From: Minchan Kim Date: Wed, 22 Sep 2010 20:05:01 +0000 (-0700) Subject: vmscan: check all_unreclaimable in direct reclaim path X-Git-Tag: v2.6.36-rc6~68 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d1908362ae0b97374eb8328fbb471576332f9fb1;p=pandora-kernel.git vmscan: check all_unreclaimable in direct reclaim path M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his 32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771). Also he bisected the regression to commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c Author: KOSAKI Motohiro Date: Fri Jun 4 14:15:05 2010 -0700 vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure At first impression, this seemed very strange because the above commit only chenged function return value and hibernate_preallocate_memory() ignore return value of shrink_all_memory(). But it's related. Now, page allocation from hibernation code may enter infinite loop if the system has highmem. The reasons are that vmscan don't care enough OOM case when oom_killer_disabled. The problem sequence is following as. 1. hibernation 2. oom_disable 3. alloc_pages 4. do_try_to_free_pages if (scanning_global_lru(sc) && !all_unreclaimable) return 1; If kswapd is not freozen, it would set zone->all_unreclaimable to 1 and then shrink_zones maybe return true(ie, all_unreclaimable is true). So at last, alloc_pages could go to _nopage_. If it is, it should have no problem. This patch adds all_unreclaimable check to protect in direct reclaim path, too. It can care of hibernation OOM case and help bailout all_unreclaimable case slightly. Signed-off-by: KOSAKI Motohiro Signed-off-by: Minchan Kim Reported-by: M. Vefa Bicakci Reported-by: Reviewed-by: Johannes Weiner Tested-by: Acked-by: Rafael J. Wysocki Acked-by: Rik van Riel Acked-by: KAMEZAWA Hiroyuki Cc: Balbir Singh Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed