diff --git a/sys/netinet/ip_divert.c b/sys/netinet/ip_divert.c
--- a/sys/netinet/ip_divert.c
+++ b/sys/netinet/ip_divert.c
@@ -212,9 +212,6 @@
 
 	/* Delayed checksums are currently not compatible with divert. */
 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL)
-			return;
 		in_delayed_cksum(m);
 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 	}
@@ -226,9 +223,6 @@
 #endif
 #ifdef INET6
 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL)
-			return;
 		in6_delayed_cksum(m, m->m_pkthdr.len -
 		    sizeof(struct ip6_hdr), sizeof(struct ip6_hdr));
 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -733,23 +733,20 @@
 		}
 	}
 
-	m->m_pkthdr.csum_flags |= CSUM_IP;
-	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA & ~ifp->if_hwassist) {
+	/* Ensure the packet data is mapped if the interface requires it. */
+	if ((ifp->if_capenable & IFCAP_MEXTPG) == 0) {
 		m = mb_unmapped_to_ext(m);
 		if (m == NULL) {
 			IPSTAT_INC(ips_odropped);
 			error = ENOBUFS;
 			goto bad;
 		}
+	}
+
+	m->m_pkthdr.csum_flags |= CSUM_IP;
+	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA & ~ifp->if_hwassist) {
 		in_delayed_cksum(m);
 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
-	} else if ((ifp->if_capenable & IFCAP_MEXTPG) == 0) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL) {
-			IPSTAT_INC(ips_odropped);
-			error = ENOBUFS;
-			goto bad;
-		}
 	}
 #if defined(SCTP) || defined(SCTP_SUPPORT)
 	if (m->m_pkthdr.csum_flags & CSUM_SCTP & ~ifp->if_hwassist) {
@@ -894,12 +891,6 @@
 	 * fragmented packets, then do it here.
 	 */
 	if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-		m0 = mb_unmapped_to_ext(m0);
-		if (m0 == NULL) {
-			error = ENOBUFS;
-			IPSTAT_INC(ips_odropped);
-			goto done;
-		}
 		in_delayed_cksum(m0);
 		m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 	}
diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -212,42 +212,26 @@
 		*(u_short *)mtodo(m, offset) = csum;
 }
 
-static int
+static void
 ip6_output_delayed_csum(struct mbuf *m, struct ifnet *ifp, int csum_flags,
-    int plen, int optlen, bool frag)
+    int plen, int optlen)
 {
 
 	KASSERT((plen >= optlen), ("%s:%d: plen %d < optlen %d, m %p, ifp %p "
-	    "csum_flags %#x frag %d\n",
-	    __func__, __LINE__, plen, optlen, m, ifp, csum_flags, frag));
+	    "csum_flags %#x",
+	    __func__, __LINE__, plen, optlen, m, ifp, csum_flags));
 
-	if ((csum_flags & CSUM_DELAY_DATA_IPV6) ||
-#if defined(SCTP) || defined(SCTP_SUPPORT)
-	    (csum_flags & CSUM_SCTP_IPV6) ||
-#endif
-	    (!frag && (ifp->if_capenable & IFCAP_MEXTPG) == 0)) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL) {
-			if (frag)
-				in6_ifstat_inc(ifp, ifs6_out_fragfail);
-			else
-				IP6STAT_INC(ip6s_odropped);
-			return (ENOBUFS);
-		}
-		if (csum_flags & CSUM_DELAY_DATA_IPV6) {
-			in6_delayed_cksum(m, plen - optlen,
-			    sizeof(struct ip6_hdr) + optlen);
-			m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
-		}
+	if (csum_flags & CSUM_DELAY_DATA_IPV6) {
+		in6_delayed_cksum(m, plen - optlen,
+		    sizeof(struct ip6_hdr) + optlen);
+		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
+	}
 #if defined(SCTP) || defined(SCTP_SUPPORT)
-		if (csum_flags & CSUM_SCTP_IPV6) {
-			sctp_delayed_cksum(m, sizeof(struct ip6_hdr) + optlen);
-			m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
-		}
-#endif
+	if (csum_flags & CSUM_SCTP_IPV6) {
+		sctp_delayed_cksum(m, sizeof(struct ip6_hdr) + optlen);
+		m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
 	}
-
-	return (0);
+#endif
 }
 
 int
@@ -1104,6 +1088,16 @@
 passout:
 	if (vlan_pcp > -1)
 		EVL_APPLY_PRI(m, vlan_pcp);
+
+	/* Ensure the packet data is mapped if the interface requires it. */
+	if ((ifp->if_capenable & IFCAP_MEXTPG) == 0) {
+		m = mb_unmapped_to_ext(m);
+		if (m == NULL) {
+			IP6STAT_INC(ip6s_odropped);
+			return (ENOBUFS);
+		}
+	}
+
 	/*
 	 * Send the packet to the outgoing interface.
 	 * If necessary, do IPv6 fragmentation before sending.
@@ -1136,9 +1130,7 @@
 	 * XXX-BZ  Need a framework to know when the NIC can handle it, even
 	 * with ext. hdrs.
 	 */
-	error = ip6_output_delayed_csum(m, ifp, sw_csum, plen, optlen, false);
-	if (error != 0)
-		goto bad;
+	ip6_output_delayed_csum(m, ifp, sw_csum, plen, optlen);
 	/* XXX-BZ m->m_pkthdr.csum_flags &= ~ifp->if_hwassist; */
 	tlen = m->m_pkthdr.len;
 
@@ -1217,10 +1209,8 @@
 		 * fragmented packets, then do it here.
 		 * XXX-BZ handle the hw offloading case.  Need flags.
 		 */
-		error = ip6_output_delayed_csum(m, ifp, m->m_pkthdr.csum_flags,
-		    plen, optlen, true);
-		if (error != 0)
-			goto bad;
+		ip6_output_delayed_csum(m, ifp, m->m_pkthdr.csum_flags, plen,
+		    optlen);
 
 		/*
 		 * Change the next header field of the last header in the
diff --git a/sys/netipsec/ipsec_output.c b/sys/netipsec/ipsec_output.c
--- a/sys/netipsec/ipsec_output.c
+++ b/sys/netipsec/ipsec_output.c
@@ -398,12 +398,6 @@
 		 * this is done in the normal processing path.
 		 */
 		if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-			m = mb_unmapped_to_ext(m);
-			if (m == NULL) {
-				IPSECSTAT_INC(ips_out_nomem);
-				key_freesp(&sp);
-				return (ENOBUFS);
-			}
 			in_delayed_cksum(m);
 			m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 		}
@@ -773,12 +767,6 @@
 		 * this is done in the normal processing path.
 		 */
 		if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
-			m = mb_unmapped_to_ext(m);
-			if (m == NULL) {
-				IPSEC6STAT_INC(ips_out_nomem);
-				key_freesp(&sp);
-				return (ENOBUFS);
-			}
 			in6_delayed_cksum(m, m->m_pkthdr.len -
 			    sizeof(struct ip6_hdr), sizeof(struct ip6_hdr));
 			m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
diff --git a/sys/netpfil/ipfw/nat64/nat64_translate.c b/sys/netpfil/ipfw/nat64/nat64_translate.c
--- a/sys/netpfil/ipfw/nat64/nat64_translate.c
+++ b/sys/netpfil/ipfw/nat64/nat64_translate.c
@@ -1292,11 +1292,6 @@
 
 	/* Handle delayed checksums if needed. */
 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL) {
-			NAT64STAT_INC(&cfg->stats, nomem);
-			return (NAT64RETURN);
-		}
 		in_delayed_cksum(m);
 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 	}
@@ -1674,11 +1669,6 @@
 
 	/* Handle delayed checksums if needed. */
 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL) {
-			NAT64STAT_INC(&cfg->stats, nomem);
-			return (NAT64RETURN);
-		}
 		in6_delayed_cksum(m, plen, hlen);
 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
 	}
diff --git a/sys/netpfil/pf/pf.c b/sys/netpfil/pf/pf.c
--- a/sys/netpfil/pf/pf.c
+++ b/sys/netpfil/pf/pf.c
@@ -5989,9 +5989,6 @@
 	/* Copied from FreeBSD 10.0-CURRENT ip_output. */
 	m0->m_pkthdr.csum_flags |= CSUM_IP;
 	if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA & ~ifp->if_hwassist) {
-		m0 = mb_unmapped_to_ext(m0);
-		if (m0 == NULL)
-			goto done;
 		in_delayed_cksum(m0);
 		m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 	}
@@ -6178,9 +6175,6 @@
 	if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6 &
 	    ~ifp->if_hwassist) {
 		uint32_t plen = m0->m_pkthdr.len - sizeof(*ip6);
-		m0 = mb_unmapped_to_ext(m0);
-		if (m0 == NULL)
-			goto done;
 		in6_delayed_cksum(m0, plen, sizeof(struct ip6_hdr));
 		m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
 	}