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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/export.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/hugetlb_cgroup.h> | |
37 | #include <linux/gfp.h> | |
38 | #include <linux/balloon_compaction.h> | |
39 | ||
40 | #include <asm/tlbflush.h> | |
41 | ||
42 | #define CREATE_TRACE_POINTS | |
43 | #include <trace/events/migrate.h> | |
44 | ||
45 | #include "internal.h" | |
46 | ||
47 | /* | |
48 | * migrate_prep() needs to be called before we start compiling a list of pages | |
49 | * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is | |
50 | * undesirable, use migrate_prep_local() | |
51 | */ | |
52 | int migrate_prep(void) | |
53 | { | |
54 | /* | |
55 | * Clear the LRU lists so pages can be isolated. | |
56 | * Note that pages may be moved off the LRU after we have | |
57 | * drained them. Those pages will fail to migrate like other | |
58 | * pages that may be busy. | |
59 | */ | |
60 | lru_add_drain_all(); | |
61 | ||
62 | return 0; | |
63 | } | |
64 | ||
65 | /* Do the necessary work of migrate_prep but not if it involves other CPUs */ | |
66 | int migrate_prep_local(void) | |
67 | { | |
68 | lru_add_drain(); | |
69 | ||
70 | return 0; | |
71 | } | |
72 | ||
73 | /* | |
74 | * Add isolated pages on the list back to the LRU under page lock | |
75 | * to avoid leaking evictable pages back onto unevictable list. | |
76 | */ | |
77 | void putback_lru_pages(struct list_head *l) | |
78 | { | |
79 | struct page *page; | |
80 | struct page *page2; | |
81 | ||
82 | list_for_each_entry_safe(page, page2, l, lru) { | |
83 | list_del(&page->lru); | |
84 | dec_zone_page_state(page, NR_ISOLATED_ANON + | |
85 | page_is_file_cache(page)); | |
86 | putback_lru_page(page); | |
87 | } | |
88 | } | |
89 | ||
90 | /* | |
91 | * Put previously isolated pages back onto the appropriate lists | |
92 | * from where they were once taken off for compaction/migration. | |
93 | * | |
94 | * This function shall be used instead of putback_lru_pages(), | |
95 | * whenever the isolated pageset has been built by isolate_migratepages_range() | |
96 | */ | |
97 | void putback_movable_pages(struct list_head *l) | |
98 | { | |
99 | struct page *page; | |
100 | struct page *page2; | |
101 | ||
102 | list_for_each_entry_safe(page, page2, l, lru) { | |
103 | list_del(&page->lru); | |
104 | dec_zone_page_state(page, NR_ISOLATED_ANON + | |
105 | page_is_file_cache(page)); | |
106 | if (unlikely(balloon_page_movable(page))) | |
107 | balloon_page_putback(page); | |
108 | else | |
109 | putback_lru_page(page); | |
110 | } | |
111 | } | |
112 | ||
113 | /* | |
114 | * Restore a potential migration pte to a working pte entry | |
115 | */ | |
116 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, | |
117 | unsigned long addr, void *old) | |
118 | { | |
119 | struct mm_struct *mm = vma->vm_mm; | |
120 | swp_entry_t entry; | |
121 | pmd_t *pmd; | |
122 | pte_t *ptep, pte; | |
123 | spinlock_t *ptl; | |
124 | ||
125 | if (unlikely(PageHuge(new))) { | |
126 | ptep = huge_pte_offset(mm, addr); | |
127 | if (!ptep) | |
128 | goto out; | |
129 | ptl = &mm->page_table_lock; | |
130 | } else { | |
131 | pmd = mm_find_pmd(mm, addr); | |
132 | if (!pmd) | |
133 | goto out; | |
134 | if (pmd_trans_huge(*pmd)) | |
135 | goto out; | |
136 | ||
137 | ptep = pte_offset_map(pmd, addr); | |
138 | ||
139 | /* | |
140 | * Peek to check is_swap_pte() before taking ptlock? No, we | |
141 | * can race mremap's move_ptes(), which skips anon_vma lock. | |
142 | */ | |
143 | ||
144 | ptl = pte_lockptr(mm, pmd); | |
145 | } | |
146 | ||
147 | spin_lock(ptl); | |
148 | pte = *ptep; | |
149 | if (!is_swap_pte(pte)) | |
150 | goto unlock; | |
151 | ||
152 | entry = pte_to_swp_entry(pte); | |
153 | ||
154 | if (!is_migration_entry(entry) || | |
155 | migration_entry_to_page(entry) != old) | |
156 | goto unlock; | |
157 | ||
158 | get_page(new); | |
159 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
160 | if (is_write_migration_entry(entry)) | |
161 | pte = pte_mkwrite(pte); | |
162 | #ifdef CONFIG_HUGETLB_PAGE | |
163 | if (PageHuge(new)) { | |
164 | pte = pte_mkhuge(pte); | |
165 | pte = arch_make_huge_pte(pte, vma, new, 0); | |
166 | } | |
167 | #endif | |
168 | flush_cache_page(vma, addr, pte_pfn(pte)); | |
169 | set_pte_at(mm, addr, ptep, pte); | |
170 | ||
171 | if (PageHuge(new)) { | |
172 | if (PageAnon(new)) | |
173 | hugepage_add_anon_rmap(new, vma, addr); | |
174 | else | |
175 | page_dup_rmap(new); | |
176 | } else if (PageAnon(new)) | |
177 | page_add_anon_rmap(new, vma, addr); | |
178 | else | |
179 | page_add_file_rmap(new); | |
180 | ||
181 | /* No need to invalidate - it was non-present before */ | |
182 | update_mmu_cache(vma, addr, ptep); | |
183 | unlock: | |
184 | pte_unmap_unlock(ptep, ptl); | |
185 | out: | |
186 | return SWAP_AGAIN; | |
187 | } | |
188 | ||
189 | /* | |
190 | * Get rid of all migration entries and replace them by | |
191 | * references to the indicated page. | |
192 | */ | |
193 | static void remove_migration_ptes(struct page *old, struct page *new) | |
194 | { | |
195 | rmap_walk(new, remove_migration_pte, old); | |
196 | } | |
197 | ||
198 | /* | |
199 | * Something used the pte of a page under migration. We need to | |
200 | * get to the page and wait until migration is finished. | |
201 | * When we return from this function the fault will be retried. | |
202 | */ | |
203 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
204 | unsigned long address) | |
205 | { | |
206 | pte_t *ptep, pte; | |
207 | spinlock_t *ptl; | |
208 | swp_entry_t entry; | |
209 | struct page *page; | |
210 | ||
211 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
212 | pte = *ptep; | |
213 | if (!is_swap_pte(pte)) | |
214 | goto out; | |
215 | ||
216 | entry = pte_to_swp_entry(pte); | |
217 | if (!is_migration_entry(entry)) | |
218 | goto out; | |
219 | ||
220 | page = migration_entry_to_page(entry); | |
221 | ||
222 | /* | |
223 | * Once radix-tree replacement of page migration started, page_count | |
224 | * *must* be zero. And, we don't want to call wait_on_page_locked() | |
225 | * against a page without get_page(). | |
226 | * So, we use get_page_unless_zero(), here. Even failed, page fault | |
227 | * will occur again. | |
228 | */ | |
229 | if (!get_page_unless_zero(page)) | |
230 | goto out; | |
231 | pte_unmap_unlock(ptep, ptl); | |
232 | wait_on_page_locked(page); | |
233 | put_page(page); | |
234 | return; | |
235 | out: | |
236 | pte_unmap_unlock(ptep, ptl); | |
237 | } | |
238 | ||
239 | #ifdef CONFIG_BLOCK | |
240 | /* Returns true if all buffers are successfully locked */ | |
241 | static bool buffer_migrate_lock_buffers(struct buffer_head *head, | |
242 | enum migrate_mode mode) | |
243 | { | |
244 | struct buffer_head *bh = head; | |
245 | ||
246 | /* Simple case, sync compaction */ | |
247 | if (mode != MIGRATE_ASYNC) { | |
248 | do { | |
249 | get_bh(bh); | |
250 | lock_buffer(bh); | |
251 | bh = bh->b_this_page; | |
252 | ||
253 | } while (bh != head); | |
254 | ||
255 | return true; | |
256 | } | |
257 | ||
258 | /* async case, we cannot block on lock_buffer so use trylock_buffer */ | |
259 | do { | |
260 | get_bh(bh); | |
261 | if (!trylock_buffer(bh)) { | |
262 | /* | |
263 | * We failed to lock the buffer and cannot stall in | |
264 | * async migration. Release the taken locks | |
265 | */ | |
266 | struct buffer_head *failed_bh = bh; | |
267 | put_bh(failed_bh); | |
268 | bh = head; | |
269 | while (bh != failed_bh) { | |
270 | unlock_buffer(bh); | |
271 | put_bh(bh); | |
272 | bh = bh->b_this_page; | |
273 | } | |
274 | return false; | |
275 | } | |
276 | ||
277 | bh = bh->b_this_page; | |
278 | } while (bh != head); | |
279 | return true; | |
280 | } | |
281 | #else | |
282 | static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, | |
283 | enum migrate_mode mode) | |
284 | { | |
285 | return true; | |
286 | } | |
287 | #endif /* CONFIG_BLOCK */ | |
288 | ||
289 | /* | |
290 | * Replace the page in the mapping. | |
291 | * | |
292 | * The number of remaining references must be: | |
293 | * 1 for anonymous pages without a mapping | |
294 | * 2 for pages with a mapping | |
295 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. | |
296 | */ | |
297 | static int migrate_page_move_mapping(struct address_space *mapping, | |
298 | struct page *newpage, struct page *page, | |
299 | struct buffer_head *head, enum migrate_mode mode) | |
300 | { | |
301 | int expected_count = 0; | |
302 | void **pslot; | |
303 | ||
304 | if (!mapping) { | |
305 | /* Anonymous page without mapping */ | |
306 | if (page_count(page) != 1) | |
307 | return -EAGAIN; | |
308 | return MIGRATEPAGE_SUCCESS; | |
309 | } | |
310 | ||
311 | spin_lock_irq(&mapping->tree_lock); | |
312 | ||
313 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
314 | page_index(page)); | |
315 | ||
316 | expected_count = 2 + page_has_private(page); | |
317 | if (page_count(page) != expected_count || | |
318 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { | |
319 | spin_unlock_irq(&mapping->tree_lock); | |
320 | return -EAGAIN; | |
321 | } | |
322 | ||
323 | if (!page_freeze_refs(page, expected_count)) { | |
324 | spin_unlock_irq(&mapping->tree_lock); | |
325 | return -EAGAIN; | |
326 | } | |
327 | ||
328 | /* | |
329 | * In the async migration case of moving a page with buffers, lock the | |
330 | * buffers using trylock before the mapping is moved. If the mapping | |
331 | * was moved, we later failed to lock the buffers and could not move | |
332 | * the mapping back due to an elevated page count, we would have to | |
333 | * block waiting on other references to be dropped. | |
334 | */ | |
335 | if (mode == MIGRATE_ASYNC && head && | |
336 | !buffer_migrate_lock_buffers(head, mode)) { | |
337 | page_unfreeze_refs(page, expected_count); | |
338 | spin_unlock_irq(&mapping->tree_lock); | |
339 | return -EAGAIN; | |
340 | } | |
341 | ||
342 | /* | |
343 | * Now we know that no one else is looking at the page. | |
344 | */ | |
345 | get_page(newpage); /* add cache reference */ | |
346 | if (PageSwapCache(page)) { | |
347 | SetPageSwapCache(newpage); | |
348 | set_page_private(newpage, page_private(page)); | |
349 | } | |
350 | ||
351 | radix_tree_replace_slot(pslot, newpage); | |
352 | ||
353 | /* | |
354 | * Drop cache reference from old page by unfreezing | |
355 | * to one less reference. | |
356 | * We know this isn't the last reference. | |
357 | */ | |
358 | page_unfreeze_refs(page, expected_count - 1); | |
359 | ||
360 | /* | |
361 | * If moved to a different zone then also account | |
362 | * the page for that zone. Other VM counters will be | |
363 | * taken care of when we establish references to the | |
364 | * new page and drop references to the old page. | |
365 | * | |
366 | * Note that anonymous pages are accounted for | |
367 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
368 | * are mapped to swap space. | |
369 | */ | |
370 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
371 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
372 | if (!PageSwapCache(page) && PageSwapBacked(page)) { | |
373 | __dec_zone_page_state(page, NR_SHMEM); | |
374 | __inc_zone_page_state(newpage, NR_SHMEM); | |
375 | } | |
376 | spin_unlock_irq(&mapping->tree_lock); | |
377 | ||
378 | return MIGRATEPAGE_SUCCESS; | |
379 | } | |
380 | ||
381 | /* | |
382 | * The expected number of remaining references is the same as that | |
383 | * of migrate_page_move_mapping(). | |
384 | */ | |
385 | int migrate_huge_page_move_mapping(struct address_space *mapping, | |
386 | struct page *newpage, struct page *page) | |
387 | { | |
388 | int expected_count; | |
389 | void **pslot; | |
390 | ||
391 | if (!mapping) { | |
392 | if (page_count(page) != 1) | |
393 | return -EAGAIN; | |
394 | return MIGRATEPAGE_SUCCESS; | |
395 | } | |
396 | ||
397 | spin_lock_irq(&mapping->tree_lock); | |
398 | ||
399 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
400 | page_index(page)); | |
401 | ||
402 | expected_count = 2 + page_has_private(page); | |
403 | if (page_count(page) != expected_count || | |
404 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { | |
405 | spin_unlock_irq(&mapping->tree_lock); | |
406 | return -EAGAIN; | |
407 | } | |
408 | ||
409 | if (!page_freeze_refs(page, expected_count)) { | |
410 | spin_unlock_irq(&mapping->tree_lock); | |
411 | return -EAGAIN; | |
412 | } | |
413 | ||
414 | get_page(newpage); | |
415 | ||
416 | radix_tree_replace_slot(pslot, newpage); | |
417 | ||
418 | page_unfreeze_refs(page, expected_count - 1); | |
419 | ||
420 | spin_unlock_irq(&mapping->tree_lock); | |
421 | return MIGRATEPAGE_SUCCESS; | |
422 | } | |
423 | ||
424 | /* | |
425 | * Copy the page to its new location | |
426 | */ | |
427 | void migrate_page_copy(struct page *newpage, struct page *page) | |
428 | { | |
429 | if (PageHuge(page) || PageTransHuge(page)) | |
430 | copy_huge_page(newpage, page); | |
431 | else | |
432 | copy_highpage(newpage, page); | |
433 | ||
434 | if (PageError(page)) | |
435 | SetPageError(newpage); | |
436 | if (PageReferenced(page)) | |
437 | SetPageReferenced(newpage); | |
438 | if (PageUptodate(page)) | |
439 | SetPageUptodate(newpage); | |
440 | if (TestClearPageActive(page)) { | |
441 | VM_BUG_ON(PageUnevictable(page)); | |
442 | SetPageActive(newpage); | |
443 | } else if (TestClearPageUnevictable(page)) | |
444 | SetPageUnevictable(newpage); | |
445 | if (PageChecked(page)) | |
446 | SetPageChecked(newpage); | |
447 | if (PageMappedToDisk(page)) | |
448 | SetPageMappedToDisk(newpage); | |
449 | ||
450 | if (PageDirty(page)) { | |
451 | clear_page_dirty_for_io(page); | |
452 | /* | |
453 | * Want to mark the page and the radix tree as dirty, and | |
454 | * redo the accounting that clear_page_dirty_for_io undid, | |
455 | * but we can't use set_page_dirty because that function | |
456 | * is actually a signal that all of the page has become dirty. | |
457 | * Whereas only part of our page may be dirty. | |
458 | */ | |
459 | if (PageSwapBacked(page)) | |
460 | SetPageDirty(newpage); | |
461 | else | |
462 | __set_page_dirty_nobuffers(newpage); | |
463 | } | |
464 | ||
465 | mlock_migrate_page(newpage, page); | |
466 | ksm_migrate_page(newpage, page); | |
467 | ||
468 | ClearPageSwapCache(page); | |
469 | ClearPagePrivate(page); | |
470 | set_page_private(page, 0); | |
471 | ||
472 | /* | |
473 | * If any waiters have accumulated on the new page then | |
474 | * wake them up. | |
475 | */ | |
476 | if (PageWriteback(newpage)) | |
477 | end_page_writeback(newpage); | |
478 | } | |
479 | ||
480 | /************************************************************ | |
481 | * Migration functions | |
482 | ***********************************************************/ | |
483 | ||
484 | /* Always fail migration. Used for mappings that are not movable */ | |
485 | int fail_migrate_page(struct address_space *mapping, | |
486 | struct page *newpage, struct page *page) | |
487 | { | |
488 | return -EIO; | |
489 | } | |
490 | EXPORT_SYMBOL(fail_migrate_page); | |
491 | ||
492 | /* | |
493 | * Common logic to directly migrate a single page suitable for | |
494 | * pages that do not use PagePrivate/PagePrivate2. | |
495 | * | |
496 | * Pages are locked upon entry and exit. | |
497 | */ | |
498 | int migrate_page(struct address_space *mapping, | |
499 | struct page *newpage, struct page *page, | |
500 | enum migrate_mode mode) | |
501 | { | |
502 | int rc; | |
503 | ||
504 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
505 | ||
506 | rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode); | |
507 | ||
508 | if (rc != MIGRATEPAGE_SUCCESS) | |
509 | return rc; | |
510 | ||
511 | migrate_page_copy(newpage, page); | |
512 | return MIGRATEPAGE_SUCCESS; | |
513 | } | |
514 | EXPORT_SYMBOL(migrate_page); | |
515 | ||
516 | #ifdef CONFIG_BLOCK | |
517 | /* | |
518 | * Migration function for pages with buffers. This function can only be used | |
519 | * if the underlying filesystem guarantees that no other references to "page" | |
520 | * exist. | |
521 | */ | |
522 | int buffer_migrate_page(struct address_space *mapping, | |
523 | struct page *newpage, struct page *page, enum migrate_mode mode) | |
524 | { | |
525 | struct buffer_head *bh, *head; | |
526 | int rc; | |
527 | ||
528 | if (!page_has_buffers(page)) | |
529 | return migrate_page(mapping, newpage, page, mode); | |
530 | ||
531 | head = page_buffers(page); | |
532 | ||
533 | rc = migrate_page_move_mapping(mapping, newpage, page, head, mode); | |
534 | ||
535 | if (rc != MIGRATEPAGE_SUCCESS) | |
536 | return rc; | |
537 | ||
538 | /* | |
539 | * In the async case, migrate_page_move_mapping locked the buffers | |
540 | * with an IRQ-safe spinlock held. In the sync case, the buffers | |
541 | * need to be locked now | |
542 | */ | |
543 | if (mode != MIGRATE_ASYNC) | |
544 | BUG_ON(!buffer_migrate_lock_buffers(head, mode)); | |
545 | ||
546 | ClearPagePrivate(page); | |
547 | set_page_private(newpage, page_private(page)); | |
548 | set_page_private(page, 0); | |
549 | put_page(page); | |
550 | get_page(newpage); | |
551 | ||
552 | bh = head; | |
553 | do { | |
554 | set_bh_page(bh, newpage, bh_offset(bh)); | |
555 | bh = bh->b_this_page; | |
556 | ||
557 | } while (bh != head); | |
558 | ||
559 | SetPagePrivate(newpage); | |
560 | ||
561 | migrate_page_copy(newpage, page); | |
562 | ||
563 | bh = head; | |
564 | do { | |
565 | unlock_buffer(bh); | |
566 | put_bh(bh); | |
567 | bh = bh->b_this_page; | |
568 | ||
569 | } while (bh != head); | |
570 | ||
571 | return MIGRATEPAGE_SUCCESS; | |
572 | } | |
573 | EXPORT_SYMBOL(buffer_migrate_page); | |
574 | #endif | |
575 | ||
576 | /* | |
577 | * Writeback a page to clean the dirty state | |
578 | */ | |
579 | static int writeout(struct address_space *mapping, struct page *page) | |
580 | { | |
581 | struct writeback_control wbc = { | |
582 | .sync_mode = WB_SYNC_NONE, | |
583 | .nr_to_write = 1, | |
584 | .range_start = 0, | |
585 | .range_end = LLONG_MAX, | |
586 | .for_reclaim = 1 | |
587 | }; | |
588 | int rc; | |
589 | ||
590 | if (!mapping->a_ops->writepage) | |
591 | /* No write method for the address space */ | |
592 | return -EINVAL; | |
593 | ||
594 | if (!clear_page_dirty_for_io(page)) | |
595 | /* Someone else already triggered a write */ | |
596 | return -EAGAIN; | |
597 | ||
598 | /* | |
599 | * A dirty page may imply that the underlying filesystem has | |
600 | * the page on some queue. So the page must be clean for | |
601 | * migration. Writeout may mean we loose the lock and the | |
602 | * page state is no longer what we checked for earlier. | |
603 | * At this point we know that the migration attempt cannot | |
604 | * be successful. | |
605 | */ | |
606 | remove_migration_ptes(page, page); | |
607 | ||
608 | rc = mapping->a_ops->writepage(page, &wbc); | |
609 | ||
610 | if (rc != AOP_WRITEPAGE_ACTIVATE) | |
611 | /* unlocked. Relock */ | |
612 | lock_page(page); | |
613 | ||
614 | return (rc < 0) ? -EIO : -EAGAIN; | |
615 | } | |
616 | ||
617 | /* | |
618 | * Default handling if a filesystem does not provide a migration function. | |
619 | */ | |
620 | static int fallback_migrate_page(struct address_space *mapping, | |
621 | struct page *newpage, struct page *page, enum migrate_mode mode) | |
622 | { | |
623 | if (PageDirty(page)) { | |
624 | /* Only writeback pages in full synchronous migration */ | |
625 | if (mode != MIGRATE_SYNC) | |
626 | return -EBUSY; | |
627 | return writeout(mapping, page); | |
628 | } | |
629 | ||
630 | /* | |
631 | * Buffers may be managed in a filesystem specific way. | |
632 | * We must have no buffers or drop them. | |
633 | */ | |
634 | if (page_has_private(page) && | |
635 | !try_to_release_page(page, GFP_KERNEL)) | |
636 | return -EAGAIN; | |
637 | ||
638 | return migrate_page(mapping, newpage, page, mode); | |
639 | } | |
640 | ||
641 | /* | |
642 | * Move a page to a newly allocated page | |
643 | * The page is locked and all ptes have been successfully removed. | |
644 | * | |
645 | * The new page will have replaced the old page if this function | |
646 | * is successful. | |
647 | * | |
648 | * Return value: | |
649 | * < 0 - error code | |
650 | * MIGRATEPAGE_SUCCESS - success | |
651 | */ | |
652 | static int move_to_new_page(struct page *newpage, struct page *page, | |
653 | int remap_swapcache, enum migrate_mode mode) | |
654 | { | |
655 | struct address_space *mapping; | |
656 | int rc; | |
657 | ||
658 | /* | |
659 | * Block others from accessing the page when we get around to | |
660 | * establishing additional references. We are the only one | |
661 | * holding a reference to the new page at this point. | |
662 | */ | |
663 | if (!trylock_page(newpage)) | |
664 | BUG(); | |
665 | ||
666 | /* Prepare mapping for the new page.*/ | |
667 | newpage->index = page->index; | |
668 | newpage->mapping = page->mapping; | |
669 | if (PageSwapBacked(page)) | |
670 | SetPageSwapBacked(newpage); | |
671 | ||
672 | mapping = page_mapping(page); | |
673 | if (!mapping) | |
674 | rc = migrate_page(mapping, newpage, page, mode); | |
675 | else if (mapping->a_ops->migratepage) | |
676 | /* | |
677 | * Most pages have a mapping and most filesystems provide a | |
678 | * migratepage callback. Anonymous pages are part of swap | |
679 | * space which also has its own migratepage callback. This | |
680 | * is the most common path for page migration. | |
681 | */ | |
682 | rc = mapping->a_ops->migratepage(mapping, | |
683 | newpage, page, mode); | |
684 | else | |
685 | rc = fallback_migrate_page(mapping, newpage, page, mode); | |
686 | ||
687 | if (rc != MIGRATEPAGE_SUCCESS) { | |
688 | newpage->mapping = NULL; | |
689 | } else { | |
690 | if (remap_swapcache) | |
691 | remove_migration_ptes(page, newpage); | |
692 | page->mapping = NULL; | |
693 | } | |
694 | ||
695 | unlock_page(newpage); | |
696 | ||
697 | return rc; | |
698 | } | |
699 | ||
700 | static int __unmap_and_move(struct page *page, struct page *newpage, | |
701 | int force, bool offlining, enum migrate_mode mode) | |
702 | { | |
703 | int rc = -EAGAIN; | |
704 | int remap_swapcache = 1; | |
705 | struct mem_cgroup *mem; | |
706 | struct anon_vma *anon_vma = NULL; | |
707 | ||
708 | if (!trylock_page(page)) { | |
709 | if (!force || mode == MIGRATE_ASYNC) | |
710 | goto out; | |
711 | ||
712 | /* | |
713 | * It's not safe for direct compaction to call lock_page. | |
714 | * For example, during page readahead pages are added locked | |
715 | * to the LRU. Later, when the IO completes the pages are | |
716 | * marked uptodate and unlocked. However, the queueing | |
717 | * could be merging multiple pages for one bio (e.g. | |
718 | * mpage_readpages). If an allocation happens for the | |
719 | * second or third page, the process can end up locking | |
720 | * the same page twice and deadlocking. Rather than | |
721 | * trying to be clever about what pages can be locked, | |
722 | * avoid the use of lock_page for direct compaction | |
723 | * altogether. | |
724 | */ | |
725 | if (current->flags & PF_MEMALLOC) | |
726 | goto out; | |
727 | ||
728 | lock_page(page); | |
729 | } | |
730 | ||
731 | /* | |
732 | * Only memory hotplug's offline_pages() caller has locked out KSM, | |
733 | * and can safely migrate a KSM page. The other cases have skipped | |
734 | * PageKsm along with PageReserved - but it is only now when we have | |
735 | * the page lock that we can be certain it will not go KSM beneath us | |
736 | * (KSM will not upgrade a page from PageAnon to PageKsm when it sees | |
737 | * its pagecount raised, but only here do we take the page lock which | |
738 | * serializes that). | |
739 | */ | |
740 | if (PageKsm(page) && !offlining) { | |
741 | rc = -EBUSY; | |
742 | goto unlock; | |
743 | } | |
744 | ||
745 | /* charge against new page */ | |
746 | mem_cgroup_prepare_migration(page, newpage, &mem); | |
747 | ||
748 | if (PageWriteback(page)) { | |
749 | /* | |
750 | * Only in the case of a full syncronous migration is it | |
751 | * necessary to wait for PageWriteback. In the async case, | |
752 | * the retry loop is too short and in the sync-light case, | |
753 | * the overhead of stalling is too much | |
754 | */ | |
755 | if (mode != MIGRATE_SYNC) { | |
756 | rc = -EBUSY; | |
757 | goto uncharge; | |
758 | } | |
759 | if (!force) | |
760 | goto uncharge; | |
761 | wait_on_page_writeback(page); | |
762 | } | |
763 | /* | |
764 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, | |
765 | * we cannot notice that anon_vma is freed while we migrates a page. | |
766 | * This get_anon_vma() delays freeing anon_vma pointer until the end | |
767 | * of migration. File cache pages are no problem because of page_lock() | |
768 | * File Caches may use write_page() or lock_page() in migration, then, | |
769 | * just care Anon page here. | |
770 | */ | |
771 | if (PageAnon(page)) { | |
772 | /* | |
773 | * Only page_lock_anon_vma_read() understands the subtleties of | |
774 | * getting a hold on an anon_vma from outside one of its mms. | |
775 | */ | |
776 | anon_vma = page_get_anon_vma(page); | |
777 | if (anon_vma) { | |
778 | /* | |
779 | * Anon page | |
780 | */ | |
781 | } else if (PageSwapCache(page)) { | |
782 | /* | |
783 | * We cannot be sure that the anon_vma of an unmapped | |
784 | * swapcache page is safe to use because we don't | |
785 | * know in advance if the VMA that this page belonged | |
786 | * to still exists. If the VMA and others sharing the | |
787 | * data have been freed, then the anon_vma could | |
788 | * already be invalid. | |
789 | * | |
790 | * To avoid this possibility, swapcache pages get | |
791 | * migrated but are not remapped when migration | |
792 | * completes | |
793 | */ | |
794 | remap_swapcache = 0; | |
795 | } else { | |
796 | goto uncharge; | |
797 | } | |
798 | } | |
799 | ||
800 | if (unlikely(balloon_page_movable(page))) { | |
801 | /* | |
802 | * A ballooned page does not need any special attention from | |
803 | * physical to virtual reverse mapping procedures. | |
804 | * Skip any attempt to unmap PTEs or to remap swap cache, | |
805 | * in order to avoid burning cycles at rmap level, and perform | |
806 | * the page migration right away (proteced by page lock). | |
807 | */ | |
808 | rc = balloon_page_migrate(newpage, page, mode); | |
809 | goto uncharge; | |
810 | } | |
811 | ||
812 | /* | |
813 | * Corner case handling: | |
814 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
815 | * and treated as swapcache but it has no rmap yet. | |
816 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
817 | * trigger a BUG. So handle it here. | |
818 | * 2. An orphaned page (see truncate_complete_page) might have | |
819 | * fs-private metadata. The page can be picked up due to memory | |
820 | * offlining. Everywhere else except page reclaim, the page is | |
821 | * invisible to the vm, so the page can not be migrated. So try to | |
822 | * free the metadata, so the page can be freed. | |
823 | */ | |
824 | if (!page->mapping) { | |
825 | VM_BUG_ON(PageAnon(page)); | |
826 | if (page_has_private(page)) { | |
827 | try_to_free_buffers(page); | |
828 | goto uncharge; | |
829 | } | |
830 | goto skip_unmap; | |
831 | } | |
832 | ||
833 | /* Establish migration ptes or remove ptes */ | |
834 | try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); | |
835 | ||
836 | skip_unmap: | |
837 | if (!page_mapped(page)) | |
838 | rc = move_to_new_page(newpage, page, remap_swapcache, mode); | |
839 | ||
840 | if (rc && remap_swapcache) | |
841 | remove_migration_ptes(page, page); | |
842 | ||
843 | /* Drop an anon_vma reference if we took one */ | |
844 | if (anon_vma) | |
845 | put_anon_vma(anon_vma); | |
846 | ||
847 | uncharge: | |
848 | mem_cgroup_end_migration(mem, page, newpage, | |
849 | (rc == MIGRATEPAGE_SUCCESS || | |
850 | rc == MIGRATEPAGE_BALLOON_SUCCESS)); | |
851 | unlock: | |
852 | unlock_page(page); | |
853 | out: | |
854 | return rc; | |
855 | } | |
856 | ||
857 | /* | |
858 | * Obtain the lock on page, remove all ptes and migrate the page | |
859 | * to the newly allocated page in newpage. | |
860 | */ | |
861 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, | |
862 | struct page *page, int force, bool offlining, | |
863 | enum migrate_mode mode) | |
864 | { | |
865 | int rc = 0; | |
866 | int *result = NULL; | |
867 | struct page *newpage = get_new_page(page, private, &result); | |
868 | ||
869 | if (!newpage) | |
870 | return -ENOMEM; | |
871 | ||
872 | if (page_count(page) == 1) { | |
873 | /* page was freed from under us. So we are done. */ | |
874 | goto out; | |
875 | } | |
876 | ||
877 | if (unlikely(PageTransHuge(page))) | |
878 | if (unlikely(split_huge_page(page))) | |
879 | goto out; | |
880 | ||
881 | rc = __unmap_and_move(page, newpage, force, offlining, mode); | |
882 | ||
883 | if (unlikely(rc == MIGRATEPAGE_BALLOON_SUCCESS)) { | |
884 | /* | |
885 | * A ballooned page has been migrated already. | |
886 | * Now, it's the time to wrap-up counters, | |
887 | * handle the page back to Buddy and return. | |
888 | */ | |
889 | dec_zone_page_state(page, NR_ISOLATED_ANON + | |
890 | page_is_file_cache(page)); | |
891 | balloon_page_free(page); | |
892 | return MIGRATEPAGE_SUCCESS; | |
893 | } | |
894 | out: | |
895 | if (rc != -EAGAIN) { | |
896 | /* | |
897 | * A page that has been migrated has all references | |
898 | * removed and will be freed. A page that has not been | |
899 | * migrated will have kepts its references and be | |
900 | * restored. | |
901 | */ | |
902 | list_del(&page->lru); | |
903 | dec_zone_page_state(page, NR_ISOLATED_ANON + | |
904 | page_is_file_cache(page)); | |
905 | putback_lru_page(page); | |
906 | } | |
907 | /* | |
908 | * Move the new page to the LRU. If migration was not successful | |
909 | * then this will free the page. | |
910 | */ | |
911 | putback_lru_page(newpage); | |
912 | if (result) { | |
913 | if (rc) | |
914 | *result = rc; | |
915 | else | |
916 | *result = page_to_nid(newpage); | |
917 | } | |
918 | return rc; | |
919 | } | |
920 | ||
921 | /* | |
922 | * Counterpart of unmap_and_move_page() for hugepage migration. | |
923 | * | |
924 | * This function doesn't wait the completion of hugepage I/O | |
925 | * because there is no race between I/O and migration for hugepage. | |
926 | * Note that currently hugepage I/O occurs only in direct I/O | |
927 | * where no lock is held and PG_writeback is irrelevant, | |
928 | * and writeback status of all subpages are counted in the reference | |
929 | * count of the head page (i.e. if all subpages of a 2MB hugepage are | |
930 | * under direct I/O, the reference of the head page is 512 and a bit more.) | |
931 | * This means that when we try to migrate hugepage whose subpages are | |
932 | * doing direct I/O, some references remain after try_to_unmap() and | |
933 | * hugepage migration fails without data corruption. | |
934 | * | |
935 | * There is also no race when direct I/O is issued on the page under migration, | |
936 | * because then pte is replaced with migration swap entry and direct I/O code | |
937 | * will wait in the page fault for migration to complete. | |
938 | */ | |
939 | static int unmap_and_move_huge_page(new_page_t get_new_page, | |
940 | unsigned long private, struct page *hpage, | |
941 | int force, bool offlining, | |
942 | enum migrate_mode mode) | |
943 | { | |
944 | int rc = 0; | |
945 | int *result = NULL; | |
946 | struct page *new_hpage = get_new_page(hpage, private, &result); | |
947 | struct anon_vma *anon_vma = NULL; | |
948 | ||
949 | if (!new_hpage) | |
950 | return -ENOMEM; | |
951 | ||
952 | rc = -EAGAIN; | |
953 | ||
954 | if (!trylock_page(hpage)) { | |
955 | if (!force || mode != MIGRATE_SYNC) | |
956 | goto out; | |
957 | lock_page(hpage); | |
958 | } | |
959 | ||
960 | if (PageAnon(hpage)) | |
961 | anon_vma = page_get_anon_vma(hpage); | |
962 | ||
963 | try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); | |
964 | ||
965 | if (!page_mapped(hpage)) | |
966 | rc = move_to_new_page(new_hpage, hpage, 1, mode); | |
967 | ||
968 | if (rc) | |
969 | remove_migration_ptes(hpage, hpage); | |
970 | ||
971 | if (anon_vma) | |
972 | put_anon_vma(anon_vma); | |
973 | ||
974 | if (!rc) | |
975 | hugetlb_cgroup_migrate(hpage, new_hpage); | |
976 | ||
977 | unlock_page(hpage); | |
978 | out: | |
979 | put_page(new_hpage); | |
980 | if (result) { | |
981 | if (rc) | |
982 | *result = rc; | |
983 | else | |
984 | *result = page_to_nid(new_hpage); | |
985 | } | |
986 | return rc; | |
987 | } | |
988 | ||
989 | /* | |
990 | * migrate_pages | |
991 | * | |
992 | * The function takes one list of pages to migrate and a function | |
993 | * that determines from the page to be migrated and the private data | |
994 | * the target of the move and allocates the page. | |
995 | * | |
996 | * The function returns after 10 attempts or if no pages | |
997 | * are movable anymore because to has become empty | |
998 | * or no retryable pages exist anymore. | |
999 | * Caller should call putback_lru_pages to return pages to the LRU | |
1000 | * or free list only if ret != 0. | |
1001 | * | |
1002 | * Return: Number of pages not migrated or error code. | |
1003 | */ | |
1004 | int migrate_pages(struct list_head *from, | |
1005 | new_page_t get_new_page, unsigned long private, bool offlining, | |
1006 | enum migrate_mode mode, int reason) | |
1007 | { | |
1008 | int retry = 1; | |
1009 | int nr_failed = 0; | |
1010 | int nr_succeeded = 0; | |
1011 | int pass = 0; | |
1012 | struct page *page; | |
1013 | struct page *page2; | |
1014 | int swapwrite = current->flags & PF_SWAPWRITE; | |
1015 | int rc; | |
1016 | ||
1017 | if (!swapwrite) | |
1018 | current->flags |= PF_SWAPWRITE; | |
1019 | ||
1020 | for(pass = 0; pass < 10 && retry; pass++) { | |
1021 | retry = 0; | |
1022 | ||
1023 | list_for_each_entry_safe(page, page2, from, lru) { | |
1024 | cond_resched(); | |
1025 | ||
1026 | rc = unmap_and_move(get_new_page, private, | |
1027 | page, pass > 2, offlining, | |
1028 | mode); | |
1029 | ||
1030 | switch(rc) { | |
1031 | case -ENOMEM: | |
1032 | goto out; | |
1033 | case -EAGAIN: | |
1034 | retry++; | |
1035 | break; | |
1036 | case MIGRATEPAGE_SUCCESS: | |
1037 | nr_succeeded++; | |
1038 | break; | |
1039 | default: | |
1040 | /* Permanent failure */ | |
1041 | nr_failed++; | |
1042 | break; | |
1043 | } | |
1044 | } | |
1045 | } | |
1046 | rc = nr_failed + retry; | |
1047 | out: | |
1048 | if (nr_succeeded) | |
1049 | count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); | |
1050 | if (nr_failed) | |
1051 | count_vm_events(PGMIGRATE_FAIL, nr_failed); | |
1052 | trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); | |
1053 | ||
1054 | if (!swapwrite) | |
1055 | current->flags &= ~PF_SWAPWRITE; | |
1056 | ||
1057 | return rc; | |
1058 | } | |
1059 | ||
1060 | int migrate_huge_page(struct page *hpage, new_page_t get_new_page, | |
1061 | unsigned long private, bool offlining, | |
1062 | enum migrate_mode mode) | |
1063 | { | |
1064 | int pass, rc; | |
1065 | ||
1066 | for (pass = 0; pass < 10; pass++) { | |
1067 | rc = unmap_and_move_huge_page(get_new_page, | |
1068 | private, hpage, pass > 2, offlining, | |
1069 | mode); | |
1070 | switch (rc) { | |
1071 | case -ENOMEM: | |
1072 | goto out; | |
1073 | case -EAGAIN: | |
1074 | /* try again */ | |
1075 | cond_resched(); | |
1076 | break; | |
1077 | case MIGRATEPAGE_SUCCESS: | |
1078 | goto out; | |
1079 | default: | |
1080 | rc = -EIO; | |
1081 | goto out; | |
1082 | } | |
1083 | } | |
1084 | out: | |
1085 | return rc; | |
1086 | } | |
1087 | ||
1088 | #ifdef CONFIG_NUMA | |
1089 | /* | |
1090 | * Move a list of individual pages | |
1091 | */ | |
1092 | struct page_to_node { | |
1093 | unsigned long addr; | |
1094 | struct page *page; | |
1095 | int node; | |
1096 | int status; | |
1097 | }; | |
1098 | ||
1099 | static struct page *new_page_node(struct page *p, unsigned long private, | |
1100 | int **result) | |
1101 | { | |
1102 | struct page_to_node *pm = (struct page_to_node *)private; | |
1103 | ||
1104 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
1105 | pm++; | |
1106 | ||
1107 | if (pm->node == MAX_NUMNODES) | |
1108 | return NULL; | |
1109 | ||
1110 | *result = &pm->status; | |
1111 | ||
1112 | return alloc_pages_exact_node(pm->node, | |
1113 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); | |
1114 | } | |
1115 | ||
1116 | /* | |
1117 | * Move a set of pages as indicated in the pm array. The addr | |
1118 | * field must be set to the virtual address of the page to be moved | |
1119 | * and the node number must contain a valid target node. | |
1120 | * The pm array ends with node = MAX_NUMNODES. | |
1121 | */ | |
1122 | static int do_move_page_to_node_array(struct mm_struct *mm, | |
1123 | struct page_to_node *pm, | |
1124 | int migrate_all) | |
1125 | { | |
1126 | int err; | |
1127 | struct page_to_node *pp; | |
1128 | LIST_HEAD(pagelist); | |
1129 | ||
1130 | down_read(&mm->mmap_sem); | |
1131 | ||
1132 | /* | |
1133 | * Build a list of pages to migrate | |
1134 | */ | |
1135 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { | |
1136 | struct vm_area_struct *vma; | |
1137 | struct page *page; | |
1138 | ||
1139 | err = -EFAULT; | |
1140 | vma = find_vma(mm, pp->addr); | |
1141 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) | |
1142 | goto set_status; | |
1143 | ||
1144 | page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT); | |
1145 | ||
1146 | err = PTR_ERR(page); | |
1147 | if (IS_ERR(page)) | |
1148 | goto set_status; | |
1149 | ||
1150 | err = -ENOENT; | |
1151 | if (!page) | |
1152 | goto set_status; | |
1153 | ||
1154 | /* Use PageReserved to check for zero page */ | |
1155 | if (PageReserved(page) || PageKsm(page)) | |
1156 | goto put_and_set; | |
1157 | ||
1158 | pp->page = page; | |
1159 | err = page_to_nid(page); | |
1160 | ||
1161 | if (err == pp->node) | |
1162 | /* | |
1163 | * Node already in the right place | |
1164 | */ | |
1165 | goto put_and_set; | |
1166 | ||
1167 | err = -EACCES; | |
1168 | if (page_mapcount(page) > 1 && | |
1169 | !migrate_all) | |
1170 | goto put_and_set; | |
1171 | ||
1172 | err = isolate_lru_page(page); | |
1173 | if (!err) { | |
1174 | list_add_tail(&page->lru, &pagelist); | |
1175 | inc_zone_page_state(page, NR_ISOLATED_ANON + | |
1176 | page_is_file_cache(page)); | |
1177 | } | |
1178 | put_and_set: | |
1179 | /* | |
1180 | * Either remove the duplicate refcount from | |
1181 | * isolate_lru_page() or drop the page ref if it was | |
1182 | * not isolated. | |
1183 | */ | |
1184 | put_page(page); | |
1185 | set_status: | |
1186 | pp->status = err; | |
1187 | } | |
1188 | ||
1189 | err = 0; | |
1190 | if (!list_empty(&pagelist)) { | |
1191 | err = migrate_pages(&pagelist, new_page_node, | |
1192 | (unsigned long)pm, 0, MIGRATE_SYNC, | |
1193 | MR_SYSCALL); | |
1194 | if (err) | |
1195 | putback_lru_pages(&pagelist); | |
1196 | } | |
1197 | ||
1198 | up_read(&mm->mmap_sem); | |
1199 | return err; | |
1200 | } | |
1201 | ||
1202 | /* | |
1203 | * Migrate an array of page address onto an array of nodes and fill | |
1204 | * the corresponding array of status. | |
1205 | */ | |
1206 | static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, | |
1207 | unsigned long nr_pages, | |
1208 | const void __user * __user *pages, | |
1209 | const int __user *nodes, | |
1210 | int __user *status, int flags) | |
1211 | { | |
1212 | struct page_to_node *pm; | |
1213 | unsigned long chunk_nr_pages; | |
1214 | unsigned long chunk_start; | |
1215 | int err; | |
1216 | ||
1217 | err = -ENOMEM; | |
1218 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); | |
1219 | if (!pm) | |
1220 | goto out; | |
1221 | ||
1222 | migrate_prep(); | |
1223 | ||
1224 | /* | |
1225 | * Store a chunk of page_to_node array in a page, | |
1226 | * but keep the last one as a marker | |
1227 | */ | |
1228 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; | |
1229 | ||
1230 | for (chunk_start = 0; | |
1231 | chunk_start < nr_pages; | |
1232 | chunk_start += chunk_nr_pages) { | |
1233 | int j; | |
1234 | ||
1235 | if (chunk_start + chunk_nr_pages > nr_pages) | |
1236 | chunk_nr_pages = nr_pages - chunk_start; | |
1237 | ||
1238 | /* fill the chunk pm with addrs and nodes from user-space */ | |
1239 | for (j = 0; j < chunk_nr_pages; j++) { | |
1240 | const void __user *p; | |
1241 | int node; | |
1242 | ||
1243 | err = -EFAULT; | |
1244 | if (get_user(p, pages + j + chunk_start)) | |
1245 | goto out_pm; | |
1246 | pm[j].addr = (unsigned long) p; | |
1247 | ||
1248 | if (get_user(node, nodes + j + chunk_start)) | |
1249 | goto out_pm; | |
1250 | ||
1251 | err = -ENODEV; | |
1252 | if (node < 0 || node >= MAX_NUMNODES) | |
1253 | goto out_pm; | |
1254 | ||
1255 | if (!node_state(node, N_MEMORY)) | |
1256 | goto out_pm; | |
1257 | ||
1258 | err = -EACCES; | |
1259 | if (!node_isset(node, task_nodes)) | |
1260 | goto out_pm; | |
1261 | ||
1262 | pm[j].node = node; | |
1263 | } | |
1264 | ||
1265 | /* End marker for this chunk */ | |
1266 | pm[chunk_nr_pages].node = MAX_NUMNODES; | |
1267 | ||
1268 | /* Migrate this chunk */ | |
1269 | err = do_move_page_to_node_array(mm, pm, | |
1270 | flags & MPOL_MF_MOVE_ALL); | |
1271 | if (err < 0) | |
1272 | goto out_pm; | |
1273 | ||
1274 | /* Return status information */ | |
1275 | for (j = 0; j < chunk_nr_pages; j++) | |
1276 | if (put_user(pm[j].status, status + j + chunk_start)) { | |
1277 | err = -EFAULT; | |
1278 | goto out_pm; | |
1279 | } | |
1280 | } | |
1281 | err = 0; | |
1282 | ||
1283 | out_pm: | |
1284 | free_page((unsigned long)pm); | |
1285 | out: | |
1286 | return err; | |
1287 | } | |
1288 | ||
1289 | /* | |
1290 | * Determine the nodes of an array of pages and store it in an array of status. | |
1291 | */ | |
1292 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, | |
1293 | const void __user **pages, int *status) | |
1294 | { | |
1295 | unsigned long i; | |
1296 | ||
1297 | down_read(&mm->mmap_sem); | |
1298 | ||
1299 | for (i = 0; i < nr_pages; i++) { | |
1300 | unsigned long addr = (unsigned long)(*pages); | |
1301 | struct vm_area_struct *vma; | |
1302 | struct page *page; | |
1303 | int err = -EFAULT; | |
1304 | ||
1305 | vma = find_vma(mm, addr); | |
1306 | if (!vma || addr < vma->vm_start) | |
1307 | goto set_status; | |
1308 | ||
1309 | page = follow_page(vma, addr, 0); | |
1310 | ||
1311 | err = PTR_ERR(page); | |
1312 | if (IS_ERR(page)) | |
1313 | goto set_status; | |
1314 | ||
1315 | err = -ENOENT; | |
1316 | /* Use PageReserved to check for zero page */ | |
1317 | if (!page || PageReserved(page) || PageKsm(page)) | |
1318 | goto set_status; | |
1319 | ||
1320 | err = page_to_nid(page); | |
1321 | set_status: | |
1322 | *status = err; | |
1323 | ||
1324 | pages++; | |
1325 | status++; | |
1326 | } | |
1327 | ||
1328 | up_read(&mm->mmap_sem); | |
1329 | } | |
1330 | ||
1331 | /* | |
1332 | * Determine the nodes of a user array of pages and store it in | |
1333 | * a user array of status. | |
1334 | */ | |
1335 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, | |
1336 | const void __user * __user *pages, | |
1337 | int __user *status) | |
1338 | { | |
1339 | #define DO_PAGES_STAT_CHUNK_NR 16 | |
1340 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; | |
1341 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; | |
1342 | ||
1343 | while (nr_pages) { | |
1344 | unsigned long chunk_nr; | |
1345 | ||
1346 | chunk_nr = nr_pages; | |
1347 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) | |
1348 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; | |
1349 | ||
1350 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) | |
1351 | break; | |
1352 | ||
1353 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); | |
1354 | ||
1355 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) | |
1356 | break; | |
1357 | ||
1358 | pages += chunk_nr; | |
1359 | status += chunk_nr; | |
1360 | nr_pages -= chunk_nr; | |
1361 | } | |
1362 | return nr_pages ? -EFAULT : 0; | |
1363 | } | |
1364 | ||
1365 | /* | |
1366 | * Move a list of pages in the address space of the currently executing | |
1367 | * process. | |
1368 | */ | |
1369 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, | |
1370 | const void __user * __user *, pages, | |
1371 | const int __user *, nodes, | |
1372 | int __user *, status, int, flags) | |
1373 | { | |
1374 | const struct cred *cred = current_cred(), *tcred; | |
1375 | struct task_struct *task; | |
1376 | struct mm_struct *mm; | |
1377 | int err; | |
1378 | nodemask_t task_nodes; | |
1379 | ||
1380 | /* Check flags */ | |
1381 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
1382 | return -EINVAL; | |
1383 | ||
1384 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
1385 | return -EPERM; | |
1386 | ||
1387 | /* Find the mm_struct */ | |
1388 | rcu_read_lock(); | |
1389 | task = pid ? find_task_by_vpid(pid) : current; | |
1390 | if (!task) { | |
1391 | rcu_read_unlock(); | |
1392 | return -ESRCH; | |
1393 | } | |
1394 | get_task_struct(task); | |
1395 | ||
1396 | /* | |
1397 | * Check if this process has the right to modify the specified | |
1398 | * process. The right exists if the process has administrative | |
1399 | * capabilities, superuser privileges or the same | |
1400 | * userid as the target process. | |
1401 | */ | |
1402 | tcred = __task_cred(task); | |
1403 | if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) && | |
1404 | !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) && | |
1405 | !capable(CAP_SYS_NICE)) { | |
1406 | rcu_read_unlock(); | |
1407 | err = -EPERM; | |
1408 | goto out; | |
1409 | } | |
1410 | rcu_read_unlock(); | |
1411 | ||
1412 | err = security_task_movememory(task); | |
1413 | if (err) | |
1414 | goto out; | |
1415 | ||
1416 | task_nodes = cpuset_mems_allowed(task); | |
1417 | mm = get_task_mm(task); | |
1418 | put_task_struct(task); | |
1419 | ||
1420 | if (!mm) | |
1421 | return -EINVAL; | |
1422 | ||
1423 | if (nodes) | |
1424 | err = do_pages_move(mm, task_nodes, nr_pages, pages, | |
1425 | nodes, status, flags); | |
1426 | else | |
1427 | err = do_pages_stat(mm, nr_pages, pages, status); | |
1428 | ||
1429 | mmput(mm); | |
1430 | return err; | |
1431 | ||
1432 | out: | |
1433 | put_task_struct(task); | |
1434 | return err; | |
1435 | } | |
1436 | ||
1437 | /* | |
1438 | * Call migration functions in the vma_ops that may prepare | |
1439 | * memory in a vm for migration. migration functions may perform | |
1440 | * the migration for vmas that do not have an underlying page struct. | |
1441 | */ | |
1442 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1443 | const nodemask_t *from, unsigned long flags) | |
1444 | { | |
1445 | struct vm_area_struct *vma; | |
1446 | int err = 0; | |
1447 | ||
1448 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { | |
1449 | if (vma->vm_ops && vma->vm_ops->migrate) { | |
1450 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1451 | if (err) | |
1452 | break; | |
1453 | } | |
1454 | } | |
1455 | return err; | |
1456 | } | |
1457 | ||
1458 | #ifdef CONFIG_NUMA_BALANCING | |
1459 | /* | |
1460 | * Returns true if this is a safe migration target node for misplaced NUMA | |
1461 | * pages. Currently it only checks the watermarks which crude | |
1462 | */ | |
1463 | static bool migrate_balanced_pgdat(struct pglist_data *pgdat, | |
1464 | int nr_migrate_pages) | |
1465 | { | |
1466 | int z; | |
1467 | for (z = pgdat->nr_zones - 1; z >= 0; z--) { | |
1468 | struct zone *zone = pgdat->node_zones + z; | |
1469 | ||
1470 | if (!populated_zone(zone)) | |
1471 | continue; | |
1472 | ||
1473 | if (zone->all_unreclaimable) | |
1474 | continue; | |
1475 | ||
1476 | /* Avoid waking kswapd by allocating pages_to_migrate pages. */ | |
1477 | if (!zone_watermark_ok(zone, 0, | |
1478 | high_wmark_pages(zone) + | |
1479 | nr_migrate_pages, | |
1480 | 0, 0)) | |
1481 | continue; | |
1482 | return true; | |
1483 | } | |
1484 | return false; | |
1485 | } | |
1486 | ||
1487 | static struct page *alloc_misplaced_dst_page(struct page *page, | |
1488 | unsigned long data, | |
1489 | int **result) | |
1490 | { | |
1491 | int nid = (int) data; | |
1492 | struct page *newpage; | |
1493 | ||
1494 | newpage = alloc_pages_exact_node(nid, | |
1495 | (GFP_HIGHUSER_MOVABLE | GFP_THISNODE | | |
1496 | __GFP_NOMEMALLOC | __GFP_NORETRY | | |
1497 | __GFP_NOWARN) & | |
1498 | ~GFP_IOFS, 0); | |
1499 | if (newpage) | |
1500 | page_xchg_last_nid(newpage, page_last_nid(page)); | |
1501 | ||
1502 | return newpage; | |
1503 | } | |
1504 | ||
1505 | /* | |
1506 | * page migration rate limiting control. | |
1507 | * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs | |
1508 | * window of time. Default here says do not migrate more than 1280M per second. | |
1509 | * If a node is rate-limited then PTE NUMA updates are also rate-limited. However | |
1510 | * as it is faults that reset the window, pte updates will happen unconditionally | |
1511 | * if there has not been a fault since @pteupdate_interval_millisecs after the | |
1512 | * throttle window closed. | |
1513 | */ | |
1514 | static unsigned int migrate_interval_millisecs __read_mostly = 100; | |
1515 | static unsigned int pteupdate_interval_millisecs __read_mostly = 1000; | |
1516 | static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); | |
1517 | ||
1518 | /* Returns true if NUMA migration is currently rate limited */ | |
1519 | bool migrate_ratelimited(int node) | |
1520 | { | |
1521 | pg_data_t *pgdat = NODE_DATA(node); | |
1522 | ||
1523 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window + | |
1524 | msecs_to_jiffies(pteupdate_interval_millisecs))) | |
1525 | return false; | |
1526 | ||
1527 | if (pgdat->numabalancing_migrate_nr_pages < ratelimit_pages) | |
1528 | return false; | |
1529 | ||
1530 | return true; | |
1531 | } | |
1532 | ||
1533 | /* Returns true if the node is migrate rate-limited after the update */ | |
1534 | bool numamigrate_update_ratelimit(pg_data_t *pgdat, unsigned long nr_pages) | |
1535 | { | |
1536 | bool rate_limited = false; | |
1537 | ||
1538 | /* | |
1539 | * Rate-limit the amount of data that is being migrated to a node. | |
1540 | * Optimal placement is no good if the memory bus is saturated and | |
1541 | * all the time is being spent migrating! | |
1542 | */ | |
1543 | spin_lock(&pgdat->numabalancing_migrate_lock); | |
1544 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { | |
1545 | pgdat->numabalancing_migrate_nr_pages = 0; | |
1546 | pgdat->numabalancing_migrate_next_window = jiffies + | |
1547 | msecs_to_jiffies(migrate_interval_millisecs); | |
1548 | } | |
1549 | if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) | |
1550 | rate_limited = true; | |
1551 | else | |
1552 | pgdat->numabalancing_migrate_nr_pages += nr_pages; | |
1553 | spin_unlock(&pgdat->numabalancing_migrate_lock); | |
1554 | ||
1555 | return rate_limited; | |
1556 | } | |
1557 | ||
1558 | int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) | |
1559 | { | |
1560 | int ret = 0; | |
1561 | ||
1562 | /* Avoid migrating to a node that is nearly full */ | |
1563 | if (migrate_balanced_pgdat(pgdat, 1)) { | |
1564 | int page_lru; | |
1565 | ||
1566 | if (isolate_lru_page(page)) { | |
1567 | put_page(page); | |
1568 | return 0; | |
1569 | } | |
1570 | ||
1571 | /* Page is isolated */ | |
1572 | ret = 1; | |
1573 | page_lru = page_is_file_cache(page); | |
1574 | if (!PageTransHuge(page)) | |
1575 | inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru); | |
1576 | else | |
1577 | mod_zone_page_state(page_zone(page), | |
1578 | NR_ISOLATED_ANON + page_lru, | |
1579 | HPAGE_PMD_NR); | |
1580 | } | |
1581 | ||
1582 | /* | |
1583 | * Page is either isolated or there is not enough space on the target | |
1584 | * node. If isolated, then it has taken a reference count and the | |
1585 | * callers reference can be safely dropped without the page | |
1586 | * disappearing underneath us during migration. Otherwise the page is | |
1587 | * not to be migrated but the callers reference should still be | |
1588 | * dropped so it does not leak. | |
1589 | */ | |
1590 | put_page(page); | |
1591 | ||
1592 | return ret; | |
1593 | } | |
1594 | ||
1595 | /* | |
1596 | * Attempt to migrate a misplaced page to the specified destination | |
1597 | * node. Caller is expected to have an elevated reference count on | |
1598 | * the page that will be dropped by this function before returning. | |
1599 | */ | |
1600 | int migrate_misplaced_page(struct page *page, int node) | |
1601 | { | |
1602 | pg_data_t *pgdat = NODE_DATA(node); | |
1603 | int isolated = 0; | |
1604 | int nr_remaining; | |
1605 | LIST_HEAD(migratepages); | |
1606 | ||
1607 | /* | |
1608 | * Don't migrate pages that are mapped in multiple processes. | |
1609 | * TODO: Handle false sharing detection instead of this hammer | |
1610 | */ | |
1611 | if (page_mapcount(page) != 1) { | |
1612 | put_page(page); | |
1613 | goto out; | |
1614 | } | |
1615 | ||
1616 | /* | |
1617 | * Rate-limit the amount of data that is being migrated to a node. | |
1618 | * Optimal placement is no good if the memory bus is saturated and | |
1619 | * all the time is being spent migrating! | |
1620 | */ | |
1621 | if (numamigrate_update_ratelimit(pgdat, 1)) { | |
1622 | put_page(page); | |
1623 | goto out; | |
1624 | } | |
1625 | ||
1626 | isolated = numamigrate_isolate_page(pgdat, page); | |
1627 | if (!isolated) | |
1628 | goto out; | |
1629 | ||
1630 | list_add(&page->lru, &migratepages); | |
1631 | nr_remaining = migrate_pages(&migratepages, | |
1632 | alloc_misplaced_dst_page, | |
1633 | node, false, MIGRATE_ASYNC, | |
1634 | MR_NUMA_MISPLACED); | |
1635 | if (nr_remaining) { | |
1636 | putback_lru_pages(&migratepages); | |
1637 | isolated = 0; | |
1638 | } else | |
1639 | count_vm_numa_event(NUMA_PAGE_MIGRATE); | |
1640 | BUG_ON(!list_empty(&migratepages)); | |
1641 | out: | |
1642 | return isolated; | |
1643 | } | |
1644 | #endif /* CONFIG_NUMA_BALANCING */ | |
1645 | ||
1646 | #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) | |
1647 | int migrate_misplaced_transhuge_page(struct mm_struct *mm, | |
1648 | struct vm_area_struct *vma, | |
1649 | pmd_t *pmd, pmd_t entry, | |
1650 | unsigned long address, | |
1651 | struct page *page, int node) | |
1652 | { | |
1653 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
1654 | pg_data_t *pgdat = NODE_DATA(node); | |
1655 | int isolated = 0; | |
1656 | struct page *new_page = NULL; | |
1657 | struct mem_cgroup *memcg = NULL; | |
1658 | int page_lru = page_is_file_cache(page); | |
1659 | ||
1660 | /* | |
1661 | * Don't migrate pages that are mapped in multiple processes. | |
1662 | * TODO: Handle false sharing detection instead of this hammer | |
1663 | */ | |
1664 | if (page_mapcount(page) != 1) | |
1665 | goto out_dropref; | |
1666 | ||
1667 | /* | |
1668 | * Rate-limit the amount of data that is being migrated to a node. | |
1669 | * Optimal placement is no good if the memory bus is saturated and | |
1670 | * all the time is being spent migrating! | |
1671 | */ | |
1672 | if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) | |
1673 | goto out_dropref; | |
1674 | ||
1675 | new_page = alloc_pages_node(node, | |
1676 | (GFP_TRANSHUGE | GFP_THISNODE) & ~__GFP_WAIT, HPAGE_PMD_ORDER); | |
1677 | if (!new_page) { | |
1678 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); | |
1679 | goto out_dropref; | |
1680 | } | |
1681 | page_xchg_last_nid(new_page, page_last_nid(page)); | |
1682 | ||
1683 | isolated = numamigrate_isolate_page(pgdat, page); | |
1684 | ||
1685 | /* | |
1686 | * Failing to isolate or a GUP pin prevents migration. The expected | |
1687 | * page count is 2. 1 for anonymous pages without a mapping and 1 | |
1688 | * for the callers pin. If the page was isolated, the page will | |
1689 | * need to be put back on the LRU. | |
1690 | */ | |
1691 | if (!isolated || page_count(page) != 2) { | |
1692 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); | |
1693 | put_page(new_page); | |
1694 | if (isolated) { | |
1695 | putback_lru_page(page); | |
1696 | isolated = 0; | |
1697 | goto out; | |
1698 | } | |
1699 | goto out_keep_locked; | |
1700 | } | |
1701 | ||
1702 | /* Prepare a page as a migration target */ | |
1703 | __set_page_locked(new_page); | |
1704 | SetPageSwapBacked(new_page); | |
1705 | ||
1706 | /* anon mapping, we can simply copy page->mapping to the new page: */ | |
1707 | new_page->mapping = page->mapping; | |
1708 | new_page->index = page->index; | |
1709 | migrate_page_copy(new_page, page); | |
1710 | WARN_ON(PageLRU(new_page)); | |
1711 | ||
1712 | /* Recheck the target PMD */ | |
1713 | spin_lock(&mm->page_table_lock); | |
1714 | if (unlikely(!pmd_same(*pmd, entry))) { | |
1715 | spin_unlock(&mm->page_table_lock); | |
1716 | ||
1717 | /* Reverse changes made by migrate_page_copy() */ | |
1718 | if (TestClearPageActive(new_page)) | |
1719 | SetPageActive(page); | |
1720 | if (TestClearPageUnevictable(new_page)) | |
1721 | SetPageUnevictable(page); | |
1722 | mlock_migrate_page(page, new_page); | |
1723 | ||
1724 | unlock_page(new_page); | |
1725 | put_page(new_page); /* Free it */ | |
1726 | ||
1727 | unlock_page(page); | |
1728 | putback_lru_page(page); | |
1729 | ||
1730 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); | |
1731 | goto out; | |
1732 | } | |
1733 | ||
1734 | /* | |
1735 | * Traditional migration needs to prepare the memcg charge | |
1736 | * transaction early to prevent the old page from being | |
1737 | * uncharged when installing migration entries. Here we can | |
1738 | * save the potential rollback and start the charge transfer | |
1739 | * only when migration is already known to end successfully. | |
1740 | */ | |
1741 | mem_cgroup_prepare_migration(page, new_page, &memcg); | |
1742 | ||
1743 | entry = mk_pmd(new_page, vma->vm_page_prot); | |
1744 | entry = pmd_mknonnuma(entry); | |
1745 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1746 | entry = pmd_mkhuge(entry); | |
1747 | ||
1748 | page_add_new_anon_rmap(new_page, vma, haddr); | |
1749 | ||
1750 | set_pmd_at(mm, haddr, pmd, entry); | |
1751 | update_mmu_cache_pmd(vma, address, &entry); | |
1752 | page_remove_rmap(page); | |
1753 | /* | |
1754 | * Finish the charge transaction under the page table lock to | |
1755 | * prevent split_huge_page() from dividing up the charge | |
1756 | * before it's fully transferred to the new page. | |
1757 | */ | |
1758 | mem_cgroup_end_migration(memcg, page, new_page, true); | |
1759 | spin_unlock(&mm->page_table_lock); | |
1760 | ||
1761 | unlock_page(new_page); | |
1762 | unlock_page(page); | |
1763 | put_page(page); /* Drop the rmap reference */ | |
1764 | put_page(page); /* Drop the LRU isolation reference */ | |
1765 | ||
1766 | count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); | |
1767 | count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); | |
1768 | ||
1769 | out: | |
1770 | mod_zone_page_state(page_zone(page), | |
1771 | NR_ISOLATED_ANON + page_lru, | |
1772 | -HPAGE_PMD_NR); | |
1773 | return isolated; | |
1774 | ||
1775 | out_dropref: | |
1776 | put_page(page); | |
1777 | out_keep_locked: | |
1778 | return 0; | |
1779 | } | |
1780 | #endif /* CONFIG_NUMA_BALANCING */ | |
1781 | ||
1782 | #endif /* CONFIG_NUMA */ |