mm/memcg: mz already removed from rb_tree if not NULL

When mz is not NULL, it means mz can either come from
mem_cgroup_largest_soft_limit_node or
__mem_cgroup_largest_soft_limit_node.  And both of them have removed this
node by __mem_cgroup_remove_exceeded().

Not necessary to call __mem_cgroup_remove_exceeded() again.

[mhocko@suse.com: refine changelog]
Link: https://lkml.kernel.org/r/20220314233030.12334-1-richard.weiyang@gmail.comSigned-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcontrol.c

@@ -3418,7 +3418,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 						    gfp_mask, total_scanned);
 		nr_reclaimed += reclaimed;
 		spin_lock_irq(&mctz->lock);
-		__mem_cgroup_remove_exceeded(mz, mctz);
 
 		/*
 		 * If we failed to reclaim anything from this memory cgroup