On 04/27/2016 04:57 PM, Mel Gorman wrote: > as the patch "mm, page_alloc: inline the fast path of the zonelist iterator" > is fine. The nodemask pointer is the same between cpuset retries. If the > zonelist changes due to ALLOC_NO_WATERMARKS *and* it races with a cpuset > change then there is a second harmless pass through the page allocator. True. But I just realized (while working on direct compaction priorities) that there's another subtle issue with the ALLOC_NO_WATERMARKS part. According to the comment it should be ignoring mempolicies, but it still honours ac.nodemask, and your patch is replacing NULL ac.nodemask with the mempolicy one. I think it's possibly easily fixed outside the fast path like this. If you agree, consider it has my s-o-b: diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3f052bbca41d..7ccaa6e023f3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3834,6 +3834,11 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, alloc_mask = memalloc_noio_flags(gfp_mask); ac.spread_dirty_pages = false; + /* + * Restore the original nodemask, which might have been replaced with + * &cpuset_current_mems_allowed to optimize the fast-path attempt. + */ + ac.nodemask = nodemask; page = __alloc_pages_slowpath(alloc_mask, order, &ac); no_zone: -- 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>