In my understanding, the head initialised using LIST_HEAD_INIT or defined by LIST_HEAD corresponds to no *real* data field. But it *does* have its own _next_ and _prev_ pointers. The _next_ pointer points to the first real node in the doubly linked list, and the _prev_ pointer points to the last real node.
I'm wondering if the picture shown at the very bottom of http://kernelnewbies.org/FAQ/LinkedLists is wrong about this. Because I believe head's _prev_ should point to the last node, which is at the very right. And the last node's _next_ should point to the head. Just as shown like the red line.