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
get_anon_vma(struct anon_vma * anon_vma)86 static inline void get_anon_vma(struct anon_vma *anon_vma)
87 {
88 atomic_inc(&anon_vma->refcount);
89 }
90
91 void __put_anon_vma(struct anon_vma *anon_vma);
92
put_anon_vma(struct anon_vma * anon_vma)93 static inline void put_anon_vma(struct anon_vma *anon_vma)
94 {
95 if (atomic_dec_and_test(&anon_vma->refcount))
96 __put_anon_vma(anon_vma);
97 }
98
page_anon_vma(struct page * page)99 static inline struct anon_vma *page_anon_vma(struct page *page)
100 {
101 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
102 PAGE_MAPPING_ANON)
103 return NULL;
104 return page_rmapping(page);
105 }
106
vma_lock_anon_vma(struct vm_area_struct * vma)107 static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
108 {
109 struct anon_vma *anon_vma = vma->anon_vma;
110 if (anon_vma)
111 down_write(&anon_vma->root->rwsem);
112 }
113
vma_unlock_anon_vma(struct vm_area_struct * vma)114 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
115 {
116 struct anon_vma *anon_vma = vma->anon_vma;
117 if (anon_vma)
118 up_write(&anon_vma->root->rwsem);
119 }
120
anon_vma_lock_write(struct anon_vma * anon_vma)121 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
122 {
123 down_write(&anon_vma->root->rwsem);
124 }
125
anon_vma_unlock_write(struct anon_vma * anon_vma)126 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
127 {
128 up_write(&anon_vma->root->rwsem);
129 }
130
anon_vma_lock_read(struct anon_vma * anon_vma)131 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
132 {
133 down_read(&anon_vma->root->rwsem);
134 }
135
anon_vma_unlock_read(struct anon_vma * anon_vma)136 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
137 {
138 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
anon_vma_merge(struct vm_area_struct * vma,struct vm_area_struct * next)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 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
page_dup_rmap(struct page * page)176 static inline void page_dup_rmap(struct page *page)
177 {
178 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, unsigned int *mapcount, unsigned long *vm_flags);
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, enum ttu_flags flags);
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
page_check_address(struct page * page,struct mm_struct * mm,unsigned long address,spinlock_t ** ptlp,int sync)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 __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 * Called by migrate.c to remove migration ptes, but might be used more later.
240 */
241 int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
242 struct vm_area_struct *, unsigned long, void *), void *arg);
243
244 #else /* !CONFIG_MMU */
245
246 #define anon_vma_init() do {} while (0)
247 #define anon_vma_prepare(vma) (0)
248 #define anon_vma_link(vma) do {} while (0)
249
page_referenced(struct page * page,int is_locked,struct mem_cgroup * memcg,unsigned long * vm_flags)250 static inline int page_referenced(struct page *page, int is_locked,
251 struct mem_cgroup *memcg,
252 unsigned long *vm_flags)
253 {
254 *vm_flags = 0;
255 return 0;
256 }
257
258 #define try_to_unmap(page, refs) SWAP_FAIL
259
page_mkclean(struct page * page)260 static inline int page_mkclean(struct page *page)
261 {
262 return 0;
263 }
264
265
266 #endif /* CONFIG_MMU */
267
268 /*
269 * Return values of try_to_unmap
270 */
271 #define SWAP_SUCCESS 0
272 #define SWAP_AGAIN 1
273 #define SWAP_FAIL 2
274 #define SWAP_MLOCK 3
275
276 #endif /* _LINUX_RMAP_H */
277