#ifndef _LINUX_MM_H
  #define _LINUX_MM_H

  #include <linux/errno.h>
  
  #ifdef __KERNEL__

  #include <linux/gfp.h>
  #include <linux/list.h>
  #include <linux/mmzone.h>
  #include <linux/rbtree.h>
  #include <linux/prio_tree.h>

  #include <linux/debug_locks.h>

  #include <linux/mm_types.h>

  #include <linux/range.h>

  #include <linux/pfn.h>

  
  struct mempolicy;
  struct anon_vma;

  struct file_ra_state;

  struct user_struct;

  struct writeback_control;

  
  #ifndef CONFIG_DISCONTIGMEM          /* Don't use mapnrs, do it properly */
  extern unsigned long max_mapnr;
  #endif
  
  extern unsigned long num_physpages;

  extern unsigned long totalram_pages;

  extern void * high_memory;

  extern int page_cluster;
  
  #ifdef CONFIG_SYSCTL
  extern int sysctl_legacy_va_layout;
  #else
  #define sysctl_legacy_va_layout 0
  #endif
  
  #include <asm/page.h>
  #include <asm/pgtable.h>
  #include <asm/processor.h>

  #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))

  /* to align the pointer to the (next) page boundary */
  #define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)

  /*
   * Linux kernel virtual memory manager primitives.
   * The idea being to have a "virtual" mm in the same way
   * we have a virtual fs - giving a cleaner interface to the
   * mm details, and allowing different kinds of memory mappings
   * (from shared memory to executable loading to arbitrary
   * mmap() functions).
   */

  extern struct kmem_cache *vm_area_cachep;

  #ifndef CONFIG_MMU

  extern struct rb_root nommu_region_tree;
  extern struct rw_semaphore nommu_region_sem;

  
  extern unsigned int kobjsize(const void *objp);
  #endif
  
  /*

   * vm_flags in vm_area_struct, see mm_types.h.

   */
  #define VM_READ		0x00000001	/* currently active flags */
  #define VM_WRITE	0x00000002
  #define VM_EXEC		0x00000004
  #define VM_SHARED	0x00000008

  /* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */

  #define VM_MAYREAD	0x00000010	/* limits for mprotect() etc */
  #define VM_MAYWRITE	0x00000020
  #define VM_MAYEXEC	0x00000040
  #define VM_MAYSHARE	0x00000080
  
  #define VM_GROWSDOWN	0x00000100	/* general info on the segment */
  #define VM_GROWSUP	0x00000200

  #define VM_PFNMAP	0x00000400	/* Page-ranges managed without "struct page", just pure PFN */

  #define VM_DENYWRITE	0x00000800	/* ETXTBSY on write attempts.. */
  
  #define VM_EXECUTABLE	0x00001000
  #define VM_LOCKED	0x00002000
  #define VM_IO           0x00004000	/* Memory mapped I/O or similar */
  
  					/* Used by sys_madvise() */
  #define VM_SEQ_READ	0x00008000	/* App will access data sequentially */
  #define VM_RAND_READ	0x00010000	/* App will not benefit from clustered reads */
  
  #define VM_DONTCOPY	0x00020000      /* Do not copy this vma on fork */
  #define VM_DONTEXPAND	0x00040000	/* Cannot expand with mremap() */

  #define VM_RESERVED	0x00080000	/* Count as reserved_vm like IO */

  #define VM_ACCOUNT	0x00100000	/* Is a VM accounted object */

  #define VM_NORESERVE	0x00200000	/* should the VM suppress accounting */

  #define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
  #define VM_NONLINEAR	0x00800000	/* Is non-linear (remap_file_pages) */
  #define VM_MAPPED_COPY	0x01000000	/* T if mapped copy of data (nommu mmap) */

  #define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */

  #define VM_ALWAYSDUMP	0x04000000	/* Always include in core dumps */

  #define VM_CAN_NONLINEAR 0x08000000	/* Has ->fault & does nonlinear pages */

  #define VM_MIXEDMAP	0x10000000	/* Can contain "struct page" and pure PFN pages */

  #define VM_SAO		0x20000000	/* Strong Access Ordering (powerpc) */

  #define VM_PFN_AT_MMAP	0x40000000	/* PFNMAP vma that is fully mapped at mmap time */

  #define VM_MERGEABLE	0x80000000	/* KSM may merge identical pages */

  /* Bits set in the VMA until the stack is in its final location */
  #define VM_STACK_INCOMPLETE_SETUP	(VM_RAND_READ | VM_SEQ_READ)

  #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
  #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
  #endif
  
  #ifdef CONFIG_STACK_GROWSUP
  #define VM_STACK_FLAGS	(VM_GROWSUP | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
  #else
  #define VM_STACK_FLAGS	(VM_GROWSDOWN | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
  #endif
  
  #define VM_READHINTMASK			(VM_SEQ_READ | VM_RAND_READ)
  #define VM_ClearReadHint(v)		(v)->vm_flags &= ~VM_READHINTMASK
  #define VM_NormalReadHint(v)		(!((v)->vm_flags & VM_READHINTMASK))
  #define VM_SequentialReadHint(v)	((v)->vm_flags & VM_SEQ_READ)
  #define VM_RandomReadHint(v)		((v)->vm_flags & VM_RAND_READ)
  
  /*

   * special vmas that are non-mergable, non-mlock()able
   */
  #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
  
  /*

   * mapping from the currently active vm_flags protection bits (the
   * low four bits) to a page protection mask..
   */
  extern pgprot_t protection_map[16];

  #define FAULT_FLAG_WRITE	0x01	/* Fault was a write access */
  #define FAULT_FLAG_NONLINEAR	0x02	/* Fault was via a nonlinear mapping */

  #define FAULT_FLAG_MKWRITE	0x04	/* Fault was mkwrite of existing pte */

  /*
   * This interface is used by x86 PAT code to identify a pfn mapping that is
   * linear over entire vma. This is to optimize PAT code that deals with
   * marking the physical region with a particular prot. This is not for generic
   * mm use. Note also that this check will not work if the pfn mapping is
   * linear for a vma starting at physical address 0. In which case PAT code
   * falls back to slow path of reserving physical range page by page.
   */

  static inline int is_linear_pfn_mapping(struct vm_area_struct *vma)
  {

  	return (vma->vm_flags & VM_PFN_AT_MMAP);

  }
  
  static inline int is_pfn_mapping(struct vm_area_struct *vma)
  {
  	return (vma->vm_flags & VM_PFNMAP);
  }

  /*

   * vm_fault is filled by the the pagefault handler and passed to the vma's

   * ->fault function. The vma's ->fault is responsible for returning a bitmask
   * of VM_FAULT_xxx flags that give details about how the fault was handled.

   *

   * pgoff should be used in favour of virtual_address, if possible. If pgoff
   * is used, one may set VM_CAN_NONLINEAR in the vma->vm_flags to get nonlinear
   * mapping support.

   */

  struct vm_fault {
  	unsigned int flags;		/* FAULT_FLAG_xxx flags */
  	pgoff_t pgoff;			/* Logical page offset based on vma */
  	void __user *virtual_address;	/* Faulting virtual address */
  
  	struct page *page;		/* ->fault handlers should return a

  					 * page here, unless VM_FAULT_NOPAGE

  					 * is set (which is also implied by

  					 * VM_FAULT_ERROR).

  					 */

  };

  
  /*
   * These are the virtual MM functions - opening of an area, closing and
   * unmapping it (needed to keep files on disk up-to-date etc), pointer
   * to the functions called when a no-page or a wp-page exception occurs. 
   */
  struct vm_operations_struct {
  	void (*open)(struct vm_area_struct * area);
  	void (*close)(struct vm_area_struct * area);

  	int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);

  
  	/* notification that a previously read-only page is about to become
  	 * writable, if an error is returned it will cause a SIGBUS */

  	int (*page_mkwrite)(struct vm_area_struct *vma, struct vm_fault *vmf);

  
  	/* called by access_process_vm when get_user_pages() fails, typically
  	 * for use by special VMAs that can switch between memory and hardware
  	 */
  	int (*access)(struct vm_area_struct *vma, unsigned long addr,
  		      void *buf, int len, int write);

  #ifdef CONFIG_NUMA

  	/*
  	 * set_policy() op must add a reference to any non-NULL @new mempolicy
  	 * to hold the policy upon return.  Caller should pass NULL @new to
  	 * remove a policy and fall back to surrounding context--i.e. do not
  	 * install a MPOL_DEFAULT policy, nor the task or system default
  	 * mempolicy.
  	 */

  	int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);

  
  	/*
  	 * get_policy() op must add reference [mpol_get()] to any policy at
  	 * (vma,addr) marked as MPOL_SHARED.  The shared policy infrastructure
  	 * in mm/mempolicy.c will do this automatically.
  	 * get_policy() must NOT add a ref if the policy at (vma,addr) is not
  	 * marked as MPOL_SHARED. vma policies are protected by the mmap_sem.
  	 * If no [shared/vma] mempolicy exists at the addr, get_policy() op
  	 * must return NULL--i.e., do not "fallback" to task or system default
  	 * policy.
  	 */

  	struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
  					unsigned long addr);

  	int (*migrate)(struct vm_area_struct *vma, const nodemask_t *from,
  		const nodemask_t *to, unsigned long flags);

  #endif
  };
  
  struct mmu_gather;
  struct inode;

  #define page_private(page)		((page)->private)
  #define set_page_private(page, v)	((page)->private = (v))

  /*
   * FIXME: take this include out, include page-flags.h in
   * files which need it (119 of them)
   */
  #include <linux/page-flags.h>
  
  /*
   * Methods to modify the page usage count.
   *
   * What counts for a page usage:
   * - cache mapping   (page->mapping)
   * - private data    (page->private)
   * - page mapped in a task's page tables, each mapping
   *   is counted separately
   *
   * Also, many kernel routines increase the page count before a critical
   * routine so they can be sure the page doesn't go away from under them.

   */
  
  /*

   * Drop a ref, return true if the refcount fell to zero (the page has no users)

   */

  static inline int put_page_testzero(struct page *page)
  {

  	VM_BUG_ON(atomic_read(&page->_count) == 0);

  	return atomic_dec_and_test(&page->_count);

  }

  
  /*

   * Try to grab a ref unless the page has a refcount of zero, return false if
   * that is the case.

   */

  static inline int get_page_unless_zero(struct page *page)
  {

  	return atomic_inc_not_zero(&page->_count);

  }

  extern int page_is_ram(unsigned long pfn);

  /* Support for virtually mapped pages */

  struct page *vmalloc_to_page(const void *addr);
  unsigned long vmalloc_to_pfn(const void *addr);

  /*
   * Determine if an address is within the vmalloc range
   *
   * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
   * is no special casing required.
   */

  static inline int is_vmalloc_addr(const void *x)
  {

  #ifdef CONFIG_MMU

  	unsigned long addr = (unsigned long)x;
  
  	return addr >= VMALLOC_START && addr < VMALLOC_END;

  #else
  	return 0;

  #endif

  }

  #ifdef CONFIG_MMU
  extern int is_vmalloc_or_module_addr(const void *x);
  #else

  static inline int is_vmalloc_or_module_addr(const void *x)

  {
  	return 0;
  }
  #endif

  static inline struct page *compound_head(struct page *page)
  {

  	if (unlikely(PageTail(page)))

  		return page->first_page;
  	return page;
  }

  static inline int page_count(struct page *page)

  {

  	return atomic_read(&compound_head(page)->_count);

  }
  
  static inline void get_page(struct page *page)
  {

  	page = compound_head(page);

  	VM_BUG_ON(atomic_read(&page->_count) == 0);

  	atomic_inc(&page->_count);
  }

  static inline struct page *virt_to_head_page(const void *x)
  {
  	struct page *page = virt_to_page(x);
  	return compound_head(page);
  }

  /*
   * Setup the page count before being freed into the page allocator for
   * the first time (boot or memory hotplug)
   */
  static inline void init_page_count(struct page *page)
  {
  	atomic_set(&page->_count, 1);
  }

  void put_page(struct page *page);

  void put_pages_list(struct list_head *pages);

  void split_page(struct page *page, unsigned int order);

  int split_free_page(struct page *page);

  /*

   * Compound pages have a destructor function.  Provide a
   * prototype for that function and accessor functions.
   * These are _only_ valid on the head of a PG_compound page.
   */
  typedef void compound_page_dtor(struct page *);
  
  static inline void set_compound_page_dtor(struct page *page,
  						compound_page_dtor *dtor)
  {
  	page[1].lru.next = (void *)dtor;
  }
  
  static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
  {
  	return (compound_page_dtor *)page[1].lru.next;
  }

  static inline int compound_order(struct page *page)
  {

  	if (!PageHead(page))

  		return 0;
  	return (unsigned long)page[1].lru.prev;
  }
  
  static inline void set_compound_order(struct page *page, unsigned long order)
  {
  	page[1].lru.prev = (void *)order;
  }

  /*

   * Multiple processes may "see" the same page. E.g. for untouched
   * mappings of /dev/null, all processes see the same page full of
   * zeroes, and text pages of executables and shared libraries have
   * only one copy in memory, at most, normally.
   *
   * For the non-reserved pages, page_count(page) denotes a reference count.

   *   page_count() == 0 means the page is free. page->lru is then used for
   *   freelist management in the buddy allocator.

   *   page_count() > 0  means the page has been allocated.

   *

   * Pages are allocated by the slab allocator in order to provide memory
   * to kmalloc and kmem_cache_alloc. In this case, the management of the
   * page, and the fields in 'struct page' are the responsibility of mm/slab.c
   * unless a particular usage is carefully commented. (the responsibility of
   * freeing the kmalloc memory is the caller's, of course).

   *

   * A page may be used by anyone else who does a __get_free_page().
   * In this case, page_count still tracks the references, and should only
   * be used through the normal accessor functions. The top bits of page->flags
   * and page->virtual store page management information, but all other fields
   * are unused and could be used privately, carefully. The management of this
   * page is the responsibility of the one who allocated it, and those who have
   * subsequently been given references to it.
   *
   * The other pages (we may call them "pagecache pages") are completely

   * managed by the Linux memory manager: I/O, buffers, swapping etc.
   * The following discussion applies only to them.
   *

   * A pagecache page contains an opaque `private' member, which belongs to the
   * page's address_space. Usually, this is the address of a circular list of
   * the page's disk buffers. PG_private must be set to tell the VM to call
   * into the filesystem to release these pages.

   *

   * A page may belong to an inode's memory mapping. In this case, page->mapping
   * is the pointer to the inode, and page->index is the file offset of the page,
   * in units of PAGE_CACHE_SIZE.

   *

   * If pagecache pages are not associated with an inode, they are said to be
   * anonymous pages. These may become associated with the swapcache, and in that
   * case PG_swapcache is set, and page->private is an offset into the swapcache.

   *

   * In either case (swapcache or inode backed), the pagecache itself holds one
   * reference to the page. Setting PG_private should also increment the
   * refcount. The each user mapping also has a reference to the page.

   *

   * The pagecache pages are stored in a per-mapping radix tree, which is
   * rooted at mapping->page_tree, and indexed by offset.
   * Where 2.4 and early 2.6 kernels kept dirty/clean pages in per-address_space
   * lists, we instead now tag pages as dirty/writeback in the radix tree.

   *

   * All pagecache pages may be subject to I/O:

   * - inode pages may need to be read from disk,
   * - inode pages which have been modified and are MAP_SHARED may need

   *   to be written back to the inode on disk,
   * - anonymous pages (including MAP_PRIVATE file mappings) which have been
   *   modified may need to be swapped out to swap space and (later) to be read
   *   back into memory.

   */
  
  /*
   * The zone field is never updated after free_area_init_core()
   * sets it, so none of the operations on it need to be atomic.

   */

  
  /*
   * page->flags layout:
   *
   * There are three possibilities for how page->flags get
   * laid out.  The first is for the normal case, without
   * sparsemem.  The second is for sparsemem when there is
   * plenty of space for node and section.  The last is when
   * we have run out of space and have to fall back to an
   * alternate (slower) way of determining the node.
   *

   * No sparsemem or sparsemem vmemmap: |       NODE     | ZONE | ... | FLAGS |
   * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS |
   * classic sparse no space for node:  | SECTION |     ZONE    | ... | FLAGS |

   */

  #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)

  #define SECTIONS_WIDTH		SECTIONS_SHIFT
  #else
  #define SECTIONS_WIDTH		0
  #endif
  
  #define ZONES_WIDTH		ZONES_SHIFT

  #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS

  #define NODES_WIDTH		NODES_SHIFT
  #else

  #ifdef CONFIG_SPARSEMEM_VMEMMAP
  #error "Vmemmap: No space for nodes field in page flags"
  #endif

  #define NODES_WIDTH		0
  #endif
  
  /* Page flags: | [SECTION] | [NODE] | ZONE | ... | FLAGS | */

  #define SECTIONS_PGOFF		((sizeof(unsigned long)*8) - SECTIONS_WIDTH)

  #define NODES_PGOFF		(SECTIONS_PGOFF - NODES_WIDTH)
  #define ZONES_PGOFF		(NODES_PGOFF - ZONES_WIDTH)
  
  /*
   * We are going to use the flags for the page to node mapping if its in
   * there.  This includes the case where there is no node, so it is implicit.
   */

  #if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
  #define NODE_NOT_IN_PAGE_FLAGS
  #endif

  
  #ifndef PFN_SECTION_SHIFT
  #define PFN_SECTION_SHIFT 0
  #endif

  
  /*
   * Define the bit shifts to access each section.  For non-existant
   * sections we define the shift as 0; that plus a 0 mask ensures
   * the compiler will optimise away reference to them.
   */

  #define SECTIONS_PGSHIFT	(SECTIONS_PGOFF * (SECTIONS_WIDTH != 0))
  #define NODES_PGSHIFT		(NODES_PGOFF * (NODES_WIDTH != 0))
  #define ZONES_PGSHIFT		(ZONES_PGOFF * (ZONES_WIDTH != 0))

  /* NODE:ZONE or SECTION:ZONE is used to ID a zone for the buddy allcator */
  #ifdef NODE_NOT_IN_PAGEFLAGS
  #define ZONEID_SHIFT		(SECTIONS_SHIFT + ZONES_SHIFT)

  #define ZONEID_PGOFF		((SECTIONS_PGOFF < ZONES_PGOFF)? \
  						SECTIONS_PGOFF : ZONES_PGOFF)

  #else

  #define ZONEID_SHIFT		(NODES_SHIFT + ZONES_SHIFT)

  #define ZONEID_PGOFF		((NODES_PGOFF < ZONES_PGOFF)? \
  						NODES_PGOFF : ZONES_PGOFF)

  #endif

  #define ZONEID_PGSHIFT		(ZONEID_PGOFF * (ZONEID_SHIFT != 0))

  #if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
  #error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS

  #endif

  #define ZONES_MASK		((1UL << ZONES_WIDTH) - 1)
  #define NODES_MASK		((1UL << NODES_WIDTH) - 1)
  #define SECTIONS_MASK		((1UL << SECTIONS_WIDTH) - 1)

  #define ZONEID_MASK		((1UL << ZONEID_SHIFT) - 1)

  static inline enum zone_type page_zonenum(struct page *page)

  {

  	return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;

  }

  /*
   * The identification function is only used by the buddy allocator for
   * determining if two pages could be buddies. We are not really
   * identifying a zone since we could be using a the section number
   * id if we have not node id available in page flags.
   * We guarantee only that it will return the same value for two
   * combinable pages in a zone.
   */

  static inline int page_zone_id(struct page *page)
  {

  	return (page->flags >> ZONEID_PGSHIFT) & ZONEID_MASK;

  }

  static inline int zone_to_nid(struct zone *zone)

  {

  #ifdef CONFIG_NUMA
  	return zone->node;
  #else
  	return 0;
  #endif

  }

  #ifdef NODE_NOT_IN_PAGE_FLAGS

  extern int page_to_nid(struct page *page);

  #else

  static inline int page_to_nid(struct page *page)

  {

  	return (page->flags >> NODES_PGSHIFT) & NODES_MASK;

  }

  #endif
  
  static inline struct zone *page_zone(struct page *page)
  {
  	return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];
  }

  #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)

  static inline unsigned long page_to_section(struct page *page)
  {
  	return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
  }

  #endif

  static inline void set_page_zone(struct page *page, enum zone_type zone)

  {
  	page->flags &= ~(ZONES_MASK << ZONES_PGSHIFT);
  	page->flags |= (zone & ZONES_MASK) << ZONES_PGSHIFT;
  }

  static inline void set_page_node(struct page *page, unsigned long node)
  {
  	page->flags &= ~(NODES_MASK << NODES_PGSHIFT);
  	page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;

  }

  static inline void set_page_section(struct page *page, unsigned long section)
  {
  	page->flags &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
  	page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
  }

  static inline void set_page_links(struct page *page, enum zone_type zone,

  	unsigned long node, unsigned long pfn)

  {

  	set_page_zone(page, zone);
  	set_page_node(page, node);

  	set_page_section(page, pfn_to_section_nr(pfn));

  }

  /*
   * Some inline functions in vmstat.h depend on page_zone()
   */
  #include <linux/vmstat.h>

  static __always_inline void *lowmem_page_address(struct page *page)

  {

  	return __va(PFN_PHYS(page_to_pfn(page)));

  }
  
  #if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
  #define HASHED_PAGE_VIRTUAL
  #endif
  
  #if defined(WANT_PAGE_VIRTUAL)
  #define page_address(page) ((page)->virtual)
  #define set_page_address(page, address)			\
  	do {						\
  		(page)->virtual = (address);		\
  	} while(0)
  #define page_address_init()  do { } while(0)
  #endif
  
  #if defined(HASHED_PAGE_VIRTUAL)
  void *page_address(struct page *page);
  void set_page_address(struct page *page, void *virtual);
  void page_address_init(void);
  #endif
  
  #if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
  #define page_address(page) lowmem_page_address(page)
  #define set_page_address(page, address)  do { } while(0)
  #define page_address_init()  do { } while(0)
  #endif
  
  /*
   * On an anonymous page mapped into a user virtual memory area,
   * page->mapping points to its anon_vma, not to a struct address_space;

   * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
   *
   * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
   * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
   * and then page->mapping points, not to an anon_vma, but to a private
   * structure which KSM associates with that merged page.  See ksm.h.
   *
   * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.

   *
   * Please note that, confusingly, "page_mapping" refers to the inode
   * address_space which maps the page from disk; whereas "page_mapped"
   * refers to user virtual address space into which the page is mapped.
   */
  #define PAGE_MAPPING_ANON	1

  #define PAGE_MAPPING_KSM	2
  #define PAGE_MAPPING_FLAGS	(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)

  
  extern struct address_space swapper_space;
  static inline struct address_space *page_mapping(struct page *page)
  {
  	struct address_space *mapping = page->mapping;

  	VM_BUG_ON(PageSlab(page));

  	if (unlikely(PageSwapCache(page)))
  		mapping = &swapper_space;

  	else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))

  		mapping = NULL;
  	return mapping;
  }

  /* Neutral page->mapping pointer to address_space or anon_vma or other */
  static inline void *page_rmapping(struct page *page)
  {
  	return (void *)((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
  }

  static inline int PageAnon(struct page *page)
  {
  	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
  }
  
  /*
   * Return the pagecache index of the passed page.  Regular pagecache pages
   * use ->index whereas swapcache pages use ->private
   */
  static inline pgoff_t page_index(struct page *page)
  {
  	if (unlikely(PageSwapCache(page)))

  		return page_private(page);

  	return page->index;
  }
  
  /*
   * The atomic page->_mapcount, like _count, starts from -1:
   * so that transitions both from it and to it can be tracked,
   * using atomic_inc_and_test and atomic_add_negative(-1).
   */
  static inline void reset_page_mapcount(struct page *page)
  {
  	atomic_set(&(page)->_mapcount, -1);
  }
  
  static inline int page_mapcount(struct page *page)
  {
  	return atomic_read(&(page)->_mapcount) + 1;
  }
  
  /*
   * Return true if this page is mapped into pagetables.
   */
  static inline int page_mapped(struct page *page)
  {
  	return atomic_read(&(page)->_mapcount) >= 0;
  }
  
  /*

   * Different kinds of faults, as returned by handle_mm_fault().
   * Used to decide whether a process gets delivered SIGBUS or
   * just gets major/minor fault counters bumped up.
   */

  #define VM_FAULT_MINOR	0 /* For backwards compat. Remove me quickly. */

  #define VM_FAULT_OOM	0x0001
  #define VM_FAULT_SIGBUS	0x0002
  #define VM_FAULT_MAJOR	0x0004
  #define VM_FAULT_WRITE	0x0008	/* Special case for get_user_pages */

  #define VM_FAULT_HWPOISON 0x0010	/* Hit poisoned page */

  #define VM_FAULT_NOPAGE	0x0100	/* ->fault installed the pte, not return page */
  #define VM_FAULT_LOCKED	0x0200	/* ->fault locked the returned page */

  #define VM_FAULT_ERROR	(VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON)

  /*
   * Can be called by the pagefault handler when it gets a VM_FAULT_OOM.
   */
  extern void pagefault_out_of_memory(void);

  #define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
  
  extern void show_free_areas(void);

  int shmem_lock(struct file *file, int lock, struct user_struct *user);

  struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags);

  int shmem_zero_setup(struct vm_area_struct *);

  #ifndef CONFIG_MMU
  extern unsigned long shmem_get_unmapped_area(struct file *file,
  					     unsigned long addr,
  					     unsigned long len,
  					     unsigned long pgoff,
  					     unsigned long flags);
  #endif

  extern int can_do_mlock(void);

  extern int user_shm_lock(size_t, struct user_struct *);
  extern void user_shm_unlock(size_t, struct user_struct *);
  
  /*
   * Parameter block passed down to zap_pte_range in exceptional cases.
   */
  struct zap_details {
  	struct vm_area_struct *nonlinear_vma;	/* Check page->index if set */
  	struct address_space *check_mapping;	/* Check page->mapping if set */
  	pgoff_t	first_index;			/* Lowest page->index to unmap */
  	pgoff_t last_index;			/* Highest page->index to unmap */
  	spinlock_t *i_mmap_lock;		/* For unmap_mapping_range: */

  	unsigned long truncate_count;		/* Compare vm_truncate_count */
  };

  struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
  		pte_t pte);

  int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
  		unsigned long size);

  unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,

  		unsigned long size, struct zap_details *);

  unsigned long unmap_vmas(struct mmu_gather **tlb,

  		struct vm_area_struct *start_vma, unsigned long start_addr,
  		unsigned long end_addr, unsigned long *nr_accounted,
  		struct zap_details *);

  
  /**
   * mm_walk - callbacks for walk_page_range
   * @pgd_entry: if set, called for each non-empty PGD (top-level) entry
   * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
   * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
   * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
   * @pte_hole: if set, called for each hole at all levels

   * @hugetlb_entry: if set, called for each hugetlb entry

   *
   * (see walk_page_range for more details)
   */
  struct mm_walk {

  	int (*pgd_entry)(pgd_t *, unsigned long, unsigned long, struct mm_walk *);
  	int (*pud_entry)(pud_t *, unsigned long, unsigned long, struct mm_walk *);
  	int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, struct mm_walk *);
  	int (*pte_entry)(pte_t *, unsigned long, unsigned long, struct mm_walk *);
  	int (*pte_hole)(unsigned long, unsigned long, struct mm_walk *);

  	int (*hugetlb_entry)(pte_t *, unsigned long,
  			     unsigned long, unsigned long, struct mm_walk *);

  	struct mm_struct *mm;
  	void *private;

  };

  int walk_page_range(unsigned long addr, unsigned long end,
  		struct mm_walk *walk);

  void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,

  		unsigned long end, unsigned long floor, unsigned long ceiling);

  int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
  			struct vm_area_struct *vma);

  void unmap_mapping_range(struct address_space *mapping,
  		loff_t const holebegin, loff_t const holelen, int even_cows);

  int follow_pfn(struct vm_area_struct *vma, unsigned long address,
  	unsigned long *pfn);

  int follow_phys(struct vm_area_struct *vma, unsigned long address,
  		unsigned int flags, unsigned long *prot, resource_size_t *phys);

  int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
  			void *buf, int len, int write);

  
  static inline void unmap_shared_mapping_range(struct address_space *mapping,
  		loff_t const holebegin, loff_t const holelen)
  {
  	unmap_mapping_range(mapping, holebegin, holelen, 0);
  }

  extern void truncate_pagecache(struct inode *inode, loff_t old, loff_t new);

  extern void truncate_setsize(struct inode *inode, loff_t newsize);

  extern int vmtruncate(struct inode *inode, loff_t offset);
  extern int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end);

  int truncate_inode_page(struct address_space *mapping, struct page *page);

  int generic_error_remove_page(struct address_space *mapping, struct page *page);

  int invalidate_inode_page(struct page *page);

  #ifdef CONFIG_MMU

  extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,

  			unsigned long address, unsigned int flags);

  #else
  static inline int handle_mm_fault(struct mm_struct *mm,
  			struct vm_area_struct *vma, unsigned long address,

  			unsigned int flags)

  {
  	/* should never happen if there's no MMU */
  	BUG();
  	return VM_FAULT_SIGBUS;
  }
  #endif

  extern int make_pages_present(unsigned long addr, unsigned long end);
  extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);

  int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,

  			unsigned long start, int nr_pages, int write, int force,

  			struct page **pages, struct vm_area_struct **vmas);
  int get_user_pages_fast(unsigned long start, int nr_pages, int write,
  			struct page **pages);

  struct page *get_dump_page(unsigned long addr);

  extern int try_to_release_page(struct page * page, gfp_t gfp_mask);
  extern void do_invalidatepage(struct page *page, unsigned long offset);

  int __set_page_dirty_nobuffers(struct page *page);

  int __set_page_dirty_no_writeback(struct page *page);

  int redirty_page_for_writepage(struct writeback_control *wbc,
  				struct page *page);

  void account_page_dirtied(struct page *page, struct address_space *mapping);

  int set_page_dirty(struct page *page);

  int set_page_dirty_lock(struct page *page);
  int clear_page_dirty_for_io(struct page *page);

  extern 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);

  extern unsigned long do_mremap(unsigned long addr,
  			       unsigned long old_len, unsigned long new_len,
  			       unsigned long flags, unsigned long new_addr);

  extern int mprotect_fixup(struct vm_area_struct *vma,
  			  struct vm_area_struct **pprev, unsigned long start,
  			  unsigned long end, unsigned long newflags);

  /*

   * doesn't attempt to fault and will return short.
   */
  int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
  			  struct page **pages);

  /*
   * per-process(per-mm_struct) statistics.
   */

  #if defined(SPLIT_RSS_COUNTING)

  /*
   * The mm counters are not protected by its page_table_lock,
   * so must be incremented atomically.
   */
  static inline void set_mm_counter(struct mm_struct *mm, int member, long value)
  {
  	atomic_long_set(&mm->rss_stat.count[member], value);
  }

  unsigned long get_mm_counter(struct mm_struct *mm, int member);

  
  static inline void add_mm_counter(struct mm_struct *mm, int member, long value)
  {
  	atomic_long_add(value, &mm->rss_stat.count[member]);
  }
  
  static inline void inc_mm_counter(struct mm_struct *mm, int member)
  {
  	atomic_long_inc(&mm->rss_stat.count[member]);
  }
  
  static inline void dec_mm_counter(struct mm_struct *mm, int member)
  {
  	atomic_long_dec(&mm->rss_stat.count[member]);
  }
  
  #else  /* !USE_SPLIT_PTLOCKS */
  /*
   * The mm counters are protected by its page_table_lock,
   * so can be incremented directly.
   */
  static inline void set_mm_counter(struct mm_struct *mm, int member, long value)
  {
  	mm->rss_stat.count[member] = value;
  }
  
  static inline unsigned long get_mm_counter(struct mm_struct *mm, int member)
  {
  	return mm->rss_stat.count[member];
  }
  
  static inline void add_mm_counter(struct mm_struct *mm, int member, long value)
  {
  	mm->rss_stat.count[member] += value;
  }
  
  static inline void inc_mm_counter(struct mm_struct *mm, int member)
  {
  	mm->rss_stat.count[member]++;
  }
  
  static inline void dec_mm_counter(struct mm_struct *mm, int member)
  {
  	mm->rss_stat.count[member]--;
  }
  
  #endif /* !USE_SPLIT_PTLOCKS */
  
  static inline unsigned long get_mm_rss(struct mm_struct *mm)
  {
  	return get_mm_counter(mm, MM_FILEPAGES) +
  		get_mm_counter(mm, MM_ANONPAGES);
  }
  
  static inline unsigned long get_mm_hiwater_rss(struct mm_struct *mm)
  {
  	return max(mm->hiwater_rss, get_mm_rss(mm));
  }
  
  static inline unsigned long get_mm_hiwater_vm(struct mm_struct *mm)
  {
  	return max(mm->hiwater_vm, mm->total_vm);
  }
  
  static inline void update_hiwater_rss(struct mm_struct *mm)
  {
  	unsigned long _rss = get_mm_rss(mm);
  
  	if ((mm)->hiwater_rss < _rss)
  		(mm)->hiwater_rss = _rss;
  }
  
  static inline void update_hiwater_vm(struct mm_struct *mm)
  {
  	if (mm->hiwater_vm < mm->total_vm)
  		mm->hiwater_vm = mm->total_vm;
  }
  
  static inline void setmax_mm_hiwater_rss(unsigned long *maxrss,
  					 struct mm_struct *mm)
  {
  	unsigned long hiwater_rss = get_mm_hiwater_rss(mm);
  
  	if (*maxrss < hiwater_rss)
  		*maxrss = hiwater_rss;
  }

  #if defined(SPLIT_RSS_COUNTING)

  void sync_mm_rss(struct task_struct *task, struct mm_struct *mm);

  #else
  static inline void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
  {
  }
  #endif

  
  /*

   * A callback you can register to apply pressure to ageable caches.

   *

   * 'shrink' is passed a count 'nr_to_scan' and a 'gfpmask'.  It should
   * look through the least-recently-used 'nr_to_scan' entries and
   * attempt to free them up.  It should return the number of objects
   * which remain in the cache.  If it returns -1, it means it cannot do
   * any scanning at this time (eg. there is a risk of deadlock).

   *

   * The 'gfpmask' refers to the allocation we are currently trying to
   * fulfil.
   *
   * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is
   * querying the cache size, so a fastpath for that case is appropriate.

   */

  struct shrinker {

  	int (*shrink)(struct shrinker *, int nr_to_scan, gfp_t gfp_mask);

  	int seeks;	/* seeks to recreate an obj */

  	/* These are for internal use */
  	struct list_head list;
  	long nr;	/* objs pending delete */
  };
  #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
  extern void register_shrinker(struct shrinker *);
  extern void unregister_shrinker(struct shrinker *);

  int vma_wants_writenotify(struct vm_area_struct *vma);

  extern pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl);

  #ifdef __PAGETABLE_PUD_FOLDED
  static inline int __pud_alloc(struct mm_struct *mm, pgd_t *pgd,
  						unsigned long address)
  {
  	return 0;
  }
  #else

  int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address);

  #endif
  
  #ifdef __PAGETABLE_PMD_FOLDED
  static inline int __pmd_alloc(struct mm_struct *mm, pud_t *pud,
  						unsigned long address)
  {
  	return 0;
  }
  #else

  int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address);

  #endif

  int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address);
  int __pte_alloc_kernel(pmd_t *pmd, unsigned long address);

  /*
   * The following ifdef needed to get the 4level-fixup.h header to work.
   * Remove it when 4level-fixup.h has been removed.
   */

  #if defined(CONFIG_MMU) && !defined(__ARCH_HAS_4LEVEL_HACK)

  static inline pud_t *pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
  {

  	return (unlikely(pgd_none(*pgd)) && __pud_alloc(mm, pgd, address))?
  		NULL: pud_offset(pgd, address);

  }
  
  static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
  {

  	return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?
  		NULL: pmd_offset(pud, address);

  }

  #endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */

  #if USE_SPLIT_PTLOCKS

  /*
   * We tuck a spinlock to guard each pagetable page into its struct page,
   * at page->private, with BUILD_BUG_ON to make sure that this will not
   * overflow into the next struct page (as it might with DEBUG_SPINLOCK).
   * When freeing, reset page->mapping so free_pages_check won't complain.
   */

  #define __pte_lockptr(page)	&((page)->ptl)

  #define pte_lock_init(_page)	do {					\
  	spin_lock_init(__pte_lockptr(_page));				\
  } while (0)
  #define pte_lock_deinit(page)	((page)->mapping = NULL)
  #define pte_lockptr(mm, pmd)	({(void)(mm); __pte_lockptr(pmd_page(*(pmd)));})

  #else	/* !USE_SPLIT_PTLOCKS */

  /*
   * We use mm->page_table_lock to guard all pagetable pages of the mm.
   */
  #define pte_lock_init(page)	do {} while (0)
  #define pte_lock_deinit(page)	do {} while (0)
  #define pte_lockptr(mm, pmd)	({(void)(pmd); &(mm)->page_table_lock;})

  #endif /* USE_SPLIT_PTLOCKS */

  static inline void pgtable_page_ctor(struct page *page)
  {
  	pte_lock_init(page);
  	inc_zone_page_state(page, NR_PAGETABLE);
  }
  
  static inline void pgtable_page_dtor(struct page *page)
  {
  	pte_lock_deinit(page);
  	dec_zone_page_state(page, NR_PAGETABLE);
  }

  #define pte_offset_map_lock(mm, pmd, address, ptlp)	\
  ({							\

  	spinlock_t *__ptl = pte_lockptr(mm, pmd);	\

  	pte_t *__pte = pte_offset_map(pmd, address);	\
  	*(ptlp) = __ptl;				\
  	spin_lock(__ptl);				\
  	__pte;						\
  })
  
  #define pte_unmap_unlock(pte, ptl)	do {		\
  	spin_unlock(ptl);				\
  	pte_unmap(pte);					\
  } while (0)

  #define pte_alloc_map(mm, pmd, address)			\
  	((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, pmd, address))? \
  		NULL: pte_offset_map(pmd, address))

  #define pte_alloc_map_lock(mm, pmd, address, ptlp)	\
  	((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, pmd, address))? \
  		NULL: pte_offset_map_lock(mm, pmd, address, ptlp))

  #define pte_alloc_kernel(pmd, address)			\
  	((unlikely(!pmd_present(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
  		NULL: pte_offset_kernel(pmd, address))

  
  extern void free_area_init(unsigned long * zones_size);

  extern void free_area_init_node(int nid, unsigned long * zones_size,
  		unsigned long zone_start_pfn, unsigned long *zholes_size);

  #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
   * With CONFIG_ARCH_POPULATES_NODE_MAP set, an architecture may initialise its
   * zones, allocate the backing mem_map and account for memory holes in a more
   * architecture independent manner. This is a substitute for creating the
   * zone_sizes[] and zholes_size[] arrays and passing them to
   * free_area_init_node()
   *
   * An architecture is expected to register range of page frames backed by
   * physical memory with add_active_range() before calling
   * free_area_init_nodes() passing in the PFN each zone ends at. At a basic
   * usage, an architecture is expected to do something like
   *
   * unsigned long max_zone_pfns[MAX_NR_ZONES] = {max_dma, max_normal_pfn,
   * 							 max_highmem_pfn};
   * for_each_valid_physical_page_range()
   * 	add_active_range(node_id, start_pfn, end_pfn)
   * free_area_init_nodes(max_zone_pfns);
   *
   * If the architecture guarantees that there are no holes in the ranges
   * registered with add_active_range(), free_bootmem_active_regions()
   * will call free_bootmem_node() for each registered physical page range.
   * Similarly sparse_memory_present_with_active_regions() calls
   * memory_present() for each range when SPARSEMEM is enabled.
   *
   * See mm/page_alloc.c for more information on each function exposed by
   * CONFIG_ARCH_POPULATES_NODE_MAP
   */
  extern void free_area_init_nodes(unsigned long *max_zone_pfn);
  extern void add_active_range(unsigned int nid, unsigned long start_pfn,
  					unsigned long end_pfn);

  extern void remove_active_range(unsigned int nid, unsigned long start_pfn,
  					unsigned long end_pfn);

  extern void remove_all_active_ranges(void);

  void sort_node_map(void);
  unsigned long __absent_pages_in_range(int nid, unsigned long start_pfn,
  						unsigned long end_pfn);

  extern unsigned long absent_pages_in_range(unsigned long start_pfn,
  						unsigned long end_pfn);
  extern void get_pfn_range_for_nid(unsigned int nid,
  			unsigned long *start_pfn, unsigned long *end_pfn);
  extern unsigned long find_min_pfn_with_active_regions(void);

  extern void free_bootmem_with_active_regions(int nid,
  						unsigned long max_low_pfn);

  int add_from_early_node_map(struct range *range, int az,
  				   int nr_range, int nid);
  void *__alloc_memory_core_early(int nodeid, u64 size, u64 align,
  				 u64 goal, u64 limit);

  typedef int (*work_fn_t)(unsigned long, unsigned long, void *);

  extern void work_with_active_regions(int nid, work_fn_t work_fn, void *data);

  extern void sparse_memory_present_with_active_regions(int nid);

  #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */

  
  #if !defined(CONFIG_ARCH_POPULATES_NODE_MAP) && \
      !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID)
  static inline int __early_pfn_to_nid(unsigned long pfn)
  {
  	return 0;
  }
  #else
  /* please see mm/page_alloc.c */
  extern int __meminit early_pfn_to_nid(unsigned long pfn);
  #ifdef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
  /* there is a per-arch backend function. */
  extern int __meminit __early_pfn_to_nid(unsigned long pfn);
  #endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */
  #endif

  extern void set_dma_reserve(unsigned long new_dma_reserve);

  extern void memmap_init_zone(unsigned long, int, unsigned long,
  				unsigned long, enum memmap_context);

  extern void setup_per_zone_wmarks(void);

  extern void calculate_zone_inactive_ratio(struct zone *zone);

  extern void mem_init(void);

  extern void __init mmap_init(void);

  extern void show_mem(void);
  extern void si_meminfo(struct sysinfo * val);
  extern void si_meminfo_node(struct sysinfo *val, int nid);

  extern int after_bootmem;

  extern void setup_per_cpu_pageset(void);

  extern void zone_pcp_update(struct zone *zone);

  /* nommu.c */

  extern atomic_long_t mmap_pages_allocated;

  extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);

  /* prio_tree.c */
  void vma_prio_tree_add(struct vm_area_struct *, struct vm_area_struct *old);
  void vma_prio_tree_insert(struct vm_area_struct *, struct prio_tree_root *);
  void vma_prio_tree_remove(struct vm_area_struct *, struct prio_tree_root *);
  struct vm_area_struct *vma_prio_tree_next(struct vm_area_struct *vma,
  	struct prio_tree_iter *iter);
  
  #define vma_prio_tree_foreach(vma, iter, root, begin, end)	\
  	for (prio_tree_iter_init(iter, root, begin, end), vma = NULL;	\
  		(vma = vma_prio_tree_next(vma, iter)); )
  
  static inline void vma_nonlinear_insert(struct vm_area_struct *vma,
  					struct list_head *list)
  {
  	vma->shared.vm_set.parent = NULL;
  	list_add_tail(&vma->shared.vm_set.list, list);
  }
  
  /* mmap.c */

  extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);

  extern int vma_adjust(struct vm_area_struct *vma, unsigned long start,

  	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert);
  extern struct vm_area_struct *vma_merge(struct mm_struct *,
  	struct vm_area_struct *prev, unsigned long addr, unsigned long end,
  	unsigned long vm_flags, struct anon_vma *, struct file *, pgoff_t,
  	struct mempolicy *);
  extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
  extern int split_vma(struct mm_struct *,
  	struct vm_area_struct *, unsigned long addr, int new_below);
  extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
  extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *,
  	struct rb_node **, struct rb_node *);

  extern void unlink_file_vma(struct vm_area_struct *);

  extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
  	unsigned long addr, unsigned long len, pgoff_t pgoff);
  extern void exit_mmap(struct mm_struct *);

  extern int mm_take_all_locks(struct mm_struct *mm);
  extern void mm_drop_all_locks(struct mm_struct *mm);

  #ifdef CONFIG_PROC_FS
  /* From fs/proc/base.c. callers must _not_ hold the mm's exe_file_lock */
  extern void added_exe_file_vma(struct mm_struct *mm);
  extern void removed_exe_file_vma(struct mm_struct *mm);
  #else
  static inline void added_exe_file_vma(struct mm_struct *mm)
  {}
  
  static inline void removed_exe_file_vma(struct mm_struct *mm)
  {}
  #endif /* CONFIG_PROC_FS */

  extern int may_expand_vm(struct mm_struct *mm, unsigned long npages);

  extern int install_special_mapping(struct mm_struct *mm,
  				   unsigned long addr, unsigned long len,
  				   unsigned long flags, struct page **pages);

  
  extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
  
  extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
  	unsigned long len, unsigned long prot,
  	unsigned long flag, unsigned long pgoff);

  extern unsigned long mmap_region(struct file *file, unsigned long addr,
  	unsigned long len, unsigned long flags,

  	unsigned int vm_flags, unsigned long pgoff);

  
  static inline unsigned long do_mmap(struct file *file, unsigned long addr,
  	unsigned long len, unsigned long prot,
  	unsigned long flag, unsigned long offset)
  {
  	unsigned long ret = -EINVAL;
  	if ((offset + PAGE_ALIGN(len)) < offset)
  		goto out;
  	if (!(offset & ~PAGE_MASK))
  		ret = do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
  out:
  	return ret;
  }
  
  extern int do_munmap(struct mm_struct *, unsigned long, size_t);
  
  extern unsigned long do_brk(unsigned long, unsigned long);
  
  /* filemap.c */
  extern unsigned long page_unuse(struct page *);
  extern void truncate_inode_pages(struct address_space *, loff_t);

  extern void truncate_inode_pages_range(struct address_space *,
  				       loff_t lstart, loff_t lend);

  
  /* generic vm_area_ops exported for stackable file systems */

  extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);

  
  /* mm/page-writeback.c */
  int write_one_page(struct page *page, int wait);

  void task_dirty_inc(struct task_struct *tsk);

  
  /* readahead.c */
  #define VM_MAX_READAHEAD	128	/* kbytes */
  #define VM_MIN_READAHEAD	16	/* kbytes (includes current page) */

  int force_page_cache_readahead(struct address_space *mapping, struct file *filp,

  			pgoff_t offset, unsigned long nr_to_read);

  
  void page_cache_sync_readahead(struct address_space *mapping,
  			       struct file_ra_state *ra,
  			       struct file *filp,
  			       pgoff_t offset,
  			       unsigned long size);
  
  void page_cache_async_readahead(struct address_space *mapping,
  				struct file_ra_state *ra,
  				struct file *filp,
  				struct page *pg,
  				pgoff_t offset,
  				unsigned long size);

  unsigned long max_sane_readahead(unsigned long nr);

  unsigned long ra_submit(struct file_ra_state *ra,
  			struct address_space *mapping,
  			struct file *filp);

  
  /* Do stack extension */

  extern int expand_stack(struct vm_area_struct *vma, unsigned long address);

  #ifdef CONFIG_IA64

  extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);

  #endif

  extern int expand_stack_downwards(struct vm_area_struct *vma,
  				  unsigned long address);

  
  /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
  extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);
  extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
  					     struct vm_area_struct **pprev);
  
  /* Look up the first VMA which intersects the interval start_addr..end_addr-1,
     NULL if none.  Assume start_addr < end_addr. */
  static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr)
  {
  	struct vm_area_struct * vma = find_vma(mm,start_addr);
  
  	if (vma && end_addr <= vma->vm_start)
  		vma = NULL;
  	return vma;
  }
  
  static inline unsigned long vma_pages(struct vm_area_struct *vma)
  {
  	return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
  }

  pgprot_t vm_get_page_prot(unsigned long vm_flags);

  struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);

  int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
  			unsigned long pfn, unsigned long size, pgprot_t);

  int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);

  int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
  			unsigned long pfn);

  int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
  			unsigned long pfn);

  struct page *follow_page(struct vm_area_struct *, unsigned long address,

  			unsigned int foll_flags);
  #define FOLL_WRITE	0x01	/* check pte is writable */
  #define FOLL_TOUCH	0x02	/* mark page accessed */
  #define FOLL_GET	0x04	/* do get_page on page */

  #define FOLL_DUMP	0x08	/* give error on hole if it would be zero */

  #define FOLL_FORCE	0x10	/* get_user_pages read/write w/o permission */

  typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,

  			void *data);
  extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
  			       unsigned long size, pte_fn_t fn, void *data);

  #ifdef CONFIG_PROC_FS

  void vm_stat_account(struct mm_struct *, unsigned long, struct file *, long);

  #else

  static inline void vm_stat_account(struct mm_struct *mm,

  			unsigned long flags, struct file *file, long pages)
  {
  }
  #endif /* CONFIG_PROC_FS */

  #ifdef CONFIG_DEBUG_PAGEALLOC
  extern int debug_pagealloc_enabled;
  
  extern void kernel_map_pages(struct page *page, int numpages, int enable);
  
  static inline void enable_debug_pagealloc(void)
  {
  	debug_pagealloc_enabled = 1;
  }

  #ifdef CONFIG_HIBERNATION
  extern bool kernel_page_present(struct page *page);
  #endif /* CONFIG_HIBERNATION */

  #else

  static inline void

  kernel_map_pages(struct page *page, int numpages, int enable) {}

  static inline void enable_debug_pagealloc(void)
  {
  }

  #ifdef CONFIG_HIBERNATION
  static inline bool kernel_page_present(struct page *page) { return true; }
  #endif /* CONFIG_HIBERNATION */

  #endif
  
  extern struct vm_area_struct *get_gate_vma(struct task_struct *tsk);
  #ifdef	__HAVE_ARCH_GATE_AREA
  int in_gate_area_no_task(unsigned long addr);
  int in_gate_area(struct task_struct *task, unsigned long addr);
  #else
  int in_gate_area_no_task(unsigned long addr);
  #define in_gate_area(task, addr) ({(void)task; in_gate_area_no_task(addr);})
  #endif	/* __HAVE_ARCH_GATE_AREA */

  int drop_caches_sysctl_handler(struct ctl_table *, int,

  					void __user *, size_t *, loff_t *);

  unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,

  			unsigned long lru_pages);

  #ifndef CONFIG_MMU
  #define randomize_va_space 0
  #else

  extern int randomize_va_space;

  #endif

  const char * arch_vma_name(struct vm_area_struct *vma);

  void print_vma_addr(char *prefix, unsigned long rip);

  void sparse_mem_maps_populate_node(struct page **map_map,
  				   unsigned long pnum_begin,
  				   unsigned long pnum_end,
  				   unsigned long map_count,
  				   int nodeid);

  struct page *sparse_mem_map_populate(unsigned long pnum, int nid);

  pgd_t *vmemmap_pgd_populate(unsigned long addr, int node);
  pud_t *vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node);
  pmd_t *vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node);
  pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node);

  void *vmemmap_alloc_block(unsigned long size, int node);

  void *vmemmap_alloc_block_buf(unsigned long size, int node);

  void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);

  int vmemmap_populate_basepages(struct page *start_page,
  						unsigned long pages, int node);
  int vmemmap_populate(struct page *start_page, unsigned long pages, int node);

  void vmemmap_populate_print_last(void);

  enum mf_flags {
  	MF_COUNT_INCREASED = 1 << 0,
  };

  extern void memory_failure(unsigned long pfn, int trapno);

  extern int __memory_failure(unsigned long pfn, int trapno, int flags);

  extern int unpoison_memory(unsigned long pfn);

  extern int sysctl_memory_failure_early_kill;
  extern int sysctl_memory_failure_recovery;

  extern void shake_page(struct page *p, int access);

  extern atomic_long_t mce_bad_pages;

  extern int soft_offline_page(struct page *page, int flags);

  #ifdef CONFIG_MEMORY_FAILURE
  int is_hwpoison_address(unsigned long addr);
  #else
  static inline int is_hwpoison_address(unsigned long addr)
  {
  	return 0;
  }
  #endif

  extern void dump_page(struct page *page);

  #endif /* __KERNEL__ */
  #endif /* _LINUX_MM_H */