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         /*
  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
  42 static 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
  49 static 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  */
  59 void anon_vma_init(void);       /* create anon_vma_cachep */
  60 int  anon_vma_prepare(struct vm_area_struct *);
  61 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  62 void anon_vma_unlink(struct vm_area_struct *);
  63 void anon_vma_link(struct vm_area_struct *);
  64 void __anon_vma_link(struct vm_area_struct *);
  65
  66 /*
  67  * rmap interfaces called when adding or removing pte of page
  68  */
  69 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  70 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  71 void page_add_file_rmap(struct page *);
  72 void page_remove_rmap(struct page *);
  73
  74 static 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  */
  82 int page_referenced(struct page *, int is_locked,
  83                         struct mem_cgroup *cnt, unsigned long *vm_flags);
  84 int try_to_unmap(struct page *, int ignore_refs);
  85
  86 /*
  87  * Called from mm/filemap_xip.c to unmap empty zero page
  88  */
  89 pte_t *page_check_address(struct page *, struct mm_struct *,
  90                                 unsigned long, spinlock_t **, int);
  91
  92 /*
  93  * Used by swapoff to help locate where page is expected in vma.
  94  */
  95 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
  96
  97 /*
  98  * Cleans the PTEs of shared mappings.
  99  * (and since clean PTEs should also be readonly, write protects them too)
 100  *
 101  * returns the number of cleaned PTEs.
 102  */
 103 int page_mkclean(struct page *);
 104
 105 /*
 106  * called in munlock()/munmap() path to check for other vmas holding
 107  * the page mlocked.
 108  */
 109 int try_to_munlock(struct page *);
 110
 111 #else   /* !CONFIG_MMU */
 112
 113 #define anon_vma_init()         do {} while (0)
 114 #define anon_vma_prepare(vma)   (0)
 115 #define anon_vma_link(vma)      do {} while (0)
 116
 117 static inline int page_referenced(struct page *page, int is_locked,
 118                                   struct mem_cgroup *cnt,
 119                                   unsigned long *vm_flags)
 120 {
 121         *vm_flags = 0;
 122         return TestClearPageReferenced(page);
 123 }
 124
 125 #define try_to_unmap(page, refs) SWAP_FAIL
 126
 127 static inline int page_mkclean(struct page *page)
 128 {
 129         return 0;
 130 }
 131
 132
 133 #endif  /* CONFIG_MMU */
 134
 135 /*
 136  * Return values of try_to_unmap
 137  */
 138 #define SWAP_SUCCESS    0
 139 #define SWAP_AGAIN      1
 140 #define SWAP_FAIL       2
 141 #define SWAP_MLOCK      3
 142
 143 #endif  /* _LINUX_RMAP_H */