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TOMOYO Linux Cross Reference
Linux/include/linux/rmap.h

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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         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         if (atomic_dec_and_test(&anon_vma->refcount))
 96                 __put_anon_vma(anon_vma);
 97 }
 98 
 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 
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 
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 
121 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
122 {
123         down_write(&anon_vma->root->rwsem);
124 }
125 
126 static inline void anon_vma_unlock(struct anon_vma *anon_vma)
127 {
128         up_write(&anon_vma->root->rwsem);
129 }
130 
131 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
132 {
133         down_read(&anon_vma->root->rwsem);
134 }
135 
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 
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 
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 
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 
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 
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 

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