mm: migrate: support non-lru movable page migration

[mirror_ubuntu-artful-kernel.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/percpu-refcount.h>
#include <linux/bit_spinlock.h>
#include <linux/shrinker.h>
#include <linux/resource.h>
#include <linux/page_ext.h>
#include <linux/err.h>
#include <linux/page_ref.h>

struct mempolicy;
struct anon_vma;
struct anon_vma_chain;
struct file_ra_state;
struct user_struct;
struct writeback_control;
struct bdi_writeback;

#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

#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
extern const int mmap_rnd_bits_min;
extern const int mmap_rnd_bits_max;
extern int mmap_rnd_bits __read_mostly;
#endif
#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
extern const int mmap_rnd_compat_bits_min;
extern const int mmap_rnd_compat_bits_max;
extern int mmap_rnd_compat_bits __read_mostly;
#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

#ifndef page_to_virt
#define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
#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

/*
 * Default maximum number of active map areas, this limits the number of vmas
 * per mm struct. Users can overwrite this number by sysctl but there is a
 * problem.
 *
 * When a program's coredump is generated as ELF format, a section is created
 * per a vma. In ELF, the number of sections is represented in unsigned short.
 * This means the number of sections should be smaller than 65535 at coredump.
 * Because the kernel adds some informative sections to a image of program at
 * generating coredump, we need some margin. The number of extra sections is
 * 1-3 now and depends on arch. We use "5" as safe margin, here.
 *
 * ELF extended numbering allows more than 65535 sections, so 16-bit bound is
 * not a hard limit any more. Although some userspace tools can be surprised by
 * that.
 */
#define MAPCOUNT_ELF_CORE_MARGIN        (5)
#define DEFAULT_MAX_MAP_COUNT   (USHRT_MAX - MAPCOUNT_ELF_CORE_MARGIN)

extern int sysctl_max_map_count;

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.
 * When changing, update also include/trace/events/mmflags.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_UFFD_MISSING 0x00000200      /* missing pages tracking */
#define VM_PFNMAP       0x00000400      /* Page-ranges managed without "struct page", just pure PFN */
#define VM_DENYWRITE    0x00000800      /* ETXTBSY on write attempts.. */
#define VM_UFFD_WP      0x00001000      /* wrprotect pages tracking */

#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_LOCKONFAULT  0x00080000      /* Lock the pages covered when they are faulted in */
#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 */

#ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
#define VM_HIGH_ARCH_BIT_0      32      /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_BIT_1      33      /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_BIT_2      34      /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_BIT_3      35      /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_0  BIT(VM_HIGH_ARCH_BIT_0)
#define VM_HIGH_ARCH_1  BIT(VM_HIGH_ARCH_BIT_1)
#define VM_HIGH_ARCH_2  BIT(VM_HIGH_ARCH_BIT_2)
#define VM_HIGH_ARCH_3  BIT(VM_HIGH_ARCH_BIT_3)
#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */

#if defined(CONFIG_X86)
# define VM_PAT         VM_ARCH_1       /* PAT reserves whole VMA at once (x86) */
#if defined (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS)
# define VM_PKEY_SHIFT  VM_HIGH_ARCH_BIT_0
# define VM_PKEY_BIT0   VM_HIGH_ARCH_0  /* A protection key is a 4-bit value */
# define VM_PKEY_BIT1   VM_HIGH_ARCH_1
# define VM_PKEY_BIT2   VM_HIGH_ARCH_2
# define VM_PKEY_BIT3   VM_HIGH_ARCH_3
#endif
#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        VM_GROWSUP
#else
#define VM_STACK        VM_GROWSDOWN
#endif

#define VM_STACK_FLAGS  (VM_STACK | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)

/*
 * 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

/* This mask is used to clear all the VMA flags used by mlock */
#define VM_LOCKED_CLEAR_MASK    (~(VM_LOCKED | VM_LOCKONFAULT))

/*
 * 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 */
#define FAULT_FLAG_REMOTE       0x80    /* faulting for non current tsk/mm */
#define FAULT_FLAG_INSTRUCTION  0x100   /* The fault was during an instruction fetch */

/*
 * 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.
 *
 * MM layer fills up gfp_mask for page allocations but fault handler might
 * alter it if its implementation requires a different allocation context.
 *
 * pgoff should be used in favour of virtual_address, if possible.
 */
struct vm_fault {
        unsigned int flags;             /* FAULT_FLAG_xxx flags */
        gfp_t gfp_mask;                 /* gfp mask to be used for allocations */
        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).
                                         */
        void *entry;                    /* ->fault handler can alternatively
                                         * return locked DAX entry. In that
                                         * case handler should return
                                         * VM_FAULT_DAX_LOCKED and fill in
                                         * entry here.
                                         */
        /* 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 (*mremap)(struct vm_area_struct * area);
        int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
        int (*pmd_fault)(struct vm_area_struct *, unsigned long address,
                                                pmd_t *, unsigned int flags);
        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);

        /* same as page_mkwrite when using VM_PFNMAP|VM_MIXEDMAP */
        int (*pfn_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))

#if !defined(__HAVE_ARCH_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
static inline int pmd_devmap(pmd_t pmd)
{
        return 0;
}
#endif

/*
 * 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(page_ref_count(page) == 0, page);
        return page_ref_dec_and_test(page);
}

/*
 * 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 page_ref_add_unless(page, 1, 0);
}

extern int page_is_ram(unsigned long pfn);

enum {
        REGION_INTERSECTS,
        REGION_DISJOINT,
        REGION_MIXED,
};

int region_intersects(resource_size_t offset, size_t size, unsigned long flags,
                      unsigned long desc);

/* 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 bool is_vmalloc_addr(const void *x)
{
#ifdef CONFIG_MMU
        unsigned long addr = (unsigned long)x;

        return addr >= VMALLOC_START && addr < VMALLOC_END;
#else
        return false;
#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 atomic_t *compound_mapcount_ptr(struct page *page)
{
        return &page[1].compound_mapcount;
}

static inline int compound_mapcount(struct page *page)
{
        VM_BUG_ON_PAGE(!PageCompound(page), page);
        page = compound_head(page);
        return atomic_read(compound_mapcount_ptr(page)) + 1;
}

/*
 * 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);
}

int __page_mapcount(struct page *page);

static inline int page_mapcount(struct page *page)
{
        VM_BUG_ON_PAGE(PageSlab(page), page);

        if (unlikely(PageCompound(page)))
                return __page_mapcount(page);
        return atomic_read(&page->_mapcount) + 1;
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
int total_mapcount(struct page *page);
int page_trans_huge_mapcount(struct page *page, int *total_mapcount);
#else
static inline int total_mapcount(struct page *page)
{
        return page_mapcount(page);
}
static inline int page_trans_huge_mapcount(struct page *page,
                                           int *total_mapcount)
{
        int mapcount = page_mapcount(page);
        if (total_mapcount)
                *total_mapcount = mapcount;
        return mapcount;
}
#endif

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

        return compound_head(page);
}

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 compound page.
 */
typedef void compound_page_dtor(struct page *);

/* Keep the enum in sync with compound_page_dtors array in mm/page_alloc.c */
enum compound_dtor_id {
        NULL_COMPOUND_DTOR,
        COMPOUND_PAGE_DTOR,
#ifdef CONFIG_HUGETLB_PAGE
        HUGETLB_PAGE_DTOR,
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
        TRANSHUGE_PAGE_DTOR,
#endif
        NR_COMPOUND_DTORS,
};
extern compound_page_dtor * const compound_page_dtors[];

static inline void set_compound_page_dtor(struct page *page,
                enum compound_dtor_id compound_dtor)
{
        VM_BUG_ON_PAGE(compound_dtor >= NR_COMPOUND_DTORS, page);
        page[1].compound_dtor = compound_dtor;
}

static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
{
        VM_BUG_ON_PAGE(page[1].compound_dtor >= NR_COMPOUND_DTORS, page);
        return compound_page_dtors[page[1].compound_dtor];
}

static inline unsigned 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 int order)
{
        page[1].compound_order = order;
}

void free_compound_page(struct page *page);

#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_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;
}

#ifdef CONFIG_ZONE_DEVICE
void get_zone_device_page(struct page *page);
void put_zone_device_page(struct page *page);
static inline bool is_zone_device_page(const struct page *page)
{
        return page_zonenum(page) == ZONE_DEVICE;
}
#else
static inline void get_zone_device_page(struct page *page)
{
}
static inline void put_zone_device_page(struct page *page)
{
}
static inline bool is_zone_device_page(const struct page *page)
{
        return false;
}
#endif

static inline void get_page(struct page *page)
{
        page = compound_head(page);
        /*
         * Getting a normal page or the head of a compound page
         * requires to already have an elevated page->_refcount.
         */
        VM_BUG_ON_PAGE(page_ref_count(page) <= 0, page);
        page_ref_inc(page);

        if (unlikely(is_zone_device_page(page)))
                get_zone_device_page(page);
}

static inline void put_page(struct page *page)
{
        page = compound_head(page);

        if (put_page_testzero(page))
                __put_page(page);

        if (unlikely(is_zone_device_page(page)))
                put_zone_device_page(page);
}

#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)
{
        page->flags |= 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
}

#ifdef CONFIG_MEMCG
static inline struct mem_cgroup *page_memcg(struct page *page)
{
        return page->mem_cgroup;
}
#else
static inline struct mem_cgroup *page_memcg(struct page *page)
{
        return NULL;
}
#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 page_to_virt(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

extern void *page_rmapping(struct page *page);
extern struct anon_vma *page_anon_vma(struct page *page);
extern struct address_space *page_mapping(struct page *page);

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;
}

/*
 * 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;
}

bool page_mapped(struct page *page);
struct address_space *page_mapping(struct page *page);

/*
 * Return true only if the page has been allocated with
 * ALLOC_NO_WATERMARKS and the low watermark was not
 * met implying that the system is under some pressure.
 */
static inline bool page_is_pfmemalloc(struct page *page)
{
        /*
         * Page index cannot be this large so this must be
         * a pfmemalloc page.
         */
        return page->index == -1UL;
}

/*
 * Only to be called by the page allocator on a freshly allocated
 * page.
 */
static inline void set_page_pfmemalloc(struct page *page)
{
        page->index = -1UL;
}

static inline void clear_page_pfmemalloc(struct page *page)
{
        page->index = 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_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_DAX_LOCKED 0x1000      /* ->fault has locked DAX entry */

#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 bool 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 */
        bool ignore_dirty;                      /* Ignore dirty pages */
        bool check_swap_entries;                /* Check also swap entries */
};

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

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,
                            bool *unlocked);
#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, bool *unlocked)
{
        /* 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_remote(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(unsigned long start, unsigned long nr_pages,
                            int write, int force, struct page **pages,
                            struct vm_area_struct **vmas);
long get_user_pages_locked(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(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);

/* Container for pinned pfns / pages */
struct frame_vector {
        unsigned int nr_allocated;      /* Number of frames we have space for */
        unsigned int nr_frames; /* Number of frames stored in ptrs array */
        bool got_ref;           /* Did we pin pages by getting page ref? */
        bool is_pfns;           /* Does array contain pages or pfns? */
        void *ptrs[0];          /* Array of pinned pfns / pages. Use
                                 * pfns_vector_pages() or pfns_vector_pfns()
                                 * for access */
};

struct frame_vector *frame_vector_create(unsigned int nr_frames);
void frame_vector_destroy(struct frame_vector *vec);
int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
                     bool write, bool force, struct frame_vector *vec);
void put_vaddr_frames(struct frame_vector *vec);
int frame_vector_to_pages(struct frame_vector *vec);
void frame_vector_to_pfns(struct frame_vector *vec);

static inline unsigned int frame_vector_count(struct frame_vector *vec)
{
        return vec->nr_frames;
}

static inline struct page **frame_vector_pages(struct frame_vector *vec)
{
        if (vec->is_pfns) {
                int err = frame_vector_to_pages(vec);

                if (err)
                        return ERR_PTR(err);
        }
        return (struct page **)(vec->ptrs);
}

static inline unsigned long *frame_vector_pfns(struct frame_vector *vec)
{
        if (!vec->is_pfns)
                frame_vector_to_pfns(vec);
        return (unsigned long *)(vec->ptrs);
}

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_cleaned(struct page *page, struct address_space *mapping,
                          struct bdi_writeback *wb);
int set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
void cancel_dirty_page(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 bool vma_is_anonymous(struct vm_area_struct *vma)
{
        return !vma->vm_ops;
}

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);
}

int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);

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]);
}

/* Optimized variant when page is already known not to be PageAnon */
static inline int mm_counter_file(struct page *page)
{
        if (PageSwapBacked(page))
                return MM_SHMEMPAGES;
        return MM_FILEPAGES;
}

static inline int mm_counter(struct page *page)
{
        if (PageAnon(page))
                return MM_ANONPAGES;
        return mm_counter_file(page);
}

static inline unsigned long get_mm_rss(struct mm_struct *mm)
{
        return get_mm_counter(mm, MM_FILEPAGES) +
                get_mm_counter(mm, MM_ANONPAGES) +
                get_mm_counter(mm, MM_SHMEMPAGES);
}

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

#ifndef __HAVE_ARCH_PTE_DEVMAP
static inline int pte_devmap(pte_t pte)
{
        return 0;
}
#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, 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, 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)
{
        if (!ptlock_init(page))
                return false;
        inc_zone_page_state(page, NR_PAGETABLE);
        return true;
}

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(mm, pmd, address)                     \
        (unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, pmd, address))

#define pte_alloc_map(mm, pmd, address)                 \
        (pte_alloc(mm, pmd, address) ? NULL : pte_offset_map(pmd, address))

#define pte_alloc_map_lock(mm, pmd, address, ptlp)      \
        (pte_alloc(mm, 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);

extern void reserve_bootmem_region(phys_addr_t start, phys_addr_t end);

/* 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,
                                        struct mminit_pfnnid_cache *state)
{
        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,
                                        struct mminit_pfnnid_cache *state);
#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 long si_mem_available(void);
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, unsigned 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;
extern int watermark_scale_factor;

/* 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 *, struct vm_userfaultfd_ctx);
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 bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
extern void vm_stat_account(struct mm_struct *, vm_flags_t, 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(struct file *file, unsigned long addr,
        unsigned long len, unsigned long prot, unsigned long flags,
        vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate);
extern int do_munmap(struct mm_struct *, unsigned long, size_t);

static inline 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)
{
        return do_mmap(file, addr, len, prot, flags, 0, pgoff, populate);
}

#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 int __must_check vm_brk(unsigned long, unsigned long);
extern int vm_munmap(unsigned long, size_t);
extern unsigned long __must_check 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_topdown(info);
        else
                return unmapped_area(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);

/* 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_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
                        unsigned long pfn, pgprot_t pgprot);
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
                        pfn_t 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_POPULATE   0x40    /* fault in page */
#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 */
#define FOLL_MLOCK      0x1000  /* lock present pages */
#define FOLL_REMOTE     0x2000  /* we are working on non-current tsk/mm */

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_PAGE_POISONING
extern bool page_poisoning_enabled(void);
extern void kernel_poison_pages(struct page *page, int numpages, int enable);
extern bool page_is_poisoned(struct page *page);
#else
static inline bool page_poisoning_enabled(void) { return false; }
static inline void kernel_poison_pages(struct page *page, int numpages,
                                        int enable) { }
static inline bool page_is_poisoned(struct page *page) { return false; }
#endif

#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   /* CONFIG_DEBUG_PAGEALLOC */
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 */
static inline bool debug_pagealloc_enabled(void)
{
        return false;
}
#endif  /* CONFIG_DEBUG_PAGEALLOC */

#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);
struct vmem_altmap;
void *__vmemmap_alloc_block_buf(unsigned long size, int node,
                struct vmem_altmap *altmap);
static inline void *vmemmap_alloc_block_buf(unsigned long size, int node)
{
        return __vmemmap_alloc_block_buf(size, node, NULL);
}

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 get_hwpoison_page(struct page *page);
#define put_hwpoison_page(page) put_page(page)
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);


/*
 * Error handlers for various types of pages.
 */
enum mf_result {
        MF_IGNORED,     /* Error: cannot be handled */
        MF_FAILED,      /* Error: handling failed */
        MF_DELAYED,     /* Will be handled later */
        MF_RECOVERED,   /* Successfully recovered */
};

enum mf_action_page_type {
        MF_MSG_KERNEL,
        MF_MSG_KERNEL_HIGH_ORDER,
        MF_MSG_SLAB,
        MF_MSG_DIFFERENT_COMPOUND,
        MF_MSG_POISONED_HUGE,
        MF_MSG_HUGE,
        MF_MSG_FREE_HUGE,
        MF_MSG_UNMAP_FAILED,
        MF_MSG_DIRTY_SWAPCACHE,
        MF_MSG_CLEAN_SWAPCACHE,
        MF_MSG_DIRTY_MLOCKED_LRU,
        MF_MSG_CLEAN_MLOCKED_LRU,
        MF_MSG_DIRTY_UNEVICTABLE_LRU,
        MF_MSG_CLEAN_UNEVICTABLE_LRU,
        MF_MSG_DIRTY_LRU,
        MF_MSG_CLEAN_LRU,
        MF_MSG_TRUNCATED_LRU,
        MF_MSG_BUDDY,
        MF_MSG_BUDDY_2ND,
        MF_MSG_UNKNOWN,
};

#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);
        if (unlikely(!page_ext))
                return false;

        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 */