On Thu, Jan 2, 2014 at 12:30 PM, John Stultz <john.stu...@linaro.org> wrote:
>
> So something else may be at play. Even with Linus' patch I reproduced a
> similar hang here.
>
> Still chasing it down, but it looks like a seqlock deadlock where we're
> calling read while holding the lock.
Hmm. Only with lockdep, right?
Does lockdep perhaps read the scheduler clock? Afaik, we have
lockstat_clock(), which uses local_clock(), which in turn translates
to sched_clock_cpu(smp_processor_id())..
So if that code now tries to read the scheduler clock when
update_sched_clock() is doing a update and has done a
write_seqcount_begin()...
Linus
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