4 * Declarations for Reverse Mapping functions in mm/rmap.c
7 #include <linux/list.h>
8 #include <linux/slab.h>
10 #include <linux/rwsem.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 struct anon_vma *root; /* Root of this anon_vma tree */
29 struct rw_semaphore rwsem; /* W: modification, R: walking the list */
31 * The refcount is taken on an anon_vma when there is no
32 * guarantee that the vma of page tables will exist for
33 * the duration of the operation. A caller that takes
34 * the reference is responsible for clearing up the
35 * anon_vma if they are the last user on release
40 * NOTE: the LSB of the rb_root.rb_node is set by
41 * mm_take_all_locks() _after_ taking the above lock. So the
42 * rb_root must only be read/written after taking the above lock
43 * to be sure to see a valid next pointer. The LSB bit itself
44 * is serialized by a system wide lock only visible to
45 * mm_take_all_locks() (mm_all_locks_mutex).
47 struct rb_root rb_root; /* Interval tree of private "related" vmas */
51 * The copy-on-write semantics of fork mean that an anon_vma
52 * can become associated with multiple processes. Furthermore,
53 * each child process will have its own anon_vma, where new
54 * pages for that process are instantiated.
56 * This structure allows us to find the anon_vmas associated
57 * with a VMA, or the VMAs associated with an anon_vma.
58 * The "same_vma" list contains the anon_vma_chains linking
59 * all the anon_vmas associated with this VMA.
60 * The "rb" field indexes on an interval tree the anon_vma_chains
61 * which link all the VMAs associated with this anon_vma.
63 struct anon_vma_chain {
64 struct vm_area_struct *vma;
65 struct anon_vma *anon_vma;
66 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
67 struct rb_node rb; /* locked by anon_vma->rwsem */
68 unsigned long rb_subtree_last;
69 #ifdef CONFIG_DEBUG_VM_RB
70 unsigned long cached_vma_start, cached_vma_last;
75 TTU_UNMAP = 1, /* unmap mode */
76 TTU_MIGRATION = 2, /* migration mode */
77 TTU_MUNLOCK = 4, /* munlock mode */
79 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
80 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
81 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
85 static inline void get_anon_vma(struct anon_vma *anon_vma)
87 atomic_inc(&anon_vma->refcount);
90 void __put_anon_vma(struct anon_vma *anon_vma);
92 static inline void put_anon_vma(struct anon_vma *anon_vma)
94 if (atomic_dec_and_test(&anon_vma->refcount))
95 __put_anon_vma(anon_vma);
98 static inline struct anon_vma *page_anon_vma(struct page *page)
100 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
103 return page_rmapping(page);
106 static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
108 struct anon_vma *anon_vma = vma->anon_vma;
110 down_write(&anon_vma->root->rwsem);
113 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
115 struct anon_vma *anon_vma = vma->anon_vma;
117 up_write(&anon_vma->root->rwsem);
120 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
122 down_write(&anon_vma->root->rwsem);
125 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
127 up_write(&anon_vma->root->rwsem);
130 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
132 down_read(&anon_vma->root->rwsem);
135 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
137 up_read(&anon_vma->root->rwsem);
142 * anon_vma helper functions.
144 void anon_vma_init(void); /* create anon_vma_cachep */
145 int anon_vma_prepare(struct vm_area_struct *);
146 void unlink_anon_vmas(struct vm_area_struct *);
147 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
148 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
150 static inline void anon_vma_merge(struct vm_area_struct *vma,
151 struct vm_area_struct *next)
153 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
154 unlink_anon_vmas(next);
157 struct anon_vma *page_get_anon_vma(struct page *page);
160 * rmap interfaces called when adding or removing pte of page
162 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
163 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
164 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
166 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
167 void page_add_file_rmap(struct page *);
168 void page_remove_rmap(struct page *);
170 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
172 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
175 static inline void page_dup_rmap(struct page *page)
177 atomic_inc(&page->_mapcount);
181 * Called from mm/vmscan.c to handle paging out
183 int page_referenced(struct page *, int is_locked,
184 struct mem_cgroup *memcg, unsigned long *vm_flags);
186 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
188 int try_to_unmap(struct page *, enum ttu_flags flags);
191 * Called from mm/filemap_xip.c to unmap empty zero page
193 pte_t *__page_check_address(struct page *, struct mm_struct *,
194 unsigned long, spinlock_t **, int);
196 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
197 unsigned long address,
198 spinlock_t **ptlp, int sync)
202 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
208 * Used by swapoff to help locate where page is expected in vma.
210 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
213 * Cleans the PTEs of shared mappings.
214 * (and since clean PTEs should also be readonly, write protects them too)
216 * returns the number of cleaned PTEs.
218 int page_mkclean(struct page *);
221 * called in munlock()/munmap() path to check for other vmas holding
224 int try_to_munlock(struct page *);
227 * Called by memory-failure.c to kill processes.
229 struct anon_vma *page_lock_anon_vma_read(struct page *page);
230 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
231 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
234 * rmap_walk_control: To control rmap traversing for specific needs
236 * arg: passed to rmap_one() and invalid_vma()
237 * rmap_one: executed on each vma where page is mapped
238 * done: for checking traversing termination condition
239 * file_nonlinear: for handling file nonlinear mapping
240 * anon_lock: for getting anon_lock by optimized way rather than default
241 * invalid_vma: for skipping uninterested vma
243 struct rmap_walk_control {
245 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
246 unsigned long addr, void *arg);
247 int (*done)(struct page *page);
248 int (*file_nonlinear)(struct page *, struct address_space *, void *arg);
249 struct anon_vma *(*anon_lock)(struct page *page);
250 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
253 int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
255 #else /* !CONFIG_MMU */
257 #define anon_vma_init() do {} while (0)
258 #define anon_vma_prepare(vma) (0)
259 #define anon_vma_link(vma) do {} while (0)
261 static inline int page_referenced(struct page *page, int is_locked,
262 struct mem_cgroup *memcg,
263 unsigned long *vm_flags)
269 #define try_to_unmap(page, refs) SWAP_FAIL
271 static inline int page_mkclean(struct page *page)
277 #endif /* CONFIG_MMU */
280 * Return values of try_to_unmap
282 #define SWAP_SUCCESS 0
287 #endif /* _LINUX_RMAP_H */