Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <r...@kernel.org>
> 
> Instead of looping over numa_meminfo array to detect node's start and
> end addresses use get_pfn_range_for_init().
> 
> This is shorter and make it easier to lift numa_memblks to generic code.
> 
> Signed-off-by: Mike Rapoport (Microsoft) <r...@kernel.org>
> Tested-by: Zi Yan <z...@nvidia.com> # for x86_64 and arm64
> ---
>  arch/x86/mm/numa.c | 13 +++----------
>  1 file changed, 3 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index edfc38803779..cfe7e5477cf8 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -521,17 +521,10 @@ static int __init numa_register_memblks(struct 
> numa_meminfo *mi)
>  
>       /* Finally register nodes. */
>       for_each_node_mask(nid, node_possible_map) {
> -             u64 start = PFN_PHYS(max_pfn);
> -             u64 end = 0;
> +             unsigned long start_pfn, end_pfn;
>  
> -             for (i = 0; i < mi->nr_blks; i++) {
> -                     if (nid != mi->blk[i].nid)
> -                             continue;
> -                     start = min(mi->blk[i].start, start);
> -                     end = max(mi->blk[i].end, end);
> -             }
> -
> -             if (start >= end)
> +             get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
> +             if (start_pfn >= end_pfn)

Assuming I understand why this works, would it be worth a comment like:

"Note, get_pfn_range_for_nid() depends on memblock_set_node() having
 already happened"

...at least that context was not part of the diff so took me second to
figure out how this works.

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