4 * Declarations for Reverse Mapping functions in mm/rmap.c
7 #include <linux/list.h>
8 #include <linux/slab.h>
10 #include <linux/spinlock.h>
11 #include <linux/memcontrol.h>
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.
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.
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.
28 spinlock_t lock; /* Serialize access to vma list */
29 struct anon_vma *root; /* Root of this anon_vma tree */
30 #if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
33 * The external_refcount is taken by either KSM or page migration
34 * to take a reference to an anon_vma when there is no
35 * guarantee that the vma of page tables will exist for
36 * the duration of the operation. A caller that takes
37 * the reference is responsible for clearing up the
38 * anon_vma if they are the last user on release
40 atomic_t external_refcount;
43 * NOTE: the LSB of the head.next is set by
44 * mm_take_all_locks() _after_ taking the above lock. So the
45 * head must only be read/written after taking the above lock
46 * to be sure to see a valid next pointer. The LSB bit itself
47 * is serialized by a system wide lock only visible to
48 * mm_take_all_locks() (mm_all_locks_mutex).
50 struct list_head head; /* Chain of private "related" vmas */
54 * The copy-on-write semantics of fork mean that an anon_vma
55 * can become associated with multiple processes. Furthermore,
56 * each child process will have its own anon_vma, where new
57 * pages for that process are instantiated.
59 * This structure allows us to find the anon_vmas associated
60 * with a VMA, or the VMAs associated with an anon_vma.
61 * The "same_vma" list contains the anon_vma_chains linking
62 * all the anon_vmas associated with this VMA.
63 * The "same_anon_vma" list contains the anon_vma_chains
64 * which link all the VMAs associated with this anon_vma.
66 struct anon_vma_chain {
67 struct vm_area_struct *vma;
68 struct anon_vma *anon_vma;
69 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
70 struct list_head same_anon_vma; /* locked by anon_vma->lock */
74 #if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
75 static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
77 atomic_set(&anon_vma->external_refcount, 0);
80 static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
82 return atomic_read(&anon_vma->external_refcount);
85 static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
89 static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
93 #endif /* CONFIG_KSM */
95 static inline struct anon_vma *page_anon_vma(struct page *page)
97 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
100 return page_rmapping(page);
103 static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
105 struct anon_vma *anon_vma = vma->anon_vma;
107 spin_lock(&anon_vma->root->lock);
110 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
112 struct anon_vma *anon_vma = vma->anon_vma;
114 spin_unlock(&anon_vma->root->lock);
117 static inline void anon_vma_lock(struct anon_vma *anon_vma)
119 spin_lock(&anon_vma->root->lock);
122 static inline void anon_vma_unlock(struct anon_vma *anon_vma)
124 spin_unlock(&anon_vma->root->lock);
128 * anon_vma helper functions.
130 void anon_vma_init(void); /* create anon_vma_cachep */
131 int anon_vma_prepare(struct vm_area_struct *);
132 void unlink_anon_vmas(struct vm_area_struct *);
133 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
134 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
135 void __anon_vma_link(struct vm_area_struct *);
136 void anon_vma_free(struct anon_vma *);
138 static inline void anon_vma_merge(struct vm_area_struct *vma,
139 struct vm_area_struct *next)
141 VM_BUG_ON(vma->anon_vma != next->anon_vma);
142 unlink_anon_vmas(next);
146 * rmap interfaces called when adding or removing pte of page
148 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
149 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
150 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
151 void page_add_file_rmap(struct page *);
152 void page_remove_rmap(struct page *);
154 static inline void page_dup_rmap(struct page *page)
156 atomic_inc(&page->_mapcount);
160 * Called from mm/vmscan.c to handle paging out
162 int page_referenced(struct page *, int is_locked,
163 struct mem_cgroup *cnt, unsigned long *vm_flags);
164 int page_referenced_one(struct page *, struct vm_area_struct *,
165 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
168 TTU_UNMAP = 0, /* unmap mode */
169 TTU_MIGRATION = 1, /* migration mode */
170 TTU_MUNLOCK = 2, /* munlock mode */
171 TTU_ACTION_MASK = 0xff,
173 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
174 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
175 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
177 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
179 int try_to_unmap(struct page *, enum ttu_flags flags);
180 int try_to_unmap_one(struct page *, struct vm_area_struct *,
181 unsigned long address, enum ttu_flags flags);
184 * Called from mm/filemap_xip.c to unmap empty zero page
186 pte_t *page_check_address(struct page *, struct mm_struct *,
187 unsigned long, spinlock_t **, int);
190 * Used by swapoff to help locate where page is expected in vma.
192 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
195 * Cleans the PTEs of shared mappings.
196 * (and since clean PTEs should also be readonly, write protects them too)
198 * returns the number of cleaned PTEs.
200 int page_mkclean(struct page *);
203 * called in munlock()/munmap() path to check for other vmas holding
206 int try_to_munlock(struct page *);
209 * Called by memory-failure.c to kill processes.
211 struct anon_vma *page_lock_anon_vma(struct page *page);
212 void page_unlock_anon_vma(struct anon_vma *anon_vma);
213 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
216 * Called by migrate.c to remove migration ptes, but might be used more later.
218 int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
219 struct vm_area_struct *, unsigned long, void *), void *arg);
221 #else /* !CONFIG_MMU */
223 #define anon_vma_init() do {} while (0)
224 #define anon_vma_prepare(vma) (0)
225 #define anon_vma_link(vma) do {} while (0)
227 static inline int page_referenced(struct page *page, int is_locked,
228 struct mem_cgroup *cnt,
229 unsigned long *vm_flags)
235 #define try_to_unmap(page, refs) SWAP_FAIL
237 static inline int page_mkclean(struct page *page)
243 #endif /* CONFIG_MMU */
246 * Return values of try_to_unmap
248 #define SWAP_SUCCESS 0
253 #endif /* _LINUX_RMAP_H */