Re: Stable regression: usb-storage is stuck in 2.6.26.5

[Michael Tokarev <mjt@tls.msk.ru>]

Michael Tokarev wrote:
> Just updated my machine from 2.6.26.1 to 2.6.26.5, and it does not
> wan to boot anymore.  It says "Initializing USB Mass Storage driver.."
> (when trying to load usb-storage module) and sits here forever, every
> 2 minutes showing warnings about stuck processes (traces below).
> With 2.6.26.1 or any previous version I never experienced this
> problem.  Both 32- and 64-bits kernels behave the same way.
> While waiting for usb-storage to complete, no other USB devices
> works (incl. mouse and keyboard).
> 
> The machine is an AMD X2-64 (BE-2400) processor with an nVidia MCP51
> chipset (lspci is below).  Motherboard is Asus M2NPV-VM, latest BIOS
> (1401, dated 08/07/2008)
> 
> I'm rebuilding 2.6.26.3 for now -- trying to bisect the issue...
[...]

And it's more: even without usb-storage, other USB devices does
not work, waiting in the same usb_start_wait_urb.

Ok, it turned out to be pretty.. interesting.

It's not a regression within -stable kernel series.  The problem
happens when BOTH are true:

   - using latest BIOS for this mobo (1401), AND
   - enabling KVM_GUEST in kernel.

The only difference in my kernel config between .1 and .5 was
to enable KVM_GUEST and KVM_CLOCK, and also I2C_HELPER_AUTO
which was added by kernel update.

Going with previous BIOS (1201) OR disabling PARAVIRT_GUEST
fixes the problem.  I'll try to figure out which config
option is at problem here.

> Thanks.
> 
> /mjt
>