Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932940AbYBMQG7 (ORCPT ); Wed, 13 Feb 2008 11:06:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757977AbYBMQGv (ORCPT ); Wed, 13 Feb 2008 11:06:51 -0500 Received: from kanga.kvack.org ([66.96.29.28]:53046 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756802AbYBMQGu (ORCPT ); Wed, 13 Feb 2008 11:06:50 -0500 Date: Wed, 13 Feb 2008 14:09:05 -0200 From: Marcelo Tosatti To: Jiri Kosina , Avi Kivity Cc: Zdenek Kabelac , linux-kernel@vger.kernel.org Subject: Re: Qemu & KVM bug Message-ID: <20080213160905.GA8559@dmt> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1763 Lines: 51 On Wed, Feb 13, 2008 at 04:24:53PM +0100, Jiri Kosina wrote: > On Wed, 13 Feb 2008, Zdenek Kabelac wrote: > > > I get this bug in my log whenever I start qemu-kvm - I do not use kqemu > > module - so it's with plain kernel modules. If more details are needed - > > just ask. (Cpu; C2D) > > BUG: sleeping function called from invalid context at kernel/rwsem.c:48 > > in_atomic():1, irqs_disabled():0 > > INFO: lockdep is turned off. > > Pid: 26600, comm: qemu-kvm Not tainted 2.6.25-rc1 #29 > > This has been obviously caused by Marcelo's (added to CC) commit > 10589a4699b, which added down_write(mmap_sem) to alloc_apic_access_page(), > which is called with preempt disabled from vmx_create_vcpu(). alloc_apic_access_page() called mutex_lock, so the warning would trigger before that change. I think it's fine to allocate the APIC page after put_cpu(), since no vcpu state is required. Avi? --- linux-2.6.orig/arch/x86/kvm/vmx.c +++ linux-2.6/arch/x86/kvm/vmx.c @@ -1601,9 +1601,6 @@ static int vmx_vcpu_setup(struct vcpu_vm vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL); vmcs_writel(CR4_GUEST_HOST_MASK, KVM_GUEST_CR4_MASK); - if (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm)) - if (alloc_apic_access_page(vmx->vcpu.kvm) != 0) - return -ENOMEM; return 0; } @@ -2533,6 +2530,9 @@ static struct kvm_vcpu *vmx_create_vcpu( put_cpu(); if (err) goto free_vmcs; + if (vm_need_virtualize_apic_accesses(kvm)) + if (alloc_apic_access_page(kvm) != 0) + goto free_vmcs; return &vmx->vcpu; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/