Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753743AbdHXUAY (ORCPT <rfc822;w@1wt.eu>);
        Thu, 24 Aug 2017 16:00:24 -0400
Received: from paleale.coelho.fi ([176.9.41.70]:45566 "EHLO
        farmhouse.coelho.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org
        with ESMTP id S1751168AbdHXUAW (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 24 Aug 2017 16:00:22 -0400
Message-ID: <1503604818.15969.433.camel@coelho.fi>
From: Luca Coelho <luca@coelho.fi>
To: Jiri Kosina <jikos@kernel.org>
Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
        linuxwifi@intel.com, rui.zhang@intel.com, edubezval@gmail.com,
        linux-pm@vger.kernel.org, david.weinehall@intel.com,
        johannes.berg@intel.com, kvalo@codeaurora.org, sara.sharon@intel.com,
        emmanuel.grumbach@intel.com
Date: Thu, 24 Aug 2017 23:00:18 +0300
In-Reply-To: <alpine.LSU.2.20.1708242153000.3581@cbobk.fhfr.pm>
References: <alpine.LSU.2.20.1708171537380.3581@cbobk.fhfr.pm>
          <20170822073729.4856-1-luca@coelho.fi>
         <1503554432.15969.415.camel@coelho.fi>
         <alpine.LSU.2.20.1708242153000.3581@cbobk.fhfr.pm>
Content-Type: text/plain; charset="UTF-8"
X-Mailer: Evolution 3.22.6-1 
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
X-SA-Exim-Connect-IP: 91.156.4.241
X-SA-Exim-Mail-From: luca@coelho.fi
Subject: Re: [PATCH v2] iwlwifi: pcie: move rx workqueue initialization to
 iwl_trans_pcie_alloc()
X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000)
X-SA-Exim-Scanned: Yes (on farmhouse.coelho.fi)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2048
Lines: 52

On Thu, 2017-08-24 at 21:56 +0200, Jiri Kosina wrote:
> On Thu, 24 Aug 2017, Luca Coelho wrote:
> 
> > > Work queues cannot be allocated when a mutex is held because the mutex
> > > may be in use and that would make it sleep.  Doing so generates the
> > > following splat with 4.13+:
> > > 
> > > [   19.513298] ======================================================
> > > [   19.513429] WARNING: possible circular locking dependency detected
> > > [   19.513557] 4.13.0-rc5+ #6 Not tainted
> > > [   19.513638] ------------------------------------------------------
> > > [   19.513767] cpuhp/0/12 is trying to acquire lock:
> > > [   19.513867]  (&tz->lock){+.+.+.}, at: [<ffffffff924afebb>] thermal_zone_get_temp+0x5b/0xb0
> > > [   19.514047]
> > > [   19.514047] but task is already holding lock:
> > > [   19.514166]  (cpuhp_state){+.+.+.}, at: [<ffffffff91cc4baa>] cpuhp_thread_fun+0x3a/0x210
> > > [   19.514338]
> > > [   19.514338] which lock already depends on the new lock.
> > > 
> > > This lock dependency already existed with previous kernel versions,
> > > but it was not detected until commit 49dfe2a67797 ("cpuhotplug: Link
> > > lock stacks for hotplug callbacks") was introduced.
> > > 
> > > Reported-by: David Weinehall <david.weinehall@intel.com>
> > > Reported-by: Jiri Kosina <jikos@kernel.org>
> > > Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
> > 
> > Jiri, did you have a chance to try this out? I'm about to ask Kalle to
> > merge this so it gets in in time for 4.13-rc7.
> 
> Sorry, I am almost completely offline for one more week (vacation), and 
> will not have access to the affected system before that.

Sounds good! Enjoy! ;)


>  But this indeed 
> looks like a correct fix to me, so feel free to add
> 
> 	Acked-by: Jiri Kosina <jkosina@suse.cz>
> 
> I'll be able to provide my Tested-by: eventually only in ~10 days.


Kalle already picked it up in wireless-drivers and this should make it's
way to 4.13-rc7 (we hope).

In any case, thanks for reporting and the help debugging it.

--
Cheers,
Luca.