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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - mm/migrate.c
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 <clameter@sgi.com>
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/pagevec.h>
23 #include <linux/rmap.h>
24 #include <linux/topology.h>
25 #include <linux/cpu.h>
26 #include <linux/cpuset.h>
27 #include <linux/writeback.h>
28 #include <linux/mempolicy.h>
29 #include <linux/vmalloc.h>
33 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
36 * Isolate one page from the LRU lists. If successful put it onto
37 * the indicated list with elevated page count.
40 * -EBUSY: page not on LRU list
41 * 0: page removed from LRU list and added to the specified list.
43 int isolate_lru_page(struct page
*page
, struct list_head
*pagelist
)
48 struct zone
*zone
= page_zone(page
);
50 spin_lock_irq(&zone
->lru_lock
);
56 del_page_from_active_list(zone
, page
);
58 del_page_from_inactive_list(zone
, page
);
59 list_add_tail(&page
->lru
, pagelist
);
61 spin_unlock_irq(&zone
->lru_lock
);
67 * migrate_prep() needs to be called before we start compiling a list of pages
68 * to be migrated using isolate_lru_page().
70 int migrate_prep(void)
73 * Clear the LRU lists so pages can be isolated.
74 * Note that pages may be moved off the LRU after we have
75 * drained them. Those pages will fail to migrate like other
76 * pages that may be busy.
83 static inline void move_to_lru(struct page
*page
)
85 if (PageActive(page
)) {
87 * lru_cache_add_active checks that
88 * the PG_active bit is off.
90 ClearPageActive(page
);
91 lru_cache_add_active(page
);
99 * Add isolated pages on the list back to the LRU.
101 * returns the number of pages put back.
103 int putback_lru_pages(struct list_head
*l
)
109 list_for_each_entry_safe(page
, page2
, l
, lru
) {
110 list_del(&page
->lru
);
117 static inline int is_swap_pte(pte_t pte
)
119 return !pte_none(pte
) && !pte_present(pte
) && !pte_file(pte
);
123 * Restore a potential migration pte to a working pte entry
125 static void remove_migration_pte(struct vm_area_struct
*vma
,
126 struct page
*old
, struct page
*new)
128 struct mm_struct
*mm
= vma
->vm_mm
;
135 unsigned long addr
= page_address_in_vma(new, vma
);
140 pgd
= pgd_offset(mm
, addr
);
141 if (!pgd_present(*pgd
))
144 pud
= pud_offset(pgd
, addr
);
145 if (!pud_present(*pud
))
148 pmd
= pmd_offset(pud
, addr
);
149 if (!pmd_present(*pmd
))
152 ptep
= pte_offset_map(pmd
, addr
);
154 if (!is_swap_pte(*ptep
)) {
159 ptl
= pte_lockptr(mm
, pmd
);
162 if (!is_swap_pte(pte
))
165 entry
= pte_to_swp_entry(pte
);
167 if (!is_migration_entry(entry
) || migration_entry_to_page(entry
) != old
)
171 pte
= pte_mkold(mk_pte(new, vma
->vm_page_prot
));
172 if (is_write_migration_entry(entry
))
173 pte
= pte_mkwrite(pte
);
174 set_pte_at(mm
, addr
, ptep
, pte
);
177 page_add_anon_rmap(new, vma
, addr
);
179 page_add_file_rmap(new);
181 /* No need to invalidate - it was non-present before */
182 update_mmu_cache(vma
, addr
, pte
);
183 lazy_mmu_prot_update(pte
);
186 pte_unmap_unlock(ptep
, ptl
);
190 * Note that remove_file_migration_ptes will only work on regular mappings,
191 * Nonlinear mappings do not use migration entries.
193 static void remove_file_migration_ptes(struct page
*old
, struct page
*new)
195 struct vm_area_struct
*vma
;
196 struct address_space
*mapping
= page_mapping(new);
197 struct prio_tree_iter iter
;
198 pgoff_t pgoff
= new->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
203 spin_lock(&mapping
->i_mmap_lock
);
205 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
)
206 remove_migration_pte(vma
, old
, new);
208 spin_unlock(&mapping
->i_mmap_lock
);
212 * Must hold mmap_sem lock on at least one of the vmas containing
213 * the page so that the anon_vma cannot vanish.
215 static void remove_anon_migration_ptes(struct page
*old
, struct page
*new)
217 struct anon_vma
*anon_vma
;
218 struct vm_area_struct
*vma
;
219 unsigned long mapping
;
221 mapping
= (unsigned long)new->mapping
;
223 if (!mapping
|| (mapping
& PAGE_MAPPING_ANON
) == 0)
227 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
229 anon_vma
= (struct anon_vma
*) (mapping
- PAGE_MAPPING_ANON
);
230 spin_lock(&anon_vma
->lock
);
232 list_for_each_entry(vma
, &anon_vma
->head
, anon_vma_node
)
233 remove_migration_pte(vma
, old
, new);
235 spin_unlock(&anon_vma
->lock
);
239 * Get rid of all migration entries and replace them by
240 * references to the indicated page.
242 static void remove_migration_ptes(struct page
*old
, struct page
*new)
245 remove_anon_migration_ptes(old
, new);
247 remove_file_migration_ptes(old
, new);
251 * Something used the pte of a page under migration. We need to
252 * get to the page and wait until migration is finished.
253 * When we return from this function the fault will be retried.
255 * This function is called from do_swap_page().
257 void migration_entry_wait(struct mm_struct
*mm
, pmd_t
*pmd
,
258 unsigned long address
)
265 ptep
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
267 if (!is_swap_pte(pte
))
270 entry
= pte_to_swp_entry(pte
);
271 if (!is_migration_entry(entry
))
274 page
= migration_entry_to_page(entry
);
277 pte_unmap_unlock(ptep
, ptl
);
278 wait_on_page_locked(page
);
282 pte_unmap_unlock(ptep
, ptl
);
286 * Replace the page in the mapping.
288 * The number of remaining references must be:
289 * 1 for anonymous pages without a mapping
290 * 2 for pages with a mapping
291 * 3 for pages with a mapping and PagePrivate set.
293 static int migrate_page_move_mapping(struct address_space
*mapping
,
294 struct page
*newpage
, struct page
*page
)
296 struct page
**radix_pointer
;
300 if (page_count(page
) != 1)
305 write_lock_irq(&mapping
->tree_lock
);
307 radix_pointer
= (struct page
**)radix_tree_lookup_slot(
311 if (page_count(page
) != 2 + !!PagePrivate(page
) ||
312 *radix_pointer
!= page
) {
313 write_unlock_irq(&mapping
->tree_lock
);
318 * Now we know that no one else is looking at the page.
322 if (PageSwapCache(page
)) {
323 SetPageSwapCache(newpage
);
324 set_page_private(newpage
, page_private(page
));
328 *radix_pointer
= newpage
;
330 write_unlock_irq(&mapping
->tree_lock
);
336 * Copy the page to its new location
338 static void migrate_page_copy(struct page
*newpage
, struct page
*page
)
340 copy_highpage(newpage
, page
);
343 SetPageError(newpage
);
344 if (PageReferenced(page
))
345 SetPageReferenced(newpage
);
346 if (PageUptodate(page
))
347 SetPageUptodate(newpage
);
348 if (PageActive(page
))
349 SetPageActive(newpage
);
350 if (PageChecked(page
))
351 SetPageChecked(newpage
);
352 if (PageMappedToDisk(page
))
353 SetPageMappedToDisk(newpage
);
355 if (PageDirty(page
)) {
356 clear_page_dirty_for_io(page
);
357 set_page_dirty(newpage
);
361 ClearPageSwapCache(page
);
363 ClearPageActive(page
);
364 ClearPagePrivate(page
);
365 set_page_private(page
, 0);
366 page
->mapping
= NULL
;
369 * If any waiters have accumulated on the new page then
372 if (PageWriteback(newpage
))
373 end_page_writeback(newpage
);
376 /************************************************************
377 * Migration functions
378 ***********************************************************/
380 /* Always fail migration. Used for mappings that are not movable */
381 int fail_migrate_page(struct address_space
*mapping
,
382 struct page
*newpage
, struct page
*page
)
386 EXPORT_SYMBOL(fail_migrate_page
);
389 * Common logic to directly migrate a single page suitable for
390 * pages that do not use PagePrivate.
392 * Pages are locked upon entry and exit.
394 int migrate_page(struct address_space
*mapping
,
395 struct page
*newpage
, struct page
*page
)
399 BUG_ON(PageWriteback(page
)); /* Writeback must be complete */
401 rc
= migrate_page_move_mapping(mapping
, newpage
, page
);
406 migrate_page_copy(newpage
, page
);
409 EXPORT_SYMBOL(migrate_page
);
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"
416 int buffer_migrate_page(struct address_space
*mapping
,
417 struct page
*newpage
, struct page
*page
)
419 struct buffer_head
*bh
, *head
;
422 if (!page_has_buffers(page
))
423 return migrate_page(mapping
, newpage
, page
);
425 head
= page_buffers(page
);
427 rc
= migrate_page_move_mapping(mapping
, newpage
, page
);
436 bh
= bh
->b_this_page
;
438 } while (bh
!= head
);
440 ClearPagePrivate(page
);
441 set_page_private(newpage
, page_private(page
));
442 set_page_private(page
, 0);
448 set_bh_page(bh
, newpage
, bh_offset(bh
));
449 bh
= bh
->b_this_page
;
451 } while (bh
!= head
);
453 SetPagePrivate(newpage
);
455 migrate_page_copy(newpage
, page
);
461 bh
= bh
->b_this_page
;
463 } while (bh
!= head
);
467 EXPORT_SYMBOL(buffer_migrate_page
);
470 * Writeback a page to clean the dirty state
472 static int writeout(struct address_space
*mapping
, struct page
*page
)
474 struct writeback_control wbc
= {
475 .sync_mode
= WB_SYNC_NONE
,
478 .range_end
= LLONG_MAX
,
484 if (!mapping
->a_ops
->writepage
)
485 /* No write method for the address space */
488 if (!clear_page_dirty_for_io(page
))
489 /* Someone else already triggered a write */
493 * A dirty page may imply that the underlying filesystem has
494 * the page on some queue. So the page must be clean for
495 * migration. Writeout may mean we loose the lock and the
496 * page state is no longer what we checked for earlier.
497 * At this point we know that the migration attempt cannot
500 remove_migration_ptes(page
, page
);
502 rc
= mapping
->a_ops
->writepage(page
, &wbc
);
504 /* I/O Error writing */
507 if (rc
!= AOP_WRITEPAGE_ACTIVATE
)
508 /* unlocked. Relock */
515 * Default handling if a filesystem does not provide a migration function.
517 static int fallback_migrate_page(struct address_space
*mapping
,
518 struct page
*newpage
, struct page
*page
)
521 return writeout(mapping
, page
);
524 * Buffers may be managed in a filesystem specific way.
525 * We must have no buffers or drop them.
527 if (page_has_buffers(page
) &&
528 !try_to_release_page(page
, GFP_KERNEL
))
531 return migrate_page(mapping
, newpage
, page
);
535 * Move a page to a newly allocated page
536 * The page is locked and all ptes have been successfully removed.
538 * The new page will have replaced the old page if this function
541 static int move_to_new_page(struct page
*newpage
, struct page
*page
)
543 struct address_space
*mapping
;
547 * Block others from accessing the page when we get around to
548 * establishing additional references. We are the only one
549 * holding a reference to the new page at this point.
551 if (TestSetPageLocked(newpage
))
554 /* Prepare mapping for the new page.*/
555 newpage
->index
= page
->index
;
556 newpage
->mapping
= page
->mapping
;
558 mapping
= page_mapping(page
);
560 rc
= migrate_page(mapping
, newpage
, page
);
561 else if (mapping
->a_ops
->migratepage
)
563 * Most pages have a mapping and most filesystems
564 * should provide a migration function. Anonymous
565 * pages are part of swap space which also has its
566 * own migration function. This is the most common
567 * path for page migration.
569 rc
= mapping
->a_ops
->migratepage(mapping
,
572 rc
= fallback_migrate_page(mapping
, newpage
, page
);
575 remove_migration_ptes(page
, newpage
);
577 newpage
->mapping
= NULL
;
579 unlock_page(newpage
);
585 * Obtain the lock on page, remove all ptes and migrate the page
586 * to the newly allocated page in newpage.
588 static int unmap_and_move(new_page_t get_new_page
, unsigned long private,
589 struct page
*page
, int force
)
593 struct page
*newpage
= get_new_page(page
, private, &result
);
598 if (page_count(page
) == 1)
599 /* page was freed from under us. So we are done. */
603 if (TestSetPageLocked(page
)) {
609 if (PageWriteback(page
)) {
612 wait_on_page_writeback(page
);
616 * Establish migration ptes or remove ptes
618 if (try_to_unmap(page
, 1) != SWAP_FAIL
) {
619 if (!page_mapped(page
))
620 rc
= move_to_new_page(newpage
, page
);
622 /* A vma has VM_LOCKED set -> permanent failure */
626 remove_migration_ptes(page
, page
);
632 * A page that has been migrated has all references
633 * removed and will be freed. A page that has not been
634 * migrated will have kepts its references and be
637 list_del(&page
->lru
);
643 * Move the new page to the LRU. If migration was not successful
644 * then this will free the page.
646 move_to_lru(newpage
);
651 *result
= page_to_nid(newpage
);
659 * The function takes one list of pages to migrate and a function
660 * that determines from the page to be migrated and the private data
661 * the target of the move and allocates the page.
663 * The function returns after 10 attempts or if no pages
664 * are movable anymore because to has become empty
665 * or no retryable pages exist anymore. All pages will be
666 * retruned to the LRU or freed.
668 * Return: Number of pages not migrated or error code.
670 int migrate_pages(struct list_head
*from
,
671 new_page_t get_new_page
, unsigned long private)
678 int swapwrite
= current
->flags
& PF_SWAPWRITE
;
682 current
->flags
|= PF_SWAPWRITE
;
684 for(pass
= 0; pass
< 10 && retry
; pass
++) {
687 list_for_each_entry_safe(page
, page2
, from
, lru
) {
690 rc
= unmap_and_move(get_new_page
, private,
702 /* Permanent failure */
711 current
->flags
&= ~PF_SWAPWRITE
;
713 putback_lru_pages(from
);
718 return nr_failed
+ retry
;
723 * Move a list of individual pages
725 struct page_to_node
{
732 static struct page
*new_page_node(struct page
*p
, unsigned long private,
735 struct page_to_node
*pm
= (struct page_to_node
*)private;
737 while (pm
->node
!= MAX_NUMNODES
&& pm
->page
!= p
)
740 if (pm
->node
== MAX_NUMNODES
)
743 *result
= &pm
->status
;
745 return alloc_pages_node(pm
->node
, GFP_HIGHUSER
, 0);
749 * Move a set of pages as indicated in the pm array. The addr
750 * field must be set to the virtual address of the page to be moved
751 * and the node number must contain a valid target node.
753 static int do_move_pages(struct mm_struct
*mm
, struct page_to_node
*pm
,
757 struct page_to_node
*pp
;
760 down_read(&mm
->mmap_sem
);
763 * Build a list of pages to migrate
766 for (pp
= pm
; pp
->node
!= MAX_NUMNODES
; pp
++) {
767 struct vm_area_struct
*vma
;
771 * A valid page pointer that will not match any of the
772 * pages that will be moved.
774 pp
->page
= ZERO_PAGE(0);
777 vma
= find_vma(mm
, pp
->addr
);
781 page
= follow_page(vma
, pp
->addr
, FOLL_GET
);
786 if (PageReserved(page
)) /* Check for zero page */
790 err
= page_to_nid(page
);
794 * Node already in the right place
799 if (page_mapcount(page
) > 1 &&
803 err
= isolate_lru_page(page
, &pagelist
);
806 * Either remove the duplicate refcount from
807 * isolate_lru_page() or drop the page ref if it was
815 if (!list_empty(&pagelist
))
816 err
= migrate_pages(&pagelist
, new_page_node
,
821 up_read(&mm
->mmap_sem
);
826 * Determine the nodes of a list of pages. The addr in the pm array
827 * must have been set to the virtual address of which we want to determine
830 static int do_pages_stat(struct mm_struct
*mm
, struct page_to_node
*pm
)
832 down_read(&mm
->mmap_sem
);
834 for ( ; pm
->node
!= MAX_NUMNODES
; pm
++) {
835 struct vm_area_struct
*vma
;
840 vma
= find_vma(mm
, pm
->addr
);
844 page
= follow_page(vma
, pm
->addr
, 0);
846 /* Use PageReserved to check for zero page */
847 if (!page
|| PageReserved(page
))
850 err
= page_to_nid(page
);
855 up_read(&mm
->mmap_sem
);
860 * Move a list of pages in the address space of the currently executing
863 asmlinkage
long sys_move_pages(pid_t pid
, unsigned long nr_pages
,
864 const void __user
* __user
*pages
,
865 const int __user
*nodes
,
866 int __user
*status
, int flags
)
870 struct task_struct
*task
;
871 nodemask_t task_nodes
;
872 struct mm_struct
*mm
;
873 struct page_to_node
*pm
= NULL
;
876 if (flags
& ~(MPOL_MF_MOVE
|MPOL_MF_MOVE_ALL
))
879 if ((flags
& MPOL_MF_MOVE_ALL
) && !capable(CAP_SYS_NICE
))
882 /* Find the mm_struct */
883 read_lock(&tasklist_lock
);
884 task
= pid
? find_task_by_pid(pid
) : current
;
886 read_unlock(&tasklist_lock
);
889 mm
= get_task_mm(task
);
890 read_unlock(&tasklist_lock
);
896 * Check if this process has the right to modify the specified
897 * process. The right exists if the process has administrative
898 * capabilities, superuser privileges or the same
899 * userid as the target process.
901 if ((current
->euid
!= task
->suid
) && (current
->euid
!= task
->uid
) &&
902 (current
->uid
!= task
->suid
) && (current
->uid
!= task
->uid
) &&
903 !capable(CAP_SYS_NICE
)) {
908 task_nodes
= cpuset_mems_allowed(task
);
910 /* Limit nr_pages so that the multiplication may not overflow */
911 if (nr_pages
>= ULONG_MAX
/ sizeof(struct page_to_node
) - 1) {
916 pm
= vmalloc((nr_pages
+ 1) * sizeof(struct page_to_node
));
923 * Get parameters from user space and initialize the pm
924 * array. Return various errors if the user did something wrong.
926 for (i
= 0; i
< nr_pages
; i
++) {
930 if (get_user(p
, pages
+ i
))
933 pm
[i
].addr
= (unsigned long)p
;
937 if (get_user(node
, nodes
+ i
))
941 if (!node_online(node
))
945 if (!node_isset(node
, task_nodes
))
952 pm
[nr_pages
].node
= MAX_NUMNODES
;
955 err
= do_move_pages(mm
, pm
, flags
& MPOL_MF_MOVE_ALL
);
957 err
= do_pages_stat(mm
, pm
);
960 /* Return status information */
961 for (i
= 0; i
< nr_pages
; i
++)
962 if (put_user(pm
[i
].status
, status
+ i
))