diff --git a/include/linux/security.h b/include/linux/security.h
index 466cbad..3696ca3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -978,6 +978,7 @@
  *	Check permissions on incoming network packets.  This hook is distinct
  *	from Netfilter's IP input hooks since it is the first time that the
  *	incoming sk_buff @skb has been associated with a particular socket, @sk.
+ *	Must not sleep inside this hook because some callers hold spinlocks.
  *	@sk contains the sock (not socket) associated with the incoming sk_buff.
  *	@skb contains the incoming network data.
  * @socket_getpeersec_stream: