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From: Jia He <hejianet@gmail.com>
Subject: [PATCH RFC 1/1] mm, page_alloc: fix incorrect zone_statistics data
Date: Mon, 12 Dec 2016 13:59:07 +0800
Message-Id: <1481522347-20393-2-git-send-email-hejianet@gmail.com>
In-Reply-To: <1481522347-20393-1-git-send-email-hejianet@gmail.com>
References: <1481522347-20393-1-git-send-email-hejianet@gmail.com>
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To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>, Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@techsingularity.net>, Michal Hocko <mhocko@suse.com>, Johannes Weiner <hannes@cmpxchg.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Taku Izumi <izumi.taku@jp.fujitsu.com>, Jia He <hejianet@gmail.com>

In commit b9f00e147f27 ("mm, page_alloc: reduce branches in
zone_statistics"), it reconstructed codes to reduce the branch miss rate.
Compared with the original logic, it assumed if !(flag & __GFP_OTHER_NODE)
 z->node would not be equal to preferred_zone->node. That seems to be
incorrect.

Fixes: commit b9f00e147f27 ("mm, page_alloc: reduce branches in
zone_statistics")

Signed-off-by: Jia He <hejianet@gmail.com>
---
 mm/page_alloc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6de9440..474757e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2568,6 +2568,9 @@ static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
 	if (z->node == local_nid) {
 		__inc_zone_state(z, NUMA_HIT);
 		__inc_zone_state(z, local_stat);
+	} else if (z->node == preferred_zone->node) {
+		__inc_zone_state(z, NUMA_HIT);
+		__inc_zone_state(z, NUMA_OTHER);
 	} else {
 		__inc_zone_state(z, NUMA_MISS);
 		__inc_zone_state(preferred_zone, NUMA_FOREIGN);
-- 
2.5.5

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