linux-kernel - Re: [PATCH] maple_tree: Fix mas_empty_area

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Date:   Tue, 12 Jul 2022 13:51:37 +0200
From:   Alexander Gordeev <agordeev@...ux.ibm.com>
To:     Liam Howlett <liam.howlett@...cle.com>
Cc:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] maple_tree: Fix mas_empty_area_rev() search exhaustion
 at root node

On Tue, Jul 12, 2022 at 01:50:36AM +0000, Liam Howlett wrote:
> When the possibilities of finding a gap are exhausted at the root node,
> the error code was not returned which results in returning a range that
> is currently occupied.  Add the necessary check for the error code and
> return to the caller.
> 
> Reported-by: Alexander Gordeev <agordeev@...ux.ibm.com>
> Fixes: d0aac5e48048 (Maple Tree: add new data structure)
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> ---
>  lib/maple_tree.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 9dc4ffff18d0..14e9ab14c1da 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5287,6 +5287,9 @@ int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
>  		}
>  	}
>  
> +	if (mas_is_err(mas))
> +		return xa_err(mas->node);
> +
>  	if (unlikely(mas->offset == MAPLE_NODE_SLOTS))
>  		return -EBUSY;

Tested-by: Alexander Gordeev <agordeev@...ux.ibm.com>

Thanks!