This is a note to let you know that I've just added the patch titled

vhost_net: add missing lock nesting notation

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: vhost_net-add-missing-lock-nesting-notation.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Apr 11 10:26:56 CEST 2018

From: Jason Wang jasowang@redhat.com Date: Mon, 26 Mar 2018 16:10:23 +0800 Subject: vhost_net: add missing lock nesting notation

From: Jason Wang jasowang@redhat.com

[ Upstream commit aaa3149bbee9ba9b4e6f0bd6e3e7d191edeae942 ]

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 jasowang@redhat.com Acked-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/vhost/net.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -524,7 +524,7 @@ static int vhost_net_rx_peek_head_len(st

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(); @@ -657,7 +657,7 @@ static void handle_rx(struct vhost_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;

Patches currently in stable-queue which might be from jasowang@redhat.com are

queue-4.9/skbuff-return-emsgsize-in-skb_to_sgvec-to-prevent-overflow.patch queue-4.9/virtio_net-check-return-value-of-skb_to_sgvec-always.patch queue-4.9/vhost-validate-log-when-iotlb-is-enabled.patch queue-4.9/vhost_net-add-missing-lock-nesting-notation.patch queue-4.9/vhost-correctly-remove-wait-queue-during-poll-failure.patch queue-4.9/virtio_net-check-return-value-of-skb_to_sgvec-in-one-more-location.patch