linux-kernel - Re: [PATCH] mm/shmem.c: use helper transhuge_vma

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Date:   Fri, 10 Jun 2022 20:14:46 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Miaohe Lin <linmiaohe@...wei.com>
cc:     akpm@...ux-foundation.org, hughd@...gle.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/shmem.c: use helper transhuge_vma_enabled()

On Sat, 11 Jun 2022, Miaohe Lin wrote:

> Use helper transhuge_vma_enabled() to check whether transhuge is enable
> on vma. Minor readability improvement.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>

No thanks, that's a readability regression, forcing reader
to go and look up what transhuge_vma_enabled() actually means.

What you call a helper, I call an obfuscator - as I implied in
b9e2faaf6fa0 ("huge tmpfs: revert shmem's use of transhuge_vma_enabled()")

Hugh

> ---
>  mm/shmem.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 133c67057d41..59cc2e980c95 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -480,8 +480,7 @@ bool shmem_is_huge(struct vm_area_struct *vma,
>  		return false;
>  	if (shmem_huge == SHMEM_HUGE_DENY)
>  		return false;
> -	if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
> -	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
> +	if (vma && !transhuge_vma_enabled(vma, vma->vm_flags))
>  		return false;
>  	if (shmem_huge == SHMEM_HUGE_FORCE)
>  		return true;
> -- 
> 2.23.0