Index: sys/netinet/ip_divert.c
===================================================================
--- sys/netinet/ip_divert.c
+++ 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;
Index: sys/netinet/ip_output.c
===================================================================
--- sys/netinet/ip_output.c
+++ sys/netinet/ip_output.c
@@ -735,12 +735,6 @@
 
 	m->m_pkthdr.csum_flags |= CSUM_IP;
 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA & ~ifp->if_hwassist) {
-		m = mb_unmapped_to_ext(m);
-		if (m == NULL) {
-			IPSTAT_INC(ips_odropped);
-			error = ENOBUFS;
-			goto bad;
-		}
 		in_delayed_cksum(m);
 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 	} else if ((ifp->if_capenable & IFCAP_MEXTPG) == 0) {
@@ -894,12 +888,6 @@
 	 * 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;
 	}
Index: sys/netinet6/ip6_output.c
===================================================================
--- sys/netinet6/ip6_output.c
+++ sys/netinet6/ip6_output.c
@@ -221,19 +221,7 @@
 	    "csum_flags %#x frag %d\n",
 	    __func__, __LINE__, plen, optlen, m, ifp, csum_flags, frag));
 
-	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_SCTP_IPV6 | CSUM_DELAY_DATA_IPV6)) != 0) {
 		if (csum_flags & CSUM_DELAY_DATA_IPV6) {
 			in6_delayed_cksum(m, plen - optlen,
 			    sizeof(struct ip6_hdr) + optlen);
@@ -246,6 +234,16 @@
 		}
 #endif
 	}
+	if (!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);
+		}
+	}
 
 	return (0);
 }
Index: sys/netipsec/ipsec_output.c
===================================================================
--- sys/netipsec/ipsec_output.c
+++ 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;
Index: sys/netpfil/ipfw/nat64/nat64_translate.c
===================================================================
--- sys/netpfil/ipfw/nat64/nat64_translate.c
+++ 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;
 	}
Index: sys/netpfil/pf/pf.c
===================================================================
--- sys/netpfil/pf/pf.c
+++ sys/netpfil/pf/pf.c
@@ -5992,9 +5992,6 @@
 	/* 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;
 	}
@@ -6181,9 +6178,6 @@
 	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;
 	}