linux-kernel - Re: acpi_button: random oops on boot

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Message-Id: <20101207084405.e71289cd.Richard.Coe@med.ge.com>
Date:	Tue, 7 Dec 2010 08:44:05 -0600
From:	Rich Coe <Richard.Coe@....ge.com>
To:	Bjorn Helgaas <bjorn.helgaas@...com>
Cc:	Tobias Karnat <tobias.karnat@...glemail.com>,
	linux-acpi@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: acpi_button: random oops on boot

I agree that it's a timing race condition.  I had an earlier version of
acpi-button with printf's that masked the issue from happening.

Rich

On Mon, 6 Dec 2010 22:15:21 -0700
Bjorn Helgaas <bjorn.helgaas@...com> wrote:
> 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
> 


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