Re: [PATCH 2/2] mm,memory_hotplug: Drop redundant hugepage_migration_supported check

From: David Hildenbrand
Date: Mon Mar 04 2019 - 04:18:49 EST


On 04.03.19 09:51, Oscar Salvador wrote:
> has_unmovable_pages() does alreay check whether the hugetlb page supports
> migration, so all non-migrateable hugetlb pages should have been caught there.
> Let us drop the check from scan_movable_pages() as is redundant.
>
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/memory_hotplug.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 0f479c710615..2dfd9a0b0832 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1346,8 +1346,7 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
> if (!PageHuge(page))
> continue;
> head = compound_head(page);
> - if (hugepage_migration_supported(page_hstate(head)) &&
> - page_huge_active(head))
> + if (page_huge_active(head))
> return pfn;
> skip = (1 << compound_order(head)) - (page - head);
> pfn += skip - 1;
>

Yes, it would actually be a BUG once we reach that point and we suddenly
have !hugepage_migration_supported() in my opinion.

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

--

Thanks,

David / dhildenb