Messages in this thread | | | Date | Thu, 11 Apr 2013 10:10:54 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] CPU hotplug, smpboot: Fix crash in smpboot_thread_fn() |
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On Wed, 10 Apr 2013, Srivatsa S. Bhat wrote:
> Interestingly, in every single stack trace, the crashing task is the migration > thread. Now, migration thread belongs to the highest priority stop_task sched > class, and this particular sched class is very unique in the way it implements > its internal sched class functions, and I suspect this has a lot of bearing > on how functions like kthread_bind(), wake_up_process() etc react with it > (by looking at how it implements its functions such as select_task_rq(), > enqueue_task(), dequeue_task() etc).
I don't think that's relevant. The migration thread can only be woken via try_to_wakeup and my previous patch which implements a separate task state makes sure that it cannot be woken accidentaly by anything else than unpark.
> But note that __kthread_bind() can wake up the task if the task is an RT > task. So it can be called only when the CPU (to which we want to bind the task)
kthread_bind() does NOT wakeup anything. It merily sets the cpus allowed ptr without further ado.
Thanks,
tglx
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