From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752371AbbE1Dcf (ORCPT <rfc822;w@1wt.eu>);
	Wed, 27 May 2015 23:32:35 -0400
Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:58672 "EHLO
	mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1751657AbbE1Dc1 (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 27 May 2015 23:32:27 -0400
Message-ID: <55668C45.3060700@fb.com>
Date: Wed, 27 May 2015 21:32:21 -0600
From: Jens Axboe <axboe@fb.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: NeilBrown <neilb@suse.de>, Keith Busch <keith.busch@intel.com>
CC: lkml <linux-kernel@vger.kernel.org>
Subject: Re: LOCKDEP warning due to ext_devt_lock
References: <20150528123233.3df8ff55@notabene.brown>
In-Reply-To: <20150528123233.3df8ff55@notabene.brown>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
X-Originating-IP: [192.168.54.13]
X-Proofpoint-Spam-Reason: safe
X-FB-Internal: Safe
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.14.151,1.0.33,0.0.0000
 definitions=2015-05-28_01:2015-05-28,2015-05-28,1970-01-01 signatures=0
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 05/27/2015 08:32 PM, NeilBrown wrote:
>
> Hi Keith,
>   I'm getting lockdep warning around use of ext_devt_lock.
>
> [11428.266019] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
>
>   As you say in
>      2da78092dda1 ("block: Fix dev_t minor allocation lifetime")
> ext_devt_lock can be taken from call_rcu's soft-irq.
> I think that means it should always use the _irq verion of spinlock.

Wouldn't spin_lock_bh() and friends suffice then?

-- 
Jens Axboe