Re: [PATCH] mm/mm_init.c: use round_up() to align movable range

[Shivank Garg <shivankg@amd.com>]

On 2/7/2025 3:34 PM, Wei Yang wrote:
> Since MAX_ORDER_NR_PAGES is power of 2, let's use a faster version.

Makes sense to me.

Reviewed-by: Shivank Garg <shivankg@amd.com>


I noticed two similar instances in the same file
where round_up() might also be applicable:

  mm_init.c (usemap_size):
    usemapsize = roundup(zonesize, pageblock_nr_pages);
    usemapsize = roundup(usemapsize, BITS_PER_LONG);

Since both pageblock_nr_pages (1UL << pageblock_order) and BITS_PER_LONG (32 or 64)
are powers of 2, these could potentially use round_up() as well. Perhaps 
worth considering in a follow-up patch?

Thanks,
Shivank



> 
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> ---
>  mm/mm_init.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index dec4084fe15a..99ef70a8b63c 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -438,7 +438,7 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  		 * was requested by the user
>  		 */
>  		required_movablecore =
> -			roundup(required_movablecore, MAX_ORDER_NR_PAGES);
> +			round_up(required_movablecore, MAX_ORDER_NR_PAGES);
>  		required_movablecore = min(totalpages, required_movablecore);
>  		corepages = totalpages - required_movablecore;
>  
> @@ -549,7 +549,7 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  		unsigned long start_pfn, end_pfn;
>  
>  		zone_movable_pfn[nid] =
> -			roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
> +			round_up(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
>  
>  		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
>  		if (zone_movable_pfn[nid] >= end_pfn)