Re: [PATCH 10/16] mm/huge_memory: check pmd_present first in is_huge_zero_pmd

[Muchun Song]

On Thu, Jun 23, 2022 at 01:06:21AM +0800, Miaohe Lin wrote:
> When pmd is non-present, pmd_pfn returns an insane value. So we should

Although it does not cause any problems, it is better to check pmd_present()
in advance. The change looks good to me. So

> check pmd_present first to avoid acquiring such insane value and also
> avoid touching possible cold huge_zero_pfn cache line when pmd isn't
> present.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>

Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>