mm/memcg: remove unneeded nr_scanned

The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim
always does *total_scanned += nr_scanned.  So we can pass total_scanned
directly to the mem_cgroup_soft_reclaim to simplify the code and save some
cpu cycles of adding nr_scanned to total_scanned.

Link: https://lkml.kernel.org/r/20220328114144.53389-1-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcontrol.c

@@ -3387,7 +3387,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 	int loop = 0;
 	struct mem_cgroup_tree_per_node *mctz;
 	unsigned long excess;
-	unsigned long nr_scanned;
 
 	if (order > 0)
 		return 0;
@@ -3415,11 +3414,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 		if (!mz)
 			break;
 
-		nr_scanned = 0;
 		reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
-						    gfp_mask, &nr_scanned);
+						    gfp_mask, total_scanned);
 		nr_reclaimed += reclaimed;
-		*total_scanned += nr_scanned;
 		spin_lock_irq(&mctz->lock);
 		__mem_cgroup_remove_exceeded(mz, mctz);