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From: Andrew Morton <akpm@linux-foundation.org>
To: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.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: Thu, 26 May 2016 14:02:02 -0700	[thread overview]
Message-ID: <20160526140202.077d611dbe0926ce290b4e53@linux-foundation.org> (raw)
In-Reply-To: <20160526203018.GG23194@mtj.duckdns.org>

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?

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WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Vladimir Davydov
	<vdavydov-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	kernel-team-b10kYP2dOMg@public.gmane.org
Subject: Re: [PATCH] memcg: add RCU locking around css_for_each_descendant_pre() in memcg_offline_kmem()
Date: Thu, 26 May 2016 14:02:02 -0700	[thread overview]
Message-ID: <20160526140202.077d611dbe0926ce290b4e53@linux-foundation.org> (raw)
In-Reply-To: <20160526203018.GG23194-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>

On Thu, 26 May 2016 16:30:18 -0400 Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.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?

  reply	other threads:[~2016-05-26 21:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-26 20:30 [PATCH] memcg: add RCU locking around css_for_each_descendant_pre() in memcg_offline_kmem() Tejun Heo
2016-05-26 20:30 ` Tejun Heo
2016-05-26 21:02 ` Andrew Morton [this message]
2016-05-26 21:02   ` Andrew Morton
2016-05-27 15:31   ` Michal Hocko
2016-05-27 15:31     ` Michal Hocko
2016-05-27 15:51     ` Tejun Heo
2016-05-27 15:51       ` Tejun Heo
2016-05-31  9:33       ` Michal Hocko
2016-05-31  9:33         ` Michal Hocko
2016-05-27  8:17 ` Vladimir Davydov
2016-05-27  8:17   ` Vladimir Davydov
2016-05-27 17:19 ` Johannes Weiner
2016-05-27 17:19   ` Johannes Weiner

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