From: Lee Schermerhorn Date: Sun, 30 Oct 2005 01:15:51 +0000 (-0700) Subject: [PATCH] shrink_list(): skip anon pages if not may_swap X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c340010e4bf824d969a89fa192ecc7a526c0cd24;p=openwrt%2Fstaging%2Fblogic.git [PATCH] shrink_list(): skip anon pages if not may_swap Martin Hicks' page cache reclaim patch added the 'may_swap' flag to the scan_control struct; and modified shrink_list() not to add anon pages to the swap cache if may_swap is not asserted. Ref: http://marc.theaimsgroup.com/?l=linux-mm&m=111461480725322&w=4 However, further down, if the page is mapped, shrink_list() calls try_to_unmap() which will call try_to_unmap_one() via try_to_unmap_anon (). try_to_unmap_one() will BUG_ON() an anon page that is NOT in the swap cache. Martin says he never encountered this path in his testing, but agrees that it might happen. This patch modifies shrink_list() to skip anon pages that are not already in the swap cache when !may_swap, rather than just not adding them to the cache. Signed-off-by: Lee Schermerhorn Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/vmscan.c b/mm/vmscan.c index 843c87d1e61f..41d1064aabfb 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -417,7 +417,9 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc) * Anonymous process memory has backing store? * Try to allocate it some swap space here. */ - if (PageAnon(page) && !PageSwapCache(page) && sc->may_swap) { + if (PageAnon(page) && !PageSwapCache(page)) { + if (!sc->may_swap) + goto keep_locked; if (!add_to_swap(page)) goto activate_locked; }