blob: 4e0eccca5e265ac19bc507a171a2f720d27f8c21 [file] [log] [blame]
Christoph Lameterb20a3502006-03-22 00:09:12 -08001/*
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>
Christoph Lameter06972122006-06-23 02:03:35 -070018#include <linux/swapops.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080019#include <linux/pagemap.h>
Christoph Lametere23ca002006-04-10 22:52:57 -070020#include <linux/buffer_head.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080021#include <linux/mm_inline.h>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070022#include <linux/nsproxy.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080023#include <linux/pagevec.h>
24#include <linux/rmap.h>
25#include <linux/topology.h>
26#include <linux/cpu.h>
27#include <linux/cpuset.h>
Christoph Lameter04e62a22006-06-23 02:03:38 -070028#include <linux/writeback.h>
Christoph Lameter742755a2006-06-23 02:03:55 -070029#include <linux/mempolicy.h>
30#include <linux/vmalloc.h>
David Quigley86c3a762006-06-23 02:04:02 -070031#include <linux/security.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080032#include <linux/memcontrol.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080033
34#include "internal.h"
35
Christoph Lameterb20a3502006-03-22 00:09:12 -080036#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
37
38/*
39 * Isolate one page from the LRU lists. If successful put it onto
40 * the indicated list with elevated page count.
41 *
42 * Result:
43 * -EBUSY: page not on LRU list
44 * 0: page removed from LRU list and added to the specified list.
45 */
46int isolate_lru_page(struct page *page, struct list_head *pagelist)
47{
48 int ret = -EBUSY;
49
50 if (PageLRU(page)) {
51 struct zone *zone = page_zone(page);
52
53 spin_lock_irq(&zone->lru_lock);
KAMEZAWA Hiroyuki3dd9fe82007-07-26 10:41:08 -070054 if (PageLRU(page) && get_page_unless_zero(page)) {
Christoph Lameterb20a3502006-03-22 00:09:12 -080055 ret = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -080056 ClearPageLRU(page);
57 if (PageActive(page))
58 del_page_from_active_list(zone, page);
59 else
60 del_page_from_inactive_list(zone, page);
61 list_add_tail(&page->lru, pagelist);
62 }
63 spin_unlock_irq(&zone->lru_lock);
64 }
65 return ret;
66}
67
68/*
Christoph Lameter742755a2006-06-23 02:03:55 -070069 * migrate_prep() needs to be called before we start compiling a list of pages
70 * to be migrated using isolate_lru_page().
Christoph Lameterb20a3502006-03-22 00:09:12 -080071 */
72int migrate_prep(void)
73{
Christoph Lameterb20a3502006-03-22 00:09:12 -080074 /*
75 * Clear the LRU lists so pages can be isolated.
76 * Note that pages may be moved off the LRU after we have
77 * drained them. Those pages will fail to migrate like other
78 * pages that may be busy.
79 */
80 lru_add_drain_all();
81
82 return 0;
83}
84
85static inline void move_to_lru(struct page *page)
86{
Christoph Lameterb20a3502006-03-22 00:09:12 -080087 if (PageActive(page)) {
88 /*
89 * lru_cache_add_active checks that
90 * the PG_active bit is off.
91 */
92 ClearPageActive(page);
93 lru_cache_add_active(page);
94 } else {
95 lru_cache_add(page);
96 }
97 put_page(page);
98}
99
100/*
101 * Add isolated pages on the list back to the LRU.
102 *
103 * returns the number of pages put back.
104 */
105int putback_lru_pages(struct list_head *l)
106{
107 struct page *page;
108 struct page *page2;
109 int count = 0;
110
111 list_for_each_entry_safe(page, page2, l, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700112 list_del(&page->lru);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800113 move_to_lru(page);
114 count++;
115 }
116 return count;
117}
118
Christoph Lameter06972122006-06-23 02:03:35 -0700119/*
120 * Restore a potential migration pte to a working pte entry
121 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700122static void remove_migration_pte(struct vm_area_struct *vma,
Christoph Lameter06972122006-06-23 02:03:35 -0700123 struct page *old, struct page *new)
124{
125 struct mm_struct *mm = vma->vm_mm;
126 swp_entry_t entry;
127 pgd_t *pgd;
128 pud_t *pud;
129 pmd_t *pmd;
130 pte_t *ptep, pte;
131 spinlock_t *ptl;
Christoph Lameter04e62a22006-06-23 02:03:38 -0700132 unsigned long addr = page_address_in_vma(new, vma);
133
134 if (addr == -EFAULT)
135 return;
Christoph Lameter06972122006-06-23 02:03:35 -0700136
137 pgd = pgd_offset(mm, addr);
138 if (!pgd_present(*pgd))
139 return;
140
141 pud = pud_offset(pgd, addr);
142 if (!pud_present(*pud))
143 return;
144
145 pmd = pmd_offset(pud, addr);
146 if (!pmd_present(*pmd))
147 return;
148
149 ptep = pte_offset_map(pmd, addr);
150
151 if (!is_swap_pte(*ptep)) {
152 pte_unmap(ptep);
153 return;
154 }
155
156 ptl = pte_lockptr(mm, pmd);
157 spin_lock(ptl);
158 pte = *ptep;
159 if (!is_swap_pte(pte))
160 goto out;
161
162 entry = pte_to_swp_entry(pte);
163
164 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
165 goto out;
166
Hugh Dickins98837c72008-03-04 14:29:06 -0800167 /*
168 * Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge.
169 * Failure is not an option here: we're now expected to remove every
170 * migration pte, and will cause crashes otherwise. Normally this
171 * is not an issue: mem_cgroup_prepare_migration bumped up the old
172 * page_cgroup count for safety, that's now attached to the new page,
173 * so this charge should just be another incrementation of the count,
174 * to keep in balance with rmap.c's mem_cgroup_uncharging. But if
175 * there's been a force_empty, those reference counts may no longer
176 * be reliable, and this charge can actually fail: oh well, we don't
177 * make the situation any worse by proceeding as if it had succeeded.
178 */
179 mem_cgroup_charge(new, mm, GFP_ATOMIC);
180
Christoph Lameter06972122006-06-23 02:03:35 -0700181 get_page(new);
182 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
183 if (is_write_migration_entry(entry))
184 pte = pte_mkwrite(pte);
KAMEZAWA Hiroyuki97ee0522007-10-16 01:25:43 -0700185 flush_cache_page(vma, addr, pte_pfn(pte));
Christoph Lameter06972122006-06-23 02:03:35 -0700186 set_pte_at(mm, addr, ptep, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700187
188 if (PageAnon(new))
189 page_add_anon_rmap(new, vma, addr);
190 else
191 page_add_file_rmap(new);
192
193 /* No need to invalidate - it was non-present before */
194 update_mmu_cache(vma, addr, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700195
Christoph Lameter06972122006-06-23 02:03:35 -0700196out:
197 pte_unmap_unlock(ptep, ptl);
198}
199
200/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700201 * Note that remove_file_migration_ptes will only work on regular mappings,
202 * Nonlinear mappings do not use migration entries.
203 */
204static void remove_file_migration_ptes(struct page *old, struct page *new)
205{
206 struct vm_area_struct *vma;
207 struct address_space *mapping = page_mapping(new);
208 struct prio_tree_iter iter;
209 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
210
211 if (!mapping)
212 return;
213
214 spin_lock(&mapping->i_mmap_lock);
215
216 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
217 remove_migration_pte(vma, old, new);
218
219 spin_unlock(&mapping->i_mmap_lock);
220}
221
222/*
Christoph Lameter06972122006-06-23 02:03:35 -0700223 * Must hold mmap_sem lock on at least one of the vmas containing
224 * the page so that the anon_vma cannot vanish.
225 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700226static void remove_anon_migration_ptes(struct page *old, struct page *new)
Christoph Lameter06972122006-06-23 02:03:35 -0700227{
228 struct anon_vma *anon_vma;
229 struct vm_area_struct *vma;
230 unsigned long mapping;
231
232 mapping = (unsigned long)new->mapping;
233
234 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
235 return;
236
237 /*
238 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
239 */
240 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
241 spin_lock(&anon_vma->lock);
242
243 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
Christoph Lameter04e62a22006-06-23 02:03:38 -0700244 remove_migration_pte(vma, old, new);
Christoph Lameter06972122006-06-23 02:03:35 -0700245
246 spin_unlock(&anon_vma->lock);
247}
248
249/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700250 * Get rid of all migration entries and replace them by
251 * references to the indicated page.
252 */
253static void remove_migration_ptes(struct page *old, struct page *new)
254{
255 if (PageAnon(new))
256 remove_anon_migration_ptes(old, new);
257 else
258 remove_file_migration_ptes(old, new);
259}
260
261/*
Christoph Lameter06972122006-06-23 02:03:35 -0700262 * Something used the pte of a page under migration. We need to
263 * get to the page and wait until migration is finished.
264 * When we return from this function the fault will be retried.
265 *
266 * This function is called from do_swap_page().
267 */
268void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
269 unsigned long address)
270{
271 pte_t *ptep, pte;
272 spinlock_t *ptl;
273 swp_entry_t entry;
274 struct page *page;
275
276 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
277 pte = *ptep;
278 if (!is_swap_pte(pte))
279 goto out;
280
281 entry = pte_to_swp_entry(pte);
282 if (!is_migration_entry(entry))
283 goto out;
284
285 page = migration_entry_to_page(entry);
286
287 get_page(page);
288 pte_unmap_unlock(ptep, ptl);
289 wait_on_page_locked(page);
290 put_page(page);
291 return;
292out:
293 pte_unmap_unlock(ptep, ptl);
294}
295
Christoph Lameterb20a3502006-03-22 00:09:12 -0800296/*
Christoph Lameterc3fcf8a2006-06-23 02:03:32 -0700297 * Replace the page in the mapping.
Christoph Lameter5b5c7122006-06-23 02:03:29 -0700298 *
299 * The number of remaining references must be:
300 * 1 for anonymous pages without a mapping
301 * 2 for pages with a mapping
302 * 3 for pages with a mapping and PagePrivate set.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800303 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700304static int migrate_page_move_mapping(struct address_space *mapping,
305 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800306{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800307 void **pslot;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800308
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700309 if (!mapping) {
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700310 /* Anonymous page without mapping */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700311 if (page_count(page) != 1)
312 return -EAGAIN;
313 return 0;
314 }
315
Christoph Lameterb20a3502006-03-22 00:09:12 -0800316 write_lock_irq(&mapping->tree_lock);
317
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800318 pslot = radix_tree_lookup_slot(&mapping->page_tree,
319 page_index(page));
Christoph Lameterb20a3502006-03-22 00:09:12 -0800320
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700321 if (page_count(page) != 2 + !!PagePrivate(page) ||
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800322 (struct page *)radix_tree_deref_slot(pslot) != page) {
Christoph Lameterb20a3502006-03-22 00:09:12 -0800323 write_unlock_irq(&mapping->tree_lock);
Christoph Lametere23ca002006-04-10 22:52:57 -0700324 return -EAGAIN;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800325 }
326
327 /*
328 * Now we know that no one else is looking at the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800329 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800330 get_page(newpage); /* add cache reference */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700331#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800332 if (PageSwapCache(page)) {
333 SetPageSwapCache(newpage);
334 set_page_private(newpage, page_private(page));
335 }
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700336#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800337
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800338 radix_tree_replace_slot(pslot, newpage);
339
340 /*
341 * Drop cache reference from old page.
342 * We know this isn't the last reference.
343 */
Christoph Lameterb20a3502006-03-22 00:09:12 -0800344 __put_page(page);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800345
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700346 /*
347 * If moved to a different zone then also account
348 * the page for that zone. Other VM counters will be
349 * taken care of when we establish references to the
350 * new page and drop references to the old page.
351 *
352 * Note that anonymous pages are accounted for
353 * via NR_FILE_PAGES and NR_ANON_PAGES if they
354 * are mapped to swap space.
355 */
356 __dec_zone_page_state(page, NR_FILE_PAGES);
357 __inc_zone_page_state(newpage, NR_FILE_PAGES);
358
Christoph Lameterb20a3502006-03-22 00:09:12 -0800359 write_unlock_irq(&mapping->tree_lock);
360
361 return 0;
362}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800363
364/*
365 * Copy the page to its new location
366 */
Christoph Lametere7340f72006-06-23 02:03:29 -0700367static void migrate_page_copy(struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800368{
369 copy_highpage(newpage, page);
370
371 if (PageError(page))
372 SetPageError(newpage);
373 if (PageReferenced(page))
374 SetPageReferenced(newpage);
375 if (PageUptodate(page))
376 SetPageUptodate(newpage);
377 if (PageActive(page))
378 SetPageActive(newpage);
379 if (PageChecked(page))
380 SetPageChecked(newpage);
381 if (PageMappedToDisk(page))
382 SetPageMappedToDisk(newpage);
383
384 if (PageDirty(page)) {
385 clear_page_dirty_for_io(page);
386 set_page_dirty(newpage);
387 }
388
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700389#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800390 ClearPageSwapCache(page);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700391#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800392 ClearPageActive(page);
393 ClearPagePrivate(page);
394 set_page_private(page, 0);
395 page->mapping = NULL;
396
397 /*
398 * If any waiters have accumulated on the new page then
399 * wake them up.
400 */
401 if (PageWriteback(newpage))
402 end_page_writeback(newpage);
403}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800404
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700405/************************************************************
406 * Migration functions
407 ***********************************************************/
408
409/* Always fail migration. Used for mappings that are not movable */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700410int fail_migrate_page(struct address_space *mapping,
411 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700412{
413 return -EIO;
414}
415EXPORT_SYMBOL(fail_migrate_page);
416
Christoph Lameterb20a3502006-03-22 00:09:12 -0800417/*
418 * Common logic to directly migrate a single page suitable for
419 * pages that do not use PagePrivate.
420 *
421 * Pages are locked upon entry and exit.
422 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700423int migrate_page(struct address_space *mapping,
424 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800425{
426 int rc;
427
428 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
429
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700430 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800431
432 if (rc)
433 return rc;
434
435 migrate_page_copy(newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800436 return 0;
437}
438EXPORT_SYMBOL(migrate_page);
439
David Howells93614012006-09-30 20:45:40 +0200440#ifdef CONFIG_BLOCK
Christoph Lameterb20a3502006-03-22 00:09:12 -0800441/*
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700442 * Migration function for pages with buffers. This function can only be used
443 * if the underlying filesystem guarantees that no other references to "page"
444 * exist.
445 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700446int buffer_migrate_page(struct address_space *mapping,
447 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700448{
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700449 struct buffer_head *bh, *head;
450 int rc;
451
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700452 if (!page_has_buffers(page))
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700453 return migrate_page(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700454
455 head = page_buffers(page);
456
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700457 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700458
459 if (rc)
460 return rc;
461
462 bh = head;
463 do {
464 get_bh(bh);
465 lock_buffer(bh);
466 bh = bh->b_this_page;
467
468 } while (bh != head);
469
470 ClearPagePrivate(page);
471 set_page_private(newpage, page_private(page));
472 set_page_private(page, 0);
473 put_page(page);
474 get_page(newpage);
475
476 bh = head;
477 do {
478 set_bh_page(bh, newpage, bh_offset(bh));
479 bh = bh->b_this_page;
480
481 } while (bh != head);
482
483 SetPagePrivate(newpage);
484
485 migrate_page_copy(newpage, page);
486
487 bh = head;
488 do {
489 unlock_buffer(bh);
490 put_bh(bh);
491 bh = bh->b_this_page;
492
493 } while (bh != head);
494
495 return 0;
496}
497EXPORT_SYMBOL(buffer_migrate_page);
David Howells93614012006-09-30 20:45:40 +0200498#endif
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700499
Christoph Lameter04e62a22006-06-23 02:03:38 -0700500/*
501 * Writeback a page to clean the dirty state
502 */
503static int writeout(struct address_space *mapping, struct page *page)
504{
505 struct writeback_control wbc = {
506 .sync_mode = WB_SYNC_NONE,
507 .nr_to_write = 1,
508 .range_start = 0,
509 .range_end = LLONG_MAX,
510 .nonblocking = 1,
511 .for_reclaim = 1
512 };
513 int rc;
514
515 if (!mapping->a_ops->writepage)
516 /* No write method for the address space */
517 return -EINVAL;
518
519 if (!clear_page_dirty_for_io(page))
520 /* Someone else already triggered a write */
521 return -EAGAIN;
522
523 /*
524 * A dirty page may imply that the underlying filesystem has
525 * the page on some queue. So the page must be clean for
526 * migration. Writeout may mean we loose the lock and the
527 * page state is no longer what we checked for earlier.
528 * At this point we know that the migration attempt cannot
529 * be successful.
530 */
531 remove_migration_ptes(page, page);
532
533 rc = mapping->a_ops->writepage(page, &wbc);
534 if (rc < 0)
535 /* I/O Error writing */
536 return -EIO;
537
538 if (rc != AOP_WRITEPAGE_ACTIVATE)
539 /* unlocked. Relock */
540 lock_page(page);
541
542 return -EAGAIN;
543}
544
545/*
546 * Default handling if a filesystem does not provide a migration function.
547 */
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700548static int fallback_migrate_page(struct address_space *mapping,
549 struct page *newpage, struct page *page)
550{
Christoph Lameter04e62a22006-06-23 02:03:38 -0700551 if (PageDirty(page))
552 return writeout(mapping, page);
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700553
554 /*
555 * Buffers may be managed in a filesystem specific way.
556 * We must have no buffers or drop them.
557 */
David Howellsb398f6b2006-08-29 19:05:58 +0100558 if (PagePrivate(page) &&
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700559 !try_to_release_page(page, GFP_KERNEL))
560 return -EAGAIN;
561
562 return migrate_page(mapping, newpage, page);
563}
564
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700565/*
Christoph Lametere24f0b82006-06-23 02:03:51 -0700566 * Move a page to a newly allocated page
567 * The page is locked and all ptes have been successfully removed.
568 *
569 * The new page will have replaced the old page if this function
570 * is successful.
571 */
572static int move_to_new_page(struct page *newpage, struct page *page)
573{
574 struct address_space *mapping;
575 int rc;
576
577 /*
578 * Block others from accessing the page when we get around to
579 * establishing additional references. We are the only one
580 * holding a reference to the new page at this point.
581 */
582 if (TestSetPageLocked(newpage))
583 BUG();
584
585 /* Prepare mapping for the new page.*/
586 newpage->index = page->index;
587 newpage->mapping = page->mapping;
588
589 mapping = page_mapping(page);
590 if (!mapping)
591 rc = migrate_page(mapping, newpage, page);
592 else if (mapping->a_ops->migratepage)
593 /*
594 * Most pages have a mapping and most filesystems
595 * should provide a migration function. Anonymous
596 * pages are part of swap space which also has its
597 * own migration function. This is the most common
598 * path for page migration.
599 */
600 rc = mapping->a_ops->migratepage(mapping,
601 newpage, page);
602 else
603 rc = fallback_migrate_page(mapping, newpage, page);
604
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800605 if (!rc) {
606 mem_cgroup_page_migration(page, newpage);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700607 remove_migration_ptes(page, newpage);
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800608 } else
Christoph Lametere24f0b82006-06-23 02:03:51 -0700609 newpage->mapping = NULL;
610
611 unlock_page(newpage);
612
613 return rc;
614}
615
616/*
617 * Obtain the lock on page, remove all ptes and migrate the page
618 * to the newly allocated page in newpage.
619 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700620static int unmap_and_move(new_page_t get_new_page, unsigned long private,
621 struct page *page, int force)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700622{
623 int rc = 0;
Christoph Lameter742755a2006-06-23 02:03:55 -0700624 int *result = NULL;
625 struct page *newpage = get_new_page(page, private, &result);
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700626 int rcu_locked = 0;
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800627 int charge = 0;
Christoph Lameter95a402c2006-06-23 02:03:53 -0700628
629 if (!newpage)
630 return -ENOMEM;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700631
632 if (page_count(page) == 1)
633 /* page was freed from under us. So we are done. */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700634 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700635
636 rc = -EAGAIN;
637 if (TestSetPageLocked(page)) {
638 if (!force)
Christoph Lameter95a402c2006-06-23 02:03:53 -0700639 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700640 lock_page(page);
641 }
642
643 if (PageWriteback(page)) {
644 if (!force)
645 goto unlock;
646 wait_on_page_writeback(page);
647 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700648 /*
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700649 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
650 * we cannot notice that anon_vma is freed while we migrates a page.
651 * This rcu_read_lock() delays freeing anon_vma pointer until the end
652 * of migration. File cache pages are no problem because of page_lock()
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700653 * File Caches may use write_page() or lock_page() in migration, then,
654 * just care Anon page here.
Christoph Lametere24f0b82006-06-23 02:03:51 -0700655 */
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700656 if (PageAnon(page)) {
657 rcu_read_lock();
658 rcu_locked = 1;
659 }
Shaohua Li62e1c552008-02-04 22:29:33 -0800660
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700661 /*
Shaohua Li62e1c552008-02-04 22:29:33 -0800662 * Corner case handling:
663 * 1. When a new swap-cache page is read into, it is added to the LRU
664 * and treated as swapcache but it has no rmap yet.
665 * Calling try_to_unmap() against a page->mapping==NULL page will
666 * trigger a BUG. So handle it here.
667 * 2. An orphaned page (see truncate_complete_page) might have
668 * fs-private metadata. The page can be picked up due to memory
669 * offlining. Everywhere else except page reclaim, the page is
670 * invisible to the vm, so the page can not be migrated. So try to
671 * free the metadata, so the page can be freed.
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700672 */
Shaohua Li62e1c552008-02-04 22:29:33 -0800673 if (!page->mapping) {
674 if (!PageAnon(page) && PagePrivate(page)) {
675 /*
676 * Go direct to try_to_free_buffers() here because
677 * a) that's what try_to_release_page() would do anyway
678 * b) we may be under rcu_read_lock() here, so we can't
679 * use GFP_KERNEL which is what try_to_release_page()
680 * needs to be effective.
681 */
682 try_to_free_buffers(page);
683 }
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700684 goto rcu_unlock;
Shaohua Li62e1c552008-02-04 22:29:33 -0800685 }
686
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800687 charge = mem_cgroup_prepare_migration(page);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700688 /* Establish migration ptes or remove ptes */
Christoph Lametere6a15302006-06-25 05:46:49 -0700689 try_to_unmap(page, 1);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700690
Christoph Lametere6a15302006-06-25 05:46:49 -0700691 if (!page_mapped(page))
692 rc = move_to_new_page(newpage, page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700693
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800694 if (rc) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700695 remove_migration_ptes(page, page);
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800696 if (charge)
697 mem_cgroup_end_migration(page);
698 } else if (charge)
699 mem_cgroup_end_migration(newpage);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700700rcu_unlock:
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700701 if (rcu_locked)
702 rcu_read_unlock();
Christoph Lametere6a15302006-06-25 05:46:49 -0700703
Christoph Lametere24f0b82006-06-23 02:03:51 -0700704unlock:
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700705
Christoph Lametere24f0b82006-06-23 02:03:51 -0700706 unlock_page(page);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700707
Christoph Lametere24f0b82006-06-23 02:03:51 -0700708 if (rc != -EAGAIN) {
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700709 /*
710 * A page that has been migrated has all references
711 * removed and will be freed. A page that has not been
712 * migrated will have kepts its references and be
713 * restored.
714 */
715 list_del(&page->lru);
716 move_to_lru(page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700717 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700718
719move_newpage:
720 /*
721 * Move the new page to the LRU. If migration was not successful
722 * then this will free the page.
723 */
724 move_to_lru(newpage);
Christoph Lameter742755a2006-06-23 02:03:55 -0700725 if (result) {
726 if (rc)
727 *result = rc;
728 else
729 *result = page_to_nid(newpage);
730 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700731 return rc;
732}
733
734/*
Christoph Lameterb20a3502006-03-22 00:09:12 -0800735 * migrate_pages
736 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700737 * The function takes one list of pages to migrate and a function
738 * that determines from the page to be migrated and the private data
739 * the target of the move and allocates the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800740 *
741 * The function returns after 10 attempts or if no pages
742 * are movable anymore because to has become empty
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700743 * or no retryable pages exist anymore. All pages will be
Gabriel Craciunescue9534b32007-10-20 02:13:26 +0200744 * returned to the LRU or freed.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800745 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700746 * Return: Number of pages not migrated or error code.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800747 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700748int migrate_pages(struct list_head *from,
749 new_page_t get_new_page, unsigned long private)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800750{
Christoph Lametere24f0b82006-06-23 02:03:51 -0700751 int retry = 1;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800752 int nr_failed = 0;
753 int pass = 0;
754 struct page *page;
755 struct page *page2;
756 int swapwrite = current->flags & PF_SWAPWRITE;
757 int rc;
758
759 if (!swapwrite)
760 current->flags |= PF_SWAPWRITE;
761
Christoph Lametere24f0b82006-06-23 02:03:51 -0700762 for(pass = 0; pass < 10 && retry; pass++) {
763 retry = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800764
Christoph Lametere24f0b82006-06-23 02:03:51 -0700765 list_for_each_entry_safe(page, page2, from, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700766 cond_resched();
Christoph Lameterb20a3502006-03-22 00:09:12 -0800767
Christoph Lameter95a402c2006-06-23 02:03:53 -0700768 rc = unmap_and_move(get_new_page, private,
769 page, pass > 2);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800770
Christoph Lametere24f0b82006-06-23 02:03:51 -0700771 switch(rc) {
Christoph Lameter95a402c2006-06-23 02:03:53 -0700772 case -ENOMEM:
773 goto out;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700774 case -EAGAIN:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700775 retry++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700776 break;
777 case 0:
Christoph Lametere24f0b82006-06-23 02:03:51 -0700778 break;
779 default:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700780 /* Permanent failure */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700781 nr_failed++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700782 break;
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700783 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800784 }
785 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700786 rc = 0;
787out:
Christoph Lameterb20a3502006-03-22 00:09:12 -0800788 if (!swapwrite)
789 current->flags &= ~PF_SWAPWRITE;
790
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700791 putback_lru_pages(from);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700792
793 if (rc)
794 return rc;
795
Christoph Lameterb20a3502006-03-22 00:09:12 -0800796 return nr_failed + retry;
797}
798
Christoph Lameter742755a2006-06-23 02:03:55 -0700799#ifdef CONFIG_NUMA
800/*
801 * Move a list of individual pages
802 */
803struct page_to_node {
804 unsigned long addr;
805 struct page *page;
806 int node;
807 int status;
808};
809
810static struct page *new_page_node(struct page *p, unsigned long private,
811 int **result)
812{
813 struct page_to_node *pm = (struct page_to_node *)private;
814
815 while (pm->node != MAX_NUMNODES && pm->page != p)
816 pm++;
817
818 if (pm->node == MAX_NUMNODES)
819 return NULL;
820
821 *result = &pm->status;
822
Mel Gorman769848c2007-07-17 04:03:05 -0700823 return alloc_pages_node(pm->node,
824 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
Christoph Lameter742755a2006-06-23 02:03:55 -0700825}
826
827/*
828 * Move a set of pages as indicated in the pm array. The addr
829 * field must be set to the virtual address of the page to be moved
830 * and the node number must contain a valid target node.
831 */
832static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
833 int migrate_all)
834{
835 int err;
836 struct page_to_node *pp;
837 LIST_HEAD(pagelist);
838
839 down_read(&mm->mmap_sem);
840
841 /*
842 * Build a list of pages to migrate
843 */
844 migrate_prep();
845 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
846 struct vm_area_struct *vma;
847 struct page *page;
848
849 /*
850 * A valid page pointer that will not match any of the
851 * pages that will be moved.
852 */
853 pp->page = ZERO_PAGE(0);
854
855 err = -EFAULT;
856 vma = find_vma(mm, pp->addr);
Christoph Lameter0dc952d2007-03-05 00:30:33 -0800857 if (!vma || !vma_migratable(vma))
Christoph Lameter742755a2006-06-23 02:03:55 -0700858 goto set_status;
859
860 page = follow_page(vma, pp->addr, FOLL_GET);
861 err = -ENOENT;
862 if (!page)
863 goto set_status;
864
865 if (PageReserved(page)) /* Check for zero page */
866 goto put_and_set;
867
868 pp->page = page;
869 err = page_to_nid(page);
870
871 if (err == pp->node)
872 /*
873 * Node already in the right place
874 */
875 goto put_and_set;
876
877 err = -EACCES;
878 if (page_mapcount(page) > 1 &&
879 !migrate_all)
880 goto put_and_set;
881
882 err = isolate_lru_page(page, &pagelist);
883put_and_set:
884 /*
885 * Either remove the duplicate refcount from
886 * isolate_lru_page() or drop the page ref if it was
887 * not isolated.
888 */
889 put_page(page);
890set_status:
891 pp->status = err;
892 }
893
894 if (!list_empty(&pagelist))
895 err = migrate_pages(&pagelist, new_page_node,
896 (unsigned long)pm);
897 else
898 err = -ENOENT;
899
900 up_read(&mm->mmap_sem);
901 return err;
902}
903
904/*
905 * Determine the nodes of a list of pages. The addr in the pm array
906 * must have been set to the virtual address of which we want to determine
907 * the node number.
908 */
909static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
910{
911 down_read(&mm->mmap_sem);
912
913 for ( ; pm->node != MAX_NUMNODES; pm++) {
914 struct vm_area_struct *vma;
915 struct page *page;
916 int err;
917
918 err = -EFAULT;
919 vma = find_vma(mm, pm->addr);
920 if (!vma)
921 goto set_status;
922
923 page = follow_page(vma, pm->addr, 0);
924 err = -ENOENT;
925 /* Use PageReserved to check for zero page */
926 if (!page || PageReserved(page))
927 goto set_status;
928
929 err = page_to_nid(page);
930set_status:
931 pm->status = err;
932 }
933
934 up_read(&mm->mmap_sem);
935 return 0;
936}
937
938/*
939 * Move a list of pages in the address space of the currently executing
940 * process.
941 */
942asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
943 const void __user * __user *pages,
944 const int __user *nodes,
945 int __user *status, int flags)
946{
947 int err = 0;
948 int i;
949 struct task_struct *task;
950 nodemask_t task_nodes;
951 struct mm_struct *mm;
952 struct page_to_node *pm = NULL;
953
954 /* Check flags */
955 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
956 return -EINVAL;
957
958 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
959 return -EPERM;
960
961 /* Find the mm_struct */
962 read_lock(&tasklist_lock);
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700963 task = pid ? find_task_by_vpid(pid) : current;
Christoph Lameter742755a2006-06-23 02:03:55 -0700964 if (!task) {
965 read_unlock(&tasklist_lock);
966 return -ESRCH;
967 }
968 mm = get_task_mm(task);
969 read_unlock(&tasklist_lock);
970
971 if (!mm)
972 return -EINVAL;
973
974 /*
975 * Check if this process has the right to modify the specified
976 * process. The right exists if the process has administrative
977 * capabilities, superuser privileges or the same
978 * userid as the target process.
979 */
980 if ((current->euid != task->suid) && (current->euid != task->uid) &&
981 (current->uid != task->suid) && (current->uid != task->uid) &&
982 !capable(CAP_SYS_NICE)) {
983 err = -EPERM;
984 goto out2;
985 }
986
David Quigley86c3a762006-06-23 02:04:02 -0700987 err = security_task_movememory(task);
988 if (err)
989 goto out2;
990
991
Christoph Lameter742755a2006-06-23 02:03:55 -0700992 task_nodes = cpuset_mems_allowed(task);
993
994 /* Limit nr_pages so that the multiplication may not overflow */
995 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
996 err = -E2BIG;
997 goto out2;
998 }
999
1000 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
1001 if (!pm) {
1002 err = -ENOMEM;
1003 goto out2;
1004 }
1005
1006 /*
1007 * Get parameters from user space and initialize the pm
1008 * array. Return various errors if the user did something wrong.
1009 */
1010 for (i = 0; i < nr_pages; i++) {
Al Viro9d966d42007-10-14 19:34:10 +01001011 const void __user *p;
Christoph Lameter742755a2006-06-23 02:03:55 -07001012
1013 err = -EFAULT;
1014 if (get_user(p, pages + i))
1015 goto out;
1016
1017 pm[i].addr = (unsigned long)p;
1018 if (nodes) {
1019 int node;
1020
1021 if (get_user(node, nodes + i))
1022 goto out;
1023
1024 err = -ENODEV;
Christoph Lameter56bbd652007-10-16 01:25:35 -07001025 if (!node_state(node, N_HIGH_MEMORY))
Christoph Lameter742755a2006-06-23 02:03:55 -07001026 goto out;
1027
1028 err = -EACCES;
1029 if (!node_isset(node, task_nodes))
1030 goto out;
1031
1032 pm[i].node = node;
Stephen Rothwell8ce08462006-11-02 22:07:28 -08001033 } else
1034 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
Christoph Lameter742755a2006-06-23 02:03:55 -07001035 }
1036 /* End marker */
1037 pm[nr_pages].node = MAX_NUMNODES;
1038
1039 if (nodes)
1040 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
1041 else
1042 err = do_pages_stat(mm, pm);
1043
1044 if (err >= 0)
1045 /* Return status information */
1046 for (i = 0; i < nr_pages; i++)
1047 if (put_user(pm[i].status, status + i))
1048 err = -EFAULT;
1049
1050out:
1051 vfree(pm);
1052out2:
1053 mmput(mm);
1054 return err;
1055}
1056#endif
1057
Christoph Lameter7b2259b2006-06-25 05:46:48 -07001058/*
1059 * Call migration functions in the vma_ops that may prepare
1060 * memory in a vm for migration. migration functions may perform
1061 * the migration for vmas that do not have an underlying page struct.
1062 */
1063int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1064 const nodemask_t *from, unsigned long flags)
1065{
1066 struct vm_area_struct *vma;
1067 int err = 0;
1068
1069 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
1070 if (vma->vm_ops && vma->vm_ops->migrate) {
1071 err = vma->vm_ops->migrate(vma, to, from, flags);
1072 if (err)
1073 break;
1074 }
1075 }
1076 return err;
1077}