From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935457AbeBMOki (ORCPT ); Tue, 13 Feb 2018 09:40:38 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:59532 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S935298AbeBMOkh (ORCPT ); Tue, 13 Feb 2018 09:40:37 -0500 Subject: Re: [patch] kvm: suppress KVM_SET_GSI_ROUTING allocation failure To: David Rientjes , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: From: Paolo Bonzini Message-ID: <706b878f-3375-cf2b-c194-d348cb6d510b@redhat.com> Date: Tue, 13 Feb 2018 15:40:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/02/2018 22:35, David Rientjes 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: > > vmalloc: allocation failure: 0 bytes, mode:0x24000c2(GFP_KERNEL|__GFP_HIGHMEM) > Call Trace: > __dump_stack lib/dump_stack.c:15 [inline] > dump_stack+0xf6/0x184 lib/dump_stack.c:51 > warn_alloc+0x208/0x230 mm/page_alloc.c:2930 > __vmalloc_node_range_memcg+0x510/0x670 mm/vmalloc.c:1711 > __vmalloc_node_memcg mm/vmalloc.c:1751 [inline] > __vmalloc_node_memcg_flags mm/vmalloc.c:1788 [inline] > vmalloc+0x69/0x70 mm/vmalloc.c:1803 > kvm_vm_ioctl+0x910/0x15e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4153 > vfs_ioctl fs/ioctl.c:44 [inline] > do_vfs_ioctl+0x842/0xee0 fs/ioctl.c:611 > SYSC_ioctl fs/ioctl.c:626 [inline] > SyS_ioctl+0x94/0xc0 fs/ioctl.c:617 > entry_SYSCALL_64_fastpath+0x12/0x17 > > If the vmalloc address space is fully depleted, the ioctl can gracefully > fail. Add __GFP_NOWARN to the allocation to suppress the warning. > > Signed-off-by: David Rientjes Queued, thanks. Paolo > --- > virt/kvm/kvm_main.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 001085b611ad..d0352dd45b95 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3063,7 +3063,8 @@ static long kvm_vm_ioctl(struct file *filp, > goto out; > if (routing.nr) { > r = -ENOMEM; > - entries = vmalloc(routing.nr * sizeof(*entries)); > + entries = __vmalloc(routing.nr * sizeof(*entries), > + GFP_KERNEL | __GFP_NOWARN, PAGE_KERNEL); > if (!entries) > goto out; > r = -EFAULT; >