Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * mm/rmap.c - physical to virtual reverse mappings | |
3 | * | |
4 | * Copyright 2001, Rik van Riel <riel@conectiva.com.br> | |
5 | * Released under the General Public License (GPL). | |
6 | * | |
7 | * Simple, low overhead reverse mapping scheme. | |
8 | * Please try to keep this thing as modular as possible. | |
9 | * | |
10 | * Provides methods for unmapping each kind of mapped page: | |
11 | * the anon methods track anonymous pages, and | |
12 | * the file methods track pages belonging to an inode. | |
13 | * | |
14 | * Original design by Rik van Riel <riel@conectiva.com.br> 2001 | |
15 | * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 | |
16 | * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 | |
98f32602 | 17 | * Contributions by Hugh Dickins 2003, 2004 |
1da177e4 LT |
18 | */ |
19 | ||
20 | /* | |
21 | * Lock ordering in mm: | |
22 | * | |
1b1dcc1b | 23 | * inode->i_mutex (while writing or truncating, not reading or faulting) |
82591e6e NP |
24 | * mm->mmap_sem |
25 | * page->flags PG_locked (lock_page) | |
3d48ae45 | 26 | * mapping->i_mmap_mutex |
5a505085 | 27 | * anon_vma->rwsem |
82591e6e NP |
28 | * mm->page_table_lock or pte_lock |
29 | * zone->lru_lock (in mark_page_accessed, isolate_lru_page) | |
30 | * swap_lock (in swap_duplicate, swap_info_get) | |
31 | * mmlist_lock (in mmput, drain_mmlist and others) | |
32 | * mapping->private_lock (in __set_page_dirty_buffers) | |
250df6ed | 33 | * inode->i_lock (in set_page_dirty's __mark_inode_dirty) |
f758eeab | 34 | * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) |
82591e6e NP |
35 | * sb_lock (within inode_lock in fs/fs-writeback.c) |
36 | * mapping->tree_lock (widely used, in set_page_dirty, | |
37 | * in arch-dependent flush_dcache_mmap_lock, | |
f758eeab | 38 | * within bdi.wb->list_lock in __sync_single_inode) |
6a46079c | 39 | * |
5a505085 | 40 | * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon) |
9b679320 | 41 | * ->tasklist_lock |
6a46079c | 42 | * pte map lock |
1da177e4 LT |
43 | */ |
44 | ||
45 | #include <linux/mm.h> | |
46 | #include <linux/pagemap.h> | |
47 | #include <linux/swap.h> | |
48 | #include <linux/swapops.h> | |
49 | #include <linux/slab.h> | |
50 | #include <linux/init.h> | |
5ad64688 | 51 | #include <linux/ksm.h> |
1da177e4 LT |
52 | #include <linux/rmap.h> |
53 | #include <linux/rcupdate.h> | |
b95f1b31 | 54 | #include <linux/export.h> |
8a9f3ccd | 55 | #include <linux/memcontrol.h> |
cddb8a5c | 56 | #include <linux/mmu_notifier.h> |
64cdd548 | 57 | #include <linux/migrate.h> |
0fe6e20b | 58 | #include <linux/hugetlb.h> |
ef5d437f | 59 | #include <linux/backing-dev.h> |
1da177e4 LT |
60 | |
61 | #include <asm/tlbflush.h> | |
62 | ||
b291f000 NP |
63 | #include "internal.h" |
64 | ||
fdd2e5f8 | 65 | static struct kmem_cache *anon_vma_cachep; |
5beb4930 | 66 | static struct kmem_cache *anon_vma_chain_cachep; |
fdd2e5f8 AB |
67 | |
68 | static inline struct anon_vma *anon_vma_alloc(void) | |
69 | { | |
01d8b20d PZ |
70 | struct anon_vma *anon_vma; |
71 | ||
72 | anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); | |
73 | if (anon_vma) { | |
74 | atomic_set(&anon_vma->refcount, 1); | |
75 | /* | |
76 | * Initialise the anon_vma root to point to itself. If called | |
77 | * from fork, the root will be reset to the parents anon_vma. | |
78 | */ | |
79 | anon_vma->root = anon_vma; | |
80 | } | |
81 | ||
82 | return anon_vma; | |
fdd2e5f8 AB |
83 | } |
84 | ||
01d8b20d | 85 | static inline void anon_vma_free(struct anon_vma *anon_vma) |
fdd2e5f8 | 86 | { |
01d8b20d | 87 | VM_BUG_ON(atomic_read(&anon_vma->refcount)); |
88c22088 PZ |
88 | |
89 | /* | |
4fc3f1d6 | 90 | * Synchronize against page_lock_anon_vma_read() such that |
88c22088 PZ |
91 | * we can safely hold the lock without the anon_vma getting |
92 | * freed. | |
93 | * | |
94 | * Relies on the full mb implied by the atomic_dec_and_test() from | |
95 | * put_anon_vma() against the acquire barrier implied by | |
4fc3f1d6 | 96 | * down_read_trylock() from page_lock_anon_vma_read(). This orders: |
88c22088 | 97 | * |
4fc3f1d6 IM |
98 | * page_lock_anon_vma_read() VS put_anon_vma() |
99 | * down_read_trylock() atomic_dec_and_test() | |
88c22088 | 100 | * LOCK MB |
4fc3f1d6 | 101 | * atomic_read() rwsem_is_locked() |
88c22088 PZ |
102 | * |
103 | * LOCK should suffice since the actual taking of the lock must | |
104 | * happen _before_ what follows. | |
105 | */ | |
ef151648 | 106 | might_sleep(); |
5a505085 | 107 | if (rwsem_is_locked(&anon_vma->root->rwsem)) { |
4fc3f1d6 | 108 | anon_vma_lock_write(anon_vma); |
08b52706 | 109 | anon_vma_unlock_write(anon_vma); |
88c22088 PZ |
110 | } |
111 | ||
fdd2e5f8 AB |
112 | kmem_cache_free(anon_vma_cachep, anon_vma); |
113 | } | |
1da177e4 | 114 | |
dd34739c | 115 | static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp) |
5beb4930 | 116 | { |
dd34739c | 117 | return kmem_cache_alloc(anon_vma_chain_cachep, gfp); |
5beb4930 RR |
118 | } |
119 | ||
e574b5fd | 120 | static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) |
5beb4930 RR |
121 | { |
122 | kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); | |
123 | } | |
124 | ||
6583a843 KC |
125 | static void anon_vma_chain_link(struct vm_area_struct *vma, |
126 | struct anon_vma_chain *avc, | |
127 | struct anon_vma *anon_vma) | |
128 | { | |
129 | avc->vma = vma; | |
130 | avc->anon_vma = anon_vma; | |
131 | list_add(&avc->same_vma, &vma->anon_vma_chain); | |
bf181b9f | 132 | anon_vma_interval_tree_insert(avc, &anon_vma->rb_root); |
6583a843 KC |
133 | } |
134 | ||
d9d332e0 LT |
135 | /** |
136 | * anon_vma_prepare - attach an anon_vma to a memory region | |
137 | * @vma: the memory region in question | |
138 | * | |
139 | * This makes sure the memory mapping described by 'vma' has | |
140 | * an 'anon_vma' attached to it, so that we can associate the | |
141 | * anonymous pages mapped into it with that anon_vma. | |
142 | * | |
143 | * The common case will be that we already have one, but if | |
23a0790a | 144 | * not we either need to find an adjacent mapping that we |
d9d332e0 LT |
145 | * can re-use the anon_vma from (very common when the only |
146 | * reason for splitting a vma has been mprotect()), or we | |
147 | * allocate a new one. | |
148 | * | |
149 | * Anon-vma allocations are very subtle, because we may have | |
4fc3f1d6 | 150 | * optimistically looked up an anon_vma in page_lock_anon_vma_read() |
d9d332e0 LT |
151 | * and that may actually touch the spinlock even in the newly |
152 | * allocated vma (it depends on RCU to make sure that the | |
153 | * anon_vma isn't actually destroyed). | |
154 | * | |
155 | * As a result, we need to do proper anon_vma locking even | |
156 | * for the new allocation. At the same time, we do not want | |
157 | * to do any locking for the common case of already having | |
158 | * an anon_vma. | |
159 | * | |
160 | * This must be called with the mmap_sem held for reading. | |
161 | */ | |
1da177e4 LT |
162 | int anon_vma_prepare(struct vm_area_struct *vma) |
163 | { | |
164 | struct anon_vma *anon_vma = vma->anon_vma; | |
5beb4930 | 165 | struct anon_vma_chain *avc; |
1da177e4 LT |
166 | |
167 | might_sleep(); | |
168 | if (unlikely(!anon_vma)) { | |
169 | struct mm_struct *mm = vma->vm_mm; | |
d9d332e0 | 170 | struct anon_vma *allocated; |
1da177e4 | 171 | |
dd34739c | 172 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
5beb4930 RR |
173 | if (!avc) |
174 | goto out_enomem; | |
175 | ||
1da177e4 | 176 | anon_vma = find_mergeable_anon_vma(vma); |
d9d332e0 LT |
177 | allocated = NULL; |
178 | if (!anon_vma) { | |
1da177e4 LT |
179 | anon_vma = anon_vma_alloc(); |
180 | if (unlikely(!anon_vma)) | |
5beb4930 | 181 | goto out_enomem_free_avc; |
1da177e4 | 182 | allocated = anon_vma; |
1da177e4 LT |
183 | } |
184 | ||
4fc3f1d6 | 185 | anon_vma_lock_write(anon_vma); |
1da177e4 LT |
186 | /* page_table_lock to protect against threads */ |
187 | spin_lock(&mm->page_table_lock); | |
188 | if (likely(!vma->anon_vma)) { | |
189 | vma->anon_vma = anon_vma; | |
6583a843 | 190 | anon_vma_chain_link(vma, avc, anon_vma); |
1da177e4 | 191 | allocated = NULL; |
31f2b0eb | 192 | avc = NULL; |
1da177e4 LT |
193 | } |
194 | spin_unlock(&mm->page_table_lock); | |
08b52706 | 195 | anon_vma_unlock_write(anon_vma); |
31f2b0eb ON |
196 | |
197 | if (unlikely(allocated)) | |
01d8b20d | 198 | put_anon_vma(allocated); |
31f2b0eb | 199 | if (unlikely(avc)) |
5beb4930 | 200 | anon_vma_chain_free(avc); |
1da177e4 LT |
201 | } |
202 | return 0; | |
5beb4930 RR |
203 | |
204 | out_enomem_free_avc: | |
205 | anon_vma_chain_free(avc); | |
206 | out_enomem: | |
207 | return -ENOMEM; | |
1da177e4 LT |
208 | } |
209 | ||
bb4aa396 LT |
210 | /* |
211 | * This is a useful helper function for locking the anon_vma root as | |
212 | * we traverse the vma->anon_vma_chain, looping over anon_vma's that | |
213 | * have the same vma. | |
214 | * | |
215 | * Such anon_vma's should have the same root, so you'd expect to see | |
216 | * just a single mutex_lock for the whole traversal. | |
217 | */ | |
218 | static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma) | |
219 | { | |
220 | struct anon_vma *new_root = anon_vma->root; | |
221 | if (new_root != root) { | |
222 | if (WARN_ON_ONCE(root)) | |
5a505085 | 223 | up_write(&root->rwsem); |
bb4aa396 | 224 | root = new_root; |
5a505085 | 225 | down_write(&root->rwsem); |
bb4aa396 LT |
226 | } |
227 | return root; | |
228 | } | |
229 | ||
230 | static inline void unlock_anon_vma_root(struct anon_vma *root) | |
231 | { | |
232 | if (root) | |
5a505085 | 233 | up_write(&root->rwsem); |
bb4aa396 LT |
234 | } |
235 | ||
5beb4930 RR |
236 | /* |
237 | * Attach the anon_vmas from src to dst. | |
238 | * Returns 0 on success, -ENOMEM on failure. | |
239 | */ | |
240 | int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) | |
1da177e4 | 241 | { |
5beb4930 | 242 | struct anon_vma_chain *avc, *pavc; |
bb4aa396 | 243 | struct anon_vma *root = NULL; |
5beb4930 | 244 | |
646d87b4 | 245 | list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { |
bb4aa396 LT |
246 | struct anon_vma *anon_vma; |
247 | ||
dd34739c LT |
248 | avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN); |
249 | if (unlikely(!avc)) { | |
250 | unlock_anon_vma_root(root); | |
251 | root = NULL; | |
252 | avc = anon_vma_chain_alloc(GFP_KERNEL); | |
253 | if (!avc) | |
254 | goto enomem_failure; | |
255 | } | |
bb4aa396 LT |
256 | anon_vma = pavc->anon_vma; |
257 | root = lock_anon_vma_root(root, anon_vma); | |
258 | anon_vma_chain_link(dst, avc, anon_vma); | |
5beb4930 | 259 | } |
bb4aa396 | 260 | unlock_anon_vma_root(root); |
5beb4930 | 261 | return 0; |
1da177e4 | 262 | |
5beb4930 RR |
263 | enomem_failure: |
264 | unlink_anon_vmas(dst); | |
265 | return -ENOMEM; | |
1da177e4 LT |
266 | } |
267 | ||
5beb4930 RR |
268 | /* |
269 | * Attach vma to its own anon_vma, as well as to the anon_vmas that | |
270 | * the corresponding VMA in the parent process is attached to. | |
271 | * Returns 0 on success, non-zero on failure. | |
272 | */ | |
273 | int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) | |
1da177e4 | 274 | { |
5beb4930 RR |
275 | struct anon_vma_chain *avc; |
276 | struct anon_vma *anon_vma; | |
1da177e4 | 277 | |
5beb4930 RR |
278 | /* Don't bother if the parent process has no anon_vma here. */ |
279 | if (!pvma->anon_vma) | |
280 | return 0; | |
281 | ||
282 | /* | |
283 | * First, attach the new VMA to the parent VMA's anon_vmas, | |
284 | * so rmap can find non-COWed pages in child processes. | |
285 | */ | |
286 | if (anon_vma_clone(vma, pvma)) | |
287 | return -ENOMEM; | |
288 | ||
289 | /* Then add our own anon_vma. */ | |
290 | anon_vma = anon_vma_alloc(); | |
291 | if (!anon_vma) | |
292 | goto out_error; | |
dd34739c | 293 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
5beb4930 RR |
294 | if (!avc) |
295 | goto out_error_free_anon_vma; | |
5c341ee1 RR |
296 | |
297 | /* | |
298 | * The root anon_vma's spinlock is the lock actually used when we | |
299 | * lock any of the anon_vmas in this anon_vma tree. | |
300 | */ | |
301 | anon_vma->root = pvma->anon_vma->root; | |
76545066 | 302 | /* |
01d8b20d PZ |
303 | * With refcounts, an anon_vma can stay around longer than the |
304 | * process it belongs to. The root anon_vma needs to be pinned until | |
305 | * this anon_vma is freed, because the lock lives in the root. | |
76545066 RR |
306 | */ |
307 | get_anon_vma(anon_vma->root); | |
5beb4930 RR |
308 | /* Mark this anon_vma as the one where our new (COWed) pages go. */ |
309 | vma->anon_vma = anon_vma; | |
4fc3f1d6 | 310 | anon_vma_lock_write(anon_vma); |
5c341ee1 | 311 | anon_vma_chain_link(vma, avc, anon_vma); |
08b52706 | 312 | anon_vma_unlock_write(anon_vma); |
5beb4930 RR |
313 | |
314 | return 0; | |
315 | ||
316 | out_error_free_anon_vma: | |
01d8b20d | 317 | put_anon_vma(anon_vma); |
5beb4930 | 318 | out_error: |
4946d54c | 319 | unlink_anon_vmas(vma); |
5beb4930 | 320 | return -ENOMEM; |
1da177e4 LT |
321 | } |
322 | ||
5beb4930 RR |
323 | void unlink_anon_vmas(struct vm_area_struct *vma) |
324 | { | |
325 | struct anon_vma_chain *avc, *next; | |
eee2acba | 326 | struct anon_vma *root = NULL; |
5beb4930 | 327 | |
5c341ee1 RR |
328 | /* |
329 | * Unlink each anon_vma chained to the VMA. This list is ordered | |
330 | * from newest to oldest, ensuring the root anon_vma gets freed last. | |
331 | */ | |
5beb4930 | 332 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
eee2acba PZ |
333 | struct anon_vma *anon_vma = avc->anon_vma; |
334 | ||
335 | root = lock_anon_vma_root(root, anon_vma); | |
bf181b9f | 336 | anon_vma_interval_tree_remove(avc, &anon_vma->rb_root); |
eee2acba PZ |
337 | |
338 | /* | |
339 | * Leave empty anon_vmas on the list - we'll need | |
340 | * to free them outside the lock. | |
341 | */ | |
bf181b9f | 342 | if (RB_EMPTY_ROOT(&anon_vma->rb_root)) |
eee2acba PZ |
343 | continue; |
344 | ||
345 | list_del(&avc->same_vma); | |
346 | anon_vma_chain_free(avc); | |
347 | } | |
348 | unlock_anon_vma_root(root); | |
349 | ||
350 | /* | |
351 | * Iterate the list once more, it now only contains empty and unlinked | |
352 | * anon_vmas, destroy them. Could not do before due to __put_anon_vma() | |
5a505085 | 353 | * needing to write-acquire the anon_vma->root->rwsem. |
eee2acba PZ |
354 | */ |
355 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { | |
356 | struct anon_vma *anon_vma = avc->anon_vma; | |
357 | ||
358 | put_anon_vma(anon_vma); | |
359 | ||
5beb4930 RR |
360 | list_del(&avc->same_vma); |
361 | anon_vma_chain_free(avc); | |
362 | } | |
363 | } | |
364 | ||
51cc5068 | 365 | static void anon_vma_ctor(void *data) |
1da177e4 | 366 | { |
a35afb83 | 367 | struct anon_vma *anon_vma = data; |
1da177e4 | 368 | |
5a505085 | 369 | init_rwsem(&anon_vma->rwsem); |
83813267 | 370 | atomic_set(&anon_vma->refcount, 0); |
bf181b9f | 371 | anon_vma->rb_root = RB_ROOT; |
1da177e4 LT |
372 | } |
373 | ||
374 | void __init anon_vma_init(void) | |
375 | { | |
376 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 377 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
5beb4930 | 378 | anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC); |
1da177e4 LT |
379 | } |
380 | ||
381 | /* | |
6111e4ca PZ |
382 | * Getting a lock on a stable anon_vma from a page off the LRU is tricky! |
383 | * | |
384 | * Since there is no serialization what so ever against page_remove_rmap() | |
385 | * the best this function can do is return a locked anon_vma that might | |
386 | * have been relevant to this page. | |
387 | * | |
388 | * The page might have been remapped to a different anon_vma or the anon_vma | |
389 | * returned may already be freed (and even reused). | |
390 | * | |
bc658c96 PZ |
391 | * In case it was remapped to a different anon_vma, the new anon_vma will be a |
392 | * child of the old anon_vma, and the anon_vma lifetime rules will therefore | |
393 | * ensure that any anon_vma obtained from the page will still be valid for as | |
394 | * long as we observe page_mapped() [ hence all those page_mapped() tests ]. | |
395 | * | |
6111e4ca PZ |
396 | * All users of this function must be very careful when walking the anon_vma |
397 | * chain and verify that the page in question is indeed mapped in it | |
398 | * [ something equivalent to page_mapped_in_vma() ]. | |
399 | * | |
400 | * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap() | |
401 | * that the anon_vma pointer from page->mapping is valid if there is a | |
402 | * mapcount, we can dereference the anon_vma after observing those. | |
1da177e4 | 403 | */ |
746b18d4 | 404 | struct anon_vma *page_get_anon_vma(struct page *page) |
1da177e4 | 405 | { |
746b18d4 | 406 | struct anon_vma *anon_vma = NULL; |
1da177e4 LT |
407 | unsigned long anon_mapping; |
408 | ||
409 | rcu_read_lock(); | |
80e14822 | 410 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
3ca7b3c5 | 411 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
1da177e4 LT |
412 | goto out; |
413 | if (!page_mapped(page)) | |
414 | goto out; | |
415 | ||
416 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
746b18d4 PZ |
417 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
418 | anon_vma = NULL; | |
419 | goto out; | |
420 | } | |
f1819427 HD |
421 | |
422 | /* | |
423 | * If this page is still mapped, then its anon_vma cannot have been | |
746b18d4 PZ |
424 | * freed. But if it has been unmapped, we have no security against the |
425 | * anon_vma structure being freed and reused (for another anon_vma: | |
426 | * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero() | |
427 | * above cannot corrupt). | |
f1819427 | 428 | */ |
746b18d4 | 429 | if (!page_mapped(page)) { |
ef151648 | 430 | rcu_read_unlock(); |
746b18d4 | 431 | put_anon_vma(anon_vma); |
ef151648 | 432 | return NULL; |
746b18d4 | 433 | } |
1da177e4 LT |
434 | out: |
435 | rcu_read_unlock(); | |
746b18d4 PZ |
436 | |
437 | return anon_vma; | |
438 | } | |
439 | ||
88c22088 PZ |
440 | /* |
441 | * Similar to page_get_anon_vma() except it locks the anon_vma. | |
442 | * | |
443 | * Its a little more complex as it tries to keep the fast path to a single | |
444 | * atomic op -- the trylock. If we fail the trylock, we fall back to getting a | |
445 | * reference like with page_get_anon_vma() and then block on the mutex. | |
446 | */ | |
4fc3f1d6 | 447 | struct anon_vma *page_lock_anon_vma_read(struct page *page) |
746b18d4 | 448 | { |
88c22088 | 449 | struct anon_vma *anon_vma = NULL; |
eee0f252 | 450 | struct anon_vma *root_anon_vma; |
88c22088 | 451 | unsigned long anon_mapping; |
746b18d4 | 452 | |
88c22088 PZ |
453 | rcu_read_lock(); |
454 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); | |
455 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) | |
456 | goto out; | |
457 | if (!page_mapped(page)) | |
458 | goto out; | |
459 | ||
460 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
eee0f252 | 461 | root_anon_vma = ACCESS_ONCE(anon_vma->root); |
4fc3f1d6 | 462 | if (down_read_trylock(&root_anon_vma->rwsem)) { |
88c22088 | 463 | /* |
eee0f252 HD |
464 | * If the page is still mapped, then this anon_vma is still |
465 | * its anon_vma, and holding the mutex ensures that it will | |
bc658c96 | 466 | * not go away, see anon_vma_free(). |
88c22088 | 467 | */ |
eee0f252 | 468 | if (!page_mapped(page)) { |
4fc3f1d6 | 469 | up_read(&root_anon_vma->rwsem); |
88c22088 PZ |
470 | anon_vma = NULL; |
471 | } | |
472 | goto out; | |
473 | } | |
746b18d4 | 474 | |
88c22088 PZ |
475 | /* trylock failed, we got to sleep */ |
476 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { | |
477 | anon_vma = NULL; | |
478 | goto out; | |
479 | } | |
480 | ||
481 | if (!page_mapped(page)) { | |
ef151648 | 482 | rcu_read_unlock(); |
88c22088 | 483 | put_anon_vma(anon_vma); |
ef151648 | 484 | return NULL; |
88c22088 PZ |
485 | } |
486 | ||
487 | /* we pinned the anon_vma, its safe to sleep */ | |
488 | rcu_read_unlock(); | |
4fc3f1d6 | 489 | anon_vma_lock_read(anon_vma); |
88c22088 PZ |
490 | |
491 | if (atomic_dec_and_test(&anon_vma->refcount)) { | |
492 | /* | |
493 | * Oops, we held the last refcount, release the lock | |
494 | * and bail -- can't simply use put_anon_vma() because | |
4fc3f1d6 | 495 | * we'll deadlock on the anon_vma_lock_write() recursion. |
88c22088 | 496 | */ |
4fc3f1d6 | 497 | anon_vma_unlock_read(anon_vma); |
88c22088 PZ |
498 | __put_anon_vma(anon_vma); |
499 | anon_vma = NULL; | |
500 | } | |
501 | ||
502 | return anon_vma; | |
503 | ||
504 | out: | |
505 | rcu_read_unlock(); | |
746b18d4 | 506 | return anon_vma; |
34bbd704 ON |
507 | } |
508 | ||
4fc3f1d6 | 509 | void page_unlock_anon_vma_read(struct anon_vma *anon_vma) |
34bbd704 | 510 | { |
4fc3f1d6 | 511 | anon_vma_unlock_read(anon_vma); |
1da177e4 LT |
512 | } |
513 | ||
514 | /* | |
3ad33b24 | 515 | * At what user virtual address is page expected in @vma? |
1da177e4 | 516 | */ |
86c2ad19 ML |
517 | static inline unsigned long |
518 | __vma_address(struct page *page, struct vm_area_struct *vma) | |
1da177e4 LT |
519 | { |
520 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1da177e4 | 521 | |
0fe6e20b NH |
522 | if (unlikely(is_vm_hugetlb_page(vma))) |
523 | pgoff = page->index << huge_page_order(page_hstate(page)); | |
86c2ad19 ML |
524 | |
525 | return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
526 | } | |
527 | ||
528 | inline unsigned long | |
529 | vma_address(struct page *page, struct vm_area_struct *vma) | |
530 | { | |
531 | unsigned long address = __vma_address(page, vma); | |
532 | ||
533 | /* page should be within @vma mapping range */ | |
534 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
535 | ||
1da177e4 LT |
536 | return address; |
537 | } | |
538 | ||
539 | /* | |
bf89c8c8 | 540 | * At what user virtual address is page expected in vma? |
ab941e0f | 541 | * Caller should check the page is actually part of the vma. |
1da177e4 LT |
542 | */ |
543 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
544 | { | |
86c2ad19 | 545 | unsigned long address; |
21d0d443 | 546 | if (PageAnon(page)) { |
4829b906 HD |
547 | struct anon_vma *page__anon_vma = page_anon_vma(page); |
548 | /* | |
549 | * Note: swapoff's unuse_vma() is more efficient with this | |
550 | * check, and needs it to match anon_vma when KSM is active. | |
551 | */ | |
552 | if (!vma->anon_vma || !page__anon_vma || | |
553 | vma->anon_vma->root != page__anon_vma->root) | |
21d0d443 AA |
554 | return -EFAULT; |
555 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
556 | if (!vma->vm_file || |
557 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
558 | return -EFAULT; |
559 | } else | |
560 | return -EFAULT; | |
86c2ad19 ML |
561 | address = __vma_address(page, vma); |
562 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) | |
563 | return -EFAULT; | |
564 | return address; | |
1da177e4 LT |
565 | } |
566 | ||
6219049a BL |
567 | pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) |
568 | { | |
569 | pgd_t *pgd; | |
570 | pud_t *pud; | |
571 | pmd_t *pmd = NULL; | |
572 | ||
573 | pgd = pgd_offset(mm, address); | |
574 | if (!pgd_present(*pgd)) | |
575 | goto out; | |
576 | ||
577 | pud = pud_offset(pgd, address); | |
578 | if (!pud_present(*pud)) | |
579 | goto out; | |
580 | ||
581 | pmd = pmd_offset(pud, address); | |
582 | if (!pmd_present(*pmd)) | |
583 | pmd = NULL; | |
584 | out: | |
585 | return pmd; | |
586 | } | |
587 | ||
81b4082d ND |
588 | /* |
589 | * Check that @page is mapped at @address into @mm. | |
590 | * | |
479db0bf NP |
591 | * If @sync is false, page_check_address may perform a racy check to avoid |
592 | * the page table lock when the pte is not present (helpful when reclaiming | |
593 | * highly shared pages). | |
594 | * | |
b8072f09 | 595 | * On success returns with pte mapped and locked. |
81b4082d | 596 | */ |
e9a81a82 | 597 | pte_t *__page_check_address(struct page *page, struct mm_struct *mm, |
479db0bf | 598 | unsigned long address, spinlock_t **ptlp, int sync) |
81b4082d | 599 | { |
81b4082d ND |
600 | pmd_t *pmd; |
601 | pte_t *pte; | |
c0718806 | 602 | spinlock_t *ptl; |
81b4082d | 603 | |
0fe6e20b | 604 | if (unlikely(PageHuge(page))) { |
398bbc57 | 605 | /* when pud is not present, pte will be NULL */ |
0fe6e20b | 606 | pte = huge_pte_offset(mm, address); |
398bbc57 JW |
607 | if (!pte) |
608 | return NULL; | |
609 | ||
0fe6e20b NH |
610 | ptl = &mm->page_table_lock; |
611 | goto check; | |
612 | } | |
613 | ||
6219049a BL |
614 | pmd = mm_find_pmd(mm, address); |
615 | if (!pmd) | |
c0718806 HD |
616 | return NULL; |
617 | ||
71e3aac0 AA |
618 | if (pmd_trans_huge(*pmd)) |
619 | return NULL; | |
c0718806 HD |
620 | |
621 | pte = pte_offset_map(pmd, address); | |
622 | /* Make a quick check before getting the lock */ | |
479db0bf | 623 | if (!sync && !pte_present(*pte)) { |
c0718806 HD |
624 | pte_unmap(pte); |
625 | return NULL; | |
626 | } | |
627 | ||
4c21e2f2 | 628 | ptl = pte_lockptr(mm, pmd); |
0fe6e20b | 629 | check: |
c0718806 HD |
630 | spin_lock(ptl); |
631 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
632 | *ptlp = ptl; | |
633 | return pte; | |
81b4082d | 634 | } |
c0718806 HD |
635 | pte_unmap_unlock(pte, ptl); |
636 | return NULL; | |
81b4082d ND |
637 | } |
638 | ||
b291f000 NP |
639 | /** |
640 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
641 | * @page: the page to test | |
642 | * @vma: the VMA to test | |
643 | * | |
644 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
645 | * if the page is not mapped into the page tables of this VMA. Only | |
646 | * valid for normal file or anonymous VMAs. | |
647 | */ | |
6a46079c | 648 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) |
b291f000 NP |
649 | { |
650 | unsigned long address; | |
651 | pte_t *pte; | |
652 | spinlock_t *ptl; | |
653 | ||
86c2ad19 ML |
654 | address = __vma_address(page, vma); |
655 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) | |
b291f000 NP |
656 | return 0; |
657 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); | |
658 | if (!pte) /* the page is not in this mm */ | |
659 | return 0; | |
660 | pte_unmap_unlock(pte, ptl); | |
661 | ||
662 | return 1; | |
663 | } | |
664 | ||
1da177e4 LT |
665 | /* |
666 | * Subfunctions of page_referenced: page_referenced_one called | |
667 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
668 | */ | |
5ad64688 HD |
669 | int page_referenced_one(struct page *page, struct vm_area_struct *vma, |
670 | unsigned long address, unsigned int *mapcount, | |
671 | unsigned long *vm_flags) | |
1da177e4 LT |
672 | { |
673 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 LT |
674 | int referenced = 0; |
675 | ||
71e3aac0 AA |
676 | if (unlikely(PageTransHuge(page))) { |
677 | pmd_t *pmd; | |
678 | ||
679 | spin_lock(&mm->page_table_lock); | |
2da28bfd AA |
680 | /* |
681 | * rmap might return false positives; we must filter | |
682 | * these out using page_check_address_pmd(). | |
683 | */ | |
71e3aac0 AA |
684 | pmd = page_check_address_pmd(page, mm, address, |
685 | PAGE_CHECK_ADDRESS_PMD_FLAG); | |
2da28bfd AA |
686 | if (!pmd) { |
687 | spin_unlock(&mm->page_table_lock); | |
688 | goto out; | |
689 | } | |
690 | ||
691 | if (vma->vm_flags & VM_LOCKED) { | |
692 | spin_unlock(&mm->page_table_lock); | |
693 | *mapcount = 0; /* break early from loop */ | |
694 | *vm_flags |= VM_LOCKED; | |
695 | goto out; | |
696 | } | |
697 | ||
698 | /* go ahead even if the pmd is pmd_trans_splitting() */ | |
699 | if (pmdp_clear_flush_young_notify(vma, address, pmd)) | |
71e3aac0 AA |
700 | referenced++; |
701 | spin_unlock(&mm->page_table_lock); | |
702 | } else { | |
703 | pte_t *pte; | |
704 | spinlock_t *ptl; | |
705 | ||
2da28bfd AA |
706 | /* |
707 | * rmap might return false positives; we must filter | |
708 | * these out using page_check_address(). | |
709 | */ | |
71e3aac0 AA |
710 | pte = page_check_address(page, mm, address, &ptl, 0); |
711 | if (!pte) | |
712 | goto out; | |
713 | ||
2da28bfd AA |
714 | if (vma->vm_flags & VM_LOCKED) { |
715 | pte_unmap_unlock(pte, ptl); | |
716 | *mapcount = 0; /* break early from loop */ | |
717 | *vm_flags |= VM_LOCKED; | |
718 | goto out; | |
719 | } | |
720 | ||
71e3aac0 AA |
721 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
722 | /* | |
723 | * Don't treat a reference through a sequentially read | |
724 | * mapping as such. If the page has been used in | |
725 | * another mapping, we will catch it; if this other | |
726 | * mapping is already gone, the unmap path will have | |
727 | * set PG_referenced or activated the page. | |
728 | */ | |
729 | if (likely(!VM_SequentialReadHint(vma))) | |
730 | referenced++; | |
731 | } | |
732 | pte_unmap_unlock(pte, ptl); | |
733 | } | |
734 | ||
c0718806 | 735 | (*mapcount)--; |
273f047e | 736 | |
6fe6b7e3 WF |
737 | if (referenced) |
738 | *vm_flags |= vma->vm_flags; | |
273f047e | 739 | out: |
1da177e4 LT |
740 | return referenced; |
741 | } | |
742 | ||
bed7161a | 743 | static int page_referenced_anon(struct page *page, |
72835c86 | 744 | struct mem_cgroup *memcg, |
6fe6b7e3 | 745 | unsigned long *vm_flags) |
1da177e4 LT |
746 | { |
747 | unsigned int mapcount; | |
748 | struct anon_vma *anon_vma; | |
bf181b9f | 749 | pgoff_t pgoff; |
5beb4930 | 750 | struct anon_vma_chain *avc; |
1da177e4 LT |
751 | int referenced = 0; |
752 | ||
4fc3f1d6 | 753 | anon_vma = page_lock_anon_vma_read(page); |
1da177e4 LT |
754 | if (!anon_vma) |
755 | return referenced; | |
756 | ||
757 | mapcount = page_mapcount(page); | |
bf181b9f ML |
758 | pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
759 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { | |
5beb4930 | 760 | struct vm_area_struct *vma = avc->vma; |
1cb1729b | 761 | unsigned long address = vma_address(page, vma); |
bed7161a BS |
762 | /* |
763 | * If we are reclaiming on behalf of a cgroup, skip | |
764 | * counting on behalf of references from different | |
765 | * cgroups | |
766 | */ | |
72835c86 | 767 | if (memcg && !mm_match_cgroup(vma->vm_mm, memcg)) |
bed7161a | 768 | continue; |
1cb1729b | 769 | referenced += page_referenced_one(page, vma, address, |
6fe6b7e3 | 770 | &mapcount, vm_flags); |
1da177e4 LT |
771 | if (!mapcount) |
772 | break; | |
773 | } | |
34bbd704 | 774 | |
4fc3f1d6 | 775 | page_unlock_anon_vma_read(anon_vma); |
1da177e4 LT |
776 | return referenced; |
777 | } | |
778 | ||
779 | /** | |
780 | * page_referenced_file - referenced check for object-based rmap | |
781 | * @page: the page we're checking references on. | |
72835c86 | 782 | * @memcg: target memory control group |
6fe6b7e3 | 783 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
784 | * |
785 | * For an object-based mapped page, find all the places it is mapped and | |
786 | * check/clear the referenced flag. This is done by following the page->mapping | |
787 | * pointer, then walking the chain of vmas it holds. It returns the number | |
788 | * of references it found. | |
789 | * | |
790 | * This function is only called from page_referenced for object-based pages. | |
791 | */ | |
bed7161a | 792 | static int page_referenced_file(struct page *page, |
72835c86 | 793 | struct mem_cgroup *memcg, |
6fe6b7e3 | 794 | unsigned long *vm_flags) |
1da177e4 LT |
795 | { |
796 | unsigned int mapcount; | |
797 | struct address_space *mapping = page->mapping; | |
798 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
799 | struct vm_area_struct *vma; | |
1da177e4 LT |
800 | int referenced = 0; |
801 | ||
802 | /* | |
803 | * The caller's checks on page->mapping and !PageAnon have made | |
804 | * sure that this is a file page: the check for page->mapping | |
805 | * excludes the case just before it gets set on an anon page. | |
806 | */ | |
807 | BUG_ON(PageAnon(page)); | |
808 | ||
809 | /* | |
810 | * The page lock not only makes sure that page->mapping cannot | |
811 | * suddenly be NULLified by truncation, it makes sure that the | |
812 | * structure at mapping cannot be freed and reused yet, | |
3d48ae45 | 813 | * so we can safely take mapping->i_mmap_mutex. |
1da177e4 LT |
814 | */ |
815 | BUG_ON(!PageLocked(page)); | |
816 | ||
3d48ae45 | 817 | mutex_lock(&mapping->i_mmap_mutex); |
1da177e4 LT |
818 | |
819 | /* | |
3d48ae45 | 820 | * i_mmap_mutex does not stabilize mapcount at all, but mapcount |
1da177e4 LT |
821 | * is more likely to be accurate if we note it after spinning. |
822 | */ | |
823 | mapcount = page_mapcount(page); | |
824 | ||
6b2dbba8 | 825 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
1cb1729b | 826 | unsigned long address = vma_address(page, vma); |
bed7161a BS |
827 | /* |
828 | * If we are reclaiming on behalf of a cgroup, skip | |
829 | * counting on behalf of references from different | |
830 | * cgroups | |
831 | */ | |
72835c86 | 832 | if (memcg && !mm_match_cgroup(vma->vm_mm, memcg)) |
bed7161a | 833 | continue; |
1cb1729b | 834 | referenced += page_referenced_one(page, vma, address, |
6fe6b7e3 | 835 | &mapcount, vm_flags); |
1da177e4 LT |
836 | if (!mapcount) |
837 | break; | |
838 | } | |
839 | ||
3d48ae45 | 840 | mutex_unlock(&mapping->i_mmap_mutex); |
1da177e4 LT |
841 | return referenced; |
842 | } | |
843 | ||
844 | /** | |
845 | * page_referenced - test if the page was referenced | |
846 | * @page: the page to test | |
847 | * @is_locked: caller holds lock on the page | |
72835c86 | 848 | * @memcg: target memory cgroup |
6fe6b7e3 | 849 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
850 | * |
851 | * Quick test_and_clear_referenced for all mappings to a page, | |
852 | * returns the number of ptes which referenced the page. | |
853 | */ | |
6fe6b7e3 WF |
854 | int page_referenced(struct page *page, |
855 | int is_locked, | |
72835c86 | 856 | struct mem_cgroup *memcg, |
6fe6b7e3 | 857 | unsigned long *vm_flags) |
1da177e4 LT |
858 | { |
859 | int referenced = 0; | |
5ad64688 | 860 | int we_locked = 0; |
1da177e4 | 861 | |
6fe6b7e3 | 862 | *vm_flags = 0; |
3ca7b3c5 | 863 | if (page_mapped(page) && page_rmapping(page)) { |
5ad64688 HD |
864 | if (!is_locked && (!PageAnon(page) || PageKsm(page))) { |
865 | we_locked = trylock_page(page); | |
866 | if (!we_locked) { | |
867 | referenced++; | |
868 | goto out; | |
869 | } | |
870 | } | |
871 | if (unlikely(PageKsm(page))) | |
72835c86 | 872 | referenced += page_referenced_ksm(page, memcg, |
5ad64688 HD |
873 | vm_flags); |
874 | else if (PageAnon(page)) | |
72835c86 | 875 | referenced += page_referenced_anon(page, memcg, |
6fe6b7e3 | 876 | vm_flags); |
5ad64688 | 877 | else if (page->mapping) |
72835c86 | 878 | referenced += page_referenced_file(page, memcg, |
6fe6b7e3 | 879 | vm_flags); |
5ad64688 | 880 | if (we_locked) |
1da177e4 | 881 | unlock_page(page); |
50a15981 MS |
882 | |
883 | if (page_test_and_clear_young(page_to_pfn(page))) | |
884 | referenced++; | |
1da177e4 | 885 | } |
5ad64688 | 886 | out: |
1da177e4 LT |
887 | return referenced; |
888 | } | |
889 | ||
1cb1729b HD |
890 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, |
891 | unsigned long address) | |
d08b3851 PZ |
892 | { |
893 | struct mm_struct *mm = vma->vm_mm; | |
c2fda5fe | 894 | pte_t *pte; |
d08b3851 PZ |
895 | spinlock_t *ptl; |
896 | int ret = 0; | |
897 | ||
479db0bf | 898 | pte = page_check_address(page, mm, address, &ptl, 1); |
d08b3851 PZ |
899 | if (!pte) |
900 | goto out; | |
901 | ||
c2fda5fe PZ |
902 | if (pte_dirty(*pte) || pte_write(*pte)) { |
903 | pte_t entry; | |
d08b3851 | 904 | |
c2fda5fe | 905 | flush_cache_page(vma, address, pte_pfn(*pte)); |
2ec74c3e | 906 | entry = ptep_clear_flush(vma, address, pte); |
c2fda5fe PZ |
907 | entry = pte_wrprotect(entry); |
908 | entry = pte_mkclean(entry); | |
d6e88e67 | 909 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
910 | ret = 1; |
911 | } | |
d08b3851 | 912 | |
d08b3851 | 913 | pte_unmap_unlock(pte, ptl); |
2ec74c3e SG |
914 | |
915 | if (ret) | |
916 | mmu_notifier_invalidate_page(mm, address); | |
d08b3851 PZ |
917 | out: |
918 | return ret; | |
919 | } | |
920 | ||
921 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
922 | { | |
923 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
924 | struct vm_area_struct *vma; | |
d08b3851 PZ |
925 | int ret = 0; |
926 | ||
927 | BUG_ON(PageAnon(page)); | |
928 | ||
3d48ae45 | 929 | mutex_lock(&mapping->i_mmap_mutex); |
6b2dbba8 | 930 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
1cb1729b HD |
931 | if (vma->vm_flags & VM_SHARED) { |
932 | unsigned long address = vma_address(page, vma); | |
1cb1729b HD |
933 | ret += page_mkclean_one(page, vma, address); |
934 | } | |
d08b3851 | 935 | } |
3d48ae45 | 936 | mutex_unlock(&mapping->i_mmap_mutex); |
d08b3851 PZ |
937 | return ret; |
938 | } | |
939 | ||
940 | int page_mkclean(struct page *page) | |
941 | { | |
942 | int ret = 0; | |
943 | ||
944 | BUG_ON(!PageLocked(page)); | |
945 | ||
946 | if (page_mapped(page)) { | |
947 | struct address_space *mapping = page_mapping(page); | |
ef5d437f | 948 | if (mapping) |
d08b3851 PZ |
949 | ret = page_mkclean_file(mapping, page); |
950 | } | |
951 | ||
952 | return ret; | |
953 | } | |
60b59bea | 954 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 955 | |
c44b6743 RR |
956 | /** |
957 | * page_move_anon_rmap - move a page to our anon_vma | |
958 | * @page: the page to move to our anon_vma | |
959 | * @vma: the vma the page belongs to | |
960 | * @address: the user virtual address mapped | |
961 | * | |
962 | * When a page belongs exclusively to one process after a COW event, | |
963 | * that page can be moved into the anon_vma that belongs to just that | |
964 | * process, so the rmap code will not search the parent or sibling | |
965 | * processes. | |
966 | */ | |
967 | void page_move_anon_rmap(struct page *page, | |
968 | struct vm_area_struct *vma, unsigned long address) | |
969 | { | |
970 | struct anon_vma *anon_vma = vma->anon_vma; | |
971 | ||
972 | VM_BUG_ON(!PageLocked(page)); | |
973 | VM_BUG_ON(!anon_vma); | |
974 | VM_BUG_ON(page->index != linear_page_index(vma, address)); | |
975 | ||
976 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
977 | page->mapping = (struct address_space *) anon_vma; | |
978 | } | |
979 | ||
9617d95e | 980 | /** |
4e1c1975 AK |
981 | * __page_set_anon_rmap - set up new anonymous rmap |
982 | * @page: Page to add to rmap | |
983 | * @vma: VM area to add page to. | |
984 | * @address: User virtual address of the mapping | |
e8a03feb | 985 | * @exclusive: the page is exclusively owned by the current process |
9617d95e NP |
986 | */ |
987 | static void __page_set_anon_rmap(struct page *page, | |
e8a03feb | 988 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
9617d95e | 989 | { |
e8a03feb | 990 | struct anon_vma *anon_vma = vma->anon_vma; |
ea90002b | 991 | |
e8a03feb | 992 | BUG_ON(!anon_vma); |
ea90002b | 993 | |
4e1c1975 AK |
994 | if (PageAnon(page)) |
995 | return; | |
996 | ||
ea90002b | 997 | /* |
e8a03feb RR |
998 | * If the page isn't exclusively mapped into this vma, |
999 | * we must use the _oldest_ possible anon_vma for the | |
1000 | * page mapping! | |
ea90002b | 1001 | */ |
4e1c1975 | 1002 | if (!exclusive) |
288468c3 | 1003 | anon_vma = anon_vma->root; |
9617d95e | 1004 | |
9617d95e NP |
1005 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1006 | page->mapping = (struct address_space *) anon_vma; | |
9617d95e | 1007 | page->index = linear_page_index(vma, address); |
9617d95e NP |
1008 | } |
1009 | ||
c97a9e10 | 1010 | /** |
43d8eac4 | 1011 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
c97a9e10 NP |
1012 | * @page: the page to add the mapping to |
1013 | * @vma: the vm area in which the mapping is added | |
1014 | * @address: the user virtual address mapped | |
1015 | */ | |
1016 | static void __page_check_anon_rmap(struct page *page, | |
1017 | struct vm_area_struct *vma, unsigned long address) | |
1018 | { | |
1019 | #ifdef CONFIG_DEBUG_VM | |
1020 | /* | |
1021 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
1022 | * be set up correctly at this point. | |
1023 | * | |
1024 | * We have exclusion against page_add_anon_rmap because the caller | |
1025 | * always holds the page locked, except if called from page_dup_rmap, | |
1026 | * in which case the page is already known to be setup. | |
1027 | * | |
1028 | * We have exclusion against page_add_new_anon_rmap because those pages | |
1029 | * are initially only visible via the pagetables, and the pte is locked | |
1030 | * over the call to page_add_new_anon_rmap. | |
1031 | */ | |
44ab57a0 | 1032 | BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); |
c97a9e10 NP |
1033 | BUG_ON(page->index != linear_page_index(vma, address)); |
1034 | #endif | |
1035 | } | |
1036 | ||
1da177e4 LT |
1037 | /** |
1038 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
1039 | * @page: the page to add the mapping to | |
1040 | * @vma: the vm area in which the mapping is added | |
1041 | * @address: the user virtual address mapped | |
1042 | * | |
5ad64688 | 1043 | * The caller needs to hold the pte lock, and the page must be locked in |
80e14822 HD |
1044 | * the anon_vma case: to serialize mapping,index checking after setting, |
1045 | * and to ensure that PageAnon is not being upgraded racily to PageKsm | |
1046 | * (but PageKsm is never downgraded to PageAnon). | |
1da177e4 LT |
1047 | */ |
1048 | void page_add_anon_rmap(struct page *page, | |
1049 | struct vm_area_struct *vma, unsigned long address) | |
ad8c2ee8 RR |
1050 | { |
1051 | do_page_add_anon_rmap(page, vma, address, 0); | |
1052 | } | |
1053 | ||
1054 | /* | |
1055 | * Special version of the above for do_swap_page, which often runs | |
1056 | * into pages that are exclusively owned by the current process. | |
1057 | * Everybody else should continue to use page_add_anon_rmap above. | |
1058 | */ | |
1059 | void do_page_add_anon_rmap(struct page *page, | |
1060 | struct vm_area_struct *vma, unsigned long address, int exclusive) | |
1da177e4 | 1061 | { |
5ad64688 | 1062 | int first = atomic_inc_and_test(&page->_mapcount); |
79134171 AA |
1063 | if (first) { |
1064 | if (!PageTransHuge(page)) | |
1065 | __inc_zone_page_state(page, NR_ANON_PAGES); | |
1066 | else | |
1067 | __inc_zone_page_state(page, | |
1068 | NR_ANON_TRANSPARENT_HUGEPAGES); | |
1069 | } | |
5ad64688 HD |
1070 | if (unlikely(PageKsm(page))) |
1071 | return; | |
1072 | ||
c97a9e10 | 1073 | VM_BUG_ON(!PageLocked(page)); |
5dbe0af4 | 1074 | /* address might be in next vma when migration races vma_adjust */ |
5ad64688 | 1075 | if (first) |
ad8c2ee8 | 1076 | __page_set_anon_rmap(page, vma, address, exclusive); |
69029cd5 | 1077 | else |
c97a9e10 | 1078 | __page_check_anon_rmap(page, vma, address); |
1da177e4 LT |
1079 | } |
1080 | ||
43d8eac4 | 1081 | /** |
9617d95e NP |
1082 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
1083 | * @page: the page to add the mapping to | |
1084 | * @vma: the vm area in which the mapping is added | |
1085 | * @address: the user virtual address mapped | |
1086 | * | |
1087 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
1088 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 1089 | * Page does not have to be locked. |
9617d95e NP |
1090 | */ |
1091 | void page_add_new_anon_rmap(struct page *page, | |
1092 | struct vm_area_struct *vma, unsigned long address) | |
1093 | { | |
b5934c53 | 1094 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
cbf84b7a HD |
1095 | SetPageSwapBacked(page); |
1096 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ | |
79134171 AA |
1097 | if (!PageTransHuge(page)) |
1098 | __inc_zone_page_state(page, NR_ANON_PAGES); | |
1099 | else | |
1100 | __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
e8a03feb | 1101 | __page_set_anon_rmap(page, vma, address, 1); |
39b5f29a | 1102 | if (!mlocked_vma_newpage(vma, page)) |
cbf84b7a | 1103 | lru_cache_add_lru(page, LRU_ACTIVE_ANON); |
b5934c53 HD |
1104 | else |
1105 | add_page_to_unevictable_list(page); | |
9617d95e NP |
1106 | } |
1107 | ||
1da177e4 LT |
1108 | /** |
1109 | * page_add_file_rmap - add pte mapping to a file page | |
1110 | * @page: the page to add the mapping to | |
1111 | * | |
b8072f09 | 1112 | * The caller needs to hold the pte lock. |
1da177e4 LT |
1113 | */ |
1114 | void page_add_file_rmap(struct page *page) | |
1115 | { | |
89c06bd5 KH |
1116 | bool locked; |
1117 | unsigned long flags; | |
1118 | ||
1119 | mem_cgroup_begin_update_page_stat(page, &locked, &flags); | |
d69b042f | 1120 | if (atomic_inc_and_test(&page->_mapcount)) { |
65ba55f5 | 1121 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
2a7106f2 | 1122 | mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED); |
d69b042f | 1123 | } |
89c06bd5 | 1124 | mem_cgroup_end_update_page_stat(page, &locked, &flags); |
1da177e4 LT |
1125 | } |
1126 | ||
1127 | /** | |
1128 | * page_remove_rmap - take down pte mapping from a page | |
1129 | * @page: page to remove mapping from | |
1130 | * | |
b8072f09 | 1131 | * The caller needs to hold the pte lock. |
1da177e4 | 1132 | */ |
edc315fd | 1133 | void page_remove_rmap(struct page *page) |
1da177e4 | 1134 | { |
89c06bd5 KH |
1135 | bool anon = PageAnon(page); |
1136 | bool locked; | |
1137 | unsigned long flags; | |
1138 | ||
1139 | /* | |
1140 | * The anon case has no mem_cgroup page_stat to update; but may | |
1141 | * uncharge_page() below, where the lock ordering can deadlock if | |
1142 | * we hold the lock against page_stat move: so avoid it on anon. | |
1143 | */ | |
1144 | if (!anon) | |
1145 | mem_cgroup_begin_update_page_stat(page, &locked, &flags); | |
1146 | ||
b904dcfe KM |
1147 | /* page still mapped by someone else? */ |
1148 | if (!atomic_add_negative(-1, &page->_mapcount)) | |
89c06bd5 | 1149 | goto out; |
b904dcfe | 1150 | |
0fe6e20b NH |
1151 | /* |
1152 | * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED | |
1153 | * and not charged by memcg for now. | |
1154 | */ | |
1155 | if (unlikely(PageHuge(page))) | |
89c06bd5 KH |
1156 | goto out; |
1157 | if (anon) { | |
b904dcfe | 1158 | mem_cgroup_uncharge_page(page); |
79134171 AA |
1159 | if (!PageTransHuge(page)) |
1160 | __dec_zone_page_state(page, NR_ANON_PAGES); | |
1161 | else | |
1162 | __dec_zone_page_state(page, | |
1163 | NR_ANON_TRANSPARENT_HUGEPAGES); | |
b904dcfe KM |
1164 | } else { |
1165 | __dec_zone_page_state(page, NR_FILE_MAPPED); | |
2a7106f2 | 1166 | mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED); |
e6c509f8 | 1167 | mem_cgroup_end_update_page_stat(page, &locked, &flags); |
b904dcfe | 1168 | } |
e6c509f8 HD |
1169 | if (unlikely(PageMlocked(page))) |
1170 | clear_page_mlock(page); | |
b904dcfe KM |
1171 | /* |
1172 | * It would be tidy to reset the PageAnon mapping here, | |
1173 | * but that might overwrite a racing page_add_anon_rmap | |
1174 | * which increments mapcount after us but sets mapping | |
1175 | * before us: so leave the reset to free_hot_cold_page, | |
1176 | * and remember that it's only reliable while mapped. | |
1177 | * Leaving it set also helps swapoff to reinstate ptes | |
1178 | * faster for those pages still in swapcache. | |
1179 | */ | |
e6c509f8 | 1180 | return; |
89c06bd5 KH |
1181 | out: |
1182 | if (!anon) | |
1183 | mem_cgroup_end_update_page_stat(page, &locked, &flags); | |
1da177e4 LT |
1184 | } |
1185 | ||
1186 | /* | |
1187 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
99ef0315 | 1188 | * repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file. |
1da177e4 | 1189 | */ |
5ad64688 HD |
1190 | int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
1191 | unsigned long address, enum ttu_flags flags) | |
1da177e4 LT |
1192 | { |
1193 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 LT |
1194 | pte_t *pte; |
1195 | pte_t pteval; | |
c0718806 | 1196 | spinlock_t *ptl; |
1da177e4 LT |
1197 | int ret = SWAP_AGAIN; |
1198 | ||
479db0bf | 1199 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 | 1200 | if (!pte) |
81b4082d | 1201 | goto out; |
1da177e4 LT |
1202 | |
1203 | /* | |
1204 | * If the page is mlock()d, we cannot swap it out. | |
1205 | * If it's recently referenced (perhaps page_referenced | |
1206 | * skipped over this mm) then we should reactivate it. | |
1207 | */ | |
14fa31b8 | 1208 | if (!(flags & TTU_IGNORE_MLOCK)) { |
caed0f48 KM |
1209 | if (vma->vm_flags & VM_LOCKED) |
1210 | goto out_mlock; | |
1211 | ||
af8e3354 | 1212 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
53f79acb | 1213 | goto out_unmap; |
14fa31b8 AK |
1214 | } |
1215 | if (!(flags & TTU_IGNORE_ACCESS)) { | |
b291f000 NP |
1216 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
1217 | ret = SWAP_FAIL; | |
1218 | goto out_unmap; | |
1219 | } | |
1220 | } | |
1da177e4 | 1221 | |
1da177e4 LT |
1222 | /* Nuke the page table entry. */ |
1223 | flush_cache_page(vma, address, page_to_pfn(page)); | |
2ec74c3e | 1224 | pteval = ptep_clear_flush(vma, address, pte); |
1da177e4 LT |
1225 | |
1226 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
1227 | if (pte_dirty(pteval)) | |
1228 | set_page_dirty(page); | |
1229 | ||
365e9c87 HD |
1230 | /* Update high watermark before we lower rss */ |
1231 | update_hiwater_rss(mm); | |
1232 | ||
888b9f7c | 1233 | if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
5f24ae58 NH |
1234 | if (!PageHuge(page)) { |
1235 | if (PageAnon(page)) | |
1236 | dec_mm_counter(mm, MM_ANONPAGES); | |
1237 | else | |
1238 | dec_mm_counter(mm, MM_FILEPAGES); | |
1239 | } | |
888b9f7c | 1240 | set_pte_at(mm, address, pte, |
5f24ae58 | 1241 | swp_entry_to_pte(make_hwpoison_entry(page))); |
888b9f7c | 1242 | } else if (PageAnon(page)) { |
4c21e2f2 | 1243 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
1244 | |
1245 | if (PageSwapCache(page)) { | |
1246 | /* | |
1247 | * Store the swap location in the pte. | |
1248 | * See handle_pte_fault() ... | |
1249 | */ | |
570a335b HD |
1250 | if (swap_duplicate(entry) < 0) { |
1251 | set_pte_at(mm, address, pte, pteval); | |
1252 | ret = SWAP_FAIL; | |
1253 | goto out_unmap; | |
1254 | } | |
0697212a CL |
1255 | if (list_empty(&mm->mmlist)) { |
1256 | spin_lock(&mmlist_lock); | |
1257 | if (list_empty(&mm->mmlist)) | |
1258 | list_add(&mm->mmlist, &init_mm.mmlist); | |
1259 | spin_unlock(&mmlist_lock); | |
1260 | } | |
d559db08 | 1261 | dec_mm_counter(mm, MM_ANONPAGES); |
b084d435 | 1262 | inc_mm_counter(mm, MM_SWAPENTS); |
ce1744f4 | 1263 | } else if (IS_ENABLED(CONFIG_MIGRATION)) { |
0697212a CL |
1264 | /* |
1265 | * Store the pfn of the page in a special migration | |
1266 | * pte. do_swap_page() will wait until the migration | |
1267 | * pte is removed and then restart fault handling. | |
1268 | */ | |
14fa31b8 | 1269 | BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION); |
0697212a | 1270 | entry = make_migration_entry(page, pte_write(pteval)); |
1da177e4 LT |
1271 | } |
1272 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
1273 | BUG_ON(pte_file(*pte)); | |
ce1744f4 KK |
1274 | } else if (IS_ENABLED(CONFIG_MIGRATION) && |
1275 | (TTU_ACTION(flags) == TTU_MIGRATION)) { | |
04e62a29 CL |
1276 | /* Establish migration entry for a file page */ |
1277 | swp_entry_t entry; | |
1278 | entry = make_migration_entry(page, pte_write(pteval)); | |
1279 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
1280 | } else | |
d559db08 | 1281 | dec_mm_counter(mm, MM_FILEPAGES); |
1da177e4 | 1282 | |
edc315fd | 1283 | page_remove_rmap(page); |
1da177e4 LT |
1284 | page_cache_release(page); |
1285 | ||
1286 | out_unmap: | |
c0718806 | 1287 | pte_unmap_unlock(pte, ptl); |
2ec74c3e SG |
1288 | if (ret != SWAP_FAIL) |
1289 | mmu_notifier_invalidate_page(mm, address); | |
caed0f48 KM |
1290 | out: |
1291 | return ret; | |
53f79acb | 1292 | |
caed0f48 KM |
1293 | out_mlock: |
1294 | pte_unmap_unlock(pte, ptl); | |
1295 | ||
1296 | ||
1297 | /* | |
1298 | * We need mmap_sem locking, Otherwise VM_LOCKED check makes | |
1299 | * unstable result and race. Plus, We can't wait here because | |
5a505085 | 1300 | * we now hold anon_vma->rwsem or mapping->i_mmap_mutex. |
caed0f48 KM |
1301 | * if trylock failed, the page remain in evictable lru and later |
1302 | * vmscan could retry to move the page to unevictable lru if the | |
1303 | * page is actually mlocked. | |
1304 | */ | |
1305 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
1306 | if (vma->vm_flags & VM_LOCKED) { | |
1307 | mlock_vma_page(page); | |
1308 | ret = SWAP_MLOCK; | |
53f79acb | 1309 | } |
caed0f48 | 1310 | up_read(&vma->vm_mm->mmap_sem); |
53f79acb | 1311 | } |
1da177e4 LT |
1312 | return ret; |
1313 | } | |
1314 | ||
1315 | /* | |
1316 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
1317 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
1318 | * Consequently, given a particular page and its ->index, we cannot locate the | |
1319 | * ptes which are mapping that page without an exhaustive linear search. | |
1320 | * | |
1321 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
1322 | * maps the file to which the target page belongs. The ->vm_private_data field | |
1323 | * holds the current cursor into that scan. Successive searches will circulate | |
1324 | * around the vma's virtual address space. | |
1325 | * | |
1326 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
1327 | * more scanning pressure is placed against them as well. Eventually pages | |
1328 | * will become fully unmapped and are eligible for eviction. | |
1329 | * | |
1330 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
1331 | * there there won't be many ptes located within the scan cluster. In this case | |
1332 | * maybe we could scan further - to the end of the pte page, perhaps. | |
b291f000 NP |
1333 | * |
1334 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can | |
1335 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, | |
1336 | * rather than unmapping them. If we encounter the "check_page" that vmscan is | |
1337 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. | |
1da177e4 LT |
1338 | */ |
1339 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
1340 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
1341 | ||
b291f000 NP |
1342 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
1343 | struct vm_area_struct *vma, struct page *check_page) | |
1da177e4 LT |
1344 | { |
1345 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 | 1346 | pmd_t *pmd; |
c0718806 | 1347 | pte_t *pte; |
1da177e4 | 1348 | pte_t pteval; |
c0718806 | 1349 | spinlock_t *ptl; |
1da177e4 LT |
1350 | struct page *page; |
1351 | unsigned long address; | |
2ec74c3e SG |
1352 | unsigned long mmun_start; /* For mmu_notifiers */ |
1353 | unsigned long mmun_end; /* For mmu_notifiers */ | |
1da177e4 | 1354 | unsigned long end; |
b291f000 NP |
1355 | int ret = SWAP_AGAIN; |
1356 | int locked_vma = 0; | |
1da177e4 | 1357 | |
1da177e4 LT |
1358 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
1359 | end = address + CLUSTER_SIZE; | |
1360 | if (address < vma->vm_start) | |
1361 | address = vma->vm_start; | |
1362 | if (end > vma->vm_end) | |
1363 | end = vma->vm_end; | |
1364 | ||
6219049a BL |
1365 | pmd = mm_find_pmd(mm, address); |
1366 | if (!pmd) | |
b291f000 NP |
1367 | return ret; |
1368 | ||
2ec74c3e SG |
1369 | mmun_start = address; |
1370 | mmun_end = end; | |
1371 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1372 | ||
b291f000 | 1373 | /* |
af8e3354 | 1374 | * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, |
b291f000 NP |
1375 | * keep the sem while scanning the cluster for mlocking pages. |
1376 | */ | |
af8e3354 | 1377 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
b291f000 NP |
1378 | locked_vma = (vma->vm_flags & VM_LOCKED); |
1379 | if (!locked_vma) | |
1380 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ | |
1381 | } | |
c0718806 HD |
1382 | |
1383 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 1384 | |
365e9c87 HD |
1385 | /* Update high watermark before we lower rss */ |
1386 | update_hiwater_rss(mm); | |
1387 | ||
c0718806 | 1388 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
1389 | if (!pte_present(*pte)) |
1390 | continue; | |
6aab341e LT |
1391 | page = vm_normal_page(vma, address, *pte); |
1392 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 | 1393 | |
b291f000 | 1394 | if (locked_vma) { |
77552735 VB |
1395 | if (page == check_page) { |
1396 | /* we know we have check_page locked */ | |
1397 | mlock_vma_page(page); | |
b291f000 | 1398 | ret = SWAP_MLOCK; |
77552735 VB |
1399 | } else if (trylock_page(page)) { |
1400 | /* | |
1401 | * If we can lock the page, perform mlock. | |
1402 | * Otherwise leave the page alone, it will be | |
1403 | * eventually encountered again later. | |
1404 | */ | |
1405 | mlock_vma_page(page); | |
1406 | unlock_page(page); | |
1407 | } | |
b291f000 NP |
1408 | continue; /* don't unmap */ |
1409 | } | |
1410 | ||
cddb8a5c | 1411 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1da177e4 LT |
1412 | continue; |
1413 | ||
1414 | /* Nuke the page table entry. */ | |
eca35133 | 1415 | flush_cache_page(vma, address, pte_pfn(*pte)); |
2ec74c3e | 1416 | pteval = ptep_clear_flush(vma, address, pte); |
1da177e4 LT |
1417 | |
1418 | /* If nonlinear, store the file page offset in the pte. */ | |
1419 | if (page->index != linear_page_index(vma, address)) | |
1420 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
1421 | ||
1422 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
1423 | if (pte_dirty(pteval)) | |
1424 | set_page_dirty(page); | |
1425 | ||
edc315fd | 1426 | page_remove_rmap(page); |
1da177e4 | 1427 | page_cache_release(page); |
d559db08 | 1428 | dec_mm_counter(mm, MM_FILEPAGES); |
1da177e4 LT |
1429 | (*mapcount)--; |
1430 | } | |
c0718806 | 1431 | pte_unmap_unlock(pte - 1, ptl); |
2ec74c3e | 1432 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b291f000 NP |
1433 | if (locked_vma) |
1434 | up_read(&vma->vm_mm->mmap_sem); | |
1435 | return ret; | |
1da177e4 LT |
1436 | } |
1437 | ||
71e3aac0 | 1438 | bool is_vma_temporary_stack(struct vm_area_struct *vma) |
a8bef8ff MG |
1439 | { |
1440 | int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); | |
1441 | ||
1442 | if (!maybe_stack) | |
1443 | return false; | |
1444 | ||
1445 | if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == | |
1446 | VM_STACK_INCOMPLETE_SETUP) | |
1447 | return true; | |
1448 | ||
1449 | return false; | |
1450 | } | |
1451 | ||
b291f000 NP |
1452 | /** |
1453 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based | |
1454 | * rmap method | |
1455 | * @page: the page to unmap/unlock | |
8051be5e | 1456 | * @flags: action and flags |
b291f000 NP |
1457 | * |
1458 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1459 | * contained in the anon_vma struct it points to. | |
1460 | * | |
1461 | * This function is only called from try_to_unmap/try_to_munlock for | |
1462 | * anonymous pages. | |
1463 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1464 | * where the page was found will be held for write. So, we won't recheck | |
1465 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1466 | * 'LOCKED. | |
1467 | */ | |
14fa31b8 | 1468 | static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1469 | { |
1470 | struct anon_vma *anon_vma; | |
bf181b9f | 1471 | pgoff_t pgoff; |
5beb4930 | 1472 | struct anon_vma_chain *avc; |
1da177e4 | 1473 | int ret = SWAP_AGAIN; |
b291f000 | 1474 | |
4fc3f1d6 | 1475 | anon_vma = page_lock_anon_vma_read(page); |
1da177e4 LT |
1476 | if (!anon_vma) |
1477 | return ret; | |
1478 | ||
bf181b9f ML |
1479 | pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
1480 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { | |
5beb4930 | 1481 | struct vm_area_struct *vma = avc->vma; |
a8bef8ff MG |
1482 | unsigned long address; |
1483 | ||
1484 | /* | |
1485 | * During exec, a temporary VMA is setup and later moved. | |
1486 | * The VMA is moved under the anon_vma lock but not the | |
1487 | * page tables leading to a race where migration cannot | |
1488 | * find the migration ptes. Rather than increasing the | |
1489 | * locking requirements of exec(), migration skips | |
1490 | * temporary VMAs until after exec() completes. | |
1491 | */ | |
ce1744f4 | 1492 | if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) && |
a8bef8ff MG |
1493 | is_vma_temporary_stack(vma)) |
1494 | continue; | |
1495 | ||
1496 | address = vma_address(page, vma); | |
1cb1729b | 1497 | ret = try_to_unmap_one(page, vma, address, flags); |
53f79acb HD |
1498 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1499 | break; | |
1da177e4 | 1500 | } |
34bbd704 | 1501 | |
4fc3f1d6 | 1502 | page_unlock_anon_vma_read(anon_vma); |
1da177e4 LT |
1503 | return ret; |
1504 | } | |
1505 | ||
1506 | /** | |
b291f000 NP |
1507 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
1508 | * @page: the page to unmap/unlock | |
14fa31b8 | 1509 | * @flags: action and flags |
1da177e4 LT |
1510 | * |
1511 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1512 | * contained in the address_space struct it points to. | |
1513 | * | |
b291f000 NP |
1514 | * This function is only called from try_to_unmap/try_to_munlock for |
1515 | * object-based pages. | |
1516 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1517 | * where the page was found will be held for write. So, we won't recheck | |
1518 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1519 | * 'LOCKED. | |
1da177e4 | 1520 | */ |
14fa31b8 | 1521 | static int try_to_unmap_file(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1522 | { |
1523 | struct address_space *mapping = page->mapping; | |
1524 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1525 | struct vm_area_struct *vma; | |
1da177e4 LT |
1526 | int ret = SWAP_AGAIN; |
1527 | unsigned long cursor; | |
1528 | unsigned long max_nl_cursor = 0; | |
1529 | unsigned long max_nl_size = 0; | |
1530 | unsigned int mapcount; | |
1531 | ||
369a713e HD |
1532 | if (PageHuge(page)) |
1533 | pgoff = page->index << compound_order(page); | |
1534 | ||
3d48ae45 | 1535 | mutex_lock(&mapping->i_mmap_mutex); |
6b2dbba8 | 1536 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
1cb1729b | 1537 | unsigned long address = vma_address(page, vma); |
1cb1729b | 1538 | ret = try_to_unmap_one(page, vma, address, flags); |
53f79acb HD |
1539 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1540 | goto out; | |
1da177e4 LT |
1541 | } |
1542 | ||
1543 | if (list_empty(&mapping->i_mmap_nonlinear)) | |
1544 | goto out; | |
1545 | ||
53f79acb HD |
1546 | /* |
1547 | * We don't bother to try to find the munlocked page in nonlinears. | |
1548 | * It's costly. Instead, later, page reclaim logic may call | |
1549 | * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily. | |
1550 | */ | |
1551 | if (TTU_ACTION(flags) == TTU_MUNLOCK) | |
1552 | goto out; | |
1553 | ||
1da177e4 | 1554 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
6b2dbba8 | 1555 | shared.nonlinear) { |
1da177e4 LT |
1556 | cursor = (unsigned long) vma->vm_private_data; |
1557 | if (cursor > max_nl_cursor) | |
1558 | max_nl_cursor = cursor; | |
1559 | cursor = vma->vm_end - vma->vm_start; | |
1560 | if (cursor > max_nl_size) | |
1561 | max_nl_size = cursor; | |
1562 | } | |
1563 | ||
b291f000 | 1564 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1da177e4 LT |
1565 | ret = SWAP_FAIL; |
1566 | goto out; | |
1567 | } | |
1568 | ||
1569 | /* | |
1570 | * We don't try to search for this page in the nonlinear vmas, | |
1571 | * and page_referenced wouldn't have found it anyway. Instead | |
1572 | * just walk the nonlinear vmas trying to age and unmap some. | |
1573 | * The mapcount of the page we came in with is irrelevant, | |
1574 | * but even so use it as a guide to how hard we should try? | |
1575 | */ | |
1576 | mapcount = page_mapcount(page); | |
1577 | if (!mapcount) | |
1578 | goto out; | |
3d48ae45 | 1579 | cond_resched(); |
1da177e4 LT |
1580 | |
1581 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
1582 | if (max_nl_cursor == 0) | |
1583 | max_nl_cursor = CLUSTER_SIZE; | |
1584 | ||
1585 | do { | |
1586 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
6b2dbba8 | 1587 | shared.nonlinear) { |
1da177e4 | 1588 | cursor = (unsigned long) vma->vm_private_data; |
839b9685 | 1589 | while ( cursor < max_nl_cursor && |
1da177e4 | 1590 | cursor < vma->vm_end - vma->vm_start) { |
53f79acb HD |
1591 | if (try_to_unmap_cluster(cursor, &mapcount, |
1592 | vma, page) == SWAP_MLOCK) | |
1593 | ret = SWAP_MLOCK; | |
1da177e4 LT |
1594 | cursor += CLUSTER_SIZE; |
1595 | vma->vm_private_data = (void *) cursor; | |
1596 | if ((int)mapcount <= 0) | |
1597 | goto out; | |
1598 | } | |
1599 | vma->vm_private_data = (void *) max_nl_cursor; | |
1600 | } | |
3d48ae45 | 1601 | cond_resched(); |
1da177e4 LT |
1602 | max_nl_cursor += CLUSTER_SIZE; |
1603 | } while (max_nl_cursor <= max_nl_size); | |
1604 | ||
1605 | /* | |
1606 | * Don't loop forever (perhaps all the remaining pages are | |
1607 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
1608 | * vmas, now forgetting on which ones it had fallen behind. | |
1609 | */ | |
6b2dbba8 | 1610 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear) |
101d2be7 | 1611 | vma->vm_private_data = NULL; |
1da177e4 | 1612 | out: |
3d48ae45 | 1613 | mutex_unlock(&mapping->i_mmap_mutex); |
1da177e4 LT |
1614 | return ret; |
1615 | } | |
1616 | ||
1617 | /** | |
1618 | * try_to_unmap - try to remove all page table mappings to a page | |
1619 | * @page: the page to get unmapped | |
14fa31b8 | 1620 | * @flags: action and flags |
1da177e4 LT |
1621 | * |
1622 | * Tries to remove all the page table entries which are mapping this | |
1623 | * page, used in the pageout path. Caller must hold the page lock. | |
1624 | * Return values are: | |
1625 | * | |
1626 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
1627 | * SWAP_AGAIN - we missed a mapping, try again later | |
1628 | * SWAP_FAIL - the page is unswappable | |
b291f000 | 1629 | * SWAP_MLOCK - page is mlocked. |
1da177e4 | 1630 | */ |
14fa31b8 | 1631 | int try_to_unmap(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1632 | { |
1633 | int ret; | |
1634 | ||
1da177e4 | 1635 | BUG_ON(!PageLocked(page)); |
91600e9e | 1636 | VM_BUG_ON(!PageHuge(page) && PageTransHuge(page)); |
1da177e4 | 1637 | |
5ad64688 HD |
1638 | if (unlikely(PageKsm(page))) |
1639 | ret = try_to_unmap_ksm(page, flags); | |
1640 | else if (PageAnon(page)) | |
14fa31b8 | 1641 | ret = try_to_unmap_anon(page, flags); |
1da177e4 | 1642 | else |
14fa31b8 | 1643 | ret = try_to_unmap_file(page, flags); |
b291f000 | 1644 | if (ret != SWAP_MLOCK && !page_mapped(page)) |
1da177e4 LT |
1645 | ret = SWAP_SUCCESS; |
1646 | return ret; | |
1647 | } | |
81b4082d | 1648 | |
b291f000 NP |
1649 | /** |
1650 | * try_to_munlock - try to munlock a page | |
1651 | * @page: the page to be munlocked | |
1652 | * | |
1653 | * Called from munlock code. Checks all of the VMAs mapping the page | |
1654 | * to make sure nobody else has this page mlocked. The page will be | |
1655 | * returned with PG_mlocked cleared if no other vmas have it mlocked. | |
1656 | * | |
1657 | * Return values are: | |
1658 | * | |
53f79acb | 1659 | * SWAP_AGAIN - no vma is holding page mlocked, or, |
b291f000 | 1660 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem |
5ad64688 | 1661 | * SWAP_FAIL - page cannot be located at present |
b291f000 NP |
1662 | * SWAP_MLOCK - page is now mlocked. |
1663 | */ | |
1664 | int try_to_munlock(struct page *page) | |
1665 | { | |
1666 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); | |
1667 | ||
5ad64688 HD |
1668 | if (unlikely(PageKsm(page))) |
1669 | return try_to_unmap_ksm(page, TTU_MUNLOCK); | |
1670 | else if (PageAnon(page)) | |
14fa31b8 | 1671 | return try_to_unmap_anon(page, TTU_MUNLOCK); |
b291f000 | 1672 | else |
14fa31b8 | 1673 | return try_to_unmap_file(page, TTU_MUNLOCK); |
b291f000 | 1674 | } |
e9995ef9 | 1675 | |
01d8b20d | 1676 | void __put_anon_vma(struct anon_vma *anon_vma) |
76545066 | 1677 | { |
01d8b20d | 1678 | struct anon_vma *root = anon_vma->root; |
76545066 | 1679 | |
65375ce7 | 1680 | anon_vma_free(anon_vma); |
01d8b20d PZ |
1681 | if (root != anon_vma && atomic_dec_and_test(&root->refcount)) |
1682 | anon_vma_free(root); | |
76545066 | 1683 | } |
76545066 | 1684 | |
e9995ef9 HD |
1685 | #ifdef CONFIG_MIGRATION |
1686 | /* | |
1687 | * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file(): | |
1688 | * Called by migrate.c to remove migration ptes, but might be used more later. | |
1689 | */ | |
1690 | static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, | |
1691 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1692 | { | |
1693 | struct anon_vma *anon_vma; | |
bf181b9f | 1694 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
5beb4930 | 1695 | struct anon_vma_chain *avc; |
e9995ef9 HD |
1696 | int ret = SWAP_AGAIN; |
1697 | ||
1698 | /* | |
4fc3f1d6 | 1699 | * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() |
e9995ef9 | 1700 | * because that depends on page_mapped(); but not all its usages |
3f6c8272 MG |
1701 | * are holding mmap_sem. Users without mmap_sem are required to |
1702 | * take a reference count to prevent the anon_vma disappearing | |
e9995ef9 HD |
1703 | */ |
1704 | anon_vma = page_anon_vma(page); | |
1705 | if (!anon_vma) | |
1706 | return ret; | |
4fc3f1d6 | 1707 | anon_vma_lock_read(anon_vma); |
bf181b9f | 1708 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
5beb4930 | 1709 | struct vm_area_struct *vma = avc->vma; |
e9995ef9 | 1710 | unsigned long address = vma_address(page, vma); |
e9995ef9 HD |
1711 | ret = rmap_one(page, vma, address, arg); |
1712 | if (ret != SWAP_AGAIN) | |
1713 | break; | |
1714 | } | |
4fc3f1d6 | 1715 | anon_vma_unlock_read(anon_vma); |
e9995ef9 HD |
1716 | return ret; |
1717 | } | |
1718 | ||
1719 | static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, | |
1720 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1721 | { | |
1722 | struct address_space *mapping = page->mapping; | |
1723 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1724 | struct vm_area_struct *vma; | |
e9995ef9 HD |
1725 | int ret = SWAP_AGAIN; |
1726 | ||
1727 | if (!mapping) | |
1728 | return ret; | |
3d48ae45 | 1729 | mutex_lock(&mapping->i_mmap_mutex); |
6b2dbba8 | 1730 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
e9995ef9 | 1731 | unsigned long address = vma_address(page, vma); |
e9995ef9 HD |
1732 | ret = rmap_one(page, vma, address, arg); |
1733 | if (ret != SWAP_AGAIN) | |
1734 | break; | |
1735 | } | |
1736 | /* | |
1737 | * No nonlinear handling: being always shared, nonlinear vmas | |
1738 | * never contain migration ptes. Decide what to do about this | |
1739 | * limitation to linear when we need rmap_walk() on nonlinear. | |
1740 | */ | |
3d48ae45 | 1741 | mutex_unlock(&mapping->i_mmap_mutex); |
e9995ef9 HD |
1742 | return ret; |
1743 | } | |
1744 | ||
1745 | int rmap_walk(struct page *page, int (*rmap_one)(struct page *, | |
1746 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1747 | { | |
1748 | VM_BUG_ON(!PageLocked(page)); | |
1749 | ||
1750 | if (unlikely(PageKsm(page))) | |
1751 | return rmap_walk_ksm(page, rmap_one, arg); | |
1752 | else if (PageAnon(page)) | |
1753 | return rmap_walk_anon(page, rmap_one, arg); | |
1754 | else | |
1755 | return rmap_walk_file(page, rmap_one, arg); | |
1756 | } | |
1757 | #endif /* CONFIG_MIGRATION */ | |
0fe6e20b | 1758 | |
e3390f67 | 1759 | #ifdef CONFIG_HUGETLB_PAGE |
0fe6e20b NH |
1760 | /* |
1761 | * The following three functions are for anonymous (private mapped) hugepages. | |
1762 | * Unlike common anonymous pages, anonymous hugepages have no accounting code | |
1763 | * and no lru code, because we handle hugepages differently from common pages. | |
1764 | */ | |
1765 | static void __hugepage_set_anon_rmap(struct page *page, | |
1766 | struct vm_area_struct *vma, unsigned long address, int exclusive) | |
1767 | { | |
1768 | struct anon_vma *anon_vma = vma->anon_vma; | |
433abed6 | 1769 | |
0fe6e20b | 1770 | BUG_ON(!anon_vma); |
433abed6 NH |
1771 | |
1772 | if (PageAnon(page)) | |
1773 | return; | |
1774 | if (!exclusive) | |
1775 | anon_vma = anon_vma->root; | |
1776 | ||
0fe6e20b NH |
1777 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1778 | page->mapping = (struct address_space *) anon_vma; | |
1779 | page->index = linear_page_index(vma, address); | |
1780 | } | |
1781 | ||
1782 | void hugepage_add_anon_rmap(struct page *page, | |
1783 | struct vm_area_struct *vma, unsigned long address) | |
1784 | { | |
1785 | struct anon_vma *anon_vma = vma->anon_vma; | |
1786 | int first; | |
a850ea30 NH |
1787 | |
1788 | BUG_ON(!PageLocked(page)); | |
0fe6e20b | 1789 | BUG_ON(!anon_vma); |
5dbe0af4 | 1790 | /* address might be in next vma when migration races vma_adjust */ |
0fe6e20b NH |
1791 | first = atomic_inc_and_test(&page->_mapcount); |
1792 | if (first) | |
1793 | __hugepage_set_anon_rmap(page, vma, address, 0); | |
1794 | } | |
1795 | ||
1796 | void hugepage_add_new_anon_rmap(struct page *page, | |
1797 | struct vm_area_struct *vma, unsigned long address) | |
1798 | { | |
1799 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
1800 | atomic_set(&page->_mapcount, 0); | |
1801 | __hugepage_set_anon_rmap(page, vma, address, 1); | |
1802 | } | |
e3390f67 | 1803 | #endif /* CONFIG_HUGETLB_PAGE */ |