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1 | /* |
2 | * mm/rmap.c - physical to virtual reverse mappings |
3 | * |
4 | * Copyright 2001, Rik van Riel <riel@conectiva.com.br> |
5 | * Released under the General Public License (GPL). |
6 | * |
7 | * Simple, low overhead reverse mapping scheme. |
8 | * Please try to keep this thing as modular as possible. |
9 | * |
10 | * Provides methods for unmapping each kind of mapped page: |
11 | * the anon methods track anonymous pages, and |
12 | * the file methods track pages belonging to an inode. |
13 | * |
14 | * Original design by Rik van Riel <riel@conectiva.com.br> 2001 |
15 | * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 |
16 | * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 |
17 | * Contributions by Hugh Dickins 2003, 2004 |
18 | */ |
19 | |
20 | /* |
21 | * Lock ordering in mm: |
22 | * |
23 | * inode->i_mutex (while writing or truncating, not reading or faulting) |
24 | * mm->mmap_sem |
25 | * page->flags PG_locked (lock_page) |
26 | * mapping->i_mmap_mutex |
27 | * anon_vma->rwsem |
28 | * mm->page_table_lock or pte_lock |
29 | * zone->lru_lock (in mark_page_accessed, isolate_lru_page) |
30 | * swap_lock (in swap_duplicate, swap_info_get) |
31 | * mmlist_lock (in mmput, drain_mmlist and others) |
32 | * mapping->private_lock (in __set_page_dirty_buffers) |
33 | * inode->i_lock (in set_page_dirty's __mark_inode_dirty) |
34 | * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) |
35 | * sb_lock (within inode_lock in fs/fs-writeback.c) |
36 | * mapping->tree_lock (widely used, in set_page_dirty, |
37 | * in arch-dependent flush_dcache_mmap_lock, |
38 | * within bdi.wb->list_lock in __sync_single_inode) |
39 | * |
40 | * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon) |
41 | * ->tasklist_lock |
42 | * pte map lock |
43 | */ |
44 | |
45 | #include <linux/mm.h> |
46 | #include <linux/pagemap.h> |
47 | #include <linux/swap.h> |
48 | #include <linux/swapops.h> |
49 | #include <linux/slab.h> |
50 | #include <linux/init.h> |
51 | #include <linux/ksm.h> |
52 | #include <linux/rmap.h> |
53 | #include <linux/rcupdate.h> |
54 | #include <linux/export.h> |
55 | #include <linux/memcontrol.h> |
56 | #include <linux/mmu_notifier.h> |
57 | #include <linux/migrate.h> |
58 | #include <linux/hugetlb.h> |
59 | #include <linux/backing-dev.h> |
60 | |
61 | #include <asm/tlbflush.h> |
62 | |
63 | #include "internal.h" |
64 | |
65 | static struct kmem_cache *anon_vma_cachep; |
66 | static struct kmem_cache *anon_vma_chain_cachep; |
67 | |
68 | static inline struct anon_vma *anon_vma_alloc(void) |
69 | { |
70 | struct anon_vma *anon_vma; |
71 | |
72 | anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); |
73 | if (anon_vma) { |
74 | atomic_set(&anon_vma->refcount, 1); |
75 | /* |
76 | * Initialise the anon_vma root to point to itself. If called |
77 | * from fork, the root will be reset to the parents anon_vma. |
78 | */ |
79 | anon_vma->root = anon_vma; |
80 | } |
81 | |
82 | return anon_vma; |
83 | } |
84 | |
85 | static inline void anon_vma_free(struct anon_vma *anon_vma) |
86 | { |
87 | VM_BUG_ON(atomic_read(&anon_vma->refcount)); |
88 | |
89 | /* |
90 | * Synchronize against page_lock_anon_vma_read() such that |
91 | * we can safely hold the lock without the anon_vma getting |
92 | * freed. |
93 | * |
94 | * Relies on the full mb implied by the atomic_dec_and_test() from |
95 | * put_anon_vma() against the acquire barrier implied by |
96 | * down_read_trylock() from page_lock_anon_vma_read(). This orders: |
97 | * |
98 | * page_lock_anon_vma_read() VS put_anon_vma() |
99 | * down_read_trylock() atomic_dec_and_test() |
100 | * LOCK MB |
101 | * atomic_read() rwsem_is_locked() |
102 | * |
103 | * LOCK should suffice since the actual taking of the lock must |
104 | * happen _before_ what follows. |
105 | */ |
106 | might_sleep(); |
107 | if (rwsem_is_locked(&anon_vma->root->rwsem)) { |
108 | anon_vma_lock_write(anon_vma); |
109 | anon_vma_unlock_write(anon_vma); |
110 | } |
111 | |
112 | kmem_cache_free(anon_vma_cachep, anon_vma); |
113 | } |
114 | |
115 | static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp) |
116 | { |
117 | return kmem_cache_alloc(anon_vma_chain_cachep, gfp); |
118 | } |
119 | |
120 | static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) |
121 | { |
122 | kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); |
123 | } |
124 | |
125 | static void anon_vma_chain_link(struct vm_area_struct *vma, |
126 | struct anon_vma_chain *avc, |
127 | struct anon_vma *anon_vma) |
128 | { |
129 | avc->vma = vma; |
130 | avc->anon_vma = anon_vma; |
131 | list_add(&avc->same_vma, &vma->anon_vma_chain); |
132 | anon_vma_interval_tree_insert(avc, &anon_vma->rb_root); |
133 | } |
134 | |
135 | /** |
136 | * anon_vma_prepare - attach an anon_vma to a memory region |
137 | * @vma: the memory region in question |
138 | * |
139 | * This makes sure the memory mapping described by 'vma' has |
140 | * an 'anon_vma' attached to it, so that we can associate the |
141 | * anonymous pages mapped into it with that anon_vma. |
142 | * |
143 | * The common case will be that we already have one, but if |
144 | * not we either need to find an adjacent mapping that we |
145 | * can re-use the anon_vma from (very common when the only |
146 | * reason for splitting a vma has been mprotect()), or we |
147 | * allocate a new one. |
148 | * |
149 | * Anon-vma allocations are very subtle, because we may have |
150 | * optimistically looked up an anon_vma in page_lock_anon_vma_read() |
151 | * and that may actually touch the spinlock even in the newly |
152 | * allocated vma (it depends on RCU to make sure that the |
153 | * anon_vma isn't actually destroyed). |
154 | * |
155 | * As a result, we need to do proper anon_vma locking even |
156 | * for the new allocation. At the same time, we do not want |
157 | * to do any locking for the common case of already having |
158 | * an anon_vma. |
159 | * |
160 | * This must be called with the mmap_sem held for reading. |
161 | */ |
162 | int anon_vma_prepare(struct vm_area_struct *vma) |
163 | { |
164 | struct anon_vma *anon_vma = vma->anon_vma; |
165 | struct anon_vma_chain *avc; |
166 | |
167 | might_sleep(); |
168 | if (unlikely(!anon_vma)) { |
169 | struct mm_struct *mm = vma->vm_mm; |
170 | struct anon_vma *allocated; |
171 | |
172 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
173 | if (!avc) |
174 | goto out_enomem; |
175 | |
176 | anon_vma = find_mergeable_anon_vma(vma); |
177 | allocated = NULL; |
178 | if (!anon_vma) { |
179 | anon_vma = anon_vma_alloc(); |
180 | if (unlikely(!anon_vma)) |
181 | goto out_enomem_free_avc; |
182 | allocated = anon_vma; |
183 | } |
184 | |
185 | anon_vma_lock_write(anon_vma); |
186 | /* page_table_lock to protect against threads */ |
187 | spin_lock(&mm->page_table_lock); |
188 | if (likely(!vma->anon_vma)) { |
189 | vma->anon_vma = anon_vma; |
190 | anon_vma_chain_link(vma, avc, anon_vma); |
191 | allocated = NULL; |
192 | avc = NULL; |
193 | } |
194 | spin_unlock(&mm->page_table_lock); |
195 | anon_vma_unlock_write(anon_vma); |
196 | |
197 | if (unlikely(allocated)) |
198 | put_anon_vma(allocated); |
199 | if (unlikely(avc)) |
200 | anon_vma_chain_free(avc); |
201 | } |
202 | return 0; |
203 | |
204 | out_enomem_free_avc: |
205 | anon_vma_chain_free(avc); |
206 | out_enomem: |
207 | return -ENOMEM; |
208 | } |
209 | |
210 | /* |
211 | * This is a useful helper function for locking the anon_vma root as |
212 | * we traverse the vma->anon_vma_chain, looping over anon_vma's that |
213 | * have the same vma. |
214 | * |
215 | * Such anon_vma's should have the same root, so you'd expect to see |
216 | * just a single mutex_lock for the whole traversal. |
217 | */ |
218 | static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma) |
219 | { |
220 | struct anon_vma *new_root = anon_vma->root; |
221 | if (new_root != root) { |
222 | if (WARN_ON_ONCE(root)) |
223 | up_write(&root->rwsem); |
224 | root = new_root; |
225 | down_write(&root->rwsem); |
226 | } |
227 | return root; |
228 | } |
229 | |
230 | static inline void unlock_anon_vma_root(struct anon_vma *root) |
231 | { |
232 | if (root) |
233 | up_write(&root->rwsem); |
234 | } |
235 | |
236 | /* |
237 | * Attach the anon_vmas from src to dst. |
238 | * Returns 0 on success, -ENOMEM on failure. |
239 | */ |
240 | int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) |
241 | { |
242 | struct anon_vma_chain *avc, *pavc; |
243 | struct anon_vma *root = NULL; |
244 | |
245 | list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { |
246 | struct anon_vma *anon_vma; |
247 | |
248 | avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN); |
249 | if (unlikely(!avc)) { |
250 | unlock_anon_vma_root(root); |
251 | root = NULL; |
252 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
253 | if (!avc) |
254 | goto enomem_failure; |
255 | } |
256 | anon_vma = pavc->anon_vma; |
257 | root = lock_anon_vma_root(root, anon_vma); |
258 | anon_vma_chain_link(dst, avc, anon_vma); |
259 | } |
260 | unlock_anon_vma_root(root); |
261 | return 0; |
262 | |
263 | enomem_failure: |
264 | unlink_anon_vmas(dst); |
265 | return -ENOMEM; |
266 | } |
267 | |
268 | /* |
269 | * Attach vma to its own anon_vma, as well as to the anon_vmas that |
270 | * the corresponding VMA in the parent process is attached to. |
271 | * Returns 0 on success, non-zero on failure. |
272 | */ |
273 | int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) |
274 | { |
275 | struct anon_vma_chain *avc; |
276 | struct anon_vma *anon_vma; |
277 | int error; |
278 | |
279 | /* Don't bother if the parent process has no anon_vma here. */ |
280 | if (!pvma->anon_vma) |
281 | return 0; |
282 | |
283 | /* |
284 | * First, attach the new VMA to the parent VMA's anon_vmas, |
285 | * so rmap can find non-COWed pages in child processes. |
286 | */ |
287 | error = anon_vma_clone(vma, pvma); |
288 | if (error) |
289 | return error; |
290 | |
291 | /* Then add our own anon_vma. */ |
292 | anon_vma = anon_vma_alloc(); |
293 | if (!anon_vma) |
294 | goto out_error; |
295 | avc = anon_vma_chain_alloc(GFP_KERNEL); |
296 | if (!avc) |
297 | goto out_error_free_anon_vma; |
298 | |
299 | /* |
300 | * The root anon_vma's spinlock is the lock actually used when we |
301 | * lock any of the anon_vmas in this anon_vma tree. |
302 | */ |
303 | anon_vma->root = pvma->anon_vma->root; |
304 | /* |
305 | * With refcounts, an anon_vma can stay around longer than the |
306 | * process it belongs to. The root anon_vma needs to be pinned until |
307 | * this anon_vma is freed, because the lock lives in the root. |
308 | */ |
309 | get_anon_vma(anon_vma->root); |
310 | /* Mark this anon_vma as the one where our new (COWed) pages go. */ |
311 | vma->anon_vma = anon_vma; |
312 | anon_vma_lock_write(anon_vma); |
313 | anon_vma_chain_link(vma, avc, anon_vma); |
314 | anon_vma_unlock_write(anon_vma); |
315 | |
316 | return 0; |
317 | |
318 | out_error_free_anon_vma: |
319 | put_anon_vma(anon_vma); |
320 | out_error: |
321 | unlink_anon_vmas(vma); |
322 | return -ENOMEM; |
323 | } |
324 | |
325 | void unlink_anon_vmas(struct vm_area_struct *vma) |
326 | { |
327 | struct anon_vma_chain *avc, *next; |
328 | struct anon_vma *root = NULL; |
329 | |
330 | /* |
331 | * Unlink each anon_vma chained to the VMA. This list is ordered |
332 | * from newest to oldest, ensuring the root anon_vma gets freed last. |
333 | */ |
334 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
335 | struct anon_vma *anon_vma = avc->anon_vma; |
336 | |
337 | root = lock_anon_vma_root(root, anon_vma); |
338 | anon_vma_interval_tree_remove(avc, &anon_vma->rb_root); |
339 | |
340 | /* |
341 | * Leave empty anon_vmas on the list - we'll need |
342 | * to free them outside the lock. |
343 | */ |
344 | if (RB_EMPTY_ROOT(&anon_vma->rb_root)) |
345 | continue; |
346 | |
347 | list_del(&avc->same_vma); |
348 | anon_vma_chain_free(avc); |
349 | } |
350 | unlock_anon_vma_root(root); |
351 | |
352 | /* |
353 | * Iterate the list once more, it now only contains empty and unlinked |
354 | * anon_vmas, destroy them. Could not do before due to __put_anon_vma() |
355 | * needing to write-acquire the anon_vma->root->rwsem. |
356 | */ |
357 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
358 | struct anon_vma *anon_vma = avc->anon_vma; |
359 | |
360 | put_anon_vma(anon_vma); |
361 | |
362 | list_del(&avc->same_vma); |
363 | anon_vma_chain_free(avc); |
364 | } |
365 | } |
366 | |
367 | static void anon_vma_ctor(void *data) |
368 | { |
369 | struct anon_vma *anon_vma = data; |
370 | |
371 | init_rwsem(&anon_vma->rwsem); |
372 | atomic_set(&anon_vma->refcount, 0); |
373 | anon_vma->rb_root = RB_ROOT; |
374 | } |
375 | |
376 | void __init anon_vma_init(void) |
377 | { |
378 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), |
379 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
380 | anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC); |
381 | } |
382 | |
383 | /* |
384 | * Getting a lock on a stable anon_vma from a page off the LRU is tricky! |
385 | * |
386 | * Since there is no serialization what so ever against page_remove_rmap() |
387 | * the best this function can do is return a locked anon_vma that might |
388 | * have been relevant to this page. |
389 | * |
390 | * The page might have been remapped to a different anon_vma or the anon_vma |
391 | * returned may already be freed (and even reused). |
392 | * |
393 | * In case it was remapped to a different anon_vma, the new anon_vma will be a |
394 | * child of the old anon_vma, and the anon_vma lifetime rules will therefore |
395 | * ensure that any anon_vma obtained from the page will still be valid for as |
396 | * long as we observe page_mapped() [ hence all those page_mapped() tests ]. |
397 | * |
398 | * All users of this function must be very careful when walking the anon_vma |
399 | * chain and verify that the page in question is indeed mapped in it |
400 | * [ something equivalent to page_mapped_in_vma() ]. |
401 | * |
402 | * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap() |
403 | * that the anon_vma pointer from page->mapping is valid if there is a |
404 | * mapcount, we can dereference the anon_vma after observing those. |
405 | */ |
406 | struct anon_vma *page_get_anon_vma(struct page *page) |
407 | { |
408 | struct anon_vma *anon_vma = NULL; |
409 | unsigned long anon_mapping; |
410 | |
411 | rcu_read_lock(); |
412 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
413 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
414 | goto out; |
415 | if (!page_mapped(page)) |
416 | goto out; |
417 | |
418 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
419 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
420 | anon_vma = NULL; |
421 | goto out; |
422 | } |
423 | |
424 | /* |
425 | * If this page is still mapped, then its anon_vma cannot have been |
426 | * freed. But if it has been unmapped, we have no security against the |
427 | * anon_vma structure being freed and reused (for another anon_vma: |
428 | * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero() |
429 | * above cannot corrupt). |
430 | */ |
431 | if (!page_mapped(page)) { |
432 | rcu_read_unlock(); |
433 | put_anon_vma(anon_vma); |
434 | return NULL; |
435 | } |
436 | out: |
437 | rcu_read_unlock(); |
438 | |
439 | return anon_vma; |
440 | } |
441 | |
442 | /* |
443 | * Similar to page_get_anon_vma() except it locks the anon_vma. |
444 | * |
445 | * Its a little more complex as it tries to keep the fast path to a single |
446 | * atomic op -- the trylock. If we fail the trylock, we fall back to getting a |
447 | * reference like with page_get_anon_vma() and then block on the mutex. |
448 | */ |
449 | struct anon_vma *page_lock_anon_vma_read(struct page *page) |
450 | { |
451 | struct anon_vma *anon_vma = NULL; |
452 | struct anon_vma *root_anon_vma; |
453 | unsigned long anon_mapping; |
454 | |
455 | rcu_read_lock(); |
456 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
457 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
458 | goto out; |
459 | if (!page_mapped(page)) |
460 | goto out; |
461 | |
462 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
463 | root_anon_vma = ACCESS_ONCE(anon_vma->root); |
464 | if (down_read_trylock(&root_anon_vma->rwsem)) { |
465 | /* |
466 | * If the page is still mapped, then this anon_vma is still |
467 | * its anon_vma, and holding the mutex ensures that it will |
468 | * not go away, see anon_vma_free(). |
469 | */ |
470 | if (!page_mapped(page)) { |
471 | up_read(&root_anon_vma->rwsem); |
472 | anon_vma = NULL; |
473 | } |
474 | goto out; |
475 | } |
476 | |
477 | /* trylock failed, we got to sleep */ |
478 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
479 | anon_vma = NULL; |
480 | goto out; |
481 | } |
482 | |
483 | if (!page_mapped(page)) { |
484 | rcu_read_unlock(); |
485 | put_anon_vma(anon_vma); |
486 | return NULL; |
487 | } |
488 | |
489 | /* we pinned the anon_vma, its safe to sleep */ |
490 | rcu_read_unlock(); |
491 | anon_vma_lock_read(anon_vma); |
492 | |
493 | if (atomic_dec_and_test(&anon_vma->refcount)) { |
494 | /* |
495 | * Oops, we held the last refcount, release the lock |
496 | * and bail -- can't simply use put_anon_vma() because |
497 | * we'll deadlock on the anon_vma_lock_write() recursion. |
498 | */ |
499 | anon_vma_unlock_read(anon_vma); |
500 | __put_anon_vma(anon_vma); |
501 | anon_vma = NULL; |
502 | } |
503 | |
504 | return anon_vma; |
505 | |
506 | out: |
507 | rcu_read_unlock(); |
508 | return anon_vma; |
509 | } |
510 | |
511 | void page_unlock_anon_vma_read(struct anon_vma *anon_vma) |
512 | { |
513 | anon_vma_unlock_read(anon_vma); |
514 | } |
515 | |
516 | /* |
517 | * At what user virtual address is page expected in @vma? |
518 | */ |
519 | static inline unsigned long |
520 | __vma_address(struct page *page, struct vm_area_struct *vma) |
521 | { |
522 | pgoff_t pgoff = page_to_pgoff(page); |
523 | return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
524 | } |
525 | |
526 | inline unsigned long |
527 | vma_address(struct page *page, struct vm_area_struct *vma) |
528 | { |
529 | unsigned long address = __vma_address(page, vma); |
530 | |
531 | /* page should be within @vma mapping range */ |
532 | VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); |
533 | |
534 | return address; |
535 | } |
536 | |
537 | /* |
538 | * At what user virtual address is page expected in vma? |
539 | * Caller should check the page is actually part of the vma. |
540 | */ |
541 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) |
542 | { |
543 | unsigned long address; |
544 | if (PageAnon(page)) { |
545 | struct anon_vma *page__anon_vma = page_anon_vma(page); |
546 | /* |
547 | * Note: swapoff's unuse_vma() is more efficient with this |
548 | * check, and needs it to match anon_vma when KSM is active. |
549 | */ |
550 | if (!vma->anon_vma || !page__anon_vma || |
551 | vma->anon_vma->root != page__anon_vma->root) |
552 | return -EFAULT; |
553 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { |
554 | if (!vma->vm_file || |
555 | vma->vm_file->f_mapping != page->mapping) |
556 | return -EFAULT; |
557 | } else |
558 | return -EFAULT; |
559 | address = __vma_address(page, vma); |
560 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) |
561 | return -EFAULT; |
562 | return address; |
563 | } |
564 | |
565 | pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) |
566 | { |
567 | pgd_t *pgd; |
568 | pud_t *pud; |
569 | pmd_t *pmd = NULL; |
570 | pmd_t pmde; |
571 | |
572 | pgd = pgd_offset(mm, address); |
573 | if (!pgd_present(*pgd)) |
574 | goto out; |
575 | |
576 | pud = pud_offset(pgd, address); |
577 | if (!pud_present(*pud)) |
578 | goto out; |
579 | |
580 | pmd = pmd_offset(pud, address); |
581 | /* |
582 | * Some THP functions use the sequence pmdp_clear_flush(), set_pmd_at() |
583 | * without holding anon_vma lock for write. So when looking for a |
584 | * genuine pmde (in which to find pte), test present and !THP together. |
585 | */ |
586 | pmde = ACCESS_ONCE(*pmd); |
587 | if (!pmd_present(pmde) || pmd_trans_huge(pmde)) |
588 | pmd = NULL; |
589 | out: |
590 | return pmd; |
591 | } |
592 | |
593 | /* |
594 | * Check that @page is mapped at @address into @mm. |
595 | * |
596 | * If @sync is false, page_check_address may perform a racy check to avoid |
597 | * the page table lock when the pte is not present (helpful when reclaiming |
598 | * highly shared pages). |
599 | * |
600 | * On success returns with pte mapped and locked. |
601 | */ |
602 | pte_t *__page_check_address(struct page *page, struct mm_struct *mm, |
603 | unsigned long address, spinlock_t **ptlp, int sync) |
604 | { |
605 | pmd_t *pmd; |
606 | pte_t *pte; |
607 | spinlock_t *ptl; |
608 | |
609 | if (unlikely(PageHuge(page))) { |
610 | /* when pud is not present, pte will be NULL */ |
611 | pte = huge_pte_offset(mm, address); |
612 | if (!pte) |
613 | return NULL; |
614 | |
615 | ptl = huge_pte_lockptr(page_hstate(page), mm, pte); |
616 | goto check; |
617 | } |
618 | |
619 | pmd = mm_find_pmd(mm, address); |
620 | if (!pmd) |
621 | return NULL; |
622 | |
623 | pte = pte_offset_map(pmd, address); |
624 | /* Make a quick check before getting the lock */ |
625 | if (!sync && !pte_present(*pte)) { |
626 | pte_unmap(pte); |
627 | return NULL; |
628 | } |
629 | |
630 | ptl = pte_lockptr(mm, pmd); |
631 | check: |
632 | spin_lock(ptl); |
633 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { |
634 | *ptlp = ptl; |
635 | return pte; |
636 | } |
637 | pte_unmap_unlock(pte, ptl); |
638 | return NULL; |
639 | } |
640 | |
641 | /** |
642 | * page_mapped_in_vma - check whether a page is really mapped in a VMA |
643 | * @page: the page to test |
644 | * @vma: the VMA to test |
645 | * |
646 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 |
647 | * if the page is not mapped into the page tables of this VMA. Only |
648 | * valid for normal file or anonymous VMAs. |
649 | */ |
650 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) |
651 | { |
652 | unsigned long address; |
653 | pte_t *pte; |
654 | spinlock_t *ptl; |
655 | |
656 | address = __vma_address(page, vma); |
657 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) |
658 | return 0; |
659 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); |
660 | if (!pte) /* the page is not in this mm */ |
661 | return 0; |
662 | pte_unmap_unlock(pte, ptl); |
663 | |
664 | return 1; |
665 | } |
666 | |
667 | struct page_referenced_arg { |
668 | int mapcount; |
669 | int referenced; |
670 | unsigned long vm_flags; |
671 | struct mem_cgroup *memcg; |
672 | }; |
673 | /* |
674 | * arg: page_referenced_arg will be passed |
675 | */ |
676 | static int page_referenced_one(struct page *page, struct vm_area_struct *vma, |
677 | unsigned long address, void *arg) |
678 | { |
679 | struct mm_struct *mm = vma->vm_mm; |
680 | spinlock_t *ptl; |
681 | int referenced = 0; |
682 | struct page_referenced_arg *pra = arg; |
683 | |
684 | if (unlikely(PageTransHuge(page))) { |
685 | pmd_t *pmd; |
686 | |
687 | /* |
688 | * rmap might return false positives; we must filter |
689 | * these out using page_check_address_pmd(). |
690 | */ |
691 | pmd = page_check_address_pmd(page, mm, address, |
692 | PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl); |
693 | if (!pmd) |
694 | return SWAP_AGAIN; |
695 | |
696 | if (vma->vm_flags & VM_LOCKED) { |
697 | spin_unlock(ptl); |
698 | pra->vm_flags |= VM_LOCKED; |
699 | return SWAP_FAIL; /* To break the loop */ |
700 | } |
701 | |
702 | /* go ahead even if the pmd is pmd_trans_splitting() */ |
703 | if (pmdp_clear_flush_young_notify(vma, address, pmd)) |
704 | referenced++; |
705 | spin_unlock(ptl); |
706 | } else { |
707 | pte_t *pte; |
708 | |
709 | /* |
710 | * rmap might return false positives; we must filter |
711 | * these out using page_check_address(). |
712 | */ |
713 | pte = page_check_address(page, mm, address, &ptl, 0); |
714 | if (!pte) |
715 | return SWAP_AGAIN; |
716 | |
717 | if (vma->vm_flags & VM_LOCKED) { |
718 | pte_unmap_unlock(pte, ptl); |
719 | pra->vm_flags |= VM_LOCKED; |
720 | return SWAP_FAIL; /* To break the loop */ |
721 | } |
722 | |
723 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
724 | /* |
725 | * Don't treat a reference through a sequentially read |
726 | * mapping as such. If the page has been used in |
727 | * another mapping, we will catch it; if this other |
728 | * mapping is already gone, the unmap path will have |
729 | * set PG_referenced or activated the page. |
730 | */ |
731 | if (likely(!(vma->vm_flags & VM_SEQ_READ))) |
732 | referenced++; |
733 | } |
734 | pte_unmap_unlock(pte, ptl); |
735 | } |
736 | |
737 | if (referenced) { |
738 | pra->referenced++; |
739 | pra->vm_flags |= vma->vm_flags; |
740 | } |
741 | |
742 | pra->mapcount--; |
743 | if (!pra->mapcount) |
744 | return SWAP_SUCCESS; /* To break the loop */ |
745 | |
746 | return SWAP_AGAIN; |
747 | } |
748 | |
749 | static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) |
750 | { |
751 | struct page_referenced_arg *pra = arg; |
752 | struct mem_cgroup *memcg = pra->memcg; |
753 | |
754 | if (!mm_match_cgroup(vma->vm_mm, memcg)) |
755 | return true; |
756 | |
757 | return false; |
758 | } |
759 | |
760 | /** |
761 | * page_referenced - test if the page was referenced |
762 | * @page: the page to test |
763 | * @is_locked: caller holds lock on the page |
764 | * @memcg: target memory cgroup |
765 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
766 | * |
767 | * Quick test_and_clear_referenced for all mappings to a page, |
768 | * returns the number of ptes which referenced the page. |
769 | */ |
770 | int page_referenced(struct page *page, |
771 | int is_locked, |
772 | struct mem_cgroup *memcg, |
773 | unsigned long *vm_flags) |
774 | { |
775 | int ret; |
776 | int we_locked = 0; |
777 | struct page_referenced_arg pra = { |
778 | .mapcount = page_mapcount(page), |
779 | .memcg = memcg, |
780 | }; |
781 | struct rmap_walk_control rwc = { |
782 | .rmap_one = page_referenced_one, |
783 | .arg = (void *)&pra, |
784 | .anon_lock = page_lock_anon_vma_read, |
785 | }; |
786 | |
787 | *vm_flags = 0; |
788 | if (!page_mapped(page)) |
789 | return 0; |
790 | |
791 | if (!page_rmapping(page)) |
792 | return 0; |
793 | |
794 | if (!is_locked && (!PageAnon(page) || PageKsm(page))) { |
795 | we_locked = trylock_page(page); |
796 | if (!we_locked) |
797 | return 1; |
798 | } |
799 | |
800 | /* |
801 | * If we are reclaiming on behalf of a cgroup, skip |
802 | * counting on behalf of references from different |
803 | * cgroups |
804 | */ |
805 | if (memcg) { |
806 | rwc.invalid_vma = invalid_page_referenced_vma; |
807 | } |
808 | |
809 | ret = rmap_walk(page, &rwc); |
810 | *vm_flags = pra.vm_flags; |
811 | |
812 | if (we_locked) |
813 | unlock_page(page); |
814 | |
815 | return pra.referenced; |
816 | } |
817 | |
818 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, |
819 | unsigned long address, void *arg) |
820 | { |
821 | struct mm_struct *mm = vma->vm_mm; |
822 | pte_t *pte; |
823 | spinlock_t *ptl; |
824 | int ret = 0; |
825 | int *cleaned = arg; |
826 | |
827 | pte = page_check_address(page, mm, address, &ptl, 1); |
828 | if (!pte) |
829 | goto out; |
830 | |
831 | if (pte_dirty(*pte) || pte_write(*pte)) { |
832 | pte_t entry; |
833 | |
834 | flush_cache_page(vma, address, pte_pfn(*pte)); |
835 | entry = ptep_clear_flush(vma, address, pte); |
836 | entry = pte_wrprotect(entry); |
837 | entry = pte_mkclean(entry); |
838 | set_pte_at(mm, address, pte, entry); |
839 | ret = 1; |
840 | } |
841 | |
842 | pte_unmap_unlock(pte, ptl); |
843 | |
844 | if (ret) { |
845 | mmu_notifier_invalidate_page(mm, address); |
846 | (*cleaned)++; |
847 | } |
848 | out: |
849 | return SWAP_AGAIN; |
850 | } |
851 | |
852 | static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg) |
853 | { |
854 | if (vma->vm_flags & VM_SHARED) |
855 | return false; |
856 | |
857 | return true; |
858 | } |
859 | |
860 | int page_mkclean(struct page *page) |
861 | { |
862 | int cleaned = 0; |
863 | struct address_space *mapping; |
864 | struct rmap_walk_control rwc = { |
865 | .arg = (void *)&cleaned, |
866 | .rmap_one = page_mkclean_one, |
867 | .invalid_vma = invalid_mkclean_vma, |
868 | }; |
869 | |
870 | BUG_ON(!PageLocked(page)); |
871 | |
872 | if (!page_mapped(page)) |
873 | return 0; |
874 | |
875 | mapping = page_mapping(page); |
876 | if (!mapping) |
877 | return 0; |
878 | |
879 | rmap_walk(page, &rwc); |
880 | |
881 | return cleaned; |
882 | } |
883 | EXPORT_SYMBOL_GPL(page_mkclean); |
884 | |
885 | /** |
886 | * page_move_anon_rmap - move a page to our anon_vma |
887 | * @page: the page to move to our anon_vma |
888 | * @vma: the vma the page belongs to |
889 | * @address: the user virtual address mapped |
890 | * |
891 | * When a page belongs exclusively to one process after a COW event, |
892 | * that page can be moved into the anon_vma that belongs to just that |
893 | * process, so the rmap code will not search the parent or sibling |
894 | * processes. |
895 | */ |
896 | void page_move_anon_rmap(struct page *page, |
897 | struct vm_area_struct *vma, unsigned long address) |
898 | { |
899 | struct anon_vma *anon_vma = vma->anon_vma; |
900 | |
901 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
902 | VM_BUG_ON_VMA(!anon_vma, vma); |
903 | VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page); |
904 | |
905 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
906 | page->mapping = (struct address_space *) anon_vma; |
907 | } |
908 | |
909 | /** |
910 | * __page_set_anon_rmap - set up new anonymous rmap |
911 | * @page: Page to add to rmap |
912 | * @vma: VM area to add page to. |
913 | * @address: User virtual address of the mapping |
914 | * @exclusive: the page is exclusively owned by the current process |
915 | */ |
916 | static void __page_set_anon_rmap(struct page *page, |
917 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
918 | { |
919 | struct anon_vma *anon_vma = vma->anon_vma; |
920 | |
921 | BUG_ON(!anon_vma); |
922 | |
923 | if (PageAnon(page)) |
924 | return; |
925 | |
926 | /* |
927 | * If the page isn't exclusively mapped into this vma, |
928 | * we must use the _oldest_ possible anon_vma for the |
929 | * page mapping! |
930 | */ |
931 | if (!exclusive) |
932 | anon_vma = anon_vma->root; |
933 | |
934 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
935 | page->mapping = (struct address_space *) anon_vma; |
936 | page->index = linear_page_index(vma, address); |
937 | } |
938 | |
939 | /** |
940 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
941 | * @page: the page to add the mapping to |
942 | * @vma: the vm area in which the mapping is added |
943 | * @address: the user virtual address mapped |
944 | */ |
945 | static void __page_check_anon_rmap(struct page *page, |
946 | struct vm_area_struct *vma, unsigned long address) |
947 | { |
948 | #ifdef CONFIG_DEBUG_VM |
949 | /* |
950 | * The page's anon-rmap details (mapping and index) are guaranteed to |
951 | * be set up correctly at this point. |
952 | * |
953 | * We have exclusion against page_add_anon_rmap because the caller |
954 | * always holds the page locked, except if called from page_dup_rmap, |
955 | * in which case the page is already known to be setup. |
956 | * |
957 | * We have exclusion against page_add_new_anon_rmap because those pages |
958 | * are initially only visible via the pagetables, and the pte is locked |
959 | * over the call to page_add_new_anon_rmap. |
960 | */ |
961 | BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); |
962 | BUG_ON(page->index != linear_page_index(vma, address)); |
963 | #endif |
964 | } |
965 | |
966 | /** |
967 | * page_add_anon_rmap - add pte mapping to an anonymous page |
968 | * @page: the page to add the mapping to |
969 | * @vma: the vm area in which the mapping is added |
970 | * @address: the user virtual address mapped |
971 | * |
972 | * The caller needs to hold the pte lock, and the page must be locked in |
973 | * the anon_vma case: to serialize mapping,index checking after setting, |
974 | * and to ensure that PageAnon is not being upgraded racily to PageKsm |
975 | * (but PageKsm is never downgraded to PageAnon). |
976 | */ |
977 | void page_add_anon_rmap(struct page *page, |
978 | struct vm_area_struct *vma, unsigned long address) |
979 | { |
980 | do_page_add_anon_rmap(page, vma, address, 0); |
981 | } |
982 | |
983 | /* |
984 | * Special version of the above for do_swap_page, which often runs |
985 | * into pages that are exclusively owned by the current process. |
986 | * Everybody else should continue to use page_add_anon_rmap above. |
987 | */ |
988 | void do_page_add_anon_rmap(struct page *page, |
989 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
990 | { |
991 | int first = atomic_inc_and_test(&page->_mapcount); |
992 | if (first) { |
993 | /* |
994 | * We use the irq-unsafe __{inc|mod}_zone_page_stat because |
995 | * these counters are not modified in interrupt context, and |
996 | * pte lock(a spinlock) is held, which implies preemption |
997 | * disabled. |
998 | */ |
999 | if (PageTransHuge(page)) |
1000 | __inc_zone_page_state(page, |
1001 | NR_ANON_TRANSPARENT_HUGEPAGES); |
1002 | __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, |
1003 | hpage_nr_pages(page)); |
1004 | } |
1005 | if (unlikely(PageKsm(page))) |
1006 | return; |
1007 | |
1008 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
1009 | /* address might be in next vma when migration races vma_adjust */ |
1010 | if (first) |
1011 | __page_set_anon_rmap(page, vma, address, exclusive); |
1012 | else |
1013 | __page_check_anon_rmap(page, vma, address); |
1014 | } |
1015 | |
1016 | /** |
1017 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
1018 | * @page: the page to add the mapping to |
1019 | * @vma: the vm area in which the mapping is added |
1020 | * @address: the user virtual address mapped |
1021 | * |
1022 | * Same as page_add_anon_rmap but must only be called on *new* pages. |
1023 | * This means the inc-and-test can be bypassed. |
1024 | * Page does not have to be locked. |
1025 | */ |
1026 | void page_add_new_anon_rmap(struct page *page, |
1027 | struct vm_area_struct *vma, unsigned long address) |
1028 | { |
1029 | VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); |
1030 | SetPageSwapBacked(page); |
1031 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ |
1032 | if (PageTransHuge(page)) |
1033 | __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1034 | __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, |
1035 | hpage_nr_pages(page)); |
1036 | __page_set_anon_rmap(page, vma, address, 1); |
1037 | } |
1038 | |
1039 | /** |
1040 | * page_add_file_rmap - add pte mapping to a file page |
1041 | * @page: the page to add the mapping to |
1042 | * |
1043 | * The caller needs to hold the pte lock. |
1044 | */ |
1045 | void page_add_file_rmap(struct page *page) |
1046 | { |
1047 | struct mem_cgroup *memcg; |
1048 | unsigned long flags; |
1049 | bool locked; |
1050 | |
1051 | memcg = mem_cgroup_begin_page_stat(page, &locked, &flags); |
1052 | if (atomic_inc_and_test(&page->_mapcount)) { |
1053 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
1054 | mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED); |
1055 | } |
1056 | mem_cgroup_end_page_stat(memcg, locked, flags); |
1057 | } |
1058 | |
1059 | static void page_remove_file_rmap(struct page *page) |
1060 | { |
1061 | struct mem_cgroup *memcg; |
1062 | unsigned long flags; |
1063 | bool locked; |
1064 | |
1065 | memcg = mem_cgroup_begin_page_stat(page, &locked, &flags); |
1066 | |
1067 | /* page still mapped by someone else? */ |
1068 | if (!atomic_add_negative(-1, &page->_mapcount)) |
1069 | goto out; |
1070 | |
1071 | /* Hugepages are not counted in NR_FILE_MAPPED for now. */ |
1072 | if (unlikely(PageHuge(page))) |
1073 | goto out; |
1074 | |
1075 | /* |
1076 | * We use the irq-unsafe __{inc|mod}_zone_page_stat because |
1077 | * these counters are not modified in interrupt context, and |
1078 | * pte lock(a spinlock) is held, which implies preemption disabled. |
1079 | */ |
1080 | __dec_zone_page_state(page, NR_FILE_MAPPED); |
1081 | mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED); |
1082 | |
1083 | if (unlikely(PageMlocked(page))) |
1084 | clear_page_mlock(page); |
1085 | out: |
1086 | mem_cgroup_end_page_stat(memcg, locked, flags); |
1087 | } |
1088 | |
1089 | /** |
1090 | * page_remove_rmap - take down pte mapping from a page |
1091 | * @page: page to remove mapping from |
1092 | * |
1093 | * The caller needs to hold the pte lock. |
1094 | */ |
1095 | void page_remove_rmap(struct page *page) |
1096 | { |
1097 | if (!PageAnon(page)) { |
1098 | page_remove_file_rmap(page); |
1099 | return; |
1100 | } |
1101 | |
1102 | /* page still mapped by someone else? */ |
1103 | if (!atomic_add_negative(-1, &page->_mapcount)) |
1104 | return; |
1105 | |
1106 | /* Hugepages are not counted in NR_ANON_PAGES for now. */ |
1107 | if (unlikely(PageHuge(page))) |
1108 | return; |
1109 | |
1110 | /* |
1111 | * We use the irq-unsafe __{inc|mod}_zone_page_stat because |
1112 | * these counters are not modified in interrupt context, and |
1113 | * pte lock(a spinlock) is held, which implies preemption disabled. |
1114 | */ |
1115 | if (PageTransHuge(page)) |
1116 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1117 | |
1118 | __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, |
1119 | -hpage_nr_pages(page)); |
1120 | |
1121 | if (unlikely(PageMlocked(page))) |
1122 | clear_page_mlock(page); |
1123 | |
1124 | /* |
1125 | * It would be tidy to reset the PageAnon mapping here, |
1126 | * but that might overwrite a racing page_add_anon_rmap |
1127 | * which increments mapcount after us but sets mapping |
1128 | * before us: so leave the reset to free_hot_cold_page, |
1129 | * and remember that it's only reliable while mapped. |
1130 | * Leaving it set also helps swapoff to reinstate ptes |
1131 | * faster for those pages still in swapcache. |
1132 | */ |
1133 | } |
1134 | |
1135 | /* |
1136 | * @arg: enum ttu_flags will be passed to this argument |
1137 | */ |
1138 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
1139 | unsigned long address, void *arg) |
1140 | { |
1141 | struct mm_struct *mm = vma->vm_mm; |
1142 | pte_t *pte; |
1143 | pte_t pteval; |
1144 | spinlock_t *ptl; |
1145 | int ret = SWAP_AGAIN; |
1146 | enum ttu_flags flags = (enum ttu_flags)arg; |
1147 | |
1148 | pte = page_check_address(page, mm, address, &ptl, 0); |
1149 | if (!pte) |
1150 | goto out; |
1151 | |
1152 | /* |
1153 | * If the page is mlock()d, we cannot swap it out. |
1154 | * If it's recently referenced (perhaps page_referenced |
1155 | * skipped over this mm) then we should reactivate it. |
1156 | */ |
1157 | if (!(flags & TTU_IGNORE_MLOCK)) { |
1158 | if (vma->vm_flags & VM_LOCKED) |
1159 | goto out_mlock; |
1160 | |
1161 | if (flags & TTU_MUNLOCK) |
1162 | goto out_unmap; |
1163 | } |
1164 | if (!(flags & TTU_IGNORE_ACCESS)) { |
1165 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
1166 | ret = SWAP_FAIL; |
1167 | goto out_unmap; |
1168 | } |
1169 | } |
1170 | |
1171 | /* Nuke the page table entry. */ |
1172 | flush_cache_page(vma, address, page_to_pfn(page)); |
1173 | pteval = ptep_clear_flush(vma, address, pte); |
1174 | |
1175 | /* Move the dirty bit to the physical page now the pte is gone. */ |
1176 | if (pte_dirty(pteval)) |
1177 | set_page_dirty(page); |
1178 | |
1179 | /* Update high watermark before we lower rss */ |
1180 | update_hiwater_rss(mm); |
1181 | |
1182 | if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
1183 | if (!PageHuge(page)) { |
1184 | if (PageAnon(page)) |
1185 | dec_mm_counter(mm, MM_ANONPAGES); |
1186 | else |
1187 | dec_mm_counter(mm, MM_FILEPAGES); |
1188 | } |
1189 | set_pte_at(mm, address, pte, |
1190 | swp_entry_to_pte(make_hwpoison_entry(page))); |
1191 | } else if (pte_unused(pteval)) { |
1192 | /* |
1193 | * The guest indicated that the page content is of no |
1194 | * interest anymore. Simply discard the pte, vmscan |
1195 | * will take care of the rest. |
1196 | */ |
1197 | if (PageAnon(page)) |
1198 | dec_mm_counter(mm, MM_ANONPAGES); |
1199 | else |
1200 | dec_mm_counter(mm, MM_FILEPAGES); |
1201 | } else if (PageAnon(page)) { |
1202 | swp_entry_t entry = { .val = page_private(page) }; |
1203 | pte_t swp_pte; |
1204 | |
1205 | if (PageSwapCache(page)) { |
1206 | /* |
1207 | * Store the swap location in the pte. |
1208 | * See handle_pte_fault() ... |
1209 | */ |
1210 | if (swap_duplicate(entry) < 0) { |
1211 | set_pte_at(mm, address, pte, pteval); |
1212 | ret = SWAP_FAIL; |
1213 | goto out_unmap; |
1214 | } |
1215 | if (list_empty(&mm->mmlist)) { |
1216 | spin_lock(&mmlist_lock); |
1217 | if (list_empty(&mm->mmlist)) |
1218 | list_add(&mm->mmlist, &init_mm.mmlist); |
1219 | spin_unlock(&mmlist_lock); |
1220 | } |
1221 | dec_mm_counter(mm, MM_ANONPAGES); |
1222 | inc_mm_counter(mm, MM_SWAPENTS); |
1223 | } else if (IS_ENABLED(CONFIG_MIGRATION)) { |
1224 | /* |
1225 | * Store the pfn of the page in a special migration |
1226 | * pte. do_swap_page() will wait until the migration |
1227 | * pte is removed and then restart fault handling. |
1228 | */ |
1229 | BUG_ON(!(flags & TTU_MIGRATION)); |
1230 | entry = make_migration_entry(page, pte_write(pteval)); |
1231 | } |
1232 | swp_pte = swp_entry_to_pte(entry); |
1233 | if (pte_soft_dirty(pteval)) |
1234 | swp_pte = pte_swp_mksoft_dirty(swp_pte); |
1235 | set_pte_at(mm, address, pte, swp_pte); |
1236 | BUG_ON(pte_file(*pte)); |
1237 | } else if (IS_ENABLED(CONFIG_MIGRATION) && |
1238 | (flags & TTU_MIGRATION)) { |
1239 | /* Establish migration entry for a file page */ |
1240 | swp_entry_t entry; |
1241 | entry = make_migration_entry(page, pte_write(pteval)); |
1242 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
1243 | } else |
1244 | dec_mm_counter(mm, MM_FILEPAGES); |
1245 | |
1246 | page_remove_rmap(page); |
1247 | page_cache_release(page); |
1248 | |
1249 | out_unmap: |
1250 | pte_unmap_unlock(pte, ptl); |
1251 | if (ret != SWAP_FAIL && !(flags & TTU_MUNLOCK)) |
1252 | mmu_notifier_invalidate_page(mm, address); |
1253 | out: |
1254 | return ret; |
1255 | |
1256 | out_mlock: |
1257 | pte_unmap_unlock(pte, ptl); |
1258 | |
1259 | |
1260 | /* |
1261 | * We need mmap_sem locking, Otherwise VM_LOCKED check makes |
1262 | * unstable result and race. Plus, We can't wait here because |
1263 | * we now hold anon_vma->rwsem or mapping->i_mmap_mutex. |
1264 | * if trylock failed, the page remain in evictable lru and later |
1265 | * vmscan could retry to move the page to unevictable lru if the |
1266 | * page is actually mlocked. |
1267 | */ |
1268 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
1269 | if (vma->vm_flags & VM_LOCKED) { |
1270 | mlock_vma_page(page); |
1271 | ret = SWAP_MLOCK; |
1272 | } |
1273 | up_read(&vma->vm_mm->mmap_sem); |
1274 | } |
1275 | return ret; |
1276 | } |
1277 | |
1278 | /* |
1279 | * objrmap doesn't work for nonlinear VMAs because the assumption that |
1280 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. |
1281 | * Consequently, given a particular page and its ->index, we cannot locate the |
1282 | * ptes which are mapping that page without an exhaustive linear search. |
1283 | * |
1284 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which |
1285 | * maps the file to which the target page belongs. The ->vm_private_data field |
1286 | * holds the current cursor into that scan. Successive searches will circulate |
1287 | * around the vma's virtual address space. |
1288 | * |
1289 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, |
1290 | * more scanning pressure is placed against them as well. Eventually pages |
1291 | * will become fully unmapped and are eligible for eviction. |
1292 | * |
1293 | * For very sparsely populated VMAs this is a little inefficient - chances are |
1294 | * there there won't be many ptes located within the scan cluster. In this case |
1295 | * maybe we could scan further - to the end of the pte page, perhaps. |
1296 | * |
1297 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can |
1298 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, |
1299 | * rather than unmapping them. If we encounter the "check_page" that vmscan is |
1300 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. |
1301 | */ |
1302 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) |
1303 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) |
1304 | |
1305 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
1306 | struct vm_area_struct *vma, struct page *check_page) |
1307 | { |
1308 | struct mm_struct *mm = vma->vm_mm; |
1309 | pmd_t *pmd; |
1310 | pte_t *pte; |
1311 | pte_t pteval; |
1312 | spinlock_t *ptl; |
1313 | struct page *page; |
1314 | unsigned long address; |
1315 | unsigned long mmun_start; /* For mmu_notifiers */ |
1316 | unsigned long mmun_end; /* For mmu_notifiers */ |
1317 | unsigned long end; |
1318 | int ret = SWAP_AGAIN; |
1319 | int locked_vma = 0; |
1320 | |
1321 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
1322 | end = address + CLUSTER_SIZE; |
1323 | if (address < vma->vm_start) |
1324 | address = vma->vm_start; |
1325 | if (end > vma->vm_end) |
1326 | end = vma->vm_end; |
1327 | |
1328 | pmd = mm_find_pmd(mm, address); |
1329 | if (!pmd) |
1330 | return ret; |
1331 | |
1332 | mmun_start = address; |
1333 | mmun_end = end; |
1334 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
1335 | |
1336 | /* |
1337 | * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, |
1338 | * keep the sem while scanning the cluster for mlocking pages. |
1339 | */ |
1340 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
1341 | locked_vma = (vma->vm_flags & VM_LOCKED); |
1342 | if (!locked_vma) |
1343 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ |
1344 | } |
1345 | |
1346 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
1347 | |
1348 | /* Update high watermark before we lower rss */ |
1349 | update_hiwater_rss(mm); |
1350 | |
1351 | for (; address < end; pte++, address += PAGE_SIZE) { |
1352 | if (!pte_present(*pte)) |
1353 | continue; |
1354 | page = vm_normal_page(vma, address, *pte); |
1355 | BUG_ON(!page || PageAnon(page)); |
1356 | |
1357 | if (locked_vma) { |
1358 | if (page == check_page) { |
1359 | /* we know we have check_page locked */ |
1360 | mlock_vma_page(page); |
1361 | ret = SWAP_MLOCK; |
1362 | } else if (trylock_page(page)) { |
1363 | /* |
1364 | * If we can lock the page, perform mlock. |
1365 | * Otherwise leave the page alone, it will be |
1366 | * eventually encountered again later. |
1367 | */ |
1368 | mlock_vma_page(page); |
1369 | unlock_page(page); |
1370 | } |
1371 | continue; /* don't unmap */ |
1372 | } |
1373 | |
1374 | /* |
1375 | * No need for _notify because we're within an |
1376 | * mmu_notifier_invalidate_range_ {start|end} scope. |
1377 | */ |
1378 | if (ptep_clear_flush_young(vma, address, pte)) |
1379 | continue; |
1380 | |
1381 | /* Nuke the page table entry. */ |
1382 | flush_cache_page(vma, address, pte_pfn(*pte)); |
1383 | pteval = ptep_clear_flush(vma, address, pte); |
1384 | |
1385 | /* If nonlinear, store the file page offset in the pte. */ |
1386 | if (page->index != linear_page_index(vma, address)) { |
1387 | pte_t ptfile = pgoff_to_pte(page->index); |
1388 | if (pte_soft_dirty(pteval)) |
1389 | ptfile = pte_file_mksoft_dirty(ptfile); |
1390 | set_pte_at(mm, address, pte, ptfile); |
1391 | } |
1392 | |
1393 | /* Move the dirty bit to the physical page now the pte is gone. */ |
1394 | if (pte_dirty(pteval)) |
1395 | set_page_dirty(page); |
1396 | |
1397 | page_remove_rmap(page); |
1398 | page_cache_release(page); |
1399 | dec_mm_counter(mm, MM_FILEPAGES); |
1400 | (*mapcount)--; |
1401 | } |
1402 | pte_unmap_unlock(pte - 1, ptl); |
1403 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1404 | if (locked_vma) |
1405 | up_read(&vma->vm_mm->mmap_sem); |
1406 | return ret; |
1407 | } |
1408 | |
1409 | static int try_to_unmap_nonlinear(struct page *page, |
1410 | struct address_space *mapping, void *arg) |
1411 | { |
1412 | struct vm_area_struct *vma; |
1413 | int ret = SWAP_AGAIN; |
1414 | unsigned long cursor; |
1415 | unsigned long max_nl_cursor = 0; |
1416 | unsigned long max_nl_size = 0; |
1417 | unsigned int mapcount; |
1418 | |
1419 | list_for_each_entry(vma, |
1420 | &mapping->i_mmap_nonlinear, shared.nonlinear) { |
1421 | |
1422 | cursor = (unsigned long) vma->vm_private_data; |
1423 | if (cursor > max_nl_cursor) |
1424 | max_nl_cursor = cursor; |
1425 | cursor = vma->vm_end - vma->vm_start; |
1426 | if (cursor > max_nl_size) |
1427 | max_nl_size = cursor; |
1428 | } |
1429 | |
1430 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1431 | return SWAP_FAIL; |
1432 | } |
1433 | |
1434 | /* |
1435 | * We don't try to search for this page in the nonlinear vmas, |
1436 | * and page_referenced wouldn't have found it anyway. Instead |
1437 | * just walk the nonlinear vmas trying to age and unmap some. |
1438 | * The mapcount of the page we came in with is irrelevant, |
1439 | * but even so use it as a guide to how hard we should try? |
1440 | */ |
1441 | mapcount = page_mapcount(page); |
1442 | if (!mapcount) |
1443 | return ret; |
1444 | |
1445 | cond_resched(); |
1446 | |
1447 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; |
1448 | if (max_nl_cursor == 0) |
1449 | max_nl_cursor = CLUSTER_SIZE; |
1450 | |
1451 | do { |
1452 | list_for_each_entry(vma, |
1453 | &mapping->i_mmap_nonlinear, shared.nonlinear) { |
1454 | |
1455 | cursor = (unsigned long) vma->vm_private_data; |
1456 | while (cursor < max_nl_cursor && |
1457 | cursor < vma->vm_end - vma->vm_start) { |
1458 | if (try_to_unmap_cluster(cursor, &mapcount, |
1459 | vma, page) == SWAP_MLOCK) |
1460 | ret = SWAP_MLOCK; |
1461 | cursor += CLUSTER_SIZE; |
1462 | vma->vm_private_data = (void *) cursor; |
1463 | if ((int)mapcount <= 0) |
1464 | return ret; |
1465 | } |
1466 | vma->vm_private_data = (void *) max_nl_cursor; |
1467 | } |
1468 | cond_resched(); |
1469 | max_nl_cursor += CLUSTER_SIZE; |
1470 | } while (max_nl_cursor <= max_nl_size); |
1471 | |
1472 | /* |
1473 | * Don't loop forever (perhaps all the remaining pages are |
1474 | * in locked vmas). Reset cursor on all unreserved nonlinear |
1475 | * vmas, now forgetting on which ones it had fallen behind. |
1476 | */ |
1477 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear) |
1478 | vma->vm_private_data = NULL; |
1479 | |
1480 | return ret; |
1481 | } |
1482 | |
1483 | bool is_vma_temporary_stack(struct vm_area_struct *vma) |
1484 | { |
1485 | int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); |
1486 | |
1487 | if (!maybe_stack) |
1488 | return false; |
1489 | |
1490 | if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == |
1491 | VM_STACK_INCOMPLETE_SETUP) |
1492 | return true; |
1493 | |
1494 | return false; |
1495 | } |
1496 | |
1497 | static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) |
1498 | { |
1499 | return is_vma_temporary_stack(vma); |
1500 | } |
1501 | |
1502 | static int page_not_mapped(struct page *page) |
1503 | { |
1504 | return !page_mapped(page); |
1505 | }; |
1506 | |
1507 | /** |
1508 | * try_to_unmap - try to remove all page table mappings to a page |
1509 | * @page: the page to get unmapped |
1510 | * @flags: action and flags |
1511 | * |
1512 | * Tries to remove all the page table entries which are mapping this |
1513 | * page, used in the pageout path. Caller must hold the page lock. |
1514 | * Return values are: |
1515 | * |
1516 | * SWAP_SUCCESS - we succeeded in removing all mappings |
1517 | * SWAP_AGAIN - we missed a mapping, try again later |
1518 | * SWAP_FAIL - the page is unswappable |
1519 | * SWAP_MLOCK - page is mlocked. |
1520 | */ |
1521 | int try_to_unmap(struct page *page, enum ttu_flags flags) |
1522 | { |
1523 | int ret; |
1524 | struct rmap_walk_control rwc = { |
1525 | .rmap_one = try_to_unmap_one, |
1526 | .arg = (void *)flags, |
1527 | .done = page_not_mapped, |
1528 | .file_nonlinear = try_to_unmap_nonlinear, |
1529 | .anon_lock = page_lock_anon_vma_read, |
1530 | }; |
1531 | |
1532 | VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page); |
1533 | |
1534 | /* |
1535 | * During exec, a temporary VMA is setup and later moved. |
1536 | * The VMA is moved under the anon_vma lock but not the |
1537 | * page tables leading to a race where migration cannot |
1538 | * find the migration ptes. Rather than increasing the |
1539 | * locking requirements of exec(), migration skips |
1540 | * temporary VMAs until after exec() completes. |
1541 | */ |
1542 | if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page)) |
1543 | rwc.invalid_vma = invalid_migration_vma; |
1544 | |
1545 | ret = rmap_walk(page, &rwc); |
1546 | |
1547 | if (ret != SWAP_MLOCK && !page_mapped(page)) |
1548 | ret = SWAP_SUCCESS; |
1549 | return ret; |
1550 | } |
1551 | |
1552 | /** |
1553 | * try_to_munlock - try to munlock a page |
1554 | * @page: the page to be munlocked |
1555 | * |
1556 | * Called from munlock code. Checks all of the VMAs mapping the page |
1557 | * to make sure nobody else has this page mlocked. The page will be |
1558 | * returned with PG_mlocked cleared if no other vmas have it mlocked. |
1559 | * |
1560 | * Return values are: |
1561 | * |
1562 | * SWAP_AGAIN - no vma is holding page mlocked, or, |
1563 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem |
1564 | * SWAP_FAIL - page cannot be located at present |
1565 | * SWAP_MLOCK - page is now mlocked. |
1566 | */ |
1567 | int try_to_munlock(struct page *page) |
1568 | { |
1569 | int ret; |
1570 | struct rmap_walk_control rwc = { |
1571 | .rmap_one = try_to_unmap_one, |
1572 | .arg = (void *)TTU_MUNLOCK, |
1573 | .done = page_not_mapped, |
1574 | /* |
1575 | * We don't bother to try to find the munlocked page in |
1576 | * nonlinears. It's costly. Instead, later, page reclaim logic |
1577 | * may call try_to_unmap() and recover PG_mlocked lazily. |
1578 | */ |
1579 | .file_nonlinear = NULL, |
1580 | .anon_lock = page_lock_anon_vma_read, |
1581 | |
1582 | }; |
1583 | |
1584 | VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page); |
1585 | |
1586 | ret = rmap_walk(page, &rwc); |
1587 | return ret; |
1588 | } |
1589 | |
1590 | void __put_anon_vma(struct anon_vma *anon_vma) |
1591 | { |
1592 | struct anon_vma *root = anon_vma->root; |
1593 | |
1594 | anon_vma_free(anon_vma); |
1595 | if (root != anon_vma && atomic_dec_and_test(&root->refcount)) |
1596 | anon_vma_free(root); |
1597 | } |
1598 | |
1599 | static struct anon_vma *rmap_walk_anon_lock(struct page *page, |
1600 | struct rmap_walk_control *rwc) |
1601 | { |
1602 | struct anon_vma *anon_vma; |
1603 | |
1604 | if (rwc->anon_lock) |
1605 | return rwc->anon_lock(page); |
1606 | |
1607 | /* |
1608 | * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() |
1609 | * because that depends on page_mapped(); but not all its usages |
1610 | * are holding mmap_sem. Users without mmap_sem are required to |
1611 | * take a reference count to prevent the anon_vma disappearing |
1612 | */ |
1613 | anon_vma = page_anon_vma(page); |
1614 | if (!anon_vma) |
1615 | return NULL; |
1616 | |
1617 | anon_vma_lock_read(anon_vma); |
1618 | return anon_vma; |
1619 | } |
1620 | |
1621 | /* |
1622 | * rmap_walk_anon - do something to anonymous page using the object-based |
1623 | * rmap method |
1624 | * @page: the page to be handled |
1625 | * @rwc: control variable according to each walk type |
1626 | * |
1627 | * Find all the mappings of a page using the mapping pointer and the vma chains |
1628 | * contained in the anon_vma struct it points to. |
1629 | * |
1630 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma |
1631 | * where the page was found will be held for write. So, we won't recheck |
1632 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be |
1633 | * LOCKED. |
1634 | */ |
1635 | static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) |
1636 | { |
1637 | struct anon_vma *anon_vma; |
1638 | pgoff_t pgoff = page_to_pgoff(page); |
1639 | struct anon_vma_chain *avc; |
1640 | int ret = SWAP_AGAIN; |
1641 | |
1642 | anon_vma = rmap_walk_anon_lock(page, rwc); |
1643 | if (!anon_vma) |
1644 | return ret; |
1645 | |
1646 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
1647 | struct vm_area_struct *vma = avc->vma; |
1648 | unsigned long address = vma_address(page, vma); |
1649 | |
1650 | if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) |
1651 | continue; |
1652 | |
1653 | ret = rwc->rmap_one(page, vma, address, rwc->arg); |
1654 | if (ret != SWAP_AGAIN) |
1655 | break; |
1656 | if (rwc->done && rwc->done(page)) |
1657 | break; |
1658 | } |
1659 | anon_vma_unlock_read(anon_vma); |
1660 | return ret; |
1661 | } |
1662 | |
1663 | /* |
1664 | * rmap_walk_file - do something to file page using the object-based rmap method |
1665 | * @page: the page to be handled |
1666 | * @rwc: control variable according to each walk type |
1667 | * |
1668 | * Find all the mappings of a page using the mapping pointer and the vma chains |
1669 | * contained in the address_space struct it points to. |
1670 | * |
1671 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma |
1672 | * where the page was found will be held for write. So, we won't recheck |
1673 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be |
1674 | * LOCKED. |
1675 | */ |
1676 | static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) |
1677 | { |
1678 | struct address_space *mapping = page->mapping; |
1679 | pgoff_t pgoff = page_to_pgoff(page); |
1680 | struct vm_area_struct *vma; |
1681 | int ret = SWAP_AGAIN; |
1682 | |
1683 | /* |
1684 | * The page lock not only makes sure that page->mapping cannot |
1685 | * suddenly be NULLified by truncation, it makes sure that the |
1686 | * structure at mapping cannot be freed and reused yet, |
1687 | * so we can safely take mapping->i_mmap_mutex. |
1688 | */ |
1689 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
1690 | |
1691 | if (!mapping) |
1692 | return ret; |
1693 | mutex_lock(&mapping->i_mmap_mutex); |
1694 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
1695 | unsigned long address = vma_address(page, vma); |
1696 | |
1697 | if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) |
1698 | continue; |
1699 | |
1700 | ret = rwc->rmap_one(page, vma, address, rwc->arg); |
1701 | if (ret != SWAP_AGAIN) |
1702 | goto done; |
1703 | if (rwc->done && rwc->done(page)) |
1704 | goto done; |
1705 | } |
1706 | |
1707 | if (!rwc->file_nonlinear) |
1708 | goto done; |
1709 | |
1710 | if (list_empty(&mapping->i_mmap_nonlinear)) |
1711 | goto done; |
1712 | |
1713 | ret = rwc->file_nonlinear(page, mapping, rwc->arg); |
1714 | |
1715 | done: |
1716 | mutex_unlock(&mapping->i_mmap_mutex); |
1717 | return ret; |
1718 | } |
1719 | |
1720 | int rmap_walk(struct page *page, struct rmap_walk_control *rwc) |
1721 | { |
1722 | if (unlikely(PageKsm(page))) |
1723 | return rmap_walk_ksm(page, rwc); |
1724 | else if (PageAnon(page)) |
1725 | return rmap_walk_anon(page, rwc); |
1726 | else |
1727 | return rmap_walk_file(page, rwc); |
1728 | } |
1729 | |
1730 | #ifdef CONFIG_HUGETLB_PAGE |
1731 | /* |
1732 | * The following three functions are for anonymous (private mapped) hugepages. |
1733 | * Unlike common anonymous pages, anonymous hugepages have no accounting code |
1734 | * and no lru code, because we handle hugepages differently from common pages. |
1735 | */ |
1736 | static void __hugepage_set_anon_rmap(struct page *page, |
1737 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
1738 | { |
1739 | struct anon_vma *anon_vma = vma->anon_vma; |
1740 | |
1741 | BUG_ON(!anon_vma); |
1742 | |
1743 | if (PageAnon(page)) |
1744 | return; |
1745 | if (!exclusive) |
1746 | anon_vma = anon_vma->root; |
1747 | |
1748 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1749 | page->mapping = (struct address_space *) anon_vma; |
1750 | page->index = linear_page_index(vma, address); |
1751 | } |
1752 | |
1753 | void hugepage_add_anon_rmap(struct page *page, |
1754 | struct vm_area_struct *vma, unsigned long address) |
1755 | { |
1756 | struct anon_vma *anon_vma = vma->anon_vma; |
1757 | int first; |
1758 | |
1759 | BUG_ON(!PageLocked(page)); |
1760 | BUG_ON(!anon_vma); |
1761 | /* address might be in next vma when migration races vma_adjust */ |
1762 | first = atomic_inc_and_test(&page->_mapcount); |
1763 | if (first) |
1764 | __hugepage_set_anon_rmap(page, vma, address, 0); |
1765 | } |
1766 | |
1767 | void hugepage_add_new_anon_rmap(struct page *page, |
1768 | struct vm_area_struct *vma, unsigned long address) |
1769 | { |
1770 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
1771 | atomic_set(&page->_mapcount, 0); |
1772 | __hugepage_set_anon_rmap(page, vma, address, 1); |
1773 | } |
1774 | #endif /* CONFIG_HUGETLB_PAGE */ |
1775 |
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v2.6.34-rc5
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