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
13 */
14
15 #include <linux/migrate.h>
16 #include <linux/module.h>
17 #include <linux/swap.h>
18 #include <linux/swapops.h>
19 #include <linux/pagemap.h>
20 #include <linux/buffer_head.h>
21 #include <linux/mm_inline.h>
22 #include <linux/nsproxy.h>
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>
28 #include <linux/writeback.h>
29 #include <linux/mempolicy.h>
30 #include <linux/vmalloc.h>
31 #include <linux/security.h>
32 #include <linux/memcontrol.h>
33 #include <linux/syscalls.h>
34
35 #include "internal.h"
36
37 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
38
39 /*
40 * migrate_prep() needs to be called before we start compiling a list of pages
41 * to be migrated using isolate_lru_page().
42 */
43 int migrate_prep(void)
44 {
45 /*
46 * Clear the LRU lists so pages can be isolated.
47 * Note that pages may be moved off the LRU after we have
48 * drained them. Those pages will fail to migrate like other
49 * pages that may be busy.
50 */
51 lru_add_drain_all();
52
53 return 0;
54 }
55
56 /*
57 * Add isolated pages on the list back to the LRU under page lock
58 * to avoid leaking evictable pages back onto unevictable list.
59 *
60 * returns the number of pages put back.
61 */
62 int putback_lru_pages(struct list_head *l)
63 {
64 struct page *page;
65 struct page *page2;
66 int count = 0;
67
68 list_for_each_entry_safe(page, page2, l, lru) {
69 list_del(&page->lru);
70 putback_lru_page(page);
71 count++;
72 }
73 return count;
74 }
75
76 /*
77 * Restore a potential migration pte to a working pte entry
78 */
79 static void remove_migration_pte(struct vm_area_struct *vma,
80 struct page *old, struct page *new)
81 {
82 struct mm_struct *mm = vma->vm_mm;
83 swp_entry_t entry;
84 pgd_t *pgd;
85 pud_t *pud;
86 pmd_t *pmd;
87 pte_t *ptep, pte;
88 spinlock_t *ptl;
89 unsigned long addr = page_address_in_vma(new, vma);
90
91 if (addr == -EFAULT)
92 return;
93
94 pgd = pgd_offset(mm, addr);
95 if (!pgd_present(*pgd))
96 return;
97
98 pud = pud_offset(pgd, addr);
99 if (!pud_present(*pud))
100 return;
101
102 pmd = pmd_offset(pud, addr);
103 if (!pmd_present(*pmd))
104 return;
105
106 ptep = pte_offset_map(pmd, addr);
107
108 if (!is_swap_pte(*ptep)) {
109 pte_unmap(ptep);
110 return;
111 }
112
113 ptl = pte_lockptr(mm, pmd);
114 spin_lock(ptl);
115 pte = *ptep;
116 if (!is_swap_pte(pte))
117 goto out;
118
119 entry = pte_to_swp_entry(pte);
120
121 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
122 goto out;
123
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);
128 flush_cache_page(vma, addr, pte_pfn(pte));
129 set_pte_at(mm, addr, ptep, pte);
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);
138
139 out:
140 pte_unmap_unlock(ptep, ptl);
141 }
142
143 /*
144 * Note that remove_file_migration_ptes will only work on regular mappings,
145 * Nonlinear mappings do not use migration entries.
146 */
147 static void remove_file_migration_ptes(struct page *old, struct page *new)
148 {
149 struct vm_area_struct *vma;
150 struct address_space *mapping = page_mapping(new);
151 struct prio_tree_iter iter;
152 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
153
154 if (!mapping)
155 return;
156
157 spin_lock(&mapping->i_mmap_lock);
158
159 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
160 remove_migration_pte(vma, old, new);
161
162 spin_unlock(&mapping->i_mmap_lock);
163 }
164
165 /*
166 * Must hold mmap_sem lock on at least one of the vmas containing
167 * the page so that the anon_vma cannot vanish.
168 */
169 static void remove_anon_migration_ptes(struct page *old, struct page *new)
170 {
171 struct anon_vma *anon_vma;
172 struct vm_area_struct *vma;
173 unsigned long mapping;
174
175 mapping = (unsigned long)new->mapping;
176
177 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
178 return;
179
180 /*
181 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
182 */
183 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
184 spin_lock(&anon_vma->lock);
185
186 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
187 remove_migration_pte(vma, old, new);
188
189 spin_unlock(&anon_vma->lock);
190 }
191
192 /*
193 * Get rid of all migration entries and replace them by
194 * references to the indicated page.
195 */
196 static void remove_migration_ptes(struct page *old, struct page *new)
197 {
198 if (PageAnon(new))
199 remove_anon_migration_ptes(old, new);
200 else
201 remove_file_migration_ptes(old, new);
202 }
203
204 /*
205 * Something used the pte of a page under migration. We need to
206 * get to the page and wait until migration is finished.
207 * When we return from this function the fault will be retried.
208 *
209 * This function is called from do_swap_page().
210 */
211 void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
212 unsigned long address)
213 {
214 pte_t *ptep, pte;
215 spinlock_t *ptl;
216 swp_entry_t entry;
217 struct page *page;
218
219 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
220 pte = *ptep;
221 if (!is_swap_pte(pte))
222 goto out;
223
224 entry = pte_to_swp_entry(pte);
225 if (!is_migration_entry(entry))
226 goto out;
227
228 page = migration_entry_to_page(entry);
229
230 /*
231 * Once radix-tree replacement of page migration started, page_count
232 * *must* be zero. And, we don't want to call wait_on_page_locked()
233 * against a page without get_page().
234 * So, we use get_page_unless_zero(), here. Even failed, page fault
235 * will occur again.
236 */
237 if (!get_page_unless_zero(page))
238 goto out;
239 pte_unmap_unlock(ptep, ptl);
240 wait_on_page_locked(page);
241 put_page(page);
242 return;
243 out:
244 pte_unmap_unlock(ptep, ptl);
245 }
246
247 /*
248 * Replace the page in the mapping.
249 *
250 * The number of remaining references must be:
251 * 1 for anonymous pages without a mapping
252 * 2 for pages with a mapping
253 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
254 */
255 static int migrate_page_move_mapping(struct address_space *mapping,
256 struct page *newpage, struct page *page)
257 {
258 int expected_count;
259 void **pslot;
260
261 if (!mapping) {
262 /* Anonymous page without mapping */
263 if (page_count(page) != 1)
264 return -EAGAIN;
265 return 0;
266 }
267
268 spin_lock_irq(&mapping->tree_lock);
269
270 pslot = radix_tree_lookup_slot(&mapping->page_tree,
271 page_index(page));
272
273 expected_count = 2 + !!page_has_private(page);
274 if (page_count(page) != expected_count ||
275 (struct page *)radix_tree_deref_slot(pslot) != page) {
276 spin_unlock_irq(&mapping->tree_lock);
277 return -EAGAIN;
278 }
279
280 if (!page_freeze_refs(page, expected_count)) {
281 spin_unlock_irq(&mapping->tree_lock);
282 return -EAGAIN;
283 }
284
285 /*
286 * Now we know that no one else is looking at the page.
287 */
288 get_page(newpage); /* add cache reference */
289 if (PageSwapCache(page)) {
290 SetPageSwapCache(newpage);
291 set_page_private(newpage, page_private(page));
292 }
293
294 radix_tree_replace_slot(pslot, newpage);
295
296 page_unfreeze_refs(page, expected_count);
297 /*
298 * Drop cache reference from old page.
299 * We know this isn't the last reference.
300 */
301 __put_page(page);
302
303 /*
304 * If moved to a different zone then also account
305 * the page for that zone. Other VM counters will be
306 * taken care of when we establish references to the
307 * new page and drop references to the old page.
308 *
309 * Note that anonymous pages are accounted for
310 * via NR_FILE_PAGES and NR_ANON_PAGES if they
311 * are mapped to swap space.
312 */
313 __dec_zone_page_state(page, NR_FILE_PAGES);
314 __inc_zone_page_state(newpage, NR_FILE_PAGES);
315
316 spin_unlock_irq(&mapping->tree_lock);
317
318 return 0;
319 }
320
321 /*
322 * Copy the page to its new location
323 */
324 static void migrate_page_copy(struct page *newpage, struct page *page)
325 {
326 int anon;
327
328 copy_highpage(newpage, page);
329
330 if (PageError(page))
331 SetPageError(newpage);
332 if (PageReferenced(page))
333 SetPageReferenced(newpage);
334 if (PageUptodate(page))
335 SetPageUptodate(newpage);
336 if (TestClearPageActive(page)) {
337 VM_BUG_ON(PageUnevictable(page));
338 SetPageActive(newpage);
339 } else
340 unevictable_migrate_page(newpage, page);
341 if (PageChecked(page))
342 SetPageChecked(newpage);
343 if (PageMappedToDisk(page))
344 SetPageMappedToDisk(newpage);
345
346 if (PageDirty(page)) {
347 clear_page_dirty_for_io(page);
348 /*
349 * Want to mark the page and the radix tree as dirty, and
350 * redo the accounting that clear_page_dirty_for_io undid,
351 * but we can't use set_page_dirty because that function
352 * is actually a signal that all of the page has become dirty.
353 * Wheras only part of our page may be dirty.
354 */
355 __set_page_dirty_nobuffers(newpage);
356 }
357
358 mlock_migrate_page(newpage, page);
359
360 ClearPageSwapCache(page);
361 ClearPagePrivate(page);
362 set_page_private(page, 0);
363 /* page->mapping contains a flag for PageAnon() */
364 anon = PageAnon(page);
365 page->mapping = NULL;
366
367 /*
368 * If any waiters have accumulated on the new page then
369 * wake them up.
370 */
371 if (PageWriteback(newpage))
372 end_page_writeback(newpage);
373 }
374
375 /************************************************************
376 * Migration functions
377 ***********************************************************/
378
379 /* Always fail migration. Used for mappings that are not movable */
380 int fail_migrate_page(struct address_space *mapping,
381 struct page *newpage, struct page *page)
382 {
383 return -EIO;
384 }
385 EXPORT_SYMBOL(fail_migrate_page);
386
387 /*
388 * Common logic to directly migrate a single page suitable for
389 * pages that do not use PagePrivate/PagePrivate2.
390 *
391 * Pages are locked upon entry and exit.
392 */
393 int migrate_page(struct address_space *mapping,
394 struct page *newpage, struct page *page)
395 {
396 int rc;
397
398 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
399
400 rc = migrate_page_move_mapping(mapping, newpage, page);
401
402 if (rc)
403 return rc;
404
405 migrate_page_copy(newpage, page);
406 return 0;
407 }
408 EXPORT_SYMBOL(migrate_page);
409
410 #ifdef CONFIG_BLOCK
411 /*
412 * Migration function for pages with buffers. This function can only be used
413 * if the underlying filesystem guarantees that no other references to "page"
414 * exist.
415 */
416 int buffer_migrate_page(struct address_space *mapping,
417 struct page *newpage, struct page *page)
418 {
419 struct buffer_head *bh, *head;
420 int rc;
421
422 if (!page_has_buffers(page))
423 return migrate_page(mapping, newpage, page);
424
425 head = page_buffers(page);
426
427 rc = migrate_page_move_mapping(mapping, newpage, page);
428
429 if (rc)
430 return rc;
431
432 bh = head;
433 do {
434 get_bh(bh);
435 lock_buffer(bh);
436 bh = bh->b_this_page;
437
438 } while (bh != head);
439
440 ClearPagePrivate(page);
441 set_page_private(newpage, page_private(page));
442 set_page_private(page, 0);
443 put_page(page);
444 get_page(newpage);
445
446 bh = head;
447 do {
448 set_bh_page(bh, newpage, bh_offset(bh));
449 bh = bh->b_this_page;
450
451 } while (bh != head);
452
453 SetPagePrivate(newpage);
454
455 migrate_page_copy(newpage, page);
456
457 bh = head;
458 do {
459 unlock_buffer(bh);
460 put_bh(bh);
461 bh = bh->b_this_page;
462
463 } while (bh != head);
464
465 return 0;
466 }
467 EXPORT_SYMBOL(buffer_migrate_page);
468 #endif
469
470 /*
471 * Writeback a page to clean the dirty state
472 */
473 static int writeout(struct address_space *mapping, struct page *page)
474 {
475 struct writeback_control wbc = {
476 .sync_mode = WB_SYNC_NONE,
477 .nr_to_write = 1,
478 .range_start = 0,
479 .range_end = LLONG_MAX,
480 .nonblocking = 1,
481 .for_reclaim = 1
482 };
483 int rc;
484
485 if (!mapping->a_ops->writepage)
486 /* No write method for the address space */
487 return -EINVAL;
488
489 if (!clear_page_dirty_for_io(page))
490 /* Someone else already triggered a write */
491 return -EAGAIN;
492
493 /*
494 * A dirty page may imply that the underlying filesystem has
495 * the page on some queue. So the page must be clean for
496 * migration. Writeout may mean we loose the lock and the
497 * page state is no longer what we checked for earlier.
498 * At this point we know that the migration attempt cannot
499 * be successful.
500 */
501 remove_migration_ptes(page, page);
502
503 rc = mapping->a_ops->writepage(page, &wbc);
504
505 if (rc != AOP_WRITEPAGE_ACTIVATE)
506 /* unlocked. Relock */
507 lock_page(page);
508
509 return (rc < 0) ? -EIO : -EAGAIN;
510 }
511
512 /*
513 * Default handling if a filesystem does not provide a migration function.
514 */
515 static int fallback_migrate_page(struct address_space *mapping,
516 struct page *newpage, struct page *page)
517 {
518 if (PageDirty(page))
519 return writeout(mapping, page);
520
521 /*
522 * Buffers may be managed in a filesystem specific way.
523 * We must have no buffers or drop them.
524 */
525 if (page_has_private(page) &&
526 !try_to_release_page(page, GFP_KERNEL))
527 return -EAGAIN;
528
529 return migrate_page(mapping, newpage, page);
530 }
531
532 /*
533 * Move a page to a newly allocated page
534 * The page is locked and all ptes have been successfully removed.
535 *
536 * The new page will have replaced the old page if this function
537 * is successful.
538 *
539 * Return value:
540 * < 0 - error code
541 * == 0 - success
542 */
543 static int move_to_new_page(struct page *newpage, struct page *page)
544 {
545 struct address_space *mapping;
546 int rc;
547
548 /*
549 * Block others from accessing the page when we get around to
550 * establishing additional references. We are the only one
551 * holding a reference to the new page at this point.
552 */
553 if (!trylock_page(newpage))
554 BUG();
555
556 /* Prepare mapping for the new page.*/
557 newpage->index = page->index;
558 newpage->mapping = page->mapping;
559 if (PageSwapBacked(page))
560 SetPageSwapBacked(newpage);
561
562 mapping = page_mapping(page);
563 if (!mapping)
564 rc = migrate_page(mapping, newpage, page);
565 else if (mapping->a_ops->migratepage)
566 /*
567 * Most pages have a mapping and most filesystems
568 * should provide a migration function. Anonymous
569 * pages are part of swap space which also has its
570 * own migration function. This is the most common
571 * path for page migration.
572 */
573 rc = mapping->a_ops->migratepage(mapping,
574 newpage, page);
575 else
576 rc = fallback_migrate_page(mapping, newpage, page);
577
578 if (!rc) {
579 remove_migration_ptes(page, newpage);
580 } else
581 newpage->mapping = NULL;
582
583 unlock_page(newpage);
584
585 return rc;
586 }
587
588 /*
589 * Obtain the lock on page, remove all ptes and migrate the page
590 * to the newly allocated page in newpage.
591 */
592 static int unmap_and_move(new_page_t get_new_page, unsigned long private,
593 struct page *page, int force)
594 {
595 int rc = 0;
596 int *result = NULL;
597 struct page *newpage = get_new_page(page, private, &result);
598 int rcu_locked = 0;
599 int charge = 0;
600 struct mem_cgroup *mem = NULL;
601
602 if (!newpage)
603 return -ENOMEM;
604
605 if (page_count(page) == 1) {
606 /* page was freed from under us. So we are done. */
607 goto move_newpage;
608 }
609
610 /* prepare cgroup just returns 0 or -ENOMEM */
611 rc = -EAGAIN;
612
613 if (!trylock_page(page)) {
614 if (!force)
615 goto move_newpage;
616 lock_page(page);
617 }
618
619 /* charge against new page */
620 charge = mem_cgroup_prepare_migration(page, &mem);
621 if (charge == -ENOMEM) {
622 rc = -ENOMEM;
623 goto unlock;
624 }
625 BUG_ON(charge);
626
627 if (PageWriteback(page)) {
628 if (!force)
629 goto uncharge;
630 wait_on_page_writeback(page);
631 }
632 /*
633 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
634 * we cannot notice that anon_vma is freed while we migrates a page.
635 * This rcu_read_lock() delays freeing anon_vma pointer until the end
636 * of migration. File cache pages are no problem because of page_lock()
637 * File Caches may use write_page() or lock_page() in migration, then,
638 * just care Anon page here.
639 */
640 if (PageAnon(page)) {
641 rcu_read_lock();
642 rcu_locked = 1;
643 }
644
645 /*
646 * Corner case handling:
647 * 1. When a new swap-cache page is read into, it is added to the LRU
648 * and treated as swapcache but it has no rmap yet.
649 * Calling try_to_unmap() against a page->mapping==NULL page will
650 * trigger a BUG. So handle it here.
651 * 2. An orphaned page (see truncate_complete_page) might have
652 * fs-private metadata. The page can be picked up due to memory
653 * offlining. Everywhere else except page reclaim, the page is
654 * invisible to the vm, so the page can not be migrated. So try to
655 * free the metadata, so the page can be freed.
656 */
657 if (!page->mapping) {
658 if (!PageAnon(page) && page_has_private(page)) {
659 /*
660 * Go direct to try_to_free_buffers() here because
661 * a) that's what try_to_release_page() would do anyway
662 * b) we may be under rcu_read_lock() here, so we can't
663 * use GFP_KERNEL which is what try_to_release_page()
664 * needs to be effective.
665 */
666 try_to_free_buffers(page);
667 }
668 goto rcu_unlock;
669 }
670
671 /* Establish migration ptes or remove ptes */
672 try_to_unmap(page, 1);
673
674 if (!page_mapped(page))
675 rc = move_to_new_page(newpage, page);
676
677 if (rc)
678 remove_migration_ptes(page, page);
679 rcu_unlock:
680 if (rcu_locked)
681 rcu_read_unlock();
682 uncharge:
683 if (!charge)
684 mem_cgroup_end_migration(mem, page, newpage);
685 unlock:
686 unlock_page(page);
687
688 if (rc != -EAGAIN) {
689 /*
690 * A page that has been migrated has all references
691 * removed and will be freed. A page that has not been
692 * migrated will have kepts its references and be
693 * restored.
694 */
695 list_del(&page->lru);
696 putback_lru_page(page);
697 }
698
699 move_newpage:
700
701 /*
702 * Move the new page to the LRU. If migration was not successful
703 * then this will free the page.
704 */
705 putback_lru_page(newpage);
706
707 if (result) {
708 if (rc)
709 *result = rc;
710 else
711 *result = page_to_nid(newpage);
712 }
713 return rc;
714 }
715
716 /*
717 * migrate_pages
718 *
719 * The function takes one list of pages to migrate and a function
720 * that determines from the page to be migrated and the private data
721 * the target of the move and allocates the page.
722 *
723 * The function returns after 10 attempts or if no pages
724 * are movable anymore because to has become empty
725 * or no retryable pages exist anymore. All pages will be
726 * returned to the LRU or freed.
727 *
728 * Return: Number of pages not migrated or error code.
729 */
730 int migrate_pages(struct list_head *from,
731 new_page_t get_new_page, unsigned long private)
732 {
733 int retry = 1;
734 int nr_failed = 0;
735 int pass = 0;
736 struct page *page;
737 struct page *page2;
738 int swapwrite = current->flags & PF_SWAPWRITE;
739 int rc;
740
741 if (!swapwrite)
742 current->flags |= PF_SWAPWRITE;
743
744 for(pass = 0; pass < 10 && retry; pass++) {
745 retry = 0;
746
747 list_for_each_entry_safe(page, page2, from, lru) {
748 cond_resched();
749
750 rc = unmap_and_move(get_new_page, private,
751 page, pass > 2);
752
753 switch(rc) {
754 case -ENOMEM:
755 goto out;
756 case -EAGAIN:
757 retry++;
758 break;
759 case 0:
760 break;
761 default:
762 /* Permanent failure */
763 nr_failed++;
764 break;
765 }
766 }
767 }
768 rc = 0;
769 out:
770 if (!swapwrite)
771 current->flags &= ~PF_SWAPWRITE;
772
773 putback_lru_pages(from);
774
775 if (rc)
776 return rc;
777
778 return nr_failed + retry;
779 }
780
781 #ifdef CONFIG_NUMA
782 /*
783 * Move a list of individual pages
784 */
785 struct page_to_node {
786 unsigned long addr;
787 struct page *page;
788 int node;
789 int status;
790 };
791
792 static struct page *new_page_node(struct page *p, unsigned long private,
793 int **result)
794 {
795 struct page_to_node *pm = (struct page_to_node *)private;
796
797 while (pm->node != MAX_NUMNODES && pm->page != p)
798 pm++;
799
800 if (pm->node == MAX_NUMNODES)
801 return NULL;
802
803 *result = &pm->status;
804
805 return alloc_pages_exact_node(pm->node,
806 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
807 }
808
809 /*
810 * Move a set of pages as indicated in the pm array. The addr
811 * field must be set to the virtual address of the page to be moved
812 * and the node number must contain a valid target node.
813 * The pm array ends with node = MAX_NUMNODES.
814 */
815 static int do_move_page_to_node_array(struct mm_struct *mm,
816 struct page_to_node *pm,
817 int migrate_all)
818 {
819 int err;
820 struct page_to_node *pp;
821 LIST_HEAD(pagelist);
822
823 down_read(&mm->mmap_sem);
824
825 /*
826 * Build a list of pages to migrate
827 */
828 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
829 struct vm_area_struct *vma;
830 struct page *page;
831
832 err = -EFAULT;
833 vma = find_vma(mm, pp->addr);
834 if (!vma || !vma_migratable(vma))
835 goto set_status;
836
837 page = follow_page(vma, pp->addr, FOLL_GET);
838
839 err = PTR_ERR(page);
840 if (IS_ERR(page))
841 goto set_status;
842
843 err = -ENOENT;
844 if (!page)
845 goto set_status;
846
847 if (PageReserved(page)) /* Check for zero page */
848 goto put_and_set;
849
850 pp->page = page;
851 err = page_to_nid(page);
852
853 if (err == pp->node)
854 /*
855 * Node already in the right place
856 */
857 goto put_and_set;
858
859 err = -EACCES;
860 if (page_mapcount(page) > 1 &&
861 !migrate_all)
862 goto put_and_set;
863
864 err = isolate_lru_page(page);
865 if (!err)
866 list_add_tail(&page->lru, &pagelist);
867 put_and_set:
868 /*
869 * Either remove the duplicate refcount from
870 * isolate_lru_page() or drop the page ref if it was
871 * not isolated.
872 */
873 put_page(page);
874 set_status:
875 pp->status = err;
876 }
877
878 err = 0;
879 if (!list_empty(&pagelist))
880 err = migrate_pages(&pagelist, new_page_node,
881 (unsigned long)pm);
882
883 up_read(&mm->mmap_sem);
884 return err;
885 }
886
887 /*
888 * Migrate an array of page address onto an array of nodes and fill
889 * the corresponding array of status.
890 */
891 static int do_pages_move(struct mm_struct *mm, struct task_struct *task,
892 unsigned long nr_pages,
893 const void __user * __user *pages,
894 const int __user *nodes,
895 int __user *status, int flags)
896 {
897 struct page_to_node *pm;
898 nodemask_t task_nodes;
899 unsigned long chunk_nr_pages;
900 unsigned long chunk_start;
901 int err;
902
903 task_nodes = cpuset_mems_allowed(task);
904
905 err = -ENOMEM;
906 pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
907 if (!pm)
908 goto out;
909
910 migrate_prep();
911
912 /*
913 * Store a chunk of page_to_node array in a page,
914 * but keep the last one as a marker
915 */
916 chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
917
918 for (chunk_start = 0;
919 chunk_start < nr_pages;
920 chunk_start += chunk_nr_pages) {
921 int j;
922
923 if (chunk_start + chunk_nr_pages > nr_pages)
924 chunk_nr_pages = nr_pages - chunk_start;
925
926 /* fill the chunk pm with addrs and nodes from user-space */
927 for (j = 0; j < chunk_nr_pages; j++) {
928 const void __user *p;
929 int node;
930
931 err = -EFAULT;
932 if (get_user(p, pages + j + chunk_start))
933 goto out_pm;
934 pm[j].addr = (unsigned long) p;
935
936 if (get_user(node, nodes + j + chunk_start))
937 goto out_pm;
938
939 err = -ENODEV;
940 if (node < 0 || node >= MAX_NUMNODES)
941 goto out_pm;
942
943 if (!node_state(node, N_HIGH_MEMORY))
944 goto out_pm;
945
946 err = -EACCES;
947 if (!node_isset(node, task_nodes))
948 goto out_pm;
949
950 pm[j].node = node;
951 }
952
953 /* End marker for this chunk */
954 pm[chunk_nr_pages].node = MAX_NUMNODES;
955
956 /* Migrate this chunk */
957 err = do_move_page_to_node_array(mm, pm,
958 flags & MPOL_MF_MOVE_ALL);
959 if (err < 0)
960 goto out_pm;
961
962 /* Return status information */
963 for (j = 0; j < chunk_nr_pages; j++)
964 if (put_user(pm[j].status, status + j + chunk_start)) {
965 err = -EFAULT;
966 goto out_pm;
967 }
968 }
969 err = 0;
970
971 out_pm:
972 free_page((unsigned long)pm);
973 out:
974 return err;
975 }
976
977 /*
978 * Determine the nodes of an array of pages and store it in an array of status.
979 */
980 static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
981 const void __user **pages, int *status)
982 {
983 unsigned long i;
984
985 down_read(&mm->mmap_sem);
986
987 for (i = 0; i < nr_pages; i++) {
988 unsigned long addr = (unsigned long)(*pages);
989 struct vm_area_struct *vma;
990 struct page *page;
991 int err = -EFAULT;
992
993 vma = find_vma(mm, addr);
994 if (!vma)
995 goto set_status;
996
997 page = follow_page(vma, addr, 0);
998
999 err = PTR_ERR(page);
1000 if (IS_ERR(page))
1001 goto set_status;
1002
1003 err = -ENOENT;
1004 /* Use PageReserved to check for zero page */
1005 if (!page || PageReserved(page))
1006 goto set_status;
1007
1008 err = page_to_nid(page);
1009 set_status:
1010 *status = err;
1011
1012 pages++;
1013 status++;
1014 }
1015
1016 up_read(&mm->mmap_sem);
1017 }
1018
1019 /*
1020 * Determine the nodes of a user array of pages and store it in
1021 * a user array of status.
1022 */
1023 static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1024 const void __user * __user *pages,
1025 int __user *status)
1026 {
1027 #define DO_PAGES_STAT_CHUNK_NR 16
1028 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1029 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
1030 unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1031 int err;
1032
1033 for (i = 0; i < nr_pages; i += chunk_nr) {
1034 if (chunk_nr + i > nr_pages)
1035 chunk_nr = nr_pages - i;
1036
1037 err = copy_from_user(chunk_pages, &pages[i],
1038 chunk_nr * sizeof(*chunk_pages));
1039 if (err) {
1040 err = -EFAULT;
1041 goto out;
1042 }
1043
1044 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1045
1046 err = copy_to_user(&status[i], chunk_status,
1047 chunk_nr * sizeof(*chunk_status));
1048 if (err) {
1049 err = -EFAULT;
1050 goto out;
1051 }
1052 }
1053 err = 0;
1054
1055 out:
1056 return err;
1057 }
1058
1059 /*
1060 * Move a list of pages in the address space of the currently executing
1061 * process.
1062 */
1063 SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
1064 const void __user * __user *, pages,
1065 const int __user *, nodes,
1066 int __user *, status, int, flags)
1067 {
1068 const struct cred *cred = current_cred(), *tcred;
1069 struct task_struct *task;
1070 struct mm_struct *mm;
1071 int err;
1072
1073 /* Check flags */
1074 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
1075 return -EINVAL;
1076
1077 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1078 return -EPERM;
1079
1080 /* Find the mm_struct */
1081 read_lock(&tasklist_lock);
1082 task = pid ? find_task_by_vpid(pid) : current;
1083 if (!task) {
1084 read_unlock(&tasklist_lock);
1085 return -ESRCH;
1086 }
1087 mm = get_task_mm(task);
1088 read_unlock(&tasklist_lock);
1089
1090 if (!mm)
1091 return -EINVAL;
1092
1093 /*
1094 * Check if this process has the right to modify the specified
1095 * process. The right exists if the process has administrative
1096 * capabilities, superuser privileges or the same
1097 * userid as the target process.
1098 */
1099 rcu_read_lock();
1100 tcred = __task_cred(task);
1101 if (cred->euid != tcred->suid && cred->euid != tcred->uid &&
1102 cred->uid != tcred->suid && cred->uid != tcred->uid &&
1103 !capable(CAP_SYS_NICE)) {
1104 rcu_read_unlock();
1105 err = -EPERM;
1106 goto out;
1107 }
1108 rcu_read_unlock();
1109
1110 err = security_task_movememory(task);
1111 if (err)
1112 goto out;
1113
1114 if (nodes) {
1115 err = do_pages_move(mm, task, nr_pages, pages, nodes, status,
1116 flags);
1117 } else {
1118 err = do_pages_stat(mm, nr_pages, pages, status);
1119 }
1120
1121 out:
1122 mmput(mm);
1123 return err;
1124 }
1125
1126 /*
1127 * Call migration functions in the vma_ops that may prepare
1128 * memory in a vm for migration. migration functions may perform
1129 * the migration for vmas that do not have an underlying page struct.
1130 */
1131 int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1132 const nodemask_t *from, unsigned long flags)
1133 {
1134 struct vm_area_struct *vma;
1135 int err = 0;
1136
1137 for (vma = mm->mmap; vma && !err; vma = vma->vm_next) {
1138 if (vma->vm_ops && vma->vm_ops->migrate) {
1139 err = vma->vm_ops->migrate(vma, to, from, flags);
1140 if (err)
1141 break;
1142 }
1143 }
1144 return err;
1145 }
1146 #endif
1147
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