linux-kernel - Re: [PATCH v2 04/16] mm/huge_memory: use helper touch_pud in huge_pud_set

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Date:   Tue, 28 Jun 2022 22:59:24 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, shy828301@...il.com,
        willy@...radead.org, zokeefe@...gle.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/16] mm/huge_memory: use helper touch_pud in
 huge_pud_set_accessed

On Tue, Jun 28, 2022 at 09:28:23PM +0800, Miaohe Lin wrote:
> Use helper touch_pud to set pud accessed to simplify the code and improve
> the readability. No functional change intended.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  mm/huge_memory.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f7164ef8b6e3..d55d5efa06c8 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1284,15 +1284,15 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
>  
>  #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
>  static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
> -		pud_t *pud, int flags)
> +		      pud_t *pud, bool write)

You have change the last parameter. Have you forgotten to update its user
of follow_devmap_pud()?

Thanks.

>  {
>  	pud_t _pud;
>  
>  	_pud = pud_mkyoung(*pud);
> -	if (flags & FOLL_WRITE)
> +	if (write)
>  		_pud = pud_mkdirty(_pud);
>  	if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
> -				pud, _pud, flags & FOLL_WRITE))
> +				  pud, _pud, write))
>  		update_mmu_cache_pud(vma, addr, pud);
>  }
>  
> @@ -1384,21 +1384,13 @@ int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
>  
>  void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
>  {
> -	pud_t entry;
> -	unsigned long haddr;
>  	bool write = vmf->flags & FAULT_FLAG_WRITE;
>  
>  	vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
>  	if (unlikely(!pud_same(*vmf->pud, orig_pud)))
>  		goto unlock;
>  
> -	entry = pud_mkyoung(orig_pud);
> -	if (write)
> -		entry = pud_mkdirty(entry);
> -	haddr = vmf->address & HPAGE_PUD_MASK;
> -	if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
> -		update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
> -
> +	touch_pud(vmf->vma, vmf->address, vmf->pud, write);
>  unlock:
>  	spin_unlock(vmf->ptl);
>  }
> -- 
> 2.23.0
> 
>