diff options
| author | Minchan Kim <minchan.kim@gmail.com> | 2009-08-26 14:29:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-08-26 20:06:52 -0700 |
| commit | 03ef83af528899aa339e42d8024b37e2f434fba4 (patch) | |
| tree | 1a323ead874d690de79cd213d5231b4fc758979b | |
| parent | b62e408c05228f40e69bb38a48db8961cac6cd23 (diff) | |
| download | lwn-03ef83af528899aa339e42d8024b37e2f434fba4.tar.gz lwn-03ef83af528899aa339e42d8024b37e2f434fba4.zip | |
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>
| -rw-r--r-- | mm/rmap.c | 1 | ||||
| -rw-r--r-- | mm/vmscan.c | 9 |
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, */ if (vma->vm_flags & VM_LOCKED) { *mapcount = 1; /* break early from loop */ + *vm_flags |= VM_LOCKED; goto out_unmap; } 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, referenced = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); - /* In active use or really unfreeable? Activate it. */ + /* + * In active use or really unfreeable? Activate it. + * If page which have PG_mlocked lost isoltation race, + * try_to_unmap moves it to unevictable list + */ if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && - referenced && page_mapping_inuse(page)) + referenced && page_mapping_inuse(page) + && !(vm_flags & VM_LOCKED)) goto activate_locked; /* |