Daemonized kernel threads run in the init's session. This doesn't match the
behaviour of kthread_create()'ed threads, and this is one of the 2 reasons
why we need a special hack in sys_setsid().

Now that set_special_pids() was changed to use struct pid, not pid_t, we can
use init_struct_pid and set 0,0 special pids.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>