[PATCH v2] maple_tree: Make maple state reusable after mas_empty_area()

[PATCH v2] maple_tree: Make maple state reusable after mas_empty_area()

[Peng Zhang]

Make mas->min and mas->max point to a node range instead of a leaf entry
range. This allows mas to still be usable after mas_empty_area() returns.
Users would get unexpected results from other operations on the maple
state after calling the affected function.

Reported-by: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Reported-by: Tad <support@spotco.us>
Reported-by: Michael Keyes <mgkeyes@vigovproductions.net>
Link: https://lore.kernel.org/linux-mm/32f156ba80010fd97dbaf0a0cdfc84366608624d.camel@intel.com/
Link: https://lore.kernel.org/linux-mm/e6108286ac025c268964a7ead3aab9899f9bc6e9.camel@spotco.us/
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
---
 lib/maple_tree.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 110a36479dced..8ebc43d4cc8c5 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5317,15 +5317,9 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
 
 	mt = mte_node_type(mas->node);
 	pivots = ma_pivots(mas_mn(mas), mt);
-	if (offset)
-		mas->min = pivots[offset - 1] + 1;
-
-	if (offset < mt_pivots[mt])
-		mas->max = pivots[offset];
-
-	if (mas->index < mas->min)
-		mas->index = mas->min;
-
+	min = mas_safe_min(mas, pivots, offset);
+	if (mas->index < min)
+		mas->index = min;
 	mas->last = mas->index + size - 1;
 	return 0;
 }
-- 
2.20.1

Re: [PATCH v2] maple_tree: Make maple state reusable after mas_empty_area()

[Liam R. Howlett]

* Peng Zhang <zhangpeng.00@bytedance.com> [230505 10:59]:
> Make mas->min and mas->max point to a node range instead of a leaf entry
> range. This allows mas to still be usable after mas_empty_area() returns.
> Users would get unexpected results from other operations on the maple
> state after calling the affected function.
> 
> Reported-by: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
> Reported-by: Tad <support@spotco.us>
> Reported-by: Michael Keyes <mgkeyes@vigovproductions.net>
> Link: https://lore.kernel.org/linux-mm/32f156ba80010fd97dbaf0a0cdfc84366608624d.camel@intel.com/
> Link: https://lore.kernel.org/linux-mm/e6108286ac025c268964a7ead3aab9899f9bc6e9.camel@spotco.us/
> Fixes: 54a611b60590 ("Maple Tree: add new data structure")
> Cc: <Stable@vger.kernel.org>
> Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
>  lib/maple_tree.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 110a36479dced..8ebc43d4cc8c5 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5317,15 +5317,9 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
>  
>  	mt = mte_node_type(mas->node);
>  	pivots = ma_pivots(mas_mn(mas), mt);
> -	if (offset)
> -		mas->min = pivots[offset - 1] + 1;
> -
> -	if (offset < mt_pivots[mt])
> -		mas->max = pivots[offset];
> -
> -	if (mas->index < mas->min)
> -		mas->index = mas->min;
> -
> +	min = mas_safe_min(mas, pivots, offset);
> +	if (mas->index < min)
> +		mas->index = min;
>  	mas->last = mas->index + size - 1;
>  	return 0;
>  }
> -- 
> 2.20.1
> 

Re: [PATCH v2] maple_tree: Make maple state reusable after mas_empty_area()

[Edgecombe, Rick P]

On Fri, 2023-05-05 at 22:58 +0800, Peng Zhang wrote:
> Make mas->min and mas->max point to a node range instead of a leaf
> entry
> range. This allows mas to still be usable after mas_empty_area()
> returns.
> Users would get unexpected results from other operations on the maple
> state after calling the affected function.
> 
> Reported-by: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
> Reported-by: Tad <support@spotco.us>
> Reported-by: Michael Keyes <mgkeyes@vigovproductions.net>
> Link:
> https://lore.kernel.org/linux-mm/32f156ba80010fd97dbaf0a0cdfc84366608624d.camel@intel.com/
> Link:
> https://lore.kernel.org/linux-mm/e6108286ac025c268964a7ead3aab9899f9bc6e9.camel@spotco.us/
> Fixes: 54a611b60590 ("Maple Tree: add new data structure")
> Cc: <Stable@vger.kernel.org>
> Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
> ---

Yep, this also works for me. Thanks.