[PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[Wei Yang]

Unify the process to install pmd folio.

No functional change is intended.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 include/linux/huge_mm.h |  6 ++++++
 mm/huge_memory.c        | 18 ++++++++++--------
 mm/khugepaged.c         |  9 +--------
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index e3ed008a076a..becfba48d17e 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -539,6 +539,8 @@ void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address,
 			   pmd_t *pmd, bool freeze);
 bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
 			   pmd_t *pmdp, struct folio *folio);
+void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
+		struct vm_area_struct *vma, unsigned long haddr, bool in_pf);
 
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 
@@ -629,6 +631,10 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma,
 	return false;
 }
 
+void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
+		struct vm_area_struct *vma, unsigned long haddr, bool in_pf)
+{}
+
 #define split_huge_pud(__vma, __pmd, __address)	\
 	do { } while (0)
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f13de93637bf..bfe38ca60a10 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1217,8 +1217,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
 	return folio;
 }
 
-static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
-		struct vm_area_struct *vma, unsigned long haddr)
+void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
+		struct vm_area_struct *vma, unsigned long haddr, bool in_pf)
 {
 	pmd_t entry;
 
@@ -1228,11 +1228,13 @@ static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
 	folio_add_lru_vma(folio, vma);
 	set_pmd_at(vma->vm_mm, haddr, pmd, entry);
 	update_mmu_cache_pmd(vma, haddr, pmd);
-	add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
-	count_vm_event(THP_FAULT_ALLOC);
-	count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
-	count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
 	deferred_split_folio(folio, false);
+	if (in_pf) {
+		add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+		count_vm_event(THP_FAULT_ALLOC);
+		count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
+		count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
+	}
 }
 
 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
@@ -1271,7 +1273,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 			return ret;
 		}
 		pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
-		map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
+		map_anon_folio_pmd(folio, vmf->pmd, vma, haddr, true);
 		mm_inc_nr_ptes(vma->vm_mm);
 		spin_unlock(vmf->ptl);
 	}
@@ -1877,7 +1879,7 @@ static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf)
 	if (ret)
 		goto release;
 	(void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd);
-	map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
+	map_anon_folio_pmd(folio, vmf->pmd, vma, haddr, true);
 	goto unlock;
 release:
 	folio_put(folio);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index f4f57ba69d72..cd187d10dee6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1224,17 +1224,10 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
 	__folio_mark_uptodate(folio);
 	pgtable = pmd_pgtable(_pmd);
 
-	_pmd = folio_mk_pmd(folio, vma->vm_page_prot);
-	_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
-
 	spin_lock(pmd_ptl);
 	BUG_ON(!pmd_none(*pmd));
-	folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
-	folio_add_lru_vma(folio, vma);
 	pgtable_trans_huge_deposit(mm, pmd, pgtable);
-	set_pmd_at(mm, address, pmd, _pmd);
-	update_mmu_cache_pmd(vma, address, pmd);
-	deferred_split_folio(folio, false);
+	map_anon_folio_pmd(folio, pmd, vma, address, false);
 	spin_unlock(pmd_ptl);
 
 	folio = NULL;
-- 
2.34.1

Re: [PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[Dev Jain]

On 04/10/25 2:55 pm, Wei Yang wrote:
> Unify the process to install pmd folio.
>
> No functional change is intended.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>

Base commit on which this patch applies?

> ---
>   include/linux/huge_mm.h |  6 ++++++
>   mm/huge_memory.c        | 18 ++++++++++--------
>   mm/khugepaged.c         |  9 +--------
>   3 files changed, 17 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index e3ed008a076a..becfba48d17e 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -539,6 +539,8 @@ void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address,
>   			   pmd_t *pmd, bool freeze);
>   bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
>   			   pmd_t *pmdp, struct folio *folio);
> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf);
>   
>   #else /* CONFIG_TRANSPARENT_HUGEPAGE */
>   
> @@ -629,6 +631,10 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma,
>   	return false;
>   }
>   
> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf)
> +{}
> +
>   #define split_huge_pud(__vma, __pmd, __address)	\
>   	do { } while (0)
>   
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f13de93637bf..bfe38ca60a10 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1217,8 +1217,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
>   	return folio;
>   }
>   
> -static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> -		struct vm_area_struct *vma, unsigned long haddr)
> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf)
>   {
>   	pmd_t entry;
>   
> @@ -1228,11 +1228,13 @@ static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
>   	folio_add_lru_vma(folio, vma);
>   	set_pmd_at(vma->vm_mm, haddr, pmd, entry);
>   	update_mmu_cache_pmd(vma, haddr, pmd);
> -	add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
> -	count_vm_event(THP_FAULT_ALLOC);
> -	count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
> -	count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
>   	deferred_split_folio(folio, false);
> +	if (in_pf) {
> +		add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
> +		count_vm_event(THP_FAULT_ALLOC);
> +		count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
> +		count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
> +	}
>   }
>   
>   static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
> @@ -1271,7 +1273,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
>   			return ret;
>   		}
>   		pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
> -		map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
> +		map_anon_folio_pmd(folio, vmf->pmd, vma, haddr, true);
>   		mm_inc_nr_ptes(vma->vm_mm);
>   		spin_unlock(vmf->ptl);
>   	}
> @@ -1877,7 +1879,7 @@ static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf)
>   	if (ret)
>   		goto release;
>   	(void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd);
> -	map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
> +	map_anon_folio_pmd(folio, vmf->pmd, vma, haddr, true);
>   	goto unlock;
>   release:
>   	folio_put(folio);
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index f4f57ba69d72..cd187d10dee6 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1224,17 +1224,10 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>   	__folio_mark_uptodate(folio);
>   	pgtable = pmd_pgtable(_pmd);
>   
> -	_pmd = folio_mk_pmd(folio, vma->vm_page_prot);
> -	_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
> -
>   	spin_lock(pmd_ptl);
>   	BUG_ON(!pmd_none(*pmd));
> -	folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
> -	folio_add_lru_vma(folio, vma);
>   	pgtable_trans_huge_deposit(mm, pmd, pgtable);
> -	set_pmd_at(mm, address, pmd, _pmd);
> -	update_mmu_cache_pmd(vma, address, pmd);
> -	deferred_split_folio(folio, false);
> +	map_anon_folio_pmd(folio, pmd, vma, address, false);
>   	spin_unlock(pmd_ptl);
>   
>   	folio = NULL;

Re: [PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[Wei Yang]

On Sat, Oct 04, 2025 at 07:56:48PM +0530, Dev Jain wrote:
>
>On 04/10/25 2:55 pm, Wei Yang wrote:
>> Unify the process to install pmd folio.
>> 
>> No functional change is intended.
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>
>Base commit on which this patch applies?
>

The base commit is 

696ef26cfef2 2025-10-03 mm: redefine VM_* flag constants with BIT()

on latest akpm/mm-new branch.

-- 
Wei Yang
Help you, Help me

Re: [PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[Wei Yang]

On Sun, Oct 05, 2025 at 12:04:13AM +0000, Wei Yang wrote:
>On Sat, Oct 04, 2025 at 07:56:48PM +0530, Dev Jain wrote:
>>
>>On 04/10/25 2:55 pm, Wei Yang wrote:
>>> Unify the process to install pmd folio.
>>> 
>>> No functional change is intended.
>>> 
>>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>>
>>Base commit on which this patch applies?
>>
>
>The base commit is 
>
>696ef26cfef2 2025-10-03 mm: redefine VM_* flag constants with BIT()
>
>on latest akpm/mm-new branch.
>

Forget to mention, with this [1] change applied.

[1]: https://lkml.kernel.org/r/20251002013825.20448-1-richard.weiyang@gmail.com

-- 
Wei Yang
Help you, Help me

Re: [PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[Matthew Wilcox]

On Sat, Oct 04, 2025 at 09:25:23AM +0000, Wei Yang wrote:
> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf);

It's generally a bad idea to have a 'bool' flag like this because it's
not immediately obvious in the callers what 'true' means.

> -static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> -		struct vm_area_struct *vma, unsigned long haddr)
> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf)
>  {
>  	pmd_t entry;
>  
> @@ -1228,11 +1228,13 @@ static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
>  	folio_add_lru_vma(folio, vma);
>  	set_pmd_at(vma->vm_mm, haddr, pmd, entry);
>  	update_mmu_cache_pmd(vma, haddr, pmd);
> -	add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
> -	count_vm_event(THP_FAULT_ALLOC);
> -	count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
> -	count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
>  	deferred_split_folio(folio, false);
> +	if (in_pf) {
> +		add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
> +		count_vm_event(THP_FAULT_ALLOC);
> +		count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
> +		count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
> +	}
>  }

And it's really not necessary here.  There's probably better naming
available, but a good pattern to follow here would be:

void map_anon_folio_pmd_nopf(struct folio *folio, pmd_t *pmd,
		struct vm_area_struct *vma, unsigned long haddr)
{
...
}

static void map_anon_folio_pmd_pf(struct folio *folio, pmd_t *pmd,
		struct vm_area_struct *vma, unsigned long haddr)
{
	map_anon_folio_pmd_nopf(folio, pmd, vma, haddr);
	add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
	count_vm_event(THP_FAULT_ALLOC);
	count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
	count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
}

Re: [PATCH] mm/khugepaged: use map_anon_folio_pmd() in collapse_huge_page()

[Wei Yang]

On Sun, Oct 05, 2025 at 02:48:25AM +0100, Matthew Wilcox wrote:
>On Sat, Oct 04, 2025 at 09:25:23AM +0000, Wei Yang wrote:
>> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
>> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf);
>
>It's generally a bad idea to have a 'bool' flag like this because it's
>not immediately obvious in the callers what 'true' means.
>
>> -static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
>> -		struct vm_area_struct *vma, unsigned long haddr)
>> +void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
>> +		struct vm_area_struct *vma, unsigned long haddr, bool in_pf)
>>  {
>>  	pmd_t entry;
>>  
>> @@ -1228,11 +1228,13 @@ static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
>>  	folio_add_lru_vma(folio, vma);
>>  	set_pmd_at(vma->vm_mm, haddr, pmd, entry);
>>  	update_mmu_cache_pmd(vma, haddr, pmd);
>> -	add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
>> -	count_vm_event(THP_FAULT_ALLOC);
>> -	count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
>> -	count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
>>  	deferred_split_folio(folio, false);
>> +	if (in_pf) {
>> +		add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
>> +		count_vm_event(THP_FAULT_ALLOC);
>> +		count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
>> +		count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
>> +	}
>>  }
>
>And it's really not necessary here.  There's probably better naming
>available, but a good pattern to follow here would be:
>
>void map_anon_folio_pmd_nopf(struct folio *folio, pmd_t *pmd,
>		struct vm_area_struct *vma, unsigned long haddr)
>{
>...
>}
>
>static void map_anon_folio_pmd_pf(struct folio *folio, pmd_t *pmd,
>		struct vm_area_struct *vma, unsigned long haddr)
>{
>	map_anon_folio_pmd_nopf(folio, pmd, vma, haddr);
>	add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
>	count_vm_event(THP_FAULT_ALLOC);
>	count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
>	count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
>}

Thanks for the comment.

Will adjust it.

-- 
Wei Yang
Help you, Help me