projects/linux·blob v3.16 · refs

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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 */
27struct 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 */
63struct 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
74enum ttu_flags {
75 TTU_UNMAP = 1, /* unmap mode */
76 TTU_MIGRATION = 2, /* migration mode */
77 TTU_MUNLOCK = 4, /* munlock mode */
78
79 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
80 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
81 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
82};
83
84#ifdef CONFIG_MMU
85static inline void get_anon_vma(struct anon_vma *anon_vma)
86{
87 atomic_inc(&anon_vma->refcount);
88}
89
90void __put_anon_vma(struct anon_vma *anon_vma);
91
92static inline void put_anon_vma(struct anon_vma *anon_vma)
93{
94 if (atomic_dec_and_test(&anon_vma->refcount))
95 __put_anon_vma(anon_vma);
96}
97
98static inline struct anon_vma *page_anon_vma(struct page *page)
99{
100 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
101 PAGE_MAPPING_ANON)
102 return NULL;
103 return page_rmapping(page);
104}
105
106static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
107{
108 struct anon_vma *anon_vma = vma->anon_vma;
109 if (anon_vma)
110 down_write(&anon_vma->root->rwsem);
111}
112
113static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
114{
115 struct anon_vma *anon_vma = vma->anon_vma;
116 if (anon_vma)
117 up_write(&anon_vma->root->rwsem);
118}
119
120static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
121{
122 down_write(&anon_vma->root->rwsem);
123}
124
125static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
126{
127 up_write(&anon_vma->root->rwsem);
128}
129
130static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
131{
132 down_read(&anon_vma->root->rwsem);
133}
134
135static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
136{
137 up_read(&anon_vma->root->rwsem);
138}
139
140
141/*
142 * anon_vma helper functions.
143 */
144void anon_vma_init(void); /* create anon_vma_cachep */
145int anon_vma_prepare(struct vm_area_struct *);
146void unlink_anon_vmas(struct vm_area_struct *);
147int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
148int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
149
150static inline void anon_vma_merge(struct vm_area_struct *vma,
151 struct vm_area_struct *next)
152{
153 VM_BUG_ON(vma->anon_vma != next->anon_vma);
154 unlink_anon_vmas(next);
155}
156
157struct anon_vma *page_get_anon_vma(struct page *page);
158
159/*
160 * rmap interfaces called when adding or removing pte of page
161 */
162void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
163void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
164void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
165 unsigned long, int);
166void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
167void page_add_file_rmap(struct page *);
168void page_remove_rmap(struct page *);
169
170void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
171 unsigned long);
172void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
173 unsigned long);
174
175static inline void page_dup_rmap(struct page *page)
176{
177 atomic_inc(&page->_mapcount);
178}
179
180/*
181 * Called from mm/vmscan.c to handle paging out
182 */
183int page_referenced(struct page *, int is_locked,
184 struct mem_cgroup *memcg, unsigned long *vm_flags);
185
186#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
187
188int try_to_unmap(struct page *, enum ttu_flags flags);
189
190/*
191 * Called from mm/filemap_xip.c to unmap empty zero page
192 */
193pte_t *__page_check_address(struct page *, struct mm_struct *,
194 unsigned long, spinlock_t **, int);
195
196static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
197 unsigned long address,
198 spinlock_t **ptlp, int sync)
199{
200 pte_t *ptep;
201
202 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
203 ptlp, sync));
204 return ptep;
205}
206
207/*
208 * Used by swapoff to help locate where page is expected in vma.
209 */
210unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
211
212/*
213 * Cleans the PTEs of shared mappings.
214 * (and since clean PTEs should also be readonly, write protects them too)
215 *
216 * returns the number of cleaned PTEs.
217 */
218int page_mkclean(struct page *);
219
220/*
221 * called in munlock()/munmap() path to check for other vmas holding
222 * the page mlocked.
223 */
224int try_to_munlock(struct page *);
225
226/*
227 * Called by memory-failure.c to kill processes.
228 */
229struct anon_vma *page_lock_anon_vma_read(struct page *page);
230void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
231int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
232
233/*
234 * rmap_walk_control: To control rmap traversing for specific needs
235 *
236 * arg: passed to rmap_one() and invalid_vma()
237 * rmap_one: executed on each vma where page is mapped
238 * done: for checking traversing termination condition
239 * file_nonlinear: for handling file nonlinear mapping
240 * anon_lock: for getting anon_lock by optimized way rather than default
241 * invalid_vma: for skipping uninterested vma
242 */
243struct rmap_walk_control {
244 void *arg;
245 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
246 unsigned long addr, void *arg);
247 int (*done)(struct page *page);
248 int (*file_nonlinear)(struct page *, struct address_space *, void *arg);
249 struct anon_vma *(*anon_lock)(struct page *page);
250 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
251};
252
253int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
254
255#else /* !CONFIG_MMU */
256
257#define anon_vma_init() do {} while (0)
258#define anon_vma_prepare(vma) (0)
259#define anon_vma_link(vma) do {} while (0)
260
261static inline int page_referenced(struct page *page, int is_locked,
262 struct mem_cgroup *memcg,
263 unsigned long *vm_flags)
264{
265 *vm_flags = 0;
266 return 0;
267}
268
269#define try_to_unmap(page, refs) SWAP_FAIL
270
271static inline int page_mkclean(struct page *page)
272{
273 return 0;
274}
275
276
277#endif /* CONFIG_MMU */
278
279/*
280 * Return values of try_to_unmap
281 */
282#define SWAP_SUCCESS 0
283#define SWAP_AGAIN 1
284#define SWAP_FAIL 2
285#define SWAP_MLOCK 3
286
287#endif /* _LINUX_RMAP_H */