On Tue, 11 Apr 2017, Vlastimil Babka wrote: > The root of the problem is that the cpuset's mems_allowed and mempolicy's > nodemask can temporarily have no intersection, thus get_page_from_freelist() > cannot find any usable zone. The current semantic for empty intersection is to > ignore mempolicy's nodemask and honour cpuset restrictions. This is checked in > node_zonelist(), but the racy update can happen after we already passed the The fallback was only intended for a cpuset on which boundaries are not enforced in critical conditions (softwall). A hardwall cpuset (CS_MEM_HARDWALL) should fail the allocation. > This patch fixes the issue by having __alloc_pages_slowpath() check for empty > intersection of cpuset and ac->nodemask before OOM or allocation failure. If > it's indeed empty, the nodemask is ignored and allocation retried, which mimics > node_zonelist(). This works fine, because almost all callers of Well that would need to be subject to the hardwall flag. Allocation needs to fail for a hardwall cpuset. -- 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>
