On Mon, Feb 02, 2015 at 04:00:51PM +0100, Michal Hocko wrote: > From: Michal Hocko <mhocko@xxxxxxx> > Date: Mon, 2 Feb 2015 15:22:19 +0100 > Subject: [PATCH] memcg, shmem: fix shmem migration to use lrucare. > > It has been reported that 965GM might trigger > > VM_BUG_ON_PAGE(!lrucare && PageLRU(oldpage), oldpage) > > in mem_cgroup_migrate when shmem wants to replace a swap cache page > because of shmem_should_replace_page (the page is allocated from an > inappropriate zone). shmem_replace_page expects that the oldpage is not > on LRU list and calls mem_cgroup_migrate without lrucare. This is obviously > incorrect because swapcache pages might be on the LRU list (e.g. swapin > readahead page). > > Fix this by enabling lrucare for the migration in shmem_replace_page. > Also clarify that lrucare should be used even if one of the pages might > be on LRU list. > > The BUG_ON will trigger only when CONFIG_DEBUG_VM is enabled but even > without that the migration code might leave the old page on an > inappropriate memcg' LRU which is not that critical because the page > would get removed with its last reference but it is still confusing. > > Fixes: 0a31bc97c80c (mm: memcontrol: rewrite uncharge API) > Cc: stable@xxxxxxxxxxxxxxx # 3.17+ > Reported-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Reported-by: Dave Airlie <airlied@xxxxxxxxx> > Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> > Signed-off-by: Michal Hocko <mhocko@xxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Thanks, Michal. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>