diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index e9836f611d9c3cdc381b5da0679211cbfb03950f..fd0284c1dc328b92520aa0c39b4ca2a4b9899915 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -1084,6 +1084,7 @@ struct svc_version nfs4_callback_version1 = {
 	.vs_xdrsize = NFS4_CALLBACK_XDRSIZE,
 	.vs_dispatch = NULL,
 	.vs_hidden = true,
+	.vs_need_cong_ctrl = true,
 };
 
 struct svc_version nfs4_callback_version4 = {
@@ -1093,4 +1094,5 @@ struct svc_version nfs4_callback_version4 = {
 	.vs_xdrsize = NFS4_CALLBACK_XDRSIZE,
 	.vs_dispatch = NULL,
 	.vs_hidden = true,
+	.vs_need_cong_ctrl = true,
 };
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 89e582fa58cd1bd187f05fd51caf34703ff1c463..cbeeda1e94a2fbbba61e2adeeb4f9ba89287eaf9 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -2537,12 +2537,13 @@ static struct svc_procedure		nfsd_procedures4[2] = {
 };
 
 struct svc_version	nfsd_version4 = {
-		.vs_vers	= 4,
-		.vs_nproc	= 2,
-		.vs_proc	= nfsd_procedures4,
-		.vs_dispatch	= nfsd_dispatch,
-		.vs_xdrsize	= NFS4_SVC_XDRSIZE,
-		.vs_rpcb_optnl	= true,
+	.vs_vers		= 4,
+	.vs_nproc		= 2,
+	.vs_proc		= nfsd_procedures4,
+	.vs_dispatch		= nfsd_dispatch,
+	.vs_xdrsize		= NFS4_SVC_XDRSIZE,
+	.vs_rpcb_optnl		= true,
+	.vs_need_cong_ctrl	= true,
 };
 
 /*
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 96467c95f02e81cb347ed09f4d97b22472387aa3..e770abeed32d7117c4f2d363f9d7370a60d2c55f 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -406,6 +406,9 @@ struct svc_version {
 	/* Don't care if the rpcbind registration fails */
 	bool			vs_rpcb_optnl;
 
+	/* Need xprt with congestion control */
+	bool			vs_need_cong_ctrl;
+
 	/* Override dispatch function (e.g. when caching replies).
 	 * A return value of 0 means drop the request. 
 	 * vs_dispatch == NULL means use default dispatcher.
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 85bcdea67a3f7ca12bda0c9321c0d44544aa0482..1fc3ff8221689e1c12e33f55dfbe6d56b688c2c1 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1169,6 +1169,21 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 	  !(versp = progp->pg_vers[vers]))
 		goto err_bad_vers;
 
+	/*
+	 * Some protocol versions (namely NFSv4) require some form of
+	 * congestion control.  (See RFC 7530 section 3.1 paragraph 2)
+	 * In other words, UDP is not allowed. We mark those when setting
+	 * up the svc_xprt, and verify that here.
+	 *
+	 * The spec is not very clear about what error should be returned
+	 * when someone tries to access a server that is listening on UDP
+	 * for lower versions. RPC_PROG_MISMATCH seems to be the closest
+	 * fit.
+	 */
+	if (versp->vs_need_cong_ctrl &&
+	    !test_bit(XPT_CONG_CTRL, &rqstp->rq_xprt->xpt_flags))
+		goto err_bad_vers;
+
 	procp = versp->vs_proc + proc;
 	if (proc >= versp->vs_nproc || !procp->pc_func)
 		goto err_bad_proc;