linux-kernel - Re: [PATCH] mm/numa_memblks: Use SZ_1M macro to denote bytes to MB conversion

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Message-ID: <aKSNED01R-AaclOT@kernel.org>
Date: Tue, 19 Aug 2025 17:41:20 +0300
From: Mike Rapoport <rppt@...nel.org>
To: pratyush.brahma@....qualcomm.com
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/numa_memblks: Use SZ_1M macro to denote bytes to MB
 conversion

On Tue, Aug 19, 2025 at 02:21:44PM +0530, pratyush.brahma@....qualcomm.com wrote:
> From: Pratyush Brahma <pratyush.brahma@....qualcomm.com>
> 
> Replace the manual bitwise conversion of bytes to MB with
> SZ_1M macro, a standard macro used within the mm subsystem,
> to improve readability.

There are few others:

$ git grep '>> 20' mm/
mm/memblock.c:          mem_size_mb = memblock_phys_mem_size() >> 20;
mm/memblock.c:                 (nr_pages << PAGE_SHIFT) >> 20, mem_size_mb);
mm/numa_emulation.c:           nid, eb->start, eb->end - 1, (eb->end - eb->start) >> 20);
mm/numa_emulation.c:                    size >> 20, min_size >> 20);

It makes sense to replace all of them in one patch.
 
> Signed-off-by: Pratyush Brahma <pratyush.brahma@....qualcomm.com>
> ---
>  mm/numa_memblks.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/numa_memblks.c b/mm/numa_memblks.c
> index 541a99c4071a67e5b0ef66f4136dee268a880003..a47aa262a33366337c38ccc7c7064da818523dd2 100644
> --- a/mm/numa_memblks.c
> +++ b/mm/numa_memblks.c
> @@ -427,9 +427,9 @@ static int __init numa_register_meminfo(struct numa_meminfo *mi)
>  		unsigned long pfn_align = node_map_pfn_alignment();
>  
>  		if (pfn_align && pfn_align < PAGES_PER_SECTION) {
> -			unsigned long node_align_mb = PFN_PHYS(pfn_align) >> 20;
> +			unsigned long node_align_mb = PFN_PHYS(pfn_align) / SZ_1M;
>  
> -			unsigned long sect_align_mb = PFN_PHYS(PAGES_PER_SECTION) >> 20;
> +			unsigned long sect_align_mb = PFN_PHYS(PAGES_PER_SECTION) / SZ_1M;
>  
>  			pr_warn("Node alignment %luMB < min %luMB, rejecting NUMA config\n",
>  				node_align_mb, sect_align_mb);
> 
> ---
> base-commit: c17b750b3ad9f45f2b6f7e6f7f4679844244f0b9
> change-id: 20250819-numa-memblks-refac-7b4b5017b598
> 
> Best regards,
> -- 
> Pratyush Brahma <pratyush.brahma@....qualcomm.com>
> 

-- 
Sincerely yours,
Mike.