From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zachary Amsden Subject: Re: 2.6.35-rc1 regression with pvclock and smp guests Date: Thu, 30 Sep 2010 03:54:23 -1000 Message-ID: <4CA4968F.9050402@redhat.com> References: <4C4D4B8B.80006@amd.com> <4C4DDB00.50203@xutrox.com> <4C4F48D0.8090609@xutrox.com> <4C500872.1020809@redhat.com> <4C536F80.5090205@xutrox.com> <4C538CCE.1010104@redhat.com> <4C540EC9.1010008@xutrox.com> <4C54512B.6000307@xutrox.com> <4C54B7DE.4060901@redhat.com> <20100802144300.GD14448@mothafucka.localdomain> <4C5729F6.2050605@redhat.com> <4C573A20.6030001@xutrox.com> <4CA2F8A3.80400@redhat.com> <4CA30424.9030007@msgid.tls.msk.ru> <4CA30493.6090503@msgid.tls.msk.ru> <4CA392FE.5090009@xutrox.com> <4CA4427C.9090304@msgid.tls.msk.ru> <4CA45F7B.8050806@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Arjan Koers <0h61vkll2ly8@xutrox.com>, kvm@vger.kernel.org, Avi Kivity , Glauber Costa , Andre Przywara To: Michael Tokarev Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33029 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756123Ab0I3Nyc (ORCPT ); Thu, 30 Sep 2010 09:54:32 -0400 In-Reply-To: <4CA45F7B.8050806@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: On 09/29/2010 11:59 PM, Michael Tokarev wrote: > 30.09.2010 11:55, Michael Tokarev wrote: > >> 29.09.2010 23:26, Arjan Koers wrote: >> >>> On 2010-09-29 11:19, Michael Tokarev wrote: >>> >>>> 29.09.2010 13:17, Michael Tokarev wrote: >>>> >> [] >> >>>>> Avi, this is definitely a -stable material, for 2.6.32 (longterm >>>>> stable) and 2.6.35. >>>>> >>>> Er. Please excuse me for the misinformation. It is _not_ for 2.6.32 >>>> ofcourse. >>>> >>> I wish you hadn't mentioned 2.6.32. I just tried 2.6.32.23 and it also >>> hangs. Reverting commit 1345126c761f0360dc108973bf73281d51945bc1 >>> (introduced in 2.6.32.16) makes it boot again. >>> >>> The kvmclock printk patch doesn't help, but I'll try to figure out >>> what's wrong. >>> >> It works here just fine - both 32- and 64-bit 2.6.32.23 as is, >> and both 32- and 64-bit 2.6.35.6 with the printk.time patch >> applied. >> > Ok, I can confirm there's another issue somewhere around this. > > After numerous tries I noticed that guests sporadically stops > during bootup - either somewhere in the middle or at the very > end of it. It is definitely not this problem with printk time, > but it appears to be related to kvm-clock still, and smp. > > This time, the lockup isn't really a lock up per se - the system > works (fsvo) - it reacts to keyboard, I can scroll up/down the > text console. But it does nothing more, and in particular I've > no idea what it is waiting for. It does not consume host CPU > as the printk.time problem had. > > Happens most with 2.6.35.6 32bit guest kernel. I weren't able > to reproduce it with 2.6.35.6 64bit. Does not happen on > 2.6.35.3. And happens sporadically on 2.6.32.23 32bit too. > > The thing always happens during some module load or other > _kernel_ work. F.e. right now I've 2.6.35.6 32bit kernel > sitting after the login prompt (the Login: is at the middle > of the screen), with a few messages after the login prompt > telling me about various "misc" drivers (floppy, parport, > sg, piix_smbus etc) loaded. > > Booting with clocksource=tsc does not expose the problem > so far - at least the most problematic 2.6.35.6 32bit always > booted ok with tsc. But since the issue is intermittent, > one can't be sure it's really pvclock. > > /mjt > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > The printk movement is just a bandaid patch, correct? Anything which does printk before kvmclock is registered could trigger the same bug. Can you try with printk timing disabled and see if the bug disappears? Zach