https://bugzilla.kernel.org/show_bug.cgi?id=101391
--- Comment #6 from Michel Dänzer michel@daenzer.net --- "No more bad commits" isn't necessarily a problem. Just keep testing the commits you get from running "git bisect good/bad" according to the test result with the previous commit, until the process is finished and it prints out which commit seems to have introduced the problem.
FWIW, it's better not to limit the bisection to a sub-tree.