TOMOYO Linux Cross Reference
Linux/include/linux/mm.h

   #ifndef _LINUX_MM_H
   #define _LINUX_MM_H
   
   #include <linux/errno.h>
   
   #ifdef __KERNEL__
   
   #include <linux/mmdebug.h>
   #include <linux/gfp.h>
  #include <linux/bug.h>
  #include <linux/list.h>
  #include <linux/mmzone.h>
  #include <linux/rbtree.h>
  #include <linux/atomic.h>
  #include <linux/debug_locks.h>
  #include <linux/mm_types.h>
  #include <linux/range.h>
  #include <linux/pfn.h>
  #include <linux/bit_spinlock.h>
  #include <linux/shrinker.h>
  
  struct mempolicy;
  struct anon_vma;
  struct anon_vma_chain;
  struct file_ra_state;
  struct user_struct;
  struct writeback_control;
  
  #ifndef CONFIG_NEED_MULTIPLE_NODES      /* Don't use mapnrs, do it properly */
  extern unsigned long max_mapnr;
  
  static inline void set_max_mapnr(unsigned long limit)
  {
          max_mapnr = limit;
  }
  #else
  static inline void set_max_mapnr(unsigned long limit) { }
  #endif
  
  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>
  
  #ifndef __pa_symbol
  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
  #endif
  
  extern unsigned long sysctl_user_reserve_kbytes;
  extern unsigned long sysctl_admin_reserve_kbytes;
  
  extern int sysctl_overcommit_memory;
  extern int sysctl_overcommit_ratio;
  extern unsigned long sysctl_overcommit_kbytes;
  
  extern int overcommit_ratio_handler(struct ctl_table *, int, void __user *,
                                      size_t *, loff_t *);
  extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *,
                                      size_t *, loff_t *);
  
  #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)
  
  /* test whether an address (unsigned long or pointer) is aligned to PAGE_SIZE */
  #define PAGE_ALIGNED(addr)      IS_ALIGNED((unsigned long)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_NONE         0x00000000
 
 #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_PFNMAP       0x00000400      /* Page-ranges managed without "struct page", just pure PFN */
 #define VM_DENYWRITE    0x00000800      /* ETXTBSY on write attempts.. */
 
 #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_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_ARCH_1       0x01000000      /* Architecture-specific flag */
 #define VM_DONTDUMP     0x04000000      /* Do not include in the core dump */
 
 #ifdef CONFIG_MEM_SOFT_DIRTY
 # define VM_SOFTDIRTY   0x08000000      /* Not soft dirty clean area */
 #else
 # define VM_SOFTDIRTY   0
 #endif
 
 #define VM_MIXEDMAP     0x10000000      /* Can contain "struct page" and pure PFN pages */
 #define VM_HUGEPAGE     0x20000000      /* MADV_HUGEPAGE marked this vma */
 #define VM_NOHUGEPAGE   0x40000000      /* MADV_NOHUGEPAGE marked this vma */
 #define VM_MERGEABLE    0x80000000      /* KSM may merge identical pages */
 
 #if defined(CONFIG_X86)
 # define VM_PAT         VM_ARCH_1       /* PAT reserves whole VMA at once (x86) */
 #elif defined(CONFIG_PPC)
 # define VM_SAO         VM_ARCH_1       /* Strong Access Ordering (powerpc) */
 #elif defined(CONFIG_PARISC)
 # define VM_GROWSUP     VM_ARCH_1
 #elif defined(CONFIG_METAG)
 # define VM_GROWSUP     VM_ARCH_1
 #elif defined(CONFIG_IA64)
 # define VM_GROWSUP     VM_ARCH_1
 #elif !defined(CONFIG_MMU)
 # define VM_MAPPED_COPY VM_ARCH_1       /* T if mapped copy of data (nommu mmap) */
 #endif
 
 #ifndef VM_GROWSUP
 # define VM_GROWSUP     VM_NONE
 #endif
 
 /* 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
 
 /*
  * Special vmas that are non-mergable, non-mlock()able.
  * Note: mm/huge_memory.c VM_NO_THP depends on this definition.
  */
 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP)
 
 /*
  * 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 */
 #define FAULT_FLAG_ALLOW_RETRY  0x08    /* Retry fault if blocking */
 #define FAULT_FLAG_RETRY_NOWAIT 0x10    /* Don't drop mmap_sem and wait when retrying */
 #define FAULT_FLAG_KILLABLE     0x20    /* The fault task is in SIGKILL killable region */
 #define FAULT_FLAG_TRIED        0x40    /* second try */
 #define FAULT_FLAG_USER         0x80    /* The fault originated in userspace */
 
 /*
  * 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 implement ->remap_pages 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
         /* called by sys_remap_file_pages() to populate non-linear mapping */
         int (*remap_pages)(struct vm_area_struct *vma, unsigned long addr,
                            unsigned long size, pgoff_t pgoff);
 };
 
 struct mmu_gather;
 struct inode;
 
 #define page_private(page)              ((page)->private)
 #define set_page_private(page, v)       ((page)->private = (v))
 
 /* It's valid only if the page is free path or free_list */
 static inline void set_freepage_migratetype(struct page *page, int migratetype)
 {
         page->index = migratetype;
 }
 
 /* It's valid only if the page is free path or free_list */
 static inline int get_freepage_migratetype(struct page *page)
 {
         return page->index;
 }
 
 /*
  * FIXME: take this include out, include page-flags.h in
  * files which need it (119 of them)
  */
 #include <linux/page-flags.h>
 #include <linux/huge_mm.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_PAGE(atomic_read(&page->_count) == 0, page);
         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.
  * This can be called when MMU is off so it must not access
  * any of the virtual mappings.
  */
 static inline int get_page_unless_zero(struct page *page)
 {
         return atomic_inc_not_zero(&page->_count);
 }
 
 /*
  * Try to drop a ref unless the page has a refcount of one, return false if
  * that is the case.
  * This is to make sure that the refcount won't become zero after this drop.
  * This can be called when MMU is off so it must not access
  * any of the virtual mappings.
  */
 static inline int put_page_unless_one(struct page *page)
 {
         return atomic_add_unless(&page->_count, -1, 1);
 }
 
 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 void compound_lock(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         VM_BUG_ON_PAGE(PageSlab(page), page);
         bit_spin_lock(PG_compound_lock, &page->flags);
 #endif
 }
 
 static inline void compound_unlock(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         VM_BUG_ON_PAGE(PageSlab(page), page);
         bit_spin_unlock(PG_compound_lock, &page->flags);
 #endif
 }
 
 static inline unsigned long compound_lock_irqsave(struct page *page)
 {
         unsigned long uninitialized_var(flags);
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         local_irq_save(flags);
         compound_lock(page);
 #endif
         return flags;
 }
 
 static inline void compound_unlock_irqrestore(struct page *page,
                                               unsigned long flags)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         compound_unlock(page);
         local_irq_restore(flags);
 #endif
 }
 
 static inline struct page *compound_head(struct page *page)
 {
         if (unlikely(PageTail(page))) {
                 struct page *head = page->first_page;
 
                 /*
                  * page->first_page may be a dangling pointer to an old
                  * compound page, so recheck that it is still a tail
                  * page before returning.
                  */
                 smp_rmb();
                 if (likely(PageTail(page)))
                         return head;
         }
         return page;
 }
 
 /*
  * The atomic page->_mapcount, 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 page_mapcount_reset(struct page *page)
 {
         atomic_set(&(page)->_mapcount, -1);
 }
 
 static inline int page_mapcount(struct page *page)
 {
         return atomic_read(&(page)->_mapcount) + 1;
 }
 
 static inline int page_count(struct page *page)
 {
         return atomic_read(&compound_head(page)->_count);
 }
 
 #ifdef CONFIG_HUGETLB_PAGE
 extern int PageHeadHuge(struct page *page_head);
 #else /* CONFIG_HUGETLB_PAGE */
 static inline int PageHeadHuge(struct page *page_head)
 {
         return 0;
 }
 #endif /* CONFIG_HUGETLB_PAGE */
 
 static inline bool __compound_tail_refcounted(struct page *page)
 {
         return !PageSlab(page) && !PageHeadHuge(page);
 }
 
 /*
  * This takes a head page as parameter and tells if the
  * tail page reference counting can be skipped.
  *
  * For this to be safe, PageSlab and PageHeadHuge must remain true on
  * any given page where they return true here, until all tail pins
  * have been released.
  */
 static inline bool compound_tail_refcounted(struct page *page)
 {
         VM_BUG_ON_PAGE(!PageHead(page), page);
         return __compound_tail_refcounted(page);
 }
 
 static inline void get_huge_page_tail(struct page *page)
 {
         /*
          * __split_huge_page_refcount() cannot run from under us.
          */
         VM_BUG_ON_PAGE(!PageTail(page), page);
         VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
         VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
         if (compound_tail_refcounted(page->first_page))
                 atomic_inc(&page->_mapcount);
 }
 
 extern bool __get_page_tail(struct page *page);
 
 static inline void get_page(struct page *page)
 {
         if (unlikely(PageTail(page)))
                 if (likely(__get_page_tail(page)))
                         return;
         /*
          * 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);
 }
 
 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);
 }
 
 /*
  * PageBuddy() indicate that the page is free and in the buddy system
  * (see mm/page_alloc.c).
  *
  * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
  * -2 so that an underflow of the page_mapcount() won't be mistaken
  * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
  * efficiently by most CPU architectures.
  */
 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
 
 static inline int PageBuddy(struct page *page)
 {
         return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
 }
 
 static inline void __SetPageBuddy(struct page *page)
 {
         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
         atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
 }
 
 static inline void __ClearPageBuddy(struct page *page)
 {
         VM_BUG_ON_PAGE(!PageBuddy(page), page);
         atomic_set(&page->_mapcount, -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;
 }
 
 #ifdef CONFIG_MMU
 /*
  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
  * servicing faults for write access.  In the normal case, do always want
  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
  * that do not have writing enabled, when used by access_process_vm.
  */
 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
 {
         if (likely(vma->vm_flags & VM_WRITE))
                 pte = pte_mkwrite(pte);
         return pte;
 }
 #endif
 
 /*
  * 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: | [SECTION] | [NODE] | ZONE | [LAST_CPUPID] | ... | FLAGS | */
 #define SECTIONS_PGOFF          ((sizeof(unsigned long)*8) - SECTIONS_WIDTH)
 #define NODES_PGOFF             (SECTIONS_PGOFF - NODES_WIDTH)
 #define ZONES_PGOFF             (NODES_PGOFF - ZONES_WIDTH)
 #define LAST_CPUPID_PGOFF       (ZONES_PGOFF - LAST_CPUPID_WIDTH)
 
 /*
  * Define the bit shifts to access each section.  For non-existent
  * 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))
 #define LAST_CPUPID_PGSHIFT     (LAST_CPUPID_PGOFF * (LAST_CPUPID_WIDTH != 0))
 
 /* NODE:ZONE or SECTION:ZONE is used to ID a zone for the buddy allocator */
 #ifdef NODE_NOT_IN_PAGE_FLAGS
 #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 LAST_CPUPID_MASK        ((1UL << LAST_CPUPID_WIDTH) - 1)
 #define ZONEID_MASK             ((1UL << ZONEID_SHIFT) - 1)
 
 static inline enum zone_type page_zonenum(const struct page *page)
 {
         return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
 }
 
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif
 
 /*
  * The identification function is mainly used by the buddy allocator for
  * determining if two pages could be buddies. We are not really identifying
  * the zone since we could be using the section number id if we do not have
  * node id available in page flags.
  * We only guarantee 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(const struct page *page);
 #else
 static inline int page_to_nid(const struct page *page)
 {
         return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
 }
 #endif
 
 #ifdef CONFIG_NUMA_BALANCING
 static inline int cpu_pid_to_cpupid(int cpu, int pid)
 {
         return ((cpu & LAST__CPU_MASK) << LAST__PID_SHIFT) | (pid & LAST__PID_MASK);
 }
 
 static inline int cpupid_to_pid(int cpupid)
 {
         return cpupid & LAST__PID_MASK;
 }
 
 static inline int cpupid_to_cpu(int cpupid)
 {
         return (cpupid >> LAST__PID_SHIFT) & LAST__CPU_MASK;
 }
 
 static inline int cpupid_to_nid(int cpupid)
 {
         return cpu_to_node(cpupid_to_cpu(cpupid));
 }
 
 static inline bool cpupid_pid_unset(int cpupid)
 {
         return cpupid_to_pid(cpupid) == (-1 & LAST__PID_MASK);
 }
 
 static inline bool cpupid_cpu_unset(int cpupid)
 {
         return cpupid_to_cpu(cpupid) == (-1 & LAST__CPU_MASK);
 }
 
 static inline bool __cpupid_match_pid(pid_t task_pid, int cpupid)
 {
         return (task_pid & LAST__PID_MASK) == cpupid_to_pid(cpupid);
 }
 
 #define cpupid_match_pid(task, cpupid) __cpupid_match_pid(task->pid, cpupid)
 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
 static inline int page_cpupid_xchg_last(struct page *page, int cpupid)
 {
         return xchg(&page->_last_cpupid, cpupid & LAST_CPUPID_MASK);
 }
 
 static inline int page_cpupid_last(struct page *page)
 {
         return page->_last_cpupid;
 }
 static inline void page_cpupid_reset_last(struct page *page)
 {
         page->_last_cpupid = -1 & LAST_CPUPID_MASK;
 }
 #else
 static inline int page_cpupid_last(struct page *page)
 {
         return (page->flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;
 }
 
 extern int page_cpupid_xchg_last(struct page *page, int cpupid);
 
 static inline void page_cpupid_reset_last(struct page *page)
 {
         int cpupid = (1 << LAST_CPUPID_SHIFT) - 1;
 
         page->flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
         page->flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
 }
 #endif /* LAST_CPUPID_NOT_IN_PAGE_FLAGS */
 #else /* !CONFIG_NUMA_BALANCING */
 static inline int page_cpupid_xchg_last(struct page *page, int cpupid)
 {
         return page_to_nid(page); /* XXX */
 }
 
 static inline int page_cpupid_last(struct page *page)
 {
         return page_to_nid(page); /* XXX */
 }
 
 static inline int cpupid_to_nid(int cpupid)
 {
         return -1;
 }
 
 static inline int cpupid_to_pid(int cpupid)
 {
         return -1;
 }
 
 static inline int cpupid_to_cpu(int cpupid)
 {
         return -1;
 }
 
 static inline int cpu_pid_to_cpupid(int nid, int pid)
 {
         return -1;
 }
 
 static inline bool cpupid_pid_unset(int cpupid)
 {
         return 1;
 }
 
 static inline void page_cpupid_reset_last(struct page *page)
 {
 }
 
 static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
 {
         return false;
 }
 #endif /* CONFIG_NUMA_BALANCING */
 
 static inline struct zone *page_zone(const struct page *page)
 {
         return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];
 }
 
 #ifdef SECTION_IN_PAGE_FLAGS
 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 unsigned long page_to_section(const 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_links(struct page *page, enum zone_type zone,
         unsigned long node, unsigned long pfn)
 {
         set_page_zone(page, zone);
         set_page_node(page, node);
 #ifdef SECTION_IN_PAGE_FLAGS
         set_page_section(page, pfn_to_section_nr(pfn));
 #endif
 }
 
 /*
  * Some inline functions in vmstat.h depend on page_zone()
  */
 #include <linux/vmstat.h>
 
 static __always_inline void *lowmem_page_address(const 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)
 static inline void *page_address(const struct page *page)
 {
         return page->virtual;
 }
 static inline void set_page_address(struct page *page, void *address)
 {
         page->virtual = address;
 }
 #define page_address_init()  do { } while(0)
 #endif
 
 #if defined(HASHED_PAGE_VIRTUAL)
 void *page_address(const 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 *page_mapping(struct page *page);
 
 /* 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);
 }
 
 extern struct address_space *__page_file_mapping(struct page *);
 
 static inline
 struct address_space *page_file_mapping(struct page *page)
 {
         if (unlikely(PageSwapCache(page)))
                 return __page_file_mapping(page);
 
         return page->mapping;
 }
 
 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;
 }
 
 extern pgoff_t __page_file_index(struct page *page);
 
 /*
  * Return the file index of the page. Regular pagecache pages use ->index
  * whereas swapcache pages use swp_offset(->private)
  */
 static inline pgoff_t page_file_index(struct page *page)
 {
         if (unlikely(PageSwapCache(page)))
                 return __page_file_index(page);
 
         return page->index;
 }
 
 /*
  * 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 small page */
 #define VM_FAULT_HWPOISON_LARGE 0x0020  /* Hit poisoned large page. Index encoded in upper bits */
 #define VM_FAULT_SIGSEGV 0x0040
 
 #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_RETRY  0x0400  /* ->fault blocked, must retry */
 #define VM_FAULT_FALLBACK 0x0800        /* huge page fault failed, fall back to small */
 
 #define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */
 
 #define VM_FAULT_ERROR  (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
                          VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
                          VM_FAULT_FALLBACK)
 
 /* Encode hstate index for a hwpoisoned large page */
 #define VM_FAULT_SET_HINDEX(x) ((x) << 12)
 #define VM_FAULT_GET_HINDEX(x) (((x) >> 12) & 0xf)
 
 /*
  * 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)
 
 /*
  * Flags passed to show_mem() and show_free_areas() to suppress output in
  * various contexts.
  */
 #define SHOW_MEM_FILTER_NODES           (0x0001u)       /* disallowed nodes */
 
 extern void show_free_areas(unsigned int flags);
 extern bool skip_free_areas_node(unsigned int flags, int nid);
 
 int shmem_zero_setup(struct vm_area_struct *);
 #ifdef CONFIG_SHMEM
 bool shmem_mapping(struct address_space *mapping);
 #else
 static inline bool shmem_mapping(struct address_space *mapping)
 {
         return false;
 }
 #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 */
 };
 
 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);
 void zap_page_range(struct vm_area_struct *vma, unsigned long address,
                 unsigned long size, struct zap_details *);
 void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
                 unsigned long start, unsigned long end);
 
 /**
  * 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
  *             this handler is required to be able to handle
  *             pmd_trans_huge() pmds.  They may simply choose to
  *             split_huge_page() instead of handling it explicitly.
  * @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
  *                 *Caution*: The caller must hold mmap_sem() if @hugetlb_entry
  *                            is used.
  *
  * (see walk_page_range for more details)
  */
 struct mm_walk {
         int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
                          unsigned long next, struct mm_walk *walk);
         int (*pud_entry)(pud_t *pud, unsigned long addr,
                          unsigned long next, struct mm_walk *walk);
         int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
                          unsigned long next, struct mm_walk *walk);
         int (*pte_entry)(pte_t *pte, unsigned long addr,
                          unsigned long next, struct mm_walk *walk);
         int (*pte_hole)(unsigned long addr, unsigned long next,
                         struct mm_walk *walk);
         int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
                              unsigned long addr, unsigned long next,
                              struct mm_walk *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 new);
 extern void truncate_setsize(struct inode *inode, loff_t newsize);
 void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to);
 void truncate_pagecache_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);
 extern int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
                             unsigned long address, unsigned int fault_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;
 }
 static inline int fixup_user_fault(struct task_struct *tsk,
                 struct mm_struct *mm, unsigned long address,
                 unsigned int fault_flags)
 {
         /* should never happen if there's no MMU */
         BUG();
         return -EFAULT;
 }
 #endif
 
 extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
                 void *buf, int len, int write);
 
 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);
 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 get_user_pages_fast(unsigned long start, int nr_pages, int write,
                         struct page **pages);
 struct kvec;
 int get_kernel_pages(const struct kvec *iov, int nr_pages, int write,
                         struct page **pages);
 int get_kernel_page(unsigned long start, 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 int offset,
                               unsigned int length);
 
 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);
 void account_page_writeback(struct page *page);
 int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
 
 /* Is the vma a continuation of the stack vma above it? */
 static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
 {
         return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
 }
 
 static inline int stack_guard_page_start(struct vm_area_struct *vma,
                                              unsigned long addr)
 {
         return (vma->vm_flags & VM_GROWSDOWN) &&
                 (vma->vm_start == addr) &&
                 !vma_growsdown(vma->vm_prev, addr);
 }
 
 /* Is the vma a continuation of the stack vma below it? */
 static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
 {
         return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
 }
 
 static inline int stack_guard_page_end(struct vm_area_struct *vma,
                                            unsigned long addr)
 {
         return (vma->vm_flags & VM_GROWSUP) &&
                 (vma->vm_end == addr) &&
                 !vma_growsup(vma->vm_next, addr);
 }
 
 extern pid_t
 vm_is_stack(struct task_struct *task, struct vm_area_struct *vma, int in_group);
 
 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,
                 bool need_rmap_locks);
 extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
                               unsigned long end, pgprot_t newprot,
                               int dirty_accountable, int prot_numa);
 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.
  */
 static inline unsigned long get_mm_counter(struct mm_struct *mm, int member)
 {
         long val = atomic_long_read(&mm->rss_stat.count[member]);
 
 #ifdef SPLIT_RSS_COUNTING
         /*
          * counter is updated in asynchronous manner and may go to minus.
          * But it's never be expected number for users.
          */
         if (val < 0)
                 val = 0;
 #endif
         return (unsigned long)val;
 }
 
 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]);
 }
 
 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 mm_struct *mm);
 #else
 static inline void sync_mm_rss(struct mm_struct *mm)
 {
 }
 #endif
 
 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);
 static inline pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
                                     spinlock_t **ptl)
 {
         pte_t *ptep;
         __cond_lock(*ptl, ptep = __get_locked_pte(mm, addr, ptl));
         return ptep;
 }
 
 #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, struct vm_area_struct *vma,
                 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_PTE_PTLOCKS
 #if ALLOC_SPLIT_PTLOCKS
 void __init ptlock_cache_init(void);
 extern bool ptlock_alloc(struct page *page);
 extern void ptlock_free(struct page *page);
 
 static inline spinlock_t *ptlock_ptr(struct page *page)
 {
         return page->ptl;
 }
 #else /* ALLOC_SPLIT_PTLOCKS */
 static inline void ptlock_cache_init(void)
 {
 }
 
 static inline bool ptlock_alloc(struct page *page)
 {
         return true;
 }
 
 static inline void ptlock_free(struct page *page)
 {
 }
 
 static inline spinlock_t *ptlock_ptr(struct page *page)
 {
         return &page->ptl;
 }
 #endif /* ALLOC_SPLIT_PTLOCKS */
 
 static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)
 {
         return ptlock_ptr(pmd_page(*pmd));
 }
 
 static inline bool ptlock_init(struct page *page)
 {
         /*
          * prep_new_page() initialize page->private (and therefore page->ptl)
          * with 0. Make sure nobody took it in use in between.
          *
          * It can happen if arch try to use slab for page table allocation:
          * slab code uses page->slab_cache and page->first_page (for tail
          * pages), which share storage with page->ptl.
          */
         VM_BUG_ON_PAGE(*(unsigned long *)&page->ptl, page);
         if (!ptlock_alloc(page))
                 return false;
         spin_lock_init(ptlock_ptr(page));
         return true;
 }
 
 /* Reset page->mapping so free_pages_check won't complain. */
 static inline void pte_lock_deinit(struct page *page)
 {
         page->mapping = NULL;
         ptlock_free(page);
 }
 
 #else   /* !USE_SPLIT_PTE_PTLOCKS */
 /*
  * We use mm->page_table_lock to guard all pagetable pages of the mm.
  */
 static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)
 {
         return &mm->page_table_lock;
 }
 static inline void ptlock_cache_init(void) {}
 static inline bool ptlock_init(struct page *page) { return true; }
 static inline void pte_lock_deinit(struct page *page) {}
 #endif /* USE_SPLIT_PTE_PTLOCKS */
 
 static inline void pgtable_init(void)
 {
         ptlock_cache_init();
         pgtable_cache_init();
 }
 
 static inline bool pgtable_page_ctor(struct page *page)
 {
         inc_zone_page_state(page, NR_PAGETABLE);
         return ptlock_init(page);
 }
 
 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, vma, pmd, address)                            \
         ((unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, vma,    \
                                                         pmd, address))? \
          NULL: pte_offset_map(pmd, address))
 
 #define pte_alloc_map_lock(mm, pmd, address, ptlp)      \
         ((unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, NULL,   \
                                                         pmd, address))? \
                 NULL: pte_offset_map_lock(mm, pmd, address, ptlp))
 
 #define pte_alloc_kernel(pmd, address)                  \
         ((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
                 NULL: pte_offset_kernel(pmd, address))
 
 #if USE_SPLIT_PMD_PTLOCKS
 
 static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
 {
         return ptlock_ptr(virt_to_page(pmd));
 }
 
 static inline bool pgtable_pmd_page_ctor(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         page->pmd_huge_pte = NULL;
 #endif
         return ptlock_init(page);
 }
 
 static inline void pgtable_pmd_page_dtor(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         VM_BUG_ON_PAGE(page->pmd_huge_pte, page);
 #endif
         ptlock_free(page);
 }
 
 #define pmd_huge_pte(mm, pmd) (virt_to_page(pmd)->pmd_huge_pte)
 
 #else
 
 static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
 {
         return &mm->page_table_lock;
 }
 
 static inline bool pgtable_pmd_page_ctor(struct page *page) { return true; }
 static inline void pgtable_pmd_page_dtor(struct page *page) {}
 
 #define pmd_huge_pte(mm, pmd) ((mm)->pmd_huge_pte)
 
 #endif
 
 static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
 {
         spinlock_t *ptl = pmd_lockptr(mm, pmd);
         spin_lock(ptl);
         return ptl;
 }
 
 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);
 extern void free_initmem(void);
 
 /*
  * Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
  * into the buddy system. The freed pages will be poisoned with pattern
  * "poison" if it's within range [0, UCHAR_MAX].
  * Return pages freed into the buddy system.
  */
 extern unsigned long free_reserved_area(void *start, void *end,
                                         int poison, char *s);
 
 #ifdef  CONFIG_HIGHMEM
 /*
  * Free a highmem page into the buddy system, adjusting totalhigh_pages
  * and totalram_pages.
  */
 extern void free_highmem_page(struct page *page);
 #endif
 
 extern void adjust_managed_page_count(struct page *page, long count);
 extern void mem_init_print_info(const char *str);
 
 /* Free the reserved page into the buddy system, so it gets managed. */
 static inline void __free_reserved_page(struct page *page)
 {
         ClearPageReserved(page);
         init_page_count(page);
         __free_page(page);
 }
 
 static inline void free_reserved_page(struct page *page)
 {
         __free_reserved_page(page);
         adjust_managed_page_count(page, 1);
 }
 
 static inline void mark_page_reserved(struct page *page)
 {
         SetPageReserved(page);
         adjust_managed_page_count(page, -1);
 }
 
 /*
  * Default method to free all the __init memory into the buddy system.
  * The freed pages will be poisoned with pattern "poison" if it's within
  * range [0, UCHAR_MAX].
  * Return pages freed into the buddy system.
  */
 static inline unsigned long free_initmem_default(int poison)
 {
         extern char __init_begin[], __init_end[];
 
         return free_reserved_area(&__init_begin, &__init_end,
                                   poison, "unused kernel");
 }
 
 static inline unsigned long get_num_physpages(void)
 {
         int nid;
         unsigned long phys_pages = 0;
 
         for_each_online_node(nid)
                 phys_pages += node_present_pages(nid);
 
         return phys_pages;
 }
 
 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
 /*
  * With CONFIG_HAVE_MEMBLOCK_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 memblock_add[_node]() 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()
  *      memblock_add_node(base, size, nid)
  * free_area_init_nodes(max_zone_pfns);
  *
  * free_bootmem_with_active_regions() calls 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_HAVE_MEMBLOCK_NODE_MAP.
  */
 extern void free_area_init_nodes(unsigned long *max_zone_pfn);
 unsigned long node_map_pfn_alignment(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);
 extern void sparse_memory_present_with_active_regions(int nid);
 
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 
 #if !defined(CONFIG_HAVE_MEMBLOCK_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 int __meminit init_per_zone_wmark_min(void);
 extern void mem_init(void);
 extern void __init mmap_init(void);
 extern void show_mem(unsigned int flags);
 extern void si_meminfo(struct sysinfo * val);
 extern void si_meminfo_node(struct sysinfo *val, int nid);
 
 extern __printf(3, 4)
 void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...);
 
 extern void setup_per_cpu_pageset(void);
 
 extern void zone_pcp_update(struct zone *zone);
 extern void zone_pcp_reset(struct zone *zone);
 
 /* page_alloc.c */
 extern int min_free_kbytes;
 
 /* nommu.c */
 extern atomic_long_t mmap_pages_allocated;
 extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);
 
 /* interval_tree.c */
 void vma_interval_tree_insert(struct vm_area_struct *node,
                               struct rb_root *root);
 void vma_interval_tree_insert_after(struct vm_area_struct *node,
                                     struct vm_area_struct *prev,
                                     struct rb_root *root);
 void vma_interval_tree_remove(struct vm_area_struct *node,
                               struct rb_root *root);
 struct vm_area_struct *vma_interval_tree_iter_first(struct rb_root *root,
                                 unsigned long start, unsigned long last);
 struct vm_area_struct *vma_interval_tree_iter_next(struct vm_area_struct *node,
                                 unsigned long start, unsigned long last);
 
 #define vma_interval_tree_foreach(vma, root, start, last)               \
         for (vma = vma_interval_tree_iter_first(root, start, last);     \
              vma; vma = vma_interval_tree_iter_next(vma, start, last))
 
 static inline void vma_nonlinear_insert(struct vm_area_struct *vma,
                                         struct list_head *list)
 {
         list_add_tail(&vma->shared.nonlinear, list);
 }
 
 void anon_vma_interval_tree_insert(struct anon_vma_chain *node,
                                    struct rb_root *root);
 void anon_vma_interval_tree_remove(struct anon_vma_chain *node,
                                    struct rb_root *root);
 struct anon_vma_chain *anon_vma_interval_tree_iter_first(
         struct rb_root *root, unsigned long start, unsigned long last);
 struct anon_vma_chain *anon_vma_interval_tree_iter_next(
         struct anon_vma_chain *node, unsigned long start, unsigned long last);
 #ifdef CONFIG_DEBUG_VM_RB
 void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
 #endif
 
 #define anon_vma_interval_tree_foreach(avc, root, start, last)           \
         for (avc = anon_vma_interval_tree_iter_first(root, start, last); \
              avc; avc = anon_vma_interval_tree_iter_next(avc, start, last))
 
 /* 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,
         bool *need_rmap_locks);
 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);
 
 extern void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
 extern struct file *get_mm_exe_file(struct mm_struct *mm);
 
 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 mmap_region(struct file *file, unsigned long addr,
         unsigned long len, vm_flags_t vm_flags, unsigned long pgoff);
 extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
         unsigned long len, unsigned long prot, unsigned long flags,
         unsigned long pgoff, unsigned long *populate);
 extern int do_munmap(struct mm_struct *, unsigned long, size_t);
 
 #ifdef CONFIG_MMU
 extern int __mm_populate(unsigned long addr, unsigned long len,
                          int ignore_errors);
 static inline void mm_populate(unsigned long addr, unsigned long len)
 {
         /* Ignore errors */
         (void) __mm_populate(addr, len, 1);
 }
 #else
 static inline void mm_populate(unsigned long addr, unsigned long len) {}
 #endif
 
 /* These take the mm semaphore themselves */
 extern unsigned long vm_brk(unsigned long, unsigned long);
 extern int vm_munmap(unsigned long, size_t);
 extern unsigned long vm_mmap(struct file *, unsigned long,
         unsigned long, unsigned long,
         unsigned long, unsigned long);
 
 struct vm_unmapped_area_info {
 #define VM_UNMAPPED_AREA_TOPDOWN 1
         unsigned long flags;
         unsigned long length;
         unsigned long low_limit;
         unsigned long high_limit;
         unsigned long align_mask;
         unsigned long align_offset;
 };
 
 extern unsigned long unmapped_area(struct vm_unmapped_area_info *info);
 extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info);
 
 /*
  * Search for an unmapped address range.
  *
  * We are looking for a range that:
  * - does not intersect with any VMA;
  * - is contained within the [low_limit, high_limit) interval;
  * - is at least the desired size.
  * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
  */
 static inline unsigned long
 vm_unmapped_area(struct vm_unmapped_area_info *info)
 {
         if (!(info->flags & VM_UNMAPPED_AREA_TOPDOWN))
                 return unmapped_area(info);
         else
                 return unmapped_area_topdown(info);
 }
 
 /* truncate.c */
 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 *);
 extern int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 
 /* 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);
 
 /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
 extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
 
 /* CONFIG_STACK_GROWSUP still needs to to grow downwards at some places */
 extern int expand_downwards(struct vm_area_struct *vma,
                 unsigned long address);
 #if VM_GROWSUP
 extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
 #else
   #define expand_upwards(vma, address) (0)
 #endif
 
 /* 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;
 }
 
 /* Look up the first VMA which exactly match the interval vm_start ... vm_end */
 static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm,
                                 unsigned long vm_start, unsigned long vm_end)
 {
         struct vm_area_struct *vma = find_vma(mm, vm_start);
 
         if (vma && (vma->vm_start != vm_start || vma->vm_end != vm_end))
                 vma = NULL;
 
         return vma;
 }
 
 #ifdef CONFIG_MMU
 pgprot_t vm_get_page_prot(unsigned long vm_flags);
 #else
 static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
 {
         return __pgprot(0);
 }
 #endif
 
 #ifdef CONFIG_NUMA_BALANCING
 unsigned long change_prot_numa(struct vm_area_struct *vma,
                         unsigned long start, unsigned long end);
 #endif
 
 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);
 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
 
 
 struct page *follow_page_mask(struct vm_area_struct *vma,
                               unsigned long address, unsigned int foll_flags,
                               unsigned int *page_mask);
 
 static inline struct page *follow_page(struct vm_area_struct *vma,
                 unsigned long address, unsigned int foll_flags)
 {
         unsigned int unused_page_mask;
         return follow_page_mask(vma, address, foll_flags, &unused_page_mask);
 }
 
 #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 */
 #define FOLL_NOWAIT     0x20    /* if a disk transfer is needed, start the IO
                                  * and return without waiting upon it */
 #define FOLL_MLOCK      0x40    /* mark page as mlocked */
 #define FOLL_SPLIT      0x80    /* don't return transhuge pages, split them */
 #define FOLL_HWPOISON   0x100   /* check page is hwpoisoned */
 #define FOLL_NUMA       0x200   /* force NUMA hinting page fault */
 #define FOLL_MIGRATION  0x400   /* wait for page to replace migration entry */
 
 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)
 {
         mm->total_vm += pages;
 }
 #endif /* CONFIG_PROC_FS */
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 extern void kernel_map_pages(struct page *page, int numpages, int enable);
 #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) {}
 #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 mm_struct *mm);
 #ifdef  __HAVE_ARCH_GATE_AREA
 int in_gate_area_no_mm(unsigned long addr);
 int in_gate_area(struct mm_struct *mm, unsigned long addr);
 #else
 int in_gate_area_no_mm(unsigned long addr);
 #define in_gate_area(mm, addr) ({(void)mm; in_gate_area_no_mm(addr);})
 #endif  /* __HAVE_ARCH_GATE_AREA */
 
 #ifdef CONFIG_SYSCTL
 extern int sysctl_drop_caches;
 int drop_caches_sysctl_handler(struct ctl_table *, int,
                                         void __user *, size_t *, loff_t *);
 #endif
 
 unsigned long shrink_slab(struct shrink_control *shrink,
                           unsigned long nr_pages_scanned,
                           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(unsigned long start, unsigned long end,
                                int node);
 int vmemmap_populate(unsigned long start, unsigned long end, int node);
 void vmemmap_populate_print_last(void);
 #ifdef CONFIG_MEMORY_HOTPLUG
 void vmemmap_free(unsigned long start, unsigned long end);
 #endif
 void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
                                   unsigned long size);
 
 enum mf_flags {
         MF_COUNT_INCREASED = 1 << 0,
         MF_ACTION_REQUIRED = 1 << 1,
         MF_MUST_KILL = 1 << 2,
         MF_SOFT_OFFLINE = 1 << 3,
 };
 extern int memory_failure(unsigned long pfn, int trapno, int flags);
 extern void memory_failure_queue(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 num_poisoned_pages;
 extern int soft_offline_page(struct page *page, int flags);
 
 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
 extern void clear_huge_page(struct page *page,
                             unsigned long addr,
                             unsigned int pages_per_huge_page);
 extern 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);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 extern unsigned int _debug_guardpage_minorder;
 
 static inline unsigned int debug_guardpage_minorder(void)
 {
         return _debug_guardpage_minorder;
 }
 
 static inline bool page_is_guard(struct page *page)
 {
         return test_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
 }
 #else
 static inline unsigned int debug_guardpage_minorder(void) { return 0; }
 static inline bool page_is_guard(struct page *page) { return false; }
 #endif /* CONFIG_DEBUG_PAGEALLOC */
 
 #if MAX_NUMNODES > 1
 void __init setup_nr_node_ids(void);
 #else
 static inline void setup_nr_node_ids(void) {}
 #endif
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
 

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