From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: BUG: soft lockup - CPU#0 stuck for 13s! [swapper:0] Date: Wed, 25 Aug 2010 09:22:50 -0500 Message-ID: <4C75273A.4060003@codemonkey.ws> References: <4C75185E.2040006@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Boris Dolgov , kvm@vger.kernel.org, "qemu-devel@nongnu.org" To: Avi Kivity Return-path: Received: from mail-qw0-f46.google.com ([209.85.216.46]:49714 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752049Ab0HYOWw (ORCPT ); Wed, 25 Aug 2010 10:22:52 -0400 Received: by qwh6 with SMTP id 6so539749qwh.19 for ; Wed, 25 Aug 2010 07:22:51 -0700 (PDT) In-Reply-To: <4C75185E.2040006@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/25/2010 08:19 AM, Avi Kivity wrote: > On 08/25/2010 04:15 PM, Boris Dolgov wrote: >> Hello! >> >> I try to use KVM on slackware host and centos5 guest with SMP. >> >> When the server is idle, I get following errors in /var/log/messages: >> http://pastebin.com/4RrMVuXq >> >> Guest: >> [root@centos-5-x64 ~]# uname -a >> Linux centos-5-x64.slave 2.6.18-194.11.1.el5 #1 SMP Tue Aug 10 >> 19:05:06 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux >> >> Start command: /usr/local/qemu/bin/qemu-system-x86_64 -name >> centos-5-x64 -m 384 -smp 2 -cdrom >> /root/CentOS-5.5-x86_64-netinstall.iso -drive >> index=0,media=disk,if=virtio,file=/dev/mapper/vgvm-centos5x64,boot=on >> -vnc 0.0.0.0:1 -net nic,macaddr=fe:e1:de:ad:57:22 -net >> tap,script=/usr/local/qemu/bin/qemu-ifup -monitor stdio -usb >> -usbdevice tablet -enable-kvm >> >> Host: >> root@superserver:~# uname -a >> Linux superserver 2.6.35.3 #4 SMP Mon Aug 23 12:17:01 MSD 2010 x86_64 >> Intel(R) Xeon(R) CPU X3460 @ 2.80GHz GenuineIntel GNU/Linux >> root@superserver:~# /usr/local/qemu/bin/qemu-system-x86_64 -version >> QEMU PC emulator version 0.12.5 (qemu-kvm-0.12.5), Copyright (c) >> 2003-2008 Fabrice Bellard >> >> What does it mean? > > Looks like a bug in our USB emulation. Copying qemu-devel to see if > anyone has a clue. USB tablet emulation would not do anything that causes QEMU to block so it seems unlikely to me. What's more likely is that since USB is polling based, statistically speaking it's more likely that a VCPU is executing that call when the soft lockup is detected. Regards, Anthony Liguori