From: Thomas Gleixner Date: Fri, 7 Feb 2014 19:58:37 +0000 (+0100) Subject: sched: Init idle->on_rq in init_idle() X-Git-Tag: firefly_0821_release~176^2~4170^2~27 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=77177856e3bf39d435b3ae4bfd164ca3c8cd4577;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1391803122-4425-2-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 49db434a35d0..06da865043ec 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