diff --git a/sys/netinet/igmp.c b/sys/netinet/igmp.c
--- a/sys/netinet/igmp.c
+++ b/sys/netinet/igmp.c
@@ -1471,6 +1471,7 @@
 	m = *mp;
 	ifp = m->m_pkthdr.rcvif;
 	*mp = NULL;
+	M_ASSERTMAPPED(m);
 
 	IGMPSTAT_INC(igps_rcv_total);
 
diff --git a/sys/netinet/ip_mroute.c b/sys/netinet/ip_mroute.c
--- a/sys/netinet/ip_mroute.c
+++ b/sys/netinet/ip_mroute.c
@@ -1311,6 +1311,8 @@
 	u_long hash;
 	int hlen;
 
+	M_ASSERTMAPPED(m);
+
 	CTR3(KTR_IPMF, "ip_mforward: delete mfc orig 0x%08x group %lx ifp %p",
 	    ntohl(ip->ip_src.s_addr), (u_long)ntohl(ip->ip_dst.s_addr), ifp);
 
@@ -1562,6 +1564,7 @@
 	vifi_t vifi;
 	int plen = ntohs(ip->ip_len);
 
+	M_ASSERTMAPPED(m);
 	MRW_LOCK_ASSERT();
 	NET_EPOCH_ASSERT();
 
@@ -1745,6 +1748,7 @@
 	int hlen = ip->ip_hl << 2;
 
 	MRW_LOCK_ASSERT();
+	M_ASSERTMAPPED(m);
 
 	/*
 	 * Make a new reference to the packet; make sure that
diff --git a/sys/netinet/ip_options.c b/sys/netinet/ip_options.c
--- a/sys/netinet/ip_options.c
+++ b/sys/netinet/ip_options.c
@@ -514,6 +514,8 @@
 		*phlen = 0;
 		return (m);		/* XXX should fail */
 	}
+	KASSERT((m->m_flags & M_EXTPG) == 0, ("%s: mbuf %p is unmapped",
+	    __func__, m));
 	if (p->ipopt_dst.s_addr)
 		ip->ip_dst = p->ipopt_dst;
 	if (!M_WRITABLE(m) || M_LEADINGSPACE(m) < optlen) {
diff --git a/sys/netinet6/ip6_mroute.c b/sys/netinet6/ip6_mroute.c
--- a/sys/netinet6/ip6_mroute.c
+++ b/sys/netinet6/ip6_mroute.c
@@ -1073,6 +1073,7 @@
 	GET_TIME(tp);
 #endif /* UPCALL_TIMING */
 
+	M_ASSERTMAPPED(m);
 	MRT6_DLOG(DEBUG_FORWARD, "src %s, dst %s, ifindex %d",
 	    ip6_sprintf(ip6bufs, &ip6->ip6_src),
 	    ip6_sprintf(ip6bufd, &ip6->ip6_dst), ifp->if_index);
@@ -1364,6 +1365,8 @@
 	u_int32_t iszone, idzone, oszone, odzone;
 	int error = 0;
 
+	M_ASSERTMAPPED(m);
+
 	/*
 	 * Don't forward if it didn't arrive from the parent mif
 	 * for its origin.
@@ -1527,6 +1530,8 @@
 	int error __unused = 0;
 	u_long linkmtu;
 
+	M_ASSERTMAPPED(m);
+
 	/*
 	 * Make a new reference to the packet; make sure that
 	 * the IPv6 header is actually copied, not just referenced,