[PATCH] mm, vmscan: set shrinker to the left page count

[Chen Feng]

In my platform, there can be cache a lot of memory in
ion page pool. When shrink memory the nr_to_scan to ion
is always to little.
to_scan: 395  ion_pool_cached: 27305

Currently, the shrinker nr_deferred is set to total_scan.
But it's not the real left of the shrinker. Change it to
the freeable - freed.

Signed-off-by: Chen Feng <puck.chen@xxxxxxxxxxxxx>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c4a2f45..1ce3fc4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -357,8 +357,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 	 * manner that handles concurrent updates. If we exhausted the
 	 * scan, there is no need to do an update.
 	 */
-	if (total_scan > 0)
-		new_nr = atomic_long_add_return(total_scan,
+	if (freeable - freed > 0)
+		new_nr = atomic_long_add_return(freeable - freed,
 						&shrinker->nr_deferred[nid]);
 	else
 		new_nr = atomic_long_read(&shrinker->nr_deferred[nid]);
-- 
1.9.1