diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index f251845fe532..5e740c486203 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -327,8 +327,8 @@ struct rxrpc_local {
 	 * packet with a maximum set of jumbo subpackets or a PING ACK padded
 	 * out to 64K with zeropages for PMTUD.
 	 */
-	struct kvec		kvec[RXRPC_MAX_NR_JUMBO > 3 + 16 ?
-				     RXRPC_MAX_NR_JUMBO : 3 + 16];
+	struct kvec		kvec[1 + RXRPC_MAX_NR_JUMBO > 3 + 16 ?
+				     1 + RXRPC_MAX_NR_JUMBO : 3 + 16];
 };
 
 /*
@@ -874,8 +874,7 @@ struct rxrpc_txbuf {
 #define RXRPC_TXBUF_RESENT	0x100		/* Set if has been resent */
 	__be16			cksum;		/* Checksum to go in header */
 	bool			jumboable;	/* Can be non-terminal jumbo subpacket */
-	u8			nr_kvec;	/* Amount of kvec[] used */
-	struct kvec		kvec[1];
+	void			*data;		/* Data with preceding jumbo header */
 };
 
 static inline bool rxrpc_sending_to_server(const struct rxrpc_txbuf *txb)
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 6f7a125d6e90..95905b85a8d7 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -428,13 +428,13 @@ int rxrpc_send_abort_packet(struct rxrpc_call *call)
 static size_t rxrpc_prepare_data_subpacket(struct rxrpc_call *call,
 					   struct rxrpc_send_data_req *req,
 					   struct rxrpc_txbuf *txb,
+					   struct rxrpc_wire_header *whdr,
 					   rxrpc_serial_t serial, int subpkt)
 {
-	struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
-	struct rxrpc_jumbo_header *jumbo = (void *)(whdr + 1) - sizeof(*jumbo);
+	struct rxrpc_jumbo_header *jumbo = txb->data - sizeof(*jumbo);
 	enum rxrpc_req_ack_trace why;
 	struct rxrpc_connection *conn = call->conn;
-	struct kvec *kv = &call->local->kvec[subpkt];
+	struct kvec *kv = &call->local->kvec[1 + subpkt];
 	size_t len = txb->pkt_len;
 	bool last;
 	u8 flags;
@@ -491,18 +491,15 @@ static size_t rxrpc_prepare_data_subpacket(struct rxrpc_call *call,
 	}
 dont_set_request_ack:
 
-	/* The jumbo header overlays the wire header in the txbuf. */
+	/* There's a jumbo header prepended to the data if we need it. */
 	if (subpkt < req->n - 1)
 		flags |= RXRPC_JUMBO_PACKET;
 	else
 		flags &= ~RXRPC_JUMBO_PACKET;
 	if (subpkt == 0) {
 		whdr->flags	= flags;
-		whdr->serial	= htonl(txb->serial);
 		whdr->cksum	= txb->cksum;
-		whdr->serviceId	= htons(conn->service_id);
-		kv->iov_base	= whdr;
-		len += sizeof(*whdr);
+		kv->iov_base	= txb->data;
 	} else {
 		jumbo->flags	= flags;
 		jumbo->pad	= 0;
@@ -535,7 +532,9 @@ static unsigned int rxrpc_prepare_txqueue(struct rxrpc_txqueue *tq,
 /*
  * Prepare a (jumbo) packet for transmission.
  */
-static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_send_data_req *req)
+static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call,
+					struct rxrpc_send_data_req *req,
+					struct rxrpc_wire_header *whdr)
 {
 	struct rxrpc_txqueue *tq = req->tq;
 	rxrpc_serial_t serial;
@@ -549,6 +548,18 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
 	/* Each transmission of a Tx packet needs a new serial number */
 	serial = rxrpc_get_next_serials(call->conn, req->n);
 
+	whdr->epoch		= htonl(call->conn->proto.epoch);
+	whdr->cid		= htonl(call->cid);
+	whdr->callNumber	= htonl(call->call_id);
+	whdr->seq		= htonl(seq);
+	whdr->serial		= htonl(serial);
+	whdr->type		= RXRPC_PACKET_TYPE_DATA;
+	whdr->flags		= 0;
+	whdr->userStatus	= 0;
+	whdr->securityIndex	= call->security_ix;
+	whdr->_rsvd		= 0;
+	whdr->serviceId		= htons(call->conn->service_id);
+
 	call->tx_last_serial = serial + req->n - 1;
 	call->tx_last_sent = req->now;
 	xmit_ts = rxrpc_prepare_txqueue(tq, req);
@@ -576,7 +587,7 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
 		if (i + 1 == req->n)
 			/* Only sample the last subpacket in a jumbo. */
 			__set_bit(ix, &tq->rtt_samples);
-		len += rxrpc_prepare_data_subpacket(call, req, txb, serial, i);
+		len += rxrpc_prepare_data_subpacket(call, req, txb, whdr, serial, i);
 		serial++;
 		seq++;
 		i++;
@@ -618,6 +629,7 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
 	}
 
 	rxrpc_set_keepalive(call, req->now);
+	page_frag_free(whdr);
 	return len;
 }
 
@@ -626,25 +638,33 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
  */
 void rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_send_data_req *req)
 {
+	struct rxrpc_wire_header *whdr;
 	struct rxrpc_connection *conn = call->conn;
 	enum rxrpc_tx_point frag;
 	struct rxrpc_txqueue *tq = req->tq;
 	struct rxrpc_txbuf *txb;
 	struct msghdr msg;
 	rxrpc_seq_t seq = req->seq;
-	size_t len;
+	size_t len = sizeof(*whdr);
 	bool new_call = test_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags);
 	int ret, stat_ix;
 
 	_enter("%x,%x-%x", tq->qbase, seq, seq + req->n - 1);
 
+	whdr = page_frag_alloc(&call->local->tx_alloc, sizeof(*whdr), GFP_NOFS);
+	if (!whdr)
+		return; /* Drop the packet if no memory. */
+
+	call->local->kvec[0].iov_base = whdr;
+	call->local->kvec[0].iov_len = sizeof(*whdr);
+
 	stat_ix = umin(req->n, ARRAY_SIZE(call->rxnet->stat_tx_jumbo)) - 1;
 	atomic_inc(&call->rxnet->stat_tx_jumbo[stat_ix]);
 
-	len = rxrpc_prepare_data_packet(call, req);
+	len += rxrpc_prepare_data_packet(call, req, whdr);
 	txb = tq->bufs[seq & RXRPC_TXQ_MASK];
 
-	iov_iter_kvec(&msg.msg_iter, WRITE, call->local->kvec, req->n, len);
+	iov_iter_kvec(&msg.msg_iter, WRITE, call->local->kvec, 1 + req->n, len);
 
 	msg.msg_name	= &call->peer->srx.transport;
 	msg.msg_namelen	= call->peer->srx.transport_len;
@@ -695,13 +715,13 @@ void rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_send_data_req
 
 	if (ret == -EMSGSIZE) {
 		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_msgsize);
-		trace_rxrpc_tx_packet(call->debug_id, call->local->kvec[0].iov_base, frag);
+		trace_rxrpc_tx_packet(call->debug_id, whdr, frag);
 		ret = 0;
 	} else if (ret < 0) {
 		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail);
 		trace_rxrpc_tx_fail(call->debug_id, txb->serial, ret, frag);
 	} else {
-		trace_rxrpc_tx_packet(call->debug_id, call->local->kvec[0].iov_base, frag);
+		trace_rxrpc_tx_packet(call->debug_id, whdr, frag);
 	}
 
 	rxrpc_tx_backoff(call, ret);
diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index 62b09d23ec08..6cb37b0eb77f 100644
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -257,8 +257,7 @@ static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
 				    struct rxrpc_txbuf *txb,
 				    struct skcipher_request *req)
 {
-	struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
-	struct rxkad_level1_hdr *hdr = (void *)(whdr + 1);
+	struct rxkad_level1_hdr *hdr = txb->data;
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
 	size_t pad;
@@ -274,7 +273,7 @@ static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
 	pad = RXKAD_ALIGN - pad;
 	pad &= RXKAD_ALIGN - 1;
 	if (pad) {
-		memset(txb->kvec[0].iov_base + txb->offset, 0, pad);
+		memset(txb->data + txb->offset, 0, pad);
 		txb->pkt_len += pad;
 	}
 
@@ -300,8 +299,7 @@ static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
 				       struct skcipher_request *req)
 {
 	const struct rxrpc_key_token *token;
-	struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
-	struct rxkad_level2_hdr *rxkhdr = (void *)(whdr + 1);
+	struct rxkad_level2_hdr *rxkhdr = txb->data;
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
 	size_t content, pad;
@@ -319,7 +317,7 @@ static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
 	txb->pkt_len = round_up(content, RXKAD_ALIGN);
 	pad = txb->pkt_len - content;
 	if (pad)
-		memset(txb->kvec[0].iov_base + txb->offset, 0, pad);
+		memset(txb->data + txb->offset, 0, pad);
 
 	/* encrypt from the session key */
 	token = call->conn->key->payload.data[0];
@@ -407,9 +405,8 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 
 	/* Clear excess space in the packet */
 	if (txb->pkt_len < txb->alloc_size) {
-		struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
 		size_t gap = txb->alloc_size - txb->pkt_len;
-		void *p = whdr + 1;
+		void *p = txb->data;
 
 		memset(p + txb->pkt_len, 0, gap);
 	}
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 584397aba4a0..84dc6c94f23b 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -419,7 +419,7 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 			size_t copy = umin(txb->space, msg_data_left(msg));
 
 			_debug("add %zu", copy);
-			if (!copy_from_iter_full(txb->kvec[0].iov_base + txb->offset,
+			if (!copy_from_iter_full(txb->data + txb->offset,
 						 copy, &msg->msg_iter))
 				goto efault;
 			_debug("added");
@@ -445,8 +445,6 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 			ret = call->security->secure_packet(call, txb);
 			if (ret < 0)
 				goto out;
-
-			txb->kvec[0].iov_len += txb->len;
 			rxrpc_queue_packet(rx, call, txb, notify_end_tx);
 			txb = NULL;
 		}
diff --git a/net/rxrpc/txbuf.c b/net/rxrpc/txbuf.c
index 131d9e55c8e9..2bc455705632 100644
--- a/net/rxrpc/txbuf.c
+++ b/net/rxrpc/txbuf.c
@@ -19,17 +19,19 @@ atomic_t rxrpc_nr_txbuf;
 struct rxrpc_txbuf *rxrpc_alloc_data_txbuf(struct rxrpc_call *call, size_t data_size,
 					   size_t data_align, gfp_t gfp)
 {
-	struct rxrpc_wire_header *whdr;
 	struct rxrpc_txbuf *txb;
-	size_t total, hoff;
+	size_t total, doff, jsize = sizeof(struct rxrpc_jumbo_header);
 	void *buf;
 
 	txb = kzalloc(sizeof(*txb), gfp);
 	if (!txb)
 		return NULL;
 
-	hoff = round_up(sizeof(*whdr), data_align) - sizeof(*whdr);
-	total = hoff + sizeof(*whdr) + data_size;
+	/* We put a jumbo header in the buffer, but not a full wire header to
+	 * avoid delayed-corruption problems with zerocopy.
+	 */
+	doff = round_up(jsize, data_align);
+	total = doff + data_size;
 
 	data_align = umax(data_align, L1_CACHE_BYTES);
 	mutex_lock(&call->conn->tx_data_alloc_lock);
@@ -41,30 +43,15 @@ struct rxrpc_txbuf *rxrpc_alloc_data_txbuf(struct rxrpc_call *call, size_t data_
 		return NULL;
 	}
 
-	whdr = buf + hoff;
-
 	refcount_set(&txb->ref, 1);
 	txb->call_debug_id	= call->debug_id;
 	txb->debug_id		= atomic_inc_return(&rxrpc_txbuf_debug_ids);
 	txb->alloc_size		= data_size;
 	txb->space		= data_size;
-	txb->offset		= sizeof(*whdr);
+	txb->offset		= 0;
 	txb->flags		= call->conn->out_clientflag;
 	txb->seq		= call->send_top + 1;
-	txb->nr_kvec		= 1;
-	txb->kvec[0].iov_base	= whdr;
-	txb->kvec[0].iov_len	= sizeof(*whdr);
-
-	whdr->epoch		= htonl(call->conn->proto.epoch);
-	whdr->cid		= htonl(call->cid);
-	whdr->callNumber	= htonl(call->call_id);
-	whdr->seq		= htonl(txb->seq);
-	whdr->type		= RXRPC_PACKET_TYPE_DATA;
-	whdr->flags		= 0;
-	whdr->userStatus	= 0;
-	whdr->securityIndex	= call->security_ix;
-	whdr->_rsvd		= 0;
-	whdr->serviceId		= htons(call->dest_srx.srx_service);
+	txb->data		= buf + doff;
 
 	trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, 1,
 			  rxrpc_txbuf_alloc_data);
@@ -94,10 +81,8 @@ static void rxrpc_free_txbuf(struct rxrpc_txbuf *txb)
 
 	trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, 0,
 			  rxrpc_txbuf_free);
-	for (i = 0; i < txb->nr_kvec; i++)
-		if (txb->kvec[i].iov_base &&
-		    !is_zero_pfn(page_to_pfn(virt_to_page(txb->kvec[i].iov_base))))
-			page_frag_free(txb->kvec[i].iov_base);
+	if (txb->data)
+		page_frag_free(txb->data);
 	kfree(txb);
 	atomic_dec(&rxrpc_nr_txbuf);
 }
