From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757362AbbIXSOg (ORCPT ); Thu, 24 Sep 2015 14:14:36 -0400 Received: from mail-yk0-f173.google.com ([209.85.160.173]:33334 "EHLO mail-yk0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756544AbbIXSOf (ORCPT ); Thu, 24 Sep 2015 14:14:35 -0400 Date: Thu, 24 Sep 2015 14:14:30 -0400 From: Tejun Heo To: Bart Van Assche Cc: Ming Lei , Jens Axboe , Christoph Hellwig , "linux-kernel@vger.kernel.org" , Akinobu Mita Subject: Re: [PATCH 3/3] blk-mq: Fix the queue freezing mechanism Message-ID: <20150924181430.GD25415@mtj.duckdns.org> References: <560323AB.80900@sandisk.com> <56032432.6080006@sandisk.com> <20150924112251.2ec061fd@tom-T450> <56042844.60603@sandisk.com> <20150924165354.GB25415@mtj.duckdns.org> <5604346D.3080000@sandisk.com> <20150924174938.GC25415@mtj.duckdns.org> <56043C5D.3090307@sandisk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56043C5D.3090307@sandisk.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Sep 24, 2015 at 11:09:33AM -0700, Bart Van Assche wrote: > On 09/24/2015 10:49 AM, Tejun Heo wrote: > > Again, that doesn't happen. > > Hello Tejun, > > In case anyone would be interested, the backtraces for the lockup I had > observed are as follows: If this is happening and it's not caused by a hung in-flight request, it's either percpu_ref being buggy or the forementioned kill/reinit race screwing it up. percpu_ref_kill() is expected to disable tryget_live() in a finite amount of time regardless of concurrent tryget tries. Thanks. -- tejun