Well, actually, I discovered this when I was playing with implementing a lock free queue in shared memory. I was using singly linked lists; one for the queue an

Well, actually, I discovered this when I was playing with implementing a lock free queue in shared memory. I was using singly linked lists; one for the queue and one for the free list. A node would sometimes come back to the queue's head from the free list and mess things up. It's not surprising that this is well known, but I learnt it by doing. :)