Message-ID: <82c12d63-1c28-f38f-eaca-fd251706ec74@suse.cz>
Date:   Thu, 16 Mar 2023 12:18:56 +0100
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Subject: Re: [PATCH 08/10] mm/slub: Fix MAX_ORDER usage in calculate_order()
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To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>,
        David Hildenbrand <david@redhat.com>
Cc:     linux-mm@kvack.org, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>
References: <20230315113133.11326-1-kirill.shutemov@linux.intel.com>
 <20230315113133.11326-9-kirill.shutemov@linux.intel.com>
From:   Vlastimil Babka <vbabka@suse.cz>
In-Reply-To: <20230315113133.11326-9-kirill.shutemov@linux.intel.com>
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On 3/15/23 12:31, Kirill A. Shutemov wrote:
> MAX_ORDER is not inclusive: the maximum allocation order buddy allocator
> can deliver is MAX_ORDER-1.
> 
> Fix MAX_ORDER usage in calculate_order().
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Pekka Enberg <penberg@kernel.org>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/slub.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 39327e98fce3..32eb6b50fe18 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -4171,7 +4171,7 @@ static inline int calculate_order(unsigned int size)
>  	/*
>  	 * Doh this slab cannot be placed using slub_max_order.
>  	 */
> -	order = calc_slab_order(size, 1, MAX_ORDER, 1);
> +	order = calc_slab_order(size, 1, MAX_ORDER - 1, 1);
>  	if (order < MAX_ORDER)
>  		return order;
>  	return -ENOSYS;