linux-kernel - [PATCH] mm: vmscan: fix memcg-aware shrinkers not called on global reclaim

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Date:	Mon, 1 Aug 2016 16:03:10 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Mel Gorman <mgorman@...hsingularity.net>,
	Hillf Danton <hillf.zj@...baba-inc.com>,
	Johannes Weiner <hannes@...xchg.org>,
	"Vlastimil Babka" <vbabka@...e.cz>,
	Michal Hocko <mhocko@...nel.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Minchan Kim <minchan@...nel.org>,
	Rik van Riel <riel@...riel.com>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] mm: vmscan: fix memcg-aware shrinkers not called on global reclaim

We must call shrink_slab() for each memory cgroup on both global and
memcg reclaim in shrink_node_memcg(). Commit d71df22b55099 accidentally
changed that so that now shrink_slab() is only called with memcg != NULL
on memcg reclaim. As a result, memcg-aware shrinkers (including
dentry/inode) are never invoked on global reclaim. Fix that.

Fixes: d71df22b55099 ("mm, vmscan: begin reclaiming pages on a per-node basis")
Signed-off-by: Vladimir Davydov <vdavydov@...tuozzo.com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 650d26832569..374d95d04178 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2561,7 +2561,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 			shrink_node_memcg(pgdat, memcg, sc, &lru_pages);
 			node_lru_pages += lru_pages;
 
-			if (!global_reclaim(sc))
+			if (memcg)
 				shrink_slab(sc->gfp_mask, pgdat->node_id,
 					    memcg, sc->nr_scanned - scanned,
 					    lru_pages);
-- 
2.1.4