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1 | /* | |
2 | * Memory Migration functionality - linux/mm/migrate.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/backing-dev.h> | |
34 | #include <linux/compaction.h> | |
35 | #include <linux/syscalls.h> | |
36 | #include <linux/hugetlb.h> | |
37 | #include <linux/hugetlb_cgroup.h> | |
38 | #include <linux/gfp.h> | |
39 | #include <linux/balloon_compaction.h> | |
40 | #include <linux/mmu_notifier.h> | |
41 | #include <linux/page_idle.h> | |
42 | #include <linux/page_owner.h> | |
43 | ||
44 | #include <asm/tlbflush.h> | |
45 | ||
46 | #define CREATE_TRACE_POINTS | |
47 | #include <trace/events/migrate.h> | |
48 | ||
49 | #include "internal.h" | |
50 | ||
51 | /* | |
52 | * migrate_prep() needs to be called before we start compiling a list of pages | |
53 | * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is | |
54 | * undesirable, use migrate_prep_local() | |
55 | */ | |
56 | int migrate_prep(void) | |
57 | { | |
58 | /* | |
59 | * Clear the LRU lists so pages can be isolated. | |
60 | * Note that pages may be moved off the LRU after we have | |
61 | * drained them. Those pages will fail to migrate like other | |
62 | * pages that may be busy. | |
63 | */ | |
64 | lru_add_drain_all(); | |
65 | ||
66 | return 0; | |
67 | } | |
68 | ||
69 | /* Do the necessary work of migrate_prep but not if it involves other CPUs */ | |
70 | int migrate_prep_local(void) | |
71 | { | |
72 | lru_add_drain(); | |
73 | ||
74 | return 0; | |
75 | } | |
76 | ||
77 | bool isolate_movable_page(struct page *page, isolate_mode_t mode) | |
78 | { | |
79 | struct address_space *mapping; | |
80 | ||
81 | /* | |
82 | * Avoid burning cycles with pages that are yet under __free_pages(), | |
83 | * or just got freed under us. | |
84 | * | |
85 | * In case we 'win' a race for a movable page being freed under us and | |
86 | * raise its refcount preventing __free_pages() from doing its job | |
87 | * the put_page() at the end of this block will take care of | |
88 | * release this page, thus avoiding a nasty leakage. | |
89 | */ | |
90 | if (unlikely(!get_page_unless_zero(page))) | |
91 | goto out; | |
92 | ||
93 | /* | |
94 | * Check PageMovable before holding a PG_lock because page's owner | |
95 | * assumes anybody doesn't touch PG_lock of newly allocated page | |
96 | * so unconditionally grapping the lock ruins page's owner side. | |
97 | */ | |
98 | if (unlikely(!__PageMovable(page))) | |
99 | goto out_putpage; | |
100 | /* | |
101 | * As movable pages are not isolated from LRU lists, concurrent | |
102 | * compaction threads can race against page migration functions | |
103 | * as well as race against the releasing a page. | |
104 | * | |
105 | * In order to avoid having an already isolated movable page | |
106 | * being (wrongly) re-isolated while it is under migration, | |
107 | * or to avoid attempting to isolate pages being released, | |
108 | * lets be sure we have the page lock | |
109 | * before proceeding with the movable page isolation steps. | |
110 | */ | |
111 | if (unlikely(!trylock_page(page))) | |
112 | goto out_putpage; | |
113 | ||
114 | if (!PageMovable(page) || PageIsolated(page)) | |
115 | goto out_no_isolated; | |
116 | ||
117 | mapping = page_mapping(page); | |
118 | VM_BUG_ON_PAGE(!mapping, page); | |
119 | ||
120 | if (!mapping->a_ops->isolate_page(page, mode)) | |
121 | goto out_no_isolated; | |
122 | ||
123 | /* Driver shouldn't use PG_isolated bit of page->flags */ | |
124 | WARN_ON_ONCE(PageIsolated(page)); | |
125 | __SetPageIsolated(page); | |
126 | unlock_page(page); | |
127 | ||
128 | return true; | |
129 | ||
130 | out_no_isolated: | |
131 | unlock_page(page); | |
132 | out_putpage: | |
133 | put_page(page); | |
134 | out: | |
135 | return false; | |
136 | } | |
137 | ||
138 | /* It should be called on page which is PG_movable */ | |
139 | void putback_movable_page(struct page *page) | |
140 | { | |
141 | struct address_space *mapping; | |
142 | ||
143 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
144 | VM_BUG_ON_PAGE(!PageMovable(page), page); | |
145 | VM_BUG_ON_PAGE(!PageIsolated(page), page); | |
146 | ||
147 | mapping = page_mapping(page); | |
148 | mapping->a_ops->putback_page(page); | |
149 | __ClearPageIsolated(page); | |
150 | } | |
151 | ||
152 | /* | |
153 | * Put previously isolated pages back onto the appropriate lists | |
154 | * from where they were once taken off for compaction/migration. | |
155 | * | |
156 | * This function shall be used whenever the isolated pageset has been | |
157 | * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range() | |
158 | * and isolate_huge_page(). | |
159 | */ | |
160 | void putback_movable_pages(struct list_head *l) | |
161 | { | |
162 | struct page *page; | |
163 | struct page *page2; | |
164 | ||
165 | list_for_each_entry_safe(page, page2, l, lru) { | |
166 | if (unlikely(PageHuge(page))) { | |
167 | putback_active_hugepage(page); | |
168 | continue; | |
169 | } | |
170 | list_del(&page->lru); | |
171 | /* | |
172 | * We isolated non-lru movable page so here we can use | |
173 | * __PageMovable because LRU page's mapping cannot have | |
174 | * PAGE_MAPPING_MOVABLE. | |
175 | */ | |
176 | if (unlikely(__PageMovable(page))) { | |
177 | VM_BUG_ON_PAGE(!PageIsolated(page), page); | |
178 | lock_page(page); | |
179 | if (PageMovable(page)) | |
180 | putback_movable_page(page); | |
181 | else | |
182 | __ClearPageIsolated(page); | |
183 | unlock_page(page); | |
184 | put_page(page); | |
185 | } else { | |
186 | dec_node_page_state(page, NR_ISOLATED_ANON + | |
187 | page_is_file_cache(page)); | |
188 | putback_lru_page(page); | |
189 | } | |
190 | } | |
191 | } | |
192 | ||
193 | /* | |
194 | * Restore a potential migration pte to a working pte entry | |
195 | */ | |
196 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, | |
197 | unsigned long addr, void *old) | |
198 | { | |
199 | struct mm_struct *mm = vma->vm_mm; | |
200 | swp_entry_t entry; | |
201 | pmd_t *pmd; | |
202 | pte_t *ptep, pte; | |
203 | spinlock_t *ptl; | |
204 | ||
205 | if (unlikely(PageHuge(new))) { | |
206 | ptep = huge_pte_offset(mm, addr); | |
207 | if (!ptep) | |
208 | goto out; | |
209 | ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep); | |
210 | } else { | |
211 | pmd = mm_find_pmd(mm, addr); | |
212 | if (!pmd) | |
213 | goto out; | |
214 | ||
215 | ptep = pte_offset_map(pmd, addr); | |
216 | ||
217 | /* | |
218 | * Peek to check is_swap_pte() before taking ptlock? No, we | |
219 | * can race mremap's move_ptes(), which skips anon_vma lock. | |
220 | */ | |
221 | ||
222 | ptl = pte_lockptr(mm, pmd); | |
223 | } | |
224 | ||
225 | spin_lock(ptl); | |
226 | pte = *ptep; | |
227 | if (!is_swap_pte(pte)) | |
228 | goto unlock; | |
229 | ||
230 | entry = pte_to_swp_entry(pte); | |
231 | ||
232 | if (!is_migration_entry(entry) || | |
233 | migration_entry_to_page(entry) != old) | |
234 | goto unlock; | |
235 | ||
236 | get_page(new); | |
237 | pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot))); | |
238 | if (pte_swp_soft_dirty(*ptep)) | |
239 | pte = pte_mksoft_dirty(pte); | |
240 | ||
241 | /* Recheck VMA as permissions can change since migration started */ | |
242 | if (is_write_migration_entry(entry)) | |
243 | pte = maybe_mkwrite(pte, vma); | |
244 | ||
245 | #ifdef CONFIG_HUGETLB_PAGE | |
246 | if (PageHuge(new)) { | |
247 | pte = pte_mkhuge(pte); | |
248 | pte = arch_make_huge_pte(pte, vma, new, 0); | |
249 | } | |
250 | #endif | |
251 | flush_dcache_page(new); | |
252 | set_pte_at(mm, addr, ptep, pte); | |
253 | ||
254 | if (PageHuge(new)) { | |
255 | if (PageAnon(new)) | |
256 | hugepage_add_anon_rmap(new, vma, addr); | |
257 | else | |
258 | page_dup_rmap(new, true); | |
259 | } else if (PageAnon(new)) | |
260 | page_add_anon_rmap(new, vma, addr, false); | |
261 | else | |
262 | page_add_file_rmap(new, false); | |
263 | ||
264 | if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new)) | |
265 | mlock_vma_page(new); | |
266 | ||
267 | /* No need to invalidate - it was non-present before */ | |
268 | update_mmu_cache(vma, addr, ptep); | |
269 | unlock: | |
270 | pte_unmap_unlock(ptep, ptl); | |
271 | out: | |
272 | return SWAP_AGAIN; | |
273 | } | |
274 | ||
275 | /* | |
276 | * Get rid of all migration entries and replace them by | |
277 | * references to the indicated page. | |
278 | */ | |
279 | void remove_migration_ptes(struct page *old, struct page *new, bool locked) | |
280 | { | |
281 | struct rmap_walk_control rwc = { | |
282 | .rmap_one = remove_migration_pte, | |
283 | .arg = old, | |
284 | }; | |
285 | ||
286 | if (locked) | |
287 | rmap_walk_locked(new, &rwc); | |
288 | else | |
289 | rmap_walk(new, &rwc); | |
290 | } | |
291 | ||
292 | /* | |
293 | * Something used the pte of a page under migration. We need to | |
294 | * get to the page and wait until migration is finished. | |
295 | * When we return from this function the fault will be retried. | |
296 | */ | |
297 | void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, | |
298 | spinlock_t *ptl) | |
299 | { | |
300 | pte_t pte; | |
301 | swp_entry_t entry; | |
302 | struct page *page; | |
303 | ||
304 | spin_lock(ptl); | |
305 | pte = *ptep; | |
306 | if (!is_swap_pte(pte)) | |
307 | goto out; | |
308 | ||
309 | entry = pte_to_swp_entry(pte); | |
310 | if (!is_migration_entry(entry)) | |
311 | goto out; | |
312 | ||
313 | page = migration_entry_to_page(entry); | |
314 | ||
315 | /* | |
316 | * Once radix-tree replacement of page migration started, page_count | |
317 | * *must* be zero. And, we don't want to call wait_on_page_locked() | |
318 | * against a page without get_page(). | |
319 | * So, we use get_page_unless_zero(), here. Even failed, page fault | |
320 | * will occur again. | |
321 | */ | |
322 | if (!get_page_unless_zero(page)) | |
323 | goto out; | |
324 | pte_unmap_unlock(ptep, ptl); | |
325 | wait_on_page_locked(page); | |
326 | put_page(page); | |
327 | return; | |
328 | out: | |
329 | pte_unmap_unlock(ptep, ptl); | |
330 | } | |
331 | ||
332 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
333 | unsigned long address) | |
334 | { | |
335 | spinlock_t *ptl = pte_lockptr(mm, pmd); | |
336 | pte_t *ptep = pte_offset_map(pmd, address); | |
337 | __migration_entry_wait(mm, ptep, ptl); | |
338 | } | |
339 | ||
340 | void migration_entry_wait_huge(struct vm_area_struct *vma, | |
341 | struct mm_struct *mm, pte_t *pte) | |
342 | { | |
343 | spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); | |
344 | __migration_entry_wait(mm, pte, ptl); | |
345 | } | |
346 | ||
347 | #ifdef CONFIG_BLOCK | |
348 | /* Returns true if all buffers are successfully locked */ | |
349 | static bool buffer_migrate_lock_buffers(struct buffer_head *head, | |
350 | enum migrate_mode mode) | |
351 | { | |
352 | struct buffer_head *bh = head; | |
353 | ||
354 | /* Simple case, sync compaction */ | |
355 | if (mode != MIGRATE_ASYNC) { | |
356 | do { | |
357 | get_bh(bh); | |
358 | lock_buffer(bh); | |
359 | bh = bh->b_this_page; | |
360 | ||
361 | } while (bh != head); | |
362 | ||
363 | return true; | |
364 | } | |
365 | ||
366 | /* async case, we cannot block on lock_buffer so use trylock_buffer */ | |
367 | do { | |
368 | get_bh(bh); | |
369 | if (!trylock_buffer(bh)) { | |
370 | /* | |
371 | * We failed to lock the buffer and cannot stall in | |
372 | * async migration. Release the taken locks | |
373 | */ | |
374 | struct buffer_head *failed_bh = bh; | |
375 | put_bh(failed_bh); | |
376 | bh = head; | |
377 | while (bh != failed_bh) { | |
378 | unlock_buffer(bh); | |
379 | put_bh(bh); | |
380 | bh = bh->b_this_page; | |
381 | } | |
382 | return false; | |
383 | } | |
384 | ||
385 | bh = bh->b_this_page; | |
386 | } while (bh != head); | |
387 | return true; | |
388 | } | |
389 | #else | |
390 | static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, | |
391 | enum migrate_mode mode) | |
392 | { | |
393 | return true; | |
394 | } | |
395 | #endif /* CONFIG_BLOCK */ | |
396 | ||
397 | /* | |
398 | * Replace the page in the mapping. | |
399 | * | |
400 | * The number of remaining references must be: | |
401 | * 1 for anonymous pages without a mapping | |
402 | * 2 for pages with a mapping | |
403 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. | |
404 | */ | |
405 | int migrate_page_move_mapping(struct address_space *mapping, | |
406 | struct page *newpage, struct page *page, | |
407 | struct buffer_head *head, enum migrate_mode mode, | |
408 | int extra_count) | |
409 | { | |
410 | struct zone *oldzone, *newzone; | |
411 | int dirty; | |
412 | int expected_count = 1 + extra_count; | |
413 | void **pslot; | |
414 | ||
415 | if (!mapping) { | |
416 | /* Anonymous page without mapping */ | |
417 | if (page_count(page) != expected_count) | |
418 | return -EAGAIN; | |
419 | ||
420 | /* No turning back from here */ | |
421 | newpage->index = page->index; | |
422 | newpage->mapping = page->mapping; | |
423 | if (PageSwapBacked(page)) | |
424 | __SetPageSwapBacked(newpage); | |
425 | ||
426 | return MIGRATEPAGE_SUCCESS; | |
427 | } | |
428 | ||
429 | oldzone = page_zone(page); | |
430 | newzone = page_zone(newpage); | |
431 | ||
432 | spin_lock_irq(&mapping->tree_lock); | |
433 | ||
434 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
435 | page_index(page)); | |
436 | ||
437 | expected_count += 1 + page_has_private(page); | |
438 | if (page_count(page) != expected_count || | |
439 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { | |
440 | spin_unlock_irq(&mapping->tree_lock); | |
441 | return -EAGAIN; | |
442 | } | |
443 | ||
444 | if (!page_ref_freeze(page, expected_count)) { | |
445 | spin_unlock_irq(&mapping->tree_lock); | |
446 | return -EAGAIN; | |
447 | } | |
448 | ||
449 | /* | |
450 | * In the async migration case of moving a page with buffers, lock the | |
451 | * buffers using trylock before the mapping is moved. If the mapping | |
452 | * was moved, we later failed to lock the buffers and could not move | |
453 | * the mapping back due to an elevated page count, we would have to | |
454 | * block waiting on other references to be dropped. | |
455 | */ | |
456 | if (mode == MIGRATE_ASYNC && head && | |
457 | !buffer_migrate_lock_buffers(head, mode)) { | |
458 | page_ref_unfreeze(page, expected_count); | |
459 | spin_unlock_irq(&mapping->tree_lock); | |
460 | return -EAGAIN; | |
461 | } | |
462 | ||
463 | /* | |
464 | * Now we know that no one else is looking at the page: | |
465 | * no turning back from here. | |
466 | */ | |
467 | newpage->index = page->index; | |
468 | newpage->mapping = page->mapping; | |
469 | get_page(newpage); /* add cache reference */ | |
470 | if (PageSwapBacked(page)) { | |
471 | __SetPageSwapBacked(newpage); | |
472 | if (PageSwapCache(page)) { | |
473 | SetPageSwapCache(newpage); | |
474 | set_page_private(newpage, page_private(page)); | |
475 | } | |
476 | } else { | |
477 | VM_BUG_ON_PAGE(PageSwapCache(page), page); | |
478 | } | |
479 | ||
480 | /* Move dirty while page refs frozen and newpage not yet exposed */ | |
481 | dirty = PageDirty(page); | |
482 | if (dirty) { | |
483 | ClearPageDirty(page); | |
484 | SetPageDirty(newpage); | |
485 | } | |
486 | ||
487 | radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); | |
488 | ||
489 | /* | |
490 | * Drop cache reference from old page by unfreezing | |
491 | * to one less reference. | |
492 | * We know this isn't the last reference. | |
493 | */ | |
494 | page_ref_unfreeze(page, expected_count - 1); | |
495 | ||
496 | spin_unlock(&mapping->tree_lock); | |
497 | /* Leave irq disabled to prevent preemption while updating stats */ | |
498 | ||
499 | /* | |
500 | * If moved to a different zone then also account | |
501 | * the page for that zone. Other VM counters will be | |
502 | * taken care of when we establish references to the | |
503 | * new page and drop references to the old page. | |
504 | * | |
505 | * Note that anonymous pages are accounted for | |
506 | * via NR_FILE_PAGES and NR_ANON_MAPPED if they | |
507 | * are mapped to swap space. | |
508 | */ | |
509 | if (newzone != oldzone) { | |
510 | __dec_node_state(oldzone->zone_pgdat, NR_FILE_PAGES); | |
511 | __inc_node_state(newzone->zone_pgdat, NR_FILE_PAGES); | |
512 | if (PageSwapBacked(page) && !PageSwapCache(page)) { | |
513 | __dec_node_state(oldzone->zone_pgdat, NR_SHMEM); | |
514 | __inc_node_state(newzone->zone_pgdat, NR_SHMEM); | |
515 | } | |
516 | if (dirty && mapping_cap_account_dirty(mapping)) { | |
517 | __dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY); | |
518 | __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING); | |
519 | __inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY); | |
520 | __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING); | |
521 | } | |
522 | } | |
523 | local_irq_enable(); | |
524 | ||
525 | return MIGRATEPAGE_SUCCESS; | |
526 | } | |
527 | EXPORT_SYMBOL(migrate_page_move_mapping); | |
528 | ||
529 | /* | |
530 | * The expected number of remaining references is the same as that | |
531 | * of migrate_page_move_mapping(). | |
532 | */ | |
533 | int migrate_huge_page_move_mapping(struct address_space *mapping, | |
534 | struct page *newpage, struct page *page) | |
535 | { | |
536 | int expected_count; | |
537 | void **pslot; | |
538 | ||
539 | spin_lock_irq(&mapping->tree_lock); | |
540 | ||
541 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
542 | page_index(page)); | |
543 | ||
544 | expected_count = 2 + page_has_private(page); | |
545 | if (page_count(page) != expected_count || | |
546 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { | |
547 | spin_unlock_irq(&mapping->tree_lock); | |
548 | return -EAGAIN; | |
549 | } | |
550 | ||
551 | if (!page_ref_freeze(page, expected_count)) { | |
552 | spin_unlock_irq(&mapping->tree_lock); | |
553 | return -EAGAIN; | |
554 | } | |
555 | ||
556 | newpage->index = page->index; | |
557 | newpage->mapping = page->mapping; | |
558 | ||
559 | get_page(newpage); | |
560 | ||
561 | radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); | |
562 | ||
563 | page_ref_unfreeze(page, expected_count - 1); | |
564 | ||
565 | spin_unlock_irq(&mapping->tree_lock); | |
566 | ||
567 | return MIGRATEPAGE_SUCCESS; | |
568 | } | |
569 | ||
570 | /* | |
571 | * Gigantic pages are so large that we do not guarantee that page++ pointer | |
572 | * arithmetic will work across the entire page. We need something more | |
573 | * specialized. | |
574 | */ | |
575 | static void __copy_gigantic_page(struct page *dst, struct page *src, | |
576 | int nr_pages) | |
577 | { | |
578 | int i; | |
579 | struct page *dst_base = dst; | |
580 | struct page *src_base = src; | |
581 | ||
582 | for (i = 0; i < nr_pages; ) { | |
583 | cond_resched(); | |
584 | copy_highpage(dst, src); | |
585 | ||
586 | i++; | |
587 | dst = mem_map_next(dst, dst_base, i); | |
588 | src = mem_map_next(src, src_base, i); | |
589 | } | |
590 | } | |
591 | ||
592 | static void copy_huge_page(struct page *dst, struct page *src) | |
593 | { | |
594 | int i; | |
595 | int nr_pages; | |
596 | ||
597 | if (PageHuge(src)) { | |
598 | /* hugetlbfs page */ | |
599 | struct hstate *h = page_hstate(src); | |
600 | nr_pages = pages_per_huge_page(h); | |
601 | ||
602 | if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { | |
603 | __copy_gigantic_page(dst, src, nr_pages); | |
604 | return; | |
605 | } | |
606 | } else { | |
607 | /* thp page */ | |
608 | BUG_ON(!PageTransHuge(src)); | |
609 | nr_pages = hpage_nr_pages(src); | |
610 | } | |
611 | ||
612 | for (i = 0; i < nr_pages; i++) { | |
613 | cond_resched(); | |
614 | copy_highpage(dst + i, src + i); | |
615 | } | |
616 | } | |
617 | ||
618 | /* | |
619 | * Copy the page to its new location | |
620 | */ | |
621 | void migrate_page_copy(struct page *newpage, struct page *page) | |
622 | { | |
623 | int cpupid; | |
624 | ||
625 | if (PageHuge(page) || PageTransHuge(page)) | |
626 | copy_huge_page(newpage, page); | |
627 | else | |
628 | copy_highpage(newpage, page); | |
629 | ||
630 | if (PageError(page)) | |
631 | SetPageError(newpage); | |
632 | if (PageReferenced(page)) | |
633 | SetPageReferenced(newpage); | |
634 | if (PageUptodate(page)) | |
635 | SetPageUptodate(newpage); | |
636 | if (TestClearPageActive(page)) { | |
637 | VM_BUG_ON_PAGE(PageUnevictable(page), page); | |
638 | SetPageActive(newpage); | |
639 | } else if (TestClearPageUnevictable(page)) | |
640 | SetPageUnevictable(newpage); | |
641 | if (PageChecked(page)) | |
642 | SetPageChecked(newpage); | |
643 | if (PageMappedToDisk(page)) | |
644 | SetPageMappedToDisk(newpage); | |
645 | ||
646 | /* Move dirty on pages not done by migrate_page_move_mapping() */ | |
647 | if (PageDirty(page)) | |
648 | SetPageDirty(newpage); | |
649 | ||
650 | if (page_is_young(page)) | |
651 | set_page_young(newpage); | |
652 | if (page_is_idle(page)) | |
653 | set_page_idle(newpage); | |
654 | ||
655 | /* | |
656 | * Copy NUMA information to the new page, to prevent over-eager | |
657 | * future migrations of this same page. | |
658 | */ | |
659 | cpupid = page_cpupid_xchg_last(page, -1); | |
660 | page_cpupid_xchg_last(newpage, cpupid); | |
661 | ||
662 | ksm_migrate_page(newpage, page); | |
663 | /* | |
664 | * Please do not reorder this without considering how mm/ksm.c's | |
665 | * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). | |
666 | */ | |
667 | if (PageSwapCache(page)) | |
668 | ClearPageSwapCache(page); | |
669 | ClearPagePrivate(page); | |
670 | set_page_private(page, 0); | |
671 | ||
672 | /* | |
673 | * If any waiters have accumulated on the new page then | |
674 | * wake them up. | |
675 | */ | |
676 | if (PageWriteback(newpage)) | |
677 | end_page_writeback(newpage); | |
678 | ||
679 | copy_page_owner(page, newpage); | |
680 | ||
681 | mem_cgroup_migrate(page, newpage); | |
682 | } | |
683 | EXPORT_SYMBOL(migrate_page_copy); | |
684 | ||
685 | /************************************************************ | |
686 | * Migration functions | |
687 | ***********************************************************/ | |
688 | ||
689 | /* | |
690 | * Common logic to directly migrate a single LRU page suitable for | |
691 | * pages that do not use PagePrivate/PagePrivate2. | |
692 | * | |
693 | * Pages are locked upon entry and exit. | |
694 | */ | |
695 | int migrate_page(struct address_space *mapping, | |
696 | struct page *newpage, struct page *page, | |
697 | enum migrate_mode mode) | |
698 | { | |
699 | int rc; | |
700 | ||
701 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
702 | ||
703 | rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); | |
704 | ||
705 | if (rc != MIGRATEPAGE_SUCCESS) | |
706 | return rc; | |
707 | ||
708 | migrate_page_copy(newpage, page); | |
709 | return MIGRATEPAGE_SUCCESS; | |
710 | } | |
711 | EXPORT_SYMBOL(migrate_page); | |
712 | ||
713 | #ifdef CONFIG_BLOCK | |
714 | /* | |
715 | * Migration function for pages with buffers. This function can only be used | |
716 | * if the underlying filesystem guarantees that no other references to "page" | |
717 | * exist. | |
718 | */ | |
719 | int buffer_migrate_page(struct address_space *mapping, | |
720 | struct page *newpage, struct page *page, enum migrate_mode mode) | |
721 | { | |
722 | struct buffer_head *bh, *head; | |
723 | int rc; | |
724 | ||
725 | if (!page_has_buffers(page)) | |
726 | return migrate_page(mapping, newpage, page, mode); | |
727 | ||
728 | head = page_buffers(page); | |
729 | ||
730 | rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0); | |
731 | ||
732 | if (rc != MIGRATEPAGE_SUCCESS) | |
733 | return rc; | |
734 | ||
735 | /* | |
736 | * In the async case, migrate_page_move_mapping locked the buffers | |
737 | * with an IRQ-safe spinlock held. In the sync case, the buffers | |
738 | * need to be locked now | |
739 | */ | |
740 | if (mode != MIGRATE_ASYNC) | |
741 | BUG_ON(!buffer_migrate_lock_buffers(head, mode)); | |
742 | ||
743 | ClearPagePrivate(page); | |
744 | set_page_private(newpage, page_private(page)); | |
745 | set_page_private(page, 0); | |
746 | put_page(page); | |
747 | get_page(newpage); | |
748 | ||
749 | bh = head; | |
750 | do { | |
751 | set_bh_page(bh, newpage, bh_offset(bh)); | |
752 | bh = bh->b_this_page; | |
753 | ||
754 | } while (bh != head); | |
755 | ||
756 | SetPagePrivate(newpage); | |
757 | ||
758 | migrate_page_copy(newpage, page); | |
759 | ||
760 | bh = head; | |
761 | do { | |
762 | unlock_buffer(bh); | |
763 | put_bh(bh); | |
764 | bh = bh->b_this_page; | |
765 | ||
766 | } while (bh != head); | |
767 | ||
768 | return MIGRATEPAGE_SUCCESS; | |
769 | } | |
770 | EXPORT_SYMBOL(buffer_migrate_page); | |
771 | #endif | |
772 | ||
773 | /* | |
774 | * Writeback a page to clean the dirty state | |
775 | */ | |
776 | static int writeout(struct address_space *mapping, struct page *page) | |
777 | { | |
778 | struct writeback_control wbc = { | |
779 | .sync_mode = WB_SYNC_NONE, | |
780 | .nr_to_write = 1, | |
781 | .range_start = 0, | |
782 | .range_end = LLONG_MAX, | |
783 | .for_reclaim = 1 | |
784 | }; | |
785 | int rc; | |
786 | ||
787 | if (!mapping->a_ops->writepage) | |
788 | /* No write method for the address space */ | |
789 | return -EINVAL; | |
790 | ||
791 | if (!clear_page_dirty_for_io(page)) | |
792 | /* Someone else already triggered a write */ | |
793 | return -EAGAIN; | |
794 | ||
795 | /* | |
796 | * A dirty page may imply that the underlying filesystem has | |
797 | * the page on some queue. So the page must be clean for | |
798 | * migration. Writeout may mean we loose the lock and the | |
799 | * page state is no longer what we checked for earlier. | |
800 | * At this point we know that the migration attempt cannot | |
801 | * be successful. | |
802 | */ | |
803 | remove_migration_ptes(page, page, false); | |
804 | ||
805 | rc = mapping->a_ops->writepage(page, &wbc); | |
806 | ||
807 | if (rc != AOP_WRITEPAGE_ACTIVATE) | |
808 | /* unlocked. Relock */ | |
809 | lock_page(page); | |
810 | ||
811 | return (rc < 0) ? -EIO : -EAGAIN; | |
812 | } | |
813 | ||
814 | /* | |
815 | * Default handling if a filesystem does not provide a migration function. | |
816 | */ | |
817 | static int fallback_migrate_page(struct address_space *mapping, | |
818 | struct page *newpage, struct page *page, enum migrate_mode mode) | |
819 | { | |
820 | if (PageDirty(page)) { | |
821 | /* Only writeback pages in full synchronous migration */ | |
822 | if (mode != MIGRATE_SYNC) | |
823 | return -EBUSY; | |
824 | return writeout(mapping, page); | |
825 | } | |
826 | ||
827 | /* | |
828 | * Buffers may be managed in a filesystem specific way. | |
829 | * We must have no buffers or drop them. | |
830 | */ | |
831 | if (page_has_private(page) && | |
832 | !try_to_release_page(page, GFP_KERNEL)) | |
833 | return -EAGAIN; | |
834 | ||
835 | return migrate_page(mapping, newpage, page, mode); | |
836 | } | |
837 | ||
838 | /* | |
839 | * Move a page to a newly allocated page | |
840 | * The page is locked and all ptes have been successfully removed. | |
841 | * | |
842 | * The new page will have replaced the old page if this function | |
843 | * is successful. | |
844 | * | |
845 | * Return value: | |
846 | * < 0 - error code | |
847 | * MIGRATEPAGE_SUCCESS - success | |
848 | */ | |
849 | static int move_to_new_page(struct page *newpage, struct page *page, | |
850 | enum migrate_mode mode) | |
851 | { | |
852 | struct address_space *mapping; | |
853 | int rc = -EAGAIN; | |
854 | bool is_lru = !__PageMovable(page); | |
855 | ||
856 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
857 | VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); | |
858 | ||
859 | mapping = page_mapping(page); | |
860 | ||
861 | if (likely(is_lru)) { | |
862 | if (!mapping) | |
863 | rc = migrate_page(mapping, newpage, page, mode); | |
864 | else if (mapping->a_ops->migratepage) | |
865 | /* | |
866 | * Most pages have a mapping and most filesystems | |
867 | * provide a migratepage callback. Anonymous pages | |
868 | * are part of swap space which also has its own | |
869 | * migratepage callback. This is the most common path | |
870 | * for page migration. | |
871 | */ | |
872 | rc = mapping->a_ops->migratepage(mapping, newpage, | |
873 | page, mode); | |
874 | else | |
875 | rc = fallback_migrate_page(mapping, newpage, | |
876 | page, mode); | |
877 | } else { | |
878 | /* | |
879 | * In case of non-lru page, it could be released after | |
880 | * isolation step. In that case, we shouldn't try migration. | |
881 | */ | |
882 | VM_BUG_ON_PAGE(!PageIsolated(page), page); | |
883 | if (!PageMovable(page)) { | |
884 | rc = MIGRATEPAGE_SUCCESS; | |
885 | __ClearPageIsolated(page); | |
886 | goto out; | |
887 | } | |
888 | ||
889 | rc = mapping->a_ops->migratepage(mapping, newpage, | |
890 | page, mode); | |
891 | WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS && | |
892 | !PageIsolated(page)); | |
893 | } | |
894 | ||
895 | /* | |
896 | * When successful, old pagecache page->mapping must be cleared before | |
897 | * page is freed; but stats require that PageAnon be left as PageAnon. | |
898 | */ | |
899 | if (rc == MIGRATEPAGE_SUCCESS) { | |
900 | if (__PageMovable(page)) { | |
901 | VM_BUG_ON_PAGE(!PageIsolated(page), page); | |
902 | ||
903 | /* | |
904 | * We clear PG_movable under page_lock so any compactor | |
905 | * cannot try to migrate this page. | |
906 | */ | |
907 | __ClearPageIsolated(page); | |
908 | } | |
909 | ||
910 | /* | |
911 | * Anonymous and movable page->mapping will be cleard by | |
912 | * free_pages_prepare so don't reset it here for keeping | |
913 | * the type to work PageAnon, for example. | |
914 | */ | |
915 | if (!PageMappingFlags(page)) | |
916 | page->mapping = NULL; | |
917 | } | |
918 | out: | |
919 | return rc; | |
920 | } | |
921 | ||
922 | static int __unmap_and_move(struct page *page, struct page *newpage, | |
923 | int force, enum migrate_mode mode) | |
924 | { | |
925 | int rc = -EAGAIN; | |
926 | int page_was_mapped = 0; | |
927 | struct anon_vma *anon_vma = NULL; | |
928 | bool is_lru = !__PageMovable(page); | |
929 | ||
930 | if (!trylock_page(page)) { | |
931 | if (!force || mode == MIGRATE_ASYNC) | |
932 | goto out; | |
933 | ||
934 | /* | |
935 | * It's not safe for direct compaction to call lock_page. | |
936 | * For example, during page readahead pages are added locked | |
937 | * to the LRU. Later, when the IO completes the pages are | |
938 | * marked uptodate and unlocked. However, the queueing | |
939 | * could be merging multiple pages for one bio (e.g. | |
940 | * mpage_readpages). If an allocation happens for the | |
941 | * second or third page, the process can end up locking | |
942 | * the same page twice and deadlocking. Rather than | |
943 | * trying to be clever about what pages can be locked, | |
944 | * avoid the use of lock_page for direct compaction | |
945 | * altogether. | |
946 | */ | |
947 | if (current->flags & PF_MEMALLOC) | |
948 | goto out; | |
949 | ||
950 | lock_page(page); | |
951 | } | |
952 | ||
953 | if (PageWriteback(page)) { | |
954 | /* | |
955 | * Only in the case of a full synchronous migration is it | |
956 | * necessary to wait for PageWriteback. In the async case, | |
957 | * the retry loop is too short and in the sync-light case, | |
958 | * the overhead of stalling is too much | |
959 | */ | |
960 | if (mode != MIGRATE_SYNC) { | |
961 | rc = -EBUSY; | |
962 | goto out_unlock; | |
963 | } | |
964 | if (!force) | |
965 | goto out_unlock; | |
966 | wait_on_page_writeback(page); | |
967 | } | |
968 | ||
969 | /* | |
970 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, | |
971 | * we cannot notice that anon_vma is freed while we migrates a page. | |
972 | * This get_anon_vma() delays freeing anon_vma pointer until the end | |
973 | * of migration. File cache pages are no problem because of page_lock() | |
974 | * File Caches may use write_page() or lock_page() in migration, then, | |
975 | * just care Anon page here. | |
976 | * | |
977 | * Only page_get_anon_vma() understands the subtleties of | |
978 | * getting a hold on an anon_vma from outside one of its mms. | |
979 | * But if we cannot get anon_vma, then we won't need it anyway, | |
980 | * because that implies that the anon page is no longer mapped | |
981 | * (and cannot be remapped so long as we hold the page lock). | |
982 | */ | |
983 | if (PageAnon(page) && !PageKsm(page)) | |
984 | anon_vma = page_get_anon_vma(page); | |
985 | ||
986 | /* | |
987 | * Block others from accessing the new page when we get around to | |
988 | * establishing additional references. We are usually the only one | |
989 | * holding a reference to newpage at this point. We used to have a BUG | |
990 | * here if trylock_page(newpage) fails, but would like to allow for | |
991 | * cases where there might be a race with the previous use of newpage. | |
992 | * This is much like races on refcount of oldpage: just don't BUG(). | |
993 | */ | |
994 | if (unlikely(!trylock_page(newpage))) | |
995 | goto out_unlock; | |
996 | ||
997 | if (unlikely(!is_lru)) { | |
998 | rc = move_to_new_page(newpage, page, mode); | |
999 | goto out_unlock_both; | |
1000 | } | |
1001 | ||
1002 | /* | |
1003 | * Corner case handling: | |
1004 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
1005 | * and treated as swapcache but it has no rmap yet. | |
1006 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
1007 | * trigger a BUG. So handle it here. | |
1008 | * 2. An orphaned page (see truncate_complete_page) might have | |
1009 | * fs-private metadata. The page can be picked up due to memory | |
1010 | * offlining. Everywhere else except page reclaim, the page is | |
1011 | * invisible to the vm, so the page can not be migrated. So try to | |
1012 | * free the metadata, so the page can be freed. | |
1013 | */ | |
1014 | if (!page->mapping) { | |
1015 | VM_BUG_ON_PAGE(PageAnon(page), page); | |
1016 | if (page_has_private(page)) { | |
1017 | try_to_free_buffers(page); | |
1018 | goto out_unlock_both; | |
1019 | } | |
1020 | } else if (page_mapped(page)) { | |
1021 | /* Establish migration ptes */ | |
1022 | VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma, | |
1023 | page); | |
1024 | try_to_unmap(page, | |
1025 | TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); | |
1026 | page_was_mapped = 1; | |
1027 | } | |
1028 | ||
1029 | if (!page_mapped(page)) | |
1030 | rc = move_to_new_page(newpage, page, mode); | |
1031 | ||
1032 | if (page_was_mapped) | |
1033 | remove_migration_ptes(page, | |
1034 | rc == MIGRATEPAGE_SUCCESS ? newpage : page, false); | |
1035 | ||
1036 | out_unlock_both: | |
1037 | unlock_page(newpage); | |
1038 | out_unlock: | |
1039 | /* Drop an anon_vma reference if we took one */ | |
1040 | if (anon_vma) | |
1041 | put_anon_vma(anon_vma); | |
1042 | unlock_page(page); | |
1043 | out: | |
1044 | /* | |
1045 | * If migration is successful, decrease refcount of the newpage | |
1046 | * which will not free the page because new page owner increased | |
1047 | * refcounter. As well, if it is LRU page, add the page to LRU | |
1048 | * list in here. | |
1049 | */ | |
1050 | if (rc == MIGRATEPAGE_SUCCESS) { | |
1051 | if (unlikely(__PageMovable(newpage))) | |
1052 | put_page(newpage); | |
1053 | else | |
1054 | putback_lru_page(newpage); | |
1055 | } | |
1056 | ||
1057 | return rc; | |
1058 | } | |
1059 | ||
1060 | /* | |
1061 | * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work | |
1062 | * around it. | |
1063 | */ | |
1064 | #if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM) | |
1065 | #define ICE_noinline noinline | |
1066 | #else | |
1067 | #define ICE_noinline | |
1068 | #endif | |
1069 | ||
1070 | /* | |
1071 | * Obtain the lock on page, remove all ptes and migrate the page | |
1072 | * to the newly allocated page in newpage. | |
1073 | */ | |
1074 | static ICE_noinline int unmap_and_move(new_page_t get_new_page, | |
1075 | free_page_t put_new_page, | |
1076 | unsigned long private, struct page *page, | |
1077 | int force, enum migrate_mode mode, | |
1078 | enum migrate_reason reason) | |
1079 | { | |
1080 | int rc = MIGRATEPAGE_SUCCESS; | |
1081 | int *result = NULL; | |
1082 | struct page *newpage; | |
1083 | ||
1084 | newpage = get_new_page(page, private, &result); | |
1085 | if (!newpage) | |
1086 | return -ENOMEM; | |
1087 | ||
1088 | if (page_count(page) == 1) { | |
1089 | /* page was freed from under us. So we are done. */ | |
1090 | ClearPageActive(page); | |
1091 | ClearPageUnevictable(page); | |
1092 | if (unlikely(__PageMovable(page))) { | |
1093 | lock_page(page); | |
1094 | if (!PageMovable(page)) | |
1095 | __ClearPageIsolated(page); | |
1096 | unlock_page(page); | |
1097 | } | |
1098 | if (put_new_page) | |
1099 | put_new_page(newpage, private); | |
1100 | else | |
1101 | put_page(newpage); | |
1102 | goto out; | |
1103 | } | |
1104 | ||
1105 | if (unlikely(PageTransHuge(page))) { | |
1106 | lock_page(page); | |
1107 | rc = split_huge_page(page); | |
1108 | unlock_page(page); | |
1109 | if (rc) | |
1110 | goto out; | |
1111 | } | |
1112 | ||
1113 | rc = __unmap_and_move(page, newpage, force, mode); | |
1114 | if (rc == MIGRATEPAGE_SUCCESS) | |
1115 | set_page_owner_migrate_reason(newpage, reason); | |
1116 | ||
1117 | out: | |
1118 | if (rc != -EAGAIN) { | |
1119 | /* | |
1120 | * A page that has been migrated has all references | |
1121 | * removed and will be freed. A page that has not been | |
1122 | * migrated will have kepts its references and be | |
1123 | * restored. | |
1124 | */ | |
1125 | list_del(&page->lru); | |
1126 | ||
1127 | /* | |
1128 | * Compaction can migrate also non-LRU pages which are | |
1129 | * not accounted to NR_ISOLATED_*. They can be recognized | |
1130 | * as __PageMovable | |
1131 | */ | |
1132 | if (likely(!__PageMovable(page))) | |
1133 | dec_node_page_state(page, NR_ISOLATED_ANON + | |
1134 | page_is_file_cache(page)); | |
1135 | } | |
1136 | ||
1137 | /* | |
1138 | * If migration is successful, releases reference grabbed during | |
1139 | * isolation. Otherwise, restore the page to right list unless | |
1140 | * we want to retry. | |
1141 | */ | |
1142 | if (rc == MIGRATEPAGE_SUCCESS) { | |
1143 | put_page(page); | |
1144 | if (reason == MR_MEMORY_FAILURE) { | |
1145 | /* | |
1146 | * Set PG_HWPoison on just freed page | |
1147 | * intentionally. Although it's rather weird, | |
1148 | * it's how HWPoison flag works at the moment. | |
1149 | */ | |
1150 | if (!test_set_page_hwpoison(page)) | |
1151 | num_poisoned_pages_inc(); | |
1152 | } | |
1153 | } else { | |
1154 | if (rc != -EAGAIN) { | |
1155 | if (likely(!__PageMovable(page))) { | |
1156 | putback_lru_page(page); | |
1157 | goto put_new; | |
1158 | } | |
1159 | ||
1160 | lock_page(page); | |
1161 | if (PageMovable(page)) | |
1162 | putback_movable_page(page); | |
1163 | else | |
1164 | __ClearPageIsolated(page); | |
1165 | unlock_page(page); | |
1166 | put_page(page); | |
1167 | } | |
1168 | put_new: | |
1169 | if (put_new_page) | |
1170 | put_new_page(newpage, private); | |
1171 | else | |
1172 | put_page(newpage); | |
1173 | } | |
1174 | ||
1175 | if (result) { | |
1176 | if (rc) | |
1177 | *result = rc; | |
1178 | else | |
1179 | *result = page_to_nid(newpage); | |
1180 | } | |
1181 | return rc; | |
1182 | } | |
1183 | ||
1184 | /* | |
1185 | * Counterpart of unmap_and_move_page() for hugepage migration. | |
1186 | * | |
1187 | * This function doesn't wait the completion of hugepage I/O | |
1188 | * because there is no race between I/O and migration for hugepage. | |
1189 | * Note that currently hugepage I/O occurs only in direct I/O | |
1190 | * where no lock is held and PG_writeback is irrelevant, | |
1191 | * and writeback status of all subpages are counted in the reference | |
1192 | * count of the head page (i.e. if all subpages of a 2MB hugepage are | |
1193 | * under direct I/O, the reference of the head page is 512 and a bit more.) | |
1194 | * This means that when we try to migrate hugepage whose subpages are | |
1195 | * doing direct I/O, some references remain after try_to_unmap() and | |
1196 | * hugepage migration fails without data corruption. | |
1197 | * | |
1198 | * There is also no race when direct I/O is issued on the page under migration, | |
1199 | * because then pte is replaced with migration swap entry and direct I/O code | |
1200 | * will wait in the page fault for migration to complete. | |
1201 | */ | |
1202 | static int unmap_and_move_huge_page(new_page_t get_new_page, | |
1203 | free_page_t put_new_page, unsigned long private, | |
1204 | struct page *hpage, int force, | |
1205 | enum migrate_mode mode, int reason) | |
1206 | { | |
1207 | int rc = -EAGAIN; | |
1208 | int *result = NULL; | |
1209 | int page_was_mapped = 0; | |
1210 | struct page *new_hpage; | |
1211 | struct anon_vma *anon_vma = NULL; | |
1212 | ||
1213 | /* | |
1214 | * Movability of hugepages depends on architectures and hugepage size. | |
1215 | * This check is necessary because some callers of hugepage migration | |
1216 | * like soft offline and memory hotremove don't walk through page | |
1217 | * tables or check whether the hugepage is pmd-based or not before | |
1218 | * kicking migration. | |
1219 | */ | |
1220 | if (!hugepage_migration_supported(page_hstate(hpage))) { | |
1221 | putback_active_hugepage(hpage); | |
1222 | return -ENOSYS; | |
1223 | } | |
1224 | ||
1225 | new_hpage = get_new_page(hpage, private, &result); | |
1226 | if (!new_hpage) | |
1227 | return -ENOMEM; | |
1228 | ||
1229 | if (!trylock_page(hpage)) { | |
1230 | if (!force || mode != MIGRATE_SYNC) | |
1231 | goto out; | |
1232 | lock_page(hpage); | |
1233 | } | |
1234 | ||
1235 | if (PageAnon(hpage)) | |
1236 | anon_vma = page_get_anon_vma(hpage); | |
1237 | ||
1238 | if (unlikely(!trylock_page(new_hpage))) | |
1239 | goto put_anon; | |
1240 | ||
1241 | if (page_mapped(hpage)) { | |
1242 | try_to_unmap(hpage, | |
1243 | TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); | |
1244 | page_was_mapped = 1; | |
1245 | } | |
1246 | ||
1247 | if (!page_mapped(hpage)) | |
1248 | rc = move_to_new_page(new_hpage, hpage, mode); | |
1249 | ||
1250 | if (page_was_mapped) | |
1251 | remove_migration_ptes(hpage, | |
1252 | rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false); | |
1253 | ||
1254 | unlock_page(new_hpage); | |
1255 | ||
1256 | put_anon: | |
1257 | if (anon_vma) | |
1258 | put_anon_vma(anon_vma); | |
1259 | ||
1260 | if (rc == MIGRATEPAGE_SUCCESS) { | |
1261 | hugetlb_cgroup_migrate(hpage, new_hpage); | |
1262 | put_new_page = NULL; | |
1263 | set_page_owner_migrate_reason(new_hpage, reason); | |
1264 | } | |
1265 | ||
1266 | unlock_page(hpage); | |
1267 | out: | |
1268 | if (rc != -EAGAIN) | |
1269 | putback_active_hugepage(hpage); | |
1270 | ||
1271 | /* | |
1272 | * If migration was not successful and there's a freeing callback, use | |
1273 | * it. Otherwise, put_page() will drop the reference grabbed during | |
1274 | * isolation. | |
1275 | */ | |
1276 | if (put_new_page) | |
1277 | put_new_page(new_hpage, private); | |
1278 | else | |
1279 | putback_active_hugepage(new_hpage); | |
1280 | ||
1281 | if (result) { | |
1282 | if (rc) | |
1283 | *result = rc; | |
1284 | else | |
1285 | *result = page_to_nid(new_hpage); | |
1286 | } | |
1287 | return rc; | |
1288 | } | |
1289 | ||
1290 | /* | |
1291 | * migrate_pages - migrate the pages specified in a list, to the free pages | |
1292 | * supplied as the target for the page migration | |
1293 | * | |
1294 | * @from: The list of pages to be migrated. | |
1295 | * @get_new_page: The function used to allocate free pages to be used | |
1296 | * as the target of the page migration. | |
1297 | * @put_new_page: The function used to free target pages if migration | |
1298 | * fails, or NULL if no special handling is necessary. | |
1299 | * @private: Private data to be passed on to get_new_page() | |
1300 | * @mode: The migration mode that specifies the constraints for | |
1301 | * page migration, if any. | |
1302 | * @reason: The reason for page migration. | |
1303 | * | |
1304 | * The function returns after 10 attempts or if no pages are movable any more | |
1305 | * because the list has become empty or no retryable pages exist any more. | |
1306 | * The caller should call putback_movable_pages() to return pages to the LRU | |
1307 | * or free list only if ret != 0. | |
1308 | * | |
1309 | * Returns the number of pages that were not migrated, or an error code. | |
1310 | */ | |
1311 | int migrate_pages(struct list_head *from, new_page_t get_new_page, | |
1312 | free_page_t put_new_page, unsigned long private, | |
1313 | enum migrate_mode mode, int reason) | |
1314 | { | |
1315 | int retry = 1; | |
1316 | int nr_failed = 0; | |
1317 | int nr_succeeded = 0; | |
1318 | int pass = 0; | |
1319 | struct page *page; | |
1320 | struct page *page2; | |
1321 | int swapwrite = current->flags & PF_SWAPWRITE; | |
1322 | int rc; | |
1323 | ||
1324 | if (!swapwrite) | |
1325 | current->flags |= PF_SWAPWRITE; | |
1326 | ||
1327 | for(pass = 0; pass < 10 && retry; pass++) { | |
1328 | retry = 0; | |
1329 | ||
1330 | list_for_each_entry_safe(page, page2, from, lru) { | |
1331 | cond_resched(); | |
1332 | ||
1333 | if (PageHuge(page)) | |
1334 | rc = unmap_and_move_huge_page(get_new_page, | |
1335 | put_new_page, private, page, | |
1336 | pass > 2, mode, reason); | |
1337 | else | |
1338 | rc = unmap_and_move(get_new_page, put_new_page, | |
1339 | private, page, pass > 2, mode, | |
1340 | reason); | |
1341 | ||
1342 | switch(rc) { | |
1343 | case -ENOMEM: | |
1344 | nr_failed++; | |
1345 | goto out; | |
1346 | case -EAGAIN: | |
1347 | retry++; | |
1348 | break; | |
1349 | case MIGRATEPAGE_SUCCESS: | |
1350 | nr_succeeded++; | |
1351 | break; | |
1352 | default: | |
1353 | /* | |
1354 | * Permanent failure (-EBUSY, -ENOSYS, etc.): | |
1355 | * unlike -EAGAIN case, the failed page is | |
1356 | * removed from migration page list and not | |
1357 | * retried in the next outer loop. | |
1358 | */ | |
1359 | nr_failed++; | |
1360 | break; | |
1361 | } | |
1362 | } | |
1363 | } | |
1364 | nr_failed += retry; | |
1365 | rc = nr_failed; | |
1366 | out: | |
1367 | if (nr_succeeded) | |
1368 | count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); | |
1369 | if (nr_failed) | |
1370 | count_vm_events(PGMIGRATE_FAIL, nr_failed); | |
1371 | trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); | |
1372 | ||
1373 | if (!swapwrite) | |
1374 | current->flags &= ~PF_SWAPWRITE; | |
1375 | ||
1376 | return rc; | |
1377 | } | |
1378 | ||
1379 | #ifdef CONFIG_NUMA | |
1380 | /* | |
1381 | * Move a list of individual pages | |
1382 | */ | |
1383 | struct page_to_node { | |
1384 | unsigned long addr; | |
1385 | struct page *page; | |
1386 | int node; | |
1387 | int status; | |
1388 | }; | |
1389 | ||
1390 | static struct page *new_page_node(struct page *p, unsigned long private, | |
1391 | int **result) | |
1392 | { | |
1393 | struct page_to_node *pm = (struct page_to_node *)private; | |
1394 | ||
1395 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
1396 | pm++; | |
1397 | ||
1398 | if (pm->node == MAX_NUMNODES) | |
1399 | return NULL; | |
1400 | ||
1401 | *result = &pm->status; | |
1402 | ||
1403 | if (PageHuge(p)) | |
1404 | return alloc_huge_page_node(page_hstate(compound_head(p)), | |
1405 | pm->node); | |
1406 | else | |
1407 | return __alloc_pages_node(pm->node, | |
1408 | GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0); | |
1409 | } | |
1410 | ||
1411 | /* | |
1412 | * Move a set of pages as indicated in the pm array. The addr | |
1413 | * field must be set to the virtual address of the page to be moved | |
1414 | * and the node number must contain a valid target node. | |
1415 | * The pm array ends with node = MAX_NUMNODES. | |
1416 | */ | |
1417 | static int do_move_page_to_node_array(struct mm_struct *mm, | |
1418 | struct page_to_node *pm, | |
1419 | int migrate_all) | |
1420 | { | |
1421 | int err; | |
1422 | struct page_to_node *pp; | |
1423 | LIST_HEAD(pagelist); | |
1424 | ||
1425 | down_read(&mm->mmap_sem); | |
1426 | ||
1427 | /* | |
1428 | * Build a list of pages to migrate | |
1429 | */ | |
1430 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { | |
1431 | struct vm_area_struct *vma; | |
1432 | struct page *page; | |
1433 | ||
1434 | err = -EFAULT; | |
1435 | vma = find_vma(mm, pp->addr); | |
1436 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) | |
1437 | goto set_status; | |
1438 | ||
1439 | /* FOLL_DUMP to ignore special (like zero) pages */ | |
1440 | page = follow_page(vma, pp->addr, | |
1441 | FOLL_GET | FOLL_SPLIT | FOLL_DUMP); | |
1442 | ||
1443 | err = PTR_ERR(page); | |
1444 | if (IS_ERR(page)) | |
1445 | goto set_status; | |
1446 | ||
1447 | err = -ENOENT; | |
1448 | if (!page) | |
1449 | goto set_status; | |
1450 | ||
1451 | pp->page = page; | |
1452 | err = page_to_nid(page); | |
1453 | ||
1454 | if (err == pp->node) | |
1455 | /* | |
1456 | * Node already in the right place | |
1457 | */ | |
1458 | goto put_and_set; | |
1459 | ||
1460 | err = -EACCES; | |
1461 | if (page_mapcount(page) > 1 && | |
1462 | !migrate_all) | |
1463 | goto put_and_set; | |
1464 | ||
1465 | if (PageHuge(page)) { | |
1466 | if (PageHead(page)) | |
1467 | isolate_huge_page(page, &pagelist); | |
1468 | goto put_and_set; | |
1469 | } | |
1470 | ||
1471 | err = isolate_lru_page(page); | |
1472 | if (!err) { | |
1473 | list_add_tail(&page->lru, &pagelist); | |
1474 | inc_node_page_state(page, NR_ISOLATED_ANON + | |
1475 | page_is_file_cache(page)); | |
1476 | } | |
1477 | put_and_set: | |
1478 | /* | |
1479 | * Either remove the duplicate refcount from | |
1480 | * isolate_lru_page() or drop the page ref if it was | |
1481 | * not isolated. | |
1482 | */ | |
1483 | put_page(page); | |
1484 | set_status: | |
1485 | pp->status = err; | |
1486 | } | |
1487 | ||
1488 | err = 0; | |
1489 | if (!list_empty(&pagelist)) { | |
1490 | err = migrate_pages(&pagelist, new_page_node, NULL, | |
1491 | (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL); | |
1492 | if (err) | |
1493 | putback_movable_pages(&pagelist); | |
1494 | } | |
1495 | ||
1496 | up_read(&mm->mmap_sem); | |
1497 | return err; | |
1498 | } | |
1499 | ||
1500 | /* | |
1501 | * Migrate an array of page address onto an array of nodes and fill | |
1502 | * the corresponding array of status. | |
1503 | */ | |
1504 | static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, | |
1505 | unsigned long nr_pages, | |
1506 | const void __user * __user *pages, | |
1507 | const int __user *nodes, | |
1508 | int __user *status, int flags) | |
1509 | { | |
1510 | struct page_to_node *pm; | |
1511 | unsigned long chunk_nr_pages; | |
1512 | unsigned long chunk_start; | |
1513 | int err; | |
1514 | ||
1515 | err = -ENOMEM; | |
1516 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); | |
1517 | if (!pm) | |
1518 | goto out; | |
1519 | ||
1520 | migrate_prep(); | |
1521 | ||
1522 | /* | |
1523 | * Store a chunk of page_to_node array in a page, | |
1524 | * but keep the last one as a marker | |
1525 | */ | |
1526 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; | |
1527 | ||
1528 | for (chunk_start = 0; | |
1529 | chunk_start < nr_pages; | |
1530 | chunk_start += chunk_nr_pages) { | |
1531 | int j; | |
1532 | ||
1533 | if (chunk_start + chunk_nr_pages > nr_pages) | |
1534 | chunk_nr_pages = nr_pages - chunk_start; | |
1535 | ||
1536 | /* fill the chunk pm with addrs and nodes from user-space */ | |
1537 | for (j = 0; j < chunk_nr_pages; j++) { | |
1538 | const void __user *p; | |
1539 | int node; | |
1540 | ||
1541 | err = -EFAULT; | |
1542 | if (get_user(p, pages + j + chunk_start)) | |
1543 | goto out_pm; | |
1544 | pm[j].addr = (unsigned long) p; | |
1545 | ||
1546 | if (get_user(node, nodes + j + chunk_start)) | |
1547 | goto out_pm; | |
1548 | ||
1549 | err = -ENODEV; | |
1550 | if (node < 0 || node >= MAX_NUMNODES) | |
1551 | goto out_pm; | |
1552 | ||
1553 | if (!node_state(node, N_MEMORY)) | |
1554 | goto out_pm; | |
1555 | ||
1556 | err = -EACCES; | |
1557 | if (!node_isset(node, task_nodes)) | |
1558 | goto out_pm; | |
1559 | ||
1560 | pm[j].node = node; | |
1561 | } | |
1562 | ||
1563 | /* End marker for this chunk */ | |
1564 | pm[chunk_nr_pages].node = MAX_NUMNODES; | |
1565 | ||
1566 | /* Migrate this chunk */ | |
1567 | err = do_move_page_to_node_array(mm, pm, | |
1568 | flags & MPOL_MF_MOVE_ALL); | |
1569 | if (err < 0) | |
1570 | goto out_pm; | |
1571 | ||
1572 | /* Return status information */ | |
1573 | for (j = 0; j < chunk_nr_pages; j++) | |
1574 | if (put_user(pm[j].status, status + j + chunk_start)) { | |
1575 | err = -EFAULT; | |
1576 | goto out_pm; | |
1577 | } | |
1578 | } | |
1579 | err = 0; | |
1580 | ||
1581 | out_pm: | |
1582 | free_page((unsigned long)pm); | |
1583 | out: | |
1584 | return err; | |
1585 | } | |
1586 | ||
1587 | /* | |
1588 | * Determine the nodes of an array of pages and store it in an array of status. | |
1589 | */ | |
1590 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, | |
1591 | const void __user **pages, int *status) | |
1592 | { | |
1593 | unsigned long i; | |
1594 | ||
1595 | down_read(&mm->mmap_sem); | |
1596 | ||
1597 | for (i = 0; i < nr_pages; i++) { | |
1598 | unsigned long addr = (unsigned long)(*pages); | |
1599 | struct vm_area_struct *vma; | |
1600 | struct page *page; | |
1601 | int err = -EFAULT; | |
1602 | ||
1603 | vma = find_vma(mm, addr); | |
1604 | if (!vma || addr < vma->vm_start) | |
1605 | goto set_status; | |
1606 | ||
1607 | /* FOLL_DUMP to ignore special (like zero) pages */ | |
1608 | page = follow_page(vma, addr, FOLL_DUMP); | |
1609 | ||
1610 | err = PTR_ERR(page); | |
1611 | if (IS_ERR(page)) | |
1612 | goto set_status; | |
1613 | ||
1614 | err = page ? page_to_nid(page) : -ENOENT; | |
1615 | set_status: | |
1616 | *status = err; | |
1617 | ||
1618 | pages++; | |
1619 | status++; | |
1620 | } | |
1621 | ||
1622 | up_read(&mm->mmap_sem); | |
1623 | } | |
1624 | ||
1625 | /* | |
1626 | * Determine the nodes of a user array of pages and store it in | |
1627 | * a user array of status. | |
1628 | */ | |
1629 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, | |
1630 | const void __user * __user *pages, | |
1631 | int __user *status) | |
1632 | { | |
1633 | #define DO_PAGES_STAT_CHUNK_NR 16 | |
1634 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; | |
1635 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; | |
1636 | ||
1637 | while (nr_pages) { | |
1638 | unsigned long chunk_nr; | |
1639 | ||
1640 | chunk_nr = nr_pages; | |
1641 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) | |
1642 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; | |
1643 | ||
1644 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) | |
1645 | break; | |
1646 | ||
1647 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); | |
1648 | ||
1649 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) | |
1650 | break; | |
1651 | ||
1652 | pages += chunk_nr; | |
1653 | status += chunk_nr; | |
1654 | nr_pages -= chunk_nr; | |
1655 | } | |
1656 | return nr_pages ? -EFAULT : 0; | |
1657 | } | |
1658 | ||
1659 | /* | |
1660 | * Move a list of pages in the address space of the currently executing | |
1661 | * process. | |
1662 | */ | |
1663 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, | |
1664 | const void __user * __user *, pages, | |
1665 | const int __user *, nodes, | |
1666 | int __user *, status, int, flags) | |
1667 | { | |
1668 | const struct cred *cred = current_cred(), *tcred; | |
1669 | struct task_struct *task; | |
1670 | struct mm_struct *mm; | |
1671 | int err; | |
1672 | nodemask_t task_nodes; | |
1673 | ||
1674 | /* Check flags */ | |
1675 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
1676 | return -EINVAL; | |
1677 | ||
1678 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
1679 | return -EPERM; | |
1680 | ||
1681 | /* Find the mm_struct */ | |
1682 | rcu_read_lock(); | |
1683 | task = pid ? find_task_by_vpid(pid) : current; | |
1684 | if (!task) { | |
1685 | rcu_read_unlock(); | |
1686 | return -ESRCH; | |
1687 | } | |
1688 | get_task_struct(task); | |
1689 | ||
1690 | /* | |
1691 | * Check if this process has the right to modify the specified | |
1692 | * process. The right exists if the process has administrative | |
1693 | * capabilities, superuser privileges or the same | |
1694 | * userid as the target process. | |
1695 | */ | |
1696 | tcred = __task_cred(task); | |
1697 | if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) && | |
1698 | !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) && | |
1699 | !capable(CAP_SYS_NICE)) { | |
1700 | rcu_read_unlock(); | |
1701 | err = -EPERM; | |
1702 | goto out; | |
1703 | } | |
1704 | rcu_read_unlock(); | |
1705 | ||
1706 | err = security_task_movememory(task); | |
1707 | if (err) | |
1708 | goto out; | |
1709 | ||
1710 | task_nodes = cpuset_mems_allowed(task); | |
1711 | mm = get_task_mm(task); | |
1712 | put_task_struct(task); | |
1713 | ||
1714 | if (!mm) | |
1715 | return -EINVAL; | |
1716 | ||
1717 | if (nodes) | |
1718 | err = do_pages_move(mm, task_nodes, nr_pages, pages, | |
1719 | nodes, status, flags); | |
1720 | else | |
1721 | err = do_pages_stat(mm, nr_pages, pages, status); | |
1722 | ||
1723 | mmput(mm); | |
1724 | return err; | |
1725 | ||
1726 | out: | |
1727 | put_task_struct(task); | |
1728 | return err; | |
1729 | } | |
1730 | ||
1731 | #ifdef CONFIG_NUMA_BALANCING | |
1732 | /* | |
1733 | * Returns true if this is a safe migration target node for misplaced NUMA | |
1734 | * pages. Currently it only checks the watermarks which crude | |
1735 | */ | |
1736 | static bool migrate_balanced_pgdat(struct pglist_data *pgdat, | |
1737 | unsigned long nr_migrate_pages) | |
1738 | { | |
1739 | int z; | |
1740 | ||
1741 | if (!pgdat_reclaimable(pgdat)) | |
1742 | return false; | |
1743 | ||
1744 | for (z = pgdat->nr_zones - 1; z >= 0; z--) { | |
1745 | struct zone *zone = pgdat->node_zones + z; | |
1746 | ||
1747 | if (!populated_zone(zone)) | |
1748 | continue; | |
1749 | ||
1750 | /* Avoid waking kswapd by allocating pages_to_migrate pages. */ | |
1751 | if (!zone_watermark_ok(zone, 0, | |
1752 | high_wmark_pages(zone) + | |
1753 | nr_migrate_pages, | |
1754 | 0, 0)) | |
1755 | continue; | |
1756 | return true; | |
1757 | } | |
1758 | return false; | |
1759 | } | |
1760 | ||
1761 | static struct page *alloc_misplaced_dst_page(struct page *page, | |
1762 | unsigned long data, | |
1763 | int **result) | |
1764 | { | |
1765 | int nid = (int) data; | |
1766 | struct page *newpage; | |
1767 | ||
1768 | newpage = __alloc_pages_node(nid, | |
1769 | (GFP_HIGHUSER_MOVABLE | | |
1770 | __GFP_THISNODE | __GFP_NOMEMALLOC | | |
1771 | __GFP_NORETRY | __GFP_NOWARN) & | |
1772 | ~__GFP_RECLAIM, 0); | |
1773 | ||
1774 | return newpage; | |
1775 | } | |
1776 | ||
1777 | /* | |
1778 | * page migration rate limiting control. | |
1779 | * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs | |
1780 | * window of time. Default here says do not migrate more than 1280M per second. | |
1781 | */ | |
1782 | static unsigned int migrate_interval_millisecs __read_mostly = 100; | |
1783 | static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); | |
1784 | ||
1785 | /* Returns true if the node is migrate rate-limited after the update */ | |
1786 | static bool numamigrate_update_ratelimit(pg_data_t *pgdat, | |
1787 | unsigned long nr_pages) | |
1788 | { | |
1789 | /* | |
1790 | * Rate-limit the amount of data that is being migrated to a node. | |
1791 | * Optimal placement is no good if the memory bus is saturated and | |
1792 | * all the time is being spent migrating! | |
1793 | */ | |
1794 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { | |
1795 | spin_lock(&pgdat->numabalancing_migrate_lock); | |
1796 | pgdat->numabalancing_migrate_nr_pages = 0; | |
1797 | pgdat->numabalancing_migrate_next_window = jiffies + | |
1798 | msecs_to_jiffies(migrate_interval_millisecs); | |
1799 | spin_unlock(&pgdat->numabalancing_migrate_lock); | |
1800 | } | |
1801 | if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { | |
1802 | trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, | |
1803 | nr_pages); | |
1804 | return true; | |
1805 | } | |
1806 | ||
1807 | /* | |
1808 | * This is an unlocked non-atomic update so errors are possible. | |
1809 | * The consequences are failing to migrate when we potentiall should | |
1810 | * have which is not severe enough to warrant locking. If it is ever | |
1811 | * a problem, it can be converted to a per-cpu counter. | |
1812 | */ | |
1813 | pgdat->numabalancing_migrate_nr_pages += nr_pages; | |
1814 | return false; | |
1815 | } | |
1816 | ||
1817 | static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) | |
1818 | { | |
1819 | int page_lru; | |
1820 | ||
1821 | VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); | |
1822 | ||
1823 | /* Avoid migrating to a node that is nearly full */ | |
1824 | if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) | |
1825 | return 0; | |
1826 | ||
1827 | if (isolate_lru_page(page)) | |
1828 | return 0; | |
1829 | ||
1830 | /* | |
1831 | * migrate_misplaced_transhuge_page() skips page migration's usual | |
1832 | * check on page_count(), so we must do it here, now that the page | |
1833 | * has been isolated: a GUP pin, or any other pin, prevents migration. | |
1834 | * The expected page count is 3: 1 for page's mapcount and 1 for the | |
1835 | * caller's pin and 1 for the reference taken by isolate_lru_page(). | |
1836 | */ | |
1837 | if (PageTransHuge(page) && page_count(page) != 3) { | |
1838 | putback_lru_page(page); | |
1839 | return 0; | |
1840 | } | |
1841 | ||
1842 | page_lru = page_is_file_cache(page); | |
1843 | mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, | |
1844 | hpage_nr_pages(page)); | |
1845 | ||
1846 | /* | |
1847 | * Isolating the page has taken another reference, so the | |
1848 | * caller's reference can be safely dropped without the page | |
1849 | * disappearing underneath us during migration. | |
1850 | */ | |
1851 | put_page(page); | |
1852 | return 1; | |
1853 | } | |
1854 | ||
1855 | bool pmd_trans_migrating(pmd_t pmd) | |
1856 | { | |
1857 | struct page *page = pmd_page(pmd); | |
1858 | return PageLocked(page); | |
1859 | } | |
1860 | ||
1861 | /* | |
1862 | * Attempt to migrate a misplaced page to the specified destination | |
1863 | * node. Caller is expected to have an elevated reference count on | |
1864 | * the page that will be dropped by this function before returning. | |
1865 | */ | |
1866 | int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, | |
1867 | int node) | |
1868 | { | |
1869 | pg_data_t *pgdat = NODE_DATA(node); | |
1870 | int isolated; | |
1871 | int nr_remaining; | |
1872 | LIST_HEAD(migratepages); | |
1873 | ||
1874 | /* | |
1875 | * Don't migrate file pages that are mapped in multiple processes | |
1876 | * with execute permissions as they are probably shared libraries. | |
1877 | */ | |
1878 | if (page_mapcount(page) != 1 && page_is_file_cache(page) && | |
1879 | (vma->vm_flags & VM_EXEC)) | |
1880 | goto out; | |
1881 | ||
1882 | /* | |
1883 | * Rate-limit the amount of data that is being migrated to a node. | |
1884 | * Optimal placement is no good if the memory bus is saturated and | |
1885 | * all the time is being spent migrating! | |
1886 | */ | |
1887 | if (numamigrate_update_ratelimit(pgdat, 1)) | |
1888 | goto out; | |
1889 | ||
1890 | isolated = numamigrate_isolate_page(pgdat, page); | |
1891 | if (!isolated) | |
1892 | goto out; | |
1893 | ||
1894 | list_add(&page->lru, &migratepages); | |
1895 | nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page, | |
1896 | NULL, node, MIGRATE_ASYNC, | |
1897 | MR_NUMA_MISPLACED); | |
1898 | if (nr_remaining) { | |
1899 | if (!list_empty(&migratepages)) { | |
1900 | list_del(&page->lru); | |
1901 | dec_node_page_state(page, NR_ISOLATED_ANON + | |
1902 | page_is_file_cache(page)); | |
1903 | putback_lru_page(page); | |
1904 | } | |
1905 | isolated = 0; | |
1906 | } else | |
1907 | count_vm_numa_event(NUMA_PAGE_MIGRATE); | |
1908 | BUG_ON(!list_empty(&migratepages)); | |
1909 | return isolated; | |
1910 | ||
1911 | out: | |
1912 | put_page(page); | |
1913 | return 0; | |
1914 | } | |
1915 | #endif /* CONFIG_NUMA_BALANCING */ | |
1916 | ||
1917 | #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) | |
1918 | /* | |
1919 | * Migrates a THP to a given target node. page must be locked and is unlocked | |
1920 | * before returning. | |
1921 | */ | |
1922 | int migrate_misplaced_transhuge_page(struct mm_struct *mm, | |
1923 | struct vm_area_struct *vma, | |
1924 | pmd_t *pmd, pmd_t entry, | |
1925 | unsigned long address, | |
1926 | struct page *page, int node) | |
1927 | { | |
1928 | spinlock_t *ptl; | |
1929 | pg_data_t *pgdat = NODE_DATA(node); | |
1930 | int isolated = 0; | |
1931 | struct page *new_page = NULL; | |
1932 | int page_lru = page_is_file_cache(page); | |
1933 | unsigned long mmun_start = address & HPAGE_PMD_MASK; | |
1934 | unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; | |
1935 | pmd_t orig_entry; | |
1936 | ||
1937 | /* | |
1938 | * Rate-limit the amount of data that is being migrated to a node. | |
1939 | * Optimal placement is no good if the memory bus is saturated and | |
1940 | * all the time is being spent migrating! | |
1941 | */ | |
1942 | if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) | |
1943 | goto out_dropref; | |
1944 | ||
1945 | new_page = alloc_pages_node(node, | |
1946 | (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), | |
1947 | HPAGE_PMD_ORDER); | |
1948 | if (!new_page) | |
1949 | goto out_fail; | |
1950 | prep_transhuge_page(new_page); | |
1951 | ||
1952 | isolated = numamigrate_isolate_page(pgdat, page); | |
1953 | if (!isolated) { | |
1954 | put_page(new_page); | |
1955 | goto out_fail; | |
1956 | } | |
1957 | /* | |
1958 | * We are not sure a pending tlb flush here is for a huge page | |
1959 | * mapping or not. Hence use the tlb range variant | |
1960 | */ | |
1961 | if (mm_tlb_flush_pending(mm)) | |
1962 | flush_tlb_range(vma, mmun_start, mmun_end); | |
1963 | ||
1964 | /* Prepare a page as a migration target */ | |
1965 | __SetPageLocked(new_page); | |
1966 | __SetPageSwapBacked(new_page); | |
1967 | ||
1968 | /* anon mapping, we can simply copy page->mapping to the new page: */ | |
1969 | new_page->mapping = page->mapping; | |
1970 | new_page->index = page->index; | |
1971 | migrate_page_copy(new_page, page); | |
1972 | WARN_ON(PageLRU(new_page)); | |
1973 | ||
1974 | /* Recheck the target PMD */ | |
1975 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1976 | ptl = pmd_lock(mm, pmd); | |
1977 | if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) { | |
1978 | fail_putback: | |
1979 | spin_unlock(ptl); | |
1980 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1981 | ||
1982 | /* Reverse changes made by migrate_page_copy() */ | |
1983 | if (TestClearPageActive(new_page)) | |
1984 | SetPageActive(page); | |
1985 | if (TestClearPageUnevictable(new_page)) | |
1986 | SetPageUnevictable(page); | |
1987 | ||
1988 | unlock_page(new_page); | |
1989 | put_page(new_page); /* Free it */ | |
1990 | ||
1991 | /* Retake the callers reference and putback on LRU */ | |
1992 | get_page(page); | |
1993 | putback_lru_page(page); | |
1994 | mod_node_page_state(page_pgdat(page), | |
1995 | NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); | |
1996 | ||
1997 | goto out_unlock; | |
1998 | } | |
1999 | ||
2000 | orig_entry = *pmd; | |
2001 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); | |
2002 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
2003 | ||
2004 | /* | |
2005 | * Clear the old entry under pagetable lock and establish the new PTE. | |
2006 | * Any parallel GUP will either observe the old page blocking on the | |
2007 | * page lock, block on the page table lock or observe the new page. | |
2008 | * The SetPageUptodate on the new page and page_add_new_anon_rmap | |
2009 | * guarantee the copy is visible before the pagetable update. | |
2010 | */ | |
2011 | flush_cache_range(vma, mmun_start, mmun_end); | |
2012 | page_add_anon_rmap(new_page, vma, mmun_start, true); | |
2013 | pmdp_huge_clear_flush_notify(vma, mmun_start, pmd); | |
2014 | set_pmd_at(mm, mmun_start, pmd, entry); | |
2015 | update_mmu_cache_pmd(vma, address, &entry); | |
2016 | ||
2017 | if (page_count(page) != 2) { | |
2018 | set_pmd_at(mm, mmun_start, pmd, orig_entry); | |
2019 | flush_pmd_tlb_range(vma, mmun_start, mmun_end); | |
2020 | mmu_notifier_invalidate_range(mm, mmun_start, mmun_end); | |
2021 | update_mmu_cache_pmd(vma, address, &entry); | |
2022 | page_remove_rmap(new_page, true); | |
2023 | goto fail_putback; | |
2024 | } | |
2025 | ||
2026 | mlock_migrate_page(new_page, page); | |
2027 | page_remove_rmap(page, true); | |
2028 | set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED); | |
2029 | ||
2030 | spin_unlock(ptl); | |
2031 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
2032 | ||
2033 | /* Take an "isolate" reference and put new page on the LRU. */ | |
2034 | get_page(new_page); | |
2035 | putback_lru_page(new_page); | |
2036 | ||
2037 | unlock_page(new_page); | |
2038 | unlock_page(page); | |
2039 | put_page(page); /* Drop the rmap reference */ | |
2040 | put_page(page); /* Drop the LRU isolation reference */ | |
2041 | ||
2042 | count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); | |
2043 | count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); | |
2044 | ||
2045 | mod_node_page_state(page_pgdat(page), | |
2046 | NR_ISOLATED_ANON + page_lru, | |
2047 | -HPAGE_PMD_NR); | |
2048 | return isolated; | |
2049 | ||
2050 | out_fail: | |
2051 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); | |
2052 | out_dropref: | |
2053 | ptl = pmd_lock(mm, pmd); | |
2054 | if (pmd_same(*pmd, entry)) { | |
2055 | entry = pmd_modify(entry, vma->vm_page_prot); | |
2056 | set_pmd_at(mm, mmun_start, pmd, entry); | |
2057 | update_mmu_cache_pmd(vma, address, &entry); | |
2058 | } | |
2059 | spin_unlock(ptl); | |
2060 | ||
2061 | out_unlock: | |
2062 | unlock_page(page); | |
2063 | put_page(page); | |
2064 | return 0; | |
2065 | } | |
2066 | #endif /* CONFIG_NUMA_BALANCING */ | |
2067 | ||
2068 | #endif /* CONFIG_NUMA */ |