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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> | |
04e62a29 | 27 | #include <linux/writeback.h> |
b20a3503 CL |
28 | |
29 | #include "internal.h" | |
30 | ||
b20a3503 CL |
31 | /* The maximum number of pages to take off the LRU for migration */ |
32 | #define MIGRATE_CHUNK_SIZE 256 | |
33 | ||
34 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) | |
35 | ||
36 | /* | |
37 | * Isolate one page from the LRU lists. If successful put it onto | |
38 | * the indicated list with elevated page count. | |
39 | * | |
40 | * Result: | |
41 | * -EBUSY: page not on LRU list | |
42 | * 0: page removed from LRU list and added to the specified list. | |
43 | */ | |
44 | int isolate_lru_page(struct page *page, struct list_head *pagelist) | |
45 | { | |
46 | int ret = -EBUSY; | |
47 | ||
48 | if (PageLRU(page)) { | |
49 | struct zone *zone = page_zone(page); | |
50 | ||
51 | spin_lock_irq(&zone->lru_lock); | |
52 | if (PageLRU(page)) { | |
53 | ret = 0; | |
54 | get_page(page); | |
55 | ClearPageLRU(page); | |
56 | if (PageActive(page)) | |
57 | del_page_from_active_list(zone, page); | |
58 | else | |
59 | del_page_from_inactive_list(zone, page); | |
60 | list_add_tail(&page->lru, pagelist); | |
61 | } | |
62 | spin_unlock_irq(&zone->lru_lock); | |
63 | } | |
64 | return ret; | |
65 | } | |
66 | ||
67 | /* | |
68 | * migrate_prep() needs to be called after we have compiled the list of pages | |
69 | * to be migrated using isolate_lru_page() but before we begin a series of calls | |
70 | * to migrate_pages(). | |
71 | */ | |
72 | int migrate_prep(void) | |
73 | { | |
b20a3503 CL |
74 | /* |
75 | * Clear the LRU lists so pages can be isolated. | |
76 | * Note that pages may be moved off the LRU after we have | |
77 | * drained them. Those pages will fail to migrate like other | |
78 | * pages that may be busy. | |
79 | */ | |
80 | lru_add_drain_all(); | |
81 | ||
82 | return 0; | |
83 | } | |
84 | ||
85 | static inline void move_to_lru(struct page *page) | |
86 | { | |
b20a3503 CL |
87 | if (PageActive(page)) { |
88 | /* | |
89 | * lru_cache_add_active checks that | |
90 | * the PG_active bit is off. | |
91 | */ | |
92 | ClearPageActive(page); | |
93 | lru_cache_add_active(page); | |
94 | } else { | |
95 | lru_cache_add(page); | |
96 | } | |
97 | put_page(page); | |
98 | } | |
99 | ||
100 | /* | |
101 | * Add isolated pages on the list back to the LRU. | |
102 | * | |
103 | * returns the number of pages put back. | |
104 | */ | |
105 | int putback_lru_pages(struct list_head *l) | |
106 | { | |
107 | struct page *page; | |
108 | struct page *page2; | |
109 | int count = 0; | |
110 | ||
111 | list_for_each_entry_safe(page, page2, l, lru) { | |
e24f0b8f | 112 | list_del(&page->lru); |
b20a3503 CL |
113 | move_to_lru(page); |
114 | count++; | |
115 | } | |
116 | return count; | |
117 | } | |
118 | ||
0697212a CL |
119 | static inline int is_swap_pte(pte_t pte) |
120 | { | |
121 | return !pte_none(pte) && !pte_present(pte) && !pte_file(pte); | |
122 | } | |
123 | ||
124 | /* | |
125 | * Restore a potential migration pte to a working pte entry | |
126 | */ | |
04e62a29 | 127 | static void remove_migration_pte(struct vm_area_struct *vma, |
0697212a CL |
128 | struct page *old, struct page *new) |
129 | { | |
130 | struct mm_struct *mm = vma->vm_mm; | |
131 | swp_entry_t entry; | |
132 | pgd_t *pgd; | |
133 | pud_t *pud; | |
134 | pmd_t *pmd; | |
135 | pte_t *ptep, pte; | |
136 | spinlock_t *ptl; | |
04e62a29 CL |
137 | unsigned long addr = page_address_in_vma(new, vma); |
138 | ||
139 | if (addr == -EFAULT) | |
140 | return; | |
0697212a CL |
141 | |
142 | pgd = pgd_offset(mm, addr); | |
143 | if (!pgd_present(*pgd)) | |
144 | return; | |
145 | ||
146 | pud = pud_offset(pgd, addr); | |
147 | if (!pud_present(*pud)) | |
148 | return; | |
149 | ||
150 | pmd = pmd_offset(pud, addr); | |
151 | if (!pmd_present(*pmd)) | |
152 | return; | |
153 | ||
154 | ptep = pte_offset_map(pmd, addr); | |
155 | ||
156 | if (!is_swap_pte(*ptep)) { | |
157 | pte_unmap(ptep); | |
158 | return; | |
159 | } | |
160 | ||
161 | ptl = pte_lockptr(mm, pmd); | |
162 | spin_lock(ptl); | |
163 | pte = *ptep; | |
164 | if (!is_swap_pte(pte)) | |
165 | goto out; | |
166 | ||
167 | entry = pte_to_swp_entry(pte); | |
168 | ||
169 | if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) | |
170 | goto out; | |
171 | ||
0697212a CL |
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); | |
04e62a29 CL |
177 | |
178 | if (PageAnon(new)) | |
179 | page_add_anon_rmap(new, vma, addr); | |
180 | else | |
181 | page_add_file_rmap(new); | |
182 | ||
183 | /* No need to invalidate - it was non-present before */ | |
184 | update_mmu_cache(vma, addr, pte); | |
185 | lazy_mmu_prot_update(pte); | |
186 | ||
0697212a CL |
187 | out: |
188 | pte_unmap_unlock(ptep, ptl); | |
189 | } | |
190 | ||
191 | /* | |
04e62a29 CL |
192 | * Note that remove_file_migration_ptes will only work on regular mappings, |
193 | * Nonlinear mappings do not use migration entries. | |
194 | */ | |
195 | static void remove_file_migration_ptes(struct page *old, struct page *new) | |
196 | { | |
197 | struct vm_area_struct *vma; | |
198 | struct address_space *mapping = page_mapping(new); | |
199 | struct prio_tree_iter iter; | |
200 | pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
201 | ||
202 | if (!mapping) | |
203 | return; | |
204 | ||
205 | spin_lock(&mapping->i_mmap_lock); | |
206 | ||
207 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) | |
208 | remove_migration_pte(vma, old, new); | |
209 | ||
210 | spin_unlock(&mapping->i_mmap_lock); | |
211 | } | |
212 | ||
213 | /* | |
0697212a CL |
214 | * Must hold mmap_sem lock on at least one of the vmas containing |
215 | * the page so that the anon_vma cannot vanish. | |
216 | */ | |
04e62a29 | 217 | static void remove_anon_migration_ptes(struct page *old, struct page *new) |
0697212a CL |
218 | { |
219 | struct anon_vma *anon_vma; | |
220 | struct vm_area_struct *vma; | |
221 | unsigned long mapping; | |
222 | ||
223 | mapping = (unsigned long)new->mapping; | |
224 | ||
225 | if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) | |
226 | return; | |
227 | ||
228 | /* | |
229 | * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. | |
230 | */ | |
231 | anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); | |
232 | spin_lock(&anon_vma->lock); | |
233 | ||
234 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) | |
04e62a29 | 235 | remove_migration_pte(vma, old, new); |
0697212a CL |
236 | |
237 | spin_unlock(&anon_vma->lock); | |
238 | } | |
239 | ||
04e62a29 CL |
240 | /* |
241 | * Get rid of all migration entries and replace them by | |
242 | * references to the indicated page. | |
243 | */ | |
244 | static void remove_migration_ptes(struct page *old, struct page *new) | |
245 | { | |
246 | if (PageAnon(new)) | |
247 | remove_anon_migration_ptes(old, new); | |
248 | else | |
249 | remove_file_migration_ptes(old, new); | |
250 | } | |
251 | ||
0697212a CL |
252 | /* |
253 | * Something used the pte of a page under migration. We need to | |
254 | * get to the page and wait until migration is finished. | |
255 | * When we return from this function the fault will be retried. | |
256 | * | |
257 | * This function is called from do_swap_page(). | |
258 | */ | |
259 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
260 | unsigned long address) | |
261 | { | |
262 | pte_t *ptep, pte; | |
263 | spinlock_t *ptl; | |
264 | swp_entry_t entry; | |
265 | struct page *page; | |
266 | ||
267 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
268 | pte = *ptep; | |
269 | if (!is_swap_pte(pte)) | |
270 | goto out; | |
271 | ||
272 | entry = pte_to_swp_entry(pte); | |
273 | if (!is_migration_entry(entry)) | |
274 | goto out; | |
275 | ||
276 | page = migration_entry_to_page(entry); | |
277 | ||
278 | get_page(page); | |
279 | pte_unmap_unlock(ptep, ptl); | |
280 | wait_on_page_locked(page); | |
281 | put_page(page); | |
282 | return; | |
283 | out: | |
284 | pte_unmap_unlock(ptep, ptl); | |
285 | } | |
286 | ||
b20a3503 | 287 | /* |
c3fcf8a5 | 288 | * Replace the page in the mapping. |
5b5c7120 CL |
289 | * |
290 | * The number of remaining references must be: | |
291 | * 1 for anonymous pages without a mapping | |
292 | * 2 for pages with a mapping | |
293 | * 3 for pages with a mapping and PagePrivate set. | |
b20a3503 | 294 | */ |
2d1db3b1 CL |
295 | static int migrate_page_move_mapping(struct address_space *mapping, |
296 | struct page *newpage, struct page *page) | |
b20a3503 | 297 | { |
b20a3503 CL |
298 | struct page **radix_pointer; |
299 | ||
6c5240ae CL |
300 | if (!mapping) { |
301 | /* Anonymous page */ | |
302 | if (page_count(page) != 1) | |
303 | return -EAGAIN; | |
304 | return 0; | |
305 | } | |
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 | ||
6c5240ae | 313 | if (page_count(page) != 2 + !!PagePrivate(page) || |
b20a3503 CL |
314 | *radix_pointer != page) { |
315 | write_unlock_irq(&mapping->tree_lock); | |
e23ca00b | 316 | return -EAGAIN; |
b20a3503 CL |
317 | } |
318 | ||
319 | /* | |
320 | * Now we know that no one else is looking at the page. | |
b20a3503 CL |
321 | */ |
322 | get_page(newpage); | |
6c5240ae | 323 | #ifdef CONFIG_SWAP |
b20a3503 CL |
324 | if (PageSwapCache(page)) { |
325 | SetPageSwapCache(newpage); | |
326 | set_page_private(newpage, page_private(page)); | |
327 | } | |
6c5240ae | 328 | #endif |
b20a3503 CL |
329 | |
330 | *radix_pointer = newpage; | |
331 | __put_page(page); | |
332 | write_unlock_irq(&mapping->tree_lock); | |
333 | ||
334 | return 0; | |
335 | } | |
b20a3503 CL |
336 | |
337 | /* | |
338 | * Copy the page to its new location | |
339 | */ | |
e7340f73 | 340 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 CL |
341 | { |
342 | copy_highpage(newpage, page); | |
343 | ||
344 | if (PageError(page)) | |
345 | SetPageError(newpage); | |
346 | if (PageReferenced(page)) | |
347 | SetPageReferenced(newpage); | |
348 | if (PageUptodate(page)) | |
349 | SetPageUptodate(newpage); | |
350 | if (PageActive(page)) | |
351 | SetPageActive(newpage); | |
352 | if (PageChecked(page)) | |
353 | SetPageChecked(newpage); | |
354 | if (PageMappedToDisk(page)) | |
355 | SetPageMappedToDisk(newpage); | |
356 | ||
357 | if (PageDirty(page)) { | |
358 | clear_page_dirty_for_io(page); | |
359 | set_page_dirty(newpage); | |
360 | } | |
361 | ||
6c5240ae | 362 | #ifdef CONFIG_SWAP |
b20a3503 | 363 | ClearPageSwapCache(page); |
6c5240ae | 364 | #endif |
b20a3503 CL |
365 | ClearPageActive(page); |
366 | ClearPagePrivate(page); | |
367 | set_page_private(page, 0); | |
368 | page->mapping = NULL; | |
369 | ||
370 | /* | |
371 | * If any waiters have accumulated on the new page then | |
372 | * wake them up. | |
373 | */ | |
374 | if (PageWriteback(newpage)) | |
375 | end_page_writeback(newpage); | |
376 | } | |
b20a3503 | 377 | |
1d8b85cc CL |
378 | /************************************************************ |
379 | * Migration functions | |
380 | ***********************************************************/ | |
381 | ||
382 | /* Always fail migration. Used for mappings that are not movable */ | |
2d1db3b1 CL |
383 | int fail_migrate_page(struct address_space *mapping, |
384 | struct page *newpage, struct page *page) | |
1d8b85cc CL |
385 | { |
386 | return -EIO; | |
387 | } | |
388 | EXPORT_SYMBOL(fail_migrate_page); | |
389 | ||
b20a3503 CL |
390 | /* |
391 | * Common logic to directly migrate a single page suitable for | |
392 | * pages that do not use PagePrivate. | |
393 | * | |
394 | * Pages are locked upon entry and exit. | |
395 | */ | |
2d1db3b1 CL |
396 | int migrate_page(struct address_space *mapping, |
397 | struct page *newpage, struct page *page) | |
b20a3503 CL |
398 | { |
399 | int rc; | |
400 | ||
401 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
402 | ||
2d1db3b1 | 403 | rc = migrate_page_move_mapping(mapping, newpage, page); |
b20a3503 CL |
404 | |
405 | if (rc) | |
406 | return rc; | |
407 | ||
408 | migrate_page_copy(newpage, page); | |
b20a3503 CL |
409 | return 0; |
410 | } | |
411 | EXPORT_SYMBOL(migrate_page); | |
412 | ||
1d8b85cc CL |
413 | /* |
414 | * Migration function for pages with buffers. This function can only be used | |
415 | * if the underlying filesystem guarantees that no other references to "page" | |
416 | * exist. | |
417 | */ | |
2d1db3b1 CL |
418 | int buffer_migrate_page(struct address_space *mapping, |
419 | struct page *newpage, struct page *page) | |
1d8b85cc | 420 | { |
1d8b85cc CL |
421 | struct buffer_head *bh, *head; |
422 | int rc; | |
423 | ||
1d8b85cc | 424 | if (!page_has_buffers(page)) |
2d1db3b1 | 425 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
426 | |
427 | head = page_buffers(page); | |
428 | ||
2d1db3b1 | 429 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
430 | |
431 | if (rc) | |
432 | return rc; | |
433 | ||
434 | bh = head; | |
435 | do { | |
436 | get_bh(bh); | |
437 | lock_buffer(bh); | |
438 | bh = bh->b_this_page; | |
439 | ||
440 | } while (bh != head); | |
441 | ||
442 | ClearPagePrivate(page); | |
443 | set_page_private(newpage, page_private(page)); | |
444 | set_page_private(page, 0); | |
445 | put_page(page); | |
446 | get_page(newpage); | |
447 | ||
448 | bh = head; | |
449 | do { | |
450 | set_bh_page(bh, newpage, bh_offset(bh)); | |
451 | bh = bh->b_this_page; | |
452 | ||
453 | } while (bh != head); | |
454 | ||
455 | SetPagePrivate(newpage); | |
456 | ||
457 | migrate_page_copy(newpage, page); | |
458 | ||
459 | bh = head; | |
460 | do { | |
461 | unlock_buffer(bh); | |
462 | put_bh(bh); | |
463 | bh = bh->b_this_page; | |
464 | ||
465 | } while (bh != head); | |
466 | ||
467 | return 0; | |
468 | } | |
469 | EXPORT_SYMBOL(buffer_migrate_page); | |
470 | ||
04e62a29 CL |
471 | /* |
472 | * Writeback a page to clean the dirty state | |
473 | */ | |
474 | static int writeout(struct address_space *mapping, struct page *page) | |
8351a6e4 | 475 | { |
04e62a29 CL |
476 | struct writeback_control wbc = { |
477 | .sync_mode = WB_SYNC_NONE, | |
478 | .nr_to_write = 1, | |
479 | .range_start = 0, | |
480 | .range_end = LLONG_MAX, | |
481 | .nonblocking = 1, | |
482 | .for_reclaim = 1 | |
483 | }; | |
484 | int rc; | |
485 | ||
486 | if (!mapping->a_ops->writepage) | |
487 | /* No write method for the address space */ | |
488 | return -EINVAL; | |
489 | ||
490 | if (!clear_page_dirty_for_io(page)) | |
491 | /* Someone else already triggered a write */ | |
492 | return -EAGAIN; | |
493 | ||
8351a6e4 | 494 | /* |
04e62a29 CL |
495 | * A dirty page may imply that the underlying filesystem has |
496 | * the page on some queue. So the page must be clean for | |
497 | * migration. Writeout may mean we loose the lock and the | |
498 | * page state is no longer what we checked for earlier. | |
499 | * At this point we know that the migration attempt cannot | |
500 | * be successful. | |
8351a6e4 | 501 | */ |
04e62a29 | 502 | remove_migration_ptes(page, page); |
8351a6e4 | 503 | |
04e62a29 CL |
504 | rc = mapping->a_ops->writepage(page, &wbc); |
505 | if (rc < 0) | |
506 | /* I/O Error writing */ | |
507 | return -EIO; | |
8351a6e4 | 508 | |
04e62a29 CL |
509 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
510 | /* unlocked. Relock */ | |
511 | lock_page(page); | |
512 | ||
513 | return -EAGAIN; | |
514 | } | |
515 | ||
516 | /* | |
517 | * Default handling if a filesystem does not provide a migration function. | |
518 | */ | |
519 | static int fallback_migrate_page(struct address_space *mapping, | |
520 | struct page *newpage, struct page *page) | |
521 | { | |
522 | if (PageDirty(page)) | |
523 | return writeout(mapping, page); | |
8351a6e4 CL |
524 | |
525 | /* | |
526 | * Buffers may be managed in a filesystem specific way. | |
527 | * We must have no buffers or drop them. | |
528 | */ | |
529 | if (page_has_buffers(page) && | |
530 | !try_to_release_page(page, GFP_KERNEL)) | |
531 | return -EAGAIN; | |
532 | ||
533 | return migrate_page(mapping, newpage, page); | |
534 | } | |
535 | ||
e24f0b8f CL |
536 | /* |
537 | * Move a page to a newly allocated page | |
538 | * The page is locked and all ptes have been successfully removed. | |
539 | * | |
540 | * The new page will have replaced the old page if this function | |
541 | * is successful. | |
542 | */ | |
543 | static int move_to_new_page(struct page *newpage, struct page *page) | |
544 | { | |
545 | struct address_space *mapping; | |
546 | int rc; | |
547 | ||
548 | /* | |
549 | * Block others from accessing the page when we get around to | |
550 | * establishing additional references. We are the only one | |
551 | * holding a reference to the new page at this point. | |
552 | */ | |
553 | if (TestSetPageLocked(newpage)) | |
554 | BUG(); | |
555 | ||
556 | /* Prepare mapping for the new page.*/ | |
557 | newpage->index = page->index; | |
558 | newpage->mapping = page->mapping; | |
559 | ||
560 | mapping = page_mapping(page); | |
561 | if (!mapping) | |
562 | rc = migrate_page(mapping, newpage, page); | |
563 | else if (mapping->a_ops->migratepage) | |
564 | /* | |
565 | * Most pages have a mapping and most filesystems | |
566 | * should provide a migration function. Anonymous | |
567 | * pages are part of swap space which also has its | |
568 | * own migration function. This is the most common | |
569 | * path for page migration. | |
570 | */ | |
571 | rc = mapping->a_ops->migratepage(mapping, | |
572 | newpage, page); | |
573 | else | |
574 | rc = fallback_migrate_page(mapping, newpage, page); | |
575 | ||
576 | if (!rc) | |
577 | remove_migration_ptes(page, newpage); | |
578 | else | |
579 | newpage->mapping = NULL; | |
580 | ||
581 | unlock_page(newpage); | |
582 | ||
583 | return rc; | |
584 | } | |
585 | ||
586 | /* | |
587 | * Obtain the lock on page, remove all ptes and migrate the page | |
588 | * to the newly allocated page in newpage. | |
589 | */ | |
590 | static int unmap_and_move(struct page *newpage, struct page *page, int force) | |
591 | { | |
592 | int rc = 0; | |
593 | ||
594 | if (page_count(page) == 1) | |
595 | /* page was freed from under us. So we are done. */ | |
596 | goto ret; | |
597 | ||
598 | rc = -EAGAIN; | |
599 | if (TestSetPageLocked(page)) { | |
600 | if (!force) | |
601 | goto ret; | |
602 | lock_page(page); | |
603 | } | |
604 | ||
605 | if (PageWriteback(page)) { | |
606 | if (!force) | |
607 | goto unlock; | |
608 | wait_on_page_writeback(page); | |
609 | } | |
610 | ||
611 | /* | |
612 | * Establish migration ptes or remove ptes | |
613 | */ | |
614 | if (try_to_unmap(page, 1) != SWAP_FAIL) { | |
615 | if (!page_mapped(page)) | |
616 | rc = move_to_new_page(newpage, page); | |
617 | } else | |
618 | /* A vma has VM_LOCKED set -> permanent failure */ | |
619 | rc = -EPERM; | |
620 | ||
621 | if (rc) | |
622 | remove_migration_ptes(page, page); | |
623 | unlock: | |
624 | unlock_page(page); | |
625 | ret: | |
626 | if (rc != -EAGAIN) { | |
627 | list_del(&newpage->lru); | |
628 | move_to_lru(newpage); | |
629 | } | |
630 | return rc; | |
631 | } | |
632 | ||
b20a3503 CL |
633 | /* |
634 | * migrate_pages | |
635 | * | |
636 | * Two lists are passed to this function. The first list | |
637 | * contains the pages isolated from the LRU to be migrated. | |
e24f0b8f | 638 | * The second list contains new pages that the isolated pages |
d75a0fcd | 639 | * can be moved to. |
b20a3503 CL |
640 | * |
641 | * The function returns after 10 attempts or if no pages | |
642 | * are movable anymore because to has become empty | |
643 | * or no retryable pages exist anymore. | |
644 | * | |
645 | * Return: Number of pages not migrated when "to" ran empty. | |
646 | */ | |
647 | int migrate_pages(struct list_head *from, struct list_head *to, | |
648 | struct list_head *moved, struct list_head *failed) | |
649 | { | |
e24f0b8f | 650 | int retry = 1; |
b20a3503 CL |
651 | int nr_failed = 0; |
652 | int pass = 0; | |
653 | struct page *page; | |
654 | struct page *page2; | |
655 | int swapwrite = current->flags & PF_SWAPWRITE; | |
656 | int rc; | |
657 | ||
658 | if (!swapwrite) | |
659 | current->flags |= PF_SWAPWRITE; | |
660 | ||
e24f0b8f CL |
661 | for(pass = 0; pass < 10 && retry; pass++) { |
662 | retry = 0; | |
b20a3503 | 663 | |
e24f0b8f | 664 | list_for_each_entry_safe(page, page2, from, lru) { |
b20a3503 | 665 | |
e24f0b8f CL |
666 | if (list_empty(to)) |
667 | break; | |
c3fcf8a5 | 668 | |
e24f0b8f | 669 | cond_resched(); |
2d1db3b1 | 670 | |
e24f0b8f | 671 | rc = unmap_and_move(lru_to_page(to), page, pass > 2); |
2d1db3b1 | 672 | |
e24f0b8f CL |
673 | switch(rc) { |
674 | case -EAGAIN: | |
2d1db3b1 | 675 | retry++; |
e24f0b8f CL |
676 | break; |
677 | case 0: | |
678 | list_move(&page->lru, moved); | |
679 | break; | |
680 | default: | |
2d1db3b1 CL |
681 | /* Permanent failure */ |
682 | list_move(&page->lru, failed); | |
683 | nr_failed++; | |
e24f0b8f | 684 | break; |
2d1db3b1 | 685 | } |
b20a3503 CL |
686 | } |
687 | } | |
b20a3503 CL |
688 | |
689 | if (!swapwrite) | |
690 | current->flags &= ~PF_SWAPWRITE; | |
691 | ||
692 | return nr_failed + retry; | |
693 | } | |
694 | ||
b20a3503 CL |
695 | /* |
696 | * Migrate the list 'pagelist' of pages to a certain destination. | |
697 | * | |
698 | * Specify destination with either non-NULL vma or dest_node >= 0 | |
699 | * Return the number of pages not migrated or error code | |
700 | */ | |
701 | int migrate_pages_to(struct list_head *pagelist, | |
702 | struct vm_area_struct *vma, int dest) | |
703 | { | |
704 | LIST_HEAD(newlist); | |
705 | LIST_HEAD(moved); | |
706 | LIST_HEAD(failed); | |
707 | int err = 0; | |
708 | unsigned long offset = 0; | |
709 | int nr_pages; | |
710 | struct page *page; | |
711 | struct list_head *p; | |
712 | ||
713 | redo: | |
714 | nr_pages = 0; | |
715 | list_for_each(p, pagelist) { | |
716 | if (vma) { | |
717 | /* | |
718 | * The address passed to alloc_page_vma is used to | |
719 | * generate the proper interleave behavior. We fake | |
720 | * the address here by an increasing offset in order | |
721 | * to get the proper distribution of pages. | |
722 | * | |
723 | * No decision has been made as to which page | |
724 | * a certain old page is moved to so we cannot | |
725 | * specify the correct address. | |
726 | */ | |
727 | page = alloc_page_vma(GFP_HIGHUSER, vma, | |
728 | offset + vma->vm_start); | |
729 | offset += PAGE_SIZE; | |
730 | } | |
731 | else | |
732 | page = alloc_pages_node(dest, GFP_HIGHUSER, 0); | |
733 | ||
734 | if (!page) { | |
735 | err = -ENOMEM; | |
736 | goto out; | |
737 | } | |
738 | list_add_tail(&page->lru, &newlist); | |
739 | nr_pages++; | |
740 | if (nr_pages > MIGRATE_CHUNK_SIZE) | |
741 | break; | |
742 | } | |
743 | err = migrate_pages(pagelist, &newlist, &moved, &failed); | |
744 | ||
745 | putback_lru_pages(&moved); /* Call release pages instead ?? */ | |
746 | ||
747 | if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist)) | |
748 | goto redo; | |
749 | out: | |
750 | /* Return leftover allocated pages */ | |
751 | while (!list_empty(&newlist)) { | |
752 | page = list_entry(newlist.next, struct page, lru); | |
753 | list_del(&page->lru); | |
754 | __free_page(page); | |
755 | } | |
756 | list_splice(&failed, pagelist); | |
757 | if (err < 0) | |
758 | return err; | |
759 | ||
760 | /* Calculate number of leftover pages */ | |
761 | nr_pages = 0; | |
762 | list_for_each(p, pagelist) | |
763 | nr_pages++; | |
764 | return nr_pages; | |
765 | } |