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 | 21 | #include <linux/mm_inline.h> |
b488893a | 22 | #include <linux/nsproxy.h> |
b20a3503 CL |
23 | #include <linux/pagevec.h> |
24 | #include <linux/rmap.h> | |
25 | #include <linux/topology.h> | |
26 | #include <linux/cpu.h> | |
27 | #include <linux/cpuset.h> | |
04e62a29 | 28 | #include <linux/writeback.h> |
742755a1 CL |
29 | #include <linux/mempolicy.h> |
30 | #include <linux/vmalloc.h> | |
86c3a764 | 31 | #include <linux/security.h> |
b20a3503 CL |
32 | |
33 | #include "internal.h" | |
34 | ||
b20a3503 CL |
35 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
36 | ||
37 | /* | |
38 | * Isolate one page from the LRU lists. If successful put it onto | |
39 | * the indicated list with elevated page count. | |
40 | * | |
41 | * Result: | |
42 | * -EBUSY: page not on LRU list | |
43 | * 0: page removed from LRU list and added to the specified list. | |
44 | */ | |
45 | int isolate_lru_page(struct page *page, struct list_head *pagelist) | |
46 | { | |
47 | int ret = -EBUSY; | |
48 | ||
49 | if (PageLRU(page)) { | |
50 | struct zone *zone = page_zone(page); | |
51 | ||
52 | spin_lock_irq(&zone->lru_lock); | |
3dd9fe8c | 53 | if (PageLRU(page) && get_page_unless_zero(page)) { |
b20a3503 | 54 | ret = 0; |
b20a3503 CL |
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 | /* | |
742755a1 CL |
68 | * migrate_prep() needs to be called before we start compiling a list of pages |
69 | * to be migrated using isolate_lru_page(). | |
b20a3503 CL |
70 | */ |
71 | int migrate_prep(void) | |
72 | { | |
b20a3503 CL |
73 | /* |
74 | * Clear the LRU lists so pages can be isolated. | |
75 | * Note that pages may be moved off the LRU after we have | |
76 | * drained them. Those pages will fail to migrate like other | |
77 | * pages that may be busy. | |
78 | */ | |
79 | lru_add_drain_all(); | |
80 | ||
81 | return 0; | |
82 | } | |
83 | ||
84 | static inline void move_to_lru(struct page *page) | |
85 | { | |
b20a3503 CL |
86 | if (PageActive(page)) { |
87 | /* | |
88 | * lru_cache_add_active checks that | |
89 | * the PG_active bit is off. | |
90 | */ | |
91 | ClearPageActive(page); | |
92 | lru_cache_add_active(page); | |
93 | } else { | |
94 | lru_cache_add(page); | |
95 | } | |
96 | put_page(page); | |
97 | } | |
98 | ||
99 | /* | |
100 | * Add isolated pages on the list back to the LRU. | |
101 | * | |
102 | * returns the number of pages put back. | |
103 | */ | |
104 | int putback_lru_pages(struct list_head *l) | |
105 | { | |
106 | struct page *page; | |
107 | struct page *page2; | |
108 | int count = 0; | |
109 | ||
110 | list_for_each_entry_safe(page, page2, l, lru) { | |
e24f0b8f | 111 | list_del(&page->lru); |
b20a3503 CL |
112 | move_to_lru(page); |
113 | count++; | |
114 | } | |
115 | return count; | |
116 | } | |
117 | ||
0697212a CL |
118 | /* |
119 | * Restore a potential migration pte to a working pte entry | |
120 | */ | |
04e62a29 | 121 | static void remove_migration_pte(struct vm_area_struct *vma, |
0697212a CL |
122 | struct page *old, struct page *new) |
123 | { | |
124 | struct mm_struct *mm = vma->vm_mm; | |
125 | swp_entry_t entry; | |
126 | pgd_t *pgd; | |
127 | pud_t *pud; | |
128 | pmd_t *pmd; | |
129 | pte_t *ptep, pte; | |
130 | spinlock_t *ptl; | |
04e62a29 CL |
131 | unsigned long addr = page_address_in_vma(new, vma); |
132 | ||
133 | if (addr == -EFAULT) | |
134 | return; | |
0697212a CL |
135 | |
136 | pgd = pgd_offset(mm, addr); | |
137 | if (!pgd_present(*pgd)) | |
138 | return; | |
139 | ||
140 | pud = pud_offset(pgd, addr); | |
141 | if (!pud_present(*pud)) | |
142 | return; | |
143 | ||
144 | pmd = pmd_offset(pud, addr); | |
145 | if (!pmd_present(*pmd)) | |
146 | return; | |
147 | ||
148 | ptep = pte_offset_map(pmd, addr); | |
149 | ||
150 | if (!is_swap_pte(*ptep)) { | |
151 | pte_unmap(ptep); | |
152 | return; | |
153 | } | |
154 | ||
155 | ptl = pte_lockptr(mm, pmd); | |
156 | spin_lock(ptl); | |
157 | pte = *ptep; | |
158 | if (!is_swap_pte(pte)) | |
159 | goto out; | |
160 | ||
161 | entry = pte_to_swp_entry(pte); | |
162 | ||
163 | if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) | |
164 | goto out; | |
165 | ||
0697212a CL |
166 | get_page(new); |
167 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
168 | if (is_write_migration_entry(entry)) | |
169 | pte = pte_mkwrite(pte); | |
97ee0524 | 170 | flush_cache_page(vma, addr, pte_pfn(pte)); |
0697212a | 171 | set_pte_at(mm, addr, ptep, pte); |
04e62a29 CL |
172 | |
173 | if (PageAnon(new)) | |
174 | page_add_anon_rmap(new, vma, addr); | |
175 | else | |
176 | page_add_file_rmap(new); | |
177 | ||
178 | /* No need to invalidate - it was non-present before */ | |
179 | update_mmu_cache(vma, addr, pte); | |
04e62a29 | 180 | |
0697212a CL |
181 | out: |
182 | pte_unmap_unlock(ptep, ptl); | |
183 | } | |
184 | ||
185 | /* | |
04e62a29 CL |
186 | * Note that remove_file_migration_ptes will only work on regular mappings, |
187 | * Nonlinear mappings do not use migration entries. | |
188 | */ | |
189 | static void remove_file_migration_ptes(struct page *old, struct page *new) | |
190 | { | |
191 | struct vm_area_struct *vma; | |
192 | struct address_space *mapping = page_mapping(new); | |
193 | struct prio_tree_iter iter; | |
194 | pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
195 | ||
196 | if (!mapping) | |
197 | return; | |
198 | ||
199 | spin_lock(&mapping->i_mmap_lock); | |
200 | ||
201 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) | |
202 | remove_migration_pte(vma, old, new); | |
203 | ||
204 | spin_unlock(&mapping->i_mmap_lock); | |
205 | } | |
206 | ||
207 | /* | |
0697212a CL |
208 | * Must hold mmap_sem lock on at least one of the vmas containing |
209 | * the page so that the anon_vma cannot vanish. | |
210 | */ | |
04e62a29 | 211 | static void remove_anon_migration_ptes(struct page *old, struct page *new) |
0697212a CL |
212 | { |
213 | struct anon_vma *anon_vma; | |
214 | struct vm_area_struct *vma; | |
215 | unsigned long mapping; | |
216 | ||
217 | mapping = (unsigned long)new->mapping; | |
218 | ||
219 | if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) | |
220 | return; | |
221 | ||
222 | /* | |
223 | * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. | |
224 | */ | |
225 | anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); | |
226 | spin_lock(&anon_vma->lock); | |
227 | ||
228 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) | |
04e62a29 | 229 | remove_migration_pte(vma, old, new); |
0697212a CL |
230 | |
231 | spin_unlock(&anon_vma->lock); | |
232 | } | |
233 | ||
04e62a29 CL |
234 | /* |
235 | * Get rid of all migration entries and replace them by | |
236 | * references to the indicated page. | |
237 | */ | |
238 | static void remove_migration_ptes(struct page *old, struct page *new) | |
239 | { | |
240 | if (PageAnon(new)) | |
241 | remove_anon_migration_ptes(old, new); | |
242 | else | |
243 | remove_file_migration_ptes(old, new); | |
244 | } | |
245 | ||
0697212a CL |
246 | /* |
247 | * Something used the pte of a page under migration. We need to | |
248 | * get to the page and wait until migration is finished. | |
249 | * When we return from this function the fault will be retried. | |
250 | * | |
251 | * This function is called from do_swap_page(). | |
252 | */ | |
253 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
254 | unsigned long address) | |
255 | { | |
256 | pte_t *ptep, pte; | |
257 | spinlock_t *ptl; | |
258 | swp_entry_t entry; | |
259 | struct page *page; | |
260 | ||
261 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
262 | pte = *ptep; | |
263 | if (!is_swap_pte(pte)) | |
264 | goto out; | |
265 | ||
266 | entry = pte_to_swp_entry(pte); | |
267 | if (!is_migration_entry(entry)) | |
268 | goto out; | |
269 | ||
270 | page = migration_entry_to_page(entry); | |
271 | ||
272 | get_page(page); | |
273 | pte_unmap_unlock(ptep, ptl); | |
274 | wait_on_page_locked(page); | |
275 | put_page(page); | |
276 | return; | |
277 | out: | |
278 | pte_unmap_unlock(ptep, ptl); | |
279 | } | |
280 | ||
b20a3503 | 281 | /* |
c3fcf8a5 | 282 | * Replace the page in the mapping. |
5b5c7120 CL |
283 | * |
284 | * The number of remaining references must be: | |
285 | * 1 for anonymous pages without a mapping | |
286 | * 2 for pages with a mapping | |
287 | * 3 for pages with a mapping and PagePrivate set. | |
b20a3503 | 288 | */ |
2d1db3b1 CL |
289 | static int migrate_page_move_mapping(struct address_space *mapping, |
290 | struct page *newpage, struct page *page) | |
b20a3503 | 291 | { |
7cf9c2c7 | 292 | void **pslot; |
b20a3503 | 293 | |
6c5240ae | 294 | if (!mapping) { |
0e8c7d0f | 295 | /* Anonymous page without mapping */ |
6c5240ae CL |
296 | if (page_count(page) != 1) |
297 | return -EAGAIN; | |
298 | return 0; | |
299 | } | |
300 | ||
b20a3503 CL |
301 | write_lock_irq(&mapping->tree_lock); |
302 | ||
7cf9c2c7 NP |
303 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
304 | page_index(page)); | |
b20a3503 | 305 | |
6c5240ae | 306 | if (page_count(page) != 2 + !!PagePrivate(page) || |
7cf9c2c7 | 307 | (struct page *)radix_tree_deref_slot(pslot) != page) { |
b20a3503 | 308 | write_unlock_irq(&mapping->tree_lock); |
e23ca00b | 309 | return -EAGAIN; |
b20a3503 CL |
310 | } |
311 | ||
312 | /* | |
313 | * Now we know that no one else is looking at the page. | |
b20a3503 | 314 | */ |
7cf9c2c7 | 315 | get_page(newpage); /* add cache reference */ |
6c5240ae | 316 | #ifdef CONFIG_SWAP |
b20a3503 CL |
317 | if (PageSwapCache(page)) { |
318 | SetPageSwapCache(newpage); | |
319 | set_page_private(newpage, page_private(page)); | |
320 | } | |
6c5240ae | 321 | #endif |
b20a3503 | 322 | |
7cf9c2c7 NP |
323 | radix_tree_replace_slot(pslot, newpage); |
324 | ||
325 | /* | |
326 | * Drop cache reference from old page. | |
327 | * We know this isn't the last reference. | |
328 | */ | |
b20a3503 | 329 | __put_page(page); |
7cf9c2c7 | 330 | |
0e8c7d0f CL |
331 | /* |
332 | * If moved to a different zone then also account | |
333 | * the page for that zone. Other VM counters will be | |
334 | * taken care of when we establish references to the | |
335 | * new page and drop references to the old page. | |
336 | * | |
337 | * Note that anonymous pages are accounted for | |
338 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
339 | * are mapped to swap space. | |
340 | */ | |
341 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
342 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
343 | ||
b20a3503 CL |
344 | write_unlock_irq(&mapping->tree_lock); |
345 | ||
346 | return 0; | |
347 | } | |
b20a3503 CL |
348 | |
349 | /* | |
350 | * Copy the page to its new location | |
351 | */ | |
e7340f73 | 352 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 CL |
353 | { |
354 | copy_highpage(newpage, page); | |
355 | ||
356 | if (PageError(page)) | |
357 | SetPageError(newpage); | |
358 | if (PageReferenced(page)) | |
359 | SetPageReferenced(newpage); | |
360 | if (PageUptodate(page)) | |
361 | SetPageUptodate(newpage); | |
362 | if (PageActive(page)) | |
363 | SetPageActive(newpage); | |
364 | if (PageChecked(page)) | |
365 | SetPageChecked(newpage); | |
366 | if (PageMappedToDisk(page)) | |
367 | SetPageMappedToDisk(newpage); | |
368 | ||
369 | if (PageDirty(page)) { | |
370 | clear_page_dirty_for_io(page); | |
371 | set_page_dirty(newpage); | |
372 | } | |
373 | ||
6c5240ae | 374 | #ifdef CONFIG_SWAP |
b20a3503 | 375 | ClearPageSwapCache(page); |
6c5240ae | 376 | #endif |
b20a3503 CL |
377 | ClearPageActive(page); |
378 | ClearPagePrivate(page); | |
379 | set_page_private(page, 0); | |
380 | page->mapping = NULL; | |
381 | ||
382 | /* | |
383 | * If any waiters have accumulated on the new page then | |
384 | * wake them up. | |
385 | */ | |
386 | if (PageWriteback(newpage)) | |
387 | end_page_writeback(newpage); | |
388 | } | |
b20a3503 | 389 | |
1d8b85cc CL |
390 | /************************************************************ |
391 | * Migration functions | |
392 | ***********************************************************/ | |
393 | ||
394 | /* Always fail migration. Used for mappings that are not movable */ | |
2d1db3b1 CL |
395 | int fail_migrate_page(struct address_space *mapping, |
396 | struct page *newpage, struct page *page) | |
1d8b85cc CL |
397 | { |
398 | return -EIO; | |
399 | } | |
400 | EXPORT_SYMBOL(fail_migrate_page); | |
401 | ||
b20a3503 CL |
402 | /* |
403 | * Common logic to directly migrate a single page suitable for | |
404 | * pages that do not use PagePrivate. | |
405 | * | |
406 | * Pages are locked upon entry and exit. | |
407 | */ | |
2d1db3b1 CL |
408 | int migrate_page(struct address_space *mapping, |
409 | struct page *newpage, struct page *page) | |
b20a3503 CL |
410 | { |
411 | int rc; | |
412 | ||
413 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
414 | ||
2d1db3b1 | 415 | rc = migrate_page_move_mapping(mapping, newpage, page); |
b20a3503 CL |
416 | |
417 | if (rc) | |
418 | return rc; | |
419 | ||
420 | migrate_page_copy(newpage, page); | |
b20a3503 CL |
421 | return 0; |
422 | } | |
423 | EXPORT_SYMBOL(migrate_page); | |
424 | ||
9361401e | 425 | #ifdef CONFIG_BLOCK |
1d8b85cc CL |
426 | /* |
427 | * Migration function for pages with buffers. This function can only be used | |
428 | * if the underlying filesystem guarantees that no other references to "page" | |
429 | * exist. | |
430 | */ | |
2d1db3b1 CL |
431 | int buffer_migrate_page(struct address_space *mapping, |
432 | struct page *newpage, struct page *page) | |
1d8b85cc | 433 | { |
1d8b85cc CL |
434 | struct buffer_head *bh, *head; |
435 | int rc; | |
436 | ||
1d8b85cc | 437 | if (!page_has_buffers(page)) |
2d1db3b1 | 438 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
439 | |
440 | head = page_buffers(page); | |
441 | ||
2d1db3b1 | 442 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
443 | |
444 | if (rc) | |
445 | return rc; | |
446 | ||
447 | bh = head; | |
448 | do { | |
449 | get_bh(bh); | |
450 | lock_buffer(bh); | |
451 | bh = bh->b_this_page; | |
452 | ||
453 | } while (bh != head); | |
454 | ||
455 | ClearPagePrivate(page); | |
456 | set_page_private(newpage, page_private(page)); | |
457 | set_page_private(page, 0); | |
458 | put_page(page); | |
459 | get_page(newpage); | |
460 | ||
461 | bh = head; | |
462 | do { | |
463 | set_bh_page(bh, newpage, bh_offset(bh)); | |
464 | bh = bh->b_this_page; | |
465 | ||
466 | } while (bh != head); | |
467 | ||
468 | SetPagePrivate(newpage); | |
469 | ||
470 | migrate_page_copy(newpage, page); | |
471 | ||
472 | bh = head; | |
473 | do { | |
474 | unlock_buffer(bh); | |
475 | put_bh(bh); | |
476 | bh = bh->b_this_page; | |
477 | ||
478 | } while (bh != head); | |
479 | ||
480 | return 0; | |
481 | } | |
482 | EXPORT_SYMBOL(buffer_migrate_page); | |
9361401e | 483 | #endif |
1d8b85cc | 484 | |
04e62a29 CL |
485 | /* |
486 | * Writeback a page to clean the dirty state | |
487 | */ | |
488 | static int writeout(struct address_space *mapping, struct page *page) | |
8351a6e4 | 489 | { |
04e62a29 CL |
490 | struct writeback_control wbc = { |
491 | .sync_mode = WB_SYNC_NONE, | |
492 | .nr_to_write = 1, | |
493 | .range_start = 0, | |
494 | .range_end = LLONG_MAX, | |
495 | .nonblocking = 1, | |
496 | .for_reclaim = 1 | |
497 | }; | |
498 | int rc; | |
499 | ||
500 | if (!mapping->a_ops->writepage) | |
501 | /* No write method for the address space */ | |
502 | return -EINVAL; | |
503 | ||
504 | if (!clear_page_dirty_for_io(page)) | |
505 | /* Someone else already triggered a write */ | |
506 | return -EAGAIN; | |
507 | ||
8351a6e4 | 508 | /* |
04e62a29 CL |
509 | * A dirty page may imply that the underlying filesystem has |
510 | * the page on some queue. So the page must be clean for | |
511 | * migration. Writeout may mean we loose the lock and the | |
512 | * page state is no longer what we checked for earlier. | |
513 | * At this point we know that the migration attempt cannot | |
514 | * be successful. | |
8351a6e4 | 515 | */ |
04e62a29 | 516 | remove_migration_ptes(page, page); |
8351a6e4 | 517 | |
04e62a29 CL |
518 | rc = mapping->a_ops->writepage(page, &wbc); |
519 | if (rc < 0) | |
520 | /* I/O Error writing */ | |
521 | return -EIO; | |
8351a6e4 | 522 | |
04e62a29 CL |
523 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
524 | /* unlocked. Relock */ | |
525 | lock_page(page); | |
526 | ||
527 | return -EAGAIN; | |
528 | } | |
529 | ||
530 | /* | |
531 | * Default handling if a filesystem does not provide a migration function. | |
532 | */ | |
533 | static int fallback_migrate_page(struct address_space *mapping, | |
534 | struct page *newpage, struct page *page) | |
535 | { | |
536 | if (PageDirty(page)) | |
537 | return writeout(mapping, page); | |
8351a6e4 CL |
538 | |
539 | /* | |
540 | * Buffers may be managed in a filesystem specific way. | |
541 | * We must have no buffers or drop them. | |
542 | */ | |
b398f6bf | 543 | if (PagePrivate(page) && |
8351a6e4 CL |
544 | !try_to_release_page(page, GFP_KERNEL)) |
545 | return -EAGAIN; | |
546 | ||
547 | return migrate_page(mapping, newpage, page); | |
548 | } | |
549 | ||
e24f0b8f CL |
550 | /* |
551 | * Move a page to a newly allocated page | |
552 | * The page is locked and all ptes have been successfully removed. | |
553 | * | |
554 | * The new page will have replaced the old page if this function | |
555 | * is successful. | |
556 | */ | |
557 | static int move_to_new_page(struct page *newpage, struct page *page) | |
558 | { | |
559 | struct address_space *mapping; | |
560 | int rc; | |
561 | ||
562 | /* | |
563 | * Block others from accessing the page when we get around to | |
564 | * establishing additional references. We are the only one | |
565 | * holding a reference to the new page at this point. | |
566 | */ | |
567 | if (TestSetPageLocked(newpage)) | |
568 | BUG(); | |
569 | ||
570 | /* Prepare mapping for the new page.*/ | |
571 | newpage->index = page->index; | |
572 | newpage->mapping = page->mapping; | |
573 | ||
574 | mapping = page_mapping(page); | |
575 | if (!mapping) | |
576 | rc = migrate_page(mapping, newpage, page); | |
577 | else if (mapping->a_ops->migratepage) | |
578 | /* | |
579 | * Most pages have a mapping and most filesystems | |
580 | * should provide a migration function. Anonymous | |
581 | * pages are part of swap space which also has its | |
582 | * own migration function. This is the most common | |
583 | * path for page migration. | |
584 | */ | |
585 | rc = mapping->a_ops->migratepage(mapping, | |
586 | newpage, page); | |
587 | else | |
588 | rc = fallback_migrate_page(mapping, newpage, page); | |
589 | ||
590 | if (!rc) | |
591 | remove_migration_ptes(page, newpage); | |
592 | else | |
593 | newpage->mapping = NULL; | |
594 | ||
595 | unlock_page(newpage); | |
596 | ||
597 | return rc; | |
598 | } | |
599 | ||
600 | /* | |
601 | * Obtain the lock on page, remove all ptes and migrate the page | |
602 | * to the newly allocated page in newpage. | |
603 | */ | |
95a402c3 CL |
604 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
605 | struct page *page, int force) | |
e24f0b8f CL |
606 | { |
607 | int rc = 0; | |
742755a1 CL |
608 | int *result = NULL; |
609 | struct page *newpage = get_new_page(page, private, &result); | |
989f89c5 | 610 | int rcu_locked = 0; |
95a402c3 CL |
611 | |
612 | if (!newpage) | |
613 | return -ENOMEM; | |
e24f0b8f CL |
614 | |
615 | if (page_count(page) == 1) | |
616 | /* page was freed from under us. So we are done. */ | |
95a402c3 | 617 | goto move_newpage; |
e24f0b8f CL |
618 | |
619 | rc = -EAGAIN; | |
620 | if (TestSetPageLocked(page)) { | |
621 | if (!force) | |
95a402c3 | 622 | goto move_newpage; |
e24f0b8f CL |
623 | lock_page(page); |
624 | } | |
625 | ||
626 | if (PageWriteback(page)) { | |
627 | if (!force) | |
628 | goto unlock; | |
629 | wait_on_page_writeback(page); | |
630 | } | |
e24f0b8f | 631 | /* |
dc386d4d KH |
632 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
633 | * we cannot notice that anon_vma is freed while we migrates a page. | |
634 | * This rcu_read_lock() delays freeing anon_vma pointer until the end | |
635 | * of migration. File cache pages are no problem because of page_lock() | |
989f89c5 KH |
636 | * File Caches may use write_page() or lock_page() in migration, then, |
637 | * just care Anon page here. | |
dc386d4d | 638 | */ |
989f89c5 KH |
639 | if (PageAnon(page)) { |
640 | rcu_read_lock(); | |
641 | rcu_locked = 1; | |
642 | } | |
62e1c553 | 643 | |
dc386d4d | 644 | /* |
62e1c553 SL |
645 | * Corner case handling: |
646 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
647 | * and treated as swapcache but it has no rmap yet. | |
648 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
649 | * trigger a BUG. So handle it here. | |
650 | * 2. An orphaned page (see truncate_complete_page) might have | |
651 | * fs-private metadata. The page can be picked up due to memory | |
652 | * offlining. Everywhere else except page reclaim, the page is | |
653 | * invisible to the vm, so the page can not be migrated. So try to | |
654 | * free the metadata, so the page can be freed. | |
e24f0b8f | 655 | */ |
62e1c553 SL |
656 | if (!page->mapping) { |
657 | if (!PageAnon(page) && PagePrivate(page)) { | |
658 | /* | |
659 | * Go direct to try_to_free_buffers() here because | |
660 | * a) that's what try_to_release_page() would do anyway | |
661 | * b) we may be under rcu_read_lock() here, so we can't | |
662 | * use GFP_KERNEL which is what try_to_release_page() | |
663 | * needs to be effective. | |
664 | */ | |
665 | try_to_free_buffers(page); | |
666 | } | |
dc386d4d | 667 | goto rcu_unlock; |
62e1c553 SL |
668 | } |
669 | ||
dc386d4d | 670 | /* Establish migration ptes or remove ptes */ |
e6a1530d | 671 | try_to_unmap(page, 1); |
dc386d4d | 672 | |
e6a1530d CL |
673 | if (!page_mapped(page)) |
674 | rc = move_to_new_page(newpage, page); | |
e24f0b8f CL |
675 | |
676 | if (rc) | |
677 | remove_migration_ptes(page, page); | |
dc386d4d | 678 | rcu_unlock: |
989f89c5 KH |
679 | if (rcu_locked) |
680 | rcu_read_unlock(); | |
e6a1530d | 681 | |
e24f0b8f | 682 | unlock: |
dc386d4d | 683 | |
e24f0b8f | 684 | unlock_page(page); |
95a402c3 | 685 | |
e24f0b8f | 686 | if (rc != -EAGAIN) { |
aaa994b3 CL |
687 | /* |
688 | * A page that has been migrated has all references | |
689 | * removed and will be freed. A page that has not been | |
690 | * migrated will have kepts its references and be | |
691 | * restored. | |
692 | */ | |
693 | list_del(&page->lru); | |
694 | move_to_lru(page); | |
e24f0b8f | 695 | } |
95a402c3 CL |
696 | |
697 | move_newpage: | |
698 | /* | |
699 | * Move the new page to the LRU. If migration was not successful | |
700 | * then this will free the page. | |
701 | */ | |
702 | move_to_lru(newpage); | |
742755a1 CL |
703 | if (result) { |
704 | if (rc) | |
705 | *result = rc; | |
706 | else | |
707 | *result = page_to_nid(newpage); | |
708 | } | |
e24f0b8f CL |
709 | return rc; |
710 | } | |
711 | ||
b20a3503 CL |
712 | /* |
713 | * migrate_pages | |
714 | * | |
95a402c3 CL |
715 | * The function takes one list of pages to migrate and a function |
716 | * that determines from the page to be migrated and the private data | |
717 | * the target of the move and allocates the page. | |
b20a3503 CL |
718 | * |
719 | * The function returns after 10 attempts or if no pages | |
720 | * are movable anymore because to has become empty | |
aaa994b3 | 721 | * or no retryable pages exist anymore. All pages will be |
e9534b3f | 722 | * returned to the LRU or freed. |
b20a3503 | 723 | * |
95a402c3 | 724 | * Return: Number of pages not migrated or error code. |
b20a3503 | 725 | */ |
95a402c3 CL |
726 | int migrate_pages(struct list_head *from, |
727 | new_page_t get_new_page, unsigned long private) | |
b20a3503 | 728 | { |
e24f0b8f | 729 | int retry = 1; |
b20a3503 CL |
730 | int nr_failed = 0; |
731 | int pass = 0; | |
732 | struct page *page; | |
733 | struct page *page2; | |
734 | int swapwrite = current->flags & PF_SWAPWRITE; | |
735 | int rc; | |
736 | ||
737 | if (!swapwrite) | |
738 | current->flags |= PF_SWAPWRITE; | |
739 | ||
e24f0b8f CL |
740 | for(pass = 0; pass < 10 && retry; pass++) { |
741 | retry = 0; | |
b20a3503 | 742 | |
e24f0b8f | 743 | list_for_each_entry_safe(page, page2, from, lru) { |
e24f0b8f | 744 | cond_resched(); |
2d1db3b1 | 745 | |
95a402c3 CL |
746 | rc = unmap_and_move(get_new_page, private, |
747 | page, pass > 2); | |
2d1db3b1 | 748 | |
e24f0b8f | 749 | switch(rc) { |
95a402c3 CL |
750 | case -ENOMEM: |
751 | goto out; | |
e24f0b8f | 752 | case -EAGAIN: |
2d1db3b1 | 753 | retry++; |
e24f0b8f CL |
754 | break; |
755 | case 0: | |
e24f0b8f CL |
756 | break; |
757 | default: | |
2d1db3b1 | 758 | /* Permanent failure */ |
2d1db3b1 | 759 | nr_failed++; |
e24f0b8f | 760 | break; |
2d1db3b1 | 761 | } |
b20a3503 CL |
762 | } |
763 | } | |
95a402c3 CL |
764 | rc = 0; |
765 | out: | |
b20a3503 CL |
766 | if (!swapwrite) |
767 | current->flags &= ~PF_SWAPWRITE; | |
768 | ||
aaa994b3 | 769 | putback_lru_pages(from); |
b20a3503 | 770 | |
95a402c3 CL |
771 | if (rc) |
772 | return rc; | |
b20a3503 | 773 | |
95a402c3 | 774 | return nr_failed + retry; |
b20a3503 | 775 | } |
95a402c3 | 776 | |
742755a1 CL |
777 | #ifdef CONFIG_NUMA |
778 | /* | |
779 | * Move a list of individual pages | |
780 | */ | |
781 | struct page_to_node { | |
782 | unsigned long addr; | |
783 | struct page *page; | |
784 | int node; | |
785 | int status; | |
786 | }; | |
787 | ||
788 | static struct page *new_page_node(struct page *p, unsigned long private, | |
789 | int **result) | |
790 | { | |
791 | struct page_to_node *pm = (struct page_to_node *)private; | |
792 | ||
793 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
794 | pm++; | |
795 | ||
796 | if (pm->node == MAX_NUMNODES) | |
797 | return NULL; | |
798 | ||
799 | *result = &pm->status; | |
800 | ||
769848c0 MG |
801 | return alloc_pages_node(pm->node, |
802 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); | |
742755a1 CL |
803 | } |
804 | ||
805 | /* | |
806 | * Move a set of pages as indicated in the pm array. The addr | |
807 | * field must be set to the virtual address of the page to be moved | |
808 | * and the node number must contain a valid target node. | |
809 | */ | |
810 | static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm, | |
811 | int migrate_all) | |
812 | { | |
813 | int err; | |
814 | struct page_to_node *pp; | |
815 | LIST_HEAD(pagelist); | |
816 | ||
817 | down_read(&mm->mmap_sem); | |
818 | ||
819 | /* | |
820 | * Build a list of pages to migrate | |
821 | */ | |
822 | migrate_prep(); | |
823 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { | |
824 | struct vm_area_struct *vma; | |
825 | struct page *page; | |
826 | ||
827 | /* | |
828 | * A valid page pointer that will not match any of the | |
829 | * pages that will be moved. | |
830 | */ | |
831 | pp->page = ZERO_PAGE(0); | |
832 | ||
833 | err = -EFAULT; | |
834 | vma = find_vma(mm, pp->addr); | |
0dc952dc | 835 | if (!vma || !vma_migratable(vma)) |
742755a1 CL |
836 | goto set_status; |
837 | ||
838 | page = follow_page(vma, pp->addr, FOLL_GET); | |
839 | err = -ENOENT; | |
840 | if (!page) | |
841 | goto set_status; | |
842 | ||
843 | if (PageReserved(page)) /* Check for zero page */ | |
844 | goto put_and_set; | |
845 | ||
846 | pp->page = page; | |
847 | err = page_to_nid(page); | |
848 | ||
849 | if (err == pp->node) | |
850 | /* | |
851 | * Node already in the right place | |
852 | */ | |
853 | goto put_and_set; | |
854 | ||
855 | err = -EACCES; | |
856 | if (page_mapcount(page) > 1 && | |
857 | !migrate_all) | |
858 | goto put_and_set; | |
859 | ||
860 | err = isolate_lru_page(page, &pagelist); | |
861 | put_and_set: | |
862 | /* | |
863 | * Either remove the duplicate refcount from | |
864 | * isolate_lru_page() or drop the page ref if it was | |
865 | * not isolated. | |
866 | */ | |
867 | put_page(page); | |
868 | set_status: | |
869 | pp->status = err; | |
870 | } | |
871 | ||
872 | if (!list_empty(&pagelist)) | |
873 | err = migrate_pages(&pagelist, new_page_node, | |
874 | (unsigned long)pm); | |
875 | else | |
876 | err = -ENOENT; | |
877 | ||
878 | up_read(&mm->mmap_sem); | |
879 | return err; | |
880 | } | |
881 | ||
882 | /* | |
883 | * Determine the nodes of a list of pages. The addr in the pm array | |
884 | * must have been set to the virtual address of which we want to determine | |
885 | * the node number. | |
886 | */ | |
887 | static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm) | |
888 | { | |
889 | down_read(&mm->mmap_sem); | |
890 | ||
891 | for ( ; pm->node != MAX_NUMNODES; pm++) { | |
892 | struct vm_area_struct *vma; | |
893 | struct page *page; | |
894 | int err; | |
895 | ||
896 | err = -EFAULT; | |
897 | vma = find_vma(mm, pm->addr); | |
898 | if (!vma) | |
899 | goto set_status; | |
900 | ||
901 | page = follow_page(vma, pm->addr, 0); | |
902 | err = -ENOENT; | |
903 | /* Use PageReserved to check for zero page */ | |
904 | if (!page || PageReserved(page)) | |
905 | goto set_status; | |
906 | ||
907 | err = page_to_nid(page); | |
908 | set_status: | |
909 | pm->status = err; | |
910 | } | |
911 | ||
912 | up_read(&mm->mmap_sem); | |
913 | return 0; | |
914 | } | |
915 | ||
916 | /* | |
917 | * Move a list of pages in the address space of the currently executing | |
918 | * process. | |
919 | */ | |
920 | asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages, | |
921 | const void __user * __user *pages, | |
922 | const int __user *nodes, | |
923 | int __user *status, int flags) | |
924 | { | |
925 | int err = 0; | |
926 | int i; | |
927 | struct task_struct *task; | |
928 | nodemask_t task_nodes; | |
929 | struct mm_struct *mm; | |
930 | struct page_to_node *pm = NULL; | |
931 | ||
932 | /* Check flags */ | |
933 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
934 | return -EINVAL; | |
935 | ||
936 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
937 | return -EPERM; | |
938 | ||
939 | /* Find the mm_struct */ | |
940 | read_lock(&tasklist_lock); | |
228ebcbe | 941 | task = pid ? find_task_by_vpid(pid) : current; |
742755a1 CL |
942 | if (!task) { |
943 | read_unlock(&tasklist_lock); | |
944 | return -ESRCH; | |
945 | } | |
946 | mm = get_task_mm(task); | |
947 | read_unlock(&tasklist_lock); | |
948 | ||
949 | if (!mm) | |
950 | return -EINVAL; | |
951 | ||
952 | /* | |
953 | * Check if this process has the right to modify the specified | |
954 | * process. The right exists if the process has administrative | |
955 | * capabilities, superuser privileges or the same | |
956 | * userid as the target process. | |
957 | */ | |
958 | if ((current->euid != task->suid) && (current->euid != task->uid) && | |
959 | (current->uid != task->suid) && (current->uid != task->uid) && | |
960 | !capable(CAP_SYS_NICE)) { | |
961 | err = -EPERM; | |
962 | goto out2; | |
963 | } | |
964 | ||
86c3a764 DQ |
965 | err = security_task_movememory(task); |
966 | if (err) | |
967 | goto out2; | |
968 | ||
969 | ||
742755a1 CL |
970 | task_nodes = cpuset_mems_allowed(task); |
971 | ||
972 | /* Limit nr_pages so that the multiplication may not overflow */ | |
973 | if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) { | |
974 | err = -E2BIG; | |
975 | goto out2; | |
976 | } | |
977 | ||
978 | pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node)); | |
979 | if (!pm) { | |
980 | err = -ENOMEM; | |
981 | goto out2; | |
982 | } | |
983 | ||
984 | /* | |
985 | * Get parameters from user space and initialize the pm | |
986 | * array. Return various errors if the user did something wrong. | |
987 | */ | |
988 | for (i = 0; i < nr_pages; i++) { | |
9d966d49 | 989 | const void __user *p; |
742755a1 CL |
990 | |
991 | err = -EFAULT; | |
992 | if (get_user(p, pages + i)) | |
993 | goto out; | |
994 | ||
995 | pm[i].addr = (unsigned long)p; | |
996 | if (nodes) { | |
997 | int node; | |
998 | ||
999 | if (get_user(node, nodes + i)) | |
1000 | goto out; | |
1001 | ||
1002 | err = -ENODEV; | |
56bbd65d | 1003 | if (!node_state(node, N_HIGH_MEMORY)) |
742755a1 CL |
1004 | goto out; |
1005 | ||
1006 | err = -EACCES; | |
1007 | if (!node_isset(node, task_nodes)) | |
1008 | goto out; | |
1009 | ||
1010 | pm[i].node = node; | |
8ce08464 SR |
1011 | } else |
1012 | pm[i].node = 0; /* anything to not match MAX_NUMNODES */ | |
742755a1 CL |
1013 | } |
1014 | /* End marker */ | |
1015 | pm[nr_pages].node = MAX_NUMNODES; | |
1016 | ||
1017 | if (nodes) | |
1018 | err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL); | |
1019 | else | |
1020 | err = do_pages_stat(mm, pm); | |
1021 | ||
1022 | if (err >= 0) | |
1023 | /* Return status information */ | |
1024 | for (i = 0; i < nr_pages; i++) | |
1025 | if (put_user(pm[i].status, status + i)) | |
1026 | err = -EFAULT; | |
1027 | ||
1028 | out: | |
1029 | vfree(pm); | |
1030 | out2: | |
1031 | mmput(mm); | |
1032 | return err; | |
1033 | } | |
1034 | #endif | |
1035 | ||
7b2259b3 CL |
1036 | /* |
1037 | * Call migration functions in the vma_ops that may prepare | |
1038 | * memory in a vm for migration. migration functions may perform | |
1039 | * the migration for vmas that do not have an underlying page struct. | |
1040 | */ | |
1041 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1042 | const nodemask_t *from, unsigned long flags) | |
1043 | { | |
1044 | struct vm_area_struct *vma; | |
1045 | int err = 0; | |
1046 | ||
1047 | for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) { | |
1048 | if (vma->vm_ops && vma->vm_ops->migrate) { | |
1049 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1050 | if (err) | |
1051 | break; | |
1052 | } | |
1053 | } | |
1054 | return err; | |
1055 | } |