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From: Johannes Weiner <hannes@cmpxchg.org>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Hillf Danton <hillf.zj@alibaba-inc.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@surriel.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: vmscan: fix memcg-aware shrinkers not called on global reclaim
Date: Mon, 1 Aug 2016 11:15:08 -0400	[thread overview]
Message-ID: <20160801151508.GB7603@cmpxchg.org> (raw)
In-Reply-To: <1470056590-7177-1-git-send-email-vdavydov@virtuozzo.com>

On Mon, Aug 01, 2016 at 04:03:10PM +0300, Vladimir Davydov wrote:
> 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@virtuozzo.com>

Ouch, I missed that in the review. The change looked so obviously
correct, but the shrink_slab() interface is a little deceiving. It
would be great if shrink_slab() could handle root_mem_cgroup/NULL and
then we'd always call it from inside the loop. But AFAICS we need the
global call to get the cumulative scanned/lru_pages ratio from all of
the memcgs reclaimed... grr. Oh well.

This fix looks correct to me, anyway.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Hillf Danton <hillf.zj@alibaba-inc.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@surriel.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: vmscan: fix memcg-aware shrinkers not called on global reclaim
Date: Mon, 1 Aug 2016 11:15:08 -0400	[thread overview]
Message-ID: <20160801151508.GB7603@cmpxchg.org> (raw)
In-Reply-To: <1470056590-7177-1-git-send-email-vdavydov@virtuozzo.com>

On Mon, Aug 01, 2016 at 04:03:10PM +0300, Vladimir Davydov wrote:
> 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@virtuozzo.com>

Ouch, I missed that in the review. The change looked so obviously
correct, but the shrink_slab() interface is a little deceiving. It
would be great if shrink_slab() could handle root_mem_cgroup/NULL and
then we'd always call it from inside the loop. But AFAICS we need the
global call to get the cumulative scanned/lru_pages ratio from all of
the memcgs reclaimed... grr. Oh well.

This fix looks correct to me, anyway.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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  parent reply	other threads:[~2016-08-01 15:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-01 13:03 [PATCH] mm: vmscan: fix memcg-aware shrinkers not called on global reclaim Vladimir Davydov
2016-08-01 13:03 ` Vladimir Davydov
2016-08-01 13:18 ` Michal Hocko
2016-08-01 13:18   ` Michal Hocko
2016-08-01 13:21   ` Vladimir Davydov
2016-08-01 13:21     ` Vladimir Davydov
2016-08-01 13:27     ` Michal Hocko
2016-08-01 13:27       ` Michal Hocko
2016-08-01 15:15 ` Johannes Weiner [this message]
2016-08-01 15:15   ` Johannes Weiner
2016-08-02  0:11 ` Minchan Kim
2016-08-02  0:11   ` Minchan Kim
2016-08-02  9:32 ` Mel Gorman
2016-08-02  9:32   ` Mel Gorman

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