[Intel-gfx] [PATCH] mm: Reward slab shrinkers that reclaim more than they were asked

[Chris Wilson]

Some shrinkers may only be able to free a bunch of objects at a time, and
so free more than the requested nr_to_scan in one pass. Account for the
extra freed objects against the total number of objects we intend to
free, otherwise we may end up penalising the slab far more than intended.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Johannes Weiner <hannes at cmpxchg.org>
Cc: Hillf Danton <hillf.zj at alibaba-inc.com>
Cc: Minchan Kim <minchan at kernel.org>
Cc: Vlastimil Babka <vbabka at suse.cz>
Cc: Mel Gorman <mgorman at techsingularity.net>
Cc: Shaohua Li <shli at fb.com>
Cc: linux-mm at kvack.org
---
 mm/vmscan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a1af041930a6..8bf6f41f94fb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -398,6 +398,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 			break;
 		freed += ret;
 
+		nr_to_scan = max(nr_to_scan, ret);
 		count_vm_events(SLABS_SCANNED, nr_to_scan);
 		total_scan -= nr_to_scan;
 		scanned += nr_to_scan;
-- 
2.13.3