From: Christopher Lameter <cl@linux.com>
To: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>,
Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Thelen <gthelen@google.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Linux MM <linux-mm@kvack.org>,
cgroups@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mm: fix race between kmem_cache destroy, create and deactivate
Date: Tue, 29 May 2018 13:58:11 +0000 [thread overview]
Message-ID: <01000163ac3122e8-e705287a-17f4-4ff6-8eae-1ad310676096-000000@email.amazonses.com> (raw)
In-Reply-To: <20180526185837.k5ztrillokpi65qj@esperanza>
On Sat, 26 May 2018, Vladimir Davydov wrote:
> > The reference counting is only implemented for root kmem_caches for
> > simplicity. The reference of a root kmem_cache is elevated on sharing or
> > while its memcg kmem_cache creation or deactivation request is in the
> > fly and thus it is made sure that the root kmem_cache is not destroyed
> > in the middle. As the reference of kmem_cache is elevated on sharing,
> > the 'shared_count' does not need any locking protection as at worst it
> > can be out-dated for a small window which is tolerable.
>
> I wonder if we could fix this problem without introducing reference
> counting for kmem caches (which seems a bit of an overkill to me TBO),
> e.g. by flushing memcg_kmem_cache_wq before root cache destruction?
Would prefer that too but the whole memcg handling is something of a
mystery to me.
prev parent reply other threads:[~2018-05-29 13:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-22 20:13 Shakeel Butt
2018-05-26 18:58 ` Vladimir Davydov
2018-05-26 22:43 ` Shakeel Butt
2018-05-29 13:58 ` Christopher Lameter [this message]
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