Re: [PATCH RFC 3/4] mm/page_alloc: always move pages to the tail of the freelist in unset_migratetype_isolate()

Oscar Salvador
2020-09-25T13:57:55Z

On Wed, Sep 16, 2020 at 08:34:10PM +0200, David Hildenbrand wrote:
> Page isolation doesn't actually touch the pages, it simply isolates
> pageblocks and moves all free pages to the MIGRATE_ISOLATE freelist.
>
> We already place pages to the tail of the freelists when undoing
> isolation via __putback_isolated_page(), let's do it in any case
> (e.g., if order == pageblock_order) and document the behavior.
>
> This change results in all pages getting onlined via online_pages() to
> be placed to the tail of the freelist.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Scott Cheloha <cheloha@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: David Hildenbrand <david@redhat.com>

LGTM.
Feel the same way about move_freepages_block_tail/move_freepages_block_tail
wrappers, I think we are better off without them.

Reviewed-by: Oscar Salvador <osalvador@suse.de>

Thanks

--
Oscar Salvador
SUSE L3