From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751859AbeCZNYX (ORCPT ); Mon, 26 Mar 2018 09:24:23 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:33114 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750955AbeCZNYV (ORCPT ); Mon, 26 Mar 2018 09:24:21 -0400 Date: Mon, 26 Mar 2018 16:24:20 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] vhost_net: add missing lock nesting notation Message-ID: <20180326162416-mutt-send-email-mst@kernel.org> References: <1522051823-5166-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522051823-5166-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 26, 2018 at 04:10:23PM +0800, Jason Wang wrote: > We try to hold TX virtqueue mutex in vhost_net_rx_peek_head_len() > after RX virtqueue mutex is held in handle_rx(). This requires an > appropriate lock nesting notation to calm down deadlock detector. > > Fixes: 0308813724606 ("vhost_net: basic polling support") > Reported-by: syzbot+7f073540b1384a614e09@syzkaller.appspotmail.com > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin > --- > drivers/vhost/net.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 8139bc7..12bcfba 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -630,7 +630,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk) > > if (!len && vq->busyloop_timeout) { > /* Both tx vq and rx socket were polled here */ > - mutex_lock(&vq->mutex); > + mutex_lock_nested(&vq->mutex, 1); > vhost_disable_notify(&net->dev, vq); > > preempt_disable(); > @@ -763,7 +763,7 @@ static void handle_rx(struct vhost_net *net) > struct iov_iter fixup; > __virtio16 num_buffers; > > - mutex_lock(&vq->mutex); > + mutex_lock_nested(&vq->mutex, 0); > sock = vq->private_data; > if (!sock) > goto out; > -- > 2.7.4