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

Ryan Roberts
2024-12-17T16:58:43Z

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@arm.com>
> ---
> 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;