Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758757Ab2EYUvb (ORCPT ); Fri, 25 May 2012 16:51:31 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:11829 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756085Ab2EYUv3 (ORCPT ); Fri, 25 May 2012 16:51:29 -0400 X-Authority-Analysis: v=2.0 cv=D8PF24tj c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=Aua4qMZyJ18A:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=meVymXHHAAAA:8 a=ayC55rCoAAAA:8 a=e_sQblxPdNk3Y3Kc7iQA:9 a=PUjeQqilurYA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-ID: <1337979086.13348.269.camel@gandalf.stny.rr.com> Subject: Re: BUG - function tracing with breakpoints From: Steven Rostedt To: "H. Peter Anvin" Cc: Dave Jones , Linux Kernel , Frederic Weisbecker , Ingo Molnar , Andi Kleen Date: Fri, 25 May 2012 16:51:26 -0400 In-Reply-To: <1337971575.13348.268.camel@gandalf.stny.rr.com> References: <20120524160146.GA6226@redhat.com> <1337876398.13348.178.camel@gandalf.stny.rr.com> <20120524172223.GA10689@redhat.com> <1337902816.13348.224.camel@gandalf.stny.rr.com> <4FBEC9E6.8040301@linux.intel.com> <1337909963.13348.232.camel@gandalf.stny.rr.com> <1337910106.13348.234.camel@gandalf.stny.rr.com> <1337956262.13348.257.camel@gandalf.stny.rr.com> <1337959746.13348.264.camel@gandalf.stny.rr.com> <4FBFC421.3020901@linux.intel.com> <1337971575.13348.268.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.2.2-1 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1381 Lines: 36 On Fri, 2012-05-25 at 14:46 -0400, Steven Rostedt wrote: > On Fri, 2012-05-25 at 10:40 -0700, H. Peter Anvin wrote: > > On 05/25/2012 08:29 AM, Steven Rostedt wrote: > > > > > > This would make sense for this bug, as if modifying_ftrace_code was not > > > seen by other CPUs, it wouldn't go into the ftrace_int3_handler() path. > > > That would cause this issue. But the bug remains after the smp_mb()'s > > > were put in place. Although it behaves a little differently not. Maybe > > > there's something else I missed? > > > > > > > Perhaps you should make the modifying_ftrace_code modification atomic... > > it seems odd to have it not be atomic when it is clearly accessed across > > CPUs that way. > > I guess I can make it atomic. Not really a big deal as this (and soon > one other place) is the only place that changes its value. > > I've found another place that may be causing harm, and I'm currently > working on fixing it. Hopefully after that's done, this problem will go > away. Grumble, still faults, and the notifier that I was tracking down happened to be for DIE_OOPS :-p /me continues his search. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/