mm: page_alloc: abort fair zone allocation policy when remotes nodes are encountered

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@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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 daa0160..6e5e8f7 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1965,7 +1965,7 @@ zonelist_scan:
                 */
                if (alloc_flags & ALLOC_FAIR) {
                        if (!zone_local(preferred_zone, zone))
-                               continue;
+                               break;
                        if (zone_page_state(zone, NR_ALLOC_BATCH) <= 0)
                                continue;
                }