Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752253AbdCOJSM (ORCPT ); Wed, 15 Mar 2017 05:18:12 -0400 Received: from mail-wr0-f182.google.com ([209.85.128.182]:33381 "EHLO mail-wr0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751894AbdCOJSJ (ORCPT ); Wed, 15 Mar 2017 05:18:09 -0400 Date: Wed, 15 Mar 2017 10:17:55 +0100 From: Christoffer Dall To: Suzuki K Poulose Cc: linux-arm-kernel@lists.infradead.org, andreyknvl@google.com, dvyukov@google.com, marc.zyngier@arm.com, christoffer.dall@linaro.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kcc@google.com, syzkaller@googlegroups.com, will.deacon@arm.com, catalin.marinas@arm.com, pbonzini@redhat.com, mark.rutland@arm.com, ard.biesheuvel@linaro.org, stable@vger.kernel.org Subject: Re: [PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm Message-ID: <20170315091755.GL1277@cbox> References: <1489503154-20705-1-git-send-email-suzuki.poulose@arm.com> <1489503154-20705-2-git-send-email-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1489503154-20705-2-git-send-email-suzuki.poulose@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1315 Lines: 44 On Tue, Mar 14, 2017 at 02:52:32PM +0000, Suzuki K Poulose wrote: > From: Marc Zyngier > > We don't hold the mmap_sem while searching for the VMAs when > we try to unmap each memslot for a VM. Fix this properly to > avoid unexpected results. > > Fixes: commit 957db105c997 ("arm/arm64: KVM: Introduce stage2_unmap_vm") > Cc: stable@vger.kernel.org # v3.19+ > Cc: Christoffer Dall > Signed-off-by: Marc Zyngier > Signed-off-by: Suzuki K Poulose > --- > arch/arm/kvm/mmu.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index 962616f..f2e2e0c 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -803,6 +803,7 @@ void stage2_unmap_vm(struct kvm *kvm) > int idx; > > idx = srcu_read_lock(&kvm->srcu); > + down_read(¤t->mm->mmap_sem); > spin_lock(&kvm->mmu_lock); > > slots = kvm_memslots(kvm); > @@ -810,6 +811,7 @@ void stage2_unmap_vm(struct kvm *kvm) > stage2_unmap_memslot(kvm, memslot); > > spin_unlock(&kvm->mmu_lock); > + up_read(¤t->mm->mmap_sem); > srcu_read_unlock(&kvm->srcu, idx); > } > > -- > 2.7.4 > Are we sure that holding mmu_lock is valid while holding the mmap_sem? Thanks, -Christoffer