sched: fix mult overflow

It was observed these mults can overflow.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched_fair.c

@@ -1477,16 +1477,16 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
 		struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
 		unsigned long busiest_h_load = busiest_cfs_rq->h_load;
 		unsigned long busiest_weight = busiest_cfs_rq->load.weight;
-		long rem_load, moved_load;
+		u64 rem_load, moved_load;
 
 		/*
 		 * empty group
 		 */
 		if (!busiest_cfs_rq->task_weight)
 			continue;
 
-		rem_load = rem_load_move * busiest_weight;
-		rem_load /= busiest_h_load + 1;
+		rem_load = (u64)rem_load_move * busiest_weight;
+		rem_load = div_u64(rem_load, busiest_h_load + 1);
 
 		moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
 				rem_load, sd, idle, all_pinned, this_best_prio,
@@ -1496,7 +1496,7 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
 			continue;
 
 		moved_load *= busiest_h_load;
-		moved_load /= busiest_weight + 1;
+		moved_load = div_u64(moved_load, busiest_weight + 1);
 
 		rem_load_move -= moved_load;
 		if (rem_load_move < 0)