Date: Thu, 1 Dec 2011 15:05:00 +0100
From: Michal Hocko <mhocko@suse.cz>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"John W. Linville" <linville@tuxdriver.com>,
	linux-wireless@vger.kernel.org, Yong Zhang <yong.zhang0@gmail.com>
Subject: Re: [3.2-rc3] 100% CPU usage while in del_timer_sync from
 iwl3945_rs_free_sta
Message-ID: <20111201140500.GA4269@tiehlicka.suse.cz> (sfid-20111201_150510_299146_A793FF6B)
References: <20111129100727.GD2675@tiehlicka.suse.cz>
 <20111129113906.GA7299@redhat.com>
 <20111130101028.GA2906@tiehlicka.suse.cz>
 <20111130142316.GA2466@redhat.com>
 <20111130140316.GA4153@tiehlicka.suse.cz>
 <20111130153929.GA2144@redhat.com>
 <20111201085845.GA4602@tiehlicka.suse.cz>
 <20111201105538.GA4504@tiehlicka.suse.cz>
 <20111201115911.GA5706@redhat.com>
 <20111201124440.GB25614@tiehlicka.suse.cz>
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Sender: linux-wireless-owner@vger.kernel.org

On Thu 01-12-11 13:44:40, Michal Hocko wrote:
> On Thu 01-12-11 12:59:12, Stanislaw Gruszka wrote:
> > On Thu, Dec 01, 2011 at 11:55:38AM +0100, Michal Hocko wrote:
> > > [  349.316070] iwl3945_rs_free_sta rs_sta f4be1ac0
> > > [  349.316076] ------------[ cut here ]------------
> > > [  349.316097] WARNING: at drivers/net/wireless/iwlegacy/iwl-3945-rs.c:438 iwl3945_rs_free_sta+0x33/0x42 [iwl3945]()
> > 
> > Johannes pointed on irc that this problem is most likely caused by:
> > 
> > commit f785d83a19bca326f79d127a413e35769afc0105
> > Author: Eliad Peller <eliad@wizery.com>
> > Date:   Mon Aug 8 16:50:22 2011 +0300
> > 
> >     mac80211: clear sta.drv_priv on reconfiguration
> > 
> > Michal, could you confirm that? If that is the root of the problem, we
> > need patch for iwlegacy (and iwlwifi) that allocate separate memory for
> > rc structures.
> 
> Should I just revert it?

Reverted and guess what ;)
Yeah, it works. So feel free to add
Reported-adn-Tested-by: Michal Hocko <mhocko@suse.cz>
to the revert.

Anyway, I have really no idea about the 80211 stack but the patch
doesn't seem to be correct from the layering POV. Why should generic
layer clear something that is driver private data (or at least the
naming suggests that it is driver specific data)?

Thanks a lot for your help.
-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic