release_one_tty(tty) can be called when tty still has a reference
to pgrp/session. In this case we leak the pid.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reported-by: NCatalin Marinas <catalin.marinas@arm.com>
Reported-and-tested-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Acked-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>