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/mutex.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 mutex mutex; /* Serialize access to vma 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 head.next is set by
41 * mm_take_all_locks() _after_ taking the above lock. So the
42 * head 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 list_head head; /* Chain 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 "same_anon_vma" list contains 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 list_head same_anon_vma; /* locked by anon_vma->mutex */
68 };
69
70 #ifdef CONFIG_MMU
get_anon_vma(struct anon_vma * anon_vma)71 static inline void get_anon_vma(struct anon_vma *anon_vma)
72 {
73 atomic_inc(&anon_vma->refcount);
74 }
75
76 void __put_anon_vma(struct anon_vma *anon_vma);
77
put_anon_vma(struct anon_vma * anon_vma)78 static inline void put_anon_vma(struct anon_vma *anon_vma)
79 {
80 if (atomic_dec_and_test(&anon_vma->refcount))
81 __put_anon_vma(anon_vma);
82 }
83
page_anon_vma(struct page * page)84 static inline struct anon_vma *page_anon_vma(struct page *page)
85 {
86 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
87 PAGE_MAPPING_ANON)
88 return NULL;
89 return page_rmapping(page);
90 }
91
vma_lock_anon_vma(struct vm_area_struct * vma)92 static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
93 {
94 struct anon_vma *anon_vma = vma->anon_vma;
95 if (anon_vma)
96 mutex_lock(&anon_vma->root->mutex);
97 }
98
vma_unlock_anon_vma(struct vm_area_struct * vma)99 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
100 {
101 struct anon_vma *anon_vma = vma->anon_vma;
102 if (anon_vma)
103 mutex_unlock(&anon_vma->root->mutex);
104 }
105
anon_vma_lock(struct anon_vma * anon_vma)106 static inline void anon_vma_lock(struct anon_vma *anon_vma)
107 {
108 mutex_lock(&anon_vma->root->mutex);
109 }
110
anon_vma_unlock(struct anon_vma * anon_vma)111 static inline void anon_vma_unlock(struct anon_vma *anon_vma)
112 {
113 mutex_unlock(&anon_vma->root->mutex);
114 }
115
116 /*
117 * anon_vma helper functions.
118 */
119 void anon_vma_init(void); /* create anon_vma_cachep */
120 int anon_vma_prepare(struct vm_area_struct *);
121 void unlink_anon_vmas(struct vm_area_struct *);
122 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
123 void anon_vma_moveto_tail(struct vm_area_struct *);
124 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
125
anon_vma_merge(struct vm_area_struct * vma,struct vm_area_struct * next)126 static inline void anon_vma_merge(struct vm_area_struct *vma,
127 struct vm_area_struct *next)
128 {
129 VM_BUG_ON(vma->anon_vma != next->anon_vma);
130 unlink_anon_vmas(next);
131 }
132
133 struct anon_vma *page_get_anon_vma(struct page *page);
134
135 /*
136 * rmap interfaces called when adding or removing pte of page
137 */
138 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
139 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
140 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
141 unsigned long, int);
142 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
143 void page_add_file_rmap(struct page *);
144 void page_remove_rmap(struct page *);
145
146 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
147 unsigned long);
148 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
149 unsigned long);
150
page_dup_rmap(struct page * page)151 static inline void page_dup_rmap(struct page *page)
152 {
153 atomic_inc(&page->_mapcount);
154 }
155
156 /*
157 * Called from mm/vmscan.c to handle paging out
158 */
159 int page_referenced(struct page *, int is_locked,
160 struct mem_cgroup *memcg, unsigned long *vm_flags);
161 int page_referenced_one(struct page *, struct vm_area_struct *,
162 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
163
164 enum ttu_flags {
165 TTU_UNMAP = 0, /* unmap mode */
166 TTU_MIGRATION = 1, /* migration mode */
167 TTU_MUNLOCK = 2, /* munlock mode */
168 TTU_ACTION_MASK = 0xff,
169
170 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
171 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
172 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
173 };
174 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
175
176 bool is_vma_temporary_stack(struct vm_area_struct *vma);
177
178 int try_to_unmap(struct page *, enum ttu_flags flags);
179 int try_to_unmap_one(struct page *, struct vm_area_struct *,
180 unsigned long address, enum ttu_flags flags);
181
182 /*
183 * Called from mm/filemap_xip.c to unmap empty zero page
184 */
185 pte_t *__page_check_address(struct page *, struct mm_struct *,
186 unsigned long, spinlock_t **, int);
187
page_check_address(struct page * page,struct mm_struct * mm,unsigned long address,spinlock_t ** ptlp,int sync)188 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
189 unsigned long address,
190 spinlock_t **ptlp, int sync)
191 {
192 pte_t *ptep;
193
194 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
195 ptlp, sync));
196 return ptep;
197 }
198
199 /*
200 * Used by swapoff to help locate where page is expected in vma.
201 */
202 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
203
204 /*
205 * Cleans the PTEs of shared mappings.
206 * (and since clean PTEs should also be readonly, write protects them too)
207 *
208 * returns the number of cleaned PTEs.
209 */
210 int page_mkclean(struct page *);
211
212 /*
213 * called in munlock()/munmap() path to check for other vmas holding
214 * the page mlocked.
215 */
216 int try_to_munlock(struct page *);
217
218 /*
219 * Called by memory-failure.c to kill processes.
220 */
221 struct anon_vma *page_lock_anon_vma(struct page *page);
222 void page_unlock_anon_vma(struct anon_vma *anon_vma);
223 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
224
225 /*
226 * Called by migrate.c to remove migration ptes, but might be used more later.
227 */
228 int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
229 struct vm_area_struct *, unsigned long, void *), void *arg);
230
231 #else /* !CONFIG_MMU */
232
233 #define anon_vma_init() do {} while (0)
234 #define anon_vma_prepare(vma) (0)
235 #define anon_vma_link(vma) do {} while (0)
236
page_referenced(struct page * page,int is_locked,struct mem_cgroup * memcg,unsigned long * vm_flags)237 static inline int page_referenced(struct page *page, int is_locked,
238 struct mem_cgroup *memcg,
239 unsigned long *vm_flags)
240 {
241 *vm_flags = 0;
242 return 0;
243 }
244
245 #define try_to_unmap(page, refs) SWAP_FAIL
246
page_mkclean(struct page * page)247 static inline int page_mkclean(struct page *page)
248 {
249 return 0;
250 }
251
252
253 #endif /* CONFIG_MMU */
254
255 /*
256 * Return values of try_to_unmap
257 */
258 #define SWAP_SUCCESS 0
259 #define SWAP_AGAIN 1
260 #define SWAP_FAIL 2
261 #define SWAP_MLOCK 3
262
263 #endif /* _LINUX_RMAP_H */
264