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 extern struct kmem_cache *anon_vma_cachep;
  43
  44 static inline struct anon_vma *anon_vma_alloc(void)
  45 {
  46         return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
  47 }
  48
  49 static inline void anon_vma_free(struct anon_vma *anon_vma)
  50 {
  51         kmem_cache_free(anon_vma_cachep, anon_vma);
  52 }
  53
  54 static inline void anon_vma_lock(struct vm_area_struct *vma)
  55 {
  56         struct anon_vma *anon_vma = vma->anon_vma;
  57         if (anon_vma)
  58                 spin_lock(&anon_vma->lock);
  59 }
  60
  61 static inline void anon_vma_unlock(struct vm_area_struct *vma)
  62 {
  63         struct anon_vma *anon_vma = vma->anon_vma;
  64         if (anon_vma)
  65                 spin_unlock(&anon_vma->lock);
  66 }
  67
  68 /*
  69  * anon_vma helper functions.
  70  */
  71 void anon_vma_init(void);       /* create anon_vma_cachep */
  72 int  anon_vma_prepare(struct vm_area_struct *);
  73 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  74 void anon_vma_unlink(struct vm_area_struct *);
  75 void anon_vma_link(struct vm_area_struct *);
  76 void __anon_vma_link(struct vm_area_struct *);
  77
  78 /*
  79  * rmap interfaces called when adding or removing pte of page
  80  */
  81 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  82 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  83 void page_add_file_rmap(struct page *);
  84 void page_remove_rmap(struct page *, struct vm_area_struct *);
  85
  86 #ifdef CONFIG_DEBUG_VM
  87 void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address);
  88 #else
  89 static inline void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
  90 {
  91         atomic_inc(&page->_mapcount);
  92 }
  93 #endif
  94
  95 /*
  96  * Called from mm/vmscan.c to handle paging out
  97  */
  98 int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt);
  99 int try_to_unmap(struct page *, int ignore_refs);
 100
 101 /*
 102  * Called from mm/filemap_xip.c to unmap empty zero page
 103  */
 104 pte_t *page_check_address(struct page *, struct mm_struct *,
 105                                 unsigned long, spinlock_t **);
 106
 107 /*
 108  * Used by swapoff to help locate where page is expected in vma.
 109  */
 110 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 111
 112 /*
 113  * Cleans the PTEs of shared mappings.
 114  * (and since clean PTEs should also be readonly, write protects them too)
 115  *
 116  * returns the number of cleaned PTEs.
 117  */
 118 int page_mkclean(struct page *);
 119
 120 #else   /* !CONFIG_MMU */
 121
 122 #define anon_vma_init()         do {} while (0)
 123 #define anon_vma_prepare(vma)   (0)
 124 #define anon_vma_link(vma)      do {} while (0)
 125
 126 #define page_referenced(page,l,cnt) TestClearPageReferenced(page)
 127 #define try_to_unmap(page, refs) SWAP_FAIL
 128
 129 static inline int page_mkclean(struct page *page)
 130 {
 131         return 0;
 132 }
 133
 134
 135 #endif  /* CONFIG_MMU */
 136
 137 /*
 138  * Return values of try_to_unmap
 139  */
 140 #define SWAP_SUCCESS    0
 141 #define SWAP_AGAIN      1
 142 #define SWAP_FAIL       2
 143
 144 #endif  /* _LINUX_RMAP_H */