The following test does not time out for a really really long time, when it should throw TimeoutException immediately.

public class NegativeTimeout {
    public static void main(String[] args) throws Exception {
        FutureTask<Void> task = new FutureTask<>( () -> { return null; } );
        try {
            task.get(Long.MIN_VALUE, TimeUnit.NANOSECONDS);
        } catch (TimeoutException success) {}
    }
}

This is already fixed in the 166CVS, and a test added:
   "Fix underflow when timeout = Long.MIN_VALUE"
   http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/main/java/util/concurrent/FutureTask.java?view=log
   http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/test/tck/FutureTaskTest.java?view=log