From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968115Ab0B0JwG (ORCPT ); Sat, 27 Feb 2010 04:52:06 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:43493 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968098Ab0B0JwC (ORCPT ); Sat, 27 Feb 2010 04:52:02 -0500 Date: Sat, 27 Feb 2010 10:51:15 +0100 From: Ingo Molnar To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com Subject: Re: [PATCH tip/core/rcu 0/2] rcu: fixes for RCU lockdep Message-ID: <20100227095115.GF31794@elte.hu> References: <20100225220624.GA7013@linux.vnet.ibm.com> <20100226115018.GA4519@elte.hu> <20100226174248.GF6733@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100226174248.GF6733@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Paul E. McKenney wrote: > On Fri, Feb 26, 2010 at 12:50:18PM +0100, Ingo Molnar wrote: > > > > * Paul E. McKenney wrote: > > > > > Hello! > > > > > > This set fixes a couple of problems with the RCU-based lockdep patches: > > > > > > 1. Make the lockdep_rcu_dereference() message less alarmist > > > > > > 2. Make rcu_read_lock_sched_held() take boot-time lack of > > > preemption into account. > > > > > > Thanx, Paul > > > > > > ------------------------------------------------------------------------ > > > > > > include/linux/rcupdate.h | 4 +++- > > > include/linux/rcutiny.h | 4 ---- > > > include/linux/rcutree.h | 1 - > > > kernel/lockdep.c | 7 +++---- > > > kernel/rcupdate.c | 18 ++++++++++++++++++ > > > kernel/rcutree.c | 20 -------------------- > > > 6 files changed, 24 insertions(+), 30 deletions(-) > > > > Applied, thanks Paul! > > > > Here's a new warning: > > > > [ 0.000000] > > [ 0.000000] =================================================== > > [ 0.000000] [ INFO: suspicious rcu_dereference_check() usage. ] > > [ 0.000000] --------------------------------------------------- > > [ 0.000000] kernel/sched_fair.c:3469 invoked rcu_dereference_check() without protection! > > Hmmm... Could you please tell me what commit this test ran against? One version of tip:master :-/ ob'kconfig - i think this header bit of the .config: > > # Automatically generated make config: don't edit > > # Linux kernel version: 2.6.33 > > # Fri Feb 26 14:51:28 2010 should contain the last-seen kernel Git sha1 as well. It would ease things considerably. > My guesses thus far either don't have that many lines in kernel/sched_fair.c > or have some unrelated code at line 3469. I'll post the sha1 next time i encounter this warning. Thanks, Ingo