linux-kernel - Re: [PATCH v2 1/2] arm64/hugetlb: Use ptep_get() to get the pte value of a huge page

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Message-ID: <88e02de3-c87e-2728-d980-da0e70a58102@arm.com>
Date:   Fri, 13 May 2022 16:20:35 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>,
        catalin.marinas@....com, will@...nel.org
Cc:     mike.kravetz@...cle.com, akpm@...ux-foundation.org,
        songmuchun@...edance.com, willy@...radead.org,
        christophe.leroy@...roup.eu, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v2 1/2] arm64/hugetlb: Use ptep_get() to get the pte value
 of a huge page



On 5/13/22 09:07, Baolin Wang wrote:
> The original huge_ptep_get() on ARM64 is just a wrapper of ptep_get(),

Right, as arm64 does not enable __HAVE_ARCH_HUGE_PTEP_GET.

> which will not take into account any contig-PTEs dirty and access bits.

As expected being operating on a single table entry.

> Meanwhile we will implement a new ARM64-specific huge_ptep_get()
> interface in following patch, which will take into account any contig-PTEs
> dirty and access bits. To keep the same efficient logics to get the pte

s/logics/logic

> value, change to use ptep_get() as a preparation.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> Reviewed-by: Muchun Song <songmuchun@...edance.com>

LGTM

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

> ---
>  arch/arm64/mm/hugetlbpage.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 30f5b76..9553851 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -172,7 +172,7 @@ static pte_t get_clear_contig(struct mm_struct *mm,
>  			     unsigned long pgsize,
>  			     unsigned long ncontig)
>  {
> -	pte_t orig_pte = huge_ptep_get(ptep);
> +	pte_t orig_pte = ptep_get(ptep);
>  	unsigned long i;
>  
>  	for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
> @@ -379,7 +379,7 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
>  {
>  	int ncontig;
>  	size_t pgsize;
> -	pte_t orig_pte = huge_ptep_get(ptep);
> +	pte_t orig_pte = ptep_get(ptep);
>  
>  	if (!pte_cont(orig_pte))
>  		return ptep_get_and_clear(mm, addr, ptep);
> @@ -402,11 +402,11 @@ static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
>  {
>  	int i;
>  
> -	if (pte_write(pte) != pte_write(huge_ptep_get(ptep)))
> +	if (pte_write(pte) != pte_write(ptep_get(ptep)))
>  		return 1;
>  
>  	for (i = 0; i < ncontig; i++) {
> -		pte_t orig_pte = huge_ptep_get(ptep + i);
> +		pte_t orig_pte = ptep_get(ptep + i);
>  
>  		if (pte_dirty(pte) != pte_dirty(orig_pte))
>  			return 1;