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

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Date:   Wed, 29 Jun 2022 10:17:32 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Muchun Song <songmuchun@...edance.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 2022/6/28 22:59, Muchun Song wrote:
> 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()?

My bad. I was overloaded yesterday. Thanks for catching this!
Will change it in next version.

> 
> 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
>>
>>
> .
>