Re: [RFC PATCH 03/12] khugepaged: Generalize hugepage_vma_revalidate()

[Ryan Roberts]

On 16/12/2024 16:50, Dev Jain wrote:
> Post retaking the lock, it must be checked that the VMA is suitable for our
> scan order. Hence, generalize hugepage_vma_revalidate().
> 
> Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
> ---
>  mm/khugepaged.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 02cd424b8e48..2f0601795471 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -918,7 +918,7 @@ static int hpage_collapse_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 vm_area_struct **vmap, int order,
>  				   struct collapse_control *cc)
>  {
>  	struct vm_area_struct *vma;
> @@ -931,9 +931,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>  	if (!vma)
>  		return SCAN_VMA_NULL;
>  
> -	if (!thp_vma_suitable_order(vma, address, PMD_ORDER))
> +	if (!thp_vma_suitable_order(vma, address, 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
> @@ -1134,7 +1134,7 @@ 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, order, cc);

some more compilation issues: replace order with HPAGE_PMD_ORDER.

>  	if (result != SCAN_SUCCEED) {
>  		mmap_read_unlock(mm);
>  		goto out_nolock;
> @@ -1168,7 +1168,7 @@ 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, order, cc);

and here.

>  	if (result != SCAN_SUCCEED)
>  		goto out_up_write;
>  	/* check if the pmd is still valid */
> @@ -2776,7 +2776,7 @@ 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);
> +							 HPAGE_PMD_ORDER, cc);
>  			if (result  != SCAN_SUCCEED) {
>  				last_fail = result;
>  				goto out_nolock;