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Message-ID: <e8cca5c1-2db1-840e-609b-4ae98791ba80@flygoat.com>
Date:   Tue, 31 May 2022 16:40:08 +0100
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Subject: Re: [PATCH] MIPS: fix pmd_mkinvalid
Content-Language: en-GB
To:     Hongchen Zhang <zhanghongchen@loongson.cn>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Zhaolong Zhang <zhangzl2013@126.com>
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1653971769-14152-1-git-send-email-zhanghongchen@loongson.cn>
From:   Jiaxun Yang <jiaxun.yang@flygoat.com>
In-Reply-To: <1653971769-14152-1-git-send-email-zhanghongchen@loongson.cn>
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在 2022/5/31 5:36, Hongchen Zhang 写道:
> pmd_mkinvalid should not clear dirty flag,otherwise the pmd
> dirty flag,it's ok to just clear _PAGE_VALID.
Hi Hongcheng,

Sorry, what is meant by "otherwise the pmd dirty flag"? Could you please
elaborate?
In my humble opinion _PAGE_PRESENT must be cleared in mkinvalid as it
nolonger present here. And thus it lose the dirty status.

Thanks
- Jiaxun

> Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn>
> ---
>   arch/mips/include/asm/pgtable.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
> index 374c632..d30a186 100644
> --- a/arch/mips/include/asm/pgtable.h
> +++ b/arch/mips/include/asm/pgtable.h
> @@ -698,7 +698,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
>   
>   static inline pmd_t pmd_mkinvalid(pmd_t pmd)
>   {
> -	pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY);
> +	pmd_val(pmd) &= ~_PAGE_VALID;
>   
>   	return pmd;
>   }