radix-tree: move rcu_head into a union with private_list

I want to be able to reference node->parent after freeing node.

Currently node->parent is in a union with rcu_head, so it is overwritten
when the node is put on the RCU list.  We know that private_list is not
referenced after the node is freed, so it is safe for these two members
to share space.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox <[email protected]>
Tested-by: Kirill A. Shutemov <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Matthew Wilcox 2016-12-14 15:08:34 -08:00 • committed by Linus Torvalds
commit 91d9c05ac6
2 changed files with 5 additions and 10 deletions

View file

@ -325,6 +325,7 @@ static void radix_tree_node_rcu_free(struct rcu_head *head)
tag_clear(node, i, 0);
node->slots[0] = NULL;
INIT_LIST_HEAD(&node->private_list);
kmem_cache_free(radix_tree_node_cachep, node);
}