4.9-stable review patch. If anyone has any objections, please let me know.
------------------
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;