Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932531Ab3COU4o (ORCPT ); Fri, 15 Mar 2013 16:56:44 -0400 Received: from mail-qa0-f43.google.com ([209.85.216.43]:59491 "EHLO mail-qa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932338Ab3COU4n (ORCPT ); Fri, 15 Mar 2013 16:56:43 -0400 MIME-Version: 1.0 In-Reply-To: References: <20130315132607.GA4565@quad> <20130315203123.GA28128@kroah.com> Date: Fri, 15 Mar 2013 21:56:42 +0100 Message-ID: Subject: Re: [PATCH] perf,x86: fix kernel crash with PEBS/BTS after suspend/resume From: Stephane Eranian To: Shuah Khan Cc: Greg KH , LKML , Linus Torvalds , Peter Zijlstra , "mingo@elte.hu" , Thomas Gleixner , Andrew Morton , Arnaldo Carvalho de Melo , Jiri Olsa , "ak@linux.intel.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1696 Lines: 42 On Fri, Mar 15, 2013 at 9:53 PM, Shuah Khan wrote: > On Fri, Mar 15, 2013 at 2:31 PM, Greg KH wrote: >> On Fri, Mar 15, 2013 at 02:26:07PM +0100, Stephane Eranian wrote: >>> >>> This patch fixes a kernel crash when using precise sampling (PEBS) >>> after a suspend/resume. Turns out the CPU notifier code is not invoked >>> on CPU0 (BP). Therefore, the DS_AREA (used by PEBS) is not restored properly >>> by the kernel and keeps it power-on/resume value of 0 causing any PEBS >>> measurement to crash when running on CPU0. >>> >>> The workaround is to add a hook in the actual resume code to restore >>> the DS Area MSR value. It is invoked for all CPUS. So for all but CPU0, >>> the DS_AREA will be restored twice but this is harmless. >>> >>> Reported-by: Linus Torvalds >>> Signed-off-by: Stephane Eranian >>> --- >> >> Is this needed for the 3.8 or older kernels as well? >> >> thanks, >> >> greg k-h > > Just about to ask the same question. Patch applies to 3.8, 3.4, 3.2 > and 3.5. But needs some massaging for 3.0. I have the kernels built, > haven't started testing yet. > Testing the patch is easy: # echo mem >/sys/power/state Then press the power button again, when you get control again, type: $ taskset -c 0 perf record -e cycles:pp my_test_program Note that this problem impacts only Intel processors after Core 2 (PEBS enabled). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/