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Date:   Fri, 7 Jul 2023 10:58:48 -0400
From:   "Liam R. Howlett" <Liam.Howlett@Oracle.com>
To:     Peng Zhang <zhangpeng.00@bytedance.com>
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org
Subject: Re: [RESEND PATCH 5/8] maple_tree: make mas_validate_limits() check
 root node and node limit
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References: <20230707101057.29326-1-zhangpeng.00@bytedance.com>
 <20230707101057.29326-6-zhangpeng.00@bytedance.com>
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* Peng Zhang <zhangpeng.00@bytedance.com> [230707 06:11]:
> Update mas_validate_limits() to check root node, check node limit pivot
> if there is enough room for it to exist and check data_end. Remove the
> check for child existence as it is done in mas_validate_child_slot().
> 

The comments for this function say:
 * Validate all pivots are within mas->min and mas->max.

This needs adjusting since we are doing a whole lot more now..

Validate limits is now checking metadata ends where the maximum ends,
checks the pivots are within the limits of the node, and ensures
there is no slots or pivots set outside of the end of the data.

Did I miss anything?

> Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
> ---
>  lib/maple_tree.c | 26 +++++++++++---------------
>  1 file changed, 11 insertions(+), 15 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 88d6373f37b0..e84a042b6d84 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -7148,26 +7148,15 @@ static void mas_validate_limits(struct ma_state *mas)
>  	void __rcu **slots = ma_slots(mte_to_node(mas->node), type);
>  	unsigned long *pivots = ma_pivots(mas_mn(mas), type);
>  
> -	/* all limits are fine here. */
> -	if (mte_is_root(mas->node))
> -		return;
> -
>  	for (i = 0; i < mt_slots[type]; i++) {
>  		unsigned long piv;
>  
>  		piv = mas_safe_pivot(mas, pivots, i, type);
>  
> -		if (!piv && (i != 0))
> -			break;
> -
> -		if (!mte_is_leaf(mas->node)) {
> -			void *entry = mas_slot(mas, slots, i);
> -
> -			if (!entry)
> -				pr_err("%p[%u] cannot be null\n",
> -				       mas_mn(mas), i);
> -
> -			MT_BUG_ON(mas->tree, !entry);
> +		if (!piv && (i != 0)) {
> +			pr_err("Missing node limit pivot at %p[%u]",
> +			       mas_mn(mas), i);
> +			MAS_WARN_ON(mas, 1);
>  		}
>  
>  		if (prev_piv > piv) {
> @@ -7190,6 +7179,13 @@ static void mas_validate_limits(struct ma_state *mas)
>  		if (piv == mas->max)
>  			break;
>  	}
> +
> +	if (mas_data_end(mas) != i) {
> +		pr_err("node%p: data_end %u != the last slot offset %u\n",
> +		       mas_mn(mas), mas_data_end(mas), i);
> +		MT_BUG_ON(mas->tree, 1);
> +	}
> +
>  	for (i += 1; i < mt_slots[type]; i++) {
>  		void *entry = mas_slot(mas, slots, i);
>  
> -- 
> 2.20.1
> 
> 
> -- 
> maple-tree mailing list
> maple-tree@lists.infradead.org
> https://lists.infradead.org/mailman/listinfo/maple-tree