Re: [PATCH 3/3] maple_tree: assert retrieving new value on a tree with only root node

Liam R. Howlett
2025-02-10T14:19:21Z

* Wei Yang <richard.weiyang@gmail.com> [250207 20:26]:
> Original code may get a stall value when overwriting the whole range on a
^^^^^- stale value. I thought you were saying
it was stalling which did not make sense.

> maple tree with only root node. The reason is we didn't set the only
> root node dead during destroy.
>
> Add a test case to verify this is not recreated.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> CC: Liam R. Howlett <Liam.Howlett@Oracle.com>
> ---
> tools/testing/radix-tree/maple.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
> index bc30050227fd..1e293e4d856d 100644
> --- a/tools/testing/radix-tree/maple.c
> +++ b/tools/testing/radix-tree/maple.c
> @@ -35256,6 +35256,30 @@ static noinline void __init check_rcu_simulated(struct maple_tree *mt)
> MT_BUG_ON(mt, mas_prev(&mas_reader, 0) != xa_mk_value(val));
> rcu_read_unlock();
>
> + /* Clear out tree & create one with only root node */
> + mas_lock(&mas_writer);
> + mas_set_range(&mas_writer, 0, ULONG_MAX);
> + mas_store_gfp(&mas_writer, NULL, GFP_KERNEL);
> + mas_set_range(&mas_writer, 0, 0);
> + for (i = 0; i <= 5; i++) {
> + mas_writer.index = i * 10;
> + mas_writer.last = i * 10 + 5;
> + mas_store_gfp(&mas_writer, xa_mk_value(i), GFP_KERNEL);
> + }
> + mas_unlock(&mas_writer);
> + target = 10;
> + mas_set_range(&mas_reader, target, target);
> + rcu_read_lock();
> + MT_BUG_ON(mt, mas_walk(&mas_reader) != xa_mk_value(target/10));
> +
> + /* Overwrite the whole range */
> + mas_lock(&mas_writer);
> + mas_set_range(&mas_writer, 0, ULONG_MAX);
> + mas_store_gfp(&mas_writer, xa_mk_value(val), GFP_KERNEL);
> + mas_unlock(&mas_writer);
> + MT_BUG_ON(mt, mas_walk(&mas_reader) != xa_mk_value(val));
> + rcu_read_unlock();
> +
> rcu_unregister_thread();
> }
>
> --
> 2.34.1
>