From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760183AbZCTT1n (ORCPT ); Fri, 20 Mar 2009 15:27:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752265AbZCTT1f (ORCPT ); Fri, 20 Mar 2009 15:27:35 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:52508 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751898AbZCTT1e (ORCPT ); Fri, 20 Mar 2009 15:27:34 -0400 Date: Fri, 20 Mar 2009 20:27:21 +0100 From: Ingo Molnar To: "Paul E. McKenney" Cc: Steven Rostedt , LKML , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker Subject: Re: [PATCH 0/5] [GIT PULL] updates for tip/tracing/ftrace Message-ID: <20090320192721.GI6224@elte.hu> References: <20090318031423.981603258@goodmis.org> <20090318055924.GA24627@elte.hu> <20090318073903.GA31341@elte.hu> <20090319073357.GA14615@elte.hu> <20090320174331.GH6698@linux.vnet.ibm.com> <20090320183642.GA2070@elte.hu> <20090320183849.GA3657@elte.hu> <20090320191926.GJ6698@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090320191926.GJ6698@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Paul E. McKenney wrote: > On Fri, Mar 20, 2009 at 07:38:49PM +0100, Ingo Molnar wrote: > > > > * Ingo Molnar wrote: > > > > > > > This looks like it is RCU/stop_machine related. The CPU is > > > > > stuck in in stop_machine? I see that rcu_torture is running. > > > > > Does this go away if you turn off rcu_torture? > > > > > > > > Grasping at straws... Does Lai's rcu_barrier() fix help? > > > > > > which one is that? > > > > ok, found it. Will know in about ~24 hours whether it helps. > > http://lkml.org/lkml/2009/3/20/71 was the one I was thinking of, > just to double-check. Yeah - i just picked it up into tip:core/rcu. I didnt immediately connect the two things, as 'tracer self-test' does not lend itself to 'CPU hotplug and RCU race fix' - but indeed in the case of the function tracer there's a dependency due to stop_machine_run(). Thanks for point it out! Ingo