin_lock(&si->lock);
+
+no_page:
+	si->flags -= SWP_SCANNING;
+	return 0;
+}
+
+swp_entry_t get_swap_page(void)
+{
+	struct swap_info_struct *si, *next;
+	pgoff_t offset;
+
+	if (atomic_long_read(&nr_swap_pages) <= 0)
+		goto noswap;
+	atomic_long_dec(&nr_swap_pages);
+
+	spin_lock(&swap_avail_lock);
+
+start_over:
+	plist_for_each_entry_safe(si, next, &swap_avail_head, avail_list) {
+		/* requeue si to after same-priority siblings */
+		plist_requeue(&si->avail_list, &swap_avail_head);
+		spin_unlock(&swap_avail_lock);
+		spin_lock(&si->lock);
+		if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) {
+			spin_lock(&swap_avail_lock);
+			if (plist_node_empty(&si->avail_list)) {
+				spin_unlock(&si->lock);
+				goto nextsi;
+			}
+			WARN(!si->highest_bit,
+			     "swap_info %d in list but !highest_bit\n",
+			     si->type);
+			WARN(!(si->flags & SWP_WRITEOK),
+			     "swap_info %d in list but !SWP_WRITEOK\n",
+			     si->type);
+			plist_del(&si->avail_list, &swap_avail_head);
+			spin_unlock(&si->lock);
+			goto nextsi;
+		}
+
+		/* This is called for allocating swap entry for cache */
+		offset = scan_swap_map(si, SWAP_HAS_CACHE);
+		spin_unlock(&si->lock);
+		if (offset)
+			return swp_entry(si->type, offset);
+		pr_debug("scan_swap_map of si %d failed to find offset\n",
+		       si->type);
+		spin_lock(&swap_avail_lock);
+nextsi:
+		/*
+		 * if we got here, it's likely that si was almost full before,
+		 * and since scan_swap_map() can drop the si->lock, multiple
+		 * callers probably all tried to get a page from the same si
+		 * and it filled up before we could get one; or, the si filled
+		 * up between us dropping swap_avail_lock and taking si->lock.
+		 * Since we dropped the swap_avail_lock, the swap_avail_head
+		 * list may have been modified; so if next is still in the
+		 * swap_avail_head list then try it, otherwise start over.
+		 */
+		if (plist_node_empty(&next->avail_list))
+			goto start_over;
+	}
+
+	spin_unlock(&swap_avail_lock);
+
+	atomic_long_inc(&nr_swap_pages);
+noswap:
+	return (swp_entry_t) {0};
+}
+
+/* The only caller of this function is now suspend routine */
+swp_entry_t get_swap_page_of_type(int type)
+{
+	struct swap_info_struct *si;
+	pgoff_t offset;
+
+	si = swap_info[type];
+	spin_lock(&si->lock);
+	if (si && (si->flags & SWP_WRITEOK)) {
+		atomic_long_dec(&nr_swap_pages);
+		/* This is called for allocating swap entry, not cache */
+		offset = scan_swap_map(si, 1);
+		if (offset) {
+			spin_unlock(&si->lock);
+			return swp_entry(type, offset);
+		}
+		atomic_long_inc(&nr_swap_pages);
+	}
+	spin_unlock(&si->lock);
+	return (swp_entry_t) {0};
+}
+
+static struct swap_info_struct *swap_info_get(swp_entry_t entry)
+{
+	struct swap_info_struct *p;
+	unsigned long offset, type;
+
+	if (!entry.val)
+		goto out;
+	type = swp_type(entry);
+	if (type >= nr_swapfiles)
+		goto bad_nofile;
+	p = swap_info[type];
+	if (!(p->flags & SWP_USED))
+		goto bad_device;
+	offset = swp_offset(entry);
+	if (offset >= p->max)
+		goto bad_offset;
+	if (!p->swap_map[offset])
+		goto bad_free;
+	spin_lock(&p->lock);
+	return p;
+
+bad_free:
+	pr_err("swap_free: %s%08lx\n", Unused_offset, entry.val);
+	goto out;
+bad_offset:
+	pr_err("swap_free: %s%08lx\n", Bad_offset, entry.val);
+	goto out;
+bad_device:
+	pr_err("swap_free: %s%08lx\n", Unused_file, entry.val);
+	goto out;
+bad_nofile:
+	pr_err("swap_free: %s%08lx\n", Bad_file, entry.val);
+out:
+	return NULL;
+}
+
+static unsigned char swap_entry_free(struct swap_info_struct *p,
+				     swp_entry_t entry, unsigned char usage)
+{
+	unsigned long offset = swp_offset(entry);
+	unsigned char count;
+	unsigned char has_cache;
+
+	count = p->swap_map[offset];
+	has_cache = count & SWAP_HAS_CACHE;
+	count &= ~SWAP_HAS_CACHE;
+
+	if (usage == SWAP_HAS_CACHE) {
+		VM_BUG_ON(!has_cache);
+		has_cache = 0;
+	} else if (count == SWAP_MAP_SHMEM) {
+		/*
+		 * Or we could insist on shmem.c using a special
+		 * swap_shmem_free() and free_shmem_swap_and_cache()...
+		 */
+		count = 0;
+	} else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) {
+		if (count == COUNT_CONTINUED) {
+			if (swap_count_continued(p, offset, count))
+				count = SWAP_MAP_MAX | COUNT_CONTINUED;
+			else
+				count = SWAP_MAP_MAX;
+		} else
+			count--;
+	}
+
+	if (!count)
+		mem_cgroup_uncharge_swap(entry);
+
+	usage = count | has_cache;
+	p->swap_map[offset] = usage;
+
+	/* free if no reference */
+	if (!usage) {
+		dec_cluster_info_page(p, p->cluster_info, offset);
+		if (offset < p->lowest_bit)
+			p->lowest_bit = offset;
+		if (offset > p->highest_bit) {
+			bool was_full = !p->highest_bit;
+			p->highest_bit = offset;
+			if (was_full && (p->flags & SWP_WRITEOK)) {
+				spin_lock(&swap_avail_lock);
+				WARN_ON(!plist_node_empty(&p->avail_list));
+				if (plist_node_empty(&p->avail_list))
+					plist_add(&p->avail_list,
+						  &swap_avail_head);
+				spin_unlock(&swap_avail_lock);
+			}
+		}
+		atomic_long_inc(&nr_swap_pages);
+		p->inuse_pages--;
+		frontswap_invalidate_page(p->type, offset);
+		if (p->flags & SWP_BLKDEV) {
+			struct gendisk *disk = p->bdev->bd_disk;
+			if (disk->fops->swap_slot_free_notify)
+				disk->fops->swap_slot_free_notify(p->bdev,
+								  offset);
+		}
+	}
+
+	return usage;
+}
+
+/*
+ * Caller has made sure that the swap device corresponding to entry
+ * is still around or has not been recycled.
+ */
+void swap_free(swp_entry_t entry)
+{
+	struct swap_info_struct *p;
+
+	p = swap_info_get(entry);
+	if (p) {
+		swap_entry_free(p, entry, 1);
+		spin_unlock(&p->lock);
+	}
+}
+
+/*
+ * Called after dropping swapcache to decrease refcnt to swap entries.
+ */
+void swapcache_free(swp_entry_t entry)
+{
+	struct swap_info_struct *p;
+
+	p = swap_info_get(entry);
+	if (p) {
+		swap_entry_free(p, entry, SWAP_HAS_CACHE);
+		spin_unlock(&p->lock);
+	}
+}
+
+/*
+ * How many references to page are currently swapped out?
+ * This does not give an exact answer when swap count is continued,
+ * but does include the high COUNT_CONTINUED flag to allow for that.
+ */
+int page_swapcount(struct page *page)
+{
+	int count = 0;
+	struct swap_info_struct *p;
+	swp_entry_t entry;
+
+	entry.val = page_private(page);
+	p = swap_info_get(entry);
+	if (p) {
+		count = swap_count(p->swap_map[swp_offset(entry)]);
+		spin_unlock(&p->lock);
+	}
+	return count;
+}
+
+/*
+ * How many references to @entry are currently swapped out?
+ * This considers COUNT_CONTINUED so it returns exact answer.
+ */
+int swp_swapcount(swp_entry_t entry)
+{
+	int count, tmp_count, n;
+	struct swap_info_struct *p;
+	struct page *page;
+	pgoff_t offset;
+	unsigned char *map;
+
+	p = swap_info_get(entry);
+	if (!p)
+		return 0;
+
+	count = swap_count(p->swap_map[swp_offset(entry)]);
+	if (!(count & COUNT_CONTINUED))
+		goto out;
+
+	count &= ~COUNT_CONTINUED;
+	n = SWAP_MAP_MAX + 1;
+
+	offset = swp_offset(entry);
+	page = vmalloc_to_page(p->swap_map + offset);
+	offset &= ~PAGE_MASK;
+	VM_BUG_ON(page_private(page) != SWP_CONTINUED);
+
+	do {
+		page = list_entry(page->lru.next, struct page, lru);
+		map = kmap_atomic(page);
+		tmp_count = map[offset];
+		kunmap_atomic(map);
+
+		count += (tmp_count & ~COUNT_CONTINUED) * n;
+		n *= (SWAP_CONT_MAX + 1);
+	} while (tmp_count & COUNT_CONTINUED);
+out:
+	spin_unlock(&p->lock);
+	return count;
+}
+
+/*
+ * We can write to an anon page without COW if there are no other references
+ * to it.  And as a side-effect, free up its swap: because the old content
+ * on disk will never be read, and seeking back there to write new content
+ * later would only waste time away from clustering.
+ */
+int reuse_swap_page(struct page *page)
+{
+	int count;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	if (unlikely(PageKsm(page)))
+		return 0;
+	count = page_mapcount(page);
+	if (count <= 1 && PageSwapCache(page)) {
+		count += page_swapcount(page);
+		if (count == 1 && !PageWriteback(page)) {
+			delete_from_swap_cache(page);
+			SetPageDirty(page);
+		}
+	}
+	return count <= 1;
+}
+
+/*
+ * If swap is getting full, or if there are no more mappings of this page,
+ * then try_to_free_swap is called to free its swap space.
+ */
+int try_to_free_swap(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+	if (!PageSwapCache(page))
+		return 0;
+	if (PageWriteback(page))
+		return 0;
+	if (page_swapcount(page))
+		return 0;
+
+	/*
+	 * Once hibernation has begun to create its image of memory,
+	 * there's a danger that one of the calls to try_to_free_swap()
+	 * - most probably a call from __try_to_reclaim_swap() while
+	 * hibernation is allocating its own swap pages for the image,
+	 * but conceivably even a call from memory reclaim - will free
+	 * the swap from a page which has already been recorded in the
+	 * image as a clean swapcache page, and then reuse its swap for
+	 * another page of the image.  On waking from hibernation, the
+	 * original page might be freed under memory pressure, then
+	 * later read back in from swap, now with the wrong data.
+	 *
+	 * Hibernation suspends storage while it is writing the image
+	 * to disk so check that here.
+	 */
+	if (pm_suspended_storage())
+		return 0;
+
+	delete_from_swap_cache(page);
+	SetPageDirty(page);
+	return 1;
+}
+
+/*
+ * Free the swap entry like above, but also try to
+ * free the page cache entry if it is the last user.
+ */
+int free_swap_and_cache(swp_entry_t entry)
+{
+	struct swap_info_struct *p;
+	struct page *page = NULL;
+
+	if (non_swap_entry(entry))
+		return 1;
+
+	p = swap_info_get(entry);
+	if (p) {
+		if (swap_entry_free(p, entry, 1) == SWAP_HAS_CACHE) {
+			page = find_get_page(swap_address_space(entry),
+						entry.val);
+			if (page && !trylock_page(page)) {
+				page_cache_release(page);
+				page = NULL;
+			}
+		}
+		spin_unlock(&p->lock);
+	}
+	if (page) {
+		/*
+		 * Not mapped elsewhere, or swap space full? Free it!
+		 * Also recheck PageSwapCache now page is locked (above).
+		 */
+		if (PageSwapCache(page) && !PageWriteback(page) &&
+				(!page_mapped(page) || vm_swap_full())) {
+			delete_from_swap_cache(page);
+			SetPageDirty(page);
+		}
+		unlock_page(page);
+		page_cache_release(page);
+	}
+	return p != NULL;
+}
+
+#ifdef CONFIG_HIBERNATION
+/*
+ * Find the swap type that corresponds to given device (if any).
+ *
+ * @offset - number of the PAGE_SIZE-sized block of the device, starting
+ * from 0, in which the swap header is expected to be located.
+ *
+ * This is needed for the suspend to disk (aka swsusp).
+ */
+int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
+{
+	struct block_device *bdev = NULL;
+	int type;
+
+	if (device)
+		bdev = bdget(device);
+
+	spin_lock(&swap_lock);
+	for (type = 0; type < nr_swapfiles; type++) {
+		struct swap_info_struct *sis = swap_info[type];
+
+		if (!(sis->flags & SWP_WRITEOK))
+			continue;
+
+		if (!bdev) {
+			if (bdev_p)
+				*bdev_p = bdgrab(sis->bdev);
+
+			spin_unlock(&swap_lock);
+			return type;
+		}
+		if (bdev == sis->bdev) {
+			struct swap_extent *se = &sis->first_swap_extent;
+
+			if (se->start_block == offset) {
+				if (bdev_p)
+					*bdev_p = bdgrab(sis->bdev);
+
+				spin_unlock(&swap_lock);
+				bdput(bdev);
+				return type;
+			}
+		}
+	}
+	spin_unlock(&swap_lock);
+	if (bdev)
+		bdput(bdev);
+
+	return -ENODEV;
+}
+
+/*
+ * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
+ * corresponding to given index in swap_info (swap type).
+ */
+sector_t swapdev_block(int type, pgoff_t offset)
+{
+	struct block_device *bdev;
+
+	if ((unsigned int)type >= nr_swapfiles)
+		return 0;
+	if (!(swap_info[type]->flags & SWP_WRITEOK))
+		return 0;
+	return map_swap_entry(swp_entry(type, offset), &bdev);
+}
+
+/*
+ * Return either the total number of swap pages of given type, or the number
+ * of free pages of that type (depending on @free)
+ *
+ * This is needed for software suspend
+ */
+unsigned int count_swap_pages(int type, int free)
+{
+	unsigned int n = 0;
+
+	spin_lock(&swap_lock);
+	if ((unsigned int)type < nr_swapfiles) {
+		struct swap_info_struct *sis = swap_info[type];
+
+		spin_lock(&sis->lock);
+		if (sis->flags & SWP_WRITEOK) {
+			n = sis->pages;
+			if (free)
+				n -= sis->inuse_pages;
+		}
+		spin_unlock(&sis->lock);
+	}
+	spin_unlock(&swap_lock);
+	return n;
+}
+#endif /* CONFIG_HIBERNATION */
+
+static inline int maybe_same_pte(pte_t pte, pte_t swp_pte)
+{
+#ifdef CONFIG_MEM_SOFT_DIRTY
+	/*
+	 * When pte keeps soft dirty bit the pte generated
+	 * from swap entry does not has it, still it's same
+	 * pte from logical point of view.
+	 */
+	pte_t swp_pte_dirty = pte_swp_mksoft_dirty(swp_pte);
+	return pte_same(pte, swp_pte) || pte_same(pte, swp_pte_dirty);
+#else
+	return pte_same(pte, swp_pte);
+#endif
+}
+
+/*
+ * No need to decide whether this PTE shares the swap entry with others,
+ * just let do_wp_page work it out if a write is requested later - to
+ * force COW, vm_page_prot omits write permission from any private vma.
+ */
+static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
+		unsigned long addr, swp_entry_t entry, struct page *page)
+{
+	struct page *swapcache;
+	struct mem_cgroup *memcg;
+	spinlock_t *ptl;
+	pte_t *pte;
+	int ret = 1;
+
+	swapcache = page;
+	page = ksm_might_need_to_copy(page, vma, addr);
+	if (unlikely(!page))
+		return -ENOMEM;
+
+	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg)) {
+		ret = -ENOMEM;
+		goto out_nolock;
+	}
+
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	if (unlikely(!maybe_same_pte(*pte, swp_entry_to_pte(entry)))) {
+		mem_cgroup_cancel_charge(page, memcg);
+		ret = 0;
+		goto out;
+	}
+
+	dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
+	inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
+	get_page(page);
+	set_pte_at(vma->vm_mm, addr, pte,
+		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
+	if (page == swapcache) {
+		page_add_anon_rmap(page, vma, addr);
+		mem_cgroup_commit_charge(page, memcg, true);
+	} else { /* ksm created a completely new copy */
+		page_add_new_anon_rmap(page, vma, addr);
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_active_or_unevictable(page, vma);
+	}
+	swap_free(entry);
+	/*
+	 * Move the page to the active list so it is not
+	 * immediately swapped out again after swapon.
+	 */
+	activate_page(page);
+out:
+	pte_unmap_unlock(pte, ptl);
+out_nolock:
+	if (page != swapcache) {
+		unlock_page(page);
+		put_page(page);
+	}
+	return ret;
+}
+
+static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+				unsigned long addr, unsigned long end,
+				swp_entry_t entry, struct page *page)
+{
+	pte_t swp_pte = swp_entry_to_pte(entry);
+	pte_t *pte;
+	int ret = 0;
+
+	/*
+	 * We don't actually need pte lock while scanning for swp_pte: since
+	 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
+	 * page table while we're scanning; though it could get zapped, and on
+	 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
+	 * of unmatched parts which look like swp_pte, so unuse_pte must
+	 * recheck under pte lock.  Scanning without pte lock lets it be
+	 * preemptable whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
+	 */
+	pte = pte_offset_map(pmd, addr);
+	do {
+		/*
+		 * swapoff spends a _lot_ of time in this loop!
+		 * Test inline before going to call unuse_pte.
+		 */
+		if (unlikely(maybe_same_pte(*pte, swp_pte))) {
+			pte_unmap(pte);
+			ret = unuse_pte(vma, pmd, addr, entry, page);
+			if (ret)
+				goto out;
+			pte = pte_offset_map(pmd, addr);
+		}
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	pte_unmap(pte - 1);
+out:
+	return ret;
+}
+
+static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
+				unsigned long addr, unsigned long end,
+				swp_entry_t entry, struct page *page)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	int ret;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+			continue;
+		ret = unuse_pte_range(vma, pmd, addr, next, entry, page);
+		if (ret)
+			return ret;
+	} while (pmd++, addr = next, addr != end);
+	return 0;
+}
+
+static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
+				unsigned long addr, unsigned long end,
+				swp_entry_t entry, struct page *page)
+{
+	pud_t *pud;
+	unsigned long next;
+	int ret;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		ret = unuse_pmd_range(vma, pud, addr, next, entry, page);
+		if (ret)
+			return ret;
+	} while (pud++, addr = next, addr != end);
+	return 0;
+}
+
+static int unuse_vma(struct vm_area_struct *vma,
+				swp_entry_t entry, struct page *page)
+{
+	pgd_t *pgd;
+	unsigned long addr, end, next;
+	int ret;
+
+	if (page_anon_vma(page)) {
+		addr = page_address_in_vma(page, vma);
+		if (addr == -EFAULT)
+			return 0;
+		else
+			end = addr + PAGE_SIZE;
+	} else {
+		addr = vma->vm_start;
+		end = vma->vm_end;
+	}
+
+	pgd = pgd_offset(vma->vm_mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		ret = unuse_pud_range(vma, pgd, addr, next, entry, page);
+		if (ret)
+			return ret;
+	} while (pgd++, addr = next, addr != end);
+	return 0;
+}
+
+static int unuse_mm(struct mm_struct *mm,
+				swp_entry_t entry, struct page *page)
+{
+	struct vm_area_struct *vma;
+	int ret = 0;
+
+	if (!down_read_trylock(&mm->mmap_sem)) {
+		/*
+		 * Activate page so shrink_inactive_list is unlikely to unmap
+		 * its ptes while lock is dropped, so swapoff can make progress.
+		 */
+		activate_page(page);
+		unlock_page(page);
+		down_read(&mm->mmap_sem);
+		lock_page(page);
+	}
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
+			break;
+	}
+	up_read(&mm->mmap_sem);
+	return (ret < 0)? ret: 0;
+}
+
+/*
+ * Scan swap_map (or frontswap_map if frontswap parameter is true)
+ * from current position to next entry still in use.
+ * Recycle to start on reaching the end, returning 0 when empty.
+ */
+static unsigned int find_next_to_unuse(struct swap_info_struct *si,
+					unsigned int prev, bool frontswap)
+{
+	unsigned int max = si->max;
+	unsigned int i = prev;
+	unsigned char count;
+
+	/*
+	 * No need for swap_lock here: we're just looking
+	 * for whether an entry is in use, not modifying it; false
+	 * hits are okay, and sys_swapoff() has already prevented new
+	 * allocations from this area (while holding swap_lock).
+	 */
+	for (;;) {
+		if (++i >= max) {
+			if (!prev) {
+				i = 0;
+				break;
+			}
+			/*
+			 * No entries in use at top of swap_map,
+			 * loop back to start and recheck there.
+			 */
+			max = prev + 1;
+			prev = 0;
+			i = 1;
+		}
+		if (frontswap) {
+			if (frontswap_test(si, i))
+				break;
+			else
+				continue;
+		}
+		count = READ_ONCE(si->swap_map[i]);
+		if (count && swap_count(count) != SWAP_MAP_BAD)
+			break;
+	}
+	return i;
+}
+
+/*
+ * We completely avoid races by reading each swap page in advance,
+ * and then search for the process using it.  All the necessary
+ * page table adjustments can then be made atomically.
+ *
+ * if the boolean frontswap is true, only unuse pages_to_unuse pages;
+ * pages_to_unuse==0 means all pages; ignored if frontswap is false
+ */
+int try_to_unuse(unsigned int type, bool frontswap,
+		 unsigned long pages_to_unuse)
+{
+	struct swap_info_struct *si = swap_info[type];
+	struct mm_struct *start_mm;
+	volatile unsigned char *swap_map; /* swap_map is accessed without
+					   * locking. Mark it as volatile
+					   * to prevent compiler doing
+					   * something odd.
+					   */
+	unsigned char swcount;
+	struct page *page;
+	swp_entry_t entry;
+	unsigned int i = 0;
+	int retval = 0;
+
+	/*
+	 * When searching mms for an entry, a good strategy is to
+	 * start at the first mm we freed the previous entry from
+	 * (though actually we don't notice whether we or coincidence
+	 * freed the entry).  Initialize this start_mm with a hold.
+	 *
+	 * A simpler strategy would be to start at the last mm we
+	 * freed the previous entry from; but that would take less
+	 * advantage of mmlist ordering, which clusters forked mms
+	 * together, child after parent.  If we race with dup_mmap(), we
+	 * prefer to resolve parent before child, lest we miss entries
+	 * duplicated after we scanned child: using last mm would invert
+	 * that.
+	 */
+	start_mm = &init_mm;
+	atomic_inc(&init_mm.mm_users);
+
+	/*
+	 * Keep on scanning until all entries have gone.  Usually,
+	 * one pass through swap_map is enough, but not necessarily:
+	 * there are races when an instance of an entry might be missed.
+	 */
+	while ((i = find_next_to_unuse(si, i, frontswap)) != 0) {
+		if (signal_pending(current)) {
+			retval = -EINTR;
+			break;
+		}
+
+		/*
+		 * Get a page for the entry, using the existing swap
+		 * cache page if there is one.  Otherwise, get a clean
+		 * page and read the swap into it.
+		 */
+		swap_map = &si->swap_map[i];
+		entry = swp_entry(type, i);
+		page = read_swap_cache_async(entry,
+					GFP_HIGHUSER_MOVABLE, NULL, 0);
+		if (!page) {
+			/*
+			 * Either swap_duplicate() failed because entry
+			 * has been freed independently, and will not be
+			 * reused since sys_swapoff() already disabled
+			 * allocation from here, or alloc_page() failed.
+			 */
+			swcount = *swap_map;
+			/*
+			 * We don't hold lock here, so the swap entry could be
+			 * SWAP_MAP_BAD (when the cluster is discarding).
+			 * Instead of fail out, We can just skip the swap
+			 * entry because swapoff will wait for discarding
+			 * finish anyway.
+			 */
+			if (!swcount || swcount == SWAP_MAP_BAD)
+				continue;
+			retval = -ENOMEM;
+			break;
+		}
+
+		/*
+		 * Don't hold on to start_mm if it looks like exiting.
+		 */
+		if (atomic_read(&start_mm->mm_users) == 1) {
+			mmput(start_mm);
+			start_mm = &init_mm;
+			atomic_inc(&init_mm.mm_users);
+		}
+
+		/*
+		 * Wait for and lock page.  When do_swap_page races with
+		 * try_to_unuse, do_swap_page can handle the fault much
+		 * faster than try_to_unuse can locate the entry.  This
+		 * apparently redundant "wait_on_page_locked" lets try_to_unuse
+		 * defer to do_swap_page in such a case - in some tests,
+		 * do_swap_page and try_to_unuse repeatedly compete.
+		 */
+		wait_on_page_locked(page);
+		wait_on_page_writeback(page);
+		lock_page(page);
+		wait_on_page_writeback(page);
+
+		/*
+		 * Remove all references to entry.
+		 */
+		swcount = *swap_map;
+		if (swap_count(swcount) == SWAP_MAP_SHMEM) {
+			retval = shmem_unuse(entry, page);
+			/* page has already been unlocked and released */
+			if (retval < 0)
+				break;
+			continue;
+		}
+		if (swap_count(swcount) && start_mm != &init_mm)
+			retval = unuse_mm(start_mm, entry, page);
+
+		if (swap_count(*swap_map)) {
+			int set_start_mm = (*swap_map >= swcount);
+			struct list_head *p = &start_mm->mmlist;
+			struct mm_struct *new_start_mm = start_mm;
+			struct mm_struct *prev_mm = start_mm;
+			struct mm_struct *mm;
+
+			atomic_inc(&new_start_mm->mm_users);
+			atomic_inc(&prev_mm->mm_users);
+			spin_lock(&mmlist_lock);
+			while (swap_count(*swap_map) && !retval &&
+					(p = p->next) != &start_mm->mmlist) {
+				mm = list_entry(p, struct mm_struct, mmlist);
+				if (!atomic_inc_not_zero(&mm->mm_users))
+					continue;
+				spin_unlock(&mmlist_lock);
+				mmput(prev_mm);
+				prev_mm = mm;
+
+				cond_resched();
+
+				swcount = *swap_map;
+				if (!swap_count(swcount)) /* any usage ? */
+					;
+				else if (mm == &init_mm)
+					set_start_mm = 1;
+				else
+					retval = unuse_mm(mm, entry, page);
+
+				if (set_start_mm && *swap_map < swcount) {
+					mmput(new_start_mm);
+					atomic_inc(&mm->mm_users);
+					new_start_mm = mm;
+					set_start_mm = 0;
+				}
+				spin_lock(&mmlist_lock);
+			}
+			spin_unlock(&mmlist_lock);
+			mmput(prev_mm);
+			mmput(start_mm);
+			start_mm = new_start_mm;
+		}
+		if (retval) {
+			unlock_page(page);
+			page_cache_release(page);
+			break;
+		}
+
+		/*
+		 * If a reference remains (rare), we would like to leave
+		 * the page in the swap cache; but try_to_unmap could
+		 * then re-duplicate the entry once we drop page lock,
+		 * so we might loop indefinitely; also, that page could
+		 * not be swapped out to other storage meanwhile.  So:
+		 * delete from cache even if there's another reference,
+		 * after ensuring that the data has been saved to disk -
+		 * since if the reference remains (rarer), it will be
+		 * read from disk into another page.  Splitting into two
+		 * pages would be incorrect if swap supported "shared
+		 * private" pages, but they are handled by tmpfs files.
+		 *
+		 * Given how unuse_vma() targets one particular offset
+		 * in an anon_vma, once the anon_vma has been determined,
+		 * this splitting happens to be just what is needed to
+		 * handle where KSM pages have been swapped out: re-reading
+		 * is unnecessarily slow, but we can fix that later on.
+		 */
+		if (swap_count(*swap_map) &&
+		     PageDirty(page) && PageSwapCache(page)) {
+			struct writeback_control wbc = {
+				.sync_mode = WB_SYNC_NONE,
+			};
+
+			swap_writepage(page, &wbc);
+			lock_page(page);
+			wait_on_page_writeback(page);
+		}
+
+		/*
+		 * It is conceivable that a racing task removed this page from
+		 * swap cache just before we acquired the page lock at the top,
+		 * or while we dropped it in unuse_mm().  The page might even
+		 * be back in swap cache on another swap area: that we must not
+		 * delete, since it may not have been written out to swap yet.
+		 */
+		if (PageSwapCache(page) &&
+		    likely(page_private(page) == entry.val))
+			delete_from_swap_cache(page);
+
+		/*
+		 * So we could skip searching mms once swap count went
+		 * to 1, we did not mark any present ptes as dirty: must
+		 * mark page dirty so shrink_page_list will preserve it.
+		 */
+		SetPageDirty(page);
+		unlock_page(page);
+		page_cache_release(page);
+
+		/*
+		 * Make sure that we aren't completely killing
+		 * interactive performance.
+		 */
+		cond_resched();
+		if (frontswap && pages_to_unuse > 0) {
+			if (!--pages_to_unuse)
+				break;
+		}
+	}
+
+	mmput(start_mm);
+	return retval;
+}
+
+/*
+ * After a successful try_to_unuse, if no swap is now in use, we know
+ * we can empty the mmlist.  swap_lock must be held on entry and exit.
+ * Note that mmlist_lock nests inside swap_lock, and an mm must be
+ * added to the mmlist just after page_duplicate - before would be racy.
+ */
+static void drain_mmlist(void)
+{
+	struct list_head *p, *next;
+	unsigned int type;
+
+	for (type = 0; type < nr_swapfiles; type++)
+		if (swap_info[type]->inuse_pages)
+			return;
+	spin_lock(&mmlist_lock);
+	list_for_each_safe(p, next, &init_mm.mmlist)
+		list_del_init(p);
+	spin_unlock(&mmlist_lock);
+}
+
+/*
+ * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
+ * corresponds to page offset for the specified swap entry.
+ * Note that the type of this function is sector_t, but it returns page offset
+ * into the bdev, not sector offset.
+ */
+static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev)
+{
+	struct swap_info_struct *sis;
+	struct swap_extent *start_se;
+	struct swap_extent *se;
+	pgoff_t offset;
+
+	sis = swap_info[swp_type(entry)];
+	*bdev = sis->bdev;
+
+	offset = swp_offset(entry);
+	start_se = sis->curr_swap_extent;
+	se = start_se;
+
+	for ( ; ; ) {
+		struct list_head *lh;
+
+		if (se->start_page <= offset &&
+				offset < (se->start_page + se->nr_pages)) {
+			return se->start_block + (offset - se->start_page);
+		}
+		lh = se->list.next;
+		se = list_entry(lh, struct swap_extent, list);
+		sis->curr_swap_extent = se;
+		BUG_ON(se == start_se);		/* It *must* be present */
+	}
+}
+
+/*
+ * Returns the page offset into bdev for the specified page's swap entry.
+ */
+sector_t map_swap_page(struct page *page, struct block_device **bdev)
+{
+	swp_entry_t entry;
+	entry.val = page_private(page);
+	return map_swap_entry(entry, bdev);
+}
+
+/*
+ * Free all of a swapdev's extent information
+ */
+static void destroy_swap_extents(struct swap_info_struct *sis)
+{
+	while (!list_empty(&sis->first_swap_extent.list)) {
+		struct swap_extent *se;
+
+		se = list_entry(sis->first_swap_extent.list.next,
+				struct swap_extent, list);
+		list_del(&se->list);
+		kfree(se);
+	}
+
+	if (sis->flags & SWP_FILE) {
+		struct file *swap_file = sis->swap_file;
+		struct address_space *mapping = swap_file->f_mapping;
+
+		sis->flags &= ~SWP_FILE;
+		mapping->a_ops->swap_deactivate(swap_file);
+	}
+}
+
+/*
+ * Add a block range (and the corresponding page range) into this swapdev's
+ * extent list.  The extent list is kept sorted in page order.
+ *
+ * This function rather assumes that it is called in ascending page order.
+ */
+int
+add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
+		unsigned long nr_pages, sector_t start_block)
+{
+	struct swap_extent *se;
+	struct swap_extent *new_se;
+	struct list_head *lh;
+
+	if (start_page == 0) {
+		se = &sis->first_swap_extent;
+		sis->curr_swap_extent = se;
+		se->start_page = 0;
+		se->nr_pages = nr_pages;
+		se->start_block = start_block;
+		return 1;
+	} else {
+		lh = sis->first_swap_extent.list.prev;	/* Highest extent */
+		se = list_entry(lh, struct swap_extent, list);
+		BUG_ON(se->start_page + se->nr_pages != start_page);
+		if (se->start_block + se->nr_pages == start_block) {
+			/* Merge it */
+			se->nr_pages += nr_pages;
+			return 0;
+		}
+	}
+
+	/*
+	 * No merge.  Insert a new extent, preserving ordering.
+	 */
+	new_se = kmalloc(sizeof(*se), GFP_KERNEL);
+	if (new_se == NULL)
+		return -ENOMEM;
+	new_se->start_page = start_page;
+	new_se->nr_pages = nr_pages;
+	new_se->start_block = start_block;
+
+	list_add_tail(&new_se->list, &sis->first_swap_extent.list);
+	return 1;
+}
+
+/*
+ * A `swap extent' is a simple thing which maps a contiguous range of pages
+ * onto a contiguous range of disk blocks.  An ordered list of swap extents
+ * is built at swapon time and is then used at swap_writepage/swap_readpage
+ * time for locating where on disk a page belongs.
+ *
+ * If the swapfile is an S_ISBLK block device, a single extent is installed.
+ * This is done so that the main operating code can treat S_ISBLK and S_ISREG
+ * swap files identically.
+ *
+ * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
+ * extent list operates in PAGE_SIZE disk blocks.  Both S_ISREG and S_ISBLK
+ * swapfiles are handled *identically* after swapon time.
+ *
+ * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
+ * and will parse them into an ordered extent list, in PAGE_SIZE chunks.  If
+ * some stray blocks are found which do not fall within the PAGE_SIZE alignment
+ * requirements, they are simply tossed out - we will never use those blocks
+ * for swapping.
+ *
+ * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon.  This
+ * prevents root from shooting her foot off by ftruncating an in-use swapfile,
+ * which will scribble on the fs.
+ *
+ * The amount of disk space which a single swap extent represents varies.
+ * Typically it is in the 1-4 megabyte range.  So we can have hundreds of
+ * extents in the list.  To avoid much list walking, we cache the previous
+ * search location in `curr_swap_extent', and start new searches from there.
+ * This is extremely effective.  The average number of iterations in
+ * map_swap_page() has been measured at about 0.3 per page.  - akpm.
+ */
+static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
+{
+	struct file *swap_file = sis->swap_file;
+	struct address_space *mapping = swap_file->f_mapping;
+	struct inode *inode = mapping->host;
+	int ret;
+
+	if (S_ISBLK(inode->i_mode)) {
+		ret = add_swap_extent(sis, 0, sis->max, 0);
+		*span = sis->pages;
+		return ret;
+	}
+
+	if (mapping->a_ops->swap_activate) {
+		ret = mapping->a_ops->swap_activate(sis, swap_file, span);
+		if (!ret) {
+			sis->flags |= SWP_FILE;
+			ret = add_swap_extent(sis, 0, sis->max, 0);
+			*span = sis->pages;
+		}
+		return ret;
+	}
+
+	return generic_swapfile_activate(sis, swap_file, span);
+}
+
+static void _enable_swap_info(struct swap_info_struct *p, int prio,
+				unsigned char *swap_map,
+				struct swap_cluster_info *cluster_info)
+{
+	if (prio >= 0)
+		p->prio = prio;
+	else
+		p->prio = --least_priority;
+	/*
+	 * the plist prio is negated because plist ordering is
+	 * low-to-high, while swap ordering is high-to-low
+	 */
+	p->list.prio = -p->prio;
+	p->avail_list.prio = -p->prio;
+	p->swap_map = swap_map;
+	p->cluster_info = cluster_info;
+	p->flags |= SWP_WRITEOK;
+	atomic_long_add(p->pages, &nr_swap_pages);
+	total_swap_pages += p->pages;
+
+	assert_spin_locked(&swap_lock);
+	/*
+	 * both lists are plists, and thus priority ordered.
+	 * swap_active_head needs to be priority ordered for swapoff(),
+	 * which on removal of any swap_info_struct with an auto-assigned
+	 * (i.e. negative) priority increments the auto-assigned priority
+	 * of any lower-priority swap_info_structs.
+	 * swap_avail_head needs to be priority ordered for get_swap_page(),
+	 * which allocates swap pages from the highest available priority
+	 * swap_info_struct.
+	 */
+	plist_add(&p->list, &swap_active_head);
+	spin_lock(&swap_avail_lock);
+	plist_add(&p->avail_list, &swap_avail_head);
+	spin_unlock(&swap_avail_lock);
+}
+
+static void enable_swap_info(struct swap_info_struct *p, int prio,
+				unsigned char *swap_map,
+				struct swap_cluster_info *cluster_info,
+				unsigned long *frontswap_map)
+{
+	frontswap_init(p->type, frontswap_map);
+	spin_lock(&swap_lock);
+	spin_lock(&p->lock);
+	 _enable_swap_info(p, prio, swap_map, cluster_info);
+	spin_unlock(&p->lock);
+	spin_unlock(&swap_lock);
+}
+
+static void reinsert_swap_info(struct swap_info_struct *p)
+{
+	spin_lock(&swap_lock);
+	spin_lock(&p->lock);
+	_enable_swap_info(p, p->prio, p->swap_map, p->cluster_info);
+	spin_unlock(&p->lock);
+	spin_unlock(&swap_lock);
+}
+
+SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
+{
+	struct swap_info_struct *p = NULL;
+	unsigned char *swap_map;
+	struct swap_cluster_info *cluster_info;
+	unsigned long *frontswap_map;
+	struct file *swap_file, *victim;
+	struct address_space *mapping;
+	struct inode *inode;
+	struct filename *pathname;
+	int err, found = 0;
+	unsigned int old_block_size;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	BUG_ON(!current->mm);
+
+	pathname = getname(specialfile);
+	if (IS_ERR(pathname))
+		return PTR_ERR(pathname);
+
+	victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0);
+	err = PTR_ERR(victim);
+	if (IS_ERR(victim))
+		goto out;
+
+	mapping = victim->f_mapping;
+	spin_lock(&swap_lock);
+	plist_for_each_entry(p, &swap_active_head, list) {
+		if (p->flags & SWP_WRITEOK) {
+			if (p->swap_file->f_mapping == mapping) {
+				found = 1;
+				break;
+			}
+		}
+	}
+	if (!found) {
+		err = -EINVAL;
+		spin_unlock(&swap_lock);
+		goto out_dput;
+	}
+	if (!security_vm_enough_memory_mm(current->mm, p->pages))
+		vm_unacct_memory(p->pages);
+	else {
+		err = -ENOMEM;
+		spin_unlock(&swap_lock);
+		goto out_dput;
+	}
+	spin_lock(&swap_avail_lock);
+	plist_del(&p->avail_list, &swap_avail_head);
+	spin_unlock(&swap_avail_lock);
+	spin_lock(&p->lock);
+	if (p->prio < 0) {
+		struct swap_info_struct *si = p;
+
+		plist_for_each_entry_continue(si, &swap_active_head, list) {
+			si->prio++;
+			si->list.prio--;
+			si->avail_list.prio--;
+		}
+		least_priority++;
+	}
+	plist_del(&p->list, &swap_active_head);
+	atomic_long_sub(p->pages, &nr_swap_pages);
+	total_swap_pages -= p->pages;
+	p->flags &= ~SWP_WRITEOK;
+	spin_unlock(&p->lock);
+	spin_unlock(&swap_lock);
+
+	set_current_oom_origin();
+	err = try_to_unuse(p->type, false, 0); /* force unuse all pages */
+	clear_current_oom_origin();
+
+	if (err) {
+		/* re-insert swap space back into swap_list */
+		reinsert_swap_info(p);
+		goto out_dput;
+	}
+
+	flush_work(&p->discard_work);
+
+	destroy_swap_extents(p);
+	if (p->flags & SWP_CONTINUED)
+		free_swap_count_continuations(p);
+
+	mutex_lock(&swapon_mutex);
+	spin_lock(&swap_lock);
+	spin_lock(&p->lock);
+	drain_mmlist();
+
+	/* wait for anyone still in scan_swap_map */
+	p->highest_bit = 0;		/* cuts scans short */
+	while (p->flags >= SWP_SCANNING) {
+		spin_unlock(&p->lock);
+		spin_unlock(&swap_lock);
+		schedule_timeout_uninterruptible(1);
+		spin_lock(&swap_lock);
+		spin_lock(&p->lock);
+	}
+
+	swap_file = p->swap_file;
+	old_block_size = p->old_block_size;
+	p->swap_file = NULL;
+	p->max = 0;
+	swap_map = p->swap_map;
+	p->swap_map = NULL;
+	cluster_info = p->cluster_info;
+	p->cluster_info = NULL;
+	frontswap_map = frontswap_map_get(p);
+	spin_unlock(&p->lock);
+	spin_unlock(&swap_lock);
+	frontswap_invalidate_area(p->type);
+	frontswap_map_set(p, NULL);
+	mutex_unlock(&swapon_mutex);
+	free_percpu(p->percpu_cluster);
+	p->percpu_cluster = NULL;
+	vfree(swap_map);
+	vfree(cluster_info);
+	vfree(frontswap_map);
+	/* Destroy swap account information */
+	swap_cgroup_swapoff(p->type);
+
+	inode = mapping->host;
+	if (S_ISBLK(inode->i_mode)) {
+		struct block_device *bdev = I_BDEV(inode);
+		set_blocksize(bdev, old_block_size);
+		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+	} else {
+		mutex_lock(&inode->i_mutex);
+		inode->i_flags &= ~S_SWAPFILE;
+		mutex_unlock(&inode->i_mutex);
+	}
+	filp_close(swap_file, NULL);
+
+	/*
+	 * Clear the SWP_USED flag after all resources are freed so that swapon
+	 * can reuse this swap_info in alloc_swap_info() safely.  It is ok to
+	 * not hold p->lock after we cleared its SWP_WRITEOK.
+	 */
+	spin_lock(&swap_lock);
+	p->flags = 0;
+	spin_unlock(&swap_lock);
+
+	err = 0;
+	atomic_inc(&proc_poll_event);
+	wake_up_interruptible(&proc_poll_wait);
+
+out_dput:
+	filp_close(victim, NULL);
+out:
+	putname(pathname);
+	return err;
+}
+
+#ifdef CONFIG_PROC_FS
+static unsigned swaps_poll(struct file *file, poll_table *wait)
+{
+	struct seq_file *seq = file->private_data;
+
+	poll_wait(file, &proc_poll_wait, wait);
+
+	if (seq->poll_event != atomic_read(&proc_poll_event)) {
+		seq->poll_event = atomic_read(&proc_poll_event);
+		return POLLIN | POLLRDNORM | POLLERR | POLLPRI;
+	}
+
+	return POLLIN | POLLRDNORM;
+}
+
+/* iterator */
+static void *swap_start(struct seq_file *swap, loff_t *pos)
+{
+	struct swap_info_struct *si;
+	int type;
+	loff_t l = *pos;
+
+	mutex_lock(&swapon_mutex);
+
+	if (!l)
+		return SEQ_START_TOKEN;
+
+	for (type = 0; type < nr_swapfiles; type++) {
+		smp_rmb();	/* read nr_swapfiles before swap_info[type] */
+		si = swap_info[type];
+		if (!(si->flags & SWP_USED) || !si->swap_map)
+			continue;
+		if (!--l)
+			return si;
+	}
+
+	return NULL;
+}
+
+static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
+{
+	struct swap_info_struct *si = v;
+	int type;
+
+	if (v == SEQ_START_TOKEN)
+		type = 0;
+	else
+		type = si->type + 1;
+
+	for (; type < nr_swapfiles; type++) {
+		smp_rmb();	/* read nr_swapfiles before swap_info[type] */
+		si = swap_info[type];
+		if (!(si->flags & SWP_USED) || !si->swap_map)
+			continue;
+		++*pos;
+		return si;
+	}
+
+	return NULL;
+}
+
+static void swap_stop(struct seq_file *swap, void *v)
+{
+	mutex_unlock(&swapon_mutex);
+}
+
+static int swap_show(struct seq_file *swap, void *v)
+{
+	struct swap_info_struct *si = v;
+	struct file *file;
+	int len;
+
+	if (si == SEQ_START_TOKEN) {
+		seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
+		return 0;
+	}
+
+	file = si->swap_file;
+	len = seq_file_path(swap, file, " \t\n\\");
+	seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
+			len < 40 ? 40 - len : 1, " ",
+			S_ISBLK(file_inode(file)->i_mode) ?
+				"partition" : "file\t",
+			si->pages << (PAGE_SHIFT - 10),
+			si->inuse_pages << (PAGE_SHIFT - 10),
+			si->prio);
+	return 0;
+}
+
+static const struct seq_operations swaps_op = {
+	.start =	swap_start,
+	.next =		swap_next,
+	.stop =		swap_stop,
+	.show =		swap_show
+};
+
+static int swaps_open(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq;
+	int ret;
+
+	ret = seq_open(file, &swaps_op);
+	if (ret)
+		return ret;
+
+	seq = file->private_data;
+	seq->poll_event = atomic_read(&proc_poll_event);
+	return 0;
+}
+
+static const struct file_operations proc_swaps_operations = {
+	.open		= swaps_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+	.poll		= swaps_poll,
+};
+
+static int __init procswaps_init(void)
+{
+	proc_create("swaps", 0, NULL, &proc_swaps_operations);
+	return 0;
+}
+__initcall(procswaps_init);
+#endif /* CONFIG_PROC_FS */
+
+#ifdef MAX_SWAPFILES_CHECK
+static int __init max_swapfiles_check(void)
+{
+	MAX_SWAPFILES_CHECK();
+	return 0;
+}
+late_initcall(max_swapfiles_check);
+#endif
+
+static struct swap_info_struct *alloc_swap_info(void)
+{
+	struct swap_info_struct *p;
+	unsigned int type;
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	spin_lock(&swap_lock);
+	for (type = 0; type < nr_swapfiles; type++) {
+		if (!(swap_info[type]->flags & SWP_USED))
+			break;
+	}
+	if (type >= MAX_SWAPFILES) {
+		spin_unlock(&swap_lock);
+		kfree(p);
+		return ERR_PTR(-EPERM);
+	}
+	if (type >= nr_swapfiles) {
+		p->type = type;
+		swap_info[type] = p;
+		/*
+		 * Write swap_info[type] before nr_swapfiles, in case a
+		 * racing procfs swap_start() or swap_next() is reading them.
+		 * (We never shrink nr_swapfiles, we never free this entry.)
+		 */
+		smp_wmb();
+		nr_swapfiles++;
+	} else {
+		kfree(p);
+		p = swap_info[type];
+		/*
+		 * Do not memset this entry: a racing procfs swap_next()
+		 * would be relying on p->type to remain valid.
+		 */
+	}
+	INIT_LIST_HEAD(&p->first_swap_extent.list);
+	plist_node_init(&p->list, 0);
+	plist_node_init(&p->avail_list, 0);
+	p->flags = SWP_USED;
+	spin_unlock(&swap_lock);
+	spin_lock_init(&p->lock);
+
+	return p;
+}
+
+static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
+{
+	int error;
+
+	if (S_ISBLK(inode->i_mode)) {
+		p->bdev = bdgrab(I_BDEV(inode));
+		error = blkdev_get(p->bdev,
+				   FMODE_READ | FMODE_WRITE | FMODE_EXCL, p);
+		if (error < 0) {
+			p->bdev = NULL;
+			return error;
+		}
+		p->old_block_size = block_size(p->bdev);
+		error = set_blocksize(p->bdev, PAGE_SIZE);
+		if (error < 0)
+			return error;
+		p->flags |= SWP_BLKDEV;
+	} else if (S_ISREG(inode->i_mode)) {
+		p->bdev = inode->i_sb->s_bdev;
+		mutex_lock(&inode->i_mutex);
+		if (IS_SWAPFILE(inode))
+			return -EBUSY;
+	} else
+		return -EINVAL;
+
+	return 0;
+}
+
+static unsigned long read_swap_header(struct swap_info_struct *p,
+					union swap_header *swap_header,
+					struct inode *inode)
+{
+	int i;
+	unsigned long maxpages;
+	unsigned long swapfilepages;
+	unsigned long last_page;
+
+	if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
+		pr_err("Unable to find swap-space signature\n");
+		return 0;
+	}
+
+	/* swap partition endianess hack... */
+	if (swab32(swap_header->info.version) == 1) {
+		swab32s(&swap_header->info.version);
+		swab32s(&swap_header->info.last_page);
+		swab32s(&swap_header->info.nr_badpages);
+		if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
+			return 0;
+		for (i = 0; i < swap_header->info.nr_badpages; i++)
+			swab32s(&swap_header->info.badpages[i]);
+	}
+	/* Check the swap header's sub-version */
+	if (swap_header->info.version != 1) {
+		pr_warn("Unable to handle swap header version %d\n",
+			swap_header->info.version);
+		return 0;
+	}
+
+	p->lowest_bit  = 1;
+	p->cluster_next = 1;
+	p->cluster_nr = 0;
+
+	/*
+	 * Find out how many pages are allowed for a single swap
+	 * device. There are two limiting factors: 1) the number
+	 * of bits for the swap offset in the swp_entry_t type, and
+	 * 2) the number of bits in the swap pte as defined by the
+	 * different architectures. In order to find the
+	 * largest possible bit mask, a swap entry with swap type 0
+	 * and swap offset ~0UL is created, encoded to a swap pte,
+	 * decoded to a swp_entry_t again, and finally the swap
+	 * offset is extracted. This will mask all the bits from
+	 * the initial ~0UL mask that can't be encoded in either
+	 * the swp_entry_t or the architecture definition of a
+	 * swap pte.
+	 */
+	maxpages = swp_offset(pte_to_swp_entry(
+			swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+	last_page = swap_header->info.last_page;
+	if (last_page > maxpages) {
+		pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
+			maxpages << (PAGE_SHIFT - 10),
+			last_page << (PAGE_SHIFT - 10));
+	}
+	if (maxpages > last_page) {
+		maxpages = last_page + 1;
+		/* p->max is an unsigned int: don't overflow it */
+		if ((unsigned int)maxpages == 0)
+			maxpages = UINT_MAX;
+	}
+	p->highest_bit = maxpages - 1;
+
+	if (!maxpages)
+		return 0;
+	swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
+	if (swapfilepages && maxpages > swapfilepages) {
+		pr_warn("Swap area shorter than signature indicates\n");
+		return 0;
+	}
+	if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
+		return 0;
+	if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
+		return 0;
+
+	return maxpages;
+}
+
+static int setup_swap_map_and_extents(struct swap_info_struct *p,
+					union swap_header *swap_header,
+					unsigned char *swap_map,
+					struct swap_cluster_info *cluster_info,
+					unsigned long maxpages,
+					sector_t *span)
+{
+	int i;
+	unsigned int nr_good_pages;
+	int nr_extents;
+	unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
+	unsigned long idx = p->cluster_next / SWAPFILE_CLUSTER;
+
+	nr_good_pages = maxpages - 1;	/* omit header page */
+
+	cluster_set_null(&p->free_cluster_head);
+	cluster_set_null(&p->free_cluster_tail);
+	cluster_set_null(&p->discard_cluster_head);
+	cluster_set_null(&p->discard_cluster_tail);
+
+	for (i = 0; i < swap_header->info.nr_badpages; i++) {
+		unsigned int page_nr = swap_header->info.badpages[i];
+		if (page_nr == 0 || page_nr > swap_header->info.last_page)
+			return -EINVAL;
+		if (page_nr < maxpages) {
+			swap_map[page_nr] = SWAP_MAP_BAD;
+			nr_good_pages--;
+			/*
+			 * Haven't marked the cluster free yet, no list
+			 * operation involved
+			 */
+			inc_cluster_info_page(p, cluster_info, page_nr);
+		}
+	}
+
+	/* Haven't marked the cluster free yet, no list operation involved */
+	for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++)
+		inc_cluster_info_page(p, cluster_info, i);
+
+	if (nr_good_pages) {
+		swap_map[0] = SWAP_MAP_BAD;
+		/*
+		 * Not mark the cluster free yet, no list
+		 * operation involved
+		 */
+		inc_cluster_info_page(p, cluster_info, 0);
+		p->max = maxpages;
+		p->pages = nr_good_pages;
+		nr_extents = setup_swap_extents(p, span);
+		if (nr_extents < 0)
+			return nr_extents;
+		nr_good_pages = p->pages;
+	}
+	if (!nr_good_pages) {
+		pr_warn("Empty swap-file\n");
+		return -EINVAL;
+	}
+
+	if (!cluster_info)
+		return nr_extents;
+
+	for (i = 0; i < nr_clusters; i++) {
+		if (!cluster_count(&cluster_info[idx])) {
+			cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE);
+			if (cluster_is_null(&p->free_cluster_head)) {
+				cluster_set_next_flag(&p->free_cluster_head,
+								idx, 0);
+				cluster_set_next_flag(&p->free_cluster_tail,
+								idx, 0);
+			} else {
+				unsigned int tail;
+
+				tail = cluster_next(&p->free_cluster_tail);
+				cluster_set_next(&cluster_info[tail], idx);
+				cluster_set_next_flag(&p->free_cluster_tail,
+								idx, 0);
+			}
+		}
+		idx++;
+		if (idx == nr_clusters)
+			idx = 0;
+	}
+	return nr_extents;
+}
+
+/*
+ * Helper to sys_swapon determining if a given swap
+ * backing device queue supports DISCARD operations.
+ */
+static bool swap_discardable(struct swap_info_struct *si)
+{
+	struct request_queue *q = bdev_get_queue(si->bdev);
+
+	if (!q || !blk_queue_discard(q))
+		return false;
+
+	return true;
+}
+
+SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
+{
+	struct swap_info_struct *p;
+	struct filename *name;
+	struct file *swap_file = NULL;
+	struct address_space *mapping;
+	int prio;
+	int error;
+	union swap_header *swap_header;
+	int nr_extents;
+	sector_t span;
+	unsigned long maxpages;
+	unsigned char *swap_map = NULL;
+	struct swap_cluster_info *cluster_info = NULL;
+	unsigned long *frontswap_map = NULL;
+	struct page *page = NULL;
+	struct inode *inode = NULL;
+
+	if (swap_flags & ~SWAP_FLAGS_VALID)
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	p = alloc_swap_info();
+	if (IS_ERR(p))
+		return PTR_ERR(p);
+
+	INIT_WORK(&p->discard_work, swap_discard_work);
+
+	name = getname(specialfile);
+	if (IS_ERR(name)) {
+		error = PTR_ERR(name);
+		name = NULL;
+		goto bad_swap;
+	}
+	swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0);
+	if (IS_ERR(swap_file)) {
+		error = PTR_ERR(swap_file);
+		swap_file = NULL;
+		goto bad_swap;
+	}
+
+	p->swap_file = swap_file;
+	mapping = swap_file->f_mapping;
+	inode = mapping->host;
+
+	/* If S_ISREG(inode->i_mode) will do mutex_lock(&inode->i_mutex); */
+	error = claim_swapfile(p, inode);
+	if (unlikely(error))
+		goto bad_swap;
+
+	/*
+	 * Read the swap header.
+	 */
+	if (!mapping->a_ops->readpage) {
+		error = -EINVAL;
+		goto bad_swap;
+	}
+	page = read_mapping_page(mapping, 0, swap_file);
+	if (IS_ERR(page)) {
+		error = PTR_ERR(page);
+		goto bad_swap;
+	}
+	swap_header = kmap(page);
+
+	maxpages = read_swap_header(p, swap_header, inode);
+	if (unlikely(!maxpages)) {
+		error = -EINVAL;
+		goto bad_swap;
+	}
+
+	/* OK, set up the swap map and apply the bad block list */
+	swap_map = vzalloc(maxpages);
+	if (!swap_map) {
+		error = -ENOMEM;
+		goto bad_swap;
+	}
+	if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
+		int cpu;
+
+		p->flags |= SWP_SOLIDSTATE;
+		/*
+		 * select a random position to start with to help wear leveling
+		 * SSD
+		 */
+		p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
+
+		cluster_info = vzalloc(DIV_ROUND_UP(maxpages,
+			SWAPFILE_CLUSTER) * sizeof(*cluster_info));
+		if (!cluster_info) {
+			error = -ENOMEM;
+			goto bad_swap;
+		}
+		p->percpu_cluster = alloc_percpu(struct percpu_cluster);
+		if (!p->percpu_cluster) {
+			error = -ENOMEM;
+			goto bad_swap;
+		}
+		for_each_possible_cpu(cpu) {
+			struct percpu_cluster *cluster;
+			cluster = per_cpu_ptr(p->percpu_cluster, cpu);
+			cluster_set_null(&cluster->index);
+		}
+	}
+
+	error = swap_cgroup_swapon(p->type, maxpages);
+	if (error)
+		goto bad_swap;
+
+	nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
+		cluster_info, maxpages, &span);
+	if (unlikely(nr_extents < 0)) {
+		error = nr_extents;
+		goto bad_swap;
+	}
+	/* frontswap enabled? set up bit-per-page map for frontswap */
+	if (frontswap_enabled)
+		frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long));
+
+	if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) {
+		/*
+		 * When discard is enabled for swap with no particular
+		 * policy flagged, we set all swap discard flags here in
+		 * order to sustain backward compatibility with older
+		 * swapon(8) releases.
+		 */
+		p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD |
+			     SWP_PAGE_DISCARD);
+
+		/*
+		 * By flagging sys_swapon, a sysadmin can tell us to
+		 * either do single-time area discards only, or to just
+		 * perform discards for released swap page-clusters.
+		 * Now it's time to adjust the p->flags accordingly.
+		 */
+		if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
+			p->flags &= ~SWP_PAGE_DISCARD;
+		else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
+			p->flags &= ~SWP_AREA_DISCARD;
+
+		/* issue a swapon-time discard if it's still required */
+		if (p->flags & SWP_AREA_DISCARD) {
+			int err = discard_swap(p);
+			if (unlikely(err))
+				pr_err("swapon: discard_swap(%p): %d\n",
+					p, err);
+		}
+	}
+
+	mutex_lock(&swapon_mutex);
+	prio = -1;
+	if (swap_flags & SWAP_FLAG_PREFER)
+		prio =
+		  (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
+	enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
+
+	pr_info("Adding %uk swap on %s.  "
+			"Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
+		p->pages<<(PAGE_SHIFT-10), name->name, p->prio,
+		nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
+		(p->flags & SWP_SOLIDSTATE) ? "SS" : "",
+		(p->flags & SWP_DISCARDABLE) ? "D" : "",
+		(p->flags & SWP_AREA_DISCARD) ? "s" : "",
+		(p->flags & SWP_PAGE_DISCARD) ? "c" : "",
+		(frontswap_map) ? "FS" : "");
+
+	mutex_unlock(&swapon_mutex);
+	atomic_inc(&proc_poll_event);
+	wake_up_interruptible(&proc_poll_wait);
+
+	if (S_ISREG(inode->i_mode))
+		inode->i_flags |= S_SWAPFILE;
+	error = 0;
+	goto out;
+bad_swap:
+	free_percpu(p->percpu_cluster);
+	p->percpu_cluster = NULL;
+	if (inode && S_ISBLK(inode->i_mode) && p->bdev) {
+		set_blocksize(p->bdev, p->old_block_size);
+		blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+	}
+	destroy_swap_extents(p);
+	swap_cgroup_swapoff(p->type);
+	spin_lock(&swap_lock);
+	p->swap_file = NULL;
+	p->flags = 0;
+	spin_unlock(&swap_lock);
+	vfree(swap_map);
+	vfree(cluster_info);
+	if (swap_file) {
+		if (inode && S_ISREG(inode->i_mode)) {
+			mutex_unlock(&inode->i_mutex);
+			inode = NULL;
+		}
+		filp_close(swap_file, NULL);
+	}
+out:
+	if (page && !IS_ERR(page)) {
+		kunmap(page);
+		page_cache_release(page);
+	}
+	if (name)
+		putname(name);
+	if (inode && S_ISREG(inode->i_mode))
+		mutex_unlock(&inode->i_mutex);
+	return error;
+}
+
+void si_swapinfo(struct sysinfo *val)
+{
+	unsigned int type;
+	unsigned long nr_to_be_unused = 0;
+
+	spin_lock(&swap_lock);
+	for (type = 0; type < nr_swapfiles; type++) {
+		struct swap_info_struct *si = swap_info[type];
+
+		if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK))
+			nr_to_be_unused += si->inuse_pages;
+	}
+	val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused;
+	val->totalswap = total_swap_pages + nr_to_be_unused;
+	spin_unlock(&swap_lock);
+}
+
+/*
+ * Verify that a swap entry is valid and increment its swap map count.
+ *
+ * Returns error code in following case.
+ * - success -> 0
+ * - swp_entry is invalid -> EINVAL
+ * - swp_entry is migration entry -> EINVAL
+ * - swap-cache reference is requested but there is already one. -> EEXIST
+ * - swap-cache reference is requested but the entry is not used. -> ENOENT
+ * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
+ */
+static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
+{
+	struct swap_info_struct *p;
+	unsigned long offset, type;
+	unsigned char count;
+	unsigned char has_cache;
+	int err = -EINVAL;
+
+	if (non_swap_entry(entry))
+		goto out;
+
+	type = swp_type(entry);
+	if (type >= nr_swapfiles)
+		goto bad_file;
+	p = swap_info[type];
+	offset = swp_offset(entry);
+
+	spin_lock(&p->lock);
+	if (unlikely(offset >= p->max))
+		goto unlock_out;
+
+	count = p->swap_map[offset];
+
+	/*
+	 * swapin_readahead() doesn't check if a swap entry is valid, so the
+	 * swap entry could be SWAP_MAP_BAD. Check here with lock held.
+	 */
+	if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
+		err = -ENOENT;
+		goto unlock_out;
+	}
+
+	has_cache = count & SWAP_HAS_CACHE;
+	count &= ~SWAP_HAS_CACHE;
+	err = 0;
+
+	if (usage == SWAP_HAS_CACHE) {
+
+		/* set SWAP_HAS_CACHE if there is no cache and entry is used */
+		if (!has_cache && count)
+			has_cache = SWAP_HAS_CACHE;
+		else if (has_cache)		/* someone else added cache */
+			err = -EEXIST;
+		else				/* no users remaining */
+			err = -ENOENT;
+
+	} else if (count || has_cache) {
+
+		if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX)
+			count += usage;
+		else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX)
+			err = -EINVAL;
+		else if (swap_count_continued(p, offset, count))
+			count = COUNT_CONTINUED;
+		else
+			err = -ENOMEM;
+	} else
+		err = -ENOENT;			/* unused swap entry */
+
+	p->swap_map[offset] = count | has_cache;
+
+unlock_out:
+	spin_unlock(&p->lock);
+out:
+	return err;
+
+bad_file:
+	pr_err("swap_dup: %s%08lx\n", Bad_file, entry.val);
+	goto out;
+}
+
+/*
+ * Help swapoff by noting that swap entry belongs to shmem/tmpfs
+ * (in which case its reference count is never incremented).
+ */
+void swap_shmem_alloc(swp_entry_t entry)
+{
+	__swap_duplicate(entry, SWAP_MAP_SHMEM);
+}
+
+/*
+ * Increase reference count of swap entry by 1.
+ * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
+ * but could not be atomically allocated.  Returns 0, just as if it succeeded,
+ * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
+ * might occur if a page table entry has got corrupted.
+ */
+int swap_duplicate(swp_entry_t entry)
+{
+	int err = 0;
+
+	while (!err && __swap_duplicate(entry, 1) == -ENOMEM)
+		err = add_swap_count_continuation(entry, GFP_ATOMIC);
+	return err;
+}
+
+/*
+ * @entry: swap entry for which we allocate swap cache.
+ *
+ * Called when allocating swap cache for existing swap entry,
+ * This can return error codes. Returns 0 at success.
+ * -EBUSY means there is a swap cache.
+ * Note: return code is different from swap_duplicate().
+ */
+int swapcache_prepare(swp_entry_t entry)
+{
+	return __swap_duplicate(entry, SWAP_HAS_CACHE);
+}
+
+struct swap_info_struct *page_swap_info(struct page *page)
+{
+	swp_entry_t swap = { .val = page_private(page) };
+	BUG_ON(!PageSwapCache(page));
+	return swap_info[swp_type(swap)];
+}
+
+/*
+ * out-of-line __page_file_ methods to avoid include hell.
+ */
+struct address_space *__page_file_mapping(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
+	return page_swap_info(page)->swap_file->f_mapping;
+}
+EXPORT_SYMBOL_GPL(__page_file_mapping);
+
+pgoff_t __page_file_index(struct page *page)
+{
+	swp_entry_t swap = { .val = page_private(page) };
+	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
+	return swp_offset(swap);
+}
+EXPORT_SYMBOL_GPL(__page_file_index);
+
+/*
+ * add_swap_count_continuation - called when a swap count is duplicated
+ * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
+ * page of the original vmalloc'ed swap_map, to hold the continuation count
+ * (for that entry and for its neighbouring PAGE_SIZE swap entries).  Called
+ * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
+ *
+ * These continuation pages are seldom referenced: the common paths all work
+ * on the original swap_map, only referring to a continuation page when the
+ * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
+ *
+ * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
+ * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
+ * can be called after dropping locks.
+ */
+int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
+{
+	struct swap_info_struct *si;
+	struct page *head;
+	struct page *page;
+	struct page *list_page;
+	pgoff_t offset;
+	unsigned char count;
+
+	/*
+	 * When debugging, it's easier to use __GFP_ZERO here; but it's better
+	 * for latency not to zero a page while GFP_ATOMIC and holding locks.
+	 */
+	page = alloc_page(gfp_mask | __GFP_HIGHMEM);
+
+	si = swap_info_get(entry);
+	if (!si) {
+		/*
+		 * An acceptable race has occurred since the failing
+		 * __swap_duplicate(): the swap entry has been freed,
+		 * perhaps even the whole swap_map cleared for swapoff.
+		 */
+		goto outer;
+	}
+
+	offset = swp_offset(entry);
+	count = si->swap_map[offset] & ~SWAP_HAS_CACHE;
+
+	if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) {
+		/*
+		 * The higher the swap count, the more likely it is that tasks
+		 * will race to add swap count continuation: we need to avoid
+		 * over-provisioning.
+		 */
+		goto out;
+	}
+
+	if (!page) {
+		spin_unlock(&si->lock);
+		return -ENOMEM;
+	}
+
+	/*
+	 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
+	 * no architecture is using highmem pages for kernel page tables: so it
+	 * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
+	 */
+	head = vmalloc_to_page(si->swap_map + offset);
+	offset &= ~PAGE_MASK;
+
+	/*
+	 * Page allocation does not initialize the page's lru field,
+	 * but it does always reset its private field.
+	 */
+	if (!page_private(head)) {
+		BUG_ON(count & COUNT_CONTINUED);
+		INIT_LIST_HEAD(&head->lru);
+		set_page_private(head, SWP_CONTINUED);
+		si->flags |= SWP_CONTINUED;
+	}
+
+	list_for_each_entry(list_page, &head->lru, lru) {
+		unsigned char *map;
+
+		/*
+		 * If the previous map said no continuation, but we've found
+		 * a continuation page, free our allocation and use this one.
+		 */
+		if (!(count & COUNT_CONTINUED))
+			goto out;
+
+		map = kmap_atomic(list_page) + offset;
+		count = *map;
+		kunmap_atomic(map);
+
+		/*
+		 * If this continuation count now has some space in it,
+		 * free our allocation and use this one.
+		 */
+		if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX)
+			goto out;
+	}
+
+	list_add_tail(&page->lru, &head->lru);
+	page = NULL;			/* now it's attached, don't free it */
+out:
+	spin_unlock(&si->lock);
+outer:
+	if (page)
+		__free_page(page);
+	return 0;
+}
+
+/*
+ * swap_count_continued - when the original swap_map count is incremented
+ * from SWAP_MAP_MAX, check if there is already a continuation page to carry
+ * into, carry if so, or else fail until a new continuation page is allocated;
+ * when the original swap_map count is decremented from 0 with continuation,
+ * borrow from the continuation and report whether it still holds more.
+ * Called while __swap_duplicate() or swap_entry_free() holds swap_lock.
+ */
+static bool swap_count_continued(struct swap_info_struct *si,
+				 pgoff_t offset, unsigned char count)
+{
+	struct page *head;
+	struct page *page;
+	unsigned char *map;
+
+	head = vmalloc_to_page(si->swap_map + offset);
+	if (page_private(head) != SWP_CONTINUED) {
+		BUG_ON(count & COUNT_CONTINUED);
+		return false;		/* need to add count continuation */
+	}
+
+	offset &= ~PAGE_MASK;
+	page = list_entry(head->lru.next, struct page, lru);
+	map = kmap_atomic(page) + offset;
+
+	if (count == SWAP_MAP_MAX)	/* initial increment from swap_map */
+		goto init_map;		/* jump over SWAP_CONT_MAX checks */
+
+	if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */
+		/*
+		 * Think of how you add 1 to 999
+		 */
+		while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) {
+			kunmap_atomic(map);
+			page = list_entry(page->lru.next, struct page, lru);
+			BUG_ON(page == head);
+			map = kmap_atomic(page) + offset;
+		}
+		if (*map == SWAP_CONT_MAX) {
+			kunmap_atomic(map);
+			page = list_entry(page->lru.next, struct page, lru);
+			if (page == head)
+				return false;	/* add count continuation */
+			map = kmap_atomic(page) + offset;
+init_map:		*map = 0;		/* we didn't zero the page */
+		}
+		*map += 1;
+		kunmap_atomic(map);
+		page = list_entry(page->lru.prev, struct page, lru);
+		while (page != head) {
+			map = kmap_atomic(page) + offset;
+			*map = COUNT_CONTINUED;
+			kunmap_atomic(map);
+			page = list_entry(page->lru.prev, struct page, lru);
+		}
+		return true;			/* incremented */
+
+	} else {				/* decrementing */
+		/*
+		 * Think of how you subtract 1 from 1000
+		 */
+		BUG_ON(count != COUNT_CONTINUED);
+		while (*map == COUNT_CONTINUED) {
+			kunmap_atomic(map);
+			page = list_entry(page->lru.next, struct page, lru);
+			BUG_ON(page == head);
+			map = kmap_atomic(page) + offset;
+		}
+		BUG_ON(*map == 0);
+		*map -= 1;
+		if (*map == 0)
+			count = 0;
+		kunmap_atomic(map);
+		page = list_entry(page->lru.prev, struct page, lru);
+		while (page != head) {
+			map = kmap_atomic(page) + offset;
+			*map = SWAP_CONT_MAX | count;
+			count = COUNT_CONTINUED;
+			kunmap_atomic(map);
+			page = list_entry(page->lru.prev, struct page, lru);
+		}
+		return count == COUNT_CONTINUED;
+	}
+}
+
+/*
+ * free_swap_count_continuations - swapoff free all the continuation pages
+ * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
+ */
+static void free_swap_count_continuations(struct swap_info_struct *si)
+{
+	pgoff_t offset;
+
+	for (offset = 0; offset < si->max; offset += PAGE_SIZE) {
+		struct page *head;
+		head = vmalloc_to_page(si->swap_map + offset);
+		if (page_private(head)) {
+			struct list_head *this, *next;
+			list_for_each_safe(this, next, &head->lru) {
+				struct page *page;
+				page = list_entry(this, struct page, lru);
+				list_del(this);
+				__free_page(page);
+			}
+		}
+	}
+}
diff --git a/mm/truncate.c b/mm/truncate.c
new file mode 100644
index 0000000..f4c8270
--- /dev/null
+++ b/mm/truncate.c
@@ -0,0 +1,801 @@
+/*
+ * mm/truncate.c - code for taking down pages from address_spaces
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 10Sep2002	Andrew Morton
+ *		Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/backing-dev.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/export.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/pagevec.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/buffer_head.h>	/* grr. try_to_release_page,
+				   do_invalidatepage */
+#include <linux/cleancache.h>
+#include <linux/rmap.h>
+#include "internal.h"
+
+static void clear_exceptional_entry(struct address_space *mapping,
+				    pgoff_t index, void *entry)
+{
+	struct radix_tree_node *node;
+	void **slot;
+
+	/* Handled by shmem itself */
+	if (shmem_mapping(mapping))
+		return;
+
+	spin_lock_irq(&mapping->tree_lock);
+	/*
+	 * Regular page slots are stabilized by the page lock even
+	 * without the tree itself locked.  These unlocked entries
+	 * need verification under the tree lock.
+	 */
+	if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
+		goto unlock;
+	if (*slot != entry)
+		goto unlock;
+	radix_tree_replace_slot(slot, NULL);
+	mapping->nrshadows--;
+	if (!node)
+		goto unlock;
+	workingset_node_shadows_dec(node);
+	/*
+	 * Don't track node without shadow entries.
+	 *
+	 * Avoid acquiring the list_lru lock if already untracked.
+	 * The list_empty() test is safe as node->private_list is
+	 * protected by mapping->tree_lock.
+	 */
+	if (!workingset_node_shadows(node) &&
+	    !list_empty(&node->private_list))
+		list_lru_del(&workingset_shadow_nodes, &node->private_list);
+	__radix_tree_delete_node(&mapping->page_tree, node);
+unlock:
+	spin_unlock_irq(&mapping->tree_lock);
+}
+
+/**
+ * do_invalidatepage - invalidate part or all of a page
+ * @page: the page which is affected
+ * @offset: start of the range to invalidate
+ * @length: length of the range to invalidate
+ *
+ * do_invalidatepage() is called when all or part of the page has become
+ * invalidated by a truncate operation.
+ *
+ * do_invalidatepage() does not have to release all buffers, but it must
+ * ensure that no dirty buffer is left outside @offset and that no I/O
+ * is underway against any of the blocks which are outside the truncation
+ * point.  Because the caller is about to free (and possibly reuse) those
+ * blocks on-disk.
+ */
+void do_invalidatepage(struct page *page, unsigned int offset,
+		       unsigned int length)
+{
+	void (*invalidatepage)(struct page *, unsigned int, unsigned int);
+
+	invalidatepage = page->mapping->a_ops->invalidatepage;
+#ifdef CONFIG_BLOCK
+	if (!invalidatepage)
+		invalidatepage = block_invalidatepage;
+#endif
+	if (invalidatepage)
+		(*invalidatepage)(page, offset, length);
+}
+
+/*
+ * If truncate cannot remove the fs-private metadata from the page, the page
+ * becomes orphaned.  It will be left on the LRU and may even be mapped into
+ * user pagetables if we're racing with filemap_fault().
+ *
+ * We need to bale out if page->mapping is no longer equal to the original
+ * mapping.  This happens a) when the VM reclaimed the page while we waited on
+ * its lock, b) when a concurrent invalidate_mapping_pages got there first and
+ * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
+ */
+static int
+truncate_complete_page(struct address_space *mapping, struct page *page)
+{
+	if (page->mapping != mapping)
+		return -EIO;
+
+	if (page_has_private(page))
+		do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
+
+	/*
+	 * Some filesystems seem to re-dirty the page even after
+	 * the VM has canceled the dirty bit (eg ext3 journaling).
+	 * Hence dirty accounting check is placed after invalidation.
+	 */
+	cancel_dirty_page(page);
+	ClearPageMappedToDisk(page);
+	delete_from_page_cache(page);
+	return 0;
+}
+
+/*
+ * This is for invalidate_mapping_pages().  That function can be called at
+ * any time, and is not supposed to throw away dirty pages.  But pages can
+ * be marked dirty at any time too, so use remove_mapping which safely
+ * discards clean, unused pages.
+ *
+ * Returns non-zero if the page was successfully invalidated.
+ */
+static int
+invalidate_complete_page(struct address_space *mapping, struct page *page)
+{
+	int ret;
+
+	if (page->mapping != mapping)
+		return 0;
+
+	if (page_has_private(page) && !try_to_release_page(page, 0))
+		return 0;
+
+	ret = remove_mapping(mapping, page);
+
+	return ret;
+}
+
+int truncate_inode_page(struct address_space *mapping, struct page *page)
+{
+	if (page_mapped(page)) {
+		unmap_mapping_range(mapping,
+				   (loff_t)page->index << PAGE_CACHE_SHIFT,
+				   PAGE_CACHE_SIZE, 0);
+	}
+	return truncate_complete_page(mapping, page);
+}
+
+/*
+ * Used to get rid of pages on hardware memory corruption.
+ */
+int generic_error_remove_page(struct address_space *mapping, struct page *page)
+{
+	if (!mapping)
+		return -EINVAL;
+	/*
+	 * Only punch for normal data pages for now.
+	 * Handling other types like directories would need more auditing.
+	 */
+	if (!S_ISREG(mapping->host->i_mode))
+		return -EIO;
+	return truncate_inode_page(mapping, page);
+}
+EXPORT_SYMBOL(generic_error_remove_page);
+
+/*
+ * Safely invalidate one page from its pagecache mapping.
+ * It only drops clean, unused pages. The page must be locked.
+ *
+ * Returns 1 if the page is successfully invalidated, otherwise 0.
+ */
+int invalidate_inode_page(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+	if (!mapping)
+		return 0;
+	if (PageDirty(page) || PageWriteback(page))
+		return 0;
+	if (page_mapped(page))
+		return 0;
+	return invalidate_complete_page(mapping, page);
+}
+
+/**
+ * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ * @lend: offset to which to truncate (inclusive)
+ *
+ * Truncate the page cache, removing the pages that are between
+ * specified offsets (and zeroing out partial pages
+ * if lstart or lend + 1 is not page aligned).
+ *
+ * Truncate takes two passes - the first pass is nonblocking.  It will not
+ * block on page locks and it will not block on writeback.  The second pass
+ * will wait.  This is to prevent as much IO as possible in the affected region.
+ * The first pass will remove most pages, so the search cost of the second pass
+ * is low.
+ *
+ * We pass down the cache-hot hint to the page freeing code.  Even if the
+ * mapping is large, it is probably the case that the final pages are the most
+ * recently touched, and freeing happens in ascending file offset order.
+ *
+ * Note that since ->invalidatepage() accepts range to invalidate
+ * truncate_inode_pages_range is able to handle cases where lend + 1 is not
+ * page aligned properly.
+ */
+void truncate_inode_pages_range(struct address_space *mapping,
+				loff_t lstart, loff_t lend)
+{
+	pgoff_t		start;		/* inclusive */
+	pgoff_t		end;		/* exclusive */
+	unsigned int	partial_start;	/* inclusive */
+	unsigned int	partial_end;	/* exclusive */
+	struct pagevec	pvec;
+	pgoff_t		indices[PAGEVEC_SIZE];
+	pgoff_t		index;
+	int		i;
+
+	cleancache_invalidate_inode(mapping);
+	if (mapping->nrpages == 0 && mapping->nrshadows == 0)
+		return;
+
+	/* Offsets within partial pages */
+	partial_start = lstart & (PAGE_CACHE_SIZE - 1);
+	partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
+
+	/*
+	 * 'start' and 'end' always covers the range of pages to be fully
+	 * truncated. Partial pages are covered with 'partial_start' at the
+	 * start of the range and 'partial_end' at the end of the range.
+	 * Note that 'end' is exclusive while 'lend' is inclusive.
+	 */
+	start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	if (lend == -1)
+		/*
+		 * lend == -1 indicates end-of-file so we have to set 'end'
+		 * to the highest possible pgoff_t and since the type is
+		 * unsigned we're using -1.
+		 */
+		end = -1;
+	else
+		end = (lend + 1) >> PAGE_CACHE_SHIFT;
+
+	pagevec_init(&pvec, 0);
+	index = start;
+	while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE),
+			indices)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+
+			/* We rely upon deletion not changing page->index */
+			index = indices[i];
+			if (index >= end)
+				break;
+
+			if (radix_tree_exceptional_entry(page)) {
+				clear_exceptional_entry(mapping, index, page);
+				continue;
+			}
+
+			if (!trylock_page(page))
+				continue;
+			WARN_ON(page->index != index);
+			if (PageWriteback(page)) {
+				unlock_page(page);
+				continue;
+			}
+			truncate_inode_page(mapping, page);
+			unlock_page(page);
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		cond_resched();
+		index++;
+	}
+
+	if (partial_start) {
+		struct page *page = find_lock_page(mapping, start - 1);
+		if (page) {
+			unsigned int top = PAGE_CACHE_SIZE;
+			if (start > end) {
+				/* Truncation within a single page */
+				top = partial_end;
+				partial_end = 0;
+			}
+			wait_on_page_writeback(page);
+			zero_user_segment(page, partial_start, top);
+			cleancache_invalidate_page(mapping, page);
+			if (page_has_private(page))
+				do_invalidatepage(page, partial_start,
+						  top - partial_start);
+			unlock_page(page);
+			page_cache_release(page);
+		}
+	}
+	if (partial_end) {
+		struct page *page = find_lock_page(mapping, end);
+		if (page) {
+			wait_on_page_writeback(page);
+			zero_user_segment(page, 0, partial_end);
+			cleancache_invalidate_page(mapping, page);
+			if (page_has_private(page))
+				do_invalidatepage(page, 0,
+						  partial_end);
+			unlock_page(page);
+			page_cache_release(page);
+		}
+	}
+	/*
+	 * If the truncation happened within a single page no pages
+	 * will be released, just zeroed, so we can bail out now.
+	 */
+	if (start >= end)
+		return;
+
+	index = start;
+	for ( ; ; ) {
+		cond_resched();
+		if (!pagevec_lookup_entries(&pvec, mapping, index,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) {
+			/* If all gone from start onwards, we're done */
+			if (index == start)
+				break;
+			/* Otherwise restart to make sure all gone */
+			index = start;
+			continue;
+		}
+		if (index == start && indices[0] >= end) {
+			/* All gone out of hole to be punched, we're done */
+			pagevec_remove_exceptionals(&pvec);
+			pagevec_release(&pvec);
+			break;
+		}
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+
+			/* We rely upon deletion not changing page->index */
+			index = indices[i];
+			if (index >= end) {
+				/* Restart punch to make sure all gone */
+				index = start - 1;
+				break;
+			}
+
+			if (radix_tree_exceptional_entry(page)) {
+				clear_exceptional_entry(mapping, index, page);
+				continue;
+			}
+
+			lock_page(page);
+			WARN_ON(page->index != index);
+			wait_on_page_writeback(page);
+			truncate_inode_page(mapping, page);
+			unlock_page(page);
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		index++;
+	}
+	cleancache_invalidate_inode(mapping);
+}
+EXPORT_SYMBOL(truncate_inode_pages_range);
+
+/**
+ * truncate_inode_pages - truncate *all* the pages from an offset
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ *
+ * Called under (and serialised by) inode->i_mutex.
+ *
+ * Note: When this function returns, there can be a page in the process of
+ * deletion (inside __delete_from_page_cache()) in the specified range.  Thus
+ * mapping->nrpages can be non-zero when this function returns even after
+ * truncation of the whole mapping.
+ */
+void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
+{
+	truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
+}
+EXPORT_SYMBOL(truncate_inode_pages);
+
+/**
+ * truncate_inode_pages_final - truncate *all* pages before inode dies
+ * @mapping: mapping to truncate
+ *
+ * Called under (and serialized by) inode->i_mutex.
+ *
+ * Filesystems have to use this in the .evict_inode path to inform the
+ * VM that this is the final truncate and the inode is going away.
+ */
+void truncate_inode_pages_final(struct address_space *mapping)
+{
+	unsigned long nrshadows;
+	unsigned long nrpages;
+
+	/*
+	 * Page reclaim can not participate in regular inode lifetime
+	 * management (can't call iput()) and thus can race with the
+	 * inode teardown.  Tell it when the address space is exiting,
+	 * so that it does not install eviction information after the
+	 * final truncate has begun.
+	 */
+	mapping_set_exiting(mapping);
+
+	/*
+	 * When reclaim installs eviction entries, it increases
+	 * nrshadows first, then decreases nrpages.  Make sure we see
+	 * this in the right order or we might miss an entry.
+	 */
+	nrpages = mapping->nrpages;
+	smp_rmb();
+	nrshadows = mapping->nrshadows;
+
+	if (nrpages || nrshadows) {
+		/*
+		 * As truncation uses a lockless tree lookup, cycle
+		 * the tree lock to make sure any ongoing tree
+		 * modification that does not see AS_EXITING is
+		 * completed before starting the final truncate.
+		 */
+		spin_lock_irq(&mapping->tree_lock);
+		spin_unlock_irq(&mapping->tree_lock);
+
+		truncate_inode_pages(mapping, 0);
+	}
+}
+EXPORT_SYMBOL(truncate_inode_pages_final);
+
+/**
+ * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
+ * @mapping: the address_space which holds the pages to invalidate
+ * @start: the offset 'from' which to invalidate
+ * @end: the offset 'to' which to invalidate (inclusive)
+ *
+ * This function only removes the unlocked pages, if you want to
+ * remove all the pages of one inode, you must call truncate_inode_pages.
+ *
+ * invalidate_mapping_pages() will not block on IO activity. It will not
+ * invalidate pages which are dirty, locked, under writeback or mapped into
+ * pagetables.
+ */
+unsigned long invalidate_mapping_pages(struct address_space *mapping,
+		pgoff_t start, pgoff_t end)
+{
+	pgoff_t indices[PAGEVEC_SIZE];
+	struct pagevec pvec;
+	pgoff_t index = start;
+	unsigned long ret;
+	unsigned long count = 0;
+	int i;
+
+	pagevec_init(&pvec, 0);
+	while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
+			indices)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+
+			/* We rely upon deletion not changing page->index */
+			index = indices[i];
+			if (index > end)
+				break;
+
+			if (radix_tree_exceptional_entry(page)) {
+				clear_exceptional_entry(mapping, index, page);
+				continue;
+			}
+
+			if (!trylock_page(page))
+				continue;
+			WARN_ON(page->index != index);
+			ret = invalidate_inode_page(page);
+			unlock_page(page);
+			/*
+			 * Invalidation is a hint that the page is no longer
+			 * of interest and try to speed up its reclaim.
+			 */
+			if (!ret)
+				deactivate_file_page(page);
+			count += ret;
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		cond_resched();
+		index++;
+	}
+	return count;
+}
+EXPORT_SYMBOL(invalidate_mapping_pages);
+
+/*
+ * This is like invalidate_complete_page(), except it ignores the page's
+ * refcount.  We do this because invalidate_inode_pages2() needs stronger
+ * invalidation guarantees, and cannot afford to leave pages behind because
+ * shrink_page_list() has a temp ref on them, or because they're transiently
+ * sitting in the lru_cache_add() pagevecs.
+ */
+static int
+invalidate_complete_page2(struct address_space *mapping, struct page *page)
+{
+	struct mem_cgroup *memcg;
+	unsigned long flags;
+
+	if (page->mapping != mapping)
+		return 0;
+
+	if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
+		return 0;
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	spin_lock_irqsave(&mapping->tree_lock, flags);
+	if (PageDirty(page))
+		goto failed;
+
+	BUG_ON(page_has_private(page));
+	__delete_from_page_cache(page, NULL, memcg);
+	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	mem_cgroup_end_page_stat(memcg);
+
+	if (mapping->a_ops->freepage)
+		mapping->a_ops->freepage(page);
+
+	page_cache_release(page);	/* pagecache ref */
+	return 1;
+failed:
+	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	mem_cgroup_end_page_stat(memcg);
+	return 0;
+}
+
+static int do_launder_page(struct address_space *mapping, struct page *page)
+{
+	if (!PageDirty(page))
+		return 0;
+	if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
+		return 0;
+	return mapping->a_ops->launder_page(page);
+}
+
+/**
+ * invalidate_inode_pages2_range - remove range of pages from an address_space
+ * @mapping: the address_space
+ * @start: the page offset 'from' which to invalidate
+ * @end: the page offset 'to' which to invalidate (inclusive)
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Returns -EBUSY if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2_range(struct address_space *mapping,
+				  pgoff_t start, pgoff_t end)
+{
+	pgoff_t indices[PAGEVEC_SIZE];
+	struct pagevec pvec;
+	pgoff_t index;
+	int i;
+	int ret = 0;
+	int ret2 = 0;
+	int did_range_unmap = 0;
+
+	cleancache_invalidate_inode(mapping);
+	pagevec_init(&pvec, 0);
+	index = start;
+	while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
+			indices)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+
+			/* We rely upon deletion not changing page->index */
+			index = indices[i];
+			if (index > end)
+				break;
+
+			if (radix_tree_exceptional_entry(page)) {
+				clear_exceptional_entry(mapping, index, page);
+				continue;
+			}
+
+			lock_page(page);
+			WARN_ON(page->index != index);
+			if (page->mapping != mapping) {
+				unlock_page(page);
+				continue;
+			}
+			wait_on_page_writeback(page);
+			if (page_mapped(page)) {
+				if (!did_range_unmap) {
+					/*
+					 * Zap the rest of the file in one hit.
+					 */
+					unmap_mapping_range(mapping,
+					   (loff_t)index << PAGE_CACHE_SHIFT,
+					   (loff_t)(1 + end - index)
+							 << PAGE_CACHE_SHIFT,
+					    0);
+					did_range_unmap = 1;
+				} else {
+					/*
+					 * Just zap this page
+					 */
+					unmap_mapping_range(mapping,
+					   (loff_t)index << PAGE_CACHE_SHIFT,
+					   PAGE_CACHE_SIZE, 0);
+				}
+			}
+			BUG_ON(page_mapped(page));
+			ret2 = do_launder_page(mapping, page);
+			if (ret2 == 0) {
+				if (!invalidate_complete_page2(mapping, page))
+					ret2 = -EBUSY;
+			}
+			if (ret2 < 0)
+				ret = ret2;
+			unlock_page(page);
+		}
+		pagevec_remove_exceptionals(&pvec);
+		pagevec_release(&pvec);
+		cond_resched();
+		index++;
+	}
+	cleancache_invalidate_inode(mapping);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
+
+/**
+ * invalidate_inode_pages2 - remove all pages from an address_space
+ * @mapping: the address_space
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Returns -EBUSY if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2(struct address_space *mapping)
+{
+	return invalidate_inode_pages2_range(mapping, 0, -1);
+}
+EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
+
+/**
+ * truncate_pagecache - unmap and remove pagecache that has been truncated
+ * @inode: inode
+ * @newsize: new file size
+ *
+ * inode's new i_size must already be written before truncate_pagecache
+ * is called.
+ *
+ * This function should typically be called before the filesystem
+ * releases resources associated with the freed range (eg. deallocates
+ * blocks). This way, pagecache will always stay logically coherent
+ * with on-disk format, and the filesystem would not have to deal with
+ * situations such as writepage being called for a page that has already
+ * had its underlying blocks deallocated.
+ */
+void truncate_pagecache(struct inode *inode, loff_t newsize)
+{
+	struct address_space *mapping = inode->i_mapping;
+	loff_t holebegin = round_up(newsize, PAGE_SIZE);
+
+	/*
+	 * unmap_mapping_range is called twice, first simply for
+	 * efficiency so that truncate_inode_pages does fewer
+	 * single-page unmaps.  However after this first call, and
+	 * before truncate_inode_pages finishes, it is possible for
+	 * private pages to be COWed, which remain after
+	 * truncate_inode_pages finishes, hence the second
+	 * unmap_mapping_range call must be made for correctness.
+	 */
+	unmap_mapping_range(mapping, holebegin, 0, 1);
+	truncate_inode_pages(mapping, newsize);
+	unmap_mapping_range(mapping, holebegin, 0, 1);
+}
+EXPORT_SYMBOL(truncate_pagecache);
+
+/**
+ * truncate_setsize - update inode and pagecache for a new file size
+ * @inode: inode
+ * @newsize: new file size
+ *
+ * truncate_setsize updates i_size and performs pagecache truncation (if
+ * necessary) to @newsize. It will be typically be called from the filesystem's
+ * setattr function when ATTR_SIZE is passed in.
+ *
+ * Must be called with a lock serializing truncates and writes (generally
+ * i_mutex but e.g. xfs uses a different lock) and before all filesystem
+ * specific block truncation has been performed.
+ */
+void truncate_setsize(struct inode *inode, loff_t newsize)
+{
+	loff_t oldsize = inode->i_size;
+
+	i_size_write(inode, newsize);
+	if (newsize > oldsize)
+		pagecache_isize_extended(inode, oldsize, newsize);
+	truncate_pagecache(inode, newsize);
+}
+EXPORT_SYMBOL(truncate_setsize);
+
+/**
+ * pagecache_isize_extended - update pagecache after extension of i_size
+ * @inode:	inode for which i_size was extended
+ * @from:	original inode size
+ * @to:		new inode size
+ *
+ * Handle extension of inode size either caused by extending truncate or by
+ * write starting after current i_size. We mark the page straddling current
+ * i_size RO so that page_mkwrite() is called on the nearest write access to
+ * the page.  This way filesystem can be sure that page_mkwrite() is called on
+ * the page before user writes to the page via mmap after the i_size has been
+ * changed.
+ *
+ * The function must be called after i_size is updated so that page fault
+ * coming after we unlock the page will already see the new i_size.
+ * The function must be called while we still hold i_mutex - this not only
+ * makes sure i_size is stable but also that userspace cannot observe new
+ * i_size value before we are prepared to store mmap writes at new inode size.
+ */
+void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
+{
+	int bsize = i_blocksize(inode);
+	loff_t rounded_from;
+	struct page *page;
+	pgoff_t index;
+
+	WARN_ON(to > inode->i_size);
+
+	if (from >= to || bsize == PAGE_CACHE_SIZE)
+		return;
+	/* Page straddling @from will not have any hole block created? */
+	rounded_from = round_up(from, bsize);
+	if (to <= rounded_from || !(rounded_from & (PAGE_CACHE_SIZE - 1)))
+		return;
+
+	index = from >> PAGE_CACHE_SHIFT;
+	page = find_lock_page(inode->i_mapping, index);
+	/* Page not cached? Nothing to do */
+	if (!page)
+		return;
+	/*
+	 * See clear_page_dirty_for_io() for details why set_page_dirty()
+	 * is needed.
+	 */
+	if (page_mkclean(page))
+		set_page_dirty(page);
+	unlock_page(page);
+	page_cache_release(page);
+}
+EXPORT_SYMBOL(pagecache_isize_extended);
+
+/**
+ * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
+ * @inode: inode
+ * @lstart: offset of beginning of hole
+ * @lend: offset of last byte of hole
+ *
+ * This function should typically be called before the filesystem
+ * releases resources associated with the freed range (eg. deallocates
+ * blocks). This way, pagecache will always stay logically coherent
+ * with on-disk format, and the filesystem would not have to deal with
+ * situations such as writepage being called for a page that has already
+ * had its underlying blocks deallocated.
+ */
+void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+	struct address_space *mapping = inode->i_mapping;
+	loff_t unmap_start = round_up(lstart, PAGE_SIZE);
+	loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
+	/*
+	 * This rounding is currently just for example: unmap_mapping_range
+	 * expands its hole outwards, whereas we want it to contract the hole
+	 * inwards.  However, existing callers of truncate_pagecache_range are
+	 * doing their own page rounding first.  Note that unmap_mapping_range
+	 * allows holelen 0 for all, and we allow lend -1 for end of file.
+	 */
+
+	/*
+	 * Unlike in truncate_pagecache, unmap_mapping_range is called only
+	 * once (before truncating pagecache), and without "even_cows" flag:
+	 * hole-punching should not remove private COWed pages from the hole.
+	 */
+	if ((u64)unmap_end > (u64)unmap_start)
+		unmap_mapping_range(mapping, unmap_start,
+				    1 + unmap_end - unmap_start, 0);
+	truncate_inode_pages_range(mapping, lstart, lend);
+}
+EXPORT_SYMBOL(truncate_pagecache_range);
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
new file mode 100644
index 0000000..77fee93
--- /dev/null
+++ b/mm/userfaultfd.c
@@ -0,0 +1,308 @@
+/*
+ *  mm/userfaultfd.c
+ *
+ *  Copyright (C) 2015  Red Hat, Inc.
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2. See
+ *  the COPYING file in the top-level directory.
+ */
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/mmu_notifier.h>
+#include <asm/tlbflush.h>
+#include "internal.h"
+
+static int mcopy_atomic_pte(struct mm_struct *dst_mm,
+			    pmd_t *dst_pmd,
+			    struct vm_area_struct *dst_vma,
+			    unsigned long dst_addr,
+			    unsigned long src_addr,
+			    struct page **pagep)
+{
+	struct mem_cgroup *memcg;
+	pte_t _dst_pte, *dst_pte;
+	spinlock_t *ptl;
+	void *page_kaddr;
+	int ret;
+	struct page *page;
+
+	if (!*pagep) {
+		ret = -ENOMEM;
+		page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
+		if (!page)
+			goto out;
+
+		page_kaddr = kmap_atomic(page);
+		ret = copy_from_user(page_kaddr,
+				     (const void __user *) src_addr,
+				     PAGE_SIZE);
+		kunmap_atomic(page_kaddr);
+
+		/* fallback to copy_from_user outside mmap_sem */
+		if (unlikely(ret)) {
+			ret = -EFAULT;
+			*pagep = page;
+			/* don't free the page */
+			goto out;
+		}
+	} else {
+		page = *pagep;
+		*pagep = NULL;
+	}
+
+	/*
+	 * The memory barrier inside __SetPageUptodate makes sure that
+	 * preceeding stores to the page contents become visible before
+	 * the set_pte_at() write.
+	 */
+	__SetPageUptodate(page);
+
+	ret = -ENOMEM;
+	if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg))
+		goto out_release;
+
+	_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
+	if (dst_vma->vm_flags & VM_WRITE)
+		_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
+
+	ret = -EEXIST;
+	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+	if (!pte_none(*dst_pte))
+		goto out_release_uncharge_unlock;
+
+	inc_mm_counter(dst_mm, MM_ANONPAGES);
+	page_add_new_anon_rmap(page, dst_vma, dst_addr);
+	mem_cgroup_commit_charge(page, memcg, false);
+	lru_cache_add_active_or_unevictable(page, dst_vma);
+
+	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+
+	/* No need to invalidate - it was non-present before */
+	update_mmu_cache(dst_vma, dst_addr, dst_pte);
+
+	pte_unmap_unlock(dst_pte, ptl);
+	ret = 0;
+out:
+	return ret;
+out_release_uncharge_unlock:
+	pte_unmap_unlock(dst_pte, ptl);
+	mem_cgroup_cancel_charge(page, memcg);
+out_release:
+	page_cache_release(page);
+	goto out;
+}
+
+static int mfill_zeropage_pte(struct mm_struct *dst_mm,
+			      pmd_t *dst_pmd,
+			      struct vm_area_struct *dst_vma,
+			      unsigned long dst_addr)
+{
+	pte_t _dst_pte, *dst_pte;
+	spinlock_t *ptl;
+	int ret;
+
+	_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
+					 dst_vma->vm_page_prot));
+	ret = -EEXIST;
+	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+	if (!pte_none(*dst_pte))
+		goto out_unlock;
+	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+	/* No need to invalidate - it was non-present before */
+	update_mmu_cache(dst_vma, dst_addr, dst_pte);
+	ret = 0;
+out_unlock:
+	pte_unmap_unlock(dst_pte, ptl);
+	return ret;
+}
+
+static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd = NULL;
+
+	pgd = pgd_offset(mm, address);
+	pud = pud_alloc(mm, pgd, address);
+	if (pud)
+		/*
+		 * Note that we didn't run this because the pmd was
+		 * missing, the *pmd may be already established and in
+		 * turn it may also be a trans_huge_pmd.
+		 */
+		pmd = pmd_alloc(mm, pud, address);
+	return pmd;
+}
+
+static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
+					      unsigned long dst_start,
+					      unsigned long src_start,
+					      unsigned long len,
+					      bool zeropage)
+{
+	struct vm_area_struct *dst_vma;
+	ssize_t err;
+	pmd_t *dst_pmd;
+	unsigned long src_addr, dst_addr;
+	long copied;
+	struct page *page;
+
+	/*
+	 * Sanitize the command parameters:
+	 */
+	BUG_ON(dst_start & ~PAGE_MASK);
+	BUG_ON(len & ~PAGE_MASK);
+
+	/* Does the address range wrap, or is the span zero-sized? */
+	BUG_ON(src_start + len <= src_start);
+	BUG_ON(dst_start + len <= dst_start);
+
+	src_addr = src_start;
+	dst_addr = dst_start;
+	copied = 0;
+	page = NULL;
+retry:
+	down_read(&dst_mm->mmap_sem);
+
+	/*
+	 * Make sure the vma is not shared, that the dst range is
+	 * both valid and fully within a single existing vma.
+	 */
+	err = -EINVAL;
+	dst_vma = find_vma(dst_mm, dst_start);
+	if (!dst_vma || (dst_vma->vm_flags & VM_SHARED))
+		goto out_unlock;
+	if (dst_start < dst_vma->vm_start ||
+	    dst_start + len > dst_vma->vm_end)
+		goto out_unlock;
+
+	/*
+	 * Be strict and only allow __mcopy_atomic on userfaultfd
+	 * registered ranges to prevent userland errors going
+	 * unnoticed. As far as the VM consistency is concerned, it
+	 * would be perfectly safe to remove this check, but there's
+	 * no useful usage for __mcopy_atomic ouside of userfaultfd
+	 * registered ranges. This is after all why these are ioctls
+	 * belonging to the userfaultfd and not syscalls.
+	 */
+	if (!dst_vma->vm_userfaultfd_ctx.ctx)
+		goto out_unlock;
+
+	/*
+	 * FIXME: only allow copying on anonymous vmas, tmpfs should
+	 * be added.
+	 */
+	if (dst_vma->vm_ops)
+		goto out_unlock;
+
+	/*
+	 * Ensure the dst_vma has a anon_vma or this page
+	 * would get a NULL anon_vma when moved in the
+	 * dst_vma.
+	 */
+	err = -ENOMEM;
+	if (unlikely(anon_vma_prepare(dst_vma)))
+		goto out_unlock;
+
+	while (src_addr < src_start + len) {
+		pmd_t dst_pmdval;
+
+		BUG_ON(dst_addr >= dst_start + len);
+
+		dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
+		if (unlikely(!dst_pmd)) {
+			err = -ENOMEM;
+			break;
+		}
+
+		dst_pmdval = pmd_read_atomic(dst_pmd);
+		/*
+		 * If the dst_pmd is mapped as THP don't
+		 * override it and just be strict.
+		 */
+		if (unlikely(pmd_trans_huge(dst_pmdval))) {
+			err = -EEXIST;
+			break;
+		}
+		if (unlikely(pmd_none(dst_pmdval)) &&
+		    unlikely(__pte_alloc(dst_mm, dst_vma, dst_pmd,
+					 dst_addr))) {
+			err = -ENOMEM;
+			break;
+		}
+		/* If an huge pmd materialized from under us fail */
+		if (unlikely(pmd_trans_huge(*dst_pmd))) {
+			err = -EFAULT;
+			break;
+		}
+
+		BUG_ON(pmd_none(*dst_pmd));
+		BUG_ON(pmd_trans_huge(*dst_pmd));
+
+		if (!zeropage)
+			err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
+					       dst_addr, src_addr, &page);
+		else
+			err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma,
+						 dst_addr);
+
+		cond_resched();
+
+		if (unlikely(err == -EFAULT)) {
+			void *page_kaddr;
+
+			up_read(&dst_mm->mmap_sem);
+			BUG_ON(!page);
+
+			page_kaddr = kmap(page);
+			err = copy_from_user(page_kaddr,
+					     (const void __user *) src_addr,
+					     PAGE_SIZE);
+			kunmap(page);
+			if (unlikely(err)) {
+				err = -EFAULT;
+				goto out;
+			}
+			goto retry;
+		} else
+			BUG_ON(page);
+
+		if (!err) {
+			dst_addr += PAGE_SIZE;
+			src_addr += PAGE_SIZE;
+			copied += PAGE_SIZE;
+
+			if (fatal_signal_pending(current))
+				err = -EINTR;
+		}
+		if (err)
+			break;
+	}
+
+out_unlock:
+	up_read(&dst_mm->mmap_sem);
+out:
+	if (page)
+		page_cache_release(page);
+	BUG_ON(copied < 0);
+	BUG_ON(err > 0);
+	BUG_ON(!copied && !err);
+	return copied ? copied : err;
+}
+
+ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
+		     unsigned long src_start, unsigned long len)
+{
+	return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
+}
+
+ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
+		       unsigned long len)
+{
+	return __mcopy_atomic(dst_mm, start, 0, len, true);
+}
diff --git a/mm/util.c b/mm/util.c
new file mode 100644
index 0000000..d5259b6
--- /dev/null
+++ b/mm/util.c
@@ -0,0 +1,440 @@
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/compiler.h>
+#include <linux/export.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/security.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/mman.h>
+#include <linux/hugetlb.h>
+#include <linux/vmalloc.h>
+
+#include <asm/sections.h>
+#include <asm/uaccess.h>
+
+#include "internal.h"
+
+static inline int is_kernel_rodata(unsigned long addr)
+{
+	return addr >= (unsigned long)__start_rodata &&
+		addr < (unsigned long)__end_rodata;
+}
+
+/**
+ * kfree_const - conditionally free memory
+ * @x: pointer to the memory
+ *
+ * Function calls kfree only if @x is not in .rodata section.
+ */
+void kfree_const(const void *x)
+{
+	if (!is_kernel_rodata((unsigned long)x))
+		kfree(x);
+}
+EXPORT_SYMBOL(kfree_const);
+
+/**
+ * kstrdup - allocate space for and copy an existing string
+ * @s: the string to duplicate
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ */
+char *kstrdup(const char *s, gfp_t gfp)
+{
+	size_t len;
+	char *buf;
+
+	if (!s)
+		return NULL;
+
+	len = strlen(s) + 1;
+	buf = kmalloc_track_caller(len, gfp);
+	if (buf)
+		memcpy(buf, s, len);
+	return buf;
+}
+EXPORT_SYMBOL(kstrdup);
+
+/**
+ * kstrdup_const - conditionally duplicate an existing const string
+ * @s: the string to duplicate
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Function returns source string if it is in .rodata section otherwise it
+ * fallbacks to kstrdup.
+ * Strings allocated by kstrdup_const should be freed by kfree_const.
+ */
+const char *kstrdup_const(const char *s, gfp_t gfp)
+{
+	if (is_kernel_rodata((unsigned long)s))
+		return s;
+
+	return kstrdup(s, gfp);
+}
+EXPORT_SYMBOL(kstrdup_const);
+
+/**
+ * kstrndup - allocate space for and copy an existing string
+ * @s: the string to duplicate
+ * @max: read at most @max chars from @s
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ */
+char *kstrndup(const char *s, size_t max, gfp_t gfp)
+{
+	size_t len;
+	char *buf;
+
+	if (!s)
+		return NULL;
+
+	len = strnlen(s, max);
+	buf = kmalloc_track_caller(len+1, gfp);
+	if (buf) {
+		memcpy(buf, s, len);
+		buf[len] = '\0';
+	}
+	return buf;
+}
+EXPORT_SYMBOL(kstrndup);
+
+/**
+ * kmemdup - duplicate region of memory
+ *
+ * @src: memory region to duplicate
+ * @len: memory region length
+ * @gfp: GFP mask to use
+ */
+void *kmemdup(const void *src, size_t len, gfp_t gfp)
+{
+	void *p;
+
+	p = kmalloc_track_caller(len, gfp);
+	if (p)
+		memcpy(p, src, len);
+	return p;
+}
+EXPORT_SYMBOL(kmemdup);
+
+/**
+ * memdup_user - duplicate memory region from user space
+ *
+ * @src: source address in user space
+ * @len: number of bytes to copy
+ *
+ * Returns an ERR_PTR() on failure.
+ */
+void *memdup_user(const void __user *src, size_t len)
+{
+	void *p;
+
+	/*
+	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
+	 * cause pagefault, which makes it pointless to use GFP_NOFS
+	 * or GFP_ATOMIC.
+	 */
+	p = kmalloc_track_caller(len, GFP_KERNEL);
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	if (copy_from_user(p, src, len)) {
+		kfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+
+	return p;
+}
+EXPORT_SYMBOL(memdup_user);
+
+/*
+ * strndup_user - duplicate an existing string from user space
+ * @s: The string to duplicate
+ * @n: Maximum number of bytes to copy, including the trailing NUL.
+ */
+char *strndup_user(const char __user *s, long n)
+{
+	char *p;
+	long length;
+
+	length = strnlen_user(s, n);
+
+	if (!length)
+		return ERR_PTR(-EFAULT);
+
+	if (length > n)
+		return ERR_PTR(-EINVAL);
+
+	p = memdup_user(s, length);
+
+	if (IS_ERR(p))
+		return p;
+
+	p[length - 1] = '\0';
+
+	return p;
+}
+EXPORT_SYMBOL(strndup_user);
+
+void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct vm_area_struct *prev, struct rb_node *rb_parent)
+{
+	struct vm_area_struct *next;
+
+	vma->vm_prev = prev;
+	if (prev) {
+		next = prev->vm_next;
+		prev->vm_next = vma;
+	} else {
+		mm->mmap = vma;
+		if (rb_parent)
+			next = rb_entry(rb_parent,
+					struct vm_area_struct, vm_rb);
+		else
+			next = NULL;
+	}
+	vma->vm_next = next;
+	if (next)
+		next->vm_prev = vma;
+}
+
+/* Check if the vma is being used as a stack by this task */
+int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t)
+{
+	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
+}
+
+#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
+void arch_pick_mmap_layout(struct mm_struct *mm)
+{
+	mm->mmap_base = TASK_UNMAPPED_BASE;
+	mm->get_unmapped_area = arch_get_unmapped_area;
+}
+#endif
+
+/*
+ * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
+ * back to the regular GUP.
+ * If the architecture not support this function, simply return with no
+ * page pinned
+ */
+int __weak __get_user_pages_fast(unsigned long start,
+				 int nr_pages, int write, struct page **pages)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
+
+/**
+ * get_user_pages_fast() - pin user pages in memory
+ * @start:	starting user address
+ * @nr_pages:	number of pages from start to pin
+ * @write:	whether pages will be written to
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_pages long.
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno.
+ *
+ * get_user_pages_fast provides equivalent functionality to get_user_pages,
+ * operating on current and current->mm, with force=0 and vma=NULL. However
+ * unlike get_user_pages, it must be called without mmap_sem held.
+ *
+ * get_user_pages_fast may take mmap_sem and page table locks, so no
+ * assumptions can be made about lack of locking. get_user_pages_fast is to be
+ * implemented in a way that is advantageous (vs get_user_pages()) when the
+ * user memory area is already faulted in and present in ptes. However if the
+ * pages have to be faulted in, it may turn out to be slightly slower so
+ * callers need to carefully consider what to use. On many architectures,
+ * get_user_pages_fast simply falls back to get_user_pages.
+ */
+int __weak get_user_pages_fast(unsigned long start,
+				int nr_pages, int write, struct page **pages)
+{
+	struct mm_struct *mm = current->mm;
+	return get_user_pages_unlocked(current, mm, start, nr_pages,
+				       write, 0, pages);
+}
+EXPORT_SYMBOL_GPL(get_user_pages_fast);
+
+unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long prot,
+	unsigned long flag, unsigned long pgoff)
+{
+	unsigned long ret;
+	struct mm_struct *mm = current->mm;
+	unsigned long populate;
+
+	ret = security_mmap_file(file, prot, flag);
+	if (!ret) {
+		down_write(&mm->mmap_sem);
+		ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
+				    &populate);
+		up_write(&mm->mmap_sem);
+		if (populate)
+			mm_populate(ret, populate);
+	}
+	return ret;
+}
+
+unsigned long vm_mmap(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long prot,
+	unsigned long flag, unsigned long offset)
+{
+	if (unlikely(offset + PAGE_ALIGN(len) < offset))
+		return -EINVAL;
+	if (unlikely(offset_in_page(offset)))
+		return -EINVAL;
+
+	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(vm_mmap);
+
+void kvfree(const void *addr)
+{
+	if (is_vmalloc_addr(addr))
+		vfree(addr);
+	else
+		kfree(addr);
+}
+EXPORT_SYMBOL(kvfree);
+
+static inline void *__page_rmapping(struct page *page)
+{
+	unsigned long mapping;
+
+	mapping = (unsigned long)page->mapping;
+	mapping &= ~PAGE_MAPPING_FLAGS;
+
+	return (void *)mapping;
+}
+
+/* Neutral page->mapping pointer to address_space or anon_vma or other */
+void *page_rmapping(struct page *page)
+{
+	page = compound_head(page);
+	return __page_rmapping(page);
+}
+
+struct anon_vma *page_anon_vma(struct page *page)
+{
+	unsigned long mapping;
+
+	page = compound_head(page);
+	mapping = (unsigned long)page->mapping;
+	if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+		return NULL;
+	return __page_rmapping(page);
+}
+
+struct address_space *page_mapping(struct page *page)
+{
+	unsigned long mapping;
+
+	/* This happens if someone calls flush_dcache_page on slab page */
+	if (unlikely(PageSlab(page)))
+		return NULL;
+
+	if (unlikely(PageSwapCache(page))) {
+		swp_entry_t entry;
+
+		entry.val = page_private(page);
+		return swap_address_space(entry);
+	}
+
+	mapping = (unsigned long)page->mapping;
+	if (mapping & PAGE_MAPPING_FLAGS)
+		return NULL;
+	return page->mapping;
+}
+
+int overcommit_ratio_handler(struct ctl_table *table, int write,
+			     void __user *buffer, size_t *lenp,
+			     loff_t *ppos)
+{
+	int ret;
+
+	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+	if (ret == 0 && write)
+		sysctl_overcommit_kbytes = 0;
+	return ret;
+}
+
+int overcommit_kbytes_handler(struct ctl_table *table, int write,
+			     void __user *buffer, size_t *lenp,
+			     loff_t *ppos)
+{
+	int ret;
+
+	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret == 0 && write)
+		sysctl_overcommit_ratio = 0;
+	return ret;
+}
+
+/*
+ * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
+ */
+unsigned long vm_commit_limit(void)
+{
+	unsigned long allowed;
+
+	if (sysctl_overcommit_kbytes)
+		allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
+	else
+		allowed = ((totalram_pages - hugetlb_total_pages())
+			   * sysctl_overcommit_ratio / 100);
+	allowed += total_swap_pages;
+
+	return allowed;
+}
+
+/**
+ * get_cmdline() - copy the cmdline value to a buffer.
+ * @task:     the task whose cmdline value to copy.
+ * @buffer:   the buffer to copy to.
+ * @buflen:   the length of the buffer. Larger cmdline values are truncated
+ *            to this length.
+ * Returns the size of the cmdline field copied. Note that the copy does
+ * not guarantee an ending NULL byte.
+ */
+int get_cmdline(struct task_struct *task, char *buffer, int buflen)
+{
+	int res = 0;
+	unsigned int len;
+	struct mm_struct *mm = get_task_mm(task);
+	if (!mm)
+		goto out;
+	if (!mm->arg_end)
+		goto out_mm;	/* Shh! No looking before we're done */
+
+	len = mm->arg_end - mm->arg_start;
+
+	if (len > buflen)
+		len = buflen;
+
+	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
+
+	/*
+	 * If the nul at the end of args has been overwritten, then
+	 * assume application is using setproctitle(3).
+	 */
+	if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
+		len = strnlen(buffer, res);
+		if (len < res) {
+			res = len;
+		} else {
+			len = mm->env_end - mm->env_start;
+			if (len > buflen - res)
+				len = buflen - res;
+			res += access_process_vm(task, mm->env_start,
+						 buffer+res, len, 0);
+			res = strnlen(buffer, res);
+		}
+	}
+out_mm:
+	mmput(mm);
+out:
+	return res;
+}
diff --git a/mm/vmacache.c b/mm/vmacache.c
new file mode 100644
index 0000000..fd09dc9
--- /dev/null
+++ b/mm/vmacache.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2014 Davidlohr Bueso.
+ */
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/vmacache.h>
+
+/*
+ * Flush vma caches for threads that share a given mm.
+ *
+ * The operation is safe because the caller holds the mmap_sem
+ * exclusively and other threads accessing the vma cache will
+ * have mmap_sem held at least for read, so no extra locking
+ * is required to maintain the vma cache.
+ */
+void vmacache_flush_all(struct mm_struct *mm)
+{
+	struct task_struct *g, *p;
+
+	count_vm_vmacache_event(VMACACHE_FULL_FLUSHES);
+
+	/*
+	 * Single threaded tasks need not iterate the entire
+	 * list of process. We can avoid the flushing as well
+	 * since the mm's seqnum was increased and don't have
+	 * to worry about other threads' seqnum. Current's
+	 * flush will occur upon the next lookup.
+	 */
+	if (atomic_read(&mm->mm_users) == 1)
+		return;
+
+	rcu_read_lock();
+	for_each_process_thread(g, p) {
+		/*
+		 * Only flush the vmacache pointers as the
+		 * mm seqnum is already set and curr's will
+		 * be set upon invalidation when the next
+		 * lookup is done.
+		 */
+		if (mm == p->mm)
+			vmacache_flush(p);
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * This task may be accessing a foreign mm via (for example)
+ * get_user_pages()->find_vma().  The vmacache is task-local and this
+ * task's vmacache pertains to a different mm (ie, its own).  There is
+ * nothing we can do here.
+ *
+ * Also handle the case where a kernel thread has adopted this mm via use_mm().
+ * That kernel thread's vmacache is not applicable to this mm.
+ */
+static inline bool vmacache_valid_mm(struct mm_struct *mm)
+{
+	return current->mm == mm && !(current->flags & PF_KTHREAD);
+}
+
+void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
+{
+	if (vmacache_valid_mm(newvma->vm_mm))
+		current->vmacache[VMACACHE_HASH(addr)] = newvma;
+}
+
+static bool vmacache_valid(struct mm_struct *mm)
+{
+	struct task_struct *curr;
+
+	if (!vmacache_valid_mm(mm))
+		return false;
+
+	curr = current;
+	if (mm->vmacache_seqnum != curr->vmacache_seqnum) {
+		/*
+		 * First attempt will always be invalid, initialize
+		 * the new cache for this task here.
+		 */
+		curr->vmacache_seqnum = mm->vmacache_seqnum;
+		vmacache_flush(curr);
+		return false;
+	}
+	return true;
+}
+
+struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
+{
+	int i;
+
+	if (!vmacache_valid(mm))
+		return NULL;
+
+	count_vm_vmacache_event(VMACACHE_FIND_CALLS);
+
+	for (i = 0; i < VMACACHE_SIZE; i++) {
+		struct vm_area_struct *vma = current->vmacache[i];
+
+		if (!vma)
+			continue;
+		if (WARN_ON_ONCE(vma->vm_mm != mm))
+			break;
+		if (vma->vm_start <= addr && vma->vm_end > addr) {
+			count_vm_vmacache_event(VMACACHE_FIND_HITS);
+			return vma;
+		}
+	}
+
+	return NULL;
+}
+
+#ifndef CONFIG_MMU
+struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
+					   unsigned long start,
+					   unsigned long end)
+{
+	int i;
+
+	if (!vmacache_valid(mm))
+		return NULL;
+
+	count_vm_vmacache_event(VMACACHE_FIND_CALLS);
+
+	for (i = 0; i < VMACACHE_SIZE; i++) {
+		struct vm_area_struct *vma = current->vmacache[i];
+
+		if (vma && vma->vm_start == start && vma->vm_end == end) {
+			count_vm_vmacache_event(VMACACHE_FIND_HITS);
+			return vma;
+		}
+	}
+
+	return NULL;
+}
+#endif
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
new file mode 100644
index 0000000..8e3c9c5
--- /dev/null
+++ b/mm/vmalloc.c
@@ -0,0 +1,2693 @@
+/*
+ *  linux/mm/vmalloc.c
+ *
+ *  Copyright (C) 1993  Linus Torvalds
+ *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
+ *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
+ *  Numa awareness, Christoph Lameter, SGI, June 2005
+ */
+
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/highmem.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/debugobjects.h>
+#include <linux/kallsyms.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include <linux/radix-tree.h>
+#include <linux/rcupdate.h>
+#include <linux/pfn.h>
+#include <linux/kmemleak.h>
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/llist.h>
+#include <linux/bitops.h>
+
+#include <asm/uaccess.h>
+#include <asm/tlbflush.h>
+#include <asm/shmparam.h>
+
+#include "internal.h"
+
+struct vfree_deferred {
+	struct llist_head list;
+	struct work_struct wq;
+};
+static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);
+
+static void __vunmap(const void *, int);
+
+static void free_work(struct work_struct *w)
+{
+	struct vfree_deferred *p = container_of(w, struct vfree_deferred, wq);
+	struct llist_node *llnode = llist_del_all(&p->list);
+	while (llnode) {
+		void *p = llnode;
+		llnode = llist_next(llnode);
+		__vunmap(p, 1);
+	}
+}
+
+/*** Page table manipulation functions ***/
+
+static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
+{
+	pte_t *pte;
+
+	pte = pte_offset_kernel(pmd, addr);
+	do {
+		pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
+		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+}
+
+static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_clear_huge(pmd))
+			continue;
+		if (pmd_none_or_clear_bad(pmd))
+			continue;
+		vunmap_pte_range(pmd, addr, next);
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void vunmap_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_clear_huge(pud))
+			continue;
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		vunmap_pmd_range(pud, addr, next);
+	} while (pud++, addr = next, addr != end);
+}
+
+static void vunmap_page_range(unsigned long addr, unsigned long end)
+{
+	pgd_t *pgd;
+	unsigned long next;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset_k(addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		vunmap_pud_range(pgd, addr, next);
+	} while (pgd++, addr = next, addr != end);
+}
+
+static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	pte_t *pte;
+
+	/*
+	 * nr is a running index into the array which helps higher level
+	 * callers keep track of where we're up to.
+	 */
+
+	pte = pte_alloc_kernel(pmd, addr);
+	if (!pte)
+		return -ENOMEM;
+	do {
+		struct page *page = pages[*nr];
+
+		if (WARN_ON(!pte_none(*pte)))
+			return -EBUSY;
+		if (WARN_ON(!page))
+			return -ENOMEM;
+		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
+		(*nr)++;
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	return 0;
+}
+
+static int vmap_pmd_range(pud_t *pud, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_alloc(&init_mm, pud, addr);
+	if (!pmd)
+		return -ENOMEM;
+	do {
+		next = pmd_addr_end(addr, end);
+		if (vmap_pte_range(pmd, addr, next, prot, pages, nr))
+			return -ENOMEM;
+	} while (pmd++, addr = next, addr != end);
+	return 0;
+}
+
+static int vmap_pud_range(pgd_t *pgd, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_alloc(&init_mm, pgd, addr);
+	if (!pud)
+		return -ENOMEM;
+	do {
+		next = pud_addr_end(addr, end);
+		if (vmap_pmd_range(pud, addr, next, prot, pages, nr))
+			return -ENOMEM;
+	} while (pud++, addr = next, addr != end);
+	return 0;
+}
+
+/*
+ * Set up page tables in kva (addr, end). The ptes shall have prot "prot", and
+ * will have pfns corresponding to the "pages" array.
+ *
+ * Ie. pte at addr+N*PAGE_SIZE shall point to pfn corresponding to pages[N]
+ */
+static int vmap_page_range_noflush(unsigned long start, unsigned long end,
+				   pgprot_t prot, struct page **pages)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long addr = start;
+	int err = 0;
+	int nr = 0;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset_k(addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		err = vmap_pud_range(pgd, addr, next, prot, pages, &nr);
+		if (err)
+			return err;
+	} while (pgd++, addr = next, addr != end);
+
+	return nr;
+}
+
+static int vmap_page_range(unsigned long start, unsigned long end,
+			   pgprot_t prot, struct page **pages)
+{
+	int ret;
+
+	ret = vmap_page_range_noflush(start, end, prot, pages);
+	flush_cache_vmap(start, end);
+	return ret;
+}
+
+int is_vmalloc_or_module_addr(const void *x)
+{
+	/*
+	 * ARM, x86-64 and sparc64 put modules in a special place,
+	 * and fall back on vmalloc() if that fails. Others
+	 * just put it in the vmalloc space.
+	 */
+#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
+	unsigned long addr = (unsigned long)x;
+	if (addr >= MODULES_VADDR && addr < MODULES_END)
+		return 1;
+#endif
+	return is_vmalloc_addr(x);
+}
+
+/*
+ * Walk a vmap address to the struct page it maps.
+ */
+struct page *vmalloc_to_page(const void *vmalloc_addr)
+{
+	unsigned long addr = (unsigned long) vmalloc_addr;
+	struct page *page = NULL;
+	pgd_t *pgd = pgd_offset_k(addr);
+
+	/*
+	 * XXX we might need to change this if we add VIRTUAL_BUG_ON for
+	 * architectures that do not vmalloc module space
+	 */
+	VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr));
+
+	if (!pgd_none(*pgd)) {
+		pud_t *pud = pud_offset(pgd, addr);
+		if (!pud_none(*pud)) {
+			pmd_t *pmd = pmd_offset(pud, addr);
+			if (!pmd_none(*pmd)) {
+				pte_t *ptep, pte;
+
+				ptep = pte_offset_map(pmd, addr);
+				pte = *ptep;
+				if (pte_present(pte))
+					page = pte_page(pte);
+				pte_unmap(ptep);
+			}
+		}
+	}
+	return page;
+}
+EXPORT_SYMBOL(vmalloc_to_page);
+
+/*
+ * Map a vmalloc()-space virtual address to the physical page frame number.
+ */
+unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
+{
+	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
+}
+EXPORT_SYMBOL(vmalloc_to_pfn);
+
+
+/*** Global kva allocator ***/
+
+#define VM_LAZY_FREE	0x01
+#define VM_LAZY_FREEING	0x02
+#define VM_VM_AREA	0x04
+
+static DEFINE_SPINLOCK(vmap_area_lock);
+/* Export for kexec only */
+LIST_HEAD(vmap_area_list);
+static struct rb_root vmap_area_root = RB_ROOT;
+
+/* The vmap cache globals are protected by vmap_area_lock */
+static struct rb_node *free_vmap_cache;
+static unsigned long cached_hole_size;
+static unsigned long cached_vstart;
+static unsigned long cached_align;
+
+static unsigned long vmap_area_pcpu_hole;
+
+static struct vmap_area *__find_vmap_area(unsigned long addr)
+{
+	struct rb_node *n = vmap_area_root.rb_node;
+
+	while (n) {
+		struct vmap_area *va;
+
+		va = rb_entry(n, struct vmap_area, rb_node);
+		if (addr < va->va_start)
+			n = n->rb_left;
+		else if (addr >= va->va_end)
+			n = n->rb_right;
+		else
+			return va;
+	}
+
+	return NULL;
+}
+
+static void __insert_vmap_area(struct vmap_area *va)
+{
+	struct rb_node **p = &vmap_area_root.rb_node;
+	struct rb_node *parent = NULL;
+	struct rb_node *tmp;
+
+	while (*p) {
+		struct vmap_area *tmp_va;
+
+		parent = *p;
+		tmp_va = rb_entry(parent, struct vmap_area, rb_node);
+		if (va->va_start < tmp_va->va_end)
+			p = &(*p)->rb_left;
+		else if (va->va_end > tmp_va->va_start)
+			p = &(*p)->rb_right;
+		else
+			BUG();
+	}
+
+	rb_link_node(&va->rb_node, parent, p);
+	rb_insert_color(&va->rb_node, &vmap_area_root);
+
+	/* address-sort this list */
+	tmp = rb_prev(&va->rb_node);
+	if (tmp) {
+		struct vmap_area *prev;
+		prev = rb_entry(tmp, struct vmap_area, rb_node);
+		list_add_rcu(&va->list, &prev->list);
+	} else
+		list_add_rcu(&va->list, &vmap_area_list);
+}
+
+static void purge_vmap_area_lazy(void);
+
+/*
+ * Allocate a region of KVA of the specified size and alignment, within the
+ * vstart and vend.
+ */
+static struct vmap_area *alloc_vmap_area(unsigned long size,
+				unsigned long align,
+				unsigned long vstart, unsigned long vend,
+				int node, gfp_t gfp_mask)
+{
+	struct vmap_area *va;
+	struct rb_node *n;
+	unsigned long addr;
+	int purged = 0;
+	struct vmap_area *first;
+
+	BUG_ON(!size);
+	BUG_ON(offset_in_page(size));
+	BUG_ON(!is_power_of_2(align));
+
+	va = kmalloc_node(sizeof(struct vmap_area),
+			gfp_mask & GFP_RECLAIM_MASK, node);
+	if (unlikely(!va))
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * Only scan the relevant parts containing pointers to other objects
+	 * to avoid false negatives.
+	 */
+	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask & GFP_RECLAIM_MASK);
+
+retry:
+	spin_lock(&vmap_area_lock);
+	/*
+	 * Invalidate cache if we have more permissive parameters.
+	 * cached_hole_size notes the largest hole noticed _below_
+	 * the vmap_area cached in free_vmap_cache: if size fits
+	 * into that hole, we want to scan from vstart to reuse
+	 * the hole instead of allocating above free_vmap_cache.
+	 * Note that __free_vmap_area may update free_vmap_cache
+	 * without updating cached_hole_size or cached_align.
+	 */
+	if (!free_vmap_cache ||
+			size < cached_hole_size ||
+			vstart < cached_vstart ||
+			align < cached_align) {
+nocache:
+		cached_hole_size = 0;
+		free_vmap_cache = NULL;
+	}
+	/* record if we encounter less permissive parameters */
+	cached_vstart = vstart;
+	cached_align = align;
+
+	/* find starting point for our search */
+	if (free_vmap_cache) {
+		first = rb_entry(free_vmap_cache, struct vmap_area, rb_node);
+		addr = ALIGN(first->va_end, align);
+		if (addr < vstart)
+			goto nocache;
+		if (addr + size < addr)
+			goto overflow;
+
+	} else {
+		addr = ALIGN(vstart, align);
+		if (addr + size < addr)
+			goto overflow;
+
+		n = vmap_area_root.rb_node;
+		first = NULL;
+
+		while (n) {
+			struct vmap_area *tmp;
+			tmp = rb_entry(n, struct vmap_area, rb_node);
+			if (tmp->va_end >= addr) {
+				first = tmp;
+				if (tmp->va_start <= addr)
+					break;
+				n = n->rb_left;
+			} else
+				n = n->rb_right;
+		}
+
+		if (!first)
+			goto found;
+	}
+
+	/* from the starting point, walk areas until a suitable hole is found */
+	while (addr + size > first->va_start && addr + size <= vend) {
+		if (addr + cached_hole_size < first->va_start)
+			cached_hole_size = first->va_start - addr;
+		addr = ALIGN(first->va_end, align);
+		if (addr + size < addr)
+			goto overflow;
+
+		if (list_is_last(&first->list, &vmap_area_list))
+			goto found;
+
+		first = list_entry(first->list.next,
+				struct vmap_area, list);
+	}
+
+found:
+	if (addr + size > vend)
+		goto overflow;
+
+	va->va_start = addr;
+	va->va_end = addr + size;
+	va->flags = 0;
+	__insert_vmap_area(va);
+	free_vmap_cache = &va->rb_node;
+	spin_unlock(&vmap_area_lock);
+
+	BUG_ON(va->va_start & (align-1));
+	BUG_ON(va->va_start < vstart);
+	BUG_ON(va->va_end > vend);
+
+	return va;
+
+overflow:
+	spin_unlock(&vmap_area_lock);
+	if (!purged) {
+		purge_vmap_area_lazy();
+		purged = 1;
+		goto retry;
+	}
+	if (printk_ratelimit())
+		pr_warn("vmap allocation for size %lu failed: "
+			"use vmalloc=<size> to increase size.\n", size);
+	kfree(va);
+	return ERR_PTR(-EBUSY);
+}
+
+static void __free_vmap_area(struct vmap_area *va)
+{
+	BUG_ON(RB_EMPTY_NODE(&va->rb_node));
+
+	if (free_vmap_cache) {
+		if (va->va_end < cached_vstart) {
+			free_vmap_cache = NULL;
+		} else {
+			struct vmap_area *cache;
+			cache = rb_entry(free_vmap_cache, struct vmap_area, rb_node);
+			if (va->va_start <= cache->va_start) {
+				free_vmap_cache = rb_prev(&va->rb_node);
+				/*
+				 * We don't try to update cached_hole_size or
+				 * cached_align, but it won't go very wrong.
+				 */
+			}
+		}
+	}
+	rb_erase(&va->rb_node, &vmap_area_root);
+	RB_CLEAR_NODE(&va->rb_node);
+	list_del_rcu(&va->list);
+
+	/*
+	 * Track the highest possible candidate for pcpu area
+	 * allocation.  Areas outside of vmalloc area can be returned
+	 * here too, consider only end addresses which fall inside
+	 * vmalloc area proper.
+	 */
+	if (va->va_end > VMALLOC_START && va->va_end <= VMALLOC_END)
+		vmap_area_pcpu_hole = max(vmap_area_pcpu_hole, va->va_end);
+
+	kfree_rcu(va, rcu_head);
+}
+
+/*
+ * Free a region of KVA allocated by alloc_vmap_area
+ */
+static void free_vmap_area(struct vmap_area *va)
+{
+	spin_lock(&vmap_area_lock);
+	__free_vmap_area(va);
+	spin_unlock(&vmap_area_lock);
+}
+
+/*
+ * Clear the pagetable entries of a given vmap_area
+ */
+static void unmap_vmap_area(struct vmap_area *va)
+{
+	vunmap_page_range(va->va_start, va->va_end);
+}
+
+static void vmap_debug_free_range(unsigned long start, unsigned long end)
+{
+	/*
+	 * Unmap page tables and force a TLB flush immediately if
+	 * CONFIG_DEBUG_PAGEALLOC is set. This catches use after free
+	 * bugs similarly to those in linear kernel virtual address
+	 * space after a page has been freed.
+	 *
+	 * All the lazy freeing logic is still retained, in order to
+	 * minimise intrusiveness of this debugging feature.
+	 *
+	 * This is going to be *slow* (linear kernel virtual address
+	 * debugging doesn't do a broadcast TLB flush so it is a lot
+	 * faster).
+	 */
+#ifdef CONFIG_DEBUG_PAGEALLOC
+	vunmap_page_range(start, end);
+	flush_tlb_kernel_range(start, end);
+#endif
+}
+
+/*
+ * lazy_max_pages is the maximum amount of virtual address space we gather up
+ * before attempting to purge with a TLB flush.
+ *
+ * There is a tradeoff here: a larger number will cover more kernel page tables
+ * and take slightly longer to purge, but it will linearly reduce the number of
+ * global TLB flushes that must be performed. It would seem natural to scale
+ * this number up linearly with the number of CPUs (because vmapping activity
+ * could also scale linearly with the number of CPUs), however it is likely
+ * that in practice, workloads might be constrained in other ways that mean
+ * vmap activity will not scale linearly with CPUs. Also, I want to be
+ * conservative and not introduce a big latency on huge systems, so go with
+ * a less aggressive log scale. It will still be an improvement over the old
+ * code, and it will be simple to change the scale factor if we find that it
+ * becomes a problem on bigger systems.
+ */
+static unsigned long lazy_max_pages(void)
+{
+	unsigned int log;
+
+	log = fls(num_online_cpus());
+
+	return log * (32UL * 1024 * 1024 / PAGE_SIZE);
+}
+
+static atomic_t vmap_lazy_nr = ATOMIC_INIT(0);
+
+/* for per-CPU blocks */
+static void purge_fragmented_blocks_allcpus(void);
+
+/*
+ * called before a call to iounmap() if the caller wants vm_area_struct's
+ * immediately freed.
+ */
+void set_iounmap_nonlazy(void)
+{
+	atomic_set(&vmap_lazy_nr, lazy_max_pages()+1);
+}
+
+/*
+ * Purges all lazily-freed vmap areas.
+ *
+ * If sync is 0 then don't purge if there is already a purge in progress.
+ * If force_flush is 1, then flush kernel TLBs between *start and *end even
+ * if we found no lazy vmap areas to unmap (callers can use this to optimise
+ * their own TLB flushing).
+ * Returns with *start = min(*start, lowest purged address)
+ *              *end = max(*end, highest purged address)
+ */
+static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
+					int sync, int force_flush)
+{
+	static DEFINE_SPINLOCK(purge_lock);
+	LIST_HEAD(valist);
+	struct vmap_area *va;
+	struct vmap_area *n_va;
+	int nr = 0;
+
+	/*
+	 * If sync is 0 but force_flush is 1, we'll go sync anyway but callers
+	 * should not expect such behaviour. This just simplifies locking for
+	 * the case that isn't actually used at the moment anyway.
+	 */
+	if (!sync && !force_flush) {
+		if (!spin_trylock(&purge_lock))
+			return;
+	} else
+		spin_lock(&purge_lock);
+
+	if (sync)
+		purge_fragmented_blocks_allcpus();
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(va, &vmap_area_list, list) {
+		if (va->flags & VM_LAZY_FREE) {
+			if (va->va_start < *start)
+				*start = va->va_start;
+			if (va->va_end > *end)
+				*end = va->va_end;
+			nr += (va->va_end - va->va_start) >> PAGE_SHIFT;
+			list_add_tail(&va->purge_list, &valist);
+			va->flags |= VM_LAZY_FREEING;
+			va->flags &= ~VM_LAZY_FREE;
+		}
+	}
+	rcu_read_unlock();
+
+	if (nr)
+		atomic_sub(nr, &vmap_lazy_nr);
+
+	if (nr || force_flush)
+		flush_tlb_kernel_range(*start, *end);
+
+	if (nr) {
+		spin_lock(&vmap_area_lock);
+		list_for_each_entry_safe(va, n_va, &valist, purge_list)
+			__free_vmap_area(va);
+		spin_unlock(&vmap_area_lock);
+	}
+	spin_unlock(&purge_lock);
+}
+
+/*
+ * Kick off a purge of the outstanding lazy areas. Don't bother if somebody
+ * is already purging.
+ */
+static void try_purge_vmap_area_lazy(void)
+{
+	unsigned long start = ULONG_MAX, end = 0;
+
+	__purge_vmap_area_lazy(&start, &end, 0, 0);
+}
+
+/*
+ * Kick off a purge of the outstanding lazy areas.
+ */
+static void purge_vmap_area_lazy(void)
+{
+	unsigned long start = ULONG_MAX, end = 0;
+
+	__purge_vmap_area_lazy(&start, &end, 1, 0);
+}
+
+/*
+ * Free a vmap area, caller ensuring that the area has been unmapped
+ * and flush_cache_vunmap had been called for the correct range
+ * previously.
+ */
+static void free_vmap_area_noflush(struct vmap_area *va)
+{
+	va->flags |= VM_LAZY_FREE;
+	atomic_add((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr);
+	if (unlikely(atomic_read(&vmap_lazy_nr) > lazy_max_pages()))
+		try_purge_vmap_area_lazy();
+}
+
+/*
+ * Free and unmap a vmap area, caller ensuring flush_cache_vunmap had been
+ * called for the correct range previously.
+ */
+static void free_unmap_vmap_area_noflush(struct vmap_area *va)
+{
+	unmap_vmap_area(va);
+	free_vmap_area_noflush(va);
+}
+
+/*
+ * Free and unmap a vmap area
+ */
+static void free_unmap_vmap_area(struct vmap_area *va)
+{
+	flush_cache_vunmap(va->va_start, va->va_end);
+	free_unmap_vmap_area_noflush(va);
+}
+
+static struct vmap_area *find_vmap_area(unsigned long addr)
+{
+	struct vmap_area *va;
+
+	spin_lock(&vmap_area_lock);
+	va = __find_vmap_area(addr);
+	spin_unlock(&vmap_area_lock);
+
+	return va;
+}
+
+static void free_unmap_vmap_area_addr(unsigned long addr)
+{
+	struct vmap_area *va;
+
+	va = find_vmap_area(addr);
+	BUG_ON(!va);
+	free_unmap_vmap_area(va);
+}
+
+
+/*** Per cpu kva allocator ***/
+
+/*
+ * vmap space is limited especially on 32 bit architectures. Ensure there is
+ * room for at least 16 percpu vmap blocks per CPU.
+ */
+/*
+ * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able
+ * to #define VMALLOC_SPACE		(VMALLOC_END-VMALLOC_START). Guess
+ * instead (we just need a rough idea)
+ */
+#if BITS_PER_LONG == 32
+#define VMALLOC_SPACE		(128UL*1024*1024)
+#else
+#define VMALLOC_SPACE		(128UL*1024*1024*1024)
+#endif
+
+#define VMALLOC_PAGES		(VMALLOC_SPACE / PAGE_SIZE)
+#define VMAP_MAX_ALLOC		BITS_PER_LONG	/* 256K with 4K pages */
+#define VMAP_BBMAP_BITS_MAX	1024	/* 4MB with 4K pages */
+#define VMAP_BBMAP_BITS_MIN	(VMAP_MAX_ALLOC*2)
+#define VMAP_MIN(x, y)		((x) < (y) ? (x) : (y)) /* can't use min() */
+#define VMAP_MAX(x, y)		((x) > (y) ? (x) : (y)) /* can't use max() */
+#define VMAP_BBMAP_BITS		\
+		VMAP_MIN(VMAP_BBMAP_BITS_MAX,	\
+		VMAP_MAX(VMAP_BBMAP_BITS_MIN,	\
+			VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))
+
+#define VMAP_BLOCK_SIZE		(VMAP_BBMAP_BITS * PAGE_SIZE)
+
+static bool vmap_initialized __read_mostly = false;
+
+struct vmap_block_queue {
+	spinlock_t lock;
+	struct list_head free;
+};
+
+struct vmap_block {
+	spinlock_t lock;
+	struct vmap_area *va;
+	unsigned long free, dirty;
+	unsigned long dirty_min, dirty_max; /*< dirty range */
+	struct list_head free_list;
+	struct rcu_head rcu_head;
+	struct list_head purge;
+};
+
+/* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
+static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);
+
+/*
+ * Radix tree of vmap blocks, indexed by address, to quickly find a vmap block
+ * in the free path. Could get rid of this if we change the API to return a
+ * "cookie" from alloc, to be passed to free. But no big deal yet.
+ */
+static DEFINE_SPINLOCK(vmap_block_tree_lock);
+static RADIX_TREE(vmap_block_tree, GFP_ATOMIC);
+
+/*
+ * We should probably have a fallback mechanism to allocate virtual memory
+ * out of partially filled vmap blocks. However vmap block sizing should be
+ * fairly reasonable according to the vmalloc size, so it shouldn't be a
+ * big problem.
+ */
+
+static unsigned long addr_to_vb_idx(unsigned long addr)
+{
+	addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1);
+	addr /= VMAP_BLOCK_SIZE;
+	return addr;
+}
+
+static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off)
+{
+	unsigned long addr;
+
+	addr = va_start + (pages_off << PAGE_SHIFT);
+	BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start));
+	return (void *)addr;
+}
+
+/**
+ * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
+ *                  block. Of course pages number can't exceed VMAP_BBMAP_BITS
+ * @order:    how many 2^order pages should be occupied in newly allocated block
+ * @gfp_mask: flags for the page level allocator
+ *
+ * Returns: virtual address in a newly allocated block or ERR_PTR(-errno)
+ */
+static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
+{
+	struct vmap_block_queue *vbq;
+	struct vmap_block *vb;
+	struct vmap_area *va;
+	unsigned long vb_idx;
+	int node, err;
+	void *vaddr;
+
+	node = numa_node_id();
+
+	vb = kmalloc_node(sizeof(struct vmap_block),
+			gfp_mask & GFP_RECLAIM_MASK, node);
+	if (unlikely(!vb))
+		return ERR_PTR(-ENOMEM);
+
+	va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
+					VMALLOC_START, VMALLOC_END,
+					node, gfp_mask);
+	if (IS_ERR(va)) {
+		kfree(vb);
+		return ERR_CAST(va);
+	}
+
+	err = radix_tree_preload(gfp_mask);
+	if (unlikely(err)) {
+		kfree(vb);
+		free_vmap_area(va);
+		return ERR_PTR(err);
+	}
+
+	vaddr = vmap_block_vaddr(va->va_start, 0);
+	spin_lock_init(&vb->lock);
+	vb->va = va;
+	/* At least something should be left free */
+	BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
+	vb->free = VMAP_BBMAP_BITS - (1UL << order);
+	vb->dirty = 0;
+	vb->dirty_min = VMAP_BBMAP_BITS;
+	vb->dirty_max = 0;
+	INIT_LIST_HEAD(&vb->free_list);
+
+	vb_idx = addr_to_vb_idx(va->va_start);
+	spin_lock(&vmap_block_tree_lock);
+	err = radix_tree_insert(&vmap_block_tree, vb_idx, vb);
+	spin_unlock(&vmap_block_tree_lock);
+	BUG_ON(err);
+	radix_tree_preload_end();
+
+	vbq = &get_cpu_var(vmap_block_queue);
+	spin_lock(&vbq->lock);
+	list_add_tail_rcu(&vb->free_list, &vbq->free);
+	spin_unlock(&vbq->lock);
+	put_cpu_var(vmap_block_queue);
+
+	return vaddr;
+}
+
+static void free_vmap_block(struct vmap_block *vb)
+{
+	struct vmap_block *tmp;
+	unsigned long vb_idx;
+
+	vb_idx = addr_to_vb_idx(vb->va->va_start);
+	spin_lock(&vmap_block_tree_lock);
+	tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
+	spin_unlock(&vmap_block_tree_lock);
+	BUG_ON(tmp != vb);
+
+	free_vmap_area_noflush(vb->va);
+	kfree_rcu(vb, rcu_head);
+}
+
+static void purge_fragmented_blocks(int cpu)
+{
+	LIST_HEAD(purge);
+	struct vmap_block *vb;
+	struct vmap_block *n_vb;
+	struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+
+		if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
+			continue;
+
+		spin_lock(&vb->lock);
+		if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS) {
+			vb->free = 0; /* prevent further allocs after releasing lock */
+			vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
+			vb->dirty_min = 0;
+			vb->dirty_max = VMAP_BBMAP_BITS;
+			spin_lock(&vbq->lock);
+			list_del_rcu(&vb->free_list);
+			spin_unlock(&vbq->lock);
+			spin_unlock(&vb->lock);
+			list_add_tail(&vb->purge, &purge);
+		} else
+			spin_unlock(&vb->lock);
+	}
+	rcu_read_unlock();
+
+	list_for_each_entry_safe(vb, n_vb, &purge, purge) {
+		list_del(&vb->purge);
+		free_vmap_block(vb);
+	}
+}
+
+static void purge_fragmented_blocks_allcpus(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		purge_fragmented_blocks(cpu);
+}
+
+static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
+{
+	struct vmap_block_queue *vbq;
+	struct vmap_block *vb;
+	void *vaddr = NULL;
+	unsigned int order;
+
+	BUG_ON(offset_in_page(size));
+	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
+	if (WARN_ON(size == 0)) {
+		/*
+		 * Allocating 0 bytes isn't what caller wants since
+		 * get_order(0) returns funny result. Just warn and terminate
+		 * early.
+		 */
+		return NULL;
+	}
+	order = get_order(size);
+
+	rcu_read_lock();
+	vbq = &get_cpu_var(vmap_block_queue);
+	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+		unsigned long pages_off;
+
+		spin_lock(&vb->lock);
+		if (vb->free < (1UL << order)) {
+			spin_unlock(&vb->lock);
+			continue;
+		}
+
+		pages_off = VMAP_BBMAP_BITS - vb->free;
+		vaddr = vmap_block_vaddr(vb->va->va_start, pages_off);
+		vb->free -= 1UL << order;
+		if (vb->free == 0) {
+			spin_lock(&vbq->lock);
+			list_del_rcu(&vb->free_list);
+			spin_unlock(&vbq->lock);
+		}
+
+		spin_unlock(&vb->lock);
+		break;
+	}
+
+	put_cpu_var(vmap_block_queue);
+	rcu_read_unlock();
+
+	/* Allocate new block if nothing was found */
+	if (!vaddr)
+		vaddr = new_vmap_block(order, gfp_mask);
+
+	return vaddr;
+}
+
+static void vb_free(const void *addr, unsigned long size)
+{
+	unsigned long offset;
+	unsigned long vb_idx;
+	unsigned int order;
+	struct vmap_block *vb;
+
+	BUG_ON(offset_in_page(size));
+	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
+
+	flush_cache_vunmap((unsigned long)addr, (unsigned long)addr + size);
+
+	order = get_order(size);
+
+	offset = (unsigned long)addr & (VMAP_BLOCK_SIZE - 1);
+	offset >>= PAGE_SHIFT;
+
+	vb_idx = addr_to_vb_idx((unsigned long)addr);
+	rcu_read_lock();
+	vb = radix_tree_lookup(&vmap_block_tree, vb_idx);
+	rcu_read_unlock();
+	BUG_ON(!vb);
+
+	vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);
+
+	spin_lock(&vb->lock);
+
+	/* Expand dirty range */
+	vb->dirty_min = min(vb->dirty_min, offset);
+	vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));
+
+	vb->dirty += 1UL << order;
+	if (vb->dirty == VMAP_BBMAP_BITS) {
+		BUG_ON(vb->free);
+		spin_unlock(&vb->lock);
+		free_vmap_block(vb);
+	} else
+		spin_unlock(&vb->lock);
+}
+
+/**
+ * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer
+ *
+ * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily
+ * to amortize TLB flushing overheads. What this means is that any page you
+ * have now, may, in a former life, have been mapped into kernel virtual
+ * address by the vmap layer and so there might be some CPUs with TLB entries
+ * still referencing that page (additional to the regular 1:1 kernel mapping).
+ *
+ * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can
+ * be sure that none of the pages we have control over will have any aliases
+ * from the vmap layer.
+ */
+void vm_unmap_aliases(void)
+{
+	unsigned long start = ULONG_MAX, end = 0;
+	int cpu;
+	int flush = 0;
+
+	if (unlikely(!vmap_initialized))
+		return;
+
+	for_each_possible_cpu(cpu) {
+		struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
+		struct vmap_block *vb;
+
+		rcu_read_lock();
+		list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+			spin_lock(&vb->lock);
+			if (vb->dirty) {
+				unsigned long va_start = vb->va->va_start;
+				unsigned long s, e;
+
+				s = va_start + (vb->dirty_min << PAGE_SHIFT);
+				e = va_start + (vb->dirty_max << PAGE_SHIFT);
+
+				start = min(s, start);
+				end   = max(e, end);
+
+				flush = 1;
+			}
+			spin_unlock(&vb->lock);
+		}
+		rcu_read_unlock();
+	}
+
+	__purge_vmap_area_lazy(&start, &end, 1, flush);
+}
+EXPORT_SYMBOL_GPL(vm_unmap_aliases);
+
+/**
+ * vm_unmap_ram - unmap linear kernel address space set up by vm_map_ram
+ * @mem: the pointer returned by vm_map_ram
+ * @count: the count passed to that vm_map_ram call (cannot unmap partial)
+ */
+void vm_unmap_ram(const void *mem, unsigned int count)
+{
+	unsigned long size = count << PAGE_SHIFT;
+	unsigned long addr = (unsigned long)mem;
+
+	BUG_ON(!addr);
+	BUG_ON(addr < VMALLOC_START);
+	BUG_ON(addr > VMALLOC_END);
+	BUG_ON(addr & (PAGE_SIZE-1));
+
+	debug_check_no_locks_freed(mem, size);
+	vmap_debug_free_range(addr, addr+size);
+
+	if (likely(count <= VMAP_MAX_ALLOC))
+		vb_free(mem, size);
+	else
+		free_unmap_vmap_area_addr(addr);
+}
+EXPORT_SYMBOL(vm_unmap_ram);
+
+/**
+ * vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
+ * @pages: an array of pointers to the pages to be mapped
+ * @count: number of pages
+ * @node: prefer to allocate data structures on this node
+ * @prot: memory protection to use. PAGE_KERNEL for regular RAM
+ *
+ * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
+ * faster than vmap so it's good.  But if you mix long-life and short-life
+ * objects with vm_map_ram(), it could consume lots of address space through
+ * fragmentation (especially on a 32bit machine).  You could see failures in
+ * the end.  Please use this function for short-lived objects.
+ *
+ * Returns: a pointer to the address that has been mapped, or %NULL on failure
+ */
+void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
+{
+	unsigned long size = count << PAGE_SHIFT;
+	unsigned long addr;
+	void *mem;
+
+	if (likely(count <= VMAP_MAX_ALLOC)) {
+		mem = vb_alloc(size, GFP_KERNEL);
+		if (IS_ERR(mem))
+			return NULL;
+		addr = (unsigned long)mem;
+	} else {
+		struct vmap_area *va;
+		va = alloc_vmap_area(size, PAGE_SIZE,
+				VMALLOC_START, VMALLOC_END, node, GFP_KERNEL);
+		if (IS_ERR(va))
+			return NULL;
+
+		addr = va->va_start;
+		mem = (void *)addr;
+	}
+	if (vmap_page_range(addr, addr + size, prot, pages) < 0) {
+		vm_unmap_ram(mem, count);
+		return NULL;
+	}
+	return mem;
+}
+EXPORT_SYMBOL(vm_map_ram);
+
+static struct vm_struct *vmlist __initdata;
+/**
+ * vm_area_add_early - add vmap area early during boot
+ * @vm: vm_struct to add
+ *
+ * This function is used to add fixed kernel vm area to vmlist before
+ * vmalloc_init() is called.  @vm->addr, @vm->size, and @vm->flags
+ * should contain proper values and the other fields should be zero.
+ *
+ * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
+ */
+void __init vm_area_add_early(struct vm_struct *vm)
+{
+	struct vm_struct *tmp, **p;
+
+	BUG_ON(vmap_initialized);
+	for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
+		if (tmp->addr >= vm->addr) {
+			BUG_ON(tmp->addr < vm->addr + vm->size);
+			break;
+		} else
+			BUG_ON(tmp->addr + tmp->size > vm->addr);
+	}
+	vm->next = *p;
+	*p = vm;
+}
+
+/**
+ * vm_area_register_early - register vmap area early during boot
+ * @vm: vm_struct to register
+ * @align: requested alignment
+ *
+ * This function is used to register kernel vm area before
+ * vmalloc_init() is called.  @vm->size and @vm->flags should contain
+ * proper values on entry and other fields should be zero.  On return,
+ * vm->addr contains the allocated address.
+ *
+ * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
+ */
+void __init vm_area_register_early(struct vm_struct *vm, size_t align)
+{
+	static size_t vm_init_off __initdata;
+	unsigned long addr;
+
+	addr = ALIGN(VMALLOC_START + vm_init_off, align);
+	vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;
+
+	vm->addr = (void *)addr;
+
+	vm_area_add_early(vm);
+}
+
+void __init vmalloc_init(void)
+{
+	struct vmap_area *va;
+	struct vm_struct *tmp;
+	int i;
+
+	for_each_possible_cpu(i) {
+		struct vmap_block_queue *vbq;
+		struct vfree_deferred *p;
+
+		vbq = &per_cpu(vmap_block_queue, i);
+		spin_lock_init(&vbq->lock);
+		INIT_LIST_HEAD(&vbq->free);
+		p = &per_cpu(vfree_deferred, i);
+		init_llist_head(&p->list);
+		INIT_WORK(&p->wq, free_work);
+	}
+
+	/* Import existing vmlist entries. */
+	for (tmp = vmlist; tmp; tmp = tmp->next) {
+		va = kzalloc(sizeof(struct vmap_area), GFP_NOWAIT);
+		va->flags = VM_VM_AREA;
+		va->va_start = (unsigned long)tmp->addr;
+		va->va_end = va->va_start + tmp->size;
+		va->vm = tmp;
+		__insert_vmap_area(va);
+	}
+
+	vmap_area_pcpu_hole = VMALLOC_END;
+
+	vmap_initialized = true;
+}
+
+/**
+ * map_kernel_range_noflush - map kernel VM area with the specified pages
+ * @addr: start of the VM area to map
+ * @size: size of the VM area to map
+ * @prot: page protection flags to use
+ * @pages: pages to map
+ *
+ * Map PFN_UP(@size) pages at @addr.  The VM area @addr and @size
+ * specify should have been allocated using get_vm_area() and its
+ * friends.
+ *
+ * NOTE:
+ * This function does NOT do any cache flushing.  The caller is
+ * responsible for calling flush_cache_vmap() on to-be-mapped areas
+ * before calling this function.
+ *
+ * RETURNS:
+ * The number of pages mapped on success, -errno on failure.
+ */
+int map_kernel_range_noflush(unsigned long addr, unsigned long size,
+			     pgprot_t prot, struct page **pages)
+{
+	return vmap_page_range_noflush(addr, addr + size, prot, pages);
+}
+
+/**
+ * unmap_kernel_range_noflush - unmap kernel VM area
+ * @addr: start of the VM area to unmap
+ * @size: size of the VM area to unmap
+ *
+ * Unmap PFN_UP(@size) pages at @addr.  The VM area @addr and @size
+ * specify should have been allocated using get_vm_area() and its
+ * friends.
+ *
+ * NOTE:
+ * This function does NOT do any cache flushing.  The caller is
+ * responsible for calling flush_cache_vunmap() on to-be-mapped areas
+ * before calling this function and flush_tlb_kernel_range() after.
+ */
+void unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
+{
+	vunmap_page_range(addr, addr + size);
+}
+EXPORT_SYMBOL_GPL(unmap_kernel_range_noflush);
+
+/**
+ * unmap_kernel_range - unmap kernel VM area and flush cache and TLB
+ * @addr: start of the VM area to unmap
+ * @size: size of the VM area to unmap
+ *
+ * Similar to unmap_kernel_range_noflush() but flushes vcache before
+ * the unmapping and tlb after.
+ */
+void unmap_kernel_range(unsigned long addr, unsigned long size)
+{
+	unsigned long end = addr + size;
+
+	flush_cache_vunmap(addr, end);
+	vunmap_page_range(addr, end);
+	flush_tlb_kernel_range(addr, end);
+}
+EXPORT_SYMBOL_GPL(unmap_kernel_range);
+
+int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page **pages)
+{
+	unsigned long addr = (unsigned long)area->addr;
+	unsigned long end = addr + get_vm_area_size(area);
+	int err;
+
+	err = vmap_page_range(addr, end, prot, pages);
+
+	return err > 0 ? 0 : err;
+}
+EXPORT_SYMBOL_GPL(map_vm_area);
+
+static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
+			      unsigned long flags, const void *caller)
+{
+	spin_lock(&vmap_area_lock);
+	vm->flags = flags;
+	vm->addr = (void *)va->va_start;
+	vm->size = va->va_end - va->va_start;
+	vm->caller = caller;
+	va->vm = vm;
+	va->flags |= VM_VM_AREA;
+	spin_unlock(&vmap_area_lock);
+}
+
+static void clear_vm_uninitialized_flag(struct vm_struct *vm)
+{
+	/*
+	 * Before removing VM_UNINITIALIZED,
+	 * we should make sure that vm has proper values.
+	 * Pair with smp_rmb() in show_numa_info().
+	 */
+	smp_wmb();
+	vm->flags &= ~VM_UNINITIALIZED;
+}
+
+static struct vm_struct *__get_vm_area_node(unsigned long size,
+		unsigned long align, unsigned long flags, unsigned long start,
+		unsigned long end, int node, gfp_t gfp_mask, const void *caller)
+{
+	struct vmap_area *va;
+	struct vm_struct *area;
+
+	BUG_ON(in_interrupt());
+	if (flags & VM_IOREMAP)
+		align = 1ul << clamp_t(int, fls_long(size),
+				       PAGE_SHIFT, IOREMAP_MAX_ORDER);
+
+	size = PAGE_ALIGN(size);
+	if (unlikely(!size))
+		return NULL;
+
+	area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
+	if (unlikely(!area))
+		return NULL;
+
+	if (!(flags & VM_NO_GUARD))
+		size += PAGE_SIZE;
+
+	va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
+	if (IS_ERR(va)) {
+		kfree(area);
+		return NULL;
+	}
+
+	setup_vmalloc_vm(area, va, flags, caller);
+
+	return area;
+}
+
+struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
+				unsigned long start, unsigned long end)
+{
+	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
+				  GFP_KERNEL, __builtin_return_address(0));
+}
+EXPORT_SYMBOL_GPL(__get_vm_area);
+
+struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
+				       unsigned long start, unsigned long end,
+				       const void *caller)
+{
+	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
+				  GFP_KERNEL, caller);
+}
+
+/**
+ *	get_vm_area  -  reserve a contiguous kernel virtual area
+ *	@size:		size of the area
+ *	@flags:		%VM_IOREMAP for I/O mappings or VM_ALLOC
+ *
+ *	Search an area of @size in the kernel virtual mapping area,
+ *	and reserved it for out purposes.  Returns the area descriptor
+ *	on success or %NULL on failure.
+ */
+struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
+{
+	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
+				  NUMA_NO_NODE, GFP_KERNEL,
+				  __builtin_return_address(0));
+}
+
+struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
+				const void *caller)
+{
+	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
+				  NUMA_NO_NODE, GFP_KERNEL, caller);
+}
+
+/**
+ *	find_vm_area  -  find a continuous kernel virtual area
+ *	@addr:		base address
+ *
+ *	Search for the kernel VM area starting at @addr, and return it.
+ *	It is up to the caller to do all required locking to keep the returned
+ *	pointer valid.
+ */
+struct vm_struct *find_vm_area(const void *addr)
+{
+	struct vmap_area *va;
+
+	va = find_vmap_area((unsigned long)addr);
+	if (va && va->flags & VM_VM_AREA)
+		return va->vm;
+
+	return NULL;
+}
+
+/**
+ *	remove_vm_area  -  find and remove a continuous kernel virtual area
+ *	@addr:		base address
+ *
+ *	Search for the kernel VM area starting at @addr, and remove it.
+ *	This function returns the found VM area, but using it is NOT safe
+ *	on SMP machines, except for its size or flags.
+ */
+struct vm_struct *remove_vm_area(const void *addr)
+{
+	struct vmap_area *va;
+
+	va = find_vmap_area((unsigned long)addr);
+	if (va && va->flags & VM_VM_AREA) {
+		struct vm_struct *vm = va->vm;
+
+		spin_lock(&vmap_area_lock);
+		va->vm = NULL;
+		va->flags &= ~VM_VM_AREA;
+		spin_unlock(&vmap_area_lock);
+
+		vmap_debug_free_range(va->va_start, va->va_end);
+		kasan_free_shadow(vm);
+		free_unmap_vmap_area(va);
+
+		return vm;
+	}
+	return NULL;
+}
+
+static void __vunmap(const void *addr, int deallocate_pages)
+{
+	struct vm_struct *area;
+
+	if (!addr)
+		return;
+
+	if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",
+			addr))
+		return;
+
+	area = remove_vm_area(addr);
+	if (unlikely(!area)) {
+		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
+				addr);
+		return;
+	}
+
+	debug_check_no_locks_freed(addr, get_vm_area_size(area));
+	debug_check_no_obj_freed(addr, get_vm_area_size(area));
+
+	if (deallocate_pages) {
+		int i;
+
+		for (i = 0; i < area->nr_pages; i++) {
+			struct page *page = area->pages[i];
+
+			BUG_ON(!page);
+			__free_page(page);
+		}
+
+		if (area->flags & VM_VPAGES)
+			vfree(area->pages);
+		else
+			kfree(area->pages);
+	}
+
+	kfree(area);
+	return;
+}
+ 
+/**
+ *	vfree  -  release memory allocated by vmalloc()
+ *	@addr:		memory base address
+ *
+ *	Free the virtually continuous memory area starting at @addr, as
+ *	obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
+ *	NULL, no operation is performed.
+ *
+ *	Must not be called in NMI context (strictly speaking, only if we don't
+ *	have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
+ *	conventions for vfree() arch-depenedent would be a really bad idea)
+ *
+ *	NOTE: assumes that the object at *addr has a size >= sizeof(llist_node)
+ */
+void vfree(const void *addr)
+{
+	BUG_ON(in_nmi());
+
+	kmemleak_free(addr);
+
+	if (!addr)
+		return;
+	if (unlikely(in_interrupt())) {
+		struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred);
+		if (llist_add((struct llist_node *)addr, &p->list))
+			schedule_work(&p->wq);
+	} else
+		__vunmap(addr, 1);
+}
+EXPORT_SYMBOL(vfree);
+
+/**
+ *	vunmap  -  release virtual mapping obtained by vmap()
+ *	@addr:		memory base address
+ *
+ *	Free the virtually contiguous memory area starting at @addr,
+ *	which was created from the page array passed to vmap().
+ *
+ *	Must not be called in interrupt context.
+ */
+void vunmap(const void *addr)
+{
+	BUG_ON(in_interrupt());
+	might_sleep();
+	if (addr)
+		__vunmap(addr, 0);
+}
+EXPORT_SYMBOL(vunmap);
+
+/**
+ *	vmap  -  map an array of pages into virtually contiguous space
+ *	@pages:		array of page pointers
+ *	@count:		number of pages to map
+ *	@flags:		vm_area->flags
+ *	@prot:		page protection for the mapping
+ *
+ *	Maps @count pages from @pages into contiguous kernel virtual
+ *	space.
+ */
+void *vmap(struct page **pages, unsigned int count,
+		unsigned long flags, pgprot_t prot)
+{
+	struct vm_struct *area;
+
+	might_sleep();
+
+	if (count > totalram_pages)
+		return NULL;
+
+	area = get_vm_area_caller((count << PAGE_SHIFT), flags,
+					__builtin_return_address(0));
+	if (!area)
+		return NULL;
+
+	if (map_vm_area(area, prot, pages)) {
+		vunmap(area->addr);
+		return NULL;
+	}
+
+	return area->addr;
+}
+EXPORT_SYMBOL(vmap);
+
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+			    gfp_t gfp_mask, pgprot_t prot,
+			    int node, const void *caller);
+static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
+				 pgprot_t prot, int node)
+{
+	const int order = 0;
+	struct page **pages;
+	unsigned int nr_pages, array_size, i;
+	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
+	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
+
+	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
+	array_size = (nr_pages * sizeof(struct page *));
+
+	area->nr_pages = nr_pages;
+	/* Please note that the recursion is strictly bounded. */
+	if (array_size > PAGE_SIZE) {
+		pages = __vmalloc_node(array_size, 1, nested_gfp|__GFP_HIGHMEM,
+				PAGE_KERNEL, node, area->caller);
+		area->flags |= VM_VPAGES;
+	} else {
+		pages = kmalloc_node(array_size, nested_gfp, node);
+	}
+	area->pages = pages;
+	if (!area->pages) {
+		remove_vm_area(area->addr);
+		kfree(area);
+		return NULL;
+	}
+
+	for (i = 0; i < area->nr_pages; i++) {
+		struct page *page;
+
+		if (node == NUMA_NO_NODE)
+			page = alloc_page(alloc_mask);
+		else
+			page = alloc_pages_node(node, alloc_mask, order);
+
+		if (unlikely(!page)) {
+			/* Successfully allocated i pages, free them in __vunmap() */
+			area->nr_pages = i;
+			goto fail;
+		}
+		area->pages[i] = page;
+		if (gfpflags_allow_blocking(gfp_mask))
+			cond_resched();
+	}
+
+	if (map_vm_area(area, prot, pages))
+		goto fail;
+	return area->addr;
+
+fail:
+	warn_alloc_failed(gfp_mask, order,
+			  "vmalloc: allocation failure, allocated %ld of %ld bytes\n",
+			  (area->nr_pages*PAGE_SIZE), area->size);
+	vfree(area->addr);
+	return NULL;
+}
+
+/**
+ *	__vmalloc_node_range  -  allocate virtually contiguous memory
+ *	@size:		allocation size
+ *	@align:		desired alignment
+ *	@start:		vm area range start
+ *	@end:		vm area range end
+ *	@gfp_mask:	flags for the page level allocator
+ *	@prot:		protection mask for the allocated pages
+ *	@vm_flags:	additional vm area flags (e.g. %VM_NO_GUARD)
+ *	@node:		node to use for allocation or NUMA_NO_NODE
+ *	@caller:	caller's return address
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator with @gfp_mask flags.  Map them into contiguous
+ *	kernel virtual space, using a pagetable protection of @prot.
+ */
+void *__vmalloc_node_range(unsigned long size, unsigned long align,
+			unsigned long start, unsigned long end, gfp_t gfp_mask,
+			pgprot_t prot, unsigned long vm_flags, int node,
+			const void *caller)
+{
+	struct vm_struct *area;
+	void *addr;
+	unsigned long real_size = size;
+
+	size = PAGE_ALIGN(size);
+	if (!size || (size >> PAGE_SHIFT) > totalram_pages)
+		goto fail;
+
+	area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNINITIALIZED |
+				vm_flags, start, end, node, gfp_mask, caller);
+	if (!area)
+		goto fail;
+
+	addr = __vmalloc_area_node(area, gfp_mask, prot, node);
+	if (!addr)
+		return NULL;
+
+	/*
+	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
+	 * flag. It means that vm_struct is not fully initialized.
+	 * Now, it is fully initialized, so remove this flag here.
+	 */
+	clear_vm_uninitialized_flag(area);
+
+	/*
+	 * A ref_count = 2 is needed because vm_struct allocated in
+	 * __get_vm_area_node() contains a reference to the virtual address of
+	 * the vmalloc'ed block.
+	 */
+	kmemleak_alloc(addr, real_size, 2, gfp_mask);
+
+	return addr;
+
+fail:
+	warn_alloc_failed(gfp_mask, 0,
+			  "vmalloc: allocation failure: %lu bytes\n",
+			  real_size);
+	return NULL;
+}
+
+/**
+ *	__vmalloc_node  -  allocate virtually contiguous memory
+ *	@size:		allocation size
+ *	@align:		desired alignment
+ *	@gfp_mask:	flags for the page level allocator
+ *	@prot:		protection mask for the allocated pages
+ *	@node:		node to use for allocation or NUMA_NO_NODE
+ *	@caller:	caller's return address
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator with @gfp_mask flags.  Map them into contiguous
+ *	kernel virtual space, using a pagetable protection of @prot.
+ */
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+			    gfp_t gfp_mask, pgprot_t prot,
+			    int node, const void *caller)
+{
+	return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
+				gfp_mask, prot, 0, node, caller);
+}
+
+void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
+{
+	return __vmalloc_node(size, 1, gfp_mask, prot, NUMA_NO_NODE,
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(__vmalloc);
+
+static inline void *__vmalloc_node_flags(unsigned long size,
+					int node, gfp_t flags)
+{
+	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
+					node, __builtin_return_address(0));
+}
+
+/**
+ *	vmalloc  -  allocate virtually contiguous memory
+ *	@size:		allocation size
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vmalloc(unsigned long size)
+{
+	return __vmalloc_node_flags(size, NUMA_NO_NODE,
+				    GFP_KERNEL | __GFP_HIGHMEM);
+}
+EXPORT_SYMBOL(vmalloc);
+
+/**
+ *	vzalloc - allocate virtually contiguous memory with zero fill
+ *	@size:	allocation size
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *	The memory allocated is set to zero.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vzalloc(unsigned long size)
+{
+	return __vmalloc_node_flags(size, NUMA_NO_NODE,
+				GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
+}
+EXPORT_SYMBOL(vzalloc);
+
+/**
+ * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
+ * @size: allocation size
+ *
+ * The resulting memory area is zeroed so it can be mapped to userspace
+ * without leaking data.
+ */
+void *vmalloc_user(unsigned long size)
+{
+	struct vm_struct *area;
+	void *ret;
+
+	ret = __vmalloc_node(size, SHMLBA,
+			     GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+			     PAGE_KERNEL, NUMA_NO_NODE,
+			     __builtin_return_address(0));
+	if (ret) {
+		area = find_vm_area(ret);
+		area->flags |= VM_USERMAP;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(vmalloc_user);
+
+/**
+ *	vmalloc_node  -  allocate memory on a specific node
+ *	@size:		allocation size
+ *	@node:		numa node
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vmalloc_node(unsigned long size, int node)
+{
+	return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
+					node, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_node);
+
+/**
+ * vzalloc_node - allocate memory on a specific node with zero fill
+ * @size:	allocation size
+ * @node:	numa node
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ * The memory allocated is set to zero.
+ *
+ * For tight control over page level allocator and protection flags
+ * use __vmalloc_node() instead.
+ */
+void *vzalloc_node(unsigned long size, int node)
+{
+	return __vmalloc_node_flags(size, node,
+			 GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
+}
+EXPORT_SYMBOL(vzalloc_node);
+
+#ifndef PAGE_KERNEL_EXEC
+# define PAGE_KERNEL_EXEC PAGE_KERNEL
+#endif
+
+/**
+ *	vmalloc_exec  -  allocate virtually contiguous, executable memory
+ *	@size:		allocation size
+ *
+ *	Kernel-internal function to allocate enough pages to cover @size
+ *	the page level allocator and map them into contiguous and
+ *	executable kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+
+void *vmalloc_exec(unsigned long size)
+{
+	return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
+			      NUMA_NO_NODE, __builtin_return_address(0));
+}
+
+#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
+#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
+#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
+#define GFP_VMALLOC32 GFP_DMA | GFP_KERNEL
+#else
+#define GFP_VMALLOC32 GFP_KERNEL
+#endif
+
+/**
+ *	vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
+ *	@size:		allocation size
+ *
+ *	Allocate enough 32bit PA addressable pages to cover @size from the
+ *	page level allocator and map them into contiguous kernel virtual space.
+ */
+void *vmalloc_32(unsigned long size)
+{
+	return __vmalloc_node(size, 1, GFP_VMALLOC32, PAGE_KERNEL,
+			      NUMA_NO_NODE, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_32);
+
+/**
+ * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
+ *	@size:		allocation size
+ *
+ * The resulting memory area is 32bit addressable and zeroed so it can be
+ * mapped to userspace without leaking data.
+ */
+void *vmalloc_32_user(unsigned long size)
+{
+	struct vm_struct *area;
+	void *ret;
+
+	ret = __vmalloc_node(size, 1, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
+			     NUMA_NO_NODE, __builtin_return_address(0));
+	if (ret) {
+		area = find_vm_area(ret);
+		area->flags |= VM_USERMAP;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(vmalloc_32_user);
+
+/*
+ * small helper routine , copy contents to buf from addr.
+ * If the page is not present, fill zero.
+ */
+
+static int aligned_vread(char *buf, char *addr, unsigned long count)
+{
+	struct page *p;
+	int copied = 0;
+
+	while (count) {
+		unsigned long offset, length;
+
+		offset = offset_in_page(addr);
+		length = PAGE_SIZE - offset;
+		if (length > count)
+			length = count;
+		p = vmalloc_to_page(addr);
+		/*
+		 * To do safe access to this _mapped_ area, we need
+		 * lock. But adding lock here means that we need to add
+		 * overhead of vmalloc()/vfree() calles for this _debug_
+		 * interface, rarely used. Instead of that, we'll use
+		 * kmap() and get small overhead in this access function.
+		 */
+		if (p) {
+			/*
+			 * we can expect USER0 is not used (see vread/vwrite's
+			 * function description)
+			 */
+			void *map = kmap_atomic(p);
+			memcpy(buf, map + offset, length);
+			kunmap_atomic(map);
+		} else
+			memset(buf, 0, length);
+
+		addr += length;
+		buf += length;
+		copied += length;
+		count -= length;
+	}
+	return copied;
+}
+
+static int aligned_vwrite(char *buf, char *addr, unsigned long count)
+{
+	struct page *p;
+	int copied = 0;
+
+	while (count) {
+		unsigned long offset, length;
+
+		offset = offset_in_page(addr);
+		length = PAGE_SIZE - offset;
+		if (length > count)
+			length = count;
+		p = vmalloc_to_page(addr);
+		/*
+		 * To do safe access to this _mapped_ area, we need
+		 * lock. But adding lock here means that we need to add
+		 * overhead of vmalloc()/vfree() calles for this _debug_
+		 * interface, rarely used. Instead of that, we'll use
+		 * kmap() and get small overhead in this access function.
+		 */
+		if (p) {
+			/*
+			 * we can expect USER0 is not used (see vread/vwrite's
+			 * function description)
+			 */
+			void *map = kmap_atomic(p);
+			memcpy(map + offset, buf, length);
+			kunmap_atomic(map);
+		}
+		addr += length;
+		buf += length;
+		copied += length;
+		count -= length;
+	}
+	return copied;
+}
+
+/**
+ *	vread() -  read vmalloc area in a safe way.
+ *	@buf:		buffer for reading data
+ *	@addr:		vm address.
+ *	@count:		number of bytes to be read.
+ *
+ *	Returns # of bytes which addr and buf should be increased.
+ *	(same number to @count). Returns 0 if [addr...addr+count) doesn't
+ *	includes any intersect with alive vmalloc area.
+ *
+ *	This function checks that addr is a valid vmalloc'ed area, and
+ *	copy data from that area to a given buffer. If the given memory range
+ *	of [addr...addr+count) includes some valid address, data is copied to
+ *	proper area of @buf. If there are memory holes, they'll be zero-filled.
+ *	IOREMAP area is treated as memory hole and no copy is done.
+ *
+ *	If [addr...addr+count) doesn't includes any intersects with alive
+ *	vm_struct area, returns 0. @buf should be kernel's buffer.
+ *
+ *	Note: In usual ops, vread() is never necessary because the caller
+ *	should know vmalloc() area is valid and can use memcpy().
+ *	This is for routines which have to access vmalloc area without
+ *	any informaion, as /dev/kmem.
+ *
+ */
+
+long vread(char *buf, char *addr, unsigned long count)
+{
+	struct vmap_area *va;
+	struct vm_struct *vm;
+	char *vaddr, *buf_start = buf;
+	unsigned long buflen = count;
+	unsigned long n;
+
+	/* Don't allow overflow */
+	if ((unsigned long) addr + count < count)
+		count = -(unsigned long) addr;
+
+	spin_lock(&vmap_area_lock);
+	list_for_each_entry(va, &vmap_area_list, list) {
+		if (!count)
+			break;
+
+		if (!(va->flags & VM_VM_AREA))
+			continue;
+
+		vm = va->vm;
+		vaddr = (char *) vm->addr;
+		if (addr >= vaddr + get_vm_area_size(vm))
+			continue;
+		while (addr < vaddr) {
+			if (count == 0)
+				goto finished;
+			*buf = '\0';
+			buf++;
+			addr++;
+			count--;
+		}
+		n = vaddr + get_vm_area_size(vm) - addr;
+		if (n > count)
+			n = count;
+		if (!(vm->flags & VM_IOREMAP))
+			aligned_vread(buf, addr, n);
+		else /* IOREMAP area is treated as memory hole */
+			memset(buf, 0, n);
+		buf += n;
+		addr += n;
+		count -= n;
+	}
+finished:
+	spin_unlock(&vmap_area_lock);
+
+	if (buf == buf_start)
+		return 0;
+	/* zero-fill memory holes */
+	if (buf != buf_start + buflen)
+		memset(buf, 0, buflen - (buf - buf_start));
+
+	return buflen;
+}
+
+/**
+ *	vwrite() -  write vmalloc area in a safe way.
+ *	@buf:		buffer for source data
+ *	@addr:		vm address.
+ *	@count:		number of bytes to be read.
+ *
+ *	Returns # of bytes which addr and buf should be incresed.
+ *	(same number to @count).
+ *	If [addr...addr+count) doesn't includes any intersect with valid
+ *	vmalloc area, returns 0.
+ *
+ *	This function checks that addr is a valid vmalloc'ed area, and
+ *	copy data from a buffer to the given addr. If specified range of
+ *	[addr...addr+count) includes some valid address, data is copied from
+ *	proper area of @buf. If there are memory holes, no copy to hole.
+ *	IOREMAP area is treated as memory hole and no copy is done.
+ *
+ *	If [addr...addr+count) doesn't includes any intersects with alive
+ *	vm_struct area, returns 0. @buf should be kernel's buffer.
+ *
+ *	Note: In usual ops, vwrite() is never necessary because the caller
+ *	should know vmalloc() area is valid and can use memcpy().
+ *	This is for routines which have to access vmalloc area without
+ *	any informaion, as /dev/kmem.
+ */
+
+long vwrite(char *buf, char *addr, unsigned long count)
+{
+	struct vmap_area *va;
+	struct vm_struct *vm;
+	char *vaddr;
+	unsigned long n, buflen;
+	int copied = 0;
+
+	/* Don't allow overflow */
+	if ((unsigned long) addr + count < count)
+		count = -(unsigned long) addr;
+	buflen = count;
+
+	spin_lock(&vmap_area_lock);
+	list_for_each_entry(va, &vmap_area_list, list) {
+		if (!count)
+			break;
+
+		if (!(va->flags & VM_VM_AREA))
+			continue;
+
+		vm = va->vm;
+		vaddr = (char *) vm->addr;
+		if (addr >= vaddr + get_vm_area_size(vm))
+			continue;
+		while (addr < vaddr) {
+			if (count == 0)
+				goto finished;
+			buf++;
+			addr++;
+			count--;
+		}
+		n = vaddr + get_vm_area_size(vm) - addr;
+		if (n > count)
+			n = count;
+		if (!(vm->flags & VM_IOREMAP)) {
+			aligned_vwrite(buf, addr, n);
+			copied++;
+		}
+		buf += n;
+		addr += n;
+		count -= n;
+	}
+finished:
+	spin_unlock(&vmap_area_lock);
+	if (!copied)
+		return 0;
+	return buflen;
+}
+
+/**
+ *	remap_vmalloc_range_partial  -  map vmalloc pages to userspace
+ *	@vma:		vma to cover
+ *	@uaddr:		target user address to start at
+ *	@kaddr:		virtual address of vmalloc kernel memory
+ *	@size:		size of map area
+ *
+ *	Returns:	0 for success, -Exxx on failure
+ *
+ *	This function checks that @kaddr is a valid vmalloc'ed area,
+ *	and that it is big enough to cover the range starting at
+ *	@uaddr in @vma. Will return failure if that criteria isn't
+ *	met.
+ *
+ *	Similar to remap_pfn_range() (see mm/memory.c)
+ */
+int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
+				void *kaddr, unsigned long size)
+{
+	struct vm_struct *area;
+
+	size = PAGE_ALIGN(size);
+
+	if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))
+		return -EINVAL;
+
+	area = find_vm_area(kaddr);
+	if (!area)
+		return -EINVAL;
+
+	if (!(area->flags & VM_USERMAP))
+		return -EINVAL;
+
+	if (kaddr + size > area->addr + area->size)
+		return -EINVAL;
+
+	do {
+		struct page *page = vmalloc_to_page(kaddr);
+		int ret;
+
+		ret = vm_insert_page(vma, uaddr, page);
+		if (ret)
+			return ret;
+
+		uaddr += PAGE_SIZE;
+		kaddr += PAGE_SIZE;
+		size -= PAGE_SIZE;
+	} while (size > 0);
+
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+
+	return 0;
+}
+EXPORT_SYMBOL(remap_vmalloc_range_partial);
+
+/**
+ *	remap_vmalloc_range  -  map vmalloc pages to userspace
+ *	@vma:		vma to cover (map full range of vma)
+ *	@addr:		vmalloc memory
+ *	@pgoff:		number of pages into addr before first page to map
+ *
+ *	Returns:	0 for success, -Exxx on failure
+ *
+ *	This function checks that addr is a valid vmalloc'ed area, and
+ *	that it is big enough to cover the vma. Will return failure if
+ *	that criteria isn't met.
+ *
+ *	Similar to remap_pfn_range() (see mm/memory.c)
+ */
+int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
+						unsigned long pgoff)
+{
+	return remap_vmalloc_range_partial(vma, vma->vm_start,
+					   addr + (pgoff << PAGE_SHIFT),
+					   vma->vm_end - vma->vm_start);
+}
+EXPORT_SYMBOL(remap_vmalloc_range);
+
+/*
+ * Implement a stub for vmalloc_sync_all() if the architecture chose not to
+ * have one.
+ */
+void __weak vmalloc_sync_all(void)
+{
+}
+
+
+static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
+{
+	pte_t ***p = data;
+
+	if (p) {
+		*(*p) = pte;
+		(*p)++;
+	}
+	return 0;
+}
+
+/**
+ *	alloc_vm_area - allocate a range of kernel address space
+ *	@size:		size of the area
+ *	@ptes:		returns the PTEs for the address space
+ *
+ *	Returns:	NULL on failure, vm_struct on success
+ *
+ *	This function reserves a range of kernel address space, and
+ *	allocates pagetables to map that range.  No actual mappings
+ *	are created.
+ *
+ *	If @ptes is non-NULL, pointers to the PTEs (in init_mm)
+ *	allocated for the VM area are returned.
+ */
+struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area_caller(size, VM_IOREMAP,
+				__builtin_return_address(0));
+	if (area == NULL)
+		return NULL;
+
+	/*
+	 * This ensures that page tables are constructed for this region
+	 * of kernel virtual address space and mapped into init_mm.
+	 */
+	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
+				size, f, ptes ? &ptes : NULL)) {
+		free_vm_area(area);
+		return NULL;
+	}
+
+	return area;
+}
+EXPORT_SYMBOL_GPL(alloc_vm_area);
+
+void free_vm_area(struct vm_struct *area)
+{
+	struct vm_struct *ret;
+	ret = remove_vm_area(area->addr);
+	BUG_ON(ret != area);
+	kfree(area);
+}
+EXPORT_SYMBOL_GPL(free_vm_area);
+
+#ifdef CONFIG_SMP
+static struct vmap_area *node_to_va(struct rb_node *n)
+{
+	return n ? rb_entry(n, struct vmap_area, rb_node) : NULL;
+}
+
+/**
+ * pvm_find_next_prev - find the next and prev vmap_area surrounding @end
+ * @end: target address
+ * @pnext: out arg for the next vmap_area
+ * @pprev: out arg for the previous vmap_area
+ *
+ * Returns: %true if either or both of next and prev are found,
+ *	    %false if no vmap_area exists
+ *
+ * Find vmap_areas end addresses of which enclose @end.  ie. if not
+ * NULL, *pnext->va_end > @end and *pprev->va_end <= @end.
+ */
+static bool pvm_find_next_prev(unsigned long end,
+			       struct vmap_area **pnext,
+			       struct vmap_area **pprev)
+{
+	struct rb_node *n = vmap_area_root.rb_node;
+	struct vmap_area *va = NULL;
+
+	while (n) {
+		va = rb_entry(n, struct vmap_area, rb_node);
+		if (end < va->va_end)
+			n = n->rb_left;
+		else if (end > va->va_end)
+			n = n->rb_right;
+		else
+			break;
+	}
+
+	if (!va)
+		return false;
+
+	if (va->va_end > end) {
+		*pnext = va;
+		*pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+	} else {
+		*pprev = va;
+		*pnext = node_to_va(rb_next(&(*pprev)->rb_node));
+	}
+	return true;
+}
+
+/**
+ * pvm_determine_end - find the highest aligned address between two vmap_areas
+ * @pnext: in/out arg for the next vmap_area
+ * @pprev: in/out arg for the previous vmap_area
+ * @align: alignment
+ *
+ * Returns: determined end address
+ *
+ * Find the highest aligned address between *@pnext and *@pprev below
+ * VMALLOC_END.  *@pnext and *@pprev are adjusted so that the aligned
+ * down address is between the end addresses of the two vmap_areas.
+ *
+ * Please note that the address returned by this function may fall
+ * inside *@pnext vmap_area.  The caller is responsible for checking
+ * that.
+ */
+static unsigned long pvm_determine_end(struct vmap_area **pnext,
+				       struct vmap_area **pprev,
+				       unsigned long align)
+{
+	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
+	unsigned long addr;
+
+	if (*pnext)
+		addr = min((*pnext)->va_start & ~(align - 1), vmalloc_end);
+	else
+		addr = vmalloc_end;
+
+	while (*pprev && (*pprev)->va_end > addr) {
+		*pnext = *pprev;
+		*pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+	}
+
+	return addr;
+}
+
+/**
+ * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
+ * @offsets: array containing offset of each area
+ * @sizes: array containing size of each area
+ * @nr_vms: the number of areas to allocate
+ * @align: alignment, all entries in @offsets and @sizes must be aligned to this
+ *
+ * Returns: kmalloc'd vm_struct pointer array pointing to allocated
+ *	    vm_structs on success, %NULL on failure
+ *
+ * Percpu allocator wants to use congruent vm areas so that it can
+ * maintain the offsets among percpu areas.  This function allocates
+ * congruent vmalloc areas for it with GFP_KERNEL.  These areas tend to
+ * be scattered pretty far, distance between two areas easily going up
+ * to gigabytes.  To avoid interacting with regular vmallocs, these
+ * areas are allocated from top.
+ *
+ * Despite its complicated look, this allocator is rather simple.  It
+ * does everything top-down and scans areas from the end looking for
+ * matching slot.  While scanning, if any of the areas overlaps with
+ * existing vmap_area, the base address is pulled down to fit the
+ * area.  Scanning is repeated till all the areas fit and then all
+ * necessary data structres are inserted and the result is returned.
+ */
+struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
+				     const size_t *sizes, int nr_vms,
+				     size_t align)
+{
+	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
+	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
+	struct vmap_area **vas, *prev, *next;
+	struct vm_struct **vms;
+	int area, area2, last_area, term_area;
+	unsigned long base, start, end, last_end;
+	bool purged = false;
+
+	/* verify parameters and allocate data structures */
+	BUG_ON(offset_in_page(align) || !is_power_of_2(align));
+	for (last_area = 0, area = 0; area < nr_vms; area++) {
+		start = offsets[area];
+		end = start + sizes[area];
+
+		/* is everything aligned properly? */
+		BUG_ON(!IS_ALIGNED(offsets[area], align));
+		BUG_ON(!IS_ALIGNED(sizes[area], align));
+
+		/* detect the area with the highest address */
+		if (start > offsets[last_area])
+			last_area = area;
+
+		for (area2 = 0; area2 < nr_vms; area2++) {
+			unsigned long start2 = offsets[area2];
+			unsigned long end2 = start2 + sizes[area2];
+
+			if (area2 == area)
+				continue;
+
+			BUG_ON(start2 >= start && start2 < end);
+			BUG_ON(end2 <= end && end2 > start);
+		}
+	}
+	last_end = offsets[last_area] + sizes[last_area];
+
+	if (vmalloc_end - vmalloc_start < last_end) {
+		WARN_ON(true);
+		return NULL;
+	}
+
+	vms = kcalloc(nr_vms, sizeof(vms[0]), GFP_KERNEL);
+	vas = kcalloc(nr_vms, sizeof(vas[0]), GFP_KERNEL);
+	if (!vas || !vms)
+		goto err_free2;
+
+	for (area = 0; area < nr_vms; area++) {
+		vas[area] = kzalloc(sizeof(struct vmap_area), GFP_KERNEL);
+		vms[area] = kzalloc(sizeof(struct vm_struct), GFP_KERNEL);
+		if (!vas[area] || !vms[area])
+			goto err_free;
+	}
+retry:
+	spin_lock(&vmap_area_lock);
+
+	/* start scanning - we scan from the top, begin with the last area */
+	area = term_area = last_area;
+	start = offsets[area];
+	end = start + sizes[area];
+
+	if (!pvm_find_next_prev(vmap_area_pcpu_hole, &next, &prev)) {
+		base = vmalloc_end - last_end;
+		goto found;
+	}
+	base = pvm_determine_end(&next, &prev, align) - end;
+
+	while (true) {
+		BUG_ON(next && next->va_end <= base + end);
+		BUG_ON(prev && prev->va_end > base + end);
+
+		/*
+		 * base might have underflowed, add last_end before
+		 * comparing.
+		 */
+		if (base + last_end < vmalloc_start + last_end) {
+			spin_unlock(&vmap_area_lock);
+			if (!purged) {
+				purge_vmap_area_lazy();
+				purged = true;
+				goto retry;
+			}
+			goto err_free;
+		}
+
+		/*
+		 * If next overlaps, move base downwards so that it's
+		 * right below next and then recheck.
+		 */
+		if (next && next->va_start < base + end) {
+			base = pvm_determine_end(&next, &prev, align) - end;
+			term_area = area;
+			continue;
+		}
+
+		/*
+		 * If prev overlaps, shift down next and prev and move
+		 * base so that it's right below new next and then
+		 * recheck.
+		 */
+		if (prev && prev->va_end > base + start)  {
+			next = prev;
+			prev = node_to_va(rb_prev(&next->rb_node));
+			base = pvm_determine_end(&next, &prev, align) - end;
+			term_area = area;
+			continue;
+		}
+
+		/*
+		 * This area fits, move on to the previous one.  If
+		 * the previous one is the terminal one, we're done.
+		 */
+		area = (area + nr_vms - 1) % nr_vms;
+		if (area == term_area)
+			break;
+		start = offsets[area];
+		end = start + sizes[area];
+		pvm_find_next_prev(base + end, &next, &prev);
+	}
+found:
+	/* we've found a fitting base, insert all va's */
+	for (area = 0; area < nr_vms; area++) {
+		struct vmap_area *va = vas[area];
+
+		va->va_start = base + offsets[area];
+		va->va_end = va->va_start + sizes[area];
+		__insert_vmap_area(va);
+	}
+
+	vmap_area_pcpu_hole = base + offsets[last_area];
+
+	spin_unlock(&vmap_area_lock);
+
+	/* insert all vm's */
+	for (area = 0; area < nr_vms; area++)
+		setup_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
+				 pcpu_get_vm_areas);
+
+	kfree(vas);
+	return vms;
+
+err_free:
+	for (area = 0; area < nr_vms; area++) {
+		kfree(vas[area]);
+		kfree(vms[area]);
+	}
+err_free2:
+	kfree(vas);
+	kfree(vms);
+	return NULL;
+}
+
+/**
+ * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
+ * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
+ * @nr_vms: the number of allocated areas
+ *
+ * Free vm_structs and the array allocated by pcpu_get_vm_areas().
+ */
+void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
+{
+	int i;
+
+	for (i = 0; i < nr_vms; i++)
+		free_vm_area(vms[i]);
+	kfree(vms);
+}
+#endif	/* CONFIG_SMP */
+
+#ifdef CONFIG_PROC_FS
+static void *s_start(struct seq_file *m, loff_t *pos)
+	__acquires(&vmap_area_lock)
+{
+	loff_t n = *pos;
+	struct vmap_area *va;
+
+	spin_lock(&vmap_area_lock);
+	va = list_entry((&vmap_area_list)->next, typeof(*va), list);
+	while (n > 0 && &va->list != &vmap_area_list) {
+		n--;
+		va = list_entry(va->list.next, typeof(*va), list);
+	}
+	if (!n && &va->list != &vmap_area_list)
+		return va;
+
+	return NULL;
+
+}
+
+static void *s_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	struct vmap_area *va = p, *next;
+
+	++*pos;
+	next = list_entry(va->list.next, typeof(*va), list);
+	if (&next->list != &vmap_area_list)
+		return next;
+
+	return NULL;
+}
+
+static void s_stop(struct seq_file *m, void *p)
+	__releases(&vmap_area_lock)
+{
+	spin_unlock(&vmap_area_lock);
+}
+
+static void show_numa_info(struct seq_file *m, struct vm_struct *v)
+{
+	if (IS_ENABLED(CONFIG_NUMA)) {
+		unsigned int nr, *counters = m->private;
+
+		if (!counters)
+			return;
+
+		if (v->flags & VM_UNINITIALIZED)
+			return;
+		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+		smp_rmb();
+
+		memset(counters, 0, nr_node_ids * sizeof(unsigned int));
+
+		for (nr = 0; nr < v->nr_pages; nr++)
+			counters[page_to_nid(v->pages[nr])]++;
+
+		for_each_node_state(nr, N_HIGH_MEMORY)
+			if (counters[nr])
+				seq_printf(m, " N%u=%u", nr, counters[nr]);
+	}
+}
+
+static int s_show(struct seq_file *m, void *p)
+{
+	struct vmap_area *va = p;
+	struct vm_struct *v;
+
+	/*
+	 * s_show can encounter race with remove_vm_area, !VM_VM_AREA on
+	 * behalf of vmap area is being tear down or vm_map_ram allocation.
+	 */
+	if (!(va->flags & VM_VM_AREA))
+		return 0;
+
+	v = va->vm;
+
+	seq_printf(m, "0x%pK-0x%pK %7ld",
+		v->addr, v->addr + v->size, v->size);
+
+	if (v->caller)
+		seq_printf(m, " %pS", v->caller);
+
+	if (v->nr_pages)
+		seq_printf(m, " pages=%d", v->nr_pages);
+
+	if (v->phys_addr)
+		seq_printf(m, " phys=%llx", (unsigned long long)v->phys_addr);
+
+	if (v->flags & VM_IOREMAP)
+		seq_puts(m, " ioremap");
+
+	if (v->flags & VM_ALLOC)
+		seq_puts(m, " vmalloc");
+
+	if (v->flags & VM_MAP)
+		seq_puts(m, " vmap");
+
+	if (v->flags & VM_USERMAP)
+		seq_puts(m, " user");
+
+	if (v->flags & VM_VPAGES)
+		seq_puts(m, " vpages");
+
+	show_numa_info(m, v);
+	seq_putc(m, '\n');
+	return 0;
+}
+
+static const struct seq_operations vmalloc_op = {
+	.start = s_start,
+	.next = s_next,
+	.stop = s_stop,
+	.show = s_show,
+};
+
+static int vmalloc_open(struct inode *inode, struct file *file)
+{
+	if (IS_ENABLED(CONFIG_NUMA))
+		return seq_open_private(file, &vmalloc_op,
+					nr_node_ids * sizeof(unsigned int));
+	else
+		return seq_open(file, &vmalloc_op);
+}
+
+static const struct file_operations proc_vmalloc_operations = {
+	.open		= vmalloc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release_private,
+};
+
+static int __init proc_vmalloc_init(void)
+{
+	proc_create("vmallocinfo", S_IRUSR, NULL, &proc_vmalloc_operations);
+	return 0;
+}
+module_init(proc_vmalloc_init);
+
+#endif
+
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
new file mode 100644
index 0000000..3fb15c2
--- /dev/null
+++ b/mm/vmpressure.c
@@ -0,0 +1,390 @@
+/*
+ * Linux VM pressure
+ *
+ * Copyright 2012 Linaro Ltd.
+ *		  Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * Based on ideas from Andrew Morton, David Rientjes, KOSAKI Motohiro,
+ * Leonid Moiseichuk, Mel Gorman, Minchan Kim and Pekka Enberg.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/log2.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/vmstat.h>
+#include <linux/eventfd.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/printk.h>
+#include <linux/vmpressure.h>
+
+/*
+ * The window size (vmpressure_win) is the number of scanned pages before
+ * we try to analyze scanned/reclaimed ratio. So the window is used as a
+ * rate-limit tunable for the "low" level notification, and also for
+ * averaging the ratio for medium/critical levels. Using small window
+ * sizes can cause lot of false positives, but too big window size will
+ * delay the notifications.
+ *
+ * As the vmscan reclaimer logic works with chunks which are multiple of
+ * SWAP_CLUSTER_MAX, it makes sense to use it for the window size as well.
+ *
+ * TODO: Make the window size depend on machine size, as we do for vmstat
+ * thresholds. Currently we set it to 512 pages (2MB for 4KB pages).
+ */
+static const unsigned long vmpressure_win = SWAP_CLUSTER_MAX * 16;
+
+/*
+ * These thresholds are used when we account memory pressure through
+ * scanned/reclaimed ratio. The current values were chosen empirically. In
+ * essence, they are percents: the higher the value, the more number
+ * unsuccessful reclaims there were.
+ */
+static const unsigned int vmpressure_level_med = 60;
+static const unsigned int vmpressure_level_critical = 95;
+
+/*
+ * When there are too little pages left to scan, vmpressure() may miss the
+ * critical pressure as number of pages will be less than "window size".
+ * However, in that case the vmscan priority will raise fast as the
+ * reclaimer will try to scan LRUs more deeply.
+ *
+ * The vmscan logic considers these special priorities:
+ *
+ * prio == DEF_PRIORITY (12): reclaimer starts with that value
+ * prio <= DEF_PRIORITY - 2 : kswapd becomes somewhat overwhelmed
+ * prio == 0                : close to OOM, kernel scans every page in an lru
+ *
+ * Any value in this range is acceptable for this tunable (i.e. from 12 to
+ * 0). Current value for the vmpressure_level_critical_prio is chosen
+ * empirically, but the number, in essence, means that we consider
+ * critical level when scanning depth is ~10% of the lru size (vmscan
+ * scans 'lru_size >> prio' pages, so it is actually 12.5%, or one
+ * eights).
+ */
+static const unsigned int vmpressure_level_critical_prio = ilog2(100 / 10);
+
+static struct vmpressure *work_to_vmpressure(struct work_struct *work)
+{
+	return container_of(work, struct vmpressure, work);
+}
+
+static struct vmpressure *vmpressure_parent(struct vmpressure *vmpr)
+{
+	struct cgroup_subsys_state *css = vmpressure_to_css(vmpr);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	memcg = parent_mem_cgroup(memcg);
+	if (!memcg)
+		return NULL;
+	return memcg_to_vmpressure(memcg);
+}
+
+enum vmpressure_levels {
+	VMPRESSURE_LOW = 0,
+	VMPRESSURE_MEDIUM,
+	VMPRESSURE_CRITICAL,
+	VMPRESSURE_NUM_LEVELS,
+};
+
+static const char * const vmpressure_str_levels[] = {
+	[VMPRESSURE_LOW] = "low",
+	[VMPRESSURE_MEDIUM] = "medium",
+	[VMPRESSURE_CRITICAL] = "critical",
+};
+
+static enum vmpressure_levels vmpressure_level(unsigned long pressure)
+{
+	if (pressure >= vmpressure_level_critical)
+		return VMPRESSURE_CRITICAL;
+	else if (pressure >= vmpressure_level_med)
+		return VMPRESSURE_MEDIUM;
+	return VMPRESSURE_LOW;
+}
+
+static enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,
+						    unsigned long reclaimed)
+{
+	unsigned long scale = scanned + reclaimed;
+	unsigned long pressure = 0;
+
+	/*
+	 * reclaimed can be greater than scanned in cases
+	 * like THP, where the scanned is 1 and reclaimed
+	 * could be 512
+	 */
+	if (reclaimed >= scanned)
+		goto out;
+	/*
+	 * We calculate the ratio (in percents) of how many pages were
+	 * scanned vs. reclaimed in a given time frame (window). Note that
+	 * time is in VM reclaimer's "ticks", i.e. number of pages
+	 * scanned. This makes it possible to set desired reaction time
+	 * and serves as a ratelimit.
+	 */
+	pressure = scale - (reclaimed * scale / scanned);
+	pressure = pressure * 100 / scale;
+
+out:
+	pr_debug("%s: %3lu  (s: %lu  r: %lu)\n", __func__, pressure,
+		 scanned, reclaimed);
+
+	return vmpressure_level(pressure);
+}
+
+struct vmpressure_event {
+	struct eventfd_ctx *efd;
+	enum vmpressure_levels level;
+	struct list_head node;
+};
+
+static bool vmpressure_event(struct vmpressure *vmpr,
+			     unsigned long scanned, unsigned long reclaimed)
+{
+	struct vmpressure_event *ev;
+	enum vmpressure_levels level;
+	bool signalled = false;
+
+	level = vmpressure_calc_level(scanned, reclaimed);
+
+	mutex_lock(&vmpr->events_lock);
+
+	list_for_each_entry(ev, &vmpr->events, node) {
+		if (level >= ev->level) {
+			eventfd_signal(ev->efd, 1);
+			signalled = true;
+		}
+	}
+
+	mutex_unlock(&vmpr->events_lock);
+
+	return signalled;
+}
+
+static void vmpressure_work_fn(struct work_struct *work)
+{
+	struct vmpressure *vmpr = work_to_vmpressure(work);
+	unsigned long scanned;
+	unsigned long reclaimed;
+
+	spin_lock(&vmpr->sr_lock);
+	/*
+	 * Several contexts might be calling vmpressure(), so it is
+	 * possible that the work was rescheduled again before the old
+	 * work context cleared the counters. In that case we will run
+	 * just after the old work returns, but then scanned might be zero
+	 * here. No need for any locks here since we don't care if
+	 * vmpr->reclaimed is in sync.
+	 */
+	scanned = vmpr->scanned;
+	if (!scanned) {
+		spin_unlock(&vmpr->sr_lock);
+		return;
+	}
+
+	reclaimed = vmpr->reclaimed;
+	vmpr->scanned = 0;
+	vmpr->reclaimed = 0;
+	spin_unlock(&vmpr->sr_lock);
+
+	do {
+		if (vmpressure_event(vmpr, scanned, reclaimed))
+			break;
+		/*
+		 * If not handled, propagate the event upward into the
+		 * hierarchy.
+		 */
+	} while ((vmpr = vmpressure_parent(vmpr)));
+}
+
+/**
+ * vmpressure() - Account memory pressure through scanned/reclaimed ratio
+ * @gfp:	reclaimer's gfp mask
+ * @memcg:	cgroup memory controller handle
+ * @scanned:	number of pages scanned
+ * @reclaimed:	number of pages reclaimed
+ *
+ * This function should be called from the vmscan reclaim path to account
+ * "instantaneous" memory pressure (scanned/reclaimed ratio). The raw
+ * pressure index is then further refined and averaged over time.
+ *
+ * This function does not return any value.
+ */
+void vmpressure(gfp_t gfp, struct mem_cgroup *memcg,
+		unsigned long scanned, unsigned long reclaimed)
+{
+	struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
+
+	/*
+	 * Here we only want to account pressure that userland is able to
+	 * help us with. For example, suppose that DMA zone is under
+	 * pressure; if we notify userland about that kind of pressure,
+	 * then it will be mostly a waste as it will trigger unnecessary
+	 * freeing of memory by userland (since userland is more likely to
+	 * have HIGHMEM/MOVABLE pages instead of the DMA fallback). That
+	 * is why we include only movable, highmem and FS/IO pages.
+	 * Indirect reclaim (kswapd) sets sc->gfp_mask to GFP_KERNEL, so
+	 * we account it too.
+	 */
+	if (!(gfp & (__GFP_HIGHMEM | __GFP_MOVABLE | __GFP_IO | __GFP_FS)))
+		return;
+
+	/*
+	 * If we got here with no pages scanned, then that is an indicator
+	 * that reclaimer was unable to find any shrinkable LRUs at the
+	 * current scanning depth. But it does not mean that we should
+	 * report the critical pressure, yet. If the scanning priority
+	 * (scanning depth) goes too high (deep), we will be notified
+	 * through vmpressure_prio(). But so far, keep calm.
+	 */
+	if (!scanned)
+		return;
+
+	spin_lock(&vmpr->sr_lock);
+	vmpr->scanned += scanned;
+	vmpr->reclaimed += reclaimed;
+	scanned = vmpr->scanned;
+	spin_unlock(&vmpr->sr_lock);
+
+	if (scanned < vmpressure_win)
+		return;
+	schedule_work(&vmpr->work);
+}
+
+/**
+ * vmpressure_prio() - Account memory pressure through reclaimer priority level
+ * @gfp:	reclaimer's gfp mask
+ * @memcg:	cgroup memory controller handle
+ * @prio:	reclaimer's priority
+ *
+ * This function should be called from the reclaim path every time when
+ * the vmscan's reclaiming priority (scanning depth) changes.
+ *
+ * This function does not return any value.
+ */
+void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
+{
+	/*
+	 * We only use prio for accounting critical level. For more info
+	 * see comment for vmpressure_level_critical_prio variable above.
+	 */
+	if (prio > vmpressure_level_critical_prio)
+		return;
+
+	/*
+	 * OK, the prio is below the threshold, updating vmpressure
+	 * information before shrinker dives into long shrinking of long
+	 * range vmscan. Passing scanned = vmpressure_win, reclaimed = 0
+	 * to the vmpressure() basically means that we signal 'critical'
+	 * level.
+	 */
+	vmpressure(gfp, memcg, vmpressure_win, 0);
+}
+
+/**
+ * vmpressure_register_event() - Bind vmpressure notifications to an eventfd
+ * @memcg:	memcg that is interested in vmpressure notifications
+ * @eventfd:	eventfd context to link notifications with
+ * @args:	event arguments (used to set up a pressure level threshold)
+ *
+ * This function associates eventfd context with the vmpressure
+ * infrastructure, so that the notifications will be delivered to the
+ * @eventfd. The @args parameter is a string that denotes pressure level
+ * threshold (one of vmpressure_str_levels, i.e. "low", "medium", or
+ * "critical").
+ *
+ * To be used as memcg event method.
+ */
+int vmpressure_register_event(struct mem_cgroup *memcg,
+			      struct eventfd_ctx *eventfd, const char *args)
+{
+	struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
+	struct vmpressure_event *ev;
+	int level;
+
+	for (level = 0; level < VMPRESSURE_NUM_LEVELS; level++) {
+		if (!strcmp(vmpressure_str_levels[level], args))
+			break;
+	}
+
+	if (level >= VMPRESSURE_NUM_LEVELS)
+		return -EINVAL;
+
+	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
+	if (!ev)
+		return -ENOMEM;
+
+	ev->efd = eventfd;
+	ev->level = level;
+
+	mutex_lock(&vmpr->events_lock);
+	list_add(&ev->node, &vmpr->events);
+	mutex_unlock(&vmpr->events_lock);
+
+	return 0;
+}
+
+/**
+ * vmpressure_unregister_event() - Unbind eventfd from vmpressure
+ * @memcg:	memcg handle
+ * @eventfd:	eventfd context that was used to link vmpressure with the @cg
+ *
+ * This function does internal manipulations to detach the @eventfd from
+ * the vmpressure notifications, and then frees internal resources
+ * associated with the @eventfd (but the @eventfd itself is not freed).
+ *
+ * To be used as memcg event method.
+ */
+void vmpressure_unregister_event(struct mem_cgroup *memcg,
+				 struct eventfd_ctx *eventfd)
+{
+	struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
+	struct vmpressure_event *ev;
+
+	mutex_lock(&vmpr->events_lock);
+	list_for_each_entry(ev, &vmpr->events, node) {
+		if (ev->efd != eventfd)
+			continue;
+		list_del(&ev->node);
+		kfree(ev);
+		break;
+	}
+	mutex_unlock(&vmpr->events_lock);
+}
+
+/**
+ * vmpressure_init() - Initialize vmpressure control structure
+ * @vmpr:	Structure to be initialized
+ *
+ * This function should be called on every allocated vmpressure structure
+ * before any usage.
+ */
+void vmpressure_init(struct vmpressure *vmpr)
+{
+	spin_lock_init(&vmpr->sr_lock);
+	mutex_init(&vmpr->events_lock);
+	INIT_LIST_HEAD(&vmpr->events);
+	INIT_WORK(&vmpr->work, vmpressure_work_fn);
+}
+
+/**
+ * vmpressure_cleanup() - shuts down vmpressure control structure
+ * @vmpr:	Structure to be cleaned up
+ *
+ * This function should be called before the structure in which it is
+ * embedded is cleaned up.
+ */
+void vmpressure_cleanup(struct vmpressure *vmpr)
+{
+	/*
+	 * Make sure there is no pending work before eventfd infrastructure
+	 * goes away.
+	 */
+	flush_work(&vmpr->work);
+}
diff --git a/mm/vmscan.c b/mm/vmscan.c
new file mode 100644
index 0000000..440c2df
--- /dev/null
+++ b/mm/vmscan.c
@@ -0,0 +1,3880 @@
+/*
+ *  linux/mm/vmscan.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *
+ *  Swap reorganised 29.12.95, Stephen Tweedie.
+ *  kswapd added: 7.1.96  sct
+ *  Removed kswapd_ctl limits, and swap out as many pages as needed
+ *  to bring the system back to freepages.high: 2.4.97, Rik van Riel.
+ *  Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
+ *  Multiqueue VM started 5.8.00, Rik van Riel.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/gfp.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/highmem.h>
+#include <linux/vmpressure.h>
+#include <linux/vmstat.h>
+#include <linux/file.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>	/* for try_to_release_page(),
+					buffer_heads_over_limit */
+#include <linux/mm_inline.h>
+#include <linux/backing-dev.h>
+#include <linux/rmap.h>
+#include <linux/topology.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/compaction.h>
+#include <linux/notifier.h>
+#include <linux/rwsem.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include <linux/memcontrol.h>
+#include <linux/delayacct.h>
+#include <linux/sysctl.h>
+#include <linux/oom.h>
+#include <linux/prefetch.h>
+#include <linux/printk.h>
+
+#include <asm/tlbflush.h>
+#include <asm/div64.h>
+
+#include <linux/swapops.h>
+#include <linux/balloon_compaction.h>
+
+#include "internal.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/vmscan.h>
+
+struct scan_control {
+	/* How many pages shrink_list() should reclaim */
+	unsigned long nr_to_reclaim;
+
+	/* This context's GFP mask */
+	gfp_t gfp_mask;
+
+	/* Allocation order */
+	int order;
+
+	/*
+	 * Nodemask of nodes allowed by the caller. If NULL, all nodes
+	 * are scanned.
+	 */
+	nodemask_t	*nodemask;
+
+	/*
+	 * The memory cgroup that hit its limit and as a result is the
+	 * primary target of this reclaim invocation.
+	 */
+	struct mem_cgroup *target_mem_cgroup;
+
+	/* Scan (total_size >> priority) pages at once */
+	int priority;
+
+	unsigned int may_writepage:1;
+
+	/* Can mapped pages be reclaimed? */
+	unsigned int may_unmap:1;
+
+	/* Can pages be swapped as part of reclaim? */
+	unsigned int may_swap:1;
+
+	/* Can cgroups be reclaimed below their normal consumption range? */
+	unsigned int may_thrash:1;
+
+	unsigned int hibernation_mode:1;
+
+	/* One of the zones is ready for compaction */
+	unsigned int compaction_ready:1;
+
+	/* Incremented by the number of inactive pages that were scanned */
+	unsigned long nr_scanned;
+
+	/* Number of pages freed so far during a call to shrink_zones() */
+	unsigned long nr_reclaimed;
+};
+
+#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
+
+#ifdef ARCH_HAS_PREFETCH
+#define prefetch_prev_lru_page(_page, _base, _field)			\
+	do {								\
+		if ((_page)->lru.prev != _base) {			\
+			struct page *prev;				\
+									\
+			prev = lru_to_page(&(_page->lru));		\
+			prefetch(&prev->_field);			\
+		}							\
+	} while (0)
+#else
+#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
+#endif
+
+#ifdef ARCH_HAS_PREFETCHW
+#define prefetchw_prev_lru_page(_page, _base, _field)			\
+	do {								\
+		if ((_page)->lru.prev != _base) {			\
+			struct page *prev;				\
+									\
+			prev = lru_to_page(&(_page->lru));		\
+			prefetchw(&prev->_field);			\
+		}							\
+	} while (0)
+#else
+#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
+#endif
+
+/*
+ * From 0 .. 100.  Higher means more swappy.
+ */
+int vm_swappiness = 60;
+/*
+ * The total number of pages which are beyond the high watermark within all
+ * zones.
+ */
+unsigned long vm_total_pages;
+
+static LIST_HEAD(shrinker_list);
+static DECLARE_RWSEM(shrinker_rwsem);
+
+#ifdef CONFIG_MEMCG
+static bool global_reclaim(struct scan_control *sc)
+{
+	return !sc->target_mem_cgroup;
+}
+
+/**
+ * sane_reclaim - is the usual dirty throttling mechanism operational?
+ * @sc: scan_control in question
+ *
+ * The normal page dirty throttling mechanism in balance_dirty_pages() is
+ * completely broken with the legacy memcg and direct stalling in
+ * shrink_page_list() is used for throttling instead, which lacks all the
+ * niceties such as fairness, adaptive pausing, bandwidth proportional
+ * allocation and configurability.
+ *
+ * This function tests whether the vmscan currently in progress can assume
+ * that the normal dirty throttling mechanism is operational.
+ */
+static bool sane_reclaim(struct scan_control *sc)
+{
+	struct mem_cgroup *memcg = sc->target_mem_cgroup;
+
+	if (!memcg)
+		return true;
+#ifdef CONFIG_CGROUP_WRITEBACK
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return true;
+#endif
+	return false;
+}
+#else
+static bool global_reclaim(struct scan_control *sc)
+{
+	return true;
+}
+
+static bool sane_reclaim(struct scan_control *sc)
+{
+	return true;
+}
+#endif
+
+static unsigned long zone_reclaimable_pages(struct zone *zone)
+{
+	unsigned long nr;
+
+	nr = zone_page_state(zone, NR_ACTIVE_FILE) +
+	     zone_page_state(zone, NR_INACTIVE_FILE);
+
+	if (get_nr_swap_pages() > 0)
+		nr += zone_page_state(zone, NR_ACTIVE_ANON) +
+		      zone_page_state(zone, NR_INACTIVE_ANON);
+
+	return nr;
+}
+
+bool zone_reclaimable(struct zone *zone)
+{
+	return zone_page_state(zone, NR_PAGES_SCANNED) <
+		zone_reclaimable_pages(zone) * 6;
+}
+
+static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru)
+{
+	if (!mem_cgroup_disabled())
+		return mem_cgroup_get_lru_size(lruvec, lru);
+
+	return zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru);
+}
+
+/*
+ * Add a shrinker callback to be called from the vm.
+ */
+int register_shrinker(struct shrinker *shrinker)
+{
+	size_t size = sizeof(*shrinker->nr_deferred);
+
+	/*
+	 * If we only have one possible node in the system anyway, save
+	 * ourselves the trouble and disable NUMA aware behavior. This way we
+	 * will save memory and some small loop time later.
+	 */
+	if (nr_node_ids == 1)
+		shrinker->flags &= ~SHRINKER_NUMA_AWARE;
+
+	if (shrinker->flags & SHRINKER_NUMA_AWARE)
+		size *= nr_node_ids;
+
+	shrinker->nr_deferred = kzalloc(size, GFP_KERNEL);
+	if (!shrinker->nr_deferred)
+		return -ENOMEM;
+
+	down_write(&shrinker_rwsem);
+	list_add_tail(&shrinker->list, &shrinker_list);
+	up_write(&shrinker_rwsem);
+	return 0;
+}
+EXPORT_SYMBOL(register_shrinker);
+
+/*
+ * Remove one
+ */
+void unregister_shrinker(struct shrinker *shrinker)
+{
+	down_write(&shrinker_rwsem);
+	list_del(&shrinker->list);
+	up_write(&shrinker_rwsem);
+	kfree(shrinker->nr_deferred);
+}
+EXPORT_SYMBOL(unregister_shrinker);
+
+#define SHRINK_BATCH 128
+
+static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
+				    struct shrinker *shrinker,
+				    unsigned long nr_scanned,
+				    unsigned long nr_eligible)
+{
+	unsigned long freed = 0;
+	unsigned long long delta;
+	long total_scan;
+	long freeable;
+	long nr;
+	long new_nr;
+	int nid = shrinkctl->nid;
+	long batch_size = shrinker->batch ? shrinker->batch
+					  : SHRINK_BATCH;
+	long scanned = 0, next_deferred;
+
+	freeable = shrinker->count_objects(shrinker, shrinkctl);
+	if (freeable == 0)
+		return 0;
+
+	/*
+	 * copy the current shrinker scan count into a local variable
+	 * and zero it so that other concurrent shrinker invocations
+	 * don't also do this scanning work.
+	 */
+	nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
+
+	total_scan = nr;
+	delta = (4 * nr_scanned) / shrinker->seeks;
+	delta *= freeable;
+	do_div(delta, nr_eligible + 1);
+	total_scan += delta;
+	if (total_scan < 0) {
+		pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n",
+		       shrinker->scan_objects, total_scan);
+		total_scan = freeable;
+		next_deferred = nr;
+	} else
+		next_deferred = total_scan;
+
+	/*
+	 * We need to avoid excessive windup on filesystem shrinkers
+	 * due to large numbers of GFP_NOFS allocations causing the
+	 * shrinkers to return -1 all the time. This results in a large
+	 * nr being built up so when a shrink that can do some work
+	 * comes along it empties the entire cache due to nr >>>
+	 * freeable. This is bad for sustaining a working set in
+	 * memory.
+	 *
+	 * Hence only allow the shrinker to scan the entire cache when
+	 * a large delta change is calculated directly.
+	 */
+	if (delta < freeable / 4)
+		total_scan = min(total_scan, freeable / 2);
+
+	/*
+	 * Avoid risking looping forever due to too large nr value:
+	 * never try to free more than twice the estimate number of
+	 * freeable entries.
+	 */
+	if (total_scan > freeable * 2)
+		total_scan = freeable * 2;
+
+	trace_mm_shrink_slab_start(shrinker, shrinkctl, nr,
+				   nr_scanned, nr_eligible,
+				   freeable, delta, total_scan);
+
+	/*
+	 * Normally, we should not scan less than batch_size objects in one
+	 * pass to avoid too frequent shrinker calls, but if the slab has less
+	 * than batch_size objects in total and we are really tight on memory,
+	 * we will try to reclaim all available objects, otherwise we can end
+	 * up failing allocations although there are plenty of reclaimable
+	 * objects spread over several slabs with usage less than the
+	 * batch_size.
+	 *
+	 * We detect the "tight on memory" situations by looking at the total
+	 * number of objects we want to scan (total_scan). If it is greater
+	 * than the total number of objects on slab (freeable), we must be
+	 * scanning at high prio and therefore should try to reclaim as much as
+	 * possible.
+	 */
+	while (total_scan >= batch_size ||
+	       total_scan >= freeable) {
+		unsigned long ret;
+		unsigned long nr_to_scan = min(batch_size, total_scan);
+
+		shrinkctl->nr_to_scan = nr_to_scan;
+		ret = shrinker->scan_objects(shrinker, shrinkctl);
+		if (ret == SHRINK_STOP)
+			break;
+		freed += ret;
+
+		count_vm_events(SLABS_SCANNED, nr_to_scan);
+		total_scan -= nr_to_scan;
+		scanned += nr_to_scan;
+
+		cond_resched();
+	}
+
+	if (next_deferred >= scanned)
+		next_deferred -= scanned;
+	else
+		next_deferred = 0;
+	/*
+	 * move the unused scan count back into the shrinker in a
+	 * manner that handles concurrent updates. If we exhausted the
+	 * scan, there is no need to do an update.
+	 */
+	if (next_deferred > 0)
+		new_nr = atomic_long_add_return(next_deferred,
+						&shrinker->nr_deferred[nid]);
+	else
+		new_nr = atomic_long_read(&shrinker->nr_deferred[nid]);
+
+	trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan);
+	return freed;
+}
+
+/**
+ * shrink_slab - shrink slab caches
+ * @gfp_mask: allocation context
+ * @nid: node whose slab caches to target
+ * @memcg: memory cgroup whose slab caches to target
+ * @nr_scanned: pressure numerator
+ * @nr_eligible: pressure denominator
+ *
+ * Call the shrink functions to age shrinkable caches.
+ *
+ * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set,
+ * unaware shrinkers will receive a node id of 0 instead.
+ *
+ * @memcg specifies the memory cgroup to target. If it is not NULL,
+ * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan
+ * objects from the memory cgroup specified. Otherwise all shrinkers
+ * are called, and memcg aware shrinkers are supposed to scan the
+ * global list then.
+ *
+ * @nr_scanned and @nr_eligible form a ratio that indicate how much of
+ * the available objects should be scanned.  Page reclaim for example
+ * passes the number of pages scanned and the number of pages on the
+ * LRU lists that it considered on @nid, plus a bias in @nr_scanned
+ * when it encountered mapped pages.  The ratio is further biased by
+ * the ->seeks setting of the shrink function, which indicates the
+ * cost to recreate an object relative to that of an LRU page.
+ *
+ * Returns the number of reclaimed slab objects.
+ */
+static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
+				 struct mem_cgroup *memcg,
+				 unsigned long nr_scanned,
+				 unsigned long nr_eligible)
+{
+	struct shrinker *shrinker;
+	unsigned long freed = 0;
+
+	if (memcg && !memcg_kmem_is_active(memcg))
+		return 0;
+
+	if (nr_scanned == 0)
+		nr_scanned = SWAP_CLUSTER_MAX;
+
+	if (!down_read_trylock(&shrinker_rwsem)) {
+		/*
+		 * If we would return 0, our callers would understand that we
+		 * have nothing else to shrink and give up trying. By returning
+		 * 1 we keep it going and assume we'll be able to shrink next
+		 * time.
+		 */
+		freed = 1;
+		goto out;
+	}
+
+	list_for_each_entry(shrinker, &shrinker_list, list) {
+		struct shrink_control sc = {
+			.gfp_mask = gfp_mask,
+			.nid = nid,
+			.memcg = memcg,
+		};
+
+		if (memcg && !(shrinker->flags & SHRINKER_MEMCG_AWARE))
+			continue;
+
+		if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+			sc.nid = 0;
+
+		freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);
+	}
+
+	up_read(&shrinker_rwsem);
+out:
+	cond_resched();
+	return freed;
+}
+
+void drop_slab_node(int nid)
+{
+	unsigned long freed;
+
+	do {
+		struct mem_cgroup *memcg = NULL;
+
+		freed = 0;
+		do {
+			freed += shrink_slab(GFP_KERNEL, nid, memcg,
+					     1000, 1000);
+		} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
+	} while (freed > 10);
+}
+
+void drop_slab(void)
+{
+	int nid;
+
+	for_each_online_node(nid)
+		drop_slab_node(nid);
+}
+
+static inline int is_page_cache_freeable(struct page *page)
+{
+	/*
+	 * A freeable page cache page is referenced only by the caller
+	 * that isolated the page, the page cache radix tree and
+	 * optional buffer heads at page->private.
+	 */
+	return page_count(page) - page_has_private(page) == 2;
+}
+
+static int may_write_to_inode(struct inode *inode, struct scan_control *sc)
+{
+	if (current->flags & PF_SWAPWRITE)
+		return 1;
+	if (!inode_write_congested(inode))
+		return 1;
+	if (inode_to_bdi(inode) == current->backing_dev_info)
+		return 1;
+	return 0;
+}
+
+/*
+ * We detected a synchronous write error writing a page out.  Probably
+ * -ENOSPC.  We need to propagate that into the address_space for a subsequent
+ * fsync(), msync() or close().
+ *
+ * The tricky part is that after writepage we cannot touch the mapping: nothing
+ * prevents it from being freed up.  But we have a ref on the page and once
+ * that page is locked, the mapping is pinned.
+ *
+ * We're allowed to run sleeping lock_page() here because we know the caller has
+ * __GFP_FS.
+ */
+static void handle_write_error(struct address_space *mapping,
+				struct page *page, int error)
+{
+	lock_page(page);
+	if (page_mapping(page) == mapping)
+		mapping_set_error(mapping, error);
+	unlock_page(page);
+}
+
+/* possible outcome of pageout() */
+typedef enum {
+	/* failed to write page out, page is locked */
+	PAGE_KEEP,
+	/* move page to the active list, page is locked */
+	PAGE_ACTIVATE,
+	/* page has been sent to the disk successfully, page is unlocked */
+	PAGE_SUCCESS,
+	/* page is clean and locked */
+	PAGE_CLEAN,
+} pageout_t;
+
+/*
+ * pageout is called by shrink_page_list() for each dirty page.
+ * Calls ->writepage().
+ */
+static pageout_t pageout(struct page *page, struct address_space *mapping,
+			 struct scan_control *sc)
+{
+	/*
+	 * If the page is dirty, only perform writeback if that write
+	 * will be non-blocking.  To prevent this allocation from being
+	 * stalled by pagecache activity.  But note that there may be
+	 * stalls if we need to run get_block().  We could test
+	 * PagePrivate for that.
+	 *
+	 * If this process is currently in __generic_file_write_iter() against
+	 * this page's queue, we can perform writeback even if that
+	 * will block.
+	 *
+	 * If the page is swapcache, write it back even if that would
+	 * block, for some throttling. This happens by accident, because
+	 * swap_backing_dev_info is bust: it doesn't reflect the
+	 * congestion state of the swapdevs.  Easy to fix, if needed.
+	 */
+	if (!is_page_cache_freeable(page))
+		return PAGE_KEEP;
+	if (!mapping) {
+		/*
+		 * Some data journaling orphaned pages can have
+		 * page->mapping == NULL while being dirty with clean buffers.
+		 */
+		if (page_has_private(page)) {
+			if (try_to_free_buffers(page)) {
+				ClearPageDirty(page);
+				pr_info("%s: orphaned page\n", __func__);
+				return PAGE_CLEAN;
+			}
+		}
+		return PAGE_KEEP;
+	}
+	if (mapping->a_ops->writepage == NULL)
+		return PAGE_ACTIVATE;
+	if (!may_write_to_inode(mapping->host, sc))
+		return PAGE_KEEP;
+
+	if (clear_page_dirty_for_io(page)) {
+		int res;
+		struct writeback_control wbc = {
+			.sync_mode = WB_SYNC_NONE,
+			.nr_to_write = SWAP_CLUSTER_MAX,
+			.range_start = 0,
+			.range_end = LLONG_MAX,
+			.for_reclaim = 1,
+		};
+
+		SetPageReclaim(page);
+		res = mapping->a_ops->writepage(page, &wbc);
+		if (res < 0)
+			handle_write_error(mapping, page, res);
+		if (res == AOP_WRITEPAGE_ACTIVATE) {
+			ClearPageReclaim(page);
+			return PAGE_ACTIVATE;
+		}
+
+		if (!PageWriteback(page)) {
+			/* synchronous write or broken a_ops? */
+			ClearPageReclaim(page);
+		}
+		trace_mm_vmscan_writepage(page, trace_reclaim_flags(page));
+		inc_zone_page_state(page, NR_VMSCAN_WRITE);
+		return PAGE_SUCCESS;
+	}
+
+	return PAGE_CLEAN;
+}
+
+/*
+ * Same as remove_mapping, but if the page is removed from the mapping, it
+ * gets returned with a refcount of 0.
+ */
+static int __remove_mapping(struct address_space *mapping, struct page *page,
+			    bool reclaimed)
+{
+	unsigned long flags;
+	struct mem_cgroup *memcg;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(mapping != page_mapping(page));
+
+	memcg = mem_cgroup_begin_page_stat(page);
+	spin_lock_irqsave(&mapping->tree_lock, flags);
+	/*
+	 * The non racy check for a busy page.
+	 *
+	 * Must be careful with the order of the tests. When someone has
+	 * a ref to the page, it may be possible that they dirty it then
+	 * drop the reference. So if PageDirty is tested before page_count
+	 * here, then the following race may occur:
+	 *
+	 * get_user_pages(&page);
+	 * [user mapping goes away]
+	 * write_to(page);
+	 *				!PageDirty(page)    [good]
+	 * SetPageDirty(page);
+	 * put_page(page);
+	 *				!page_count(page)   [good, discard it]
+	 *
+	 * [oops, our write_to data is lost]
+	 *
+	 * Reversing the order of the tests ensures such a situation cannot
+	 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
+	 * load is not satisfied before that of page->_count.
+	 *
+	 * Note that if SetPageDirty is always performed via set_page_dirty,
+	 * and thus under tree_lock, then this ordering is not required.
+	 */
+	if (!page_freeze_refs(page, 2))
+		goto cannot_free;
+	/* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
+	if (unlikely(PageDirty(page))) {
+		page_unfreeze_refs(page, 2);
+		goto cannot_free;
+	}
+
+	if (PageSwapCache(page)) {
+		swp_entry_t swap = { .val = page_private(page) };
+		mem_cgroup_swapout(page, swap);
+		__delete_from_swap_cache(page);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		mem_cgroup_end_page_stat(memcg);
+		swapcache_free(swap);
+	} else {
+		void (*freepage)(struct page *);
+		void *shadow = NULL;
+
+		freepage = mapping->a_ops->freepage;
+		/*
+		 * Remember a shadow entry for reclaimed file cache in
+		 * order to detect refaults, thus thrashing, later on.
+		 *
+		 * But don't store shadows in an address space that is
+		 * already exiting.  This is not just an optizimation,
+		 * inode reclaim needs to empty out the radix tree or
+		 * the nodes are lost.  Don't plant shadows behind its
+		 * back.
+		 */
+		if (reclaimed && page_is_file_cache(page) &&
+		    !mapping_exiting(mapping))
+			shadow = workingset_eviction(mapping, page);
+		__delete_from_page_cache(page, shadow, memcg);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		mem_cgroup_end_page_stat(memcg);
+
+		if (freepage != NULL)
+			freepage(page);
+	}
+
+	return 1;
+
+cannot_free:
+	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	mem_cgroup_end_page_stat(memcg);
+	return 0;
+}
+
+/*
+ * Attempt to detach a locked page from its ->mapping.  If it is dirty or if
+ * someone else has a ref on the page, abort and return 0.  If it was
+ * successfully detached, return 1.  Assumes the caller has a single ref on
+ * this page.
+ */
+int remove_mapping(struct address_space *mapping, struct page *page)
+{
+	if (__remove_mapping(mapping, page, false)) {
+		/*
+		 * Unfreezing the refcount with 1 rather than 2 effectively
+		 * drops the pagecache ref for us without requiring another
+		 * atomic operation.
+		 */
+		page_unfreeze_refs(page, 1);
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * putback_lru_page - put previously isolated page onto appropriate LRU list
+ * @page: page to be put back to appropriate lru list
+ *
+ * Add previously isolated @page to appropriate LRU list.
+ * Page may still be unevictable for other reasons.
+ *
+ * lru_lock must not be held, interrupts must be enabled.
+ */
+void putback_lru_page(struct page *page)
+{
+	bool is_unevictable;
+	int was_unevictable = PageUnevictable(page);
+
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+
+redo:
+	ClearPageUnevictable(page);
+
+	if (page_evictable(page)) {
+		/*
+		 * For evictable pages, we can use the cache.
+		 * In event of a race, worst case is we end up with an
+		 * unevictable page on [in]active list.
+		 * We know how to handle that.
+		 */
+		is_unevictable = false;
+		lru_cache_add(page);
+	} else {
+		/*
+		 * Put unevictable pages directly on zone's unevictable
+		 * list.
+		 */
+		is_unevictable = true;
+		add_page_to_unevictable_list(page);
+		/*
+		 * When racing with an mlock or AS_UNEVICTABLE clearing
+		 * (page is unlocked) make sure that if the other thread
+		 * does not observe our setting of PG_lru and fails
+		 * isolation/check_move_unevictable_pages,
+		 * we see PG_mlocked/AS_UNEVICTABLE cleared below and move
+		 * the page back to the evictable list.
+		 *
+		 * The other side is TestClearPageMlocked() or shmem_lock().
+		 */
+		smp_mb();
+	}
+
+	/*
+	 * page's status can change while we move it among lru. If an evictable
+	 * page is on unevictable list, it never be freed. To avoid that,
+	 * check after we added it to the list, again.
+	 */
+	if (is_unevictable && page_evictable(page)) {
+		if (!isolate_lru_page(page)) {
+			put_page(page);
+			goto redo;
+		}
+		/* This means someone else dropped this page from LRU
+		 * So, it will be freed or putback to LRU again. There is
+		 * nothing to do here.
+		 */
+	}
+
+	if (was_unevictable && !is_unevictable)
+		count_vm_event(UNEVICTABLE_PGRESCUED);
+	else if (!was_unevictable && is_unevictable)
+		count_vm_event(UNEVICTABLE_PGCULLED);
+
+	put_page(page);		/* drop ref from isolate */
+}
+
+enum page_references {
+	PAGEREF_RECLAIM,
+	PAGEREF_RECLAIM_CLEAN,
+	PAGEREF_KEEP,
+	PAGEREF_ACTIVATE,
+};
+
+static enum page_references page_check_references(struct page *page,
+						  struct scan_control *sc)
+{
+	int referenced_ptes, referenced_page;
+	unsigned long vm_flags;
+
+	referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
+					  &vm_flags);
+	referenced_page = TestClearPageReferenced(page);
+
+	/*
+	 * Mlock lost the isolation race with us.  Let try_to_unmap()
+	 * move the page to the unevictable list.
+	 */
+	if (vm_flags & VM_LOCKED)
+		return PAGEREF_RECLAIM;
+
+	if (referenced_ptes) {
+		if (PageSwapBacked(page))
+			return PAGEREF_ACTIVATE;
+		/*
+		 * All mapped pages start out with page table
+		 * references from the instantiating fault, so we need
+		 * to look twice if a mapped file page is used more
+		 * than once.
+		 *
+		 * Mark it and spare it for another trip around the
+		 * inactive list.  Another page table reference will
+		 * lead to its activation.
+		 *
+		 * Note: the mark is set for activated pages as well
+		 * so that recently deactivated but used pages are
+		 * quickly recovered.
+		 */
+		SetPageReferenced(page);
+
+		if (referenced_page || referenced_ptes > 1)
+			return PAGEREF_ACTIVATE;
+
+		/*
+		 * Activate file-backed executable pages after first usage.
+		 */
+		if (vm_flags & VM_EXEC)
+			return PAGEREF_ACTIVATE;
+
+		return PAGEREF_KEEP;
+	}
+
+	/* Reclaim if clean, defer dirty pages to writeback */
+	if (referenced_page && !PageSwapBacked(page))
+		return PAGEREF_RECLAIM_CLEAN;
+
+	return PAGEREF_RECLAIM;
+}
+
+/* Check if a page is dirty or under writeback */
+static void page_check_dirty_writeback(struct page *page,
+				       bool *dirty, bool *writeback)
+{
+	struct address_space *mapping;
+
+	/*
+	 * Anonymous pages are not handled by flushers and must be written
+	 * from reclaim context. Do not stall reclaim based on them
+	 */
+	if (!page_is_file_cache(page)) {
+		*dirty = false;
+		*writeback = false;
+		return;
+	}
+
+	/* By default assume that the page flags are accurate */
+	*dirty = PageDirty(page);
+	*writeback = PageWriteback(page);
+
+	/* Verify dirty/writeback state if the filesystem supports it */
+	if (!page_has_private(page))
+		return;
+
+	mapping = page_mapping(page);
+	if (mapping && mapping->a_ops->is_dirty_writeback)
+		mapping->a_ops->is_dirty_writeback(page, dirty, writeback);
+}
+
+/*
+ * shrink_page_list() returns the number of reclaimed pages
+ */
+static unsigned long shrink_page_list(struct list_head *page_list,
+				      struct zone *zone,
+				      struct scan_control *sc,
+				      enum ttu_flags ttu_flags,
+				      unsigned long *ret_nr_dirty,
+				      unsigned long *ret_nr_unqueued_dirty,
+				      unsigned long *ret_nr_congested,
+				      unsigned long *ret_nr_writeback,
+				      unsigned long *ret_nr_immediate,
+				      bool force_reclaim)
+{
+	LIST_HEAD(ret_pages);
+	LIST_HEAD(free_pages);
+	int pgactivate = 0;
+	unsigned long nr_unqueued_dirty = 0;
+	unsigned long nr_dirty = 0;
+	unsigned long nr_congested = 0;
+	unsigned long nr_reclaimed = 0;
+	unsigned long nr_writeback = 0;
+	unsigned long nr_immediate = 0;
+
+	cond_resched();
+
+	while (!list_empty(page_list)) {
+		struct address_space *mapping;
+		struct page *page;
+		int may_enter_fs;
+		enum page_references references = PAGEREF_RECLAIM_CLEAN;
+		bool dirty, writeback;
+
+		cond_resched();
+
+		page = lru_to_page(page_list);
+		list_del(&page->lru);
+
+		if (!trylock_page(page))
+			goto keep;
+
+		VM_BUG_ON_PAGE(PageActive(page), page);
+		VM_BUG_ON_PAGE(page_zone(page) != zone, page);
+
+		sc->nr_scanned++;
+
+		if (unlikely(!page_evictable(page)))
+			goto cull_mlocked;
+
+		if (!sc->may_unmap && page_mapped(page))
+			goto keep_locked;
+
+		/* Double the slab pressure for mapped and swapcache pages */
+		if (page_mapped(page) || PageSwapCache(page))
+			sc->nr_scanned++;
+
+		may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
+			(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
+
+		/*
+		 * The number of dirty pages determines if a zone is marked
+		 * reclaim_congested which affects wait_iff_congested. kswapd
+		 * will stall and start writing pages if the tail of the LRU
+		 * is all dirty unqueued pages.
+		 */
+		page_check_dirty_writeback(page, &dirty, &writeback);
+		if (dirty || writeback)
+			nr_dirty++;
+
+		if (dirty && !writeback)
+			nr_unqueued_dirty++;
+
+		/*
+		 * Treat this page as congested if the underlying BDI is or if
+		 * pages are cycling through the LRU so quickly that the
+		 * pages marked for immediate reclaim are making it to the
+		 * end of the LRU a second time.
+		 */
+		mapping = page_mapping(page);
+		if (((dirty || writeback) && mapping &&
+		     inode_write_congested(mapping->host)) ||
+		    (writeback && PageReclaim(page)))
+			nr_congested++;
+
+		/*
+		 * If a page at the tail of the LRU is under writeback, there
+		 * are three cases to consider.
+		 *
+		 * 1) If reclaim is encountering an excessive number of pages
+		 *    under writeback and this page is both under writeback and
+		 *    PageReclaim then it indicates that pages are being queued
+		 *    for IO but are being recycled through the LRU before the
+		 *    IO can complete. Waiting on the page itself risks an
+		 *    indefinite stall if it is impossible to writeback the
+		 *    page due to IO error or disconnected storage so instead
+		 *    note that the LRU is being scanned too quickly and the
+		 *    caller can stall after page list has been processed.
+		 *
+		 * 2) Global or new memcg reclaim encounters a page that is
+		 *    not marked for immediate reclaim, or the caller does not
+		 *    have __GFP_FS (or __GFP_IO if it's simply going to swap,
+		 *    not to fs). In this case mark the page for immediate
+		 *    reclaim and continue scanning.
+		 *
+		 *    Require may_enter_fs because we would wait on fs, which
+		 *    may not have submitted IO yet. And the loop driver might
+		 *    enter reclaim, and deadlock if it waits on a page for
+		 *    which it is needed to do the write (loop masks off
+		 *    __GFP_IO|__GFP_FS for this reason); but more thought
+		 *    would probably show more reasons.
+		 *
+		 * 3) Legacy memcg encounters a page that is already marked
+		 *    PageReclaim. memcg does not have any dirty pages
+		 *    throttling so we could easily OOM just because too many
+		 *    pages are in writeback and there is nothing else to
+		 *    reclaim. Wait for the writeback to complete.
+		 */
+		if (PageWriteback(page)) {
+			/* Case 1 above */
+			if (current_is_kswapd() &&
+			    PageReclaim(page) &&
+			    test_bit(ZONE_WRITEBACK, &zone->flags)) {
+				nr_immediate++;
+				goto keep_locked;
+
+			/* Case 2 above */
+			} else if (sane_reclaim(sc) ||
+			    !PageReclaim(page) || !may_enter_fs) {
+				/*
+				 * This is slightly racy - end_page_writeback()
+				 * might have just cleared PageReclaim, then
+				 * setting PageReclaim here end up interpreted
+				 * as PageReadahead - but that does not matter
+				 * enough to care.  What we do want is for this
+				 * page to have PageReclaim set next time memcg
+				 * reclaim reaches the tests above, so it will
+				 * then wait_on_page_writeback() to avoid OOM;
+				 * and it's also appropriate in global reclaim.
+				 */
+				SetPageReclaim(page);
+				nr_writeback++;
+				goto keep_locked;
+
+			/* Case 3 above */
+			} else {
+				unlock_page(page);
+				wait_on_page_writeback(page);
+				/* then go back and try same page again */
+				list_add_tail(&page->lru, page_list);
+				continue;
+			}
+		}
+
+		if (!force_reclaim)
+			references = page_check_references(page, sc);
+
+		switch (references) {
+		case PAGEREF_ACTIVATE:
+			goto activate_locked;
+		case PAGEREF_KEEP:
+			goto keep_locked;
+		case PAGEREF_RECLAIM:
+		case PAGEREF_RECLAIM_CLEAN:
+			; /* try to reclaim the page below */
+		}
+
+		/*
+		 * Anonymous process memory has backing store?
+		 * Try to allocate it some swap space here.
+		 */
+		if (PageAnon(page) && !PageSwapCache(page)) {
+			if (!(sc->gfp_mask & __GFP_IO))
+				goto keep_locked;
+			if (!add_to_swap(page, page_list))
+				goto activate_locked;
+			may_enter_fs = 1;
+
+			/* Adding to swap updated mapping */
+			mapping = page_mapping(page);
+		}
+
+		/*
+		 * The page is mapped into the page tables of one or more
+		 * processes. Try to unmap it here.
+		 */
+		if (page_mapped(page) && mapping) {
+			switch (try_to_unmap(page,
+					ttu_flags|TTU_BATCH_FLUSH)) {
+			case SWAP_FAIL:
+				goto activate_locked;
+			case SWAP_AGAIN:
+				goto keep_locked;
+			case SWAP_MLOCK:
+				goto cull_mlocked;
+			case SWAP_SUCCESS:
+				; /* try to free the page below */
+			}
+		}
+
+		if (PageDirty(page)) {
+			/*
+			 * Only kswapd can writeback filesystem pages to
+			 * avoid risk of stack overflow but only writeback
+			 * if many dirty pages have been encountered.
+			 */
+			if (page_is_file_cache(page) &&
+					(!current_is_kswapd() ||
+					 !test_bit(ZONE_DIRTY, &zone->flags))) {
+				/*
+				 * Immediately reclaim when written back.
+				 * Similar in principal to deactivate_page()
+				 * except we already have the page isolated
+				 * and know it's dirty
+				 */
+				inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE);
+				SetPageReclaim(page);
+
+				goto keep_locked;
+			}
+
+			if (references == PAGEREF_RECLAIM_CLEAN)
+				goto keep_locked;
+			if (!may_enter_fs)
+				goto keep_locked;
+			if (!sc->may_writepage)
+				goto keep_locked;
+
+			/*
+			 * Page is dirty. Flush the TLB if a writable entry
+			 * potentially exists to avoid CPU writes after IO
+			 * starts and then write it out here.
+			 */
+			try_to_unmap_flush_dirty();
+			switch (pageout(page, mapping, sc)) {
+			case PAGE_KEEP:
+				goto keep_locked;
+			case PAGE_ACTIVATE:
+				goto activate_locked;
+			case PAGE_SUCCESS:
+				if (PageWriteback(page))
+					goto keep;
+				if (PageDirty(page))
+					goto keep;
+
+				/*
+				 * A synchronous write - probably a ramdisk.  Go
+				 * ahead and try to reclaim the page.
+				 */
+				if (!trylock_page(page))
+					goto keep;
+				if (PageDirty(page) || PageWriteback(page))
+					goto keep_locked;
+				mapping = page_mapping(page);
+			case PAGE_CLEAN:
+				; /* try to free the page below */
+			}
+		}
+
+		/*
+		 * If the page has buffers, try to free the buffer mappings
+		 * associated with this page. If we succeed we try to free
+		 * the page as well.
+		 *
+		 * We do this even if the page is PageDirty().
+		 * try_to_release_page() does not perform I/O, but it is
+		 * possible for a page to have PageDirty set, but it is actually
+		 * clean (all its buffers are clean).  This happens if the
+		 * buffers were written out directly, with submit_bh(). ext3
+		 * will do this, as well as the blockdev mapping.
+		 * try_to_release_page() will discover that cleanness and will
+		 * drop the buffers and mark the page clean - it can be freed.
+		 *
+		 * Rarely, pages can have buffers and no ->mapping.  These are
+		 * the pages which were not successfully invalidated in
+		 * truncate_complete_page().  We try to drop those buffers here
+		 * and if that worked, and the page is no longer mapped into
+		 * process address space (page_count == 1) it can be freed.
+		 * Otherwise, leave the page on the LRU so it is swappable.
+		 */
+		if (page_has_private(page)) {
+			if (!try_to_release_page(page, sc->gfp_mask))
+				goto activate_locked;
+			if (!mapping && page_count(page) == 1) {
+				unlock_page(page);
+				if (put_page_testzero(page))
+					goto free_it;
+				else {
+					/*
+					 * rare race with speculative reference.
+					 * the speculative reference will free
+					 * this page shortly, so we may
+					 * increment nr_reclaimed here (and
+					 * leave it off the LRU).
+					 */
+					nr_reclaimed++;
+					continue;
+				}
+			}
+		}
+
+		if (!mapping || !__remove_mapping(mapping, page, true))
+			goto keep_locked;
+
+		/*
+		 * At this point, we have no other references and there is
+		 * no way to pick any more up (removed from LRU, removed
+		 * from pagecache). Can use non-atomic bitops now (and
+		 * we obviously don't have to worry about waking up a process
+		 * waiting on the page lock, because there are no references.
+		 */
+		__clear_page_locked(page);
+free_it:
+		nr_reclaimed++;
+
+		/*
+		 * Is there need to periodically free_page_list? It would
+		 * appear not as the counts should be low
+		 */
+		list_add(&page->lru, &free_pages);
+		continue;
+
+cull_mlocked:
+		if (PageSwapCache(page))
+			try_to_free_swap(page);
+		unlock_page(page);
+		list_add(&page->lru, &ret_pages);
+		continue;
+
+activate_locked:
+		/* Not a candidate for swapping, so reclaim swap space. */
+		if (PageSwapCache(page) && vm_swap_full())
+			try_to_free_swap(page);
+		VM_BUG_ON_PAGE(PageActive(page), page);
+		SetPageActive(page);
+		pgactivate++;
+keep_locked:
+		unlock_page(page);
+keep:
+		list_add(&page->lru, &ret_pages);
+		VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page);
+	}
+
+	mem_cgroup_uncharge_list(&free_pages);
+	try_to_unmap_flush();
+	free_hot_cold_page_list(&free_pages, true);
+
+	list_splice(&ret_pages, page_list);
+	count_vm_events(PGACTIVATE, pgactivate);
+
+	*ret_nr_dirty += nr_dirty;
+	*ret_nr_congested += nr_congested;
+	*ret_nr_unqueued_dirty += nr_unqueued_dirty;
+	*ret_nr_writeback += nr_writeback;
+	*ret_nr_immediate += nr_immediate;
+	return nr_reclaimed;
+}
+
+unsigned long reclaim_clean_pages_from_list(struct zone *zone,
+					    struct list_head *page_list)
+{
+	struct scan_control sc = {
+		.gfp_mask = GFP_KERNEL,
+		.priority = DEF_PRIORITY,
+		.may_unmap = 1,
+	};
+	unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;
+	struct page *page, *next;
+	LIST_HEAD(clean_pages);
+
+	list_for_each_entry_safe(page, next, page_list, lru) {
+		if (page_is_file_cache(page) && !PageDirty(page) &&
+		    !isolated_balloon_page(page)) {
+			ClearPageActive(page);
+			list_move(&page->lru, &clean_pages);
+		}
+	}
+
+	ret = shrink_page_list(&clean_pages, zone, &sc,
+			TTU_UNMAP|TTU_IGNORE_ACCESS,
+			&dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
+	list_splice(&clean_pages, page_list);
+	mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
+	return ret;
+}
+
+/*
+ * Attempt to remove the specified page from its LRU.  Only take this page
+ * if it is of the appropriate PageActive status.  Pages which are being
+ * freed elsewhere are also ignored.
+ *
+ * page:	page to consider
+ * mode:	one of the LRU isolation modes defined above
+ *
+ * returns 0 on success, -ve errno on failure.
+ */
+int __isolate_lru_page(struct page *page, isolate_mode_t mode)
+{
+	int ret = -EINVAL;
+
+	/* Only take pages on the LRU. */
+	if (!PageLRU(page))
+		return ret;
+
+	/* Compaction should not handle unevictable pages but CMA can do so */
+	if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))
+		return ret;
+
+	ret = -EBUSY;
+
+	/*
+	 * To minimise LRU disruption, the caller can indicate that it only
+	 * wants to isolate pages it will be able to operate on without
+	 * blocking - clean pages for the most part.
+	 *
+	 * ISOLATE_CLEAN means that only clean pages should be isolated. This
+	 * is used by reclaim when it is cannot write to backing storage
+	 *
+	 * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages
+	 * that it is possible to migrate without blocking
+	 */
+	if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) {
+		/* All the caller can do on PageWriteback is block */
+		if (PageWriteback(page))
+			return ret;
+
+		if (PageDirty(page)) {
+			struct address_space *mapping;
+
+			/* ISOLATE_CLEAN means only clean pages */
+			if (mode & ISOLATE_CLEAN)
+				return ret;
+
+			/*
+			 * Only pages without mappings or that have a
+			 * ->migratepage callback are possible to migrate
+			 * without blocking
+			 */
+			mapping = page_mapping(page);
+			if (mapping && !mapping->a_ops->migratepage)
+				return ret;
+		}
+	}
+
+	if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
+		return ret;
+
+	if (likely(get_page_unless_zero(page))) {
+		/*
+		 * Be careful not to clear PageLRU until after we're
+		 * sure the page is not being freed elsewhere -- the
+		 * page release code relies on it.
+		 */
+		ClearPageLRU(page);
+		ret = 0;
+	}
+
+	return ret;
+}
+
+/*
+ * zone->lru_lock is heavily contended.  Some of the functions that
+ * shrink the lists perform better by taking out a batch of pages
+ * and working on them outside the LRU lock.
+ *
+ * For pagecache intensive workloads, this function is the hottest
+ * spot in the kernel (apart from copy_*_user functions).
+ *
+ * Appropriate locks must be held before calling this function.
+ *
+ * @nr_to_scan:	The number of pages to look through on the list.
+ * @lruvec:	The LRU vector to pull pages from.
+ * @dst:	The temp list to put pages on to.
+ * @nr_scanned:	The number of pages that were scanned.
+ * @sc:		The scan_control struct for this reclaim session
+ * @mode:	One of the LRU isolation modes
+ * @lru:	LRU list id for isolating
+ *
+ * returns how many pages were moved onto *@dst.
+ */
+static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
+		struct lruvec *lruvec, struct list_head *dst,
+		unsigned long *nr_scanned, struct scan_control *sc,
+		isolate_mode_t mode, enum lru_list lru)
+{
+	struct list_head *src = &lruvec->lists[lru];
+	unsigned long nr_taken = 0;
+	unsigned long scan;
+
+	for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
+					!list_empty(src); scan++) {
+		struct page *page;
+		int nr_pages;
+
+		page = lru_to_page(src);
+		prefetchw_prev_lru_page(page, src, flags);
+
+		VM_BUG_ON_PAGE(!PageLRU(page), page);
+
+		switch (__isolate_lru_page(page, mode)) {
+		case 0:
+			nr_pages = hpage_nr_pages(page);
+			mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
+			list_move(&page->lru, dst);
+			nr_taken += nr_pages;
+			break;
+
+		case -EBUSY:
+			/* else it is being freed elsewhere */
+			list_move(&page->lru, src);
+			continue;
+
+		default:
+			BUG();
+		}
+	}
+
+	*nr_scanned = scan;
+	trace_mm_vmscan_lru_isolate(sc->order, nr_to_scan, scan,
+				    nr_taken, mode, is_file_lru(lru));
+	return nr_taken;
+}
+
+/**
+ * isolate_lru_page - tries to isolate a page from its LRU list
+ * @page: page to isolate from its LRU list
+ *
+ * Isolates a @page from an LRU list, clears PageLRU and adjusts the
+ * vmstat statistic corresponding to whatever LRU list the page was on.
+ *
+ * Returns 0 if the page was removed from an LRU list.
+ * Returns -EBUSY if the page was not on an LRU list.
+ *
+ * The returned page will have PageLRU() cleared.  If it was found on
+ * the active list, it will have PageActive set.  If it was found on
+ * the unevictable list, it will have the PageUnevictable bit set. That flag
+ * may need to be cleared by the caller before letting the page go.
+ *
+ * The vmstat statistic corresponding to the list on which the page was
+ * found will be decremented.
+ *
+ * Restrictions:
+ * (1) Must be called with an elevated refcount on the page. This is a
+ *     fundamentnal difference from isolate_lru_pages (which is called
+ *     without a stable reference).
+ * (2) the lru_lock must not be held.
+ * (3) interrupts must be enabled.
+ */
+int isolate_lru_page(struct page *page)
+{
+	int ret = -EBUSY;
+
+	VM_BUG_ON_PAGE(!page_count(page), page);
+
+	if (PageLRU(page)) {
+		struct zone *zone = page_zone(page);
+		struct lruvec *lruvec;
+
+		spin_lock_irq(&zone->lru_lock);
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+		if (PageLRU(page)) {
+			int lru = page_lru(page);
+			get_page(page);
+			ClearPageLRU(page);
+			del_page_from_lru_list(page, lruvec, lru);
+			ret = 0;
+		}
+		spin_unlock_irq(&zone->lru_lock);
+	}
+	return ret;
+}
+
+/*
+ * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and
+ * then get resheduled. When there are massive number of tasks doing page
+ * allocation, such sleeping direct reclaimers may keep piling up on each CPU,
+ * the LRU list will go small and be scanned faster than necessary, leading to
+ * unnecessary swapping, thrashing and OOM.
+ */
+static int too_many_isolated(struct zone *zone, int file,
+		struct scan_control *sc)
+{
+	unsigned long inactive, isolated;
+
+	if (current_is_kswapd())
+		return 0;
+
+	if (!sane_reclaim(sc))
+		return 0;
+
+	if (file) {
+		inactive = zone_page_state(zone, NR_INACTIVE_FILE);
+		isolated = zone_page_state(zone, NR_ISOLATED_FILE);
+	} else {
+		inactive = zone_page_state(zone, NR_INACTIVE_ANON);
+		isolated = zone_page_state(zone, NR_ISOLATED_ANON);
+	}
+
+	/*
+	 * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they
+	 * won't get blocked by normal direct-reclaimers, forming a circular
+	 * deadlock.
+	 */
+	if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
+		inactive >>= 3;
+
+	return isolated > inactive;
+}
+
+static noinline_for_stack void
+putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
+{
+	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
+	struct zone *zone = lruvec_zone(lruvec);
+	LIST_HEAD(pages_to_free);
+
+	/*
+	 * Put back any unfreeable pages.
+	 */
+	while (!list_empty(page_list)) {
+		struct page *page = lru_to_page(page_list);
+		int lru;
+
+		VM_BUG_ON_PAGE(PageLRU(page), page);
+		list_del(&page->lru);
+		if (unlikely(!page_evictable(page))) {
+			spin_unlock_irq(&zone->lru_lock);
+			putback_lru_page(page);
+			spin_lock_irq(&zone->lru_lock);
+			continue;
+		}
+
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+
+		SetPageLRU(page);
+		lru = page_lru(page);
+		add_page_to_lru_list(page, lruvec, lru);
+
+		if (is_active_lru(lru)) {
+			int file = is_file_lru(lru);
+			int numpages = hpage_nr_pages(page);
+			reclaim_stat->recent_rotated[file] += numpages;
+		}
+		if (put_page_testzero(page)) {
+			__ClearPageLRU(page);
+			__ClearPageActive(page);
+			del_page_from_lru_list(page, lruvec, lru);
+
+			if (unlikely(PageCompound(page))) {
+				spin_unlock_irq(&zone->lru_lock);
+				mem_cgroup_uncharge(page);
+				(*get_compound_page_dtor(page))(page);
+				spin_lock_irq(&zone->lru_lock);
+			} else
+				list_add(&page->lru, &pages_to_free);
+		}
+	}
+
+	/*
+	 * To save our caller's stack, now use input list for pages to free.
+	 */
+	list_splice(&pages_to_free, page_list);
+}
+
+/*
+ * If a kernel thread (such as nfsd for loop-back mounts) services
+ * a backing device by writing to the page cache it sets PF_LESS_THROTTLE.
+ * In that case we should only throttle if the backing device it is
+ * writing to is congested.  In other cases it is safe to throttle.
+ */
+static int current_may_throttle(void)
+{
+	return !(current->flags & PF_LESS_THROTTLE) ||
+		current->backing_dev_info == NULL ||
+		bdi_write_congested(current->backing_dev_info);
+}
+
+/*
+ * shrink_inactive_list() is a helper for shrink_zone().  It returns the number
+ * of reclaimed pages
+ */
+static noinline_for_stack unsigned long
+shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
+		     struct scan_control *sc, enum lru_list lru)
+{
+	LIST_HEAD(page_list);
+	unsigned long nr_scanned;
+	unsigned long nr_reclaimed = 0;
+	unsigned long nr_taken;
+	unsigned long nr_dirty = 0;
+	unsigned long nr_congested = 0;
+	unsigned long nr_unqueued_dirty = 0;
+	unsigned long nr_writeback = 0;
+	unsigned long nr_immediate = 0;
+	isolate_mode_t isolate_mode = 0;
+	int file = is_file_lru(lru);
+	struct zone *zone = lruvec_zone(lruvec);
+	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
+
+	while (unlikely(too_many_isolated(zone, file, sc))) {
+		congestion_wait(BLK_RW_ASYNC, HZ/10);
+
+		/* We are about to die and free our memory. Return now. */
+		if (fatal_signal_pending(current))
+			return SWAP_CLUSTER_MAX;
+	}
+
+	lru_add_drain();
+
+	if (!sc->may_unmap)
+		isolate_mode |= ISOLATE_UNMAPPED;
+	if (!sc->may_writepage)
+		isolate_mode |= ISOLATE_CLEAN;
+
+	spin_lock_irq(&zone->lru_lock);
+
+	nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list,
+				     &nr_scanned, sc, isolate_mode, lru);
+
+	__mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
+	__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
+
+	if (global_reclaim(sc)) {
+		__mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
+		if (current_is_kswapd())
+			__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned);
+		else
+			__count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned);
+	}
+	spin_unlock_irq(&zone->lru_lock);
+
+	if (nr_taken == 0)
+		return 0;
+
+	nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,
+				&nr_dirty, &nr_unqueued_dirty, &nr_congested,
+				&nr_writeback, &nr_immediate,
+				false);
+
+	spin_lock_irq(&zone->lru_lock);
+
+	reclaim_stat->recent_scanned[file] += nr_taken;
+
+	if (global_reclaim(sc)) {
+		if (current_is_kswapd())
+			__count_zone_vm_events(PGSTEAL_KSWAPD, zone,
+					       nr_reclaimed);
+		else
+			__count_zone_vm_events(PGSTEAL_DIRECT, zone,
+					       nr_reclaimed);
+	}
+
+	putback_inactive_pages(lruvec, &page_list);
+
+	__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
+
+	spin_unlock_irq(&zone->lru_lock);
+
+	mem_cgroup_uncharge_list(&page_list);
+	free_hot_cold_page_list(&page_list, true);
+
+	/*
+	 * If reclaim is isolating dirty pages under writeback, it implies
+	 * that the long-lived page allocation rate is exceeding the page
+	 * laundering rate. Either the global limits are not being effective
+	 * at throttling processes due to the page distribution throughout
+	 * zones or there is heavy usage of a slow backing device. The
+	 * only option is to throttle from reclaim context which is not ideal
+	 * as there is no guarantee the dirtying process is throttled in the
+	 * same way balance_dirty_pages() manages.
+	 *
+	 * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number
+	 * of pages under pages flagged for immediate reclaim and stall if any
+	 * are encountered in the nr_immediate check below.
+	 */
+	if (nr_writeback && nr_writeback == nr_taken)
+		set_bit(ZONE_WRITEBACK, &zone->flags);
+
+	/*
+	 * Legacy memcg will stall in page writeback so avoid forcibly
+	 * stalling here.
+	 */
+	if (sane_reclaim(sc)) {
+		/*
+		 * Tag a zone as congested if all the dirty pages scanned were
+		 * backed by a congested BDI and wait_iff_congested will stall.
+		 */
+		if (nr_dirty && nr_dirty == nr_congested)
+			set_bit(ZONE_CONGESTED, &zone->flags);
+
+		/*
+		 * If dirty pages are scanned that are not queued for IO, it
+		 * implies that flushers are not keeping up. In this case, flag
+		 * the zone ZONE_DIRTY and kswapd will start writing pages from
+		 * reclaim context.
+		 */
+		if (nr_unqueued_dirty == nr_taken)
+			set_bit(ZONE_DIRTY, &zone->flags);
+
+		/*
+		 * If kswapd scans pages marked marked for immediate
+		 * reclaim and under writeback (nr_immediate), it implies
+		 * that pages are cycling through the LRU faster than
+		 * they are written so also forcibly stall.
+		 */
+		if (nr_immediate && current_may_throttle())
+			congestion_wait(BLK_RW_ASYNC, HZ/10);
+	}
+
+	/*
+	 * Stall direct reclaim for IO completions if underlying BDIs or zone
+	 * is congested. Allow kswapd to continue until it starts encountering
+	 * unqueued dirty pages or cycling through the LRU too quickly.
+	 */
+	if (!sc->hibernation_mode && !current_is_kswapd() &&
+	    current_may_throttle())
+		wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
+
+	trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
+		zone_idx(zone),
+		nr_scanned, nr_reclaimed,
+		sc->priority,
+		trace_shrink_flags(file));
+	return nr_reclaimed;
+}
+
+/*
+ * This moves pages from the active list to the inactive list.
+ *
+ * We move them the other way if the page is referenced by one or more
+ * processes, from rmap.
+ *
+ * If the pages are mostly unmapped, the processing is fast and it is
+ * appropriate to hold zone->lru_lock across the whole operation.  But if
+ * the pages are mapped, the processing is slow (page_referenced()) so we
+ * should drop zone->lru_lock around each page.  It's impossible to balance
+ * this, so instead we remove the pages from the LRU while processing them.
+ * It is safe to rely on PG_active against the non-LRU pages in here because
+ * nobody will play with that bit on a non-LRU page.
+ *
+ * The downside is that we have to touch page->_count against each page.
+ * But we had to alter page->flags anyway.
+ */
+
+static void move_active_pages_to_lru(struct lruvec *lruvec,
+				     struct list_head *list,
+				     struct list_head *pages_to_free,
+				     enum lru_list lru)
+{
+	struct zone *zone = lruvec_zone(lruvec);
+	unsigned long pgmoved = 0;
+	struct page *page;
+	int nr_pages;
+
+	while (!list_empty(list)) {
+		page = lru_to_page(list);
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+
+		VM_BUG_ON_PAGE(PageLRU(page), page);
+		SetPageLRU(page);
+
+		nr_pages = hpage_nr_pages(page);
+		mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
+		list_move(&page->lru, &lruvec->lists[lru]);
+		pgmoved += nr_pages;
+
+		if (put_page_testzero(page)) {
+			__ClearPageLRU(page);
+			__ClearPageActive(page);
+			del_page_from_lru_list(page, lruvec, lru);
+
+			if (unlikely(PageCompound(page))) {
+				spin_unlock_irq(&zone->lru_lock);
+				mem_cgroup_uncharge(page);
+				(*get_compound_page_dtor(page))(page);
+				spin_lock_irq(&zone->lru_lock);
+			} else
+				list_add(&page->lru, pages_to_free);
+		}
+	}
+	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
+	if (!is_active_lru(lru))
+		__count_vm_events(PGDEACTIVATE, pgmoved);
+}
+
+static void shrink_active_list(unsigned long nr_to_scan,
+			       struct lruvec *lruvec,
+			       struct scan_control *sc,
+			       enum lru_list lru)
+{
+	unsigned long nr_taken;
+	unsigned long nr_scanned;
+	unsigned long vm_flags;
+	LIST_HEAD(l_hold);	/* The pages which were snipped off */
+	LIST_HEAD(l_active);
+	LIST_HEAD(l_inactive);
+	struct page *page;
+	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
+	unsigned long nr_rotated = 0;
+	isolate_mode_t isolate_mode = 0;
+	int file = is_file_lru(lru);
+	struct zone *zone = lruvec_zone(lruvec);
+
+	lru_add_drain();
+
+	if (!sc->may_unmap)
+		isolate_mode |= ISOLATE_UNMAPPED;
+	if (!sc->may_writepage)
+		isolate_mode |= ISOLATE_CLEAN;
+
+	spin_lock_irq(&zone->lru_lock);
+
+	nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
+				     &nr_scanned, sc, isolate_mode, lru);
+	if (global_reclaim(sc))
+		__mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
+
+	reclaim_stat->recent_scanned[file] += nr_taken;
+
+	__count_zone_vm_events(PGREFILL, zone, nr_scanned);
+	__mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
+	__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
+	spin_unlock_irq(&zone->lru_lock);
+
+	while (!list_empty(&l_hold)) {
+		cond_resched();
+		page = lru_to_page(&l_hold);
+		list_del(&page->lru);
+
+		if (unlikely(!page_evictable(page))) {
+			putback_lru_page(page);
+			continue;
+		}
+
+		if (unlikely(buffer_heads_over_limit)) {
+			if (page_has_private(page) && trylock_page(page)) {
+				if (page_has_private(page))
+					try_to_release_page(page, 0);
+				unlock_page(page);
+			}
+		}
+
+		if (page_referenced(page, 0, sc->target_mem_cgroup,
+				    &vm_flags)) {
+			nr_rotated += hpage_nr_pages(page);
+			/*
+			 * Identify referenced, file-backed active pages and
+			 * give them one more trip around the active list. So
+			 * that executable code get better chances to stay in
+			 * memory under moderate memory pressure.  Anon pages
+			 * are not likely to be evicted by use-once streaming
+			 * IO, plus JVM can create lots of anon VM_EXEC pages,
+			 * so we ignore them here.
+			 */
+			if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
+				list_add(&page->lru, &l_active);
+				continue;
+			}
+		}
+
+		ClearPageActive(page);	/* we are de-activating */
+		list_add(&page->lru, &l_inactive);
+	}
+
+	/*
+	 * Move pages back to the lru list.
+	 */
+	spin_lock_irq(&zone->lru_lock);
+	/*
+	 * Count referenced pages from currently used mappings as rotated,
+	 * even though only some of them are actually re-activated.  This
+	 * helps balance scan pressure between file and anonymous pages in
+	 * get_scan_count.
+	 */
+	reclaim_stat->recent_rotated[file] += nr_rotated;
+
+	move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
+	move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
+	__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
+	spin_unlock_irq(&zone->lru_lock);
+
+	mem_cgroup_uncharge_list(&l_hold);
+	free_hot_cold_page_list(&l_hold, true);
+}
+
+#ifdef CONFIG_SWAP
+static bool inactive_anon_is_low_global(struct zone *zone)
+{
+	unsigned long active, inactive;
+
+	active = zone_page_state(zone, NR_ACTIVE_ANON);
+	inactive = zone_page_state(zone, NR_INACTIVE_ANON);
+
+	return inactive * zone->inactive_ratio < active;
+}
+
+/**
+ * inactive_anon_is_low - check if anonymous pages need to be deactivated
+ * @lruvec: LRU vector to check
+ *
+ * Returns true if the zone does not have enough inactive anon pages,
+ * meaning some active anon pages need to be deactivated.
+ */
+static bool inactive_anon_is_low(struct lruvec *lruvec)
+{
+	/*
+	 * If we don't have swap space, anonymous page deactivation
+	 * is pointless.
+	 */
+	if (!total_swap_pages)
+		return false;
+
+	if (!mem_cgroup_disabled())
+		return mem_cgroup_inactive_anon_is_low(lruvec);
+
+	return inactive_anon_is_low_global(lruvec_zone(lruvec));
+}
+#else
+static inline bool inactive_anon_is_low(struct lruvec *lruvec)
+{
+	return false;
+}
+#endif
+
+/**
+ * inactive_file_is_low - check if file pages need to be deactivated
+ * @lruvec: LRU vector to check
+ *
+ * When the system is doing streaming IO, memory pressure here
+ * ensures that active file pages get deactivated, until more
+ * than half of the file pages are on the inactive list.
+ *
+ * Once we get to that situation, protect the system's working
+ * set from being evicted by disabling active file page aging.
+ *
+ * This uses a different ratio than the anonymous pages, because
+ * the page cache uses a use-once replacement algorithm.
+ */
+static bool inactive_file_is_low(struct lruvec *lruvec)
+{
+	unsigned long inactive;
+	unsigned long active;
+
+	inactive = get_lru_size(lruvec, LRU_INACTIVE_FILE);
+	active = get_lru_size(lruvec, LRU_ACTIVE_FILE);
+
+	return active > inactive;
+}
+
+static bool inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
+{
+	if (is_file_lru(lru))
+		return inactive_file_is_low(lruvec);
+	else
+		return inactive_anon_is_low(lruvec);
+}
+
+static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
+				 struct lruvec *lruvec, struct scan_control *sc)
+{
+	if (is_active_lru(lru)) {
+		if (inactive_list_is_low(lruvec, lru))
+			shrink_active_list(nr_to_scan, lruvec, sc, lru);
+		return 0;
+	}
+
+	return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
+}
+
+enum scan_balance {
+	SCAN_EQUAL,
+	SCAN_FRACT,
+	SCAN_ANON,
+	SCAN_FILE,
+};
+
+/*
+ * Determine how aggressively the anon and file LRU lists should be
+ * scanned.  The relative value of each set of LRU lists is determined
+ * by looking at the fraction of the pages scanned we did rotate back
+ * onto the active list instead of evict.
+ *
+ * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
+ * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
+ */
+static void get_scan_count(struct lruvec *lruvec, int swappiness,
+			   struct scan_control *sc, unsigned long *nr,
+			   unsigned long *lru_pages)
+{
+	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
+	u64 fraction[2];
+	u64 denominator = 0;	/* gcc */
+	struct zone *zone = lruvec_zone(lruvec);
+	unsigned long anon_prio, file_prio;
+	enum scan_balance scan_balance;
+	unsigned long anon, file;
+	bool force_scan = false;
+	unsigned long ap, fp;
+	enum lru_list lru;
+	bool some_scanned;
+	int pass;
+
+	/*
+	 * If the zone or memcg is small, nr[l] can be 0.  This
+	 * results in no scanning on this priority and a potential
+	 * priority drop.  Global direct reclaim can go to the next
+	 * zone and tends to have no problems. Global kswapd is for
+	 * zone balancing and it needs to scan a minimum amount. When
+	 * reclaiming for a memcg, a priority drop can cause high
+	 * latencies, so it's better to scan a minimum amount there as
+	 * well.
+	 */
+	if (current_is_kswapd()) {
+		if (!zone_reclaimable(zone))
+			force_scan = true;
+		if (!mem_cgroup_lruvec_online(lruvec))
+			force_scan = true;
+	}
+	if (!global_reclaim(sc))
+		force_scan = true;
+
+	/* If we have no swap space, do not bother scanning anon pages. */
+	if (!sc->may_swap || (get_nr_swap_pages() <= 0)) {
+		scan_balance = SCAN_FILE;
+		goto out;
+	}
+
+	/*
+	 * Global reclaim will swap to prevent OOM even with no
+	 * swappiness, but memcg users want to use this knob to
+	 * disable swapping for individual groups completely when
+	 * using the memory controller's swap limit feature would be
+	 * too expensive.
+	 */
+	if (!global_reclaim(sc) && !swappiness) {
+		scan_balance = SCAN_FILE;
+		goto out;
+	}
+
+	/*
+	 * Do not apply any pressure balancing cleverness when the
+	 * system is close to OOM, scan both anon and file equally
+	 * (unless the swappiness setting disagrees with swapping).
+	 */
+	if (!sc->priority && swappiness) {
+		scan_balance = SCAN_EQUAL;
+		goto out;
+	}
+
+	/*
+	 * Prevent the reclaimer from falling into the cache trap: as
+	 * cache pages start out inactive, every cache fault will tip
+	 * the scan balance towards the file LRU.  And as the file LRU
+	 * shrinks, so does the window for rotation from references.
+	 * This means we have a runaway feedback loop where a tiny
+	 * thrashing file LRU becomes infinitely more attractive than
+	 * anon pages.  Try to detect this based on file LRU size.
+	 */
+	if (global_reclaim(sc)) {
+		unsigned long zonefile;
+		unsigned long zonefree;
+
+		zonefree = zone_page_state(zone, NR_FREE_PAGES);
+		zonefile = zone_page_state(zone, NR_ACTIVE_FILE) +
+			   zone_page_state(zone, NR_INACTIVE_FILE);
+
+		if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) {
+			scan_balance = SCAN_ANON;
+			goto out;
+		}
+	}
+
+	/*
+	 * There is enough inactive page cache, do not reclaim
+	 * anything from the anonymous working set right now.
+	 */
+	if (!inactive_file_is_low(lruvec)) {
+		scan_balance = SCAN_FILE;
+		goto out;
+	}
+
+	scan_balance = SCAN_FRACT;
+
+	/*
+	 * With swappiness at 100, anonymous and file have the same priority.
+	 * This scanning priority is essentially the inverse of IO cost.
+	 */
+	anon_prio = swappiness;
+	file_prio = 200 - anon_prio;
+
+	/*
+	 * OK, so we have swap space and a fair amount of page cache
+	 * pages.  We use the recently rotated / recently scanned
+	 * ratios to determine how valuable each cache is.
+	 *
+	 * Because workloads change over time (and to avoid overflow)
+	 * we keep these statistics as a floating average, which ends
+	 * up weighing recent references more than old ones.
+	 *
+	 * anon in [0], file in [1]
+	 */
+
+	anon  = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
+		get_lru_size(lruvec, LRU_INACTIVE_ANON);
+	file  = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
+		get_lru_size(lruvec, LRU_INACTIVE_FILE);
+
+	spin_lock_irq(&zone->lru_lock);
+	if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
+		reclaim_stat->recent_scanned[0] /= 2;
+		reclaim_stat->recent_rotated[0] /= 2;
+	}
+
+	if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
+		reclaim_stat->recent_scanned[1] /= 2;
+		reclaim_stat->recent_rotated[1] /= 2;
+	}
+
+	/*
+	 * The amount of pressure on anon vs file pages is inversely
+	 * proportional to the fraction of recently scanned pages on
+	 * each list that were recently referenced and in active use.
+	 */
+	ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1);
+	ap /= reclaim_stat->recent_rotated[0] + 1;
+
+	fp = file_prio * (reclaim_stat->recent_scanned[1] + 1);
+	fp /= reclaim_stat->recent_rotated[1] + 1;
+	spin_unlock_irq(&zone->lru_lock);
+
+	fraction[0] = ap;
+	fraction[1] = fp;
+	denominator = ap + fp + 1;
+out:
+	some_scanned = false;
+	/* Only use force_scan on second pass. */
+	for (pass = 0; !some_scanned && pass < 2; pass++) {
+		*lru_pages = 0;
+		for_each_evictable_lru(lru) {
+			int file = is_file_lru(lru);
+			unsigned long size;
+			unsigned long scan;
+
+			size = get_lru_size(lruvec, lru);
+			scan = size >> sc->priority;
+
+			if (!scan && pass && force_scan)
+				scan = min(size, SWAP_CLUSTER_MAX);
+
+			switch (scan_balance) {
+			case SCAN_EQUAL:
+				/* Scan lists relative to size */
+				break;
+			case SCAN_FRACT:
+				/*
+				 * Scan types proportional to swappiness and
+				 * their relative recent reclaim efficiency.
+				 */
+				scan = div64_u64(scan * fraction[file],
+							denominator);
+				break;
+			case SCAN_FILE:
+			case SCAN_ANON:
+				/* Scan one type exclusively */
+				if ((scan_balance == SCAN_FILE) != file) {
+					size = 0;
+					scan = 0;
+				}
+				break;
+			default:
+				/* Look ma, no brain */
+				BUG();
+			}
+
+			*lru_pages += size;
+			nr[lru] = scan;
+
+			/*
+			 * Skip the second pass and don't force_scan,
+			 * if we found something to scan.
+			 */
+			some_scanned |= !!scan;
+		}
+	}
+}
+
+/*
+ * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
+ */
+static void shrink_lruvec(struct lruvec *lruvec, int swappiness,
+			  struct scan_control *sc, unsigned long *lru_pages)
+{
+	unsigned long nr[NR_LRU_LISTS];
+	unsigned long targets[NR_LRU_LISTS];
+	unsigned long nr_to_scan;
+	enum lru_list lru;
+	unsigned long nr_reclaimed = 0;
+	unsigned long nr_to_reclaim = sc->nr_to_reclaim;
+	struct blk_plug plug;
+	bool scan_adjusted;
+
+	get_scan_count(lruvec, swappiness, sc, nr, lru_pages);
+
+	/* Record the original scan target for proportional adjustments later */
+	memcpy(targets, nr, sizeof(nr));
+
+	/*
+	 * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
+	 * event that can occur when there is little memory pressure e.g.
+	 * multiple streaming readers/writers. Hence, we do not abort scanning
+	 * when the requested number of pages are reclaimed when scanning at
+	 * DEF_PRIORITY on the assumption that the fact we are direct
+	 * reclaiming implies that kswapd is not keeping up and it is best to
+	 * do a batch of work at once. For memcg reclaim one check is made to
+	 * abort proportional reclaim if either the file or anon lru has already
+	 * dropped to zero at the first pass.
+	 */
+	scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() &&
+			 sc->priority == DEF_PRIORITY);
+
+	blk_start_plug(&plug);
+	while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
+					nr[LRU_INACTIVE_FILE]) {
+		unsigned long nr_anon, nr_file, percentage;
+		unsigned long nr_scanned;
+
+		for_each_evictable_lru(lru) {
+			if (nr[lru]) {
+				nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX);
+				nr[lru] -= nr_to_scan;
+
+				nr_reclaimed += shrink_list(lru, nr_to_scan,
+							    lruvec, sc);
+			}
+		}
+
+		if (nr_reclaimed < nr_to_reclaim || scan_adjusted)
+			continue;
+
+		/*
+		 * For kswapd and memcg, reclaim at least the number of pages
+		 * requested. Ensure that the anon and file LRUs are scanned
+		 * proportionally what was requested by get_scan_count(). We
+		 * stop reclaiming one LRU and reduce the amount scanning
+		 * proportional to the original scan target.
+		 */
+		nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE];
+		nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON];
+
+		/*
+		 * It's just vindictive to attack the larger once the smaller
+		 * has gone to zero.  And given the way we stop scanning the
+		 * smaller below, this makes sure that we only make one nudge
+		 * towards proportionality once we've got nr_to_reclaim.
+		 */
+		if (!nr_file || !nr_anon)
+			break;
+
+		if (nr_file > nr_anon) {
+			unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
+						targets[LRU_ACTIVE_ANON] + 1;
+			lru = LRU_BASE;
+			percentage = nr_anon * 100 / scan_target;
+		} else {
+			unsigned long scan_target = targets[LRU_INACTIVE_FILE] +
+						targets[LRU_ACTIVE_FILE] + 1;
+			lru = LRU_FILE;
+			percentage = nr_file * 100 / scan_target;
+		}
+
+		/* Stop scanning the smaller of the LRU */
+		nr[lru] = 0;
+		nr[lru + LRU_ACTIVE] = 0;
+
+		/*
+		 * Recalculate the other LRU scan count based on its original
+		 * scan target and the percentage scanning already complete
+		 */
+		lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE;
+		nr_scanned = targets[lru] - nr[lru];
+		nr[lru] = targets[lru] * (100 - percentage) / 100;
+		nr[lru] -= min(nr[lru], nr_scanned);
+
+		lru += LRU_ACTIVE;
+		nr_scanned = targets[lru] - nr[lru];
+		nr[lru] = targets[lru] * (100 - percentage) / 100;
+		nr[lru] -= min(nr[lru], nr_scanned);
+
+		scan_adjusted = true;
+	}
+	blk_finish_plug(&plug);
+	sc->nr_reclaimed += nr_reclaimed;
+
+	/*
+	 * Even if we did not try to evict anon pages at all, we want to
+	 * rebalance the anon lru active/inactive ratio.
+	 */
+	if (inactive_anon_is_low(lruvec))
+		shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
+				   sc, LRU_ACTIVE_ANON);
+
+	throttle_vm_writeout(sc->gfp_mask);
+}
+
+/* Use reclaim/compaction for costly allocs or under memory pressure */
+static bool in_reclaim_compaction(struct scan_control *sc)
+{
+	if (IS_ENABLED(CONFIG_COMPACTION) && sc->order &&
+			(sc->order > PAGE_ALLOC_COSTLY_ORDER ||
+			 sc->priority < DEF_PRIORITY - 2))
+		return true;
+
+	return false;
+}
+
+/*
+ * Reclaim/compaction is used for high-order allocation requests. It reclaims
+ * order-0 pages before compacting the zone. should_continue_reclaim() returns
+ * true if more pages should be reclaimed such that when the page allocator
+ * calls try_to_compact_zone() that it will have enough free pages to succeed.
+ * It will give up earlier than that if there is difficulty reclaiming pages.
+ */
+static inline bool should_continue_reclaim(struct zone *zone,
+					unsigned long nr_reclaimed,
+					unsigned long nr_scanned,
+					struct scan_control *sc)
+{
+	unsigned long pages_for_compaction;
+	unsigned long inactive_lru_pages;
+
+	/* If not in reclaim/compaction mode, stop */
+	if (!in_reclaim_compaction(sc))
+		return false;
+
+	/* Consider stopping depending on scan and reclaim activity */
+	if (sc->gfp_mask & __GFP_REPEAT) {
+		/*
+		 * For __GFP_REPEAT allocations, stop reclaiming if the
+		 * full LRU list has been scanned and we are still failing
+		 * to reclaim pages. This full LRU scan is potentially
+		 * expensive but a __GFP_REPEAT caller really wants to succeed
+		 */
+		if (!nr_reclaimed && !nr_scanned)
+			return false;
+	} else {
+		/*
+		 * For non-__GFP_REPEAT allocations which can presumably
+		 * fail without consequence, stop if we failed to reclaim
+		 * any pages from the last SWAP_CLUSTER_MAX number of
+		 * pages that were scanned. This will return to the
+		 * caller faster at the risk reclaim/compaction and
+		 * the resulting allocation attempt fails
+		 */
+		if (!nr_reclaimed)
+			return false;
+	}
+
+	/*
+	 * If we have not reclaimed enough pages for compaction and the
+	 * inactive lists are large enough, continue reclaiming
+	 */
+	pages_for_compaction = (2UL << sc->order);
+	inactive_lru_pages = zone_page_state(zone, NR_INACTIVE_FILE);
+	if (get_nr_swap_pages() > 0)
+		inactive_lru_pages += zone_page_state(zone, NR_INACTIVE_ANON);
+	if (sc->nr_reclaimed < pages_for_compaction &&
+			inactive_lru_pages > pages_for_compaction)
+		return true;
+
+	/* If compaction would go ahead or the allocation would succeed, stop */
+	switch (compaction_suitable(zone, sc->order, 0, 0)) {
+	case COMPACT_PARTIAL:
+	case COMPACT_CONTINUE:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static bool shrink_zone(struct zone *zone, struct scan_control *sc,
+			bool is_classzone)
+{
+	struct reclaim_state *reclaim_state = current->reclaim_state;
+	unsigned long nr_reclaimed, nr_scanned;
+	bool reclaimable = false;
+
+	do {
+		struct mem_cgroup *root = sc->target_mem_cgroup;
+		struct mem_cgroup_reclaim_cookie reclaim = {
+			.zone = zone,
+			.priority = sc->priority,
+		};
+		unsigned long zone_lru_pages = 0;
+		struct mem_cgroup *memcg;
+
+		nr_reclaimed = sc->nr_reclaimed;
+		nr_scanned = sc->nr_scanned;
+
+		memcg = mem_cgroup_iter(root, NULL, &reclaim);
+		do {
+			unsigned long lru_pages;
+			unsigned long scanned;
+			struct lruvec *lruvec;
+			int swappiness;
+
+			if (mem_cgroup_low(root, memcg)) {
+				if (!sc->may_thrash)
+					continue;
+				mem_cgroup_events(memcg, MEMCG_LOW, 1);
+			}
+
+			lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+			swappiness = mem_cgroup_swappiness(memcg);
+			scanned = sc->nr_scanned;
+
+			shrink_lruvec(lruvec, swappiness, sc, &lru_pages);
+			zone_lru_pages += lru_pages;
+
+			if (memcg && is_classzone)
+				shrink_slab(sc->gfp_mask, zone_to_nid(zone),
+					    memcg, sc->nr_scanned - scanned,
+					    lru_pages);
+
+			/*
+			 * Direct reclaim and kswapd have to scan all memory
+			 * cgroups to fulfill the overall scan target for the
+			 * zone.
+			 *
+			 * Limit reclaim, on the other hand, only cares about
+			 * nr_to_reclaim pages to be reclaimed and it will
+			 * retry with decreasing priority if one round over the
+			 * whole hierarchy is not sufficient.
+			 */
+			if (!global_reclaim(sc) &&
+					sc->nr_reclaimed >= sc->nr_to_reclaim) {
+				mem_cgroup_iter_break(root, memcg);
+				break;
+			}
+		} while ((memcg = mem_cgroup_iter(root, memcg, &reclaim)));
+
+		/*
+		 * Shrink the slab caches in the same proportion that
+		 * the eligible LRU pages were scanned.
+		 */
+		if (global_reclaim(sc) && is_classzone)
+			shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL,
+				    sc->nr_scanned - nr_scanned,
+				    zone_lru_pages);
+
+		if (reclaim_state) {
+			sc->nr_reclaimed += reclaim_state->reclaimed_slab;
+			reclaim_state->reclaimed_slab = 0;
+		}
+
+		vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
+			   sc->nr_scanned - nr_scanned,
+			   sc->nr_reclaimed - nr_reclaimed);
+
+		if (sc->nr_reclaimed - nr_reclaimed)
+			reclaimable = true;
+
+	} while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed,
+					 sc->nr_scanned - nr_scanned, sc));
+
+	return reclaimable;
+}
+
+/*
+ * Returns true if compaction should go ahead for a high-order request, or
+ * the high-order allocation would succeed without compaction.
+ */
+static inline bool compaction_ready(struct zone *zone, int order)
+{
+	unsigned long balance_gap, watermark;
+	bool watermark_ok;
+
+	/*
+	 * Compaction takes time to run and there are potentially other
+	 * callers using the pages just freed. Continue reclaiming until
+	 * there is a buffer of free pages available to give compaction
+	 * a reasonable chance of completing and allocating the page
+	 */
+	balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
+			zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
+	watermark = high_wmark_pages(zone) + balance_gap + (2UL << order);
+	watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0);
+
+	/*
+	 * If compaction is deferred, reclaim up to a point where
+	 * compaction will have a chance of success when re-enabled
+	 */
+	if (compaction_deferred(zone, order))
+		return watermark_ok;
+
+	/*
+	 * If compaction is not ready to start and allocation is not likely
+	 * to succeed without it, then keep reclaiming.
+	 */
+	if (compaction_suitable(zone, order, 0, 0) == COMPACT_SKIPPED)
+		return false;
+
+	return watermark_ok;
+}
+
+/*
+ * This is the direct reclaim path, for page-allocating processes.  We only
+ * try to reclaim pages from zones which will satisfy the caller's allocation
+ * request.
+ *
+ * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
+ * Because:
+ * a) The caller may be trying to free *extra* pages to satisfy a higher-order
+ *    allocation or
+ * b) The target zone may be at high_wmark_pages(zone) but the lower zones
+ *    must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
+ *    zone defense algorithm.
+ *
+ * If a zone is deemed to be full of pinned pages then just give it a light
+ * scan then give up on it.
+ *
+ * Returns true if a zone was reclaimable.
+ */
+static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
+{
+	struct zoneref *z;
+	struct zone *zone;
+	unsigned long nr_soft_reclaimed;
+	unsigned long nr_soft_scanned;
+	gfp_t orig_mask;
+	enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);
+	bool reclaimable = false;
+
+	/*
+	 * If the number of buffer_heads in the machine exceeds the maximum
+	 * allowed level, force direct reclaim to scan the highmem zone as
+	 * highmem pages could be pinning lowmem pages storing buffer_heads
+	 */
+	orig_mask = sc->gfp_mask;
+	if (buffer_heads_over_limit)
+		sc->gfp_mask |= __GFP_HIGHMEM;
+
+	for_each_zone_zonelist_nodemask(zone, z, zonelist,
+					gfp_zone(sc->gfp_mask), sc->nodemask) {
+		enum zone_type classzone_idx;
+
+		if (!populated_zone(zone))
+			continue;
+
+		classzone_idx = gfp_zone(sc->gfp_mask);
+		while (!populated_zone(zone->zone_pgdat->node_zones +
+							classzone_idx))
+			classzone_idx--;
+
+		/*
+		 * Take care memory controller reclaiming has small influence
+		 * to global LRU.
+		 */
+		if (global_reclaim(sc)) {
+			if (!cpuset_zone_allowed(zone,
+						 GFP_KERNEL | __GFP_HARDWALL))
+				continue;
+
+			if (sc->priority != DEF_PRIORITY &&
+			    !zone_reclaimable(zone))
+				continue;	/* Let kswapd poll it */
+
+			/*
+			 * If we already have plenty of memory free for
+			 * compaction in this zone, don't free any more.
+			 * Even though compaction is invoked for any
+			 * non-zero order, only frequent costly order
+			 * reclamation is disruptive enough to become a
+			 * noticeable problem, like transparent huge
+			 * page allocations.
+			 */
+			if (IS_ENABLED(CONFIG_COMPACTION) &&
+			    sc->order > PAGE_ALLOC_COSTLY_ORDER &&
+			    zonelist_zone_idx(z) <= requested_highidx &&
+			    compaction_ready(zone, sc->order)) {
+				sc->compaction_ready = true;
+				continue;
+			}
+
+			/*
+			 * This steals pages from memory cgroups over softlimit
+			 * and returns the number of reclaimed pages and
+			 * scanned pages. This works for global memory pressure
+			 * and balancing, not for a memcg's limit.
+			 */
+			nr_soft_scanned = 0;
+			nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+						sc->order, sc->gfp_mask,
+						&nr_soft_scanned);
+			sc->nr_reclaimed += nr_soft_reclaimed;
+			sc->nr_scanned += nr_soft_scanned;
+			if (nr_soft_reclaimed)
+				reclaimable = true;
+			/* need some check for avoid more shrink_zone() */
+		}
+
+		if (shrink_zone(zone, sc, zone_idx(zone) == classzone_idx))
+			reclaimable = true;
+
+		if (global_reclaim(sc) &&
+		    !reclaimable && zone_reclaimable(zone))
+			reclaimable = true;
+	}
+
+	/*
+	 * Restore to original mask to avoid the impact on the caller if we
+	 * promoted it to __GFP_HIGHMEM.
+	 */
+	sc->gfp_mask = orig_mask;
+
+	return reclaimable;
+}
+
+/*
+ * This is the main entry point to direct page reclaim.
+ *
+ * If a full scan of the inactive list fails to free enough memory then we
+ * are "out of memory" and something needs to be killed.
+ *
+ * If the caller is !__GFP_FS then the probability of a failure is reasonably
+ * high - the zone may be full of dirty or under-writeback pages, which this
+ * caller can't do much about.  We kick the writeback threads and take explicit
+ * naps in the hope that some of these pages can be written.  But if the
+ * allocating task holds filesystem locks which prevent writeout this might not
+ * work, and the allocation attempt will fail.
+ *
+ * returns:	0, if no pages reclaimed
+ * 		else, the number of pages reclaimed
+ */
+static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
+					  struct scan_control *sc)
+{
+	int initial_priority = sc->priority;
+	unsigned long total_scanned = 0;
+	unsigned long writeback_threshold;
+	bool zones_reclaimable;
+retry:
+	delayacct_freepages_start();
+
+	if (global_reclaim(sc))
+		count_vm_event(ALLOCSTALL);
+
+	do {
+		vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
+				sc->priority);
+		sc->nr_scanned = 0;
+		zones_reclaimable = shrink_zones(zonelist, sc);
+
+		total_scanned += sc->nr_scanned;
+		if (sc->nr_reclaimed >= sc->nr_to_reclaim)
+			break;
+
+		if (sc->compaction_ready)
+			break;
+
+		/*
+		 * If we're getting trouble reclaiming, start doing
+		 * writepage even in laptop mode.
+		 */
+		if (sc->priority < DEF_PRIORITY - 2)
+			sc->may_writepage = 1;
+
+		/*
+		 * Try to write back as many pages as we just scanned.  This
+		 * tends to cause slow streaming writers to write data to the
+		 * disk smoothly, at the dirtying rate, which is nice.   But
+		 * that's undesirable in laptop mode, where we *want* lumpy
+		 * writeout.  So in laptop mode, write out the whole world.
+		 */
+		writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
+		if (total_scanned > writeback_threshold) {
+			wakeup_flusher_threads(laptop_mode ? 0 : total_scanned,
+						WB_REASON_TRY_TO_FREE_PAGES);
+			sc->may_writepage = 1;
+		}
+	} while (--sc->priority >= 0);
+
+	delayacct_freepages_end();
+
+	if (sc->nr_reclaimed)
+		return sc->nr_reclaimed;
+
+	/* Aborted reclaim to try compaction? don't OOM, then */
+	if (sc->compaction_ready)
+		return 1;
+
+	/* Untapped cgroup reserves?  Don't OOM, retry. */
+	if (!sc->may_thrash) {
+		sc->priority = initial_priority;
+		sc->may_thrash = 1;
+		goto retry;
+	}
+
+	/* Any of the zones still reclaimable?  Don't OOM. */
+	if (zones_reclaimable)
+		return 1;
+
+	return 0;
+}
+
+static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
+{
+	struct zone *zone;
+	unsigned long pfmemalloc_reserve = 0;
+	unsigned long free_pages = 0;
+	int i;
+	bool wmark_ok;
+
+	for (i = 0; i <= ZONE_NORMAL; i++) {
+		zone = &pgdat->node_zones[i];
+		if (!populated_zone(zone) ||
+		    zone_reclaimable_pages(zone) == 0)
+			continue;
+
+		pfmemalloc_reserve += min_wmark_pages(zone);
+		free_pages += zone_page_state(zone, NR_FREE_PAGES);
+	}
+
+	/* If there are no reserves (unexpected config) then do not throttle */
+	if (!pfmemalloc_reserve)
+		return true;
+
+	wmark_ok = free_pages > pfmemalloc_reserve / 2;
+
+	/* kswapd must be awake if processes are being throttled */
+	if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) {
+		pgdat->classzone_idx = min(pgdat->classzone_idx,
+						(enum zone_type)ZONE_NORMAL);
+		wake_up_interruptible(&pgdat->kswapd_wait);
+	}
+
+	return wmark_ok;
+}
+
+/*
+ * Throttle direct reclaimers if backing storage is backed by the network
+ * and the PFMEMALLOC reserve for the preferred node is getting dangerously
+ * depleted. kswapd will continue to make progress and wake the processes
+ * when the low watermark is reached.
+ *
+ * Returns true if a fatal signal was delivered during throttling. If this
+ * happens, the page allocator should not consider triggering the OOM killer.
+ */
+static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
+					nodemask_t *nodemask)
+{
+	struct zoneref *z;
+	struct zone *zone;
+	pg_data_t *pgdat = NULL;
+
+	/*
+	 * Kernel threads should not be throttled as they may be indirectly
+	 * responsible for cleaning pages necessary for reclaim to make forward
+	 * progress. kjournald for example may enter direct reclaim while
+	 * committing a transaction where throttling it could forcing other
+	 * processes to block on log_wait_commit().
+	 */
+	if (current->flags & PF_KTHREAD)
+		goto out;
+
+	/*
+	 * If a fatal signal is pending, this process should not throttle.
+	 * It should return quickly so it can exit and free its memory
+	 */
+	if (fatal_signal_pending(current))
+		goto out;
+
+	/*
+	 * Check if the pfmemalloc reserves are ok by finding the first node
+	 * with a usable ZONE_NORMAL or lower zone. The expectation is that
+	 * GFP_KERNEL will be required for allocating network buffers when
+	 * swapping over the network so ZONE_HIGHMEM is unusable.
+	 *
+	 * Throttling is based on the first usable node and throttled processes
+	 * wait on a queue until kswapd makes progress and wakes them. There
+	 * is an affinity then between processes waking up and where reclaim
+	 * progress has been made assuming the process wakes on the same node.
+	 * More importantly, processes running on remote nodes will not compete
+	 * for remote pfmemalloc reserves and processes on different nodes
+	 * should make reasonable progress.
+	 */
+	for_each_zone_zonelist_nodemask(zone, z, zonelist,
+					gfp_zone(gfp_mask), nodemask) {
+		if (zone_idx(zone) > ZONE_NORMAL)
+			continue;
+
+		/* Throttle based on the first usable node */
+		pgdat = zone->zone_pgdat;
+		if (pfmemalloc_watermark_ok(pgdat))
+			goto out;
+		break;
+	}
+
+	/* If no zone was usable by the allocation flags then do not throttle */
+	if (!pgdat)
+		goto out;
+
+	/* Account for the throttling */
+	count_vm_event(PGSCAN_DIRECT_THROTTLE);
+
+	/*
+	 * If the caller cannot enter the filesystem, it's possible that it
+	 * is due to the caller holding an FS lock or performing a journal
+	 * transaction in the case of a filesystem like ext[3|4]. In this case,
+	 * it is not safe to block on pfmemalloc_wait as kswapd could be
+	 * blocked waiting on the same lock. Instead, throttle for up to a
+	 * second before continuing.
+	 */
+	if (!(gfp_mask & __GFP_FS)) {
+		wait_event_interruptible_timeout(pgdat->pfmemalloc_wait,
+			pfmemalloc_watermark_ok(pgdat), HZ);
+
+		goto check_pending;
+	}
+
+	/* Throttle until kswapd wakes the process */
+	wait_event_killable(zone->zone_pgdat->pfmemalloc_wait,
+		pfmemalloc_watermark_ok(pgdat));
+
+check_pending:
+	if (fatal_signal_pending(current))
+		return true;
+
+out:
+	return false;
+}
+
+unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
+				gfp_t gfp_mask, nodemask_t *nodemask)
+{
+	unsigned long nr_reclaimed;
+	struct scan_control sc = {
+		.nr_to_reclaim = SWAP_CLUSTER_MAX,
+		.gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+		.order = order,
+		.nodemask = nodemask,
+		.priority = DEF_PRIORITY,
+		.may_writepage = !laptop_mode,
+		.may_unmap = 1,
+		.may_swap = 1,
+	};
+
+	/*
+	 * Do not enter reclaim if fatal signal was delivered while throttled.
+	 * 1 is returned so that the page allocator does not OOM kill at this
+	 * point.
+	 */
+	if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask))
+		return 1;
+
+	trace_mm_vmscan_direct_reclaim_begin(order,
+				sc.may_writepage,
+				gfp_mask);
+
+	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
+
+	trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
+
+	return nr_reclaimed;
+}
+
+#ifdef CONFIG_MEMCG
+
+unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
+						gfp_t gfp_mask, bool noswap,
+						struct zone *zone,
+						unsigned long *nr_scanned)
+{
+	struct scan_control sc = {
+		.nr_to_reclaim = SWAP_CLUSTER_MAX,
+		.target_mem_cgroup = memcg,
+		.may_writepage = !laptop_mode,
+		.may_unmap = 1,
+		.may_swap = !noswap,
+	};
+	struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+	int swappiness = mem_cgroup_swappiness(memcg);
+	unsigned long lru_pages;
+
+	sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
+			(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
+
+	trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
+						      sc.may_writepage,
+						      sc.gfp_mask);
+
+	/*
+	 * NOTE: Although we can get the priority field, using it
+	 * here is not a good idea, since it limits the pages we can scan.
+	 * if we don't reclaim here, the shrink_zone from balance_pgdat
+	 * will pick up pages from other mem cgroup's as well. We hack
+	 * the priority and make it zero.
+	 */
+	shrink_lruvec(lruvec, swappiness, &sc, &lru_pages);
+
+	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
+
+	*nr_scanned = sc.nr_scanned;
+	return sc.nr_reclaimed;
+}
+
+unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
+					   unsigned long nr_pages,
+					   gfp_t gfp_mask,
+					   bool may_swap)
+{
+	struct zonelist *zonelist;
+	unsigned long nr_reclaimed;
+	int nid;
+	struct scan_control sc = {
+		.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
+		.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
+				(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
+		.target_mem_cgroup = memcg,
+		.priority = DEF_PRIORITY,
+		.may_writepage = !laptop_mode,
+		.may_unmap = 1,
+		.may_swap = may_swap,
+	};
+
+	/*
+	 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
+	 * take care of from where we get pages. So the node where we start the
+	 * scan does not need to be the current node.
+	 */
+	nid = mem_cgroup_select_victim_node(memcg);
+
+	zonelist = NODE_DATA(nid)->node_zonelists;
+
+	trace_mm_vmscan_memcg_reclaim_begin(0,
+					    sc.may_writepage,
+					    sc.gfp_mask);
+
+	current->flags |= PF_MEMALLOC;
+	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
+	current->flags &= ~PF_MEMALLOC;
+
+	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
+
+	return nr_reclaimed;
+}
+#endif
+
+static void age_active_anon(struct zone *zone, struct scan_control *sc)
+{
+	struct mem_cgroup *memcg;
+
+	if (!total_swap_pages)
+		return;
+
+	memcg = mem_cgroup_iter(NULL, NULL, NULL);
+	do {
+		struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+
+		if (inactive_anon_is_low(lruvec))
+			shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
+					   sc, LRU_ACTIVE_ANON);
+
+		memcg = mem_cgroup_iter(NULL, memcg, NULL);
+	} while (memcg);
+}
+
+static bool zone_balanced(struct zone *zone, int order,
+			  unsigned long balance_gap, int classzone_idx)
+{
+	if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
+				    balance_gap, classzone_idx))
+		return false;
+
+	if (IS_ENABLED(CONFIG_COMPACTION) && order && compaction_suitable(zone,
+				order, 0, classzone_idx) == COMPACT_SKIPPED)
+		return false;
+
+	return true;
+}
+
+/*
+ * pgdat_balanced() is used when checking if a node is balanced.
+ *
+ * For order-0, all zones must be balanced!
+ *
+ * For high-order allocations only zones that meet watermarks and are in a
+ * zone allowed by the callers classzone_idx are added to balanced_pages. The
+ * total of balanced pages must be at least 25% of the zones allowed by
+ * classzone_idx for the node to be considered balanced. Forcing all zones to
+ * be balanced for high orders can cause excessive reclaim when there are
+ * imbalanced zones.
+ * The choice of 25% is due to
+ *   o a 16M DMA zone that is balanced will not balance a zone on any
+ *     reasonable sized machine
+ *   o On all other machines, the top zone must be at least a reasonable
+ *     percentage of the middle zones. For example, on 32-bit x86, highmem
+ *     would need to be at least 256M for it to be balance a whole node.
+ *     Similarly, on x86-64 the Normal zone would need to be at least 1G
+ *     to balance a node on its own. These seemed like reasonable ratios.
+ */
+static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx)
+{
+	unsigned long managed_pages = 0;
+	unsigned long balanced_pages = 0;
+	int i;
+
+	/* Check the watermark levels */
+	for (i = 0; i <= classzone_idx; i++) {
+		struct zone *zone = pgdat->node_zones + i;
+
+		if (!populated_zone(zone))
+			continue;
+
+		managed_pages += zone->managed_pages;
+
+		/*
+		 * A special case here:
+		 *
+		 * balance_pgdat() skips over all_unreclaimable after
+		 * DEF_PRIORITY. Effectively, it considers them balanced so
+		 * they must be considered balanced here as well!
+		 */
+		if (!zone_reclaimable(zone)) {
+			balanced_pages += zone->managed_pages;
+			continue;
+		}
+
+		if (zone_balanced(zone, order, 0, i))
+			balanced_pages += zone->managed_pages;
+		else if (!order)
+			return false;
+	}
+
+	if (order)
+		return balanced_pages >= (managed_pages >> 2);
+	else
+		return true;
+}
+
+/*
+ * Prepare kswapd for sleeping. This verifies that there are no processes
+ * waiting in throttle_direct_reclaim() and that watermarks have been met.
+ *
+ * Returns true if kswapd is ready to sleep
+ */
+static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
+					int classzone_idx)
+{
+	/* If a direct reclaimer woke kswapd within HZ/10, it's premature */
+	if (remaining)
+		return false;
+
+	/*
+	 * The throttled processes are normally woken up in balance_pgdat() as
+	 * soon as pfmemalloc_watermark_ok() is true. But there is a potential
+	 * race between when kswapd checks the watermarks and a process gets
+	 * throttled. There is also a potential race if processes get
+	 * throttled, kswapd wakes, a large process exits thereby balancing the
+	 * zones, which causes kswapd to exit balance_pgdat() before reaching
+	 * the wake up checks. If kswapd is going to sleep, no process should
+	 * be sleeping on pfmemalloc_wait, so wake them now if necessary. If
+	 * the wake up is premature, processes will wake kswapd and get
+	 * throttled again. The difference from wake ups in balance_pgdat() is
+	 * that here we are under prepare_to_wait().
+	 */
+	if (waitqueue_active(&pgdat->pfmemalloc_wait))
+		wake_up_all(&pgdat->pfmemalloc_wait);
+
+	return pgdat_balanced(pgdat, order, classzone_idx);
+}
+
+/*
+ * kswapd shrinks the zone by the number of pages required to reach
+ * the high watermark.
+ *
+ * Returns true if kswapd scanned at least the requested number of pages to
+ * reclaim or if the lack of progress was due to pages under writeback.
+ * This is used to determine if the scanning priority needs to be raised.
+ */
+static bool kswapd_shrink_zone(struct zone *zone,
+			       int classzone_idx,
+			       struct scan_control *sc,
+			       unsigned long *nr_attempted)
+{
+	int testorder = sc->order;
+	unsigned long balance_gap;
+	bool lowmem_pressure;
+
+	/* Reclaim above the high watermark. */
+	sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone));
+
+	/*
+	 * Kswapd reclaims only single pages with compaction enabled. Trying
+	 * too hard to reclaim until contiguous free pages have become
+	 * available can hurt performance by evicting too much useful data
+	 * from memory. Do not reclaim more than needed for compaction.
+	 */
+	if (IS_ENABLED(CONFIG_COMPACTION) && sc->order &&
+			compaction_suitable(zone, sc->order, 0, classzone_idx)
+							!= COMPACT_SKIPPED)
+		testorder = 0;
+
+	/*
+	 * We put equal pressure on every zone, unless one zone has way too
+	 * many pages free already. The "too many pages" is defined as the
+	 * high wmark plus a "gap" where the gap is either the low
+	 * watermark or 1% of the zone, whichever is smaller.
+	 */
+	balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
+			zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
+
+	/*
+	 * If there is no low memory pressure or the zone is balanced then no
+	 * reclaim is necessary
+	 */
+	lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone));
+	if (!lowmem_pressure && zone_balanced(zone, testorder,
+						balance_gap, classzone_idx))
+		return true;
+
+	shrink_zone(zone, sc, zone_idx(zone) == classzone_idx);
+
+	/* Account for the number of pages attempted to reclaim */
+	*nr_attempted += sc->nr_to_reclaim;
+
+	clear_bit(ZONE_WRITEBACK, &zone->flags);
+
+	/*
+	 * If a zone reaches its high watermark, consider it to be no longer
+	 * congested. It's possible there are dirty pages backed by congested
+	 * BDIs but as pressure is relieved, speculatively avoid congestion
+	 * waits.
+	 */
+	if (zone_reclaimable(zone) &&
+	    zone_balanced(zone, testorder, 0, classzone_idx)) {
+		clear_bit(ZONE_CONGESTED, &zone->flags);
+		clear_bit(ZONE_DIRTY, &zone->flags);
+	}
+
+	return sc->nr_scanned >= sc->nr_to_reclaim;
+}
+
+/*
+ * For kswapd, balance_pgdat() will work across all this node's zones until
+ * they are all at high_wmark_pages(zone).
+ *
+ * Returns the final order kswapd was reclaiming at
+ *
+ * There is special handling here for zones which are full of pinned pages.
+ * This can happen if the pages are all mlocked, or if they are all used by
+ * device drivers (say, ZONE_DMA).  Or if they are all in use by hugetlb.
+ * What we do is to detect the case where all pages in the zone have been
+ * scanned twice and there has been zero successful reclaim.  Mark the zone as
+ * dead and from now on, only perform a short scan.  Basically we're polling
+ * the zone for when the problem goes away.
+ *
+ * kswapd scans the zones in the highmem->normal->dma direction.  It skips
+ * zones which have free_pages > high_wmark_pages(zone), but once a zone is
+ * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
+ * lower zones regardless of the number of free pages in the lower zones. This
+ * interoperates with the page allocator fallback scheme to ensure that aging
+ * of pages is balanced across the zones.
+ */
+static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
+							int *classzone_idx)
+{
+	int i;
+	int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */
+	unsigned long nr_soft_reclaimed;
+	unsigned long nr_soft_scanned;
+	struct scan_control sc = {
+		.gfp_mask = GFP_KERNEL,
+		.order = order,
+		.priority = DEF_PRIORITY,
+		.may_writepage = !laptop_mode,
+		.may_unmap = 1,
+		.may_swap = 1,
+	};
+	count_vm_event(PAGEOUTRUN);
+
+	do {
+		unsigned long nr_attempted = 0;
+		bool raise_priority = true;
+		bool pgdat_needs_compaction = (order > 0);
+
+		sc.nr_reclaimed = 0;
+
+		/*
+		 * Scan in the highmem->dma direction for the highest
+		 * zone which needs scanning
+		 */
+		for (i = pgdat->nr_zones - 1; i >= 0; i--) {
+			struct zone *zone = pgdat->node_zones + i;
+
+			if (!populated_zone(zone))
+				continue;
+
+			if (sc.priority != DEF_PRIORITY &&
+			    !zone_reclaimable(zone))
+				continue;
+
+			/*
+			 * Do some background aging of the anon list, to give
+			 * pages a chance to be referenced before reclaiming.
+			 */
+			age_active_anon(zone, &sc);
+
+			/*
+			 * If the number of buffer_heads in the machine
+			 * exceeds the maximum allowed level and this node
+			 * has a highmem zone, force kswapd to reclaim from
+			 * it to relieve lowmem pressure.
+			 */
+			if (buffer_heads_over_limit && is_highmem_idx(i)) {
+				end_zone = i;
+				break;
+			}
+
+			if (!zone_balanced(zone, order, 0, 0)) {
+				end_zone = i;
+				break;
+			} else {
+				/*
+				 * If balanced, clear the dirty and congested
+				 * flags
+				 */
+				clear_bit(ZONE_CONGESTED, &zone->flags);
+				clear_bit(ZONE_DIRTY, &zone->flags);
+			}
+		}
+
+		if (i < 0)
+			goto out;
+
+		for (i = 0; i <= end_zone; i++) {
+			struct zone *zone = pgdat->node_zones + i;
+
+			if (!populated_zone(zone))
+				continue;
+
+			/*
+			 * If any zone is currently balanced then kswapd will
+			 * not call compaction as it is expected that the
+			 * necessary pages are already available.
+			 */
+			if (pgdat_needs_compaction &&
+					zone_watermark_ok(zone, order,
+						low_wmark_pages(zone),
+						*classzone_idx, 0))
+				pgdat_needs_compaction = false;
+		}
+
+		/*
+		 * If we're getting trouble reclaiming, start doing writepage
+		 * even in laptop mode.
+		 */
+		if (sc.priority < DEF_PRIORITY - 2)
+			sc.may_writepage = 1;
+
+		/*
+		 * Now scan the zone in the dma->highmem direction, stopping
+		 * at the last zone which needs scanning.
+		 *
+		 * We do this because the page allocator works in the opposite
+		 * direction.  This prevents the page allocator from allocating
+		 * pages behind kswapd's direction of progress, which would
+		 * cause too much scanning of the lower zones.
+		 */
+		for (i = 0; i <= end_zone; i++) {
+			struct zone *zone = pgdat->node_zones + i;
+
+			if (!populated_zone(zone))
+				continue;
+
+			if (sc.priority != DEF_PRIORITY &&
+			    !zone_reclaimable(zone))
+				continue;
+
+			sc.nr_scanned = 0;
+
+			nr_soft_scanned = 0;
+			/*
+			 * Call soft limit reclaim before calling shrink_zone.
+			 */
+			nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+							order, sc.gfp_mask,
+							&nr_soft_scanned);
+			sc.nr_reclaimed += nr_soft_reclaimed;
+
+			/*
+			 * There should be no need to raise the scanning
+			 * priority if enough pages are already being scanned
+			 * that that high watermark would be met at 100%
+			 * efficiency.
+			 */
+			if (kswapd_shrink_zone(zone, end_zone,
+					       &sc, &nr_attempted))
+				raise_priority = false;
+		}
+
+		/*
+		 * If the low watermark is met there is no need for processes
+		 * to be throttled on pfmemalloc_wait as they should not be
+		 * able to safely make forward progress. Wake them
+		 */
+		if (waitqueue_active(&pgdat->pfmemalloc_wait) &&
+				pfmemalloc_watermark_ok(pgdat))
+			wake_up_all(&pgdat->pfmemalloc_wait);
+
+		/*
+		 * Fragmentation may mean that the system cannot be rebalanced
+		 * for high-order allocations in all zones. If twice the
+		 * allocation size has been reclaimed and the zones are still
+		 * not balanced then recheck the watermarks at order-0 to
+		 * prevent kswapd reclaiming excessively. Assume that a
+		 * process requested a high-order can direct reclaim/compact.
+		 */
+		if (order && sc.nr_reclaimed >= 2UL << order)
+			order = sc.order = 0;
+
+		/* Check if kswapd should be suspending */
+		if (try_to_freeze() || kthread_should_stop())
+			break;
+
+		/*
+		 * Compact if necessary and kswapd is reclaiming at least the
+		 * high watermark number of pages as requsted
+		 */
+		if (pgdat_needs_compaction && sc.nr_reclaimed > nr_attempted)
+			compact_pgdat(pgdat, order);
+
+		/*
+		 * Raise priority if scanning rate is too low or there was no
+		 * progress in reclaiming pages
+		 */
+		if (raise_priority || !sc.nr_reclaimed)
+			sc.priority--;
+	} while (sc.priority >= 1 &&
+		 !pgdat_balanced(pgdat, order, *classzone_idx));
+
+out:
+	/*
+	 * Return the order we were reclaiming at so prepare_kswapd_sleep()
+	 * makes a decision on the order we were last reclaiming at. However,
+	 * if another caller entered the allocator slow path while kswapd
+	 * was awake, order will remain at the higher level
+	 */
+	*classzone_idx = end_zone;
+	return order;
+}
+
+static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
+{
+	long remaining = 0;
+	DEFINE_WAIT(wait);
+
+	if (freezing(current) || kthread_should_stop())
+		return;
+
+	prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
+
+	/* Try to sleep for a short interval */
+	if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) {
+		remaining = schedule_timeout(HZ/10);
+		finish_wait(&pgdat->kswapd_wait, &wait);
+		prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
+	}
+
+	/*
+	 * After a short sleep, check if it was a premature sleep. If not, then
+	 * go fully to sleep until explicitly woken up.
+	 */
+	if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) {
+		trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
+
+		/*
+		 * vmstat counters are not perfectly accurate and the estimated
+		 * value for counters such as NR_FREE_PAGES can deviate from the
+		 * true value by nr_online_cpus * threshold. To avoid the zone
+		 * watermarks being breached while under pressure, we reduce the
+		 * per-cpu vmstat threshold while kswapd is awake and restore
+		 * them before going back to sleep.
+		 */
+		set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
+
+		/*
+		 * Compaction records what page blocks it recently failed to
+		 * isolate pages from and skips them in the future scanning.
+		 * When kswapd is going to sleep, it is reasonable to assume
+		 * that pages and compaction may succeed so reset the cache.
+		 */
+		reset_isolation_suitable(pgdat);
+
+		if (!kthread_should_stop())
+			schedule();
+
+		set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
+	} else {
+		if (remaining)
+			count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
+		else
+			count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
+	}
+	finish_wait(&pgdat->kswapd_wait, &wait);
+}
+
+/*
+ * The background pageout daemon, started as a kernel thread
+ * from the init process.
+ *
+ * This basically trickles out pages so that we have _some_
+ * free memory available even if there is no other activity
+ * that frees anything up. This is needed for things like routing
+ * etc, where we otherwise might have all activity going on in
+ * asynchronous contexts that cannot page things out.
+ *
+ * If there are applications that are active memory-allocators
+ * (most normal use), this basically shouldn't matter.
+ */
+static int kswapd(void *p)
+{
+	unsigned long order, new_order;
+	unsigned balanced_order;
+	int classzone_idx, new_classzone_idx;
+	int balanced_classzone_idx;
+	pg_data_t *pgdat = (pg_data_t*)p;
+	struct task_struct *tsk = current;
+
+	struct reclaim_state reclaim_state = {
+		.reclaimed_slab = 0,
+	};
+	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
+
+	lockdep_set_current_reclaim_state(GFP_KERNEL);
+
+	if (!cpumask_empty(cpumask))
+		set_cpus_allowed_ptr(tsk, cpumask);
+	current->reclaim_state = &reclaim_state;
+
+	/*
+	 * Tell the memory management that we're a "memory allocator",
+	 * and that if we need more memory we should get access to it
+	 * regardless (see "__alloc_pages()"). "kswapd" should
+	 * never get caught in the normal page freeing logic.
+	 *
+	 * (Kswapd normally doesn't need memory anyway, but sometimes
+	 * you need a small amount of memory in order to be able to
+	 * page out something else, and this flag essentially protects
+	 * us from recursively trying to free more memory as we're
+	 * trying to free the first piece of memory in the first place).
+	 */
+	tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
+	set_freezable();
+
+	order = new_order = 0;
+	balanced_order = 0;
+	classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
+	balanced_classzone_idx = classzone_idx;
+	for ( ; ; ) {
+		bool ret;
+
+		/*
+		 * If the last balance_pgdat was unsuccessful it's unlikely a
+		 * new request of a similar or harder type will succeed soon
+		 * so consider going to sleep on the basis we reclaimed at
+		 */
+		if (balanced_classzone_idx >= new_classzone_idx &&
+					balanced_order == new_order) {
+			new_order = pgdat->kswapd_max_order;
+			new_classzone_idx = pgdat->classzone_idx;
+			pgdat->kswapd_max_order =  0;
+			pgdat->classzone_idx = pgdat->nr_zones - 1;
+		}
+
+		if (order < new_order || classzone_idx > new_classzone_idx) {
+			/*
+			 * Don't sleep if someone wants a larger 'order'
+			 * allocation or has tigher zone constraints
+			 */
+			order = new_order;
+			classzone_idx = new_classzone_idx;
+		} else {
+			kswapd_try_to_sleep(pgdat, balanced_order,
+						balanced_classzone_idx);
+			order = pgdat->kswapd_max_order;
+			classzone_idx = pgdat->classzone_idx;
+			new_order = order;
+			new_classzone_idx = classzone_idx;
+			pgdat->kswapd_max_order = 0;
+			pgdat->classzone_idx = pgdat->nr_zones - 1;
+		}
+
+		ret = try_to_freeze();
+		if (kthread_should_stop())
+			break;
+
+		/*
+		 * We can speed up thawing tasks if we don't call balance_pgdat
+		 * after returning from the refrigerator
+		 */
+		if (!ret) {
+			trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
+			balanced_classzone_idx = classzone_idx;
+			balanced_order = balance_pgdat(pgdat, order,
+						&balanced_classzone_idx);
+		}
+	}
+
+	tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);
+	current->reclaim_state = NULL;
+	lockdep_clear_current_reclaim_state();
+
+	return 0;
+}
+
+/*
+ * A zone is low on free memory, so wake its kswapd task to service it.
+ */
+void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
+{
+	pg_data_t *pgdat;
+
+	if (!populated_zone(zone))
+		return;
+
+	if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL))
+		return;
+	pgdat = zone->zone_pgdat;
+	if (pgdat->kswapd_max_order < order) {
+		pgdat->kswapd_max_order = order;
+		pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
+	}
+	if (!waitqueue_active(&pgdat->kswapd_wait))
+		return;
+	if (zone_balanced(zone, order, 0, 0))
+		return;
+
+	trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
+	wake_up_interruptible(&pgdat->kswapd_wait);
+}
+
+#ifdef CONFIG_HIBERNATION
+/*
+ * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
+ * freed pages.
+ *
+ * Rather than trying to age LRUs the aim is to preserve the overall
+ * LRU order by reclaiming preferentially
+ * inactive > active > active referenced > active mapped
+ */
+unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
+{
+	struct reclaim_state reclaim_state;
+	struct scan_control sc = {
+		.nr_to_reclaim = nr_to_reclaim,
+		.gfp_mask = GFP_HIGHUSER_MOVABLE,
+		.priority = DEF_PRIORITY,
+		.may_writepage = 1,
+		.may_unmap = 1,
+		.may_swap = 1,
+		.hibernation_mode = 1,
+	};
+	struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
+	struct task_struct *p = current;
+	unsigned long nr_reclaimed;
+
+	p->flags |= PF_MEMALLOC;
+	lockdep_set_current_reclaim_state(sc.gfp_mask);
+	reclaim_state.reclaimed_slab = 0;
+	p->reclaim_state = &reclaim_state;
+
+	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
+
+	p->reclaim_state = NULL;
+	lockdep_clear_current_reclaim_state();
+	p->flags &= ~PF_MEMALLOC;
+
+	return nr_reclaimed;
+}
+#endif /* CONFIG_HIBERNATION */
+
+/* It's optimal to keep kswapds on the same CPUs as their memory, but
+   not required for correctness.  So if the last cpu in a node goes
+   away, we get changed to run anywhere: as the first one comes back,
+   restore their cpu bindings. */
+static int cpu_callback(struct notifier_block *nfb, unsigned long action,
+			void *hcpu)
+{
+	int nid;
+
+	if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
+		for_each_node_state(nid, N_MEMORY) {
+			pg_data_t *pgdat = NODE_DATA(nid);
+			const struct cpumask *mask;
+
+			mask = cpumask_of_node(pgdat->node_id);
+
+			if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
+				/* One of our CPUs online: restore mask */
+				set_cpus_allowed_ptr(pgdat->kswapd, mask);
+		}
+	}
+	return NOTIFY_OK;
+}
+
+/*
+ * This kswapd start function will be called by init and node-hot-add.
+ * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
+ */
+int kswapd_run(int nid)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+	int ret = 0;
+
+	if (pgdat->kswapd)
+		return 0;
+
+	pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
+	if (IS_ERR(pgdat->kswapd)) {
+		/* failure at boot is fatal */
+		BUG_ON(system_state == SYSTEM_BOOTING);
+		pr_err("Failed to start kswapd on node %d\n", nid);
+		ret = PTR_ERR(pgdat->kswapd);
+		pgdat->kswapd = NULL;
+	}
+	return ret;
+}
+
+/*
+ * Called by memory hotplug when all memory in a node is offlined.  Caller must
+ * hold mem_hotplug_begin/end().
+ */
+void kswapd_stop(int nid)
+{
+	struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
+
+	if (kswapd) {
+		kthread_stop(kswapd);
+		NODE_DATA(nid)->kswapd = NULL;
+	}
+}
+
+static int __init kswapd_init(void)
+{
+	int nid;
+
+	swap_setup();
+	for_each_node_state(nid, N_MEMORY)
+ 		kswapd_run(nid);
+	hotcpu_notifier(cpu_callback, 0);
+	return 0;
+}
+
+module_init(kswapd_init)
+
+#ifdef CONFIG_NUMA
+/*
+ * Zone reclaim mode
+ *
+ * If non-zero call zone_reclaim when the number of free pages falls below
+ * the watermarks.
+ */
+int zone_reclaim_mode __read_mostly;
+
+#define RECLAIM_OFF 0
+#define RECLAIM_ZONE (1<<0)	/* Run shrink_inactive_list on the zone */
+#define RECLAIM_WRITE (1<<1)	/* Writeout pages during reclaim */
+#define RECLAIM_UNMAP (1<<2)	/* Unmap pages during reclaim */
+
+/*
+ * Priority for ZONE_RECLAIM. This determines the fraction of pages
+ * of a node considered for each zone_reclaim. 4 scans 1/16th of
+ * a zone.
+ */
+#define ZONE_RECLAIM_PRIORITY 4
+
+/*
+ * Percentage of pages in a zone that must be unmapped for zone_reclaim to
+ * occur.
+ */
+int sysctl_min_unmapped_ratio = 1;
+
+/*
+ * If the number of slab pages in a zone grows beyond this percentage then
+ * slab reclaim needs to occur.
+ */
+int sysctl_min_slab_ratio = 5;
+
+static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
+{
+	unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
+	unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
+		zone_page_state(zone, NR_ACTIVE_FILE);
+
+	/*
+	 * It's possible for there to be more file mapped pages than
+	 * accounted for by the pages on the file LRU lists because
+	 * tmpfs pages accounted for as ANON can also be FILE_MAPPED
+	 */
+	return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
+}
+
+/* Work out how many page cache pages we can reclaim in this reclaim_mode */
+static unsigned long zone_pagecache_reclaimable(struct zone *zone)
+{
+	unsigned long nr_pagecache_reclaimable;
+	unsigned long delta = 0;
+
+	/*
+	 * If RECLAIM_UNMAP is set, then all file pages are considered
+	 * potentially reclaimable. Otherwise, we have to worry about
+	 * pages like swapcache and zone_unmapped_file_pages() provides
+	 * a better estimate
+	 */
+	if (zone_reclaim_mode & RECLAIM_UNMAP)
+		nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
+	else
+		nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
+
+	/* If we can't clean pages, remove dirty pages from consideration */
+	if (!(zone_reclaim_mode & RECLAIM_WRITE))
+		delta += zone_page_state(zone, NR_FILE_DIRTY);
+
+	/* Watch for any possible underflows due to delta */
+	if (unlikely(delta > nr_pagecache_reclaimable))
+		delta = nr_pagecache_reclaimable;
+
+	return nr_pagecache_reclaimable - delta;
+}
+
+/*
+ * Try to free up some pages from this zone through reclaim.
+ */
+static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+{
+	/* Minimum pages needed in order to stay on node */
+	const unsigned long nr_pages = 1 << order;
+	struct task_struct *p = current;
+	struct reclaim_state reclaim_state;
+	struct scan_control sc = {
+		.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
+		.gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+		.order = order,
+		.priority = ZONE_RECLAIM_PRIORITY,
+		.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
+		.may_unmap = !!(zone_reclaim_mode & RECLAIM_UNMAP),
+		.may_swap = 1,
+	};
+
+	cond_resched();
+	/*
+	 * We need to be able to allocate from the reserves for RECLAIM_UNMAP
+	 * and we also need to be able to write out pages for RECLAIM_WRITE
+	 * and RECLAIM_UNMAP.
+	 */
+	p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
+	lockdep_set_current_reclaim_state(gfp_mask);
+	reclaim_state.reclaimed_slab = 0;
+	p->reclaim_state = &reclaim_state;
+
+	if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
+		/*
+		 * Free memory by calling shrink zone with increasing
+		 * priorities until we have enough memory freed.
+		 */
+		do {
+			shrink_zone(zone, &sc, true);
+		} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
+	}
+
+	p->reclaim_state = NULL;
+	current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
+	lockdep_clear_current_reclaim_state();
+	return sc.nr_reclaimed >= nr_pages;
+}
+
+int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+{
+	int node_id;
+	int ret;
+
+	/*
+	 * Zone reclaim reclaims unmapped file backed pages and
+	 * slab pages if we are over the defined limits.
+	 *
+	 * A small portion of unmapped file backed pages is needed for
+	 * file I/O otherwise pages read by file I/O will be immediately
+	 * thrown out if the zone is overallocated. So we do not reclaim
+	 * if less than a specified percentage of the zone is used by
+	 * unmapped file backed pages.
+	 */
+	if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
+	    zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
+		return ZONE_RECLAIM_FULL;
+
+	if (!zone_reclaimable(zone))
+		return ZONE_RECLAIM_FULL;
+
+	/*
+	 * Do not scan if the allocation should not be delayed.
+	 */
+	if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC))
+		return ZONE_RECLAIM_NOSCAN;
+
+	/*
+	 * Only run zone reclaim on the local zone or on zones that do not
+	 * have associated processors. This will favor the local processor
+	 * over remote processors and spread off node memory allocations
+	 * as wide as possible.
+	 */
+	node_id = zone_to_nid(zone);
+	if (node_state(node_id, N_CPU) && node_id != numa_node_id())
+		return ZONE_RECLAIM_NOSCAN;
+
+	if (test_and_set_bit(ZONE_RECLAIM_LOCKED, &zone->flags))
+		return ZONE_RECLAIM_NOSCAN;
+
+	ret = __zone_reclaim(zone, gfp_mask, order);
+	clear_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
+
+	if (!ret)
+		count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
+
+	return ret;
+}
+#endif
+
+/*
+ * page_evictable - test whether a page is evictable
+ * @page: the page to test
+ *
+ * Test whether page is evictable--i.e., should be placed on active/inactive
+ * lists vs unevictable list.
+ *
+ * Reasons page might not be evictable:
+ * (1) page's mapping marked unevictable
+ * (2) page is part of an mlocked VMA
+ *
+ */
+int page_evictable(struct page *page)
+{
+	return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
+}
+
+#ifdef CONFIG_SHMEM
+/**
+ * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list
+ * @pages:	array of pages to check
+ * @nr_pages:	number of pages to check
+ *
+ * Checks pages for evictability and moves them to the appropriate lru list.
+ *
+ * This function is only used for SysV IPC SHM_UNLOCK.
+ */
+void check_move_unevictable_pages(struct page **pages, int nr_pages)
+{
+	struct lruvec *lruvec;
+	struct zone *zone = NULL;
+	int pgscanned = 0;
+	int pgrescued = 0;
+	int i;
+
+	for (i = 0; i < nr_pages; i++) {
+		struct page *page = pages[i];
+		struct zone *pagezone;
+
+		pgscanned++;
+		pagezone = page_zone(page);
+		if (pagezone != zone) {
+			if (zone)
+				spin_unlock_irq(&zone->lru_lock);
+			zone = pagezone;
+			spin_lock_irq(&zone->lru_lock);
+		}
+		lruvec = mem_cgroup_page_lruvec(page, zone);
+
+		if (!PageLRU(page) || !PageUnevictable(page))
+			continue;
+
+		if (page_evictable(page)) {
+			enum lru_list lru = page_lru_base_type(page);
+
+			VM_BUG_ON_PAGE(PageActive(page), page);
+			ClearPageUnevictable(page);
+			del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE);
+			add_page_to_lru_list(page, lruvec, lru);
+			pgrescued++;
+		}
+	}
+
+	if (zone) {
+		__count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
+		__count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
+		spin_unlock_irq(&zone->lru_lock);
+	}
+}
+#endif /* CONFIG_SHMEM */
diff --git a/mm/vmstat.c b/mm/vmstat.c
new file mode 100644
index 0000000..c54fd29
--- /dev/null
+++ b/mm/vmstat.c
@@ -0,0 +1,1724 @@
+/*
+ *  linux/mm/vmstat.c
+ *
+ *  Manages VM statistics
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *
+ *  zoned VM statistics
+ *  Copyright (C) 2006 Silicon Graphics, Inc.,
+ *		Christoph Lameter <christoph@lameter.com>
+ *  Copyright (C) 2008-2014 Christoph Lameter
+ */
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/vmstat.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/sched.h>
+#include <linux/math64.h>
+#include <linux/writeback.h>
+#include <linux/compaction.h>
+#include <linux/mm_inline.h>
+#include <linux/page_ext.h>
+#include <linux/page_owner.h>
+
+#include "internal.h"
+
+#ifdef CONFIG_VM_EVENT_COUNTERS
+DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
+EXPORT_PER_CPU_SYMBOL(vm_event_states);
+
+static void sum_vm_events(unsigned long *ret)
+{
+	int cpu;
+	int i;
+
+	memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
+
+	for_each_online_cpu(cpu) {
+		struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
+
+		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
+			ret[i] += this->event[i];
+	}
+}
+
+/*
+ * Accumulate the vm event counters across all CPUs.
+ * The result is unavoidably approximate - it can change
+ * during and after execution of this function.
+*/
+void all_vm_events(unsigned long *ret)
+{
+	get_online_cpus();
+	sum_vm_events(ret);
+	put_online_cpus();
+}
+EXPORT_SYMBOL_GPL(all_vm_events);
+
+/*
+ * Fold the foreign cpu events into our own.
+ *
+ * This is adding to the events on one processor
+ * but keeps the global counts constant.
+ */
+void vm_events_fold_cpu(int cpu)
+{
+	struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
+	int i;
+
+	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
+		count_vm_events(i, fold_state->event[i]);
+		fold_state->event[i] = 0;
+	}
+}
+
+#endif /* CONFIG_VM_EVENT_COUNTERS */
+
+/*
+ * Manage combined zone based / global counters
+ *
+ * vm_stat contains the global counters
+ */
+atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
+EXPORT_SYMBOL(vm_stat);
+
+#ifdef CONFIG_SMP
+
+int calculate_pressure_threshold(struct zone *zone)
+{
+	int threshold;
+	int watermark_distance;
+
+	/*
+	 * As vmstats are not up to date, there is drift between the estimated
+	 * and real values. For high thresholds and a high number of CPUs, it
+	 * is possible for the min watermark to be breached while the estimated
+	 * value looks fine. The pressure threshold is a reduced value such
+	 * that even the maximum amount of drift will not accidentally breach
+	 * the min watermark
+	 */
+	watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
+	threshold = max(1, (int)(watermark_distance / num_online_cpus()));
+
+	/*
+	 * Maximum threshold is 125
+	 */
+	threshold = min(125, threshold);
+
+	return threshold;
+}
+
+int calculate_normal_threshold(struct zone *zone)
+{
+	int threshold;
+	int mem;	/* memory in 128 MB units */
+
+	/*
+	 * The threshold scales with the number of processors and the amount
+	 * of memory per zone. More memory means that we can defer updates for
+	 * longer, more processors could lead to more contention.
+ 	 * fls() is used to have a cheap way of logarithmic scaling.
+	 *
+	 * Some sample thresholds:
+	 *
+	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
+	 * ------------------------------------------------------------------
+	 * 8		1		1	0.9-1 GB	4
+	 * 16		2		2	0.9-1 GB	4
+	 * 20 		2		2	1-2 GB		5
+	 * 24		2		2	2-4 GB		6
+	 * 28		2		2	4-8 GB		7
+	 * 32		2		2	8-16 GB		8
+	 * 4		2		2	<128M		1
+	 * 30		4		3	2-4 GB		5
+	 * 48		4		3	8-16 GB		8
+	 * 32		8		4	1-2 GB		4
+	 * 32		8		4	0.9-1GB		4
+	 * 10		16		5	<128M		1
+	 * 40		16		5	900M		4
+	 * 70		64		7	2-4 GB		5
+	 * 84		64		7	4-8 GB		6
+	 * 108		512		9	4-8 GB		6
+	 * 125		1024		10	8-16 GB		8
+	 * 125		1024		10	16-32 GB	9
+	 */
+
+	mem = zone->managed_pages >> (27 - PAGE_SHIFT);
+
+	threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
+
+	/*
+	 * Maximum threshold is 125
+	 */
+	threshold = min(125, threshold);
+
+	return threshold;
+}
+
+/*
+ * Refresh the thresholds for each zone.
+ */
+void refresh_zone_stat_thresholds(void)
+{
+	struct zone *zone;
+	int cpu;
+	int threshold;
+
+	for_each_populated_zone(zone) {
+		unsigned long max_drift, tolerate_drift;
+
+		threshold = calculate_normal_threshold(zone);
+
+		for_each_online_cpu(cpu)
+			per_cpu_ptr(zone->pageset, cpu)->stat_threshold
+							= threshold;
+
+		/*
+		 * Only set percpu_drift_mark if there is a danger that
+		 * NR_FREE_PAGES reports the low watermark is ok when in fact
+		 * the min watermark could be breached by an allocation
+		 */
+		tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
+		max_drift = num_online_cpus() * threshold;
+		if (max_drift > tolerate_drift)
+			zone->percpu_drift_mark = high_wmark_pages(zone) +
+					max_drift;
+	}
+}
+
+void set_pgdat_percpu_threshold(pg_data_t *pgdat,
+				int (*calculate_pressure)(struct zone *))
+{
+	struct zone *zone;
+	int cpu;
+	int threshold;
+	int i;
+
+	for (i = 0; i < pgdat->nr_zones; i++) {
+		zone = &pgdat->node_zones[i];
+		if (!zone->percpu_drift_mark)
+			continue;
+
+		threshold = (*calculate_pressure)(zone);
+		for_each_online_cpu(cpu)
+			per_cpu_ptr(zone->pageset, cpu)->stat_threshold
+							= threshold;
+	}
+}
+
+/*
+ * For use when we know that interrupts are disabled,
+ * or when we know that preemption is disabled and that
+ * particular counter cannot be updated from interrupt context.
+ */
+void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
+			   long delta)
+{
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
+	long x;
+	long t;
+
+	x = delta + __this_cpu_read(*p);
+
+	t = __this_cpu_read(pcp->stat_threshold);
+
+	if (unlikely(x > t || x < -t)) {
+		zone_page_state_add(x, zone, item);
+		x = 0;
+	}
+	__this_cpu_write(*p, x);
+}
+EXPORT_SYMBOL(__mod_zone_page_state);
+
+/*
+ * Optimized increment and decrement functions.
+ *
+ * These are only for a single page and therefore can take a struct page *
+ * argument instead of struct zone *. This allows the inclusion of the code
+ * generated for page_zone(page) into the optimized functions.
+ *
+ * No overflow check is necessary and therefore the differential can be
+ * incremented or decremented in place which may allow the compilers to
+ * generate better code.
+ * The increment or decrement is known and therefore one boundary check can
+ * be omitted.
+ *
+ * NOTE: These functions are very performance sensitive. Change only
+ * with care.
+ *
+ * Some processors have inc/dec instructions that are atomic vs an interrupt.
+ * However, the code must first determine the differential location in a zone
+ * based on the processor number and then inc/dec the counter. There is no
+ * guarantee without disabling preemption that the processor will not change
+ * in between and therefore the atomicity vs. interrupt cannot be exploited
+ * in a useful way here.
+ */
+void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
+{
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
+	s8 v, t;
+
+	v = __this_cpu_inc_return(*p);
+	t = __this_cpu_read(pcp->stat_threshold);
+	if (unlikely(v > t)) {
+		s8 overstep = t >> 1;
+
+		zone_page_state_add(v + overstep, zone, item);
+		__this_cpu_write(*p, -overstep);
+	}
+}
+
+void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	__inc_zone_state(page_zone(page), item);
+}
+EXPORT_SYMBOL(__inc_zone_page_state);
+
+void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
+{
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
+	s8 v, t;
+
+	v = __this_cpu_dec_return(*p);
+	t = __this_cpu_read(pcp->stat_threshold);
+	if (unlikely(v < - t)) {
+		s8 overstep = t >> 1;
+
+		zone_page_state_add(v - overstep, zone, item);
+		__this_cpu_write(*p, overstep);
+	}
+}
+
+void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	__dec_zone_state(page_zone(page), item);
+}
+EXPORT_SYMBOL(__dec_zone_page_state);
+
+#ifdef CONFIG_HAVE_CMPXCHG_LOCAL
+/*
+ * If we have cmpxchg_local support then we do not need to incur the overhead
+ * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
+ *
+ * mod_state() modifies the zone counter state through atomic per cpu
+ * operations.
+ *
+ * Overstep mode specifies how overstep should handled:
+ *     0       No overstepping
+ *     1       Overstepping half of threshold
+ *     -1      Overstepping minus half of threshold
+*/
+static inline void mod_state(struct zone *zone, enum zone_stat_item item,
+			     long delta, int overstep_mode)
+{
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
+	long o, n, t, z;
+
+	do {
+		z = 0;  /* overflow to zone counters */
+
+		/*
+		 * The fetching of the stat_threshold is racy. We may apply
+		 * a counter threshold to the wrong the cpu if we get
+		 * rescheduled while executing here. However, the next
+		 * counter update will apply the threshold again and
+		 * therefore bring the counter under the threshold again.
+		 *
+		 * Most of the time the thresholds are the same anyways
+		 * for all cpus in a zone.
+		 */
+		t = this_cpu_read(pcp->stat_threshold);
+
+		o = this_cpu_read(*p);
+		n = delta + o;
+
+		if (n > t || n < -t) {
+			int os = overstep_mode * (t >> 1) ;
+
+			/* Overflow must be added to zone counters */
+			z = n + os;
+			n = -os;
+		}
+	} while (this_cpu_cmpxchg(*p, o, n) != o);
+
+	if (z)
+		zone_page_state_add(z, zone, item);
+}
+
+void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
+			 long delta)
+{
+	mod_state(zone, item, delta, 0);
+}
+EXPORT_SYMBOL(mod_zone_page_state);
+
+void inc_zone_state(struct zone *zone, enum zone_stat_item item)
+{
+	mod_state(zone, item, 1, 1);
+}
+
+void inc_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	mod_state(page_zone(page), item, 1, 1);
+}
+EXPORT_SYMBOL(inc_zone_page_state);
+
+void dec_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	mod_state(page_zone(page), item, -1, -1);
+}
+EXPORT_SYMBOL(dec_zone_page_state);
+#else
+/*
+ * Use interrupt disable to serialize counter updates
+ */
+void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
+			 long delta)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__mod_zone_page_state(zone, item, delta);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(mod_zone_page_state);
+
+void inc_zone_state(struct zone *zone, enum zone_stat_item item)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__inc_zone_state(zone, item);
+	local_irq_restore(flags);
+}
+
+void inc_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	unsigned long flags;
+	struct zone *zone;
+
+	zone = page_zone(page);
+	local_irq_save(flags);
+	__inc_zone_state(zone, item);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(inc_zone_page_state);
+
+void dec_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__dec_zone_page_state(page, item);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(dec_zone_page_state);
+#endif
+
+
+/*
+ * Fold a differential into the global counters.
+ * Returns the number of counters updated.
+ */
+static int fold_diff(int *diff)
+{
+	int i;
+	int changes = 0;
+
+	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+		if (diff[i]) {
+			atomic_long_add(diff[i], &vm_stat[i]);
+			changes++;
+	}
+	return changes;
+}
+
+/*
+ * Update the zone counters for the current cpu.
+ *
+ * Note that refresh_cpu_vm_stats strives to only access
+ * node local memory. The per cpu pagesets on remote zones are placed
+ * in the memory local to the processor using that pageset. So the
+ * loop over all zones will access a series of cachelines local to
+ * the processor.
+ *
+ * The call to zone_page_state_add updates the cachelines with the
+ * statistics in the remote zone struct as well as the global cachelines
+ * with the global counters. These could cause remote node cache line
+ * bouncing and will have to be only done when necessary.
+ *
+ * The function returns the number of global counters updated.
+ */
+static int refresh_cpu_vm_stats(void)
+{
+	struct zone *zone;
+	int i;
+	int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
+	int changes = 0;
+
+	for_each_populated_zone(zone) {
+		struct per_cpu_pageset __percpu *p = zone->pageset;
+
+		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
+			int v;
+
+			v = this_cpu_xchg(p->vm_stat_diff[i], 0);
+			if (v) {
+
+				atomic_long_add(v, &zone->vm_stat[i]);
+				global_diff[i] += v;
+#ifdef CONFIG_NUMA
+				/* 3 seconds idle till flush */
+				__this_cpu_write(p->expire, 3);
+#endif
+			}
+		}
+		cond_resched();
+#ifdef CONFIG_NUMA
+		/*
+		 * Deal with draining the remote pageset of this
+		 * processor
+		 *
+		 * Check if there are pages remaining in this pageset
+		 * if not then there is nothing to expire.
+		 */
+		if (!__this_cpu_read(p->expire) ||
+			       !__this_cpu_read(p->pcp.count))
+			continue;
+
+		/*
+		 * We never drain zones local to this processor.
+		 */
+		if (zone_to_nid(zone) == numa_node_id()) {
+			__this_cpu_write(p->expire, 0);
+			continue;
+		}
+
+		if (__this_cpu_dec_return(p->expire))
+			continue;
+
+		if (__this_cpu_read(p->pcp.count)) {
+			drain_zone_pages(zone, this_cpu_ptr(&p->pcp));
+			changes++;
+		}
+#endif
+	}
+	changes += fold_diff(global_diff);
+	return changes;
+}
+
+/*
+ * Fold the data for an offline cpu into the global array.
+ * There cannot be any access by the offline cpu and therefore
+ * synchronization is simplified.
+ */
+void cpu_vm_stats_fold(int cpu)
+{
+	struct zone *zone;
+	int i;
+	int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
+
+	for_each_populated_zone(zone) {
+		struct per_cpu_pageset *p;
+
+		p = per_cpu_ptr(zone->pageset, cpu);
+
+		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+			if (p->vm_stat_diff[i]) {
+				int v;
+
+				v = p->vm_stat_diff[i];
+				p->vm_stat_diff[i] = 0;
+				atomic_long_add(v, &zone->vm_stat[i]);
+				global_diff[i] += v;
+			}
+	}
+
+	fold_diff(global_diff);
+}
+
+/*
+ * this is only called if !populated_zone(zone), which implies no other users of
+ * pset->vm_stat_diff[] exsist.
+ */
+void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
+{
+	int i;
+
+	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+		if (pset->vm_stat_diff[i]) {
+			int v = pset->vm_stat_diff[i];
+			pset->vm_stat_diff[i] = 0;
+			atomic_long_add(v, &zone->vm_stat[i]);
+			atomic_long_add(v, &vm_stat[i]);
+		}
+}
+#endif
+
+#ifdef CONFIG_NUMA
+/*
+ * zonelist = the list of zones passed to the allocator
+ * z 	    = the zone from which the allocation occurred.
+ *
+ * Must be called with interrupts disabled.
+ *
+ * When __GFP_OTHER_NODE is set assume the node of the preferred
+ * zone is the local node. This is useful for daemons who allocate
+ * memory on behalf of other processes.
+ */
+void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
+{
+	if (z->zone_pgdat == preferred_zone->zone_pgdat) {
+		__inc_zone_state(z, NUMA_HIT);
+	} else {
+		__inc_zone_state(z, NUMA_MISS);
+		__inc_zone_state(preferred_zone, NUMA_FOREIGN);
+	}
+	if (z->node == ((flags & __GFP_OTHER_NODE) ?
+			preferred_zone->node : numa_node_id()))
+		__inc_zone_state(z, NUMA_LOCAL);
+	else
+		__inc_zone_state(z, NUMA_OTHER);
+}
+
+/*
+ * Determine the per node value of a stat item.
+ */
+unsigned long node_page_state(int node, enum zone_stat_item item)
+{
+	struct zone *zones = NODE_DATA(node)->node_zones;
+
+	return
+#ifdef CONFIG_ZONE_DMA
+		zone_page_state(&zones[ZONE_DMA], item) +
+#endif
+#ifdef CONFIG_ZONE_DMA32
+		zone_page_state(&zones[ZONE_DMA32], item) +
+#endif
+#ifdef CONFIG_HIGHMEM
+		zone_page_state(&zones[ZONE_HIGHMEM], item) +
+#endif
+		zone_page_state(&zones[ZONE_NORMAL], item) +
+		zone_page_state(&zones[ZONE_MOVABLE], item);
+}
+
+#endif
+
+#ifdef CONFIG_COMPACTION
+
+struct contig_page_info {
+	unsigned long free_pages;
+	unsigned long free_blocks_total;
+	unsigned long free_blocks_suitable;
+};
+
+/*
+ * Calculate the number of free pages in a zone, how many contiguous
+ * pages are free and how many are large enough to satisfy an allocation of
+ * the target size. Note that this function makes no attempt to estimate
+ * how many suitable free blocks there *might* be if MOVABLE pages were
+ * migrated. Calculating that is possible, but expensive and can be
+ * figured out from userspace
+ */
+static void fill_contig_page_info(struct zone *zone,
+				unsigned int suitable_order,
+				struct contig_page_info *info)
+{
+	unsigned int order;
+
+	info->free_pages = 0;
+	info->free_blocks_total = 0;
+	info->free_blocks_suitable = 0;
+
+	for (order = 0; order < MAX_ORDER; order++) {
+		unsigned long blocks;
+
+		/* Count number of free blocks */
+		blocks = zone->free_area[order].nr_free;
+		info->free_blocks_total += blocks;
+
+		/* Count free base pages */
+		info->free_pages += blocks << order;
+
+		/* Count the suitable free blocks */
+		if (order >= suitable_order)
+			info->free_blocks_suitable += blocks <<
+						(order - suitable_order);
+	}
+}
+
+/*
+ * A fragmentation index only makes sense if an allocation of a requested
+ * size would fail. If that is true, the fragmentation index indicates
+ * whether external fragmentation or a lack of memory was the problem.
+ * The value can be used to determine if page reclaim or compaction
+ * should be used
+ */
+static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
+{
+	unsigned long requested = 1UL << order;
+
+	if (!info->free_blocks_total)
+		return 0;
+
+	/* Fragmentation index only makes sense when a request would fail */
+	if (info->free_blocks_suitable)
+		return -1000;
+
+	/*
+	 * Index is between 0 and 1 so return within 3 decimal places
+	 *
+	 * 0 => allocation would fail due to lack of memory
+	 * 1 => allocation would fail due to fragmentation
+	 */
+	return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
+}
+
+/* Same as __fragmentation index but allocs contig_page_info on stack */
+int fragmentation_index(struct zone *zone, unsigned int order)
+{
+	struct contig_page_info info;
+
+	fill_contig_page_info(zone, order, &info);
+	return __fragmentation_index(order, &info);
+}
+#endif
+
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
+#ifdef CONFIG_ZONE_DMA
+#define TEXT_FOR_DMA(xx) xx "_dma",
+#else
+#define TEXT_FOR_DMA(xx)
+#endif
+
+#ifdef CONFIG_ZONE_DMA32
+#define TEXT_FOR_DMA32(xx) xx "_dma32",
+#else
+#define TEXT_FOR_DMA32(xx)
+#endif
+
+#ifdef CONFIG_HIGHMEM
+#define TEXT_FOR_HIGHMEM(xx) xx "_high",
+#else
+#define TEXT_FOR_HIGHMEM(xx)
+#endif
+
+#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
+					TEXT_FOR_HIGHMEM(xx) xx "_movable",
+
+const char * const vmstat_text[] = {
+	/* enum zone_stat_item countes */
+	"nr_free_pages",
+	"nr_alloc_batch",
+	"nr_inactive_anon",
+	"nr_active_anon",
+	"nr_inactive_file",
+	"nr_active_file",
+	"nr_unevictable",
+	"nr_mlock",
+	"nr_anon_pages",
+	"nr_mapped",
+	"nr_file_pages",
+	"nr_dirty",
+	"nr_writeback",
+	"nr_slab_reclaimable",
+	"nr_slab_unreclaimable",
+	"nr_page_table_pages",
+	"nr_kernel_stack",
+	"nr_unstable",
+	"nr_bounce",
+	"nr_vmscan_write",
+	"nr_vmscan_immediate_reclaim",
+	"nr_writeback_temp",
+	"nr_isolated_anon",
+	"nr_isolated_file",
+	"nr_shmem",
+	"nr_dirtied",
+	"nr_written",
+	"nr_pages_scanned",
+
+#ifdef CONFIG_NUMA
+	"numa_hit",
+	"numa_miss",
+	"numa_foreign",
+	"numa_interleave",
+	"numa_local",
+	"numa_other",
+#endif
+	"workingset_refault",
+	"workingset_activate",
+	"workingset_nodereclaim",
+	"nr_anon_transparent_hugepages",
+	"nr_free_cma",
+
+	/* enum writeback_stat_item counters */
+	"nr_dirty_threshold",
+	"nr_dirty_background_threshold",
+
+#ifdef CONFIG_VM_EVENT_COUNTERS
+	/* enum vm_event_item counters */
+	"pgpgin",
+	"pgpgout",
+	"pswpin",
+	"pswpout",
+
+	TEXTS_FOR_ZONES("pgalloc")
+
+	"pgfree",
+	"pgactivate",
+	"pgdeactivate",
+
+	"pgfault",
+	"pgmajfault",
+
+	TEXTS_FOR_ZONES("pgrefill")
+	TEXTS_FOR_ZONES("pgsteal_kswapd")
+	TEXTS_FOR_ZONES("pgsteal_direct")
+	TEXTS_FOR_ZONES("pgscan_kswapd")
+	TEXTS_FOR_ZONES("pgscan_direct")
+	"pgscan_direct_throttle",
+
+#ifdef CONFIG_NUMA
+	"zone_reclaim_failed",
+#endif
+	"pginodesteal",
+	"slabs_scanned",
+	"kswapd_inodesteal",
+	"kswapd_low_wmark_hit_quickly",
+	"kswapd_high_wmark_hit_quickly",
+	"pageoutrun",
+	"allocstall",
+
+	"pgrotated",
+
+	"drop_pagecache",
+	"drop_slab",
+
+#ifdef CONFIG_NUMA_BALANCING
+	"numa_pte_updates",
+	"numa_huge_pte_updates",
+	"numa_hint_faults",
+	"numa_hint_faults_local",
+	"numa_pages_migrated",
+#endif
+#ifdef CONFIG_MIGRATION
+	"pgmigrate_success",
+	"pgmigrate_fail",
+#endif
+#ifdef CONFIG_COMPACTION
+	"compact_migrate_scanned",
+	"compact_free_scanned",
+	"compact_isolated",
+	"compact_stall",
+	"compact_fail",
+	"compact_success",
+#endif
+
+#ifdef CONFIG_HUGETLB_PAGE
+	"htlb_buddy_alloc_success",
+	"htlb_buddy_alloc_fail",
+#endif
+	"unevictable_pgs_culled",
+	"unevictable_pgs_scanned",
+	"unevictable_pgs_rescued",
+	"unevictable_pgs_mlocked",
+	"unevictable_pgs_munlocked",
+	"unevictable_pgs_cleared",
+	"unevictable_pgs_stranded",
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	"thp_fault_alloc",
+	"thp_fault_fallback",
+	"thp_collapse_alloc",
+	"thp_collapse_alloc_failed",
+	"thp_split",
+	"thp_zero_page_alloc",
+	"thp_zero_page_alloc_failed",
+#endif
+#ifdef CONFIG_MEMORY_BALLOON
+	"balloon_inflate",
+	"balloon_deflate",
+#ifdef CONFIG_BALLOON_COMPACTION
+	"balloon_migrate",
+#endif
+#endif /* CONFIG_MEMORY_BALLOON */
+#ifdef CONFIG_DEBUG_TLBFLUSH
+#ifdef CONFIG_SMP
+	"nr_tlb_remote_flush",
+	"nr_tlb_remote_flush_received",
+#endif /* CONFIG_SMP */
+	"nr_tlb_local_flush_all",
+	"nr_tlb_local_flush_one",
+#endif /* CONFIG_DEBUG_TLBFLUSH */
+
+#ifdef CONFIG_DEBUG_VM_VMACACHE
+	"vmacache_find_calls",
+	"vmacache_find_hits",
+	"vmacache_full_flushes",
+#endif
+#endif /* CONFIG_VM_EVENTS_COUNTERS */
+};
+#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
+
+
+#if (defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)) || \
+     defined(CONFIG_PROC_FS)
+static void *frag_start(struct seq_file *m, loff_t *pos)
+{
+	pg_data_t *pgdat;
+	loff_t node = *pos;
+
+	for (pgdat = first_online_pgdat();
+	     pgdat && node;
+	     pgdat = next_online_pgdat(pgdat))
+		--node;
+
+	return pgdat;
+}
+
+static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	(*pos)++;
+	return next_online_pgdat(pgdat);
+}
+
+static void frag_stop(struct seq_file *m, void *arg)
+{
+}
+
+/* Walk all the zones in a node and print using a callback */
+static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
+		void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
+{
+	struct zone *zone;
+	struct zone *node_zones = pgdat->node_zones;
+	unsigned long flags;
+
+	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
+		if (!populated_zone(zone))
+			continue;
+
+		spin_lock_irqsave(&zone->lock, flags);
+		print(m, pgdat, zone);
+		spin_unlock_irqrestore(&zone->lock, flags);
+	}
+}
+#endif
+
+#ifdef CONFIG_PROC_FS
+static char * const migratetype_names[MIGRATE_TYPES] = {
+	"Unmovable",
+	"Movable",
+	"Reclaimable",
+	"HighAtomic",
+#ifdef CONFIG_CMA
+	"CMA",
+#endif
+#ifdef CONFIG_MEMORY_ISOLATION
+	"Isolate",
+#endif
+};
+
+static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
+						struct zone *zone)
+{
+	int order;
+
+	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
+	for (order = 0; order < MAX_ORDER; ++order)
+		seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
+	seq_putc(m, '\n');
+}
+
+/*
+ * This walks the free areas for each zone.
+ */
+static int frag_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+	walk_zones_in_node(m, pgdat, frag_show_print);
+	return 0;
+}
+
+static void pagetypeinfo_showfree_print(struct seq_file *m,
+					pg_data_t *pgdat, struct zone *zone)
+{
+	int order, mtype;
+
+	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
+		seq_printf(m, "Node %4d, zone %8s, type %12s ",
+					pgdat->node_id,
+					zone->name,
+					migratetype_names[mtype]);
+		for (order = 0; order < MAX_ORDER; ++order) {
+			unsigned long freecount = 0;
+			struct free_area *area;
+			struct list_head *curr;
+
+			area = &(zone->free_area[order]);
+
+			list_for_each(curr, &area->free_list[mtype])
+				freecount++;
+			seq_printf(m, "%6lu ", freecount);
+		}
+		seq_putc(m, '\n');
+	}
+}
+
+/* Print out the free pages at each order for each migatetype */
+static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
+{
+	int order;
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	/* Print header */
+	seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
+	for (order = 0; order < MAX_ORDER; ++order)
+		seq_printf(m, "%6d ", order);
+	seq_putc(m, '\n');
+
+	walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
+
+	return 0;
+}
+
+static void pagetypeinfo_showblockcount_print(struct seq_file *m,
+					pg_data_t *pgdat, struct zone *zone)
+{
+	int mtype;
+	unsigned long pfn;
+	unsigned long start_pfn = zone->zone_start_pfn;
+	unsigned long end_pfn = zone_end_pfn(zone);
+	unsigned long count[MIGRATE_TYPES] = { 0, };
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+		struct page *page;
+
+		if (!pfn_valid(pfn))
+			continue;
+
+		page = pfn_to_page(pfn);
+
+		/* Watch for unexpected holes punched in the memmap */
+		if (!memmap_valid_within(pfn, page, zone))
+			continue;
+
+		mtype = get_pageblock_migratetype(page);
+
+		if (mtype < MIGRATE_TYPES)
+			count[mtype]++;
+	}
+
+	/* Print counts */
+	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
+	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
+		seq_printf(m, "%12lu ", count[mtype]);
+	seq_putc(m, '\n');
+}
+
+/* Print out the free pages at each order for each migratetype */
+static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
+{
+	int mtype;
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	seq_printf(m, "\n%-23s", "Number of blocks type ");
+	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
+		seq_printf(m, "%12s ", migratetype_names[mtype]);
+	seq_putc(m, '\n');
+	walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
+
+	return 0;
+}
+
+#ifdef CONFIG_PAGE_OWNER
+static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
+							pg_data_t *pgdat,
+							struct zone *zone)
+{
+	struct page *page;
+	struct page_ext *page_ext;
+	unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
+	unsigned long end_pfn = pfn + zone->spanned_pages;
+	unsigned long count[MIGRATE_TYPES] = { 0, };
+	int pageblock_mt, page_mt;
+	int i;
+
+	/* Scan block by block. First and last block may be incomplete */
+	pfn = zone->zone_start_pfn;
+
+	/*
+	 * Walk the zone in pageblock_nr_pages steps. If a page block spans
+	 * a zone boundary, it will be double counted between zones. This does
+	 * not matter as the mixed block count will still be correct
+	 */
+	for (; pfn < end_pfn; ) {
+		if (!pfn_valid(pfn)) {
+			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
+			continue;
+		}
+
+		block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+		block_end_pfn = min(block_end_pfn, end_pfn);
+
+		page = pfn_to_page(pfn);
+		pageblock_mt = get_pfnblock_migratetype(page, pfn);
+
+		for (; pfn < block_end_pfn; pfn++) {
+			if (!pfn_valid_within(pfn))
+				continue;
+
+			page = pfn_to_page(pfn);
+			if (PageBuddy(page)) {
+				pfn += (1UL << page_order(page)) - 1;
+				continue;
+			}
+
+			if (PageReserved(page))
+				continue;
+
+			page_ext = lookup_page_ext(page);
+
+			if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
+				continue;
+
+			page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
+			if (pageblock_mt != page_mt) {
+				if (is_migrate_cma(pageblock_mt))
+					count[MIGRATE_MOVABLE]++;
+				else
+					count[pageblock_mt]++;
+
+				pfn = block_end_pfn;
+				break;
+			}
+			pfn += (1UL << page_ext->order) - 1;
+		}
+	}
+
+	/* Print counts */
+	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
+	for (i = 0; i < MIGRATE_TYPES; i++)
+		seq_printf(m, "%12lu ", count[i]);
+	seq_putc(m, '\n');
+}
+#endif /* CONFIG_PAGE_OWNER */
+
+/*
+ * Print out the number of pageblocks for each migratetype that contain pages
+ * of other types. This gives an indication of how well fallbacks are being
+ * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
+ * to determine what is going on
+ */
+static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
+{
+#ifdef CONFIG_PAGE_OWNER
+	int mtype;
+
+	if (!page_owner_inited)
+		return;
+
+	drain_all_pages(NULL);
+
+	seq_printf(m, "\n%-23s", "Number of mixed blocks ");
+	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
+		seq_printf(m, "%12s ", migratetype_names[mtype]);
+	seq_putc(m, '\n');
+
+	walk_zones_in_node(m, pgdat, pagetypeinfo_showmixedcount_print);
+#endif /* CONFIG_PAGE_OWNER */
+}
+
+/*
+ * This prints out statistics in relation to grouping pages by mobility.
+ * It is expensive to collect so do not constantly read the file.
+ */
+static int pagetypeinfo_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	/* check memoryless node */
+	if (!node_state(pgdat->node_id, N_MEMORY))
+		return 0;
+
+	seq_printf(m, "Page block order: %d\n", pageblock_order);
+	seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
+	seq_putc(m, '\n');
+	pagetypeinfo_showfree(m, pgdat);
+	pagetypeinfo_showblockcount(m, pgdat);
+	pagetypeinfo_showmixedcount(m, pgdat);
+
+	return 0;
+}
+
+static const struct seq_operations fragmentation_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= frag_show,
+};
+
+static int fragmentation_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &fragmentation_op);
+}
+
+static const struct file_operations fragmentation_file_operations = {
+	.open		= fragmentation_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static const struct seq_operations pagetypeinfo_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= pagetypeinfo_show,
+};
+
+static int pagetypeinfo_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &pagetypeinfo_op);
+}
+
+static const struct file_operations pagetypeinfo_file_ops = {
+	.open		= pagetypeinfo_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
+							struct zone *zone)
+{
+	int i;
+	seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
+	seq_printf(m,
+		   "\n  pages free     %lu"
+		   "\n        min      %lu"
+		   "\n        low      %lu"
+		   "\n        high     %lu"
+		   "\n        scanned  %lu"
+		   "\n        spanned  %lu"
+		   "\n        present  %lu"
+		   "\n        managed  %lu",
+		   zone_page_state(zone, NR_FREE_PAGES),
+		   min_wmark_pages(zone),
+		   low_wmark_pages(zone),
+		   high_wmark_pages(zone),
+		   zone_page_state(zone, NR_PAGES_SCANNED),
+		   zone->spanned_pages,
+		   zone->present_pages,
+		   zone->managed_pages);
+
+	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+		seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
+				zone_page_state(zone, i));
+
+	seq_printf(m,
+		   "\n        protection: (%ld",
+		   zone->lowmem_reserve[0]);
+	for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
+		seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
+	seq_printf(m,
+		   ")"
+		   "\n  pagesets");
+	for_each_online_cpu(i) {
+		struct per_cpu_pageset *pageset;
+
+		pageset = per_cpu_ptr(zone->pageset, i);
+		seq_printf(m,
+			   "\n    cpu: %i"
+			   "\n              count: %i"
+			   "\n              high:  %i"
+			   "\n              batch: %i",
+			   i,
+			   pageset->pcp.count,
+			   pageset->pcp.high,
+			   pageset->pcp.batch);
+#ifdef CONFIG_SMP
+		seq_printf(m, "\n  vm stats threshold: %d",
+				pageset->stat_threshold);
+#endif
+	}
+	seq_printf(m,
+		   "\n  all_unreclaimable: %u"
+		   "\n  start_pfn:         %lu"
+		   "\n  inactive_ratio:    %u",
+		   !zone_reclaimable(zone),
+		   zone->zone_start_pfn,
+		   zone->inactive_ratio);
+	seq_putc(m, '\n');
+}
+
+/*
+ * Output information about zones in @pgdat.
+ */
+static int zoneinfo_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+	walk_zones_in_node(m, pgdat, zoneinfo_show_print);
+	return 0;
+}
+
+static const struct seq_operations zoneinfo_op = {
+	.start	= frag_start, /* iterate over all zones. The same as in
+			       * fragmentation. */
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= zoneinfo_show,
+};
+
+static int zoneinfo_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &zoneinfo_op);
+}
+
+static const struct file_operations proc_zoneinfo_file_operations = {
+	.open		= zoneinfo_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+enum writeback_stat_item {
+	NR_DIRTY_THRESHOLD,
+	NR_DIRTY_BG_THRESHOLD,
+	NR_VM_WRITEBACK_STAT_ITEMS,
+};
+
+static void *vmstat_start(struct seq_file *m, loff_t *pos)
+{
+	unsigned long *v;
+	int i, stat_items_size;
+
+	if (*pos >= ARRAY_SIZE(vmstat_text))
+		return NULL;
+	stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
+			  NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
+
+#ifdef CONFIG_VM_EVENT_COUNTERS
+	stat_items_size += sizeof(struct vm_event_state);
+#endif
+
+	v = kmalloc(stat_items_size, GFP_KERNEL);
+	m->private = v;
+	if (!v)
+		return ERR_PTR(-ENOMEM);
+	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+		v[i] = global_page_state(i);
+	v += NR_VM_ZONE_STAT_ITEMS;
+
+	global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
+			    v + NR_DIRTY_THRESHOLD);
+	v += NR_VM_WRITEBACK_STAT_ITEMS;
+
+#ifdef CONFIG_VM_EVENT_COUNTERS
+	all_vm_events(v);
+	v[PGPGIN] /= 2;		/* sectors -> kbytes */
+	v[PGPGOUT] /= 2;
+#endif
+	return (unsigned long *)m->private + *pos;
+}
+
+static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
+{
+	(*pos)++;
+	if (*pos >= ARRAY_SIZE(vmstat_text))
+		return NULL;
+	return (unsigned long *)m->private + *pos;
+}
+
+static int vmstat_show(struct seq_file *m, void *arg)
+{
+	unsigned long *l = arg;
+	unsigned long off = l - (unsigned long *)m->private;
+
+	seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
+	return 0;
+}
+
+static void vmstat_stop(struct seq_file *m, void *arg)
+{
+	kfree(m->private);
+	m->private = NULL;
+}
+
+static const struct seq_operations vmstat_op = {
+	.start	= vmstat_start,
+	.next	= vmstat_next,
+	.stop	= vmstat_stop,
+	.show	= vmstat_show,
+};
+
+static int vmstat_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &vmstat_op);
+}
+
+static const struct file_operations proc_vmstat_file_operations = {
+	.open		= vmstat_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+#endif /* CONFIG_PROC_FS */
+
+#ifdef CONFIG_SMP
+static struct workqueue_struct *vmstat_wq;
+static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
+int sysctl_stat_interval __read_mostly = HZ;
+static cpumask_var_t cpu_stat_off;
+
+static void vmstat_update(struct work_struct *w)
+{
+	if (refresh_cpu_vm_stats()) {
+		/*
+		 * Counters were updated so we expect more updates
+		 * to occur in the future. Keep on running the
+		 * update worker thread.
+		 */
+		queue_delayed_work_on(smp_processor_id(), vmstat_wq,
+			this_cpu_ptr(&vmstat_work),
+			round_jiffies_relative(sysctl_stat_interval));
+	} else {
+		/*
+		 * We did not update any counters so the app may be in
+		 * a mode where it does not cause counter updates.
+		 * We may be uselessly running vmstat_update.
+		 * Defer the checking for differentials to the
+		 * shepherd thread on a different processor.
+		 */
+		int r;
+		/*
+		 * Shepherd work thread does not race since it never
+		 * changes the bit if its zero but the cpu
+		 * online / off line code may race if
+		 * worker threads are still allowed during
+		 * shutdown / startup.
+		 */
+		r = cpumask_test_and_set_cpu(smp_processor_id(),
+			cpu_stat_off);
+		VM_BUG_ON(r);
+	}
+}
+
+/*
+ * Check if the diffs for a certain cpu indicate that
+ * an update is needed.
+ */
+static bool need_update(int cpu)
+{
+	struct zone *zone;
+
+	for_each_populated_zone(zone) {
+		struct per_cpu_pageset *p = per_cpu_ptr(zone->pageset, cpu);
+
+		BUILD_BUG_ON(sizeof(p->vm_stat_diff[0]) != 1);
+		/*
+		 * The fast way of checking if there are any vmstat diffs.
+		 * This works because the diffs are byte sized items.
+		 */
+		if (memchr_inv(p->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS))
+			return true;
+
+	}
+	return false;
+}
+
+
+/*
+ * Shepherd worker thread that checks the
+ * differentials of processors that have their worker
+ * threads for vm statistics updates disabled because of
+ * inactivity.
+ */
+static void vmstat_shepherd(struct work_struct *w);
+
+static DECLARE_DELAYED_WORK(shepherd, vmstat_shepherd);
+
+static void vmstat_shepherd(struct work_struct *w)
+{
+	int cpu;
+
+	get_online_cpus();
+	/* Check processors whose vmstat worker threads have been disabled */
+	for_each_cpu(cpu, cpu_stat_off)
+		if (need_update(cpu) &&
+			cpumask_test_and_clear_cpu(cpu, cpu_stat_off))
+
+			queue_delayed_work_on(cpu, vmstat_wq,
+				&per_cpu(vmstat_work, cpu), 0);
+
+	put_online_cpus();
+
+	schedule_delayed_work(&shepherd,
+		round_jiffies_relative(sysctl_stat_interval));
+
+}
+
+static void __init start_shepherd_timer(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		INIT_DELAYED_WORK(per_cpu_ptr(&vmstat_work, cpu),
+			vmstat_update);
+
+	if (!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL))
+		BUG();
+	cpumask_copy(cpu_stat_off, cpu_online_mask);
+
+	vmstat_wq = alloc_workqueue("vmstat", WQ_FREEZABLE|WQ_MEM_RECLAIM, 0);
+	schedule_delayed_work(&shepherd,
+		round_jiffies_relative(sysctl_stat_interval));
+}
+
+static void vmstat_cpu_dead(int node)
+{
+	int cpu;
+
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		if (cpu_to_node(cpu) == node)
+			goto end;
+
+	node_clear_state(node, N_CPU);
+end:
+	put_online_cpus();
+}
+
+/*
+ * Use the cpu notifier to insure that the thresholds are recalculated
+ * when necessary.
+ */
+static int vmstat_cpuup_callback(struct notifier_block *nfb,
+		unsigned long action,
+		void *hcpu)
+{
+	long cpu = (long)hcpu;
+
+	switch (action) {
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		refresh_zone_stat_thresholds();
+		node_set_state(cpu_to_node(cpu), N_CPU);
+		cpumask_set_cpu(cpu, cpu_stat_off);
+		break;
+	case CPU_DOWN_PREPARE:
+	case CPU_DOWN_PREPARE_FROZEN:
+		cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
+		cpumask_clear_cpu(cpu, cpu_stat_off);
+		break;
+	case CPU_DOWN_FAILED:
+	case CPU_DOWN_FAILED_FROZEN:
+		cpumask_set_cpu(cpu, cpu_stat_off);
+		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		refresh_zone_stat_thresholds();
+		vmstat_cpu_dead(cpu_to_node(cpu));
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block vmstat_notifier =
+	{ &vmstat_cpuup_callback, NULL, 0 };
+#endif
+
+static int __init setup_vmstat(void)
+{
+#ifdef CONFIG_SMP
+	cpu_notifier_register_begin();
+	__register_cpu_notifier(&vmstat_notifier);
+
+	start_shepherd_timer();
+	cpu_notifier_register_done();
+#endif
+#ifdef CONFIG_PROC_FS
+	proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
+	proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
+	proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
+	proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
+#endif
+	return 0;
+}
+module_init(setup_vmstat)
+
+#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
+
+/*
+ * Return an index indicating how much of the available free memory is
+ * unusable for an allocation of the requested size.
+ */
+static int unusable_free_index(unsigned int order,
+				struct contig_page_info *info)
+{
+	/* No free memory is interpreted as all free memory is unusable */
+	if (info->free_pages == 0)
+		return 1000;
+
+	/*
+	 * Index should be a value between 0 and 1. Return a value to 3
+	 * decimal places.
+	 *
+	 * 0 => no fragmentation
+	 * 1 => high fragmentation
+	 */
+	return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
+
+}
+
+static void unusable_show_print(struct seq_file *m,
+					pg_data_t *pgdat, struct zone *zone)
+{
+	unsigned int order;
+	int index;
+	struct contig_page_info info;
+
+	seq_printf(m, "Node %d, zone %8s ",
+				pgdat->node_id,
+				zone->name);
+	for (order = 0; order < MAX_ORDER; ++order) {
+		fill_contig_page_info(zone, order, &info);
+		index = unusable_free_index(order, &info);
+		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
+	}
+
+	seq_putc(m, '\n');
+}
+
+/*
+ * Display unusable free space index
+ *
+ * The unusable free space index measures how much of the available free
+ * memory cannot be used to satisfy an allocation of a given size and is a
+ * value between 0 and 1. The higher the value, the more of free memory is
+ * unusable and by implication, the worse the external fragmentation is. This
+ * can be expressed as a percentage by multiplying by 100.
+ */
+static int unusable_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	/* check memoryless node */
+	if (!node_state(pgdat->node_id, N_MEMORY))
+		return 0;
+
+	walk_zones_in_node(m, pgdat, unusable_show_print);
+
+	return 0;
+}
+
+static const struct seq_operations unusable_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= unusable_show,
+};
+
+static int unusable_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &unusable_op);
+}
+
+static const struct file_operations unusable_file_ops = {
+	.open		= unusable_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static void extfrag_show_print(struct seq_file *m,
+					pg_data_t *pgdat, struct zone *zone)
+{
+	unsigned int order;
+	int index;
+
+	/* Alloc on stack as interrupts are disabled for zone walk */
+	struct contig_page_info info;
+
+	seq_printf(m, "Node %d, zone %8s ",
+				pgdat->node_id,
+				zone->name);
+	for (order = 0; order < MAX_ORDER; ++order) {
+		fill_contig_page_info(zone, order, &info);
+		index = __fragmentation_index(order, &info);
+		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
+	}
+
+	seq_putc(m, '\n');
+}
+
+/*
+ * Display fragmentation index for orders that allocations would fail for
+ */
+static int extfrag_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	walk_zones_in_node(m, pgdat, extfrag_show_print);
+
+	return 0;
+}
+
+static const struct seq_operations extfrag_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= extfrag_show,
+};
+
+static int extfrag_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &extfrag_op);
+}
+
+static const struct file_operations extfrag_file_ops = {
+	.open		= extfrag_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static int __init extfrag_debug_init(void)
+{
+	struct dentry *extfrag_debug_root;
+
+	extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
+	if (!extfrag_debug_root)
+		return -ENOMEM;
+
+	if (!debugfs_create_file("unusable_index", 0444,
+			extfrag_debug_root, NULL, &unusable_file_ops))
+		goto fail;
+
+	if (!debugfs_create_file("extfrag_index", 0444,
+			extfrag_debug_root, NULL, &extfrag_file_ops))
+		goto fail;
+
+	return 0;
+fail:
+	debugfs_remove_recursive(extfrag_debug_root);
+	return -ENOMEM;
+}
+
+module_init(extfrag_debug_init);
+#endif
diff --git a/mm/workingset.c b/mm/workingset.c
new file mode 100644
index 0000000..df66f42
--- /dev/null
+++ b/mm/workingset.c
@@ -0,0 +1,413 @@
+/*
+ * Workingset detection
+ *
+ * Copyright (C) 2013 Red Hat, Inc., Johannes Weiner
+ */
+
+#include <linux/memcontrol.h>
+#include <linux/writeback.h>
+#include <linux/pagemap.h>
+#include <linux/atomic.h>
+#include <linux/module.h>
+#include <linux/swap.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+
+/*
+ *		Double CLOCK lists
+ *
+ * Per zone, two clock lists are maintained for file pages: the
+ * inactive and the active list.  Freshly faulted pages start out at
+ * the head of the inactive list and page reclaim scans pages from the
+ * tail.  Pages that are accessed multiple times on the inactive list
+ * are promoted to the active list, to protect them from reclaim,
+ * whereas active pages are demoted to the inactive list when the
+ * active list grows too big.
+ *
+ *   fault ------------------------+
+ *                                 |
+ *              +--------------+   |            +-------------+
+ *   reclaim <- |   inactive   | <-+-- demotion |    active   | <--+
+ *              +--------------+                +-------------+    |
+ *                     |                                           |
+ *                     +-------------- promotion ------------------+
+ *
+ *
+ *		Access frequency and refault distance
+ *
+ * A workload is thrashing when its pages are frequently used but they
+ * are evicted from the inactive list every time before another access
+ * would have promoted them to the active list.
+ *
+ * In cases where the average access distance between thrashing pages
+ * is bigger than the size of memory there is nothing that can be
+ * done - the thrashing set could never fit into memory under any
+ * circumstance.
+ *
+ * However, the average access distance could be bigger than the
+ * inactive list, yet smaller than the size of memory.  In this case,
+ * the set could fit into memory if it weren't for the currently
+ * active pages - which may be used more, hopefully less frequently:
+ *
+ *      +-memory available to cache-+
+ *      |                           |
+ *      +-inactive------+-active----+
+ *  a b | c d e f g h i | J K L M N |
+ *      +---------------+-----------+
+ *
+ * It is prohibitively expensive to accurately track access frequency
+ * of pages.  But a reasonable approximation can be made to measure
+ * thrashing on the inactive list, after which refaulting pages can be
+ * activated optimistically to compete with the existing active pages.
+ *
+ * Approximating inactive page access frequency - Observations:
+ *
+ * 1. When a page is accessed for the first time, it is added to the
+ *    head of the inactive list, slides every existing inactive page
+ *    towards the tail by one slot, and pushes the current tail page
+ *    out of memory.
+ *
+ * 2. When a page is accessed for the second time, it is promoted to
+ *    the active list, shrinking the inactive list by one slot.  This
+ *    also slides all inactive pages that were faulted into the cache
+ *    more recently than the activated page towards the tail of the
+ *    inactive list.
+ *
+ * Thus:
+ *
+ * 1. The sum of evictions and activations between any two points in
+ *    time indicate the minimum number of inactive pages accessed in
+ *    between.
+ *
+ * 2. Moving one inactive page N page slots towards the tail of the
+ *    list requires at least N inactive page accesses.
+ *
+ * Combining these:
+ *
+ * 1. When a page is finally evicted from memory, the number of
+ *    inactive pages accessed while the page was in cache is at least
+ *    the number of page slots on the inactive list.
+ *
+ * 2. In addition, measuring the sum of evictions and activations (E)
+ *    at the time of a page's eviction, and comparing it to another
+ *    reading (R) at the time the page faults back into memory tells
+ *    the minimum number of accesses while the page was not cached.
+ *    This is called the refault distance.
+ *
+ * Because the first access of the page was the fault and the second
+ * access the refault, we combine the in-cache distance with the
+ * out-of-cache distance to get the complete minimum access distance
+ * of this page:
+ *
+ *      NR_inactive + (R - E)
+ *
+ * And knowing the minimum access distance of a page, we can easily
+ * tell if the page would be able to stay in cache assuming all page
+ * slots in the cache were available:
+ *
+ *   NR_inactive + (R - E) <= NR_inactive + NR_active
+ *
+ * which can be further simplified to
+ *
+ *   (R - E) <= NR_active
+ *
+ * Put into words, the refault distance (out-of-cache) can be seen as
+ * a deficit in inactive list space (in-cache).  If the inactive list
+ * had (R - E) more page slots, the page would not have been evicted
+ * in between accesses, but activated instead.  And on a full system,
+ * the only thing eating into inactive list space is active pages.
+ *
+ *
+ *		Activating refaulting pages
+ *
+ * All that is known about the active list is that the pages have been
+ * accessed more than once in the past.  This means that at any given
+ * time there is actually a good chance that pages on the active list
+ * are no longer in active use.
+ *
+ * So when a refault distance of (R - E) is observed and there are at
+ * least (R - E) active pages, the refaulting page is activated
+ * optimistically in the hope that (R - E) active pages are actually
+ * used less frequently than the refaulting page - or even not used at
+ * all anymore.
+ *
+ * If this is wrong and demotion kicks in, the pages which are truly
+ * used more frequently will be reactivated while the less frequently
+ * used once will be evicted from memory.
+ *
+ * But if this is right, the stale pages will be pushed out of memory
+ * and the used pages get to stay in cache.
+ *
+ *
+ *		Implementation
+ *
+ * For each zone's file LRU lists, a counter for inactive evictions
+ * and activations is maintained (zone->inactive_age).
+ *
+ * On eviction, a snapshot of this counter (along with some bits to
+ * identify the zone) is stored in the now empty page cache radix tree
+ * slot of the evicted page.  This is called a shadow entry.
+ *
+ * On cache misses for which there are shadow entries, an eligible
+ * refault distance will immediately activate the refaulting page.
+ */
+
+static void *pack_shadow(unsigned long eviction, struct zone *zone)
+{
+	eviction = (eviction << NODES_SHIFT) | zone_to_nid(zone);
+	eviction = (eviction << ZONES_SHIFT) | zone_idx(zone);
+	eviction = (eviction << RADIX_TREE_EXCEPTIONAL_SHIFT);
+
+	return (void *)(eviction | RADIX_TREE_EXCEPTIONAL_ENTRY);
+}
+
+static void unpack_shadow(void *shadow,
+			  struct zone **zone,
+			  unsigned long *distance)
+{
+	unsigned long entry = (unsigned long)shadow;
+	unsigned long eviction;
+	unsigned long refault;
+	unsigned long mask;
+	int zid, nid;
+
+	entry >>= RADIX_TREE_EXCEPTIONAL_SHIFT;
+	zid = entry & ((1UL << ZONES_SHIFT) - 1);
+	entry >>= ZONES_SHIFT;
+	nid = entry & ((1UL << NODES_SHIFT) - 1);
+	entry >>= NODES_SHIFT;
+	eviction = entry;
+
+	*zone = NODE_DATA(nid)->node_zones + zid;
+
+	refault = atomic_long_read(&(*zone)->inactive_age);
+	mask = ~0UL >> (NODES_SHIFT + ZONES_SHIFT +
+			RADIX_TREE_EXCEPTIONAL_SHIFT);
+	/*
+	 * The unsigned subtraction here gives an accurate distance
+	 * across inactive_age overflows in most cases.
+	 *
+	 * There is a special case: usually, shadow entries have a
+	 * short lifetime and are either refaulted or reclaimed along
+	 * with the inode before they get too old.  But it is not
+	 * impossible for the inactive_age to lap a shadow entry in
+	 * the field, which can then can result in a false small
+	 * refault distance, leading to a false activation should this
+	 * old entry actually refault again.  However, earlier kernels
+	 * used to deactivate unconditionally with *every* reclaim
+	 * invocation for the longest time, so the occasional
+	 * inappropriate activation leading to pressure on the active
+	 * list is not a problem.
+	 */
+	*distance = (refault - eviction) & mask;
+}
+
+/**
+ * workingset_eviction - note the eviction of a page from memory
+ * @mapping: address space the page was backing
+ * @page: the page being evicted
+ *
+ * Returns a shadow entry to be stored in @mapping->page_tree in place
+ * of the evicted @page so that a later refault can be detected.
+ */
+void *workingset_eviction(struct address_space *mapping, struct page *page)
+{
+	struct zone *zone = page_zone(page);
+	unsigned long eviction;
+
+	eviction = atomic_long_inc_return(&zone->inactive_age);
+	return pack_shadow(eviction, zone);
+}
+
+/**
+ * workingset_refault - evaluate the refault of a previously evicted page
+ * @shadow: shadow entry of the evicted page
+ *
+ * Calculates and evaluates the refault distance of the previously
+ * evicted page in the context of the zone it was allocated in.
+ *
+ * Returns %true if the page should be activated, %false otherwise.
+ */
+bool workingset_refault(void *shadow)
+{
+	unsigned long refault_distance;
+	struct zone *zone;
+
+	unpack_shadow(shadow, &zone, &refault_distance);
+	inc_zone_state(zone, WORKINGSET_REFAULT);
+
+	if (refault_distance <= zone_page_state(zone, NR_ACTIVE_FILE)) {
+		inc_zone_state(zone, WORKINGSET_ACTIVATE);
+		return true;
+	}
+	return false;
+}
+
+/**
+ * workingset_activation - note a page activation
+ * @page: page that is being activated
+ */
+void workingset_activation(struct page *page)
+{
+	atomic_long_inc(&page_zone(page)->inactive_age);
+}
+
+/*
+ * Shadow entries reflect the share of the working set that does not
+ * fit into memory, so their number depends on the access pattern of
+ * the workload.  In most cases, they will refault or get reclaimed
+ * along with the inode, but a (malicious) workload that streams
+ * through files with a total size several times that of available
+ * memory, while preventing the inodes from being reclaimed, can
+ * create excessive amounts of shadow nodes.  To keep a lid on this,
+ * track shadow nodes and reclaim them when they grow way past the
+ * point where they would still be useful.
+ */
+
+struct list_lru workingset_shadow_nodes;
+
+static unsigned long count_shadow_nodes(struct shrinker *shrinker,
+					struct shrink_control *sc)
+{
+	unsigned long shadow_nodes;
+	unsigned long max_nodes;
+	unsigned long pages;
+
+	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
+	local_irq_disable();
+	shadow_nodes = list_lru_shrink_count(&workingset_shadow_nodes, sc);
+	local_irq_enable();
+
+	pages = node_present_pages(sc->nid);
+	/*
+	 * Active cache pages are limited to 50% of memory, and shadow
+	 * entries that represent a refault distance bigger than that
+	 * do not have any effect.  Limit the number of shadow nodes
+	 * such that shadow entries do not exceed the number of active
+	 * cache pages, assuming a worst-case node population density
+	 * of 1/8th on average.
+	 *
+	 * On 64-bit with 7 radix_tree_nodes per page and 64 slots
+	 * each, this will reclaim shadow entries when they consume
+	 * ~2% of available memory:
+	 *
+	 * PAGE_SIZE / radix_tree_nodes / node_entries / PAGE_SIZE
+	 */
+	max_nodes = pages >> (1 + RADIX_TREE_MAP_SHIFT - 3);
+
+	if (shadow_nodes <= max_nodes)
+		return 0;
+
+	return shadow_nodes - max_nodes;
+}
+
+static enum lru_status shadow_lru_isolate(struct list_head *item,
+					  struct list_lru_one *lru,
+					  spinlock_t *lru_lock,
+					  void *arg)
+{
+	struct address_space *mapping;
+	struct radix_tree_node *node;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * Page cache insertions and deletions synchroneously maintain
+	 * the shadow node LRU under the mapping->tree_lock and the
+	 * lru_lock.  Because the page cache tree is emptied before
+	 * the inode can be destroyed, holding the lru_lock pins any
+	 * address_space that has radix tree nodes on the LRU.
+	 *
+	 * We can then safely transition to the mapping->tree_lock to
+	 * pin only the address_space of the particular node we want
+	 * to reclaim, take the node off-LRU, and drop the lru_lock.
+	 */
+
+	node = container_of(item, struct radix_tree_node, private_list);
+	mapping = node->private_data;
+
+	/* Coming from the list, invert the lock order */
+	if (!spin_trylock(&mapping->tree_lock)) {
+		spin_unlock(lru_lock);
+		ret = LRU_RETRY;
+		goto out;
+	}
+
+	list_lru_isolate(lru, item);
+	spin_unlock(lru_lock);
+
+	/*
+	 * The nodes should only contain one or more shadow entries,
+	 * no pages, so we expect to be able to remove them all and
+	 * delete and free the empty node afterwards.
+	 */
+	BUG_ON(!workingset_node_shadows(node));
+	BUG_ON(workingset_node_pages(node));
+
+	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
+		if (node->slots[i]) {
+			BUG_ON(!radix_tree_exceptional_entry(node->slots[i]));
+			node->slots[i] = NULL;
+			workingset_node_shadows_dec(node);
+			BUG_ON(!mapping->nrshadows);
+			mapping->nrshadows--;
+		}
+	}
+	BUG_ON(workingset_node_shadows(node));
+	inc_zone_state(page_zone(virt_to_page(node)), WORKINGSET_NODERECLAIM);
+	if (!__radix_tree_delete_node(&mapping->page_tree, node))
+		BUG();
+
+	spin_unlock(&mapping->tree_lock);
+	ret = LRU_REMOVED_RETRY;
+out:
+	local_irq_enable();
+	cond_resched();
+	local_irq_disable();
+	spin_lock(lru_lock);
+	return ret;
+}
+
+static unsigned long scan_shadow_nodes(struct shrinker *shrinker,
+				       struct shrink_control *sc)
+{
+	unsigned long ret;
+
+	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
+	local_irq_disable();
+	ret =  list_lru_shrink_walk(&workingset_shadow_nodes, sc,
+				    shadow_lru_isolate, NULL);
+	local_irq_enable();
+	return ret;
+}
+
+static struct shrinker workingset_shadow_shrinker = {
+	.count_objects = count_shadow_nodes,
+	.scan_objects = scan_shadow_nodes,
+	.seeks = DEFAULT_SEEKS,
+	.flags = SHRINKER_NUMA_AWARE,
+};
+
+/*
+ * Our list_lru->lock is IRQ-safe as it nests inside the IRQ-safe
+ * mapping->tree_lock.
+ */
+static struct lock_class_key shadow_nodes_key;
+
+static int __init workingset_init(void)
+{
+	int ret;
+
+	ret = list_lru_init_key(&workingset_shadow_nodes, &shadow_nodes_key);
+	if (ret)
+		goto err;
+	ret = register_shrinker(&workingset_shadow_shrinker);
+	if (ret)
+		goto err_list_lru;
+	return 0;
+err_list_lru:
+	list_lru_destroy(&workingset_shadow_nodes);
+err:
+	return ret;
+}
+module_init(workingset_init);
diff --git a/mm/zbud.c b/mm/zbud.c
new file mode 100644
index 0000000..d8a181f
--- /dev/null
+++ b/mm/zbud.c
@@ -0,0 +1,639 @@
+/*
+ * zbud.c
+ *
+ * Copyright (C) 2013, Seth Jennings, IBM
+ *
+ * Concepts based on zcache internal zbud allocator by Dan Magenheimer.
+ *
+ * zbud is an special purpose allocator for storing compressed pages.  Contrary
+ * to what its name may suggest, zbud is not a buddy allocator, but rather an
+ * allocator that "buddies" two compressed pages together in a single memory
+ * page.
+ *
+ * While this design limits storage density, it has simple and deterministic
+ * reclaim properties that make it preferable to a higher density approach when
+ * reclaim will be used.
+ *
+ * zbud works by storing compressed pages, or "zpages", together in pairs in a
+ * single memory page called a "zbud page".  The first buddy is "left
+ * justified" at the beginning of the zbud page, and the last buddy is "right
+ * justified" at the end of the zbud page.  The benefit is that if either
+ * buddy is freed, the freed buddy space, coalesced with whatever slack space
+ * that existed between the buddies, results in the largest possible free region
+ * within the zbud page.
+ *
+ * zbud also provides an attractive lower bound on density. The ratio of zpages
+ * to zbud pages can not be less than 1.  This ensures that zbud can never "do
+ * harm" by using more pages to store zpages than the uncompressed zpages would
+ * have used on their own.
+ *
+ * zbud pages are divided into "chunks".  The size of the chunks is fixed at
+ * compile time and determined by NCHUNKS_ORDER below.  Dividing zbud pages
+ * into chunks allows organizing unbuddied zbud pages into a manageable number
+ * of unbuddied lists according to the number of free chunks available in the
+ * zbud page.
+ *
+ * The zbud API differs from that of conventional allocators in that the
+ * allocation function, zbud_alloc(), returns an opaque handle to the user,
+ * not a dereferenceable pointer.  The user must map the handle using
+ * zbud_map() in order to get a usable pointer by which to access the
+ * allocation data and unmap the handle with zbud_unmap() when operations
+ * on the allocation data are complete.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/atomic.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/preempt.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/zbud.h>
+#include <linux/zpool.h>
+
+/*****************
+ * Structures
+*****************/
+/*
+ * NCHUNKS_ORDER determines the internal allocation granularity, effectively
+ * adjusting internal fragmentation.  It also determines the number of
+ * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
+ * allocation granularity will be in chunks of size PAGE_SIZE/64. As one chunk
+ * in allocated page is occupied by zbud header, NCHUNKS will be calculated to
+ * 63 which shows the max number of free chunks in zbud page, also there will be
+ * 63 freelists per pool.
+ */
+#define NCHUNKS_ORDER	6
+
+#define CHUNK_SHIFT	(PAGE_SHIFT - NCHUNKS_ORDER)
+#define CHUNK_SIZE	(1 << CHUNK_SHIFT)
+#define ZHDR_SIZE_ALIGNED CHUNK_SIZE
+#define NCHUNKS		((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
+
+/**
+ * struct zbud_pool - stores metadata for each zbud pool
+ * @lock:	protects all pool fields and first|last_chunk fields of any
+ *		zbud page in the pool
+ * @unbuddied:	array of lists tracking zbud pages that only contain one buddy;
+ *		the lists each zbud page is added to depends on the size of
+ *		its free region.
+ * @buddied:	list tracking the zbud pages that contain two buddies;
+ *		these zbud pages are full
+ * @lru:	list tracking the zbud pages in LRU order by most recently
+ *		added buddy.
+ * @pages_nr:	number of zbud pages in the pool.
+ * @ops:	pointer to a structure of user defined operations specified at
+ *		pool creation time.
+ *
+ * This structure is allocated at pool creation time and maintains metadata
+ * pertaining to a particular zbud pool.
+ */
+struct zbud_pool {
+	spinlock_t lock;
+	struct list_head unbuddied[NCHUNKS];
+	struct list_head buddied;
+	struct list_head lru;
+	u64 pages_nr;
+	const struct zbud_ops *ops;
+#ifdef CONFIG_ZPOOL
+	struct zpool *zpool;
+	const struct zpool_ops *zpool_ops;
+#endif
+};
+
+/*
+ * struct zbud_header - zbud page metadata occupying the first chunk of each
+ *			zbud page.
+ * @buddy:	links the zbud page into the unbuddied/buddied lists in the pool
+ * @lru:	links the zbud page into the lru list in the pool
+ * @first_chunks:	the size of the first buddy in chunks, 0 if free
+ * @last_chunks:	the size of the last buddy in chunks, 0 if free
+ */
+struct zbud_header {
+	struct list_head buddy;
+	struct list_head lru;
+	unsigned int first_chunks;
+	unsigned int last_chunks;
+	bool under_reclaim;
+};
+
+/*****************
+ * zpool
+ ****************/
+
+#ifdef CONFIG_ZPOOL
+
+static int zbud_zpool_evict(struct zbud_pool *pool, unsigned long handle)
+{
+	if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
+		return pool->zpool_ops->evict(pool->zpool, handle);
+	else
+		return -ENOENT;
+}
+
+static const struct zbud_ops zbud_zpool_ops = {
+	.evict =	zbud_zpool_evict
+};
+
+static void *zbud_zpool_create(const char *name, gfp_t gfp,
+			       const struct zpool_ops *zpool_ops,
+			       struct zpool *zpool)
+{
+	struct zbud_pool *pool;
+
+	pool = zbud_create_pool(gfp, zpool_ops ? &zbud_zpool_ops : NULL);
+	if (pool) {
+		pool->zpool = zpool;
+		pool->zpool_ops = zpool_ops;
+	}
+	return pool;
+}
+
+static void zbud_zpool_destroy(void *pool)
+{
+	zbud_destroy_pool(pool);
+}
+
+static int zbud_zpool_malloc(void *pool, size_t size, gfp_t gfp,
+			unsigned long *handle)
+{
+	return zbud_alloc(pool, size, gfp, handle);
+}
+static void zbud_zpool_free(void *pool, unsigned long handle)
+{
+	zbud_free(pool, handle);
+}
+
+static int zbud_zpool_shrink(void *pool, unsigned int pages,
+			unsigned int *reclaimed)
+{
+	unsigned int total = 0;
+	int ret = -EINVAL;
+
+	while (total < pages) {
+		ret = zbud_reclaim_page(pool, 8);
+		if (ret < 0)
+			break;
+		total++;
+	}
+
+	if (reclaimed)
+		*reclaimed = total;
+
+	return ret;
+}
+
+static void *zbud_zpool_map(void *pool, unsigned long handle,
+			enum zpool_mapmode mm)
+{
+	return zbud_map(pool, handle);
+}
+static void zbud_zpool_unmap(void *pool, unsigned long handle)
+{
+	zbud_unmap(pool, handle);
+}
+
+static u64 zbud_zpool_total_size(void *pool)
+{
+	return zbud_get_pool_size(pool) * PAGE_SIZE;
+}
+
+static struct zpool_driver zbud_zpool_driver = {
+	.type =		"zbud",
+	.owner =	THIS_MODULE,
+	.create =	zbud_zpool_create,
+	.destroy =	zbud_zpool_destroy,
+	.malloc =	zbud_zpool_malloc,
+	.free =		zbud_zpool_free,
+	.shrink =	zbud_zpool_shrink,
+	.map =		zbud_zpool_map,
+	.unmap =	zbud_zpool_unmap,
+	.total_size =	zbud_zpool_total_size,
+};
+
+MODULE_ALIAS("zpool-zbud");
+#endif /* CONFIG_ZPOOL */
+
+/*****************
+ * Helpers
+*****************/
+/* Just to make the code easier to read */
+enum buddy {
+	FIRST,
+	LAST
+};
+
+/* Converts an allocation size in bytes to size in zbud chunks */
+static int size_to_chunks(size_t size)
+{
+	return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
+}
+
+#define for_each_unbuddied_list(_iter, _begin) \
+	for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
+
+/* Initializes the zbud header of a newly allocated zbud page */
+static struct zbud_header *init_zbud_page(struct page *page)
+{
+	struct zbud_header *zhdr = page_address(page);
+	zhdr->first_chunks = 0;
+	zhdr->last_chunks = 0;
+	INIT_LIST_HEAD(&zhdr->buddy);
+	INIT_LIST_HEAD(&zhdr->lru);
+	zhdr->under_reclaim = 0;
+	return zhdr;
+}
+
+/* Resets the struct page fields and frees the page */
+static void free_zbud_page(struct zbud_header *zhdr)
+{
+	__free_page(virt_to_page(zhdr));
+}
+
+/*
+ * Encodes the handle of a particular buddy within a zbud page
+ * Pool lock should be held as this function accesses first|last_chunks
+ */
+static unsigned long encode_handle(struct zbud_header *zhdr, enum buddy bud)
+{
+	unsigned long handle;
+
+	/*
+	 * For now, the encoded handle is actually just the pointer to the data
+	 * but this might not always be the case.  A little information hiding.
+	 * Add CHUNK_SIZE to the handle if it is the first allocation to jump
+	 * over the zbud header in the first chunk.
+	 */
+	handle = (unsigned long)zhdr;
+	if (bud == FIRST)
+		/* skip over zbud header */
+		handle += ZHDR_SIZE_ALIGNED;
+	else /* bud == LAST */
+		handle += PAGE_SIZE - (zhdr->last_chunks  << CHUNK_SHIFT);
+	return handle;
+}
+
+/* Returns the zbud page where a given handle is stored */
+static struct zbud_header *handle_to_zbud_header(unsigned long handle)
+{
+	return (struct zbud_header *)(handle & PAGE_MASK);
+}
+
+/* Returns the number of free chunks in a zbud page */
+static int num_free_chunks(struct zbud_header *zhdr)
+{
+	/*
+	 * Rather than branch for different situations, just use the fact that
+	 * free buddies have a length of zero to simplify everything.
+	 */
+	return NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
+}
+
+/*****************
+ * API Functions
+*****************/
+/**
+ * zbud_create_pool() - create a new zbud pool
+ * @gfp:	gfp flags when allocating the zbud pool structure
+ * @ops:	user-defined operations for the zbud pool
+ *
+ * Return: pointer to the new zbud pool or NULL if the metadata allocation
+ * failed.
+ */
+struct zbud_pool *zbud_create_pool(gfp_t gfp, const struct zbud_ops *ops)
+{
+	struct zbud_pool *pool;
+	int i;
+
+	pool = kzalloc(sizeof(struct zbud_pool), gfp);
+	if (!pool)
+		return NULL;
+	spin_lock_init(&pool->lock);
+	for_each_unbuddied_list(i, 0)
+		INIT_LIST_HEAD(&pool->unbuddied[i]);
+	INIT_LIST_HEAD(&pool->buddied);
+	INIT_LIST_HEAD(&pool->lru);
+	pool->pages_nr = 0;
+	pool->ops = ops;
+	return pool;
+}
+
+/**
+ * zbud_destroy_pool() - destroys an existing zbud pool
+ * @pool:	the zbud pool to be destroyed
+ *
+ * The pool should be emptied before this function is called.
+ */
+void zbud_destroy_pool(struct zbud_pool *pool)
+{
+	kfree(pool);
+}
+
+/**
+ * zbud_alloc() - allocates a region of a given size
+ * @pool:	zbud pool from which to allocate
+ * @size:	size in bytes of the desired allocation
+ * @gfp:	gfp flags used if the pool needs to grow
+ * @handle:	handle of the new allocation
+ *
+ * This function will attempt to find a free region in the pool large enough to
+ * satisfy the allocation request.  A search of the unbuddied lists is
+ * performed first. If no suitable free region is found, then a new page is
+ * allocated and added to the pool to satisfy the request.
+ *
+ * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
+ * as zbud pool pages.
+ *
+ * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
+ * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
+ * a new page.
+ */
+int zbud_alloc(struct zbud_pool *pool, size_t size, gfp_t gfp,
+			unsigned long *handle)
+{
+	int chunks, i, freechunks;
+	struct zbud_header *zhdr = NULL;
+	enum buddy bud;
+	struct page *page;
+
+	if (!size || (gfp & __GFP_HIGHMEM))
+		return -EINVAL;
+	if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
+		return -ENOSPC;
+	chunks = size_to_chunks(size);
+	spin_lock(&pool->lock);
+
+	/* First, try to find an unbuddied zbud page. */
+	zhdr = NULL;
+	for_each_unbuddied_list(i, chunks) {
+		if (!list_empty(&pool->unbuddied[i])) {
+			zhdr = list_first_entry(&pool->unbuddied[i],
+					struct zbud_header, buddy);
+			list_del(&zhdr->buddy);
+			if (zhdr->first_chunks == 0)
+				bud = FIRST;
+			else
+				bud = LAST;
+			goto found;
+		}
+	}
+
+	/* Couldn't find unbuddied zbud page, create new one */
+	spin_unlock(&pool->lock);
+	page = alloc_page(gfp);
+	if (!page)
+		return -ENOMEM;
+	spin_lock(&pool->lock);
+	pool->pages_nr++;
+	zhdr = init_zbud_page(page);
+	bud = FIRST;
+
+found:
+	if (bud == FIRST)
+		zhdr->first_chunks = chunks;
+	else
+		zhdr->last_chunks = chunks;
+
+	if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0) {
+		/* Add to unbuddied list */
+		freechunks = num_free_chunks(zhdr);
+		list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+	} else {
+		/* Add to buddied list */
+		list_add(&zhdr->buddy, &pool->buddied);
+	}
+
+	/* Add/move zbud page to beginning of LRU */
+	if (!list_empty(&zhdr->lru))
+		list_del(&zhdr->lru);
+	list_add(&zhdr->lru, &pool->lru);
+
+	*handle = encode_handle(zhdr, bud);
+	spin_unlock(&pool->lock);
+
+	return 0;
+}
+
+/**
+ * zbud_free() - frees the allocation associated with the given handle
+ * @pool:	pool in which the allocation resided
+ * @handle:	handle associated with the allocation returned by zbud_alloc()
+ *
+ * In the case that the zbud page in which the allocation resides is under
+ * reclaim, as indicated by the PG_reclaim flag being set, this function
+ * only sets the first|last_chunks to 0.  The page is actually freed
+ * once both buddies are evicted (see zbud_reclaim_page() below).
+ */
+void zbud_free(struct zbud_pool *pool, unsigned long handle)
+{
+	struct zbud_header *zhdr;
+	int freechunks;
+
+	spin_lock(&pool->lock);
+	zhdr = handle_to_zbud_header(handle);
+
+	/* If first buddy, handle will be page aligned */
+	if ((handle - ZHDR_SIZE_ALIGNED) & ~PAGE_MASK)
+		zhdr->last_chunks = 0;
+	else
+		zhdr->first_chunks = 0;
+
+	if (zhdr->under_reclaim) {
+		/* zbud page is under reclaim, reclaim will free */
+		spin_unlock(&pool->lock);
+		return;
+	}
+
+	/* Remove from existing buddy list */
+	list_del(&zhdr->buddy);
+
+	if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
+		/* zbud page is empty, free */
+		list_del(&zhdr->lru);
+		free_zbud_page(zhdr);
+		pool->pages_nr--;
+	} else {
+		/* Add to unbuddied list */
+		freechunks = num_free_chunks(zhdr);
+		list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+	}
+
+	spin_unlock(&pool->lock);
+}
+
+#define list_tail_entry(ptr, type, member) \
+	list_entry((ptr)->prev, type, member)
+
+/**
+ * zbud_reclaim_page() - evicts allocations from a pool page and frees it
+ * @pool:	pool from which a page will attempt to be evicted
+ * @retires:	number of pages on the LRU list for which eviction will
+ *		be attempted before failing
+ *
+ * zbud reclaim is different from normal system reclaim in that the reclaim is
+ * done from the bottom, up.  This is because only the bottom layer, zbud, has
+ * information on how the allocations are organized within each zbud page. This
+ * has the potential to create interesting locking situations between zbud and
+ * the user, however.
+ *
+ * To avoid these, this is how zbud_reclaim_page() should be called:
+
+ * The user detects a page should be reclaimed and calls zbud_reclaim_page().
+ * zbud_reclaim_page() will remove a zbud page from the pool LRU list and call
+ * the user-defined eviction handler with the pool and handle as arguments.
+ *
+ * If the handle can not be evicted, the eviction handler should return
+ * non-zero. zbud_reclaim_page() will add the zbud page back to the
+ * appropriate list and try the next zbud page on the LRU up to
+ * a user defined number of retries.
+ *
+ * If the handle is successfully evicted, the eviction handler should
+ * return 0 _and_ should have called zbud_free() on the handle. zbud_free()
+ * contains logic to delay freeing the page if the page is under reclaim,
+ * as indicated by the setting of the PG_reclaim flag on the underlying page.
+ *
+ * If all buddies in the zbud page are successfully evicted, then the
+ * zbud page can be freed.
+ *
+ * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
+ * no pages to evict or an eviction handler is not registered, -EAGAIN if
+ * the retry limit was hit.
+ */
+int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries)
+{
+	int i, ret, freechunks;
+	struct zbud_header *zhdr;
+	unsigned long first_handle = 0, last_handle = 0;
+
+	spin_lock(&pool->lock);
+	if (!pool->ops || !pool->ops->evict || list_empty(&pool->lru) ||
+			retries == 0) {
+		spin_unlock(&pool->lock);
+		return -EINVAL;
+	}
+	for (i = 0; i < retries; i++) {
+		zhdr = list_tail_entry(&pool->lru, struct zbud_header, lru);
+		list_del(&zhdr->lru);
+		list_del(&zhdr->buddy);
+		/* Protect zbud page against free */
+		zhdr->under_reclaim = true;
+		/*
+		 * We need encode the handles before unlocking, since we can
+		 * race with free that will set (first|last)_chunks to 0
+		 */
+		first_handle = 0;
+		last_handle = 0;
+		if (zhdr->first_chunks)
+			first_handle = encode_handle(zhdr, FIRST);
+		if (zhdr->last_chunks)
+			last_handle = encode_handle(zhdr, LAST);
+		spin_unlock(&pool->lock);
+
+		/* Issue the eviction callback(s) */
+		if (first_handle) {
+			ret = pool->ops->evict(pool, first_handle);
+			if (ret)
+				goto next;
+		}
+		if (last_handle) {
+			ret = pool->ops->evict(pool, last_handle);
+			if (ret)
+				goto next;
+		}
+next:
+		spin_lock(&pool->lock);
+		zhdr->under_reclaim = false;
+		if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
+			/*
+			 * Both buddies are now free, free the zbud page and
+			 * return success.
+			 */
+			free_zbud_page(zhdr);
+			pool->pages_nr--;
+			spin_unlock(&pool->lock);
+			return 0;
+		} else if (zhdr->first_chunks == 0 ||
+				zhdr->last_chunks == 0) {
+			/* add to unbuddied list */
+			freechunks = num_free_chunks(zhdr);
+			list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+		} else {
+			/* add to buddied list */
+			list_add(&zhdr->buddy, &pool->buddied);
+		}
+
+		/* add to beginning of LRU */
+		list_add(&zhdr->lru, &pool->lru);
+	}
+	spin_unlock(&pool->lock);
+	return -EAGAIN;
+}
+
+/**
+ * zbud_map() - maps the allocation associated with the given handle
+ * @pool:	pool in which the allocation resides
+ * @handle:	handle associated with the allocation to be mapped
+ *
+ * While trivial for zbud, the mapping functions for others allocators
+ * implementing this allocation API could have more complex information encoded
+ * in the handle and could create temporary mappings to make the data
+ * accessible to the user.
+ *
+ * Returns: a pointer to the mapped allocation
+ */
+void *zbud_map(struct zbud_pool *pool, unsigned long handle)
+{
+	return (void *)(handle);
+}
+
+/**
+ * zbud_unmap() - maps the allocation associated with the given handle
+ * @pool:	pool in which the allocation resides
+ * @handle:	handle associated with the allocation to be unmapped
+ */
+void zbud_unmap(struct zbud_pool *pool, unsigned long handle)
+{
+}
+
+/**
+ * zbud_get_pool_size() - gets the zbud pool size in pages
+ * @pool:	pool whose size is being queried
+ *
+ * Returns: size in pages of the given pool.  The pool lock need not be
+ * taken to access pages_nr.
+ */
+u64 zbud_get_pool_size(struct zbud_pool *pool)
+{
+	return pool->pages_nr;
+}
+
+static int __init init_zbud(void)
+{
+	/* Make sure the zbud header will fit in one chunk */
+	BUILD_BUG_ON(sizeof(struct zbud_header) > ZHDR_SIZE_ALIGNED);
+	pr_info("loaded\n");
+
+#ifdef CONFIG_ZPOOL
+	zpool_register_driver(&zbud_zpool_driver);
+#endif
+
+	return 0;
+}
+
+static void __exit exit_zbud(void)
+{
+#ifdef CONFIG_ZPOOL
+	zpool_unregister_driver(&zbud_zpool_driver);
+#endif
+
+	pr_info("unloaded\n");
+}
+
+module_init(init_zbud);
+module_exit(exit_zbud);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
+MODULE_DESCRIPTION("Buddy Allocator for Compressed Pages");
diff --git a/mm/zpool.c b/mm/zpool.c
new file mode 100644
index 0000000..fd3ff71
--- /dev/null
+++ b/mm/zpool.c
@@ -0,0 +1,360 @@
+/*
+ * zpool memory storage api
+ *
+ * Copyright (C) 2014 Dan Streetman
+ *
+ * This is a common frontend for memory storage pool implementations.
+ * Typically, this is used to store compressed memory.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/zpool.h>
+
+struct zpool {
+	struct zpool_driver *driver;
+	void *pool;
+	const struct zpool_ops *ops;
+
+	struct list_head list;
+};
+
+static LIST_HEAD(drivers_head);
+static DEFINE_SPINLOCK(drivers_lock);
+
+static LIST_HEAD(pools_head);
+static DEFINE_SPINLOCK(pools_lock);
+
+/**
+ * zpool_register_driver() - register a zpool implementation.
+ * @driver:	driver to register
+ */
+void zpool_register_driver(struct zpool_driver *driver)
+{
+	spin_lock(&drivers_lock);
+	atomic_set(&driver->refcount, 0);
+	list_add(&driver->list, &drivers_head);
+	spin_unlock(&drivers_lock);
+}
+EXPORT_SYMBOL(zpool_register_driver);
+
+/**
+ * zpool_unregister_driver() - unregister a zpool implementation.
+ * @driver:	driver to unregister.
+ *
+ * Module usage counting is used to prevent using a driver
+ * while/after unloading, so if this is called from module
+ * exit function, this should never fail; if called from
+ * other than the module exit function, and this returns
+ * failure, the driver is in use and must remain available.
+ */
+int zpool_unregister_driver(struct zpool_driver *driver)
+{
+	int ret = 0, refcount;
+
+	spin_lock(&drivers_lock);
+	refcount = atomic_read(&driver->refcount);
+	WARN_ON(refcount < 0);
+	if (refcount > 0)
+		ret = -EBUSY;
+	else
+		list_del(&driver->list);
+	spin_unlock(&drivers_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(zpool_unregister_driver);
+
+/* this assumes @type is null-terminated. */
+static struct zpool_driver *zpool_get_driver(const char *type)
+{
+	struct zpool_driver *driver;
+
+	spin_lock(&drivers_lock);
+	list_for_each_entry(driver, &drivers_head, list) {
+		if (!strcmp(driver->type, type)) {
+			bool got = try_module_get(driver->owner);
+
+			if (got)
+				atomic_inc(&driver->refcount);
+			spin_unlock(&drivers_lock);
+			return got ? driver : NULL;
+		}
+	}
+
+	spin_unlock(&drivers_lock);
+	return NULL;
+}
+
+static void zpool_put_driver(struct zpool_driver *driver)
+{
+	atomic_dec(&driver->refcount);
+	module_put(driver->owner);
+}
+
+/**
+ * zpool_has_pool() - Check if the pool driver is available
+ * @type	The type of the zpool to check (e.g. zbud, zsmalloc)
+ *
+ * This checks if the @type pool driver is available.  This will try to load
+ * the requested module, if needed, but there is no guarantee the module will
+ * still be loaded and available immediately after calling.  If this returns
+ * true, the caller should assume the pool is available, but must be prepared
+ * to handle the @zpool_create_pool() returning failure.  However if this
+ * returns false, the caller should assume the requested pool type is not
+ * available; either the requested pool type module does not exist, or could
+ * not be loaded, and calling @zpool_create_pool() with the pool type will
+ * fail.
+ *
+ * The @type string must be null-terminated.
+ *
+ * Returns: true if @type pool is available, false if not
+ */
+bool zpool_has_pool(char *type)
+{
+	struct zpool_driver *driver = zpool_get_driver(type);
+
+	if (!driver) {
+		request_module("zpool-%s", type);
+		driver = zpool_get_driver(type);
+	}
+
+	if (!driver)
+		return false;
+
+	zpool_put_driver(driver);
+	return true;
+}
+EXPORT_SYMBOL(zpool_has_pool);
+
+/**
+ * zpool_create_pool() - Create a new zpool
+ * @type	The type of the zpool to create (e.g. zbud, zsmalloc)
+ * @name	The name of the zpool (e.g. zram0, zswap)
+ * @gfp		The GFP flags to use when allocating the pool.
+ * @ops		The optional ops callback.
+ *
+ * This creates a new zpool of the specified type.  The gfp flags will be
+ * used when allocating memory, if the implementation supports it.  If the
+ * ops param is NULL, then the created zpool will not be shrinkable.
+ *
+ * Implementations must guarantee this to be thread-safe.
+ *
+ * The @type and @name strings must be null-terminated.
+ *
+ * Returns: New zpool on success, NULL on failure.
+ */
+struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
+		const struct zpool_ops *ops)
+{
+	struct zpool_driver *driver;
+	struct zpool *zpool;
+
+	pr_debug("creating pool type %s\n", type);
+
+	driver = zpool_get_driver(type);
+
+	if (!driver) {
+		request_module("zpool-%s", type);
+		driver = zpool_get_driver(type);
+	}
+
+	if (!driver) {
+		pr_err("no driver for type %s\n", type);
+		return NULL;
+	}
+
+	zpool = kmalloc(sizeof(*zpool), gfp);
+	if (!zpool) {
+		pr_err("couldn't create zpool - out of memory\n");
+		zpool_put_driver(driver);
+		return NULL;
+	}
+
+	zpool->driver = driver;
+	zpool->pool = driver->create(name, gfp, ops, zpool);
+	zpool->ops = ops;
+
+	if (!zpool->pool) {
+		pr_err("couldn't create %s pool\n", type);
+		zpool_put_driver(driver);
+		kfree(zpool);
+		return NULL;
+	}
+
+	pr_debug("created pool type %s\n", type);
+
+	spin_lock(&pools_lock);
+	list_add(&zpool->list, &pools_head);
+	spin_unlock(&pools_lock);
+
+	return zpool;
+}
+
+/**
+ * zpool_destroy_pool() - Destroy a zpool
+ * @pool	The zpool to destroy.
+ *
+ * Implementations must guarantee this to be thread-safe,
+ * however only when destroying different pools.  The same
+ * pool should only be destroyed once, and should not be used
+ * after it is destroyed.
+ *
+ * This destroys an existing zpool.  The zpool should not be in use.
+ */
+void zpool_destroy_pool(struct zpool *zpool)
+{
+	pr_debug("destroying pool type %s\n", zpool->driver->type);
+
+	spin_lock(&pools_lock);
+	list_del(&zpool->list);
+	spin_unlock(&pools_lock);
+	zpool->driver->destroy(zpool->pool);
+	zpool_put_driver(zpool->driver);
+	kfree(zpool);
+}
+
+/**
+ * zpool_get_type() - Get the type of the zpool
+ * @pool	The zpool to check
+ *
+ * This returns the type of the pool.
+ *
+ * Implementations must guarantee this to be thread-safe.
+ *
+ * Returns: The type of zpool.
+ */
+const char *zpool_get_type(struct zpool *zpool)
+{
+	return zpool->driver->type;
+}
+
+/**
+ * zpool_malloc() - Allocate memory
+ * @pool	The zpool to allocate from.
+ * @size	The amount of memory to allocate.
+ * @gfp		The GFP flags to use when allocating memory.
+ * @handle	Pointer to the handle to set
+ *
+ * This allocates the requested amount of memory from the pool.
+ * The gfp flags will be used when allocating memory, if the
+ * implementation supports it.  The provided @handle will be
+ * set to the allocated object handle.
+ *
+ * Implementations must guarantee this to be thread-safe.
+ *
+ * Returns: 0 on success, negative value on error.
+ */
+int zpool_malloc(struct zpool *zpool, size_t size, gfp_t gfp,
+			unsigned long *handle)
+{
+	return zpool->driver->malloc(zpool->pool, size, gfp, handle);
+}
+
+/**
+ * zpool_free() - Free previously allocated memory
+ * @pool	The zpool that allocated the memory.
+ * @handle	The handle to the memory to free.
+ *
+ * This frees previously allocated memory.  This does not guarantee
+ * that the pool will actually free memory, only that the memory
+ * in the pool will become available for use by the pool.
+ *
+ * Implementations must guarantee this to be thread-safe,
+ * however only when freeing different handles.  The same
+ * handle should only be freed once, and should not be used
+ * after freeing.
+ */
+void zpool_free(struct zpool *zpool, unsigned long handle)
+{
+	zpool->driver->free(zpool->pool, handle);
+}
+
+/**
+ * zpool_shrink() - Shrink the pool size
+ * @pool	The zpool to shrink.
+ * @pages	The number of pages to shrink the pool.
+ * @reclaimed	The number of pages successfully evicted.
+ *
+ * This attempts to shrink the actual memory size of the pool
+ * by evicting currently used handle(s).  If the pool was
+ * created with no zpool_ops, or the evict call fails for any
+ * of the handles, this will fail.  If non-NULL, the @reclaimed
+ * parameter will be set to the number of pages reclaimed,
+ * which may be more than the number of pages requested.
+ *
+ * Implementations must guarantee this to be thread-safe.
+ *
+ * Returns: 0 on success, negative value on error/failure.
+ */
+int zpool_shrink(struct zpool *zpool, unsigned int pages,
+			unsigned int *reclaimed)
+{
+	return zpool->driver->shrink(zpool->pool, pages, reclaimed);
+}
+
+/**
+ * zpool_map_handle() - Map a previously allocated handle into memory
+ * @pool	The zpool that the handle was allocated from
+ * @handle	The handle to map
+ * @mm		How the memory should be mapped
+ *
+ * This maps a previously allocated handle into memory.  The @mm
+ * param indicates to the implementation how the memory will be
+ * used, i.e. read-only, write-only, read-write.  If the
+ * implementation does not support it, the memory will be treated
+ * as read-write.
+ *
+ * This may hold locks, disable interrupts, and/or preemption,
+ * and the zpool_unmap_handle() must be called to undo those
+ * actions.  The code that uses the mapped handle should complete
+ * its operatons on the mapped handle memory quickly and unmap
+ * as soon as possible.  As the implementation may use per-cpu
+ * data, multiple handles should not be mapped concurrently on
+ * any cpu.
+ *
+ * Returns: A pointer to the handle's mapped memory area.
+ */
+void *zpool_map_handle(struct zpool *zpool, unsigned long handle,
+			enum zpool_mapmode mapmode)
+{
+	return zpool->driver->map(zpool->pool, handle, mapmode);
+}
+
+/**
+ * zpool_unmap_handle() - Unmap a previously mapped handle
+ * @pool	The zpool that the handle was allocated from
+ * @handle	The handle to unmap
+ *
+ * This unmaps a previously mapped handle.  Any locks or other
+ * actions that the implementation took in zpool_map_handle()
+ * will be undone here.  The memory area returned from
+ * zpool_map_handle() should no longer be used after this.
+ */
+void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
+{
+	zpool->driver->unmap(zpool->pool, handle);
+}
+
+/**
+ * zpool_get_total_size() - The total size of the pool
+ * @pool	The zpool to check
+ *
+ * This returns the total size in bytes of the pool.
+ *
+ * Returns: Total size of the zpool in bytes.
+ */
+u64 zpool_get_total_size(struct zpool *zpool)
+{
+	return zpool->driver->total_size(zpool->pool);
+}
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
+MODULE_DESCRIPTION("Common API for compressed memory storage");
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
new file mode 100644
index 0000000..c1ea194
--- /dev/null
+++ b/mm/zsmalloc.c
@@ -0,0 +1,2053 @@
+/*
+ * zsmalloc memory allocator
+ *
+ * Copyright (C) 2011  Nitin Gupta
+ * Copyright (C) 2012, 2013 Minchan Kim
+ *
+ * This code is released using a dual license strategy: BSD/GPL
+ * You can choose the license that better fits your requirements.
+ *
+ * Released under the terms of 3-clause BSD License
+ * Released under the terms of GNU General Public License Version 2.0
+ */
+
+/*
+ * Following is how we use various fields and flags of underlying
+ * struct page(s) to form a zspage.
+ *
+ * Usage of struct page fields:
+ *	page->private: points to the first component (0-order) page
+ *	page->index (union with page->freelist): offset of the first object
+ *		starting in this page. For the first page, this is
+ *		always 0, so we use this field (aka freelist) to point
+ *		to the first free object in zspage.
+ *	page->lru: links together all component pages (except the first page)
+ *		of a zspage
+ *
+ *	For _first_ page only:
+ *
+ *	page->private: refers to the component page after the first page
+ *		If the page is first_page for huge object, it stores handle.
+ *		Look at size_class->huge.
+ *	page->freelist: points to the first free object in zspage.
+ *		Free objects are linked together using in-place
+ *		metadata.
+ *	page->objects: maximum number of objects we can store in this
+ *		zspage (class->zspage_order * PAGE_SIZE / class->size)
+ *	page->lru: links together first pages of various zspages.
+ *		Basically forming list of zspages in a fullness group.
+ *	page->mapping: class index and fullness group of the zspage
+ *	page->inuse: the number of objects that are used in this zspage
+ *
+ * Usage of struct page flags:
+ *	PG_private: identifies the first component page
+ *	PG_private2: identifies the last component page
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/highmem.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <asm/tlbflush.h>
+#include <asm/pgtable.h>
+#include <linux/cpumask.h>
+#include <linux/cpu.h>
+#include <linux/vmalloc.h>
+#include <linux/preempt.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/debugfs.h>
+#include <linux/zsmalloc.h>
+#include <linux/zpool.h>
+
+/*
+ * This must be power of 2 and greater than of equal to sizeof(link_free).
+ * These two conditions ensure that any 'struct link_free' itself doesn't
+ * span more than 1 page which avoids complex case of mapping 2 pages simply
+ * to restore link_free pointer values.
+ */
+#define ZS_ALIGN		8
+
+/*
+ * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
+ * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
+ */
+#define ZS_MAX_ZSPAGE_ORDER 2
+#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
+
+#define ZS_HANDLE_SIZE (sizeof(unsigned long))
+
+/*
+ * Object location (<PFN>, <obj_idx>) is encoded as
+ * as single (unsigned long) handle value.
+ *
+ * Note that object index <obj_idx> is relative to system
+ * page <PFN> it is stored in, so for each sub-page belonging
+ * to a zspage, obj_idx starts with 0.
+ *
+ * This is made more complicated by various memory models and PAE.
+ */
+
+#ifndef MAX_PHYSMEM_BITS
+#ifdef CONFIG_HIGHMEM64G
+#define MAX_PHYSMEM_BITS 36
+#else /* !CONFIG_HIGHMEM64G */
+/*
+ * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
+ * be PAGE_SHIFT
+ */
+#define MAX_PHYSMEM_BITS BITS_PER_LONG
+#endif
+#endif
+#define _PFN_BITS		(MAX_PHYSMEM_BITS - PAGE_SHIFT)
+
+/*
+ * Memory for allocating for handle keeps object position by
+ * encoding <page, obj_idx> and the encoded value has a room
+ * in least bit(ie, look at obj_to_location).
+ * We use the bit to synchronize between object access by
+ * user and migration.
+ */
+#define HANDLE_PIN_BIT	0
+
+/*
+ * Head in allocated object should have OBJ_ALLOCATED_TAG
+ * to identify the object was allocated or not.
+ * It's okay to add the status bit in the least bit because
+ * header keeps handle which is 4byte-aligned address so we
+ * have room for two bit at least.
+ */
+#define OBJ_ALLOCATED_TAG 1
+#define OBJ_TAG_BITS 1
+#define OBJ_INDEX_BITS	(BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
+#define OBJ_INDEX_MASK	((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
+
+#define MAX(a, b) ((a) >= (b) ? (a) : (b))
+/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
+#define ZS_MIN_ALLOC_SIZE \
+	MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
+/* each chunk includes extra space to keep handle */
+#define ZS_MAX_ALLOC_SIZE	PAGE_SIZE
+
+/*
+ * On systems with 4K page size, this gives 255 size classes! There is a
+ * trader-off here:
+ *  - Large number of size classes is potentially wasteful as free page are
+ *    spread across these classes
+ *  - Small number of size classes causes large internal fragmentation
+ *  - Probably its better to use specific size classes (empirically
+ *    determined). NOTE: all those class sizes must be set as multiple of
+ *    ZS_ALIGN to make sure link_free itself never has to span 2 pages.
+ *
+ *  ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
+ *  (reason above)
+ */
+#define ZS_SIZE_CLASS_DELTA	(PAGE_SIZE >> 8)
+
+/*
+ * We do not maintain any list for completely empty or full pages
+ */
+enum fullness_group {
+	ZS_ALMOST_FULL,
+	ZS_ALMOST_EMPTY,
+	_ZS_NR_FULLNESS_GROUPS,
+
+	ZS_EMPTY,
+	ZS_FULL
+};
+
+enum zs_stat_type {
+	OBJ_ALLOCATED,
+	OBJ_USED,
+	CLASS_ALMOST_FULL,
+	CLASS_ALMOST_EMPTY,
+};
+
+#ifdef CONFIG_ZSMALLOC_STAT
+#define NR_ZS_STAT_TYPE	(CLASS_ALMOST_EMPTY + 1)
+#else
+#define NR_ZS_STAT_TYPE	(OBJ_USED + 1)
+#endif
+
+struct zs_size_stat {
+	unsigned long objs[NR_ZS_STAT_TYPE];
+};
+
+#ifdef CONFIG_ZSMALLOC_STAT
+static struct dentry *zs_stat_root;
+#endif
+
+/*
+ * number of size_classes
+ */
+static int zs_size_classes;
+
+/*
+ * We assign a page to ZS_ALMOST_EMPTY fullness group when:
+ *	n <= N / f, where
+ * n = number of allocated objects
+ * N = total number of objects zspage can store
+ * f = fullness_threshold_frac
+ *
+ * Similarly, we assign zspage to:
+ *	ZS_ALMOST_FULL	when n > N / f
+ *	ZS_EMPTY	when n == 0
+ *	ZS_FULL		when n == N
+ *
+ * (see: fix_fullness_group())
+ */
+static const int fullness_threshold_frac = 4;
+
+struct size_class {
+	spinlock_t lock;
+	struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
+	/*
+	 * Size of objects stored in this class. Must be multiple
+	 * of ZS_ALIGN.
+	 */
+	int size;
+	unsigned int index;
+
+	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
+	int pages_per_zspage;
+	struct zs_size_stat stats;
+
+	/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
+	bool huge;
+};
+
+/*
+ * Placed within free objects to form a singly linked list.
+ * For every zspage, first_page->freelist gives head of this list.
+ *
+ * This must be power of 2 and less than or equal to ZS_ALIGN
+ */
+struct link_free {
+	union {
+		/*
+		 * Position of next free chunk (encodes <PFN, obj_idx>)
+		 * It's valid for non-allocated object
+		 */
+		void *next;
+		/*
+		 * Handle of allocated object.
+		 */
+		unsigned long handle;
+	};
+};
+
+struct zs_pool {
+	const char *name;
+
+	struct size_class **size_class;
+	struct kmem_cache *handle_cachep;
+
+	gfp_t flags;	/* allocation flags used when growing pool */
+	atomic_long_t pages_allocated;
+
+	struct zs_pool_stats stats;
+
+	/* Compact classes */
+	struct shrinker shrinker;
+	/*
+	 * To signify that register_shrinker() was successful
+	 * and unregister_shrinker() will not Oops.
+	 */
+	bool shrinker_enabled;
+#ifdef CONFIG_ZSMALLOC_STAT
+	struct dentry *stat_dentry;
+#endif
+};
+
+/*
+ * A zspage's class index and fullness group
+ * are encoded in its (first)page->mapping
+ */
+#define CLASS_IDX_BITS	28
+#define FULLNESS_BITS	4
+#define CLASS_IDX_MASK	((1 << CLASS_IDX_BITS) - 1)
+#define FULLNESS_MASK	((1 << FULLNESS_BITS) - 1)
+
+struct mapping_area {
+#ifdef CONFIG_PGTABLE_MAPPING
+	struct vm_struct *vm; /* vm area for mapping object that span pages */
+#else
+	char *vm_buf; /* copy buffer for objects that span pages */
+#endif
+	char *vm_addr; /* address of kmap_atomic()'ed pages */
+	enum zs_mapmode vm_mm; /* mapping mode */
+	bool huge;
+};
+
+static int create_handle_cache(struct zs_pool *pool)
+{
+	pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
+					0, 0, NULL);
+	return pool->handle_cachep ? 0 : 1;
+}
+
+static void destroy_handle_cache(struct zs_pool *pool)
+{
+	kmem_cache_destroy(pool->handle_cachep);
+}
+
+static unsigned long alloc_handle(struct zs_pool *pool)
+{
+	return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
+		pool->flags & ~__GFP_HIGHMEM);
+}
+
+static void free_handle(struct zs_pool *pool, unsigned long handle)
+{
+	kmem_cache_free(pool->handle_cachep, (void *)handle);
+}
+
+static void record_obj(unsigned long handle, unsigned long obj)
+{
+	/*
+	 * lsb of @obj represents handle lock while other bits
+	 * represent object value the handle is pointing so
+	 * updating shouldn't do store tearing.
+	 */
+	WRITE_ONCE(*(unsigned long *)handle, obj);
+}
+
+/* zpool driver */
+
+#ifdef CONFIG_ZPOOL
+
+static void *zs_zpool_create(const char *name, gfp_t gfp,
+			     const struct zpool_ops *zpool_ops,
+			     struct zpool *zpool)
+{
+	return zs_create_pool(name, gfp);
+}
+
+static void zs_zpool_destroy(void *pool)
+{
+	zs_destroy_pool(pool);
+}
+
+static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
+			unsigned long *handle)
+{
+	*handle = zs_malloc(pool, size);
+	return *handle ? 0 : -1;
+}
+static void zs_zpool_free(void *pool, unsigned long handle)
+{
+	zs_free(pool, handle);
+}
+
+static int zs_zpool_shrink(void *pool, unsigned int pages,
+			unsigned int *reclaimed)
+{
+	return -EINVAL;
+}
+
+static void *zs_zpool_map(void *pool, unsigned long handle,
+			enum zpool_mapmode mm)
+{
+	enum zs_mapmode zs_mm;
+
+	switch (mm) {
+	case ZPOOL_MM_RO:
+		zs_mm = ZS_MM_RO;
+		break;
+	case ZPOOL_MM_WO:
+		zs_mm = ZS_MM_WO;
+		break;
+	case ZPOOL_MM_RW: /* fallthru */
+	default:
+		zs_mm = ZS_MM_RW;
+		break;
+	}
+
+	return zs_map_object(pool, handle, zs_mm);
+}
+static void zs_zpool_unmap(void *pool, unsigned long handle)
+{
+	zs_unmap_object(pool, handle);
+}
+
+static u64 zs_zpool_total_size(void *pool)
+{
+	return zs_get_total_pages(pool) << PAGE_SHIFT;
+}
+
+static struct zpool_driver zs_zpool_driver = {
+	.type =		"zsmalloc",
+	.owner =	THIS_MODULE,
+	.create =	zs_zpool_create,
+	.destroy =	zs_zpool_destroy,
+	.malloc =	zs_zpool_malloc,
+	.free =		zs_zpool_free,
+	.shrink =	zs_zpool_shrink,
+	.map =		zs_zpool_map,
+	.unmap =	zs_zpool_unmap,
+	.total_size =	zs_zpool_total_size,
+};
+
+MODULE_ALIAS("zpool-zsmalloc");
+#endif /* CONFIG_ZPOOL */
+
+static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
+{
+	return pages_per_zspage * PAGE_SIZE / size;
+}
+
+/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
+static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
+
+static int is_first_page(struct page *page)
+{
+	return PagePrivate(page);
+}
+
+static int is_last_page(struct page *page)
+{
+	return PagePrivate2(page);
+}
+
+static void get_zspage_mapping(struct page *page, unsigned int *class_idx,
+				enum fullness_group *fullness)
+{
+	unsigned long m;
+	BUG_ON(!is_first_page(page));
+
+	m = (unsigned long)page->mapping;
+	*fullness = m & FULLNESS_MASK;
+	*class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
+}
+
+static void set_zspage_mapping(struct page *page, unsigned int class_idx,
+				enum fullness_group fullness)
+{
+	unsigned long m;
+	BUG_ON(!is_first_page(page));
+
+	m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
+			(fullness & FULLNESS_MASK);
+	page->mapping = (struct address_space *)m;
+}
+
+/*
+ * zsmalloc divides the pool into various size classes where each
+ * class maintains a list of zspages where each zspage is divided
+ * into equal sized chunks. Each allocation falls into one of these
+ * classes depending on its size. This function returns index of the
+ * size class which has chunk size big enough to hold the give size.
+ */
+static int get_size_class_index(int size)
+{
+	int idx = 0;
+
+	if (likely(size > ZS_MIN_ALLOC_SIZE))
+		idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
+				ZS_SIZE_CLASS_DELTA);
+
+	return min(zs_size_classes - 1, idx);
+}
+
+static inline void zs_stat_inc(struct size_class *class,
+				enum zs_stat_type type, unsigned long cnt)
+{
+	if (type < NR_ZS_STAT_TYPE)
+		class->stats.objs[type] += cnt;
+}
+
+static inline void zs_stat_dec(struct size_class *class,
+				enum zs_stat_type type, unsigned long cnt)
+{
+	if (type < NR_ZS_STAT_TYPE)
+		class->stats.objs[type] -= cnt;
+}
+
+static inline unsigned long zs_stat_get(struct size_class *class,
+				enum zs_stat_type type)
+{
+	if (type < NR_ZS_STAT_TYPE)
+		return class->stats.objs[type];
+	return 0;
+}
+
+#ifdef CONFIG_ZSMALLOC_STAT
+
+static int __init zs_stat_init(void)
+{
+	if (!debugfs_initialized())
+		return -ENODEV;
+
+	zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
+	if (!zs_stat_root)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void __exit zs_stat_exit(void)
+{
+	debugfs_remove_recursive(zs_stat_root);
+}
+
+static int zs_stats_size_show(struct seq_file *s, void *v)
+{
+	int i;
+	struct zs_pool *pool = s->private;
+	struct size_class *class;
+	int objs_per_zspage;
+	unsigned long class_almost_full, class_almost_empty;
+	unsigned long obj_allocated, obj_used, pages_used;
+	unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
+	unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
+
+	seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s\n",
+			"class", "size", "almost_full", "almost_empty",
+			"obj_allocated", "obj_used", "pages_used",
+			"pages_per_zspage");
+
+	for (i = 0; i < zs_size_classes; i++) {
+		class = pool->size_class[i];
+
+		if (class->index != i)
+			continue;
+
+		spin_lock(&class->lock);
+		class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL);
+		class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY);
+		obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
+		obj_used = zs_stat_get(class, OBJ_USED);
+		spin_unlock(&class->lock);
+
+		objs_per_zspage = get_maxobj_per_zspage(class->size,
+				class->pages_per_zspage);
+		pages_used = obj_allocated / objs_per_zspage *
+				class->pages_per_zspage;
+
+		seq_printf(s, " %5u %5u %11lu %12lu %13lu %10lu %10lu %16d\n",
+			i, class->size, class_almost_full, class_almost_empty,
+			obj_allocated, obj_used, pages_used,
+			class->pages_per_zspage);
+
+		total_class_almost_full += class_almost_full;
+		total_class_almost_empty += class_almost_empty;
+		total_objs += obj_allocated;
+		total_used_objs += obj_used;
+		total_pages += pages_used;
+	}
+
+	seq_puts(s, "\n");
+	seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu\n",
+			"Total", "", total_class_almost_full,
+			total_class_almost_empty, total_objs,
+			total_used_objs, total_pages);
+
+	return 0;
+}
+
+static int zs_stats_size_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, zs_stats_size_show, inode->i_private);
+}
+
+static const struct file_operations zs_stat_size_ops = {
+	.open           = zs_stats_size_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = single_release,
+};
+
+static int zs_pool_stat_create(const char *name, struct zs_pool *pool)
+{
+	struct dentry *entry;
+
+	if (!zs_stat_root)
+		return -ENODEV;
+
+	entry = debugfs_create_dir(name, zs_stat_root);
+	if (!entry) {
+		pr_warn("debugfs dir <%s> creation failed\n", name);
+		return -ENOMEM;
+	}
+	pool->stat_dentry = entry;
+
+	entry = debugfs_create_file("classes", S_IFREG | S_IRUGO,
+			pool->stat_dentry, pool, &zs_stat_size_ops);
+	if (!entry) {
+		pr_warn("%s: debugfs file entry <%s> creation failed\n",
+				name, "classes");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+	debugfs_remove_recursive(pool->stat_dentry);
+}
+
+#else /* CONFIG_ZSMALLOC_STAT */
+static int __init zs_stat_init(void)
+{
+	return 0;
+}
+
+static void __exit zs_stat_exit(void)
+{
+}
+
+static inline int zs_pool_stat_create(const char *name, struct zs_pool *pool)
+{
+	return 0;
+}
+
+static inline void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+}
+#endif
+
+
+/*
+ * For each size class, zspages are divided into different groups
+ * depending on how "full" they are. This was done so that we could
+ * easily find empty or nearly empty zspages when we try to shrink
+ * the pool (not yet implemented). This function returns fullness
+ * status of the given page.
+ */
+static enum fullness_group get_fullness_group(struct page *page)
+{
+	int inuse, max_objects;
+	enum fullness_group fg;
+	BUG_ON(!is_first_page(page));
+
+	inuse = page->inuse;
+	max_objects = page->objects;
+
+	if (inuse == 0)
+		fg = ZS_EMPTY;
+	else if (inuse == max_objects)
+		fg = ZS_FULL;
+	else if (inuse <= 3 * max_objects / fullness_threshold_frac)
+		fg = ZS_ALMOST_EMPTY;
+	else
+		fg = ZS_ALMOST_FULL;
+
+	return fg;
+}
+
+/*
+ * Each size class maintains various freelists and zspages are assigned
+ * to one of these freelists based on the number of live objects they
+ * have. This functions inserts the given zspage into the freelist
+ * identified by <class, fullness_group>.
+ */
+static void insert_zspage(struct page *page, struct size_class *class,
+				enum fullness_group fullness)
+{
+	struct page **head;
+
+	BUG_ON(!is_first_page(page));
+
+	if (fullness >= _ZS_NR_FULLNESS_GROUPS)
+		return;
+
+	zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
+			CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
+
+	head = &class->fullness_list[fullness];
+	if (!*head) {
+		*head = page;
+		return;
+	}
+
+	/*
+	 * We want to see more ZS_FULL pages and less almost
+	 * empty/full. Put pages with higher ->inuse first.
+	 */
+	list_add_tail(&page->lru, &(*head)->lru);
+	if (page->inuse >= (*head)->inuse)
+		*head = page;
+}
+
+/*
+ * This function removes the given zspage from the freelist identified
+ * by <class, fullness_group>.
+ */
+static void remove_zspage(struct page *page, struct size_class *class,
+				enum fullness_group fullness)
+{
+	struct page **head;
+
+	BUG_ON(!is_first_page(page));
+
+	if (fullness >= _ZS_NR_FULLNESS_GROUPS)
+		return;
+
+	head = &class->fullness_list[fullness];
+	BUG_ON(!*head);
+	if (list_empty(&(*head)->lru))
+		*head = NULL;
+	else if (*head == page)
+		*head = (struct page *)list_entry((*head)->lru.next,
+					struct page, lru);
+
+	list_del_init(&page->lru);
+	zs_stat_dec(class, fullness == ZS_ALMOST_EMPTY ?
+			CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
+}
+
+/*
+ * Each size class maintains zspages in different fullness groups depending
+ * on the number of live objects they contain. When allocating or freeing
+ * objects, the fullness status of the page can change, say, from ALMOST_FULL
+ * to ALMOST_EMPTY when freeing an object. This function checks if such
+ * a status change has occurred for the given page and accordingly moves the
+ * page from the freelist of the old fullness group to that of the new
+ * fullness group.
+ */
+static enum fullness_group fix_fullness_group(struct size_class *class,
+						struct page *page)
+{
+	int class_idx;
+	enum fullness_group currfg, newfg;
+
+	BUG_ON(!is_first_page(page));
+
+	get_zspage_mapping(page, &class_idx, &currfg);
+	newfg = get_fullness_group(page);
+	if (newfg == currfg)
+		goto out;
+
+	remove_zspage(page, class, currfg);
+	insert_zspage(page, class, newfg);
+	set_zspage_mapping(page, class_idx, newfg);
+
+out:
+	return newfg;
+}
+
+/*
+ * We have to decide on how many pages to link together
+ * to form a zspage for each size class. This is important
+ * to reduce wastage due to unusable space left at end of
+ * each zspage which is given as:
+ *     wastage = Zp % class_size
+ *     usage = Zp - wastage
+ * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
+ *
+ * For example, for size class of 3/8 * PAGE_SIZE, we should
+ * link together 3 PAGE_SIZE sized pages to form a zspage
+ * since then we can perfectly fit in 8 such objects.
+ */
+static int get_pages_per_zspage(int class_size)
+{
+	int i, max_usedpc = 0;
+	/* zspage order which gives maximum used size per KB */
+	int max_usedpc_order = 1;
+
+	for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
+		int zspage_size;
+		int waste, usedpc;
+
+		zspage_size = i * PAGE_SIZE;
+		waste = zspage_size % class_size;
+		usedpc = (zspage_size - waste) * 100 / zspage_size;
+
+		if (usedpc > max_usedpc) {
+			max_usedpc = usedpc;
+			max_usedpc_order = i;
+		}
+	}
+
+	return max_usedpc_order;
+}
+
+/*
+ * A single 'zspage' is composed of many system pages which are
+ * linked together using fields in struct page. This function finds
+ * the first/head page, given any component page of a zspage.
+ */
+static struct page *get_first_page(struct page *page)
+{
+	if (is_first_page(page))
+		return page;
+	else
+		return (struct page *)page_private(page);
+}
+
+static struct page *get_next_page(struct page *page)
+{
+	struct page *next;
+
+	if (is_last_page(page))
+		next = NULL;
+	else if (is_first_page(page))
+		next = (struct page *)page_private(page);
+	else
+		next = list_entry(page->lru.next, struct page, lru);
+
+	return next;
+}
+
+/*
+ * Encode <page, obj_idx> as a single handle value.
+ * We use the least bit of handle for tagging.
+ */
+static void *location_to_obj(struct page *page, unsigned long obj_idx)
+{
+	unsigned long obj;
+
+	if (!page) {
+		BUG_ON(obj_idx);
+		return NULL;
+	}
+
+	obj = page_to_pfn(page) << OBJ_INDEX_BITS;
+	obj |= ((obj_idx) & OBJ_INDEX_MASK);
+	obj <<= OBJ_TAG_BITS;
+
+	return (void *)obj;
+}
+
+/*
+ * Decode <page, obj_idx> pair from the given object handle. We adjust the
+ * decoded obj_idx back to its original value since it was adjusted in
+ * location_to_obj().
+ */
+static void obj_to_location(unsigned long obj, struct page **page,
+				unsigned long *obj_idx)
+{
+	obj >>= OBJ_TAG_BITS;
+	*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
+	*obj_idx = (obj & OBJ_INDEX_MASK);
+}
+
+static unsigned long handle_to_obj(unsigned long handle)
+{
+	return *(unsigned long *)handle;
+}
+
+static unsigned long obj_to_head(struct size_class *class, struct page *page,
+			void *obj)
+{
+	if (class->huge) {
+		VM_BUG_ON(!is_first_page(page));
+		return page_private(page);
+	} else
+		return *(unsigned long *)obj;
+}
+
+static unsigned long obj_idx_to_offset(struct page *page,
+				unsigned long obj_idx, int class_size)
+{
+	unsigned long off = 0;
+
+	if (!is_first_page(page))
+		off = page->index;
+
+	return off + obj_idx * class_size;
+}
+
+static inline int trypin_tag(unsigned long handle)
+{
+	unsigned long *ptr = (unsigned long *)handle;
+
+	return !test_and_set_bit_lock(HANDLE_PIN_BIT, ptr);
+}
+
+static void pin_tag(unsigned long handle)
+{
+	while (!trypin_tag(handle));
+}
+
+static void unpin_tag(unsigned long handle)
+{
+	unsigned long *ptr = (unsigned long *)handle;
+
+	clear_bit_unlock(HANDLE_PIN_BIT, ptr);
+}
+
+static void reset_page(struct page *page)
+{
+	clear_bit(PG_private, &page->flags);
+	clear_bit(PG_private_2, &page->flags);
+	set_page_private(page, 0);
+	page->mapping = NULL;
+	page->freelist = NULL;
+	page_mapcount_reset(page);
+}
+
+static void free_zspage(struct page *first_page)
+{
+	struct page *nextp, *tmp, *head_extra;
+
+	BUG_ON(!is_first_page(first_page));
+	BUG_ON(first_page->inuse);
+
+	head_extra = (struct page *)page_private(first_page);
+
+	reset_page(first_page);
+	__free_page(first_page);
+
+	/* zspage with only 1 system page */
+	if (!head_extra)
+		return;
+
+	list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
+		list_del(&nextp->lru);
+		reset_page(nextp);
+		__free_page(nextp);
+	}
+	reset_page(head_extra);
+	__free_page(head_extra);
+}
+
+/* Initialize a newly allocated zspage */
+static void init_zspage(struct page *first_page, struct size_class *class)
+{
+	unsigned long off = 0;
+	struct page *page = first_page;
+
+	BUG_ON(!is_first_page(first_page));
+	while (page) {
+		struct page *next_page;
+		struct link_free *link;
+		unsigned int i = 1;
+		void *vaddr;
+
+		/*
+		 * page->index stores offset of first object starting
+		 * in the page. For the first page, this is always 0,
+		 * so we use first_page->index (aka ->freelist) to store
+		 * head of corresponding zspage's freelist.
+		 */
+		if (page != first_page)
+			page->index = off;
+
+		vaddr = kmap_atomic(page);
+		link = (struct link_free *)vaddr + off / sizeof(*link);
+
+		while ((off += class->size) < PAGE_SIZE) {
+			link->next = location_to_obj(page, i++);
+			link += class->size / sizeof(*link);
+		}
+
+		/*
+		 * We now come to the last (full or partial) object on this
+		 * page, which must point to the first object on the next
+		 * page (if present)
+		 */
+		next_page = get_next_page(page);
+		link->next = location_to_obj(next_page, 0);
+		kunmap_atomic(vaddr);
+		page = next_page;
+		off %= PAGE_SIZE;
+	}
+}
+
+/*
+ * Allocate a zspage for the given size class
+ */
+static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
+{
+	int i, error;
+	struct page *first_page = NULL, *uninitialized_var(prev_page);
+
+	/*
+	 * Allocate individual pages and link them together as:
+	 * 1. first page->private = first sub-page
+	 * 2. all sub-pages are linked together using page->lru
+	 * 3. each sub-page is linked to the first page using page->private
+	 *
+	 * For each size class, First/Head pages are linked together using
+	 * page->lru. Also, we set PG_private to identify the first page
+	 * (i.e. no other sub-page has this flag set) and PG_private_2 to
+	 * identify the last page.
+	 */
+	error = -ENOMEM;
+	for (i = 0; i < class->pages_per_zspage; i++) {
+		struct page *page;
+
+		page = alloc_page(flags);
+		if (!page)
+			goto cleanup;
+
+		INIT_LIST_HEAD(&page->lru);
+		if (i == 0) {	/* first page */
+			SetPagePrivate(page);
+			set_page_private(page, 0);
+			first_page = page;
+			first_page->inuse = 0;
+		}
+		if (i == 1)
+			set_page_private(first_page, (unsigned long)page);
+		if (i >= 1)
+			set_page_private(page, (unsigned long)first_page);
+		if (i >= 2)
+			list_add(&page->lru, &prev_page->lru);
+		if (i == class->pages_per_zspage - 1)	/* last page */
+			SetPagePrivate2(page);
+		prev_page = page;
+	}
+
+	init_zspage(first_page, class);
+
+	first_page->freelist = location_to_obj(first_page, 0);
+	/* Maximum number of objects we can store in this zspage */
+	first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
+
+	error = 0; /* Success */
+
+cleanup:
+	if (unlikely(error) && first_page) {
+		free_zspage(first_page);
+		first_page = NULL;
+	}
+
+	return first_page;
+}
+
+static struct page *find_get_zspage(struct size_class *class)
+{
+	int i;
+	struct page *page;
+
+	for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
+		page = class->fullness_list[i];
+		if (page)
+			break;
+	}
+
+	return page;
+}
+
+#ifdef CONFIG_PGTABLE_MAPPING
+static inline int __zs_cpu_up(struct mapping_area *area)
+{
+	/*
+	 * Make sure we don't leak memory if a cpu UP notification
+	 * and zs_init() race and both call zs_cpu_up() on the same cpu
+	 */
+	if (area->vm)
+		return 0;
+	area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
+	if (!area->vm)
+		return -ENOMEM;
+	return 0;
+}
+
+static inline void __zs_cpu_down(struct mapping_area *area)
+{
+	if (area->vm)
+		free_vm_area(area->vm);
+	area->vm = NULL;
+}
+
+static inline void *__zs_map_object(struct mapping_area *area,
+				struct page *pages[2], int off, int size)
+{
+	BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
+	area->vm_addr = area->vm->addr;
+	return area->vm_addr + off;
+}
+
+static inline void __zs_unmap_object(struct mapping_area *area,
+				struct page *pages[2], int off, int size)
+{
+	unsigned long addr = (unsigned long)area->vm_addr;
+
+	unmap_kernel_range(addr, PAGE_SIZE * 2);
+}
+
+#else /* CONFIG_PGTABLE_MAPPING */
+
+static inline int __zs_cpu_up(struct mapping_area *area)
+{
+	/*
+	 * Make sure we don't leak memory if a cpu UP notification
+	 * and zs_init() race and both call zs_cpu_up() on the same cpu
+	 */
+	if (area->vm_buf)
+		return 0;
+	area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
+	if (!area->vm_buf)
+		return -ENOMEM;
+	return 0;
+}
+
+static inline void __zs_cpu_down(struct mapping_area *area)
+{
+	kfree(area->vm_buf);
+	area->vm_buf = NULL;
+}
+
+static void *__zs_map_object(struct mapping_area *area,
+			struct page *pages[2], int off, int size)
+{
+	int sizes[2];
+	void *addr;
+	char *buf = area->vm_buf;
+
+	/* disable page faults to match kmap_atomic() return conditions */
+	pagefault_disable();
+
+	/* no read fastpath */
+	if (area->vm_mm == ZS_MM_WO)
+		goto out;
+
+	sizes[0] = PAGE_SIZE - off;
+	sizes[1] = size - sizes[0];
+
+	/* copy object to per-cpu buffer */
+	addr = kmap_atomic(pages[0]);
+	memcpy(buf, addr + off, sizes[0]);
+	kunmap_atomic(addr);
+	addr = kmap_atomic(pages[1]);
+	memcpy(buf + sizes[0], addr, sizes[1]);
+	kunmap_atomic(addr);
+out:
+	return area->vm_buf;
+}
+
+static void __zs_unmap_object(struct mapping_area *area,
+			struct page *pages[2], int off, int size)
+{
+	int sizes[2];
+	void *addr;
+	char *buf;
+
+	/* no write fastpath */
+	if (area->vm_mm == ZS_MM_RO)
+		goto out;
+
+	buf = area->vm_buf;
+	if (!area->huge) {
+		buf = buf + ZS_HANDLE_SIZE;
+		size -= ZS_HANDLE_SIZE;
+		off += ZS_HANDLE_SIZE;
+	}
+
+	sizes[0] = PAGE_SIZE - off;
+	sizes[1] = size - sizes[0];
+
+	/* copy per-cpu buffer to object */
+	addr = kmap_atomic(pages[0]);
+	memcpy(addr + off, buf, sizes[0]);
+	kunmap_atomic(addr);
+	addr = kmap_atomic(pages[1]);
+	memcpy(addr, buf + sizes[0], sizes[1]);
+	kunmap_atomic(addr);
+
+out:
+	/* enable page faults to match kunmap_atomic() return conditions */
+	pagefault_enable();
+}
+
+#endif /* CONFIG_PGTABLE_MAPPING */
+
+static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
+				void *pcpu)
+{
+	int ret, cpu = (long)pcpu;
+	struct mapping_area *area;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		area = &per_cpu(zs_map_area, cpu);
+		ret = __zs_cpu_up(area);
+		if (ret)
+			return notifier_from_errno(ret);
+		break;
+	case CPU_DEAD:
+	case CPU_UP_CANCELED:
+		area = &per_cpu(zs_map_area, cpu);
+		__zs_cpu_down(area);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block zs_cpu_nb = {
+	.notifier_call = zs_cpu_notifier
+};
+
+static int zs_register_cpu_notifier(void)
+{
+	int cpu, uninitialized_var(ret);
+
+	cpu_notifier_register_begin();
+
+	__register_cpu_notifier(&zs_cpu_nb);
+	for_each_online_cpu(cpu) {
+		ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
+		if (notifier_to_errno(ret))
+			break;
+	}
+
+	cpu_notifier_register_done();
+	return notifier_to_errno(ret);
+}
+
+static void zs_unregister_cpu_notifier(void)
+{
+	int cpu;
+
+	cpu_notifier_register_begin();
+
+	for_each_online_cpu(cpu)
+		zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
+	__unregister_cpu_notifier(&zs_cpu_nb);
+
+	cpu_notifier_register_done();
+}
+
+static void init_zs_size_classes(void)
+{
+	int nr;
+
+	nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1;
+	if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA)
+		nr += 1;
+
+	zs_size_classes = nr;
+}
+
+static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
+{
+	if (prev->pages_per_zspage != pages_per_zspage)
+		return false;
+
+	if (get_maxobj_per_zspage(prev->size, prev->pages_per_zspage)
+		!= get_maxobj_per_zspage(size, pages_per_zspage))
+		return false;
+
+	return true;
+}
+
+static bool zspage_full(struct page *page)
+{
+	BUG_ON(!is_first_page(page));
+
+	return page->inuse == page->objects;
+}
+
+unsigned long zs_get_total_pages(struct zs_pool *pool)
+{
+	return atomic_long_read(&pool->pages_allocated);
+}
+EXPORT_SYMBOL_GPL(zs_get_total_pages);
+
+/**
+ * zs_map_object - get address of allocated object from handle.
+ * @pool: pool from which the object was allocated
+ * @handle: handle returned from zs_malloc
+ *
+ * Before using an object allocated from zs_malloc, it must be mapped using
+ * this function. When done with the object, it must be unmapped using
+ * zs_unmap_object.
+ *
+ * Only one object can be mapped per cpu at a time. There is no protection
+ * against nested mappings.
+ *
+ * This function returns with preemption and page faults disabled.
+ */
+void *zs_map_object(struct zs_pool *pool, unsigned long handle,
+			enum zs_mapmode mm)
+{
+	struct page *page;
+	unsigned long obj, obj_idx, off;
+
+	unsigned int class_idx;
+	enum fullness_group fg;
+	struct size_class *class;
+	struct mapping_area *area;
+	struct page *pages[2];
+	void *ret;
+
+	BUG_ON(!handle);
+
+	/*
+	 * Because we use per-cpu mapping areas shared among the
+	 * pools/users, we can't allow mapping in interrupt context
+	 * because it can corrupt another users mappings.
+	 */
+	BUG_ON(in_interrupt());
+
+	/* From now on, migration cannot move the object */
+	pin_tag(handle);
+
+	obj = handle_to_obj(handle);
+	obj_to_location(obj, &page, &obj_idx);
+	get_zspage_mapping(get_first_page(page), &class_idx, &fg);
+	class = pool->size_class[class_idx];
+	off = obj_idx_to_offset(page, obj_idx, class->size);
+
+	area = &get_cpu_var(zs_map_area);
+	area->vm_mm = mm;
+	if (off + class->size <= PAGE_SIZE) {
+		/* this object is contained entirely within a page */
+		area->vm_addr = kmap_atomic(page);
+		ret = area->vm_addr + off;
+		goto out;
+	}
+
+	/* this object spans two pages */
+	pages[0] = page;
+	pages[1] = get_next_page(page);
+	BUG_ON(!pages[1]);
+
+	ret = __zs_map_object(area, pages, off, class->size);
+out:
+	if (!class->huge)
+		ret += ZS_HANDLE_SIZE;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(zs_map_object);
+
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
+{
+	struct page *page;
+	unsigned long obj, obj_idx, off;
+
+	unsigned int class_idx;
+	enum fullness_group fg;
+	struct size_class *class;
+	struct mapping_area *area;
+
+	BUG_ON(!handle);
+
+	obj = handle_to_obj(handle);
+	obj_to_location(obj, &page, &obj_idx);
+	get_zspage_mapping(get_first_page(page), &class_idx, &fg);
+	class = pool->size_class[class_idx];
+	off = obj_idx_to_offset(page, obj_idx, class->size);
+
+	area = this_cpu_ptr(&zs_map_area);
+	if (off + class->size <= PAGE_SIZE)
+		kunmap_atomic(area->vm_addr);
+	else {
+		struct page *pages[2];
+
+		pages[0] = page;
+		pages[1] = get_next_page(page);
+		BUG_ON(!pages[1]);
+
+		__zs_unmap_object(area, pages, off, class->size);
+	}
+	put_cpu_var(zs_map_area);
+	unpin_tag(handle);
+}
+EXPORT_SYMBOL_GPL(zs_unmap_object);
+
+static unsigned long obj_malloc(struct page *first_page,
+		struct size_class *class, unsigned long handle)
+{
+	unsigned long obj;
+	struct link_free *link;
+
+	struct page *m_page;
+	unsigned long m_objidx, m_offset;
+	void *vaddr;
+
+	handle |= OBJ_ALLOCATED_TAG;
+	obj = (unsigned long)first_page->freelist;
+	obj_to_location(obj, &m_page, &m_objidx);
+	m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
+
+	vaddr = kmap_atomic(m_page);
+	link = (struct link_free *)vaddr + m_offset / sizeof(*link);
+	first_page->freelist = link->next;
+	if (!class->huge)
+		/* record handle in the header of allocated chunk */
+		link->handle = handle;
+	else
+		/* record handle in first_page->private */
+		set_page_private(first_page, handle);
+	kunmap_atomic(vaddr);
+	first_page->inuse++;
+	zs_stat_inc(class, OBJ_USED, 1);
+
+	return obj;
+}
+
+
+/**
+ * zs_malloc - Allocate block of given size from pool.
+ * @pool: pool to allocate from
+ * @size: size of block to allocate
+ *
+ * On success, handle to the allocated object is returned,
+ * otherwise 0.
+ * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
+ */
+unsigned long zs_malloc(struct zs_pool *pool, size_t size)
+{
+	unsigned long handle, obj;
+	struct size_class *class;
+	struct page *first_page;
+
+	if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
+		return 0;
+
+	handle = alloc_handle(pool);
+	if (!handle)
+		return 0;
+
+	/* extra space in chunk to keep the handle */
+	size += ZS_HANDLE_SIZE;
+	class = pool->size_class[get_size_class_index(size)];
+
+	spin_lock(&class->lock);
+	first_page = find_get_zspage(class);
+
+	if (!first_page) {
+		spin_unlock(&class->lock);
+		first_page = alloc_zspage(class, pool->flags);
+		if (unlikely(!first_page)) {
+			free_handle(pool, handle);
+			return 0;
+		}
+
+		set_zspage_mapping(first_page, class->index, ZS_EMPTY);
+		atomic_long_add(class->pages_per_zspage,
+					&pool->pages_allocated);
+
+		spin_lock(&class->lock);
+		zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+				class->size, class->pages_per_zspage));
+	}
+
+	obj = obj_malloc(first_page, class, handle);
+	/* Now move the zspage to another fullness group, if required */
+	fix_fullness_group(class, first_page);
+	record_obj(handle, obj);
+	spin_unlock(&class->lock);
+
+	return handle;
+}
+EXPORT_SYMBOL_GPL(zs_malloc);
+
+static void obj_free(struct zs_pool *pool, struct size_class *class,
+			unsigned long obj)
+{
+	struct link_free *link;
+	struct page *first_page, *f_page;
+	unsigned long f_objidx, f_offset;
+	void *vaddr;
+
+	BUG_ON(!obj);
+
+	obj &= ~OBJ_ALLOCATED_TAG;
+	obj_to_location(obj, &f_page, &f_objidx);
+	first_page = get_first_page(f_page);
+
+	f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
+
+	vaddr = kmap_atomic(f_page);
+
+	/* Insert this object in containing zspage's freelist */
+	link = (struct link_free *)(vaddr + f_offset);
+	link->next = first_page->freelist;
+	if (class->huge)
+		set_page_private(first_page, 0);
+	kunmap_atomic(vaddr);
+	first_page->freelist = (void *)obj;
+	first_page->inuse--;
+	zs_stat_dec(class, OBJ_USED, 1);
+}
+
+void zs_free(struct zs_pool *pool, unsigned long handle)
+{
+	struct page *first_page, *f_page;
+	unsigned long obj, f_objidx;
+	int class_idx;
+	struct size_class *class;
+	enum fullness_group fullness;
+
+	if (unlikely(!handle))
+		return;
+
+	pin_tag(handle);
+	obj = handle_to_obj(handle);
+	obj_to_location(obj, &f_page, &f_objidx);
+	first_page = get_first_page(f_page);
+
+	get_zspage_mapping(first_page, &class_idx, &fullness);
+	class = pool->size_class[class_idx];
+
+	spin_lock(&class->lock);
+	obj_free(pool, class, obj);
+	fullness = fix_fullness_group(class, first_page);
+	if (fullness == ZS_EMPTY) {
+		zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+				class->size, class->pages_per_zspage));
+		atomic_long_sub(class->pages_per_zspage,
+				&pool->pages_allocated);
+		free_zspage(first_page);
+	}
+	spin_unlock(&class->lock);
+	unpin_tag(handle);
+
+	free_handle(pool, handle);
+}
+EXPORT_SYMBOL_GPL(zs_free);
+
+static void zs_object_copy(unsigned long dst, unsigned long src,
+				struct size_class *class)
+{
+	struct page *s_page, *d_page;
+	unsigned long s_objidx, d_objidx;
+	unsigned long s_off, d_off;
+	void *s_addr, *d_addr;
+	int s_size, d_size, size;
+	int written = 0;
+
+	s_size = d_size = class->size;
+
+	obj_to_location(src, &s_page, &s_objidx);
+	obj_to_location(dst, &d_page, &d_objidx);
+
+	s_off = obj_idx_to_offset(s_page, s_objidx, class->size);
+	d_off = obj_idx_to_offset(d_page, d_objidx, class->size);
+
+	if (s_off + class->size > PAGE_SIZE)
+		s_size = PAGE_SIZE - s_off;
+
+	if (d_off + class->size > PAGE_SIZE)
+		d_size = PAGE_SIZE - d_off;
+
+	s_addr = kmap_atomic(s_page);
+	d_addr = kmap_atomic(d_page);
+
+	while (1) {
+		size = min(s_size, d_size);
+		memcpy(d_addr + d_off, s_addr + s_off, size);
+		written += size;
+
+		if (written == class->size)
+			break;
+
+		s_off += size;
+		s_size -= size;
+		d_off += size;
+		d_size -= size;
+
+		if (s_off >= PAGE_SIZE) {
+			kunmap_atomic(d_addr);
+			kunmap_atomic(s_addr);
+			s_page = get_next_page(s_page);
+			BUG_ON(!s_page);
+			s_addr = kmap_atomic(s_page);
+			d_addr = kmap_atomic(d_page);
+			s_size = class->size - written;
+			s_off = 0;
+		}
+
+		if (d_off >= PAGE_SIZE) {
+			kunmap_atomic(d_addr);
+			d_page = get_next_page(d_page);
+			BUG_ON(!d_page);
+			d_addr = kmap_atomic(d_page);
+			d_size = class->size - written;
+			d_off = 0;
+		}
+	}
+
+	kunmap_atomic(d_addr);
+	kunmap_atomic(s_addr);
+}
+
+/*
+ * Find alloced object in zspage from index object and
+ * return handle.
+ */
+static unsigned long find_alloced_obj(struct page *page, int index,
+					struct size_class *class)
+{
+	unsigned long head;
+	int offset = 0;
+	unsigned long handle = 0;
+	void *addr = kmap_atomic(page);
+
+	if (!is_first_page(page))
+		offset = page->index;
+	offset += class->size * index;
+
+	while (offset < PAGE_SIZE) {
+		head = obj_to_head(class, page, addr + offset);
+		if (head & OBJ_ALLOCATED_TAG) {
+			handle = head & ~OBJ_ALLOCATED_TAG;
+			if (trypin_tag(handle))
+				break;
+			handle = 0;
+		}
+
+		offset += class->size;
+		index++;
+	}
+
+	kunmap_atomic(addr);
+	return handle;
+}
+
+struct zs_compact_control {
+	/* Source page for migration which could be a subpage of zspage. */
+	struct page *s_page;
+	/* Destination page for migration which should be a first page
+	 * of zspage. */
+	struct page *d_page;
+	 /* Starting object index within @s_page which used for live object
+	  * in the subpage. */
+	int index;
+};
+
+static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
+				struct zs_compact_control *cc)
+{
+	unsigned long used_obj, free_obj;
+	unsigned long handle;
+	struct page *s_page = cc->s_page;
+	struct page *d_page = cc->d_page;
+	unsigned long index = cc->index;
+	int ret = 0;
+
+	while (1) {
+		handle = find_alloced_obj(s_page, index, class);
+		if (!handle) {
+			s_page = get_next_page(s_page);
+			if (!s_page)
+				break;
+			index = 0;
+			continue;
+		}
+
+		/* Stop if there is no more space */
+		if (zspage_full(d_page)) {
+			unpin_tag(handle);
+			ret = -ENOMEM;
+			break;
+		}
+
+		used_obj = handle_to_obj(handle);
+		free_obj = obj_malloc(d_page, class, handle);
+		zs_object_copy(free_obj, used_obj, class);
+		index++;
+		/*
+		 * record_obj updates handle's value to free_obj and it will
+		 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
+		 * breaks synchronization using pin_tag(e,g, zs_free) so
+		 * let's keep the lock bit.
+		 */
+		free_obj |= BIT(HANDLE_PIN_BIT);
+		record_obj(handle, free_obj);
+		unpin_tag(handle);
+		obj_free(pool, class, used_obj);
+	}
+
+	/* Remember last position in this iteration */
+	cc->s_page = s_page;
+	cc->index = index;
+
+	return ret;
+}
+
+static struct page *isolate_target_page(struct size_class *class)
+{
+	int i;
+	struct page *page;
+
+	for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
+		page = class->fullness_list[i];
+		if (page) {
+			remove_zspage(page, class, i);
+			break;
+		}
+	}
+
+	return page;
+}
+
+/*
+ * putback_zspage - add @first_page into right class's fullness list
+ * @pool: target pool
+ * @class: destination class
+ * @first_page: target page
+ *
+ * Return @fist_page's fullness_group
+ */
+static enum fullness_group putback_zspage(struct zs_pool *pool,
+			struct size_class *class,
+			struct page *first_page)
+{
+	enum fullness_group fullness;
+
+	BUG_ON(!is_first_page(first_page));
+
+	fullness = get_fullness_group(first_page);
+	insert_zspage(first_page, class, fullness);
+	set_zspage_mapping(first_page, class->index, fullness);
+
+	if (fullness == ZS_EMPTY) {
+		zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+			class->size, class->pages_per_zspage));
+		atomic_long_sub(class->pages_per_zspage,
+				&pool->pages_allocated);
+
+		free_zspage(first_page);
+	}
+
+	return fullness;
+}
+
+static struct page *isolate_source_page(struct size_class *class)
+{
+	int i;
+	struct page *page = NULL;
+
+	for (i = ZS_ALMOST_EMPTY; i >= ZS_ALMOST_FULL; i--) {
+		page = class->fullness_list[i];
+		if (!page)
+			continue;
+
+		remove_zspage(page, class, i);
+		break;
+	}
+
+	return page;
+}
+
+/*
+ *
+ * Based on the number of unused allocated objects calculate
+ * and return the number of pages that we can free.
+ */
+static unsigned long zs_can_compact(struct size_class *class)
+{
+	unsigned long obj_wasted;
+	unsigned long obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
+	unsigned long obj_used = zs_stat_get(class, OBJ_USED);
+
+	if (obj_allocated <= obj_used)
+		return 0;
+
+	obj_wasted = obj_allocated - obj_used;
+	obj_wasted /= get_maxobj_per_zspage(class->size,
+			class->pages_per_zspage);
+
+	return obj_wasted * class->pages_per_zspage;
+}
+
+static void __zs_compact(struct zs_pool *pool, struct size_class *class)
+{
+	struct zs_compact_control cc;
+	struct page *src_page;
+	struct page *dst_page = NULL;
+
+	spin_lock(&class->lock);
+	while ((src_page = isolate_source_page(class))) {
+
+		BUG_ON(!is_first_page(src_page));
+
+		if (!zs_can_compact(class))
+			break;
+
+		cc.index = 0;
+		cc.s_page = src_page;
+
+		while ((dst_page = isolate_target_page(class))) {
+			cc.d_page = dst_page;
+			/*
+			 * If there is no more space in dst_page, resched
+			 * and see if anyone had allocated another zspage.
+			 */
+			if (!migrate_zspage(pool, class, &cc))
+				break;
+
+			putback_zspage(pool, class, dst_page);
+		}
+
+		/* Stop if we couldn't find slot */
+		if (dst_page == NULL)
+			break;
+
+		putback_zspage(pool, class, dst_page);
+		if (putback_zspage(pool, class, src_page) == ZS_EMPTY)
+			pool->stats.pages_compacted += class->pages_per_zspage;
+		spin_unlock(&class->lock);
+		cond_resched();
+		spin_lock(&class->lock);
+	}
+
+	if (src_page)
+		putback_zspage(pool, class, src_page);
+
+	spin_unlock(&class->lock);
+}
+
+unsigned long zs_compact(struct zs_pool *pool)
+{
+	int i;
+	struct size_class *class;
+
+	for (i = zs_size_classes - 1; i >= 0; i--) {
+		class = pool->size_class[i];
+		if (!class)
+			continue;
+		if (class->index != i)
+			continue;
+		__zs_compact(pool, class);
+	}
+
+	return pool->stats.pages_compacted;
+}
+EXPORT_SYMBOL_GPL(zs_compact);
+
+void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
+{
+	memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
+}
+EXPORT_SYMBOL_GPL(zs_pool_stats);
+
+static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
+		struct shrink_control *sc)
+{
+	unsigned long pages_freed;
+	struct zs_pool *pool = container_of(shrinker, struct zs_pool,
+			shrinker);
+
+	pages_freed = pool->stats.pages_compacted;
+	/*
+	 * Compact classes and calculate compaction delta.
+	 * Can run concurrently with a manually triggered
+	 * (by user) compaction.
+	 */
+	pages_freed = zs_compact(pool) - pages_freed;
+
+	return pages_freed ? pages_freed : SHRINK_STOP;
+}
+
+static unsigned long zs_shrinker_count(struct shrinker *shrinker,
+		struct shrink_control *sc)
+{
+	int i;
+	struct size_class *class;
+	unsigned long pages_to_free = 0;
+	struct zs_pool *pool = container_of(shrinker, struct zs_pool,
+			shrinker);
+
+	for (i = zs_size_classes - 1; i >= 0; i--) {
+		class = pool->size_class[i];
+		if (!class)
+			continue;
+		if (class->index != i)
+			continue;
+
+		pages_to_free += zs_can_compact(class);
+	}
+
+	return pages_to_free;
+}
+
+static void zs_unregister_shrinker(struct zs_pool *pool)
+{
+	if (pool->shrinker_enabled) {
+		unregister_shrinker(&pool->shrinker);
+		pool->shrinker_enabled = false;
+	}
+}
+
+static int zs_register_shrinker(struct zs_pool *pool)
+{
+	pool->shrinker.scan_objects = zs_shrinker_scan;
+	pool->shrinker.count_objects = zs_shrinker_count;
+	pool->shrinker.batch = 0;
+	pool->shrinker.seeks = DEFAULT_SEEKS;
+
+	return register_shrinker(&pool->shrinker);
+}
+
+/**
+ * zs_create_pool - Creates an allocation pool to work from.
+ * @flags: allocation flags used to allocate pool metadata
+ *
+ * This function must be called before anything when using
+ * the zsmalloc allocator.
+ *
+ * On success, a pointer to the newly created pool is returned,
+ * otherwise NULL.
+ */
+struct zs_pool *zs_create_pool(const char *name, gfp_t flags)
+{
+	int i;
+	struct zs_pool *pool;
+	struct size_class *prev_class = NULL;
+
+	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+	if (!pool)
+		return NULL;
+
+	pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
+			GFP_KERNEL);
+	if (!pool->size_class) {
+		kfree(pool);
+		return NULL;
+	}
+
+	pool->name = kstrdup(name, GFP_KERNEL);
+	if (!pool->name)
+		goto err;
+
+	if (create_handle_cache(pool))
+		goto err;
+
+	/*
+	 * Iterate reversly, because, size of size_class that we want to use
+	 * for merging should be larger or equal to current size.
+	 */
+	for (i = zs_size_classes - 1; i >= 0; i--) {
+		int size;
+		int pages_per_zspage;
+		struct size_class *class;
+
+		size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
+		if (size > ZS_MAX_ALLOC_SIZE)
+			size = ZS_MAX_ALLOC_SIZE;
+		pages_per_zspage = get_pages_per_zspage(size);
+
+		/*
+		 * size_class is used for normal zsmalloc operation such
+		 * as alloc/free for that size. Although it is natural that we
+		 * have one size_class for each size, there is a chance that we
+		 * can get more memory utilization if we use one size_class for
+		 * many different sizes whose size_class have same
+		 * characteristics. So, we makes size_class point to
+		 * previous size_class if possible.
+		 */
+		if (prev_class) {
+			if (can_merge(prev_class, size, pages_per_zspage)) {
+				pool->size_class[i] = prev_class;
+				continue;
+			}
+		}
+
+		class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
+		if (!class)
+			goto err;
+
+		class->size = size;
+		class->index = i;
+		class->pages_per_zspage = pages_per_zspage;
+		if (pages_per_zspage == 1 &&
+			get_maxobj_per_zspage(size, pages_per_zspage) == 1)
+			class->huge = true;
+		spin_lock_init(&class->lock);
+		pool->size_class[i] = class;
+
+		prev_class = class;
+	}
+
+	pool->flags = flags;
+
+	if (zs_pool_stat_create(name, pool))
+		goto err;
+
+	/*
+	 * Not critical, we still can use the pool
+	 * and user can trigger compaction manually.
+	 */
+	if (zs_register_shrinker(pool) == 0)
+		pool->shrinker_enabled = true;
+	return pool;
+
+err:
+	zs_destroy_pool(pool);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(zs_create_pool);
+
+void zs_destroy_pool(struct zs_pool *pool)
+{
+	int i;
+
+	zs_unregister_shrinker(pool);
+	zs_pool_stat_destroy(pool);
+
+	for (i = 0; i < zs_size_classes; i++) {
+		int fg;
+		struct size_class *class = pool->size_class[i];
+
+		if (!class)
+			continue;
+
+		if (class->index != i)
+			continue;
+
+		for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
+			if (class->fullness_list[fg]) {
+				pr_info("Freeing non-empty class with size %db, fullness group %d\n",
+					class->size, fg);
+			}
+		}
+		kfree(class);
+	}
+
+	destroy_handle_cache(pool);
+	kfree(pool->size_class);
+	kfree(pool->name);
+	kfree(pool);
+}
+EXPORT_SYMBOL_GPL(zs_destroy_pool);
+
+static int __init zs_init(void)
+{
+	int ret = zs_register_cpu_notifier();
+
+	if (ret)
+		goto notifier_fail;
+
+	init_zs_size_classes();
+
+#ifdef CONFIG_ZPOOL
+	zpool_register_driver(&zs_zpool_driver);
+#endif
+
+	ret = zs_stat_init();
+	if (ret) {
+		pr_err("zs stat initialization failed\n");
+		goto stat_fail;
+	}
+	return 0;
+
+stat_fail:
+#ifdef CONFIG_ZPOOL
+	zpool_unregister_driver(&zs_zpool_driver);
+#endif
+notifier_fail:
+	zs_unregister_cpu_notifier();
+
+	return ret;
+}
+
+static void __exit zs_exit(void)
+{
+#ifdef CONFIG_ZPOOL
+	zpool_unregister_driver(&zs_zpool_driver);
+#endif
+	zs_unregister_cpu_notifier();
+
+	zs_stat_exit();
+}
+
+module_init(zs_init);
+module_exit(zs_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
diff --git a/mm/zswap.c b/mm/zswap.c
new file mode 100644
index 0000000..45476f4
--- /dev/null
+++ b/mm/zswap.c
@@ -0,0 +1,1305 @@
+/*
+ * zswap.c - zswap driver file
+ *
+ * zswap is a backend for frontswap that takes pages that are in the process
+ * of being swapped out and attempts to compress and store them in a
+ * RAM-based memory pool.  This can result in a significant I/O reduction on
+ * the swap device and, in the case where decompressing from RAM is faster
+ * than reading from the swap device, can also improve workload performance.
+ *
+ * Copyright (C) 2012  Seth Jennings <sjenning@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+*/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/cpu.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/atomic.h>
+#include <linux/frontswap.h>
+#include <linux/rbtree.h>
+#include <linux/swap.h>
+#include <linux/crypto.h>
+#include <linux/mempool.h>
+#include <linux/zpool.h>
+
+#include <linux/mm_types.h>
+#include <linux/page-flags.h>
+#include <linux/swapops.h>
+#include <linux/writeback.h>
+#include <linux/pagemap.h>
+
+/*********************************
+* statistics
+**********************************/
+/* Total bytes used by the compressed storage */
+static u64 zswap_pool_total_size;
+/* The number of compressed pages currently stored in zswap */
+static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
+
+/*
+ * The statistics below are not protected from concurrent access for
+ * performance reasons so they may not be a 100% accurate.  However,
+ * they do provide useful information on roughly how many times a
+ * certain event is occurring.
+*/
+
+/* Pool limit was hit (see zswap_max_pool_percent) */
+static u64 zswap_pool_limit_hit;
+/* Pages written back when pool limit was reached */
+static u64 zswap_written_back_pages;
+/* Store failed due to a reclaim failure after pool limit was reached */
+static u64 zswap_reject_reclaim_fail;
+/* Compressed page was too big for the allocator to (optimally) store */
+static u64 zswap_reject_compress_poor;
+/* Store failed because underlying allocator could not get memory */
+static u64 zswap_reject_alloc_fail;
+/* Store failed because the entry metadata could not be allocated (rare) */
+static u64 zswap_reject_kmemcache_fail;
+/* Duplicate store was encountered (rare) */
+static u64 zswap_duplicate_entry;
+
+/*********************************
+* tunables
+**********************************/
+
+/* Enable/disable zswap (disabled by default) */
+static bool zswap_enabled;
+static int zswap_enabled_param_set(const char *,
+				   const struct kernel_param *);
+static struct kernel_param_ops zswap_enabled_param_ops = {
+	.set =		zswap_enabled_param_set,
+	.get =		param_get_bool,
+};
+module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
+
+/* Crypto compressor to use */
+#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
+static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
+static int zswap_compressor_param_set(const char *,
+				      const struct kernel_param *);
+static struct kernel_param_ops zswap_compressor_param_ops = {
+	.set =		zswap_compressor_param_set,
+	.get =		param_get_charp,
+	.free =		param_free_charp,
+};
+module_param_cb(compressor, &zswap_compressor_param_ops,
+		&zswap_compressor, 0644);
+
+/* Compressed storage zpool to use */
+#define ZSWAP_ZPOOL_DEFAULT "zbud"
+static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
+static int zswap_zpool_param_set(const char *, const struct kernel_param *);
+static struct kernel_param_ops zswap_zpool_param_ops = {
+	.set =		zswap_zpool_param_set,
+	.get =		param_get_charp,
+	.free =		param_free_charp,
+};
+module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
+
+/* The maximum percentage of memory that the compressed pool can occupy */
+static unsigned int zswap_max_pool_percent = 20;
+module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644);
+
+/*********************************
+* data structures
+**********************************/
+
+struct zswap_pool {
+	struct zpool *zpool;
+	struct crypto_comp * __percpu *tfm;
+	struct kref kref;
+	struct list_head list;
+	struct rcu_head rcu_head;
+	struct notifier_block notifier;
+	char tfm_name[CRYPTO_MAX_ALG_NAME];
+};
+
+/*
+ * struct zswap_entry
+ *
+ * This structure contains the metadata for tracking a single compressed
+ * page within zswap.
+ *
+ * rbnode - links the entry into red-black tree for the appropriate swap type
+ * offset - the swap offset for the entry.  Index into the red-black tree.
+ * refcount - the number of outstanding reference to the entry. This is needed
+ *            to protect against premature freeing of the entry by code
+ *            concurrent calls to load, invalidate, and writeback.  The lock
+ *            for the zswap_tree structure that contains the entry must
+ *            be held while changing the refcount.  Since the lock must
+ *            be held, there is no reason to also make refcount atomic.
+ * length - the length in bytes of the compressed page data.  Needed during
+ *          decompression
+ * pool - the zswap_pool the entry's data is in
+ * handle - zpool allocation handle that stores the compressed page data
+ */
+struct zswap_entry {
+	struct rb_node rbnode;
+	pgoff_t offset;
+	int refcount;
+	unsigned int length;
+	struct zswap_pool *pool;
+	unsigned long handle;
+};
+
+struct zswap_header {
+	swp_entry_t swpentry;
+};
+
+/*
+ * The tree lock in the zswap_tree struct protects a few things:
+ * - the rbtree
+ * - the refcount field of each entry in the tree
+ */
+struct zswap_tree {
+	struct rb_root rbroot;
+	spinlock_t lock;
+};
+
+static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
+
+/* RCU-protected iteration */
+static LIST_HEAD(zswap_pools);
+/* protects zswap_pools list modification */
+static DEFINE_SPINLOCK(zswap_pools_lock);
+/* pool counter to provide unique names to zpool */
+static atomic_t zswap_pools_count = ATOMIC_INIT(0);
+
+/* used by param callback function */
+static bool zswap_init_started;
+
+/* fatal error during init */
+static bool zswap_init_failed;
+
+/*********************************
+* helpers and fwd declarations
+**********************************/
+
+#define zswap_pool_debug(msg, p)				\
+	pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name,		\
+		 zpool_get_type((p)->zpool))
+
+static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
+static int zswap_pool_get(struct zswap_pool *pool);
+static void zswap_pool_put(struct zswap_pool *pool);
+
+static const struct zpool_ops zswap_zpool_ops = {
+	.evict = zswap_writeback_entry
+};
+
+static bool zswap_is_full(void)
+{
+	return totalram_pages * zswap_max_pool_percent / 100 <
+		DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
+}
+
+static void zswap_update_total_size(void)
+{
+	struct zswap_pool *pool;
+	u64 total = 0;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(pool, &zswap_pools, list)
+		total += zpool_get_total_size(pool->zpool);
+
+	rcu_read_unlock();
+
+	zswap_pool_total_size = total;
+}
+
+/*********************************
+* zswap entry functions
+**********************************/
+static struct kmem_cache *zswap_entry_cache;
+
+static int __init zswap_entry_cache_create(void)
+{
+	zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
+	return zswap_entry_cache == NULL;
+}
+
+static void __init zswap_entry_cache_destroy(void)
+{
+	kmem_cache_destroy(zswap_entry_cache);
+}
+
+static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
+{
+	struct zswap_entry *entry;
+	entry = kmem_cache_alloc(zswap_entry_cache, gfp);
+	if (!entry)
+		return NULL;
+	entry->refcount = 1;
+	RB_CLEAR_NODE(&entry->rbnode);
+	return entry;
+}
+
+static void zswap_entry_cache_free(struct zswap_entry *entry)
+{
+	kmem_cache_free(zswap_entry_cache, entry);
+}
+
+/*********************************
+* rbtree functions
+**********************************/
+static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
+{
+	struct rb_node *node = root->rb_node;
+	struct zswap_entry *entry;
+
+	while (node) {
+		entry = rb_entry(node, struct zswap_entry, rbnode);
+		if (entry->offset > offset)
+			node = node->rb_left;
+		else if (entry->offset < offset)
+			node = node->rb_right;
+		else
+			return entry;
+	}
+	return NULL;
+}
+
+/*
+ * In the case that a entry with the same offset is found, a pointer to
+ * the existing entry is stored in dupentry and the function returns -EEXIST
+ */
+static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
+			struct zswap_entry **dupentry)
+{
+	struct rb_node **link = &root->rb_node, *parent = NULL;
+	struct zswap_entry *myentry;
+
+	while (*link) {
+		parent = *link;
+		myentry = rb_entry(parent, struct zswap_entry, rbnode);
+		if (myentry->offset > entry->offset)
+			link = &(*link)->rb_left;
+		else if (myentry->offset < entry->offset)
+			link = &(*link)->rb_right;
+		else {
+			*dupentry = myentry;
+			return -EEXIST;
+		}
+	}
+	rb_link_node(&entry->rbnode, parent, link);
+	rb_insert_color(&entry->rbnode, root);
+	return 0;
+}
+
+static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
+{
+	if (!RB_EMPTY_NODE(&entry->rbnode)) {
+		rb_erase(&entry->rbnode, root);
+		RB_CLEAR_NODE(&entry->rbnode);
+	}
+}
+
+/*
+ * Carries out the common pattern of freeing and entry's zpool allocation,
+ * freeing the entry itself, and decrementing the number of stored pages.
+ */
+static void zswap_free_entry(struct zswap_entry *entry)
+{
+	zpool_free(entry->pool->zpool, entry->handle);
+	zswap_pool_put(entry->pool);
+	zswap_entry_cache_free(entry);
+	atomic_dec(&zswap_stored_pages);
+	zswap_update_total_size();
+}
+
+/* caller must hold the tree lock */
+static void zswap_entry_get(struct zswap_entry *entry)
+{
+	entry->refcount++;
+}
+
+/* caller must hold the tree lock
+* remove from the tree and free it, if nobody reference the entry
+*/
+static void zswap_entry_put(struct zswap_tree *tree,
+			struct zswap_entry *entry)
+{
+	int refcount = --entry->refcount;
+
+	BUG_ON(refcount < 0);
+	if (refcount == 0) {
+		zswap_rb_erase(&tree->rbroot, entry);
+		zswap_free_entry(entry);
+	}
+}
+
+/* caller must hold the tree lock */
+static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
+				pgoff_t offset)
+{
+	struct zswap_entry *entry;
+
+	entry = zswap_rb_search(root, offset);
+	if (entry)
+		zswap_entry_get(entry);
+
+	return entry;
+}
+
+/*********************************
+* per-cpu code
+**********************************/
+static DEFINE_PER_CPU(u8 *, zswap_dstmem);
+
+static int __zswap_cpu_dstmem_notifier(unsigned long action, unsigned long cpu)
+{
+	u8 *dst;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+		if (!dst) {
+			pr_err("can't allocate compressor buffer\n");
+			return NOTIFY_BAD;
+		}
+		per_cpu(zswap_dstmem, cpu) = dst;
+		break;
+	case CPU_DEAD:
+	case CPU_UP_CANCELED:
+		dst = per_cpu(zswap_dstmem, cpu);
+		kfree(dst);
+		per_cpu(zswap_dstmem, cpu) = NULL;
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static int zswap_cpu_dstmem_notifier(struct notifier_block *nb,
+				     unsigned long action, void *pcpu)
+{
+	return __zswap_cpu_dstmem_notifier(action, (unsigned long)pcpu);
+}
+
+static struct notifier_block zswap_dstmem_notifier = {
+	.notifier_call =	zswap_cpu_dstmem_notifier,
+};
+
+static int __init zswap_cpu_dstmem_init(void)
+{
+	unsigned long cpu;
+
+	cpu_notifier_register_begin();
+	for_each_online_cpu(cpu)
+		if (__zswap_cpu_dstmem_notifier(CPU_UP_PREPARE, cpu) ==
+		    NOTIFY_BAD)
+			goto cleanup;
+	__register_cpu_notifier(&zswap_dstmem_notifier);
+	cpu_notifier_register_done();
+	return 0;
+
+cleanup:
+	for_each_online_cpu(cpu)
+		__zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
+	cpu_notifier_register_done();
+	return -ENOMEM;
+}
+
+static void zswap_cpu_dstmem_destroy(void)
+{
+	unsigned long cpu;
+
+	cpu_notifier_register_begin();
+	for_each_online_cpu(cpu)
+		__zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
+	__unregister_cpu_notifier(&zswap_dstmem_notifier);
+	cpu_notifier_register_done();
+}
+
+static int __zswap_cpu_comp_notifier(struct zswap_pool *pool,
+				     unsigned long action, unsigned long cpu)
+{
+	struct crypto_comp *tfm;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
+			break;
+		tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
+		if (IS_ERR_OR_NULL(tfm)) {
+			pr_err("could not alloc crypto comp %s : %ld\n",
+			       pool->tfm_name, PTR_ERR(tfm));
+			return NOTIFY_BAD;
+		}
+		*per_cpu_ptr(pool->tfm, cpu) = tfm;
+		break;
+	case CPU_DEAD:
+	case CPU_UP_CANCELED:
+		tfm = *per_cpu_ptr(pool->tfm, cpu);
+		if (!IS_ERR_OR_NULL(tfm))
+			crypto_free_comp(tfm);
+		*per_cpu_ptr(pool->tfm, cpu) = NULL;
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static int zswap_cpu_comp_notifier(struct notifier_block *nb,
+				   unsigned long action, void *pcpu)
+{
+	unsigned long cpu = (unsigned long)pcpu;
+	struct zswap_pool *pool = container_of(nb, typeof(*pool), notifier);
+
+	return __zswap_cpu_comp_notifier(pool, action, cpu);
+}
+
+static int zswap_cpu_comp_init(struct zswap_pool *pool)
+{
+	unsigned long cpu;
+
+	memset(&pool->notifier, 0, sizeof(pool->notifier));
+	pool->notifier.notifier_call = zswap_cpu_comp_notifier;
+
+	cpu_notifier_register_begin();
+	for_each_online_cpu(cpu)
+		if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) ==
+		    NOTIFY_BAD)
+			goto cleanup;
+	__register_cpu_notifier(&pool->notifier);
+	cpu_notifier_register_done();
+	return 0;
+
+cleanup:
+	for_each_online_cpu(cpu)
+		__zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
+	cpu_notifier_register_done();
+	return -ENOMEM;
+}
+
+static void zswap_cpu_comp_destroy(struct zswap_pool *pool)
+{
+	unsigned long cpu;
+
+	cpu_notifier_register_begin();
+	for_each_online_cpu(cpu)
+		__zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
+	__unregister_cpu_notifier(&pool->notifier);
+	cpu_notifier_register_done();
+}
+
+/*********************************
+* pool functions
+**********************************/
+
+static struct zswap_pool *__zswap_pool_current(void)
+{
+	struct zswap_pool *pool;
+
+	pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
+	WARN_ON(!pool);
+
+	return pool;
+}
+
+static struct zswap_pool *zswap_pool_current(void)
+{
+	assert_spin_locked(&zswap_pools_lock);
+
+	return __zswap_pool_current();
+}
+
+static struct zswap_pool *zswap_pool_current_get(void)
+{
+	struct zswap_pool *pool;
+
+	rcu_read_lock();
+
+	pool = __zswap_pool_current();
+	if (!pool || !zswap_pool_get(pool))
+		pool = NULL;
+
+	rcu_read_unlock();
+
+	return pool;
+}
+
+static struct zswap_pool *zswap_pool_last_get(void)
+{
+	struct zswap_pool *pool, *last = NULL;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(pool, &zswap_pools, list)
+		last = pool;
+	if (!WARN_ON(!last) && !zswap_pool_get(last))
+		last = NULL;
+
+	rcu_read_unlock();
+
+	return last;
+}
+
+/* type and compressor must be null-terminated */
+static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
+{
+	struct zswap_pool *pool;
+
+	assert_spin_locked(&zswap_pools_lock);
+
+	list_for_each_entry_rcu(pool, &zswap_pools, list) {
+		if (strcmp(pool->tfm_name, compressor))
+			continue;
+		if (strcmp(zpool_get_type(pool->zpool), type))
+			continue;
+		/* if we can't get it, it's about to be destroyed */
+		if (!zswap_pool_get(pool))
+			continue;
+		return pool;
+	}
+
+	return NULL;
+}
+
+static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
+{
+	struct zswap_pool *pool;
+	char name[38]; /* 'zswap' + 32 char (max) num + \0 */
+	gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
+
+	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+	if (!pool) {
+		pr_err("pool alloc failed\n");
+		return NULL;
+	}
+
+	/* unique name for each pool specifically required by zsmalloc */
+	snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count));
+
+	pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops);
+	if (!pool->zpool) {
+		pr_err("%s zpool not available\n", type);
+		goto error;
+	}
+	pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
+
+	strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
+	pool->tfm = alloc_percpu(struct crypto_comp *);
+	if (!pool->tfm) {
+		pr_err("percpu alloc failed\n");
+		goto error;
+	}
+
+	if (zswap_cpu_comp_init(pool))
+		goto error;
+	pr_debug("using %s compressor\n", pool->tfm_name);
+
+	/* being the current pool takes 1 ref; this func expects the
+	 * caller to always add the new pool as the current pool
+	 */
+	kref_init(&pool->kref);
+	INIT_LIST_HEAD(&pool->list);
+
+	zswap_pool_debug("created", pool);
+
+	return pool;
+
+error:
+	free_percpu(pool->tfm);
+	if (pool->zpool)
+		zpool_destroy_pool(pool->zpool);
+	kfree(pool);
+	return NULL;
+}
+
+static __init struct zswap_pool *__zswap_pool_create_fallback(void)
+{
+	if (!crypto_has_comp(zswap_compressor, 0, 0)) {
+		if (!strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) {
+			pr_err("default compressor %s not available\n",
+			       zswap_compressor);
+			return NULL;
+		}
+		pr_err("compressor %s not available, using default %s\n",
+		       zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
+		param_free_charp(&zswap_compressor);
+		zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
+	}
+	if (!zpool_has_pool(zswap_zpool_type)) {
+		if (!strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
+			pr_err("default zpool %s not available\n",
+			       zswap_zpool_type);
+			return NULL;
+		}
+		pr_err("zpool %s not available, using default %s\n",
+		       zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
+		param_free_charp(&zswap_zpool_type);
+		zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
+	}
+
+	return zswap_pool_create(zswap_zpool_type, zswap_compressor);
+}
+
+static void zswap_pool_destroy(struct zswap_pool *pool)
+{
+	zswap_pool_debug("destroying", pool);
+
+	zswap_cpu_comp_destroy(pool);
+	free_percpu(pool->tfm);
+	zpool_destroy_pool(pool->zpool);
+	kfree(pool);
+}
+
+static int __must_check zswap_pool_get(struct zswap_pool *pool)
+{
+	return kref_get_unless_zero(&pool->kref);
+}
+
+static void __zswap_pool_release(struct rcu_head *head)
+{
+	struct zswap_pool *pool = container_of(head, typeof(*pool), rcu_head);
+
+	/* nobody should have been able to get a kref... */
+	WARN_ON(kref_get_unless_zero(&pool->kref));
+
+	/* pool is now off zswap_pools list and has no references. */
+	zswap_pool_destroy(pool);
+}
+
+static void __zswap_pool_empty(struct kref *kref)
+{
+	struct zswap_pool *pool;
+
+	pool = container_of(kref, typeof(*pool), kref);
+
+	spin_lock(&zswap_pools_lock);
+
+	WARN_ON(pool == zswap_pool_current());
+
+	list_del_rcu(&pool->list);
+	call_rcu(&pool->rcu_head, __zswap_pool_release);
+
+	spin_unlock(&zswap_pools_lock);
+}
+
+static void zswap_pool_put(struct zswap_pool *pool)
+{
+	kref_put(&pool->kref, __zswap_pool_empty);
+}
+
+/*********************************
+* param callbacks
+**********************************/
+
+/* val must be a null-terminated string */
+static int __zswap_param_set(const char *val, const struct kernel_param *kp,
+			     char *type, char *compressor)
+{
+	struct zswap_pool *pool, *put_pool = NULL;
+	char *s = strstrip((char *)val);
+	int ret;
+
+	if (zswap_init_failed) {
+		pr_err("can't set param, initialization failed\n");
+		return -ENODEV;
+	}
+
+	/* no change required */
+	if (!strcmp(s, *(char **)kp->arg))
+		return 0;
+
+	/* if this is load-time (pre-init) param setting,
+	 * don't create a pool; that's done during init.
+	 */
+	if (!zswap_init_started)
+		return param_set_charp(s, kp);
+
+	if (!type) {
+		if (!zpool_has_pool(s)) {
+			pr_err("zpool %s not available\n", s);
+			return -ENOENT;
+		}
+		type = s;
+	} else if (!compressor) {
+		if (!crypto_has_comp(s, 0, 0)) {
+			pr_err("compressor %s not available\n", s);
+			return -ENOENT;
+		}
+		compressor = s;
+	} else {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	spin_lock(&zswap_pools_lock);
+
+	pool = zswap_pool_find_get(type, compressor);
+	if (pool) {
+		zswap_pool_debug("using existing", pool);
+		list_del_rcu(&pool->list);
+	} else {
+		spin_unlock(&zswap_pools_lock);
+		pool = zswap_pool_create(type, compressor);
+		spin_lock(&zswap_pools_lock);
+	}
+
+	if (pool)
+		ret = param_set_charp(s, kp);
+	else
+		ret = -EINVAL;
+
+	if (!ret) {
+		put_pool = zswap_pool_current();
+		list_add_rcu(&pool->list, &zswap_pools);
+	} else if (pool) {
+		/* add the possibly pre-existing pool to the end of the pools
+		 * list; if it's new (and empty) then it'll be removed and
+		 * destroyed by the put after we drop the lock
+		 */
+		list_add_tail_rcu(&pool->list, &zswap_pools);
+		put_pool = pool;
+	}
+
+	spin_unlock(&zswap_pools_lock);
+
+	/* drop the ref from either the old current pool,
+	 * or the new pool we failed to add
+	 */
+	if (put_pool)
+		zswap_pool_put(put_pool);
+
+	return ret;
+}
+
+static int zswap_compressor_param_set(const char *val,
+				      const struct kernel_param *kp)
+{
+	return __zswap_param_set(val, kp, zswap_zpool_type, NULL);
+}
+
+static int zswap_zpool_param_set(const char *val,
+				 const struct kernel_param *kp)
+{
+	return __zswap_param_set(val, kp, NULL, zswap_compressor);
+}
+
+static int zswap_enabled_param_set(const char *val,
+				   const struct kernel_param *kp)
+{
+	if (zswap_init_failed) {
+		pr_err("can't enable, initialization failed\n");
+		return -ENODEV;
+	}
+
+	return param_set_bool(val, kp);
+}
+
+/*********************************
+* writeback code
+**********************************/
+/* return enum for zswap_get_swap_cache_page */
+enum zswap_get_swap_ret {
+	ZSWAP_SWAPCACHE_NEW,
+	ZSWAP_SWAPCACHE_EXIST,
+	ZSWAP_SWAPCACHE_FAIL,
+};
+
+/*
+ * zswap_get_swap_cache_page
+ *
+ * This is an adaption of read_swap_cache_async()
+ *
+ * This function tries to find a page with the given swap entry
+ * in the swapper_space address space (the swap cache).  If the page
+ * is found, it is returned in retpage.  Otherwise, a page is allocated,
+ * added to the swap cache, and returned in retpage.
+ *
+ * If success, the swap cache page is returned in retpage
+ * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
+ * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
+ *     the new page is added to swapcache and locked
+ * Returns ZSWAP_SWAPCACHE_FAIL on error
+ */
+static int zswap_get_swap_cache_page(swp_entry_t entry,
+				struct page **retpage)
+{
+	bool page_was_allocated;
+
+	*retpage = __read_swap_cache_async(entry, GFP_KERNEL,
+			NULL, 0, &page_was_allocated);
+	if (page_was_allocated)
+		return ZSWAP_SWAPCACHE_NEW;
+	if (!*retpage)
+		return ZSWAP_SWAPCACHE_FAIL;
+	return ZSWAP_SWAPCACHE_EXIST;
+}
+
+/*
+ * Attempts to free an entry by adding a page to the swap cache,
+ * decompressing the entry data into the page, and issuing a
+ * bio write to write the page back to the swap device.
+ *
+ * This can be thought of as a "resumed writeback" of the page
+ * to the swap device.  We are basically resuming the same swap
+ * writeback path that was intercepted with the frontswap_store()
+ * in the first place.  After the page has been decompressed into
+ * the swap cache, the compressed version stored by zswap can be
+ * freed.
+ */
+static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
+{
+	struct zswap_header *zhdr;
+	swp_entry_t swpentry;
+	struct zswap_tree *tree;
+	pgoff_t offset;
+	struct zswap_entry *entry;
+	struct page *page;
+	struct crypto_comp *tfm;
+	u8 *src, *dst;
+	unsigned int dlen;
+	int ret;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_NONE,
+	};
+
+	/* extract swpentry from data */
+	zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
+	swpentry = zhdr->swpentry; /* here */
+	zpool_unmap_handle(pool, handle);
+	tree = zswap_trees[swp_type(swpentry)];
+	offset = swp_offset(swpentry);
+
+	/* find and ref zswap entry */
+	spin_lock(&tree->lock);
+	entry = zswap_entry_find_get(&tree->rbroot, offset);
+	if (!entry) {
+		/* entry was invalidated */
+		spin_unlock(&tree->lock);
+		return 0;
+	}
+	spin_unlock(&tree->lock);
+	BUG_ON(offset != entry->offset);
+
+	/* try to allocate swap cache page */
+	switch (zswap_get_swap_cache_page(swpentry, &page)) {
+	case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
+		ret = -ENOMEM;
+		goto fail;
+
+	case ZSWAP_SWAPCACHE_EXIST:
+		/* page is already in the swap cache, ignore for now */
+		page_cache_release(page);
+		ret = -EEXIST;
+		goto fail;
+
+	case ZSWAP_SWAPCACHE_NEW: /* page is locked */
+		/* decompress */
+		dlen = PAGE_SIZE;
+		src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
+				ZPOOL_MM_RO) + sizeof(struct zswap_header);
+		dst = kmap_atomic(page);
+		tfm = *get_cpu_ptr(entry->pool->tfm);
+		ret = crypto_comp_decompress(tfm, src, entry->length,
+					     dst, &dlen);
+		put_cpu_ptr(entry->pool->tfm);
+		kunmap_atomic(dst);
+		zpool_unmap_handle(entry->pool->zpool, entry->handle);
+		BUG_ON(ret);
+		BUG_ON(dlen != PAGE_SIZE);
+
+		/* page is up to date */
+		SetPageUptodate(page);
+	}
+
+	/* move it to the tail of the inactive list after end_writeback */
+	SetPageReclaim(page);
+
+	/* start writeback */
+	__swap_writepage(page, &wbc, end_swap_bio_write);
+	page_cache_release(page);
+	zswap_written_back_pages++;
+
+	spin_lock(&tree->lock);
+	/* drop local reference */
+	zswap_entry_put(tree, entry);
+
+	/*
+	* There are two possible situations for entry here:
+	* (1) refcount is 1(normal case),  entry is valid and on the tree
+	* (2) refcount is 0, entry is freed and not on the tree
+	*     because invalidate happened during writeback
+	*  search the tree and free the entry if find entry
+	*/
+	if (entry == zswap_rb_search(&tree->rbroot, offset))
+		zswap_entry_put(tree, entry);
+	spin_unlock(&tree->lock);
+
+	goto end;
+
+	/*
+	* if we get here due to ZSWAP_SWAPCACHE_EXIST
+	* a load may happening concurrently
+	* it is safe and okay to not free the entry
+	* if we free the entry in the following put
+	* it it either okay to return !0
+	*/
+fail:
+	spin_lock(&tree->lock);
+	zswap_entry_put(tree, entry);
+	spin_unlock(&tree->lock);
+
+end:
+	return ret;
+}
+
+static int zswap_shrink(void)
+{
+	struct zswap_pool *pool;
+	int ret;
+
+	pool = zswap_pool_last_get();
+	if (!pool)
+		return -ENOENT;
+
+	ret = zpool_shrink(pool->zpool, 1, NULL);
+
+	zswap_pool_put(pool);
+
+	return ret;
+}
+
+/*********************************
+* frontswap hooks
+**********************************/
+/* attempts to compress and store an single page */
+static int zswap_frontswap_store(unsigned type, pgoff_t offset,
+				struct page *page)
+{
+	struct zswap_tree *tree = zswap_trees[type];
+	struct zswap_entry *entry, *dupentry;
+	struct crypto_comp *tfm;
+	int ret;
+	unsigned int dlen = PAGE_SIZE, len;
+	unsigned long handle;
+	char *buf;
+	u8 *src, *dst;
+	struct zswap_header *zhdr;
+
+	if (!zswap_enabled || !tree) {
+		ret = -ENODEV;
+		goto reject;
+	}
+
+	/* reclaim space if needed */
+	if (zswap_is_full()) {
+		zswap_pool_limit_hit++;
+		if (zswap_shrink()) {
+			zswap_reject_reclaim_fail++;
+			ret = -ENOMEM;
+			goto reject;
+		}
+	}
+
+	/* allocate entry */
+	entry = zswap_entry_cache_alloc(GFP_KERNEL);
+	if (!entry) {
+		zswap_reject_kmemcache_fail++;
+		ret = -ENOMEM;
+		goto reject;
+	}
+
+	/* if entry is successfully added, it keeps the reference */
+	entry->pool = zswap_pool_current_get();
+	if (!entry->pool) {
+		ret = -EINVAL;
+		goto freepage;
+	}
+
+	/* compress */
+	dst = get_cpu_var(zswap_dstmem);
+	tfm = *get_cpu_ptr(entry->pool->tfm);
+	src = kmap_atomic(page);
+	ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
+	kunmap_atomic(src);
+	put_cpu_ptr(entry->pool->tfm);
+	if (ret) {
+		ret = -EINVAL;
+		goto put_dstmem;
+	}
+
+	/* store */
+	len = dlen + sizeof(struct zswap_header);
+	ret = zpool_malloc(entry->pool->zpool, len,
+			   __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM,
+			   &handle);
+	if (ret == -ENOSPC) {
+		zswap_reject_compress_poor++;
+		goto put_dstmem;
+	}
+	if (ret) {
+		zswap_reject_alloc_fail++;
+		goto put_dstmem;
+	}
+	zhdr = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW);
+	zhdr->swpentry = swp_entry(type, offset);
+	buf = (u8 *)(zhdr + 1);
+	memcpy(buf, dst, dlen);
+	zpool_unmap_handle(entry->pool->zpool, handle);
+	put_cpu_var(zswap_dstmem);
+
+	/* populate entry */
+	entry->offset = offset;
+	entry->handle = handle;
+	entry->length = dlen;
+
+	/* map */
+	spin_lock(&tree->lock);
+	do {
+		ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
+		if (ret == -EEXIST) {
+			zswap_duplicate_entry++;
+			/* remove from rbtree */
+			zswap_rb_erase(&tree->rbroot, dupentry);
+			zswap_entry_put(tree, dupentry);
+		}
+	} while (ret == -EEXIST);
+	spin_unlock(&tree->lock);
+
+	/* update stats */
+	atomic_inc(&zswap_stored_pages);
+	zswap_update_total_size();
+
+	return 0;
+
+put_dstmem:
+	put_cpu_var(zswap_dstmem);
+	zswap_pool_put(entry->pool);
+freepage:
+	zswap_entry_cache_free(entry);
+reject:
+	return ret;
+}
+
+/*
+ * returns 0 if the page was successfully decompressed
+ * return -1 on entry not found or error
+*/
+static int zswap_frontswap_load(unsigned type, pgoff_t offset,
+				struct page *page)
+{
+	struct zswap_tree *tree = zswap_trees[type];
+	struct zswap_entry *entry;
+	struct crypto_comp *tfm;
+	u8 *src, *dst;
+	unsigned int dlen;
+	int ret;
+
+	/* find */
+	spin_lock(&tree->lock);
+	entry = zswap_entry_find_get(&tree->rbroot, offset);
+	if (!entry) {
+		/* entry was written back */
+		spin_unlock(&tree->lock);
+		return -1;
+	}
+	spin_unlock(&tree->lock);
+
+	/* decompress */
+	dlen = PAGE_SIZE;
+	src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
+			ZPOOL_MM_RO) + sizeof(struct zswap_header);
+	dst = kmap_atomic(page);
+	tfm = *get_cpu_ptr(entry->pool->tfm);
+	ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
+	put_cpu_ptr(entry->pool->tfm);
+	kunmap_atomic(dst);
+	zpool_unmap_handle(entry->pool->zpool, entry->handle);
+	BUG_ON(ret);
+
+	spin_lock(&tree->lock);
+	zswap_entry_put(tree, entry);
+	spin_unlock(&tree->lock);
+
+	return 0;
+}
+
+/* frees an entry in zswap */
+static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
+{
+	struct zswap_tree *tree = zswap_trees[type];
+	struct zswap_entry *entry;
+
+	/* find */
+	spin_lock(&tree->lock);
+	entry = zswap_rb_search(&tree->rbroot, offset);
+	if (!entry) {
+		/* entry was written back */
+		spin_unlock(&tree->lock);
+		return;
+	}
+
+	/* remove from rbtree */
+	zswap_rb_erase(&tree->rbroot, entry);
+
+	/* drop the initial reference from entry creation */
+	zswap_entry_put(tree, entry);
+
+	spin_unlock(&tree->lock);
+}
+
+/* frees all zswap entries for the given swap type */
+static void zswap_frontswap_invalidate_area(unsigned type)
+{
+	struct zswap_tree *tree = zswap_trees[type];
+	struct zswap_entry *entry, *n;
+
+	if (!tree)
+		return;
+
+	/* walk the tree and free everything */
+	spin_lock(&tree->lock);
+	rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
+		zswap_free_entry(entry);
+	tree->rbroot = RB_ROOT;
+	spin_unlock(&tree->lock);
+	kfree(tree);
+	zswap_trees[type] = NULL;
+}
+
+static void zswap_frontswap_init(unsigned type)
+{
+	struct zswap_tree *tree;
+
+	tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
+	if (!tree) {
+		pr_err("alloc failed, zswap disabled for swap type %d\n", type);
+		return;
+	}
+
+	tree->rbroot = RB_ROOT;
+	spin_lock_init(&tree->lock);
+	zswap_trees[type] = tree;
+}
+
+static struct frontswap_ops zswap_frontswap_ops = {
+	.store = zswap_frontswap_store,
+	.load = zswap_frontswap_load,
+	.invalidate_page = zswap_frontswap_invalidate_page,
+	.invalidate_area = zswap_frontswap_invalidate_area,
+	.init = zswap_frontswap_init
+};
+
+/*********************************
+* debugfs functions
+**********************************/
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+
+static struct dentry *zswap_debugfs_root;
+
+static int __init zswap_debugfs_init(void)
+{
+	if (!debugfs_initialized())
+		return -ENODEV;
+
+	zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
+	if (!zswap_debugfs_root)
+		return -ENOMEM;
+
+	debugfs_create_u64("pool_limit_hit", S_IRUGO,
+			zswap_debugfs_root, &zswap_pool_limit_hit);
+	debugfs_create_u64("reject_reclaim_fail", S_IRUGO,
+			zswap_debugfs_root, &zswap_reject_reclaim_fail);
+	debugfs_create_u64("reject_alloc_fail", S_IRUGO,
+			zswap_debugfs_root, &zswap_reject_alloc_fail);
+	debugfs_create_u64("reject_kmemcache_fail", S_IRUGO,
+			zswap_debugfs_root, &zswap_reject_kmemcache_fail);
+	debugfs_create_u64("reject_compress_poor", S_IRUGO,
+			zswap_debugfs_root, &zswap_reject_compress_poor);
+	debugfs_create_u64("written_back_pages", S_IRUGO,
+			zswap_debugfs_root, &zswap_written_back_pages);
+	debugfs_create_u64("duplicate_entry", S_IRUGO,
+			zswap_debugfs_root, &zswap_duplicate_entry);
+	debugfs_create_u64("pool_total_size", S_IRUGO,
+			zswap_debugfs_root, &zswap_pool_total_size);
+	debugfs_create_atomic_t("stored_pages", S_IRUGO,
+			zswap_debugfs_root, &zswap_stored_pages);
+
+	return 0;
+}
+
+static void __exit zswap_debugfs_exit(void)
+{
+	debugfs_remove_recursive(zswap_debugfs_root);
+}
+#else
+static int __init zswap_debugfs_init(void)
+{
+	return 0;
+}
+
+static void __exit zswap_debugfs_exit(void) { }
+#endif
+
+/*********************************
+* module init and exit
+**********************************/
+static int __init init_zswap(void)
+{
+	struct zswap_pool *pool;
+
+	zswap_init_started = true;
+
+	if (zswap_entry_cache_create()) {
+		pr_err("entry cache creation failed\n");
+		goto cache_fail;
+	}
+
+	if (zswap_cpu_dstmem_init()) {
+		pr_err("dstmem alloc failed\n");
+		goto dstmem_fail;
+	}
+
+	pool = __zswap_pool_create_fallback();
+	if (!pool) {
+		pr_err("pool creation failed\n");
+		goto pool_fail;
+	}
+	pr_info("loaded using pool %s/%s\n", pool->tfm_name,
+		zpool_get_type(pool->zpool));
+
+	list_add(&pool->list, &zswap_pools);
+
+	frontswap_register_ops(&zswap_frontswap_ops);
+	if (zswap_debugfs_init())
+		pr_warn("debugfs initialization failed\n");
+	return 0;
+
+pool_fail:
+	zswap_cpu_dstmem_destroy();
+dstmem_fail:
+	zswap_entry_cache_destroy();
+cache_fail:
+	/* if built-in, we aren't unloaded on failure; don't allow use */
+	zswap_init_failed = true;
+	zswap_enabled = false;
+	return -ENOMEM;
+}
+/* must be late so crypto has time to come up */
+late_initcall(init_zswap);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
+MODULE_DESCRIPTION("Compressed cache for swap pages");