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  */
  27 struct anon_vma {
  28         spinlock_t lock;        /* Serialize access to vma list */
  29 #ifdef CONFIG_KSM
  30         atomic_t ksm_refcount;
  31 #endif
  32         /*
  33          * NOTE: the LSB of the head.next is set by
  34          * mm_take_all_locks() _after_ taking the above lock. So the
  35          * head must only be read/written after taking the above lock
  36          * to be sure to see a valid next pointer. The LSB bit itself
  37          * is serialized by a system wide lock only visible to
  38          * mm_take_all_locks() (mm_all_locks_mutex).
  39          */
  40         struct list_head head;  /* List of private "related" vmas */
  41 };
  42
  43 #ifdef CONFIG_MMU
  44 #ifdef CONFIG_KSM
  45 static inline void ksm_refcount_init(struct anon_vma *anon_vma)
  46 {
  47         atomic_set(&anon_vma->ksm_refcount, 0);
  48 }
  49
  50 static inline int ksm_refcount(struct anon_vma *anon_vma)
  51 {
  52         return atomic_read(&anon_vma->ksm_refcount);
  53 }
  54 #else
  55 static inline void ksm_refcount_init(struct anon_vma *anon_vma)
  56 {
  57 }
  58
  59 static inline int ksm_refcount(struct anon_vma *anon_vma)
  60 {
  61         return 0;
  62 }
  63 #endif /* CONFIG_KSM */
  64
  65 static inline struct anon_vma *page_anon_vma(struct page *page)
  66 {
  67         if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
  68                                             PAGE_MAPPING_ANON)
  69                 return NULL;
  70         return page_rmapping(page);
  71 }
  72
  73 static inline void anon_vma_lock(struct vm_area_struct *vma)
  74 {
  75         struct anon_vma *anon_vma = vma->anon_vma;
  76         if (anon_vma)
  77                 spin_lock(&anon_vma->lock);
  78 }
  79
  80 static inline void anon_vma_unlock(struct vm_area_struct *vma)
  81 {
  82         struct anon_vma *anon_vma = vma->anon_vma;
  83         if (anon_vma)
  84                 spin_unlock(&anon_vma->lock);
  85 }
  86
  87 /*
  88  * anon_vma helper functions.
  89  */
  90 void anon_vma_init(void);       /* create anon_vma_cachep */
  91 int  anon_vma_prepare(struct vm_area_struct *);
  92 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  93 void anon_vma_unlink(struct vm_area_struct *);
  94 void anon_vma_link(struct vm_area_struct *);
  95 void __anon_vma_link(struct vm_area_struct *);
  96 void anon_vma_free(struct anon_vma *);
  97
  98 /*
  99  * rmap interfaces called when adding or removing pte of page
 100  */
 101 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 102 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 103 void page_add_file_rmap(struct page *);
 104 void page_remove_rmap(struct page *);
 105
 106 static inline void page_dup_rmap(struct page *page)
 107 {
 108         atomic_inc(&page->_mapcount);
 109 }
 110
 111 /*
 112  * Called from mm/vmscan.c to handle paging out
 113  */
 114 int page_referenced(struct page *, int is_locked,
 115                         struct mem_cgroup *cnt, unsigned long *vm_flags);
 116 int page_referenced_one(struct page *, struct vm_area_struct *,
 117         unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
 118
 119 enum ttu_flags {
 120         TTU_UNMAP = 0,                  /* unmap mode */
 121         TTU_MIGRATION = 1,              /* migration mode */
 122         TTU_MUNLOCK = 2,                /* munlock mode */
 123         TTU_ACTION_MASK = 0xff,
 124
 125         TTU_IGNORE_MLOCK = (1 << 8),    /* ignore mlock */
 126         TTU_IGNORE_ACCESS = (1 << 9),   /* don't age */
 127         TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
 128 };
 129 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
 130
 131 int try_to_unmap(struct page *, enum ttu_flags flags);
 132 int try_to_unmap_one(struct page *, struct vm_area_struct *,
 133                         unsigned long address, enum ttu_flags flags);
 134
 135 /*
 136  * Called from mm/filemap_xip.c to unmap empty zero page
 137  */
 138 pte_t *page_check_address(struct page *, struct mm_struct *,
 139                                 unsigned long, spinlock_t **, int);
 140
 141 /*
 142  * Used by swapoff to help locate where page is expected in vma.
 143  */
 144 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 145
 146 /*
 147  * Cleans the PTEs of shared mappings.
 148  * (and since clean PTEs should also be readonly, write protects them too)
 149  *
 150  * returns the number of cleaned PTEs.
 151  */
 152 int page_mkclean(struct page *);
 153
 154 /*
 155  * called in munlock()/munmap() path to check for other vmas holding
 156  * the page mlocked.
 157  */
 158 int try_to_munlock(struct page *);
 159
 160 /*
 161  * Called by memory-failure.c to kill processes.
 162  */
 163 struct anon_vma *page_lock_anon_vma(struct page *page);
 164 void page_unlock_anon_vma(struct anon_vma *anon_vma);
 165 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 166
 167 /*
 168  * Called by migrate.c to remove migration ptes, but might be used more later.
 169  */
 170 int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
 171                 struct vm_area_struct *, unsigned long, void *), void *arg);
 172
 173 #else   /* !CONFIG_MMU */
 174
 175 #define anon_vma_init()         do {} while (0)
 176 #define anon_vma_prepare(vma)   (0)
 177 #define anon_vma_link(vma)      do {} while (0)
 178
 179 static inline int page_referenced(struct page *page, int is_locked,
 180                                   struct mem_cgroup *cnt,
 181                                   unsigned long *vm_flags)
 182 {
 183         *vm_flags = 0;
 184         return TestClearPageReferenced(page);
 185 }
 186
 187 #define try_to_unmap(page, refs) SWAP_FAIL
 188
 189 static inline int page_mkclean(struct page *page)
 190 {
 191         return 0;
 192 }
 193
 194
 195 #endif  /* CONFIG_MMU */
 196
 197 /*
 198  * Return values of try_to_unmap
 199  */
 200 #define SWAP_SUCCESS    0
 201 #define SWAP_AGAIN      1
 202 #define SWAP_FAIL       2
 203 #define SWAP_MLOCK      3
 204
 205 #endif  /* _LINUX_RMAP_H */