linux-kernel - Re: [PATCH v4 2/7] mm: Implement for_each_valid_pfn() for CONFIG

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Message-ID: <5569da56-4bd7-4ebf-88bf-a9edf7310f51@redhat.com>
Date: Thu, 24 Apr 2025 23:13:17 +0200
From: David Hildenbrand <david@...hat.com>
To: David Woodhouse <dwmw2@...radead.org>, Mike Rapoport <rppt@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 "Sauerwein, David" <dssauerw@...zon.de>,
 Anshuman Khandual <anshuman.khandual@....com>,
 Ard Biesheuvel <ardb@...nel.org>, Catalin Marinas <catalin.marinas@....com>,
 Marc Zyngier <maz@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Mike Rapoport <rppt@...ux.ibm.com>, Will Deacon <will@...nel.org>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, Ruihan Li <lrh2000@....edu.cn>
Subject: Re: [PATCH v4 2/7] mm: Implement for_each_valid_pfn() for
 CONFIG_FLATMEM

On 23.04.25 15:33, David Woodhouse wrote:
> From: David Woodhouse <dwmw@...zon.co.uk>
> 
> In the FLATMEM case, the default pfn_valid() just checks that the PFN is
> within the range [ ARCH_PFN_OFFSET .. ARCH_PFN_OFFSET + max_mapnr ).
> 
> The for_each_valid_pfn() function can therefore be a simple for() loop
> using those as min/max respectively.
> 
> Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
> Reviewed-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> ---
>   include/asm-generic/memory_model.h | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
> index a3b5029aebbd..74d0077cc5fa 100644
> --- a/include/asm-generic/memory_model.h
> +++ b/include/asm-generic/memory_model.h
> @@ -30,7 +30,15 @@ static inline int pfn_valid(unsigned long pfn)
>   	return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
>   }
>   #define pfn_valid pfn_valid
> -#endif
> +
> +#ifndef for_each_valid_pfn
> +#define for_each_valid_pfn(pfn, start_pfn, end_pfn)			 \
> +	for ((pfn) = max_t(unsigned long, (start_pfn), ARCH_PFN_OFFSET); \
> +	     (pfn) < min_t(unsigned long, (end_pfn),			 \
> +			   ARCH_PFN_OFFSET + max_mapnr);		 \
> +	     (pfn)++)
> +#endif /* for_each_valid_pfn */
> +#endif /* valid_pfn */

"pfn_valid"

>   
>   #elif defined(CONFIG_SPARSEMEM_VMEMMAP)
>   

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb