linux-kernel - Re: [PATCH v3 3/4] RISC-V: mm: Enable huge page support to kernel_page

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Message-ID: <Y9g9XGzF/X3OwXdP@spud>
Date:   Mon, 30 Jan 2023 21:57:48 +0000
From:   Conor Dooley <conor@...nel.org>
To:     Sia Jee Heng <jeeheng.sia@...rfivetech.com>,
        Alexandre Ghiti <alexghiti@...osinc.com>
Cc:     paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, leyfoon.tan@...rfivetech.com,
        mason.huo@...rfivetech.com
Subject: Re: [PATCH v3 3/4] RISC-V: mm: Enable huge page support to
 kernel_page_present() function

+CC Alex

On Fri, Jan 27, 2023 at 05:10:50PM +0800, Sia Jee Heng wrote:
> Currently kernel_page_present() function doesn't support huge page
> detection causes the function to mistakenly return false to the
> hibernation core.

This sounds like a bug & should have a fixes tag, no? I assume for
whatever commit enabled huge page support...
We don't support set_memory, which by the looks of things is the other
usecase for this function, so probably doesn't need backporting.

Alex, does this change look good to you?

> Add huge page detection to the function to solve the problem.
> 
> Signed-off-by: Sia Jee Heng <jeeheng.sia@...rfivetech.com>
> Reviewed-by: Ley Foon Tan <leyfoon.tan@...rfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@...rfivetech.com>
> ---
>  arch/riscv/mm/pageattr.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> index 86c56616e5de..792b8d10cdfc 100644
> --- a/arch/riscv/mm/pageattr.c
> +++ b/arch/riscv/mm/pageattr.c
> @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
>  	p4d = p4d_offset(pgd, addr);
>  	if (!p4d_present(*p4d))
>  		return false;
> +	if (p4d_leaf(*p4d))
> +		return true;
>  
>  	pud = pud_offset(p4d, addr);
>  	if (!pud_present(*pud))
>  		return false;
> +	if (pud_leaf(*pud))
> +		return true;
>  
>  	pmd = pmd_offset(pud, addr);
>  	if (!pmd_present(*pmd))
>  		return false;
> +	if (pmd_leaf(*pmd))
> +		return true;
>  
>  	pte = pte_offset_kernel(pmd, addr);
>  	return pte_present(*pte);
> -- 
> 2.34.1
> 

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