Re: [PATCH v7 03/12] khugepaged: generalize hugepage_vma_revalidate for mTHP support

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 2025/5/15 11:22, Nico Pache wrote:
> For khugepaged to support different mTHP orders, we must generalize this
> to check if the PMD is not shared by another VMA and the order is
> enabled.
> 
> No functional change in this patch.
> 
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Co-developed-by: Dev Jain <dev.jain@arm.com>
> Signed-off-by: Dev Jain <dev.jain@arm.com>
> Signed-off-by: Nico Pache <npache@redhat.com>
> ---
>   mm/khugepaged.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 5457571d505a..0c4d6a02d59c 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -920,7 +920,7 @@ static int khugepaged_find_target_node(struct collapse_control *cc)
>   static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>   				   bool expect_anon,
>   				   struct vm_area_struct **vmap,
> -				   struct collapse_control *cc)
> +				   struct collapse_control *cc, int order)
>   {
>   	struct vm_area_struct *vma;
>   	unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0;
> @@ -934,7 +934,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>   
>   	if (!thp_vma_suitable_order(vma, address, PMD_ORDER))

Sorry, I missed this before. Should we also change 'PMD_ORDER' to 
'order' for the thp_vma_suitable_order()?

>   		return SCAN_ADDRESS_RANGE;
> -	if (!thp_vma_allowable_order(vma, vma->vm_flags, tva_flags, PMD_ORDER))
> +	if (!thp_vma_allowable_order(vma, vma->vm_flags, tva_flags, order))
>   		return SCAN_VMA_CHECK;
>   	/*
>   	 * Anon VMA expected, the address may be unmapped then
> @@ -1130,7 +1130,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>   		goto out_nolock;
>   
>   	mmap_read_lock(mm);
> -	result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
> +	result = hugepage_vma_revalidate(mm, address, true, &vma, cc, HPAGE_PMD_ORDER);
>   	if (result != SCAN_SUCCEED) {
>   		mmap_read_unlock(mm);
>   		goto out_nolock;
> @@ -1164,7 +1164,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>   	 * mmap_lock.
>   	 */
>   	mmap_write_lock(mm);
> -	result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
> +	result = hugepage_vma_revalidate(mm, address, true, &vma, cc, HPAGE_PMD_ORDER);
>   	if (result != SCAN_SUCCEED)
>   		goto out_up_write;
>   	/* check if the pmd is still valid */
> @@ -2782,7 +2782,7 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
>   			mmap_read_lock(mm);
>   			mmap_locked = true;
>   			result = hugepage_vma_revalidate(mm, addr, false, &vma,
> -							 cc);
> +							 cc, HPAGE_PMD_ORDER);
>   			if (result  != SCAN_SUCCEED) {
>   				last_fail = result;
>   				goto out_nolock;