mm/slab: drain the free slab as much as possible

slabs_tofree() implies freeing all free slab.  We can do it with just
providing INT_MAX.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -895,12 +895,6 @@ static int init_cache_node_node(int node)
 	return 0;
 }
 
-static inline int slabs_tofree(struct kmem_cache *cachep,
-						struct kmem_cache_node *n)
-{
-	return (n->free_objects + cachep->num - 1) / cachep->num;
-}
-
 static void cpuup_canceled(long cpu)
 {
 	struct kmem_cache *cachep;
@@ -965,7 +959,7 @@ free_slab:
 		n = get_node(cachep, node);
 		if (!n)
 			continue;
-		drain_freelist(cachep, n, slabs_tofree(cachep, n));
+		drain_freelist(cachep, n, INT_MAX);
 	}
 }
 
@@ -1117,7 +1111,7 @@ static int __meminit drain_cache_node_node(int node)
 		if (!n)
 			continue;
 
-		drain_freelist(cachep, n, slabs_tofree(cachep, n));
+		drain_freelist(cachep, n, INT_MAX);
 
 		if (!list_empty(&n->slabs_full) ||
 		    !list_empty(&n->slabs_partial)) {
@@ -2311,7 +2305,7 @@ int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate)
 
 	check_irq_on();
 	for_each_kmem_cache_node(cachep, node, n) {
-		drain_freelist(cachep, n, slabs_tofree(cachep, n));
+		drain_freelist(cachep, n, INT_MAX);
 
 		ret += !list_empty(&n->slabs_full) ||
 			!list_empty(&n->slabs_partial);