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 * Count of child anon_vmas and VMAs which points to this anon_vma.
42 * This counter is used for making decision about reusing anon_vma
43 * instead of forking new one. See comments in function anon_vma_clone.
47 struct anon_vma *parent; /* Parent of this anon_vma */
50 * NOTE: the LSB of the rb_root.rb_node is set by
51 * mm_take_all_locks() _after_ taking the above lock. So the
52 * rb_root must only be read/written after taking the above lock
53 * to be sure to see a valid next pointer. The LSB bit itself
54 * is serialized by a system wide lock only visible to
55 * mm_take_all_locks() (mm_all_locks_mutex).
57 struct rb_root rb_root; /* Interval tree of private "related" vmas */
61 * The copy-on-write semantics of fork mean that an anon_vma
62 * can become associated with multiple processes. Furthermore,
63 * each child process will have its own anon_vma, where new
64 * pages for that process are instantiated.
66 * This structure allows us to find the anon_vmas associated
67 * with a VMA, or the VMAs associated with an anon_vma.
68 * The "same_vma" list contains the anon_vma_chains linking
69 * all the anon_vmas associated with this VMA.
70 * The "rb" field indexes on an interval tree the anon_vma_chains
71 * which link all the VMAs associated with this anon_vma.
73 struct anon_vma_chain {
74 struct vm_area_struct *vma;
75 struct anon_vma *anon_vma;
76 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
77 struct rb_node rb; /* locked by anon_vma->rwsem */
78 unsigned long rb_subtree_last;
79 #ifdef CONFIG_DEBUG_VM_RB
80 unsigned long cached_vma_start, cached_vma_last;
85 TTU_UNMAP = 1, /* unmap mode */
86 TTU_MIGRATION = 2, /* migration mode */
87 TTU_MUNLOCK = 4, /* munlock mode */
89 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
90 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
91 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
92 TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible
93 * and caller guarantees they will
94 * do a final flush if necessary */
98 static inline void get_anon_vma(struct anon_vma *anon_vma)
100 atomic_inc(&anon_vma->refcount);
103 void __put_anon_vma(struct anon_vma *anon_vma);
105 static inline void put_anon_vma(struct anon_vma *anon_vma)
107 if (atomic_dec_and_test(&anon_vma->refcount))
108 __put_anon_vma(anon_vma);
111 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
113 down_write(&anon_vma->root->rwsem);
116 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
118 up_write(&anon_vma->root->rwsem);
121 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
123 down_read(&anon_vma->root->rwsem);
126 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
128 up_read(&anon_vma->root->rwsem);
133 * anon_vma helper functions.
135 void anon_vma_init(void); /* create anon_vma_cachep */
136 int anon_vma_prepare(struct vm_area_struct *);
137 void unlink_anon_vmas(struct vm_area_struct *);
138 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
139 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
141 static inline void anon_vma_merge(struct vm_area_struct *vma,
142 struct vm_area_struct *next)
144 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
145 unlink_anon_vmas(next);
148 struct anon_vma *page_get_anon_vma(struct page *page);
151 * rmap interfaces called when adding or removing pte of page
153 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
154 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
155 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
157 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
158 void page_add_file_rmap(struct page *);
159 void page_remove_rmap(struct page *);
161 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
163 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
166 static inline void page_dup_rmap(struct page *page)
168 atomic_inc(&page->_mapcount);
172 * Called from mm/vmscan.c to handle paging out
174 int page_referenced(struct page *, int is_locked,
175 struct mem_cgroup *memcg, unsigned long *vm_flags);
177 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
179 int try_to_unmap(struct page *, enum ttu_flags flags);
182 * Used by uprobes to replace a userspace page safely
184 pte_t *__page_check_address(struct page *, struct mm_struct *,
185 unsigned long, spinlock_t **, int);
187 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
188 unsigned long address,
189 spinlock_t **ptlp, int sync)
193 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
199 * Used by swapoff to help locate where page is expected in vma.
201 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
204 * Cleans the PTEs of shared mappings.
205 * (and since clean PTEs should also be readonly, write protects them too)
207 * returns the number of cleaned PTEs.
209 int page_mkclean(struct page *);
212 * called in munlock()/munmap() path to check for other vmas holding
215 int try_to_munlock(struct page *);
218 * Called by memory-failure.c to kill processes.
220 struct anon_vma *page_lock_anon_vma_read(struct page *page);
221 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
222 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
225 * rmap_walk_control: To control rmap traversing for specific needs
227 * arg: passed to rmap_one() and invalid_vma()
228 * rmap_one: executed on each vma where page is mapped
229 * done: for checking traversing termination condition
230 * anon_lock: for getting anon_lock by optimized way rather than default
231 * invalid_vma: for skipping uninterested vma
233 struct rmap_walk_control {
235 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
236 unsigned long addr, void *arg);
237 int (*done)(struct page *page);
238 struct anon_vma *(*anon_lock)(struct page *page);
239 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
242 int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
244 #else /* !CONFIG_MMU */
246 #define anon_vma_init() do {} while (0)
247 #define anon_vma_prepare(vma) (0)
248 #define anon_vma_link(vma) do {} while (0)
250 static inline int page_referenced(struct page *page, int is_locked,
251 struct mem_cgroup *memcg,
252 unsigned long *vm_flags)
258 #define try_to_unmap(page, refs) SWAP_FAIL
260 static inline int page_mkclean(struct page *page)
266 #endif /* CONFIG_MMU */
269 * Return values of try_to_unmap
271 #define SWAP_SUCCESS 0
276 #endif /* _LINUX_RMAP_H */