Root/
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 | if (unlikely(PageHuge(page))) { |
104 | putback_active_hugepage(page); |
105 | continue; |
106 | } |
107 | list_del(&page->lru); |
108 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
109 | page_is_file_cache(page)); |
110 | if (unlikely(isolated_balloon_page(page))) |
111 | balloon_page_putback(page); |
112 | else |
113 | putback_lru_page(page); |
114 | } |
115 | } |
116 | |
117 | /* |
118 | * Restore a potential migration pte to a working pte entry |
119 | */ |
120 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, |
121 | unsigned long addr, void *old) |
122 | { |
123 | struct mm_struct *mm = vma->vm_mm; |
124 | swp_entry_t entry; |
125 | pmd_t *pmd; |
126 | pte_t *ptep, pte; |
127 | spinlock_t *ptl; |
128 | |
129 | if (unlikely(PageHuge(new))) { |
130 | ptep = huge_pte_offset(mm, addr); |
131 | if (!ptep) |
132 | goto out; |
133 | ptl = &mm->page_table_lock; |
134 | } else { |
135 | pmd = mm_find_pmd(mm, addr); |
136 | if (!pmd) |
137 | goto out; |
138 | if (pmd_trans_huge(*pmd)) |
139 | goto out; |
140 | |
141 | ptep = pte_offset_map(pmd, addr); |
142 | |
143 | /* |
144 | * Peek to check is_swap_pte() before taking ptlock? No, we |
145 | * can race mremap's move_ptes(), which skips anon_vma lock. |
146 | */ |
147 | |
148 | ptl = pte_lockptr(mm, pmd); |
149 | } |
150 | |
151 | spin_lock(ptl); |
152 | pte = *ptep; |
153 | if (!is_swap_pte(pte)) |
154 | goto unlock; |
155 | |
156 | entry = pte_to_swp_entry(pte); |
157 | |
158 | if (!is_migration_entry(entry) || |
159 | migration_entry_to_page(entry) != old) |
160 | goto unlock; |
161 | |
162 | get_page(new); |
163 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); |
164 | if (pte_swp_soft_dirty(*ptep)) |
165 | pte = pte_mksoft_dirty(pte); |
166 | if (is_write_migration_entry(entry)) |
167 | pte = pte_mkwrite(pte); |
168 | #ifdef CONFIG_HUGETLB_PAGE |
169 | if (PageHuge(new)) { |
170 | pte = pte_mkhuge(pte); |
171 | pte = arch_make_huge_pte(pte, vma, new, 0); |
172 | } |
173 | #endif |
174 | flush_dcache_page(new); |
175 | set_pte_at(mm, addr, ptep, pte); |
176 | |
177 | if (PageHuge(new)) { |
178 | if (PageAnon(new)) |
179 | hugepage_add_anon_rmap(new, vma, addr); |
180 | else |
181 | page_dup_rmap(new); |
182 | } else if (PageAnon(new)) |
183 | page_add_anon_rmap(new, vma, addr); |
184 | else |
185 | page_add_file_rmap(new); |
186 | |
187 | /* No need to invalidate - it was non-present before */ |
188 | update_mmu_cache(vma, addr, ptep); |
189 | unlock: |
190 | pte_unmap_unlock(ptep, ptl); |
191 | out: |
192 | return SWAP_AGAIN; |
193 | } |
194 | |
195 | /* |
196 | * Get rid of all migration entries and replace them by |
197 | * references to the indicated page. |
198 | */ |
199 | static void remove_migration_ptes(struct page *old, struct page *new) |
200 | { |
201 | rmap_walk(new, remove_migration_pte, old); |
202 | } |
203 | |
204 | /* |
205 | * Something used the pte of a page under migration. We need to |
206 | * get to the page and wait until migration is finished. |
207 | * When we return from this function the fault will be retried. |
208 | */ |
209 | static void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, |
210 | spinlock_t *ptl) |
211 | { |
212 | pte_t pte; |
213 | swp_entry_t entry; |
214 | struct page *page; |
215 | |
216 | spin_lock(ptl); |
217 | pte = *ptep; |
218 | if (!is_swap_pte(pte)) |
219 | goto out; |
220 | |
221 | entry = pte_to_swp_entry(pte); |
222 | if (!is_migration_entry(entry)) |
223 | goto out; |
224 | |
225 | page = migration_entry_to_page(entry); |
226 | |
227 | /* |
228 | * Once radix-tree replacement of page migration started, page_count |
229 | * *must* be zero. And, we don't want to call wait_on_page_locked() |
230 | * against a page without get_page(). |
231 | * So, we use get_page_unless_zero(), here. Even failed, page fault |
232 | * will occur again. |
233 | */ |
234 | if (!get_page_unless_zero(page)) |
235 | goto out; |
236 | pte_unmap_unlock(ptep, ptl); |
237 | wait_on_page_locked(page); |
238 | put_page(page); |
239 | return; |
240 | out: |
241 | pte_unmap_unlock(ptep, ptl); |
242 | } |
243 | |
244 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
245 | unsigned long address) |
246 | { |
247 | spinlock_t *ptl = pte_lockptr(mm, pmd); |
248 | pte_t *ptep = pte_offset_map(pmd, address); |
249 | __migration_entry_wait(mm, ptep, ptl); |
250 | } |
251 | |
252 | void migration_entry_wait_huge(struct mm_struct *mm, pte_t *pte) |
253 | { |
254 | spinlock_t *ptl = &(mm)->page_table_lock; |
255 | __migration_entry_wait(mm, pte, ptl); |
256 | } |
257 | |
258 | #ifdef CONFIG_BLOCK |
259 | /* Returns true if all buffers are successfully locked */ |
260 | static bool buffer_migrate_lock_buffers(struct buffer_head *head, |
261 | enum migrate_mode mode) |
262 | { |
263 | struct buffer_head *bh = head; |
264 | |
265 | /* Simple case, sync compaction */ |
266 | if (mode != MIGRATE_ASYNC) { |
267 | do { |
268 | get_bh(bh); |
269 | lock_buffer(bh); |
270 | bh = bh->b_this_page; |
271 | |
272 | } while (bh != head); |
273 | |
274 | return true; |
275 | } |
276 | |
277 | /* async case, we cannot block on lock_buffer so use trylock_buffer */ |
278 | do { |
279 | get_bh(bh); |
280 | if (!trylock_buffer(bh)) { |
281 | /* |
282 | * We failed to lock the buffer and cannot stall in |
283 | * async migration. Release the taken locks |
284 | */ |
285 | struct buffer_head *failed_bh = bh; |
286 | put_bh(failed_bh); |
287 | bh = head; |
288 | while (bh != failed_bh) { |
289 | unlock_buffer(bh); |
290 | put_bh(bh); |
291 | bh = bh->b_this_page; |
292 | } |
293 | return false; |
294 | } |
295 | |
296 | bh = bh->b_this_page; |
297 | } while (bh != head); |
298 | return true; |
299 | } |
300 | #else |
301 | static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, |
302 | enum migrate_mode mode) |
303 | { |
304 | return true; |
305 | } |
306 | #endif /* CONFIG_BLOCK */ |
307 | |
308 | /* |
309 | * Replace the page in the mapping. |
310 | * |
311 | * The number of remaining references must be: |
312 | * 1 for anonymous pages without a mapping |
313 | * 2 for pages with a mapping |
314 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. |
315 | */ |
316 | int migrate_page_move_mapping(struct address_space *mapping, |
317 | struct page *newpage, struct page *page, |
318 | struct buffer_head *head, enum migrate_mode mode) |
319 | { |
320 | int expected_count = 0; |
321 | void **pslot; |
322 | |
323 | if (!mapping) { |
324 | /* Anonymous page without mapping */ |
325 | if (page_count(page) != 1) |
326 | return -EAGAIN; |
327 | return MIGRATEPAGE_SUCCESS; |
328 | } |
329 | |
330 | spin_lock_irq(&mapping->tree_lock); |
331 | |
332 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
333 | page_index(page)); |
334 | |
335 | expected_count = 2 + page_has_private(page); |
336 | if (page_count(page) != expected_count || |
337 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
338 | spin_unlock_irq(&mapping->tree_lock); |
339 | return -EAGAIN; |
340 | } |
341 | |
342 | if (!page_freeze_refs(page, expected_count)) { |
343 | spin_unlock_irq(&mapping->tree_lock); |
344 | return -EAGAIN; |
345 | } |
346 | |
347 | /* |
348 | * In the async migration case of moving a page with buffers, lock the |
349 | * buffers using trylock before the mapping is moved. If the mapping |
350 | * was moved, we later failed to lock the buffers and could not move |
351 | * the mapping back due to an elevated page count, we would have to |
352 | * block waiting on other references to be dropped. |
353 | */ |
354 | if (mode == MIGRATE_ASYNC && head && |
355 | !buffer_migrate_lock_buffers(head, mode)) { |
356 | page_unfreeze_refs(page, expected_count); |
357 | spin_unlock_irq(&mapping->tree_lock); |
358 | return -EAGAIN; |
359 | } |
360 | |
361 | /* |
362 | * Now we know that no one else is looking at the page. |
363 | */ |
364 | get_page(newpage); /* add cache reference */ |
365 | if (PageSwapCache(page)) { |
366 | SetPageSwapCache(newpage); |
367 | set_page_private(newpage, page_private(page)); |
368 | } |
369 | |
370 | radix_tree_replace_slot(pslot, newpage); |
371 | |
372 | /* |
373 | * Drop cache reference from old page by unfreezing |
374 | * to one less reference. |
375 | * We know this isn't the last reference. |
376 | */ |
377 | page_unfreeze_refs(page, expected_count - 1); |
378 | |
379 | /* |
380 | * If moved to a different zone then also account |
381 | * the page for that zone. Other VM counters will be |
382 | * taken care of when we establish references to the |
383 | * new page and drop references to the old page. |
384 | * |
385 | * Note that anonymous pages are accounted for |
386 | * via NR_FILE_PAGES and NR_ANON_PAGES if they |
387 | * are mapped to swap space. |
388 | */ |
389 | __dec_zone_page_state(page, NR_FILE_PAGES); |
390 | __inc_zone_page_state(newpage, NR_FILE_PAGES); |
391 | if (!PageSwapCache(page) && PageSwapBacked(page)) { |
392 | __dec_zone_page_state(page, NR_SHMEM); |
393 | __inc_zone_page_state(newpage, NR_SHMEM); |
394 | } |
395 | spin_unlock_irq(&mapping->tree_lock); |
396 | |
397 | return MIGRATEPAGE_SUCCESS; |
398 | } |
399 | |
400 | /* |
401 | * The expected number of remaining references is the same as that |
402 | * of migrate_page_move_mapping(). |
403 | */ |
404 | int migrate_huge_page_move_mapping(struct address_space *mapping, |
405 | struct page *newpage, struct page *page) |
406 | { |
407 | int expected_count; |
408 | void **pslot; |
409 | |
410 | if (!mapping) { |
411 | if (page_count(page) != 1) |
412 | return -EAGAIN; |
413 | return MIGRATEPAGE_SUCCESS; |
414 | } |
415 | |
416 | spin_lock_irq(&mapping->tree_lock); |
417 | |
418 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
419 | page_index(page)); |
420 | |
421 | expected_count = 2 + page_has_private(page); |
422 | if (page_count(page) != expected_count || |
423 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
424 | spin_unlock_irq(&mapping->tree_lock); |
425 | return -EAGAIN; |
426 | } |
427 | |
428 | if (!page_freeze_refs(page, expected_count)) { |
429 | spin_unlock_irq(&mapping->tree_lock); |
430 | return -EAGAIN; |
431 | } |
432 | |
433 | get_page(newpage); |
434 | |
435 | radix_tree_replace_slot(pslot, newpage); |
436 | |
437 | page_unfreeze_refs(page, expected_count - 1); |
438 | |
439 | spin_unlock_irq(&mapping->tree_lock); |
440 | return MIGRATEPAGE_SUCCESS; |
441 | } |
442 | |
443 | /* |
444 | * Copy the page to its new location |
445 | */ |
446 | void migrate_page_copy(struct page *newpage, struct page *page) |
447 | { |
448 | if (PageHuge(page) || PageTransHuge(page)) |
449 | copy_huge_page(newpage, page); |
450 | else |
451 | copy_highpage(newpage, page); |
452 | |
453 | if (PageError(page)) |
454 | SetPageError(newpage); |
455 | if (PageReferenced(page)) |
456 | SetPageReferenced(newpage); |
457 | if (PageUptodate(page)) |
458 | SetPageUptodate(newpage); |
459 | if (TestClearPageActive(page)) { |
460 | VM_BUG_ON(PageUnevictable(page)); |
461 | SetPageActive(newpage); |
462 | } else if (TestClearPageUnevictable(page)) |
463 | SetPageUnevictable(newpage); |
464 | if (PageChecked(page)) |
465 | SetPageChecked(newpage); |
466 | if (PageMappedToDisk(page)) |
467 | SetPageMappedToDisk(newpage); |
468 | |
469 | if (PageDirty(page)) { |
470 | clear_page_dirty_for_io(page); |
471 | /* |
472 | * Want to mark the page and the radix tree as dirty, and |
473 | * redo the accounting that clear_page_dirty_for_io undid, |
474 | * but we can't use set_page_dirty because that function |
475 | * is actually a signal that all of the page has become dirty. |
476 | * Whereas only part of our page may be dirty. |
477 | */ |
478 | if (PageSwapBacked(page)) |
479 | SetPageDirty(newpage); |
480 | else |
481 | __set_page_dirty_nobuffers(newpage); |
482 | } |
483 | |
484 | mlock_migrate_page(newpage, page); |
485 | ksm_migrate_page(newpage, page); |
486 | /* |
487 | * Please do not reorder this without considering how mm/ksm.c's |
488 | * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). |
489 | */ |
490 | ClearPageSwapCache(page); |
491 | ClearPagePrivate(page); |
492 | set_page_private(page, 0); |
493 | |
494 | /* |
495 | * If any waiters have accumulated on the new page then |
496 | * wake them up. |
497 | */ |
498 | if (PageWriteback(newpage)) |
499 | end_page_writeback(newpage); |
500 | } |
501 | |
502 | /************************************************************ |
503 | * Migration functions |
504 | ***********************************************************/ |
505 | |
506 | /* Always fail migration. Used for mappings that are not movable */ |
507 | int fail_migrate_page(struct address_space *mapping, |
508 | struct page *newpage, struct page *page) |
509 | { |
510 | return -EIO; |
511 | } |
512 | EXPORT_SYMBOL(fail_migrate_page); |
513 | |
514 | /* |
515 | * Common logic to directly migrate a single page suitable for |
516 | * pages that do not use PagePrivate/PagePrivate2. |
517 | * |
518 | * Pages are locked upon entry and exit. |
519 | */ |
520 | int migrate_page(struct address_space *mapping, |
521 | struct page *newpage, struct page *page, |
522 | enum migrate_mode mode) |
523 | { |
524 | int rc; |
525 | |
526 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ |
527 | |
528 | rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode); |
529 | |
530 | if (rc != MIGRATEPAGE_SUCCESS) |
531 | return rc; |
532 | |
533 | migrate_page_copy(newpage, page); |
534 | return MIGRATEPAGE_SUCCESS; |
535 | } |
536 | EXPORT_SYMBOL(migrate_page); |
537 | |
538 | #ifdef CONFIG_BLOCK |
539 | /* |
540 | * Migration function for pages with buffers. This function can only be used |
541 | * if the underlying filesystem guarantees that no other references to "page" |
542 | * exist. |
543 | */ |
544 | int buffer_migrate_page(struct address_space *mapping, |
545 | struct page *newpage, struct page *page, enum migrate_mode mode) |
546 | { |
547 | struct buffer_head *bh, *head; |
548 | int rc; |
549 | |
550 | if (!page_has_buffers(page)) |
551 | return migrate_page(mapping, newpage, page, mode); |
552 | |
553 | head = page_buffers(page); |
554 | |
555 | rc = migrate_page_move_mapping(mapping, newpage, page, head, mode); |
556 | |
557 | if (rc != MIGRATEPAGE_SUCCESS) |
558 | return rc; |
559 | |
560 | /* |
561 | * In the async case, migrate_page_move_mapping locked the buffers |
562 | * with an IRQ-safe spinlock held. In the sync case, the buffers |
563 | * need to be locked now |
564 | */ |
565 | if (mode != MIGRATE_ASYNC) |
566 | BUG_ON(!buffer_migrate_lock_buffers(head, mode)); |
567 | |
568 | ClearPagePrivate(page); |
569 | set_page_private(newpage, page_private(page)); |
570 | set_page_private(page, 0); |
571 | put_page(page); |
572 | get_page(newpage); |
573 | |
574 | bh = head; |
575 | do { |
576 | set_bh_page(bh, newpage, bh_offset(bh)); |
577 | bh = bh->b_this_page; |
578 | |
579 | } while (bh != head); |
580 | |
581 | SetPagePrivate(newpage); |
582 | |
583 | migrate_page_copy(newpage, page); |
584 | |
585 | bh = head; |
586 | do { |
587 | unlock_buffer(bh); |
588 | put_bh(bh); |
589 | bh = bh->b_this_page; |
590 | |
591 | } while (bh != head); |
592 | |
593 | return MIGRATEPAGE_SUCCESS; |
594 | } |
595 | EXPORT_SYMBOL(buffer_migrate_page); |
596 | #endif |
597 | |
598 | /* |
599 | * Writeback a page to clean the dirty state |
600 | */ |
601 | static int writeout(struct address_space *mapping, struct page *page) |
602 | { |
603 | struct writeback_control wbc = { |
604 | .sync_mode = WB_SYNC_NONE, |
605 | .nr_to_write = 1, |
606 | .range_start = 0, |
607 | .range_end = LLONG_MAX, |
608 | .for_reclaim = 1 |
609 | }; |
610 | int rc; |
611 | |
612 | if (!mapping->a_ops->writepage) |
613 | /* No write method for the address space */ |
614 | return -EINVAL; |
615 | |
616 | if (!clear_page_dirty_for_io(page)) |
617 | /* Someone else already triggered a write */ |
618 | return -EAGAIN; |
619 | |
620 | /* |
621 | * A dirty page may imply that the underlying filesystem has |
622 | * the page on some queue. So the page must be clean for |
623 | * migration. Writeout may mean we loose the lock and the |
624 | * page state is no longer what we checked for earlier. |
625 | * At this point we know that the migration attempt cannot |
626 | * be successful. |
627 | */ |
628 | remove_migration_ptes(page, page); |
629 | |
630 | rc = mapping->a_ops->writepage(page, &wbc); |
631 | |
632 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
633 | /* unlocked. Relock */ |
634 | lock_page(page); |
635 | |
636 | return (rc < 0) ? -EIO : -EAGAIN; |
637 | } |
638 | |
639 | /* |
640 | * Default handling if a filesystem does not provide a migration function. |
641 | */ |
642 | static int fallback_migrate_page(struct address_space *mapping, |
643 | struct page *newpage, struct page *page, enum migrate_mode mode) |
644 | { |
645 | if (PageDirty(page)) { |
646 | /* Only writeback pages in full synchronous migration */ |
647 | if (mode != MIGRATE_SYNC) |
648 | return -EBUSY; |
649 | return writeout(mapping, page); |
650 | } |
651 | |
652 | /* |
653 | * Buffers may be managed in a filesystem specific way. |
654 | * We must have no buffers or drop them. |
655 | */ |
656 | if (page_has_private(page) && |
657 | !try_to_release_page(page, GFP_KERNEL)) |
658 | return -EAGAIN; |
659 | |
660 | return migrate_page(mapping, newpage, page, mode); |
661 | } |
662 | |
663 | /* |
664 | * Move a page to a newly allocated page |
665 | * The page is locked and all ptes have been successfully removed. |
666 | * |
667 | * The new page will have replaced the old page if this function |
668 | * is successful. |
669 | * |
670 | * Return value: |
671 | * < 0 - error code |
672 | * MIGRATEPAGE_SUCCESS - success |
673 | */ |
674 | static int move_to_new_page(struct page *newpage, struct page *page, |
675 | int remap_swapcache, enum migrate_mode mode) |
676 | { |
677 | struct address_space *mapping; |
678 | int rc; |
679 | |
680 | /* |
681 | * Block others from accessing the page when we get around to |
682 | * establishing additional references. We are the only one |
683 | * holding a reference to the new page at this point. |
684 | */ |
685 | if (!trylock_page(newpage)) |
686 | BUG(); |
687 | |
688 | /* Prepare mapping for the new page.*/ |
689 | newpage->index = page->index; |
690 | newpage->mapping = page->mapping; |
691 | if (PageSwapBacked(page)) |
692 | SetPageSwapBacked(newpage); |
693 | |
694 | mapping = page_mapping(page); |
695 | if (!mapping) |
696 | rc = migrate_page(mapping, newpage, page, mode); |
697 | else if (mapping->a_ops->migratepage) |
698 | /* |
699 | * Most pages have a mapping and most filesystems provide a |
700 | * migratepage callback. Anonymous pages are part of swap |
701 | * space which also has its own migratepage callback. This |
702 | * is the most common path for page migration. |
703 | */ |
704 | rc = mapping->a_ops->migratepage(mapping, |
705 | newpage, page, mode); |
706 | else |
707 | rc = fallback_migrate_page(mapping, newpage, page, mode); |
708 | |
709 | if (rc != MIGRATEPAGE_SUCCESS) { |
710 | newpage->mapping = NULL; |
711 | } else { |
712 | if (remap_swapcache) |
713 | remove_migration_ptes(page, newpage); |
714 | page->mapping = NULL; |
715 | } |
716 | |
717 | unlock_page(newpage); |
718 | |
719 | return rc; |
720 | } |
721 | |
722 | static int __unmap_and_move(struct page *page, struct page *newpage, |
723 | int force, enum migrate_mode mode) |
724 | { |
725 | int rc = -EAGAIN; |
726 | int remap_swapcache = 1; |
727 | struct mem_cgroup *mem; |
728 | struct anon_vma *anon_vma = NULL; |
729 | |
730 | if (!trylock_page(page)) { |
731 | if (!force || mode == MIGRATE_ASYNC) |
732 | goto out; |
733 | |
734 | /* |
735 | * It's not safe for direct compaction to call lock_page. |
736 | * For example, during page readahead pages are added locked |
737 | * to the LRU. Later, when the IO completes the pages are |
738 | * marked uptodate and unlocked. However, the queueing |
739 | * could be merging multiple pages for one bio (e.g. |
740 | * mpage_readpages). If an allocation happens for the |
741 | * second or third page, the process can end up locking |
742 | * the same page twice and deadlocking. Rather than |
743 | * trying to be clever about what pages can be locked, |
744 | * avoid the use of lock_page for direct compaction |
745 | * altogether. |
746 | */ |
747 | if (current->flags & PF_MEMALLOC) |
748 | goto out; |
749 | |
750 | lock_page(page); |
751 | } |
752 | |
753 | /* charge against new page */ |
754 | mem_cgroup_prepare_migration(page, newpage, &mem); |
755 | |
756 | if (PageWriteback(page)) { |
757 | /* |
758 | * Only in the case of a full synchronous migration is it |
759 | * necessary to wait for PageWriteback. In the async case, |
760 | * the retry loop is too short and in the sync-light case, |
761 | * the overhead of stalling is too much |
762 | */ |
763 | if (mode != MIGRATE_SYNC) { |
764 | rc = -EBUSY; |
765 | goto uncharge; |
766 | } |
767 | if (!force) |
768 | goto uncharge; |
769 | wait_on_page_writeback(page); |
770 | } |
771 | /* |
772 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
773 | * we cannot notice that anon_vma is freed while we migrates a page. |
774 | * This get_anon_vma() delays freeing anon_vma pointer until the end |
775 | * of migration. File cache pages are no problem because of page_lock() |
776 | * File Caches may use write_page() or lock_page() in migration, then, |
777 | * just care Anon page here. |
778 | */ |
779 | if (PageAnon(page) && !PageKsm(page)) { |
780 | /* |
781 | * Only page_lock_anon_vma_read() understands the subtleties of |
782 | * getting a hold on an anon_vma from outside one of its mms. |
783 | */ |
784 | anon_vma = page_get_anon_vma(page); |
785 | if (anon_vma) { |
786 | /* |
787 | * Anon page |
788 | */ |
789 | } else if (PageSwapCache(page)) { |
790 | /* |
791 | * We cannot be sure that the anon_vma of an unmapped |
792 | * swapcache page is safe to use because we don't |
793 | * know in advance if the VMA that this page belonged |
794 | * to still exists. If the VMA and others sharing the |
795 | * data have been freed, then the anon_vma could |
796 | * already be invalid. |
797 | * |
798 | * To avoid this possibility, swapcache pages get |
799 | * migrated but are not remapped when migration |
800 | * completes |
801 | */ |
802 | remap_swapcache = 0; |
803 | } else { |
804 | goto uncharge; |
805 | } |
806 | } |
807 | |
808 | if (unlikely(balloon_page_movable(page))) { |
809 | /* |
810 | * A ballooned page does not need any special attention from |
811 | * physical to virtual reverse mapping procedures. |
812 | * Skip any attempt to unmap PTEs or to remap swap cache, |
813 | * in order to avoid burning cycles at rmap level, and perform |
814 | * the page migration right away (proteced by page lock). |
815 | */ |
816 | rc = balloon_page_migrate(newpage, page, mode); |
817 | goto uncharge; |
818 | } |
819 | |
820 | /* |
821 | * Corner case handling: |
822 | * 1. When a new swap-cache page is read into, it is added to the LRU |
823 | * and treated as swapcache but it has no rmap yet. |
824 | * Calling try_to_unmap() against a page->mapping==NULL page will |
825 | * trigger a BUG. So handle it here. |
826 | * 2. An orphaned page (see truncate_complete_page) might have |
827 | * fs-private metadata. The page can be picked up due to memory |
828 | * offlining. Everywhere else except page reclaim, the page is |
829 | * invisible to the vm, so the page can not be migrated. So try to |
830 | * free the metadata, so the page can be freed. |
831 | */ |
832 | if (!page->mapping) { |
833 | VM_BUG_ON(PageAnon(page)); |
834 | if (page_has_private(page)) { |
835 | try_to_free_buffers(page); |
836 | goto uncharge; |
837 | } |
838 | goto skip_unmap; |
839 | } |
840 | |
841 | /* Establish migration ptes or remove ptes */ |
842 | try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
843 | |
844 | skip_unmap: |
845 | if (!page_mapped(page)) |
846 | rc = move_to_new_page(newpage, page, remap_swapcache, mode); |
847 | |
848 | if (rc && remap_swapcache) |
849 | remove_migration_ptes(page, page); |
850 | |
851 | /* Drop an anon_vma reference if we took one */ |
852 | if (anon_vma) |
853 | put_anon_vma(anon_vma); |
854 | |
855 | uncharge: |
856 | mem_cgroup_end_migration(mem, page, newpage, |
857 | (rc == MIGRATEPAGE_SUCCESS || |
858 | rc == MIGRATEPAGE_BALLOON_SUCCESS)); |
859 | unlock_page(page); |
860 | out: |
861 | return rc; |
862 | } |
863 | |
864 | /* |
865 | * Obtain the lock on page, remove all ptes and migrate the page |
866 | * to the newly allocated page in newpage. |
867 | */ |
868 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
869 | struct page *page, int force, enum migrate_mode mode) |
870 | { |
871 | int rc = 0; |
872 | int *result = NULL; |
873 | struct page *newpage = get_new_page(page, private, &result); |
874 | |
875 | if (!newpage) |
876 | return -ENOMEM; |
877 | |
878 | if (page_count(page) == 1) { |
879 | /* page was freed from under us. So we are done. */ |
880 | goto out; |
881 | } |
882 | |
883 | if (unlikely(PageTransHuge(page))) |
884 | if (unlikely(split_huge_page(page))) |
885 | goto out; |
886 | |
887 | rc = __unmap_and_move(page, newpage, force, mode); |
888 | |
889 | if (unlikely(rc == MIGRATEPAGE_BALLOON_SUCCESS)) { |
890 | /* |
891 | * A ballooned page has been migrated already. |
892 | * Now, it's the time to wrap-up counters, |
893 | * handle the page back to Buddy and return. |
894 | */ |
895 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
896 | page_is_file_cache(page)); |
897 | balloon_page_free(page); |
898 | return MIGRATEPAGE_SUCCESS; |
899 | } |
900 | out: |
901 | if (rc != -EAGAIN) { |
902 | /* |
903 | * A page that has been migrated has all references |
904 | * removed and will be freed. A page that has not been |
905 | * migrated will have kepts its references and be |
906 | * restored. |
907 | */ |
908 | list_del(&page->lru); |
909 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
910 | page_is_file_cache(page)); |
911 | putback_lru_page(page); |
912 | } |
913 | /* |
914 | * Move the new page to the LRU. If migration was not successful |
915 | * then this will free the page. |
916 | */ |
917 | putback_lru_page(newpage); |
918 | if (result) { |
919 | if (rc) |
920 | *result = rc; |
921 | else |
922 | *result = page_to_nid(newpage); |
923 | } |
924 | return rc; |
925 | } |
926 | |
927 | /* |
928 | * Counterpart of unmap_and_move_page() for hugepage migration. |
929 | * |
930 | * This function doesn't wait the completion of hugepage I/O |
931 | * because there is no race between I/O and migration for hugepage. |
932 | * Note that currently hugepage I/O occurs only in direct I/O |
933 | * where no lock is held and PG_writeback is irrelevant, |
934 | * and writeback status of all subpages are counted in the reference |
935 | * count of the head page (i.e. if all subpages of a 2MB hugepage are |
936 | * under direct I/O, the reference of the head page is 512 and a bit more.) |
937 | * This means that when we try to migrate hugepage whose subpages are |
938 | * doing direct I/O, some references remain after try_to_unmap() and |
939 | * hugepage migration fails without data corruption. |
940 | * |
941 | * There is also no race when direct I/O is issued on the page under migration, |
942 | * because then pte is replaced with migration swap entry and direct I/O code |
943 | * will wait in the page fault for migration to complete. |
944 | */ |
945 | static int unmap_and_move_huge_page(new_page_t get_new_page, |
946 | unsigned long private, struct page *hpage, |
947 | int force, enum migrate_mode mode) |
948 | { |
949 | int rc = 0; |
950 | int *result = NULL; |
951 | struct page *new_hpage = get_new_page(hpage, private, &result); |
952 | struct anon_vma *anon_vma = NULL; |
953 | |
954 | /* |
955 | * Movability of hugepages depends on architectures and hugepage size. |
956 | * This check is necessary because some callers of hugepage migration |
957 | * like soft offline and memory hotremove don't walk through page |
958 | * tables or check whether the hugepage is pmd-based or not before |
959 | * kicking migration. |
960 | */ |
961 | if (!hugepage_migration_support(page_hstate(hpage))) |
962 | return -ENOSYS; |
963 | |
964 | if (!new_hpage) |
965 | return -ENOMEM; |
966 | |
967 | rc = -EAGAIN; |
968 | |
969 | if (!trylock_page(hpage)) { |
970 | if (!force || mode != MIGRATE_SYNC) |
971 | goto out; |
972 | lock_page(hpage); |
973 | } |
974 | |
975 | if (PageAnon(hpage)) |
976 | anon_vma = page_get_anon_vma(hpage); |
977 | |
978 | try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
979 | |
980 | if (!page_mapped(hpage)) |
981 | rc = move_to_new_page(new_hpage, hpage, 1, mode); |
982 | |
983 | if (rc) |
984 | remove_migration_ptes(hpage, hpage); |
985 | |
986 | if (anon_vma) |
987 | put_anon_vma(anon_vma); |
988 | |
989 | if (!rc) |
990 | hugetlb_cgroup_migrate(hpage, new_hpage); |
991 | |
992 | unlock_page(hpage); |
993 | out: |
994 | if (rc != -EAGAIN) |
995 | putback_active_hugepage(hpage); |
996 | put_page(new_hpage); |
997 | if (result) { |
998 | if (rc) |
999 | *result = rc; |
1000 | else |
1001 | *result = page_to_nid(new_hpage); |
1002 | } |
1003 | return rc; |
1004 | } |
1005 | |
1006 | /* |
1007 | * migrate_pages - migrate the pages specified in a list, to the free pages |
1008 | * supplied as the target for the page migration |
1009 | * |
1010 | * @from: The list of pages to be migrated. |
1011 | * @get_new_page: The function used to allocate free pages to be used |
1012 | * as the target of the page migration. |
1013 | * @private: Private data to be passed on to get_new_page() |
1014 | * @mode: The migration mode that specifies the constraints for |
1015 | * page migration, if any. |
1016 | * @reason: The reason for page migration. |
1017 | * |
1018 | * The function returns after 10 attempts or if no pages are movable any more |
1019 | * because the list has become empty or no retryable pages exist any more. |
1020 | * The caller should call putback_lru_pages() to return pages to the LRU |
1021 | * or free list only if ret != 0. |
1022 | * |
1023 | * Returns the number of pages that were not migrated, or an error code. |
1024 | */ |
1025 | int migrate_pages(struct list_head *from, new_page_t get_new_page, |
1026 | unsigned long private, enum migrate_mode mode, int reason) |
1027 | { |
1028 | int retry = 1; |
1029 | int nr_failed = 0; |
1030 | int nr_succeeded = 0; |
1031 | int pass = 0; |
1032 | struct page *page; |
1033 | struct page *page2; |
1034 | int swapwrite = current->flags & PF_SWAPWRITE; |
1035 | int rc; |
1036 | |
1037 | if (!swapwrite) |
1038 | current->flags |= PF_SWAPWRITE; |
1039 | |
1040 | for(pass = 0; pass < 10 && retry; pass++) { |
1041 | retry = 0; |
1042 | |
1043 | list_for_each_entry_safe(page, page2, from, lru) { |
1044 | cond_resched(); |
1045 | |
1046 | if (PageHuge(page)) |
1047 | rc = unmap_and_move_huge_page(get_new_page, |
1048 | private, page, pass > 2, mode); |
1049 | else |
1050 | rc = unmap_and_move(get_new_page, private, |
1051 | page, pass > 2, mode); |
1052 | |
1053 | switch(rc) { |
1054 | case -ENOMEM: |
1055 | goto out; |
1056 | case -EAGAIN: |
1057 | retry++; |
1058 | break; |
1059 | case MIGRATEPAGE_SUCCESS: |
1060 | nr_succeeded++; |
1061 | break; |
1062 | default: |
1063 | /* Permanent failure */ |
1064 | nr_failed++; |
1065 | break; |
1066 | } |
1067 | } |
1068 | } |
1069 | rc = nr_failed + retry; |
1070 | out: |
1071 | if (nr_succeeded) |
1072 | count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); |
1073 | if (nr_failed) |
1074 | count_vm_events(PGMIGRATE_FAIL, nr_failed); |
1075 | trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); |
1076 | |
1077 | if (!swapwrite) |
1078 | current->flags &= ~PF_SWAPWRITE; |
1079 | |
1080 | return rc; |
1081 | } |
1082 | |
1083 | #ifdef CONFIG_NUMA |
1084 | /* |
1085 | * Move a list of individual pages |
1086 | */ |
1087 | struct page_to_node { |
1088 | unsigned long addr; |
1089 | struct page *page; |
1090 | int node; |
1091 | int status; |
1092 | }; |
1093 | |
1094 | static struct page *new_page_node(struct page *p, unsigned long private, |
1095 | int **result) |
1096 | { |
1097 | struct page_to_node *pm = (struct page_to_node *)private; |
1098 | |
1099 | while (pm->node != MAX_NUMNODES && pm->page != p) |
1100 | pm++; |
1101 | |
1102 | if (pm->node == MAX_NUMNODES) |
1103 | return NULL; |
1104 | |
1105 | *result = &pm->status; |
1106 | |
1107 | if (PageHuge(p)) |
1108 | return alloc_huge_page_node(page_hstate(compound_head(p)), |
1109 | pm->node); |
1110 | else |
1111 | return alloc_pages_exact_node(pm->node, |
1112 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); |
1113 | } |
1114 | |
1115 | /* |
1116 | * Move a set of pages as indicated in the pm array. The addr |
1117 | * field must be set to the virtual address of the page to be moved |
1118 | * and the node number must contain a valid target node. |
1119 | * The pm array ends with node = MAX_NUMNODES. |
1120 | */ |
1121 | static int do_move_page_to_node_array(struct mm_struct *mm, |
1122 | struct page_to_node *pm, |
1123 | int migrate_all) |
1124 | { |
1125 | int err; |
1126 | struct page_to_node *pp; |
1127 | LIST_HEAD(pagelist); |
1128 | |
1129 | down_read(&mm->mmap_sem); |
1130 | |
1131 | /* |
1132 | * Build a list of pages to migrate |
1133 | */ |
1134 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
1135 | struct vm_area_struct *vma; |
1136 | struct page *page; |
1137 | |
1138 | err = -EFAULT; |
1139 | vma = find_vma(mm, pp->addr); |
1140 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) |
1141 | goto set_status; |
1142 | |
1143 | page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT); |
1144 | |
1145 | err = PTR_ERR(page); |
1146 | if (IS_ERR(page)) |
1147 | goto set_status; |
1148 | |
1149 | err = -ENOENT; |
1150 | if (!page) |
1151 | goto set_status; |
1152 | |
1153 | /* Use PageReserved to check for zero page */ |
1154 | if (PageReserved(page)) |
1155 | goto put_and_set; |
1156 | |
1157 | pp->page = page; |
1158 | err = page_to_nid(page); |
1159 | |
1160 | if (err == pp->node) |
1161 | /* |
1162 | * Node already in the right place |
1163 | */ |
1164 | goto put_and_set; |
1165 | |
1166 | err = -EACCES; |
1167 | if (page_mapcount(page) > 1 && |
1168 | !migrate_all) |
1169 | goto put_and_set; |
1170 | |
1171 | if (PageHuge(page)) { |
1172 | isolate_huge_page(page, &pagelist); |
1173 | goto put_and_set; |
1174 | } |
1175 | |
1176 | err = isolate_lru_page(page); |
1177 | if (!err) { |
1178 | list_add_tail(&page->lru, &pagelist); |
1179 | inc_zone_page_state(page, NR_ISOLATED_ANON + |
1180 | page_is_file_cache(page)); |
1181 | } |
1182 | put_and_set: |
1183 | /* |
1184 | * Either remove the duplicate refcount from |
1185 | * isolate_lru_page() or drop the page ref if it was |
1186 | * not isolated. |
1187 | */ |
1188 | put_page(page); |
1189 | set_status: |
1190 | pp->status = err; |
1191 | } |
1192 | |
1193 | err = 0; |
1194 | if (!list_empty(&pagelist)) { |
1195 | err = migrate_pages(&pagelist, new_page_node, |
1196 | (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL); |
1197 | if (err) |
1198 | putback_movable_pages(&pagelist); |
1199 | } |
1200 | |
1201 | up_read(&mm->mmap_sem); |
1202 | return err; |
1203 | } |
1204 | |
1205 | /* |
1206 | * Migrate an array of page address onto an array of nodes and fill |
1207 | * the corresponding array of status. |
1208 | */ |
1209 | static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, |
1210 | unsigned long nr_pages, |
1211 | const void __user * __user *pages, |
1212 | const int __user *nodes, |
1213 | int __user *status, int flags) |
1214 | { |
1215 | struct page_to_node *pm; |
1216 | unsigned long chunk_nr_pages; |
1217 | unsigned long chunk_start; |
1218 | int err; |
1219 | |
1220 | err = -ENOMEM; |
1221 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); |
1222 | if (!pm) |
1223 | goto out; |
1224 | |
1225 | migrate_prep(); |
1226 | |
1227 | /* |
1228 | * Store a chunk of page_to_node array in a page, |
1229 | * but keep the last one as a marker |
1230 | */ |
1231 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
1232 | |
1233 | for (chunk_start = 0; |
1234 | chunk_start < nr_pages; |
1235 | chunk_start += chunk_nr_pages) { |
1236 | int j; |
1237 | |
1238 | if (chunk_start + chunk_nr_pages > nr_pages) |
1239 | chunk_nr_pages = nr_pages - chunk_start; |
1240 | |
1241 | /* fill the chunk pm with addrs and nodes from user-space */ |
1242 | for (j = 0; j < chunk_nr_pages; j++) { |
1243 | const void __user *p; |
1244 | int node; |
1245 | |
1246 | err = -EFAULT; |
1247 | if (get_user(p, pages + j + chunk_start)) |
1248 | goto out_pm; |
1249 | pm[j].addr = (unsigned long) p; |
1250 | |
1251 | if (get_user(node, nodes + j + chunk_start)) |
1252 | goto out_pm; |
1253 | |
1254 | err = -ENODEV; |
1255 | if (node < 0 || node >= MAX_NUMNODES) |
1256 | goto out_pm; |
1257 | |
1258 | if (!node_state(node, N_MEMORY)) |
1259 | goto out_pm; |
1260 | |
1261 | err = -EACCES; |
1262 | if (!node_isset(node, task_nodes)) |
1263 | goto out_pm; |
1264 | |
1265 | pm[j].node = node; |
1266 | } |
1267 | |
1268 | /* End marker for this chunk */ |
1269 | pm[chunk_nr_pages].node = MAX_NUMNODES; |
1270 | |
1271 | /* Migrate this chunk */ |
1272 | err = do_move_page_to_node_array(mm, pm, |
1273 | flags & MPOL_MF_MOVE_ALL); |
1274 | if (err < 0) |
1275 | goto out_pm; |
1276 | |
1277 | /* Return status information */ |
1278 | for (j = 0; j < chunk_nr_pages; j++) |
1279 | if (put_user(pm[j].status, status + j + chunk_start)) { |
1280 | err = -EFAULT; |
1281 | goto out_pm; |
1282 | } |
1283 | } |
1284 | err = 0; |
1285 | |
1286 | out_pm: |
1287 | free_page((unsigned long)pm); |
1288 | out: |
1289 | return err; |
1290 | } |
1291 | |
1292 | /* |
1293 | * Determine the nodes of an array of pages and store it in an array of status. |
1294 | */ |
1295 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, |
1296 | const void __user **pages, int *status) |
1297 | { |
1298 | unsigned long i; |
1299 | |
1300 | down_read(&mm->mmap_sem); |
1301 | |
1302 | for (i = 0; i < nr_pages; i++) { |
1303 | unsigned long addr = (unsigned long)(*pages); |
1304 | struct vm_area_struct *vma; |
1305 | struct page *page; |
1306 | int err = -EFAULT; |
1307 | |
1308 | vma = find_vma(mm, addr); |
1309 | if (!vma || addr < vma->vm_start) |
1310 | goto set_status; |
1311 | |
1312 | page = follow_page(vma, addr, 0); |
1313 | |
1314 | err = PTR_ERR(page); |
1315 | if (IS_ERR(page)) |
1316 | goto set_status; |
1317 | |
1318 | err = -ENOENT; |
1319 | /* Use PageReserved to check for zero page */ |
1320 | if (!page || PageReserved(page)) |
1321 | goto set_status; |
1322 | |
1323 | err = page_to_nid(page); |
1324 | set_status: |
1325 | *status = err; |
1326 | |
1327 | pages++; |
1328 | status++; |
1329 | } |
1330 | |
1331 | up_read(&mm->mmap_sem); |
1332 | } |
1333 | |
1334 | /* |
1335 | * Determine the nodes of a user array of pages and store it in |
1336 | * a user array of status. |
1337 | */ |
1338 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, |
1339 | const void __user * __user *pages, |
1340 | int __user *status) |
1341 | { |
1342 | #define DO_PAGES_STAT_CHUNK_NR 16 |
1343 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; |
1344 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; |
1345 | |
1346 | while (nr_pages) { |
1347 | unsigned long chunk_nr; |
1348 | |
1349 | chunk_nr = nr_pages; |
1350 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) |
1351 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; |
1352 | |
1353 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) |
1354 | break; |
1355 | |
1356 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); |
1357 | |
1358 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) |
1359 | break; |
1360 | |
1361 | pages += chunk_nr; |
1362 | status += chunk_nr; |
1363 | nr_pages -= chunk_nr; |
1364 | } |
1365 | return nr_pages ? -EFAULT : 0; |
1366 | } |
1367 | |
1368 | /* |
1369 | * Move a list of pages in the address space of the currently executing |
1370 | * process. |
1371 | */ |
1372 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, |
1373 | const void __user * __user *, pages, |
1374 | const int __user *, nodes, |
1375 | int __user *, status, int, flags) |
1376 | { |
1377 | const struct cred *cred = current_cred(), *tcred; |
1378 | struct task_struct *task; |
1379 | struct mm_struct *mm; |
1380 | int err; |
1381 | nodemask_t task_nodes; |
1382 | |
1383 | /* Check flags */ |
1384 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) |
1385 | return -EINVAL; |
1386 | |
1387 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) |
1388 | return -EPERM; |
1389 | |
1390 | /* Find the mm_struct */ |
1391 | rcu_read_lock(); |
1392 | task = pid ? find_task_by_vpid(pid) : current; |
1393 | if (!task) { |
1394 | rcu_read_unlock(); |
1395 | return -ESRCH; |
1396 | } |
1397 | get_task_struct(task); |
1398 | |
1399 | /* |
1400 | * Check if this process has the right to modify the specified |
1401 | * process. The right exists if the process has administrative |
1402 | * capabilities, superuser privileges or the same |
1403 | * userid as the target process. |
1404 | */ |
1405 | tcred = __task_cred(task); |
1406 | if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) && |
1407 | !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) && |
1408 | !capable(CAP_SYS_NICE)) { |
1409 | rcu_read_unlock(); |
1410 | err = -EPERM; |
1411 | goto out; |
1412 | } |
1413 | rcu_read_unlock(); |
1414 | |
1415 | err = security_task_movememory(task); |
1416 | if (err) |
1417 | goto out; |
1418 | |
1419 | task_nodes = cpuset_mems_allowed(task); |
1420 | mm = get_task_mm(task); |
1421 | put_task_struct(task); |
1422 | |
1423 | if (!mm) |
1424 | return -EINVAL; |
1425 | |
1426 | if (nodes) |
1427 | err = do_pages_move(mm, task_nodes, nr_pages, pages, |
1428 | nodes, status, flags); |
1429 | else |
1430 | err = do_pages_stat(mm, nr_pages, pages, status); |
1431 | |
1432 | mmput(mm); |
1433 | return err; |
1434 | |
1435 | out: |
1436 | put_task_struct(task); |
1437 | return err; |
1438 | } |
1439 | |
1440 | /* |
1441 | * Call migration functions in the vma_ops that may prepare |
1442 | * memory in a vm for migration. migration functions may perform |
1443 | * the migration for vmas that do not have an underlying page struct. |
1444 | */ |
1445 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, |
1446 | const nodemask_t *from, unsigned long flags) |
1447 | { |
1448 | struct vm_area_struct *vma; |
1449 | int err = 0; |
1450 | |
1451 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { |
1452 | if (vma->vm_ops && vma->vm_ops->migrate) { |
1453 | err = vma->vm_ops->migrate(vma, to, from, flags); |
1454 | if (err) |
1455 | break; |
1456 | } |
1457 | } |
1458 | return err; |
1459 | } |
1460 | |
1461 | #ifdef CONFIG_NUMA_BALANCING |
1462 | /* |
1463 | * Returns true if this is a safe migration target node for misplaced NUMA |
1464 | * pages. Currently it only checks the watermarks which crude |
1465 | */ |
1466 | static bool migrate_balanced_pgdat(struct pglist_data *pgdat, |
1467 | unsigned long nr_migrate_pages) |
1468 | { |
1469 | int z; |
1470 | for (z = pgdat->nr_zones - 1; z >= 0; z--) { |
1471 | struct zone *zone = pgdat->node_zones + z; |
1472 | |
1473 | if (!populated_zone(zone)) |
1474 | continue; |
1475 | |
1476 | if (!zone_reclaimable(zone)) |
1477 | continue; |
1478 | |
1479 | /* Avoid waking kswapd by allocating pages_to_migrate pages. */ |
1480 | if (!zone_watermark_ok(zone, 0, |
1481 | high_wmark_pages(zone) + |
1482 | nr_migrate_pages, |
1483 | 0, 0)) |
1484 | continue; |
1485 | return true; |
1486 | } |
1487 | return false; |
1488 | } |
1489 | |
1490 | static struct page *alloc_misplaced_dst_page(struct page *page, |
1491 | unsigned long data, |
1492 | int **result) |
1493 | { |
1494 | int nid = (int) data; |
1495 | struct page *newpage; |
1496 | |
1497 | newpage = alloc_pages_exact_node(nid, |
1498 | (GFP_HIGHUSER_MOVABLE | GFP_THISNODE | |
1499 | __GFP_NOMEMALLOC | __GFP_NORETRY | |
1500 | __GFP_NOWARN) & |
1501 | ~GFP_IOFS, 0); |
1502 | if (newpage) |
1503 | page_nid_xchg_last(newpage, page_nid_last(page)); |
1504 | |
1505 | return newpage; |
1506 | } |
1507 | |
1508 | /* |
1509 | * page migration rate limiting control. |
1510 | * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs |
1511 | * window of time. Default here says do not migrate more than 1280M per second. |
1512 | * If a node is rate-limited then PTE NUMA updates are also rate-limited. However |
1513 | * as it is faults that reset the window, pte updates will happen unconditionally |
1514 | * if there has not been a fault since @pteupdate_interval_millisecs after the |
1515 | * throttle window closed. |
1516 | */ |
1517 | static unsigned int migrate_interval_millisecs __read_mostly = 100; |
1518 | static unsigned int pteupdate_interval_millisecs __read_mostly = 1000; |
1519 | static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); |
1520 | |
1521 | /* Returns true if NUMA migration is currently rate limited */ |
1522 | bool migrate_ratelimited(int node) |
1523 | { |
1524 | pg_data_t *pgdat = NODE_DATA(node); |
1525 | |
1526 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window + |
1527 | msecs_to_jiffies(pteupdate_interval_millisecs))) |
1528 | return false; |
1529 | |
1530 | if (pgdat->numabalancing_migrate_nr_pages < ratelimit_pages) |
1531 | return false; |
1532 | |
1533 | return true; |
1534 | } |
1535 | |
1536 | /* Returns true if the node is migrate rate-limited after the update */ |
1537 | bool numamigrate_update_ratelimit(pg_data_t *pgdat, unsigned long nr_pages) |
1538 | { |
1539 | bool rate_limited = false; |
1540 | |
1541 | /* |
1542 | * Rate-limit the amount of data that is being migrated to a node. |
1543 | * Optimal placement is no good if the memory bus is saturated and |
1544 | * all the time is being spent migrating! |
1545 | */ |
1546 | spin_lock(&pgdat->numabalancing_migrate_lock); |
1547 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { |
1548 | pgdat->numabalancing_migrate_nr_pages = 0; |
1549 | pgdat->numabalancing_migrate_next_window = jiffies + |
1550 | msecs_to_jiffies(migrate_interval_millisecs); |
1551 | } |
1552 | if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) |
1553 | rate_limited = true; |
1554 | else |
1555 | pgdat->numabalancing_migrate_nr_pages += nr_pages; |
1556 | spin_unlock(&pgdat->numabalancing_migrate_lock); |
1557 | |
1558 | return rate_limited; |
1559 | } |
1560 | |
1561 | int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) |
1562 | { |
1563 | int page_lru; |
1564 | |
1565 | VM_BUG_ON(compound_order(page) && !PageTransHuge(page)); |
1566 | |
1567 | /* Avoid migrating to a node that is nearly full */ |
1568 | if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) |
1569 | return 0; |
1570 | |
1571 | if (isolate_lru_page(page)) |
1572 | return 0; |
1573 | |
1574 | /* |
1575 | * migrate_misplaced_transhuge_page() skips page migration's usual |
1576 | * check on page_count(), so we must do it here, now that the page |
1577 | * has been isolated: a GUP pin, or any other pin, prevents migration. |
1578 | * The expected page count is 3: 1 for page's mapcount and 1 for the |
1579 | * caller's pin and 1 for the reference taken by isolate_lru_page(). |
1580 | */ |
1581 | if (PageTransHuge(page) && page_count(page) != 3) { |
1582 | putback_lru_page(page); |
1583 | return 0; |
1584 | } |
1585 | |
1586 | page_lru = page_is_file_cache(page); |
1587 | mod_zone_page_state(page_zone(page), NR_ISOLATED_ANON + page_lru, |
1588 | hpage_nr_pages(page)); |
1589 | |
1590 | /* |
1591 | * Isolating the page has taken another reference, so the |
1592 | * caller's reference can be safely dropped without the page |
1593 | * disappearing underneath us during migration. |
1594 | */ |
1595 | put_page(page); |
1596 | return 1; |
1597 | } |
1598 | |
1599 | /* |
1600 | * Attempt to migrate a misplaced page to the specified destination |
1601 | * node. Caller is expected to have an elevated reference count on |
1602 | * the page that will be dropped by this function before returning. |
1603 | */ |
1604 | int migrate_misplaced_page(struct page *page, int node) |
1605 | { |
1606 | pg_data_t *pgdat = NODE_DATA(node); |
1607 | int isolated; |
1608 | int nr_remaining; |
1609 | LIST_HEAD(migratepages); |
1610 | |
1611 | /* |
1612 | * Don't migrate pages that are mapped in multiple processes. |
1613 | * TODO: Handle false sharing detection instead of this hammer |
1614 | */ |
1615 | if (page_mapcount(page) != 1) |
1616 | goto out; |
1617 | |
1618 | /* |
1619 | * Rate-limit the amount of data that is being migrated to a node. |
1620 | * Optimal placement is no good if the memory bus is saturated and |
1621 | * all the time is being spent migrating! |
1622 | */ |
1623 | if (numamigrate_update_ratelimit(pgdat, 1)) |
1624 | goto out; |
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, alloc_misplaced_dst_page, |
1632 | node, MIGRATE_ASYNC, MR_NUMA_MISPLACED); |
1633 | if (nr_remaining) { |
1634 | putback_lru_pages(&migratepages); |
1635 | isolated = 0; |
1636 | } else |
1637 | count_vm_numa_event(NUMA_PAGE_MIGRATE); |
1638 | BUG_ON(!list_empty(&migratepages)); |
1639 | return isolated; |
1640 | |
1641 | out: |
1642 | put_page(page); |
1643 | return 0; |
1644 | } |
1645 | #endif /* CONFIG_NUMA_BALANCING */ |
1646 | |
1647 | #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) |
1648 | /* |
1649 | * Migrates a THP to a given target node. page must be locked and is unlocked |
1650 | * before returning. |
1651 | */ |
1652 | int migrate_misplaced_transhuge_page(struct mm_struct *mm, |
1653 | struct vm_area_struct *vma, |
1654 | pmd_t *pmd, pmd_t entry, |
1655 | unsigned long address, |
1656 | struct page *page, int node) |
1657 | { |
1658 | unsigned long haddr = address & HPAGE_PMD_MASK; |
1659 | pg_data_t *pgdat = NODE_DATA(node); |
1660 | int isolated = 0; |
1661 | struct page *new_page = NULL; |
1662 | struct mem_cgroup *memcg = NULL; |
1663 | int page_lru = page_is_file_cache(page); |
1664 | |
1665 | /* |
1666 | * Don't migrate pages that are mapped in multiple processes. |
1667 | * TODO: Handle false sharing detection instead of this hammer |
1668 | */ |
1669 | if (page_mapcount(page) != 1) |
1670 | goto out_dropref; |
1671 | |
1672 | /* |
1673 | * Rate-limit the amount of data that is being migrated to a node. |
1674 | * Optimal placement is no good if the memory bus is saturated and |
1675 | * all the time is being spent migrating! |
1676 | */ |
1677 | if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) |
1678 | goto out_dropref; |
1679 | |
1680 | new_page = alloc_pages_node(node, |
1681 | (GFP_TRANSHUGE | GFP_THISNODE) & ~__GFP_WAIT, HPAGE_PMD_ORDER); |
1682 | if (!new_page) |
1683 | goto out_fail; |
1684 | |
1685 | page_nid_xchg_last(new_page, page_nid_last(page)); |
1686 | |
1687 | isolated = numamigrate_isolate_page(pgdat, page); |
1688 | if (!isolated) { |
1689 | put_page(new_page); |
1690 | goto out_fail; |
1691 | } |
1692 | |
1693 | /* Prepare a page as a migration target */ |
1694 | __set_page_locked(new_page); |
1695 | SetPageSwapBacked(new_page); |
1696 | |
1697 | /* anon mapping, we can simply copy page->mapping to the new page: */ |
1698 | new_page->mapping = page->mapping; |
1699 | new_page->index = page->index; |
1700 | migrate_page_copy(new_page, page); |
1701 | WARN_ON(PageLRU(new_page)); |
1702 | |
1703 | /* Recheck the target PMD */ |
1704 | spin_lock(&mm->page_table_lock); |
1705 | if (unlikely(!pmd_same(*pmd, entry))) { |
1706 | spin_unlock(&mm->page_table_lock); |
1707 | |
1708 | /* Reverse changes made by migrate_page_copy() */ |
1709 | if (TestClearPageActive(new_page)) |
1710 | SetPageActive(page); |
1711 | if (TestClearPageUnevictable(new_page)) |
1712 | SetPageUnevictable(page); |
1713 | mlock_migrate_page(page, new_page); |
1714 | |
1715 | unlock_page(new_page); |
1716 | put_page(new_page); /* Free it */ |
1717 | |
1718 | /* Retake the callers reference and putback on LRU */ |
1719 | get_page(page); |
1720 | putback_lru_page(page); |
1721 | mod_zone_page_state(page_zone(page), |
1722 | NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); |
1723 | goto out_fail; |
1724 | } |
1725 | |
1726 | /* |
1727 | * Traditional migration needs to prepare the memcg charge |
1728 | * transaction early to prevent the old page from being |
1729 | * uncharged when installing migration entries. Here we can |
1730 | * save the potential rollback and start the charge transfer |
1731 | * only when migration is already known to end successfully. |
1732 | */ |
1733 | mem_cgroup_prepare_migration(page, new_page, &memcg); |
1734 | |
1735 | entry = mk_pmd(new_page, vma->vm_page_prot); |
1736 | entry = pmd_mknonnuma(entry); |
1737 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
1738 | entry = pmd_mkhuge(entry); |
1739 | |
1740 | pmdp_clear_flush(vma, haddr, pmd); |
1741 | set_pmd_at(mm, haddr, pmd, entry); |
1742 | page_add_new_anon_rmap(new_page, vma, haddr); |
1743 | update_mmu_cache_pmd(vma, address, &entry); |
1744 | page_remove_rmap(page); |
1745 | /* |
1746 | * Finish the charge transaction under the page table lock to |
1747 | * prevent split_huge_page() from dividing up the charge |
1748 | * before it's fully transferred to the new page. |
1749 | */ |
1750 | mem_cgroup_end_migration(memcg, page, new_page, true); |
1751 | spin_unlock(&mm->page_table_lock); |
1752 | |
1753 | unlock_page(new_page); |
1754 | unlock_page(page); |
1755 | put_page(page); /* Drop the rmap reference */ |
1756 | put_page(page); /* Drop the LRU isolation reference */ |
1757 | |
1758 | count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); |
1759 | count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); |
1760 | |
1761 | mod_zone_page_state(page_zone(page), |
1762 | NR_ISOLATED_ANON + page_lru, |
1763 | -HPAGE_PMD_NR); |
1764 | return isolated; |
1765 | |
1766 | out_fail: |
1767 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); |
1768 | out_dropref: |
1769 | entry = pmd_mknonnuma(entry); |
1770 | set_pmd_at(mm, haddr, pmd, entry); |
1771 | update_mmu_cache_pmd(vma, address, &entry); |
1772 | |
1773 | unlock_page(page); |
1774 | put_page(page); |
1775 | return 0; |
1776 | } |
1777 | #endif /* CONFIG_NUMA_BALANCING */ |
1778 | |
1779 | #endif /* CONFIG_NUMA */ |
1780 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9