Hello!
> We actually need to do something about this, as we might loop for ever
> there. The robust cleanup code can fail (e.g. due to list corruption)
> and we would see exit_state != 0 and the OWNER_DIED bit would never be
> set, so we are stuck in a busy loop.
Yes...
It is possible to take read_lock(&tasklist_lock) before:
inc_preempt_count();
curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
dec_preempt_count();
and drop it after lookup_pi_state().
In this case exiting task will set FUTEX_OWNER_DIED, but will
spin in exit_notify(), we will find valid pi_state and go slow path
taking rtmutex.
Alexey
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