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

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Date:	Fri, 18 Jul 2008 08:54:56 -0500
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	Pekka Enberg <penberg@...helsinki.fi>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, Vegard Nossum <vegard.nossum@...il.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, davem@...emloft.net,
	johnpol@....mipt.ru
Subject: Re: [bug, netconsole, SLUB] BUG skbuff_head_cache: Poison overwritten

Pekka Enberg wrote:
> On Fri, Jul 18, 2008 at 12:11 PM, Ingo Molnar <mingo@...e.hu> wrote:
>> * Pekka J Enberg <penberg@...helsinki.fi> wrote:
>>
>>>>   Object 0xf658ae70:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>>> It's bit unfortunate that we don't see full dump of the corruption
>>> here because SLUB limits the output to 128 bytes. Ingo, you might want
>>> to try this patch so that we can see all of it:
>> ok, applied this as a debug special to tip/out-of-tree - future
>> incidents should have the full object dump.
>>
>> would makes sense for upstream too i think, or increase the limit to 4K
>> or so. (which is still fair to be dumped into a syslog)
> 
> SLUB already limits object sizes to less than PAGE_SIZE so the patch
> should be fine. Christoph, are you okay with this going upstream?

I am fine with the patch. Just be aware that we are going to be shoveling a lot of stuff into the log. The object size can be greater than 4k for non kmalloc slab caches. True in general object sizes are <4k.


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