From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754734AbaIDQEg (ORCPT ); Thu, 4 Sep 2014 12:04:36 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:46317 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751184AbaIDQEe (ORCPT ); Thu, 4 Sep 2014 12:04:34 -0400 Date: Thu, 4 Sep 2014 09:04:28 -0700 From: "Paul E. McKenney" To: Fengguang Wu Cc: Christoph Lameter , Jet Chen , Su Tao , Yuanhan Liu , LKP , linux-kernel@vger.kernel.org Subject: Re: [percpu] BUG: unable to handle kernel NULL pointer dereference at (null) Message-ID: <20140904160428.GE5001@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20140902045830.GA11321@localhost> <20140902153403.GY5001@linux.vnet.ibm.com> <20140902162110.GB5001@linux.vnet.ibm.com> <20140902171657.GG5001@linux.vnet.ibm.com> <20140904123845.GA19925@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140904123845.GA19925@localhost> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14090416-0928-0000-0000-000004A26317 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 04, 2014 at 08:38:45PM +0800, Fengguang Wu wrote: > On Tue, Sep 02, 2014 at 10:16:57AM -0700, Paul E. McKenney wrote: > > On Tue, Sep 02, 2014 at 11:55:58AM -0500, Christoph Lameter wrote: > > > On Tue, 2 Sep 2014, Paul E. McKenney wrote: > > > > > > > Added by ac1bea85781e (sched,rcu: Make cond_resched() report RCU quiescent > > > > states), removed by 4a81e8328d379 (rcu: Reduce overhead of cond_resched() > > > > checks for RCU). So, as you say, no effect on contemporary kernels. > > > > > > Well not sure what to make out of all of this.... > > > > Yep, still confused as to how the patch adding the definition could have > > caused a failure. Fengguang, any thoughts? > > Yeah this is confusing.. I checked carefully and find that commit > 0e98023 and afea227 are built on 2 quite different servers -- which > might generate slightly different code. I'll fix this issue and make > the build server selection more consistent. Looking forward to seeing what shows up! Thanx, Paul From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============4700644829424224902==" MIME-Version: 1.0 From: Paul E. McKenney To: lkp@lists.01.org Subject: Re: [percpu] BUG: unable to handle kernel NULL pointer dereference at (null) Date: Thu, 04 Sep 2014 09:04:28 -0700 Message-ID: <20140904160428.GE5001@linux.vnet.ibm.com> In-Reply-To: <20140904123845.GA19925@localhost> List-Id: --===============4700644829424224902== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Thu, Sep 04, 2014 at 08:38:45PM +0800, Fengguang Wu wrote: > On Tue, Sep 02, 2014 at 10:16:57AM -0700, Paul E. McKenney wrote: > > On Tue, Sep 02, 2014 at 11:55:58AM -0500, Christoph Lameter wrote: > > > On Tue, 2 Sep 2014, Paul E. McKenney wrote: > > > = > > > > Added by ac1bea85781e (sched,rcu: Make cond_resched() report RCU qu= iescent > > > > states), removed by 4a81e8328d379 (rcu: Reduce overhead of cond_res= ched() > > > > checks for RCU). So, as you say, no effect on contemporary kernels. > > > = > > > Well not sure what to make out of all of this.... > > = > > Yep, still confused as to how the patch adding the definition could have > > caused a failure. Fengguang, any thoughts? > = > Yeah this is confusing.. I checked carefully and find that commit > 0e98023 and afea227 are built on 2 quite different servers -- which > might generate slightly different code. I'll fix this issue and make > the build server selection more consistent. Looking forward to seeing what shows up! Thanx, Paul --===============4700644829424224902==--