diff -r 4ea51bc8a05d -r cb55beae65e9 sys/dev/cxgbe/adapter.h
--- a/sys/dev/cxgbe/adapter.h	Mon Jun 29 18:06:47 2015 -0700
+++ b/sys/dev/cxgbe/adapter.h	Thu Jul 02 14:57:05 2015 -0700
@@ -323,9 +323,29 @@ struct tx_desc {
 	__be64 flit[8];
 };
 
+#if 1
+/* Copied from struct mbuf in mbuf.h */
+struct m_hdr {
+	struct mbuf		*m_next;
+	struct mbuf		*m_nextpkt;
+	caddr_t		 m_data;	/* location of data */
+	int32_t		 m_len;		/* amount of data in this mbuf */
+	uint32_t	 m_type:8,	/* type of data in this mbuf */
+			 m_flags:24;	/* flags; see below */
+};
+
+struct tx_mbuf {
+	struct mbuf *m;
+	struct m_hdr m_hdr;
+};
+#endif
+
 struct tx_sdesc {
 	struct mbuf *m;		/* m_nextpkt linked chain of frames */
 	uint8_t desc_used;	/* # of hardware descriptors used by the WR */
+#if 1
+	struct tx_mbuf tx_mbuf_list[4];
+#endif
 };
 
 
diff -r 4ea51bc8a05d -r cb55beae65e9 sys/dev/cxgbe/t4_sge.c
--- a/sys/dev/cxgbe/t4_sge.c	Mon Jun 29 18:06:47 2015 -0700
+++ b/sys/dev/cxgbe/t4_sge.c	Thu Jul 02 14:57:05 2015 -0700
@@ -4060,6 +4060,22 @@ write_txpkt_wr(struct sge_txq *txq, stru
 	txsd = &txq->sdesc[eq->pidx];
 	txsd->m = m0;
 	txsd->desc_used = ndesc;
+#if 1
+	do {
+		struct mbuf *m;
+		int i;
+
+		m = m0;
+		for (i = 0; i < nitems(txsd->tx_mbuf_list); i++) {
+			txsd->tx_mbuf_list[i].m = m;
+			if (m == NULL)
+				break;
+			bcopy(m, &txsd->tx_mbuf_list[i].m_hdr,
+			    sizeof(struct m_hdr));
+			m = m->m_next;
+		}
+	} while (0);
+#endif
 
 	return (ndesc);
 }
@@ -4240,6 +4256,23 @@ write_txpkts_wr(struct sge_txq *txq, str
 	txsd = &txq->sdesc[eq->pidx];
 	txsd->m = m0;
 	txsd->desc_used = ndesc;
+#if 1
+	do {
+		struct mbuf *m;
+		int i;
+
+		/* Yes, only first frame of a compound WR is saved here. */
+		m = m0;
+		for (i = 0; i < nitems(txsd->tx_mbuf_list); i++) {
+			txsd->tx_mbuf_list[i].m = m;
+			if (m == NULL)
+				break;
+			bcopy(m, &txsd->tx_mbuf_list[i].m_hdr,
+			    sizeof(struct m_hdr));
+			m = m->m_next;
+		}
+	} while (0);
+#endif
 
 	return (ndesc);
 }
@@ -4459,7 +4492,17 @@ reclaim_tx_descs(struct sge_txq *txq, u_
 		for (m = txsd->m; m != NULL; m = nextpkt) {
 			nextpkt = m->m_nextpkt;
 			m->m_nextpkt = NULL;
+#if 1
+			do {
+				if (*(uint32_t *)m == 0xdeadc0de) {
+					panic("%s: mbuf %p at txsd %p freed.",
+					    __func__, m, txsd);
+				}
+				m = m_free(m);
+			} while (m != NULL);
+#else
 			m_freem(m);
+#endif
 		}
 		reclaimed += ndesc;
 		can_reclaim -= ndesc;