From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752795AbaDUN0q (ORCPT ); Mon, 21 Apr 2014 09:26:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57498 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752354AbaDUN0G (ORCPT ); Mon, 21 Apr 2014 09:26:06 -0400 Date: Mon, 21 Apr 2014 15:26:01 +0200 From: Oleg Nesterov To: Avi Kivity , Gleb Natapov , Paolo Bonzini Cc: Dominik Dingel , Christian Borntraeger , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] KVM: async_pf: mm->mm_users can not pin apf->mm Message-ID: <20140421132601.GA13615@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140421132543.GA13594@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org get_user_pages(mm) is simply wrong if mm->mm_users == 0 and exit_mmap/etc was already called (or is in progress), mm->mm_count can only pin mm->pgd and mm_struct itself. Change kvm_setup_async_pf/async_pf_execute to inc/dec mm->mm_users. kvm_create_vm/kvm_destroy_vm play with ->mm_count too but this case looks fine at first glance, it seems that this ->mm is only used to verify that current->mm == kvm->mm. Signed-off-by: Oleg Nesterov --- virt/kvm/async_pf.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index 0ced4f3..cda703e 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -99,7 +99,7 @@ static void async_pf_execute(struct work_struct *work) if (waitqueue_active(&vcpu->wq)) wake_up_interruptible(&vcpu->wq); - mmdrop(mm); + mmput(mm); kvm_put_kvm(vcpu->kvm); } @@ -116,7 +116,7 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) flush_work(&work->work); #else if (cancel_work_sync(&work->work)) { - mmdrop(work->mm); + mmput(work->mm); kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ kmem_cache_free(async_pf_cache, work); } @@ -181,7 +181,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva, work->addr = hva; work->arch = *arch; work->mm = current->mm; - atomic_inc(&work->mm->mm_count); + atomic_inc(&work->mm->mm_users); kvm_get_kvm(work->vcpu->kvm); /* this can't really happen otherwise gfn_to_pfn_async @@ -199,7 +199,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva, return 1; retry_sync: kvm_put_kvm(work->vcpu->kvm); - mmdrop(work->mm); + mmput(work->mm); kmem_cache_free(async_pf_cache, work); return 0; } -- 1.5.5.1