diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 871c73c92165..29b4ba93ab3c 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1287,7 +1287,7 @@ static bool use_gss_proxy(struct net *net)
 
 #ifdef CONFIG_PROC_FS
 
-static bool set_gss_proxy(struct net *net, int type)
+static int set_gss_proxy(struct net *net, int type)
 {
 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
 	int ret = 0;
@@ -1317,10 +1317,12 @@ static inline bool gssp_ready(struct sunrpc_net *sn)
 	return false;
 }
 
-static int wait_for_gss_proxy(struct net *net)
+static int wait_for_gss_proxy(struct net *net, struct file *file)
 {
 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
 
+	if (file->f_flags & O_NONBLOCK && !gssp_ready(sn))
+		return -EAGAIN;
 	return wait_event_interruptible(sn->gssp_wq, gssp_ready(sn));
 }
 
@@ -1362,7 +1364,7 @@ static ssize_t read_gssp(struct file *file, char __user *buf,
 	size_t len;
 	int ret;
 
-	ret = wait_for_gss_proxy(net);
+	ret = wait_for_gss_proxy(net, file);
 	if (ret)
 		return ret;
 
diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index c3f9e1ef7f53..06bdf5a1082c 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -810,11 +810,15 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp)
 		goto badcred;
 	argv->iov_base = (void*)((__be32*)argv->iov_base + slen);	/* skip machname */
 	argv->iov_len -= slen*4;
-
+	/*
+	 * Note: we skip uid_valid()/gid_valid() checks here for
+	 * backwards compatibility with clients that use -1 id's.
+	 * Instead, -1 uid or gid is later mapped to the
+	 * (export-specific) anonymous id by nfsd_setuser.
+	 * Supplementary gid's will be left alone.
+	 */
 	cred->cr_uid = make_kuid(&init_user_ns, svc_getnl(argv)); /* uid */
 	cred->cr_gid = make_kgid(&init_user_ns, svc_getnl(argv)); /* gid */
-	if (!uid_valid(cred->cr_uid) || !gid_valid(cred->cr_gid))
-		goto badcred;
 	slen = svc_getnl(argv);			/* gids length */
 	if (slen > 16 || (len -= (slen + 2)*4) < 0)
 		goto badcred;
@@ -823,8 +827,6 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp)
 		return SVC_CLOSE;
 	for (i = 0; i < slen; i++) {
 		kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv));
-		if (!gid_valid(kgid))
-			goto badcred;
 		GROUP_AT(cred->cr_group_info, i) = kgid;
 	}
 	if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) {