From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751560AbaEBE50 (ORCPT ); Fri, 2 May 2014 00:57:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:61578 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751463AbaEBE5Z (ORCPT ); Fri, 2 May 2014 00:57:25 -0400 Date: Fri, 2 May 2014 00:56:40 -0400 From: Dave Jones To: Thomas Gleixner Cc: Linux Kernel , peterz@infradead.org, davidlohr@hp.com, Linus Torvalds Subject: Re: [3.15-rc3] rtmutex-debug assertion. Message-ID: <20140502045640.GA27264@redhat.com> Mail-Followup-To: Dave Jones , Thomas Gleixner , Linux Kernel , peterz@infradead.org, davidlohr@hp.com, Linus Torvalds References: <20140429151655.GA14277@redhat.com> <20140430001432.GA32142@redhat.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) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 30, 2014 at 11:13:57AM +0200, Thomas Gleixner wrote: > On Tue, 29 Apr 2014, Dave Jones wrote: > > This is trickier to reproduce than it first seemed, as logging slows > > things down so much. But after a few hours, it logged that the > > call that triggered this was.. > > > > futex(uaddr=0x7f55ff8c4000, op=0x6, val=0x200000006223800b, utime=0x7f55ff8c4000, uaddr2=0x7f55ff8c4000, val3=-123) > > > > Those addresses come from an mmap we made on startup.. > > > > [init] mapping[3]: (zeropage PROT_READ | PROT_WRITE) 0x7f55ff8c4000 (1MB) > > > > op = FUTEX_LOCK_PI > > > > val seems to be garbage. > > > > I'll do another run, just to see if it's always the same set of values, > > but it's going to probably take an overnight run. > > Do you have the full fuzzing log, so I can see what happened > before/around that? This is tough, because it takes a long time to reproduce when the logging is enabled, and that ends up generating a lot of output. I've tried to cut it down some using just 4 threads, but that's still over 30M of logs. http://www.codemonkey.org.uk/junk/futex.tar.xz In this run, child0 was the pid that faulted. You can see the last line in trinity-child0.log has a similar fingerprint to the trace above. One thing that does look suspicious, is that all 4 threads were doing op=0x6 right before the kernel went south. Hope this helps. Dave