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 * Count of child anon_vmas and VMAs which points to this anon_vma.
42 * This counter is used for making decision about reusing anon_vma
43 * instead of forking new one. See comments in function anon_vma_clone.
47 struct anon_vma
*parent
; /* Parent of this anon_vma */
50 * NOTE: the LSB of the rb_root.rb_node is set by
51 * mm_take_all_locks() _after_ taking the above lock. So the
52 * rb_root must only be read/written after taking the above lock
53 * to be sure to see a valid next pointer. The LSB bit itself
54 * is serialized by a system wide lock only visible to
55 * mm_take_all_locks() (mm_all_locks_mutex).
57 struct rb_root rb_root
; /* Interval tree of private "related" vmas */
61 * The copy-on-write semantics of fork mean that an anon_vma
62 * can become associated with multiple processes. Furthermore,
63 * each child process will have its own anon_vma, where new
64 * pages for that process are instantiated.
66 * This structure allows us to find the anon_vmas associated
67 * with a VMA, or the VMAs associated with an anon_vma.
68 * The "same_vma" list contains the anon_vma_chains linking
69 * all the anon_vmas associated with this VMA.
70 * The "rb" field indexes on an interval tree the anon_vma_chains
71 * which link all the VMAs associated with this anon_vma.
73 struct anon_vma_chain
{
74 struct vm_area_struct
*vma
;
75 struct anon_vma
*anon_vma
;
76 struct list_head same_vma
; /* locked by mmap_sem & page_table_lock */
77 struct rb_node rb
; /* locked by anon_vma->rwsem */
78 unsigned long rb_subtree_last
;
79 #ifdef CONFIG_DEBUG_VM_RB
80 unsigned long cached_vma_start
, cached_vma_last
;
85 TTU_UNMAP
= 1, /* unmap mode */
86 TTU_MIGRATION
= 2, /* migration mode */
87 TTU_MUNLOCK
= 4, /* munlock mode */
89 TTU_IGNORE_MLOCK
= (1 << 8), /* ignore mlock */
90 TTU_IGNORE_ACCESS
= (1 << 9), /* don't age */
91 TTU_IGNORE_HWPOISON
= (1 << 10),/* corrupted page is recoverable */
95 static inline void get_anon_vma(struct anon_vma
*anon_vma
)
97 atomic_inc(&anon_vma
->refcount
);
100 void __put_anon_vma(struct anon_vma
*anon_vma
);
102 static inline void put_anon_vma(struct anon_vma
*anon_vma
)
104 if (atomic_dec_and_test(&anon_vma
->refcount
))
105 __put_anon_vma(anon_vma
);
108 static inline struct anon_vma
*page_anon_vma(struct page
*page
)
110 if (((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) !=
113 return page_rmapping(page
);
116 static inline void vma_lock_anon_vma(struct vm_area_struct
*vma
)
118 struct anon_vma
*anon_vma
= vma
->anon_vma
;
120 down_write(&anon_vma
->root
->rwsem
);
123 static inline void vma_unlock_anon_vma(struct vm_area_struct
*vma
)
125 struct anon_vma
*anon_vma
= vma
->anon_vma
;
127 up_write(&anon_vma
->root
->rwsem
);
130 static inline void anon_vma_lock_write(struct anon_vma
*anon_vma
)
132 down_write(&anon_vma
->root
->rwsem
);
135 static inline void anon_vma_unlock_write(struct anon_vma
*anon_vma
)
137 up_write(&anon_vma
->root
->rwsem
);
140 static inline void anon_vma_lock_read(struct anon_vma
*anon_vma
)
142 down_read(&anon_vma
->root
->rwsem
);
145 static inline void anon_vma_unlock_read(struct anon_vma
*anon_vma
)
147 up_read(&anon_vma
->root
->rwsem
);
152 * anon_vma helper functions.
154 void anon_vma_init(void); /* create anon_vma_cachep */
155 int anon_vma_prepare(struct vm_area_struct
*);
156 void unlink_anon_vmas(struct vm_area_struct
*);
157 int anon_vma_clone(struct vm_area_struct
*, struct vm_area_struct
*);
158 int anon_vma_fork(struct vm_area_struct
*, struct vm_area_struct
*);
160 static inline void anon_vma_merge(struct vm_area_struct
*vma
,
161 struct vm_area_struct
*next
)
163 VM_BUG_ON_VMA(vma
->anon_vma
!= next
->anon_vma
, vma
);
164 unlink_anon_vmas(next
);
167 struct anon_vma
*page_get_anon_vma(struct page
*page
);
170 * rmap interfaces called when adding or removing pte of page
172 void page_move_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
173 void page_add_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
174 void do_page_add_anon_rmap(struct page
*, struct vm_area_struct
*,
176 void page_add_new_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
177 void page_add_file_rmap(struct page
*);
178 void page_remove_rmap(struct page
*);
180 void hugepage_add_anon_rmap(struct page
*, struct vm_area_struct
*,
182 void hugepage_add_new_anon_rmap(struct page
*, struct vm_area_struct
*,
185 static inline void page_dup_rmap(struct page
*page
)
187 atomic_inc(&page
->_mapcount
);
191 * Called from mm/vmscan.c to handle paging out
193 int page_referenced(struct page
*, int is_locked
,
194 struct mem_cgroup
*memcg
, unsigned long *vm_flags
);
196 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
198 int try_to_unmap(struct page
*, enum ttu_flags flags
);
201 * Used by uprobes to replace a userspace page safely
203 pte_t
*__page_check_address(struct page
*, struct mm_struct
*,
204 unsigned long, spinlock_t
**, int);
206 static inline pte_t
*page_check_address(struct page
*page
, struct mm_struct
*mm
,
207 unsigned long address
,
208 spinlock_t
**ptlp
, int sync
)
212 __cond_lock(*ptlp
, ptep
= __page_check_address(page
, mm
, address
,
218 * Used by swapoff to help locate where page is expected in vma.
220 unsigned long page_address_in_vma(struct page
*, struct vm_area_struct
*);
223 * Cleans the PTEs of shared mappings.
224 * (and since clean PTEs should also be readonly, write protects them too)
226 * returns the number of cleaned PTEs.
228 int page_mkclean(struct page
*);
231 * called in munlock()/munmap() path to check for other vmas holding
234 int try_to_munlock(struct page
*);
237 * Called by memory-failure.c to kill processes.
239 struct anon_vma
*page_lock_anon_vma_read(struct page
*page
);
240 void page_unlock_anon_vma_read(struct anon_vma
*anon_vma
);
241 int page_mapped_in_vma(struct page
*page
, struct vm_area_struct
*vma
);
244 * rmap_walk_control: To control rmap traversing for specific needs
246 * arg: passed to rmap_one() and invalid_vma()
247 * rmap_one: executed on each vma where page is mapped
248 * done: for checking traversing termination condition
249 * anon_lock: for getting anon_lock by optimized way rather than default
250 * invalid_vma: for skipping uninterested vma
252 struct rmap_walk_control
{
254 int (*rmap_one
)(struct page
*page
, struct vm_area_struct
*vma
,
255 unsigned long addr
, void *arg
);
256 int (*done
)(struct page
*page
);
257 struct anon_vma
*(*anon_lock
)(struct page
*page
);
258 bool (*invalid_vma
)(struct vm_area_struct
*vma
, void *arg
);
261 int rmap_walk(struct page
*page
, struct rmap_walk_control
*rwc
);
263 #else /* !CONFIG_MMU */
265 #define anon_vma_init() do {} while (0)
266 #define anon_vma_prepare(vma) (0)
267 #define anon_vma_link(vma) do {} while (0)
269 static inline int page_referenced(struct page
*page
, int is_locked
,
270 struct mem_cgroup
*memcg
,
271 unsigned long *vm_flags
)
277 #define try_to_unmap(page, refs) SWAP_FAIL
279 static inline int page_mkclean(struct page
*page
)
285 #endif /* CONFIG_MMU */
288 * Return values of try_to_unmap
290 #define SWAP_SUCCESS 0
295 #endif /* _LINUX_RMAP_H */
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