My laptop is Thinkpad x220, installed with Ubuntu 12.04, gnome 3 desktop.
It can normally shutdown before. But yesterday, it can not shutdown when on battery(neither use
power off button nor
shutdown command), but on AC power, it still shutdown normally. So can anybody give me some suggestion?
I didn't install any software update before the problem occured.
UPDATE1: there's no error, it just stuck in the shutdown screen, the cpu was still working, but there was no disk io at all.
UPDATE2: I've post the the dmesg output to pastebin