From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753698AbcIBSA4 (ORCPT ); Fri, 2 Sep 2016 14:00:56 -0400 Received: from mail-yw0-f193.google.com ([209.85.161.193]:33820 "EHLO mail-yw0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752014AbcIBSAy (ORCPT ); Fri, 2 Sep 2016 14:00:54 -0400 Date: Fri, 2 Sep 2016 14:00:51 -0400 From: Tejun Heo To: "Paul E. McKenney" Cc: Jens Axboe , kernel test robot , lkp@01.org, Jens Axboe , LKML Subject: Re: [writeback] 8bc4ad9498: INFO: suspicious RCU usage. ] Message-ID: <20160902180051.GB18760@htj.duckdns.org> References: <57c8012a.zlFYe5dba5wTaKD+%xiaolong.ye@intel.com> <25429877-af98-30b2-1980-6686a7b7b78f@fb.com> <20160902145622.GH12660@htj.duckdns.org> <20160902153601.GM16261@linux.vnet.ibm.com> <1a774b3f-9fdc-b620-9a35-d3e7ff18177a@fb.com> <20160902170056.GN16261@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160902170056.GN16261@linux.vnet.ibm.com> User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Paul. On Fri, Sep 02, 2016 at 10:00:56AM -0700, Paul E. McKenney wrote: > Note that lockdep believes that the rcu_read_lock() has also been > dropped, otherwise it would have listed it. There isn't any actual code between rcu_read_lock() and the following rcu deref. That's the first thing which happens. It looked mysterious to me so I was wondering whether you knew any brekages on rcu lockdep side. Unfortunately, that doesn't seem to be the case. > At this point, I have to suggest "git bisect"... I'll try to reproduce it and see wth is going on. Thanks! -- tejun