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1 : : /* SPDX-License-Identifier: GPL-2.0 */
2 : : #ifndef _LINUX_RMAP_H
3 : : #define _LINUX_RMAP_H
4 : : /*
5 : : * Declarations for Reverse Mapping functions in mm/rmap.c
6 : : */
7 : :
8 : : #include <linux/list.h>
9 : : #include <linux/slab.h>
10 : : #include <linux/mm.h>
11 : : #include <linux/rwsem.h>
12 : : #include <linux/memcontrol.h>
13 : : #include <linux/highmem.h>
14 : :
15 : : /*
16 : : * The anon_vma heads a list of private "related" vmas, to scan if
17 : : * an anonymous page pointing to this anon_vma needs to be unmapped:
18 : : * the vmas on the list will be related by forking, or by splitting.
19 : : *
20 : : * Since vmas come and go as they are split and merged (particularly
21 : : * in mprotect), the mapping field of an anonymous page cannot point
22 : : * directly to a vma: instead it points to an anon_vma, on whose list
23 : : * the related vmas can be easily linked or unlinked.
24 : : *
25 : : * After unlinking the last vma on the list, we must garbage collect
26 : : * the anon_vma object itself: we're guaranteed no page can be
27 : : * pointing to this anon_vma once its vma list is empty.
28 : : */
29 : : struct anon_vma {
30 : : struct anon_vma *root; /* Root of this anon_vma tree */
31 : : struct rw_semaphore rwsem; /* W: modification, R: walking the list */
32 : : /*
33 : : * The refcount is taken on an anon_vma when there is no
34 : : * guarantee that the vma of page tables will exist for
35 : : * the duration of the operation. A caller that takes
36 : : * the reference is responsible for clearing up the
37 : : * anon_vma if they are the last user on release
38 : : */
39 : : atomic_t refcount;
40 : :
41 : : /*
42 : : * Count of child anon_vmas and VMAs which points to this anon_vma.
43 : : *
44 : : * This counter is used for making decision about reusing anon_vma
45 : : * instead of forking new one. See comments in function anon_vma_clone.
46 : : */
47 : : unsigned degree;
48 : :
49 : : struct anon_vma *parent; /* Parent of this anon_vma */
50 : :
51 : : /*
52 : : * NOTE: the LSB of the rb_root.rb_node is set by
53 : : * mm_take_all_locks() _after_ taking the above lock. So the
54 : : * rb_root must only be read/written after taking the above lock
55 : : * to be sure to see a valid next pointer. The LSB bit itself
56 : : * is serialized by a system wide lock only visible to
57 : : * mm_take_all_locks() (mm_all_locks_mutex).
58 : : */
59 : :
60 : : /* Interval tree of private "related" vmas */
61 : : struct rb_root_cached rb_root;
62 : : };
63 : :
64 : : /*
65 : : * The copy-on-write semantics of fork mean that an anon_vma
66 : : * can become associated with multiple processes. Furthermore,
67 : : * each child process will have its own anon_vma, where new
68 : : * pages for that process are instantiated.
69 : : *
70 : : * This structure allows us to find the anon_vmas associated
71 : : * with a VMA, or the VMAs associated with an anon_vma.
72 : : * The "same_vma" list contains the anon_vma_chains linking
73 : : * all the anon_vmas associated with this VMA.
74 : : * The "rb" field indexes on an interval tree the anon_vma_chains
75 : : * which link all the VMAs associated with this anon_vma.
76 : : */
77 : : struct anon_vma_chain {
78 : : struct vm_area_struct *vma;
79 : : struct anon_vma *anon_vma;
80 : : struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
81 : : struct rb_node rb; /* locked by anon_vma->rwsem */
82 : : unsigned long rb_subtree_last;
83 : : #ifdef CONFIG_DEBUG_VM_RB
84 : : unsigned long cached_vma_start, cached_vma_last;
85 : : #endif
86 : : };
87 : :
88 : : enum ttu_flags {
89 : : TTU_MIGRATION = 0x1, /* migration mode */
90 : : TTU_MUNLOCK = 0x2, /* munlock mode */
91 : :
92 : : TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */
93 : : TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */
94 : : TTU_IGNORE_ACCESS = 0x10, /* don't age */
95 : : TTU_IGNORE_HWPOISON = 0x20, /* corrupted page is recoverable */
96 : : TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible
97 : : * and caller guarantees they will
98 : : * do a final flush if necessary */
99 : : TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
100 : : * caller holds it */
101 : : TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */
102 : : };
103 : :
104 : : #ifdef CONFIG_MMU
105 : 1089506 : static inline void get_anon_vma(struct anon_vma *anon_vma)
106 : : {
107 : 1089506 : atomic_inc(&anon_vma->refcount);
108 : : }
109 : :
110 : : void __put_anon_vma(struct anon_vma *anon_vma);
111 : :
112 : 1792425 : static inline void put_anon_vma(struct anon_vma *anon_vma)
113 : : {
114 [ + - ]: 1792425 : if (atomic_dec_and_test(&anon_vma->refcount))
115 : 1792425 : __put_anon_vma(anon_vma);
116 : 1792425 : }
117 : :
118 : 2460436 : static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
119 : : {
120 : 2460436 : down_write(&anon_vma->root->rwsem);
121 : : }
122 : :
123 : 2460436 : static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
124 : : {
125 : 2460436 : up_write(&anon_vma->root->rwsem);
126 : 557627 : }
127 : :
128 : 0 : static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
129 : : {
130 : 0 : down_read(&anon_vma->root->rwsem);
131 : : }
132 : :
133 : 0 : static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
134 : : {
135 : 0 : up_read(&anon_vma->root->rwsem);
136 : 0 : }
137 : :
138 : :
139 : : /*
140 : : * anon_vma helper functions.
141 : : */
142 : : void anon_vma_init(void); /* create anon_vma_cachep */
143 : : int __anon_vma_prepare(struct vm_area_struct *);
144 : : void unlink_anon_vmas(struct vm_area_struct *);
145 : : int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
146 : : int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
147 : :
148 : 2995711 : static inline int anon_vma_prepare(struct vm_area_struct *vma)
149 : : {
150 [ + + + + : 2995711 : if (likely(vma->anon_vma))
+ + ]
151 : : return 0;
152 : :
153 : 735393 : return __anon_vma_prepare(vma);
154 : : }
155 : :
156 : 0 : static inline void anon_vma_merge(struct vm_area_struct *vma,
157 : : struct vm_area_struct *next)
158 : : {
159 : 0 : VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
160 : 0 : unlink_anon_vmas(next);
161 : 0 : }
162 : :
163 : : struct anon_vma *page_get_anon_vma(struct page *page);
164 : :
165 : : /* bitflags for do_page_add_anon_rmap() */
166 : : #define RMAP_EXCLUSIVE 0x01
167 : : #define RMAP_COMPOUND 0x02
168 : :
169 : : /*
170 : : * rmap interfaces called when adding or removing pte of page
171 : : */
172 : : void page_move_anon_rmap(struct page *, struct vm_area_struct *);
173 : : void page_add_anon_rmap(struct page *, struct vm_area_struct *,
174 : : unsigned long, bool);
175 : : void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
176 : : unsigned long, int);
177 : : void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
178 : : unsigned long, bool);
179 : : void page_add_file_rmap(struct page *, bool);
180 : : void page_remove_rmap(struct page *, bool);
181 : :
182 : : void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
183 : : unsigned long);
184 : : void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
185 : : unsigned long);
186 : :
187 : 4541428 : static inline void page_dup_rmap(struct page *page, bool compound)
188 : : {
189 : 4541428 : atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
190 : 0 : }
191 : :
192 : : /*
193 : : * Called from mm/vmscan.c to handle paging out
194 : : */
195 : : int page_referenced(struct page *, int is_locked,
196 : : struct mem_cgroup *memcg, unsigned long *vm_flags);
197 : :
198 : : bool try_to_unmap(struct page *, enum ttu_flags flags);
199 : :
200 : : /* Avoid racy checks */
201 : : #define PVMW_SYNC (1 << 0)
202 : : /* Look for migarion entries rather than present PTEs */
203 : : #define PVMW_MIGRATION (1 << 1)
204 : :
205 : : struct page_vma_mapped_walk {
206 : : struct page *page;
207 : : struct vm_area_struct *vma;
208 : : unsigned long address;
209 : : pmd_t *pmd;
210 : : pte_t *pte;
211 : : spinlock_t *ptl;
212 : : unsigned int flags;
213 : : };
214 : :
215 : 0 : static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
216 : : {
217 : 0 : if (pvmw->pte)
218 : 0 : pte_unmap(pvmw->pte);
219 [ # # # # : 0 : if (pvmw->ptl)
# # # # #
# # # #
# ]
220 : 0 : spin_unlock(pvmw->ptl);
221 : : }
222 : :
223 : : bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
224 : :
225 : : /*
226 : : * Used by swapoff to help locate where page is expected in vma.
227 : : */
228 : : unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
229 : :
230 : : /*
231 : : * Cleans the PTEs of shared mappings.
232 : : * (and since clean PTEs should also be readonly, write protects them too)
233 : : *
234 : : * returns the number of cleaned PTEs.
235 : : */
236 : : int page_mkclean(struct page *);
237 : :
238 : : /*
239 : : * called in munlock()/munmap() path to check for other vmas holding
240 : : * the page mlocked.
241 : : */
242 : : void try_to_munlock(struct page *);
243 : :
244 : : void remove_migration_ptes(struct page *old, struct page *new, bool locked);
245 : :
246 : : /*
247 : : * Called by memory-failure.c to kill processes.
248 : : */
249 : : struct anon_vma *page_lock_anon_vma_read(struct page *page);
250 : : void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
251 : : int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
252 : :
253 : : /*
254 : : * rmap_walk_control: To control rmap traversing for specific needs
255 : : *
256 : : * arg: passed to rmap_one() and invalid_vma()
257 : : * rmap_one: executed on each vma where page is mapped
258 : : * done: for checking traversing termination condition
259 : : * anon_lock: for getting anon_lock by optimized way rather than default
260 : : * invalid_vma: for skipping uninterested vma
261 : : */
262 : : struct rmap_walk_control {
263 : : void *arg;
264 : : /*
265 : : * Return false if page table scanning in rmap_walk should be stopped.
266 : : * Otherwise, return true.
267 : : */
268 : : bool (*rmap_one)(struct page *page, struct vm_area_struct *vma,
269 : : unsigned long addr, void *arg);
270 : : int (*done)(struct page *page);
271 : : struct anon_vma *(*anon_lock)(struct page *page);
272 : : bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
273 : : };
274 : :
275 : : void rmap_walk(struct page *page, struct rmap_walk_control *rwc);
276 : : void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
277 : :
278 : : #else /* !CONFIG_MMU */
279 : :
280 : : #define anon_vma_init() do {} while (0)
281 : : #define anon_vma_prepare(vma) (0)
282 : : #define anon_vma_link(vma) do {} while (0)
283 : :
284 : : static inline int page_referenced(struct page *page, int is_locked,
285 : : struct mem_cgroup *memcg,
286 : : unsigned long *vm_flags)
287 : : {
288 : : *vm_flags = 0;
289 : : return 0;
290 : : }
291 : :
292 : : #define try_to_unmap(page, refs) false
293 : :
294 : : static inline int page_mkclean(struct page *page)
295 : : {
296 : : return 0;
297 : : }
298 : :
299 : :
300 : : #endif /* CONFIG_MMU */
301 : :
302 : : #endif /* _LINUX_RMAP_H */
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