Index: head/sys/dev/hyperv/vmbus/vmbus_chan.c
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chan.c
+++ head/sys/dev/hyperv/vmbus/vmbus_chan.c
@@ -392,6 +392,8 @@
 	/*
 	 * Connect the bufrings, both RX and TX, to this channel.
 	 */
+	KASSERT(chan->ch_bufring_gpadl == 0,
+	    ("bufring GPADL is still connected"));
 	error = vmbus_chan_gpadl_connect(chan, cbr->cbr_paddr,
 	    txbr_size + rxbr_size, &chan->ch_bufring_gpadl);
 	if (error) {