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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 | |
13 | */ | |
14 | ||
15 | #include <linux/migrate.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/swap.h> | |
18 | #include <linux/swapops.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/buffer_head.h> | |
21 | #include <linux/mm_inline.h> | |
22 | #include <linux/nsproxy.h> | |
23 | #include <linux/pagevec.h> | |
24 | #include <linux/ksm.h> | |
25 | #include <linux/rmap.h> | |
26 | #include <linux/topology.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/cpuset.h> | |
29 | #include <linux/writeback.h> | |
30 | #include <linux/mempolicy.h> | |
31 | #include <linux/vmalloc.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/memcontrol.h> | |
34 | #include <linux/syscalls.h> | |
35 | #include <linux/hugetlb.h> | |
36 | #include <linux/gfp.h> | |
37 | ||
38 | #include <asm/tlbflush.h> | |
39 | ||
40 | #include "internal.h" | |
41 | ||
42 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) | |
43 | ||
44 | /* | |
45 | * migrate_prep() needs to be called before we start compiling a list of pages | |
46 | * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is | |
47 | * undesirable, use migrate_prep_local() | |
48 | */ | |
49 | int migrate_prep(void) | |
50 | { | |
51 | /* | |
52 | * Clear the LRU lists so pages can be isolated. | |
53 | * Note that pages may be moved off the LRU after we have | |
54 | * drained them. Those pages will fail to migrate like other | |
55 | * pages that may be busy. | |
56 | */ | |
57 | lru_add_drain_all(); | |
58 | ||
59 | return 0; | |
60 | } | |
61 | ||
62 | /* Do the necessary work of migrate_prep but not if it involves other CPUs */ | |
63 | int migrate_prep_local(void) | |
64 | { | |
65 | lru_add_drain(); | |
66 | ||
67 | return 0; | |
68 | } | |
69 | ||
70 | /* | |
71 | * Add isolated pages on the list back to the LRU under page lock | |
72 | * to avoid leaking evictable pages back onto unevictable list. | |
73 | */ | |
74 | void putback_lru_pages(struct list_head *l) | |
75 | { | |
76 | struct page *page; | |
77 | struct page *page2; | |
78 | ||
79 | list_for_each_entry_safe(page, page2, l, lru) { | |
80 | list_del(&page->lru); | |
81 | dec_zone_page_state(page, NR_ISOLATED_ANON + | |
82 | page_is_file_cache(page)); | |
83 | putback_lru_page(page); | |
84 | } | |
85 | } | |
86 | ||
87 | /* | |
88 | * Restore a potential migration pte to a working pte entry | |
89 | */ | |
90 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, | |
91 | unsigned long addr, void *old) | |
92 | { | |
93 | struct mm_struct *mm = vma->vm_mm; | |
94 | swp_entry_t entry; | |
95 | pgd_t *pgd; | |
96 | pud_t *pud; | |
97 | pmd_t *pmd; | |
98 | pte_t *ptep, pte; | |
99 | spinlock_t *ptl; | |
100 | ||
101 | if (unlikely(PageHuge(new))) { | |
102 | ptep = huge_pte_offset(mm, addr); | |
103 | if (!ptep) | |
104 | goto out; | |
105 | ptl = &mm->page_table_lock; | |
106 | } else { | |
107 | pgd = pgd_offset(mm, addr); | |
108 | if (!pgd_present(*pgd)) | |
109 | goto out; | |
110 | ||
111 | pud = pud_offset(pgd, addr); | |
112 | if (!pud_present(*pud)) | |
113 | goto out; | |
114 | ||
115 | pmd = pmd_offset(pud, addr); | |
116 | if (pmd_trans_huge(*pmd)) | |
117 | goto out; | |
118 | if (!pmd_present(*pmd)) | |
119 | goto out; | |
120 | ||
121 | ptep = pte_offset_map(pmd, addr); | |
122 | ||
123 | if (!is_swap_pte(*ptep)) { | |
124 | pte_unmap(ptep); | |
125 | goto out; | |
126 | } | |
127 | ||
128 | ptl = pte_lockptr(mm, pmd); | |
129 | } | |
130 | ||
131 | spin_lock(ptl); | |
132 | pte = *ptep; | |
133 | if (!is_swap_pte(pte)) | |
134 | goto unlock; | |
135 | ||
136 | entry = pte_to_swp_entry(pte); | |
137 | ||
138 | if (!is_migration_entry(entry) || | |
139 | migration_entry_to_page(entry) != old) | |
140 | goto unlock; | |
141 | ||
142 | get_page(new); | |
143 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
144 | if (is_write_migration_entry(entry)) | |
145 | pte = pte_mkwrite(pte); | |
146 | #ifdef CONFIG_HUGETLB_PAGE | |
147 | if (PageHuge(new)) | |
148 | pte = pte_mkhuge(pte); | |
149 | #endif | |
150 | flush_cache_page(vma, addr, pte_pfn(pte)); | |
151 | set_pte_at(mm, addr, ptep, pte); | |
152 | ||
153 | if (PageHuge(new)) { | |
154 | if (PageAnon(new)) | |
155 | hugepage_add_anon_rmap(new, vma, addr); | |
156 | else | |
157 | page_dup_rmap(new); | |
158 | } else if (PageAnon(new)) | |
159 | page_add_anon_rmap(new, vma, addr); | |
160 | else | |
161 | page_add_file_rmap(new); | |
162 | ||
163 | /* No need to invalidate - it was non-present before */ | |
164 | update_mmu_cache(vma, addr, ptep); | |
165 | unlock: | |
166 | pte_unmap_unlock(ptep, ptl); | |
167 | out: | |
168 | return SWAP_AGAIN; | |
169 | } | |
170 | ||
171 | /* | |
172 | * Get rid of all migration entries and replace them by | |
173 | * references to the indicated page. | |
174 | */ | |
175 | static void remove_migration_ptes(struct page *old, struct page *new) | |
176 | { | |
177 | rmap_walk(new, remove_migration_pte, old); | |
178 | } | |
179 | ||
180 | /* | |
181 | * Something used the pte of a page under migration. We need to | |
182 | * get to the page and wait until migration is finished. | |
183 | * When we return from this function the fault will be retried. | |
184 | * | |
185 | * This function is called from do_swap_page(). | |
186 | */ | |
187 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
188 | unsigned long address) | |
189 | { | |
190 | pte_t *ptep, pte; | |
191 | spinlock_t *ptl; | |
192 | swp_entry_t entry; | |
193 | struct page *page; | |
194 | ||
195 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
196 | pte = *ptep; | |
197 | if (!is_swap_pte(pte)) | |
198 | goto out; | |
199 | ||
200 | entry = pte_to_swp_entry(pte); | |
201 | if (!is_migration_entry(entry)) | |
202 | goto out; | |
203 | ||
204 | page = migration_entry_to_page(entry); | |
205 | ||
206 | /* | |
207 | * Once radix-tree replacement of page migration started, page_count | |
208 | * *must* be zero. And, we don't want to call wait_on_page_locked() | |
209 | * against a page without get_page(). | |
210 | * So, we use get_page_unless_zero(), here. Even failed, page fault | |
211 | * will occur again. | |
212 | */ | |
213 | if (!get_page_unless_zero(page)) | |
214 | goto out; | |
215 | pte_unmap_unlock(ptep, ptl); | |
216 | wait_on_page_locked(page); | |
217 | put_page(page); | |
218 | return; | |
219 | out: | |
220 | pte_unmap_unlock(ptep, ptl); | |
221 | } | |
222 | ||
223 | /* | |
224 | * Replace the page in the mapping. | |
225 | * | |
226 | * The number of remaining references must be: | |
227 | * 1 for anonymous pages without a mapping | |
228 | * 2 for pages with a mapping | |
229 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. | |
230 | */ | |
231 | static int migrate_page_move_mapping(struct address_space *mapping, | |
232 | struct page *newpage, struct page *page) | |
233 | { | |
234 | int expected_count; | |
235 | void **pslot; | |
236 | ||
237 | if (!mapping) { | |
238 | /* Anonymous page without mapping */ | |
239 | if (page_count(page) != 1) | |
240 | return -EAGAIN; | |
241 | return 0; | |
242 | } | |
243 | ||
244 | spin_lock_irq(&mapping->tree_lock); | |
245 | ||
246 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
247 | page_index(page)); | |
248 | ||
249 | expected_count = 2 + page_has_private(page); | |
250 | if (page_count(page) != expected_count || | |
251 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { | |
252 | spin_unlock_irq(&mapping->tree_lock); | |
253 | return -EAGAIN; | |
254 | } | |
255 | ||
256 | if (!page_freeze_refs(page, expected_count)) { | |
257 | spin_unlock_irq(&mapping->tree_lock); | |
258 | return -EAGAIN; | |
259 | } | |
260 | ||
261 | /* | |
262 | * Now we know that no one else is looking at the page. | |
263 | */ | |
264 | get_page(newpage); /* add cache reference */ | |
265 | if (PageSwapCache(page)) { | |
266 | SetPageSwapCache(newpage); | |
267 | set_page_private(newpage, page_private(page)); | |
268 | } | |
269 | ||
270 | radix_tree_replace_slot(pslot, newpage); | |
271 | ||
272 | page_unfreeze_refs(page, expected_count); | |
273 | /* | |
274 | * Drop cache reference from old page. | |
275 | * We know this isn't the last reference. | |
276 | */ | |
277 | __put_page(page); | |
278 | ||
279 | /* | |
280 | * If moved to a different zone then also account | |
281 | * the page for that zone. Other VM counters will be | |
282 | * taken care of when we establish references to the | |
283 | * new page and drop references to the old page. | |
284 | * | |
285 | * Note that anonymous pages are accounted for | |
286 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
287 | * are mapped to swap space. | |
288 | */ | |
289 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
290 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
291 | if (PageSwapBacked(page)) { | |
292 | __dec_zone_page_state(page, NR_SHMEM); | |
293 | __inc_zone_page_state(newpage, NR_SHMEM); | |
294 | } | |
295 | spin_unlock_irq(&mapping->tree_lock); | |
296 | ||
297 | return 0; | |
298 | } | |
299 | ||
300 | /* | |
301 | * The expected number of remaining references is the same as that | |
302 | * of migrate_page_move_mapping(). | |
303 | */ | |
304 | int migrate_huge_page_move_mapping(struct address_space *mapping, | |
305 | struct page *newpage, struct page *page) | |
306 | { | |
307 | int expected_count; | |
308 | void **pslot; | |
309 | ||
310 | if (!mapping) { | |
311 | if (page_count(page) != 1) | |
312 | return -EAGAIN; | |
313 | return 0; | |
314 | } | |
315 | ||
316 | spin_lock_irq(&mapping->tree_lock); | |
317 | ||
318 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
319 | page_index(page)); | |
320 | ||
321 | expected_count = 2 + page_has_private(page); | |
322 | if (page_count(page) != expected_count || | |
323 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { | |
324 | spin_unlock_irq(&mapping->tree_lock); | |
325 | return -EAGAIN; | |
326 | } | |
327 | ||
328 | if (!page_freeze_refs(page, expected_count)) { | |
329 | spin_unlock_irq(&mapping->tree_lock); | |
330 | return -EAGAIN; | |
331 | } | |
332 | ||
333 | get_page(newpage); | |
334 | ||
335 | radix_tree_replace_slot(pslot, newpage); | |
336 | ||
337 | page_unfreeze_refs(page, expected_count); | |
338 | ||
339 | __put_page(page); | |
340 | ||
341 | spin_unlock_irq(&mapping->tree_lock); | |
342 | return 0; | |
343 | } | |
344 | ||
345 | /* | |
346 | * Copy the page to its new location | |
347 | */ | |
348 | void migrate_page_copy(struct page *newpage, struct page *page) | |
349 | { | |
350 | if (PageHuge(page)) | |
351 | copy_huge_page(newpage, page); | |
352 | else | |
353 | copy_highpage(newpage, page); | |
354 | ||
355 | if (PageError(page)) | |
356 | SetPageError(newpage); | |
357 | if (PageReferenced(page)) | |
358 | SetPageReferenced(newpage); | |
359 | if (PageUptodate(page)) | |
360 | SetPageUptodate(newpage); | |
361 | if (TestClearPageActive(page)) { | |
362 | VM_BUG_ON(PageUnevictable(page)); | |
363 | SetPageActive(newpage); | |
364 | } else if (TestClearPageUnevictable(page)) | |
365 | SetPageUnevictable(newpage); | |
366 | if (PageChecked(page)) | |
367 | SetPageChecked(newpage); | |
368 | if (PageMappedToDisk(page)) | |
369 | SetPageMappedToDisk(newpage); | |
370 | ||
371 | if (PageDirty(page)) { | |
372 | clear_page_dirty_for_io(page); | |
373 | /* | |
374 | * Want to mark the page and the radix tree as dirty, and | |
375 | * redo the accounting that clear_page_dirty_for_io undid, | |
376 | * but we can't use set_page_dirty because that function | |
377 | * is actually a signal that all of the page has become dirty. | |
378 | * Wheras only part of our page may be dirty. | |
379 | */ | |
380 | __set_page_dirty_nobuffers(newpage); | |
381 | } | |
382 | ||
383 | mlock_migrate_page(newpage, page); | |
384 | ksm_migrate_page(newpage, page); | |
385 | ||
386 | ClearPageSwapCache(page); | |
387 | ClearPagePrivate(page); | |
388 | set_page_private(page, 0); | |
389 | page->mapping = NULL; | |
390 | ||
391 | /* | |
392 | * If any waiters have accumulated on the new page then | |
393 | * wake them up. | |
394 | */ | |
395 | if (PageWriteback(newpage)) | |
396 | end_page_writeback(newpage); | |
397 | } | |
398 | ||
399 | /************************************************************ | |
400 | * Migration functions | |
401 | ***********************************************************/ | |
402 | ||
403 | /* Always fail migration. Used for mappings that are not movable */ | |
404 | int fail_migrate_page(struct address_space *mapping, | |
405 | struct page *newpage, struct page *page) | |
406 | { | |
407 | return -EIO; | |
408 | } | |
409 | EXPORT_SYMBOL(fail_migrate_page); | |
410 | ||
411 | /* | |
412 | * Common logic to directly migrate a single page suitable for | |
413 | * pages that do not use PagePrivate/PagePrivate2. | |
414 | * | |
415 | * Pages are locked upon entry and exit. | |
416 | */ | |
417 | int migrate_page(struct address_space *mapping, | |
418 | struct page *newpage, struct page *page) | |
419 | { | |
420 | int rc; | |
421 | ||
422 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
423 | ||
424 | rc = migrate_page_move_mapping(mapping, newpage, page); | |
425 | ||
426 | if (rc) | |
427 | return rc; | |
428 | ||
429 | migrate_page_copy(newpage, page); | |
430 | return 0; | |
431 | } | |
432 | EXPORT_SYMBOL(migrate_page); | |
433 | ||
434 | #ifdef CONFIG_BLOCK | |
435 | /* | |
436 | * Migration function for pages with buffers. This function can only be used | |
437 | * if the underlying filesystem guarantees that no other references to "page" | |
438 | * exist. | |
439 | */ | |
440 | int buffer_migrate_page(struct address_space *mapping, | |
441 | struct page *newpage, struct page *page) | |
442 | { | |
443 | struct buffer_head *bh, *head; | |
444 | int rc; | |
445 | ||
446 | if (!page_has_buffers(page)) | |
447 | return migrate_page(mapping, newpage, page); | |
448 | ||
449 | head = page_buffers(page); | |
450 | ||
451 | rc = migrate_page_move_mapping(mapping, newpage, page); | |
452 | ||
453 | if (rc) | |
454 | return rc; | |
455 | ||
456 | bh = head; | |
457 | do { | |
458 | get_bh(bh); | |
459 | lock_buffer(bh); | |
460 | bh = bh->b_this_page; | |
461 | ||
462 | } while (bh != head); | |
463 | ||
464 | ClearPagePrivate(page); | |
465 | set_page_private(newpage, page_private(page)); | |
466 | set_page_private(page, 0); | |
467 | put_page(page); | |
468 | get_page(newpage); | |
469 | ||
470 | bh = head; | |
471 | do { | |
472 | set_bh_page(bh, newpage, bh_offset(bh)); | |
473 | bh = bh->b_this_page; | |
474 | ||
475 | } while (bh != head); | |
476 | ||
477 | SetPagePrivate(newpage); | |
478 | ||
479 | migrate_page_copy(newpage, page); | |
480 | ||
481 | bh = head; | |
482 | do { | |
483 | unlock_buffer(bh); | |
484 | put_bh(bh); | |
485 | bh = bh->b_this_page; | |
486 | ||
487 | } while (bh != head); | |
488 | ||
489 | return 0; | |
490 | } | |
491 | EXPORT_SYMBOL(buffer_migrate_page); | |
492 | #endif | |
493 | ||
494 | /* | |
495 | * Writeback a page to clean the dirty state | |
496 | */ | |
497 | static int writeout(struct address_space *mapping, struct page *page) | |
498 | { | |
499 | struct writeback_control wbc = { | |
500 | .sync_mode = WB_SYNC_NONE, | |
501 | .nr_to_write = 1, | |
502 | .range_start = 0, | |
503 | .range_end = LLONG_MAX, | |
504 | .for_reclaim = 1 | |
505 | }; | |
506 | int rc; | |
507 | ||
508 | if (!mapping->a_ops->writepage) | |
509 | /* No write method for the address space */ | |
510 | return -EINVAL; | |
511 | ||
512 | if (!clear_page_dirty_for_io(page)) | |
513 | /* Someone else already triggered a write */ | |
514 | return -EAGAIN; | |
515 | ||
516 | /* | |
517 | * A dirty page may imply that the underlying filesystem has | |
518 | * the page on some queue. So the page must be clean for | |
519 | * migration. Writeout may mean we loose the lock and the | |
520 | * page state is no longer what we checked for earlier. | |
521 | * At this point we know that the migration attempt cannot | |
522 | * be successful. | |
523 | */ | |
524 | remove_migration_ptes(page, page); | |
525 | ||
526 | rc = mapping->a_ops->writepage(page, &wbc); | |
527 | ||
528 | if (rc != AOP_WRITEPAGE_ACTIVATE) | |
529 | /* unlocked. Relock */ | |
530 | lock_page(page); | |
531 | ||
532 | return (rc < 0) ? -EIO : -EAGAIN; | |
533 | } | |
534 | ||
535 | /* | |
536 | * Default handling if a filesystem does not provide a migration function. | |
537 | */ | |
538 | static int fallback_migrate_page(struct address_space *mapping, | |
539 | struct page *newpage, struct page *page) | |
540 | { | |
541 | if (PageDirty(page)) | |
542 | return writeout(mapping, page); | |
543 | ||
544 | /* | |
545 | * Buffers may be managed in a filesystem specific way. | |
546 | * We must have no buffers or drop them. | |
547 | */ | |
548 | if (page_has_private(page) && | |
549 | !try_to_release_page(page, GFP_KERNEL)) | |
550 | return -EAGAIN; | |
551 | ||
552 | return migrate_page(mapping, newpage, page); | |
553 | } | |
554 | ||
555 | /* | |
556 | * Move a page to a newly allocated page | |
557 | * The page is locked and all ptes have been successfully removed. | |
558 | * | |
559 | * The new page will have replaced the old page if this function | |
560 | * is successful. | |
561 | * | |
562 | * Return value: | |
563 | * < 0 - error code | |
564 | * == 0 - success | |
565 | */ | |
566 | static int move_to_new_page(struct page *newpage, struct page *page, | |
567 | int remap_swapcache) | |
568 | { | |
569 | struct address_space *mapping; | |
570 | int rc; | |
571 | ||
572 | /* | |
573 | * Block others from accessing the page when we get around to | |
574 | * establishing additional references. We are the only one | |
575 | * holding a reference to the new page at this point. | |
576 | */ | |
577 | if (!trylock_page(newpage)) | |
578 | BUG(); | |
579 | ||
580 | /* Prepare mapping for the new page.*/ | |
581 | newpage->index = page->index; | |
582 | newpage->mapping = page->mapping; | |
583 | if (PageSwapBacked(page)) | |
584 | SetPageSwapBacked(newpage); | |
585 | ||
586 | mapping = page_mapping(page); | |
587 | if (!mapping) | |
588 | rc = migrate_page(mapping, newpage, page); | |
589 | else if (mapping->a_ops->migratepage) | |
590 | /* | |
591 | * Most pages have a mapping and most filesystems | |
592 | * should provide a migration function. Anonymous | |
593 | * pages are part of swap space which also has its | |
594 | * own migration function. This is the most common | |
595 | * path for page migration. | |
596 | */ | |
597 | rc = mapping->a_ops->migratepage(mapping, | |
598 | newpage, page); | |
599 | else | |
600 | rc = fallback_migrate_page(mapping, newpage, page); | |
601 | ||
602 | if (rc) { | |
603 | newpage->mapping = NULL; | |
604 | } else { | |
605 | if (remap_swapcache) | |
606 | remove_migration_ptes(page, newpage); | |
607 | } | |
608 | ||
609 | unlock_page(newpage); | |
610 | ||
611 | return rc; | |
612 | } | |
613 | ||
614 | /* | |
615 | * Obtain the lock on page, remove all ptes and migrate the page | |
616 | * to the newly allocated page in newpage. | |
617 | */ | |
618 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, | |
619 | struct page *page, int force, bool offlining, bool sync) | |
620 | { | |
621 | int rc = 0; | |
622 | int *result = NULL; | |
623 | struct page *newpage = get_new_page(page, private, &result); | |
624 | int remap_swapcache = 1; | |
625 | int rcu_locked = 0; | |
626 | int charge = 0; | |
627 | struct mem_cgroup *mem = NULL; | |
628 | struct anon_vma *anon_vma = NULL; | |
629 | ||
630 | if (!newpage) | |
631 | return -ENOMEM; | |
632 | ||
633 | if (page_count(page) == 1) { | |
634 | /* page was freed from under us. So we are done. */ | |
635 | goto move_newpage; | |
636 | } | |
637 | if (unlikely(PageTransHuge(page))) | |
638 | if (unlikely(split_huge_page(page))) | |
639 | goto move_newpage; | |
640 | ||
641 | /* prepare cgroup just returns 0 or -ENOMEM */ | |
642 | rc = -EAGAIN; | |
643 | ||
644 | if (!trylock_page(page)) { | |
645 | if (!force) | |
646 | goto move_newpage; | |
647 | ||
648 | /* | |
649 | * It's not safe for direct compaction to call lock_page. | |
650 | * For example, during page readahead pages are added locked | |
651 | * to the LRU. Later, when the IO completes the pages are | |
652 | * marked uptodate and unlocked. However, the queueing | |
653 | * could be merging multiple pages for one bio (e.g. | |
654 | * mpage_readpages). If an allocation happens for the | |
655 | * second or third page, the process can end up locking | |
656 | * the same page twice and deadlocking. Rather than | |
657 | * trying to be clever about what pages can be locked, | |
658 | * avoid the use of lock_page for direct compaction | |
659 | * altogether. | |
660 | */ | |
661 | if (current->flags & PF_MEMALLOC) | |
662 | goto move_newpage; | |
663 | ||
664 | lock_page(page); | |
665 | } | |
666 | ||
667 | /* | |
668 | * Only memory hotplug's offline_pages() caller has locked out KSM, | |
669 | * and can safely migrate a KSM page. The other cases have skipped | |
670 | * PageKsm along with PageReserved - but it is only now when we have | |
671 | * the page lock that we can be certain it will not go KSM beneath us | |
672 | * (KSM will not upgrade a page from PageAnon to PageKsm when it sees | |
673 | * its pagecount raised, but only here do we take the page lock which | |
674 | * serializes that). | |
675 | */ | |
676 | if (PageKsm(page) && !offlining) { | |
677 | rc = -EBUSY; | |
678 | goto unlock; | |
679 | } | |
680 | ||
681 | /* charge against new page */ | |
682 | charge = mem_cgroup_prepare_migration(page, newpage, &mem); | |
683 | if (charge == -ENOMEM) { | |
684 | rc = -ENOMEM; | |
685 | goto unlock; | |
686 | } | |
687 | BUG_ON(charge); | |
688 | ||
689 | if (PageWriteback(page)) { | |
690 | if (!force || !sync) | |
691 | goto uncharge; | |
692 | wait_on_page_writeback(page); | |
693 | } | |
694 | /* | |
695 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, | |
696 | * we cannot notice that anon_vma is freed while we migrates a page. | |
697 | * This rcu_read_lock() delays freeing anon_vma pointer until the end | |
698 | * of migration. File cache pages are no problem because of page_lock() | |
699 | * File Caches may use write_page() or lock_page() in migration, then, | |
700 | * just care Anon page here. | |
701 | */ | |
702 | if (PageAnon(page)) { | |
703 | rcu_read_lock(); | |
704 | rcu_locked = 1; | |
705 | ||
706 | /* Determine how to safely use anon_vma */ | |
707 | if (!page_mapped(page)) { | |
708 | if (!PageSwapCache(page)) | |
709 | goto rcu_unlock; | |
710 | ||
711 | /* | |
712 | * We cannot be sure that the anon_vma of an unmapped | |
713 | * swapcache page is safe to use because we don't | |
714 | * know in advance if the VMA that this page belonged | |
715 | * to still exists. If the VMA and others sharing the | |
716 | * data have been freed, then the anon_vma could | |
717 | * already be invalid. | |
718 | * | |
719 | * To avoid this possibility, swapcache pages get | |
720 | * migrated but are not remapped when migration | |
721 | * completes | |
722 | */ | |
723 | remap_swapcache = 0; | |
724 | } else { | |
725 | /* | |
726 | * Take a reference count on the anon_vma if the | |
727 | * page is mapped so that it is guaranteed to | |
728 | * exist when the page is remapped later | |
729 | */ | |
730 | anon_vma = page_anon_vma(page); | |
731 | get_anon_vma(anon_vma); | |
732 | } | |
733 | } | |
734 | ||
735 | /* | |
736 | * Corner case handling: | |
737 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
738 | * and treated as swapcache but it has no rmap yet. | |
739 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
740 | * trigger a BUG. So handle it here. | |
741 | * 2. An orphaned page (see truncate_complete_page) might have | |
742 | * fs-private metadata. The page can be picked up due to memory | |
743 | * offlining. Everywhere else except page reclaim, the page is | |
744 | * invisible to the vm, so the page can not be migrated. So try to | |
745 | * free the metadata, so the page can be freed. | |
746 | */ | |
747 | if (!page->mapping) { | |
748 | if (!PageAnon(page) && page_has_private(page)) { | |
749 | /* | |
750 | * Go direct to try_to_free_buffers() here because | |
751 | * a) that's what try_to_release_page() would do anyway | |
752 | * b) we may be under rcu_read_lock() here, so we can't | |
753 | * use GFP_KERNEL which is what try_to_release_page() | |
754 | * needs to be effective. | |
755 | */ | |
756 | try_to_free_buffers(page); | |
757 | goto rcu_unlock; | |
758 | } | |
759 | goto skip_unmap; | |
760 | } | |
761 | ||
762 | /* Establish migration ptes or remove ptes */ | |
763 | try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); | |
764 | ||
765 | skip_unmap: | |
766 | if (!page_mapped(page)) | |
767 | rc = move_to_new_page(newpage, page, remap_swapcache); | |
768 | ||
769 | if (rc && remap_swapcache) | |
770 | remove_migration_ptes(page, page); | |
771 | rcu_unlock: | |
772 | ||
773 | /* Drop an anon_vma reference if we took one */ | |
774 | if (anon_vma) | |
775 | drop_anon_vma(anon_vma); | |
776 | ||
777 | if (rcu_locked) | |
778 | rcu_read_unlock(); | |
779 | uncharge: | |
780 | if (!charge) | |
781 | mem_cgroup_end_migration(mem, page, newpage); | |
782 | unlock: | |
783 | unlock_page(page); | |
784 | ||
785 | if (rc != -EAGAIN) { | |
786 | /* | |
787 | * A page that has been migrated has all references | |
788 | * removed and will be freed. A page that has not been | |
789 | * migrated will have kepts its references and be | |
790 | * restored. | |
791 | */ | |
792 | list_del(&page->lru); | |
793 | dec_zone_page_state(page, NR_ISOLATED_ANON + | |
794 | page_is_file_cache(page)); | |
795 | putback_lru_page(page); | |
796 | } | |
797 | ||
798 | move_newpage: | |
799 | ||
800 | /* | |
801 | * Move the new page to the LRU. If migration was not successful | |
802 | * then this will free the page. | |
803 | */ | |
804 | putback_lru_page(newpage); | |
805 | ||
806 | if (result) { | |
807 | if (rc) | |
808 | *result = rc; | |
809 | else | |
810 | *result = page_to_nid(newpage); | |
811 | } | |
812 | return rc; | |
813 | } | |
814 | ||
815 | /* | |
816 | * Counterpart of unmap_and_move_page() for hugepage migration. | |
817 | * | |
818 | * This function doesn't wait the completion of hugepage I/O | |
819 | * because there is no race between I/O and migration for hugepage. | |
820 | * Note that currently hugepage I/O occurs only in direct I/O | |
821 | * where no lock is held and PG_writeback is irrelevant, | |
822 | * and writeback status of all subpages are counted in the reference | |
823 | * count of the head page (i.e. if all subpages of a 2MB hugepage are | |
824 | * under direct I/O, the reference of the head page is 512 and a bit more.) | |
825 | * This means that when we try to migrate hugepage whose subpages are | |
826 | * doing direct I/O, some references remain after try_to_unmap() and | |
827 | * hugepage migration fails without data corruption. | |
828 | * | |
829 | * There is also no race when direct I/O is issued on the page under migration, | |
830 | * because then pte is replaced with migration swap entry and direct I/O code | |
831 | * will wait in the page fault for migration to complete. | |
832 | */ | |
833 | static int unmap_and_move_huge_page(new_page_t get_new_page, | |
834 | unsigned long private, struct page *hpage, | |
835 | int force, bool offlining, bool sync) | |
836 | { | |
837 | int rc = 0; | |
838 | int *result = NULL; | |
839 | struct page *new_hpage = get_new_page(hpage, private, &result); | |
840 | int rcu_locked = 0; | |
841 | struct anon_vma *anon_vma = NULL; | |
842 | ||
843 | if (!new_hpage) | |
844 | return -ENOMEM; | |
845 | ||
846 | rc = -EAGAIN; | |
847 | ||
848 | if (!trylock_page(hpage)) { | |
849 | if (!force || !sync) | |
850 | goto out; | |
851 | lock_page(hpage); | |
852 | } | |
853 | ||
854 | if (PageAnon(hpage)) { | |
855 | rcu_read_lock(); | |
856 | rcu_locked = 1; | |
857 | ||
858 | if (page_mapped(hpage)) { | |
859 | anon_vma = page_anon_vma(hpage); | |
860 | atomic_inc(&anon_vma->external_refcount); | |
861 | } | |
862 | } | |
863 | ||
864 | try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); | |
865 | ||
866 | if (!page_mapped(hpage)) | |
867 | rc = move_to_new_page(new_hpage, hpage, 1); | |
868 | ||
869 | if (rc) | |
870 | remove_migration_ptes(hpage, hpage); | |
871 | ||
872 | if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount, | |
873 | &anon_vma->lock)) { | |
874 | int empty = list_empty(&anon_vma->head); | |
875 | spin_unlock(&anon_vma->lock); | |
876 | if (empty) | |
877 | anon_vma_free(anon_vma); | |
878 | } | |
879 | ||
880 | if (rcu_locked) | |
881 | rcu_read_unlock(); | |
882 | out: | |
883 | unlock_page(hpage); | |
884 | ||
885 | if (rc != -EAGAIN) { | |
886 | list_del(&hpage->lru); | |
887 | put_page(hpage); | |
888 | } | |
889 | ||
890 | put_page(new_hpage); | |
891 | ||
892 | if (result) { | |
893 | if (rc) | |
894 | *result = rc; | |
895 | else | |
896 | *result = page_to_nid(new_hpage); | |
897 | } | |
898 | return rc; | |
899 | } | |
900 | ||
901 | /* | |
902 | * migrate_pages | |
903 | * | |
904 | * The function takes one list of pages to migrate and a function | |
905 | * that determines from the page to be migrated and the private data | |
906 | * the target of the move and allocates the page. | |
907 | * | |
908 | * The function returns after 10 attempts or if no pages | |
909 | * are movable anymore because to has become empty | |
910 | * or no retryable pages exist anymore. | |
911 | * Caller should call putback_lru_pages to return pages to the LRU | |
912 | * or free list. | |
913 | * | |
914 | * Return: Number of pages not migrated or error code. | |
915 | */ | |
916 | int migrate_pages(struct list_head *from, | |
917 | new_page_t get_new_page, unsigned long private, bool offlining, | |
918 | bool sync) | |
919 | { | |
920 | int retry = 1; | |
921 | int nr_failed = 0; | |
922 | int pass = 0; | |
923 | struct page *page; | |
924 | struct page *page2; | |
925 | int swapwrite = current->flags & PF_SWAPWRITE; | |
926 | int rc; | |
927 | ||
928 | if (!swapwrite) | |
929 | current->flags |= PF_SWAPWRITE; | |
930 | ||
931 | for(pass = 0; pass < 10 && retry; pass++) { | |
932 | retry = 0; | |
933 | ||
934 | list_for_each_entry_safe(page, page2, from, lru) { | |
935 | cond_resched(); | |
936 | ||
937 | rc = unmap_and_move(get_new_page, private, | |
938 | page, pass > 2, offlining, | |
939 | sync); | |
940 | ||
941 | switch(rc) { | |
942 | case -ENOMEM: | |
943 | goto out; | |
944 | case -EAGAIN: | |
945 | retry++; | |
946 | break; | |
947 | case 0: | |
948 | break; | |
949 | default: | |
950 | /* Permanent failure */ | |
951 | nr_failed++; | |
952 | break; | |
953 | } | |
954 | } | |
955 | } | |
956 | rc = 0; | |
957 | out: | |
958 | if (!swapwrite) | |
959 | current->flags &= ~PF_SWAPWRITE; | |
960 | ||
961 | if (rc) | |
962 | return rc; | |
963 | ||
964 | return nr_failed + retry; | |
965 | } | |
966 | ||
967 | int migrate_huge_pages(struct list_head *from, | |
968 | new_page_t get_new_page, unsigned long private, bool offlining, | |
969 | bool sync) | |
970 | { | |
971 | int retry = 1; | |
972 | int nr_failed = 0; | |
973 | int pass = 0; | |
974 | struct page *page; | |
975 | struct page *page2; | |
976 | int rc; | |
977 | ||
978 | for (pass = 0; pass < 10 && retry; pass++) { | |
979 | retry = 0; | |
980 | ||
981 | list_for_each_entry_safe(page, page2, from, lru) { | |
982 | cond_resched(); | |
983 | ||
984 | rc = unmap_and_move_huge_page(get_new_page, | |
985 | private, page, pass > 2, offlining, | |
986 | sync); | |
987 | ||
988 | switch(rc) { | |
989 | case -ENOMEM: | |
990 | goto out; | |
991 | case -EAGAIN: | |
992 | retry++; | |
993 | break; | |
994 | case 0: | |
995 | break; | |
996 | default: | |
997 | /* Permanent failure */ | |
998 | nr_failed++; | |
999 | break; | |
1000 | } | |
1001 | } | |
1002 | } | |
1003 | rc = 0; | |
1004 | out: | |
1005 | ||
1006 | list_for_each_entry_safe(page, page2, from, lru) | |
1007 | put_page(page); | |
1008 | ||
1009 | if (rc) | |
1010 | return rc; | |
1011 | ||
1012 | return nr_failed + retry; | |
1013 | } | |
1014 | ||
1015 | #ifdef CONFIG_NUMA | |
1016 | /* | |
1017 | * Move a list of individual pages | |
1018 | */ | |
1019 | struct page_to_node { | |
1020 | unsigned long addr; | |
1021 | struct page *page; | |
1022 | int node; | |
1023 | int status; | |
1024 | }; | |
1025 | ||
1026 | static struct page *new_page_node(struct page *p, unsigned long private, | |
1027 | int **result) | |
1028 | { | |
1029 | struct page_to_node *pm = (struct page_to_node *)private; | |
1030 | ||
1031 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
1032 | pm++; | |
1033 | ||
1034 | if (pm->node == MAX_NUMNODES) | |
1035 | return NULL; | |
1036 | ||
1037 | *result = &pm->status; | |
1038 | ||
1039 | return alloc_pages_exact_node(pm->node, | |
1040 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); | |
1041 | } | |
1042 | ||
1043 | /* | |
1044 | * Move a set of pages as indicated in the pm array. The addr | |
1045 | * field must be set to the virtual address of the page to be moved | |
1046 | * and the node number must contain a valid target node. | |
1047 | * The pm array ends with node = MAX_NUMNODES. | |
1048 | */ | |
1049 | static int do_move_page_to_node_array(struct mm_struct *mm, | |
1050 | struct page_to_node *pm, | |
1051 | int migrate_all) | |
1052 | { | |
1053 | int err; | |
1054 | struct page_to_node *pp; | |
1055 | LIST_HEAD(pagelist); | |
1056 | ||
1057 | down_read(&mm->mmap_sem); | |
1058 | ||
1059 | /* | |
1060 | * Build a list of pages to migrate | |
1061 | */ | |
1062 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { | |
1063 | struct vm_area_struct *vma; | |
1064 | struct page *page; | |
1065 | ||
1066 | err = -EFAULT; | |
1067 | vma = find_vma(mm, pp->addr); | |
1068 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) | |
1069 | goto set_status; | |
1070 | ||
1071 | page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT); | |
1072 | ||
1073 | err = PTR_ERR(page); | |
1074 | if (IS_ERR(page)) | |
1075 | goto set_status; | |
1076 | ||
1077 | err = -ENOENT; | |
1078 | if (!page) | |
1079 | goto set_status; | |
1080 | ||
1081 | /* Use PageReserved to check for zero page */ | |
1082 | if (PageReserved(page) || PageKsm(page)) | |
1083 | goto put_and_set; | |
1084 | ||
1085 | pp->page = page; | |
1086 | err = page_to_nid(page); | |
1087 | ||
1088 | if (err == pp->node) | |
1089 | /* | |
1090 | * Node already in the right place | |
1091 | */ | |
1092 | goto put_and_set; | |
1093 | ||
1094 | err = -EACCES; | |
1095 | if (page_mapcount(page) > 1 && | |
1096 | !migrate_all) | |
1097 | goto put_and_set; | |
1098 | ||
1099 | err = isolate_lru_page(page); | |
1100 | if (!err) { | |
1101 | list_add_tail(&page->lru, &pagelist); | |
1102 | inc_zone_page_state(page, NR_ISOLATED_ANON + | |
1103 | page_is_file_cache(page)); | |
1104 | } | |
1105 | put_and_set: | |
1106 | /* | |
1107 | * Either remove the duplicate refcount from | |
1108 | * isolate_lru_page() or drop the page ref if it was | |
1109 | * not isolated. | |
1110 | */ | |
1111 | put_page(page); | |
1112 | set_status: | |
1113 | pp->status = err; | |
1114 | } | |
1115 | ||
1116 | err = 0; | |
1117 | if (!list_empty(&pagelist)) { | |
1118 | err = migrate_pages(&pagelist, new_page_node, | |
1119 | (unsigned long)pm, 0, true); | |
1120 | if (err) | |
1121 | putback_lru_pages(&pagelist); | |
1122 | } | |
1123 | ||
1124 | up_read(&mm->mmap_sem); | |
1125 | return err; | |
1126 | } | |
1127 | ||
1128 | /* | |
1129 | * Migrate an array of page address onto an array of nodes and fill | |
1130 | * the corresponding array of status. | |
1131 | */ | |
1132 | static int do_pages_move(struct mm_struct *mm, struct task_struct *task, | |
1133 | unsigned long nr_pages, | |
1134 | const void __user * __user *pages, | |
1135 | const int __user *nodes, | |
1136 | int __user *status, int flags) | |
1137 | { | |
1138 | struct page_to_node *pm; | |
1139 | nodemask_t task_nodes; | |
1140 | unsigned long chunk_nr_pages; | |
1141 | unsigned long chunk_start; | |
1142 | int err; | |
1143 | ||
1144 | task_nodes = cpuset_mems_allowed(task); | |
1145 | ||
1146 | err = -ENOMEM; | |
1147 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); | |
1148 | if (!pm) | |
1149 | goto out; | |
1150 | ||
1151 | migrate_prep(); | |
1152 | ||
1153 | /* | |
1154 | * Store a chunk of page_to_node array in a page, | |
1155 | * but keep the last one as a marker | |
1156 | */ | |
1157 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; | |
1158 | ||
1159 | for (chunk_start = 0; | |
1160 | chunk_start < nr_pages; | |
1161 | chunk_start += chunk_nr_pages) { | |
1162 | int j; | |
1163 | ||
1164 | if (chunk_start + chunk_nr_pages > nr_pages) | |
1165 | chunk_nr_pages = nr_pages - chunk_start; | |
1166 | ||
1167 | /* fill the chunk pm with addrs and nodes from user-space */ | |
1168 | for (j = 0; j < chunk_nr_pages; j++) { | |
1169 | const void __user *p; | |
1170 | int node; | |
1171 | ||
1172 | err = -EFAULT; | |
1173 | if (get_user(p, pages + j + chunk_start)) | |
1174 | goto out_pm; | |
1175 | pm[j].addr = (unsigned long) p; | |
1176 | ||
1177 | if (get_user(node, nodes + j + chunk_start)) | |
1178 | goto out_pm; | |
1179 | ||
1180 | err = -ENODEV; | |
1181 | if (node < 0 || node >= MAX_NUMNODES) | |
1182 | goto out_pm; | |
1183 | ||
1184 | if (!node_state(node, N_HIGH_MEMORY)) | |
1185 | goto out_pm; | |
1186 | ||
1187 | err = -EACCES; | |
1188 | if (!node_isset(node, task_nodes)) | |
1189 | goto out_pm; | |
1190 | ||
1191 | pm[j].node = node; | |
1192 | } | |
1193 | ||
1194 | /* End marker for this chunk */ | |
1195 | pm[chunk_nr_pages].node = MAX_NUMNODES; | |
1196 | ||
1197 | /* Migrate this chunk */ | |
1198 | err = do_move_page_to_node_array(mm, pm, | |
1199 | flags & MPOL_MF_MOVE_ALL); | |
1200 | if (err < 0) | |
1201 | goto out_pm; | |
1202 | ||
1203 | /* Return status information */ | |
1204 | for (j = 0; j < chunk_nr_pages; j++) | |
1205 | if (put_user(pm[j].status, status + j + chunk_start)) { | |
1206 | err = -EFAULT; | |
1207 | goto out_pm; | |
1208 | } | |
1209 | } | |
1210 | err = 0; | |
1211 | ||
1212 | out_pm: | |
1213 | free_page((unsigned long)pm); | |
1214 | out: | |
1215 | return err; | |
1216 | } | |
1217 | ||
1218 | /* | |
1219 | * Determine the nodes of an array of pages and store it in an array of status. | |
1220 | */ | |
1221 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, | |
1222 | const void __user **pages, int *status) | |
1223 | { | |
1224 | unsigned long i; | |
1225 | ||
1226 | down_read(&mm->mmap_sem); | |
1227 | ||
1228 | for (i = 0; i < nr_pages; i++) { | |
1229 | unsigned long addr = (unsigned long)(*pages); | |
1230 | struct vm_area_struct *vma; | |
1231 | struct page *page; | |
1232 | int err = -EFAULT; | |
1233 | ||
1234 | vma = find_vma(mm, addr); | |
1235 | if (!vma || addr < vma->vm_start) | |
1236 | goto set_status; | |
1237 | ||
1238 | page = follow_page(vma, addr, 0); | |
1239 | ||
1240 | err = PTR_ERR(page); | |
1241 | if (IS_ERR(page)) | |
1242 | goto set_status; | |
1243 | ||
1244 | err = -ENOENT; | |
1245 | /* Use PageReserved to check for zero page */ | |
1246 | if (!page || PageReserved(page) || PageKsm(page)) | |
1247 | goto set_status; | |
1248 | ||
1249 | err = page_to_nid(page); | |
1250 | set_status: | |
1251 | *status = err; | |
1252 | ||
1253 | pages++; | |
1254 | status++; | |
1255 | } | |
1256 | ||
1257 | up_read(&mm->mmap_sem); | |
1258 | } | |
1259 | ||
1260 | /* | |
1261 | * Determine the nodes of a user array of pages and store it in | |
1262 | * a user array of status. | |
1263 | */ | |
1264 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, | |
1265 | const void __user * __user *pages, | |
1266 | int __user *status) | |
1267 | { | |
1268 | #define DO_PAGES_STAT_CHUNK_NR 16 | |
1269 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; | |
1270 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; | |
1271 | ||
1272 | while (nr_pages) { | |
1273 | unsigned long chunk_nr; | |
1274 | ||
1275 | chunk_nr = nr_pages; | |
1276 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) | |
1277 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; | |
1278 | ||
1279 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) | |
1280 | break; | |
1281 | ||
1282 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); | |
1283 | ||
1284 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) | |
1285 | break; | |
1286 | ||
1287 | pages += chunk_nr; | |
1288 | status += chunk_nr; | |
1289 | nr_pages -= chunk_nr; | |
1290 | } | |
1291 | return nr_pages ? -EFAULT : 0; | |
1292 | } | |
1293 | ||
1294 | /* | |
1295 | * Move a list of pages in the address space of the currently executing | |
1296 | * process. | |
1297 | */ | |
1298 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, | |
1299 | const void __user * __user *, pages, | |
1300 | const int __user *, nodes, | |
1301 | int __user *, status, int, flags) | |
1302 | { | |
1303 | const struct cred *cred = current_cred(), *tcred; | |
1304 | struct task_struct *task; | |
1305 | struct mm_struct *mm; | |
1306 | int err; | |
1307 | ||
1308 | /* Check flags */ | |
1309 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
1310 | return -EINVAL; | |
1311 | ||
1312 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
1313 | return -EPERM; | |
1314 | ||
1315 | /* Find the mm_struct */ | |
1316 | read_lock(&tasklist_lock); | |
1317 | task = pid ? find_task_by_vpid(pid) : current; | |
1318 | if (!task) { | |
1319 | read_unlock(&tasklist_lock); | |
1320 | return -ESRCH; | |
1321 | } | |
1322 | mm = get_task_mm(task); | |
1323 | read_unlock(&tasklist_lock); | |
1324 | ||
1325 | if (!mm) | |
1326 | return -EINVAL; | |
1327 | ||
1328 | /* | |
1329 | * Check if this process has the right to modify the specified | |
1330 | * process. The right exists if the process has administrative | |
1331 | * capabilities, superuser privileges or the same | |
1332 | * userid as the target process. | |
1333 | */ | |
1334 | rcu_read_lock(); | |
1335 | tcred = __task_cred(task); | |
1336 | if (cred->euid != tcred->suid && cred->euid != tcred->uid && | |
1337 | cred->uid != tcred->suid && cred->uid != tcred->uid && | |
1338 | !capable(CAP_SYS_NICE)) { | |
1339 | rcu_read_unlock(); | |
1340 | err = -EPERM; | |
1341 | goto out; | |
1342 | } | |
1343 | rcu_read_unlock(); | |
1344 | ||
1345 | err = security_task_movememory(task); | |
1346 | if (err) | |
1347 | goto out; | |
1348 | ||
1349 | if (nodes) { | |
1350 | err = do_pages_move(mm, task, nr_pages, pages, nodes, status, | |
1351 | flags); | |
1352 | } else { | |
1353 | err = do_pages_stat(mm, nr_pages, pages, status); | |
1354 | } | |
1355 | ||
1356 | out: | |
1357 | mmput(mm); | |
1358 | return err; | |
1359 | } | |
1360 | ||
1361 | /* | |
1362 | * Call migration functions in the vma_ops that may prepare | |
1363 | * memory in a vm for migration. migration functions may perform | |
1364 | * the migration for vmas that do not have an underlying page struct. | |
1365 | */ | |
1366 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1367 | const nodemask_t *from, unsigned long flags) | |
1368 | { | |
1369 | struct vm_area_struct *vma; | |
1370 | int err = 0; | |
1371 | ||
1372 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { | |
1373 | if (vma->vm_ops && vma->vm_ops->migrate) { | |
1374 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1375 | if (err) | |
1376 | break; | |
1377 | } | |
1378 | } | |
1379 | return err; | |
1380 | } | |
1381 | #endif |