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Message-ID: <a8d1cbfa03c9bf5f1eeaee7539dacc581df2dd97.camel@surriel.com>
Subject: Re: [PATCH] mm,slab,memcg: call memcg kmem put cache with same
 condition as get
From: Rik van Riel <riel@surriel.com>
Date: Wed, 09 Jan 2019 09:09:49 -0500
In-Reply-To: <CALvZod6=-kdUk23i7eOr5AO-_2Fk_BmJiL3QjSJ4S4QOs0xKkw@mail.gmail.com>
References: <20190109040107.4110-1-riel@surriel.com>
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To: Shakeel Butt <shakeelb@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kernel-team@fb.com, Linux MM <linux-mm@kvack.org>, stable@vger.kernel.org, Alexey Dobriyan <adobriyan@gmail.com>, Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>


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On Tue, 2019-01-08 at 21:36 -0800, Shakeel Butt wrote:
> On Tue, Jan 8, 2019 at 8:01 PM Rik van Riel <riel@surriel.com> wrote:
> >=20
> > There is an imbalance between when slab_pre_alloc_hook calls
> > memcg_kmem_get_cache and when slab_post_alloc_hook calls
> > memcg_kmem_put_cache.
> >=20
>=20
> Can you explain how there is an imbalance? If the returned kmem cache
> from memcg_kmem_get_cache() is the memcg kmem cache then the refcnt
> of
> memcg is elevated and the memcg_kmem_put_cache() will correctly
> decrement the refcnt of the memcg.

Indeed, you are right. Never mind this patch.

Back to square one on that bug.

--=20
All Rights Reversed.

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