Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

[firefly-linux-kernel-4.4.55.git] / 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>
#include <linux/resource.h>
#include <linux/page_ext.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

/*
 * To prevent common memory management code establishing
 * a zero page mapping on a read fault.
 * This macro should be defined within <asm/pgtable.h>.
 * s390 does this to prevent multiplexing of hardware bits
 * related to the physical page in case of virtualization.
 */
#ifndef mm_forbids_zeropage
#define mm_forbids_zeropage(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_ARCH_1       0x01000000      /* Architecture-specific flag */
#define VM_ARCH_2       0x02000000
#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

#if defined(CONFIG_X86)
/* MPX specific bounds table or bounds directory */
# define VM_MPX         VM_ARCH_2
#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)

/* This mask defines which mm->def_flags a process can inherit its parent */
#define VM_INIT_DEF_MASK        VM_NOHUGEPAGE

/*
 * 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_MKWRITE      0x02    /* Fault was mkwrite of existing pte */
#define FAULT_FLAG_ALLOW_RETRY  0x04    /* Retry fault if blocking */
#define FAULT_FLAG_RETRY_NOWAIT 0x08    /* Don't drop mmap_sem and wait when retrying */
#define FAULT_FLAG_KILLABLE     0x10    /* The fault task is in SIGKILL killable region */
#define FAULT_FLAG_TRIED        0x20    /* Second try */
#define FAULT_FLAG_USER         0x40    /* 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.
 */
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 *cow_page;          /* Handler may choose to COW */
        struct page *page;              /* ->fault handlers should return a
                                         * page here, unless VM_FAULT_NOPAGE
                                         * is set (which is also implied by
                                         * VM_FAULT_ERROR).
                                         */
        /* for ->map_pages() only */
        pgoff_t max_pgoff;              /* map pages for offset from pgoff till
                                         * max_pgoff inclusive */
        pte_t *pte;                     /* pte entry associated with ->pgoff */
};

/*
 * 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);
        void (*map_pages)(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);

        /* Called by the /proc/PID/maps code to ask the vma whether it
         * has a special name.  Returning non-NULL will also cause this
         * vma to be dumped unconditionally. */
        const char *(*name)(struct vm_area_struct *vma);

#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);
#endif
        /*
         * Called by vm_normal_page() for special PTEs to find the
         * page for @addr.  This is useful if the default behavior
         * (using pte_page()) would not find the correct page.
         */
        struct page *(*find_special_page)(struct vm_area_struct *vma,
                                          unsigned long addr);
};

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);
extern int region_is_ram(resource_size_t phys_addr, unsigned long size);

/* 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

extern void kvfree(const void *addr);

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_by_tail(struct page *tail)
{
        struct page *head = tail->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(tail)))
                return head;
        return tail;
}

/*
 * Since either compound page could be dismantled asynchronously in THP
 * or we access asynchronously arbitrary positioned struct page, there
 * would be tail flag race. To handle this race, we should call
 * smp_rmb() before checking tail flag. compound_head_by_tail() did it.
 */
static inline struct page *compound_head(struct page *page)
{
        if (unlikely(PageTail(page)))
                return compound_head_by_tail(page);
        return page;
}

/*
 * If we access compound page synchronously such as access to
 * allocated page, there is no need to handle tail flag race, so we can
 * check tail flag directly without any synchronization primitive.
 */
static inline struct page *compound_head_fast(struct page *page)
{
        if (unlikely(PageTail(page)))
                return page->first_page;
        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)
{
        VM_BUG_ON_PAGE(PageSlab(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);

        /*
         * We don't need to worry about synchronization of tail flag
         * when we call virt_to_head_page() since it is only called for
         * already allocated page and this page won't be freed until
         * this virt_to_head_page() is finished. So use _fast variant.
         */
        return compound_head_fast(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);
}

#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)

static inline int PageBalloon(struct page *page)
{
        return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
}

static inline void __SetPageBalloon(struct page *page)
{
        VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
        atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
}

static inline void __ClearPageBalloon(struct page *page)
{
        VM_BUG_ON_PAGE(!PageBalloon(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.
 */

static inline void set_compound_page_dtor(struct page *page,
                                                compound_page_dtor *dtor)
{
        page[1].compound_dtor = dtor;
}

static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
{
        return page[1].compound_dtor;
}

static inline int compound_order(struct page *page)
{
        if (!PageHead(page))
                return 0;
        return page[1].compound_order;
}

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

void do_set_pte(struct vm_area_struct *vma, unsigned long address,
                struct page *page, pte_t *pte, bool write, bool anon);
#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_SHIFT) - 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 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
 * @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
 * @test_walk: caller specific callback function to determine whether
 *             we walk over the current vma or not. A positive returned
 *             value means "do page table walk over the current vma,"
 *             and a negative one means "abort current page table walk
 *             right now." 0 means "skip the current vma."
 * @mm:        mm_struct representing the target process of page table walk
 * @vma:       vma currently walked (NULL if walking outside vmas)
 * @private:   private data for callbacks' usage
 *
 * (see the comment on walk_page_range() for more details)
 */
struct mm_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);
        int (*test_walk)(unsigned long addr, unsigned long next,
                        struct mm_walk *walk);
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        void *private;
};

int walk_page_range(unsigned long addr, unsigned long end,
                struct mm_walk *walk);
int walk_page_vma(struct vm_area_struct *vma, 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);
long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
                    unsigned long start, unsigned long nr_pages,
                    int write, int force, struct page **pages,
                    int *locked);
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
                               unsigned long start, unsigned long nr_pages,
                               int write, int force, struct page **pages,
                               unsigned int gup_flags);
long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
                    unsigned long start, unsigned long nr_pages,
                    int write, int force, struct page **pages);
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);
int set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
int get_cmdline(struct task_struct *task, char *buffer, int buflen);

/* 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 struct task_struct *task_of_stack(struct task_struct *task,
                                struct vm_area_struct *vma, bool 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 reset_mm_hiwater_rss(struct mm_struct *mm)
{
        mm->hiwater_rss = get_mm_rss(mm);
}

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

#if defined(__PAGETABLE_PMD_FOLDED) || !defined(CONFIG_MMU)
static inline int __pmd_alloc(struct mm_struct *mm, pud_t *pud,
                                                unsigned long address)
{
        return 0;
}

static inline void mm_nr_pmds_init(struct mm_struct *mm) {}

static inline unsigned long mm_nr_pmds(struct mm_struct *mm)
{
        return 0;
}

static inline void mm_inc_nr_pmds(struct mm_struct *mm) {}
static inline void mm_dec_nr_pmds(struct mm_struct *mm) {}

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

static inline void mm_nr_pmds_init(struct mm_struct *mm)
{
        atomic_long_set(&mm->nr_pmds, 0);
}

static inline unsigned long mm_nr_pmds(struct mm_struct *mm)
{
        return atomic_long_read(&mm->nr_pmds);
}

static inline void mm_inc_nr_pmds(struct mm_struct *mm)
{
        atomic_long_inc(&mm->nr_pmds);
}

static inline void mm_dec_nr_pmds(struct mm_struct *mm)
{
        atomic_long_dec(&mm->nr_pmds);
}
#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 struct page *pmd_to_page(pmd_t *pmd)
{
        unsigned long mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
        return virt_to_page((void *)((unsigned long) pmd & mask));
}

static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
{
        return ptlock_ptr(pmd_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) (pmd_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);
/* there is a per-arch backend function. */
extern int __meminit __early_pfn_to_nid(unsigned long pfn);
#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))

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 *);

static inline int check_data_rlimit(unsigned long rlim,
                                    unsigned long new,
                                    unsigned long start,
                                    unsigned long end_data,
                                    unsigned long start_data)
{
        if (rlim < RLIM_INFINITY) {
                if (((new - start) + (end_data - start_data)) > rlim)
                        return -ENOSPC;
        }

        return 0;
}

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 struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
                                   unsigned long addr, unsigned long len,
                                   unsigned long flags,
                                   const struct vm_special_mapping *spec);
/* This is an obsolete alternative to _install_special_mapping. */
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);
extern void truncate_inode_pages_final(struct address_space *);

/* generic vm_area_ops exported for stackable file systems */
extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
extern void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf);
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);
void vma_set_page_prot(struct vm_area_struct *vma);
#else
static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
{
        return __pgprot(0);
}
static inline void vma_set_page_prot(struct vm_area_struct *vma)
{
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
}
#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 */
#define FOLL_TRIED      0x800   /* a retry, previous pass started an IO */

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 bool _debug_pagealloc_enabled;
extern void __kernel_map_pages(struct page *page, int numpages, int enable);

static inline bool debug_pagealloc_enabled(void)
{
        return _debug_pagealloc_enabled;
}

static inline void
kernel_map_pages(struct page *page, int numpages, int enable)
{
        if (!debug_pagealloc_enabled())
                return;

        __kernel_map_pages(page, numpages, 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

#ifdef __HAVE_ARCH_GATE_AREA
extern struct vm_area_struct *get_gate_vma(struct mm_struct *mm);
extern int in_gate_area_no_mm(unsigned long addr);
extern int in_gate_area(struct mm_struct *mm, unsigned long addr);
#else
static inline struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
        return NULL;
}
static inline int in_gate_area_no_mm(unsigned long addr) { return 0; }
static inline int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
        return 0;
}
#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

void drop_slab(void);
void drop_slab_node(int nid);

#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 */

extern struct page_ext_operations debug_guardpage_ops;
extern struct page_ext_operations page_poisoning_ops;

#ifdef CONFIG_DEBUG_PAGEALLOC
extern unsigned int _debug_guardpage_minorder;
extern bool _debug_guardpage_enabled;

static inline unsigned int debug_guardpage_minorder(void)
{
        return _debug_guardpage_minorder;
}

static inline bool debug_guardpage_enabled(void)
{
        return _debug_guardpage_enabled;
}

static inline bool page_is_guard(struct page *page)
{
        struct page_ext *page_ext;

        if (!debug_guardpage_enabled())
                return false;

        page_ext = lookup_page_ext(page);
        return test_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
}
#else
static inline unsigned int debug_guardpage_minorder(void) { return 0; }
static inline bool debug_guardpage_enabled(void) { return false; }
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 */