The solaris implementation of thread suspend when the thread is suspending
itself uses

Interrupt_lock->wait(Mutex::_no_safepoint_check_flag);

Interrupt_lock is defined as a special mutex

  def(Interrupt_lock , Monitor, special, true );
// used for suspension/resumption

The monitor wait code has an assertion check that the priority of the
mutex is greater than leaf (which special is not).

bool Monitor::wait(bool no_safepoint_check, long timeout) {
os::Solaris::Event* const _Lock_Event = (os::Solaris::Event*)_lock_event;

assert(_owner != INVALID_THREAD, "Wait on unknown thread");
assert(_owner == Thread::current(), "Wait on Monitor not by owner");
assert(priority() > leaf, "priority to low to do a wait");

Is the assertion in Monitor::wait too strong? Should the Interrupt_lock
be created with a higher priority?