linux-kernel - Re: [PATCH v2 3/6] mm/mm_init.c: add new function calc_nr_all

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Date: Wed, 27 Mar 2024 17:40:12 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Baoquan He <bhe@...hat.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, x86@...nel.org,
	linuxppc-dev@...ts.ozlabs.org, akpm@...ux-foundation.org
Subject: Re: [PATCH v2 3/6] mm/mm_init.c: add new function calc_nr_all_pages()

On Mon, Mar 25, 2024 at 10:56:43PM +0800, Baoquan He wrote:
> This is a preparation to calculate nr_kernel_pages and nr_all_pages,
> both of which will be used later in alloc_large_system_hash().
> 
> nr_all_pages counts up all free but not reserved memory in memblock
> allocator, including HIGHMEM memory. While nr_kernel_pages counts up
> all free but not reserved low memory in memblock allocator, excluding
> HIGHMEM memory.
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>

Reviewed-by: Mike Rapoport (IBM) <rppt@...nel.org>

> ---
>  mm/mm_init.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 153fb2dc666f..c57a7fc97a16 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1264,6 +1264,30 @@ static void __init reset_memoryless_node_totalpages(struct pglist_data *pgdat)
>  	pr_debug("On node %d totalpages: 0\n", pgdat->node_id);
>  }
>  
> +static void __init calc_nr_kernel_pages(void)
> +{
> +	unsigned long start_pfn, end_pfn;
> +	phys_addr_t start_addr, end_addr;
> +	u64 u;
> +#ifdef CONFIG_HIGHMEM
> +	unsigned long high_zone_low = arch_zone_lowest_possible_pfn[ZONE_HIGHMEM];
> +#endif
> +
> +	for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) {
> +		start_pfn = PFN_UP(start_addr);
> +		end_pfn   = PFN_DOWN(end_addr);
> +
> +		if (start_pfn < end_pfn) {
> +			nr_all_pages += end_pfn - start_pfn;
> +#ifdef CONFIG_HIGHMEM
> +			start_pfn = clamp(start_pfn, 0, high_zone_low);
> +			end_pfn = clamp(end_pfn, 0, high_zone_low);
> +#endif
> +			nr_kernel_pages += end_pfn - start_pfn;
> +		}
> +	}
> +}
> +
>  static void __init calculate_node_totalpages(struct pglist_data *pgdat,
>  						unsigned long node_start_pfn,
>  						unsigned long node_end_pfn)
> -- 
> 2.41.0
> 

-- 
Sincerely yours,
Mike.