From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42202) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WVObs-0005p1-Er for qemu-devel@nongnu.org; Wed, 02 Apr 2014 13:06:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WVObk-0004Mr-Ou for qemu-devel@nongnu.org; Wed, 02 Apr 2014 13:05:56 -0400 Received: from mx.beyond.pl ([92.43.117.49]:44020) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WVObk-0004MD-IT for qemu-devel@nongnu.org; Wed, 02 Apr 2014 13:05:48 -0400 Message-ID: <533C4360.5030801@beyond.pl> Date: Wed, 02 Apr 2014 19:05:36 +0200 From: =?UTF-8?B?TWFyY2luIEdpYnXFgmE=?= MIME-Version: 1.0 References: <20140327225242.GA5005@onthe.net.au> <5334B44E.4080300@beyond.pl> <20140327235918.GA7689@onthe.net.au> <533929D3.30109@beyond.pl> <20140402054144.GA31323@onthe.net.au> <533BCE40.8060908@beyond.pl> <20140402090450.GA2586@work-vm> <533BD8CE.9060002@beyond.pl> <20140402093938.GB2586@work-vm> In-Reply-To: <20140402093938.GB2586@work-vm> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Unresponsive linux guest once migrated List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dgilbert@redhat.com Cc: qemu-devel@nongnu.org >> Yes, that's where it gets weird. I've never seen this on fresh VM. >> It needs to be idle for couple of hours at least. And even then it >> doesn't always hang. > > So your OS is just sitting at a text console, running nothing special? > When you reboot after the migration what's the last thing you see > in the guests logs? Is there anything from after the migration? Yes, it's completely idle. After reboot there is nothing in logs. I've dumped memory of one of hanged test VMs and found kernel message buffer. The last entries were: init: failsafe main process (659) killed by TERM signal init: plymouth-upstart-bridge main process (651) killed by TERM signal Clocksource tsc unstable (delta = 470666274 ns) Uhhuh. NMI received for unknown reason 30 on CPU 0. Do you have a strange power saving mode enabled?I: Dazed and confused, but trying to continue Uhhuh. NMI received for unknown reason 20 on CPU 0. Do you have a strange power saving mode enabled?I: Dazed and confused, but trying to continue <0>Dazed and confused, but trying to continue I've tried to disassemble where VM kernel (3.8.something from Ubuntu) is spinning (using qemu-monitor, registers info and symbols from guest kernel) and it was loop inside __run_timers function from kernel/timer.c: while (time_after_eq(jiffies, base->timer_jiffies)) { ... } However my disassembly and qemu debugging skills are limited, would it help if I dump memory of broken VM and send it you somehow? -- mg