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