linux-kernel - Re: [PATCH] arm64: mm: use ptep_clear() instead of pte_clear() in clear

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Date:   Fri, 11 Aug 2023 10:38:39 +0800
From:   Qi Zheng <qi.zheng@...ux.dev>
To:     catalin.marinas@....com, will@...nel.org,
        akpm@...ux-foundation.org, pasha.tatashin@...een.com,
        muchun.song@...ux.dev, wangkefeng.wang@...wei.com
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: mm: use ptep_clear() instead of pte_clear() in
 clear_flush()


I wrote wrong Kefeng's email address before, correct it now.


On 2023/8/10 17:32, Qi Zheng wrote:
> From: Qi Zheng <zhengqi.arch@...edance.com>
> 
> In clear_flush(), the original pte may be a present entry, so we should
> use ptep_clear() to let page_table_check track the pte clearing operation,
> otherwise it may cause false positive in subsequent set_pte_at().
> 
> Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
> ---
>   arch/arm64/mm/hugetlbpage.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 21716c940682..9c52718ea750 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -236,7 +236,7 @@ static void clear_flush(struct mm_struct *mm,
>   	unsigned long i, saddr = addr;
>   
>   	for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
> -		pte_clear(mm, addr, ptep);
> +		ptep_clear(mm, addr, ptep);
>   
>   	flush_tlb_range(&vma, saddr, addr);
>   }