From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752992AbbANNtg (ORCPT ); Wed, 14 Jan 2015 08:49:36 -0500 Received: from smtprelay0200.hostedemail.com ([216.40.44.200]:34134 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751187AbbANNtf (ORCPT ); Wed, 14 Jan 2015 08:49:35 -0500 X-Session-Marker: 6E657665747340676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2198:2199:2393:2553:2559:2562:2693:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3870:3871:3872:3874:4470:5007:6261:7875:7903:8531:9040:10004:10400:10848:10967:11232:11658:11914:12043:12050:12294:12517:12519:12740:13069:13149:13161:13229:13230:13311:13357:13618:14096:14097:21060:21080,0,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: silk35_3622f889afc08 X-Filterd-Recvd-Size: 2097 Date: Wed, 14 Jan 2015 08:49:30 -0500 From: Steven Rostedt To: Masami Hiramatsu Cc: LKML , vvs@sw.ru Subject: Re: Bug with jprobes and function graph tracer Message-ID: <20150114084930.06e9daf1@gandalf.local.home> In-Reply-To: <54B513A9.8070004@hitachi.com> References: <20150108122016.0241f713@gandalf.local.home> <54B503F5.4020509@hitachi.com> <20150113072232.451c599b@gandalf.local.home> <54B513A9.8070004@hitachi.com> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; 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 Tue, 13 Jan 2015 21:46:33 +0900 Masami Hiramatsu wrote: > > > > I worked on this for the last few days and have a patch that fixes the > > problem. I'll be posting it later today. It also uncovered another > > unrelated bug that I worked on yesterday, otherwise I would have posted > > these fixes already. > > Great! I look forward that! :) I was all set to send the patches but during testing found that this isn't just affected by the fentry code, but also happens when jprobes and kprobes uses the breakpoint method (old mcount and i386). I guess this has always been broken from when jprobes and function graph tracing were together. Anyway, I think I have a simpler solution which simulates making the jprobes "notrace". At least this solution will allow us to have jprobe callbacks traced in the future. But for now, instead of crashing, we'll just disable function graph tracing while its in a jprobe. I'll see if I can get that patch working today (I should stop saying that). But all is not lost. I found two bugs in the current implementation of the function graph tracer because of this :-) -- Steve