From mboxrd@z Thu Jan  1 00:00:00 1970
From: Miles Lane <miles.lane@gmail.com>
Subject: Re: 2.6.35-rc2-git1 - net/mac80211/sta_info.c:125 invoked
	rcu_dereference_check() without protection!
Date: Tue, 8 Jun 2010 07:29:48 -0400
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Cc: paulmck@linux.vnet.ibm.com, Vivek Goyal <vgoyal@redhat.com>,
	Eric Paris <eparis@redhat.com>,
	Lai Jiangshan <laijs@cn.fujitsu.com>,
	Ingo Molnar <mingo@elte.hu>,
	Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>, nauman@google.com,
	eric.dumazet@gmail.com, netdev@vger.kernel.org,
	Jens Axboe <jens.axboe@oracle.com>,
	Gui Jianfeng <guijianfeng@cn.fujitsu.com>,
	Li Zefan <lizf@cn.fujitsu.com>
To: Johannes Berg <johannes@sipsolutions.net>
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On Tue, Jun 8, 2010 at 3:26 AM, Johannes Berg <johannes@sipsolutions.ne=
t> wrote:
> On Mon, 2010-06-07 at 16:59 -0700, Paul E. McKenney wrote:
>> On Mon, Jun 07, 2010 at 02:25:44PM -0400, Miles Lane wrote:
>> > [ =A0 43.478812] [ INFO: suspicious rcu_dereference_check() usage.=
 ]
>> > [ =A0 43.478815] -------------------------------------------------=
--
>> > [ =A0 43.478820] net/mac80211/sta_info.c:125 invoked
>> > rcu_dereference_check() without protection!
>> > [ =A0 43.478824]
>> > [ =A0 43.478824] other info that might help us debug this:
>> > [ =A0 43.478826]
>> > [ =A0 43.478829]
>> > [ =A0 43.478830] rcu_scheduler_active =3D 1, debug_locks =3D 1
>> > [ =A0 43.478834] no locks held by NetworkManager/4017.
>>
>> Hmmm... =A0Johannes's update has been merged, and it requires that c=
allers
>> either be in an RCU read-side critical section or hold either the
>> ->sta_lock or the ->sta_mtx, and this thread does none of this.
>>
>> Johannes, any thoughts?
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Thanx, Paul
>>
>> > [ =A0 43.478837] stack backtrace:
>> > [ =A0 43.478842] Pid: 4017, comm: NetworkManager Not tainted 2.6.3=
5-rc2-git1 #8
>> > [ =A0 43.478846] Call Trace:
>> > [ =A0 43.478849] =A0<IRQ> =A0[<ffffffff81064e9c>] lockdep_rcu_dere=
ference+0x9d/0xa5
>> > [ =A0 43.478876] =A0[<ffffffffa010cb3c>] sta_info_get_bss+0x71/0x1=
2d [mac80211]
>> > [ =A0 43.478889] =A0[<ffffffffa010cc0d>] ieee80211_find_sta+0x15/0=
x2f [mac80211]
>> > [ =A0 43.478902] =A0[<ffffffffa019ae16>] iwlagn_tx_queue_reclaim+0=
xe7/0x1bb [iwlagn]
>
> iwlwifi wasn't using rcu protection here -- already sent a patch fixi=
ng
> it. My mistake, I =A0think. Thanks for checking :)
>
> johannes
>
>

Yes, your patch works for me.