From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933633AbcBYTXn (ORCPT ); Thu, 25 Feb 2016 14:23:43 -0500 Received: from smtprelay0173.hostedemail.com ([216.40.44.173]:55379 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933607AbcBYTXl (ORCPT ); Thu, 25 Feb 2016 14:23:41 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1540:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:4250:5007:6119:6261:7875:7903:10004:10400:10848:10967:11232:11658:11914:12043:12517:12519:12679:12740:13069:13161:13229:13255:13311:13357:14096:14097:14659:21080:21212:30054:30056:30060:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: shop11_1febaad94e302 X-Filterd-Recvd-Size: 2072 Date: Thu, 25 Feb 2016 14:23:38 -0500 From: Steven Rostedt To: Linus Torvalds Cc: Peter Hurley , Jiri Slaby , Greg KH , Linux Kernel Mailing List , Andrew Morton , stable , lwn@lwn.net Subject: Re: BUG: unable to handle kernel paging request from pty_write [was: Linux 4.4.2] Message-ID: <20160225142338.42e46f2c@gandalf.local.home> In-Reply-To: References: <20160217203730.GA14820@kroah.com> <56CED373.9060603@suse.cz> <56CF4A83.3040408@hurleysoftware.com> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.29; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 Feb 2016 11:09:35 -0800 Linus Torvalds wrote: > Jiri, were you messing around with tracing when this happened? Or > maybe shutting down CPU's? There was a RCU locking problem with CPU > shutdown, maybe this is one of the symptoms. The fix for that is > recent, and not in 4.4.2. > > Adding Steven Rostedt to the cc. Steven, does that look like a possible case? Possible: yes. Likely: no The recent fix would require shutting down a CPU at the same time as a tracepoint is enabled or disabled. Rather difficult to hit, but easier on a virtual machine. If Jiri was not enabling/disabling tracepoints or shutting down CPUs, then it would not be the bug. But as the comm of the bug is gdb and this running on a virtual machine, I think the bug may be elsewhere. Corrupt stack possibly? -- Steve