4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xunlei Pang <xlpang@xxxxxxxxxx> commit ae83b56a56f8d9643dedbee86b457fa1c5d42f59 upstream. When a contrained task is throttled by dl_check_constrained_dl(), it may carry the remaining positive runtime, as a result when dl_task_timer() fires and calls replenish_dl_entity(), it will not be replenished correctly due to the positive dl_se->runtime. This patch assigns its runtime to 0 if positive after throttling. Signed-off-by: Xunlei Pang <xlpang@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> Cc: Juri Lelli <juri.lelli@xxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Luca Abeni <luca.abeni@xxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Fixes: df8eac8cafce ("sched/deadline: Throttle a constrained deadline task activated after the deadline) Link: http://lkml.kernel.org/r/1494421417-27550-1-git-send-email-xlpang@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/sched/deadline.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -723,6 +723,8 @@ static inline void dl_check_constrained_ if (unlikely(dl_se->dl_boosted || !start_dl_timer(p))) return; dl_se->dl_throttled = 1; + if (dl_se->runtime > 0) + dl_se->runtime = 0; } }