From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752045AbbAMLjl (ORCPT ); Tue, 13 Jan 2015 06:39:41 -0500 Received: from mail9.hitachi.co.jp ([133.145.228.44]:35732 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751212AbbAMLjk (ORCPT ); Tue, 13 Jan 2015 06:39:40 -0500 Message-ID: <54B503F5.4020509@hitachi.com> Date: Tue, 13 Jan 2015 20:39:33 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Steven Rostedt Cc: LKML , vvs@sw.ru Subject: Re: Bug with jprobes and function graph tracer References: <20150108122016.0241f713@gandalf.local.home> In-Reply-To: <20150108122016.0241f713@gandalf.local.home> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2015/01/09 2:20), Steven Rostedt wrote: > Hi Masami, > > First, I would like to wish you a Happy New Year :-) Happy New Year! :) > OK, now back to business. > > > It has come to my attention that jprobes and function graph tracing do > not play nicely together. I think you once told me they have issues as > well. > > A simple way to test this is to load the jprobe_example.ko module and > then run function graph tracing. I see. Jprobes will mess up the function call path. > Should we try to fix this? Or should it just be that users need to know > not to enable the two together. Or we can prevent one from starting if > the other is being used. Yeah we should try to fix this, but not so high priority since jprobe is not used so frequently. I guess one easy solution is adding notrace to all jprobe handlers for hiding it from function-graph tracer. If there is a way to check a function is notrace or not, I can use that in register_jprobe and reject it if the handler is not "notrace"ed. :) Thank you, > > Looking forward to hearing your thoughts on the subject. > > -- Steve > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com