Index: head/sys/dev/netmap/netmap_generic.c
===================================================================
--- head/sys/dev/netmap/netmap_generic.c
+++ head/sys/dev/netmap/netmap_generic.c
@@ -129,8 +129,9 @@
 netmap_get_mbuf(int len)
 {
 	struct mbuf *m;
-	m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR | M_NOFREE);
+	m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
 	if (m) {
+		m->m_flags |= M_NOFREE;	/* XXXNP: Almost certainly incorrect. */
 		m->m_ext.ext_arg1 = m->m_ext.ext_buf; // XXX save
 		m->m_ext.ext_free = (void *)netmap_default_mbuf_destructor;
 		m->m_ext.ext_type = EXT_EXTREF;
Index: head/sys/kern/kern_mbuf.c
===================================================================
--- head/sys/kern/kern_mbuf.c
+++ head/sys/kern/kern_mbuf.c
@@ -424,6 +424,7 @@
 
 	m = (struct mbuf *)mem;
 	flags = args->flags;
+	MPASS((flags & M_NOFREE) == 0);
 
 	error = m_init(m, how, type, flags);
 
@@ -572,6 +573,7 @@
 	args = (struct mb_args *)arg;
 	flags = args->flags;
 	type = args->type;
+	MPASS((flags & M_NOFREE) == 0);
 
 #ifdef INVARIANTS
 	trash_ctor(m->m_ext.ext_buf, MCLBYTES, arg, how);
Index: head/sys/kern/uipc_mbuf.c
===================================================================
--- head/sys/kern/uipc_mbuf.c
+++ head/sys/kern/uipc_mbuf.c
@@ -1670,7 +1670,7 @@
 		 * don't know how to break up the non-contiguous memory when
 		 * doing DMA.
 		 */
-		n = m_getcl(how, m->m_type, m->m_flags);
+		n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS);
 		if (n == NULL) {
 			m_freem(m0);
 			return (NULL);
@@ -1700,7 +1700,7 @@
 				break;
 			off += cc;
 
-			n = m_getcl(how, m->m_type, m->m_flags);
+			n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS);
 			if (n == NULL) {
 				m_freem(mfirst);
 				m_freem(m0);