LXR linux/include/linux/rmap.h

   1#ifndef _LINUX_RMAP_H
   2#define _LINUX_RMAP_H
   3/*
   4 * Declarations for Reverse Mapping functions in mm/rmap.c
   5 */
   6
   7#include <linux/list.h>
   8#include <linux/slab.h>
   9#include <linux/mm.h>
  10#include <linux/spinlock.h>
  11#include <linux/memcontrol.h>
  12
  13/*
  14 * The anon_vma heads a list of private "related" vmas, to scan if
  15 * an anonymous page pointing to this anon_vma needs to be unmapped:
  16 * the vmas on the list will be related by forking, or by splitting.
  17 *
  18 * Since vmas come and go as they are split and merged (particularly
  19 * in mprotect), the mapping field of an anonymous page cannot point
  20 * directly to a vma: instead it points to an anon_vma, on whose list
  21 * the related vmas can be easily linked or unlinked.
  22 *
  23 * After unlinking the last vma on the list, we must garbage collect
  24 * the anon_vma object itself: we're guaranteed no page can be
  25 * pointing to this anon_vma once its vma list is empty.
  26 */
  27struct anon_vma {
  28        spinlock_t lock;        /* Serialize access to vma list */
  29        /*
  30         * NOTE: the LSB of the head.next is set by
  31         * mm_take_all_locks() _after_ taking the above lock. So the
  32         * head must only be read/written after taking the above lock
  33         * to be sure to see a valid next pointer. The LSB bit itself
  34         * is serialized by a system wide lock only visible to
  35         * mm_take_all_locks() (mm_all_locks_mutex).
  36         */
  37        struct list_head head;  /* List of private "related" vmas */
  38};
  39
  40#ifdef CONFIG_MMU
  41
  42static inline void anon_vma_lock(struct vm_area_struct *vma)
  43{
  44        struct anon_vma *anon_vma = vma->anon_vma;
  45        if (anon_vma)
  46                spin_lock(&anon_vma->lock);
  47}
  48
  49static inline void anon_vma_unlock(struct vm_area_struct *vma)
  50{
  51        struct anon_vma *anon_vma = vma->anon_vma;
  52        if (anon_vma)
  53                spin_unlock(&anon_vma->lock);
  54}
  55
  56/*
  57 * anon_vma helper functions.
  58 */
  59void anon_vma_init(void);       /* create anon_vma_cachep */
  60int  anon_vma_prepare(struct vm_area_struct *);
  61void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  62void anon_vma_unlink(struct vm_area_struct *);
  63void anon_vma_link(struct vm_area_struct *);
  64void __anon_vma_link(struct vm_area_struct *);
  65
  66/*
  67 * rmap interfaces called when adding or removing pte of page
  68 */
  69void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  70void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  71void page_add_file_rmap(struct page *);
  72void page_remove_rmap(struct page *);
  73
  74static inline void page_dup_rmap(struct page *page)
  75{
  76        atomic_inc(&page->_mapcount);
  77}
  78
  79/*
  80 * Called from mm/vmscan.c to handle paging out
  81 */
  82int page_referenced(struct page *, int is_locked,
  83                        struct mem_cgroup *cnt, unsigned long *vm_flags);
  84enum ttu_flags {
  85        TTU_UNMAP = 0,                  /* unmap mode */
  86        TTU_MIGRATION = 1,              /* migration mode */
  87        TTU_MUNLOCK = 2,                /* munlock mode */
  88        TTU_ACTION_MASK = 0xff,
  89
  90        TTU_IGNORE_MLOCK = (1 << 8),    /* ignore mlock */
  91        TTU_IGNORE_ACCESS = (1 << 9),   /* don't age */
  92        TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
  93};
  94#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
  95
  96int try_to_unmap(struct page *, enum ttu_flags flags);
  97
  98/*
  99 * Called from mm/filemap_xip.c to unmap empty zero page
 100 */
 101pte_t *page_check_address(struct page *, struct mm_struct *,
 102                                unsigned long, spinlock_t **, int);
 103
 104/*
 105 * Used by swapoff to help locate where page is expected in vma.
 106 */
 107unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 108
 109/*
 110 * Cleans the PTEs of shared mappings.
 111 * (and since clean PTEs should also be readonly, write protects them too)
 112 *
 113 * returns the number of cleaned PTEs.
 114 */
 115int page_mkclean(struct page *);
 116
 117/*
 118 * called in munlock()/munmap() path to check for other vmas holding
 119 * the page mlocked.
 120 */
 121int try_to_munlock(struct page *);
 122
 123/*
 124 * Called by memory-failure.c to kill processes.
 125 */
 126struct anon_vma *page_lock_anon_vma(struct page *page);
 127void page_unlock_anon_vma(struct anon_vma *anon_vma);
 128int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 129
 130#else   /* !CONFIG_MMU */
 131
 132#define anon_vma_init()         do {} while (0)
 133#define anon_vma_prepare(vma)   (0)
 134#define anon_vma_link(vma)      do {} while (0)
 135
 136static inline int page_referenced(struct page *page, int is_locked,
 137                                  struct mem_cgroup *cnt,
 138                                  unsigned long *vm_flags)
 139{
 140        *vm_flags = 0;
 141        return TestClearPageReferenced(page);
 142}
 143
 144#define try_to_unmap(page, refs) SWAP_FAIL
 145
 146static inline int page_mkclean(struct page *page)
 147{
 148        return 0;
 149}
 150
 151
 152#endif  /* CONFIG_MMU */
 153
 154/*
 155 * Return values of try_to_unmap
 156 */
 157#define SWAP_SUCCESS    0
 158#define SWAP_AGAIN      1
 159#define SWAP_FAIL       2
 160#define SWAP_MLOCK      3
 161
 162#endif  /* _LINUX_RMAP_H */
 163