KVM: x86: Prevent starting PIT timers in the absence of irqchip support
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / migrate.c
blob14d0a6a632f6f8fb2dd0240d35c4853ff67d176d
1 /*
2 * Memory Migration functionality - linux/mm/migration.c
4 * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
6 * Page migration was first developed in the context of the memory hotplug
7 * project. The main authors of the migration code are:
9 * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
10 * Hirokazu Takahashi <taka@valinux.co.jp>
11 * Dave Hansen <haveblue@us.ibm.com>
12 * Christoph Lameter
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/ksm.h>
25 #include <linux/rmap.h>
26 #include <linux/topology.h>
27 #include <linux/cpu.h>
28 #include <linux/cpuset.h>
29 #include <linux/writeback.h>
30 #include <linux/mempolicy.h>
31 #include <linux/vmalloc.h>
32 #include <linux/security.h>
33 #include <linux/memcontrol.h>
34 #include <linux/syscalls.h>
35 #include <linux/hugetlb.h>
36 #include <linux/gfp.h>
38 #include <asm/tlbflush.h>
40 #include "internal.h"
42 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
45 * migrate_prep() needs to be called before we start compiling a list of pages
46 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
47 * undesirable, use migrate_prep_local()
49 int migrate_prep(void)
52 * Clear the LRU lists so pages can be isolated.
53 * Note that pages may be moved off the LRU after we have
54 * drained them. Those pages will fail to migrate like other
55 * pages that may be busy.
57 lru_add_drain_all();
59 return 0;
62 /* Do the necessary work of migrate_prep but not if it involves other CPUs */
63 int migrate_prep_local(void)
65 lru_add_drain();
67 return 0;
71 * Add isolated pages on the list back to the LRU under page lock
72 * to avoid leaking evictable pages back onto unevictable list.
74 void putback_lru_pages(struct list_head *l)
76 struct page *page;
77 struct page *page2;
79 list_for_each_entry_safe(page, page2, l, lru) {
80 list_del(&page->lru);
81 dec_zone_page_state(page, NR_ISOLATED_ANON +
82 page_is_file_cache(page));
83 putback_lru_page(page);
88 * Restore a potential migration pte to a working pte entry
90 static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
91 unsigned long addr, void *old)
93 struct mm_struct *mm = vma->vm_mm;
94 swp_entry_t entry;
95 pgd_t *pgd;
96 pud_t *pud;
97 pmd_t *pmd;
98 pte_t *ptep, pte;
99 spinlock_t *ptl;
101 if (unlikely(PageHuge(new))) {
102 ptep = huge_pte_offset(mm, addr);
103 if (!ptep)
104 goto out;
105 ptl = &mm->page_table_lock;
106 } else {
107 pgd = pgd_offset(mm, addr);
108 if (!pgd_present(*pgd))
109 goto out;
111 pud = pud_offset(pgd, addr);
112 if (!pud_present(*pud))
113 goto out;
115 pmd = pmd_offset(pud, addr);
116 if (pmd_trans_huge(*pmd))
117 goto out;
118 if (!pmd_present(*pmd))
119 goto out;
121 ptep = pte_offset_map(pmd, addr);
124 * Peek to check is_swap_pte() before taking ptlock? No, we
125 * can race mremap's move_ptes(), which skips anon_vma lock.
128 ptl = pte_lockptr(mm, pmd);
131 spin_lock(ptl);
132 pte = *ptep;
133 if (!is_swap_pte(pte))
134 goto unlock;
136 entry = pte_to_swp_entry(pte);
138 if (!is_migration_entry(entry) ||
139 migration_entry_to_page(entry) != old)
140 goto unlock;
142 get_page(new);
143 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
144 if (is_write_migration_entry(entry))
145 pte = pte_mkwrite(pte);
146 #ifdef CONFIG_HUGETLB_PAGE
147 if (PageHuge(new))
148 pte = pte_mkhuge(pte);
149 #endif
150 flush_cache_page(vma, addr, pte_pfn(pte));
151 set_pte_at(mm, addr, ptep, pte);
153 if (PageHuge(new)) {
154 if (PageAnon(new))
155 hugepage_add_anon_rmap(new, vma, addr);
156 else
157 page_dup_rmap(new);
158 } else if (PageAnon(new))
159 page_add_anon_rmap(new, vma, addr);
160 else
161 page_add_file_rmap(new);
163 /* No need to invalidate - it was non-present before */
164 update_mmu_cache(vma, addr, ptep);
165 unlock:
166 pte_unmap_unlock(ptep, ptl);
167 out:
168 return SWAP_AGAIN;
172 * Get rid of all migration entries and replace them by
173 * references to the indicated page.
175 static void remove_migration_ptes(struct page *old, struct page *new)
177 rmap_walk(new, remove_migration_pte, old);
181 * Something used the pte of a page under migration. We need to
182 * get to the page and wait until migration is finished.
183 * When we return from this function the fault will be retried.
185 * This function is called from do_swap_page().
187 void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
188 unsigned long address)
190 pte_t *ptep, pte;
191 spinlock_t *ptl;
192 swp_entry_t entry;
193 struct page *page;
195 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
196 pte = *ptep;
197 if (!is_swap_pte(pte))
198 goto out;
200 entry = pte_to_swp_entry(pte);
201 if (!is_migration_entry(entry))
202 goto out;
204 page = migration_entry_to_page(entry);
207 * Once radix-tree replacement of page migration started, page_count
208 * *must* be zero. And, we don't want to call wait_on_page_locked()
209 * against a page without get_page().
210 * So, we use get_page_unless_zero(), here. Even failed, page fault
211 * will occur again.
213 if (!get_page_unless_zero(page))
214 goto out;
215 pte_unmap_unlock(ptep, ptl);
216 wait_on_page_locked(page);
217 put_page(page);
218 return;
219 out:
220 pte_unmap_unlock(ptep, ptl);
224 * Replace the page in the mapping.
226 * The number of remaining references must be:
227 * 1 for anonymous pages without a mapping
228 * 2 for pages with a mapping
229 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
231 static int migrate_page_move_mapping(struct address_space *mapping,
232 struct page *newpage, struct page *page)
234 int expected_count;
235 void **pslot;
237 if (!mapping) {
238 /* Anonymous page without mapping */
239 if (page_count(page) != 1)
240 return -EAGAIN;
241 return 0;
244 spin_lock_irq(&mapping->tree_lock);
246 pslot = radix_tree_lookup_slot(&mapping->page_tree,
247 page_index(page));
249 expected_count = 2 + page_has_private(page);
250 if (page_count(page) != expected_count ||
251 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
252 spin_unlock_irq(&mapping->tree_lock);
253 return -EAGAIN;
256 if (!page_freeze_refs(page, expected_count)) {
257 spin_unlock_irq(&mapping->tree_lock);
258 return -EAGAIN;
262 * Now we know that no one else is looking at the page.
264 get_page(newpage); /* add cache reference */
265 if (PageSwapCache(page)) {
266 SetPageSwapCache(newpage);
267 set_page_private(newpage, page_private(page));
270 radix_tree_replace_slot(pslot, newpage);
272 page_unfreeze_refs(page, expected_count);
274 * Drop cache reference from old page.
275 * We know this isn't the last reference.
277 __put_page(page);
280 * If moved to a different zone then also account
281 * the page for that zone. Other VM counters will be
282 * taken care of when we establish references to the
283 * new page and drop references to the old page.
285 * Note that anonymous pages are accounted for
286 * via NR_FILE_PAGES and NR_ANON_PAGES if they
287 * are mapped to swap space.
289 __dec_zone_page_state(page, NR_FILE_PAGES);
290 __inc_zone_page_state(newpage, NR_FILE_PAGES);
291 if (!PageSwapCache(page) && PageSwapBacked(page)) {
292 __dec_zone_page_state(page, NR_SHMEM);
293 __inc_zone_page_state(newpage, NR_SHMEM);
295 spin_unlock_irq(&mapping->tree_lock);
297 return 0;
301 * The expected number of remaining references is the same as that
302 * of migrate_page_move_mapping().
304 int migrate_huge_page_move_mapping(struct address_space *mapping,
305 struct page *newpage, struct page *page)
307 int expected_count;
308 void **pslot;
310 if (!mapping) {
311 if (page_count(page) != 1)
312 return -EAGAIN;
313 return 0;
316 spin_lock_irq(&mapping->tree_lock);
318 pslot = radix_tree_lookup_slot(&mapping->page_tree,
319 page_index(page));
321 expected_count = 2 + page_has_private(page);
322 if (page_count(page) != expected_count ||
323 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
324 spin_unlock_irq(&mapping->tree_lock);
325 return -EAGAIN;
328 if (!page_freeze_refs(page, expected_count)) {
329 spin_unlock_irq(&mapping->tree_lock);
330 return -EAGAIN;
333 get_page(newpage);
335 radix_tree_replace_slot(pslot, newpage);
337 page_unfreeze_refs(page, expected_count);
339 __put_page(page);
341 spin_unlock_irq(&mapping->tree_lock);
342 return 0;
346 * Copy the page to its new location
348 void migrate_page_copy(struct page *newpage, struct page *page)
350 if (PageHuge(page))
351 copy_huge_page(newpage, page);
352 else
353 copy_highpage(newpage, page);
355 if (PageError(page))
356 SetPageError(newpage);
357 if (PageReferenced(page))
358 SetPageReferenced(newpage);
359 if (PageUptodate(page))
360 SetPageUptodate(newpage);
361 if (TestClearPageActive(page)) {
362 VM_BUG_ON(PageUnevictable(page));
363 SetPageActive(newpage);
364 } else if (TestClearPageUnevictable(page))
365 SetPageUnevictable(newpage);
366 if (PageChecked(page))
367 SetPageChecked(newpage);
368 if (PageMappedToDisk(page))
369 SetPageMappedToDisk(newpage);
371 if (PageDirty(page)) {
372 clear_page_dirty_for_io(page);
374 * Want to mark the page and the radix tree as dirty, and
375 * redo the accounting that clear_page_dirty_for_io undid,
376 * but we can't use set_page_dirty because that function
377 * is actually a signal that all of the page has become dirty.
378 * Whereas only part of our page may be dirty.
380 __set_page_dirty_nobuffers(newpage);
383 mlock_migrate_page(newpage, page);
384 ksm_migrate_page(newpage, page);
386 ClearPageSwapCache(page);
387 ClearPagePrivate(page);
388 set_page_private(page, 0);
389 page->mapping = NULL;
392 * If any waiters have accumulated on the new page then
393 * wake them up.
395 if (PageWriteback(newpage))
396 end_page_writeback(newpage);
399 /************************************************************
400 * Migration functions
401 ***********************************************************/
403 /* Always fail migration. Used for mappings that are not movable */
404 int fail_migrate_page(struct address_space *mapping,
405 struct page *newpage, struct page *page)
407 return -EIO;
409 EXPORT_SYMBOL(fail_migrate_page);
412 * Common logic to directly migrate a single page suitable for
413 * pages that do not use PagePrivate/PagePrivate2.
415 * Pages are locked upon entry and exit.
417 int migrate_page(struct address_space *mapping,
418 struct page *newpage, struct page *page)
420 int rc;
422 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
424 rc = migrate_page_move_mapping(mapping, newpage, page);
426 if (rc)
427 return rc;
429 migrate_page_copy(newpage, page);
430 return 0;
432 EXPORT_SYMBOL(migrate_page);
434 #ifdef CONFIG_BLOCK
436 * Migration function for pages with buffers. This function can only be used
437 * if the underlying filesystem guarantees that no other references to "page"
438 * exist.
440 int buffer_migrate_page(struct address_space *mapping,
441 struct page *newpage, struct page *page)
443 struct buffer_head *bh, *head;
444 int rc;
446 if (!page_has_buffers(page))
447 return migrate_page(mapping, newpage, page);
449 head = page_buffers(page);
451 rc = migrate_page_move_mapping(mapping, newpage, page);
453 if (rc)
454 return rc;
456 bh = head;
457 do {
458 get_bh(bh);
459 lock_buffer(bh);
460 bh = bh->b_this_page;
462 } while (bh != head);
464 ClearPagePrivate(page);
465 set_page_private(newpage, page_private(page));
466 set_page_private(page, 0);
467 put_page(page);
468 get_page(newpage);
470 bh = head;
471 do {
472 set_bh_page(bh, newpage, bh_offset(bh));
473 bh = bh->b_this_page;
475 } while (bh != head);
477 SetPagePrivate(newpage);
479 migrate_page_copy(newpage, page);
481 bh = head;
482 do {
483 unlock_buffer(bh);
484 put_bh(bh);
485 bh = bh->b_this_page;
487 } while (bh != head);
489 return 0;
491 EXPORT_SYMBOL(buffer_migrate_page);
492 #endif
495 * Writeback a page to clean the dirty state
497 static int writeout(struct address_space *mapping, struct page *page)
499 struct writeback_control wbc = {
500 .sync_mode = WB_SYNC_NONE,
501 .nr_to_write = 1,
502 .range_start = 0,
503 .range_end = LLONG_MAX,
504 .for_reclaim = 1
506 int rc;
508 if (!mapping->a_ops->writepage)
509 /* No write method for the address space */
510 return -EINVAL;
512 if (!clear_page_dirty_for_io(page))
513 /* Someone else already triggered a write */
514 return -EAGAIN;
517 * A dirty page may imply that the underlying filesystem has
518 * the page on some queue. So the page must be clean for
519 * migration. Writeout may mean we loose the lock and the
520 * page state is no longer what we checked for earlier.
521 * At this point we know that the migration attempt cannot
522 * be successful.
524 remove_migration_ptes(page, page);
526 rc = mapping->a_ops->writepage(page, &wbc);
528 if (rc != AOP_WRITEPAGE_ACTIVATE)
529 /* unlocked. Relock */
530 lock_page(page);
532 return (rc < 0) ? -EIO : -EAGAIN;
536 * Default handling if a filesystem does not provide a migration function.
538 static int fallback_migrate_page(struct address_space *mapping,
539 struct page *newpage, struct page *page)
541 if (PageDirty(page))
542 return writeout(mapping, page);
545 * Buffers may be managed in a filesystem specific way.
546 * We must have no buffers or drop them.
548 if (page_has_private(page) &&
549 !try_to_release_page(page, GFP_KERNEL))
550 return -EAGAIN;
552 return migrate_page(mapping, newpage, page);
556 * Move a page to a newly allocated page
557 * The page is locked and all ptes have been successfully removed.
559 * The new page will have replaced the old page if this function
560 * is successful.
562 * Return value:
563 * < 0 - error code
564 * == 0 - success
566 static int move_to_new_page(struct page *newpage, struct page *page,
567 int remap_swapcache, bool sync)
569 struct address_space *mapping;
570 int rc;
573 * Block others from accessing the page when we get around to
574 * establishing additional references. We are the only one
575 * holding a reference to the new page at this point.
577 if (!trylock_page(newpage))
578 BUG();
580 /* Prepare mapping for the new page.*/
581 newpage->index = page->index;
582 newpage->mapping = page->mapping;
583 if (PageSwapBacked(page))
584 SetPageSwapBacked(newpage);
586 mapping = page_mapping(page);
587 if (!mapping)
588 rc = migrate_page(mapping, newpage, page);
589 else {
591 * Do not writeback pages if !sync and migratepage is
592 * not pointing to migrate_page() which is nonblocking
593 * (swapcache/tmpfs uses migratepage = migrate_page).
595 if (PageDirty(page) && !sync &&
596 mapping->a_ops->migratepage != migrate_page)
597 rc = -EBUSY;
598 else if (mapping->a_ops->migratepage)
600 * Most pages have a mapping and most filesystems
601 * should provide a migration function. Anonymous
602 * pages are part of swap space which also has its
603 * own migration function. This is the most common
604 * path for page migration.
606 rc = mapping->a_ops->migratepage(mapping,
607 newpage, page);
608 else
609 rc = fallback_migrate_page(mapping, newpage, page);
612 if (rc) {
613 newpage->mapping = NULL;
614 } else {
615 if (remap_swapcache)
616 remove_migration_ptes(page, newpage);
619 unlock_page(newpage);
621 return rc;
625 * Obtain the lock on page, remove all ptes and migrate the page
626 * to the newly allocated page in newpage.
628 static int unmap_and_move(new_page_t get_new_page, unsigned long private,
629 struct page *page, int force, bool offlining, bool sync)
631 int rc = 0;
632 int *result = NULL;
633 struct page *newpage = get_new_page(page, private, &result);
634 int remap_swapcache = 1;
635 int charge = 0;
636 struct mem_cgroup *mem;
637 struct anon_vma *anon_vma = NULL;
639 if (!newpage)
640 return -ENOMEM;
642 if (page_count(page) == 1) {
643 /* page was freed from under us. So we are done. */
644 goto move_newpage;
646 if (unlikely(PageTransHuge(page)))
647 if (unlikely(split_huge_page(page)))
648 goto move_newpage;
650 /* prepare cgroup just returns 0 or -ENOMEM */
651 rc = -EAGAIN;
653 if (!trylock_page(page)) {
654 if (!force || !sync)
655 goto move_newpage;
658 * It's not safe for direct compaction to call lock_page.
659 * For example, during page readahead pages are added locked
660 * to the LRU. Later, when the IO completes the pages are
661 * marked uptodate and unlocked. However, the queueing
662 * could be merging multiple pages for one bio (e.g.
663 * mpage_readpages). If an allocation happens for the
664 * second or third page, the process can end up locking
665 * the same page twice and deadlocking. Rather than
666 * trying to be clever about what pages can be locked,
667 * avoid the use of lock_page for direct compaction
668 * altogether.
670 if (current->flags & PF_MEMALLOC)
671 goto move_newpage;
673 lock_page(page);
677 * Only memory hotplug's offline_pages() caller has locked out KSM,
678 * and can safely migrate a KSM page. The other cases have skipped
679 * PageKsm along with PageReserved - but it is only now when we have
680 * the page lock that we can be certain it will not go KSM beneath us
681 * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
682 * its pagecount raised, but only here do we take the page lock which
683 * serializes that).
685 if (PageKsm(page) && !offlining) {
686 rc = -EBUSY;
687 goto unlock;
690 /* charge against new page */
691 charge = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL);
692 if (charge == -ENOMEM) {
693 rc = -ENOMEM;
694 goto unlock;
696 BUG_ON(charge);
698 if (PageWriteback(page)) {
700 * For !sync, there is no point retrying as the retry loop
701 * is expected to be too short for PageWriteback to be cleared
703 if (!sync) {
704 rc = -EBUSY;
705 goto uncharge;
707 if (!force)
708 goto uncharge;
709 wait_on_page_writeback(page);
712 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
713 * we cannot notice that anon_vma is freed while we migrates a page.
714 * This get_anon_vma() delays freeing anon_vma pointer until the end
715 * of migration. File cache pages are no problem because of page_lock()
716 * File Caches may use write_page() or lock_page() in migration, then,
717 * just care Anon page here.
719 if (PageAnon(page)) {
721 * Only page_lock_anon_vma() understands the subtleties of
722 * getting a hold on an anon_vma from outside one of its mms.
724 anon_vma = page_get_anon_vma(page);
725 if (anon_vma) {
727 * Anon page
729 } else if (PageSwapCache(page)) {
731 * We cannot be sure that the anon_vma of an unmapped
732 * swapcache page is safe to use because we don't
733 * know in advance if the VMA that this page belonged
734 * to still exists. If the VMA and others sharing the
735 * data have been freed, then the anon_vma could
736 * already be invalid.
738 * To avoid this possibility, swapcache pages get
739 * migrated but are not remapped when migration
740 * completes
742 remap_swapcache = 0;
743 } else {
744 goto uncharge;
749 * Corner case handling:
750 * 1. When a new swap-cache page is read into, it is added to the LRU
751 * and treated as swapcache but it has no rmap yet.
752 * Calling try_to_unmap() against a page->mapping==NULL page will
753 * trigger a BUG. So handle it here.
754 * 2. An orphaned page (see truncate_complete_page) might have
755 * fs-private metadata. The page can be picked up due to memory
756 * offlining. Everywhere else except page reclaim, the page is
757 * invisible to the vm, so the page can not be migrated. So try to
758 * free the metadata, so the page can be freed.
760 if (!page->mapping) {
761 VM_BUG_ON(PageAnon(page));
762 if (page_has_private(page)) {
763 try_to_free_buffers(page);
764 goto uncharge;
766 goto skip_unmap;
769 /* Establish migration ptes or remove ptes */
770 try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
772 skip_unmap:
773 if (!page_mapped(page))
774 rc = move_to_new_page(newpage, page, remap_swapcache, sync);
776 if (rc && remap_swapcache)
777 remove_migration_ptes(page, page);
779 /* Drop an anon_vma reference if we took one */
780 if (anon_vma)
781 put_anon_vma(anon_vma);
783 uncharge:
784 if (!charge)
785 mem_cgroup_end_migration(mem, page, newpage, rc == 0);
786 unlock:
787 unlock_page(page);
789 move_newpage:
790 if (rc != -EAGAIN) {
792 * A page that has been migrated has all references
793 * removed and will be freed. A page that has not been
794 * migrated will have kepts its references and be
795 * restored.
797 list_del(&page->lru);
798 dec_zone_page_state(page, NR_ISOLATED_ANON +
799 page_is_file_cache(page));
800 putback_lru_page(page);
804 * Move the new page to the LRU. If migration was not successful
805 * then this will free the page.
807 putback_lru_page(newpage);
809 if (result) {
810 if (rc)
811 *result = rc;
812 else
813 *result = page_to_nid(newpage);
815 return rc;
819 * Counterpart of unmap_and_move_page() for hugepage migration.
821 * This function doesn't wait the completion of hugepage I/O
822 * because there is no race between I/O and migration for hugepage.
823 * Note that currently hugepage I/O occurs only in direct I/O
824 * where no lock is held and PG_writeback is irrelevant,
825 * and writeback status of all subpages are counted in the reference
826 * count of the head page (i.e. if all subpages of a 2MB hugepage are
827 * under direct I/O, the reference of the head page is 512 and a bit more.)
828 * This means that when we try to migrate hugepage whose subpages are
829 * doing direct I/O, some references remain after try_to_unmap() and
830 * hugepage migration fails without data corruption.
832 * There is also no race when direct I/O is issued on the page under migration,
833 * because then pte is replaced with migration swap entry and direct I/O code
834 * will wait in the page fault for migration to complete.
836 static int unmap_and_move_huge_page(new_page_t get_new_page,
837 unsigned long private, struct page *hpage,
838 int force, bool offlining, bool sync)
840 int rc = 0;
841 int *result = NULL;
842 struct page *new_hpage = get_new_page(hpage, private, &result);
843 struct anon_vma *anon_vma = NULL;
845 if (!new_hpage)
846 return -ENOMEM;
848 rc = -EAGAIN;
850 if (!trylock_page(hpage)) {
851 if (!force || !sync)
852 goto out;
853 lock_page(hpage);
856 if (PageAnon(hpage))
857 anon_vma = page_get_anon_vma(hpage);
859 try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
861 if (!page_mapped(hpage))
862 rc = move_to_new_page(new_hpage, hpage, 1, sync);
864 if (rc)
865 remove_migration_ptes(hpage, hpage);
867 if (anon_vma)
868 put_anon_vma(anon_vma);
869 out:
870 unlock_page(hpage);
872 if (rc != -EAGAIN) {
873 list_del(&hpage->lru);
874 put_page(hpage);
877 put_page(new_hpage);
879 if (result) {
880 if (rc)
881 *result = rc;
882 else
883 *result = page_to_nid(new_hpage);
885 return rc;
889 * migrate_pages
891 * The function takes one list of pages to migrate and a function
892 * that determines from the page to be migrated and the private data
893 * the target of the move and allocates the page.
895 * The function returns after 10 attempts or if no pages
896 * are movable anymore because to has become empty
897 * or no retryable pages exist anymore.
898 * Caller should call putback_lru_pages to return pages to the LRU
899 * or free list only if ret != 0.
901 * Return: Number of pages not migrated or error code.
903 int migrate_pages(struct list_head *from,
904 new_page_t get_new_page, unsigned long private, bool offlining,
905 bool sync)
907 int retry = 1;
908 int nr_failed = 0;
909 int pass = 0;
910 struct page *page;
911 struct page *page2;
912 int swapwrite = current->flags & PF_SWAPWRITE;
913 int rc;
915 if (!swapwrite)
916 current->flags |= PF_SWAPWRITE;
918 for(pass = 0; pass < 10 && retry; pass++) {
919 retry = 0;
921 list_for_each_entry_safe(page, page2, from, lru) {
922 cond_resched();
924 rc = unmap_and_move(get_new_page, private,
925 page, pass > 2, offlining,
926 sync);
928 switch(rc) {
929 case -ENOMEM:
930 goto out;
931 case -EAGAIN:
932 retry++;
933 break;
934 case 0:
935 break;
936 default:
937 /* Permanent failure */
938 nr_failed++;
939 break;
943 rc = 0;
944 out:
945 if (!swapwrite)
946 current->flags &= ~PF_SWAPWRITE;
948 if (rc)
949 return rc;
951 return nr_failed + retry;
954 int migrate_huge_pages(struct list_head *from,
955 new_page_t get_new_page, unsigned long private, bool offlining,
956 bool sync)
958 int retry = 1;
959 int nr_failed = 0;
960 int pass = 0;
961 struct page *page;
962 struct page *page2;
963 int rc;
965 for (pass = 0; pass < 10 && retry; pass++) {
966 retry = 0;
968 list_for_each_entry_safe(page, page2, from, lru) {
969 cond_resched();
971 rc = unmap_and_move_huge_page(get_new_page,
972 private, page, pass > 2, offlining,
973 sync);
975 switch(rc) {
976 case -ENOMEM:
977 goto out;
978 case -EAGAIN:
979 retry++;
980 break;
981 case 0:
982 break;
983 default:
984 /* Permanent failure */
985 nr_failed++;
986 break;
990 rc = 0;
991 out:
992 if (rc)
993 return rc;
995 return nr_failed + retry;
998 #ifdef CONFIG_NUMA
1000 * Move a list of individual pages
1002 struct page_to_node {
1003 unsigned long addr;
1004 struct page *page;
1005 int node;
1006 int status;
1009 static struct page *new_page_node(struct page *p, unsigned long private,
1010 int **result)
1012 struct page_to_node *pm = (struct page_to_node *)private;
1014 while (pm->node != MAX_NUMNODES && pm->page != p)
1015 pm++;
1017 if (pm->node == MAX_NUMNODES)
1018 return NULL;
1020 *result = &pm->status;
1022 return alloc_pages_exact_node(pm->node,
1023 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
1027 * Move a set of pages as indicated in the pm array. The addr
1028 * field must be set to the virtual address of the page to be moved
1029 * and the node number must contain a valid target node.
1030 * The pm array ends with node = MAX_NUMNODES.
1032 static int do_move_page_to_node_array(struct mm_struct *mm,
1033 struct page_to_node *pm,
1034 int migrate_all)
1036 int err;
1037 struct page_to_node *pp;
1038 LIST_HEAD(pagelist);
1040 down_read(&mm->mmap_sem);
1043 * Build a list of pages to migrate
1045 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
1046 struct vm_area_struct *vma;
1047 struct page *page;
1049 err = -EFAULT;
1050 vma = find_vma(mm, pp->addr);
1051 if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
1052 goto set_status;
1054 page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
1056 err = PTR_ERR(page);
1057 if (IS_ERR(page))
1058 goto set_status;
1060 err = -ENOENT;
1061 if (!page)
1062 goto set_status;
1064 /* Use PageReserved to check for zero page */
1065 if (PageReserved(page) || PageKsm(page))
1066 goto put_and_set;
1068 pp->page = page;
1069 err = page_to_nid(page);
1071 if (err == pp->node)
1073 * Node already in the right place
1075 goto put_and_set;
1077 err = -EACCES;
1078 if (page_mapcount(page) > 1 &&
1079 !migrate_all)
1080 goto put_and_set;
1082 err = isolate_lru_page(page);
1083 if (!err) {
1084 list_add_tail(&page->lru, &pagelist);
1085 inc_zone_page_state(page, NR_ISOLATED_ANON +
1086 page_is_file_cache(page));
1088 put_and_set:
1090 * Either remove the duplicate refcount from
1091 * isolate_lru_page() or drop the page ref if it was
1092 * not isolated.
1094 put_page(page);
1095 set_status:
1096 pp->status = err;
1099 err = 0;
1100 if (!list_empty(&pagelist)) {
1101 err = migrate_pages(&pagelist, new_page_node,
1102 (unsigned long)pm, 0, true);
1103 if (err)
1104 putback_lru_pages(&pagelist);
1107 up_read(&mm->mmap_sem);
1108 return err;
1112 * Migrate an array of page address onto an array of nodes and fill
1113 * the corresponding array of status.
1115 static int do_pages_move(struct mm_struct *mm, struct task_struct *task,
1116 unsigned long nr_pages,
1117 const void __user * __user *pages,
1118 const int __user *nodes,
1119 int __user *status, int flags)
1121 struct page_to_node *pm;
1122 nodemask_t task_nodes;
1123 unsigned long chunk_nr_pages;
1124 unsigned long chunk_start;
1125 int err;
1127 task_nodes = cpuset_mems_allowed(task);
1129 err = -ENOMEM;
1130 pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
1131 if (!pm)
1132 goto out;
1134 migrate_prep();
1137 * Store a chunk of page_to_node array in a page,
1138 * but keep the last one as a marker
1140 chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
1142 for (chunk_start = 0;
1143 chunk_start < nr_pages;
1144 chunk_start += chunk_nr_pages) {
1145 int j;
1147 if (chunk_start + chunk_nr_pages > nr_pages)
1148 chunk_nr_pages = nr_pages - chunk_start;
1150 /* fill the chunk pm with addrs and nodes from user-space */
1151 for (j = 0; j < chunk_nr_pages; j++) {
1152 const void __user *p;
1153 int node;
1155 err = -EFAULT;
1156 if (get_user(p, pages + j + chunk_start))
1157 goto out_pm;
1158 pm[j].addr = (unsigned long) p;
1160 if (get_user(node, nodes + j + chunk_start))
1161 goto out_pm;
1163 err = -ENODEV;
1164 if (node < 0 || node >= MAX_NUMNODES)
1165 goto out_pm;
1167 if (!node_state(node, N_HIGH_MEMORY))
1168 goto out_pm;
1170 err = -EACCES;
1171 if (!node_isset(node, task_nodes))
1172 goto out_pm;
1174 pm[j].node = node;
1177 /* End marker for this chunk */
1178 pm[chunk_nr_pages].node = MAX_NUMNODES;
1180 /* Migrate this chunk */
1181 err = do_move_page_to_node_array(mm, pm,
1182 flags & MPOL_MF_MOVE_ALL);
1183 if (err < 0)
1184 goto out_pm;
1186 /* Return status information */
1187 for (j = 0; j < chunk_nr_pages; j++)
1188 if (put_user(pm[j].status, status + j + chunk_start)) {
1189 err = -EFAULT;
1190 goto out_pm;
1193 err = 0;
1195 out_pm:
1196 free_page((unsigned long)pm);
1197 out:
1198 return err;
1202 * Determine the nodes of an array of pages and store it in an array of status.
1204 static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
1205 const void __user **pages, int *status)
1207 unsigned long i;
1209 down_read(&mm->mmap_sem);
1211 for (i = 0; i < nr_pages; i++) {
1212 unsigned long addr = (unsigned long)(*pages);
1213 struct vm_area_struct *vma;
1214 struct page *page;
1215 int err = -EFAULT;
1217 vma = find_vma(mm, addr);
1218 if (!vma || addr < vma->vm_start)
1219 goto set_status;
1221 page = follow_page(vma, addr, 0);
1223 err = PTR_ERR(page);
1224 if (IS_ERR(page))
1225 goto set_status;
1227 err = -ENOENT;
1228 /* Use PageReserved to check for zero page */
1229 if (!page || PageReserved(page) || PageKsm(page))
1230 goto set_status;
1232 err = page_to_nid(page);
1233 set_status:
1234 *status = err;
1236 pages++;
1237 status++;
1240 up_read(&mm->mmap_sem);
1244 * Determine the nodes of a user array of pages and store it in
1245 * a user array of status.
1247 static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1248 const void __user * __user *pages,
1249 int __user *status)
1251 #define DO_PAGES_STAT_CHUNK_NR 16
1252 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1253 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
1255 while (nr_pages) {
1256 unsigned long chunk_nr;
1258 chunk_nr = nr_pages;
1259 if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
1260 chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1262 if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
1263 break;
1265 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1267 if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
1268 break;
1270 pages += chunk_nr;
1271 status += chunk_nr;
1272 nr_pages -= chunk_nr;
1274 return nr_pages ? -EFAULT : 0;
1278 * Move a list of pages in the address space of the currently executing
1279 * process.
1281 SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
1282 const void __user * __user *, pages,
1283 const int __user *, nodes,
1284 int __user *, status, int, flags)
1286 const struct cred *cred = current_cred(), *tcred;
1287 struct task_struct *task;
1288 struct mm_struct *mm;
1289 int err;
1291 /* Check flags */
1292 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
1293 return -EINVAL;
1295 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1296 return -EPERM;
1298 /* Find the mm_struct */
1299 rcu_read_lock();
1300 task = pid ? find_task_by_vpid(pid) : current;
1301 if (!task) {
1302 rcu_read_unlock();
1303 return -ESRCH;
1305 mm = get_task_mm(task);
1306 rcu_read_unlock();
1308 if (!mm)
1309 return -EINVAL;
1312 * Check if this process has the right to modify the specified
1313 * process. The right exists if the process has administrative
1314 * capabilities, superuser privileges or the same
1315 * userid as the target process.
1317 rcu_read_lock();
1318 tcred = __task_cred(task);
1319 if (cred->euid != tcred->suid && cred->euid != tcred->uid &&
1320 cred->uid != tcred->suid && cred->uid != tcred->uid &&
1321 !capable(CAP_SYS_NICE)) {
1322 rcu_read_unlock();
1323 err = -EPERM;
1324 goto out;
1326 rcu_read_unlock();
1328 err = security_task_movememory(task);
1329 if (err)
1330 goto out;
1332 if (nodes) {
1333 err = do_pages_move(mm, task, nr_pages, pages, nodes, status,
1334 flags);
1335 } else {
1336 err = do_pages_stat(mm, nr_pages, pages, status);
1339 out:
1340 mmput(mm);
1341 return err;
1345 * Call migration functions in the vma_ops that may prepare
1346 * memory in a vm for migration. migration functions may perform
1347 * the migration for vmas that do not have an underlying page struct.
1349 int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1350 const nodemask_t *from, unsigned long flags)
1352 struct vm_area_struct *vma;
1353 int err = 0;
1355 for (vma = mm->mmap; vma && !err; vma = vma->vm_next) {
1356 if (vma->vm_ops && vma->vm_ops->migrate) {
1357 err = vma->vm_ops->migrate(vma, to, from, flags);
1358 if (err)
1359 break;
1362 return err;
1364 #endif