Re: [PATCH v5 5/5] maple_tree: add a test checking storing null

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

On Thu, 31 Oct 2024 23:16:27 +0000 Wei Yang <richard.weiyang@gmail.com> wrote:

> Add a test to assert that, when storing null to am empty tree or a
> single entry tree it will not result into:
> 
>   * a root node with range [0, ULONG_MAX] set to NULL
>   * a root node with consecutive slot set to NULL
> 

I don't get it.

> --- a/lib/test_maple_tree.c
> +++ b/lib/test_maple_tree.c
> @@ -1387,6 +1387,92 @@ static noinline void __init check_prev_entry(struct maple_tree *mt)
>  	mas_unlock(&mas);
>  }
>  
> +static noinline void __init check_store_null(struct maple_tree *mt)
> +{
> +	MA_STATE(mas, mt, 0, ULONG_MAX);
> +
>
> ...
>
> +	MT_BUG_ON(mt, !xa_is_node(mas_root(&mas)));
> ...
>

mas_root() is private to lib/maple_tree.c.  I'll do this for now:

--- a/lib/test_maple_tree.c~maple_tree-add-a-test-checking-storing-null-fix
+++ a/lib/test_maple_tree.c
@@ -1453,7 +1453,7 @@ static noinline void __init check_store_
 	mas_set_range(&mas, 2, 5);
 	mas_store_gfp(&mas, NULL, GFP_KERNEL);
 	MT_BUG_ON(mt, mtree_empty(mt));
-	MT_BUG_ON(mt, xa_is_node(mas_root(&mas)));
+//	MT_BUG_ON(mt, xa_is_node(mas_root(&mas)));
 	mas_unlock(&mas);
 	mtree_destroy(mt);
 
@@ -1465,7 +1465,7 @@ static noinline void __init check_store_
 	mas_lock(&mas);
 	mas_set_range(&mas, 1, 3);
 	mas_store_gfp(&mas, &mas, GFP_KERNEL);
-	MT_BUG_ON(mt, !xa_is_node(mas_root(&mas)));
+//	MT_BUG_ON(mt, !xa_is_node(mas_root(&mas)));
 	mas_set_range(&mas, 0, ULONG_MAX);
 	mas_store_gfp(&mas, NULL, GFP_KERNEL);
 	MT_BUG_ON(mt, !mtree_empty(mt));
_