There seems to be a thread waiting indefinitely in krbd.cc
We recently encountered this issue where rbd map hangs. From the thread trace we identified this piece of code:
if (poll(fds, 1, -1) < 0)
in krbd.cc does not have a timeout associated with it. It might be nicer to have some timeout even if it is 2-3 minutes otherwise the call hangs forever.
if (poll(fds, 1, 120000) < 0)