1 files changed, 10 insertions, 2 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 03496ebc4553..3a88dee165c0 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -2743,7 +2743,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
 
         /*
          * Consider the group unbalanced when the imbalance is larger
-         * than the average weight of two tasks.
+         * than the average weight of a task.
          *
          * APZ: with cgroup the avg task weight can vary wildly and
          *      might not be a suitable number - should we keep a
@@ -2753,7 +2753,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
         if (sgs->sum_nr_running)
                 avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
 
-        if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task && max_nr_running > 1)
+        if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1)
                 sgs->group_imb = 1;
 
         sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
@@ -3128,6 +3128,14 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
         if (!sds.busiest || sds.busiest_nr_running == 0)
                 goto out_balanced;
 
+        /*
+         * If the busiest group is imbalanced the below checks don't
+         * work because they assumes all things are equal, which typically
+         * isn't true due to cpus_allowed constraints and the like.
+         */
+        if (sds.group_imb)
+                goto force_balance;
+
         /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
         if (idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
                         !sds.busiest_has_capacity)