From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754819AbbJULj1 (ORCPT ); Wed, 21 Oct 2015 07:39:27 -0400 Received: from smtprelay0132.hostedemail.com ([216.40.44.132]:41778 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754654AbbJULjZ (ORCPT ); Wed, 21 Oct 2015 07:39:25 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1539:1593:1594:1711:1730:1747:1777:1792:2194:2199:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3871:3872:3874:4250:5007:6261:7875:10004:10400:10848:10967:11232:11658:11914:12517:12519:12740:13069:13311:13357:21080:21088,0,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 X-HE-Tag: scene26_520ee41efb462 X-Filterd-Recvd-Size: 1705 Date: Wed, 21 Oct 2015 07:39:22 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: "Paul E. McKenney" , LKML Subject: Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching Message-ID: <20151021073922.77e429f6@gandalf.local.home> In-Reply-To: <20151021080142.GZ2881@worktop.programming.kicks-ass.net> References: <20151020121031.2f9d72c1@gandalf.local.home> <20151020202528.GF5105@linux.vnet.ibm.com> <20151020173228.3e4edda5@gandalf.local.home> <20151021080142.GZ2881@worktop.programming.kicks-ass.net> X-Mailer: Claws Mail 3.12.0 (GTK+ 2.24.28; 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 Wed, 21 Oct 2015 10:01:42 +0200 Peter Zijlstra wrote: > > I should probably add a "if (in_nmi()) return" somewhere. > > But if there's an arch that doesn't use a separate NMI stack, the NMI > might cause the largest stack, which would then remain invisible from > the stack-tracer. > > Should we not instead fix the NMI-safety of this tracer? We could, but that should be a separate project, as that would require doing everything lockless, which would require a redesign. Is that worth it? For now, the safe thing to do is the if (in_nmi()), but certainly, if someone gets time to make it NMI safe, we can do that too. -- Steve