Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756075Ab0GGVJH (ORCPT ); Wed, 7 Jul 2010 17:09:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754779Ab0GGVJF (ORCPT ); Wed, 7 Jul 2010 17:09:05 -0400 Date: Wed, 7 Jul 2010 18:08:39 -0300 From: Glauber Costa To: Zachary Amsden Cc: Peter Palfrader , Greg KH , linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jeremy Fitzhardinge , Avi Kivity , Marcelo Tosatti Subject: Re: [patch 134/149] x86, paravirt: Add a global synchronization point for pvclock Message-ID: <20100707210839.GN2707@mothafucka.localdomain> References: <20100701175144.GA2116@kroah.com> <20100701173218.125822294@clark.site> <20100707124731.GJ15122@anguilla.noreply.org> <20100707135140.GI2707@mothafucka.localdomain> <20100707143338.GK15122@anguilla.noreply.org> <20100707181511.GL2707@mothafucka.localdomain> <4C34DF8E.7090501@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C34DF8E.7090501@redhat.com> X-ChuckNorris: True User-Agent: Jack Bauer Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2367 Lines: 52 On Wed, Jul 07, 2010 at 10:11:58AM -1000, Zachary Amsden wrote: > On 07/07/2010 08:15 AM, Glauber Costa wrote: > >On Wed, Jul 07, 2010 at 04:33:39PM +0200, Peter Palfrader wrote: > >>On Wed, 07 Jul 2010, Glauber Costa wrote: > >> > >>>>2.6.32.16 fails to boot on my KVM domains using qemu-kvm 0.11.1. > >>>> > >>>>Bisecting between 2.6.32.14 which worked and .16 turned up this commit > >>>>as the first culprit[0]. > >>>> > >>>>The host is still running 2.6.32.14 and has 8 cores on 2 CPUs. The > >>>>single-cpu KVM domain hangs just after printing 'Write protecting the > >>>>kernel read-only data: 9492k'[1]. On a successful boot this line would > >>>>usually be followed by 'INIT: version 2.86 booting'. > >>>> > >>>>A 2.6.32.16 with this patch reverted boots fine. > >>>> > >>>>If there's any info you need please just ask. > >>>if you boot with another clocksource, and then switch to kvmclock with the machine already > >>>running, do you see anything strange or suspicious? > >>Booting with various clocksource=xxx kernel parameters does not change > >>the behaviour at all, i.e. the boot still hangs. > >wow, it is really weird then. > > > >that patch shouldn't affect anything outside the pvclock realm. > > Unless you added data which is mistakenly in read-only section, I > can't see how it would affect anything either. Of course, you have > changed the data and text size, it is possible this triggered > another bug. Yes, but at least this patch alone, does not touch anything on that regard (or at least should not). > What exact section does the per-cpu pvclock data fall into? It's > read-only in the kernel, but writeable from the hypervisor. it is not explicitly marked read only in the kernel, afaik. we just trust the kernel not to use it. > > Also, did this patch arrive before or after the pvclock reboot > bugfix? Because if the hypervisor is still writing the pvclock > page, clocksource=xxx would not change that behavior without that > fix. Dunno in which order they got applied in stable. But from what I understood, this is not a reboot scenario. It happens on first boot, right? -- 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/