[IPV4]: Handle kmem_cache_create() failure in ipmr.c

net/ipv4/ipmr.c

@@ -1892,6 +1892,9 @@ void __init ip_mr_init(void)
 				       sizeof(struct mfc_cache),
 				       0, SLAB_HWCACHE_ALIGN,
 				       NULL, NULL);
+	if (!mrt_cachep)
+		panic("cannot allocate ip_mrt_cache");
+
 	init_timer(&ipmr_expire_timer);
 	ipmr_expire_timer.function=ipmr_expire_process;
 	register_netdevice_notifier(&ip_mr_notifier);