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> | |
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 | 23 | #include <linux/pagevec.h> |
e9995ef9 | 24 | #include <linux/ksm.h> |
b20a3503 CL |
25 | #include <linux/rmap.h> |
26 | #include <linux/topology.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/cpuset.h> | |
04e62a29 | 29 | #include <linux/writeback.h> |
742755a1 CL |
30 | #include <linux/mempolicy.h> |
31 | #include <linux/vmalloc.h> | |
86c3a764 | 32 | #include <linux/security.h> |
8a9f3ccd | 33 | #include <linux/memcontrol.h> |
4f5ca265 | 34 | #include <linux/syscalls.h> |
b20a3503 CL |
35 | |
36 | #include "internal.h" | |
37 | ||
b20a3503 CL |
38 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
39 | ||
b20a3503 | 40 | /* |
742755a1 CL |
41 | * migrate_prep() needs to be called before we start compiling a list of pages |
42 | * to be migrated using isolate_lru_page(). | |
b20a3503 CL |
43 | */ |
44 | int migrate_prep(void) | |
45 | { | |
b20a3503 CL |
46 | /* |
47 | * Clear the LRU lists so pages can be isolated. | |
48 | * Note that pages may be moved off the LRU after we have | |
49 | * drained them. Those pages will fail to migrate like other | |
50 | * pages that may be busy. | |
51 | */ | |
52 | lru_add_drain_all(); | |
53 | ||
54 | return 0; | |
55 | } | |
56 | ||
b20a3503 | 57 | /* |
894bc310 LS |
58 | * Add isolated pages on the list back to the LRU under page lock |
59 | * to avoid leaking evictable pages back onto unevictable list. | |
b20a3503 CL |
60 | * |
61 | * returns the number of pages put back. | |
62 | */ | |
63 | int putback_lru_pages(struct list_head *l) | |
64 | { | |
65 | struct page *page; | |
66 | struct page *page2; | |
67 | int count = 0; | |
68 | ||
69 | list_for_each_entry_safe(page, page2, l, lru) { | |
e24f0b8f | 70 | list_del(&page->lru); |
a731286d | 71 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
6c0b1351 | 72 | page_is_file_cache(page)); |
894bc310 | 73 | putback_lru_page(page); |
b20a3503 CL |
74 | count++; |
75 | } | |
76 | return count; | |
77 | } | |
78 | ||
0697212a CL |
79 | /* |
80 | * Restore a potential migration pte to a working pte entry | |
81 | */ | |
e9995ef9 HD |
82 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, |
83 | unsigned long addr, void *old) | |
0697212a CL |
84 | { |
85 | struct mm_struct *mm = vma->vm_mm; | |
86 | swp_entry_t entry; | |
87 | pgd_t *pgd; | |
88 | pud_t *pud; | |
89 | pmd_t *pmd; | |
90 | pte_t *ptep, pte; | |
91 | spinlock_t *ptl; | |
92 | ||
93 | pgd = pgd_offset(mm, addr); | |
94 | if (!pgd_present(*pgd)) | |
e9995ef9 | 95 | goto out; |
0697212a CL |
96 | |
97 | pud = pud_offset(pgd, addr); | |
98 | if (!pud_present(*pud)) | |
e9995ef9 | 99 | goto out; |
0697212a CL |
100 | |
101 | pmd = pmd_offset(pud, addr); | |
102 | if (!pmd_present(*pmd)) | |
e9995ef9 | 103 | goto out; |
0697212a CL |
104 | |
105 | ptep = pte_offset_map(pmd, addr); | |
106 | ||
107 | if (!is_swap_pte(*ptep)) { | |
108 | pte_unmap(ptep); | |
e9995ef9 | 109 | goto out; |
0697212a CL |
110 | } |
111 | ||
112 | ptl = pte_lockptr(mm, pmd); | |
113 | spin_lock(ptl); | |
114 | pte = *ptep; | |
115 | if (!is_swap_pte(pte)) | |
e9995ef9 | 116 | goto unlock; |
0697212a CL |
117 | |
118 | entry = pte_to_swp_entry(pte); | |
119 | ||
e9995ef9 HD |
120 | if (!is_migration_entry(entry) || |
121 | migration_entry_to_page(entry) != old) | |
122 | goto unlock; | |
0697212a | 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); | |
e9995ef9 | 138 | unlock: |
0697212a | 139 | pte_unmap_unlock(ptep, ptl); |
e9995ef9 HD |
140 | out: |
141 | return SWAP_AGAIN; | |
0697212a CL |
142 | } |
143 | ||
04e62a29 CL |
144 | /* |
145 | * Get rid of all migration entries and replace them by | |
146 | * references to the indicated page. | |
147 | */ | |
148 | static void remove_migration_ptes(struct page *old, struct page *new) | |
149 | { | |
e9995ef9 | 150 | rmap_walk(new, remove_migration_pte, old); |
04e62a29 CL |
151 | } |
152 | ||
0697212a CL |
153 | /* |
154 | * Something used the pte of a page under migration. We need to | |
155 | * get to the page and wait until migration is finished. | |
156 | * When we return from this function the fault will be retried. | |
157 | * | |
158 | * This function is called from do_swap_page(). | |
159 | */ | |
160 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
161 | unsigned long address) | |
162 | { | |
163 | pte_t *ptep, pte; | |
164 | spinlock_t *ptl; | |
165 | swp_entry_t entry; | |
166 | struct page *page; | |
167 | ||
168 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); | |
169 | pte = *ptep; | |
170 | if (!is_swap_pte(pte)) | |
171 | goto out; | |
172 | ||
173 | entry = pte_to_swp_entry(pte); | |
174 | if (!is_migration_entry(entry)) | |
175 | goto out; | |
176 | ||
177 | page = migration_entry_to_page(entry); | |
178 | ||
e286781d NP |
179 | /* |
180 | * Once radix-tree replacement of page migration started, page_count | |
181 | * *must* be zero. And, we don't want to call wait_on_page_locked() | |
182 | * against a page without get_page(). | |
183 | * So, we use get_page_unless_zero(), here. Even failed, page fault | |
184 | * will occur again. | |
185 | */ | |
186 | if (!get_page_unless_zero(page)) | |
187 | goto out; | |
0697212a CL |
188 | pte_unmap_unlock(ptep, ptl); |
189 | wait_on_page_locked(page); | |
190 | put_page(page); | |
191 | return; | |
192 | out: | |
193 | pte_unmap_unlock(ptep, ptl); | |
194 | } | |
195 | ||
b20a3503 | 196 | /* |
c3fcf8a5 | 197 | * Replace the page in the mapping. |
5b5c7120 CL |
198 | * |
199 | * The number of remaining references must be: | |
200 | * 1 for anonymous pages without a mapping | |
201 | * 2 for pages with a mapping | |
266cf658 | 202 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. |
b20a3503 | 203 | */ |
2d1db3b1 CL |
204 | static int migrate_page_move_mapping(struct address_space *mapping, |
205 | struct page *newpage, struct page *page) | |
b20a3503 | 206 | { |
e286781d | 207 | int expected_count; |
7cf9c2c7 | 208 | void **pslot; |
b20a3503 | 209 | |
6c5240ae | 210 | if (!mapping) { |
0e8c7d0f | 211 | /* Anonymous page without mapping */ |
6c5240ae CL |
212 | if (page_count(page) != 1) |
213 | return -EAGAIN; | |
214 | return 0; | |
215 | } | |
216 | ||
19fd6231 | 217 | spin_lock_irq(&mapping->tree_lock); |
b20a3503 | 218 | |
7cf9c2c7 NP |
219 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
220 | page_index(page)); | |
b20a3503 | 221 | |
edcf4748 | 222 | expected_count = 2 + page_has_private(page); |
e286781d | 223 | if (page_count(page) != expected_count || |
7cf9c2c7 | 224 | (struct page *)radix_tree_deref_slot(pslot) != page) { |
19fd6231 | 225 | spin_unlock_irq(&mapping->tree_lock); |
e23ca00b | 226 | return -EAGAIN; |
b20a3503 CL |
227 | } |
228 | ||
e286781d | 229 | if (!page_freeze_refs(page, expected_count)) { |
19fd6231 | 230 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
231 | return -EAGAIN; |
232 | } | |
233 | ||
b20a3503 CL |
234 | /* |
235 | * Now we know that no one else is looking at the page. | |
b20a3503 | 236 | */ |
7cf9c2c7 | 237 | get_page(newpage); /* add cache reference */ |
b20a3503 CL |
238 | if (PageSwapCache(page)) { |
239 | SetPageSwapCache(newpage); | |
240 | set_page_private(newpage, page_private(page)); | |
241 | } | |
242 | ||
7cf9c2c7 NP |
243 | radix_tree_replace_slot(pslot, newpage); |
244 | ||
e286781d | 245 | page_unfreeze_refs(page, expected_count); |
7cf9c2c7 NP |
246 | /* |
247 | * Drop cache reference from old page. | |
248 | * We know this isn't the last reference. | |
249 | */ | |
b20a3503 | 250 | __put_page(page); |
7cf9c2c7 | 251 | |
0e8c7d0f CL |
252 | /* |
253 | * If moved to a different zone then also account | |
254 | * the page for that zone. Other VM counters will be | |
255 | * taken care of when we establish references to the | |
256 | * new page and drop references to the old page. | |
257 | * | |
258 | * Note that anonymous pages are accounted for | |
259 | * via NR_FILE_PAGES and NR_ANON_PAGES if they | |
260 | * are mapped to swap space. | |
261 | */ | |
262 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
263 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
4b02108a KM |
264 | if (PageSwapBacked(page)) { |
265 | __dec_zone_page_state(page, NR_SHMEM); | |
266 | __inc_zone_page_state(newpage, NR_SHMEM); | |
267 | } | |
19fd6231 | 268 | spin_unlock_irq(&mapping->tree_lock); |
b20a3503 CL |
269 | |
270 | return 0; | |
271 | } | |
b20a3503 CL |
272 | |
273 | /* | |
274 | * Copy the page to its new location | |
275 | */ | |
e7340f73 | 276 | static void migrate_page_copy(struct page *newpage, struct page *page) |
b20a3503 | 277 | { |
b7abea96 KH |
278 | int anon; |
279 | ||
b20a3503 CL |
280 | copy_highpage(newpage, page); |
281 | ||
282 | if (PageError(page)) | |
283 | SetPageError(newpage); | |
284 | if (PageReferenced(page)) | |
285 | SetPageReferenced(newpage); | |
286 | if (PageUptodate(page)) | |
287 | SetPageUptodate(newpage); | |
894bc310 LS |
288 | if (TestClearPageActive(page)) { |
289 | VM_BUG_ON(PageUnevictable(page)); | |
b20a3503 | 290 | SetPageActive(newpage); |
418b27ef LS |
291 | } else if (TestClearPageUnevictable(page)) |
292 | SetPageUnevictable(newpage); | |
b20a3503 CL |
293 | if (PageChecked(page)) |
294 | SetPageChecked(newpage); | |
295 | if (PageMappedToDisk(page)) | |
296 | SetPageMappedToDisk(newpage); | |
297 | ||
298 | if (PageDirty(page)) { | |
299 | clear_page_dirty_for_io(page); | |
3a902c5f NP |
300 | /* |
301 | * Want to mark the page and the radix tree as dirty, and | |
302 | * redo the accounting that clear_page_dirty_for_io undid, | |
303 | * but we can't use set_page_dirty because that function | |
304 | * is actually a signal that all of the page has become dirty. | |
305 | * Wheras only part of our page may be dirty. | |
306 | */ | |
307 | __set_page_dirty_nobuffers(newpage); | |
b20a3503 CL |
308 | } |
309 | ||
b291f000 | 310 | mlock_migrate_page(newpage, page); |
e9995ef9 | 311 | ksm_migrate_page(newpage, page); |
b291f000 | 312 | |
b20a3503 | 313 | ClearPageSwapCache(page); |
b20a3503 CL |
314 | ClearPagePrivate(page); |
315 | set_page_private(page, 0); | |
b7abea96 KH |
316 | /* page->mapping contains a flag for PageAnon() */ |
317 | anon = PageAnon(page); | |
b20a3503 CL |
318 | page->mapping = NULL; |
319 | ||
320 | /* | |
321 | * If any waiters have accumulated on the new page then | |
322 | * wake them up. | |
323 | */ | |
324 | if (PageWriteback(newpage)) | |
325 | end_page_writeback(newpage); | |
326 | } | |
b20a3503 | 327 | |
1d8b85cc CL |
328 | /************************************************************ |
329 | * Migration functions | |
330 | ***********************************************************/ | |
331 | ||
332 | /* Always fail migration. Used for mappings that are not movable */ | |
2d1db3b1 CL |
333 | int fail_migrate_page(struct address_space *mapping, |
334 | struct page *newpage, struct page *page) | |
1d8b85cc CL |
335 | { |
336 | return -EIO; | |
337 | } | |
338 | EXPORT_SYMBOL(fail_migrate_page); | |
339 | ||
b20a3503 CL |
340 | /* |
341 | * Common logic to directly migrate a single page suitable for | |
266cf658 | 342 | * pages that do not use PagePrivate/PagePrivate2. |
b20a3503 CL |
343 | * |
344 | * Pages are locked upon entry and exit. | |
345 | */ | |
2d1db3b1 CL |
346 | int migrate_page(struct address_space *mapping, |
347 | struct page *newpage, struct page *page) | |
b20a3503 CL |
348 | { |
349 | int rc; | |
350 | ||
351 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ | |
352 | ||
2d1db3b1 | 353 | rc = migrate_page_move_mapping(mapping, newpage, page); |
b20a3503 CL |
354 | |
355 | if (rc) | |
356 | return rc; | |
357 | ||
358 | migrate_page_copy(newpage, page); | |
b20a3503 CL |
359 | return 0; |
360 | } | |
361 | EXPORT_SYMBOL(migrate_page); | |
362 | ||
9361401e | 363 | #ifdef CONFIG_BLOCK |
1d8b85cc CL |
364 | /* |
365 | * Migration function for pages with buffers. This function can only be used | |
366 | * if the underlying filesystem guarantees that no other references to "page" | |
367 | * exist. | |
368 | */ | |
2d1db3b1 CL |
369 | int buffer_migrate_page(struct address_space *mapping, |
370 | struct page *newpage, struct page *page) | |
1d8b85cc | 371 | { |
1d8b85cc CL |
372 | struct buffer_head *bh, *head; |
373 | int rc; | |
374 | ||
1d8b85cc | 375 | if (!page_has_buffers(page)) |
2d1db3b1 | 376 | return migrate_page(mapping, newpage, page); |
1d8b85cc CL |
377 | |
378 | head = page_buffers(page); | |
379 | ||
2d1db3b1 | 380 | rc = migrate_page_move_mapping(mapping, newpage, page); |
1d8b85cc CL |
381 | |
382 | if (rc) | |
383 | return rc; | |
384 | ||
385 | bh = head; | |
386 | do { | |
387 | get_bh(bh); | |
388 | lock_buffer(bh); | |
389 | bh = bh->b_this_page; | |
390 | ||
391 | } while (bh != head); | |
392 | ||
393 | ClearPagePrivate(page); | |
394 | set_page_private(newpage, page_private(page)); | |
395 | set_page_private(page, 0); | |
396 | put_page(page); | |
397 | get_page(newpage); | |
398 | ||
399 | bh = head; | |
400 | do { | |
401 | set_bh_page(bh, newpage, bh_offset(bh)); | |
402 | bh = bh->b_this_page; | |
403 | ||
404 | } while (bh != head); | |
405 | ||
406 | SetPagePrivate(newpage); | |
407 | ||
408 | migrate_page_copy(newpage, page); | |
409 | ||
410 | bh = head; | |
411 | do { | |
412 | unlock_buffer(bh); | |
413 | put_bh(bh); | |
414 | bh = bh->b_this_page; | |
415 | ||
416 | } while (bh != head); | |
417 | ||
418 | return 0; | |
419 | } | |
420 | EXPORT_SYMBOL(buffer_migrate_page); | |
9361401e | 421 | #endif |
1d8b85cc | 422 | |
04e62a29 CL |
423 | /* |
424 | * Writeback a page to clean the dirty state | |
425 | */ | |
426 | static int writeout(struct address_space *mapping, struct page *page) | |
8351a6e4 | 427 | { |
04e62a29 CL |
428 | struct writeback_control wbc = { |
429 | .sync_mode = WB_SYNC_NONE, | |
430 | .nr_to_write = 1, | |
431 | .range_start = 0, | |
432 | .range_end = LLONG_MAX, | |
433 | .nonblocking = 1, | |
434 | .for_reclaim = 1 | |
435 | }; | |
436 | int rc; | |
437 | ||
438 | if (!mapping->a_ops->writepage) | |
439 | /* No write method for the address space */ | |
440 | return -EINVAL; | |
441 | ||
442 | if (!clear_page_dirty_for_io(page)) | |
443 | /* Someone else already triggered a write */ | |
444 | return -EAGAIN; | |
445 | ||
8351a6e4 | 446 | /* |
04e62a29 CL |
447 | * A dirty page may imply that the underlying filesystem has |
448 | * the page on some queue. So the page must be clean for | |
449 | * migration. Writeout may mean we loose the lock and the | |
450 | * page state is no longer what we checked for earlier. | |
451 | * At this point we know that the migration attempt cannot | |
452 | * be successful. | |
8351a6e4 | 453 | */ |
04e62a29 | 454 | remove_migration_ptes(page, page); |
8351a6e4 | 455 | |
04e62a29 | 456 | rc = mapping->a_ops->writepage(page, &wbc); |
8351a6e4 | 457 | |
04e62a29 CL |
458 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
459 | /* unlocked. Relock */ | |
460 | lock_page(page); | |
461 | ||
bda8550d | 462 | return (rc < 0) ? -EIO : -EAGAIN; |
04e62a29 CL |
463 | } |
464 | ||
465 | /* | |
466 | * Default handling if a filesystem does not provide a migration function. | |
467 | */ | |
468 | static int fallback_migrate_page(struct address_space *mapping, | |
469 | struct page *newpage, struct page *page) | |
470 | { | |
471 | if (PageDirty(page)) | |
472 | return writeout(mapping, page); | |
8351a6e4 CL |
473 | |
474 | /* | |
475 | * Buffers may be managed in a filesystem specific way. | |
476 | * We must have no buffers or drop them. | |
477 | */ | |
266cf658 | 478 | if (page_has_private(page) && |
8351a6e4 CL |
479 | !try_to_release_page(page, GFP_KERNEL)) |
480 | return -EAGAIN; | |
481 | ||
482 | return migrate_page(mapping, newpage, page); | |
483 | } | |
484 | ||
e24f0b8f CL |
485 | /* |
486 | * Move a page to a newly allocated page | |
487 | * The page is locked and all ptes have been successfully removed. | |
488 | * | |
489 | * The new page will have replaced the old page if this function | |
490 | * is successful. | |
894bc310 LS |
491 | * |
492 | * Return value: | |
493 | * < 0 - error code | |
494 | * == 0 - success | |
e24f0b8f CL |
495 | */ |
496 | static int move_to_new_page(struct page *newpage, struct page *page) | |
497 | { | |
498 | struct address_space *mapping; | |
499 | int rc; | |
500 | ||
501 | /* | |
502 | * Block others from accessing the page when we get around to | |
503 | * establishing additional references. We are the only one | |
504 | * holding a reference to the new page at this point. | |
505 | */ | |
529ae9aa | 506 | if (!trylock_page(newpage)) |
e24f0b8f CL |
507 | BUG(); |
508 | ||
509 | /* Prepare mapping for the new page.*/ | |
510 | newpage->index = page->index; | |
511 | newpage->mapping = page->mapping; | |
b2e18538 RR |
512 | if (PageSwapBacked(page)) |
513 | SetPageSwapBacked(newpage); | |
e24f0b8f CL |
514 | |
515 | mapping = page_mapping(page); | |
516 | if (!mapping) | |
517 | rc = migrate_page(mapping, newpage, page); | |
518 | else if (mapping->a_ops->migratepage) | |
519 | /* | |
520 | * Most pages have a mapping and most filesystems | |
521 | * should provide a migration function. Anonymous | |
522 | * pages are part of swap space which also has its | |
523 | * own migration function. This is the most common | |
524 | * path for page migration. | |
525 | */ | |
526 | rc = mapping->a_ops->migratepage(mapping, | |
527 | newpage, page); | |
528 | else | |
529 | rc = fallback_migrate_page(mapping, newpage, page); | |
530 | ||
e9995ef9 | 531 | if (!rc) |
e24f0b8f | 532 | remove_migration_ptes(page, newpage); |
e9995ef9 | 533 | else |
e24f0b8f CL |
534 | newpage->mapping = NULL; |
535 | ||
536 | unlock_page(newpage); | |
537 | ||
538 | return rc; | |
539 | } | |
540 | ||
541 | /* | |
542 | * Obtain the lock on page, remove all ptes and migrate the page | |
543 | * to the newly allocated page in newpage. | |
544 | */ | |
95a402c3 | 545 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
62b61f61 | 546 | struct page *page, int force, int offlining) |
e24f0b8f CL |
547 | { |
548 | int rc = 0; | |
742755a1 CL |
549 | int *result = NULL; |
550 | struct page *newpage = get_new_page(page, private, &result); | |
989f89c5 | 551 | int rcu_locked = 0; |
ae41be37 | 552 | int charge = 0; |
e00e4316 | 553 | struct mem_cgroup *mem = NULL; |
95a402c3 CL |
554 | |
555 | if (!newpage) | |
556 | return -ENOMEM; | |
e24f0b8f | 557 | |
894bc310 | 558 | if (page_count(page) == 1) { |
e24f0b8f | 559 | /* page was freed from under us. So we are done. */ |
95a402c3 | 560 | goto move_newpage; |
894bc310 | 561 | } |
e24f0b8f | 562 | |
e8589cc1 | 563 | /* prepare cgroup just returns 0 or -ENOMEM */ |
e24f0b8f | 564 | rc = -EAGAIN; |
01b1ae63 | 565 | |
529ae9aa | 566 | if (!trylock_page(page)) { |
e24f0b8f | 567 | if (!force) |
95a402c3 | 568 | goto move_newpage; |
e24f0b8f CL |
569 | lock_page(page); |
570 | } | |
571 | ||
62b61f61 HD |
572 | /* |
573 | * Only memory hotplug's offline_pages() caller has locked out KSM, | |
574 | * and can safely migrate a KSM page. The other cases have skipped | |
575 | * PageKsm along with PageReserved - but it is only now when we have | |
576 | * the page lock that we can be certain it will not go KSM beneath us | |
577 | * (KSM will not upgrade a page from PageAnon to PageKsm when it sees | |
578 | * its pagecount raised, but only here do we take the page lock which | |
579 | * serializes that). | |
580 | */ | |
581 | if (PageKsm(page) && !offlining) { | |
582 | rc = -EBUSY; | |
583 | goto unlock; | |
584 | } | |
585 | ||
01b1ae63 KH |
586 | /* charge against new page */ |
587 | charge = mem_cgroup_prepare_migration(page, &mem); | |
588 | if (charge == -ENOMEM) { | |
589 | rc = -ENOMEM; | |
590 | goto unlock; | |
591 | } | |
592 | BUG_ON(charge); | |
593 | ||
e24f0b8f CL |
594 | if (PageWriteback(page)) { |
595 | if (!force) | |
01b1ae63 | 596 | goto uncharge; |
e24f0b8f CL |
597 | wait_on_page_writeback(page); |
598 | } | |
e24f0b8f | 599 | /* |
dc386d4d KH |
600 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
601 | * we cannot notice that anon_vma is freed while we migrates a page. | |
602 | * This rcu_read_lock() delays freeing anon_vma pointer until the end | |
603 | * of migration. File cache pages are no problem because of page_lock() | |
989f89c5 KH |
604 | * File Caches may use write_page() or lock_page() in migration, then, |
605 | * just care Anon page here. | |
dc386d4d | 606 | */ |
989f89c5 KH |
607 | if (PageAnon(page)) { |
608 | rcu_read_lock(); | |
609 | rcu_locked = 1; | |
610 | } | |
62e1c553 | 611 | |
dc386d4d | 612 | /* |
62e1c553 SL |
613 | * Corner case handling: |
614 | * 1. When a new swap-cache page is read into, it is added to the LRU | |
615 | * and treated as swapcache but it has no rmap yet. | |
616 | * Calling try_to_unmap() against a page->mapping==NULL page will | |
617 | * trigger a BUG. So handle it here. | |
618 | * 2. An orphaned page (see truncate_complete_page) might have | |
619 | * fs-private metadata. The page can be picked up due to memory | |
620 | * offlining. Everywhere else except page reclaim, the page is | |
621 | * invisible to the vm, so the page can not be migrated. So try to | |
622 | * free the metadata, so the page can be freed. | |
e24f0b8f | 623 | */ |
62e1c553 | 624 | if (!page->mapping) { |
266cf658 | 625 | if (!PageAnon(page) && page_has_private(page)) { |
62e1c553 SL |
626 | /* |
627 | * Go direct to try_to_free_buffers() here because | |
628 | * a) that's what try_to_release_page() would do anyway | |
629 | * b) we may be under rcu_read_lock() here, so we can't | |
630 | * use GFP_KERNEL which is what try_to_release_page() | |
631 | * needs to be effective. | |
632 | */ | |
633 | try_to_free_buffers(page); | |
abfc3488 | 634 | goto rcu_unlock; |
62e1c553 | 635 | } |
abfc3488 | 636 | goto skip_unmap; |
62e1c553 SL |
637 | } |
638 | ||
dc386d4d | 639 | /* Establish migration ptes or remove ptes */ |
14fa31b8 | 640 | try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
dc386d4d | 641 | |
abfc3488 | 642 | skip_unmap: |
e6a1530d CL |
643 | if (!page_mapped(page)) |
644 | rc = move_to_new_page(newpage, page); | |
e24f0b8f | 645 | |
e8589cc1 | 646 | if (rc) |
e24f0b8f | 647 | remove_migration_ptes(page, page); |
dc386d4d | 648 | rcu_unlock: |
989f89c5 KH |
649 | if (rcu_locked) |
650 | rcu_read_unlock(); | |
01b1ae63 KH |
651 | uncharge: |
652 | if (!charge) | |
653 | mem_cgroup_end_migration(mem, page, newpage); | |
e24f0b8f CL |
654 | unlock: |
655 | unlock_page(page); | |
95a402c3 | 656 | |
e24f0b8f | 657 | if (rc != -EAGAIN) { |
aaa994b3 CL |
658 | /* |
659 | * A page that has been migrated has all references | |
660 | * removed and will be freed. A page that has not been | |
661 | * migrated will have kepts its references and be | |
662 | * restored. | |
663 | */ | |
664 | list_del(&page->lru); | |
a731286d | 665 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
6c0b1351 | 666 | page_is_file_cache(page)); |
894bc310 | 667 | putback_lru_page(page); |
e24f0b8f | 668 | } |
95a402c3 CL |
669 | |
670 | move_newpage: | |
894bc310 | 671 | |
95a402c3 CL |
672 | /* |
673 | * Move the new page to the LRU. If migration was not successful | |
674 | * then this will free the page. | |
675 | */ | |
894bc310 LS |
676 | putback_lru_page(newpage); |
677 | ||
742755a1 CL |
678 | if (result) { |
679 | if (rc) | |
680 | *result = rc; | |
681 | else | |
682 | *result = page_to_nid(newpage); | |
683 | } | |
e24f0b8f CL |
684 | return rc; |
685 | } | |
686 | ||
b20a3503 CL |
687 | /* |
688 | * migrate_pages | |
689 | * | |
95a402c3 CL |
690 | * The function takes one list of pages to migrate and a function |
691 | * that determines from the page to be migrated and the private data | |
692 | * the target of the move and allocates the page. | |
b20a3503 CL |
693 | * |
694 | * The function returns after 10 attempts or if no pages | |
695 | * are movable anymore because to has become empty | |
aaa994b3 | 696 | * or no retryable pages exist anymore. All pages will be |
e9534b3f | 697 | * returned to the LRU or freed. |
b20a3503 | 698 | * |
95a402c3 | 699 | * Return: Number of pages not migrated or error code. |
b20a3503 | 700 | */ |
95a402c3 | 701 | int migrate_pages(struct list_head *from, |
62b61f61 | 702 | new_page_t get_new_page, unsigned long private, int offlining) |
b20a3503 | 703 | { |
e24f0b8f | 704 | int retry = 1; |
b20a3503 CL |
705 | int nr_failed = 0; |
706 | int pass = 0; | |
707 | struct page *page; | |
708 | struct page *page2; | |
709 | int swapwrite = current->flags & PF_SWAPWRITE; | |
710 | int rc; | |
711 | ||
712 | if (!swapwrite) | |
713 | current->flags |= PF_SWAPWRITE; | |
714 | ||
e24f0b8f CL |
715 | for(pass = 0; pass < 10 && retry; pass++) { |
716 | retry = 0; | |
b20a3503 | 717 | |
e24f0b8f | 718 | list_for_each_entry_safe(page, page2, from, lru) { |
e24f0b8f | 719 | cond_resched(); |
2d1db3b1 | 720 | |
95a402c3 | 721 | rc = unmap_and_move(get_new_page, private, |
62b61f61 | 722 | page, pass > 2, offlining); |
2d1db3b1 | 723 | |
e24f0b8f | 724 | switch(rc) { |
95a402c3 CL |
725 | case -ENOMEM: |
726 | goto out; | |
e24f0b8f | 727 | case -EAGAIN: |
2d1db3b1 | 728 | retry++; |
e24f0b8f CL |
729 | break; |
730 | case 0: | |
e24f0b8f CL |
731 | break; |
732 | default: | |
2d1db3b1 | 733 | /* Permanent failure */ |
2d1db3b1 | 734 | nr_failed++; |
e24f0b8f | 735 | break; |
2d1db3b1 | 736 | } |
b20a3503 CL |
737 | } |
738 | } | |
95a402c3 CL |
739 | rc = 0; |
740 | out: | |
b20a3503 CL |
741 | if (!swapwrite) |
742 | current->flags &= ~PF_SWAPWRITE; | |
743 | ||
aaa994b3 | 744 | putback_lru_pages(from); |
b20a3503 | 745 | |
95a402c3 CL |
746 | if (rc) |
747 | return rc; | |
b20a3503 | 748 | |
95a402c3 | 749 | return nr_failed + retry; |
b20a3503 | 750 | } |
95a402c3 | 751 | |
742755a1 CL |
752 | #ifdef CONFIG_NUMA |
753 | /* | |
754 | * Move a list of individual pages | |
755 | */ | |
756 | struct page_to_node { | |
757 | unsigned long addr; | |
758 | struct page *page; | |
759 | int node; | |
760 | int status; | |
761 | }; | |
762 | ||
763 | static struct page *new_page_node(struct page *p, unsigned long private, | |
764 | int **result) | |
765 | { | |
766 | struct page_to_node *pm = (struct page_to_node *)private; | |
767 | ||
768 | while (pm->node != MAX_NUMNODES && pm->page != p) | |
769 | pm++; | |
770 | ||
771 | if (pm->node == MAX_NUMNODES) | |
772 | return NULL; | |
773 | ||
774 | *result = &pm->status; | |
775 | ||
6484eb3e | 776 | return alloc_pages_exact_node(pm->node, |
769848c0 | 777 | GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); |
742755a1 CL |
778 | } |
779 | ||
780 | /* | |
781 | * Move a set of pages as indicated in the pm array. The addr | |
782 | * field must be set to the virtual address of the page to be moved | |
783 | * and the node number must contain a valid target node. | |
5e9a0f02 | 784 | * The pm array ends with node = MAX_NUMNODES. |
742755a1 | 785 | */ |
5e9a0f02 BG |
786 | static int do_move_page_to_node_array(struct mm_struct *mm, |
787 | struct page_to_node *pm, | |
788 | int migrate_all) | |
742755a1 CL |
789 | { |
790 | int err; | |
791 | struct page_to_node *pp; | |
792 | LIST_HEAD(pagelist); | |
793 | ||
794 | down_read(&mm->mmap_sem); | |
795 | ||
796 | /* | |
797 | * Build a list of pages to migrate | |
798 | */ | |
742755a1 CL |
799 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
800 | struct vm_area_struct *vma; | |
801 | struct page *page; | |
802 | ||
742755a1 CL |
803 | err = -EFAULT; |
804 | vma = find_vma(mm, pp->addr); | |
0dc952dc | 805 | if (!vma || !vma_migratable(vma)) |
742755a1 CL |
806 | goto set_status; |
807 | ||
808 | page = follow_page(vma, pp->addr, FOLL_GET); | |
89f5b7da LT |
809 | |
810 | err = PTR_ERR(page); | |
811 | if (IS_ERR(page)) | |
812 | goto set_status; | |
813 | ||
742755a1 CL |
814 | err = -ENOENT; |
815 | if (!page) | |
816 | goto set_status; | |
817 | ||
62b61f61 HD |
818 | /* Use PageReserved to check for zero page */ |
819 | if (PageReserved(page) || PageKsm(page)) | |
742755a1 CL |
820 | goto put_and_set; |
821 | ||
822 | pp->page = page; | |
823 | err = page_to_nid(page); | |
824 | ||
825 | if (err == pp->node) | |
826 | /* | |
827 | * Node already in the right place | |
828 | */ | |
829 | goto put_and_set; | |
830 | ||
831 | err = -EACCES; | |
832 | if (page_mapcount(page) > 1 && | |
833 | !migrate_all) | |
834 | goto put_and_set; | |
835 | ||
62695a84 | 836 | err = isolate_lru_page(page); |
6d9c285a | 837 | if (!err) { |
62695a84 | 838 | list_add_tail(&page->lru, &pagelist); |
6d9c285a KM |
839 | inc_zone_page_state(page, NR_ISOLATED_ANON + |
840 | page_is_file_cache(page)); | |
841 | } | |
742755a1 CL |
842 | put_and_set: |
843 | /* | |
844 | * Either remove the duplicate refcount from | |
845 | * isolate_lru_page() or drop the page ref if it was | |
846 | * not isolated. | |
847 | */ | |
848 | put_page(page); | |
849 | set_status: | |
850 | pp->status = err; | |
851 | } | |
852 | ||
e78bbfa8 | 853 | err = 0; |
742755a1 CL |
854 | if (!list_empty(&pagelist)) |
855 | err = migrate_pages(&pagelist, new_page_node, | |
62b61f61 | 856 | (unsigned long)pm, 0); |
742755a1 CL |
857 | |
858 | up_read(&mm->mmap_sem); | |
859 | return err; | |
860 | } | |
861 | ||
5e9a0f02 BG |
862 | /* |
863 | * Migrate an array of page address onto an array of nodes and fill | |
864 | * the corresponding array of status. | |
865 | */ | |
866 | static int do_pages_move(struct mm_struct *mm, struct task_struct *task, | |
867 | unsigned long nr_pages, | |
868 | const void __user * __user *pages, | |
869 | const int __user *nodes, | |
870 | int __user *status, int flags) | |
871 | { | |
3140a227 | 872 | struct page_to_node *pm; |
5e9a0f02 | 873 | nodemask_t task_nodes; |
3140a227 BG |
874 | unsigned long chunk_nr_pages; |
875 | unsigned long chunk_start; | |
876 | int err; | |
5e9a0f02 BG |
877 | |
878 | task_nodes = cpuset_mems_allowed(task); | |
879 | ||
3140a227 BG |
880 | err = -ENOMEM; |
881 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); | |
882 | if (!pm) | |
5e9a0f02 | 883 | goto out; |
35282a2d BG |
884 | |
885 | migrate_prep(); | |
886 | ||
5e9a0f02 | 887 | /* |
3140a227 BG |
888 | * Store a chunk of page_to_node array in a page, |
889 | * but keep the last one as a marker | |
5e9a0f02 | 890 | */ |
3140a227 | 891 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
5e9a0f02 | 892 | |
3140a227 BG |
893 | for (chunk_start = 0; |
894 | chunk_start < nr_pages; | |
895 | chunk_start += chunk_nr_pages) { | |
896 | int j; | |
5e9a0f02 | 897 | |
3140a227 BG |
898 | if (chunk_start + chunk_nr_pages > nr_pages) |
899 | chunk_nr_pages = nr_pages - chunk_start; | |
900 | ||
901 | /* fill the chunk pm with addrs and nodes from user-space */ | |
902 | for (j = 0; j < chunk_nr_pages; j++) { | |
903 | const void __user *p; | |
5e9a0f02 BG |
904 | int node; |
905 | ||
3140a227 BG |
906 | err = -EFAULT; |
907 | if (get_user(p, pages + j + chunk_start)) | |
908 | goto out_pm; | |
909 | pm[j].addr = (unsigned long) p; | |
910 | ||
911 | if (get_user(node, nodes + j + chunk_start)) | |
5e9a0f02 BG |
912 | goto out_pm; |
913 | ||
914 | err = -ENODEV; | |
915 | if (!node_state(node, N_HIGH_MEMORY)) | |
916 | goto out_pm; | |
917 | ||
918 | err = -EACCES; | |
919 | if (!node_isset(node, task_nodes)) | |
920 | goto out_pm; | |
921 | ||
3140a227 BG |
922 | pm[j].node = node; |
923 | } | |
924 | ||
925 | /* End marker for this chunk */ | |
926 | pm[chunk_nr_pages].node = MAX_NUMNODES; | |
927 | ||
928 | /* Migrate this chunk */ | |
929 | err = do_move_page_to_node_array(mm, pm, | |
930 | flags & MPOL_MF_MOVE_ALL); | |
931 | if (err < 0) | |
932 | goto out_pm; | |
5e9a0f02 | 933 | |
5e9a0f02 | 934 | /* Return status information */ |
3140a227 BG |
935 | for (j = 0; j < chunk_nr_pages; j++) |
936 | if (put_user(pm[j].status, status + j + chunk_start)) { | |
5e9a0f02 | 937 | err = -EFAULT; |
3140a227 BG |
938 | goto out_pm; |
939 | } | |
940 | } | |
941 | err = 0; | |
5e9a0f02 BG |
942 | |
943 | out_pm: | |
3140a227 | 944 | free_page((unsigned long)pm); |
5e9a0f02 BG |
945 | out: |
946 | return err; | |
947 | } | |
948 | ||
742755a1 | 949 | /* |
2f007e74 | 950 | * Determine the nodes of an array of pages and store it in an array of status. |
742755a1 | 951 | */ |
80bba129 BG |
952 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, |
953 | const void __user **pages, int *status) | |
742755a1 | 954 | { |
2f007e74 | 955 | unsigned long i; |
2f007e74 | 956 | |
742755a1 CL |
957 | down_read(&mm->mmap_sem); |
958 | ||
2f007e74 | 959 | for (i = 0; i < nr_pages; i++) { |
80bba129 | 960 | unsigned long addr = (unsigned long)(*pages); |
742755a1 CL |
961 | struct vm_area_struct *vma; |
962 | struct page *page; | |
c095adbc | 963 | int err = -EFAULT; |
2f007e74 BG |
964 | |
965 | vma = find_vma(mm, addr); | |
742755a1 CL |
966 | if (!vma) |
967 | goto set_status; | |
968 | ||
2f007e74 | 969 | page = follow_page(vma, addr, 0); |
89f5b7da LT |
970 | |
971 | err = PTR_ERR(page); | |
972 | if (IS_ERR(page)) | |
973 | goto set_status; | |
974 | ||
742755a1 CL |
975 | err = -ENOENT; |
976 | /* Use PageReserved to check for zero page */ | |
62b61f61 | 977 | if (!page || PageReserved(page) || PageKsm(page)) |
742755a1 CL |
978 | goto set_status; |
979 | ||
980 | err = page_to_nid(page); | |
981 | set_status: | |
80bba129 BG |
982 | *status = err; |
983 | ||
984 | pages++; | |
985 | status++; | |
986 | } | |
987 | ||
988 | up_read(&mm->mmap_sem); | |
989 | } | |
990 | ||
991 | /* | |
992 | * Determine the nodes of a user array of pages and store it in | |
993 | * a user array of status. | |
994 | */ | |
995 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, | |
996 | const void __user * __user *pages, | |
997 | int __user *status) | |
998 | { | |
999 | #define DO_PAGES_STAT_CHUNK_NR 16 | |
1000 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; | |
1001 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; | |
1002 | unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR; | |
1003 | int err; | |
1004 | ||
1005 | for (i = 0; i < nr_pages; i += chunk_nr) { | |
b9255850 | 1006 | if (chunk_nr > nr_pages - i) |
80bba129 BG |
1007 | chunk_nr = nr_pages - i; |
1008 | ||
1009 | err = copy_from_user(chunk_pages, &pages[i], | |
1010 | chunk_nr * sizeof(*chunk_pages)); | |
1011 | if (err) { | |
1012 | err = -EFAULT; | |
1013 | goto out; | |
1014 | } | |
1015 | ||
1016 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); | |
1017 | ||
1018 | err = copy_to_user(&status[i], chunk_status, | |
1019 | chunk_nr * sizeof(*chunk_status)); | |
1020 | if (err) { | |
1021 | err = -EFAULT; | |
1022 | goto out; | |
1023 | } | |
742755a1 | 1024 | } |
2f007e74 | 1025 | err = 0; |
742755a1 | 1026 | |
2f007e74 | 1027 | out: |
2f007e74 | 1028 | return err; |
742755a1 CL |
1029 | } |
1030 | ||
1031 | /* | |
1032 | * Move a list of pages in the address space of the currently executing | |
1033 | * process. | |
1034 | */ | |
938bb9f5 HC |
1035 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, |
1036 | const void __user * __user *, pages, | |
1037 | const int __user *, nodes, | |
1038 | int __user *, status, int, flags) | |
742755a1 | 1039 | { |
c69e8d9c | 1040 | const struct cred *cred = current_cred(), *tcred; |
742755a1 | 1041 | struct task_struct *task; |
742755a1 | 1042 | struct mm_struct *mm; |
5e9a0f02 | 1043 | int err; |
742755a1 CL |
1044 | |
1045 | /* Check flags */ | |
1046 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) | |
1047 | return -EINVAL; | |
1048 | ||
1049 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) | |
1050 | return -EPERM; | |
1051 | ||
1052 | /* Find the mm_struct */ | |
1053 | read_lock(&tasklist_lock); | |
228ebcbe | 1054 | task = pid ? find_task_by_vpid(pid) : current; |
742755a1 CL |
1055 | if (!task) { |
1056 | read_unlock(&tasklist_lock); | |
1057 | return -ESRCH; | |
1058 | } | |
1059 | mm = get_task_mm(task); | |
1060 | read_unlock(&tasklist_lock); | |
1061 | ||
1062 | if (!mm) | |
1063 | return -EINVAL; | |
1064 | ||
1065 | /* | |
1066 | * Check if this process has the right to modify the specified | |
1067 | * process. The right exists if the process has administrative | |
1068 | * capabilities, superuser privileges or the same | |
1069 | * userid as the target process. | |
1070 | */ | |
c69e8d9c DH |
1071 | rcu_read_lock(); |
1072 | tcred = __task_cred(task); | |
b6dff3ec DH |
1073 | if (cred->euid != tcred->suid && cred->euid != tcred->uid && |
1074 | cred->uid != tcred->suid && cred->uid != tcred->uid && | |
742755a1 | 1075 | !capable(CAP_SYS_NICE)) { |
c69e8d9c | 1076 | rcu_read_unlock(); |
742755a1 | 1077 | err = -EPERM; |
5e9a0f02 | 1078 | goto out; |
742755a1 | 1079 | } |
c69e8d9c | 1080 | rcu_read_unlock(); |
742755a1 | 1081 | |
86c3a764 DQ |
1082 | err = security_task_movememory(task); |
1083 | if (err) | |
5e9a0f02 | 1084 | goto out; |
86c3a764 | 1085 | |
5e9a0f02 BG |
1086 | if (nodes) { |
1087 | err = do_pages_move(mm, task, nr_pages, pages, nodes, status, | |
1088 | flags); | |
1089 | } else { | |
2f007e74 | 1090 | err = do_pages_stat(mm, nr_pages, pages, status); |
742755a1 CL |
1091 | } |
1092 | ||
742755a1 | 1093 | out: |
742755a1 CL |
1094 | mmput(mm); |
1095 | return err; | |
1096 | } | |
742755a1 | 1097 | |
7b2259b3 CL |
1098 | /* |
1099 | * Call migration functions in the vma_ops that may prepare | |
1100 | * memory in a vm for migration. migration functions may perform | |
1101 | * the migration for vmas that do not have an underlying page struct. | |
1102 | */ | |
1103 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, | |
1104 | const nodemask_t *from, unsigned long flags) | |
1105 | { | |
1106 | struct vm_area_struct *vma; | |
1107 | int err = 0; | |
1108 | ||
1001c9fb | 1109 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { |
7b2259b3 CL |
1110 | if (vma->vm_ops && vma->vm_ops->migrate) { |
1111 | err = vma->vm_ops->migrate(vma, to, from, flags); | |
1112 | if (err) | |
1113 | break; | |
1114 | } | |
1115 | } | |
1116 | return err; | |
1117 | } | |
83d1674a | 1118 | #endif |