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