Re: [PATCH] mm/mm_init.c: use round_up() to calculate usermap size

[Shivank Garg <shivankg@amd.com>]

On 2/12/2025 7:08 AM, Wei Yang wrote:
> Since pageblock_nr_pages and BITS_PER_LONG are power of 2, we could use
> round_up() to calculate it.
> 
> Also we have renamed blockflags to pageblock_flags, adjust the comment
> accordingly.
> 
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Suggested-by: Shivank Garg <shivankg@amd.com>

Thanks for the patch.

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

> ---
>  mm/mm_init.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 3ec50b5fda12..550d5ae98cfd 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1459,7 +1459,7 @@ void __meminit init_currently_empty_zone(struct zone *zone,
>  
>  #ifndef CONFIG_SPARSEMEM
>  /*
> - * Calculate the size of the zone->blockflags rounded to an unsigned long
> + * Calculate the size of the zone->pageblock_flags rounded to an unsigned long
>   * Start by making sure zonesize is a multiple of pageblock_order by rounding
>   * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
>   * round what is now in bits to nearest long in bits, then return it in
> @@ -1470,10 +1470,10 @@ static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned l
>  	unsigned long usemapsize;
>  
>  	zonesize += zone_start_pfn & (pageblock_nr_pages-1);
> -	usemapsize = roundup(zonesize, pageblock_nr_pages);
> +	usemapsize = round_up(zonesize, pageblock_nr_pages);
>  	usemapsize = usemapsize >> pageblock_order;
>  	usemapsize *= NR_PAGEBLOCK_BITS;
> -	usemapsize = roundup(usemapsize, BITS_PER_LONG);
> +	usemapsize = round_up(usemapsize, BITS_PER_LONG);
>  
>  	return usemapsize / BITS_PER_BYTE;
>  }