Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757572Ab2EGWKi (ORCPT ); Mon, 7 May 2012 18:10:38 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:60026 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757066Ab2EGWKd (ORCPT ); Mon, 7 May 2012 18:10:33 -0400 Date: Tue, 8 May 2012 01:10:04 +0300 From: Sergey Senozhatsky To: Avi Kivity Cc: paulmck@linux.vnet.ibm.com, Marcelo Tosatti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Dave Jones Subject: Re: possible circular locking dependency Message-ID: <20120507221004.GD4469@swordfish> References: <20120503200259.GA3524@swordfish.minsk.epam.com> <4FA63C82.7030309@redhat.com> <20120506164209.GK2470@linux.vnet.ibm.com> <20120506203439.GB3633@swordfish> <20120507034744.GA3141@linux.vnet.ibm.com> <4FA77F4C.9080908@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FA77F4C.9080908@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1859 Lines: 48 On (05/07/12 10:52), Avi Kivity wrote: > On 05/07/2012 06:47 AM, Paul E. McKenney wrote: > > On Sun, May 06, 2012 at 11:34:39PM +0300, Sergey Senozhatsky wrote: > > > On (05/06/12 09:42), Paul E. McKenney wrote: > > > > On Sun, May 06, 2012 at 11:55:30AM +0300, Avi Kivity wrote: > > > > > On 05/03/2012 11:02 PM, Sergey Senozhatsky wrote: > > > > > > Hello, > > > > > > 3.4-rc5 > > > > > > > > > > Whoa. > > > > > > > > > > Looks like inconsistent locking between cpufreq and > > > > > synchronize_srcu_expedited(). kvm triggered this because it is one of > > > > > the few users of synchronize_srcu_expedited(), but I don't think it is > > > > > doing anything wrong directly. > > > > > > > > > > Dave, Paul? > > > > > > > > SRCU hasn't changed much in mainline for quite some time. Holding > > > > the hotplug mutex across a synchronize_srcu() is a bad idea, though. > > > > > > > > However, there is a reworked implementation (courtesy of Lai Jiangshan) > > > > in -rcu that does not acquire the hotplug mutex. Could you try that out? > > > > > > > > > > Paul, should I try solely -rcu or there are several commits to pick up and apply > > > on top of -linus tree? > > > > If you want the smallest possible change, take the rcu/srcu branch of -rcu. > > If you want the works, take the rcu/next branch of -rcu. > > > > You can find -rcu at: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git > > To make the difference even smaller, merge the above branch with v3.4-rc5. > I'm unable to reproduce the issue on 3.4-rc6 so far. So I guess this will take some time. Sergey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/