From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756056AbaENQis (ORCPT ); Wed, 14 May 2014 12:38:48 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:25369 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754280AbaENQir (ORCPT ); Wed, 14 May 2014 12:38:47 -0400 Message-ID: <53739BF2.1030100@oracle.com> Date: Wed, 14 May 2014 12:38:10 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Peter Zijlstra CC: Ingo Molnar , acme@ghostprotocols.net, LKML , Thomas Gleixner , Dave Jones Subject: Re: perf: use after free in perf_remove_from_context References: <5370EBE9.6@oracle.com> <20140514162943.GR30445@twins.programming.kicks-ass.net> <53739A9A.5010703@oracle.com> <20140514163535.GS30445@twins.programming.kicks-ass.net> In-Reply-To: <20140514163535.GS30445@twins.programming.kicks-ass.net> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 05/14/2014 12:35 PM, Peter Zijlstra wrote: > On Wed, May 14, 2014 at 12:32:26PM -0400, Sasha Levin wrote: >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 >> >> On 05/14/2014 12:29 PM, Peter Zijlstra wrote: >>> On Mon, May 12, 2014 at 11:42:33AM -0400, Sasha Levin wrote: >>>> Hi all, >>>> >>>> While fuzzing with trinity inside a KVM tools guest running the latest -next kernel I've stumbled on the following spew. Maybe related to the very recent change in freeing on task exit? >>>> >>>> [ 2509.827261] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 2509.830379] Dumping ftrace buffer: [ 2509.830379] (ftrace buffer empty) [ 2509.830379] Modules linked in: [ 2509.830379] CPU: 47 PID: 43306 Comm: trinity-c126 Tainted: G W 3.15.0-rc5-next-20140512-sasha-00019-ga20bc00-dirty #456 >>> >>> Any particular trinity setup? And would you happen to have the seed of that run? >> >> Nothing special about trinity options. 400 threads and blacklisting some of the destructive syscalls (umount, reboot, etc). >> >> I don't have the seed, but that problem did reproduce again tonight so I can test out debug code if you have something in mind. > > Nah, I drew a pretty big blank, which is why I wanted to see if I could reproduce. If you could share your trinity cmdline I'd be much obliged. While I did manage to clone (the repo moved since last time) and build it, I'm not really that handy with it and want to avoid destroying my machine if possible ;-) > ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet --dangerous -C 400 -l off Note that I run it as root in a disposable VM. Running that as root on your machine will likely kill it. Thanks, Sasha -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTc5vxAAoJEN6mb/eXdyzckwUQAJDWAzRcDfjQUwJsXHeMG9hb QMBdTJqijHnbzOiPX/xHnxxALGVsUl8+ZekLxlCmPF6l5o9/AGngavrb2pBG9uQe qo8B9vB6rxmzfImwWFpaC8LTizGfrwwU60Br1ByQiGCMnKVWGsenhOJgItawH+cu nm2QsyKwGAU9OvwFXfEuD8jky9yvTMOZVftaZE2oLW85dyjzAu24+PD5ogMpCraJ 6sM4fgU8w3WdBqQEvxj4u3ET0DmUrASV4wLTJ+/K5Mty6IZPYChEpDrdMmBl7kOM jk8QnJvP9jnflbfYwKvEZ3n0j9WkiVitU+3rITy17RJ7lHglwSR/5IwU/nhYVZUA ymrWldsYRPx55r0XVvTGyfx/9SkpHyl/mOgtjbFTYq8c4oxGTpC0LQZIVmtVPP0l j8ZBIV0pZUYK4KPvoe8eozZuJ6q+YdETrekLoFpLnIweo8bCfEU2vhD8Vzxp1aDm E907cHq1pqe6eRC9Las/gAXC/efy9YhsmtQgdwVpwwDpyaIujznbCF9nTfYgOkgx VoWED91EXqls8OQONlsNkc+Xy1fMmBZpwWiQeaOI5vLXhiwl0vxUl0ZHcb9VvJ4q 0k8EET64XIoJp+vZVO8d97AYG7B6Ub0W7DAs7Sn2ib5h44pByOXpR4scMZVXR7Hv zcievjH07ftXEUXOn6Xr =sJLe -----END PGP SIGNATURE-----