[PATCH 96/97] mm: page_alloc: abort fair zone allocation policy when remotes nodes are encountered

From: Mel Gorman
Date: Thu Aug 28 2014 - 14:42:48 EST

commit f7b5d647946aae1647bf5cd26c16b3a793c1ac49 upstream.

The purpose of numa_zonelist_order=zone is to preserve lower zones for
use with 32-bit devices. If locality is preferred then the
numa_zonelist_order=node policy should be used.

Unfortunately, the fair zone allocation policy overrides this by
skipping zones on remote nodes until the lower one is found. While this
makes sense from a page aging and performance perspective, it breaks the
expected zonelist policy. This patch restores the expected behaviour
for zone-list ordering.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ee24ebb..16e6740 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1955,7 +1955,7 @@ zonelist_scan:
if (alloc_flags & ALLOC_FAIR) {
if (!zone_local(preferred_zone, zone))
- continue;
+ break;
if (zone_page_state(zone, NR_ALLOC_BATCH) <= 0)

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