On 24.03.2023 12:06, Stefano Garzarella wrote: > On Fri, Mar 24, 2023 at 9:55 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote: >> >> On Fri, Mar 24, 2023 at 9:31 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote: >>> >>> Hi Bobby, >>> can you take a look at this report? >>> >>> It seems related to the changes we made to support skbuff. >> >> Could it be a problem of concurrent access to pkt_queue ? >> >> IIUC we should hold pkt_queue.lock when we call skb_queue_splice_init() >> and remove pkt_list_lock. (or hold pkt_list_lock when calling >> virtio_transport_purge_skbs, but pkt_list_lock seems useless now that >> we use skbuff) >> > > In the previous patch was missing a hunk, new one attached: > > #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fff5a5e7f528 > > --- a/net/vmw_vsock/vsock_loopback.c > +++ b/net/vmw_vsock/vsock_loopback.c > @@ -15,7 +15,6 @@ > struct vsock_loopback { > struct workqueue_struct *workqueue; > > - spinlock_t pkt_list_lock; /* protects pkt_list */ > struct sk_buff_head pkt_queue; > struct work_struct pkt_work; > }; > @@ -32,9 +31,7 @@ static int vsock_loopback_send_pkt(struct sk_buff *skb) > struct vsock_loopback *vsock = &the_vsock_loopback; > int len = skb->len; > > - spin_lock_bh(&vsock->pkt_list_lock); > skb_queue_tail(&vsock->pkt_queue, skb); Hello Stefano and Bobby, Small remark, may be here we can use virtio_vsock_skb_queue_tail() instead of skb_queue_tail(). skb_queue_tail() disables irqs during spinlock access, while virtio_vsock_skb_queue_tail() uses spin_lock_bh(). vhost and virtio transports use virtio_vsock_skb_queue_tail(). Thanks, Arseniy > - spin_unlock_bh(&vsock->pkt_list_lock); > > queue_work(vsock->workqueue, &vsock->pkt_work); > > @@ -113,9 +110,9 @@ static void vsock_loopback_work(struct work_struct *work) > > skb_queue_head_init(&pkts); > > - spin_lock_bh(&vsock->pkt_list_lock); > + spin_lock_bh(&vsock->pkt_queue.lock); > skb_queue_splice_init(&vsock->pkt_queue, &pkts); > - spin_unlock_bh(&vsock->pkt_list_lock); > + spin_unlock_bh(&vsock->pkt_queue.lock); > > while ((skb = __skb_dequeue(&pkts))) { > virtio_transport_deliver_tap_pkt(skb); > @@ -132,7 +129,6 @@ static int __init vsock_loopback_init(void) > if (!vsock->workqueue) > return -ENOMEM; > > - spin_lock_init(&vsock->pkt_list_lock); > skb_queue_head_init(&vsock->pkt_queue); > INIT_WORK(&vsock->pkt_work, vsock_loopback_work); > > @@ -156,9 +152,7 @@ static void __exit vsock_loopback_exit(void) > > flush_work(&vsock->pkt_work); > > - spin_lock_bh(&vsock->pkt_list_lock); > virtio_vsock_skb_queue_purge(&vsock->pkt_queue); > - spin_unlock_bh(&vsock->pkt_list_lock); > > destroy_workqueue(vsock->workqueue); > } >
