Initial import

1 files changed, 2227 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
new file mode 100644
index 000000000..ffe4ecf89
--- /dev/null
+++ b/include/linux/mm.h
@@ -0,0 +1,2227 @@
+#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);
+
+	/* 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))
+
+/* 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);
+}
+
+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);
+}
+
+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
+
+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;
+}
+
+/*
+ * 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 void vma_do_file_update_time(struct vm_area_struct *, const char[], int);
+extern struct file *vma_do_pr_or_file(struct vm_area_struct *, const char[],
+				      int);
+extern void vma_do_get_file(struct vm_area_struct *, const char[], int);
+extern void vma_do_fput(struct vm_area_struct *, const char[], int);
+
+#define vma_file_update_time(vma)	vma_do_file_update_time(vma, __func__, \
+								__LINE__)
+#define vma_pr_or_file(vma)		vma_do_pr_or_file(vma, __func__, \
+							  __LINE__)
+#define vma_get_file(vma)		vma_do_get_file(vma, __func__, __LINE__)
+#define vma_fput(vma)			vma_do_fput(vma, __func__, __LINE__)
+
+#ifndef CONFIG_MMU
+extern struct file *vmr_do_pr_or_file(struct vm_region *, const char[], int);
+extern void vmr_do_fput(struct vm_region *, const char[], int);
+
+#define vmr_pr_or_file(region)		vmr_do_pr_or_file(region, __func__, \
+							  __LINE__)
+#define vmr_fput(region)		vmr_do_fput(region, __func__, __LINE__)
+#endif /* !CONFIG_MMU */
+
+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);
+void account_page_cleaned(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_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);
+
+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_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 */
+
+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_pagecache(void);
+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 */