diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index aefcd7a..0e950fd 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -30,6 +30,20 @@
 
 #define INITIAL_NET_GEN_PTRS	13 /* +1 for len +2 for rcu_head */
 
+static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
+
+static struct net_generic *net_alloc_generic(void)
+{
+	struct net_generic *ng;
+	size_t generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
+
+	ng = kzalloc(generic_size, GFP_KERNEL);
+	if (ng)
+		ng->len = max_gen_ptrs;
+
+	return ng;
+}
+
 static int net_assign_generic(struct net *net, int id, void *data)
 {
 	struct net_generic *ng, *old_ng;
@@ -43,8 +57,7 @@
 	if (old_ng->len >= id)
 		goto assign;
 
-	ng = kzalloc(sizeof(struct net_generic) +
-			id * sizeof(void *), GFP_KERNEL);
+	ng = net_alloc_generic();
 	if (ng == NULL)
 		return -ENOMEM;
 
@@ -59,7 +72,6 @@
 	 * the old copy for kfree after a grace period.
 	 */
 
-	ng->len = id;
 	memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));
 
 	rcu_assign_pointer(net->gen, ng);
@@ -161,18 +173,6 @@
 	goto out;
 }
 
-static struct net_generic *net_alloc_generic(void)
-{
-	struct net_generic *ng;
-	size_t generic_size = sizeof(struct net_generic) +
-		INITIAL_NET_GEN_PTRS * sizeof(void *);
-
-	ng = kzalloc(generic_size, GFP_KERNEL);
-	if (ng)
-		ng->len = INITIAL_NET_GEN_PTRS;
-
-	return ng;
-}
 
 #ifdef CONFIG_NET_NS
 static struct kmem_cache *net_cachep;
@@ -483,6 +483,7 @@
 			}
 			return error;
 		}
+		max_gen_ptrs = max_t(unsigned int, max_gen_ptrs, *ops->id);
 	}
 	error = __register_pernet_operations(list, ops);
 	if (error) {