rem: panic("mutex_lock failure: mutex %p acquired twice by thread 0x%x\n", mutex, me);
add: panic("mutex_lock failure: mutex %p acquired twice by thread 0x%lx\n", mutex, me);
context: mutex_lock(mutex *mutex){	thread_id me = thread_get_current_thread_id();	if (me == mutex->holder)		panic("mutex_lock failure: mutex %p acquired twice by thread 0x%x\n", mutex, me);	acquire_sem(mutex->sem);	mutex->holder = me;}