Commit | Line | Data |
---|---|---|
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> | |
cde53535 | 12 | * Christoph Lameter |
b20a3503 CL |
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> |
8a9f3ccd | 32 | #include <linux/memcontrol.h> |
4f5ca265 | 33 | #include <linux/syscalls.h> |
b20a3503 CL |
34 | |
35 | #include "internal.h" | |
36 | ||
b20a3503 CL |
37 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
38 | ||
b20a3503 | 39 | /* |
742755a1 CL |
40 | * migrate_prep() needs to be called before we start compiling a list of pages |
41 | * to be migrated using isolate_lru_page(). | |
b20a3503 CL |
42 | */ |
43 | int migrate_prep(void) | |
44 | { | |
b20a3503 CL |
45 | /* |
46 | * Clear the LRU lists so pages can be isolated. | |
47 | * Note that pages may be moved off the LRU after we have | |
48 | * drained them. Those pages will fail to migrate like other | |
49 | * pages that may be busy. | |
50 | */ | |
51 | lru_add_drain_all(); | |
52 | ||
53 | return 0; | |
54 | } | |
55 | ||
b20a3503 | 56 | /* |
894bc310 LS |
57 | * Add isolated pages on the list back to the LRU under page lock |
58 | * to avoid leaking evictable pages back onto unevictable list. | |
b20a3503 CL |
59 | * |
60 | * returns the number of pages put back. | |
61 | */ | |
62 | int putback_lru_pages(struct list_head *l) | |
63 | { | |
64 | struct page *page; | |
65 | struct page *page2; | |
66 | int count = 0; | |
67 | ||
68 | list_for_each_entry_safe(page, page2, l, lru) { | |
e24f0b8f | 69 | list_del(&page->lru); |
894bc310 | 70 | putback_lru_page(page); |
b20a3503 CL |
71 | count++; |
72 | } | |
73 | return count; | |
74 | } | |
75 | ||
0697212a CL |
76 | /* |
77 | * Restore a potential migration pte to a working pte entry | |
78 | */ | |
04e62a29 | 79 | static void remove_migration_pte(struct vm_area_struct *vma, |
0697212a CL |
80 | struct page *old, struct page *new) |
81 | { | |
82 | struct mm_struct *mm = vma->vm_mm; | |
83 | swp_entry_t entry; | |
84 | pgd_t *pgd; | |
85 | pud_t *pud; | |
86 | pmd_t *pmd; | |
87 | pte_t *ptep, pte; | |
88 | spinlock_t *ptl; | |
04e62a29 CL |
89 | unsigned long addr = page_address_in_vma(new, vma); |
90 | ||
91 | if (addr == -EFAULT) | |
92 | return; | |
0697212a CL |
93 | |
94 | pgd = pgd_offset(mm, addr); | |
95 | if (!pgd_present(*pgd)) | |
96 | return; | |
97 | ||
98 | pud = pud_offset(pgd, addr); | |
99 | if (!pud_present(*pud)) | |
100 | return; | |
101 | ||
102 | pmd = pmd_offset(pud, addr); | |
103 | if (!pmd_present(*pmd)) | |
104 | return; | |
105 | ||
106 | ptep = pte_offset_map(pmd, addr); | |
107 | ||
108 | if (!is_swap_pte(*ptep)) { | |
109 | pte_unmap(ptep); | |
110 | return; | |
111 | } | |
112 | ||
113 | ptl = pte_lockptr(mm, pmd); | |
114 | spin_lock(ptl); | |
115 | pte = *ptep; | |
116 | if (!is_swap_pte(pte)) | |
117 | goto out; | |
118 | ||
119 | entry = pte_to_swp_entry(pte); | |
120 | ||
121 | if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) | |
122 | goto out; | |
123 | ||
0697212a CL |
124 | get_page(new); |
125 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); | |
126 | if (is_write_migration_entry(entry)) | |
127 | pte = pte_mkwrite(pte); | |
97ee0524 | 128 | flush_cache_page(vma, addr, pte_pfn(pte)); |
0697212a | 129 | set_pte_at(mm, addr, ptep, pte); |
04e62a29 CL |
130 | |
131 | if (PageAnon(new)) | |
132 | page_add_anon_rmap(new, vma, addr); | |
133 | else | |
134 | page_add_file_rmap(new); | |
135 | ||
136 | /* No need to invalidate - it was non-present before */ | |
137 | update_mmu_cache(vma, addr, pte); | |
04e62a29 | 138 | |
0697212a CL |
139 | out: |
140 | pte_unmap_unlock(ptep, ptl); | |
141 | } | |
142 | ||
143 | /* | |
04e62a29 CL |
144 | * Note that remove_file_migration_ptes will only work on regular mappings, |
145 | * Nonlinear mappings do not use migration entries. | |
146 | */ | |
147 | static void remove_file_migration_ptes(struct page *old, struct page *new) | |
148 | { | |
149 | struct vm_area_struct *vma; | |
150 | struct address_space *mapping = page_mapping(new); | |
151 | struct prio_tree_iter iter; | |
152 | pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
153 | ||
154 | if (!mapping) | |
155 | return; | |
156 | ||
157 | spin_lock(&mapping->i_mmap_lock); | |
158 | ||
159 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) | |
160 | remove_migration_pte(vma, old, new); | |
161 | ||
162 | spin_unlock(&mapping->i_mmap_lock); | |
163 | } | |
164 | ||
165 | /* | |
0697212a CL |
166 | * Must hold mmap_sem lock on at least one of the vmas containing |
167 | * the page so that the anon_vma cannot vanish. | |
168 | */ | |
04e62a29 | 169 | static void remove_anon_migration_ptes(struct page *old, struct page *new) |
0697212a CL |
170 | { |
171 | struct anon_vma *anon_vma; | |
172 | struct vm_area_struct *vma; | |
173 | unsigned long mapping; | |
174 | ||
175 | mapping = (unsigned long)new->mapping; | |
176 | ||
177 | if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) | |
178 | return; | |
179 | ||
180 | /* | |
181 | * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. | |
182 | */ | |
183 | anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); | |
184 | spin_lock(&anon_vma->lock); | |
185 | ||
186 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) | |
04e62a29 | 187 | remove_migration_pte(vma, old, new); |
0697212a CL |
188 | |
189 | spin_unlock(&anon_vma->lock); | |
190 | } | |
191 | ||
04e62a29 CL |
192 | /* |
193 | * Get rid of all migration entries and replace them by | |
194 | * references to the indicated page. | |
195 | */ | |
196 | static void remove_migration_ptes(struct page *old, struct page *new) | |
197 | { | |
198 | if (PageAnon(new)) | |
199 | remove_anon_migration_ptes(old, new); | |
200 | else | |
201 | remove_file_migration_ptes(old, new); | |
202 | } | |
203 | ||
0697212a CL |
204 | /* |
205 | * Something used the pte of a page under migration. We need to | |
206 | * get to the page and wait until migration is finished. | |
207 | * When we return from this function the fault will be retried. | |
208 | * | |
209 | * This function is called from do_swap_page(). | |
210 | */ | |
211 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
212 | unsigned long address) | |
213 | { | |
214 | pte_t *ptep, pte; | |
215 | spinlock_t *ptl; | |
216 | swp_entry_t entry; | |
217 | struct page *page; | |
218 | ||
219 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
220 | pte = *ptep; | |
221 | if (!is_swap_pte(pte)) | |
222 | goto out; | |
223 | ||
224 | entry = pte_to_swp_entry(pte); | |
225 | if (!is_migration_entry(entry)) | |
226 | goto out; | |
227 | ||
228 | page = migration_entry_to_page(entry); | |
229 | ||
e286781d NP |
230 | /* |
231 | * Once radix-tree replacement of page migration started, page_count | |
232 | * *must* be zero. And, we don't want to call wait_on_page_locked() | |
233 | * against a page without get_page(). | |
234 | * So, we use get_page_unless_zero(), here. Even failed, page fault | |
235 | * will occur again. | |
236 | */ | |
237 | if (!get_page_unless_zero(page)) | |
238 | goto out; | |
0697212a CL |
239 | pte_unmap_unlock(ptep, ptl); |
240 | wait_on_page_locked(page); | |
241 | put_page(page); | |
242 | return; | |
243 | out: | |
244 | pte_unmap_unlock(ptep, ptl); | |
245 | } | |
246 | ||
b20a3503 | 247 | /* |
c3fcf8a5 | 248 | * Replace the page in the mapping. |
5b5c7120 CL |
249 | * |
250 | * The number of remaining references must be: | |
251 | * 1 for anonymous pages without a mapping | |
252 | * 2 for pages with a mapping | |
266cf658 | 253 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. |
b20a3503 | 254 | */ |
2d1db3b1 CL |
255 | static int migrate_page_move_mapping(struct address_space *mapping, |
256 | struct page *newpage, struct page *page) | |
b20a3503 | 257 | { |
e286781d | 258 | int expected_count; |
7cf9c2c7 | 259 | void **pslot; |
b20a3503 | 260 | |
6c5240ae | 261 | if (!mapping) { |
0e8c7d0f | 262 | /* Anonymous page without mapping */ |
6c5240ae CL |
263 | if (page_count(page) != 1) |
264 | return -EAGAIN; | |
265 | return 0; | |
266 | } | |
267 | ||
19fd6231 | 268 | spin_lock_irq(&mapping->tree_lock); |
b20a3503 | 269 | |
7cf9c2c7 NP |
270 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
271 | page_index(page)); | |
b20a3503 | 272 | |
266cf658 | 273 | expected_count = 2 + !!page_has_private(page); |
e286781d | 274 | if (page_count(page) != expected_count || |
7cf9c2c7 | 275 | (struct page *)radix_tree_deref_slot(pslot) != page) { |
19fd6231 | 276 | spin_unlock_irq(&mapping->tree_lock); |
e23ca00b | 277 | return -EAGAIN; |
b20a3503 CL |
278 | } |
279 | ||
e286781d | 280 | if (!page_freeze_refs(page, expected_count)) { |
19fd6231 | 281 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
282 | return -EAGAIN; |
283 | } | |
284 | ||
b20a3503 CL |
285 | /* |
286 | * Now we know that no one else is looking at the page. | |
b20a3503 | 287 | */ |
7cf9c2c7 | 288 | get_page(newpage); /* add cache reference */ |
b20a3503 CL |
289 | if (PageSwapCache(page)) { |
290 | SetPageSwapCache(newpage); | |
291 | set_page_private(newpage, page_private(page)); | |
292 | } | |
293 | ||
7cf9c2c7 NP |
294 | radix_tree_replace_slot(pslot, newpage); |
295 | ||
e286781d | 296 | page_unfreeze_refs(page, expected_count); |
7cf9c2c7 NP |
297 | /* |
298 | * Drop cache reference from old page. | |
299 | * We know this isn't the last reference. | |
300 | */ | |
b20a3503 | 301 | __put_page(page); |
7cf9c2c7 | 302 | |
0e8c7d0f CL |
303 | /* |
304 | * If moved to a different zone then also account | |
305 | * the page for that zone. Other VM counters will be | |
306 | * taken care of when we establish references to the | |
307 | * new page and drop references to the old page. | |
308 | * | |
309 | * Note that anonymous pages are accounted for | |
310 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
311 | * are mapped to swap space. | |
312 | */ | |
313 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
314 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
315 | ||
19fd6231 | 316 | spin_unlock_irq(&mapping->tree_lock); |
b20a3503 CL |
317 | |
318 | return 0; | |
319 | } | |
b20a3503 CL |
320 | |
321 | /* | |
322 | * Copy the page to its new location | |
323 | */ | |
e7340f73 | 324 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 | 325 | { |
b7abea96 KH |
326 | int anon; |
327 | ||
b20a3503 CL |
328 | copy_highpage(newpage, page); |
329 | ||
330 | if (PageError(page)) | |
331 | SetPageError(newpage); | |
332 | if (PageReferenced(page)) | |
333 | SetPageReferenced(newpage); | |
334 | if (PageUptodate(page)) | |
335 | SetPageUptodate(newpage); | |
894bc310 LS |
336 | if (TestClearPageActive(page)) { |
337 | VM_BUG_ON(PageUnevictable(page)); | |
b20a3503 | 338 | SetPageActive(newpage); |
894bc310 LS |
339 | } else |
340 | unevictable_migrate_page(newpage, page); | |
b20a3503 CL |
341 | if (PageChecked(page)) |
342 | SetPageChecked(newpage); | |
343 | if (PageMappedToDisk(page)) | |
344 | SetPageMappedToDisk(newpage); | |
345 | ||
346 | if (PageDirty(page)) { | |
347 | clear_page_dirty_for_io(page); | |
3a902c5f NP |
348 | /* |
349 | * Want to mark the page and the radix tree as dirty, and | |
350 | * redo the accounting that clear_page_dirty_for_io undid, | |
351 | * but we can't use set_page_dirty because that function | |
352 | * is actually a signal that all of the page has become dirty. | |
353 | * Wheras only part of our page may be dirty. | |
354 | */ | |
355 | __set_page_dirty_nobuffers(newpage); | |
b20a3503 CL |
356 | } |
357 | ||
b291f000 NP |
358 | mlock_migrate_page(newpage, page); |
359 | ||
b20a3503 | 360 | ClearPageSwapCache(page); |
b20a3503 CL |
361 | ClearPagePrivate(page); |
362 | set_page_private(page, 0); | |
b7abea96 KH |
363 | /* page->mapping contains a flag for PageAnon() */ |
364 | anon = PageAnon(page); | |
b20a3503 CL |
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 | |
266cf658 | 389 | * pages that do not use PagePrivate/PagePrivate2. |
b20a3503 CL |
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); | |
b20a3503 CL |
406 | return 0; |
407 | } | |
408 | EXPORT_SYMBOL(migrate_page); | |
409 | ||
9361401e | 410 | #ifdef CONFIG_BLOCK |
1d8b85cc CL |
411 | /* |
412 | * Migration function for pages with buffers. This function can only be used | |
413 | * if the underlying filesystem guarantees that no other references to "page" | |
414 | * exist. | |
415 | */ | |
2d1db3b1 CL |
416 | int buffer_migrate_page(struct address_space *mapping, |
417 | struct page *newpage, struct page *page) | |
1d8b85cc | 418 | { |
1d8b85cc CL |
419 | struct buffer_head *bh, *head; |
420 | int rc; | |
421 | ||
1d8b85cc | 422 | if (!page_has_buffers(page)) |
2d1db3b1 | 423 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
424 | |
425 | head = page_buffers(page); | |
426 | ||
2d1db3b1 | 427 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
428 | |
429 | if (rc) | |
430 | return rc; | |
431 | ||
432 | bh = head; | |
433 | do { | |
434 | get_bh(bh); | |
435 | lock_buffer(bh); | |
436 | bh = bh->b_this_page; | |
437 | ||
438 | } while (bh != head); | |
439 | ||
440 | ClearPagePrivate(page); | |
441 | set_page_private(newpage, page_private(page)); | |
442 | set_page_private(page, 0); | |
443 | put_page(page); | |
444 | get_page(newpage); | |
445 | ||
446 | bh = head; | |
447 | do { | |
448 | set_bh_page(bh, newpage, bh_offset(bh)); | |
449 | bh = bh->b_this_page; | |
450 | ||
451 | } while (bh != head); | |
452 | ||
453 | SetPagePrivate(newpage); | |
454 | ||
455 | migrate_page_copy(newpage, page); | |
456 | ||
457 | bh = head; | |
458 | do { | |
459 | unlock_buffer(bh); | |
460 | put_bh(bh); | |
461 | bh = bh->b_this_page; | |
462 | ||
463 | } while (bh != head); | |
464 | ||
465 | return 0; | |
466 | } | |
467 | EXPORT_SYMBOL(buffer_migrate_page); | |
9361401e | 468 | #endif |
1d8b85cc | 469 | |
04e62a29 CL |
470 | /* |
471 | * Writeback a page to clean the dirty state | |
472 | */ | |
473 | static int writeout(struct address_space *mapping, struct page *page) | |
8351a6e4 | 474 | { |
04e62a29 CL |
475 | struct writeback_control wbc = { |
476 | .sync_mode = WB_SYNC_NONE, | |
477 | .nr_to_write = 1, | |
478 | .range_start = 0, | |
479 | .range_end = LLONG_MAX, | |
480 | .nonblocking = 1, | |
481 | .for_reclaim = 1 | |
482 | }; | |
483 | int rc; | |
484 | ||
485 | if (!mapping->a_ops->writepage) | |
486 | /* No write method for the address space */ | |
487 | return -EINVAL; | |
488 | ||
489 | if (!clear_page_dirty_for_io(page)) | |
490 | /* Someone else already triggered a write */ | |
491 | return -EAGAIN; | |
492 | ||
8351a6e4 | 493 | /* |
04e62a29 CL |
494 | * A dirty page may imply that the underlying filesystem has |
495 | * the page on some queue. So the page must be clean for | |
496 | * migration. Writeout may mean we loose the lock and the | |
497 | * page state is no longer what we checked for earlier. | |
498 | * At this point we know that the migration attempt cannot | |
499 | * be successful. | |
8351a6e4 | 500 | */ |
04e62a29 | 501 | remove_migration_ptes(page, page); |
8351a6e4 | 502 | |
04e62a29 | 503 | rc = mapping->a_ops->writepage(page, &wbc); |
8351a6e4 | 504 | |
04e62a29 CL |
505 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
506 | /* unlocked. Relock */ | |
507 | lock_page(page); | |
508 | ||
bda8550d | 509 | return (rc < 0) ? -EIO : -EAGAIN; |
04e62a29 CL |
510 | } |
511 | ||
512 | /* | |
513 | * Default handling if a filesystem does not provide a migration function. | |
514 | */ | |
515 | static int fallback_migrate_page(struct address_space *mapping, | |
516 | struct page *newpage, struct page *page) | |
517 | { | |
518 | if (PageDirty(page)) | |
519 | return writeout(mapping, page); | |
8351a6e4 CL |
520 | |
521 | /* | |
522 | * Buffers may be managed in a filesystem specific way. | |
523 | * We must have no buffers or drop them. | |
524 | */ | |
266cf658 | 525 | if (page_has_private(page) && |
8351a6e4 CL |
526 | !try_to_release_page(page, GFP_KERNEL)) |
527 | return -EAGAIN; | |
528 | ||
529 | return migrate_page(mapping, newpage, page); | |
530 | } | |
531 | ||
e24f0b8f CL |
532 | /* |
533 | * Move a page to a newly allocated page | |
534 | * The page is locked and all ptes have been successfully removed. | |
535 | * | |
536 | * The new page will have replaced the old page if this function | |
537 | * is successful. | |
894bc310 LS |
538 | * |
539 | * Return value: | |
540 | * < 0 - error code | |
541 | * == 0 - success | |
e24f0b8f CL |
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 | */ | |
529ae9aa | 553 | if (!trylock_page(newpage)) |
e24f0b8f CL |
554 | BUG(); |
555 | ||
556 | /* Prepare mapping for the new page.*/ | |
557 | newpage->index = page->index; | |
558 | newpage->mapping = page->mapping; | |
b2e18538 RR |
559 | if (PageSwapBacked(page)) |
560 | SetPageSwapBacked(newpage); | |
e24f0b8f CL |
561 | |
562 | mapping = page_mapping(page); | |
563 | if (!mapping) | |
564 | rc = migrate_page(mapping, newpage, page); | |
565 | else if (mapping->a_ops->migratepage) | |
566 | /* | |
567 | * Most pages have a mapping and most filesystems | |
568 | * should provide a migration function. Anonymous | |
569 | * pages are part of swap space which also has its | |
570 | * own migration function. This is the most common | |
571 | * path for page migration. | |
572 | */ | |
573 | rc = mapping->a_ops->migratepage(mapping, | |
574 | newpage, page); | |
575 | else | |
576 | rc = fallback_migrate_page(mapping, newpage, page); | |
577 | ||
ae41be37 | 578 | if (!rc) { |
e24f0b8f | 579 | remove_migration_ptes(page, newpage); |
ae41be37 | 580 | } else |
e24f0b8f CL |
581 | newpage->mapping = NULL; |
582 | ||
583 | unlock_page(newpage); | |
584 | ||
585 | return rc; | |
586 | } | |
587 | ||
588 | /* | |
589 | * Obtain the lock on page, remove all ptes and migrate the page | |
590 | * to the newly allocated page in newpage. | |
591 | */ | |
95a402c3 CL |
592 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
593 | struct page *page, int force) | |
e24f0b8f CL |
594 | { |
595 | int rc = 0; | |
742755a1 CL |
596 | int *result = NULL; |
597 | struct page *newpage = get_new_page(page, private, &result); | |
989f89c5 | 598 | int rcu_locked = 0; |
ae41be37 | 599 | int charge = 0; |
01b1ae63 | 600 | struct mem_cgroup *mem; |
95a402c3 CL |
601 | |
602 | if (!newpage) | |
603 | return -ENOMEM; | |
e24f0b8f | 604 | |
894bc310 | 605 | if (page_count(page) == 1) { |
e24f0b8f | 606 | /* page was freed from under us. So we are done. */ |
95a402c3 | 607 | goto move_newpage; |
894bc310 | 608 | } |
e24f0b8f | 609 | |
e8589cc1 | 610 | /* prepare cgroup just returns 0 or -ENOMEM */ |
e24f0b8f | 611 | rc = -EAGAIN; |
01b1ae63 | 612 | |
529ae9aa | 613 | if (!trylock_page(page)) { |
e24f0b8f | 614 | if (!force) |
95a402c3 | 615 | goto move_newpage; |
e24f0b8f CL |
616 | lock_page(page); |
617 | } | |
618 | ||
01b1ae63 KH |
619 | /* charge against new page */ |
620 | charge = mem_cgroup_prepare_migration(page, &mem); | |
621 | if (charge == -ENOMEM) { | |
622 | rc = -ENOMEM; | |
623 | goto unlock; | |
624 | } | |
625 | BUG_ON(charge); | |
626 | ||
e24f0b8f CL |
627 | if (PageWriteback(page)) { |
628 | if (!force) | |
01b1ae63 | 629 | goto uncharge; |
e24f0b8f CL |
630 | wait_on_page_writeback(page); |
631 | } | |
e24f0b8f | 632 | /* |
dc386d4d KH |
633 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
634 | * we cannot notice that anon_vma is freed while we migrates a page. | |
635 | * This rcu_read_lock() delays freeing anon_vma pointer until the end | |
636 | * of migration. File cache pages are no problem because of page_lock() | |
989f89c5 KH |
637 | * File Caches may use write_page() or lock_page() in migration, then, |
638 | * just care Anon page here. | |
dc386d4d | 639 | */ |
989f89c5 KH |
640 | if (PageAnon(page)) { |
641 | rcu_read_lock(); | |
642 | rcu_locked = 1; | |
643 | } | |
62e1c553 | 644 | |
dc386d4d | 645 | /* |
62e1c553 SL |
646 | * Corner case handling: |
647 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
648 | * and treated as swapcache but it has no rmap yet. | |
649 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
650 | * trigger a BUG. So handle it here. | |
651 | * 2. An orphaned page (see truncate_complete_page) might have | |
652 | * fs-private metadata. The page can be picked up due to memory | |
653 | * offlining. Everywhere else except page reclaim, the page is | |
654 | * invisible to the vm, so the page can not be migrated. So try to | |
655 | * free the metadata, so the page can be freed. | |
e24f0b8f | 656 | */ |
62e1c553 | 657 | if (!page->mapping) { |
266cf658 | 658 | if (!PageAnon(page) && page_has_private(page)) { |
62e1c553 SL |
659 | /* |
660 | * Go direct to try_to_free_buffers() here because | |
661 | * a) that's what try_to_release_page() would do anyway | |
662 | * b) we may be under rcu_read_lock() here, so we can't | |
663 | * use GFP_KERNEL which is what try_to_release_page() | |
664 | * needs to be effective. | |
665 | */ | |
666 | try_to_free_buffers(page); | |
667 | } | |
dc386d4d | 668 | goto rcu_unlock; |
62e1c553 SL |
669 | } |
670 | ||
dc386d4d | 671 | /* Establish migration ptes or remove ptes */ |
e6a1530d | 672 | try_to_unmap(page, 1); |
dc386d4d | 673 | |
e6a1530d CL |
674 | if (!page_mapped(page)) |
675 | rc = move_to_new_page(newpage, page); | |
e24f0b8f | 676 | |
e8589cc1 | 677 | if (rc) |
e24f0b8f | 678 | remove_migration_ptes(page, page); |
dc386d4d | 679 | rcu_unlock: |
989f89c5 KH |
680 | if (rcu_locked) |
681 | rcu_read_unlock(); | |
01b1ae63 KH |
682 | uncharge: |
683 | if (!charge) | |
684 | mem_cgroup_end_migration(mem, page, newpage); | |
e24f0b8f CL |
685 | unlock: |
686 | unlock_page(page); | |
95a402c3 | 687 | |
e24f0b8f | 688 | if (rc != -EAGAIN) { |
aaa994b3 CL |
689 | /* |
690 | * A page that has been migrated has all references | |
691 | * removed and will be freed. A page that has not been | |
692 | * migrated will have kepts its references and be | |
693 | * restored. | |
694 | */ | |
695 | list_del(&page->lru); | |
894bc310 | 696 | putback_lru_page(page); |
e24f0b8f | 697 | } |
95a402c3 CL |
698 | |
699 | move_newpage: | |
894bc310 | 700 | |
95a402c3 CL |
701 | /* |
702 | * Move the new page to the LRU. If migration was not successful | |
703 | * then this will free the page. | |
704 | */ | |
894bc310 LS |
705 | putback_lru_page(newpage); |
706 | ||
742755a1 CL |
707 | if (result) { |
708 | if (rc) | |
709 | *result = rc; | |
710 | else | |
711 | *result = page_to_nid(newpage); | |
712 | } | |
e24f0b8f CL |
713 | return rc; |
714 | } | |
715 | ||
b20a3503 CL |
716 | /* |
717 | * migrate_pages | |
718 | * | |
95a402c3 CL |
719 | * The function takes one list of pages to migrate and a function |
720 | * that determines from the page to be migrated and the private data | |
721 | * the target of the move and allocates the page. | |
b20a3503 CL |
722 | * |
723 | * The function returns after 10 attempts or if no pages | |
724 | * are movable anymore because to has become empty | |
aaa994b3 | 725 | * or no retryable pages exist anymore. All pages will be |
e9534b3f | 726 | * returned to the LRU or freed. |
b20a3503 | 727 | * |
95a402c3 | 728 | * Return: Number of pages not migrated or error code. |
b20a3503 | 729 | */ |
95a402c3 CL |
730 | int migrate_pages(struct list_head *from, |
731 | new_page_t get_new_page, unsigned long private) | |
b20a3503 | 732 | { |
e24f0b8f | 733 | int retry = 1; |
b20a3503 CL |
734 | int nr_failed = 0; |
735 | int pass = 0; | |
736 | struct page *page; | |
737 | struct page *page2; | |
738 | int swapwrite = current->flags & PF_SWAPWRITE; | |
739 | int rc; | |
740 | ||
741 | if (!swapwrite) | |
742 | current->flags |= PF_SWAPWRITE; | |
743 | ||
e24f0b8f CL |
744 | for(pass = 0; pass < 10 && retry; pass++) { |
745 | retry = 0; | |
b20a3503 | 746 | |
e24f0b8f | 747 | list_for_each_entry_safe(page, page2, from, lru) { |
e24f0b8f | 748 | cond_resched(); |
2d1db3b1 | 749 | |
95a402c3 CL |
750 | rc = unmap_and_move(get_new_page, private, |
751 | page, pass > 2); | |
2d1db3b1 | 752 | |
e24f0b8f | 753 | switch(rc) { |
95a402c3 CL |
754 | case -ENOMEM: |
755 | goto out; | |
e24f0b8f | 756 | case -EAGAIN: |
2d1db3b1 | 757 | retry++; |
e24f0b8f CL |
758 | break; |
759 | case 0: | |
e24f0b8f CL |
760 | break; |
761 | default: | |
2d1db3b1 | 762 | /* Permanent failure */ |
2d1db3b1 | 763 | nr_failed++; |
e24f0b8f | 764 | break; |
2d1db3b1 | 765 | } |
b20a3503 CL |
766 | } |
767 | } | |
95a402c3 CL |
768 | rc = 0; |
769 | out: | |
b20a3503 CL |
770 | if (!swapwrite) |
771 | current->flags &= ~PF_SWAPWRITE; | |
772 | ||
aaa994b3 | 773 | putback_lru_pages(from); |
b20a3503 | 774 | |
95a402c3 CL |
775 | if (rc) |
776 | return rc; | |
b20a3503 | 777 | |
95a402c3 | 778 | return nr_failed + retry; |
b20a3503 | 779 | } |
95a402c3 | 780 | |
742755a1 CL |
781 | #ifdef CONFIG_NUMA |
782 | /* | |
783 | * Move a list of individual pages | |
784 | */ | |
785 | struct page_to_node { | |
786 | unsigned long addr; | |
787 | struct page *page; | |
788 | int node; | |
789 | int status; | |
790 | }; | |
791 | ||
792 | static struct page *new_page_node(struct page *p, unsigned long private, | |
793 | int **result) | |
794 | { | |
795 | struct page_to_node *pm = (struct page_to_node *)private; | |
796 | ||
797 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
798 | pm++; | |
799 | ||
800 | if (pm->node == MAX_NUMNODES) | |
801 | return NULL; | |
802 | ||
803 | *result = &pm->status; | |
804 | ||
6484eb3e | 805 | return alloc_pages_exact_node(pm->node, |
769848c0 | 806 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); |
742755a1 CL |
807 | } |
808 | ||
809 | /* | |
810 | * Move a set of pages as indicated in the pm array. The addr | |
811 | * field must be set to the virtual address of the page to be moved | |
812 | * and the node number must contain a valid target node. | |
5e9a0f02 | 813 | * The pm array ends with node = MAX_NUMNODES. |
742755a1 | 814 | */ |
5e9a0f02 BG |
815 | static int do_move_page_to_node_array(struct mm_struct *mm, |
816 | struct page_to_node *pm, | |
817 | int migrate_all) | |
742755a1 CL |
818 | { |
819 | int err; | |
820 | struct page_to_node *pp; | |
821 | LIST_HEAD(pagelist); | |
822 | ||
823 | down_read(&mm->mmap_sem); | |
824 | ||
825 | /* | |
826 | * Build a list of pages to migrate | |
827 | */ | |
742755a1 CL |
828 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
829 | struct vm_area_struct *vma; | |
830 | struct page *page; | |
831 | ||
742755a1 CL |
832 | err = -EFAULT; |
833 | vma = find_vma(mm, pp->addr); | |
0dc952dc | 834 | if (!vma || !vma_migratable(vma)) |
742755a1 CL |
835 | goto set_status; |
836 | ||
837 | page = follow_page(vma, pp->addr, FOLL_GET); | |
89f5b7da LT |
838 | |
839 | err = PTR_ERR(page); | |
840 | if (IS_ERR(page)) | |
841 | goto set_status; | |
842 | ||
742755a1 CL |
843 | err = -ENOENT; |
844 | if (!page) | |
845 | goto set_status; | |
846 | ||
847 | if (PageReserved(page)) /* Check for zero page */ | |
848 | goto put_and_set; | |
849 | ||
850 | pp->page = page; | |
851 | err = page_to_nid(page); | |
852 | ||
853 | if (err == pp->node) | |
854 | /* | |
855 | * Node already in the right place | |
856 | */ | |
857 | goto put_and_set; | |
858 | ||
859 | err = -EACCES; | |
860 | if (page_mapcount(page) > 1 && | |
861 | !migrate_all) | |
862 | goto put_and_set; | |
863 | ||
62695a84 NP |
864 | err = isolate_lru_page(page); |
865 | if (!err) | |
866 | list_add_tail(&page->lru, &pagelist); | |
742755a1 CL |
867 | put_and_set: |
868 | /* | |
869 | * Either remove the duplicate refcount from | |
870 | * isolate_lru_page() or drop the page ref if it was | |
871 | * not isolated. | |
872 | */ | |
873 | put_page(page); | |
874 | set_status: | |
875 | pp->status = err; | |
876 | } | |
877 | ||
e78bbfa8 | 878 | err = 0; |
742755a1 CL |
879 | if (!list_empty(&pagelist)) |
880 | err = migrate_pages(&pagelist, new_page_node, | |
881 | (unsigned long)pm); | |
742755a1 CL |
882 | |
883 | up_read(&mm->mmap_sem); | |
884 | return err; | |
885 | } | |
886 | ||
5e9a0f02 BG |
887 | /* |
888 | * Migrate an array of page address onto an array of nodes and fill | |
889 | * the corresponding array of status. | |
890 | */ | |
891 | static int do_pages_move(struct mm_struct *mm, struct task_struct *task, | |
892 | unsigned long nr_pages, | |
893 | const void __user * __user *pages, | |
894 | const int __user *nodes, | |
895 | int __user *status, int flags) | |
896 | { | |
3140a227 | 897 | struct page_to_node *pm; |
5e9a0f02 | 898 | nodemask_t task_nodes; |
3140a227 BG |
899 | unsigned long chunk_nr_pages; |
900 | unsigned long chunk_start; | |
901 | int err; | |
5e9a0f02 BG |
902 | |
903 | task_nodes = cpuset_mems_allowed(task); | |
904 | ||
3140a227 BG |
905 | err = -ENOMEM; |
906 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); | |
907 | if (!pm) | |
5e9a0f02 | 908 | goto out; |
35282a2d BG |
909 | |
910 | migrate_prep(); | |
911 | ||
5e9a0f02 | 912 | /* |
3140a227 BG |
913 | * Store a chunk of page_to_node array in a page, |
914 | * but keep the last one as a marker | |
5e9a0f02 | 915 | */ |
3140a227 | 916 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
5e9a0f02 | 917 | |
3140a227 BG |
918 | for (chunk_start = 0; |
919 | chunk_start < nr_pages; | |
920 | chunk_start += chunk_nr_pages) { | |
921 | int j; | |
5e9a0f02 | 922 | |
3140a227 BG |
923 | if (chunk_start + chunk_nr_pages > nr_pages) |
924 | chunk_nr_pages = nr_pages - chunk_start; | |
925 | ||
926 | /* fill the chunk pm with addrs and nodes from user-space */ | |
927 | for (j = 0; j < chunk_nr_pages; j++) { | |
928 | const void __user *p; | |
5e9a0f02 BG |
929 | int node; |
930 | ||
3140a227 BG |
931 | err = -EFAULT; |
932 | if (get_user(p, pages + j + chunk_start)) | |
933 | goto out_pm; | |
934 | pm[j].addr = (unsigned long) p; | |
935 | ||
936 | if (get_user(node, nodes + j + chunk_start)) | |
5e9a0f02 BG |
937 | goto out_pm; |
938 | ||
939 | err = -ENODEV; | |
940 | if (!node_state(node, N_HIGH_MEMORY)) | |
941 | goto out_pm; | |
942 | ||
943 | err = -EACCES; | |
944 | if (!node_isset(node, task_nodes)) | |
945 | goto out_pm; | |
946 | ||
3140a227 BG |
947 | pm[j].node = node; |
948 | } | |
949 | ||
950 | /* End marker for this chunk */ | |
951 | pm[chunk_nr_pages].node = MAX_NUMNODES; | |
952 | ||
953 | /* Migrate this chunk */ | |
954 | err = do_move_page_to_node_array(mm, pm, | |
955 | flags & MPOL_MF_MOVE_ALL); | |
956 | if (err < 0) | |
957 | goto out_pm; | |
5e9a0f02 | 958 | |
5e9a0f02 | 959 | /* Return status information */ |
3140a227 BG |
960 | for (j = 0; j < chunk_nr_pages; j++) |
961 | if (put_user(pm[j].status, status + j + chunk_start)) { | |
5e9a0f02 | 962 | err = -EFAULT; |
3140a227 BG |
963 | goto out_pm; |
964 | } | |
965 | } | |
966 | err = 0; | |
5e9a0f02 BG |
967 | |
968 | out_pm: | |
3140a227 | 969 | free_page((unsigned long)pm); |
5e9a0f02 BG |
970 | out: |
971 | return err; | |
972 | } | |
973 | ||
742755a1 | 974 | /* |
2f007e74 | 975 | * Determine the nodes of an array of pages and store it in an array of status. |
742755a1 | 976 | */ |
80bba129 BG |
977 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, |
978 | const void __user **pages, int *status) | |
742755a1 | 979 | { |
2f007e74 | 980 | unsigned long i; |
2f007e74 | 981 | |
742755a1 CL |
982 | down_read(&mm->mmap_sem); |
983 | ||
2f007e74 | 984 | for (i = 0; i < nr_pages; i++) { |
80bba129 | 985 | unsigned long addr = (unsigned long)(*pages); |
742755a1 CL |
986 | struct vm_area_struct *vma; |
987 | struct page *page; | |
c095adbc | 988 | int err = -EFAULT; |
2f007e74 BG |
989 | |
990 | vma = find_vma(mm, addr); | |
742755a1 CL |
991 | if (!vma) |
992 | goto set_status; | |
993 | ||
2f007e74 | 994 | page = follow_page(vma, addr, 0); |
89f5b7da LT |
995 | |
996 | err = PTR_ERR(page); | |
997 | if (IS_ERR(page)) | |
998 | goto set_status; | |
999 | ||
742755a1 CL |
1000 | err = -ENOENT; |
1001 | /* Use PageReserved to check for zero page */ | |
1002 | if (!page || PageReserved(page)) | |
1003 | goto set_status; | |
1004 | ||
1005 | err = page_to_nid(page); | |
1006 | set_status: | |
80bba129 BG |
1007 | *status = err; |
1008 | ||
1009 | pages++; | |
1010 | status++; | |
1011 | } | |
1012 | ||
1013 | up_read(&mm->mmap_sem); | |
1014 | } | |
1015 | ||
1016 | /* | |
1017 | * Determine the nodes of a user array of pages and store it in | |
1018 | * a user array of status. | |
1019 | */ | |
1020 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, | |
1021 | const void __user * __user *pages, | |
1022 | int __user *status) | |
1023 | { | |
1024 | #define DO_PAGES_STAT_CHUNK_NR 16 | |
1025 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; | |
1026 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; | |
1027 | unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR; | |
1028 | int err; | |
1029 | ||
1030 | for (i = 0; i < nr_pages; i += chunk_nr) { | |
1031 | if (chunk_nr + i > nr_pages) | |
1032 | chunk_nr = nr_pages - i; | |
1033 | ||
1034 | err = copy_from_user(chunk_pages, &pages[i], | |
1035 | chunk_nr * sizeof(*chunk_pages)); | |
1036 | if (err) { | |
1037 | err = -EFAULT; | |
1038 | goto out; | |
1039 | } | |
1040 | ||
1041 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); | |
1042 | ||
1043 | err = copy_to_user(&status[i], chunk_status, | |
1044 | chunk_nr * sizeof(*chunk_status)); | |
1045 | if (err) { | |
1046 | err = -EFAULT; | |
1047 | goto out; | |
1048 | } | |
742755a1 | 1049 | } |
2f007e74 | 1050 | err = 0; |
742755a1 | 1051 | |
2f007e74 | 1052 | out: |
2f007e74 | 1053 | return err; |
742755a1 CL |
1054 | } |
1055 | ||
1056 | /* | |
1057 | * Move a list of pages in the address space of the currently executing | |
1058 | * process. | |
1059 | */ | |
938bb9f5 HC |
1060 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, |
1061 | const void __user * __user *, pages, | |
1062 | const int __user *, nodes, | |
1063 | int __user *, status, int, flags) | |
742755a1 | 1064 | { |
c69e8d9c | 1065 | const struct cred *cred = current_cred(), *tcred; |
742755a1 | 1066 | struct task_struct *task; |
742755a1 | 1067 | struct mm_struct *mm; |
5e9a0f02 | 1068 | int err; |
742755a1 CL |
1069 | |
1070 | /* Check flags */ | |
1071 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
1072 | return -EINVAL; | |
1073 | ||
1074 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
1075 | return -EPERM; | |
1076 | ||
1077 | /* Find the mm_struct */ | |
1078 | read_lock(&tasklist_lock); | |
228ebcbe | 1079 | task = pid ? find_task_by_vpid(pid) : current; |
742755a1 CL |
1080 | if (!task) { |
1081 | read_unlock(&tasklist_lock); | |
1082 | return -ESRCH; | |
1083 | } | |
1084 | mm = get_task_mm(task); | |
1085 | read_unlock(&tasklist_lock); | |
1086 | ||
1087 | if (!mm) | |
1088 | return -EINVAL; | |
1089 | ||
1090 | /* | |
1091 | * Check if this process has the right to modify the specified | |
1092 | * process. The right exists if the process has administrative | |
1093 | * capabilities, superuser privileges or the same | |
1094 | * userid as the target process. | |
1095 | */ | |
c69e8d9c DH |
1096 | rcu_read_lock(); |
1097 | tcred = __task_cred(task); | |
b6dff3ec DH |
1098 | if (cred->euid != tcred->suid && cred->euid != tcred->uid && |
1099 | cred->uid != tcred->suid && cred->uid != tcred->uid && | |
742755a1 | 1100 | !capable(CAP_SYS_NICE)) { |
c69e8d9c | 1101 | rcu_read_unlock(); |
742755a1 | 1102 | err = -EPERM; |
5e9a0f02 | 1103 | goto out; |
742755a1 | 1104 | } |
c69e8d9c | 1105 | rcu_read_unlock(); |
742755a1 | 1106 | |
86c3a764 DQ |
1107 | err = security_task_movememory(task); |
1108 | if (err) | |
5e9a0f02 | 1109 | goto out; |
86c3a764 | 1110 | |
5e9a0f02 BG |
1111 | if (nodes) { |
1112 | err = do_pages_move(mm, task, nr_pages, pages, nodes, status, | |
1113 | flags); | |
1114 | } else { | |
2f007e74 | 1115 | err = do_pages_stat(mm, nr_pages, pages, status); |
742755a1 CL |
1116 | } |
1117 | ||
742755a1 | 1118 | out: |
742755a1 CL |
1119 | mmput(mm); |
1120 | return err; | |
1121 | } | |
742755a1 | 1122 | |
7b2259b3 CL |
1123 | /* |
1124 | * Call migration functions in the vma_ops that may prepare | |
1125 | * memory in a vm for migration. migration functions may perform | |
1126 | * the migration for vmas that do not have an underlying page struct. | |
1127 | */ | |
1128 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1129 | const nodemask_t *from, unsigned long flags) | |
1130 | { | |
1131 | struct vm_area_struct *vma; | |
1132 | int err = 0; | |
1133 | ||
1001c9fb | 1134 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { |
7b2259b3 CL |
1135 | if (vma->vm_ops && vma->vm_ops->migrate) { |
1136 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1137 | if (err) | |
1138 | break; | |
1139 | } | |
1140 | } | |
1141 | return err; | |
1142 | } | |
83d1674a | 1143 | #endif |