From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: Tracers+cyclictest causing kernel oops Date: Tue, 21 May 2013 13:16:55 +0200 Message-ID: <519B57A7.1010901@linutronix.de> References: <20130503160546.GF8230@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit To: Tom Cook , linux-rt-users Return-path: Received: from www.linutronix.de ([62.245.132.108]:50347 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750716Ab3EULQ5 (ORCPT ); Tue, 21 May 2013 07:16:57 -0400 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: please CC the list. On 05/11/2013 06:43 PM, Tom Cook wrote: > Okay, I've built the same kernel config but without kgdb enabled. > Running cyclictest with a tracer enabled (-f in this case) causes the > crash below. > > I'm not big on debugging these things yet. Since cyclictest works > without the tracers enabled and causes a crash with them enabled, the > problem must be in the tracers themselves, right? Actually, 'echo > function > current_tracer' has the same effect. > > Is that trace really saying that the processor is in mode 0? AFAICT, > ARM does not have a mode 0 unless you truncate the mode number to four > bits - in which case mode '0' is user mode. The process name seems to > be a red herring - repeating this can turn up almost any process > running on the system, from interrupt handler threads to bash. > > Is this a known problem? Any tips on figuring it out? Not known until you brought that up. I just booted x86 with kgdb=y and did "echo function > current_tracer" with no side effects. I don't have ARM at hand right now. Do you do anything kgdb related besides enabling it in the kernel? > > Thanks, > Tom Sebastian