On Tue, Jan 17, 2017 at 11:16:08PM +0100, Vlastimil Babka wrote: > Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode triggers > OOM killer in few seconds, despite lots of free memory. The test attemps to > repeatedly fault in memory in one process in a cpuset, while changing allowed > nodes of the cpuset between 0 and 1 in another process. > > One possible cause is that in the fast path we find the preferred zoneref > according to current mems_allowed, so that it points to the middle of the > zonelist, skipping e.g. zones of node 1 completely. If the mems_allowed is > updated to contain only node 1, we never reach it in the zonelist, and trigger > OOM before checking the cpuset_mems_cookie. > > This patch fixes the particular case by redoing the preferred zoneref search > if we switch back to the original nodemask. The condition is also slightly > changed so that when the last non-root cpuset is removed, we don't miss it. > > Note that this is not a full fix, and more patches will follow. > > Reported-by: Ganapatrao Kulkarni <gpkulkarni@xxxxxxxxx> > Fixes: 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator") > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> -- Mel Gorman SUSE Labs -- 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>