Don't bother with -rc1, but bisecting it may be relevant. You might of
course hit the breakage, but it's fairly unlikely.
That said, the whole "error on USB serial device" sounds like it's
squarely in the "oops, kref's are screwed up" corner, and you should talk
to Alan about your particular USB dongle. I bet that bisection would just
show you one of the kref commits (eg 4a90f09b "tty: usb-serial krefs" or
maybe 7d7b93c14 "tty: kref the tty driver object").
Alan, pls help.
Linus
--