On Wed, Sep 28, 2016 at 11:07:40AM +0200, Sebastian Andrzej Siewior wrote: > On 2016-09-26 14:32:14 [+0200], Peter Zijlstra wrote: > > --- a/kernel/futex.c > > +++ b/kernel/futex.c > > @@ -1374,9 +1374,8 @@ static int wake_futex_pi(u32 __user *uad > > * scheduled away before the wake up can take place. > > */ > > spin_unlock(&hb->lock); > > - wake_up_q(&wake_q); > > - if (deboost) > > - rt_mutex_adjust_prio(current); > > + > > + rt_mutex_postunlock(&wake_q, deboost); > > This breaks -RT. Before that spin_unlock() you do a preempt_disable() > which means you had one spinlock with enabled preemption and now you get > one unlock with disabled preemption. And this breaks migrate_disable() / > enable (because we take the fast path in the in_atomic() case).
Oh crud, the hb lock is not raw :/
