An exiting task or process which didn't do I/O yet have no io context,
elv_unregister() should check it is not NULL.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Acked-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>