4 * Declarations for Reverse Mapping functions in mm/rmap.c
7 #include <linux/list.h>
8 #include <linux/slab.h>
10 #include <linux/rwsem.h>
11 #include <linux/memcontrol.h>
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.
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.
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.
28 struct anon_vma
*root
; /* Root of this anon_vma tree */
29 struct rw_semaphore rwsem
; /* W: modification, R: walking the list */
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
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).
47 struct rb_root rb_root
; /* Interval tree of private "related" vmas */
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.
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.
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
;
75 TTU_UNMAP
= 0, /* unmap mode */
76 TTU_MIGRATION
= 1, /* migration mode */
77 TTU_MUNLOCK
= 2, /* munlock mode */
78 TTU_ACTION_MASK
= 0xff,
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 */
86 static inline void get_anon_vma(struct anon_vma
*anon_vma
)
88 atomic_inc(&anon_vma
->refcount
);
91 void __put_anon_vma(struct anon_vma
*anon_vma
);
93 static inline void put_anon_vma(struct anon_vma
*anon_vma
)
95 if (atomic_dec_and_test(&anon_vma
->refcount
))
96 __put_anon_vma(anon_vma
);
99 static inline struct anon_vma
*page_anon_vma(struct page
*page
)
101 if (((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) !=
104 return page_rmapping(page
);
107 static inline void vma_lock_anon_vma(struct vm_area_struct
*vma
)
109 struct anon_vma
*anon_vma
= vma
->anon_vma
;
111 down_write(&anon_vma
->root
->rwsem
);
114 static inline void vma_unlock_anon_vma(struct vm_area_struct
*vma
)
116 struct anon_vma
*anon_vma
= vma
->anon_vma
;
118 up_write(&anon_vma
->root
->rwsem
);
121 static inline void anon_vma_lock_write(struct anon_vma
*anon_vma
)
123 down_write(&anon_vma
->root
->rwsem
);
126 static inline void anon_vma_unlock_write(struct anon_vma
*anon_vma
)
128 up_write(&anon_vma
->root
->rwsem
);
131 static inline void anon_vma_lock_read(struct anon_vma
*anon_vma
)
133 down_read(&anon_vma
->root
->rwsem
);
136 static inline void anon_vma_unlock_read(struct anon_vma
*anon_vma
)
138 up_read(&anon_vma
->root
->rwsem
);
143 * anon_vma helper functions.
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
*);
151 static inline void anon_vma_merge(struct vm_area_struct
*vma
,
152 struct vm_area_struct
*next
)
154 VM_BUG_ON(vma
->anon_vma
!= next
->anon_vma
);
155 unlink_anon_vmas(next
);
158 struct anon_vma
*page_get_anon_vma(struct page
*page
);
161 * rmap interfaces called when adding or removing pte of page
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
*,
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
*);
171 void hugepage_add_anon_rmap(struct page
*, struct vm_area_struct
*,
173 void hugepage_add_new_anon_rmap(struct page
*, struct vm_area_struct
*,
176 static inline void page_dup_rmap(struct page
*page
)
178 atomic_inc(&page
->_mapcount
);
182 * Called from mm/vmscan.c to handle paging out
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
, void *arg
);
189 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
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
, void *arg
);
196 * Called from mm/filemap_xip.c to unmap empty zero page
198 pte_t
*__page_check_address(struct page
*, struct mm_struct
*,
199 unsigned long, spinlock_t
**, int);
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
)
207 __cond_lock(*ptlp
, ptep
= __page_check_address(page
, mm
, address
,
213 * Used by swapoff to help locate where page is expected in vma.
215 unsigned long page_address_in_vma(struct page
*, struct vm_area_struct
*);
218 * Cleans the PTEs of shared mappings.
219 * (and since clean PTEs should also be readonly, write protects them too)
221 * returns the number of cleaned PTEs.
223 int page_mkclean(struct page
*);
226 * called in munlock()/munmap() path to check for other vmas holding
229 int try_to_munlock(struct page
*);
232 * Called by memory-failure.c to kill processes.
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
);
239 * rmap_walk_control: To control rmap traversing for specific needs
241 * arg: passed to rmap_one() and invalid_vma()
242 * rmap_one: executed on each vma where page is mapped
243 * done: for checking traversing termination condition
244 * file_nonlinear: for handling file nonlinear mapping
245 * anon_lock: for getting anon_lock by optimized way rather than default
246 * invalid_vma: for skipping uninterested vma
248 struct rmap_walk_control
{
250 int (*rmap_one
)(struct page
*page
, struct vm_area_struct
*vma
,
251 unsigned long addr
, void *arg
);
252 int (*done
)(struct page
*page
);
253 int (*file_nonlinear
)(struct page
*, struct address_space
*,
254 struct vm_area_struct
*vma
);
255 struct anon_vma
*(*anon_lock
)(struct page
*page
);
256 bool (*invalid_vma
)(struct vm_area_struct
*vma
, void *arg
);
259 int rmap_walk(struct page
*page
, struct rmap_walk_control
*rwc
);
261 #else /* !CONFIG_MMU */
263 #define anon_vma_init() do {} while (0)
264 #define anon_vma_prepare(vma) (0)
265 #define anon_vma_link(vma) do {} while (0)
267 static inline int page_referenced(struct page
*page
, int is_locked
,
268 struct mem_cgroup
*memcg
,
269 unsigned long *vm_flags
)
275 #define try_to_unmap(page, refs) SWAP_FAIL
277 static inline int page_mkclean(struct page
*page
)
283 #endif /* CONFIG_MMU */
286 * Return values of try_to_unmap
288 #define SWAP_SUCCESS 0
293 #endif /* _LINUX_RMAP_H */
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