Re: [PATCH 01/12] mm/sparse: move mem_section init to sparse_extreme_init()

[Lorenzo Stoakes (ARM)]

On Wed, Sep 09, 2026 at 03:32:54PM +0200, David Hildenbrand (Arm) wrote:
> Let's just avoid another pair of ifdef inside a function. While at it,
> switch to INTERNODE_CACHE_BYTES by just defining a fallback in cache.h
> as well, given that the x86 variant already provides one.
>
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Nic ecleanup, one nit below.

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

> ---
>  include/linux/cache.h |  1 +
>  mm/sparse.c           | 19 ++++++++++++-------
>  2 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/cache.h b/include/linux/cache.h
> index e69768f50d532..b6e857b985bca 100644
> --- a/include/linux/cache.h
> +++ b/include/linux/cache.h
> @@ -89,6 +89,7 @@
>   */
>  #ifndef INTERNODE_CACHE_SHIFT
>  #define INTERNODE_CACHE_SHIFT L1_CACHE_SHIFT
> +#define INTERNODE_CACHE_BYTES (1 << INTERNODE_CACHE_SHIFT)

NIT: 1UL?

>  #endif
>
>  #if !defined(____cacheline_internodealigned_in_smp)
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 9349ed6326c01..6a6d258862904 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -103,11 +103,22 @@ int __meminit sparse_index_init(unsigned long section_nr, int nid)
>
>  	return 0;
>  }
> +
> +static void __init sparse_extreme_init(void)
> +{
> +	const unsigned long size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
> +
> +	mem_section = memblock_alloc_or_panic(size, INTERNODE_CACHE_BYTES);
> +}
>  #else /* !SPARSEMEM_EXTREME */
>  int __meminit sparse_index_init(unsigned long section_nr, int nid)
>  {
>  	return 0;
>  }
> +
> +static void __init sparse_extreme_init(void)
> +{
> +}
>  #endif
>
>  /*
> @@ -197,13 +208,7 @@ void __init sparse_sections_init(void)
>  	unsigned long start, end;
>  	int i, nid;
>
> -#ifdef CONFIG_SPARSEMEM_EXTREME
> -	unsigned long size, align;
> -
> -	size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
> -	align = 1 << (INTERNODE_CACHE_SHIFT);
> -	mem_section = memblock_alloc_or_panic(size, align);
> -#endif
> +	sparse_extreme_init();
>
>  	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
>  		memory_present(nid, start, end);
>
> --
> 2.43.0
>

--
Cheers, Lorenzo