Re: [v3 PATCH 1/7] mm: khugepaged: check THP flag in hugepage_vma_check()

[Zach O'Keefe]

Reviewed-by: Zach O'Keefe <zokeefe@xxxxxxxxxx>

On Mon, Jun 6, 2022 at 2:44 PM Yang Shi <shy828301@xxxxxxxxx> wrote:
>
> Currently the THP flag check in hugepage_vma_check() will fallthrough if
> the flag is NEVER and VM_HUGEPAGE is set.  This is not a problem for now
> since all the callers have the flag checked before or can't be invoked if
> the flag is NEVER.
>
> However, the following patch will call hugepage_vma_check() in more
> places, for example, page fault, so this flag must be checked in
> hugepge_vma_check().
>
> Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
> ---
>  mm/khugepaged.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 671ac7800e53..84b9cf4b9be9 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -458,6 +458,9 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
>         if (shmem_file(vma->vm_file))
>                 return shmem_huge_enabled(vma);
>
> +       if (!khugepaged_enabled())
> +               return false;
> +
>         /* THP settings require madvise. */
>         if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
>                 return false;
> --
> 2.26.3
>
>