Re: Plea for help

[Micha Feigin <michf-+lLcF8/aw9x6auLlOhE+pQ@public.gmane.org>]

On Thu, Dec 18, 2003 at 11:41:13PM -0600, Ian Pilcher wrote:
> I posted a couple of weeks ago about a kernel panic that shows up when I
> boot my Abit VP6 (dual-PIII) with ACPI turned on.  It turns out that the
> kernel boots just fine with ACPI on when I build it with
> CONFIG_DEBUG_SLAB=y.
> 
> Alan Cox suggested that this is probably due to code that kmallocs
> memory and then relies on its content without clearing it, but I never
> received any response to my request for suggestions on how to identify
> the offending code.
> 
> I've just spent several hours adding printk statements to the ACPI code,
> and I've reached a point where the oops message is overwriting portions
> of my printk messages.  I have the sinking feeling that this indicates
> that the process executing the ACPI code is not the one that's oops'ing.
> 
> I'm stuck.  How can a relative newbie debug a problem like this, or at
> least gather enough information to enable someone with more expertise to
> do so?
> 

If you say that CONFIG_DEBUG_SLAB=y solves the problem, you could start
by grepping in the kernel for CONFIG_DEBUG_SLAB and see what its doing.
This sounds like one of two things.
Either CONFIG_DEBUG_SLAB=y clears some memory which isn't cleared
properly somewhere else (there are quite a few kernel structures that
are allocated as slabs iirc), or its a timing problem that
CONFIG_DEBUG_SLAB solves by adding a printk somewhere that causes a
short delay (the second one will probably be a lot harder to solve).
I'll see if I have some time to look at it later.

> TIA.
> -- 
> ========================================================================
> Ian Pilcher                                        i.pilcher-Wuw85uim5zDR7s880joybQ@public.gmane.org
> ========================================================================
> 
> 
> 
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