Commit | Line | Data |
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b20a3503 CL |
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 <clameter@sgi.com> | |
13 | */ | |
14 | ||
15 | #include <linux/migrate.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/swap.h> | |
0697212a | 18 | #include <linux/swapops.h> |
b20a3503 | 19 | #include <linux/pagemap.h> |
e23ca00b | 20 | #include <linux/buffer_head.h> |
b20a3503 CL |
21 | #include <linux/mm_inline.h> |
22 | #include <linux/pagevec.h> | |
23 | #include <linux/rmap.h> | |
24 | #include <linux/topology.h> | |
25 | #include <linux/cpu.h> | |
26 | #include <linux/cpuset.h> | |
b20a3503 CL |
27 | |
28 | #include "internal.h" | |
29 | ||
b20a3503 CL |
30 | /* The maximum number of pages to take off the LRU for migration */ |
31 | #define MIGRATE_CHUNK_SIZE 256 | |
32 | ||
33 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) | |
34 | ||
35 | /* | |
36 | * Isolate one page from the LRU lists. If successful put it onto | |
37 | * the indicated list with elevated page count. | |
38 | * | |
39 | * Result: | |
40 | * -EBUSY: page not on LRU list | |
41 | * 0: page removed from LRU list and added to the specified list. | |
42 | */ | |
43 | int isolate_lru_page(struct page *page, struct list_head *pagelist) | |
44 | { | |
45 | int ret = -EBUSY; | |
46 | ||
47 | if (PageLRU(page)) { | |
48 | struct zone *zone = page_zone(page); | |
49 | ||
50 | spin_lock_irq(&zone->lru_lock); | |
51 | if (PageLRU(page)) { | |
52 | ret = 0; | |
53 | get_page(page); | |
54 | ClearPageLRU(page); | |
55 | if (PageActive(page)) | |
56 | del_page_from_active_list(zone, page); | |
57 | else | |
58 | del_page_from_inactive_list(zone, page); | |
59 | list_add_tail(&page->lru, pagelist); | |
60 | } | |
61 | spin_unlock_irq(&zone->lru_lock); | |
62 | } | |
63 | return ret; | |
64 | } | |
65 | ||
66 | /* | |
67 | * migrate_prep() needs to be called after we have compiled the list of pages | |
68 | * to be migrated using isolate_lru_page() but before we begin a series of calls | |
69 | * to migrate_pages(). | |
70 | */ | |
71 | int migrate_prep(void) | |
72 | { | |
73 | /* Must have swap device for migration */ | |
74 | if (nr_swap_pages <= 0) | |
75 | return -ENODEV; | |
76 | ||
77 | /* | |
78 | * Clear the LRU lists so pages can be isolated. | |
79 | * Note that pages may be moved off the LRU after we have | |
80 | * drained them. Those pages will fail to migrate like other | |
81 | * pages that may be busy. | |
82 | */ | |
83 | lru_add_drain_all(); | |
84 | ||
85 | return 0; | |
86 | } | |
87 | ||
88 | static inline void move_to_lru(struct page *page) | |
89 | { | |
90 | list_del(&page->lru); | |
91 | if (PageActive(page)) { | |
92 | /* | |
93 | * lru_cache_add_active checks that | |
94 | * the PG_active bit is off. | |
95 | */ | |
96 | ClearPageActive(page); | |
97 | lru_cache_add_active(page); | |
98 | } else { | |
99 | lru_cache_add(page); | |
100 | } | |
101 | put_page(page); | |
102 | } | |
103 | ||
104 | /* | |
105 | * Add isolated pages on the list back to the LRU. | |
106 | * | |
107 | * returns the number of pages put back. | |
108 | */ | |
109 | int putback_lru_pages(struct list_head *l) | |
110 | { | |
111 | struct page *page; | |
112 | struct page *page2; | |
113 | int count = 0; | |
114 | ||
115 | list_for_each_entry_safe(page, page2, l, lru) { | |
116 | move_to_lru(page); | |
117 | count++; | |
118 | } | |
119 | return count; | |
120 | } | |
121 | ||
0697212a CL |
122 | static inline int is_swap_pte(pte_t pte) |
123 | { | |
124 | return !pte_none(pte) && !pte_present(pte) && !pte_file(pte); | |
125 | } | |
126 | ||
127 | /* | |
128 | * Restore a potential migration pte to a working pte entry | |
129 | */ | |
130 | static void remove_migration_pte(struct vm_area_struct *vma, unsigned long addr, | |
131 | struct page *old, struct page *new) | |
132 | { | |
133 | struct mm_struct *mm = vma->vm_mm; | |
134 | swp_entry_t entry; | |
135 | pgd_t *pgd; | |
136 | pud_t *pud; | |
137 | pmd_t *pmd; | |
138 | pte_t *ptep, pte; | |
139 | spinlock_t *ptl; | |
140 | ||
141 | pgd = pgd_offset(mm, addr); | |
142 | if (!pgd_present(*pgd)) | |
143 | return; | |
144 | ||
145 | pud = pud_offset(pgd, addr); | |
146 | if (!pud_present(*pud)) | |
147 | return; | |
148 | ||
149 | pmd = pmd_offset(pud, addr); | |
150 | if (!pmd_present(*pmd)) | |
151 | return; | |
152 | ||
153 | ptep = pte_offset_map(pmd, addr); | |
154 | ||
155 | if (!is_swap_pte(*ptep)) { | |
156 | pte_unmap(ptep); | |
157 | return; | |
158 | } | |
159 | ||
160 | ptl = pte_lockptr(mm, pmd); | |
161 | spin_lock(ptl); | |
162 | pte = *ptep; | |
163 | if (!is_swap_pte(pte)) | |
164 | goto out; | |
165 | ||
166 | entry = pte_to_swp_entry(pte); | |
167 | ||
168 | if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) | |
169 | goto out; | |
170 | ||
171 | inc_mm_counter(mm, anon_rss); | |
172 | get_page(new); | |
173 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
174 | if (is_write_migration_entry(entry)) | |
175 | pte = pte_mkwrite(pte); | |
176 | set_pte_at(mm, addr, ptep, pte); | |
177 | page_add_anon_rmap(new, vma, addr); | |
178 | out: | |
179 | pte_unmap_unlock(ptep, ptl); | |
180 | } | |
181 | ||
182 | /* | |
183 | * Get rid of all migration entries and replace them by | |
184 | * references to the indicated page. | |
185 | * | |
186 | * Must hold mmap_sem lock on at least one of the vmas containing | |
187 | * the page so that the anon_vma cannot vanish. | |
188 | */ | |
189 | static void remove_migration_ptes(struct page *old, struct page *new) | |
190 | { | |
191 | struct anon_vma *anon_vma; | |
192 | struct vm_area_struct *vma; | |
193 | unsigned long mapping; | |
194 | ||
195 | mapping = (unsigned long)new->mapping; | |
196 | ||
197 | if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) | |
198 | return; | |
199 | ||
200 | /* | |
201 | * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. | |
202 | */ | |
203 | anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); | |
204 | spin_lock(&anon_vma->lock); | |
205 | ||
206 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) | |
207 | remove_migration_pte(vma, page_address_in_vma(new, vma), | |
208 | old, new); | |
209 | ||
210 | spin_unlock(&anon_vma->lock); | |
211 | } | |
212 | ||
213 | /* | |
214 | * Something used the pte of a page under migration. We need to | |
215 | * get to the page and wait until migration is finished. | |
216 | * When we return from this function the fault will be retried. | |
217 | * | |
218 | * This function is called from do_swap_page(). | |
219 | */ | |
220 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
221 | unsigned long address) | |
222 | { | |
223 | pte_t *ptep, pte; | |
224 | spinlock_t *ptl; | |
225 | swp_entry_t entry; | |
226 | struct page *page; | |
227 | ||
228 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
229 | pte = *ptep; | |
230 | if (!is_swap_pte(pte)) | |
231 | goto out; | |
232 | ||
233 | entry = pte_to_swp_entry(pte); | |
234 | if (!is_migration_entry(entry)) | |
235 | goto out; | |
236 | ||
237 | page = migration_entry_to_page(entry); | |
238 | ||
239 | get_page(page); | |
240 | pte_unmap_unlock(ptep, ptl); | |
241 | wait_on_page_locked(page); | |
242 | put_page(page); | |
243 | return; | |
244 | out: | |
245 | pte_unmap_unlock(ptep, ptl); | |
246 | } | |
247 | ||
b20a3503 CL |
248 | /* |
249 | * swapout a single page | |
250 | * page is locked upon entry, unlocked on exit | |
251 | */ | |
252 | static int swap_page(struct page *page) | |
253 | { | |
254 | struct address_space *mapping = page_mapping(page); | |
255 | ||
256 | if (page_mapped(page) && mapping) | |
257 | if (try_to_unmap(page, 1) != SWAP_SUCCESS) | |
258 | goto unlock_retry; | |
259 | ||
260 | if (PageDirty(page)) { | |
261 | /* Page is dirty, try to write it out here */ | |
262 | switch(pageout(page, mapping)) { | |
263 | case PAGE_KEEP: | |
264 | case PAGE_ACTIVATE: | |
265 | goto unlock_retry; | |
266 | ||
267 | case PAGE_SUCCESS: | |
268 | goto retry; | |
269 | ||
270 | case PAGE_CLEAN: | |
271 | ; /* try to free the page below */ | |
272 | } | |
273 | } | |
274 | ||
275 | if (PagePrivate(page)) { | |
276 | if (!try_to_release_page(page, GFP_KERNEL) || | |
277 | (!mapping && page_count(page) == 1)) | |
278 | goto unlock_retry; | |
279 | } | |
280 | ||
281 | if (remove_mapping(mapping, page)) { | |
282 | /* Success */ | |
283 | unlock_page(page); | |
284 | return 0; | |
285 | } | |
286 | ||
287 | unlock_retry: | |
288 | unlock_page(page); | |
289 | ||
290 | retry: | |
291 | return -EAGAIN; | |
292 | } | |
b20a3503 CL |
293 | |
294 | /* | |
c3fcf8a5 | 295 | * Replace the page in the mapping. |
5b5c7120 CL |
296 | * |
297 | * The number of remaining references must be: | |
298 | * 1 for anonymous pages without a mapping | |
299 | * 2 for pages with a mapping | |
300 | * 3 for pages with a mapping and PagePrivate set. | |
b20a3503 | 301 | */ |
2d1db3b1 CL |
302 | static int migrate_page_move_mapping(struct address_space *mapping, |
303 | struct page *newpage, struct page *page) | |
b20a3503 | 304 | { |
b20a3503 CL |
305 | struct page **radix_pointer; |
306 | ||
b20a3503 CL |
307 | write_lock_irq(&mapping->tree_lock); |
308 | ||
309 | radix_pointer = (struct page **)radix_tree_lookup_slot( | |
310 | &mapping->page_tree, | |
311 | page_index(page)); | |
312 | ||
5b5c7120 CL |
313 | if (!page_mapping(page) || |
314 | page_count(page) != 2 + !!PagePrivate(page) || | |
b20a3503 CL |
315 | *radix_pointer != page) { |
316 | write_unlock_irq(&mapping->tree_lock); | |
e23ca00b | 317 | return -EAGAIN; |
b20a3503 CL |
318 | } |
319 | ||
320 | /* | |
321 | * Now we know that no one else is looking at the page. | |
b20a3503 CL |
322 | */ |
323 | get_page(newpage); | |
b20a3503 CL |
324 | if (PageSwapCache(page)) { |
325 | SetPageSwapCache(newpage); | |
326 | set_page_private(newpage, page_private(page)); | |
327 | } | |
328 | ||
329 | *radix_pointer = newpage; | |
330 | __put_page(page); | |
331 | write_unlock_irq(&mapping->tree_lock); | |
332 | ||
333 | return 0; | |
334 | } | |
b20a3503 CL |
335 | |
336 | /* | |
337 | * Copy the page to its new location | |
338 | */ | |
e7340f73 | 339 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 CL |
340 | { |
341 | copy_highpage(newpage, page); | |
342 | ||
343 | if (PageError(page)) | |
344 | SetPageError(newpage); | |
345 | if (PageReferenced(page)) | |
346 | SetPageReferenced(newpage); | |
347 | if (PageUptodate(page)) | |
348 | SetPageUptodate(newpage); | |
349 | if (PageActive(page)) | |
350 | SetPageActive(newpage); | |
351 | if (PageChecked(page)) | |
352 | SetPageChecked(newpage); | |
353 | if (PageMappedToDisk(page)) | |
354 | SetPageMappedToDisk(newpage); | |
355 | ||
356 | if (PageDirty(page)) { | |
357 | clear_page_dirty_for_io(page); | |
358 | set_page_dirty(newpage); | |
359 | } | |
360 | ||
361 | ClearPageSwapCache(page); | |
362 | ClearPageActive(page); | |
363 | ClearPagePrivate(page); | |
364 | set_page_private(page, 0); | |
365 | page->mapping = NULL; | |
366 | ||
367 | /* | |
368 | * If any waiters have accumulated on the new page then | |
369 | * wake them up. | |
370 | */ | |
371 | if (PageWriteback(newpage)) | |
372 | end_page_writeback(newpage); | |
373 | } | |
b20a3503 | 374 | |
1d8b85cc CL |
375 | /************************************************************ |
376 | * Migration functions | |
377 | ***********************************************************/ | |
378 | ||
379 | /* Always fail migration. Used for mappings that are not movable */ | |
2d1db3b1 CL |
380 | int fail_migrate_page(struct address_space *mapping, |
381 | struct page *newpage, struct page *page) | |
1d8b85cc CL |
382 | { |
383 | return -EIO; | |
384 | } | |
385 | EXPORT_SYMBOL(fail_migrate_page); | |
386 | ||
b20a3503 CL |
387 | /* |
388 | * Common logic to directly migrate a single page suitable for | |
389 | * pages that do not use PagePrivate. | |
390 | * | |
391 | * Pages are locked upon entry and exit. | |
392 | */ | |
2d1db3b1 CL |
393 | int migrate_page(struct address_space *mapping, |
394 | struct page *newpage, struct page *page) | |
b20a3503 CL |
395 | { |
396 | int rc; | |
397 | ||
398 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
399 | ||
2d1db3b1 | 400 | rc = migrate_page_move_mapping(mapping, newpage, page); |
b20a3503 CL |
401 | |
402 | if (rc) | |
403 | return rc; | |
404 | ||
405 | migrate_page_copy(newpage, page); | |
406 | ||
407 | /* | |
408 | * Remove auxiliary swap entries and replace | |
409 | * them with real ptes. | |
410 | * | |
411 | * Note that a real pte entry will allow processes that are not | |
412 | * waiting on the page lock to use the new page via the page tables | |
413 | * before the new page is unlocked. | |
414 | */ | |
415 | remove_from_swap(newpage); | |
416 | return 0; | |
417 | } | |
418 | EXPORT_SYMBOL(migrate_page); | |
419 | ||
1d8b85cc CL |
420 | /* |
421 | * Migration function for pages with buffers. This function can only be used | |
422 | * if the underlying filesystem guarantees that no other references to "page" | |
423 | * exist. | |
424 | */ | |
2d1db3b1 CL |
425 | int buffer_migrate_page(struct address_space *mapping, |
426 | struct page *newpage, struct page *page) | |
1d8b85cc | 427 | { |
1d8b85cc CL |
428 | struct buffer_head *bh, *head; |
429 | int rc; | |
430 | ||
1d8b85cc | 431 | if (!page_has_buffers(page)) |
2d1db3b1 | 432 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
433 | |
434 | head = page_buffers(page); | |
435 | ||
2d1db3b1 | 436 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
437 | |
438 | if (rc) | |
439 | return rc; | |
440 | ||
441 | bh = head; | |
442 | do { | |
443 | get_bh(bh); | |
444 | lock_buffer(bh); | |
445 | bh = bh->b_this_page; | |
446 | ||
447 | } while (bh != head); | |
448 | ||
449 | ClearPagePrivate(page); | |
450 | set_page_private(newpage, page_private(page)); | |
451 | set_page_private(page, 0); | |
452 | put_page(page); | |
453 | get_page(newpage); | |
454 | ||
455 | bh = head; | |
456 | do { | |
457 | set_bh_page(bh, newpage, bh_offset(bh)); | |
458 | bh = bh->b_this_page; | |
459 | ||
460 | } while (bh != head); | |
461 | ||
462 | SetPagePrivate(newpage); | |
463 | ||
464 | migrate_page_copy(newpage, page); | |
465 | ||
466 | bh = head; | |
467 | do { | |
468 | unlock_buffer(bh); | |
469 | put_bh(bh); | |
470 | bh = bh->b_this_page; | |
471 | ||
472 | } while (bh != head); | |
473 | ||
474 | return 0; | |
475 | } | |
476 | EXPORT_SYMBOL(buffer_migrate_page); | |
477 | ||
8351a6e4 CL |
478 | static int fallback_migrate_page(struct address_space *mapping, |
479 | struct page *newpage, struct page *page) | |
480 | { | |
481 | /* | |
482 | * Default handling if a filesystem does not provide | |
483 | * a migration function. We can only migrate clean | |
484 | * pages so try to write out any dirty pages first. | |
485 | */ | |
486 | if (PageDirty(page)) { | |
487 | switch (pageout(page, mapping)) { | |
488 | case PAGE_KEEP: | |
489 | case PAGE_ACTIVATE: | |
490 | return -EAGAIN; | |
491 | ||
492 | case PAGE_SUCCESS: | |
493 | /* Relock since we lost the lock */ | |
494 | lock_page(page); | |
495 | /* Must retry since page state may have changed */ | |
496 | return -EAGAIN; | |
497 | ||
498 | case PAGE_CLEAN: | |
499 | ; /* try to migrate the page below */ | |
500 | } | |
501 | } | |
502 | ||
503 | /* | |
504 | * Buffers may be managed in a filesystem specific way. | |
505 | * We must have no buffers or drop them. | |
506 | */ | |
507 | if (page_has_buffers(page) && | |
508 | !try_to_release_page(page, GFP_KERNEL)) | |
509 | return -EAGAIN; | |
510 | ||
511 | return migrate_page(mapping, newpage, page); | |
512 | } | |
513 | ||
b20a3503 CL |
514 | /* |
515 | * migrate_pages | |
516 | * | |
517 | * Two lists are passed to this function. The first list | |
518 | * contains the pages isolated from the LRU to be migrated. | |
519 | * The second list contains new pages that the pages isolated | |
520 | * can be moved to. If the second list is NULL then all | |
521 | * pages are swapped out. | |
522 | * | |
523 | * The function returns after 10 attempts or if no pages | |
524 | * are movable anymore because to has become empty | |
525 | * or no retryable pages exist anymore. | |
526 | * | |
527 | * Return: Number of pages not migrated when "to" ran empty. | |
528 | */ | |
529 | int migrate_pages(struct list_head *from, struct list_head *to, | |
530 | struct list_head *moved, struct list_head *failed) | |
531 | { | |
532 | int retry; | |
533 | int nr_failed = 0; | |
534 | int pass = 0; | |
535 | struct page *page; | |
536 | struct page *page2; | |
537 | int swapwrite = current->flags & PF_SWAPWRITE; | |
538 | int rc; | |
539 | ||
540 | if (!swapwrite) | |
541 | current->flags |= PF_SWAPWRITE; | |
542 | ||
543 | redo: | |
544 | retry = 0; | |
545 | ||
546 | list_for_each_entry_safe(page, page2, from, lru) { | |
547 | struct page *newpage = NULL; | |
548 | struct address_space *mapping; | |
549 | ||
550 | cond_resched(); | |
551 | ||
552 | rc = 0; | |
553 | if (page_count(page) == 1) | |
554 | /* page was freed from under us. So we are done. */ | |
555 | goto next; | |
556 | ||
557 | if (to && list_empty(to)) | |
558 | break; | |
559 | ||
560 | /* | |
561 | * Skip locked pages during the first two passes to give the | |
562 | * functions holding the lock time to release the page. Later we | |
563 | * use lock_page() to have a higher chance of acquiring the | |
564 | * lock. | |
565 | */ | |
566 | rc = -EAGAIN; | |
567 | if (pass > 2) | |
568 | lock_page(page); | |
569 | else | |
570 | if (TestSetPageLocked(page)) | |
571 | goto next; | |
572 | ||
573 | /* | |
574 | * Only wait on writeback if we have already done a pass where | |
575 | * we we may have triggered writeouts for lots of pages. | |
576 | */ | |
577 | if (pass > 0) { | |
578 | wait_on_page_writeback(page); | |
579 | } else { | |
580 | if (PageWriteback(page)) | |
581 | goto unlock_page; | |
582 | } | |
583 | ||
584 | /* | |
585 | * Anonymous pages must have swap cache references otherwise | |
586 | * the information contained in the page maps cannot be | |
587 | * preserved. | |
588 | */ | |
589 | if (PageAnon(page) && !PageSwapCache(page)) { | |
590 | if (!add_to_swap(page, GFP_KERNEL)) { | |
591 | rc = -ENOMEM; | |
592 | goto unlock_page; | |
593 | } | |
594 | } | |
595 | ||
596 | if (!to) { | |
597 | rc = swap_page(page); | |
598 | goto next; | |
599 | } | |
600 | ||
c3fcf8a5 CL |
601 | /* |
602 | * Establish swap ptes for anonymous pages or destroy pte | |
603 | * maps for files. | |
604 | * | |
605 | * In order to reestablish file backed mappings the fault handlers | |
606 | * will take the radix tree_lock which may then be used to stop | |
607 | * processses from accessing this page until the new page is ready. | |
608 | * | |
609 | * A process accessing via a swap pte (an anonymous page) will take a | |
610 | * page_lock on the old page which will block the process until the | |
611 | * migration attempt is complete. At that time the PageSwapCache bit | |
612 | * will be examined. If the page was migrated then the PageSwapCache | |
613 | * bit will be clear and the operation to retrieve the page will be | |
614 | * retried which will find the new page in the radix tree. Then a new | |
615 | * direct mapping may be generated based on the radix tree contents. | |
616 | * | |
617 | * If the page was not migrated then the PageSwapCache bit | |
618 | * is still set and the operation may continue. | |
619 | */ | |
620 | rc = -EPERM; | |
621 | if (try_to_unmap(page, 1) == SWAP_FAIL) | |
622 | /* A vma has VM_LOCKED set -> permanent failure */ | |
2d1db3b1 | 623 | goto unlock_page; |
c3fcf8a5 CL |
624 | |
625 | rc = -EAGAIN; | |
626 | if (page_mapped(page)) | |
2d1db3b1 CL |
627 | goto unlock_page; |
628 | ||
629 | newpage = lru_to_page(to); | |
630 | lock_page(newpage); | |
631 | /* Prepare mapping for the new page.*/ | |
632 | newpage->index = page->index; | |
633 | newpage->mapping = page->mapping; | |
634 | ||
b20a3503 CL |
635 | /* |
636 | * Pages are properly locked and writeback is complete. | |
637 | * Try to migrate the page. | |
638 | */ | |
639 | mapping = page_mapping(page); | |
640 | if (!mapping) | |
641 | goto unlock_both; | |
642 | ||
8351a6e4 | 643 | if (mapping->a_ops->migratepage) |
b20a3503 CL |
644 | /* |
645 | * Most pages have a mapping and most filesystems | |
646 | * should provide a migration function. Anonymous | |
647 | * pages are part of swap space which also has its | |
648 | * own migration function. This is the most common | |
649 | * path for page migration. | |
650 | */ | |
2d1db3b1 CL |
651 | rc = mapping->a_ops->migratepage(mapping, |
652 | newpage, page); | |
8351a6e4 CL |
653 | else |
654 | rc = fallback_migrate_page(mapping, newpage, page); | |
b20a3503 CL |
655 | |
656 | unlock_both: | |
657 | unlock_page(newpage); | |
658 | ||
659 | unlock_page: | |
660 | unlock_page(page); | |
661 | ||
662 | next: | |
2d1db3b1 CL |
663 | if (rc) { |
664 | if (newpage) | |
665 | newpage->mapping = NULL; | |
666 | ||
667 | if (rc == -EAGAIN) | |
668 | retry++; | |
669 | else { | |
670 | /* Permanent failure */ | |
671 | list_move(&page->lru, failed); | |
672 | nr_failed++; | |
673 | } | |
b20a3503 CL |
674 | } else { |
675 | if (newpage) { | |
676 | /* Successful migration. Return page to LRU */ | |
677 | move_to_lru(newpage); | |
678 | } | |
679 | list_move(&page->lru, moved); | |
680 | } | |
681 | } | |
682 | if (retry && pass++ < 10) | |
683 | goto redo; | |
684 | ||
685 | if (!swapwrite) | |
686 | current->flags &= ~PF_SWAPWRITE; | |
687 | ||
688 | return nr_failed + retry; | |
689 | } | |
690 | ||
b20a3503 CL |
691 | /* |
692 | * Migrate the list 'pagelist' of pages to a certain destination. | |
693 | * | |
694 | * Specify destination with either non-NULL vma or dest_node >= 0 | |
695 | * Return the number of pages not migrated or error code | |
696 | */ | |
697 | int migrate_pages_to(struct list_head *pagelist, | |
698 | struct vm_area_struct *vma, int dest) | |
699 | { | |
700 | LIST_HEAD(newlist); | |
701 | LIST_HEAD(moved); | |
702 | LIST_HEAD(failed); | |
703 | int err = 0; | |
704 | unsigned long offset = 0; | |
705 | int nr_pages; | |
706 | struct page *page; | |
707 | struct list_head *p; | |
708 | ||
709 | redo: | |
710 | nr_pages = 0; | |
711 | list_for_each(p, pagelist) { | |
712 | if (vma) { | |
713 | /* | |
714 | * The address passed to alloc_page_vma is used to | |
715 | * generate the proper interleave behavior. We fake | |
716 | * the address here by an increasing offset in order | |
717 | * to get the proper distribution of pages. | |
718 | * | |
719 | * No decision has been made as to which page | |
720 | * a certain old page is moved to so we cannot | |
721 | * specify the correct address. | |
722 | */ | |
723 | page = alloc_page_vma(GFP_HIGHUSER, vma, | |
724 | offset + vma->vm_start); | |
725 | offset += PAGE_SIZE; | |
726 | } | |
727 | else | |
728 | page = alloc_pages_node(dest, GFP_HIGHUSER, 0); | |
729 | ||
730 | if (!page) { | |
731 | err = -ENOMEM; | |
732 | goto out; | |
733 | } | |
734 | list_add_tail(&page->lru, &newlist); | |
735 | nr_pages++; | |
736 | if (nr_pages > MIGRATE_CHUNK_SIZE) | |
737 | break; | |
738 | } | |
739 | err = migrate_pages(pagelist, &newlist, &moved, &failed); | |
740 | ||
741 | putback_lru_pages(&moved); /* Call release pages instead ?? */ | |
742 | ||
743 | if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist)) | |
744 | goto redo; | |
745 | out: | |
746 | /* Return leftover allocated pages */ | |
747 | while (!list_empty(&newlist)) { | |
748 | page = list_entry(newlist.next, struct page, lru); | |
749 | list_del(&page->lru); | |
750 | __free_page(page); | |
751 | } | |
752 | list_splice(&failed, pagelist); | |
753 | if (err < 0) | |
754 | return err; | |
755 | ||
756 | /* Calculate number of leftover pages */ | |
757 | nr_pages = 0; | |
758 | list_for_each(p, pagelist) | |
759 | nr_pages++; | |
760 | return nr_pages; | |
761 | } |