diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 2617320efa95..d6997aec45dd 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -154,6 +154,7 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 #endif
 	dev->last_rx = jiffies;
 
+	/* it's OK to use per_cpu_ptr() because BHs are off */
 	pcpu_lstats = netdev_priv(dev);
 	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
 	lb_stats->bytes += skb->len;
@@ -221,7 +222,8 @@ static void loopback_dev_free(struct net_device *dev)
 }
 
 /*
- * The loopback device is special. There is only one instance.
+ * The loopback device is special. There is only one instance
+ * per network namespace.
  */
 static void loopback_setup(struct net_device *dev)
 {