linux-kernel - Re: [bug, netconsole, SLUB] BUG skbuff_head

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Message-ID: <19f34abd0807210403n1bca348fn83773b55a08b7993@mail.gmail.com>
Date:	Mon, 21 Jul 2008 13:03:50 +0200
From:	"Vegard Nossum" <vegard.nossum@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Evgeniy Polyakov" <johnpol@....mipt.ru>,
	"Pekka Enberg" <penberg@...helsinki.fi>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	"Rafael J. Wysocki" <rjw@...k.pl>, cl@...ux-foundation.org,
	davem@...emloft.net
Subject: Re: [bug, netconsole, SLUB] BUG skbuff_head_cache: Poison overwritten

On Mon, Jul 21, 2008 at 12:50 PM, Ingo Molnar <mingo@...e.hu> wrote:
> the problem is, most of the crashes dont come with any usable dump. This
> is a laptop so netconsole is the only reliable route out - and if
> something in networking crashes chances are that it hoses netconsole
> before it can get anything out.
>
> Another thing is that i'm activating netconsole on this box via a kernel
> boot line and from within a bzImage (to get it activated as early as
> possible) - maybe that's a tad too early for certain initialization
> sequences?
>
> I could try run tests with netconsole deactivated, if you think that's a
> worthwile line of probing this problem. (although that would make me do
> blind tests in essence - having kernel log output is really essential.)

How about posting your custom patches for public review? :-D

(There was recently an odd case of kzalloc() succeeding even though it
was called before the slab caches were initialized -- and it only
generated a warning about irqs-on happening too early. I just mean to
say that it _can_ happen. On another machine, it crashed
spectacularly. I guess you're not enabling the netconsole before slab
allocator is up?)


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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