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Source at commit b386be689295730688885552666ea40b2e639b14 created 11 years 11 months ago. By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters." | |
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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->mutex |
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->mutex,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 | |
60 | #include <asm/tlbflush.h> |
61 | |
62 | #include "internal.h" |
63 | |
64 | static struct kmem_cache *anon_vma_cachep; |
65 | static struct kmem_cache *anon_vma_chain_cachep; |
66 | |
67 | static inline struct anon_vma *anon_vma_alloc(void) |
68 | { |
69 | struct anon_vma *anon_vma; |
70 | |
71 | anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); |
72 | if (anon_vma) { |
73 | atomic_set(&anon_vma->refcount, 1); |
74 | /* |
75 | * Initialise the anon_vma root to point to itself. If called |
76 | * from fork, the root will be reset to the parents anon_vma. |
77 | */ |
78 | anon_vma->root = anon_vma; |
79 | } |
80 | |
81 | return anon_vma; |
82 | } |
83 | |
84 | static inline void anon_vma_free(struct anon_vma *anon_vma) |
85 | { |
86 | VM_BUG_ON(atomic_read(&anon_vma->refcount)); |
87 | |
88 | /* |
89 | * Synchronize against page_lock_anon_vma() such that |
90 | * we can safely hold the lock without the anon_vma getting |
91 | * freed. |
92 | * |
93 | * Relies on the full mb implied by the atomic_dec_and_test() from |
94 | * put_anon_vma() against the acquire barrier implied by |
95 | * mutex_trylock() from page_lock_anon_vma(). This orders: |
96 | * |
97 | * page_lock_anon_vma() VS put_anon_vma() |
98 | * mutex_trylock() atomic_dec_and_test() |
99 | * LOCK MB |
100 | * atomic_read() mutex_is_locked() |
101 | * |
102 | * LOCK should suffice since the actual taking of the lock must |
103 | * happen _before_ what follows. |
104 | */ |
105 | if (mutex_is_locked(&anon_vma->root->mutex)) { |
106 | anon_vma_lock(anon_vma); |
107 | anon_vma_unlock(anon_vma); |
108 | } |
109 | |
110 | kmem_cache_free(anon_vma_cachep, anon_vma); |
111 | } |
112 | |
113 | static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp) |
114 | { |
115 | return kmem_cache_alloc(anon_vma_chain_cachep, gfp); |
116 | } |
117 | |
118 | static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) |
119 | { |
120 | kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); |
121 | } |
122 | |
123 | /** |
124 | * anon_vma_prepare - attach an anon_vma to a memory region |
125 | * @vma: the memory region in question |
126 | * |
127 | * This makes sure the memory mapping described by 'vma' has |
128 | * an 'anon_vma' attached to it, so that we can associate the |
129 | * anonymous pages mapped into it with that anon_vma. |
130 | * |
131 | * The common case will be that we already have one, but if |
132 | * not we either need to find an adjacent mapping that we |
133 | * can re-use the anon_vma from (very common when the only |
134 | * reason for splitting a vma has been mprotect()), or we |
135 | * allocate a new one. |
136 | * |
137 | * Anon-vma allocations are very subtle, because we may have |
138 | * optimistically looked up an anon_vma in page_lock_anon_vma() |
139 | * and that may actually touch the spinlock even in the newly |
140 | * allocated vma (it depends on RCU to make sure that the |
141 | * anon_vma isn't actually destroyed). |
142 | * |
143 | * As a result, we need to do proper anon_vma locking even |
144 | * for the new allocation. At the same time, we do not want |
145 | * to do any locking for the common case of already having |
146 | * an anon_vma. |
147 | * |
148 | * This must be called with the mmap_sem held for reading. |
149 | */ |
150 | int anon_vma_prepare(struct vm_area_struct *vma) |
151 | { |
152 | struct anon_vma *anon_vma = vma->anon_vma; |
153 | struct anon_vma_chain *avc; |
154 | |
155 | might_sleep(); |
156 | if (unlikely(!anon_vma)) { |
157 | struct mm_struct *mm = vma->vm_mm; |
158 | struct anon_vma *allocated; |
159 | |
160 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
161 | if (!avc) |
162 | goto out_enomem; |
163 | |
164 | anon_vma = find_mergeable_anon_vma(vma); |
165 | allocated = NULL; |
166 | if (!anon_vma) { |
167 | anon_vma = anon_vma_alloc(); |
168 | if (unlikely(!anon_vma)) |
169 | goto out_enomem_free_avc; |
170 | allocated = anon_vma; |
171 | } |
172 | |
173 | anon_vma_lock(anon_vma); |
174 | /* page_table_lock to protect against threads */ |
175 | spin_lock(&mm->page_table_lock); |
176 | if (likely(!vma->anon_vma)) { |
177 | vma->anon_vma = anon_vma; |
178 | avc->anon_vma = anon_vma; |
179 | avc->vma = vma; |
180 | list_add(&avc->same_vma, &vma->anon_vma_chain); |
181 | list_add_tail(&avc->same_anon_vma, &anon_vma->head); |
182 | allocated = NULL; |
183 | avc = NULL; |
184 | } |
185 | spin_unlock(&mm->page_table_lock); |
186 | anon_vma_unlock(anon_vma); |
187 | |
188 | if (unlikely(allocated)) |
189 | put_anon_vma(allocated); |
190 | if (unlikely(avc)) |
191 | anon_vma_chain_free(avc); |
192 | } |
193 | return 0; |
194 | |
195 | out_enomem_free_avc: |
196 | anon_vma_chain_free(avc); |
197 | out_enomem: |
198 | return -ENOMEM; |
199 | } |
200 | |
201 | /* |
202 | * This is a useful helper function for locking the anon_vma root as |
203 | * we traverse the vma->anon_vma_chain, looping over anon_vma's that |
204 | * have the same vma. |
205 | * |
206 | * Such anon_vma's should have the same root, so you'd expect to see |
207 | * just a single mutex_lock for the whole traversal. |
208 | */ |
209 | static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma) |
210 | { |
211 | struct anon_vma *new_root = anon_vma->root; |
212 | if (new_root != root) { |
213 | if (WARN_ON_ONCE(root)) |
214 | mutex_unlock(&root->mutex); |
215 | root = new_root; |
216 | mutex_lock(&root->mutex); |
217 | } |
218 | return root; |
219 | } |
220 | |
221 | static inline void unlock_anon_vma_root(struct anon_vma *root) |
222 | { |
223 | if (root) |
224 | mutex_unlock(&root->mutex); |
225 | } |
226 | |
227 | static void anon_vma_chain_link(struct vm_area_struct *vma, |
228 | struct anon_vma_chain *avc, |
229 | struct anon_vma *anon_vma) |
230 | { |
231 | avc->vma = vma; |
232 | avc->anon_vma = anon_vma; |
233 | list_add(&avc->same_vma, &vma->anon_vma_chain); |
234 | |
235 | /* |
236 | * It's critical to add new vmas to the tail of the anon_vma, |
237 | * see comment in huge_memory.c:__split_huge_page(). |
238 | */ |
239 | list_add_tail(&avc->same_anon_vma, &anon_vma->head); |
240 | } |
241 | |
242 | /* |
243 | * Attach the anon_vmas from src to dst. |
244 | * Returns 0 on success, -ENOMEM on failure. |
245 | */ |
246 | int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) |
247 | { |
248 | struct anon_vma_chain *avc, *pavc; |
249 | struct anon_vma *root = NULL; |
250 | |
251 | list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { |
252 | struct anon_vma *anon_vma; |
253 | |
254 | avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN); |
255 | if (unlikely(!avc)) { |
256 | unlock_anon_vma_root(root); |
257 | root = NULL; |
258 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
259 | if (!avc) |
260 | goto enomem_failure; |
261 | } |
262 | anon_vma = pavc->anon_vma; |
263 | root = lock_anon_vma_root(root, anon_vma); |
264 | anon_vma_chain_link(dst, avc, anon_vma); |
265 | } |
266 | unlock_anon_vma_root(root); |
267 | return 0; |
268 | |
269 | enomem_failure: |
270 | unlink_anon_vmas(dst); |
271 | return -ENOMEM; |
272 | } |
273 | |
274 | /* |
275 | * Some rmap walk that needs to find all ptes/hugepmds without false |
276 | * negatives (like migrate and split_huge_page) running concurrent |
277 | * with operations that copy or move pagetables (like mremap() and |
278 | * fork()) to be safe. They depend on the anon_vma "same_anon_vma" |
279 | * list to be in a certain order: the dst_vma must be placed after the |
280 | * src_vma in the list. This is always guaranteed by fork() but |
281 | * mremap() needs to call this function to enforce it in case the |
282 | * dst_vma isn't newly allocated and chained with the anon_vma_clone() |
283 | * function but just an extension of a pre-existing vma through |
284 | * vma_merge. |
285 | * |
286 | * NOTE: the same_anon_vma list can still be changed by other |
287 | * processes while mremap runs because mremap doesn't hold the |
288 | * anon_vma mutex to prevent modifications to the list while it |
289 | * runs. All we need to enforce is that the relative order of this |
290 | * process vmas isn't changing (we don't care about other vmas |
291 | * order). Each vma corresponds to an anon_vma_chain structure so |
292 | * there's no risk that other processes calling anon_vma_moveto_tail() |
293 | * and changing the same_anon_vma list under mremap() will screw with |
294 | * the relative order of this process vmas in the list, because we |
295 | * they can't alter the order of any vma that belongs to this |
296 | * process. And there can't be another anon_vma_moveto_tail() running |
297 | * concurrently with mremap() coming from this process because we hold |
298 | * the mmap_sem for the whole mremap(). fork() ordering dependency |
299 | * also shouldn't be affected because fork() only cares that the |
300 | * parent vmas are placed in the list before the child vmas and |
301 | * anon_vma_moveto_tail() won't reorder vmas from either the fork() |
302 | * parent or child. |
303 | */ |
304 | void anon_vma_moveto_tail(struct vm_area_struct *dst) |
305 | { |
306 | struct anon_vma_chain *pavc; |
307 | struct anon_vma *root = NULL; |
308 | |
309 | list_for_each_entry_reverse(pavc, &dst->anon_vma_chain, same_vma) { |
310 | struct anon_vma *anon_vma = pavc->anon_vma; |
311 | VM_BUG_ON(pavc->vma != dst); |
312 | root = lock_anon_vma_root(root, anon_vma); |
313 | list_del(&pavc->same_anon_vma); |
314 | list_add_tail(&pavc->same_anon_vma, &anon_vma->head); |
315 | } |
316 | unlock_anon_vma_root(root); |
317 | } |
318 | |
319 | /* |
320 | * Attach vma to its own anon_vma, as well as to the anon_vmas that |
321 | * the corresponding VMA in the parent process is attached to. |
322 | * Returns 0 on success, non-zero on failure. |
323 | */ |
324 | int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) |
325 | { |
326 | struct anon_vma_chain *avc; |
327 | struct anon_vma *anon_vma; |
328 | |
329 | /* Don't bother if the parent process has no anon_vma here. */ |
330 | if (!pvma->anon_vma) |
331 | return 0; |
332 | |
333 | /* |
334 | * First, attach the new VMA to the parent VMA's anon_vmas, |
335 | * so rmap can find non-COWed pages in child processes. |
336 | */ |
337 | if (anon_vma_clone(vma, pvma)) |
338 | return -ENOMEM; |
339 | |
340 | /* Then add our own anon_vma. */ |
341 | anon_vma = anon_vma_alloc(); |
342 | if (!anon_vma) |
343 | goto out_error; |
344 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
345 | if (!avc) |
346 | goto out_error_free_anon_vma; |
347 | |
348 | /* |
349 | * The root anon_vma's spinlock is the lock actually used when we |
350 | * lock any of the anon_vmas in this anon_vma tree. |
351 | */ |
352 | anon_vma->root = pvma->anon_vma->root; |
353 | /* |
354 | * With refcounts, an anon_vma can stay around longer than the |
355 | * process it belongs to. The root anon_vma needs to be pinned until |
356 | * this anon_vma is freed, because the lock lives in the root. |
357 | */ |
358 | get_anon_vma(anon_vma->root); |
359 | /* Mark this anon_vma as the one where our new (COWed) pages go. */ |
360 | vma->anon_vma = anon_vma; |
361 | anon_vma_lock(anon_vma); |
362 | anon_vma_chain_link(vma, avc, anon_vma); |
363 | anon_vma_unlock(anon_vma); |
364 | |
365 | return 0; |
366 | |
367 | out_error_free_anon_vma: |
368 | put_anon_vma(anon_vma); |
369 | out_error: |
370 | unlink_anon_vmas(vma); |
371 | return -ENOMEM; |
372 | } |
373 | |
374 | void unlink_anon_vmas(struct vm_area_struct *vma) |
375 | { |
376 | struct anon_vma_chain *avc, *next; |
377 | struct anon_vma *root = NULL; |
378 | |
379 | /* |
380 | * Unlink each anon_vma chained to the VMA. This list is ordered |
381 | * from newest to oldest, ensuring the root anon_vma gets freed last. |
382 | */ |
383 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
384 | struct anon_vma *anon_vma = avc->anon_vma; |
385 | |
386 | root = lock_anon_vma_root(root, anon_vma); |
387 | list_del(&avc->same_anon_vma); |
388 | |
389 | /* |
390 | * Leave empty anon_vmas on the list - we'll need |
391 | * to free them outside the lock. |
392 | */ |
393 | if (list_empty(&anon_vma->head)) |
394 | continue; |
395 | |
396 | list_del(&avc->same_vma); |
397 | anon_vma_chain_free(avc); |
398 | } |
399 | unlock_anon_vma_root(root); |
400 | |
401 | /* |
402 | * Iterate the list once more, it now only contains empty and unlinked |
403 | * anon_vmas, destroy them. Could not do before due to __put_anon_vma() |
404 | * needing to acquire the anon_vma->root->mutex. |
405 | */ |
406 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
407 | struct anon_vma *anon_vma = avc->anon_vma; |
408 | |
409 | put_anon_vma(anon_vma); |
410 | |
411 | list_del(&avc->same_vma); |
412 | anon_vma_chain_free(avc); |
413 | } |
414 | } |
415 | |
416 | static void anon_vma_ctor(void *data) |
417 | { |
418 | struct anon_vma *anon_vma = data; |
419 | |
420 | mutex_init(&anon_vma->mutex); |
421 | atomic_set(&anon_vma->refcount, 0); |
422 | INIT_LIST_HEAD(&anon_vma->head); |
423 | } |
424 | |
425 | void __init anon_vma_init(void) |
426 | { |
427 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), |
428 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
429 | anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC); |
430 | } |
431 | |
432 | /* |
433 | * Getting a lock on a stable anon_vma from a page off the LRU is tricky! |
434 | * |
435 | * Since there is no serialization what so ever against page_remove_rmap() |
436 | * the best this function can do is return a locked anon_vma that might |
437 | * have been relevant to this page. |
438 | * |
439 | * The page might have been remapped to a different anon_vma or the anon_vma |
440 | * returned may already be freed (and even reused). |
441 | * |
442 | * In case it was remapped to a different anon_vma, the new anon_vma will be a |
443 | * child of the old anon_vma, and the anon_vma lifetime rules will therefore |
444 | * ensure that any anon_vma obtained from the page will still be valid for as |
445 | * long as we observe page_mapped() [ hence all those page_mapped() tests ]. |
446 | * |
447 | * All users of this function must be very careful when walking the anon_vma |
448 | * chain and verify that the page in question is indeed mapped in it |
449 | * [ something equivalent to page_mapped_in_vma() ]. |
450 | * |
451 | * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap() |
452 | * that the anon_vma pointer from page->mapping is valid if there is a |
453 | * mapcount, we can dereference the anon_vma after observing those. |
454 | */ |
455 | struct anon_vma *page_get_anon_vma(struct page *page) |
456 | { |
457 | struct anon_vma *anon_vma = NULL; |
458 | unsigned long anon_mapping; |
459 | |
460 | rcu_read_lock(); |
461 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
462 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
463 | goto out; |
464 | if (!page_mapped(page)) |
465 | goto out; |
466 | |
467 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
468 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
469 | anon_vma = NULL; |
470 | goto out; |
471 | } |
472 | |
473 | /* |
474 | * If this page is still mapped, then its anon_vma cannot have been |
475 | * freed. But if it has been unmapped, we have no security against the |
476 | * anon_vma structure being freed and reused (for another anon_vma: |
477 | * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero() |
478 | * above cannot corrupt). |
479 | */ |
480 | if (!page_mapped(page)) { |
481 | put_anon_vma(anon_vma); |
482 | anon_vma = NULL; |
483 | } |
484 | out: |
485 | rcu_read_unlock(); |
486 | |
487 | return anon_vma; |
488 | } |
489 | |
490 | /* |
491 | * Similar to page_get_anon_vma() except it locks the anon_vma. |
492 | * |
493 | * Its a little more complex as it tries to keep the fast path to a single |
494 | * atomic op -- the trylock. If we fail the trylock, we fall back to getting a |
495 | * reference like with page_get_anon_vma() and then block on the mutex. |
496 | */ |
497 | struct anon_vma *page_lock_anon_vma(struct page *page) |
498 | { |
499 | struct anon_vma *anon_vma = NULL; |
500 | struct anon_vma *root_anon_vma; |
501 | unsigned long anon_mapping; |
502 | |
503 | rcu_read_lock(); |
504 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
505 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
506 | goto out; |
507 | if (!page_mapped(page)) |
508 | goto out; |
509 | |
510 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
511 | root_anon_vma = ACCESS_ONCE(anon_vma->root); |
512 | if (mutex_trylock(&root_anon_vma->mutex)) { |
513 | /* |
514 | * If the page is still mapped, then this anon_vma is still |
515 | * its anon_vma, and holding the mutex ensures that it will |
516 | * not go away, see anon_vma_free(). |
517 | */ |
518 | if (!page_mapped(page)) { |
519 | mutex_unlock(&root_anon_vma->mutex); |
520 | anon_vma = NULL; |
521 | } |
522 | goto out; |
523 | } |
524 | |
525 | /* trylock failed, we got to sleep */ |
526 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
527 | anon_vma = NULL; |
528 | goto out; |
529 | } |
530 | |
531 | if (!page_mapped(page)) { |
532 | put_anon_vma(anon_vma); |
533 | anon_vma = NULL; |
534 | goto out; |
535 | } |
536 | |
537 | /* we pinned the anon_vma, its safe to sleep */ |
538 | rcu_read_unlock(); |
539 | anon_vma_lock(anon_vma); |
540 | |
541 | if (atomic_dec_and_test(&anon_vma->refcount)) { |
542 | /* |
543 | * Oops, we held the last refcount, release the lock |
544 | * and bail -- can't simply use put_anon_vma() because |
545 | * we'll deadlock on the anon_vma_lock() recursion. |
546 | */ |
547 | anon_vma_unlock(anon_vma); |
548 | __put_anon_vma(anon_vma); |
549 | anon_vma = NULL; |
550 | } |
551 | |
552 | return anon_vma; |
553 | |
554 | out: |
555 | rcu_read_unlock(); |
556 | return anon_vma; |
557 | } |
558 | |
559 | void page_unlock_anon_vma(struct anon_vma *anon_vma) |
560 | { |
561 | anon_vma_unlock(anon_vma); |
562 | } |
563 | |
564 | /* |
565 | * At what user virtual address is page expected in @vma? |
566 | * Returns virtual address or -EFAULT if page's index/offset is not |
567 | * within the range mapped the @vma. |
568 | */ |
569 | inline unsigned long |
570 | vma_address(struct page *page, struct vm_area_struct *vma) |
571 | { |
572 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
573 | unsigned long address; |
574 | |
575 | if (unlikely(is_vm_hugetlb_page(vma))) |
576 | pgoff = page->index << huge_page_order(page_hstate(page)); |
577 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
578 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { |
579 | /* page should be within @vma mapping range */ |
580 | return -EFAULT; |
581 | } |
582 | return address; |
583 | } |
584 | |
585 | /* |
586 | * At what user virtual address is page expected in vma? |
587 | * Caller should check the page is actually part of the vma. |
588 | */ |
589 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) |
590 | { |
591 | if (PageAnon(page)) { |
592 | struct anon_vma *page__anon_vma = page_anon_vma(page); |
593 | /* |
594 | * Note: swapoff's unuse_vma() is more efficient with this |
595 | * check, and needs it to match anon_vma when KSM is active. |
596 | */ |
597 | if (!vma->anon_vma || !page__anon_vma || |
598 | vma->anon_vma->root != page__anon_vma->root) |
599 | return -EFAULT; |
600 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { |
601 | if (!vma->vm_file || |
602 | vma->vm_file->f_mapping != page->mapping) |
603 | return -EFAULT; |
604 | } else |
605 | return -EFAULT; |
606 | return vma_address(page, vma); |
607 | } |
608 | |
609 | /* |
610 | * Check that @page is mapped at @address into @mm. |
611 | * |
612 | * If @sync is false, page_check_address may perform a racy check to avoid |
613 | * the page table lock when the pte is not present (helpful when reclaiming |
614 | * highly shared pages). |
615 | * |
616 | * On success returns with pte mapped and locked. |
617 | */ |
618 | pte_t *__page_check_address(struct page *page, struct mm_struct *mm, |
619 | unsigned long address, spinlock_t **ptlp, int sync) |
620 | { |
621 | pgd_t *pgd; |
622 | pud_t *pud; |
623 | pmd_t *pmd; |
624 | pte_t *pte; |
625 | spinlock_t *ptl; |
626 | |
627 | if (unlikely(PageHuge(page))) { |
628 | pte = huge_pte_offset(mm, address); |
629 | ptl = &mm->page_table_lock; |
630 | goto check; |
631 | } |
632 | |
633 | pgd = pgd_offset(mm, address); |
634 | if (!pgd_present(*pgd)) |
635 | return NULL; |
636 | |
637 | pud = pud_offset(pgd, address); |
638 | if (!pud_present(*pud)) |
639 | return NULL; |
640 | |
641 | pmd = pmd_offset(pud, address); |
642 | if (!pmd_present(*pmd)) |
643 | return NULL; |
644 | if (pmd_trans_huge(*pmd)) |
645 | return NULL; |
646 | |
647 | pte = pte_offset_map(pmd, address); |
648 | /* Make a quick check before getting the lock */ |
649 | if (!sync && !pte_present(*pte)) { |
650 | pte_unmap(pte); |
651 | return NULL; |
652 | } |
653 | |
654 | ptl = pte_lockptr(mm, pmd); |
655 | check: |
656 | spin_lock(ptl); |
657 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { |
658 | *ptlp = ptl; |
659 | return pte; |
660 | } |
661 | pte_unmap_unlock(pte, ptl); |
662 | return NULL; |
663 | } |
664 | |
665 | /** |
666 | * page_mapped_in_vma - check whether a page is really mapped in a VMA |
667 | * @page: the page to test |
668 | * @vma: the VMA to test |
669 | * |
670 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 |
671 | * if the page is not mapped into the page tables of this VMA. Only |
672 | * valid for normal file or anonymous VMAs. |
673 | */ |
674 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) |
675 | { |
676 | unsigned long address; |
677 | pte_t *pte; |
678 | spinlock_t *ptl; |
679 | |
680 | address = vma_address(page, vma); |
681 | if (address == -EFAULT) /* out of vma range */ |
682 | return 0; |
683 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); |
684 | if (!pte) /* the page is not in this mm */ |
685 | return 0; |
686 | pte_unmap_unlock(pte, ptl); |
687 | |
688 | return 1; |
689 | } |
690 | |
691 | /* |
692 | * Subfunctions of page_referenced: page_referenced_one called |
693 | * repeatedly from either page_referenced_anon or page_referenced_file. |
694 | */ |
695 | int page_referenced_one(struct page *page, struct vm_area_struct *vma, |
696 | unsigned long address, unsigned int *mapcount, |
697 | unsigned long *vm_flags) |
698 | { |
699 | struct mm_struct *mm = vma->vm_mm; |
700 | int referenced = 0; |
701 | |
702 | if (unlikely(PageTransHuge(page))) { |
703 | pmd_t *pmd; |
704 | |
705 | spin_lock(&mm->page_table_lock); |
706 | /* |
707 | * rmap might return false positives; we must filter |
708 | * these out using page_check_address_pmd(). |
709 | */ |
710 | pmd = page_check_address_pmd(page, mm, address, |
711 | PAGE_CHECK_ADDRESS_PMD_FLAG); |
712 | if (!pmd) { |
713 | spin_unlock(&mm->page_table_lock); |
714 | goto out; |
715 | } |
716 | |
717 | if (vma->vm_flags & VM_LOCKED) { |
718 | spin_unlock(&mm->page_table_lock); |
719 | *mapcount = 0; /* break early from loop */ |
720 | *vm_flags |= VM_LOCKED; |
721 | goto out; |
722 | } |
723 | |
724 | /* go ahead even if the pmd is pmd_trans_splitting() */ |
725 | if (pmdp_clear_flush_young_notify(vma, address, pmd)) |
726 | referenced++; |
727 | spin_unlock(&mm->page_table_lock); |
728 | } else { |
729 | pte_t *pte; |
730 | spinlock_t *ptl; |
731 | |
732 | /* |
733 | * rmap might return false positives; we must filter |
734 | * these out using page_check_address(). |
735 | */ |
736 | pte = page_check_address(page, mm, address, &ptl, 0); |
737 | if (!pte) |
738 | goto out; |
739 | |
740 | if (vma->vm_flags & VM_LOCKED) { |
741 | pte_unmap_unlock(pte, ptl); |
742 | *mapcount = 0; /* break early from loop */ |
743 | *vm_flags |= VM_LOCKED; |
744 | goto out; |
745 | } |
746 | |
747 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
748 | /* |
749 | * Don't treat a reference through a sequentially read |
750 | * mapping as such. If the page has been used in |
751 | * another mapping, we will catch it; if this other |
752 | * mapping is already gone, the unmap path will have |
753 | * set PG_referenced or activated the page. |
754 | */ |
755 | if (likely(!VM_SequentialReadHint(vma))) |
756 | referenced++; |
757 | } |
758 | pte_unmap_unlock(pte, ptl); |
759 | } |
760 | |
761 | /* Pretend the page is referenced if the task has the |
762 | swap token and is in the middle of a page fault. */ |
763 | if (mm != current->mm && has_swap_token(mm) && |
764 | rwsem_is_locked(&mm->mmap_sem)) |
765 | referenced++; |
766 | |
767 | (*mapcount)--; |
768 | |
769 | if (referenced) |
770 | *vm_flags |= vma->vm_flags; |
771 | out: |
772 | return referenced; |
773 | } |
774 | |
775 | static int page_referenced_anon(struct page *page, |
776 | struct mem_cgroup *memcg, |
777 | unsigned long *vm_flags) |
778 | { |
779 | unsigned int mapcount; |
780 | struct anon_vma *anon_vma; |
781 | struct anon_vma_chain *avc; |
782 | int referenced = 0; |
783 | |
784 | anon_vma = page_lock_anon_vma(page); |
785 | if (!anon_vma) |
786 | return referenced; |
787 | |
788 | mapcount = page_mapcount(page); |
789 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
790 | struct vm_area_struct *vma = avc->vma; |
791 | unsigned long address = vma_address(page, vma); |
792 | if (address == -EFAULT) |
793 | continue; |
794 | /* |
795 | * If we are reclaiming on behalf of a cgroup, skip |
796 | * counting on behalf of references from different |
797 | * cgroups |
798 | */ |
799 | if (memcg && !mm_match_cgroup(vma->vm_mm, memcg)) |
800 | continue; |
801 | referenced += page_referenced_one(page, vma, address, |
802 | &mapcount, vm_flags); |
803 | if (!mapcount) |
804 | break; |
805 | } |
806 | |
807 | page_unlock_anon_vma(anon_vma); |
808 | return referenced; |
809 | } |
810 | |
811 | /** |
812 | * page_referenced_file - referenced check for object-based rmap |
813 | * @page: the page we're checking references on. |
814 | * @memcg: target memory control group |
815 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
816 | * |
817 | * For an object-based mapped page, find all the places it is mapped and |
818 | * check/clear the referenced flag. This is done by following the page->mapping |
819 | * pointer, then walking the chain of vmas it holds. It returns the number |
820 | * of references it found. |
821 | * |
822 | * This function is only called from page_referenced for object-based pages. |
823 | */ |
824 | static int page_referenced_file(struct page *page, |
825 | struct mem_cgroup *memcg, |
826 | unsigned long *vm_flags) |
827 | { |
828 | unsigned int mapcount; |
829 | struct address_space *mapping = page->mapping; |
830 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
831 | struct vm_area_struct *vma; |
832 | struct prio_tree_iter iter; |
833 | int referenced = 0; |
834 | |
835 | /* |
836 | * The caller's checks on page->mapping and !PageAnon have made |
837 | * sure that this is a file page: the check for page->mapping |
838 | * excludes the case just before it gets set on an anon page. |
839 | */ |
840 | BUG_ON(PageAnon(page)); |
841 | |
842 | /* |
843 | * The page lock not only makes sure that page->mapping cannot |
844 | * suddenly be NULLified by truncation, it makes sure that the |
845 | * structure at mapping cannot be freed and reused yet, |
846 | * so we can safely take mapping->i_mmap_mutex. |
847 | */ |
848 | BUG_ON(!PageLocked(page)); |
849 | |
850 | mutex_lock(&mapping->i_mmap_mutex); |
851 | |
852 | /* |
853 | * i_mmap_mutex does not stabilize mapcount at all, but mapcount |
854 | * is more likely to be accurate if we note it after spinning. |
855 | */ |
856 | mapcount = page_mapcount(page); |
857 | |
858 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
859 | unsigned long address = vma_address(page, vma); |
860 | if (address == -EFAULT) |
861 | continue; |
862 | /* |
863 | * If we are reclaiming on behalf of a cgroup, skip |
864 | * counting on behalf of references from different |
865 | * cgroups |
866 | */ |
867 | if (memcg && !mm_match_cgroup(vma->vm_mm, memcg)) |
868 | continue; |
869 | referenced += page_referenced_one(page, vma, address, |
870 | &mapcount, vm_flags); |
871 | if (!mapcount) |
872 | break; |
873 | } |
874 | |
875 | mutex_unlock(&mapping->i_mmap_mutex); |
876 | return referenced; |
877 | } |
878 | |
879 | /** |
880 | * page_referenced - test if the page was referenced |
881 | * @page: the page to test |
882 | * @is_locked: caller holds lock on the page |
883 | * @memcg: target memory cgroup |
884 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
885 | * |
886 | * Quick test_and_clear_referenced for all mappings to a page, |
887 | * returns the number of ptes which referenced the page. |
888 | */ |
889 | int page_referenced(struct page *page, |
890 | int is_locked, |
891 | struct mem_cgroup *memcg, |
892 | unsigned long *vm_flags) |
893 | { |
894 | int referenced = 0; |
895 | int we_locked = 0; |
896 | |
897 | *vm_flags = 0; |
898 | if (page_mapped(page) && page_rmapping(page)) { |
899 | if (!is_locked && (!PageAnon(page) || PageKsm(page))) { |
900 | we_locked = trylock_page(page); |
901 | if (!we_locked) { |
902 | referenced++; |
903 | goto out; |
904 | } |
905 | } |
906 | if (unlikely(PageKsm(page))) |
907 | referenced += page_referenced_ksm(page, memcg, |
908 | vm_flags); |
909 | else if (PageAnon(page)) |
910 | referenced += page_referenced_anon(page, memcg, |
911 | vm_flags); |
912 | else if (page->mapping) |
913 | referenced += page_referenced_file(page, memcg, |
914 | vm_flags); |
915 | if (we_locked) |
916 | unlock_page(page); |
917 | |
918 | if (page_test_and_clear_young(page_to_pfn(page))) |
919 | referenced++; |
920 | } |
921 | out: |
922 | return referenced; |
923 | } |
924 | |
925 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, |
926 | unsigned long address) |
927 | { |
928 | struct mm_struct *mm = vma->vm_mm; |
929 | pte_t *pte; |
930 | spinlock_t *ptl; |
931 | int ret = 0; |
932 | |
933 | pte = page_check_address(page, mm, address, &ptl, 1); |
934 | if (!pte) |
935 | goto out; |
936 | |
937 | if (pte_dirty(*pte) || pte_write(*pte)) { |
938 | pte_t entry; |
939 | |
940 | flush_cache_page(vma, address, pte_pfn(*pte)); |
941 | entry = ptep_clear_flush_notify(vma, address, pte); |
942 | entry = pte_wrprotect(entry); |
943 | entry = pte_mkclean(entry); |
944 | set_pte_at(mm, address, pte, entry); |
945 | ret = 1; |
946 | } |
947 | |
948 | pte_unmap_unlock(pte, ptl); |
949 | out: |
950 | return ret; |
951 | } |
952 | |
953 | static int page_mkclean_file(struct address_space *mapping, struct page *page) |
954 | { |
955 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
956 | struct vm_area_struct *vma; |
957 | struct prio_tree_iter iter; |
958 | int ret = 0; |
959 | |
960 | BUG_ON(PageAnon(page)); |
961 | |
962 | mutex_lock(&mapping->i_mmap_mutex); |
963 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
964 | if (vma->vm_flags & VM_SHARED) { |
965 | unsigned long address = vma_address(page, vma); |
966 | if (address == -EFAULT) |
967 | continue; |
968 | ret += page_mkclean_one(page, vma, address); |
969 | } |
970 | } |
971 | mutex_unlock(&mapping->i_mmap_mutex); |
972 | return ret; |
973 | } |
974 | |
975 | int page_mkclean(struct page *page) |
976 | { |
977 | int ret = 0; |
978 | |
979 | BUG_ON(!PageLocked(page)); |
980 | |
981 | if (page_mapped(page)) { |
982 | struct address_space *mapping = page_mapping(page); |
983 | if (mapping) { |
984 | ret = page_mkclean_file(mapping, page); |
985 | if (page_test_and_clear_dirty(page_to_pfn(page), 1)) |
986 | ret = 1; |
987 | } |
988 | } |
989 | |
990 | return ret; |
991 | } |
992 | EXPORT_SYMBOL_GPL(page_mkclean); |
993 | |
994 | /** |
995 | * page_move_anon_rmap - move a page to our anon_vma |
996 | * @page: the page to move to our anon_vma |
997 | * @vma: the vma the page belongs to |
998 | * @address: the user virtual address mapped |
999 | * |
1000 | * When a page belongs exclusively to one process after a COW event, |
1001 | * that page can be moved into the anon_vma that belongs to just that |
1002 | * process, so the rmap code will not search the parent or sibling |
1003 | * processes. |
1004 | */ |
1005 | void page_move_anon_rmap(struct page *page, |
1006 | struct vm_area_struct *vma, unsigned long address) |
1007 | { |
1008 | struct anon_vma *anon_vma = vma->anon_vma; |
1009 | |
1010 | VM_BUG_ON(!PageLocked(page)); |
1011 | VM_BUG_ON(!anon_vma); |
1012 | VM_BUG_ON(page->index != linear_page_index(vma, address)); |
1013 | |
1014 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1015 | page->mapping = (struct address_space *) anon_vma; |
1016 | } |
1017 | |
1018 | /** |
1019 | * __page_set_anon_rmap - set up new anonymous rmap |
1020 | * @page: Page to add to rmap |
1021 | * @vma: VM area to add page to. |
1022 | * @address: User virtual address of the mapping |
1023 | * @exclusive: the page is exclusively owned by the current process |
1024 | */ |
1025 | static void __page_set_anon_rmap(struct page *page, |
1026 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
1027 | { |
1028 | struct anon_vma *anon_vma = vma->anon_vma; |
1029 | |
1030 | BUG_ON(!anon_vma); |
1031 | |
1032 | if (PageAnon(page)) |
1033 | return; |
1034 | |
1035 | /* |
1036 | * If the page isn't exclusively mapped into this vma, |
1037 | * we must use the _oldest_ possible anon_vma for the |
1038 | * page mapping! |
1039 | */ |
1040 | if (!exclusive) |
1041 | anon_vma = anon_vma->root; |
1042 | |
1043 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1044 | page->mapping = (struct address_space *) anon_vma; |
1045 | page->index = linear_page_index(vma, address); |
1046 | } |
1047 | |
1048 | /** |
1049 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
1050 | * @page: the page to add the mapping to |
1051 | * @vma: the vm area in which the mapping is added |
1052 | * @address: the user virtual address mapped |
1053 | */ |
1054 | static void __page_check_anon_rmap(struct page *page, |
1055 | struct vm_area_struct *vma, unsigned long address) |
1056 | { |
1057 | #ifdef CONFIG_DEBUG_VM |
1058 | /* |
1059 | * The page's anon-rmap details (mapping and index) are guaranteed to |
1060 | * be set up correctly at this point. |
1061 | * |
1062 | * We have exclusion against page_add_anon_rmap because the caller |
1063 | * always holds the page locked, except if called from page_dup_rmap, |
1064 | * in which case the page is already known to be setup. |
1065 | * |
1066 | * We have exclusion against page_add_new_anon_rmap because those pages |
1067 | * are initially only visible via the pagetables, and the pte is locked |
1068 | * over the call to page_add_new_anon_rmap. |
1069 | */ |
1070 | BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); |
1071 | BUG_ON(page->index != linear_page_index(vma, address)); |
1072 | #endif |
1073 | } |
1074 | |
1075 | /** |
1076 | * page_add_anon_rmap - add pte mapping to an anonymous page |
1077 | * @page: the page to add the mapping to |
1078 | * @vma: the vm area in which the mapping is added |
1079 | * @address: the user virtual address mapped |
1080 | * |
1081 | * The caller needs to hold the pte lock, and the page must be locked in |
1082 | * the anon_vma case: to serialize mapping,index checking after setting, |
1083 | * and to ensure that PageAnon is not being upgraded racily to PageKsm |
1084 | * (but PageKsm is never downgraded to PageAnon). |
1085 | */ |
1086 | void page_add_anon_rmap(struct page *page, |
1087 | struct vm_area_struct *vma, unsigned long address) |
1088 | { |
1089 | do_page_add_anon_rmap(page, vma, address, 0); |
1090 | } |
1091 | |
1092 | /* |
1093 | * Special version of the above for do_swap_page, which often runs |
1094 | * into pages that are exclusively owned by the current process. |
1095 | * Everybody else should continue to use page_add_anon_rmap above. |
1096 | */ |
1097 | void do_page_add_anon_rmap(struct page *page, |
1098 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
1099 | { |
1100 | int first = atomic_inc_and_test(&page->_mapcount); |
1101 | if (first) { |
1102 | if (!PageTransHuge(page)) |
1103 | __inc_zone_page_state(page, NR_ANON_PAGES); |
1104 | else |
1105 | __inc_zone_page_state(page, |
1106 | NR_ANON_TRANSPARENT_HUGEPAGES); |
1107 | } |
1108 | if (unlikely(PageKsm(page))) |
1109 | return; |
1110 | |
1111 | VM_BUG_ON(!PageLocked(page)); |
1112 | /* address might be in next vma when migration races vma_adjust */ |
1113 | if (first) |
1114 | __page_set_anon_rmap(page, vma, address, exclusive); |
1115 | else |
1116 | __page_check_anon_rmap(page, vma, address); |
1117 | } |
1118 | |
1119 | /** |
1120 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
1121 | * @page: the page to add the mapping to |
1122 | * @vma: the vm area in which the mapping is added |
1123 | * @address: the user virtual address mapped |
1124 | * |
1125 | * Same as page_add_anon_rmap but must only be called on *new* pages. |
1126 | * This means the inc-and-test can be bypassed. |
1127 | * Page does not have to be locked. |
1128 | */ |
1129 | void page_add_new_anon_rmap(struct page *page, |
1130 | struct vm_area_struct *vma, unsigned long address) |
1131 | { |
1132 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
1133 | SetPageSwapBacked(page); |
1134 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ |
1135 | if (!PageTransHuge(page)) |
1136 | __inc_zone_page_state(page, NR_ANON_PAGES); |
1137 | else |
1138 | __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1139 | __page_set_anon_rmap(page, vma, address, 1); |
1140 | if (page_evictable(page, vma)) |
1141 | lru_cache_add_lru(page, LRU_ACTIVE_ANON); |
1142 | else |
1143 | add_page_to_unevictable_list(page); |
1144 | } |
1145 | |
1146 | /** |
1147 | * page_add_file_rmap - add pte mapping to a file page |
1148 | * @page: the page to add the mapping to |
1149 | * |
1150 | * The caller needs to hold the pte lock. |
1151 | */ |
1152 | void page_add_file_rmap(struct page *page) |
1153 | { |
1154 | if (atomic_inc_and_test(&page->_mapcount)) { |
1155 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
1156 | mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED); |
1157 | } |
1158 | } |
1159 | |
1160 | /** |
1161 | * page_remove_rmap - take down pte mapping from a page |
1162 | * @page: page to remove mapping from |
1163 | * |
1164 | * The caller needs to hold the pte lock. |
1165 | */ |
1166 | void page_remove_rmap(struct page *page) |
1167 | { |
1168 | /* page still mapped by someone else? */ |
1169 | if (!atomic_add_negative(-1, &page->_mapcount)) |
1170 | return; |
1171 | |
1172 | /* |
1173 | * Now that the last pte has gone, s390 must transfer dirty |
1174 | * flag from storage key to struct page. We can usually skip |
1175 | * this if the page is anon, so about to be freed; but perhaps |
1176 | * not if it's in swapcache - there might be another pte slot |
1177 | * containing the swap entry, but page not yet written to swap. |
1178 | */ |
1179 | if ((!PageAnon(page) || PageSwapCache(page)) && |
1180 | page_test_and_clear_dirty(page_to_pfn(page), 1)) |
1181 | set_page_dirty(page); |
1182 | /* |
1183 | * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED |
1184 | * and not charged by memcg for now. |
1185 | */ |
1186 | if (unlikely(PageHuge(page))) |
1187 | return; |
1188 | if (PageAnon(page)) { |
1189 | mem_cgroup_uncharge_page(page); |
1190 | if (!PageTransHuge(page)) |
1191 | __dec_zone_page_state(page, NR_ANON_PAGES); |
1192 | else |
1193 | __dec_zone_page_state(page, |
1194 | NR_ANON_TRANSPARENT_HUGEPAGES); |
1195 | } else { |
1196 | __dec_zone_page_state(page, NR_FILE_MAPPED); |
1197 | mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED); |
1198 | } |
1199 | /* |
1200 | * It would be tidy to reset the PageAnon mapping here, |
1201 | * but that might overwrite a racing page_add_anon_rmap |
1202 | * which increments mapcount after us but sets mapping |
1203 | * before us: so leave the reset to free_hot_cold_page, |
1204 | * and remember that it's only reliable while mapped. |
1205 | * Leaving it set also helps swapoff to reinstate ptes |
1206 | * faster for those pages still in swapcache. |
1207 | */ |
1208 | } |
1209 | |
1210 | /* |
1211 | * Subfunctions of try_to_unmap: try_to_unmap_one called |
1212 | * repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file. |
1213 | */ |
1214 | int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
1215 | unsigned long address, enum ttu_flags flags) |
1216 | { |
1217 | struct mm_struct *mm = vma->vm_mm; |
1218 | pte_t *pte; |
1219 | pte_t pteval; |
1220 | spinlock_t *ptl; |
1221 | int ret = SWAP_AGAIN; |
1222 | |
1223 | pte = page_check_address(page, mm, address, &ptl, 0); |
1224 | if (!pte) |
1225 | goto out; |
1226 | |
1227 | /* |
1228 | * If the page is mlock()d, we cannot swap it out. |
1229 | * If it's recently referenced (perhaps page_referenced |
1230 | * skipped over this mm) then we should reactivate it. |
1231 | */ |
1232 | if (!(flags & TTU_IGNORE_MLOCK)) { |
1233 | if (vma->vm_flags & VM_LOCKED) |
1234 | goto out_mlock; |
1235 | |
1236 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
1237 | goto out_unmap; |
1238 | } |
1239 | if (!(flags & TTU_IGNORE_ACCESS)) { |
1240 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
1241 | ret = SWAP_FAIL; |
1242 | goto out_unmap; |
1243 | } |
1244 | } |
1245 | |
1246 | /* Nuke the page table entry. */ |
1247 | flush_cache_page(vma, address, page_to_pfn(page)); |
1248 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1249 | |
1250 | /* Move the dirty bit to the physical page now the pte is gone. */ |
1251 | if (pte_dirty(pteval)) |
1252 | set_page_dirty(page); |
1253 | |
1254 | /* Update high watermark before we lower rss */ |
1255 | update_hiwater_rss(mm); |
1256 | |
1257 | if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
1258 | if (PageAnon(page)) |
1259 | dec_mm_counter(mm, MM_ANONPAGES); |
1260 | else |
1261 | dec_mm_counter(mm, MM_FILEPAGES); |
1262 | set_pte_at(mm, address, pte, |
1263 | swp_entry_to_pte(make_hwpoison_entry(page))); |
1264 | } else if (PageAnon(page)) { |
1265 | swp_entry_t entry = { .val = page_private(page) }; |
1266 | |
1267 | if (PageSwapCache(page)) { |
1268 | /* |
1269 | * Store the swap location in the pte. |
1270 | * See handle_pte_fault() ... |
1271 | */ |
1272 | if (swap_duplicate(entry) < 0) { |
1273 | set_pte_at(mm, address, pte, pteval); |
1274 | ret = SWAP_FAIL; |
1275 | goto out_unmap; |
1276 | } |
1277 | if (list_empty(&mm->mmlist)) { |
1278 | spin_lock(&mmlist_lock); |
1279 | if (list_empty(&mm->mmlist)) |
1280 | list_add(&mm->mmlist, &init_mm.mmlist); |
1281 | spin_unlock(&mmlist_lock); |
1282 | } |
1283 | dec_mm_counter(mm, MM_ANONPAGES); |
1284 | inc_mm_counter(mm, MM_SWAPENTS); |
1285 | } else if (PAGE_MIGRATION) { |
1286 | /* |
1287 | * Store the pfn of the page in a special migration |
1288 | * pte. do_swap_page() will wait until the migration |
1289 | * pte is removed and then restart fault handling. |
1290 | */ |
1291 | BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION); |
1292 | entry = make_migration_entry(page, pte_write(pteval)); |
1293 | } |
1294 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
1295 | BUG_ON(pte_file(*pte)); |
1296 | } else if (PAGE_MIGRATION && (TTU_ACTION(flags) == TTU_MIGRATION)) { |
1297 | /* Establish migration entry for a file page */ |
1298 | swp_entry_t entry; |
1299 | entry = make_migration_entry(page, pte_write(pteval)); |
1300 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
1301 | } else |
1302 | dec_mm_counter(mm, MM_FILEPAGES); |
1303 | |
1304 | page_remove_rmap(page); |
1305 | page_cache_release(page); |
1306 | |
1307 | out_unmap: |
1308 | pte_unmap_unlock(pte, ptl); |
1309 | out: |
1310 | return ret; |
1311 | |
1312 | out_mlock: |
1313 | pte_unmap_unlock(pte, ptl); |
1314 | |
1315 | |
1316 | /* |
1317 | * We need mmap_sem locking, Otherwise VM_LOCKED check makes |
1318 | * unstable result and race. Plus, We can't wait here because |
1319 | * we now hold anon_vma->mutex or mapping->i_mmap_mutex. |
1320 | * if trylock failed, the page remain in evictable lru and later |
1321 | * vmscan could retry to move the page to unevictable lru if the |
1322 | * page is actually mlocked. |
1323 | */ |
1324 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
1325 | if (vma->vm_flags & VM_LOCKED) { |
1326 | mlock_vma_page(page); |
1327 | ret = SWAP_MLOCK; |
1328 | } |
1329 | up_read(&vma->vm_mm->mmap_sem); |
1330 | } |
1331 | return ret; |
1332 | } |
1333 | |
1334 | /* |
1335 | * objrmap doesn't work for nonlinear VMAs because the assumption that |
1336 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. |
1337 | * Consequently, given a particular page and its ->index, we cannot locate the |
1338 | * ptes which are mapping that page without an exhaustive linear search. |
1339 | * |
1340 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which |
1341 | * maps the file to which the target page belongs. The ->vm_private_data field |
1342 | * holds the current cursor into that scan. Successive searches will circulate |
1343 | * around the vma's virtual address space. |
1344 | * |
1345 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, |
1346 | * more scanning pressure is placed against them as well. Eventually pages |
1347 | * will become fully unmapped and are eligible for eviction. |
1348 | * |
1349 | * For very sparsely populated VMAs this is a little inefficient - chances are |
1350 | * there there won't be many ptes located within the scan cluster. In this case |
1351 | * maybe we could scan further - to the end of the pte page, perhaps. |
1352 | * |
1353 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can |
1354 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, |
1355 | * rather than unmapping them. If we encounter the "check_page" that vmscan is |
1356 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. |
1357 | */ |
1358 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) |
1359 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) |
1360 | |
1361 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
1362 | struct vm_area_struct *vma, struct page *check_page) |
1363 | { |
1364 | struct mm_struct *mm = vma->vm_mm; |
1365 | pgd_t *pgd; |
1366 | pud_t *pud; |
1367 | pmd_t *pmd; |
1368 | pte_t *pte; |
1369 | pte_t pteval; |
1370 | spinlock_t *ptl; |
1371 | struct page *page; |
1372 | unsigned long address; |
1373 | unsigned long end; |
1374 | int ret = SWAP_AGAIN; |
1375 | int locked_vma = 0; |
1376 | |
1377 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
1378 | end = address + CLUSTER_SIZE; |
1379 | if (address < vma->vm_start) |
1380 | address = vma->vm_start; |
1381 | if (end > vma->vm_end) |
1382 | end = vma->vm_end; |
1383 | |
1384 | pgd = pgd_offset(mm, address); |
1385 | if (!pgd_present(*pgd)) |
1386 | return ret; |
1387 | |
1388 | pud = pud_offset(pgd, address); |
1389 | if (!pud_present(*pud)) |
1390 | return ret; |
1391 | |
1392 | pmd = pmd_offset(pud, address); |
1393 | if (!pmd_present(*pmd)) |
1394 | return ret; |
1395 | |
1396 | /* |
1397 | * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, |
1398 | * keep the sem while scanning the cluster for mlocking pages. |
1399 | */ |
1400 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
1401 | locked_vma = (vma->vm_flags & VM_LOCKED); |
1402 | if (!locked_vma) |
1403 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ |
1404 | } |
1405 | |
1406 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
1407 | |
1408 | /* Update high watermark before we lower rss */ |
1409 | update_hiwater_rss(mm); |
1410 | |
1411 | for (; address < end; pte++, address += PAGE_SIZE) { |
1412 | if (!pte_present(*pte)) |
1413 | continue; |
1414 | page = vm_normal_page(vma, address, *pte); |
1415 | BUG_ON(!page || PageAnon(page)); |
1416 | |
1417 | if (locked_vma) { |
1418 | mlock_vma_page(page); /* no-op if already mlocked */ |
1419 | if (page == check_page) |
1420 | ret = SWAP_MLOCK; |
1421 | continue; /* don't unmap */ |
1422 | } |
1423 | |
1424 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1425 | continue; |
1426 | |
1427 | /* Nuke the page table entry. */ |
1428 | flush_cache_page(vma, address, pte_pfn(*pte)); |
1429 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1430 | |
1431 | /* If nonlinear, store the file page offset in the pte. */ |
1432 | if (page->index != linear_page_index(vma, address)) |
1433 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); |
1434 | |
1435 | /* Move the dirty bit to the physical page now the pte is gone. */ |
1436 | if (pte_dirty(pteval)) |
1437 | set_page_dirty(page); |
1438 | |
1439 | page_remove_rmap(page); |
1440 | page_cache_release(page); |
1441 | dec_mm_counter(mm, MM_FILEPAGES); |
1442 | (*mapcount)--; |
1443 | } |
1444 | pte_unmap_unlock(pte - 1, ptl); |
1445 | if (locked_vma) |
1446 | up_read(&vma->vm_mm->mmap_sem); |
1447 | return ret; |
1448 | } |
1449 | |
1450 | bool is_vma_temporary_stack(struct vm_area_struct *vma) |
1451 | { |
1452 | int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); |
1453 | |
1454 | if (!maybe_stack) |
1455 | return false; |
1456 | |
1457 | if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == |
1458 | VM_STACK_INCOMPLETE_SETUP) |
1459 | return true; |
1460 | |
1461 | return false; |
1462 | } |
1463 | |
1464 | /** |
1465 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based |
1466 | * rmap method |
1467 | * @page: the page to unmap/unlock |
1468 | * @flags: action and flags |
1469 | * |
1470 | * Find all the mappings of a page using the mapping pointer and the vma chains |
1471 | * contained in the anon_vma struct it points to. |
1472 | * |
1473 | * This function is only called from try_to_unmap/try_to_munlock for |
1474 | * anonymous pages. |
1475 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma |
1476 | * where the page was found will be held for write. So, we won't recheck |
1477 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be |
1478 | * 'LOCKED. |
1479 | */ |
1480 | static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) |
1481 | { |
1482 | struct anon_vma *anon_vma; |
1483 | struct anon_vma_chain *avc; |
1484 | int ret = SWAP_AGAIN; |
1485 | |
1486 | anon_vma = page_lock_anon_vma(page); |
1487 | if (!anon_vma) |
1488 | return ret; |
1489 | |
1490 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1491 | struct vm_area_struct *vma = avc->vma; |
1492 | unsigned long address; |
1493 | |
1494 | /* |
1495 | * During exec, a temporary VMA is setup and later moved. |
1496 | * The VMA is moved under the anon_vma lock but not the |
1497 | * page tables leading to a race where migration cannot |
1498 | * find the migration ptes. Rather than increasing the |
1499 | * locking requirements of exec(), migration skips |
1500 | * temporary VMAs until after exec() completes. |
1501 | */ |
1502 | if (PAGE_MIGRATION && (flags & TTU_MIGRATION) && |
1503 | is_vma_temporary_stack(vma)) |
1504 | continue; |
1505 | |
1506 | address = vma_address(page, vma); |
1507 | if (address == -EFAULT) |
1508 | continue; |
1509 | ret = try_to_unmap_one(page, vma, address, flags); |
1510 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1511 | break; |
1512 | } |
1513 | |
1514 | page_unlock_anon_vma(anon_vma); |
1515 | return ret; |
1516 | } |
1517 | |
1518 | /** |
1519 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
1520 | * @page: the page to unmap/unlock |
1521 | * @flags: action and flags |
1522 | * |
1523 | * Find all the mappings of a page using the mapping pointer and the vma chains |
1524 | * contained in the address_space struct it points to. |
1525 | * |
1526 | * This function is only called from try_to_unmap/try_to_munlock for |
1527 | * object-based pages. |
1528 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma |
1529 | * where the page was found will be held for write. So, we won't recheck |
1530 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be |
1531 | * 'LOCKED. |
1532 | */ |
1533 | static int try_to_unmap_file(struct page *page, enum ttu_flags flags) |
1534 | { |
1535 | struct address_space *mapping = page->mapping; |
1536 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
1537 | struct vm_area_struct *vma; |
1538 | struct prio_tree_iter iter; |
1539 | int ret = SWAP_AGAIN; |
1540 | unsigned long cursor; |
1541 | unsigned long max_nl_cursor = 0; |
1542 | unsigned long max_nl_size = 0; |
1543 | unsigned int mapcount; |
1544 | |
1545 | mutex_lock(&mapping->i_mmap_mutex); |
1546 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
1547 | unsigned long address = vma_address(page, vma); |
1548 | if (address == -EFAULT) |
1549 | continue; |
1550 | ret = try_to_unmap_one(page, vma, address, flags); |
1551 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1552 | goto out; |
1553 | } |
1554 | |
1555 | if (list_empty(&mapping->i_mmap_nonlinear)) |
1556 | goto out; |
1557 | |
1558 | /* |
1559 | * We don't bother to try to find the munlocked page in nonlinears. |
1560 | * It's costly. Instead, later, page reclaim logic may call |
1561 | * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily. |
1562 | */ |
1563 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
1564 | goto out; |
1565 | |
1566 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
1567 | shared.vm_set.list) { |
1568 | cursor = (unsigned long) vma->vm_private_data; |
1569 | if (cursor > max_nl_cursor) |
1570 | max_nl_cursor = cursor; |
1571 | cursor = vma->vm_end - vma->vm_start; |
1572 | if (cursor > max_nl_size) |
1573 | max_nl_size = cursor; |
1574 | } |
1575 | |
1576 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1577 | ret = SWAP_FAIL; |
1578 | goto out; |
1579 | } |
1580 | |
1581 | /* |
1582 | * We don't try to search for this page in the nonlinear vmas, |
1583 | * and page_referenced wouldn't have found it anyway. Instead |
1584 | * just walk the nonlinear vmas trying to age and unmap some. |
1585 | * The mapcount of the page we came in with is irrelevant, |
1586 | * but even so use it as a guide to how hard we should try? |
1587 | */ |
1588 | mapcount = page_mapcount(page); |
1589 | if (!mapcount) |
1590 | goto out; |
1591 | cond_resched(); |
1592 | |
1593 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; |
1594 | if (max_nl_cursor == 0) |
1595 | max_nl_cursor = CLUSTER_SIZE; |
1596 | |
1597 | do { |
1598 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
1599 | shared.vm_set.list) { |
1600 | cursor = (unsigned long) vma->vm_private_data; |
1601 | while ( cursor < max_nl_cursor && |
1602 | cursor < vma->vm_end - vma->vm_start) { |
1603 | if (try_to_unmap_cluster(cursor, &mapcount, |
1604 | vma, page) == SWAP_MLOCK) |
1605 | ret = SWAP_MLOCK; |
1606 | cursor += CLUSTER_SIZE; |
1607 | vma->vm_private_data = (void *) cursor; |
1608 | if ((int)mapcount <= 0) |
1609 | goto out; |
1610 | } |
1611 | vma->vm_private_data = (void *) max_nl_cursor; |
1612 | } |
1613 | cond_resched(); |
1614 | max_nl_cursor += CLUSTER_SIZE; |
1615 | } while (max_nl_cursor <= max_nl_size); |
1616 | |
1617 | /* |
1618 | * Don't loop forever (perhaps all the remaining pages are |
1619 | * in locked vmas). Reset cursor on all unreserved nonlinear |
1620 | * vmas, now forgetting on which ones it had fallen behind. |
1621 | */ |
1622 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
1623 | vma->vm_private_data = NULL; |
1624 | out: |
1625 | mutex_unlock(&mapping->i_mmap_mutex); |
1626 | return ret; |
1627 | } |
1628 | |
1629 | /** |
1630 | * try_to_unmap - try to remove all page table mappings to a page |
1631 | * @page: the page to get unmapped |
1632 | * @flags: action and flags |
1633 | * |
1634 | * Tries to remove all the page table entries which are mapping this |
1635 | * page, used in the pageout path. Caller must hold the page lock. |
1636 | * Return values are: |
1637 | * |
1638 | * SWAP_SUCCESS - we succeeded in removing all mappings |
1639 | * SWAP_AGAIN - we missed a mapping, try again later |
1640 | * SWAP_FAIL - the page is unswappable |
1641 | * SWAP_MLOCK - page is mlocked. |
1642 | */ |
1643 | int try_to_unmap(struct page *page, enum ttu_flags flags) |
1644 | { |
1645 | int ret; |
1646 | |
1647 | BUG_ON(!PageLocked(page)); |
1648 | VM_BUG_ON(!PageHuge(page) && PageTransHuge(page)); |
1649 | |
1650 | if (unlikely(PageKsm(page))) |
1651 | ret = try_to_unmap_ksm(page, flags); |
1652 | else if (PageAnon(page)) |
1653 | ret = try_to_unmap_anon(page, flags); |
1654 | else |
1655 | ret = try_to_unmap_file(page, flags); |
1656 | if (ret != SWAP_MLOCK && !page_mapped(page)) |
1657 | ret = SWAP_SUCCESS; |
1658 | return ret; |
1659 | } |
1660 | |
1661 | /** |
1662 | * try_to_munlock - try to munlock a page |
1663 | * @page: the page to be munlocked |
1664 | * |
1665 | * Called from munlock code. Checks all of the VMAs mapping the page |
1666 | * to make sure nobody else has this page mlocked. The page will be |
1667 | * returned with PG_mlocked cleared if no other vmas have it mlocked. |
1668 | * |
1669 | * Return values are: |
1670 | * |
1671 | * SWAP_AGAIN - no vma is holding page mlocked, or, |
1672 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem |
1673 | * SWAP_FAIL - page cannot be located at present |
1674 | * SWAP_MLOCK - page is now mlocked. |
1675 | */ |
1676 | int try_to_munlock(struct page *page) |
1677 | { |
1678 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); |
1679 | |
1680 | if (unlikely(PageKsm(page))) |
1681 | return try_to_unmap_ksm(page, TTU_MUNLOCK); |
1682 | else if (PageAnon(page)) |
1683 | return try_to_unmap_anon(page, TTU_MUNLOCK); |
1684 | else |
1685 | return try_to_unmap_file(page, TTU_MUNLOCK); |
1686 | } |
1687 | |
1688 | void __put_anon_vma(struct anon_vma *anon_vma) |
1689 | { |
1690 | struct anon_vma *root = anon_vma->root; |
1691 | |
1692 | if (root != anon_vma && atomic_dec_and_test(&root->refcount)) |
1693 | anon_vma_free(root); |
1694 | |
1695 | anon_vma_free(anon_vma); |
1696 | } |
1697 | |
1698 | #ifdef CONFIG_MIGRATION |
1699 | /* |
1700 | * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file(): |
1701 | * Called by migrate.c to remove migration ptes, but might be used more later. |
1702 | */ |
1703 | static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, |
1704 | struct vm_area_struct *, unsigned long, void *), void *arg) |
1705 | { |
1706 | struct anon_vma *anon_vma; |
1707 | struct anon_vma_chain *avc; |
1708 | int ret = SWAP_AGAIN; |
1709 | |
1710 | /* |
1711 | * Note: remove_migration_ptes() cannot use page_lock_anon_vma() |
1712 | * because that depends on page_mapped(); but not all its usages |
1713 | * are holding mmap_sem. Users without mmap_sem are required to |
1714 | * take a reference count to prevent the anon_vma disappearing |
1715 | */ |
1716 | anon_vma = page_anon_vma(page); |
1717 | if (!anon_vma) |
1718 | return ret; |
1719 | anon_vma_lock(anon_vma); |
1720 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1721 | struct vm_area_struct *vma = avc->vma; |
1722 | unsigned long address = vma_address(page, vma); |
1723 | if (address == -EFAULT) |
1724 | continue; |
1725 | ret = rmap_one(page, vma, address, arg); |
1726 | if (ret != SWAP_AGAIN) |
1727 | break; |
1728 | } |
1729 | anon_vma_unlock(anon_vma); |
1730 | return ret; |
1731 | } |
1732 | |
1733 | static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, |
1734 | struct vm_area_struct *, unsigned long, void *), void *arg) |
1735 | { |
1736 | struct address_space *mapping = page->mapping; |
1737 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
1738 | struct vm_area_struct *vma; |
1739 | struct prio_tree_iter iter; |
1740 | int ret = SWAP_AGAIN; |
1741 | |
1742 | if (!mapping) |
1743 | return ret; |
1744 | mutex_lock(&mapping->i_mmap_mutex); |
1745 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
1746 | unsigned long address = vma_address(page, vma); |
1747 | if (address == -EFAULT) |
1748 | continue; |
1749 | ret = rmap_one(page, vma, address, arg); |
1750 | if (ret != SWAP_AGAIN) |
1751 | break; |
1752 | } |
1753 | /* |
1754 | * No nonlinear handling: being always shared, nonlinear vmas |
1755 | * never contain migration ptes. Decide what to do about this |
1756 | * limitation to linear when we need rmap_walk() on nonlinear. |
1757 | */ |
1758 | mutex_unlock(&mapping->i_mmap_mutex); |
1759 | return ret; |
1760 | } |
1761 | |
1762 | int rmap_walk(struct page *page, int (*rmap_one)(struct page *, |
1763 | struct vm_area_struct *, unsigned long, void *), void *arg) |
1764 | { |
1765 | VM_BUG_ON(!PageLocked(page)); |
1766 | |
1767 | if (unlikely(PageKsm(page))) |
1768 | return rmap_walk_ksm(page, rmap_one, arg); |
1769 | else if (PageAnon(page)) |
1770 | return rmap_walk_anon(page, rmap_one, arg); |
1771 | else |
1772 | return rmap_walk_file(page, rmap_one, arg); |
1773 | } |
1774 | #endif /* CONFIG_MIGRATION */ |
1775 | |
1776 | #ifdef CONFIG_HUGETLB_PAGE |
1777 | /* |
1778 | * The following three functions are for anonymous (private mapped) hugepages. |
1779 | * Unlike common anonymous pages, anonymous hugepages have no accounting code |
1780 | * and no lru code, because we handle hugepages differently from common pages. |
1781 | */ |
1782 | static void __hugepage_set_anon_rmap(struct page *page, |
1783 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
1784 | { |
1785 | struct anon_vma *anon_vma = vma->anon_vma; |
1786 | |
1787 | BUG_ON(!anon_vma); |
1788 | |
1789 | if (PageAnon(page)) |
1790 | return; |
1791 | if (!exclusive) |
1792 | anon_vma = anon_vma->root; |
1793 | |
1794 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1795 | page->mapping = (struct address_space *) anon_vma; |
1796 | page->index = linear_page_index(vma, address); |
1797 | } |
1798 | |
1799 | void hugepage_add_anon_rmap(struct page *page, |
1800 | struct vm_area_struct *vma, unsigned long address) |
1801 | { |
1802 | struct anon_vma *anon_vma = vma->anon_vma; |
1803 | int first; |
1804 | |
1805 | BUG_ON(!PageLocked(page)); |
1806 | BUG_ON(!anon_vma); |
1807 | /* address might be in next vma when migration races vma_adjust */ |
1808 | first = atomic_inc_and_test(&page->_mapcount); |
1809 | if (first) |
1810 | __hugepage_set_anon_rmap(page, vma, address, 0); |
1811 | } |
1812 | |
1813 | void hugepage_add_new_anon_rmap(struct page *page, |
1814 | struct vm_area_struct *vma, unsigned long address) |
1815 | { |
1816 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
1817 | atomic_set(&page->_mapcount, 0); |
1818 | __hugepage_set_anon_rmap(page, vma, address, 1); |
1819 | } |
1820 | #endif /* CONFIG_HUGETLB_PAGE */ |
1821 |
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