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

[Dev Jain <dev.jain@arm.com>]

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;