Commit | Line | Data |
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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> | |
12 | * Christoph Lameter <clameter@sgi.com> | |
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> |
b20a3503 CL |
33 | |
34 | #include "internal.h" | |
35 | ||
b20a3503 CL |
36 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
37 | ||
38 | /* | |
39 | * Isolate one page from the LRU lists. If successful put it onto | |
40 | * the indicated list with elevated page count. | |
41 | * | |
42 | * Result: | |
43 | * -EBUSY: page not on LRU list | |
44 | * 0: page removed from LRU list and added to the specified list. | |
45 | */ | |
46 | int isolate_lru_page(struct page *page, struct list_head *pagelist) | |
47 | { | |
48 | int ret = -EBUSY; | |
49 | ||
50 | if (PageLRU(page)) { | |
51 | struct zone *zone = page_zone(page); | |
52 | ||
53 | spin_lock_irq(&zone->lru_lock); | |
3dd9fe8c | 54 | if (PageLRU(page) && get_page_unless_zero(page)) { |
b20a3503 | 55 | ret = 0; |
b20a3503 CL |
56 | ClearPageLRU(page); |
57 | if (PageActive(page)) | |
58 | del_page_from_active_list(zone, page); | |
59 | else | |
60 | del_page_from_inactive_list(zone, page); | |
61 | list_add_tail(&page->lru, pagelist); | |
62 | } | |
63 | spin_unlock_irq(&zone->lru_lock); | |
64 | } | |
65 | return ret; | |
66 | } | |
67 | ||
68 | /* | |
742755a1 CL |
69 | * migrate_prep() needs to be called before we start compiling a list of pages |
70 | * to be migrated using isolate_lru_page(). | |
b20a3503 CL |
71 | */ |
72 | int migrate_prep(void) | |
73 | { | |
b20a3503 CL |
74 | /* |
75 | * Clear the LRU lists so pages can be isolated. | |
76 | * Note that pages may be moved off the LRU after we have | |
77 | * drained them. Those pages will fail to migrate like other | |
78 | * pages that may be busy. | |
79 | */ | |
80 | lru_add_drain_all(); | |
81 | ||
82 | return 0; | |
83 | } | |
84 | ||
85 | static inline void move_to_lru(struct page *page) | |
86 | { | |
b20a3503 CL |
87 | if (PageActive(page)) { |
88 | /* | |
89 | * lru_cache_add_active checks that | |
90 | * the PG_active bit is off. | |
91 | */ | |
92 | ClearPageActive(page); | |
93 | lru_cache_add_active(page); | |
94 | } else { | |
95 | lru_cache_add(page); | |
96 | } | |
97 | put_page(page); | |
98 | } | |
99 | ||
100 | /* | |
101 | * Add isolated pages on the list back to the LRU. | |
102 | * | |
103 | * returns the number of pages put back. | |
104 | */ | |
105 | int putback_lru_pages(struct list_head *l) | |
106 | { | |
107 | struct page *page; | |
108 | struct page *page2; | |
109 | int count = 0; | |
110 | ||
111 | list_for_each_entry_safe(page, page2, l, lru) { | |
e24f0b8f | 112 | list_del(&page->lru); |
b20a3503 CL |
113 | move_to_lru(page); |
114 | count++; | |
115 | } | |
116 | return count; | |
117 | } | |
118 | ||
0697212a CL |
119 | /* |
120 | * Restore a potential migration pte to a working pte entry | |
121 | */ | |
04e62a29 | 122 | static void remove_migration_pte(struct vm_area_struct *vma, |
0697212a CL |
123 | struct page *old, struct page *new) |
124 | { | |
125 | struct mm_struct *mm = vma->vm_mm; | |
126 | swp_entry_t entry; | |
127 | pgd_t *pgd; | |
128 | pud_t *pud; | |
129 | pmd_t *pmd; | |
130 | pte_t *ptep, pte; | |
131 | spinlock_t *ptl; | |
04e62a29 CL |
132 | unsigned long addr = page_address_in_vma(new, vma); |
133 | ||
134 | if (addr == -EFAULT) | |
135 | return; | |
0697212a CL |
136 | |
137 | pgd = pgd_offset(mm, addr); | |
138 | if (!pgd_present(*pgd)) | |
139 | return; | |
140 | ||
141 | pud = pud_offset(pgd, addr); | |
142 | if (!pud_present(*pud)) | |
143 | return; | |
144 | ||
145 | pmd = pmd_offset(pud, addr); | |
146 | if (!pmd_present(*pmd)) | |
147 | return; | |
148 | ||
149 | ptep = pte_offset_map(pmd, addr); | |
150 | ||
151 | if (!is_swap_pte(*ptep)) { | |
152 | pte_unmap(ptep); | |
153 | return; | |
154 | } | |
155 | ||
156 | ptl = pte_lockptr(mm, pmd); | |
157 | spin_lock(ptl); | |
158 | pte = *ptep; | |
159 | if (!is_swap_pte(pte)) | |
160 | goto out; | |
161 | ||
162 | entry = pte_to_swp_entry(pte); | |
163 | ||
164 | if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) | |
165 | goto out; | |
166 | ||
98837c7f HD |
167 | /* |
168 | * Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge. | |
169 | * Failure is not an option here: we're now expected to remove every | |
170 | * migration pte, and will cause crashes otherwise. Normally this | |
171 | * is not an issue: mem_cgroup_prepare_migration bumped up the old | |
172 | * page_cgroup count for safety, that's now attached to the new page, | |
173 | * so this charge should just be another incrementation of the count, | |
174 | * to keep in balance with rmap.c's mem_cgroup_uncharging. But if | |
175 | * there's been a force_empty, those reference counts may no longer | |
176 | * be reliable, and this charge can actually fail: oh well, we don't | |
177 | * make the situation any worse by proceeding as if it had succeeded. | |
178 | */ | |
179 | mem_cgroup_charge(new, mm, GFP_ATOMIC); | |
180 | ||
0697212a CL |
181 | get_page(new); |
182 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
183 | if (is_write_migration_entry(entry)) | |
184 | pte = pte_mkwrite(pte); | |
97ee0524 | 185 | flush_cache_page(vma, addr, pte_pfn(pte)); |
0697212a | 186 | set_pte_at(mm, addr, ptep, pte); |
04e62a29 CL |
187 | |
188 | if (PageAnon(new)) | |
189 | page_add_anon_rmap(new, vma, addr); | |
190 | else | |
191 | page_add_file_rmap(new); | |
192 | ||
193 | /* No need to invalidate - it was non-present before */ | |
194 | update_mmu_cache(vma, addr, pte); | |
04e62a29 | 195 | |
0697212a CL |
196 | out: |
197 | pte_unmap_unlock(ptep, ptl); | |
198 | } | |
199 | ||
200 | /* | |
04e62a29 CL |
201 | * Note that remove_file_migration_ptes will only work on regular mappings, |
202 | * Nonlinear mappings do not use migration entries. | |
203 | */ | |
204 | static void remove_file_migration_ptes(struct page *old, struct page *new) | |
205 | { | |
206 | struct vm_area_struct *vma; | |
207 | struct address_space *mapping = page_mapping(new); | |
208 | struct prio_tree_iter iter; | |
209 | pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
210 | ||
211 | if (!mapping) | |
212 | return; | |
213 | ||
214 | spin_lock(&mapping->i_mmap_lock); | |
215 | ||
216 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) | |
217 | remove_migration_pte(vma, old, new); | |
218 | ||
219 | spin_unlock(&mapping->i_mmap_lock); | |
220 | } | |
221 | ||
222 | /* | |
0697212a CL |
223 | * Must hold mmap_sem lock on at least one of the vmas containing |
224 | * the page so that the anon_vma cannot vanish. | |
225 | */ | |
04e62a29 | 226 | static void remove_anon_migration_ptes(struct page *old, struct page *new) |
0697212a CL |
227 | { |
228 | struct anon_vma *anon_vma; | |
229 | struct vm_area_struct *vma; | |
230 | unsigned long mapping; | |
231 | ||
232 | mapping = (unsigned long)new->mapping; | |
233 | ||
234 | if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) | |
235 | return; | |
236 | ||
237 | /* | |
238 | * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. | |
239 | */ | |
240 | anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); | |
241 | spin_lock(&anon_vma->lock); | |
242 | ||
243 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) | |
04e62a29 | 244 | remove_migration_pte(vma, old, new); |
0697212a CL |
245 | |
246 | spin_unlock(&anon_vma->lock); | |
247 | } | |
248 | ||
04e62a29 CL |
249 | /* |
250 | * Get rid of all migration entries and replace them by | |
251 | * references to the indicated page. | |
252 | */ | |
253 | static void remove_migration_ptes(struct page *old, struct page *new) | |
254 | { | |
255 | if (PageAnon(new)) | |
256 | remove_anon_migration_ptes(old, new); | |
257 | else | |
258 | remove_file_migration_ptes(old, new); | |
259 | } | |
260 | ||
0697212a CL |
261 | /* |
262 | * Something used the pte of a page under migration. We need to | |
263 | * get to the page and wait until migration is finished. | |
264 | * When we return from this function the fault will be retried. | |
265 | * | |
266 | * This function is called from do_swap_page(). | |
267 | */ | |
268 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
269 | unsigned long address) | |
270 | { | |
271 | pte_t *ptep, pte; | |
272 | spinlock_t *ptl; | |
273 | swp_entry_t entry; | |
274 | struct page *page; | |
275 | ||
276 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
277 | pte = *ptep; | |
278 | if (!is_swap_pte(pte)) | |
279 | goto out; | |
280 | ||
281 | entry = pte_to_swp_entry(pte); | |
282 | if (!is_migration_entry(entry)) | |
283 | goto out; | |
284 | ||
285 | page = migration_entry_to_page(entry); | |
286 | ||
287 | get_page(page); | |
288 | pte_unmap_unlock(ptep, ptl); | |
289 | wait_on_page_locked(page); | |
290 | put_page(page); | |
291 | return; | |
292 | out: | |
293 | pte_unmap_unlock(ptep, ptl); | |
294 | } | |
295 | ||
b20a3503 | 296 | /* |
c3fcf8a5 | 297 | * Replace the page in the mapping. |
5b5c7120 CL |
298 | * |
299 | * The number of remaining references must be: | |
300 | * 1 for anonymous pages without a mapping | |
301 | * 2 for pages with a mapping | |
302 | * 3 for pages with a mapping and PagePrivate set. | |
b20a3503 | 303 | */ |
2d1db3b1 CL |
304 | static int migrate_page_move_mapping(struct address_space *mapping, |
305 | struct page *newpage, struct page *page) | |
b20a3503 | 306 | { |
7cf9c2c7 | 307 | void **pslot; |
b20a3503 | 308 | |
6c5240ae | 309 | if (!mapping) { |
0e8c7d0f | 310 | /* Anonymous page without mapping */ |
6c5240ae CL |
311 | if (page_count(page) != 1) |
312 | return -EAGAIN; | |
313 | return 0; | |
314 | } | |
315 | ||
b20a3503 CL |
316 | write_lock_irq(&mapping->tree_lock); |
317 | ||
7cf9c2c7 NP |
318 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
319 | page_index(page)); | |
b20a3503 | 320 | |
6c5240ae | 321 | if (page_count(page) != 2 + !!PagePrivate(page) || |
7cf9c2c7 | 322 | (struct page *)radix_tree_deref_slot(pslot) != page) { |
b20a3503 | 323 | write_unlock_irq(&mapping->tree_lock); |
e23ca00b | 324 | return -EAGAIN; |
b20a3503 CL |
325 | } |
326 | ||
327 | /* | |
328 | * Now we know that no one else is looking at the page. | |
b20a3503 | 329 | */ |
7cf9c2c7 | 330 | get_page(newpage); /* add cache reference */ |
6c5240ae | 331 | #ifdef CONFIG_SWAP |
b20a3503 CL |
332 | if (PageSwapCache(page)) { |
333 | SetPageSwapCache(newpage); | |
334 | set_page_private(newpage, page_private(page)); | |
335 | } | |
6c5240ae | 336 | #endif |
b20a3503 | 337 | |
7cf9c2c7 NP |
338 | radix_tree_replace_slot(pslot, newpage); |
339 | ||
340 | /* | |
341 | * Drop cache reference from old page. | |
342 | * We know this isn't the last reference. | |
343 | */ | |
b20a3503 | 344 | __put_page(page); |
7cf9c2c7 | 345 | |
0e8c7d0f CL |
346 | /* |
347 | * If moved to a different zone then also account | |
348 | * the page for that zone. Other VM counters will be | |
349 | * taken care of when we establish references to the | |
350 | * new page and drop references to the old page. | |
351 | * | |
352 | * Note that anonymous pages are accounted for | |
353 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
354 | * are mapped to swap space. | |
355 | */ | |
356 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
357 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
358 | ||
b20a3503 CL |
359 | write_unlock_irq(&mapping->tree_lock); |
360 | ||
361 | return 0; | |
362 | } | |
b20a3503 CL |
363 | |
364 | /* | |
365 | * Copy the page to its new location | |
366 | */ | |
e7340f73 | 367 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 CL |
368 | { |
369 | copy_highpage(newpage, page); | |
370 | ||
371 | if (PageError(page)) | |
372 | SetPageError(newpage); | |
373 | if (PageReferenced(page)) | |
374 | SetPageReferenced(newpage); | |
375 | if (PageUptodate(page)) | |
376 | SetPageUptodate(newpage); | |
377 | if (PageActive(page)) | |
378 | SetPageActive(newpage); | |
379 | if (PageChecked(page)) | |
380 | SetPageChecked(newpage); | |
381 | if (PageMappedToDisk(page)) | |
382 | SetPageMappedToDisk(newpage); | |
383 | ||
384 | if (PageDirty(page)) { | |
385 | clear_page_dirty_for_io(page); | |
386 | set_page_dirty(newpage); | |
387 | } | |
388 | ||
6c5240ae | 389 | #ifdef CONFIG_SWAP |
b20a3503 | 390 | ClearPageSwapCache(page); |
6c5240ae | 391 | #endif |
b20a3503 CL |
392 | ClearPageActive(page); |
393 | ClearPagePrivate(page); | |
394 | set_page_private(page, 0); | |
395 | page->mapping = NULL; | |
396 | ||
397 | /* | |
398 | * If any waiters have accumulated on the new page then | |
399 | * wake them up. | |
400 | */ | |
401 | if (PageWriteback(newpage)) | |
402 | end_page_writeback(newpage); | |
403 | } | |
b20a3503 | 404 | |
1d8b85cc CL |
405 | /************************************************************ |
406 | * Migration functions | |
407 | ***********************************************************/ | |
408 | ||
409 | /* Always fail migration. Used for mappings that are not movable */ | |
2d1db3b1 CL |
410 | int fail_migrate_page(struct address_space *mapping, |
411 | struct page *newpage, struct page *page) | |
1d8b85cc CL |
412 | { |
413 | return -EIO; | |
414 | } | |
415 | EXPORT_SYMBOL(fail_migrate_page); | |
416 | ||
b20a3503 CL |
417 | /* |
418 | * Common logic to directly migrate a single page suitable for | |
419 | * pages that do not use PagePrivate. | |
420 | * | |
421 | * Pages are locked upon entry and exit. | |
422 | */ | |
2d1db3b1 CL |
423 | int migrate_page(struct address_space *mapping, |
424 | struct page *newpage, struct page *page) | |
b20a3503 CL |
425 | { |
426 | int rc; | |
427 | ||
428 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
429 | ||
2d1db3b1 | 430 | rc = migrate_page_move_mapping(mapping, newpage, page); |
b20a3503 CL |
431 | |
432 | if (rc) | |
433 | return rc; | |
434 | ||
435 | migrate_page_copy(newpage, page); | |
b20a3503 CL |
436 | return 0; |
437 | } | |
438 | EXPORT_SYMBOL(migrate_page); | |
439 | ||
9361401e | 440 | #ifdef CONFIG_BLOCK |
1d8b85cc CL |
441 | /* |
442 | * Migration function for pages with buffers. This function can only be used | |
443 | * if the underlying filesystem guarantees that no other references to "page" | |
444 | * exist. | |
445 | */ | |
2d1db3b1 CL |
446 | int buffer_migrate_page(struct address_space *mapping, |
447 | struct page *newpage, struct page *page) | |
1d8b85cc | 448 | { |
1d8b85cc CL |
449 | struct buffer_head *bh, *head; |
450 | int rc; | |
451 | ||
1d8b85cc | 452 | if (!page_has_buffers(page)) |
2d1db3b1 | 453 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
454 | |
455 | head = page_buffers(page); | |
456 | ||
2d1db3b1 | 457 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
458 | |
459 | if (rc) | |
460 | return rc; | |
461 | ||
462 | bh = head; | |
463 | do { | |
464 | get_bh(bh); | |
465 | lock_buffer(bh); | |
466 | bh = bh->b_this_page; | |
467 | ||
468 | } while (bh != head); | |
469 | ||
470 | ClearPagePrivate(page); | |
471 | set_page_private(newpage, page_private(page)); | |
472 | set_page_private(page, 0); | |
473 | put_page(page); | |
474 | get_page(newpage); | |
475 | ||
476 | bh = head; | |
477 | do { | |
478 | set_bh_page(bh, newpage, bh_offset(bh)); | |
479 | bh = bh->b_this_page; | |
480 | ||
481 | } while (bh != head); | |
482 | ||
483 | SetPagePrivate(newpage); | |
484 | ||
485 | migrate_page_copy(newpage, page); | |
486 | ||
487 | bh = head; | |
488 | do { | |
489 | unlock_buffer(bh); | |
490 | put_bh(bh); | |
491 | bh = bh->b_this_page; | |
492 | ||
493 | } while (bh != head); | |
494 | ||
495 | return 0; | |
496 | } | |
497 | EXPORT_SYMBOL(buffer_migrate_page); | |
9361401e | 498 | #endif |
1d8b85cc | 499 | |
04e62a29 CL |
500 | /* |
501 | * Writeback a page to clean the dirty state | |
502 | */ | |
503 | static int writeout(struct address_space *mapping, struct page *page) | |
8351a6e4 | 504 | { |
04e62a29 CL |
505 | struct writeback_control wbc = { |
506 | .sync_mode = WB_SYNC_NONE, | |
507 | .nr_to_write = 1, | |
508 | .range_start = 0, | |
509 | .range_end = LLONG_MAX, | |
510 | .nonblocking = 1, | |
511 | .for_reclaim = 1 | |
512 | }; | |
513 | int rc; | |
514 | ||
515 | if (!mapping->a_ops->writepage) | |
516 | /* No write method for the address space */ | |
517 | return -EINVAL; | |
518 | ||
519 | if (!clear_page_dirty_for_io(page)) | |
520 | /* Someone else already triggered a write */ | |
521 | return -EAGAIN; | |
522 | ||
8351a6e4 | 523 | /* |
04e62a29 CL |
524 | * A dirty page may imply that the underlying filesystem has |
525 | * the page on some queue. So the page must be clean for | |
526 | * migration. Writeout may mean we loose the lock and the | |
527 | * page state is no longer what we checked for earlier. | |
528 | * At this point we know that the migration attempt cannot | |
529 | * be successful. | |
8351a6e4 | 530 | */ |
04e62a29 | 531 | remove_migration_ptes(page, page); |
8351a6e4 | 532 | |
04e62a29 CL |
533 | rc = mapping->a_ops->writepage(page, &wbc); |
534 | if (rc < 0) | |
535 | /* I/O Error writing */ | |
536 | return -EIO; | |
8351a6e4 | 537 | |
04e62a29 CL |
538 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
539 | /* unlocked. Relock */ | |
540 | lock_page(page); | |
541 | ||
542 | return -EAGAIN; | |
543 | } | |
544 | ||
545 | /* | |
546 | * Default handling if a filesystem does not provide a migration function. | |
547 | */ | |
548 | static int fallback_migrate_page(struct address_space *mapping, | |
549 | struct page *newpage, struct page *page) | |
550 | { | |
551 | if (PageDirty(page)) | |
552 | return writeout(mapping, page); | |
8351a6e4 CL |
553 | |
554 | /* | |
555 | * Buffers may be managed in a filesystem specific way. | |
556 | * We must have no buffers or drop them. | |
557 | */ | |
b398f6bf | 558 | if (PagePrivate(page) && |
8351a6e4 CL |
559 | !try_to_release_page(page, GFP_KERNEL)) |
560 | return -EAGAIN; | |
561 | ||
562 | return migrate_page(mapping, newpage, page); | |
563 | } | |
564 | ||
e24f0b8f CL |
565 | /* |
566 | * Move a page to a newly allocated page | |
567 | * The page is locked and all ptes have been successfully removed. | |
568 | * | |
569 | * The new page will have replaced the old page if this function | |
570 | * is successful. | |
571 | */ | |
572 | static int move_to_new_page(struct page *newpage, struct page *page) | |
573 | { | |
574 | struct address_space *mapping; | |
575 | int rc; | |
576 | ||
577 | /* | |
578 | * Block others from accessing the page when we get around to | |
579 | * establishing additional references. We are the only one | |
580 | * holding a reference to the new page at this point. | |
581 | */ | |
582 | if (TestSetPageLocked(newpage)) | |
583 | BUG(); | |
584 | ||
585 | /* Prepare mapping for the new page.*/ | |
586 | newpage->index = page->index; | |
587 | newpage->mapping = page->mapping; | |
588 | ||
589 | mapping = page_mapping(page); | |
590 | if (!mapping) | |
591 | rc = migrate_page(mapping, newpage, page); | |
592 | else if (mapping->a_ops->migratepage) | |
593 | /* | |
594 | * Most pages have a mapping and most filesystems | |
595 | * should provide a migration function. Anonymous | |
596 | * pages are part of swap space which also has its | |
597 | * own migration function. This is the most common | |
598 | * path for page migration. | |
599 | */ | |
600 | rc = mapping->a_ops->migratepage(mapping, | |
601 | newpage, page); | |
602 | else | |
603 | rc = fallback_migrate_page(mapping, newpage, page); | |
604 | ||
ae41be37 KH |
605 | if (!rc) { |
606 | mem_cgroup_page_migration(page, newpage); | |
e24f0b8f | 607 | remove_migration_ptes(page, newpage); |
ae41be37 | 608 | } else |
e24f0b8f CL |
609 | newpage->mapping = NULL; |
610 | ||
611 | unlock_page(newpage); | |
612 | ||
613 | return rc; | |
614 | } | |
615 | ||
616 | /* | |
617 | * Obtain the lock on page, remove all ptes and migrate the page | |
618 | * to the newly allocated page in newpage. | |
619 | */ | |
95a402c3 CL |
620 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
621 | struct page *page, int force) | |
e24f0b8f CL |
622 | { |
623 | int rc = 0; | |
742755a1 CL |
624 | int *result = NULL; |
625 | struct page *newpage = get_new_page(page, private, &result); | |
989f89c5 | 626 | int rcu_locked = 0; |
ae41be37 | 627 | int charge = 0; |
95a402c3 CL |
628 | |
629 | if (!newpage) | |
630 | return -ENOMEM; | |
e24f0b8f CL |
631 | |
632 | if (page_count(page) == 1) | |
633 | /* page was freed from under us. So we are done. */ | |
95a402c3 | 634 | goto move_newpage; |
e24f0b8f CL |
635 | |
636 | rc = -EAGAIN; | |
637 | if (TestSetPageLocked(page)) { | |
638 | if (!force) | |
95a402c3 | 639 | goto move_newpage; |
e24f0b8f CL |
640 | lock_page(page); |
641 | } | |
642 | ||
643 | if (PageWriteback(page)) { | |
644 | if (!force) | |
645 | goto unlock; | |
646 | wait_on_page_writeback(page); | |
647 | } | |
e24f0b8f | 648 | /* |
dc386d4d KH |
649 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
650 | * we cannot notice that anon_vma is freed while we migrates a page. | |
651 | * This rcu_read_lock() delays freeing anon_vma pointer until the end | |
652 | * of migration. File cache pages are no problem because of page_lock() | |
989f89c5 KH |
653 | * File Caches may use write_page() or lock_page() in migration, then, |
654 | * just care Anon page here. | |
dc386d4d | 655 | */ |
989f89c5 KH |
656 | if (PageAnon(page)) { |
657 | rcu_read_lock(); | |
658 | rcu_locked = 1; | |
659 | } | |
62e1c553 | 660 | |
dc386d4d | 661 | /* |
62e1c553 SL |
662 | * Corner case handling: |
663 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
664 | * and treated as swapcache but it has no rmap yet. | |
665 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
666 | * trigger a BUG. So handle it here. | |
667 | * 2. An orphaned page (see truncate_complete_page) might have | |
668 | * fs-private metadata. The page can be picked up due to memory | |
669 | * offlining. Everywhere else except page reclaim, the page is | |
670 | * invisible to the vm, so the page can not be migrated. So try to | |
671 | * free the metadata, so the page can be freed. | |
e24f0b8f | 672 | */ |
62e1c553 SL |
673 | if (!page->mapping) { |
674 | if (!PageAnon(page) && PagePrivate(page)) { | |
675 | /* | |
676 | * Go direct to try_to_free_buffers() here because | |
677 | * a) that's what try_to_release_page() would do anyway | |
678 | * b) we may be under rcu_read_lock() here, so we can't | |
679 | * use GFP_KERNEL which is what try_to_release_page() | |
680 | * needs to be effective. | |
681 | */ | |
682 | try_to_free_buffers(page); | |
683 | } | |
dc386d4d | 684 | goto rcu_unlock; |
62e1c553 SL |
685 | } |
686 | ||
ae41be37 | 687 | charge = mem_cgroup_prepare_migration(page); |
dc386d4d | 688 | /* Establish migration ptes or remove ptes */ |
e6a1530d | 689 | try_to_unmap(page, 1); |
dc386d4d | 690 | |
e6a1530d CL |
691 | if (!page_mapped(page)) |
692 | rc = move_to_new_page(newpage, page); | |
e24f0b8f | 693 | |
ae41be37 | 694 | if (rc) { |
e24f0b8f | 695 | remove_migration_ptes(page, page); |
ae41be37 KH |
696 | if (charge) |
697 | mem_cgroup_end_migration(page); | |
698 | } else if (charge) | |
699 | mem_cgroup_end_migration(newpage); | |
dc386d4d | 700 | rcu_unlock: |
989f89c5 KH |
701 | if (rcu_locked) |
702 | rcu_read_unlock(); | |
e6a1530d | 703 | |
e24f0b8f | 704 | unlock: |
dc386d4d | 705 | |
e24f0b8f | 706 | unlock_page(page); |
95a402c3 | 707 | |
e24f0b8f | 708 | if (rc != -EAGAIN) { |
aaa994b3 CL |
709 | /* |
710 | * A page that has been migrated has all references | |
711 | * removed and will be freed. A page that has not been | |
712 | * migrated will have kepts its references and be | |
713 | * restored. | |
714 | */ | |
715 | list_del(&page->lru); | |
716 | move_to_lru(page); | |
e24f0b8f | 717 | } |
95a402c3 CL |
718 | |
719 | move_newpage: | |
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); | |
861 | err = -ENOENT; | |
862 | if (!page) | |
863 | goto set_status; | |
864 | ||
865 | if (PageReserved(page)) /* Check for zero page */ | |
866 | goto put_and_set; | |
867 | ||
868 | pp->page = page; | |
869 | err = page_to_nid(page); | |
870 | ||
871 | if (err == pp->node) | |
872 | /* | |
873 | * Node already in the right place | |
874 | */ | |
875 | goto put_and_set; | |
876 | ||
877 | err = -EACCES; | |
878 | if (page_mapcount(page) > 1 && | |
879 | !migrate_all) | |
880 | goto put_and_set; | |
881 | ||
882 | err = isolate_lru_page(page, &pagelist); | |
883 | put_and_set: | |
884 | /* | |
885 | * Either remove the duplicate refcount from | |
886 | * isolate_lru_page() or drop the page ref if it was | |
887 | * not isolated. | |
888 | */ | |
889 | put_page(page); | |
890 | set_status: | |
891 | pp->status = err; | |
892 | } | |
893 | ||
894 | if (!list_empty(&pagelist)) | |
895 | err = migrate_pages(&pagelist, new_page_node, | |
896 | (unsigned long)pm); | |
897 | else | |
898 | err = -ENOENT; | |
899 | ||
900 | up_read(&mm->mmap_sem); | |
901 | return err; | |
902 | } | |
903 | ||
904 | /* | |
905 | * Determine the nodes of a list of pages. The addr in the pm array | |
906 | * must have been set to the virtual address of which we want to determine | |
907 | * the node number. | |
908 | */ | |
909 | static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm) | |
910 | { | |
911 | down_read(&mm->mmap_sem); | |
912 | ||
913 | for ( ; pm->node != MAX_NUMNODES; pm++) { | |
914 | struct vm_area_struct *vma; | |
915 | struct page *page; | |
916 | int err; | |
917 | ||
918 | err = -EFAULT; | |
919 | vma = find_vma(mm, pm->addr); | |
920 | if (!vma) | |
921 | goto set_status; | |
922 | ||
923 | page = follow_page(vma, pm->addr, 0); | |
924 | err = -ENOENT; | |
925 | /* Use PageReserved to check for zero page */ | |
926 | if (!page || PageReserved(page)) | |
927 | goto set_status; | |
928 | ||
929 | err = page_to_nid(page); | |
930 | set_status: | |
931 | pm->status = err; | |
932 | } | |
933 | ||
934 | up_read(&mm->mmap_sem); | |
935 | return 0; | |
936 | } | |
937 | ||
938 | /* | |
939 | * Move a list of pages in the address space of the currently executing | |
940 | * process. | |
941 | */ | |
942 | asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages, | |
943 | const void __user * __user *pages, | |
944 | const int __user *nodes, | |
945 | int __user *status, int flags) | |
946 | { | |
947 | int err = 0; | |
948 | int i; | |
949 | struct task_struct *task; | |
950 | nodemask_t task_nodes; | |
951 | struct mm_struct *mm; | |
952 | struct page_to_node *pm = NULL; | |
953 | ||
954 | /* Check flags */ | |
955 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
956 | return -EINVAL; | |
957 | ||
958 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
959 | return -EPERM; | |
960 | ||
961 | /* Find the mm_struct */ | |
962 | read_lock(&tasklist_lock); | |
228ebcbe | 963 | task = pid ? find_task_by_vpid(pid) : current; |
742755a1 CL |
964 | if (!task) { |
965 | read_unlock(&tasklist_lock); | |
966 | return -ESRCH; | |
967 | } | |
968 | mm = get_task_mm(task); | |
969 | read_unlock(&tasklist_lock); | |
970 | ||
971 | if (!mm) | |
972 | return -EINVAL; | |
973 | ||
974 | /* | |
975 | * Check if this process has the right to modify the specified | |
976 | * process. The right exists if the process has administrative | |
977 | * capabilities, superuser privileges or the same | |
978 | * userid as the target process. | |
979 | */ | |
980 | if ((current->euid != task->suid) && (current->euid != task->uid) && | |
981 | (current->uid != task->suid) && (current->uid != task->uid) && | |
982 | !capable(CAP_SYS_NICE)) { | |
983 | err = -EPERM; | |
984 | goto out2; | |
985 | } | |
986 | ||
86c3a764 DQ |
987 | err = security_task_movememory(task); |
988 | if (err) | |
989 | goto out2; | |
990 | ||
991 | ||
742755a1 CL |
992 | task_nodes = cpuset_mems_allowed(task); |
993 | ||
994 | /* Limit nr_pages so that the multiplication may not overflow */ | |
995 | if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) { | |
996 | err = -E2BIG; | |
997 | goto out2; | |
998 | } | |
999 | ||
1000 | pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node)); | |
1001 | if (!pm) { | |
1002 | err = -ENOMEM; | |
1003 | goto out2; | |
1004 | } | |
1005 | ||
1006 | /* | |
1007 | * Get parameters from user space and initialize the pm | |
1008 | * array. Return various errors if the user did something wrong. | |
1009 | */ | |
1010 | for (i = 0; i < nr_pages; i++) { | |
9d966d49 | 1011 | const void __user *p; |
742755a1 CL |
1012 | |
1013 | err = -EFAULT; | |
1014 | if (get_user(p, pages + i)) | |
1015 | goto out; | |
1016 | ||
1017 | pm[i].addr = (unsigned long)p; | |
1018 | if (nodes) { | |
1019 | int node; | |
1020 | ||
1021 | if (get_user(node, nodes + i)) | |
1022 | goto out; | |
1023 | ||
1024 | err = -ENODEV; | |
56bbd65d | 1025 | if (!node_state(node, N_HIGH_MEMORY)) |
742755a1 CL |
1026 | goto out; |
1027 | ||
1028 | err = -EACCES; | |
1029 | if (!node_isset(node, task_nodes)) | |
1030 | goto out; | |
1031 | ||
1032 | pm[i].node = node; | |
8ce08464 SR |
1033 | } else |
1034 | pm[i].node = 0; /* anything to not match MAX_NUMNODES */ | |
742755a1 CL |
1035 | } |
1036 | /* End marker */ | |
1037 | pm[nr_pages].node = MAX_NUMNODES; | |
1038 | ||
1039 | if (nodes) | |
1040 | err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL); | |
1041 | else | |
1042 | err = do_pages_stat(mm, pm); | |
1043 | ||
1044 | if (err >= 0) | |
1045 | /* Return status information */ | |
1046 | for (i = 0; i < nr_pages; i++) | |
1047 | if (put_user(pm[i].status, status + i)) | |
1048 | err = -EFAULT; | |
1049 | ||
1050 | out: | |
1051 | vfree(pm); | |
1052 | out2: | |
1053 | mmput(mm); | |
1054 | return err; | |
1055 | } | |
1056 | #endif | |
1057 | ||
7b2259b3 CL |
1058 | /* |
1059 | * Call migration functions in the vma_ops that may prepare | |
1060 | * memory in a vm for migration. migration functions may perform | |
1061 | * the migration for vmas that do not have an underlying page struct. | |
1062 | */ | |
1063 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1064 | const nodemask_t *from, unsigned long flags) | |
1065 | { | |
1066 | struct vm_area_struct *vma; | |
1067 | int err = 0; | |
1068 | ||
1069 | for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) { | |
1070 | if (vma->vm_ops && vma->vm_ops->migrate) { | |
1071 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1072 | if (err) | |
1073 | break; | |
1074 | } | |
1075 | } | |
1076 | return err; | |
1077 | } |