commit 9e3ddb21568284fb9061a91bbd3158909b1dec45
Author: Paul Wouters <pwouters@redhat.com>
Date:   Sun Sep 1 15:18:37 2013 -0400

    * Fix for loading non-namespace aware ipv4 protocols without
      CONFIG_NAMESPACES set. IPv6 does not have this check.

diff --git a/net/ipv4/protocol.c b/net/ipv4/protocol.c
index ce84846..b5f785c 100644
--- a/net/ipv4/protocol.c
+++ b/net/ipv4/protocol.c
@@ -37,11 +37,13 @@ const struct net_offload __rcu *inet_offloads[MAX_INET_PROTOS] __read_mostly;
 
 int inet_add_protocol(const struct net_protocol *prot, unsigned char protocol)
 {
+#ifdef CONFIG_NAMESPACES
 	if (!prot->netns_ok) {
 		pr_err("Protocol %u is not namespace aware, cannot register.\n",
 			protocol);
 		return -EINVAL;
 	}
+#endif
 
 	return !cmpxchg((const struct net_protocol **)&inet_protos[protocol],
 			NULL, prot) ? 0 : -1;