Messages in this thread Patch in this message | | | Date | Sat, 22 Feb 2014 10:01:54 -0800 | From | tip-bot for Thomas Gleixner <> | Subject | [tip:sched/core] sched: Init idle->on_rq in init_idle() |
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Commit-ID: 77177856e3bf39d435b3ae4bfd164ca3c8cd4577 Gitweb: http://git.kernel.org/tip/77177856e3bf39d435b3ae4bfd164ca3c8cd4577 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Fri, 7 Feb 2014 20:58:37 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Sat, 22 Feb 2014 18:07:36 +0100
sched: Init idle->on_rq in init_idle()
We stumbled in RT over a SMP bringup issue on ARM where the idle->on_rq == 0 was causing try_to_wakeup() on the other cpu to run into nada land.
After adding that idle->on_rq = 1; I was able to find the root cause of the lockup: the idle task on the newly woken up cpu was fiddling with a sleeping spinlock, which is a nono.
I kept the init of idle->on_rq to keep the state consistent and to avoid another long lasting debug session.
As a side note, the whole debug mess could have been avoided if might_sleep() would have yelled when called from the idle task. That's fixed with patch 2/6 - and that one actually has a changelog :)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-2-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 49db434..06da865 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4443,6 +4443,7 @@ void init_idle(struct task_struct *idle, int cpu) rcu_read_unlock(); rq->curr = rq->idle = idle; + idle->on_rq = 1; #if defined(CONFIG_SMP) idle->on_cpu = 1; #endif
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