From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964901Ab2I2Nhq (ORCPT ); Sat, 29 Sep 2012 09:37:46 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:57088 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755028Ab2I2Nhn (ORCPT ); Sat, 29 Sep 2012 09:37:43 -0400 Date: Sat, 29 Sep 2012 06:37:37 -0700 From: "Paul E. McKenney" To: Frederic Weisbecker Cc: Sasha Levin , Dave Jones , "linux-kernel@vger.kernel.org" Subject: Re: rcu: eqs related warnings in linux-next Message-ID: <20120929133737.GB2551@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <50659D37.2020206@gmail.com> <20120928133633.GC12843@somewhere.redhat.com> <20120928173133.GB2498@linux.vnet.ibm.com> <50669952.1000805@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12092913-7282-0000-0000-00000D786456 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 29, 2012 at 02:25:04PM +0200, Frederic Weisbecker wrote: > 2012/9/29 Sasha Levin : > > Maybe I could help here a bit. > > > > lappy linux # addr2line -i -e vmlinux ffffffff8111d45f > > /usr/src/linux/kernel/timer.c:549 > > /usr/src/linux/include/linux/jump_label.h:101 > > /usr/src/linux/include/trace/events/timer.h:44 > > /usr/src/linux/kernel/timer.c:601 > > /usr/src/linux/kernel/timer.c:734 > > /usr/src/linux/kernel/timer.c:886 > > > > Which means that it was about to: > > > > debug_object_activate(timer, &timer_debug_descr); Understood and agreed, hence my severe diagnostic patch. > I can't find anything in the debug object code that might fault. > I was suspecting some per cpu allocated memory: per cpu allocation > sometimes use vmalloc > which uses lazy paging using faults. But I can't find such thing there. > > May be there is some faulting specific to KVM... Sasha, is the easily reproducible? If so, could you please try the previous patch? It will likely give us more information on where this bug really lives. (Yes, it might totally obscure the bug, but in that case we will just need to try some other perturbation.) Thanx, Paul