linux-kernel - Re: [PATCH v3] arm64: mm: Test for pmd_sect() in vmemmap_check

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Message-ID: <3aed8d7d-568c-43fc-a157-cb13d6259ebe@arm.com>
Date: Fri, 3 Jan 2025 12:36:36 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Zhenhua Huang <quic_zhenhuah@...cinc.com>, catalin.marinas@....com
Cc: will@...nel.org, ardb@...nel.org, ryan.roberts@....com,
 mark.rutland@....com, joey.gouly@....com, dave.hansen@...ux.intel.com,
 akpm@...ux-foundation.org, chenfeiyang@...ngson.cn, chenhuacai@...nel.org,
 linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, quic_tingweiz@...cinc.com
Subject: Re: [PATCH v3] arm64: mm: Test for pmd_sect() in vmemmap_check_pmd()



On 1/2/25 13:10, Zhenhua Huang wrote:
> Commit 2045a3b8911b ("mm/sparse-vmemmap: generalise vmemmap_populate_hugepages()")
> introduces the vmemmap_check_pmd() while does not verify if the entry is a
> section mapping, as is already done for Loongarch & X86.
> The update includes a check for pmd_sect(). Only if pmd_sect() returns true,
> further vmemmap population for the addr is skipped.
> 
> Signed-off-by: Zhenhua Huang <quic_zhenhuah@...cinc.com>
> ---
> Separate the patch out based on the discussion:
> https://lore.kernel.org/linux-arm-kernel/20241209094227.1529977-3-quic_zhenhuah@quicinc.com/T/#m41d49cd91b348ecfe2c37c4b3c0911180426934e

LGTM, regardless whether this patch goes on its own or via the series.

Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>

>  
>  arch/arm64/mm/mmu.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9afeb35673a3..50a22c63f450 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1172,7 +1172,8 @@ int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
>  				unsigned long addr, unsigned long next)
>  {
>  	vmemmap_verify((pte_t *)pmdp, node, addr, next);
> -	return 1;
> +
> +	return pmd_sect(READ_ONCE(*pmdp));
>  }
>  
>  int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,