Ingo Molnar <mi...@kernel.org> writes:
> * Vitaly Kuznetsov <vkuzn...@redhat.com> wrote:
>> Vitaly Kuznetsov <vkuzn...@redhat.com> writes:
>> > A hang on CPU0 onlining after a preceding offlining is observed. Trace
>> > shows that CPU0 is stuck in check_tsc_sync_target() waiting for source
>> > CPU to run check_tsc_sync_source() but this never happens. Source CPU,
>> > in its turn, is stuck on synchronize_sched() which is called from
>> > native_cpu_up() -> do_boot_cpu() -> unregister_nmi_handler().
>> > Fix the issue by moving unregister_nmi_handler() from do_boot_cpu() to
>> > native_cpu_up() after cpu onlining is done.
> Looks like a classic ABBA deadlock, due to the use of synchronize_sched() in
> unregister_nmi_handler(), right?
>> > Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
>> > ---
>> > It's been awile since my v1 submission, no comments so far. Resending.
>> Sorry, but
>> I haven't received a single comment on this since the initial submission
>> on June, 26 - is it so bad? :-)
> So the fix looks good to me at first sight, but wanted to wait for Thomas to
> it - once he gets back from vacation.