Re: [PATCH v6 5/5] mm,page_alloc: Drop unnecessary checks from pfn_range_valid_contig

[Michal Hocko]

On Fri 19-03-21 14:20:04, Oscar Salvador wrote:
> pfn_range_valid_contig() bails out when it finds an in-use page or a
> hugetlb page, among other things.
> We can drop the in-use page check since __alloc_contig_pages can migrate
> away those pages, and the hugetlb page check can go too since
> isolate_migratepages_range is now capable of dealing with hugetlb pages.
> Either way, those checks are racy so let the end function handle it
> when the time comes.
> 
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
>  mm/page_alloc.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ce6a14a446a4..516302b280de 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8685,12 +8685,6 @@ static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
>  
>  		if (PageReserved(page))
>  			return false;
> -
> -		if (page_count(page) > 0)
> -			return false;
> -
> -		if (PageHuge(page))
> -			return false;
>  	}
>  	return true;
>  }
> -- 
> 2.16.3

-- 
Michal Hocko
SUSE Labs