Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755293AbaDGQy5 (ORCPT <rfc822;w@1wt.eu>);
	Mon, 7 Apr 2014 12:54:57 -0400
Received: from cantor2.suse.de ([195.135.220.15]:52875 "EHLO mx2.suse.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1753778AbaDGQyv (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 7 Apr 2014 12:54:51 -0400
Date: Mon, 7 Apr 2014 18:54:49 +0200
From: David Sterba <dsterba@suse.cz>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>, dsterba@suse.cz, clm@fb.com, jbacik@fb.com,
        linux-btrfs@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: btrfs: lock inversion between delayed_node->mutex and
 found->groups_sem
Message-ID: <20140407165449.GA29256@twin.jikos.cz>
Reply-To: dsterba@suse.cz
Mail-Followup-To: dsterba@suse.cz, Sasha Levin <sasha.levin@oracle.com>,
	Jeff Mahoney <jeffm@suse.com>, clm@fb.com, jbacik@fb.com,
	linux-btrfs@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
References: <53239AE0.8030306@oracle.com>
 <20140317130546.GE29256@twin.jikos.cz>
 <533307ED.8030700@suse.com>
 <533F20EB.2040500@oracle.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <533F20EB.2040500@oracle.com>
User-Agent: Mutt/1.5.22.1-rc1 (2013-10-16)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Apr 04, 2014 at 05:15:23PM -0400, Sasha Levin wrote:
> On 03/26/2014 01:01 PM, Jeff Mahoney wrote:
> > On 3/17/14, 9:05 AM, David Sterba wrote:
> >>> On Fri, Mar 14, 2014 at 08:12:16PM -0400, Sasha Levin wrote:
> >>>>> While fuzzing with trinity inside a KVM tools guest running the latest -next kernel I've stumbled on the following:
> >>>>> 
> >>>>> [  788.458756]        CPU0                    CPU1 [  788.459188] ----                    ---- [  788.459625] lock(&found->groups_sem); [  788.460041] local_irq_disable(); [  788.460041] lock(&delayed_node->mutex); [  788.460041] lock(&found->groups_sem); [  788.460041]   <Interrupt> [ 788.460041]     lock(&delayed_node->mutex); [  788.460041] [ 788.460041]  *** DEADLOCK *** [  788.460041] [  788.460041] 2 locks held by kswapd3/4199:
> >>> 
> >>> I've once (3.14-rc5) seen the same warning also caused by xfstests/generic/224
> > I think this is from my sysfs patches. We call kobject_add while holding the group_sem. kobject_add ultimately allocates with GFP_KERNEL, so it can enter reclaim. This particular case isn't dangerous, but it could hit while hot-adding a device. The fix should be pretty simple.
> 
> Is that fix available anywhere? I'm still seeing the issue in -next.

It is: https://patchwork.kernel.org/patch/3894781/ , will probably hit -rc2
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/