linux-kernel - Re: [PATCH v3 19/29] sparc: introduce arch_zone_limits

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Message-ID: <7566eef3-bce4-4100-8a11-d88ef1e887a9@gaisler.com>
Date: Tue, 13 Jan 2026 13:28:09 +0100
From: Andreas Larsson <andreas@...sler.com>
To: Mike Rapoport <rppt@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>
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Subject: Re: [PATCH v3 19/29] sparc: introduce arch_zone_limits_init()

On 2026-01-11 09:20, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>
> 
> Move calculations of zone limits to a dedicated arch_zone_limits_init()
> function.
> 
> Later MM core will use this function as an architecture specific callback
> during nodes and zones initialization and thus there won't be a need to
> call free_area_init() from every architecture.
> 
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> ---
>  arch/sparc/mm/init_64.c |  6 ++++++
>  arch/sparc/mm/srmmu.c   | 12 ++++++++----
>  2 files changed, 14 insertions(+), 4 deletions(-)

Hi Mike,

Thanks for this nice cleanup series.


> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index df9f7c444c39..fbaad449dfc9 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -2279,6 +2279,11 @@ static void __init reduce_memory(phys_addr_t limit_ram)
>  	memblock_enforce_memory_limit(limit_ram);
>  }
>  
> +void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
> +{
> +	max_zone_pfns[ZONE_NORMAL] = last_valid_pfn;
> +}
> +
>  void __init paging_init(void)
>  {
>  	unsigned long end_pfn, shift, phys_base;
> @@ -2461,6 +2466,7 @@ void __init paging_init(void)
>  
>  		max_zone_pfns[ZONE_NORMAL] = end_pfn;

This old initialization of max_zone_pfns[ZONE_NORMAL] should also be
removed, right? With that removed it makes the local end_pfn variable
set but unused, so could you please also remove that one?

I know that this whole code block gets removed later, but the cleanup
max_zone_pfns[ZONE_NORMAL] and the removal of end_pfn (that is not done
later in this version of the series) fits logically in this patch.

>  
> +		arch_zone_limits_init(max_zone_pfns);
>  		free_area_init(max_zone_pfns);
>  	}
>  
> diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
> index f8fb4911d360..81e90151db90 100644
> --- a/arch/sparc/mm/srmmu.c
> +++ b/arch/sparc/mm/srmmu.c
> @@ -884,6 +884,13 @@ static void __init map_kernel(void)
>  
>  void (*poke_srmmu)(void) = NULL;
>  
> +void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
> +{
> +	max_zone_pfns[ZONE_DMA] = max_low_pfn;
> +	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
> +	max_zone_pfns[ZONE_HIGHMEM] = highend_pfn;
> +}
> +
>  void __init srmmu_paging_init(void)
>  {
>  	int i;
> @@ -967,10 +974,7 @@ void __init srmmu_paging_init(void)
>  	{
>  		unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
>  
> -		max_zone_pfn[ZONE_DMA] = max_low_pfn;
> -		max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
> -		max_zone_pfn[ZONE_HIGHMEM] = highend_pfn;
> -
> +		arch_zone_limits_init(max_zone_pfn);
>  		free_area_init(max_zone_pfn);
>  	}
>  }

With the feedback for arch/sparc/mm/init_64.c addressed:

Acked-by: Andreas Larsson <andreas@...sler.com>

Cheers,
Andreas