From: Li Zefan <lizf@cn.fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>,
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [BUGFIX][PATCH] memcg rcu lock fix v3
Date: Fri, 23 Apr 2010 14:10:32 +0800 [thread overview]
Message-ID: <4BD139D8.80309@cn.fujitsu.com> (raw)
In-Reply-To: <20100423130349.f320d0be.kamezawa.hiroyu@jp.fujitsu.com>
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
> css_id() should be called under rcu_read_lock().
> Following is a report from Li Zefan.
> ==
> ===================================================
> [ INFO: suspicious rcu_dereference_check() usage. ]
> ---------------------------------------------------
> kernel/cgroup.c:4438 invoked rcu_dereference_check() without protection!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 1, debug_locks = 1
> 1 lock held by kswapd0/31:
> #0: (swap_lock){+.+.-.}, at: [<c05058bb>] swap_info_get+0x4b/0xd0
>
> stack backtrace:
...
>
> And css_is_ancestor() should be called under rcu_read_lock().
>
>
> Reported-by: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
With this patch applied, I did some more test, and no warning was triggered.
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
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next prev parent reply other threads:[~2010-04-23 6:08 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-23 3:00 [BUG] an RCU warning in memcg Li Zefan
2010-04-23 3:14 ` [BUGFIX][PATCH] memcg rcu lock fix in swap code (Was " KAMEZAWA Hiroyuki
2010-04-23 3:32 ` Balbir Singh
2010-04-23 3:49 ` Li Zefan
2010-04-23 3:55 ` Li Zefan
2010-04-23 3:50 ` KAMEZAWA Hiroyuki
2010-04-23 4:02 ` Li Zefan
2010-04-23 3:58 ` [BUGFIX][PATCH] memcg rcu lock fix v2 KAMEZAWA Hiroyuki
2010-04-23 4:03 ` [BUGFIX][PATCH] memcg rcu lock fix v3 KAMEZAWA Hiroyuki
2010-04-23 4:41 ` Daisuke Nishimura
2010-04-23 6:10 ` Li Zefan [this message]
2010-04-23 6:05 ` KAMEZAWA Hiroyuki
2010-04-23 7:00 ` Balbir Singh
2010-04-23 6:57 ` KAMEZAWA Hiroyuki
2010-04-23 19:34 ` Paul E. McKenney
2010-04-24 2:08 ` KAMEZAWA Hiroyuki
2010-04-24 4:27 ` Paul E. McKenney
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