From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756825AbaEIQam (ORCPT ); Fri, 9 May 2014 12:30:42 -0400 Received: from mail-lb0-f182.google.com ([209.85.217.182]:61209 "EHLO mail-lb0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750744AbaEIQal (ORCPT ); Fri, 9 May 2014 12:30:41 -0400 Date: Fri, 9 May 2014 20:30:38 +0400 From: Cyrill Gorcunov To: Vince Weaver Cc: Don Zickus , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar Subject: Re: perf_fuzzer crash on pentium 4 Message-ID: <20140509163038.GH320@moon.sw.swsoft.com> References: <20140506202307.GA1458@moon> <20140508020050.GX39568@redhat.com> <20140508073756.GM8607@moon> <20140508074930.GN8607@moon> <20140508080234.GO8607@moon> 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) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 09, 2014 at 12:19:49PM -0400, Vince Weaver wrote: > On Thu, 8 May 2014, Cyrill Gorcunov wrote: > > > > Updated. > > --- > > arch/x86/kernel/cpu/perf_event_p4.c | 67 ++++++++++++++++-------------------- > > 1 file changed, 30 insertions(+), 37 deletions(-) > > I tried this patch, and even though it seemed to fix one of the NMI storms > I was experiencing I've managed to trigger again using a different random > seed. Thanks a lot for help in testing, Vince! I think the patch would be still needed so I will prepare normal change log explaining what has been fixed in the patch. > I've been trying to track down a trace of what is triggering things, but > this is very difficult as the full log isn't making it to the serial > console, even when I fsync() stdout. I see. Need to think. Maybe something comes to mind. Debuggin it is really a hard job :/ I've been promised to get access to real p4 machine next week, maybe I find something. > Maybe related, but the following messages tend to happen a lot while > fuzzing, and always happen before the fuzzing that eventually locks up: > > The warnings are for > if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED))) > and > WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED); Thanks for info, Vince! Look, every time you start perf_fuzzer (note, I didn't read its code yet, that's why I'm asking) -- does it log which events are passed to kernel from userspace? Btw, do you run kernel with nmi-watchdog turned on?