[PATCH 2/4] mm, page_alloc: inline the fast path of the zonelist iterator -fix

From: Mel Gorman
Date: Wed Apr 27 2016 - 08:25:57 EST


Vlastimil Babka pointed out that the nodes allowed by a cpuset are not
reread if the nodemask changes during an allocation. This potentially
allows an unnecessary page allocation failure. Moving the retry_cpuset
label is insufficient but rereading the nodemask before retrying addresses
the problem.

This is a fix to the mmotm patch
mm-page_alloc-inline-the-fast-path-of-the-zonelist-iterator.patch .

Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d8383750bd43..45a36e98b9cb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3855,6 +3855,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
*/
if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) {
alloc_mask = gfp_mask;
+ ac.nodemask = &cpuset_current_mems_allowed;
goto retry_cpuset;
}

--
2.6.4