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