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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 | #include <linux/mmu_notifier.h> |
40 | |
41 | #include <asm/tlbflush.h> |
42 | |
43 | #define CREATE_TRACE_POINTS |
44 | #include <trace/events/migrate.h> |
45 | |
46 | #include "internal.h" |
47 | |
48 | /* |
49 | * migrate_prep() needs to be called before we start compiling a list of pages |
50 | * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is |
51 | * undesirable, use migrate_prep_local() |
52 | */ |
53 | int migrate_prep(void) |
54 | { |
55 | /* |
56 | * Clear the LRU lists so pages can be isolated. |
57 | * Note that pages may be moved off the LRU after we have |
58 | * drained them. Those pages will fail to migrate like other |
59 | * pages that may be busy. |
60 | */ |
61 | lru_add_drain_all(); |
62 | |
63 | return 0; |
64 | } |
65 | |
66 | /* Do the necessary work of migrate_prep but not if it involves other CPUs */ |
67 | int migrate_prep_local(void) |
68 | { |
69 | lru_add_drain(); |
70 | |
71 | return 0; |
72 | } |
73 | |
74 | /* |
75 | * Put previously isolated pages back onto the appropriate lists |
76 | * from where they were once taken off for compaction/migration. |
77 | * |
78 | * This function shall be used whenever the isolated pageset has been |
79 | * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range() |
80 | * and isolate_huge_page(). |
81 | */ |
82 | void putback_movable_pages(struct list_head *l) |
83 | { |
84 | struct page *page; |
85 | struct page *page2; |
86 | |
87 | list_for_each_entry_safe(page, page2, l, lru) { |
88 | if (unlikely(PageHuge(page))) { |
89 | putback_active_hugepage(page); |
90 | continue; |
91 | } |
92 | list_del(&page->lru); |
93 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
94 | page_is_file_cache(page)); |
95 | if (unlikely(isolated_balloon_page(page))) |
96 | balloon_page_putback(page); |
97 | else |
98 | putback_lru_page(page); |
99 | } |
100 | } |
101 | |
102 | /* |
103 | * Restore a potential migration pte to a working pte entry |
104 | */ |
105 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, |
106 | unsigned long addr, void *old) |
107 | { |
108 | struct mm_struct *mm = vma->vm_mm; |
109 | swp_entry_t entry; |
110 | pmd_t *pmd; |
111 | pte_t *ptep, pte; |
112 | spinlock_t *ptl; |
113 | |
114 | if (unlikely(PageHuge(new))) { |
115 | ptep = huge_pte_offset(mm, addr); |
116 | if (!ptep) |
117 | goto out; |
118 | ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep); |
119 | } else { |
120 | pmd = mm_find_pmd(mm, addr); |
121 | if (!pmd) |
122 | goto out; |
123 | if (pmd_trans_huge(*pmd)) |
124 | goto out; |
125 | |
126 | ptep = pte_offset_map(pmd, addr); |
127 | |
128 | /* |
129 | * Peek to check is_swap_pte() before taking ptlock? No, we |
130 | * can race mremap's move_ptes(), which skips anon_vma lock. |
131 | */ |
132 | |
133 | ptl = pte_lockptr(mm, pmd); |
134 | } |
135 | |
136 | spin_lock(ptl); |
137 | pte = *ptep; |
138 | if (!is_swap_pte(pte)) |
139 | goto unlock; |
140 | |
141 | entry = pte_to_swp_entry(pte); |
142 | |
143 | if (!is_migration_entry(entry) || |
144 | migration_entry_to_page(entry) != old) |
145 | goto unlock; |
146 | |
147 | get_page(new); |
148 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); |
149 | if (pte_swp_soft_dirty(*ptep)) |
150 | pte = pte_mksoft_dirty(pte); |
151 | if (is_write_migration_entry(entry)) |
152 | pte = pte_mkwrite(pte); |
153 | #ifdef CONFIG_HUGETLB_PAGE |
154 | if (PageHuge(new)) { |
155 | pte = pte_mkhuge(pte); |
156 | pte = arch_make_huge_pte(pte, vma, new, 0); |
157 | } |
158 | #endif |
159 | flush_dcache_page(new); |
160 | set_pte_at(mm, addr, ptep, pte); |
161 | |
162 | if (PageHuge(new)) { |
163 | if (PageAnon(new)) |
164 | hugepage_add_anon_rmap(new, vma, addr); |
165 | else |
166 | page_dup_rmap(new); |
167 | } else if (PageAnon(new)) |
168 | page_add_anon_rmap(new, vma, addr); |
169 | else |
170 | page_add_file_rmap(new); |
171 | |
172 | /* No need to invalidate - it was non-present before */ |
173 | update_mmu_cache(vma, addr, ptep); |
174 | unlock: |
175 | pte_unmap_unlock(ptep, ptl); |
176 | out: |
177 | return SWAP_AGAIN; |
178 | } |
179 | |
180 | /* |
181 | * Congratulations to trinity for discovering this bug. |
182 | * mm/fremap.c's remap_file_pages() accepts any range within a single vma to |
183 | * convert that vma to VM_NONLINEAR; and generic_file_remap_pages() will then |
184 | * replace the specified range by file ptes throughout (maybe populated after). |
185 | * If page migration finds a page within that range, while it's still located |
186 | * by vma_interval_tree rather than lost to i_mmap_nonlinear list, no problem: |
187 | * zap_pte() clears the temporary migration entry before mmap_sem is dropped. |
188 | * But if the migrating page is in a part of the vma outside the range to be |
189 | * remapped, then it will not be cleared, and remove_migration_ptes() needs to |
190 | * deal with it. Fortunately, this part of the vma is of course still linear, |
191 | * so we just need to use linear location on the nonlinear list. |
192 | */ |
193 | static int remove_linear_migration_ptes_from_nonlinear(struct page *page, |
194 | struct address_space *mapping, void *arg) |
195 | { |
196 | struct vm_area_struct *vma; |
197 | /* hugetlbfs does not support remap_pages, so no huge pgoff worries */ |
198 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
199 | unsigned long addr; |
200 | |
201 | list_for_each_entry(vma, |
202 | &mapping->i_mmap_nonlinear, shared.nonlinear) { |
203 | |
204 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
205 | if (addr >= vma->vm_start && addr < vma->vm_end) |
206 | remove_migration_pte(page, vma, addr, arg); |
207 | } |
208 | return SWAP_AGAIN; |
209 | } |
210 | |
211 | /* |
212 | * Get rid of all migration entries and replace them by |
213 | * references to the indicated page. |
214 | */ |
215 | static void remove_migration_ptes(struct page *old, struct page *new) |
216 | { |
217 | struct rmap_walk_control rwc = { |
218 | .rmap_one = remove_migration_pte, |
219 | .arg = old, |
220 | .file_nonlinear = remove_linear_migration_ptes_from_nonlinear, |
221 | }; |
222 | |
223 | rmap_walk(new, &rwc); |
224 | } |
225 | |
226 | /* |
227 | * Something used the pte of a page under migration. We need to |
228 | * get to the page and wait until migration is finished. |
229 | * When we return from this function the fault will be retried. |
230 | */ |
231 | static void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, |
232 | spinlock_t *ptl) |
233 | { |
234 | pte_t pte; |
235 | swp_entry_t entry; |
236 | struct page *page; |
237 | |
238 | spin_lock(ptl); |
239 | pte = *ptep; |
240 | if (!is_swap_pte(pte)) |
241 | goto out; |
242 | |
243 | entry = pte_to_swp_entry(pte); |
244 | if (!is_migration_entry(entry)) |
245 | goto out; |
246 | |
247 | page = migration_entry_to_page(entry); |
248 | |
249 | /* |
250 | * Once radix-tree replacement of page migration started, page_count |
251 | * *must* be zero. And, we don't want to call wait_on_page_locked() |
252 | * against a page without get_page(). |
253 | * So, we use get_page_unless_zero(), here. Even failed, page fault |
254 | * will occur again. |
255 | */ |
256 | if (!get_page_unless_zero(page)) |
257 | goto out; |
258 | pte_unmap_unlock(ptep, ptl); |
259 | wait_on_page_locked(page); |
260 | put_page(page); |
261 | return; |
262 | out: |
263 | pte_unmap_unlock(ptep, ptl); |
264 | } |
265 | |
266 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
267 | unsigned long address) |
268 | { |
269 | spinlock_t *ptl = pte_lockptr(mm, pmd); |
270 | pte_t *ptep = pte_offset_map(pmd, address); |
271 | __migration_entry_wait(mm, ptep, ptl); |
272 | } |
273 | |
274 | void migration_entry_wait_huge(struct vm_area_struct *vma, |
275 | struct mm_struct *mm, pte_t *pte) |
276 | { |
277 | spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); |
278 | __migration_entry_wait(mm, pte, ptl); |
279 | } |
280 | |
281 | #ifdef CONFIG_BLOCK |
282 | /* Returns true if all buffers are successfully locked */ |
283 | static bool buffer_migrate_lock_buffers(struct buffer_head *head, |
284 | enum migrate_mode mode) |
285 | { |
286 | struct buffer_head *bh = head; |
287 | |
288 | /* Simple case, sync compaction */ |
289 | if (mode != MIGRATE_ASYNC) { |
290 | do { |
291 | get_bh(bh); |
292 | lock_buffer(bh); |
293 | bh = bh->b_this_page; |
294 | |
295 | } while (bh != head); |
296 | |
297 | return true; |
298 | } |
299 | |
300 | /* async case, we cannot block on lock_buffer so use trylock_buffer */ |
301 | do { |
302 | get_bh(bh); |
303 | if (!trylock_buffer(bh)) { |
304 | /* |
305 | * We failed to lock the buffer and cannot stall in |
306 | * async migration. Release the taken locks |
307 | */ |
308 | struct buffer_head *failed_bh = bh; |
309 | put_bh(failed_bh); |
310 | bh = head; |
311 | while (bh != failed_bh) { |
312 | unlock_buffer(bh); |
313 | put_bh(bh); |
314 | bh = bh->b_this_page; |
315 | } |
316 | return false; |
317 | } |
318 | |
319 | bh = bh->b_this_page; |
320 | } while (bh != head); |
321 | return true; |
322 | } |
323 | #else |
324 | static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, |
325 | enum migrate_mode mode) |
326 | { |
327 | return true; |
328 | } |
329 | #endif /* CONFIG_BLOCK */ |
330 | |
331 | /* |
332 | * Replace the page in the mapping. |
333 | * |
334 | * The number of remaining references must be: |
335 | * 1 for anonymous pages without a mapping |
336 | * 2 for pages with a mapping |
337 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. |
338 | */ |
339 | int migrate_page_move_mapping(struct address_space *mapping, |
340 | struct page *newpage, struct page *page, |
341 | struct buffer_head *head, enum migrate_mode mode, |
342 | int extra_count) |
343 | { |
344 | int expected_count = 1 + extra_count; |
345 | void **pslot; |
346 | |
347 | if (!mapping) { |
348 | /* Anonymous page without mapping */ |
349 | if (page_count(page) != expected_count) |
350 | return -EAGAIN; |
351 | return MIGRATEPAGE_SUCCESS; |
352 | } |
353 | |
354 | spin_lock_irq(&mapping->tree_lock); |
355 | |
356 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
357 | page_index(page)); |
358 | |
359 | expected_count += 1 + page_has_private(page); |
360 | if (page_count(page) != expected_count || |
361 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
362 | spin_unlock_irq(&mapping->tree_lock); |
363 | return -EAGAIN; |
364 | } |
365 | |
366 | if (!page_freeze_refs(page, expected_count)) { |
367 | spin_unlock_irq(&mapping->tree_lock); |
368 | return -EAGAIN; |
369 | } |
370 | |
371 | /* |
372 | * In the async migration case of moving a page with buffers, lock the |
373 | * buffers using trylock before the mapping is moved. If the mapping |
374 | * was moved, we later failed to lock the buffers and could not move |
375 | * the mapping back due to an elevated page count, we would have to |
376 | * block waiting on other references to be dropped. |
377 | */ |
378 | if (mode == MIGRATE_ASYNC && head && |
379 | !buffer_migrate_lock_buffers(head, mode)) { |
380 | page_unfreeze_refs(page, expected_count); |
381 | spin_unlock_irq(&mapping->tree_lock); |
382 | return -EAGAIN; |
383 | } |
384 | |
385 | /* |
386 | * Now we know that no one else is looking at the page. |
387 | */ |
388 | get_page(newpage); /* add cache reference */ |
389 | if (PageSwapCache(page)) { |
390 | SetPageSwapCache(newpage); |
391 | set_page_private(newpage, page_private(page)); |
392 | } |
393 | |
394 | radix_tree_replace_slot(pslot, newpage); |
395 | |
396 | /* |
397 | * Drop cache reference from old page by unfreezing |
398 | * to one less reference. |
399 | * We know this isn't the last reference. |
400 | */ |
401 | page_unfreeze_refs(page, expected_count - 1); |
402 | |
403 | /* |
404 | * If moved to a different zone then also account |
405 | * the page for that zone. Other VM counters will be |
406 | * taken care of when we establish references to the |
407 | * new page and drop references to the old page. |
408 | * |
409 | * Note that anonymous pages are accounted for |
410 | * via NR_FILE_PAGES and NR_ANON_PAGES if they |
411 | * are mapped to swap space. |
412 | */ |
413 | __dec_zone_page_state(page, NR_FILE_PAGES); |
414 | __inc_zone_page_state(newpage, NR_FILE_PAGES); |
415 | if (!PageSwapCache(page) && PageSwapBacked(page)) { |
416 | __dec_zone_page_state(page, NR_SHMEM); |
417 | __inc_zone_page_state(newpage, NR_SHMEM); |
418 | } |
419 | spin_unlock_irq(&mapping->tree_lock); |
420 | |
421 | return MIGRATEPAGE_SUCCESS; |
422 | } |
423 | |
424 | /* |
425 | * The expected number of remaining references is the same as that |
426 | * of migrate_page_move_mapping(). |
427 | */ |
428 | int migrate_huge_page_move_mapping(struct address_space *mapping, |
429 | struct page *newpage, struct page *page) |
430 | { |
431 | int expected_count; |
432 | void **pslot; |
433 | |
434 | if (!mapping) { |
435 | if (page_count(page) != 1) |
436 | return -EAGAIN; |
437 | return MIGRATEPAGE_SUCCESS; |
438 | } |
439 | |
440 | spin_lock_irq(&mapping->tree_lock); |
441 | |
442 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
443 | page_index(page)); |
444 | |
445 | expected_count = 2 + page_has_private(page); |
446 | if (page_count(page) != expected_count || |
447 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
448 | spin_unlock_irq(&mapping->tree_lock); |
449 | return -EAGAIN; |
450 | } |
451 | |
452 | if (!page_freeze_refs(page, expected_count)) { |
453 | spin_unlock_irq(&mapping->tree_lock); |
454 | return -EAGAIN; |
455 | } |
456 | |
457 | get_page(newpage); |
458 | |
459 | radix_tree_replace_slot(pslot, newpage); |
460 | |
461 | page_unfreeze_refs(page, expected_count - 1); |
462 | |
463 | spin_unlock_irq(&mapping->tree_lock); |
464 | return MIGRATEPAGE_SUCCESS; |
465 | } |
466 | |
467 | /* |
468 | * Gigantic pages are so large that we do not guarantee that page++ pointer |
469 | * arithmetic will work across the entire page. We need something more |
470 | * specialized. |
471 | */ |
472 | static void __copy_gigantic_page(struct page *dst, struct page *src, |
473 | int nr_pages) |
474 | { |
475 | int i; |
476 | struct page *dst_base = dst; |
477 | struct page *src_base = src; |
478 | |
479 | for (i = 0; i < nr_pages; ) { |
480 | cond_resched(); |
481 | copy_highpage(dst, src); |
482 | |
483 | i++; |
484 | dst = mem_map_next(dst, dst_base, i); |
485 | src = mem_map_next(src, src_base, i); |
486 | } |
487 | } |
488 | |
489 | static void copy_huge_page(struct page *dst, struct page *src) |
490 | { |
491 | int i; |
492 | int nr_pages; |
493 | |
494 | if (PageHuge(src)) { |
495 | /* hugetlbfs page */ |
496 | struct hstate *h = page_hstate(src); |
497 | nr_pages = pages_per_huge_page(h); |
498 | |
499 | if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { |
500 | __copy_gigantic_page(dst, src, nr_pages); |
501 | return; |
502 | } |
503 | } else { |
504 | /* thp page */ |
505 | BUG_ON(!PageTransHuge(src)); |
506 | nr_pages = hpage_nr_pages(src); |
507 | } |
508 | |
509 | for (i = 0; i < nr_pages; i++) { |
510 | cond_resched(); |
511 | copy_highpage(dst + i, src + i); |
512 | } |
513 | } |
514 | |
515 | /* |
516 | * Copy the page to its new location |
517 | */ |
518 | void migrate_page_copy(struct page *newpage, struct page *page) |
519 | { |
520 | int cpupid; |
521 | |
522 | if (PageHuge(page) || PageTransHuge(page)) |
523 | copy_huge_page(newpage, page); |
524 | else |
525 | copy_highpage(newpage, page); |
526 | |
527 | if (PageError(page)) |
528 | SetPageError(newpage); |
529 | if (PageReferenced(page)) |
530 | SetPageReferenced(newpage); |
531 | if (PageUptodate(page)) |
532 | SetPageUptodate(newpage); |
533 | if (TestClearPageActive(page)) { |
534 | VM_BUG_ON_PAGE(PageUnevictable(page), page); |
535 | SetPageActive(newpage); |
536 | } else if (TestClearPageUnevictable(page)) |
537 | SetPageUnevictable(newpage); |
538 | if (PageChecked(page)) |
539 | SetPageChecked(newpage); |
540 | if (PageMappedToDisk(page)) |
541 | SetPageMappedToDisk(newpage); |
542 | |
543 | if (PageDirty(page)) { |
544 | clear_page_dirty_for_io(page); |
545 | /* |
546 | * Want to mark the page and the radix tree as dirty, and |
547 | * redo the accounting that clear_page_dirty_for_io undid, |
548 | * but we can't use set_page_dirty because that function |
549 | * is actually a signal that all of the page has become dirty. |
550 | * Whereas only part of our page may be dirty. |
551 | */ |
552 | if (PageSwapBacked(page)) |
553 | SetPageDirty(newpage); |
554 | else |
555 | __set_page_dirty_nobuffers(newpage); |
556 | } |
557 | |
558 | /* |
559 | * Copy NUMA information to the new page, to prevent over-eager |
560 | * future migrations of this same page. |
561 | */ |
562 | cpupid = page_cpupid_xchg_last(page, -1); |
563 | page_cpupid_xchg_last(newpage, cpupid); |
564 | |
565 | mlock_migrate_page(newpage, page); |
566 | ksm_migrate_page(newpage, page); |
567 | /* |
568 | * Please do not reorder this without considering how mm/ksm.c's |
569 | * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). |
570 | */ |
571 | ClearPageSwapCache(page); |
572 | ClearPagePrivate(page); |
573 | set_page_private(page, 0); |
574 | |
575 | /* |
576 | * If any waiters have accumulated on the new page then |
577 | * wake them up. |
578 | */ |
579 | if (PageWriteback(newpage)) |
580 | end_page_writeback(newpage); |
581 | } |
582 | |
583 | /************************************************************ |
584 | * Migration functions |
585 | ***********************************************************/ |
586 | |
587 | /* |
588 | * Common logic to directly migrate a single page suitable for |
589 | * pages that do not use PagePrivate/PagePrivate2. |
590 | * |
591 | * Pages are locked upon entry and exit. |
592 | */ |
593 | int migrate_page(struct address_space *mapping, |
594 | struct page *newpage, struct page *page, |
595 | enum migrate_mode mode) |
596 | { |
597 | int rc; |
598 | |
599 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ |
600 | |
601 | rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); |
602 | |
603 | if (rc != MIGRATEPAGE_SUCCESS) |
604 | return rc; |
605 | |
606 | migrate_page_copy(newpage, page); |
607 | return MIGRATEPAGE_SUCCESS; |
608 | } |
609 | EXPORT_SYMBOL(migrate_page); |
610 | |
611 | #ifdef CONFIG_BLOCK |
612 | /* |
613 | * Migration function for pages with buffers. This function can only be used |
614 | * if the underlying filesystem guarantees that no other references to "page" |
615 | * exist. |
616 | */ |
617 | int buffer_migrate_page(struct address_space *mapping, |
618 | struct page *newpage, struct page *page, enum migrate_mode mode) |
619 | { |
620 | struct buffer_head *bh, *head; |
621 | int rc; |
622 | |
623 | if (!page_has_buffers(page)) |
624 | return migrate_page(mapping, newpage, page, mode); |
625 | |
626 | head = page_buffers(page); |
627 | |
628 | rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0); |
629 | |
630 | if (rc != MIGRATEPAGE_SUCCESS) |
631 | return rc; |
632 | |
633 | /* |
634 | * In the async case, migrate_page_move_mapping locked the buffers |
635 | * with an IRQ-safe spinlock held. In the sync case, the buffers |
636 | * need to be locked now |
637 | */ |
638 | if (mode != MIGRATE_ASYNC) |
639 | BUG_ON(!buffer_migrate_lock_buffers(head, mode)); |
640 | |
641 | ClearPagePrivate(page); |
642 | set_page_private(newpage, page_private(page)); |
643 | set_page_private(page, 0); |
644 | put_page(page); |
645 | get_page(newpage); |
646 | |
647 | bh = head; |
648 | do { |
649 | set_bh_page(bh, newpage, bh_offset(bh)); |
650 | bh = bh->b_this_page; |
651 | |
652 | } while (bh != head); |
653 | |
654 | SetPagePrivate(newpage); |
655 | |
656 | migrate_page_copy(newpage, page); |
657 | |
658 | bh = head; |
659 | do { |
660 | unlock_buffer(bh); |
661 | put_bh(bh); |
662 | bh = bh->b_this_page; |
663 | |
664 | } while (bh != head); |
665 | |
666 | return MIGRATEPAGE_SUCCESS; |
667 | } |
668 | EXPORT_SYMBOL(buffer_migrate_page); |
669 | #endif |
670 | |
671 | /* |
672 | * Writeback a page to clean the dirty state |
673 | */ |
674 | static int writeout(struct address_space *mapping, struct page *page) |
675 | { |
676 | struct writeback_control wbc = { |
677 | .sync_mode = WB_SYNC_NONE, |
678 | .nr_to_write = 1, |
679 | .range_start = 0, |
680 | .range_end = LLONG_MAX, |
681 | .for_reclaim = 1 |
682 | }; |
683 | int rc; |
684 | |
685 | if (!mapping->a_ops->writepage) |
686 | /* No write method for the address space */ |
687 | return -EINVAL; |
688 | |
689 | if (!clear_page_dirty_for_io(page)) |
690 | /* Someone else already triggered a write */ |
691 | return -EAGAIN; |
692 | |
693 | /* |
694 | * A dirty page may imply that the underlying filesystem has |
695 | * the page on some queue. So the page must be clean for |
696 | * migration. Writeout may mean we loose the lock and the |
697 | * page state is no longer what we checked for earlier. |
698 | * At this point we know that the migration attempt cannot |
699 | * be successful. |
700 | */ |
701 | remove_migration_ptes(page, page); |
702 | |
703 | rc = mapping->a_ops->writepage(page, &wbc); |
704 | |
705 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
706 | /* unlocked. Relock */ |
707 | lock_page(page); |
708 | |
709 | return (rc < 0) ? -EIO : -EAGAIN; |
710 | } |
711 | |
712 | /* |
713 | * Default handling if a filesystem does not provide a migration function. |
714 | */ |
715 | static int fallback_migrate_page(struct address_space *mapping, |
716 | struct page *newpage, struct page *page, enum migrate_mode mode) |
717 | { |
718 | if (PageDirty(page)) { |
719 | /* Only writeback pages in full synchronous migration */ |
720 | if (mode != MIGRATE_SYNC) |
721 | return -EBUSY; |
722 | return writeout(mapping, page); |
723 | } |
724 | |
725 | /* |
726 | * Buffers may be managed in a filesystem specific way. |
727 | * We must have no buffers or drop them. |
728 | */ |
729 | if (page_has_private(page) && |
730 | !try_to_release_page(page, GFP_KERNEL)) |
731 | return -EAGAIN; |
732 | |
733 | return migrate_page(mapping, newpage, page, mode); |
734 | } |
735 | |
736 | /* |
737 | * Move a page to a newly allocated page |
738 | * The page is locked and all ptes have been successfully removed. |
739 | * |
740 | * The new page will have replaced the old page if this function |
741 | * is successful. |
742 | * |
743 | * Return value: |
744 | * < 0 - error code |
745 | * MIGRATEPAGE_SUCCESS - success |
746 | */ |
747 | static int move_to_new_page(struct page *newpage, struct page *page, |
748 | int remap_swapcache, enum migrate_mode mode) |
749 | { |
750 | struct address_space *mapping; |
751 | int rc; |
752 | |
753 | /* |
754 | * Block others from accessing the page when we get around to |
755 | * establishing additional references. We are the only one |
756 | * holding a reference to the new page at this point. |
757 | */ |
758 | if (!trylock_page(newpage)) |
759 | BUG(); |
760 | |
761 | /* Prepare mapping for the new page.*/ |
762 | newpage->index = page->index; |
763 | newpage->mapping = page->mapping; |
764 | if (PageSwapBacked(page)) |
765 | SetPageSwapBacked(newpage); |
766 | |
767 | mapping = page_mapping(page); |
768 | if (!mapping) |
769 | rc = migrate_page(mapping, newpage, page, mode); |
770 | else if (mapping->a_ops->migratepage) |
771 | /* |
772 | * Most pages have a mapping and most filesystems provide a |
773 | * migratepage callback. Anonymous pages are part of swap |
774 | * space which also has its own migratepage callback. This |
775 | * is the most common path for page migration. |
776 | */ |
777 | rc = mapping->a_ops->migratepage(mapping, |
778 | newpage, page, mode); |
779 | else |
780 | rc = fallback_migrate_page(mapping, newpage, page, mode); |
781 | |
782 | if (rc != MIGRATEPAGE_SUCCESS) { |
783 | newpage->mapping = NULL; |
784 | } else { |
785 | if (remap_swapcache) |
786 | remove_migration_ptes(page, newpage); |
787 | page->mapping = NULL; |
788 | } |
789 | |
790 | unlock_page(newpage); |
791 | |
792 | return rc; |
793 | } |
794 | |
795 | static int __unmap_and_move(struct page *page, struct page *newpage, |
796 | int force, enum migrate_mode mode) |
797 | { |
798 | int rc = -EAGAIN; |
799 | int remap_swapcache = 1; |
800 | struct mem_cgroup *mem; |
801 | struct anon_vma *anon_vma = NULL; |
802 | |
803 | if (!trylock_page(page)) { |
804 | if (!force || mode == MIGRATE_ASYNC) |
805 | goto out; |
806 | |
807 | /* |
808 | * It's not safe for direct compaction to call lock_page. |
809 | * For example, during page readahead pages are added locked |
810 | * to the LRU. Later, when the IO completes the pages are |
811 | * marked uptodate and unlocked. However, the queueing |
812 | * could be merging multiple pages for one bio (e.g. |
813 | * mpage_readpages). If an allocation happens for the |
814 | * second or third page, the process can end up locking |
815 | * the same page twice and deadlocking. Rather than |
816 | * trying to be clever about what pages can be locked, |
817 | * avoid the use of lock_page for direct compaction |
818 | * altogether. |
819 | */ |
820 | if (current->flags & PF_MEMALLOC) |
821 | goto out; |
822 | |
823 | lock_page(page); |
824 | } |
825 | |
826 | /* charge against new page */ |
827 | mem_cgroup_prepare_migration(page, newpage, &mem); |
828 | |
829 | if (PageWriteback(page)) { |
830 | /* |
831 | * Only in the case of a full synchronous migration is it |
832 | * necessary to wait for PageWriteback. In the async case, |
833 | * the retry loop is too short and in the sync-light case, |
834 | * the overhead of stalling is too much |
835 | */ |
836 | if (mode != MIGRATE_SYNC) { |
837 | rc = -EBUSY; |
838 | goto uncharge; |
839 | } |
840 | if (!force) |
841 | goto uncharge; |
842 | wait_on_page_writeback(page); |
843 | } |
844 | /* |
845 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
846 | * we cannot notice that anon_vma is freed while we migrates a page. |
847 | * This get_anon_vma() delays freeing anon_vma pointer until the end |
848 | * of migration. File cache pages are no problem because of page_lock() |
849 | * File Caches may use write_page() or lock_page() in migration, then, |
850 | * just care Anon page here. |
851 | */ |
852 | if (PageAnon(page) && !PageKsm(page)) { |
853 | /* |
854 | * Only page_lock_anon_vma_read() understands the subtleties of |
855 | * getting a hold on an anon_vma from outside one of its mms. |
856 | */ |
857 | anon_vma = page_get_anon_vma(page); |
858 | if (anon_vma) { |
859 | /* |
860 | * Anon page |
861 | */ |
862 | } else if (PageSwapCache(page)) { |
863 | /* |
864 | * We cannot be sure that the anon_vma of an unmapped |
865 | * swapcache page is safe to use because we don't |
866 | * know in advance if the VMA that this page belonged |
867 | * to still exists. If the VMA and others sharing the |
868 | * data have been freed, then the anon_vma could |
869 | * already be invalid. |
870 | * |
871 | * To avoid this possibility, swapcache pages get |
872 | * migrated but are not remapped when migration |
873 | * completes |
874 | */ |
875 | remap_swapcache = 0; |
876 | } else { |
877 | goto uncharge; |
878 | } |
879 | } |
880 | |
881 | if (unlikely(balloon_page_movable(page))) { |
882 | /* |
883 | * A ballooned page does not need any special attention from |
884 | * physical to virtual reverse mapping procedures. |
885 | * Skip any attempt to unmap PTEs or to remap swap cache, |
886 | * in order to avoid burning cycles at rmap level, and perform |
887 | * the page migration right away (proteced by page lock). |
888 | */ |
889 | rc = balloon_page_migrate(newpage, page, mode); |
890 | goto uncharge; |
891 | } |
892 | |
893 | /* |
894 | * Corner case handling: |
895 | * 1. When a new swap-cache page is read into, it is added to the LRU |
896 | * and treated as swapcache but it has no rmap yet. |
897 | * Calling try_to_unmap() against a page->mapping==NULL page will |
898 | * trigger a BUG. So handle it here. |
899 | * 2. An orphaned page (see truncate_complete_page) might have |
900 | * fs-private metadata. The page can be picked up due to memory |
901 | * offlining. Everywhere else except page reclaim, the page is |
902 | * invisible to the vm, so the page can not be migrated. So try to |
903 | * free the metadata, so the page can be freed. |
904 | */ |
905 | if (!page->mapping) { |
906 | VM_BUG_ON_PAGE(PageAnon(page), page); |
907 | if (page_has_private(page)) { |
908 | try_to_free_buffers(page); |
909 | goto uncharge; |
910 | } |
911 | goto skip_unmap; |
912 | } |
913 | |
914 | /* Establish migration ptes or remove ptes */ |
915 | try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
916 | |
917 | skip_unmap: |
918 | if (!page_mapped(page)) |
919 | rc = move_to_new_page(newpage, page, remap_swapcache, mode); |
920 | |
921 | if (rc && remap_swapcache) |
922 | remove_migration_ptes(page, page); |
923 | |
924 | /* Drop an anon_vma reference if we took one */ |
925 | if (anon_vma) |
926 | put_anon_vma(anon_vma); |
927 | |
928 | uncharge: |
929 | mem_cgroup_end_migration(mem, page, newpage, |
930 | (rc == MIGRATEPAGE_SUCCESS || |
931 | rc == MIGRATEPAGE_BALLOON_SUCCESS)); |
932 | unlock_page(page); |
933 | out: |
934 | return rc; |
935 | } |
936 | |
937 | /* |
938 | * Obtain the lock on page, remove all ptes and migrate the page |
939 | * to the newly allocated page in newpage. |
940 | */ |
941 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
942 | struct page *page, int force, enum migrate_mode mode) |
943 | { |
944 | int rc = 0; |
945 | int *result = NULL; |
946 | struct page *newpage = get_new_page(page, private, &result); |
947 | |
948 | if (!newpage) |
949 | return -ENOMEM; |
950 | |
951 | if (page_count(page) == 1) { |
952 | /* page was freed from under us. So we are done. */ |
953 | goto out; |
954 | } |
955 | |
956 | if (unlikely(PageTransHuge(page))) |
957 | if (unlikely(split_huge_page(page))) |
958 | goto out; |
959 | |
960 | rc = __unmap_and_move(page, newpage, force, mode); |
961 | |
962 | if (unlikely(rc == MIGRATEPAGE_BALLOON_SUCCESS)) { |
963 | /* |
964 | * A ballooned page has been migrated already. |
965 | * Now, it's the time to wrap-up counters, |
966 | * handle the page back to Buddy and return. |
967 | */ |
968 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
969 | page_is_file_cache(page)); |
970 | balloon_page_free(page); |
971 | return MIGRATEPAGE_SUCCESS; |
972 | } |
973 | out: |
974 | if (rc != -EAGAIN) { |
975 | /* |
976 | * A page that has been migrated has all references |
977 | * removed and will be freed. A page that has not been |
978 | * migrated will have kepts its references and be |
979 | * restored. |
980 | */ |
981 | list_del(&page->lru); |
982 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
983 | page_is_file_cache(page)); |
984 | putback_lru_page(page); |
985 | } |
986 | /* |
987 | * Move the new page to the LRU. If migration was not successful |
988 | * then this will free the page. |
989 | */ |
990 | putback_lru_page(newpage); |
991 | if (result) { |
992 | if (rc) |
993 | *result = rc; |
994 | else |
995 | *result = page_to_nid(newpage); |
996 | } |
997 | return rc; |
998 | } |
999 | |
1000 | /* |
1001 | * Counterpart of unmap_and_move_page() for hugepage migration. |
1002 | * |
1003 | * This function doesn't wait the completion of hugepage I/O |
1004 | * because there is no race between I/O and migration for hugepage. |
1005 | * Note that currently hugepage I/O occurs only in direct I/O |
1006 | * where no lock is held and PG_writeback is irrelevant, |
1007 | * and writeback status of all subpages are counted in the reference |
1008 | * count of the head page (i.e. if all subpages of a 2MB hugepage are |
1009 | * under direct I/O, the reference of the head page is 512 and a bit more.) |
1010 | * This means that when we try to migrate hugepage whose subpages are |
1011 | * doing direct I/O, some references remain after try_to_unmap() and |
1012 | * hugepage migration fails without data corruption. |
1013 | * |
1014 | * There is also no race when direct I/O is issued on the page under migration, |
1015 | * because then pte is replaced with migration swap entry and direct I/O code |
1016 | * will wait in the page fault for migration to complete. |
1017 | */ |
1018 | static int unmap_and_move_huge_page(new_page_t get_new_page, |
1019 | unsigned long private, struct page *hpage, |
1020 | int force, enum migrate_mode mode) |
1021 | { |
1022 | int rc = 0; |
1023 | int *result = NULL; |
1024 | struct page *new_hpage; |
1025 | struct anon_vma *anon_vma = NULL; |
1026 | |
1027 | /* |
1028 | * Movability of hugepages depends on architectures and hugepage size. |
1029 | * This check is necessary because some callers of hugepage migration |
1030 | * like soft offline and memory hotremove don't walk through page |
1031 | * tables or check whether the hugepage is pmd-based or not before |
1032 | * kicking migration. |
1033 | */ |
1034 | if (!hugepage_migration_support(page_hstate(hpage))) { |
1035 | putback_active_hugepage(hpage); |
1036 | return -ENOSYS; |
1037 | } |
1038 | |
1039 | new_hpage = get_new_page(hpage, private, &result); |
1040 | if (!new_hpage) |
1041 | return -ENOMEM; |
1042 | |
1043 | rc = -EAGAIN; |
1044 | |
1045 | if (!trylock_page(hpage)) { |
1046 | if (!force || mode != MIGRATE_SYNC) |
1047 | goto out; |
1048 | lock_page(hpage); |
1049 | } |
1050 | |
1051 | if (PageAnon(hpage)) |
1052 | anon_vma = page_get_anon_vma(hpage); |
1053 | |
1054 | try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
1055 | |
1056 | if (!page_mapped(hpage)) |
1057 | rc = move_to_new_page(new_hpage, hpage, 1, mode); |
1058 | |
1059 | if (rc) |
1060 | remove_migration_ptes(hpage, hpage); |
1061 | |
1062 | if (anon_vma) |
1063 | put_anon_vma(anon_vma); |
1064 | |
1065 | if (!rc) |
1066 | hugetlb_cgroup_migrate(hpage, new_hpage); |
1067 | |
1068 | unlock_page(hpage); |
1069 | out: |
1070 | if (rc != -EAGAIN) |
1071 | putback_active_hugepage(hpage); |
1072 | put_page(new_hpage); |
1073 | if (result) { |
1074 | if (rc) |
1075 | *result = rc; |
1076 | else |
1077 | *result = page_to_nid(new_hpage); |
1078 | } |
1079 | return rc; |
1080 | } |
1081 | |
1082 | /* |
1083 | * migrate_pages - migrate the pages specified in a list, to the free pages |
1084 | * supplied as the target for the page migration |
1085 | * |
1086 | * @from: The list of pages to be migrated. |
1087 | * @get_new_page: The function used to allocate free pages to be used |
1088 | * as the target of the page migration. |
1089 | * @private: Private data to be passed on to get_new_page() |
1090 | * @mode: The migration mode that specifies the constraints for |
1091 | * page migration, if any. |
1092 | * @reason: The reason for page migration. |
1093 | * |
1094 | * The function returns after 10 attempts or if no pages are movable any more |
1095 | * because the list has become empty or no retryable pages exist any more. |
1096 | * The caller should call putback_lru_pages() to return pages to the LRU |
1097 | * or free list only if ret != 0. |
1098 | * |
1099 | * Returns the number of pages that were not migrated, or an error code. |
1100 | */ |
1101 | int migrate_pages(struct list_head *from, new_page_t get_new_page, |
1102 | unsigned long private, enum migrate_mode mode, int reason) |
1103 | { |
1104 | int retry = 1; |
1105 | int nr_failed = 0; |
1106 | int nr_succeeded = 0; |
1107 | int pass = 0; |
1108 | struct page *page; |
1109 | struct page *page2; |
1110 | int swapwrite = current->flags & PF_SWAPWRITE; |
1111 | int rc; |
1112 | |
1113 | if (!swapwrite) |
1114 | current->flags |= PF_SWAPWRITE; |
1115 | |
1116 | for(pass = 0; pass < 10 && retry; pass++) { |
1117 | retry = 0; |
1118 | |
1119 | list_for_each_entry_safe(page, page2, from, lru) { |
1120 | cond_resched(); |
1121 | |
1122 | if (PageHuge(page)) |
1123 | rc = unmap_and_move_huge_page(get_new_page, |
1124 | private, page, pass > 2, mode); |
1125 | else |
1126 | rc = unmap_and_move(get_new_page, private, |
1127 | page, pass > 2, mode); |
1128 | |
1129 | switch(rc) { |
1130 | case -ENOMEM: |
1131 | goto out; |
1132 | case -EAGAIN: |
1133 | retry++; |
1134 | break; |
1135 | case MIGRATEPAGE_SUCCESS: |
1136 | nr_succeeded++; |
1137 | break; |
1138 | default: |
1139 | /* |
1140 | * Permanent failure (-EBUSY, -ENOSYS, etc.): |
1141 | * unlike -EAGAIN case, the failed page is |
1142 | * removed from migration page list and not |
1143 | * retried in the next outer loop. |
1144 | */ |
1145 | nr_failed++; |
1146 | break; |
1147 | } |
1148 | } |
1149 | } |
1150 | rc = nr_failed + retry; |
1151 | out: |
1152 | if (nr_succeeded) |
1153 | count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); |
1154 | if (nr_failed) |
1155 | count_vm_events(PGMIGRATE_FAIL, nr_failed); |
1156 | trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); |
1157 | |
1158 | if (!swapwrite) |
1159 | current->flags &= ~PF_SWAPWRITE; |
1160 | |
1161 | return rc; |
1162 | } |
1163 | |
1164 | #ifdef CONFIG_NUMA |
1165 | /* |
1166 | * Move a list of individual pages |
1167 | */ |
1168 | struct page_to_node { |
1169 | unsigned long addr; |
1170 | struct page *page; |
1171 | int node; |
1172 | int status; |
1173 | }; |
1174 | |
1175 | static struct page *new_page_node(struct page *p, unsigned long private, |
1176 | int **result) |
1177 | { |
1178 | struct page_to_node *pm = (struct page_to_node *)private; |
1179 | |
1180 | while (pm->node != MAX_NUMNODES && pm->page != p) |
1181 | pm++; |
1182 | |
1183 | if (pm->node == MAX_NUMNODES) |
1184 | return NULL; |
1185 | |
1186 | *result = &pm->status; |
1187 | |
1188 | if (PageHuge(p)) |
1189 | return alloc_huge_page_node(page_hstate(compound_head(p)), |
1190 | pm->node); |
1191 | else |
1192 | return alloc_pages_exact_node(pm->node, |
1193 | GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0); |
1194 | } |
1195 | |
1196 | /* |
1197 | * Move a set of pages as indicated in the pm array. The addr |
1198 | * field must be set to the virtual address of the page to be moved |
1199 | * and the node number must contain a valid target node. |
1200 | * The pm array ends with node = MAX_NUMNODES. |
1201 | */ |
1202 | static int do_move_page_to_node_array(struct mm_struct *mm, |
1203 | struct page_to_node *pm, |
1204 | int migrate_all) |
1205 | { |
1206 | int err; |
1207 | struct page_to_node *pp; |
1208 | LIST_HEAD(pagelist); |
1209 | |
1210 | down_read(&mm->mmap_sem); |
1211 | |
1212 | /* |
1213 | * Build a list of pages to migrate |
1214 | */ |
1215 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
1216 | struct vm_area_struct *vma; |
1217 | struct page *page; |
1218 | |
1219 | err = -EFAULT; |
1220 | vma = find_vma(mm, pp->addr); |
1221 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) |
1222 | goto set_status; |
1223 | |
1224 | page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT); |
1225 | |
1226 | err = PTR_ERR(page); |
1227 | if (IS_ERR(page)) |
1228 | goto set_status; |
1229 | |
1230 | err = -ENOENT; |
1231 | if (!page) |
1232 | goto set_status; |
1233 | |
1234 | /* Use PageReserved to check for zero page */ |
1235 | if (PageReserved(page)) |
1236 | goto put_and_set; |
1237 | |
1238 | pp->page = page; |
1239 | err = page_to_nid(page); |
1240 | |
1241 | if (err == pp->node) |
1242 | /* |
1243 | * Node already in the right place |
1244 | */ |
1245 | goto put_and_set; |
1246 | |
1247 | err = -EACCES; |
1248 | if (page_mapcount(page) > 1 && |
1249 | !migrate_all) |
1250 | goto put_and_set; |
1251 | |
1252 | if (PageHuge(page)) { |
1253 | isolate_huge_page(page, &pagelist); |
1254 | goto put_and_set; |
1255 | } |
1256 | |
1257 | err = isolate_lru_page(page); |
1258 | if (!err) { |
1259 | list_add_tail(&page->lru, &pagelist); |
1260 | inc_zone_page_state(page, NR_ISOLATED_ANON + |
1261 | page_is_file_cache(page)); |
1262 | } |
1263 | put_and_set: |
1264 | /* |
1265 | * Either remove the duplicate refcount from |
1266 | * isolate_lru_page() or drop the page ref if it was |
1267 | * not isolated. |
1268 | */ |
1269 | put_page(page); |
1270 | set_status: |
1271 | pp->status = err; |
1272 | } |
1273 | |
1274 | err = 0; |
1275 | if (!list_empty(&pagelist)) { |
1276 | err = migrate_pages(&pagelist, new_page_node, |
1277 | (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL); |
1278 | if (err) |
1279 | putback_movable_pages(&pagelist); |
1280 | } |
1281 | |
1282 | up_read(&mm->mmap_sem); |
1283 | return err; |
1284 | } |
1285 | |
1286 | /* |
1287 | * Migrate an array of page address onto an array of nodes and fill |
1288 | * the corresponding array of status. |
1289 | */ |
1290 | static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, |
1291 | unsigned long nr_pages, |
1292 | const void __user * __user *pages, |
1293 | const int __user *nodes, |
1294 | int __user *status, int flags) |
1295 | { |
1296 | struct page_to_node *pm; |
1297 | unsigned long chunk_nr_pages; |
1298 | unsigned long chunk_start; |
1299 | int err; |
1300 | |
1301 | err = -ENOMEM; |
1302 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); |
1303 | if (!pm) |
1304 | goto out; |
1305 | |
1306 | migrate_prep(); |
1307 | |
1308 | /* |
1309 | * Store a chunk of page_to_node array in a page, |
1310 | * but keep the last one as a marker |
1311 | */ |
1312 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
1313 | |
1314 | for (chunk_start = 0; |
1315 | chunk_start < nr_pages; |
1316 | chunk_start += chunk_nr_pages) { |
1317 | int j; |
1318 | |
1319 | if (chunk_start + chunk_nr_pages > nr_pages) |
1320 | chunk_nr_pages = nr_pages - chunk_start; |
1321 | |
1322 | /* fill the chunk pm with addrs and nodes from user-space */ |
1323 | for (j = 0; j < chunk_nr_pages; j++) { |
1324 | const void __user *p; |
1325 | int node; |
1326 | |
1327 | err = -EFAULT; |
1328 | if (get_user(p, pages + j + chunk_start)) |
1329 | goto out_pm; |
1330 | pm[j].addr = (unsigned long) p; |
1331 | |
1332 | if (get_user(node, nodes + j + chunk_start)) |
1333 | goto out_pm; |
1334 | |
1335 | err = -ENODEV; |
1336 | if (node < 0 || node >= MAX_NUMNODES) |
1337 | goto out_pm; |
1338 | |
1339 | if (!node_state(node, N_MEMORY)) |
1340 | goto out_pm; |
1341 | |
1342 | err = -EACCES; |
1343 | if (!node_isset(node, task_nodes)) |
1344 | goto out_pm; |
1345 | |
1346 | pm[j].node = node; |
1347 | } |
1348 | |
1349 | /* End marker for this chunk */ |
1350 | pm[chunk_nr_pages].node = MAX_NUMNODES; |
1351 | |
1352 | /* Migrate this chunk */ |
1353 | err = do_move_page_to_node_array(mm, pm, |
1354 | flags & MPOL_MF_MOVE_ALL); |
1355 | if (err < 0) |
1356 | goto out_pm; |
1357 | |
1358 | /* Return status information */ |
1359 | for (j = 0; j < chunk_nr_pages; j++) |
1360 | if (put_user(pm[j].status, status + j + chunk_start)) { |
1361 | err = -EFAULT; |
1362 | goto out_pm; |
1363 | } |
1364 | } |
1365 | err = 0; |
1366 | |
1367 | out_pm: |
1368 | free_page((unsigned long)pm); |
1369 | out: |
1370 | return err; |
1371 | } |
1372 | |
1373 | /* |
1374 | * Determine the nodes of an array of pages and store it in an array of status. |
1375 | */ |
1376 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, |
1377 | const void __user **pages, int *status) |
1378 | { |
1379 | unsigned long i; |
1380 | |
1381 | down_read(&mm->mmap_sem); |
1382 | |
1383 | for (i = 0; i < nr_pages; i++) { |
1384 | unsigned long addr = (unsigned long)(*pages); |
1385 | struct vm_area_struct *vma; |
1386 | struct page *page; |
1387 | int err = -EFAULT; |
1388 | |
1389 | vma = find_vma(mm, addr); |
1390 | if (!vma || addr < vma->vm_start) |
1391 | goto set_status; |
1392 | |
1393 | page = follow_page(vma, addr, 0); |
1394 | |
1395 | err = PTR_ERR(page); |
1396 | if (IS_ERR(page)) |
1397 | goto set_status; |
1398 | |
1399 | err = -ENOENT; |
1400 | /* Use PageReserved to check for zero page */ |
1401 | if (!page || PageReserved(page)) |
1402 | goto set_status; |
1403 | |
1404 | err = page_to_nid(page); |
1405 | set_status: |
1406 | *status = err; |
1407 | |
1408 | pages++; |
1409 | status++; |
1410 | } |
1411 | |
1412 | up_read(&mm->mmap_sem); |
1413 | } |
1414 | |
1415 | /* |
1416 | * Determine the nodes of a user array of pages and store it in |
1417 | * a user array of status. |
1418 | */ |
1419 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, |
1420 | const void __user * __user *pages, |
1421 | int __user *status) |
1422 | { |
1423 | #define DO_PAGES_STAT_CHUNK_NR 16 |
1424 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; |
1425 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; |
1426 | |
1427 | while (nr_pages) { |
1428 | unsigned long chunk_nr; |
1429 | |
1430 | chunk_nr = nr_pages; |
1431 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) |
1432 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; |
1433 | |
1434 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) |
1435 | break; |
1436 | |
1437 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); |
1438 | |
1439 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) |
1440 | break; |
1441 | |
1442 | pages += chunk_nr; |
1443 | status += chunk_nr; |
1444 | nr_pages -= chunk_nr; |
1445 | } |
1446 | return nr_pages ? -EFAULT : 0; |
1447 | } |
1448 | |
1449 | /* |
1450 | * Move a list of pages in the address space of the currently executing |
1451 | * process. |
1452 | */ |
1453 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, |
1454 | const void __user * __user *, pages, |
1455 | const int __user *, nodes, |
1456 | int __user *, status, int, flags) |
1457 | { |
1458 | const struct cred *cred = current_cred(), *tcred; |
1459 | struct task_struct *task; |
1460 | struct mm_struct *mm; |
1461 | int err; |
1462 | nodemask_t task_nodes; |
1463 | |
1464 | /* Check flags */ |
1465 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) |
1466 | return -EINVAL; |
1467 | |
1468 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) |
1469 | return -EPERM; |
1470 | |
1471 | /* Find the mm_struct */ |
1472 | rcu_read_lock(); |
1473 | task = pid ? find_task_by_vpid(pid) : current; |
1474 | if (!task) { |
1475 | rcu_read_unlock(); |
1476 | return -ESRCH; |
1477 | } |
1478 | get_task_struct(task); |
1479 | |
1480 | /* |
1481 | * Check if this process has the right to modify the specified |
1482 | * process. The right exists if the process has administrative |
1483 | * capabilities, superuser privileges or the same |
1484 | * userid as the target process. |
1485 | */ |
1486 | tcred = __task_cred(task); |
1487 | if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) && |
1488 | !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) && |
1489 | !capable(CAP_SYS_NICE)) { |
1490 | rcu_read_unlock(); |
1491 | err = -EPERM; |
1492 | goto out; |
1493 | } |
1494 | rcu_read_unlock(); |
1495 | |
1496 | err = security_task_movememory(task); |
1497 | if (err) |
1498 | goto out; |
1499 | |
1500 | task_nodes = cpuset_mems_allowed(task); |
1501 | mm = get_task_mm(task); |
1502 | put_task_struct(task); |
1503 | |
1504 | if (!mm) |
1505 | return -EINVAL; |
1506 | |
1507 | if (nodes) |
1508 | err = do_pages_move(mm, task_nodes, nr_pages, pages, |
1509 | nodes, status, flags); |
1510 | else |
1511 | err = do_pages_stat(mm, nr_pages, pages, status); |
1512 | |
1513 | mmput(mm); |
1514 | return err; |
1515 | |
1516 | out: |
1517 | put_task_struct(task); |
1518 | return err; |
1519 | } |
1520 | |
1521 | /* |
1522 | * Call migration functions in the vma_ops that may prepare |
1523 | * memory in a vm for migration. migration functions may perform |
1524 | * the migration for vmas that do not have an underlying page struct. |
1525 | */ |
1526 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, |
1527 | const nodemask_t *from, unsigned long flags) |
1528 | { |
1529 | struct vm_area_struct *vma; |
1530 | int err = 0; |
1531 | |
1532 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { |
1533 | if (vma->vm_ops && vma->vm_ops->migrate) { |
1534 | err = vma->vm_ops->migrate(vma, to, from, flags); |
1535 | if (err) |
1536 | break; |
1537 | } |
1538 | } |
1539 | return err; |
1540 | } |
1541 | |
1542 | #ifdef CONFIG_NUMA_BALANCING |
1543 | /* |
1544 | * Returns true if this is a safe migration target node for misplaced NUMA |
1545 | * pages. Currently it only checks the watermarks which crude |
1546 | */ |
1547 | static bool migrate_balanced_pgdat(struct pglist_data *pgdat, |
1548 | unsigned long nr_migrate_pages) |
1549 | { |
1550 | int z; |
1551 | for (z = pgdat->nr_zones - 1; z >= 0; z--) { |
1552 | struct zone *zone = pgdat->node_zones + z; |
1553 | |
1554 | if (!populated_zone(zone)) |
1555 | continue; |
1556 | |
1557 | if (!zone_reclaimable(zone)) |
1558 | continue; |
1559 | |
1560 | /* Avoid waking kswapd by allocating pages_to_migrate pages. */ |
1561 | if (!zone_watermark_ok(zone, 0, |
1562 | high_wmark_pages(zone) + |
1563 | nr_migrate_pages, |
1564 | 0, 0)) |
1565 | continue; |
1566 | return true; |
1567 | } |
1568 | return false; |
1569 | } |
1570 | |
1571 | static struct page *alloc_misplaced_dst_page(struct page *page, |
1572 | unsigned long data, |
1573 | int **result) |
1574 | { |
1575 | int nid = (int) data; |
1576 | struct page *newpage; |
1577 | |
1578 | newpage = alloc_pages_exact_node(nid, |
1579 | (GFP_HIGHUSER_MOVABLE | |
1580 | __GFP_THISNODE | __GFP_NOMEMALLOC | |
1581 | __GFP_NORETRY | __GFP_NOWARN) & |
1582 | ~GFP_IOFS, 0); |
1583 | |
1584 | return newpage; |
1585 | } |
1586 | |
1587 | /* |
1588 | * page migration rate limiting control. |
1589 | * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs |
1590 | * window of time. Default here says do not migrate more than 1280M per second. |
1591 | * If a node is rate-limited then PTE NUMA updates are also rate-limited. However |
1592 | * as it is faults that reset the window, pte updates will happen unconditionally |
1593 | * if there has not been a fault since @pteupdate_interval_millisecs after the |
1594 | * throttle window closed. |
1595 | */ |
1596 | static unsigned int migrate_interval_millisecs __read_mostly = 100; |
1597 | static unsigned int pteupdate_interval_millisecs __read_mostly = 1000; |
1598 | static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); |
1599 | |
1600 | /* Returns true if NUMA migration is currently rate limited */ |
1601 | bool migrate_ratelimited(int node) |
1602 | { |
1603 | pg_data_t *pgdat = NODE_DATA(node); |
1604 | |
1605 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window + |
1606 | msecs_to_jiffies(pteupdate_interval_millisecs))) |
1607 | return false; |
1608 | |
1609 | if (pgdat->numabalancing_migrate_nr_pages < ratelimit_pages) |
1610 | return false; |
1611 | |
1612 | return true; |
1613 | } |
1614 | |
1615 | /* Returns true if the node is migrate rate-limited after the update */ |
1616 | static bool numamigrate_update_ratelimit(pg_data_t *pgdat, |
1617 | unsigned long nr_pages) |
1618 | { |
1619 | /* |
1620 | * Rate-limit the amount of data that is being migrated to a node. |
1621 | * Optimal placement is no good if the memory bus is saturated and |
1622 | * all the time is being spent migrating! |
1623 | */ |
1624 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { |
1625 | spin_lock(&pgdat->numabalancing_migrate_lock); |
1626 | pgdat->numabalancing_migrate_nr_pages = 0; |
1627 | pgdat->numabalancing_migrate_next_window = jiffies + |
1628 | msecs_to_jiffies(migrate_interval_millisecs); |
1629 | spin_unlock(&pgdat->numabalancing_migrate_lock); |
1630 | } |
1631 | if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { |
1632 | trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, |
1633 | nr_pages); |
1634 | return true; |
1635 | } |
1636 | |
1637 | /* |
1638 | * This is an unlocked non-atomic update so errors are possible. |
1639 | * The consequences are failing to migrate when we potentiall should |
1640 | * have which is not severe enough to warrant locking. If it is ever |
1641 | * a problem, it can be converted to a per-cpu counter. |
1642 | */ |
1643 | pgdat->numabalancing_migrate_nr_pages += nr_pages; |
1644 | return false; |
1645 | } |
1646 | |
1647 | static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) |
1648 | { |
1649 | int page_lru; |
1650 | |
1651 | VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); |
1652 | |
1653 | /* Avoid migrating to a node that is nearly full */ |
1654 | if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) |
1655 | return 0; |
1656 | |
1657 | if (isolate_lru_page(page)) |
1658 | return 0; |
1659 | |
1660 | /* |
1661 | * migrate_misplaced_transhuge_page() skips page migration's usual |
1662 | * check on page_count(), so we must do it here, now that the page |
1663 | * has been isolated: a GUP pin, or any other pin, prevents migration. |
1664 | * The expected page count is 3: 1 for page's mapcount and 1 for the |
1665 | * caller's pin and 1 for the reference taken by isolate_lru_page(). |
1666 | */ |
1667 | if (PageTransHuge(page) && page_count(page) != 3) { |
1668 | putback_lru_page(page); |
1669 | return 0; |
1670 | } |
1671 | |
1672 | page_lru = page_is_file_cache(page); |
1673 | mod_zone_page_state(page_zone(page), NR_ISOLATED_ANON + page_lru, |
1674 | hpage_nr_pages(page)); |
1675 | |
1676 | /* |
1677 | * Isolating the page has taken another reference, so the |
1678 | * caller's reference can be safely dropped without the page |
1679 | * disappearing underneath us during migration. |
1680 | */ |
1681 | put_page(page); |
1682 | return 1; |
1683 | } |
1684 | |
1685 | bool pmd_trans_migrating(pmd_t pmd) |
1686 | { |
1687 | struct page *page = pmd_page(pmd); |
1688 | return PageLocked(page); |
1689 | } |
1690 | |
1691 | void wait_migrate_huge_page(struct anon_vma *anon_vma, pmd_t *pmd) |
1692 | { |
1693 | struct page *page = pmd_page(*pmd); |
1694 | wait_on_page_locked(page); |
1695 | } |
1696 | |
1697 | /* |
1698 | * Attempt to migrate a misplaced page to the specified destination |
1699 | * node. Caller is expected to have an elevated reference count on |
1700 | * the page that will be dropped by this function before returning. |
1701 | */ |
1702 | int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, |
1703 | int node) |
1704 | { |
1705 | pg_data_t *pgdat = NODE_DATA(node); |
1706 | int isolated; |
1707 | int nr_remaining; |
1708 | LIST_HEAD(migratepages); |
1709 | |
1710 | /* |
1711 | * Don't migrate file pages that are mapped in multiple processes |
1712 | * with execute permissions as they are probably shared libraries. |
1713 | */ |
1714 | if (page_mapcount(page) != 1 && page_is_file_cache(page) && |
1715 | (vma->vm_flags & VM_EXEC)) |
1716 | goto out; |
1717 | |
1718 | /* |
1719 | * Rate-limit the amount of data that is being migrated to a node. |
1720 | * Optimal placement is no good if the memory bus is saturated and |
1721 | * all the time is being spent migrating! |
1722 | */ |
1723 | if (numamigrate_update_ratelimit(pgdat, 1)) |
1724 | goto out; |
1725 | |
1726 | isolated = numamigrate_isolate_page(pgdat, page); |
1727 | if (!isolated) |
1728 | goto out; |
1729 | |
1730 | list_add(&page->lru, &migratepages); |
1731 | nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page, |
1732 | node, MIGRATE_ASYNC, MR_NUMA_MISPLACED); |
1733 | if (nr_remaining) { |
1734 | if (!list_empty(&migratepages)) { |
1735 | list_del(&page->lru); |
1736 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
1737 | page_is_file_cache(page)); |
1738 | putback_lru_page(page); |
1739 | } |
1740 | isolated = 0; |
1741 | } else |
1742 | count_vm_numa_event(NUMA_PAGE_MIGRATE); |
1743 | BUG_ON(!list_empty(&migratepages)); |
1744 | return isolated; |
1745 | |
1746 | out: |
1747 | put_page(page); |
1748 | return 0; |
1749 | } |
1750 | #endif /* CONFIG_NUMA_BALANCING */ |
1751 | |
1752 | #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) |
1753 | /* |
1754 | * Migrates a THP to a given target node. page must be locked and is unlocked |
1755 | * before returning. |
1756 | */ |
1757 | int migrate_misplaced_transhuge_page(struct mm_struct *mm, |
1758 | struct vm_area_struct *vma, |
1759 | pmd_t *pmd, pmd_t entry, |
1760 | unsigned long address, |
1761 | struct page *page, int node) |
1762 | { |
1763 | spinlock_t *ptl; |
1764 | pg_data_t *pgdat = NODE_DATA(node); |
1765 | int isolated = 0; |
1766 | struct page *new_page = NULL; |
1767 | struct mem_cgroup *memcg = NULL; |
1768 | int page_lru = page_is_file_cache(page); |
1769 | unsigned long mmun_start = address & HPAGE_PMD_MASK; |
1770 | unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; |
1771 | pmd_t orig_entry; |
1772 | |
1773 | /* |
1774 | * Rate-limit the amount of data that is being migrated to a node. |
1775 | * Optimal placement is no good if the memory bus is saturated and |
1776 | * all the time is being spent migrating! |
1777 | */ |
1778 | if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) |
1779 | goto out_dropref; |
1780 | |
1781 | new_page = alloc_pages_node(node, |
1782 | (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_WAIT, |
1783 | HPAGE_PMD_ORDER); |
1784 | if (!new_page) |
1785 | goto out_fail; |
1786 | |
1787 | isolated = numamigrate_isolate_page(pgdat, page); |
1788 | if (!isolated) { |
1789 | put_page(new_page); |
1790 | goto out_fail; |
1791 | } |
1792 | |
1793 | if (mm_tlb_flush_pending(mm)) |
1794 | flush_tlb_range(vma, mmun_start, mmun_end); |
1795 | |
1796 | /* Prepare a page as a migration target */ |
1797 | __set_page_locked(new_page); |
1798 | SetPageSwapBacked(new_page); |
1799 | |
1800 | /* anon mapping, we can simply copy page->mapping to the new page: */ |
1801 | new_page->mapping = page->mapping; |
1802 | new_page->index = page->index; |
1803 | migrate_page_copy(new_page, page); |
1804 | WARN_ON(PageLRU(new_page)); |
1805 | |
1806 | /* Recheck the target PMD */ |
1807 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
1808 | ptl = pmd_lock(mm, pmd); |
1809 | if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) { |
1810 | fail_putback: |
1811 | spin_unlock(ptl); |
1812 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1813 | |
1814 | /* Reverse changes made by migrate_page_copy() */ |
1815 | if (TestClearPageActive(new_page)) |
1816 | SetPageActive(page); |
1817 | if (TestClearPageUnevictable(new_page)) |
1818 | SetPageUnevictable(page); |
1819 | mlock_migrate_page(page, new_page); |
1820 | |
1821 | unlock_page(new_page); |
1822 | put_page(new_page); /* Free it */ |
1823 | |
1824 | /* Retake the callers reference and putback on LRU */ |
1825 | get_page(page); |
1826 | putback_lru_page(page); |
1827 | mod_zone_page_state(page_zone(page), |
1828 | NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); |
1829 | |
1830 | goto out_unlock; |
1831 | } |
1832 | |
1833 | /* |
1834 | * Traditional migration needs to prepare the memcg charge |
1835 | * transaction early to prevent the old page from being |
1836 | * uncharged when installing migration entries. Here we can |
1837 | * save the potential rollback and start the charge transfer |
1838 | * only when migration is already known to end successfully. |
1839 | */ |
1840 | mem_cgroup_prepare_migration(page, new_page, &memcg); |
1841 | |
1842 | orig_entry = *pmd; |
1843 | entry = mk_pmd(new_page, vma->vm_page_prot); |
1844 | entry = pmd_mkhuge(entry); |
1845 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
1846 | |
1847 | /* |
1848 | * Clear the old entry under pagetable lock and establish the new PTE. |
1849 | * Any parallel GUP will either observe the old page blocking on the |
1850 | * page lock, block on the page table lock or observe the new page. |
1851 | * The SetPageUptodate on the new page and page_add_new_anon_rmap |
1852 | * guarantee the copy is visible before the pagetable update. |
1853 | */ |
1854 | flush_cache_range(vma, mmun_start, mmun_end); |
1855 | page_add_new_anon_rmap(new_page, vma, mmun_start); |
1856 | pmdp_clear_flush(vma, mmun_start, pmd); |
1857 | set_pmd_at(mm, mmun_start, pmd, entry); |
1858 | flush_tlb_range(vma, mmun_start, mmun_end); |
1859 | update_mmu_cache_pmd(vma, address, &entry); |
1860 | |
1861 | if (page_count(page) != 2) { |
1862 | set_pmd_at(mm, mmun_start, pmd, orig_entry); |
1863 | flush_tlb_range(vma, mmun_start, mmun_end); |
1864 | update_mmu_cache_pmd(vma, address, &entry); |
1865 | page_remove_rmap(new_page); |
1866 | goto fail_putback; |
1867 | } |
1868 | |
1869 | page_remove_rmap(page); |
1870 | |
1871 | /* |
1872 | * Finish the charge transaction under the page table lock to |
1873 | * prevent split_huge_page() from dividing up the charge |
1874 | * before it's fully transferred to the new page. |
1875 | */ |
1876 | mem_cgroup_end_migration(memcg, page, new_page, true); |
1877 | spin_unlock(ptl); |
1878 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1879 | |
1880 | unlock_page(new_page); |
1881 | unlock_page(page); |
1882 | put_page(page); /* Drop the rmap reference */ |
1883 | put_page(page); /* Drop the LRU isolation reference */ |
1884 | |
1885 | count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); |
1886 | count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); |
1887 | |
1888 | mod_zone_page_state(page_zone(page), |
1889 | NR_ISOLATED_ANON + page_lru, |
1890 | -HPAGE_PMD_NR); |
1891 | return isolated; |
1892 | |
1893 | out_fail: |
1894 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); |
1895 | out_dropref: |
1896 | ptl = pmd_lock(mm, pmd); |
1897 | if (pmd_same(*pmd, entry)) { |
1898 | entry = pmd_mknonnuma(entry); |
1899 | set_pmd_at(mm, mmun_start, pmd, entry); |
1900 | update_mmu_cache_pmd(vma, address, &entry); |
1901 | } |
1902 | spin_unlock(ptl); |
1903 | |
1904 | out_unlock: |
1905 | unlock_page(page); |
1906 | put_page(page); |
1907 | return 0; |
1908 | } |
1909 | #endif /* CONFIG_NUMA_BALANCING */ |
1910 | |
1911 | #endif /* CONFIG_NUMA */ |
1912 |
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v2.6.34-rc5
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v3.9