Re: acpi_button: random oops on boot

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Tue, Dec 07, 2010 at 12:54:59AM +0100, Tobias Karnat wrote:
> Am Montag, den 06.12.2010, 16:26 -0700 schrieb Bjorn Helgaas:
> > On Monday, December 06, 2010 04:01:43 pm Tobias Karnat wrote:
> > > No, it only crashes on boot (without the printk patch).
> > > If it happens the machine is completely dead, SysRq does not work.
> > > 
> > > However it is definitely the acpi_button module, because removing it
> > > also fixes this.
> > 
> > If it crashes on boot (not when loading an acpi_button module),
> > you must be building acpi_button into the static kernel.
> 
> It does crash on boot either if built-in to the kernel or as a module,
> However it does not crash if the module is loaded/unloaded after the
> machine has booted.
> 
> > The acpi_button driver has a fairly complicated add() method.
> > In the absence of a better idea, I might just comment out blocks
> > of it and try to isolate the problem.  For example, take out
> > all the input stuff, take out the wakeup GPE stuff, take out
> > the type/name setup, etc.
> 
> Couldn't this be a compiler issue?
> Adding some printk's to fix it seems to be insane.

Agreed, adding printk's is absolutely not any kind of fix.
I think it's more likely to be some sort of memory corruption or
race than a compiler problem.  I assume there is some old kernel
that works fine, even when compiled with the same compiler.

In addition to the isolation ideas I suggested above, you might
boot with "maxcpus=1" and turn on all the Kconfig memory debug
switches.

Bjorn