From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Clayton Subject: Re: qemu-kvm-1.1.0 crashing with kernel 3.5.0-rc6 Date: Thu, 19 Jul 2012 19:23:41 +0100 Message-ID: <500850AD.8080504@googlemail.com> References: <4FFAB92C.4030001@googlemail.com> <4FFD26B6.8000802@googlemail.com> <20120711071200.GG23898@redhat.com> <4FFD28B9.9040604@googlemail.com> <20120711072255.GH23898@redhat.com> <50031F85.6020908@googlemail.com> <5007FA1C.5080606@googlemail.com> <5007FAD6.2010407@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail-wg0-f42.google.com ([74.125.82.42]:46684 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751559Ab2GSSXn (ORCPT ); Thu, 19 Jul 2012 14:23:43 -0400 Received: by wgbfm10 with SMTP id fm10so5350844wgb.1 for ; Thu, 19 Jul 2012 11:23:42 -0700 (PDT) In-Reply-To: <5007FAD6.2010407@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/19/12 13:17, Avi Kivity wrote: > On 07/19/2012 03:14 PM, Chris Clayton wrote: > >>> Change of diagnostics, unfortunately. qemu-kvm-1.0.1 can, in fact, crash >>> on 3.5.0-rc6 (and rc7). I didn't get it earlier because it takes many >>> times more invocations before the crash occurs with 1.0.1 and I haven't >>> used qemu-kvm much in the past few weeks. >>> >>> I'm now checking whether I can get crashes (with 1.0.1 and/or 1.1.0) on >>> linux-3.4.4. I'll report back in a day or two. >> >> I've started up qemu-kvm on kernel 3.4.4 many times and not see a crash. >> That would indicate that the problem is in the kernel. However, I pulled >> the latest and greatest from Linus yesterday evening and I now can't get >> the crash there either, so whatever it was seems to have been fixed. If >> I checkout and build 3.5.0-rc[1..7], I can get the crash pretty quickly, >> so it's been fixed in the last few days. > > There were no kvm changes post-rc7. > Yes, I'm aware of that, Avi. This thread started because I was getting a crash in qemu-kvm, which I thought was only in v1.1.0. Later it turned out the the problem was also present in v1.0.1, but much harder to hit. However, it only ever happened with 3.5.0 kernels. 3.4.4, with either version of qemu-kvm, was stable. So then it seemed that the problem was in the kernel, (but not necessarily in the kvm code). Something that's changed since rc7 has either fixed the problem or made it much harder to hit. With rc7 and earlier I can recreate the crash quite easily with qemu-kvm-1.1.0 and with enough runs of 1.0.1. With rc7+, I haven't been able to get a crash at all. I'm not inclined to bisect to find out which patch provided the fix, but this mail should at least close the mail thread down tidily. Chris