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1da177e4
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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
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7#include <linux/list.h>
8#include <linux/slab.h>
9#include <linux/mm.h>
10#include <linux/spinlock.h>
bed7161a 11#include <linux/memcontrol.h>
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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 */
27struct anon_vma {
5c341ee1 28 struct anon_vma *root; /* Root of this anon_vma tree */
182fea8f 29 spinlock_t lock; /* Serialize access to vma list */
7f60c214
MG
30#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
31
32 /*
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
39 */
40 atomic_t external_refcount;
db114b83 41#endif
7906d00c
AA
42 /*
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).
49 */
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50 struct list_head head; /* Chain of private "related" vmas */
51};
52
53/*
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.
58 *
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.
65 */
66struct 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 */
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71};
72
73#ifdef CONFIG_MMU
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74#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
75static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
db114b83 76{
7f60c214 77 atomic_set(&anon_vma->external_refcount, 0);
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HD
78}
79
7f60c214 80static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
db114b83 81{
7f60c214 82 return atomic_read(&anon_vma->external_refcount);
db114b83 83}
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84
85static inline void get_anon_vma(struct anon_vma *anon_vma)
86{
87 atomic_inc(&anon_vma->external_refcount);
88}
89
90void drop_anon_vma(struct anon_vma *);
db114b83 91#else
7f60c214 92static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
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93{
94}
95
7f60c214 96static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
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97{
98 return 0;
99}
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100
101static inline void get_anon_vma(struct anon_vma *anon_vma)
102{
103}
104
105static inline void drop_anon_vma(struct anon_vma *anon_vma)
106{
107}
db114b83 108#endif /* CONFIG_KSM */
1da177e4 109
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110static inline struct anon_vma *page_anon_vma(struct page *page)
111{
112 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
113 PAGE_MAPPING_ANON)
114 return NULL;
115 return page_rmapping(page);
116}
117
bb4a340e 118static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
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119{
120 struct anon_vma *anon_vma = vma->anon_vma;
121 if (anon_vma)
012f1800 122 spin_lock(&anon_vma->root->lock);
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123}
124
bb4a340e 125static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
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126{
127 struct anon_vma *anon_vma = vma->anon_vma;
128 if (anon_vma)
012f1800 129 spin_unlock(&anon_vma->root->lock);
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130}
131
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132static inline void anon_vma_lock(struct anon_vma *anon_vma)
133{
012f1800 134 spin_lock(&anon_vma->root->lock);
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135}
136
137static inline void anon_vma_unlock(struct anon_vma *anon_vma)
138{
012f1800 139 spin_unlock(&anon_vma->root->lock);
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140}
141
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142/*
143 * anon_vma helper functions.
144 */
145void anon_vma_init(void); /* create anon_vma_cachep */
146int anon_vma_prepare(struct vm_area_struct *);
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147void unlink_anon_vmas(struct vm_area_struct *);
148int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
149int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
1da177e4 150void __anon_vma_link(struct vm_area_struct *);
db114b83 151void anon_vma_free(struct anon_vma *);
1da177e4 152
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153static inline void anon_vma_merge(struct vm_area_struct *vma,
154 struct vm_area_struct *next)
155{
156 VM_BUG_ON(vma->anon_vma != next->anon_vma);
157 unlink_anon_vmas(next);
158}
159
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160/*
161 * rmap interfaces called when adding or removing pte of page
162 */
c44b6743 163void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
1da177e4 164void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
ad8c2ee8
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165void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
166 unsigned long, int);
9617d95e 167void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
1da177e4 168void page_add_file_rmap(struct page *);
edc315fd 169void page_remove_rmap(struct page *);
1da177e4 170
0fe6e20b
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171void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
172 unsigned long);
173void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
174 unsigned long);
175
21333b2b 176static inline void page_dup_rmap(struct page *page)
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177{
178 atomic_inc(&page->_mapcount);
179}
180
181/*
182 * Called from mm/vmscan.c to handle paging out
183 */
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184int page_referenced(struct page *, int is_locked,
185 struct mem_cgroup *cnt, unsigned long *vm_flags);
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186int page_referenced_one(struct page *, struct vm_area_struct *,
187 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
188
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189enum ttu_flags {
190 TTU_UNMAP = 0, /* unmap mode */
191 TTU_MIGRATION = 1, /* migration mode */
192 TTU_MUNLOCK = 2, /* munlock mode */
193 TTU_ACTION_MASK = 0xff,
194
195 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
196 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
888b9f7c 197 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
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198};
199#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
200
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201bool is_vma_temporary_stack(struct vm_area_struct *vma);
202
14fa31b8 203int try_to_unmap(struct page *, enum ttu_flags flags);
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204int try_to_unmap_one(struct page *, struct vm_area_struct *,
205 unsigned long address, enum ttu_flags flags);
1da177e4 206
ceffc078
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207/*
208 * Called from mm/filemap_xip.c to unmap empty zero page
209 */
e9a81a82 210pte_t *__page_check_address(struct page *, struct mm_struct *,
479db0bf 211 unsigned long, spinlock_t **, int);
ceffc078 212
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213static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
214 unsigned long address,
215 spinlock_t **ptlp, int sync)
216{
217 pte_t *ptep;
218
219 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
220 ptlp, sync));
221 return ptep;
222}
223
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224/*
225 * Used by swapoff to help locate where page is expected in vma.
226 */
227unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
228
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229/*
230 * Cleans the PTEs of shared mappings.
231 * (and since clean PTEs should also be readonly, write protects them too)
232 *
233 * returns the number of cleaned PTEs.
234 */
235int page_mkclean(struct page *);
236
b291f000
NP
237/*
238 * called in munlock()/munmap() path to check for other vmas holding
239 * the page mlocked.
240 */
241int try_to_munlock(struct page *);
b291f000 242
10be22df
AK
243/*
244 * Called by memory-failure.c to kill processes.
245 */
ea4525b6
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246struct anon_vma *__page_lock_anon_vma(struct page *page);
247
248static inline struct anon_vma *page_lock_anon_vma(struct page *page)
249{
250 struct anon_vma *anon_vma;
251
252 __cond_lock(RCU, anon_vma = __page_lock_anon_vma(page));
253
254 /* (void) is needed to make gcc happy */
255 (void) __cond_lock(&anon_vma->root->lock, anon_vma);
256
257 return anon_vma;
258}
259
10be22df 260void page_unlock_anon_vma(struct anon_vma *anon_vma);
6a46079c 261int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
10be22df 262
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HD
263/*
264 * Called by migrate.c to remove migration ptes, but might be used more later.
265 */
266int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
267 struct vm_area_struct *, unsigned long, void *), void *arg);
268
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269#else /* !CONFIG_MMU */
270
271#define anon_vma_init() do {} while (0)
272#define anon_vma_prepare(vma) (0)
273#define anon_vma_link(vma) do {} while (0)
274
01ff53f4
MF
275static inline int page_referenced(struct page *page, int is_locked,
276 struct mem_cgroup *cnt,
277 unsigned long *vm_flags)
278{
279 *vm_flags = 0;
64574746 280 return 0;
01ff53f4
MF
281}
282
a48d07af 283#define try_to_unmap(page, refs) SWAP_FAIL
1da177e4 284
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285static inline int page_mkclean(struct page *page)
286{
287 return 0;
288}
289
290
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291#endif /* CONFIG_MMU */
292
293/*
294 * Return values of try_to_unmap
295 */
296#define SWAP_SUCCESS 0
297#define SWAP_AGAIN 1
298#define SWAP_FAIL 2
b291f000 299#define SWAP_MLOCK 3
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LT
300
301#endif /* _LINUX_RMAP_H */