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b20a3503 CL |
1 | /* |
2 | * Memory Migration functionality - linux/mm/migration.c | |
3 | * | |
4 | * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter | |
5 | * | |
6 | * Page migration was first developed in the context of the memory hotplug | |
7 | * project. The main authors of the migration code are: | |
8 | * | |
9 | * IWAMOTO Toshihiro <iwamoto@valinux.co.jp> | |
10 | * Hirokazu Takahashi <taka@valinux.co.jp> | |
11 | * Dave Hansen <haveblue@us.ibm.com> | |
cde53535 | 12 | * Christoph Lameter |
b20a3503 CL |
13 | */ |
14 | ||
15 | #include <linux/migrate.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/swap.h> | |
0697212a | 18 | #include <linux/swapops.h> |
b20a3503 | 19 | #include <linux/pagemap.h> |
e23ca00b | 20 | #include <linux/buffer_head.h> |
b20a3503 | 21 | #include <linux/mm_inline.h> |
b488893a | 22 | #include <linux/nsproxy.h> |
b20a3503 CL |
23 | #include <linux/pagevec.h> |
24 | #include <linux/rmap.h> | |
25 | #include <linux/topology.h> | |
26 | #include <linux/cpu.h> | |
27 | #include <linux/cpuset.h> | |
04e62a29 | 28 | #include <linux/writeback.h> |
742755a1 CL |
29 | #include <linux/mempolicy.h> |
30 | #include <linux/vmalloc.h> | |
86c3a764 | 31 | #include <linux/security.h> |
8a9f3ccd | 32 | #include <linux/memcontrol.h> |
4f5ca265 | 33 | #include <linux/syscalls.h> |
b20a3503 CL |
34 | |
35 | #include "internal.h" | |
36 | ||
b20a3503 CL |
37 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
38 | ||
b20a3503 | 39 | /* |
742755a1 CL |
40 | * migrate_prep() needs to be called before we start compiling a list of pages |
41 | * to be migrated using isolate_lru_page(). | |
b20a3503 CL |
42 | */ |
43 | int migrate_prep(void) | |
44 | { | |
b20a3503 CL |
45 | /* |
46 | * Clear the LRU lists so pages can be isolated. | |
47 | * Note that pages may be moved off the LRU after we have | |
48 | * drained them. Those pages will fail to migrate like other | |
49 | * pages that may be busy. | |
50 | */ | |
51 | lru_add_drain_all(); | |
52 | ||
53 | return 0; | |
54 | } | |
55 | ||
56 | static inline void move_to_lru(struct page *page) | |
57 | { | |
b20a3503 CL |
58 | if (PageActive(page)) { |
59 | /* | |
60 | * lru_cache_add_active checks that | |
61 | * the PG_active bit is off. | |
62 | */ | |
63 | ClearPageActive(page); | |
64 | lru_cache_add_active(page); | |
65 | } else { | |
66 | lru_cache_add(page); | |
67 | } | |
68 | put_page(page); | |
69 | } | |
70 | ||
71 | /* | |
72 | * Add isolated pages on the list back to the LRU. | |
73 | * | |
74 | * returns the number of pages put back. | |
75 | */ | |
76 | int putback_lru_pages(struct list_head *l) | |
77 | { | |
78 | struct page *page; | |
79 | struct page *page2; | |
80 | int count = 0; | |
81 | ||
82 | list_for_each_entry_safe(page, page2, l, lru) { | |
e24f0b8f | 83 | list_del(&page->lru); |
b20a3503 CL |
84 | move_to_lru(page); |
85 | count++; | |
86 | } | |
87 | return count; | |
88 | } | |
89 | ||
0697212a CL |
90 | /* |
91 | * Restore a potential migration pte to a working pte entry | |
92 | */ | |
04e62a29 | 93 | static void remove_migration_pte(struct vm_area_struct *vma, |
0697212a CL |
94 | struct page *old, struct page *new) |
95 | { | |
96 | struct mm_struct *mm = vma->vm_mm; | |
97 | swp_entry_t entry; | |
98 | pgd_t *pgd; | |
99 | pud_t *pud; | |
100 | pmd_t *pmd; | |
101 | pte_t *ptep, pte; | |
102 | spinlock_t *ptl; | |
04e62a29 CL |
103 | unsigned long addr = page_address_in_vma(new, vma); |
104 | ||
105 | if (addr == -EFAULT) | |
106 | return; | |
0697212a CL |
107 | |
108 | pgd = pgd_offset(mm, addr); | |
109 | if (!pgd_present(*pgd)) | |
110 | return; | |
111 | ||
112 | pud = pud_offset(pgd, addr); | |
113 | if (!pud_present(*pud)) | |
114 | return; | |
115 | ||
116 | pmd = pmd_offset(pud, addr); | |
117 | if (!pmd_present(*pmd)) | |
118 | return; | |
119 | ||
120 | ptep = pte_offset_map(pmd, addr); | |
121 | ||
122 | if (!is_swap_pte(*ptep)) { | |
123 | pte_unmap(ptep); | |
124 | return; | |
125 | } | |
126 | ||
127 | ptl = pte_lockptr(mm, pmd); | |
128 | spin_lock(ptl); | |
129 | pte = *ptep; | |
130 | if (!is_swap_pte(pte)) | |
131 | goto out; | |
132 | ||
133 | entry = pte_to_swp_entry(pte); | |
134 | ||
135 | if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) | |
136 | goto out; | |
137 | ||
98837c7f HD |
138 | /* |
139 | * Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge. | |
140 | * Failure is not an option here: we're now expected to remove every | |
141 | * migration pte, and will cause crashes otherwise. Normally this | |
142 | * is not an issue: mem_cgroup_prepare_migration bumped up the old | |
143 | * page_cgroup count for safety, that's now attached to the new page, | |
144 | * so this charge should just be another incrementation of the count, | |
145 | * to keep in balance with rmap.c's mem_cgroup_uncharging. But if | |
146 | * there's been a force_empty, those reference counts may no longer | |
147 | * be reliable, and this charge can actually fail: oh well, we don't | |
148 | * make the situation any worse by proceeding as if it had succeeded. | |
149 | */ | |
150 | mem_cgroup_charge(new, mm, GFP_ATOMIC); | |
151 | ||
0697212a CL |
152 | get_page(new); |
153 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
154 | if (is_write_migration_entry(entry)) | |
155 | pte = pte_mkwrite(pte); | |
97ee0524 | 156 | flush_cache_page(vma, addr, pte_pfn(pte)); |
0697212a | 157 | set_pte_at(mm, addr, ptep, pte); |
04e62a29 CL |
158 | |
159 | if (PageAnon(new)) | |
160 | page_add_anon_rmap(new, vma, addr); | |
161 | else | |
162 | page_add_file_rmap(new); | |
163 | ||
164 | /* No need to invalidate - it was non-present before */ | |
165 | update_mmu_cache(vma, addr, pte); | |
04e62a29 | 166 | |
0697212a CL |
167 | out: |
168 | pte_unmap_unlock(ptep, ptl); | |
169 | } | |
170 | ||
171 | /* | |
04e62a29 CL |
172 | * Note that remove_file_migration_ptes will only work on regular mappings, |
173 | * Nonlinear mappings do not use migration entries. | |
174 | */ | |
175 | static void remove_file_migration_ptes(struct page *old, struct page *new) | |
176 | { | |
177 | struct vm_area_struct *vma; | |
178 | struct address_space *mapping = page_mapping(new); | |
179 | struct prio_tree_iter iter; | |
180 | pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
181 | ||
182 | if (!mapping) | |
183 | return; | |
184 | ||
185 | spin_lock(&mapping->i_mmap_lock); | |
186 | ||
187 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) | |
188 | remove_migration_pte(vma, old, new); | |
189 | ||
190 | spin_unlock(&mapping->i_mmap_lock); | |
191 | } | |
192 | ||
193 | /* | |
0697212a CL |
194 | * Must hold mmap_sem lock on at least one of the vmas containing |
195 | * the page so that the anon_vma cannot vanish. | |
196 | */ | |
04e62a29 | 197 | static void remove_anon_migration_ptes(struct page *old, struct page *new) |
0697212a CL |
198 | { |
199 | struct anon_vma *anon_vma; | |
200 | struct vm_area_struct *vma; | |
201 | unsigned long mapping; | |
202 | ||
203 | mapping = (unsigned long)new->mapping; | |
204 | ||
205 | if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) | |
206 | return; | |
207 | ||
208 | /* | |
209 | * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. | |
210 | */ | |
211 | anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); | |
212 | spin_lock(&anon_vma->lock); | |
213 | ||
214 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) | |
04e62a29 | 215 | remove_migration_pte(vma, old, new); |
0697212a CL |
216 | |
217 | spin_unlock(&anon_vma->lock); | |
218 | } | |
219 | ||
04e62a29 CL |
220 | /* |
221 | * Get rid of all migration entries and replace them by | |
222 | * references to the indicated page. | |
223 | */ | |
224 | static void remove_migration_ptes(struct page *old, struct page *new) | |
225 | { | |
226 | if (PageAnon(new)) | |
227 | remove_anon_migration_ptes(old, new); | |
228 | else | |
229 | remove_file_migration_ptes(old, new); | |
230 | } | |
231 | ||
0697212a CL |
232 | /* |
233 | * Something used the pte of a page under migration. We need to | |
234 | * get to the page and wait until migration is finished. | |
235 | * When we return from this function the fault will be retried. | |
236 | * | |
237 | * This function is called from do_swap_page(). | |
238 | */ | |
239 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
240 | unsigned long address) | |
241 | { | |
242 | pte_t *ptep, pte; | |
243 | spinlock_t *ptl; | |
244 | swp_entry_t entry; | |
245 | struct page *page; | |
246 | ||
247 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
248 | pte = *ptep; | |
249 | if (!is_swap_pte(pte)) | |
250 | goto out; | |
251 | ||
252 | entry = pte_to_swp_entry(pte); | |
253 | if (!is_migration_entry(entry)) | |
254 | goto out; | |
255 | ||
256 | page = migration_entry_to_page(entry); | |
257 | ||
e286781d NP |
258 | /* |
259 | * Once radix-tree replacement of page migration started, page_count | |
260 | * *must* be zero. And, we don't want to call wait_on_page_locked() | |
261 | * against a page without get_page(). | |
262 | * So, we use get_page_unless_zero(), here. Even failed, page fault | |
263 | * will occur again. | |
264 | */ | |
265 | if (!get_page_unless_zero(page)) | |
266 | goto out; | |
0697212a CL |
267 | pte_unmap_unlock(ptep, ptl); |
268 | wait_on_page_locked(page); | |
269 | put_page(page); | |
270 | return; | |
271 | out: | |
272 | pte_unmap_unlock(ptep, ptl); | |
273 | } | |
274 | ||
b20a3503 | 275 | /* |
c3fcf8a5 | 276 | * Replace the page in the mapping. |
5b5c7120 CL |
277 | * |
278 | * The number of remaining references must be: | |
279 | * 1 for anonymous pages without a mapping | |
280 | * 2 for pages with a mapping | |
281 | * 3 for pages with a mapping and PagePrivate set. | |
b20a3503 | 282 | */ |
2d1db3b1 CL |
283 | static int migrate_page_move_mapping(struct address_space *mapping, |
284 | struct page *newpage, struct page *page) | |
b20a3503 | 285 | { |
e286781d | 286 | int expected_count; |
7cf9c2c7 | 287 | void **pslot; |
b20a3503 | 288 | |
6c5240ae | 289 | if (!mapping) { |
0e8c7d0f | 290 | /* Anonymous page without mapping */ |
6c5240ae CL |
291 | if (page_count(page) != 1) |
292 | return -EAGAIN; | |
293 | return 0; | |
294 | } | |
295 | ||
19fd6231 | 296 | spin_lock_irq(&mapping->tree_lock); |
b20a3503 | 297 | |
7cf9c2c7 NP |
298 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
299 | page_index(page)); | |
b20a3503 | 300 | |
e286781d NP |
301 | expected_count = 2 + !!PagePrivate(page); |
302 | if (page_count(page) != expected_count || | |
7cf9c2c7 | 303 | (struct page *)radix_tree_deref_slot(pslot) != page) { |
19fd6231 | 304 | spin_unlock_irq(&mapping->tree_lock); |
e23ca00b | 305 | return -EAGAIN; |
b20a3503 CL |
306 | } |
307 | ||
e286781d | 308 | if (!page_freeze_refs(page, expected_count)) { |
19fd6231 | 309 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
310 | return -EAGAIN; |
311 | } | |
312 | ||
b20a3503 CL |
313 | /* |
314 | * Now we know that no one else is looking at the page. | |
b20a3503 | 315 | */ |
7cf9c2c7 | 316 | get_page(newpage); /* add cache reference */ |
6c5240ae | 317 | #ifdef CONFIG_SWAP |
b20a3503 CL |
318 | if (PageSwapCache(page)) { |
319 | SetPageSwapCache(newpage); | |
320 | set_page_private(newpage, page_private(page)); | |
321 | } | |
6c5240ae | 322 | #endif |
b20a3503 | 323 | |
7cf9c2c7 NP |
324 | radix_tree_replace_slot(pslot, newpage); |
325 | ||
e286781d | 326 | page_unfreeze_refs(page, expected_count); |
7cf9c2c7 NP |
327 | /* |
328 | * Drop cache reference from old page. | |
329 | * We know this isn't the last reference. | |
330 | */ | |
b20a3503 | 331 | __put_page(page); |
7cf9c2c7 | 332 | |
0e8c7d0f CL |
333 | /* |
334 | * If moved to a different zone then also account | |
335 | * the page for that zone. Other VM counters will be | |
336 | * taken care of when we establish references to the | |
337 | * new page and drop references to the old page. | |
338 | * | |
339 | * Note that anonymous pages are accounted for | |
340 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
341 | * are mapped to swap space. | |
342 | */ | |
343 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
344 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
345 | ||
19fd6231 NP |
346 | spin_unlock_irq(&mapping->tree_lock); |
347 | if (!PageSwapCache(newpage)) | |
69029cd5 | 348 | mem_cgroup_uncharge_cache_page(page); |
b20a3503 CL |
349 | |
350 | return 0; | |
351 | } | |
b20a3503 CL |
352 | |
353 | /* | |
354 | * Copy the page to its new location | |
355 | */ | |
e7340f73 | 356 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 CL |
357 | { |
358 | copy_highpage(newpage, page); | |
359 | ||
360 | if (PageError(page)) | |
361 | SetPageError(newpage); | |
362 | if (PageReferenced(page)) | |
363 | SetPageReferenced(newpage); | |
364 | if (PageUptodate(page)) | |
365 | SetPageUptodate(newpage); | |
366 | if (PageActive(page)) | |
367 | SetPageActive(newpage); | |
368 | if (PageChecked(page)) | |
369 | SetPageChecked(newpage); | |
370 | if (PageMappedToDisk(page)) | |
371 | SetPageMappedToDisk(newpage); | |
372 | ||
373 | if (PageDirty(page)) { | |
374 | clear_page_dirty_for_io(page); | |
3a902c5f NP |
375 | /* |
376 | * Want to mark the page and the radix tree as dirty, and | |
377 | * redo the accounting that clear_page_dirty_for_io undid, | |
378 | * but we can't use set_page_dirty because that function | |
379 | * is actually a signal that all of the page has become dirty. | |
380 | * Wheras only part of our page may be dirty. | |
381 | */ | |
382 | __set_page_dirty_nobuffers(newpage); | |
b20a3503 CL |
383 | } |
384 | ||
6c5240ae | 385 | #ifdef CONFIG_SWAP |
b20a3503 | 386 | ClearPageSwapCache(page); |
6c5240ae | 387 | #endif |
b20a3503 CL |
388 | ClearPageActive(page); |
389 | ClearPagePrivate(page); | |
390 | set_page_private(page, 0); | |
391 | page->mapping = NULL; | |
392 | ||
393 | /* | |
394 | * If any waiters have accumulated on the new page then | |
395 | * wake them up. | |
396 | */ | |
397 | if (PageWriteback(newpage)) | |
398 | end_page_writeback(newpage); | |
399 | } | |
b20a3503 | 400 | |
1d8b85cc CL |
401 | /************************************************************ |
402 | * Migration functions | |
403 | ***********************************************************/ | |
404 | ||
405 | /* Always fail migration. Used for mappings that are not movable */ | |
2d1db3b1 CL |
406 | int fail_migrate_page(struct address_space *mapping, |
407 | struct page *newpage, struct page *page) | |
1d8b85cc CL |
408 | { |
409 | return -EIO; | |
410 | } | |
411 | EXPORT_SYMBOL(fail_migrate_page); | |
412 | ||
b20a3503 CL |
413 | /* |
414 | * Common logic to directly migrate a single page suitable for | |
415 | * pages that do not use PagePrivate. | |
416 | * | |
417 | * Pages are locked upon entry and exit. | |
418 | */ | |
2d1db3b1 CL |
419 | int migrate_page(struct address_space *mapping, |
420 | struct page *newpage, struct page *page) | |
b20a3503 CL |
421 | { |
422 | int rc; | |
423 | ||
424 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
425 | ||
2d1db3b1 | 426 | rc = migrate_page_move_mapping(mapping, newpage, page); |
b20a3503 CL |
427 | |
428 | if (rc) | |
429 | return rc; | |
430 | ||
431 | migrate_page_copy(newpage, page); | |
b20a3503 CL |
432 | return 0; |
433 | } | |
434 | EXPORT_SYMBOL(migrate_page); | |
435 | ||
9361401e | 436 | #ifdef CONFIG_BLOCK |
1d8b85cc CL |
437 | /* |
438 | * Migration function for pages with buffers. This function can only be used | |
439 | * if the underlying filesystem guarantees that no other references to "page" | |
440 | * exist. | |
441 | */ | |
2d1db3b1 CL |
442 | int buffer_migrate_page(struct address_space *mapping, |
443 | struct page *newpage, struct page *page) | |
1d8b85cc | 444 | { |
1d8b85cc CL |
445 | struct buffer_head *bh, *head; |
446 | int rc; | |
447 | ||
1d8b85cc | 448 | if (!page_has_buffers(page)) |
2d1db3b1 | 449 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
450 | |
451 | head = page_buffers(page); | |
452 | ||
2d1db3b1 | 453 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
454 | |
455 | if (rc) | |
456 | return rc; | |
457 | ||
458 | bh = head; | |
459 | do { | |
460 | get_bh(bh); | |
461 | lock_buffer(bh); | |
462 | bh = bh->b_this_page; | |
463 | ||
464 | } while (bh != head); | |
465 | ||
466 | ClearPagePrivate(page); | |
467 | set_page_private(newpage, page_private(page)); | |
468 | set_page_private(page, 0); | |
469 | put_page(page); | |
470 | get_page(newpage); | |
471 | ||
472 | bh = head; | |
473 | do { | |
474 | set_bh_page(bh, newpage, bh_offset(bh)); | |
475 | bh = bh->b_this_page; | |
476 | ||
477 | } while (bh != head); | |
478 | ||
479 | SetPagePrivate(newpage); | |
480 | ||
481 | migrate_page_copy(newpage, page); | |
482 | ||
483 | bh = head; | |
484 | do { | |
485 | unlock_buffer(bh); | |
486 | put_bh(bh); | |
487 | bh = bh->b_this_page; | |
488 | ||
489 | } while (bh != head); | |
490 | ||
491 | return 0; | |
492 | } | |
493 | EXPORT_SYMBOL(buffer_migrate_page); | |
9361401e | 494 | #endif |
1d8b85cc | 495 | |
04e62a29 CL |
496 | /* |
497 | * Writeback a page to clean the dirty state | |
498 | */ | |
499 | static int writeout(struct address_space *mapping, struct page *page) | |
8351a6e4 | 500 | { |
04e62a29 CL |
501 | struct writeback_control wbc = { |
502 | .sync_mode = WB_SYNC_NONE, | |
503 | .nr_to_write = 1, | |
504 | .range_start = 0, | |
505 | .range_end = LLONG_MAX, | |
506 | .nonblocking = 1, | |
507 | .for_reclaim = 1 | |
508 | }; | |
509 | int rc; | |
510 | ||
511 | if (!mapping->a_ops->writepage) | |
512 | /* No write method for the address space */ | |
513 | return -EINVAL; | |
514 | ||
515 | if (!clear_page_dirty_for_io(page)) | |
516 | /* Someone else already triggered a write */ | |
517 | return -EAGAIN; | |
518 | ||
8351a6e4 | 519 | /* |
04e62a29 CL |
520 | * A dirty page may imply that the underlying filesystem has |
521 | * the page on some queue. So the page must be clean for | |
522 | * migration. Writeout may mean we loose the lock and the | |
523 | * page state is no longer what we checked for earlier. | |
524 | * At this point we know that the migration attempt cannot | |
525 | * be successful. | |
8351a6e4 | 526 | */ |
04e62a29 | 527 | remove_migration_ptes(page, page); |
8351a6e4 | 528 | |
04e62a29 CL |
529 | rc = mapping->a_ops->writepage(page, &wbc); |
530 | if (rc < 0) | |
531 | /* I/O Error writing */ | |
532 | return -EIO; | |
8351a6e4 | 533 | |
04e62a29 CL |
534 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
535 | /* unlocked. Relock */ | |
536 | lock_page(page); | |
537 | ||
538 | return -EAGAIN; | |
539 | } | |
540 | ||
541 | /* | |
542 | * Default handling if a filesystem does not provide a migration function. | |
543 | */ | |
544 | static int fallback_migrate_page(struct address_space *mapping, | |
545 | struct page *newpage, struct page *page) | |
546 | { | |
547 | if (PageDirty(page)) | |
548 | return writeout(mapping, page); | |
8351a6e4 CL |
549 | |
550 | /* | |
551 | * Buffers may be managed in a filesystem specific way. | |
552 | * We must have no buffers or drop them. | |
553 | */ | |
b398f6bf | 554 | if (PagePrivate(page) && |
8351a6e4 CL |
555 | !try_to_release_page(page, GFP_KERNEL)) |
556 | return -EAGAIN; | |
557 | ||
558 | return migrate_page(mapping, newpage, page); | |
559 | } | |
560 | ||
e24f0b8f CL |
561 | /* |
562 | * Move a page to a newly allocated page | |
563 | * The page is locked and all ptes have been successfully removed. | |
564 | * | |
565 | * The new page will have replaced the old page if this function | |
566 | * is successful. | |
567 | */ | |
568 | static int move_to_new_page(struct page *newpage, struct page *page) | |
569 | { | |
570 | struct address_space *mapping; | |
571 | int rc; | |
572 | ||
573 | /* | |
574 | * Block others from accessing the page when we get around to | |
575 | * establishing additional references. We are the only one | |
576 | * holding a reference to the new page at this point. | |
577 | */ | |
529ae9aa | 578 | if (!trylock_page(newpage)) |
e24f0b8f CL |
579 | BUG(); |
580 | ||
581 | /* Prepare mapping for the new page.*/ | |
582 | newpage->index = page->index; | |
583 | newpage->mapping = page->mapping; | |
584 | ||
585 | mapping = page_mapping(page); | |
586 | if (!mapping) | |
587 | rc = migrate_page(mapping, newpage, page); | |
588 | else if (mapping->a_ops->migratepage) | |
589 | /* | |
590 | * Most pages have a mapping and most filesystems | |
591 | * should provide a migration function. Anonymous | |
592 | * pages are part of swap space which also has its | |
593 | * own migration function. This is the most common | |
594 | * path for page migration. | |
595 | */ | |
596 | rc = mapping->a_ops->migratepage(mapping, | |
597 | newpage, page); | |
598 | else | |
599 | rc = fallback_migrate_page(mapping, newpage, page); | |
600 | ||
ae41be37 | 601 | if (!rc) { |
e24f0b8f | 602 | remove_migration_ptes(page, newpage); |
ae41be37 | 603 | } else |
e24f0b8f CL |
604 | newpage->mapping = NULL; |
605 | ||
606 | unlock_page(newpage); | |
607 | ||
608 | return rc; | |
609 | } | |
610 | ||
611 | /* | |
612 | * Obtain the lock on page, remove all ptes and migrate the page | |
613 | * to the newly allocated page in newpage. | |
614 | */ | |
95a402c3 CL |
615 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
616 | struct page *page, int force) | |
e24f0b8f CL |
617 | { |
618 | int rc = 0; | |
742755a1 CL |
619 | int *result = NULL; |
620 | struct page *newpage = get_new_page(page, private, &result); | |
989f89c5 | 621 | int rcu_locked = 0; |
ae41be37 | 622 | int charge = 0; |
95a402c3 CL |
623 | |
624 | if (!newpage) | |
625 | return -ENOMEM; | |
e24f0b8f CL |
626 | |
627 | if (page_count(page) == 1) | |
628 | /* page was freed from under us. So we are done. */ | |
95a402c3 | 629 | goto move_newpage; |
e24f0b8f | 630 | |
e8589cc1 KH |
631 | charge = mem_cgroup_prepare_migration(page, newpage); |
632 | if (charge == -ENOMEM) { | |
633 | rc = -ENOMEM; | |
634 | goto move_newpage; | |
635 | } | |
636 | /* prepare cgroup just returns 0 or -ENOMEM */ | |
637 | BUG_ON(charge); | |
638 | ||
e24f0b8f | 639 | rc = -EAGAIN; |
529ae9aa | 640 | if (!trylock_page(page)) { |
e24f0b8f | 641 | if (!force) |
95a402c3 | 642 | goto move_newpage; |
e24f0b8f CL |
643 | lock_page(page); |
644 | } | |
645 | ||
646 | if (PageWriteback(page)) { | |
647 | if (!force) | |
648 | goto unlock; | |
649 | wait_on_page_writeback(page); | |
650 | } | |
e24f0b8f | 651 | /* |
dc386d4d KH |
652 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
653 | * we cannot notice that anon_vma is freed while we migrates a page. | |
654 | * This rcu_read_lock() delays freeing anon_vma pointer until the end | |
655 | * of migration. File cache pages are no problem because of page_lock() | |
989f89c5 KH |
656 | * File Caches may use write_page() or lock_page() in migration, then, |
657 | * just care Anon page here. | |
dc386d4d | 658 | */ |
989f89c5 KH |
659 | if (PageAnon(page)) { |
660 | rcu_read_lock(); | |
661 | rcu_locked = 1; | |
662 | } | |
62e1c553 | 663 | |
dc386d4d | 664 | /* |
62e1c553 SL |
665 | * Corner case handling: |
666 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
667 | * and treated as swapcache but it has no rmap yet. | |
668 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
669 | * trigger a BUG. So handle it here. | |
670 | * 2. An orphaned page (see truncate_complete_page) might have | |
671 | * fs-private metadata. The page can be picked up due to memory | |
672 | * offlining. Everywhere else except page reclaim, the page is | |
673 | * invisible to the vm, so the page can not be migrated. So try to | |
674 | * free the metadata, so the page can be freed. | |
e24f0b8f | 675 | */ |
62e1c553 SL |
676 | if (!page->mapping) { |
677 | if (!PageAnon(page) && PagePrivate(page)) { | |
678 | /* | |
679 | * Go direct to try_to_free_buffers() here because | |
680 | * a) that's what try_to_release_page() would do anyway | |
681 | * b) we may be under rcu_read_lock() here, so we can't | |
682 | * use GFP_KERNEL which is what try_to_release_page() | |
683 | * needs to be effective. | |
684 | */ | |
685 | try_to_free_buffers(page); | |
686 | } | |
dc386d4d | 687 | goto rcu_unlock; |
62e1c553 SL |
688 | } |
689 | ||
dc386d4d | 690 | /* Establish migration ptes or remove ptes */ |
e6a1530d | 691 | try_to_unmap(page, 1); |
dc386d4d | 692 | |
e6a1530d CL |
693 | if (!page_mapped(page)) |
694 | rc = move_to_new_page(newpage, page); | |
e24f0b8f | 695 | |
e8589cc1 | 696 | if (rc) |
e24f0b8f | 697 | remove_migration_ptes(page, page); |
dc386d4d | 698 | rcu_unlock: |
989f89c5 KH |
699 | if (rcu_locked) |
700 | rcu_read_unlock(); | |
e6a1530d | 701 | |
e24f0b8f | 702 | unlock: |
dc386d4d | 703 | |
e24f0b8f | 704 | unlock_page(page); |
95a402c3 | 705 | |
e24f0b8f | 706 | if (rc != -EAGAIN) { |
aaa994b3 CL |
707 | /* |
708 | * A page that has been migrated has all references | |
709 | * removed and will be freed. A page that has not been | |
710 | * migrated will have kepts its references and be | |
711 | * restored. | |
712 | */ | |
713 | list_del(&page->lru); | |
714 | move_to_lru(page); | |
e24f0b8f | 715 | } |
95a402c3 CL |
716 | |
717 | move_newpage: | |
e8589cc1 KH |
718 | if (!charge) |
719 | mem_cgroup_end_migration(newpage); | |
95a402c3 CL |
720 | /* |
721 | * Move the new page to the LRU. If migration was not successful | |
722 | * then this will free the page. | |
723 | */ | |
724 | move_to_lru(newpage); | |
742755a1 CL |
725 | if (result) { |
726 | if (rc) | |
727 | *result = rc; | |
728 | else | |
729 | *result = page_to_nid(newpage); | |
730 | } | |
e24f0b8f CL |
731 | return rc; |
732 | } | |
733 | ||
b20a3503 CL |
734 | /* |
735 | * migrate_pages | |
736 | * | |
95a402c3 CL |
737 | * The function takes one list of pages to migrate and a function |
738 | * that determines from the page to be migrated and the private data | |
739 | * the target of the move and allocates the page. | |
b20a3503 CL |
740 | * |
741 | * The function returns after 10 attempts or if no pages | |
742 | * are movable anymore because to has become empty | |
aaa994b3 | 743 | * or no retryable pages exist anymore. All pages will be |
e9534b3f | 744 | * returned to the LRU or freed. |
b20a3503 | 745 | * |
95a402c3 | 746 | * Return: Number of pages not migrated or error code. |
b20a3503 | 747 | */ |
95a402c3 CL |
748 | int migrate_pages(struct list_head *from, |
749 | new_page_t get_new_page, unsigned long private) | |
b20a3503 | 750 | { |
e24f0b8f | 751 | int retry = 1; |
b20a3503 CL |
752 | int nr_failed = 0; |
753 | int pass = 0; | |
754 | struct page *page; | |
755 | struct page *page2; | |
756 | int swapwrite = current->flags & PF_SWAPWRITE; | |
757 | int rc; | |
758 | ||
759 | if (!swapwrite) | |
760 | current->flags |= PF_SWAPWRITE; | |
761 | ||
e24f0b8f CL |
762 | for(pass = 0; pass < 10 && retry; pass++) { |
763 | retry = 0; | |
b20a3503 | 764 | |
e24f0b8f | 765 | list_for_each_entry_safe(page, page2, from, lru) { |
e24f0b8f | 766 | cond_resched(); |
2d1db3b1 | 767 | |
95a402c3 CL |
768 | rc = unmap_and_move(get_new_page, private, |
769 | page, pass > 2); | |
2d1db3b1 | 770 | |
e24f0b8f | 771 | switch(rc) { |
95a402c3 CL |
772 | case -ENOMEM: |
773 | goto out; | |
e24f0b8f | 774 | case -EAGAIN: |
2d1db3b1 | 775 | retry++; |
e24f0b8f CL |
776 | break; |
777 | case 0: | |
e24f0b8f CL |
778 | break; |
779 | default: | |
2d1db3b1 | 780 | /* Permanent failure */ |
2d1db3b1 | 781 | nr_failed++; |
e24f0b8f | 782 | break; |
2d1db3b1 | 783 | } |
b20a3503 CL |
784 | } |
785 | } | |
95a402c3 CL |
786 | rc = 0; |
787 | out: | |
b20a3503 CL |
788 | if (!swapwrite) |
789 | current->flags &= ~PF_SWAPWRITE; | |
790 | ||
aaa994b3 | 791 | putback_lru_pages(from); |
b20a3503 | 792 | |
95a402c3 CL |
793 | if (rc) |
794 | return rc; | |
b20a3503 | 795 | |
95a402c3 | 796 | return nr_failed + retry; |
b20a3503 | 797 | } |
95a402c3 | 798 | |
742755a1 CL |
799 | #ifdef CONFIG_NUMA |
800 | /* | |
801 | * Move a list of individual pages | |
802 | */ | |
803 | struct page_to_node { | |
804 | unsigned long addr; | |
805 | struct page *page; | |
806 | int node; | |
807 | int status; | |
808 | }; | |
809 | ||
810 | static struct page *new_page_node(struct page *p, unsigned long private, | |
811 | int **result) | |
812 | { | |
813 | struct page_to_node *pm = (struct page_to_node *)private; | |
814 | ||
815 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
816 | pm++; | |
817 | ||
818 | if (pm->node == MAX_NUMNODES) | |
819 | return NULL; | |
820 | ||
821 | *result = &pm->status; | |
822 | ||
769848c0 MG |
823 | return alloc_pages_node(pm->node, |
824 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); | |
742755a1 CL |
825 | } |
826 | ||
827 | /* | |
828 | * Move a set of pages as indicated in the pm array. The addr | |
829 | * field must be set to the virtual address of the page to be moved | |
830 | * and the node number must contain a valid target node. | |
831 | */ | |
832 | static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm, | |
833 | int migrate_all) | |
834 | { | |
835 | int err; | |
836 | struct page_to_node *pp; | |
837 | LIST_HEAD(pagelist); | |
838 | ||
839 | down_read(&mm->mmap_sem); | |
840 | ||
841 | /* | |
842 | * Build a list of pages to migrate | |
843 | */ | |
844 | migrate_prep(); | |
845 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { | |
846 | struct vm_area_struct *vma; | |
847 | struct page *page; | |
848 | ||
849 | /* | |
850 | * A valid page pointer that will not match any of the | |
851 | * pages that will be moved. | |
852 | */ | |
853 | pp->page = ZERO_PAGE(0); | |
854 | ||
855 | err = -EFAULT; | |
856 | vma = find_vma(mm, pp->addr); | |
0dc952dc | 857 | if (!vma || !vma_migratable(vma)) |
742755a1 CL |
858 | goto set_status; |
859 | ||
860 | page = follow_page(vma, pp->addr, FOLL_GET); | |
89f5b7da LT |
861 | |
862 | err = PTR_ERR(page); | |
863 | if (IS_ERR(page)) | |
864 | goto set_status; | |
865 | ||
742755a1 CL |
866 | err = -ENOENT; |
867 | if (!page) | |
868 | goto set_status; | |
869 | ||
870 | if (PageReserved(page)) /* Check for zero page */ | |
871 | goto put_and_set; | |
872 | ||
873 | pp->page = page; | |
874 | err = page_to_nid(page); | |
875 | ||
876 | if (err == pp->node) | |
877 | /* | |
878 | * Node already in the right place | |
879 | */ | |
880 | goto put_and_set; | |
881 | ||
882 | err = -EACCES; | |
883 | if (page_mapcount(page) > 1 && | |
884 | !migrate_all) | |
885 | goto put_and_set; | |
886 | ||
62695a84 NP |
887 | err = isolate_lru_page(page); |
888 | if (!err) | |
889 | list_add_tail(&page->lru, &pagelist); | |
742755a1 CL |
890 | put_and_set: |
891 | /* | |
892 | * Either remove the duplicate refcount from | |
893 | * isolate_lru_page() or drop the page ref if it was | |
894 | * not isolated. | |
895 | */ | |
896 | put_page(page); | |
897 | set_status: | |
898 | pp->status = err; | |
899 | } | |
900 | ||
901 | if (!list_empty(&pagelist)) | |
902 | err = migrate_pages(&pagelist, new_page_node, | |
903 | (unsigned long)pm); | |
904 | else | |
905 | err = -ENOENT; | |
906 | ||
907 | up_read(&mm->mmap_sem); | |
908 | return err; | |
909 | } | |
910 | ||
911 | /* | |
912 | * Determine the nodes of a list of pages. The addr in the pm array | |
913 | * must have been set to the virtual address of which we want to determine | |
914 | * the node number. | |
915 | */ | |
916 | static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm) | |
917 | { | |
918 | down_read(&mm->mmap_sem); | |
919 | ||
920 | for ( ; pm->node != MAX_NUMNODES; pm++) { | |
921 | struct vm_area_struct *vma; | |
922 | struct page *page; | |
923 | int err; | |
924 | ||
925 | err = -EFAULT; | |
926 | vma = find_vma(mm, pm->addr); | |
927 | if (!vma) | |
928 | goto set_status; | |
929 | ||
930 | page = follow_page(vma, pm->addr, 0); | |
89f5b7da LT |
931 | |
932 | err = PTR_ERR(page); | |
933 | if (IS_ERR(page)) | |
934 | goto set_status; | |
935 | ||
742755a1 CL |
936 | err = -ENOENT; |
937 | /* Use PageReserved to check for zero page */ | |
938 | if (!page || PageReserved(page)) | |
939 | goto set_status; | |
940 | ||
941 | err = page_to_nid(page); | |
942 | set_status: | |
943 | pm->status = err; | |
944 | } | |
945 | ||
946 | up_read(&mm->mmap_sem); | |
947 | return 0; | |
948 | } | |
949 | ||
950 | /* | |
951 | * Move a list of pages in the address space of the currently executing | |
952 | * process. | |
953 | */ | |
954 | asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages, | |
955 | const void __user * __user *pages, | |
956 | const int __user *nodes, | |
957 | int __user *status, int flags) | |
958 | { | |
959 | int err = 0; | |
960 | int i; | |
961 | struct task_struct *task; | |
962 | nodemask_t task_nodes; | |
963 | struct mm_struct *mm; | |
964 | struct page_to_node *pm = NULL; | |
965 | ||
966 | /* Check flags */ | |
967 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
968 | return -EINVAL; | |
969 | ||
970 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
971 | return -EPERM; | |
972 | ||
973 | /* Find the mm_struct */ | |
974 | read_lock(&tasklist_lock); | |
228ebcbe | 975 | task = pid ? find_task_by_vpid(pid) : current; |
742755a1 CL |
976 | if (!task) { |
977 | read_unlock(&tasklist_lock); | |
978 | return -ESRCH; | |
979 | } | |
980 | mm = get_task_mm(task); | |
981 | read_unlock(&tasklist_lock); | |
982 | ||
983 | if (!mm) | |
984 | return -EINVAL; | |
985 | ||
986 | /* | |
987 | * Check if this process has the right to modify the specified | |
988 | * process. The right exists if the process has administrative | |
989 | * capabilities, superuser privileges or the same | |
990 | * userid as the target process. | |
991 | */ | |
992 | if ((current->euid != task->suid) && (current->euid != task->uid) && | |
993 | (current->uid != task->suid) && (current->uid != task->uid) && | |
994 | !capable(CAP_SYS_NICE)) { | |
995 | err = -EPERM; | |
996 | goto out2; | |
997 | } | |
998 | ||
86c3a764 DQ |
999 | err = security_task_movememory(task); |
1000 | if (err) | |
1001 | goto out2; | |
1002 | ||
1003 | ||
742755a1 CL |
1004 | task_nodes = cpuset_mems_allowed(task); |
1005 | ||
1006 | /* Limit nr_pages so that the multiplication may not overflow */ | |
1007 | if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) { | |
1008 | err = -E2BIG; | |
1009 | goto out2; | |
1010 | } | |
1011 | ||
1012 | pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node)); | |
1013 | if (!pm) { | |
1014 | err = -ENOMEM; | |
1015 | goto out2; | |
1016 | } | |
1017 | ||
1018 | /* | |
1019 | * Get parameters from user space and initialize the pm | |
1020 | * array. Return various errors if the user did something wrong. | |
1021 | */ | |
1022 | for (i = 0; i < nr_pages; i++) { | |
9d966d49 | 1023 | const void __user *p; |
742755a1 CL |
1024 | |
1025 | err = -EFAULT; | |
1026 | if (get_user(p, pages + i)) | |
1027 | goto out; | |
1028 | ||
1029 | pm[i].addr = (unsigned long)p; | |
1030 | if (nodes) { | |
1031 | int node; | |
1032 | ||
1033 | if (get_user(node, nodes + i)) | |
1034 | goto out; | |
1035 | ||
1036 | err = -ENODEV; | |
56bbd65d | 1037 | if (!node_state(node, N_HIGH_MEMORY)) |
742755a1 CL |
1038 | goto out; |
1039 | ||
1040 | err = -EACCES; | |
1041 | if (!node_isset(node, task_nodes)) | |
1042 | goto out; | |
1043 | ||
1044 | pm[i].node = node; | |
8ce08464 SR |
1045 | } else |
1046 | pm[i].node = 0; /* anything to not match MAX_NUMNODES */ | |
742755a1 CL |
1047 | } |
1048 | /* End marker */ | |
1049 | pm[nr_pages].node = MAX_NUMNODES; | |
1050 | ||
1051 | if (nodes) | |
1052 | err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL); | |
1053 | else | |
1054 | err = do_pages_stat(mm, pm); | |
1055 | ||
1056 | if (err >= 0) | |
1057 | /* Return status information */ | |
1058 | for (i = 0; i < nr_pages; i++) | |
1059 | if (put_user(pm[i].status, status + i)) | |
1060 | err = -EFAULT; | |
1061 | ||
1062 | out: | |
1063 | vfree(pm); | |
1064 | out2: | |
1065 | mmput(mm); | |
1066 | return err; | |
1067 | } | |
742755a1 | 1068 | |
7b2259b3 CL |
1069 | /* |
1070 | * Call migration functions in the vma_ops that may prepare | |
1071 | * memory in a vm for migration. migration functions may perform | |
1072 | * the migration for vmas that do not have an underlying page struct. | |
1073 | */ | |
1074 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1075 | const nodemask_t *from, unsigned long flags) | |
1076 | { | |
1077 | struct vm_area_struct *vma; | |
1078 | int err = 0; | |
1079 | ||
1080 | for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) { | |
1081 | if (vma->vm_ops && vma->vm_ops->migrate) { | |
1082 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1083 | if (err) | |
1084 | break; | |
1085 | } | |
1086 | } | |
1087 | return err; | |
1088 | } | |
83d1674a | 1089 | #endif |