From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: qemu-kvm-1.1.0 crashing with kernel 3.5.0-rc6 Date: Mon, 30 Jul 2012 19:39:31 +0300 Message-ID: <5016B8C3.7040103@redhat.com> References: <5011D123.4060101@googlemail.com> <5012719A.5080208@googlemail.com> <5012E659.7060304@googlemail.com> <50152FC8.20905@redhat.com> <50154294.9040705@googlemail.com> <50154632.7010304@redhat.com> <50155AF4.9050500@redhat.com> <5015662A.2000006@redhat.com> <501577D1.7030205@googlemail.com> <20120729175453.GA32360@redhat.com> <50158A97.3050909@googlemail.com> <50169389.1020607@googlemail.com> <50169421.6060406@redhat.com> <50169515.7050900@googlemail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , Eric Northup , kvm@vger.kernel.org, Jan Kiszka , Marcelo Tosatti To: Chris Clayton Return-path: Received: from mx1.redhat.com ([209.132.183.28]:11783 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753709Ab2G3Qjh (ORCPT ); Mon, 30 Jul 2012 12:39:37 -0400 In-Reply-To: <50169515.7050900@googlemail.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/30/2012 05:07 PM, Chris Clayton wrote: >> >>>> With kernel 3.5.0 with b2da15ac26a0c00 reverted, I have just had 15 >>>> clean invocations of vanilla qemu-kvm-1.1.1. So that commit would seem >>>> to be the problem. >>> >>> Just to be sure, I've run some more tests today. No crashes occurred in >>> 20 runs of vanilla qemu-kvm-1.1.1 on kernel 3.5.0 with b2da15ac26a0c00 >>> reverted. >> >> Ok. I'm trying to reproduce it here on a nested-virt setup, since the >> code looks correct. >> >> What's your preemption settings? >> >> > [chris:~/kernel/linux-3.5.0]$ grep PREEMPT .config > CONFIG_TREE_PREEMPT_RCU=y > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_NOTIFIERS=y > # CONFIG_PREEMPT_NONE is not set > # CONFIG_PREEMPT_VOLUNTARY is not set > CONFIG_PREEMPT=y > CONFIG_PREEMPT_COUNT=y Here's what I think that is happening vcpu_load ... vmx_save_host_state vmx_vcpu_run (ds.cpl, es.cpl cleared by hardware) interrupt push ds, es # pushes bad ds, es schedule vmx_vcpu_put vmx_load_host_state reload ds, es pop ds, es # of other thread's stack iret # other thread runs interrupt schedule # back in vcpu thread interrupt return: pop ds, es # <-- problem iret ... vcpu_put # bad ds, es, but !vmx->host_state.loaded Marcelo, did I miss something here? Unfortunately, my reproducer has ceased to reproduce. But the fix is easy if the analysis above is right. -- error compiling committee.c: too many arguments to function