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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/rwsem.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 : : struct anon_vma *root; /* Root of this anon_vma tree */
29 : : struct rw_semaphore rwsem; /* W: modification, R: walking the list */
30 : : /*
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
36 : : */
37 : : atomic_t refcount;
38 : :
39 : : /*
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).
46 : : */
47 : : struct rb_root rb_root; /* Interval tree of private "related" vmas */
48 : : };
49 : :
50 : : /*
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.
55 : : *
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.
62 : : */
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;
71 : : #endif
72 : : };
73 : :
74 : : enum ttu_flags {
75 : : TTU_UNMAP = 0, /* unmap mode */
76 : : TTU_MIGRATION = 1, /* migration mode */
77 : : TTU_MUNLOCK = 2, /* munlock mode */
78 : : TTU_ACTION_MASK = 0xff,
79 : :
80 : : TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
81 : : TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
82 : : TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
83 : : };
84 : :
85 : : #ifdef CONFIG_MMU
86 : : static inline void get_anon_vma(struct anon_vma *anon_vma)
87 : : {
88 : 12195924 : atomic_inc(&anon_vma->refcount);
89 : : }
90 : :
91 : : void __put_anon_vma(struct anon_vma *anon_vma);
92 : :
93 : : static inline void put_anon_vma(struct anon_vma *anon_vma)
94 : : {
95 [ # # # # : 12496024 : if (atomic_dec_and_test(&anon_vma->refcount))
+ # # +
- ]
96 : 12496050 : __put_anon_vma(anon_vma);
97 : : }
98 : :
99 : : static inline struct anon_vma *page_anon_vma(struct page *page)
100 : : {
101 [ # # ][ # # ]: 0 : if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
102 : : PAGE_MAPPING_ANON)
103 : : return NULL;
104 : : return page_rmapping(page);
105 : : }
106 : :
107 : : static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
108 : : {
109 : : struct anon_vma *anon_vma = vma->anon_vma;
110 [ + ]: 2013486 : if (anon_vma)
111 : 2013491 : down_write(&anon_vma->root->rwsem);
112 : : }
113 : :
114 : : static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
115 : : {
116 : : struct anon_vma *anon_vma = vma->anon_vma;
117 [ + - ]: 2013473 : if (anon_vma)
118 : 2013473 : up_write(&anon_vma->root->rwsem);
119 : : }
120 : :
121 : : static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
122 : : {
123 : 12990724 : down_write(&anon_vma->root->rwsem);
124 : : }
125 : :
126 : : static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
127 : : {
128 : 12990685 : up_write(&anon_vma->root->rwsem);
129 : : }
130 : :
131 : : static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
132 : : {
133 : 0 : down_read(&anon_vma->root->rwsem);
134 : : }
135 : :
136 : : static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
137 : : {
138 : 1 : up_read(&anon_vma->root->rwsem);
139 : : }
140 : :
141 : :
142 : : /*
143 : : * anon_vma helper functions.
144 : : */
145 : : void anon_vma_init(void); /* create anon_vma_cachep */
146 : : int anon_vma_prepare(struct vm_area_struct *);
147 : : void unlink_anon_vmas(struct vm_area_struct *);
148 : : int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
149 : : int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
150 : :
151 : : static inline void anon_vma_merge(struct vm_area_struct *vma,
152 : : struct vm_area_struct *next)
153 : : {
154 : : VM_BUG_ON(vma->anon_vma != next->anon_vma);
155 : 2708 : unlink_anon_vmas(next);
156 : : }
157 : :
158 : : struct anon_vma *page_get_anon_vma(struct page *page);
159 : :
160 : : /*
161 : : * rmap interfaces called when adding or removing pte of page
162 : : */
163 : : void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
164 : : void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
165 : : void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
166 : : unsigned long, int);
167 : : void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
168 : : void page_add_file_rmap(struct page *);
169 : : void page_remove_rmap(struct page *);
170 : :
171 : : void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
172 : : unsigned long);
173 : : void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
174 : : unsigned long);
175 : :
176 : : static inline void page_dup_rmap(struct page *page)
177 : : {
178 : 23541073 : atomic_inc(&page->_mapcount);
179 : : }
180 : :
181 : : /*
182 : : * Called from mm/vmscan.c to handle paging out
183 : : */
184 : : int page_referenced(struct page *, int is_locked,
185 : : struct mem_cgroup *memcg, unsigned long *vm_flags);
186 : : int page_referenced_one(struct page *, struct vm_area_struct *,
187 : : unsigned long address, void *arg);
188 : :
189 : : #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
190 : :
191 : : int try_to_unmap(struct page *, enum ttu_flags flags);
192 : : int try_to_unmap_one(struct page *, struct vm_area_struct *,
193 : : unsigned long address, void *arg);
194 : :
195 : : /*
196 : : * Called from mm/filemap_xip.c to unmap empty zero page
197 : : */
198 : : pte_t *__page_check_address(struct page *, struct mm_struct *,
199 : : unsigned long, spinlock_t **, int);
200 : :
201 : : static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
202 : : unsigned long address,
203 : : spinlock_t **ptlp, int sync)
204 : : {
205 : : pte_t *ptep;
206 : :
207 : 265427 : __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
208 : : ptlp, sync));
209 : : return ptep;
210 : : }
211 : :
212 : : /*
213 : : * Used by swapoff to help locate where page is expected in vma.
214 : : */
215 : : unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
216 : :
217 : : /*
218 : : * Cleans the PTEs of shared mappings.
219 : : * (and since clean PTEs should also be readonly, write protects them too)
220 : : *
221 : : * returns the number of cleaned PTEs.
222 : : */
223 : : int page_mkclean(struct page *);
224 : :
225 : : /*
226 : : * called in munlock()/munmap() path to check for other vmas holding
227 : : * the page mlocked.
228 : : */
229 : : int try_to_munlock(struct page *);
230 : :
231 : : /*
232 : : * Called by memory-failure.c to kill processes.
233 : : */
234 : : struct anon_vma *page_lock_anon_vma_read(struct page *page);
235 : : void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
236 : : int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
237 : :
238 : : /*
239 : : * rmap_walk_control: To control rmap traversing for specific needs
240 : : *
241 : : * arg: passed to rmap_one() and invalid_vma()
242 : : * rmap_one: executed on each vma where page is mapped
243 : : * done: for checking traversing termination condition
244 : : * file_nonlinear: for handling file nonlinear mapping
245 : : * anon_lock: for getting anon_lock by optimized way rather than default
246 : : * invalid_vma: for skipping uninterested vma
247 : : */
248 : : struct rmap_walk_control {
249 : : void *arg;
250 : : int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
251 : : unsigned long addr, void *arg);
252 : : int (*done)(struct page *page);
253 : : int (*file_nonlinear)(struct page *, struct address_space *, void *arg);
254 : : struct anon_vma *(*anon_lock)(struct page *page);
255 : : bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
256 : : };
257 : :
258 : : int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
259 : :
260 : : #else /* !CONFIG_MMU */
261 : :
262 : : #define anon_vma_init() do {} while (0)
263 : : #define anon_vma_prepare(vma) (0)
264 : : #define anon_vma_link(vma) do {} while (0)
265 : :
266 : : static inline int page_referenced(struct page *page, int is_locked,
267 : : struct mem_cgroup *memcg,
268 : : unsigned long *vm_flags)
269 : : {
270 : : *vm_flags = 0;
271 : : return 0;
272 : : }
273 : :
274 : : #define try_to_unmap(page, refs) SWAP_FAIL
275 : :
276 : : static inline int page_mkclean(struct page *page)
277 : : {
278 : : return 0;
279 : : }
280 : :
281 : :
282 : : #endif /* CONFIG_MMU */
283 : :
284 : : /*
285 : : * Return values of try_to_unmap
286 : : */
287 : : #define SWAP_SUCCESS 0
288 : : #define SWAP_AGAIN 1
289 : : #define SWAP_FAIL 2
290 : : #define SWAP_MLOCK 3
291 : :
292 : : #endif /* _LINUX_RMAP_H */
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