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

[Muchun Song <muchun.song@linux.dev>]

> On Oct 28, 2026, at 20:11, Kaitao Cheng <kaitao.cheng@linux.dev> 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.

Yes.

> 
> Use VM_WARN_ON() and fold compound_info_has_mask() into its condition,
> preserving short-circuit evaluation.
> 
> 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(

We usually don't end with "(“. At least I rarely see that in the existing code.
We can break the line after &&.

Thanks,
Muchun

> +   		(unsigned long)pfn_to_page(0), MAX_FOLIO_VMEMMAP_ALIGN));
> 
> sparse_metadata_init();
> sparse_init_subsection_map();
> -- 
> 2.53.0
>