Index: linux-3.10.11/drivers/net/xen-netback/common.h
===================================================================
--- linux-3.10.11.orig/drivers/net/xen-netback/common.h	2014-06-26 15:06:45.852000000 +0200
+++ linux-3.10.11/drivers/net/xen-netback/common.h	2014-06-26 15:07:08.420000000 +0200
@@ -66,6 +66,7 @@
 	/* The shared rings and indexes. */
 	struct xen_netif_tx_back_ring tx;
 	struct xen_netif_rx_back_ring rx;
+	bool mapped;
 
 	/* Frontend feature information. */
 	u8 can_sg:1;
Index: linux-3.10.11/drivers/net/xen-netback/interface.c
===================================================================
--- linux-3.10.11.orig/drivers/net/xen-netback/interface.c	2014-06-26 15:04:41.228000000 +0200
+++ linux-3.10.11/drivers/net/xen-netback/interface.c	2014-06-26 15:06:32.660000000 +0200
@@ -271,6 +271,7 @@
 	vif->dev = dev;
 	INIT_LIST_HEAD(&vif->schedule_list);
 	INIT_LIST_HEAD(&vif->notify_list);
+	vif->mapped = false;
 
 	vif->credit_bytes = vif->remaining_credit = ~0UL;
 	vif->credit_usec  = 0UL;
Index: linux-3.10.11/drivers/net/xen-netback/netback.c
===================================================================
--- linux-3.10.11.orig/drivers/net/xen-netback/netback.c	2014-06-26 15:07:22.252000000 +0200
+++ linux-3.10.11/drivers/net/xen-netback/netback.c	2014-06-26 15:10:33.300000000 +0200
@@ -720,6 +720,13 @@
 		vif = netdev_priv(skb->dev);
 		nr_frags = skb_shinfo(skb)->nr_frags;
 
+		if (!vif->mapped) {
+			printk(KERN_ERR "UniDEBUG vif->mapped is false\n");
+			dev_kfree_skb(skb);
+			xenvif_put(vif);
+			continue;
+		}
+
 		sco = (struct skb_cb_overlay *)skb->cb;
 		sco->meta_slots_used = netbk_gop_skb(skb, &npo);
 
@@ -1864,6 +1870,8 @@
 
 void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
 {
+	vif->mapped = false;
+
 	if (vif->tx.sring)
 		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
 					vif->tx.sring);
@@ -1899,6 +1908,7 @@
 	BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
 
 	vif->rx_req_cons_peek = 0;
+	vif->mapped = true;
 
 	return 0;