From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967369AbeBNLQ4 (ORCPT ); Wed, 14 Feb 2018 06:16:56 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:40104 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967252AbeBNLQz (ORCPT ); Wed, 14 Feb 2018 06:16:55 -0500 Subject: Re: [patch] kvm: suppress KVM_SET_GSI_ROUTING allocation failure To: Paolo Bonzini , David Rientjes Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <47a55220-0006-6486-5a9d-1d1142efcc47@de.ibm.com> <179c1c39-2b3f-20f6-d4cb-0044aa49e570@redhat.com> From: Christian Borntraeger Date: Wed, 14 Feb 2018 12:14:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <179c1c39-2b3f-20f6-d4cb-0044aa49e570@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18021411-0012-0000-0000-000005AE9C12 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18021411-0013-0000-0000-0000192A6745 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-14_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802140132 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/14/2018 11:10 AM, Paolo Bonzini wrote: > On 14/02/2018 02:03, David Rientjes wrote: >> On Tue, 13 Feb 2018, Paolo Bonzini wrote: >> >>>>> The KVM_SET_GSI_ROUTING ioctl does a vmalloc() of >>>>> sizeof(struct kvm_irq_routing_entry) multiplied by a user-supplied value. >>>>> This can be up to 4096 entries on architectures such as arm64 and s390 >>>>> (and the upper bound may be increased on s390 eventually). >>>>> >>>>> This can produce a vmalloc allocation failure warning: >>>>> >>>> [...] >>>>> kvm_vm_ioctl+0x910/0x15e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4153 >>>> >>>> ^^^^^ >>>> >>>>> @@ -3063,7 +3063,8 @@ static long kvm_vm_ioctl(struct file *filp, >>>> >>>> ^^^^^ >>>> >>>> >>>> Are you sure that you got the right vmalloc? >>> >>> Nice catch! But well, it's the only one in the whole file. :) >>> >>> That seems very much like an old patch then. I'm unqueuing it. >>> >> >> It's not a catch at all, the fact that I saw this warning with an older >> kernel for KVM_SET_GSI_ROUTING doesn't mean that I can't patch it with an >> upstream kernel. Would you prefer I remove the stack trace completely? > > The upstream kernel doesn't warn. It checks "if (routing.nr)" before > calling vmalloc. It will warn of the vmalloc space is really exhausted. But then I really ask myself if we really want to suppress this warning. This should be a big ALERT to the host admin.