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

[Oscar Salvador]

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@xxxxxxxxxxxxxxxxxxxx>
> Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> Cc: Scott Cheloha <cheloha@xxxxxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>

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@xxxxxxx>

Thanks

-- 
Oscar Salvador
SUSE L3