Re: [PATCH v2 6/7] mm, page_alloc: move draining pcplists to page isolation users

[Oscar Salvador]

On Thu, Oct 08, 2020 at 01:42:00PM +0200, Vlastimil Babka wrote:
> Currently, pcplists are drained during set_migratetype_isolate() which means
> once per pageblock processed start_isolate_page_range(). This is somewhat
> wasteful. Moreover, the callers might need different guarantees, and the
> draining is currently prone to races and does not guarantee that no page
> from isolated pageblock will end up on the pcplist after the drain.
> 
> Better guarantees are added by later patches and require explicit actions
> by page isolation users that need them. Thus it makes sense to move the
> current imperfect draining to the callers also as a preparation step.
> 
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Suggested-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>

-- 
Oscar Salvador
SUSE L3