2.6.38-11-generic re-introduced old bug on Gateway FX6850-51u

[Aleksandar Milivojevic]

It looks like 2.6.38-11 re-introduced old bug, where kernel would hang
on halt or reboot.  The bug was present on the original kernel shipped
with Ubuntu 11.04 (2.6.38-8, if my memory serves me right), and fixed
in the very next kernel update.  However, with 2.6.38-11, the problem
is back.

In short, at the very end of shutdown sequence, after all file systems
were unmounted, etc, kernel would simply hang.  User have to
long-press power button to physically power cycle the system in order
to recover.  In my case this was mostly an annoyance, but for other
users it may be much more serious problem, as it makes system
impossible to reboot remotely (for obvious reasons).

My system is an Gateway FX6850-51u, with 3.4GHz Intel Core i7-2600
Sandy Bridge quad-core processor, 8GB DDR3 RAM.  It has an Accer
branded motherboard (no identifier of exact motherboard version
printed anywhere on it).  Gateway's website has full system specs
(http://us.gateway.com/gw/en/US/content/model/PT.GBN02.012).  The only
difference from stock system as sold by Gateway is PCI-e WiFi card
removed and replaced with an USB WiFi stick, and hard drive replaced
with an SSD drive.

I saw few older discussions on the mailing list mentioning same
problem on some other systems as well (for example, Dell's).

I'd provide a bit more info, however once the system is power cycled,
there's not much left on the system itself.