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-rw-r--r--mm/vmscan.c214
1 files changed, 180 insertions, 34 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6c30a8c59795..a537a7f16357 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -373,6 +373,43 @@ static pageout_t pageout(struct page *page, struct address_space *mapping)
373 return PAGE_CLEAN; 373 return PAGE_CLEAN;
374} 374}
375 375
376static int remove_mapping(struct address_space *mapping, struct page *page)
377{
378 if (!mapping)
379 return 0; /* truncate got there first */
380
381 write_lock_irq(&mapping->tree_lock);
382
383 /*
384 * The non-racy check for busy page. It is critical to check
385 * PageDirty _after_ making sure that the page is freeable and
386 * not in use by anybody. (pagecache + us == 2)
387 */
388 if (unlikely(page_count(page) != 2))
389 goto cannot_free;
390 smp_rmb();
391 if (unlikely(PageDirty(page)))
392 goto cannot_free;
393
394 if (PageSwapCache(page)) {
395 swp_entry_t swap = { .val = page_private(page) };
396 __delete_from_swap_cache(page);
397 write_unlock_irq(&mapping->tree_lock);
398 swap_free(swap);
399 __put_page(page); /* The pagecache ref */
400 return 1;
401 }
402
403 __remove_from_page_cache(page);
404 write_unlock_irq(&mapping->tree_lock);
405 __put_page(page);
406 return 1;
407
408cannot_free:
409 write_unlock_irq(&mapping->tree_lock);
410 return 0;
411}
412
376/* 413/*
377 * shrink_list adds the number of reclaimed pages to sc->nr_reclaimed 414 * shrink_list adds the number of reclaimed pages to sc->nr_reclaimed
378 */ 415 */
@@ -504,36 +541,8 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc)
504 goto free_it; 541 goto free_it;
505 } 542 }
506 543
507 if (!mapping) 544 if (!remove_mapping(mapping, page))
508 goto keep_locked; /* truncate got there first */ 545 goto keep_locked;
509
510 write_lock_irq(&mapping->tree_lock);
511
512 /*
513 * The non-racy check for busy page. It is critical to check
514 * PageDirty _after_ making sure that the page is freeable and
515 * not in use by anybody. (pagecache + us == 2)
516 */
517 if (unlikely(page_count(page) != 2))
518 goto cannot_free;
519 smp_rmb();
520 if (unlikely(PageDirty(page)))
521 goto cannot_free;
522
523#ifdef CONFIG_SWAP
524 if (PageSwapCache(page)) {
525 swp_entry_t swap = { .val = page_private(page) };
526 __delete_from_swap_cache(page);
527 write_unlock_irq(&mapping->tree_lock);
528 swap_free(swap);
529 __put_page(page); /* The pagecache ref */
530 goto free_it;
531 }
532#endif /* CONFIG_SWAP */
533
534 __remove_from_page_cache(page);
535 write_unlock_irq(&mapping->tree_lock);
536 __put_page(page);
537 546
538free_it: 547free_it:
539 unlock_page(page); 548 unlock_page(page);
@@ -542,10 +551,6 @@ free_it:
542 __pagevec_release_nonlru(&freed_pvec); 551 __pagevec_release_nonlru(&freed_pvec);
543 continue; 552 continue;
544 553
545cannot_free:
546 write_unlock_irq(&mapping->tree_lock);
547 goto keep_locked;
548
549activate_locked: 554activate_locked:
550 SetPageActive(page); 555 SetPageActive(page);
551 pgactivate++; 556 pgactivate++;
@@ -564,6 +569,147 @@ keep:
564} 569}
565 570
566/* 571/*
572 * swapout a single page
573 * page is locked upon entry, unlocked on exit
574 *
575 * return codes:
576 * 0 = complete
577 * 1 = retry
578 */
579static int swap_page(struct page *page)
580{
581 struct address_space *mapping = page_mapping(page);
582
583 if (page_mapped(page) && mapping)
584 if (try_to_unmap(page) != SWAP_SUCCESS)
585 goto unlock_retry;
586
587 if (PageDirty(page)) {
588 /* Page is dirty, try to write it out here */
589 switch(pageout(page, mapping)) {
590 case PAGE_KEEP:
591 case PAGE_ACTIVATE:
592 goto unlock_retry;
593
594 case PAGE_SUCCESS:
595 goto retry;
596
597 case PAGE_CLEAN:
598 ; /* try to free the page below */
599 }
600 }
601
602 if (PagePrivate(page)) {
603 if (!try_to_release_page(page, GFP_KERNEL) ||
604 (!mapping && page_count(page) == 1))
605 goto unlock_retry;
606 }
607
608 if (remove_mapping(mapping, page)) {
609 /* Success */
610 unlock_page(page);
611 return 0;
612 }
613
614unlock_retry:
615 unlock_page(page);
616
617retry:
618 return 1;
619}
620/*
621 * migrate_pages
622 *
623 * Two lists are passed to this function. The first list
624 * contains the pages isolated from the LRU to be migrated.
625 * The second list contains new pages that the pages isolated
626 * can be moved to. If the second list is NULL then all
627 * pages are swapped out.
628 *
629 * The function returns after 10 attempts or if no pages
630 * are movable anymore because t has become empty
631 * or no retryable pages exist anymore.
632 *
633 * SIMPLIFIED VERSION: This implementation of migrate_pages
634 * is only swapping out pages and never touches the second
635 * list. The direct migration patchset
636 * extends this function to avoid the use of swap.
637 */
638int migrate_pages(struct list_head *l, struct list_head *t)
639{
640 int retry;
641 LIST_HEAD(failed);
642 int nr_failed = 0;
643 int pass = 0;
644 struct page *page;
645 struct page *page2;
646 int swapwrite = current->flags & PF_SWAPWRITE;
647
648 if (!swapwrite)
649 current->flags |= PF_SWAPWRITE;
650
651redo:
652 retry = 0;
653
654 list_for_each_entry_safe(page, page2, l, lru) {
655 cond_resched();
656
657 /*
658 * Skip locked pages during the first two passes to give the
659 * functions holding the lock time to release the page. Later we use
660 * lock_page to have a higher chance of acquiring the lock.
661 */
662 if (pass > 2)
663 lock_page(page);
664 else
665 if (TestSetPageLocked(page))
666 goto retry_later;
667
668 /*
669 * Only wait on writeback if we have already done a pass where
670 * we we may have triggered writeouts for lots of pages.
671 */
672 if (pass > 0)
673 wait_on_page_writeback(page);
674 else
675 if (PageWriteback(page)) {
676 unlock_page(page);
677 goto retry_later;
678 }
679
680#ifdef CONFIG_SWAP
681 if (PageAnon(page) && !PageSwapCache(page)) {
682 if (!add_to_swap(page)) {
683 unlock_page(page);
684 list_move(&page->lru, &failed);
685 nr_failed++;
686 continue;
687 }
688 }
689#endif /* CONFIG_SWAP */
690
691 /*
692 * Page is properly locked and writeback is complete.
693 * Try to migrate the page.
694 */
695 if (swap_page(page)) {
696retry_later:
697 retry++;
698 }
699 }
700 if (retry && pass++ < 10)
701 goto redo;
702
703 if (!swapwrite)
704 current->flags &= ~PF_SWAPWRITE;
705
706 if (!list_empty(&failed))
707 list_splice(&failed, l);
708
709 return nr_failed + retry;
710}
711
712/*
567 * zone->lru_lock is heavily contended. Some of the functions that 713 * zone->lru_lock is heavily contended. Some of the functions that
568 * shrink the lists perform better by taking out a batch of pages 714 * shrink the lists perform better by taking out a batch of pages
569 * and working on them outside the LRU lock. 715 * and working on them outside the LRU lock.