From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37436) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPoDW-0006QW-Ln for qemu-devel@nongnu.org; Wed, 20 Jul 2016 05:55:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bPoDS-0004IB-JB for qemu-devel@nongnu.org; Wed, 20 Jul 2016 05:55:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51657) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPoDS-0004HU-DK for qemu-devel@nongnu.org; Wed, 20 Jul 2016 05:54:58 -0400 References: <5f2b5b51-b75e-13dc-1816-6a61f8002fa7@transip.nl> From: Jason Wang Message-ID: <578F4A6C.4090403@redhat.com> Date: Wed, 20 Jul 2016 17:54:52 +0800 MIME-Version: 1.0 In-Reply-To: <5f2b5b51-b75e-13dc-1816-6a61f8002fa7@transip.nl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] QEMU live migration RARP issue List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Robin Geuze , qemu-devel@nongnu.org, yanghy@cn.fujitsu.com Cc: Frank Schreuder On 2016=E5=B9=B407=E6=9C=8820=E6=97=A5 17:10, Robin Geuze wrote: > Hey guys, > > A few days ago we noticed that some of our VPSes lost network=20 > connection after a live migration using QEMU/KVM. We started=20 > investigating and noticed that the problem was at least present for=20 > guests running FreeBSD, Debian 7 (Linux 3.2.81-1) and some flavors of=20 > CentOS. At least Debian 8 (Linux 3.16.7-ckt25-2) was not affected.=20 > Everything is using the virtio drivers. We also noted that the problem=20 > was not present in QEMU 2.4.0, but was present in QEMU 2.6.0. The=20 > configs between both versions of QEMU are identical. We use libvirt=20 > 1.3.5 to manage QEMU/KVM (same version on both qemu versions). > > After some false starts we managed to reliably reproduce the issue=20 > with a Debian 7 VM. What we noticed was that Debian 8 send out=20 > gratuitous ARP replies. Debian 7 did not appear to send those. After=20 > some further digging we found out that on QEMU 2.4.0 Debian 7 actually=20 > send gratuitous RARP packets after a live migration instead of normal=20 > ARP packets and that those where not present when migrating on QEMU=20 > 2.6.0. We then started narrowing down the responsible commits using=20 > git bisect and eventually ended up with the last good commit being=20 > d62241eb6da9bd2517f07b3219ba4208b90b4e0d and the last bad commit we=20 > tested was 7ef7bc8586fb0d41742a896b532c7afa2bbb7f84. This is a range=20 > of 6 commits introducing the NetFilter functionality. We couldn't=20 > really pinpoint it more accurately so we decided to email you guys, to=20 > see if you can figure out whats up. > > Regards, > > Robin Geuze > > TransIP BV > Hello, have you tried latest qemu codes? We recently fixed a grarp emitting issue in ca1ee3d6b546e841a1b9db413eb8fa09f13a061b ("net: fix qemu_announce_self=20 not emitting packets") Thanks