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]>
---
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);
--
1.8.3.1
