[GIT PULL] scheduler fix

[Ingo Molnar]

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 
sched-urgent-for-linus

   # HEAD: a860fa7b96e1a1c974556327aa1aee852d434c21 sched/numa: Fix a possible 
divide-by-zero

Fix a division by zero bug that can trigger in the NUMA placement code.

 Thanks,

        Ingo

------------------>
Xie XiuQi (1):
      sched/numa: Fix a possible divide-by-zero


 kernel/sched/fair.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a4d9e14bf138..35f3ea375084 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2007,6 +2007,10 @@ static u64 numa_get_avg_runtime(struct task_struct *p, 
u64 *period)
        if (p->last_task_numa_placement) {
                delta = runtime - p->last_sum_exec_runtime;
                *period = now - p->last_task_numa_placement;
+
+               /* Avoid time going backwards, prevent potential divide error: 
*/
+               if (unlikely((s64)*period < 0))
+                       *period = 0;
        } else {
                delta = p->se.avg.load_sum;
                *period = LOAD_AVG_MAX;