On Mon, 9 May 2016 12:11:31 +0800 Xunlei Pang <[email protected]> wrote:
> We got a warning below: > WARNING: CPU: 1 PID: 2468 at kernel/sched/core.c:1161 > set_task_cpu+0x1af/0x1c0 > CPU: 1 PID: 2468 Comm: bugon Not tainted 4.6.0-rc3+ #16 > Hardware name: Intel Corporation Broadwell Client > 0000000000000086 0000000089618374 ffff8800897a7d50 ffffffff8133dc8c > 0000000000000000 0000000000000000 ffff8800897a7d90 ffffffff81089921 > 0000048981037f39 ffff88016c4315c0 ffff88016ecd6e40 0000000000000000 > Call Trace: > [<ffffffff8133dc8c>] dump_stack+0x63/0x87 > [<ffffffff81089921>] __warn+0xd1/0xf0 > [<ffffffff81089a5d>] warn_slowpath_null+0x1d/0x20 > [<ffffffff810b48ff>] set_task_cpu+0x1af/0x1c0 > [<ffffffff810cc90a>] push_dl_task.part.34+0xea/0x180 > [<ffffffff810ccd17>] push_dl_tasks+0x17/0x30 > [<ffffffff8118d17a>] __balance_callback+0x45/0x5c > [<ffffffff810b2f46>] __sched_setscheduler+0x906/0xb90 > [<ffffffff810b6f50>] SyS_sched_setattr+0x150/0x190 > [<ffffffff81003c12>] do_syscall_64+0x62/0x110 > [<ffffffff816b5021>] entry_SYSCALL64_slow_path+0x25/0x25 > > The corresponding warning triggering code: > WARN_ON_ONCE(p->state == TASK_RUNNING && > p->sched_class == &fair_sched_class && > (p->on_rq && !task_on_rq_migrating(p))) > > This is because in find_lock_later_rq(), the task whose scheduling > class was changed to fair class is still pushed away as deadline. > > So, check in find_lock_later_rq() after double_lock_balance(), if the > scheduling class of the deadline task was changed, break and retry. > Apply the same logic to RT. > > Signed-off-by: Xunlei Pang <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> -- Steve > --- > kernel/sched/deadline.c | 1 + > kernel/sched/rt.c | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 169d40d..57eb3e4 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -1385,6 +1385,7 @@ static struct rq *find_lock_later_rq(struct task_struct > *task, struct rq *rq) > !cpumask_test_cpu(later_rq->cpu, > &task->cpus_allowed) || > task_running(rq, task) || > + !dl_task(task) || > !task_on_rq_queued(task))) { > double_unlock_balance(rq, later_rq); > later_rq = NULL; > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index ecfc83d..c10a6f5 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -1720,6 +1720,7 @@ static struct rq *find_lock_lowest_rq(struct > task_struct *task, struct rq *rq) > !cpumask_test_cpu(lowest_rq->cpu, > tsk_cpus_allowed(task)) > || > task_running(rq, task) || > + !rt_task(task) || > !task_on_rq_queued(task))) { > > double_unlock_balance(rq, lowest_rq);
