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authorMinchan Kim <minchan.kim@gmail.com>2009-08-26 17:29:23 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-08-26 23:06:52 -0400
commit03ef83af528899aa339e42d8024b37e2f434fba4 (patch)
tree1a323ead874d690de79cd213d5231b4fc758979b /mm
parentb62e408c05228f40e69bb38a48db8961cac6cd23 (diff)
mm: fix for infinite churning of mlocked pages
An mlocked page might lose the isolatation race. This causes the page to clear PG_mlocked while it remains in a VM_LOCKED vma. This means it can be put onto the [in]active list. We can rescue it by using try_to_unmap() in shrink_page_list(). But now, As Wu Fengguang pointed out, vmscan has a bug. If the page has PG_referenced, it can't reach try_to_unmap() in shrink_page_list() but is put into the active list. If the page is referenced repeatedly, it can remain on the [in]active list without being moving to the unevictable list. This patch fixes it. Reported-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <<kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/rmap.c1
-rw-r--r--mm/vmscan.c9
2 files changed, 8 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 836c6c63e1f2..0895b5c7cbff 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -358,6 +358,7 @@ static int page_referenced_one(struct page *page,
358 */ 358 */
359 if (vma->vm_flags & VM_LOCKED) { 359 if (vma->vm_flags & VM_LOCKED) {
360 *mapcount = 1; /* break early from loop */ 360 *mapcount = 1; /* break early from loop */
361 *vm_flags |= VM_LOCKED;
361 goto out_unmap; 362 goto out_unmap;
362 } 363 }
363 364
diff --git a/mm/vmscan.c b/mm/vmscan.c
index dea7abd31098..94e86dd6954c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -630,9 +630,14 @@ static unsigned long shrink_page_list(struct list_head *page_list,
630 630
631 referenced = page_referenced(page, 1, 631 referenced = page_referenced(page, 1,
632 sc->mem_cgroup, &vm_flags); 632 sc->mem_cgroup, &vm_flags);
633 /* In active use or really unfreeable? Activate it. */ 633 /*
634 * In active use or really unfreeable? Activate it.
635 * If page which have PG_mlocked lost isoltation race,
636 * try_to_unmap moves it to unevictable list
637 */
634 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && 638 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
635 referenced && page_mapping_inuse(page)) 639 referenced && page_mapping_inuse(page)
640 && !(vm_flags & VM_LOCKED))
636 goto activate_locked; 641 goto activate_locked;
637 642
638 /* 643 /*