linux-kernel - Re: [PATCH 3/3] tools/testing/radix-tree: Test maple tree chaining mas

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Message-ID: <c1ccb6b2-a981-478f-ab7e-91078a6d31ba@lucifer.local>
Date: Fri, 20 Jun 2025 16:51:30 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, maple-tree@...ts.infradead.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org, stable@...nel.org,
        Suren Baghdasaryan <surenb@...gle.com>,
        Hailong Liu <hailong.liu@...o.com>, zhangpeng.00@...edance.com,
        Steve Kang <Steve.Kang@...soc.com>,
        Matthew Wilcox <willy@...radead.org>,
        Sidhartha Kumar <sidhartha.kumar@...cle.com>
Subject: Re: [PATCH 3/3] tools/testing/radix-tree: Test maple tree chaining
 mas_preallocate() calls

On Mon, Jun 16, 2025 at 02:45:21PM -0400, Liam R. Howlett wrote:
> Testing calling multiple mas_preallocate() calls in a row after
> adjusting the maple state.  Ensures new calls to mas_preallocate() will
> change the number of allocated nodes.

Really helpful to have a regression test for such a fiddly thing!

>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>

Acked-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  tools/testing/radix-tree/maple.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
> index 6a5b0342941c4..49e89dfad950c 100644
> --- a/tools/testing/radix-tree/maple.c
> +++ b/tools/testing/radix-tree/maple.c
> @@ -35693,6 +35693,18 @@ static noinline void __init check_prealloc(struct maple_tree *mt)
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
> +
> +	/* Chaining multiple preallocations */
> +	mt_set_in_rcu(mt);
> +	mas_set_range(&mas, 800, 805); /* Slot store, should be 0 allocations */
> +	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	allocated = mas_allocated(&mas);
> +	MT_BUG_ON(mt, allocated != 0);
> +	mas.last = 809; /* Node store */
> +	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	allocated = mas_allocated(&mas);
> +	MT_BUG_ON(mt, allocated != 1);
> +	mas_store_prealloc(&mas, ptr);
>  }
>  /* End of preallocation testing */
>
> --
> 2.47.2
>