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 */
30 atomic_t ksm_refcount;
32 #ifdef CONFIG_MIGRATION
33 atomic_t migrate_refcount;
36 * NOTE: the LSB of the head.next is set by
37 * mm_take_all_locks() _after_ taking the above lock. So the
38 * head must only be read/written after taking the above lock
39 * to be sure to see a valid next pointer. The LSB bit itself
40 * is serialized by a system wide lock only visible to
41 * mm_take_all_locks() (mm_all_locks_mutex).
43 struct list_head head; /* Chain of private "related" vmas */
47 * The copy-on-write semantics of fork mean that an anon_vma
48 * can become associated with multiple processes. Furthermore,
49 * each child process will have its own anon_vma, where new
50 * pages for that process are instantiated.
52 * This structure allows us to find the anon_vmas associated
53 * with a VMA, or the VMAs associated with an anon_vma.
54 * The "same_vma" list contains the anon_vma_chains linking
55 * all the anon_vmas associated with this VMA.
56 * The "same_anon_vma" list contains the anon_vma_chains
57 * which link all the VMAs associated with this anon_vma.
59 struct anon_vma_chain {
60 struct vm_area_struct *vma;
61 struct anon_vma *anon_vma;
62 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
63 struct list_head same_anon_vma; /* locked by anon_vma->lock */
68 static inline void ksm_refcount_init(struct anon_vma *anon_vma)
70 atomic_set(&anon_vma->ksm_refcount, 0);
73 static inline int ksm_refcount(struct anon_vma *anon_vma)
75 return atomic_read(&anon_vma->ksm_refcount);
78 static inline void ksm_refcount_init(struct anon_vma *anon_vma)
82 static inline int ksm_refcount(struct anon_vma *anon_vma)
86 #endif /* CONFIG_KSM */
87 #ifdef CONFIG_MIGRATION
88 static inline void migrate_refcount_init(struct anon_vma *anon_vma)
90 atomic_set(&anon_vma->migrate_refcount, 0);
93 static inline int migrate_refcount(struct anon_vma *anon_vma)
95 return atomic_read(&anon_vma->migrate_refcount);
98 static inline void migrate_refcount_init(struct anon_vma *anon_vma)
102 static inline int migrate_refcount(struct anon_vma *anon_vma)
106 #endif /* CONFIG_MIGRATE */
108 static inline struct anon_vma *page_anon_vma(struct page *page)
110 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
113 return page_rmapping(page);
116 static inline void anon_vma_lock(struct vm_area_struct *vma)
118 struct anon_vma *anon_vma = vma->anon_vma;
120 spin_lock(&anon_vma->lock);
123 static inline void anon_vma_unlock(struct vm_area_struct *vma)
125 struct anon_vma *anon_vma = vma->anon_vma;
127 spin_unlock(&anon_vma->lock);
131 * anon_vma helper functions.
133 void anon_vma_init(void); /* create anon_vma_cachep */
134 int anon_vma_prepare(struct vm_area_struct *);
135 void unlink_anon_vmas(struct vm_area_struct *);
136 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
137 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
138 void __anon_vma_link(struct vm_area_struct *);
139 void anon_vma_free(struct anon_vma *);
141 static inline void anon_vma_merge(struct vm_area_struct *vma,
142 struct vm_area_struct *next)
144 VM_BUG_ON(vma->anon_vma != next->anon_vma);
145 unlink_anon_vmas(next);
149 * rmap interfaces called when adding or removing pte of page
151 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
152 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
153 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
154 void page_add_file_rmap(struct page *);
155 void page_remove_rmap(struct page *);
157 static inline void page_dup_rmap(struct page *page)
159 atomic_inc(&page->_mapcount);
163 * Called from mm/vmscan.c to handle paging out
165 int page_referenced(struct page *, int is_locked,
166 struct mem_cgroup *cnt, unsigned long *vm_flags);
167 int page_referenced_one(struct page *, struct vm_area_struct *,
168 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
171 TTU_UNMAP = 0, /* unmap mode */
172 TTU_MIGRATION = 1, /* migration mode */
173 TTU_MUNLOCK = 2, /* munlock mode */
174 TTU_ACTION_MASK = 0xff,
176 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
177 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
178 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
180 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
182 int try_to_unmap(struct page *, enum ttu_flags flags);
183 int try_to_unmap_one(struct page *, struct vm_area_struct *,
184 unsigned long address, enum ttu_flags flags);
187 * Called from mm/filemap_xip.c to unmap empty zero page
189 pte_t *page_check_address(struct page *, struct mm_struct *,
190 unsigned long, spinlock_t **, int);
193 * Used by swapoff to help locate where page is expected in vma.
195 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
198 * Cleans the PTEs of shared mappings.
199 * (and since clean PTEs should also be readonly, write protects them too)
201 * returns the number of cleaned PTEs.
203 int page_mkclean(struct page *);
206 * called in munlock()/munmap() path to check for other vmas holding
209 int try_to_munlock(struct page *);
212 * Called by memory-failure.c to kill processes.
214 struct anon_vma *page_lock_anon_vma(struct page *page);
215 void page_unlock_anon_vma(struct anon_vma *anon_vma);
216 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
219 * Called by migrate.c to remove migration ptes, but might be used more later.
221 int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
222 struct vm_area_struct *, unsigned long, void *), void *arg);
224 #else /* !CONFIG_MMU */
226 #define anon_vma_init() do {} while (0)
227 #define anon_vma_prepare(vma) (0)
228 #define anon_vma_link(vma) do {} while (0)
230 static inline int page_referenced(struct page *page, int is_locked,
231 struct mem_cgroup *cnt,
232 unsigned long *vm_flags)
238 #define try_to_unmap(page, refs) SWAP_FAIL
240 static inline int page_mkclean(struct page *page)
246 #endif /* CONFIG_MMU */
249 * Return values of try_to_unmap
251 #define SWAP_SUCCESS 0
256 #endif /* _LINUX_RMAP_H */