linux-kernel - Re: [PATCH 2/2] mm,memory_hotplug: Drop redundant hugepage_migration

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1b56e6d3-9309-69f3-0ece-228705094975@redhat.com>
Date:   Mon, 4 Mar 2019 10:17:26 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Oscar Salvador <osalvador@...e.de>, akpm@...ux-foundation.org
Cc:     mhocko@...e.com, mike.kravetz@...cle.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 2/2] mm,memory_hotplug: Drop redundant
 hugepage_migration_supported check

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@...e.de>
> Acked-by: Michal Hocko <mhocko@...e.com>
> ---
>  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@...hat.com>

-- 

Thanks,

David / dhildenb