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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/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
 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 
 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 
 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 
 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 
 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 
106 static inline void anon_vma_lock(struct anon_vma *anon_vma)
107 {
108         mutex_lock(&anon_vma->root->mutex);
109 }
110 
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 
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 
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 int try_to_unmap(struct page *, enum ttu_flags flags);
177 int try_to_unmap_one(struct page *, struct vm_area_struct *,
178                         unsigned long address, enum ttu_flags flags);
179 
180 /*
181  * Called from mm/filemap_xip.c to unmap empty zero page
182  */
183 pte_t *__page_check_address(struct page *, struct mm_struct *,
184                                 unsigned long, spinlock_t **, int);
185 
186 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
187                                         unsigned long address,
188                                         spinlock_t **ptlp, int sync)
189 {
190         pte_t *ptep;
191 
192         __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
193                                                        ptlp, sync));
194         return ptep;
195 }
196 
197 /*
198  * Used by swapoff to help locate where page is expected in vma.
199  */
200 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
201 
202 /*
203  * Cleans the PTEs of shared mappings.
204  * (and since clean PTEs should also be readonly, write protects them too)
205  *
206  * returns the number of cleaned PTEs.
207  */
208 int page_mkclean(struct page *);
209 
210 /*
211  * called in munlock()/munmap() path to check for other vmas holding
212  * the page mlocked.
213  */
214 int try_to_munlock(struct page *);
215 
216 /*
217  * Called by memory-failure.c to kill processes.
218  */
219 struct anon_vma *page_lock_anon_vma(struct page *page);
220 void page_unlock_anon_vma(struct anon_vma *anon_vma);
221 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
222 
223 /*
224  * Called by migrate.c to remove migration ptes, but might be used more later.
225  */
226 int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
227                 struct vm_area_struct *, unsigned long, void *), void *arg);
228 
229 #else   /* !CONFIG_MMU */
230 
231 #define anon_vma_init()         do {} while (0)
232 #define anon_vma_prepare(vma)   (0)
233 #define anon_vma_link(vma)      do {} while (0)
234 
235 static inline int page_referenced(struct page *page, int is_locked,
236                                   struct mem_cgroup *memcg,
237                                   unsigned long *vm_flags)
238 {
239         *vm_flags = 0;
240         return 0;
241 }
242 
243 #define try_to_unmap(page, refs) SWAP_FAIL
244 
245 static inline int page_mkclean(struct page *page)
246 {
247         return 0;
248 }
249 
250 
251 #endif  /* CONFIG_MMU */
252 
253 /*
254  * Return values of try_to_unmap
255  */
256 #define SWAP_SUCCESS    0
257 #define SWAP_AGAIN      1
258 #define SWAP_FAIL       2
259 #define SWAP_MLOCK      3
260 
261 #endif  /* _LINUX_RMAP_H */
262 

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