Re: [patch] radix-tree: fix small lockless radix-tree bug

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 13 Jun 2008 05:03:45 +1000
Nick Piggin <nickpiggin@yahoo.com.au> wrote:

> @@ -124,6 +175,17 @@ static void radix_tree_node_rcu_free(str
>  {
>  	struct radix_tree_node *node =
>  			container_of(head, struct radix_tree_node, rcu_head);
> +
> +	/*
> +	 * must only free zeroed nodes into the slab. radix_tree_shrink
> +	 * can leave us with a non-NULL entry in the first slot, so clear
> +	 * that here to make sure.
> +	 */
> +	tag_clear(node, 0, 0);
> +	tag_clear(node, 1, 0);
> +	node->slots[0] = NULL;
> +	node->count = 0;
> +
>  	kmem_cache_free(radix_tree_node_cachep, node);
>  }

oic, that stuff got moved from the synchronous case into the RCU callback
case.