Re: [PATCH 03/12] mm/sparse: move initialization of section metadata to sparse_metadata_init()

[Lorenzo Stoakes (ARM)]

On Wed, Sep 09, 2026 at 03:32:56PM +0200, David Hildenbrand (Arm) wrote:
> Let's move the code responsible for initializing sparse metadata (usemap,
> memmap) into a helper. Cleanup the variable while at it (e.g.,
> "map_count").
>
> Drop the rather obvious code comments.
>
> No functional change intended.
>
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Similar comment to last, the move screws up the diff a bit, but staring at
git-delta it looks ok and the renames are good so:

Reviewed-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>

> ---
>  mm/sparse.c | 43 ++++++++++++++++++++++---------------------
>  1 file changed, 22 insertions(+), 21 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 36e3d854febc5..a85a9c3840f6c 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -257,38 +257,39 @@ static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
>  	}
>  }
>
> +static void __init sparse_metadata_init(void)
> +{
> +	unsigned long start_section_nr = first_present_section_nr();
> +	int nid_begin = sparse_early_nid(__nr_to_section(start_section_nr));
> +	unsigned long section_nr, nr_sections = 1;
> +
> +	for_each_present_section_nr(start_section_nr + 1, section_nr) {
> +		const int nid = sparse_early_nid(__nr_to_section(section_nr));
> +
> +		if (nid == nid_begin) {
> +			nr_sections++;
> +			continue;
> +		}
> +		sparse_init_nid(nid_begin, start_section_nr, section_nr, nr_sections);
> +		nid_begin = nid;
> +		start_section_nr = section_nr;
> +		nr_sections = 1;
> +	}
> +	sparse_init_nid(nid_begin, start_section_nr, section_nr, nr_sections);
> +}
> +
>  /*
>   * Allocate the accumulated non-linear sections, allocate a mem_map
>   * for each and record the physical to section mapping.
>   */
>  void __init sparse_init(void)
>  {
> -	unsigned long pnum_end, pnum_begin, map_count = 1;
> -	int nid_begin;
> -
>  	if (compound_info_has_mask()) {
>  		VM_WARN_ON_ONCE(!IS_ALIGNED((unsigned long) pfn_to_page(0),
>  				    MAX_FOLIO_VMEMMAP_ALIGN));
>  	}
>
> -	pnum_begin = first_present_section_nr();
> -	nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
> -
> -	for_each_present_section_nr(pnum_begin + 1, pnum_end) {
> -		int nid = sparse_early_nid(__nr_to_section(pnum_end));
> -
> -		if (nid == nid_begin) {
> -			map_count++;
> -			continue;
> -		}
> -		/* Init node with sections in range [pnum_begin, pnum_end) */
> -		sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
> -		nid_begin = nid;
> -		pnum_begin = pnum_end;
> -		map_count = 1;
> -	}
> -	/* cover the last node */
> -	sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
> +	sparse_metadata_init();
>  	sparse_init_subsection_map();
>  	vmemmap_populate_print_last();
>  }
>
> --
> 2.43.0
>

--
Cheers, Lorenzo