Date: Thu, 1 Dec 2011 13:55:55 +0100
From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Michal Hocko <mhocko@suse.cz>, Eliad Peller <eliad@wizery.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: <20111201125554.GC5706@redhat.com> (sfid-20111201_135602_797755_162FFC6A)
References: <20111129100727.GD2675@tiehlicka.suse.cz>
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 <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, Dec 01, 2011 at 01:44:40PM +0100, 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.
Actually this require quite big changes in iwlegacy at least, perhaps
also in iwlwifi. I prefer to revert commit as temporary fix,  and add
memset(0) to drivers .add_sta callback, in drivers which need it. After
changing iwlegcy/iwlwifi we could move memset(0) back to ieee80211_reconfig().

Eliad, thoughts? 

> Should I just revert it?
Yes, or remove proper line :-)

Stanislaw