linux-kernel - Re: [PATCH] x86, amd, mce: Prevent potential cpu-online oops

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Date:	Tue, 09 Apr 2013 11:25:16 +0200
From:	Steffen Persvold <sp@...ascale.com>
To:	Borislav Petkov <bp@...en8.de>,
	Daniel J Blueman <daniel@...ascale-asia.com>,
	Tony Luck <tony.luck@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, amd, mce: Prevent potential cpu-online oops

On 4/4/2013 9:07 PM, Borislav Petkov wrote:
> On Thu, Apr 04, 2013 at 08:05:46PM +0200, Steffen Persvold wrote:
>> It made more sense (to me) to skip the creation of MC4 all together
>> if you can't find the matching northbridge since you can't reliably
>> do the dec_and_test() reference counting on the shared bank when you
>> don't have the common NB struct for all the shared cores.
>>
>> Or am I just smoking the wrong stuff ?
>
> No, actually *this* explanation should've been in the commit message.
> You numascale people do crazy things with the hardware :) so explaining
> yourself more verbosely is an absolute must if anyone is to understand
> why you're changing the code.
>

Boris,

A question came up. Why have this "shared" bank concept for the kobjects 
at all ? What's the advantage ? Before our patch, when running on our 
architecture but without pci domains for "slave" servers, everything was 
working fine except the de-allocation oops due to the NULL pointer when 
offlining cores.

Why not let all cores just create their individual kobject and skip this 
"shared" nb->bank4 concept ? Any disadvantage to that (apart from the 
obvious storage bloat?).

Cheers,
Steffen


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