From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754638AbaIBRRG (ORCPT ); Tue, 2 Sep 2014 13:17:06 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:51077 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753703AbaIBRRD (ORCPT ); Tue, 2 Sep 2014 13:17:03 -0400 Date: Tue, 2 Sep 2014 10:16:57 -0700 From: "Paul E. McKenney" To: Christoph Lameter Cc: Fengguang Wu , 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: <20140902171657.GG5001@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14090217-6688-0000-0000-00000474F3C7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? Thanx, Paul