Index: head/sys/net/netmap_user.h
===================================================================
--- head/sys/net/netmap_user.h
+++ head/sys/net/netmap_user.h
@@ -981,7 +981,8 @@
 static int
 nm_mmap(struct nm_desc *d, const struct nm_desc *parent)
 {
-	//XXX TODO: check if mmap is already done
+	if (d->done_mmap)
+		goto done_mmap;
 
 	if (IS_NETMAP_DESC(parent) && parent->mem &&
 	    parent->req.nr_arg2 == d->req.nr_arg2) {
@@ -999,6 +1000,7 @@
 		}
 		d->done_mmap = 1;
 	}
+done_mmap:
 	{
 		struct netmap_if *nifp = NETMAP_IF(d->mem, d->req.nr_offset);
 		struct netmap_ring *r = NETMAP_RXRING(nifp, d->first_rx_ring);