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

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Date:	Wed, 27 Apr 2016 13:24:43 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Vlastimil Babka <vbabka@...e.cz>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 2/4] mm, page_alloc: inline the fast path of the zonelist iterator -fix

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@...e.cz>
Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
---
 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