linux-kernel - Re: [PATCH] drivers/sgi-gru: Use pxdp

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Message-ID: <4bf3894a-1825-447a-8efd-64ecc09e2dc6@arm.com>
Date: Wed, 8 Oct 2025 09:55:28 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: linux-kernel@...r.kernel.org
Cc: Dimitri Sivanich <dimitri.sivanich@....com>, Arnd Bergmann
 <arnd@...db.de>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] drivers/sgi-gru: Use pxdp_get() for page table access



On 08/10/25 9:51 AM, Anshuman Khandual wrote:
> Replace all READ_ONCE() with a standard page table accessors i.e pxdp_get()
> that default into READ_ONCE() in cases where platforms do not override.
> 
> Cc: Dimitri Sivanich <dimitri.sivanich@....com>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>  drivers/misc/sgi-gru/grufault.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
> index 3557d78ee47a..60e55facd8d7 100644
> --- a/drivers/misc/sgi-gru/grufault.c
> +++ b/drivers/misc/sgi-gru/grufault.c
> @@ -212,19 +212,19 @@ static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr,
>  	pte_t pte;
>  
>  	pgdp = pgd_offset(vma->vm_mm, vaddr);
> -	if (unlikely(pgd_none(*pgdp)))
> +	if (unlikely(pgd_none(pgdp_get(pgdp))))
>  		goto err;
>  
>  	p4dp = p4d_offset(pgdp, vaddr);
> -	if (unlikely(p4d_none(*p4dp)))
> +	if (unlikely(p4d_none(p4dp_get(p4dp))))
>  		goto err;
>  
>  	pudp = pud_offset(p4dp, vaddr);
> -	if (unlikely(pud_none(*pudp)))
> +	if (unlikely(pud_none(pudp_get(pudp))))
>  		goto err;
>  
>  	pmdp = pmd_offset(pudp, vaddr);
> -	if (unlikely(pmd_none(*pmdp)))
> +	if (unlikely(pmd_none(pmdp_get(pmdp))))
>  		goto err;
>  #ifdef CONFIG_X86_64
>  	if (unlikely(pmd_leaf(*pmdp)))

Please ignore this patch as it does not replace any READ_ONCE()
based page table accesses in this file. My bad.