On Tue, Feb 11, 2014 at 04:34:38PM +0100, Thomas Gleixner wrote: > I could slap myself for not writing a proper changelog right away. It > took me some time to figure out why it was added in the first place, > why it's not longer necessary and why I kept it.
:-) Thanks! --- Subject: sched: Init idle->on_rq in init_idle() From: Thomas Gleixner <[email protected]> Date: Fri, 7 Feb 2014 20:58:37 +0100 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 :) Cc: Ingo Molnar <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected] --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4443,6 +4443,7 @@ void init_idle(struct task_struct *idle, rcu_read_unlock(); rq->curr = rq->idle = idle; + idle->on_rq = 1; #if defined(CONFIG_SMP) idle->on_cpu = 1; #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
