From 4741526b83c5d3a3d661d1896f9e7414c5730bcb Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
Date: Thu, 19 May 2016 17:14:44 -0700
Subject: mm, page_alloc: restore the original nodemask if the fast path
 allocation failed

The page allocator fast path uses either the requested nodemask or
cpuset_current_mems_allowed if cpusets are enabled.  If the allocation
context allows watermarks to be ignored then it can also ignore memory
policies.  However, on entering the allocator slowpath the nodemask may
still be cpuset_current_mems_allowed and the policies are enforced.
This patch resets the nodemask appropriately before entering the
slowpath.

Link: http://lkml.kernel.org/r/20160504143628.GU2858@techsingularity.net
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ecf6633..5c469c1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3636,6 +3636,12 @@ retry_cpuset:
 	alloc_mask = memalloc_noio_flags(gfp_mask);
 	ac.spread_dirty_pages = false;
 
+	/*
+	 * Restore the original nodemask if it was potentially replaced with
+	 * &cpuset_current_mems_allowed to optimize the fast-path attempt.
+	 */
+	if (cpusets_enabled())
+		ac.nodemask = nodemask;
 	page = __alloc_pages_slowpath(alloc_mask, order, &ac);
 
 no_zone:
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