Re: [PATCH] mm/sparse: simplify the vmemmap alignment check

[Mike Rapoport <rppt@kernel.org>]

Hi,

On Wed, Oct 28, 2026 at 08:11:29PM +0800, Kaitao Cheng wrote:
> From: Kaitao Cheng <chengkaitao@kylinos.cn>
> 
> sparse_init() is called only once during boot, and the vmemmap alignment
> check is outside any loop, so VM_WARN_ON_ONCE() provides no benefit over
> VM_WARN_ON() here.
> 
> Use VM_WARN_ON() and fold compound_info_has_mask() into its condition,
> preserving short-circuit evaluation.

Do you think it's worth the churn?
 
> Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
> ---
>  mm/sparse.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 6acb628c8a73..248bee2d39b9 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -277,10 +277,8 @@ static void __init sparse_metadata_init(void)
>   */
>  void __init sparse_init(void)
>  {
> -	if (compound_info_has_mask()) {
> -		VM_WARN_ON_ONCE(!IS_ALIGNED((unsigned long) pfn_to_page(0),
> -				    MAX_FOLIO_VMEMMAP_ALIGN));
> -	}
> +	VM_WARN_ON(compound_info_has_mask() && !IS_ALIGNED(
> +		   (unsigned long)pfn_to_page(0), MAX_FOLIO_VMEMMAP_ALIGN));
>  
>  	sparse_metadata_init();
>  	sparse_init_subsection_map();
> -- 
> 2.53.0
> 

-- 
Sincerely yours,
Mike.