diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index 960a19b3e26d..cb1e329d66fd 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -760,13 +760,33 @@ static inline struct l2cap_chan *chan_new_conn_cb(struct l2cap_chan *pchan)
 	return chan;
 }
 
+static void unregister_dev(struct lowpan_btle_dev *dev)
+{
+	struct hci_dev *hdev = READ_ONCE(dev->hdev);
+
+	/* If netdev holds last reference to hci_dev (its parent device), this
+	 * leads to theoretical cyclic locking on lowpan_unregister_netdev:
+	 *
+	 * rtnl_lock -> put_device(parent) -> hci_release_dev ->
+	 * destroy_workqueue -> hci_rx_work -> l2cap_recv_acldata ->
+	 * chan_ready_cb -> ifup -> rtnl_lock
+	 *
+	 * However, hci_rx_work is disabled in hci_unregister_dev, so this
+	 * should not occur. Make lockdep happy by postponing hdev release after
+	 * netdev put.
+	 */
+	hci_dev_hold(hdev);
+	lowpan_unregister_netdev(dev->netdev);
+	hci_dev_put(hdev);
+}
+
 static void delete_netdev(struct work_struct *work)
 {
 	struct lowpan_btle_dev *entry = container_of(work,
 						     struct lowpan_btle_dev,
 						     delete_netdev);
 
-	lowpan_unregister_netdev(entry->netdev);
+	unregister_dev(entry);
 
 	/* The entry pointer is deleted by the netdev destructor. */
 }
@@ -1252,6 +1272,7 @@ static void disconnect_devices(void)
 			break;
 
 		new_dev->netdev = entry->netdev;
+		new_dev->hdev = entry->hdev;
 		INIT_LIST_HEAD(&new_dev->list);
 
 		list_add_rcu(&new_dev->list, &devices);
@@ -1263,7 +1284,7 @@ static void disconnect_devices(void)
 		ifdown(entry->netdev);
 		BT_DBG("Unregistering netdev %s %p",
 		       entry->netdev->name, entry->netdev);
-		lowpan_unregister_netdev(entry->netdev);
+		unregister_dev(entry);
 		kfree(entry);
 	}
 }