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From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov@virtuozzo.com>,
	cgroups@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com
Subject: Re: [PATCH] memcg: add RCU locking around css_for_each_descendant_pre() in memcg_offline_kmem()
Date: Fri, 27 May 2016 17:31:24 +0200	[thread overview]
Message-ID: <20160527153124.GT27686@dhcp22.suse.cz> (raw)
In-Reply-To: <20160526140202.077d611dbe0926ce290b4e53@linux-foundation.org>

On Thu 26-05-16 14:02:02, Andrew Morton wrote:
> On Thu, 26 May 2016 16:30:18 -0400 Tejun Heo <tj@kernel.org> wrote:
> 
> > memcg_offline_kmem() may be called from memcg_free_kmem() after a css
> > init failure.  memcg_free_kmem() is a ->css_free callback which is
> > called without cgroup_mutex and memcg_offline_kmem() ends up using
> > css_for_each_descendant_pre() without any locking.  Fix it by adding
> > rcu read locking around it.
> > 
> >  mkdir: cannot create directory ___65530___: No space left on device
> >  [  527.241361] ===============================
> >  [  527.241845] [ INFO: suspicious RCU usage. ]
> >  [  527.242367] 4.6.0-work+ #321 Not tainted
> >  [  527.242730] -------------------------------
> >  [  527.243220] kernel/cgroup.c:4008 cgroup_mutex or RCU read lock required!
> 
> cc:stable?

Also which kernel versions would be affected? I have tried to look and
got lost in the indirection of the css_free path.

Thanks!

-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2016-05-27 15:31 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-26 20:30 Tejun Heo
2016-05-26 21:02 ` Andrew Morton
2016-05-27 15:31   ` Michal Hocko [this message]
2016-05-27 15:51     ` Tejun Heo
2016-05-31  9:33       ` Michal Hocko
2016-05-27  8:17 ` Vladimir Davydov
2016-05-27 17:19 ` Johannes Weiner

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