From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752518AbcAVH6Y (ORCPT ); Fri, 22 Jan 2016 02:58:24 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:47193 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978AbcAVH6R (ORCPT ); Fri, 22 Jan 2016 02:58:17 -0500 Date: Fri, 22 Jan 2016 08:58:12 +0100 From: Peter Zijlstra To: kernel test robot Cc: Andi Kleen , LKP , linux-kernel@vger.kernel.org, Ingo Molnar , wfg@linux.intel.com Subject: Re: [perf/x86] 75925e1ad7: BUG: unable to handle kernel paging request at 000045b8 Message-ID: <20160122075812.GM6357@twins.programming.kicks-ass.net> References: <56a1b114.H5JOWAoJgA2/uN2W%fengguang.wu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56a1b114.H5JOWAoJgA2/uN2W%fengguang.wu@intel.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 22, 2016 at 12:33:24PM +0800, kernel test robot wrote: > Greetings, > > 0day kernel testing robot got the below dmesg and the first bad commit is > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > commit 75925e1ad7f5a4e867bd14ff8e7f114ea1596434 > Author: Andi Kleen > AuthorDate: Thu Oct 22 15:07:21 2015 -0700 > Commit: Ingo Molnar > CommitDate: Mon Nov 23 09:58:25 2015 +0100 > > perf/x86: Optimize stack walk user accesses > > Change the perf user stack walking to use the new > __copy_from_user_nmi(), and split each access into word sized transfer > sizes. This allows to inline the complete access and optimize it all > into a single load. Andi, please have a look at this. Also note that x86_64 __copy_from_user_nocheck() actually supports .size=16.