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
  66extern struct anon_vma *page_lock_anon_vma(struct page *page);
  67extern void page_unlock_anon_vma(struct anon_vma *anon_vma);
  68
  69/*
  70 * rmap interfaces called when adding or removing pte of page
  71 */
  72void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  73void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  74void page_add_file_rmap(struct page *);
  75void page_remove_rmap(struct page *, struct vm_area_struct *);
  76
  77#ifdef CONFIG_DEBUG_VM
  78void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address);
  79#else
  80static inline void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
  81{
  82        atomic_inc(&page->_mapcount);
  83}
  84#endif
  85
  86/*
  87 * Called from mm/vmscan.c to handle paging out
  88 */
  89int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt);
  90int try_to_unmap(struct page *, int ignore_refs);
  91
  92/*
  93 * Called from mm/filemap_xip.c to unmap empty zero page
  94 */
  95pte_t *page_check_address(struct page *, struct mm_struct *,
  96                                unsigned long, spinlock_t **, int);
  97
  98/*
  99 * Used by swapoff to help locate where page is expected in vma.
 100 */
 101unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 102
 103/*
 104 * Cleans the PTEs of shared mappings.
 105 * (and since clean PTEs should also be readonly, write protects them too)
 106 *
 107 * returns the number of cleaned PTEs.
 108 */
 109int page_mkclean(struct page *);
 110
 111#ifdef CONFIG_UNEVICTABLE_LRU
 112/*
 113 * called in munlock()/munmap() path to check for other vmas holding
 114 * the page mlocked.
 115 */
 116int try_to_munlock(struct page *);
 117#else
 118static inline int try_to_munlock(struct page *page)
 119{
 120        return 0;       /* a.k.a. SWAP_SUCCESS */
 121}
 122#endif
 123
 124#else   /* !CONFIG_MMU */
 125
 126#define anon_vma_init()         do {} while (0)
 127#define anon_vma_prepare(vma)   (0)
 128#define anon_vma_link(vma)      do {} while (0)
 129
 130#define page_referenced(page,l,cnt) TestClearPageReferenced(page)
 131#define try_to_unmap(page, refs) SWAP_FAIL
 132
 133static inline int page_mkclean(struct page *page)
 134{
 135        return 0;
 136}
 137
 138
 139#endif  /* CONFIG_MMU */
 140
 141/*
 142 * Return values of try_to_unmap
 143 */
 144#define SWAP_SUCCESS    0
 145#define SWAP_AGAIN      1
 146#define SWAP_FAIL       2
 147#define SWAP_MLOCK      3
 148
 149#endif  /* _LINUX_RMAP_H */
 150