From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:58527)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1YNMVI-0004Ks-An
	for qemu-devel@nongnu.org; Mon, 16 Feb 2015 09:18:29 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1YNMVE-00082V-SK
	for qemu-devel@nongnu.org; Mon, 16 Feb 2015 09:18:28 -0500
Received: from mail-we0-x231.google.com ([2a00:1450:400c:c03::231]:45822)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1YNMVE-00082M-EI
	for qemu-devel@nongnu.org; Mon, 16 Feb 2015 09:18:24 -0500
Received: by mail-we0-f177.google.com with SMTP id m14so23648242wev.8
	for <qemu-devel@nongnu.org>; Mon, 16 Feb 2015 06:18:23 -0800 (PST)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <54E1FC2B.3030805@redhat.com>
Date: Mon, 16 Feb 2015 15:18:19 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <54AE87C1.2060907@wiesinger.com>	<54AEBD43.2060705@redhat.com>	<54AEC877.9080600@wiesinger.com>	<54AECAF3.3060909@redhat.com>	<54AF047D.8010009@wiesinger.com>	<54B3B2F5.1090405@wiesinger.com>	<54B57C51.7090002@wiesinger.com>	<54B584AB.4090303@redhat.com>	<54B58AC0.5080805@wiesinger.com>	<54B58B18.9060205@redhat.com>	<54B595C7.3080101@wiesinger.com>
	<54B5BF5F.9000805@redhat.com> <54B633CE.3040901@wiesinger.com>
	<54E05659.9050701@wiesinger.com>
In-Reply-To: <54E05659.9050701@wiesinger.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] Fedora FC21 - Bug: 100% CPU and hangs in
 gettimeofday(&tp, NULL); forever
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Gerhard Wiesinger <lists@wiesinger.com>, Laine Stump <laine@redhat.com>, qemu-devel@nongnu.org, Cole Robinson <crobinso@redhat.com>, virt@lists.fedoraproject.org



On 15/02/2015 09:18, Gerhard Wiesinger wrote:
> 
> ppoll([{fd=98<socket:[4660317]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=89<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=88<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=87<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=86<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=85<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=84<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=83<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=82<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=81<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=80<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=79<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=78<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=77<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=76<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=75<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=74<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=73<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=72<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=71<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=70<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=69<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=68<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=67<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=66<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=65<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=64<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=63<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=62<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=61<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=60<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP},
> {fd=59<anon_inode:[eventfd]>, events=POLLIN|POLLERR|POLLHUP}, ...], 71,
> {0, 124112228}, NULL, 8) = 1 ([...], left {0, 124090614})
> write(7<anon_inode:[eventfd]>, "\1\0\0\0\0\0\0\0", 8) = 8
> read(6<anon_inode:[eventfd]>, "\1\0\0\0\0\0\0\0", 512) = 8
> write(7<anon_inode:[eventfd]>, "\1\0\0\0\0\0\0\0", 8) = 8

Can you grab some random backtraces ("thread apply all bt full") with gdb?

What is the libvirt XML or qemu command line?

Paolo

> Kernel (host/guest):  3.18.6-200.fc21.x86_64 #1 SMP
> qemu-kvm-2.2.0-5.fc21.x86_64
> 
> Bug 1178975 - endless loop in clock_gettime() on a kvm-based VM
> https://bugzilla.redhat.com/show_bug.cgi?id=1178975
> is fixed (didn't occour with the test program posted at
> https://bugzilla.redhat.com/show_bug.cgi?id=1178975#c28 in 30min,
> happened before reproduceable in 2min, still running)
> 
> So I guess there is another problem in the kernel with volatile and gcc
> optimizations (or maybe in qemu-KVM)

No, this doesn't look like volatile.