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b20a3503
CL
1/*
2 * Memory Migration functionality - linux/mm/migration.c
3 *
4 * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
5 *
6 * Page migration was first developed in the context of the memory hotplug
7 * project. The main authors of the migration code are:
8 *
9 * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
10 * Hirokazu Takahashi <taka@valinux.co.jp>
11 * Dave Hansen <haveblue@us.ibm.com>
12 * Christoph Lameter <clameter@sgi.com>
13 */
14
15#include <linux/migrate.h>
16#include <linux/module.h>
17#include <linux/swap.h>
0697212a 18#include <linux/swapops.h>
b20a3503 19#include <linux/pagemap.h>
e23ca00b 20#include <linux/buffer_head.h>
b20a3503 21#include <linux/mm_inline.h>
b488893a 22#include <linux/nsproxy.h>
b20a3503
CL
23#include <linux/pagevec.h>
24#include <linux/rmap.h>
25#include <linux/topology.h>
26#include <linux/cpu.h>
27#include <linux/cpuset.h>
04e62a29 28#include <linux/writeback.h>
742755a1
CL
29#include <linux/mempolicy.h>
30#include <linux/vmalloc.h>
86c3a764 31#include <linux/security.h>
8a9f3ccd 32#include <linux/memcontrol.h>
b20a3503
CL
33
34#include "internal.h"
35
b20a3503
CL
36#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);
3dd9fe8c 54 if (PageLRU(page) && get_page_unless_zero(page)) {
b20a3503 55 ret = 0;
b20a3503
CL
56 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/*
742755a1
CL
69 * migrate_prep() needs to be called before we start compiling a list of pages
70 * to be migrated using isolate_lru_page().
b20a3503
CL
71 */
72int migrate_prep(void)
73{
b20a3503
CL
74 /*
75 * Clear the LRU lists so pages can be isolated.
76 * Note that pages may be moved off the LRU after we have
77 * drained them. Those pages will fail to migrate like other
78 * pages that may be busy.
79 */
80 lru_add_drain_all();
81
82 return 0;
83}
84
85static inline void move_to_lru(struct page *page)
86{
b20a3503
CL
87 if (PageActive(page)) {
88 /*
89 * lru_cache_add_active checks that
90 * the PG_active bit is off.
91 */
92 ClearPageActive(page);
93 lru_cache_add_active(page);
94 } else {
95 lru_cache_add(page);
96 }
97 put_page(page);
98}
99
100/*
101 * Add isolated pages on the list back to the LRU.
102 *
103 * returns the number of pages put back.
104 */
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) {
e24f0b8f 112 list_del(&page->lru);
b20a3503
CL
113 move_to_lru(page);
114 count++;
115 }
116 return count;
117}
118
0697212a
CL
119/*
120 * Restore a potential migration pte to a working pte entry
121 */
04e62a29 122static void remove_migration_pte(struct vm_area_struct *vma,
0697212a
CL
123 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;
04e62a29
CL
132 unsigned long addr = page_address_in_vma(new, vma);
133
134 if (addr == -EFAULT)
135 return;
0697212a
CL
136
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
98837c7f
HD
167 /*
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
0697212a
CL
181 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);
97ee0524 185 flush_cache_page(vma, addr, pte_pfn(pte));
0697212a 186 set_pte_at(mm, addr, ptep, pte);
04e62a29
CL
187
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);
04e62a29 195
0697212a
CL
196out:
197 pte_unmap_unlock(ptep, ptl);
198}
199
200/*
04e62a29
CL
201 * 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/*
0697212a
CL
223 * Must hold mmap_sem lock on at least one of the vmas containing
224 * the page so that the anon_vma cannot vanish.
225 */
04e62a29 226static void remove_anon_migration_ptes(struct page *old, struct page *new)
0697212a
CL
227{
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)
04e62a29 244 remove_migration_pte(vma, old, new);
0697212a
CL
245
246 spin_unlock(&anon_vma->lock);
247}
248
04e62a29
CL
249/*
250 * 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
0697212a
CL
261/*
262 * 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
b20a3503 296/*
c3fcf8a5 297 * Replace the page in the mapping.
5b5c7120
CL
298 *
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.
b20a3503 303 */
2d1db3b1
CL
304static int migrate_page_move_mapping(struct address_space *mapping,
305 struct page *newpage, struct page *page)
b20a3503 306{
7cf9c2c7 307 void **pslot;
b20a3503 308
6c5240ae 309 if (!mapping) {
0e8c7d0f 310 /* Anonymous page without mapping */
6c5240ae
CL
311 if (page_count(page) != 1)
312 return -EAGAIN;
313 return 0;
314 }
315
b20a3503
CL
316 write_lock_irq(&mapping->tree_lock);
317
7cf9c2c7
NP
318 pslot = radix_tree_lookup_slot(&mapping->page_tree,
319 page_index(page));
b20a3503 320
6c5240ae 321 if (page_count(page) != 2 + !!PagePrivate(page) ||
7cf9c2c7 322 (struct page *)radix_tree_deref_slot(pslot) != page) {
b20a3503 323 write_unlock_irq(&mapping->tree_lock);
e23ca00b 324 return -EAGAIN;
b20a3503
CL
325 }
326
327 /*
328 * Now we know that no one else is looking at the page.
b20a3503 329 */
7cf9c2c7 330 get_page(newpage); /* add cache reference */
6c5240ae 331#ifdef CONFIG_SWAP
b20a3503
CL
332 if (PageSwapCache(page)) {
333 SetPageSwapCache(newpage);
334 set_page_private(newpage, page_private(page));
335 }
6c5240ae 336#endif
b20a3503 337
7cf9c2c7
NP
338 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 */
b20a3503 344 __put_page(page);
7cf9c2c7 345
0e8c7d0f
CL
346 /*
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
b20a3503
CL
359 write_unlock_irq(&mapping->tree_lock);
360
361 return 0;
362}
b20a3503
CL
363
364/*
365 * Copy the page to its new location
366 */
e7340f73 367static void migrate_page_copy(struct page *newpage, struct page *page)
b20a3503
CL
368{
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);
3a902c5f
NP
386 /*
387 * Want to mark the page and the radix tree as dirty, and
388 * redo the accounting that clear_page_dirty_for_io undid,
389 * but we can't use set_page_dirty because that function
390 * is actually a signal that all of the page has become dirty.
391 * Wheras only part of our page may be dirty.
392 */
393 __set_page_dirty_nobuffers(newpage);
b20a3503
CL
394 }
395
6c5240ae 396#ifdef CONFIG_SWAP
b20a3503 397 ClearPageSwapCache(page);
6c5240ae 398#endif
b20a3503
CL
399 ClearPageActive(page);
400 ClearPagePrivate(page);
401 set_page_private(page, 0);
402 page->mapping = NULL;
403
404 /*
405 * If any waiters have accumulated on the new page then
406 * wake them up.
407 */
408 if (PageWriteback(newpage))
409 end_page_writeback(newpage);
410}
b20a3503 411
1d8b85cc
CL
412/************************************************************
413 * Migration functions
414 ***********************************************************/
415
416/* Always fail migration. Used for mappings that are not movable */
2d1db3b1
CL
417int fail_migrate_page(struct address_space *mapping,
418 struct page *newpage, struct page *page)
1d8b85cc
CL
419{
420 return -EIO;
421}
422EXPORT_SYMBOL(fail_migrate_page);
423
b20a3503
CL
424/*
425 * Common logic to directly migrate a single page suitable for
426 * pages that do not use PagePrivate.
427 *
428 * Pages are locked upon entry and exit.
429 */
2d1db3b1
CL
430int migrate_page(struct address_space *mapping,
431 struct page *newpage, struct page *page)
b20a3503
CL
432{
433 int rc;
434
435 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
436
2d1db3b1 437 rc = migrate_page_move_mapping(mapping, newpage, page);
b20a3503
CL
438
439 if (rc)
440 return rc;
441
442 migrate_page_copy(newpage, page);
b20a3503
CL
443 return 0;
444}
445EXPORT_SYMBOL(migrate_page);
446
9361401e 447#ifdef CONFIG_BLOCK
1d8b85cc
CL
448/*
449 * Migration function for pages with buffers. This function can only be used
450 * if the underlying filesystem guarantees that no other references to "page"
451 * exist.
452 */
2d1db3b1
CL
453int buffer_migrate_page(struct address_space *mapping,
454 struct page *newpage, struct page *page)
1d8b85cc 455{
1d8b85cc
CL
456 struct buffer_head *bh, *head;
457 int rc;
458
1d8b85cc 459 if (!page_has_buffers(page))
2d1db3b1 460 return migrate_page(mapping, newpage, page);
1d8b85cc
CL
461
462 head = page_buffers(page);
463
2d1db3b1 464 rc = migrate_page_move_mapping(mapping, newpage, page);
1d8b85cc
CL
465
466 if (rc)
467 return rc;
468
469 bh = head;
470 do {
471 get_bh(bh);
472 lock_buffer(bh);
473 bh = bh->b_this_page;
474
475 } while (bh != head);
476
477 ClearPagePrivate(page);
478 set_page_private(newpage, page_private(page));
479 set_page_private(page, 0);
480 put_page(page);
481 get_page(newpage);
482
483 bh = head;
484 do {
485 set_bh_page(bh, newpage, bh_offset(bh));
486 bh = bh->b_this_page;
487
488 } while (bh != head);
489
490 SetPagePrivate(newpage);
491
492 migrate_page_copy(newpage, page);
493
494 bh = head;
495 do {
496 unlock_buffer(bh);
497 put_bh(bh);
498 bh = bh->b_this_page;
499
500 } while (bh != head);
501
502 return 0;
503}
504EXPORT_SYMBOL(buffer_migrate_page);
9361401e 505#endif
1d8b85cc 506
04e62a29
CL
507/*
508 * Writeback a page to clean the dirty state
509 */
510static int writeout(struct address_space *mapping, struct page *page)
8351a6e4 511{
04e62a29
CL
512 struct writeback_control wbc = {
513 .sync_mode = WB_SYNC_NONE,
514 .nr_to_write = 1,
515 .range_start = 0,
516 .range_end = LLONG_MAX,
517 .nonblocking = 1,
518 .for_reclaim = 1
519 };
520 int rc;
521
522 if (!mapping->a_ops->writepage)
523 /* No write method for the address space */
524 return -EINVAL;
525
526 if (!clear_page_dirty_for_io(page))
527 /* Someone else already triggered a write */
528 return -EAGAIN;
529
8351a6e4 530 /*
04e62a29
CL
531 * A dirty page may imply that the underlying filesystem has
532 * the page on some queue. So the page must be clean for
533 * migration. Writeout may mean we loose the lock and the
534 * page state is no longer what we checked for earlier.
535 * At this point we know that the migration attempt cannot
536 * be successful.
8351a6e4 537 */
04e62a29 538 remove_migration_ptes(page, page);
8351a6e4 539
04e62a29
CL
540 rc = mapping->a_ops->writepage(page, &wbc);
541 if (rc < 0)
542 /* I/O Error writing */
543 return -EIO;
8351a6e4 544
04e62a29
CL
545 if (rc != AOP_WRITEPAGE_ACTIVATE)
546 /* unlocked. Relock */
547 lock_page(page);
548
549 return -EAGAIN;
550}
551
552/*
553 * Default handling if a filesystem does not provide a migration function.
554 */
555static int fallback_migrate_page(struct address_space *mapping,
556 struct page *newpage, struct page *page)
557{
558 if (PageDirty(page))
559 return writeout(mapping, page);
8351a6e4
CL
560
561 /*
562 * Buffers may be managed in a filesystem specific way.
563 * We must have no buffers or drop them.
564 */
b398f6bf 565 if (PagePrivate(page) &&
8351a6e4
CL
566 !try_to_release_page(page, GFP_KERNEL))
567 return -EAGAIN;
568
569 return migrate_page(mapping, newpage, page);
570}
571
e24f0b8f
CL
572/*
573 * Move a page to a newly allocated page
574 * The page is locked and all ptes have been successfully removed.
575 *
576 * The new page will have replaced the old page if this function
577 * is successful.
578 */
579static int move_to_new_page(struct page *newpage, struct page *page)
580{
581 struct address_space *mapping;
582 int rc;
583
584 /*
585 * Block others from accessing the page when we get around to
586 * establishing additional references. We are the only one
587 * holding a reference to the new page at this point.
588 */
589 if (TestSetPageLocked(newpage))
590 BUG();
591
592 /* Prepare mapping for the new page.*/
593 newpage->index = page->index;
594 newpage->mapping = page->mapping;
595
596 mapping = page_mapping(page);
597 if (!mapping)
598 rc = migrate_page(mapping, newpage, page);
599 else if (mapping->a_ops->migratepage)
600 /*
601 * Most pages have a mapping and most filesystems
602 * should provide a migration function. Anonymous
603 * pages are part of swap space which also has its
604 * own migration function. This is the most common
605 * path for page migration.
606 */
607 rc = mapping->a_ops->migratepage(mapping,
608 newpage, page);
609 else
610 rc = fallback_migrate_page(mapping, newpage, page);
611
ae41be37
KH
612 if (!rc) {
613 mem_cgroup_page_migration(page, newpage);
e24f0b8f 614 remove_migration_ptes(page, newpage);
ae41be37 615 } else
e24f0b8f
CL
616 newpage->mapping = NULL;
617
618 unlock_page(newpage);
619
620 return rc;
621}
622
623/*
624 * Obtain the lock on page, remove all ptes and migrate the page
625 * to the newly allocated page in newpage.
626 */
95a402c3
CL
627static int unmap_and_move(new_page_t get_new_page, unsigned long private,
628 struct page *page, int force)
e24f0b8f
CL
629{
630 int rc = 0;
742755a1
CL
631 int *result = NULL;
632 struct page *newpage = get_new_page(page, private, &result);
989f89c5 633 int rcu_locked = 0;
ae41be37 634 int charge = 0;
95a402c3
CL
635
636 if (!newpage)
637 return -ENOMEM;
e24f0b8f
CL
638
639 if (page_count(page) == 1)
640 /* page was freed from under us. So we are done. */
95a402c3 641 goto move_newpage;
e24f0b8f
CL
642
643 rc = -EAGAIN;
644 if (TestSetPageLocked(page)) {
645 if (!force)
95a402c3 646 goto move_newpage;
e24f0b8f
CL
647 lock_page(page);
648 }
649
650 if (PageWriteback(page)) {
651 if (!force)
652 goto unlock;
653 wait_on_page_writeback(page);
654 }
e24f0b8f 655 /*
dc386d4d
KH
656 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
657 * we cannot notice that anon_vma is freed while we migrates a page.
658 * This rcu_read_lock() delays freeing anon_vma pointer until the end
659 * of migration. File cache pages are no problem because of page_lock()
989f89c5
KH
660 * File Caches may use write_page() or lock_page() in migration, then,
661 * just care Anon page here.
dc386d4d 662 */
989f89c5
KH
663 if (PageAnon(page)) {
664 rcu_read_lock();
665 rcu_locked = 1;
666 }
62e1c553 667
dc386d4d 668 /*
62e1c553
SL
669 * Corner case handling:
670 * 1. When a new swap-cache page is read into, it is added to the LRU
671 * and treated as swapcache but it has no rmap yet.
672 * Calling try_to_unmap() against a page->mapping==NULL page will
673 * trigger a BUG. So handle it here.
674 * 2. An orphaned page (see truncate_complete_page) might have
675 * fs-private metadata. The page can be picked up due to memory
676 * offlining. Everywhere else except page reclaim, the page is
677 * invisible to the vm, so the page can not be migrated. So try to
678 * free the metadata, so the page can be freed.
e24f0b8f 679 */
62e1c553
SL
680 if (!page->mapping) {
681 if (!PageAnon(page) && PagePrivate(page)) {
682 /*
683 * Go direct to try_to_free_buffers() here because
684 * a) that's what try_to_release_page() would do anyway
685 * b) we may be under rcu_read_lock() here, so we can't
686 * use GFP_KERNEL which is what try_to_release_page()
687 * needs to be effective.
688 */
689 try_to_free_buffers(page);
690 }
dc386d4d 691 goto rcu_unlock;
62e1c553
SL
692 }
693
ae41be37 694 charge = mem_cgroup_prepare_migration(page);
dc386d4d 695 /* Establish migration ptes or remove ptes */
e6a1530d 696 try_to_unmap(page, 1);
dc386d4d 697
e6a1530d
CL
698 if (!page_mapped(page))
699 rc = move_to_new_page(newpage, page);
e24f0b8f 700
ae41be37 701 if (rc) {
e24f0b8f 702 remove_migration_ptes(page, page);
ae41be37
KH
703 if (charge)
704 mem_cgroup_end_migration(page);
705 } else if (charge)
706 mem_cgroup_end_migration(newpage);
dc386d4d 707rcu_unlock:
989f89c5
KH
708 if (rcu_locked)
709 rcu_read_unlock();
e6a1530d 710
e24f0b8f 711unlock:
dc386d4d 712
e24f0b8f 713 unlock_page(page);
95a402c3 714
e24f0b8f 715 if (rc != -EAGAIN) {
aaa994b3
CL
716 /*
717 * A page that has been migrated has all references
718 * removed and will be freed. A page that has not been
719 * migrated will have kepts its references and be
720 * restored.
721 */
722 list_del(&page->lru);
723 move_to_lru(page);
e24f0b8f 724 }
95a402c3
CL
725
726move_newpage:
727 /*
728 * Move the new page to the LRU. If migration was not successful
729 * then this will free the page.
730 */
731 move_to_lru(newpage);
742755a1
CL
732 if (result) {
733 if (rc)
734 *result = rc;
735 else
736 *result = page_to_nid(newpage);
737 }
e24f0b8f
CL
738 return rc;
739}
740
b20a3503
CL
741/*
742 * migrate_pages
743 *
95a402c3
CL
744 * The function takes one list of pages to migrate and a function
745 * that determines from the page to be migrated and the private data
746 * the target of the move and allocates the page.
b20a3503
CL
747 *
748 * The function returns after 10 attempts or if no pages
749 * are movable anymore because to has become empty
aaa994b3 750 * or no retryable pages exist anymore. All pages will be
e9534b3f 751 * returned to the LRU or freed.
b20a3503 752 *
95a402c3 753 * Return: Number of pages not migrated or error code.
b20a3503 754 */
95a402c3
CL
755int migrate_pages(struct list_head *from,
756 new_page_t get_new_page, unsigned long private)
b20a3503 757{
e24f0b8f 758 int retry = 1;
b20a3503
CL
759 int nr_failed = 0;
760 int pass = 0;
761 struct page *page;
762 struct page *page2;
763 int swapwrite = current->flags & PF_SWAPWRITE;
764 int rc;
765
766 if (!swapwrite)
767 current->flags |= PF_SWAPWRITE;
768
e24f0b8f
CL
769 for(pass = 0; pass < 10 && retry; pass++) {
770 retry = 0;
b20a3503 771
e24f0b8f 772 list_for_each_entry_safe(page, page2, from, lru) {
e24f0b8f 773 cond_resched();
2d1db3b1 774
95a402c3
CL
775 rc = unmap_and_move(get_new_page, private,
776 page, pass > 2);
2d1db3b1 777
e24f0b8f 778 switch(rc) {
95a402c3
CL
779 case -ENOMEM:
780 goto out;
e24f0b8f 781 case -EAGAIN:
2d1db3b1 782 retry++;
e24f0b8f
CL
783 break;
784 case 0:
e24f0b8f
CL
785 break;
786 default:
2d1db3b1 787 /* Permanent failure */
2d1db3b1 788 nr_failed++;
e24f0b8f 789 break;
2d1db3b1 790 }
b20a3503
CL
791 }
792 }
95a402c3
CL
793 rc = 0;
794out:
b20a3503
CL
795 if (!swapwrite)
796 current->flags &= ~PF_SWAPWRITE;
797
aaa994b3 798 putback_lru_pages(from);
b20a3503 799
95a402c3
CL
800 if (rc)
801 return rc;
b20a3503 802
95a402c3 803 return nr_failed + retry;
b20a3503 804}
95a402c3 805
742755a1
CL
806#ifdef CONFIG_NUMA
807/*
808 * Move a list of individual pages
809 */
810struct page_to_node {
811 unsigned long addr;
812 struct page *page;
813 int node;
814 int status;
815};
816
817static struct page *new_page_node(struct page *p, unsigned long private,
818 int **result)
819{
820 struct page_to_node *pm = (struct page_to_node *)private;
821
822 while (pm->node != MAX_NUMNODES && pm->page != p)
823 pm++;
824
825 if (pm->node == MAX_NUMNODES)
826 return NULL;
827
828 *result = &pm->status;
829
769848c0
MG
830 return alloc_pages_node(pm->node,
831 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
742755a1
CL
832}
833
834/*
835 * Move a set of pages as indicated in the pm array. The addr
836 * field must be set to the virtual address of the page to be moved
837 * and the node number must contain a valid target node.
838 */
839static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
840 int migrate_all)
841{
842 int err;
843 struct page_to_node *pp;
844 LIST_HEAD(pagelist);
845
846 down_read(&mm->mmap_sem);
847
848 /*
849 * Build a list of pages to migrate
850 */
851 migrate_prep();
852 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
853 struct vm_area_struct *vma;
854 struct page *page;
855
856 /*
857 * A valid page pointer that will not match any of the
858 * pages that will be moved.
859 */
860 pp->page = ZERO_PAGE(0);
861
862 err = -EFAULT;
863 vma = find_vma(mm, pp->addr);
0dc952dc 864 if (!vma || !vma_migratable(vma))
742755a1
CL
865 goto set_status;
866
867 page = follow_page(vma, pp->addr, FOLL_GET);
868 err = -ENOENT;
869 if (!page)
870 goto set_status;
871
872 if (PageReserved(page)) /* Check for zero page */
873 goto put_and_set;
874
875 pp->page = page;
876 err = page_to_nid(page);
877
878 if (err == pp->node)
879 /*
880 * Node already in the right place
881 */
882 goto put_and_set;
883
884 err = -EACCES;
885 if (page_mapcount(page) > 1 &&
886 !migrate_all)
887 goto put_and_set;
888
889 err = isolate_lru_page(page, &pagelist);
890put_and_set:
891 /*
892 * Either remove the duplicate refcount from
893 * isolate_lru_page() or drop the page ref if it was
894 * not isolated.
895 */
896 put_page(page);
897set_status:
898 pp->status = err;
899 }
900
901 if (!list_empty(&pagelist))
902 err = migrate_pages(&pagelist, new_page_node,
903 (unsigned long)pm);
904 else
905 err = -ENOENT;
906
907 up_read(&mm->mmap_sem);
908 return err;
909}
910
911/*
912 * Determine the nodes of a list of pages. The addr in the pm array
913 * must have been set to the virtual address of which we want to determine
914 * the node number.
915 */
916static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
917{
918 down_read(&mm->mmap_sem);
919
920 for ( ; pm->node != MAX_NUMNODES; pm++) {
921 struct vm_area_struct *vma;
922 struct page *page;
923 int err;
924
925 err = -EFAULT;
926 vma = find_vma(mm, pm->addr);
927 if (!vma)
928 goto set_status;
929
930 page = follow_page(vma, pm->addr, 0);
931 err = -ENOENT;
932 /* Use PageReserved to check for zero page */
933 if (!page || PageReserved(page))
934 goto set_status;
935
936 err = page_to_nid(page);
937set_status:
938 pm->status = err;
939 }
940
941 up_read(&mm->mmap_sem);
942 return 0;
943}
944
945/*
946 * Move a list of pages in the address space of the currently executing
947 * process.
948 */
949asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
950 const void __user * __user *pages,
951 const int __user *nodes,
952 int __user *status, int flags)
953{
954 int err = 0;
955 int i;
956 struct task_struct *task;
957 nodemask_t task_nodes;
958 struct mm_struct *mm;
959 struct page_to_node *pm = NULL;
960
961 /* Check flags */
962 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
963 return -EINVAL;
964
965 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
966 return -EPERM;
967
968 /* Find the mm_struct */
969 read_lock(&tasklist_lock);
228ebcbe 970 task = pid ? find_task_by_vpid(pid) : current;
742755a1
CL
971 if (!task) {
972 read_unlock(&tasklist_lock);
973 return -ESRCH;
974 }
975 mm = get_task_mm(task);
976 read_unlock(&tasklist_lock);
977
978 if (!mm)
979 return -EINVAL;
980
981 /*
982 * Check if this process has the right to modify the specified
983 * process. The right exists if the process has administrative
984 * capabilities, superuser privileges or the same
985 * userid as the target process.
986 */
987 if ((current->euid != task->suid) && (current->euid != task->uid) &&
988 (current->uid != task->suid) && (current->uid != task->uid) &&
989 !capable(CAP_SYS_NICE)) {
990 err = -EPERM;
991 goto out2;
992 }
993
86c3a764
DQ
994 err = security_task_movememory(task);
995 if (err)
996 goto out2;
997
998
742755a1
CL
999 task_nodes = cpuset_mems_allowed(task);
1000
1001 /* Limit nr_pages so that the multiplication may not overflow */
1002 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
1003 err = -E2BIG;
1004 goto out2;
1005 }
1006
1007 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
1008 if (!pm) {
1009 err = -ENOMEM;
1010 goto out2;
1011 }
1012
1013 /*
1014 * Get parameters from user space and initialize the pm
1015 * array. Return various errors if the user did something wrong.
1016 */
1017 for (i = 0; i < nr_pages; i++) {
9d966d49 1018 const void __user *p;
742755a1
CL
1019
1020 err = -EFAULT;
1021 if (get_user(p, pages + i))
1022 goto out;
1023
1024 pm[i].addr = (unsigned long)p;
1025 if (nodes) {
1026 int node;
1027
1028 if (get_user(node, nodes + i))
1029 goto out;
1030
1031 err = -ENODEV;
56bbd65d 1032 if (!node_state(node, N_HIGH_MEMORY))
742755a1
CL
1033 goto out;
1034
1035 err = -EACCES;
1036 if (!node_isset(node, task_nodes))
1037 goto out;
1038
1039 pm[i].node = node;
8ce08464
SR
1040 } else
1041 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
742755a1
CL
1042 }
1043 /* End marker */
1044 pm[nr_pages].node = MAX_NUMNODES;
1045
1046 if (nodes)
1047 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
1048 else
1049 err = do_pages_stat(mm, pm);
1050
1051 if (err >= 0)
1052 /* Return status information */
1053 for (i = 0; i < nr_pages; i++)
1054 if (put_user(pm[i].status, status + i))
1055 err = -EFAULT;
1056
1057out:
1058 vfree(pm);
1059out2:
1060 mmput(mm);
1061 return err;
1062}
1063#endif
1064
7b2259b3
CL
1065/*
1066 * Call migration functions in the vma_ops that may prepare
1067 * memory in a vm for migration. migration functions may perform
1068 * the migration for vmas that do not have an underlying page struct.
1069 */
1070int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1071 const nodemask_t *from, unsigned long flags)
1072{
1073 struct vm_area_struct *vma;
1074 int err = 0;
1075
1076 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
1077 if (vma->vm_ops && vma->vm_ops->migrate) {
1078 err = vma->vm_ops->migrate(vma, to, from, flags);
1079 if (err)
1080 break;
1081 }
1082 }
1083 return err;
1084}