Re: [PATCH] kmemcheck: Disable SLUB and SLAB debugging when kmemcheck is enabled

[Vegard Nossum <vegard.nossum@gmail.com>]

2009/2/23 Pekka Enberg <penberg@cs.helsinki.fi>:
> On Mon, 2009-02-23 at 10:41 -0500, Christoph Lameter wrote:
>> On Mon, 23 Feb 2009, Pekka Enberg wrote:
>>
>> > Enabling kmemcheck in Kconfig is a painful experience. Lets make it a
>> > tad bit easier by inverting the dependencies to SLUB and SLAB debugging.
>> > As kmemcheck is more powerful than slab debugging, disable the latter
>> > functionality if an user enables kmemcheck.
>>
>> SLUB_DEBUG is fundamentally different from SLAB_DEBUG. It only includes
>> the code to be able to enable debugging at runtime. It does not enable
>> debugging.
>
> Yes, I know that but we can't really let the user enable both, slub
> debugging and kmemcheck debugging, at run-time. That's why I used
> SLUB_DEBUG here.

It is possible. Which is why it said SLUB_DEBUG_ON to begin with. This
is how it works:

If slub_debug=,xyz is specified on the command line, the SLUB
debugging will be used for the "xyz" cache, and kmemcheck will track
the rest (all non-slub-debugged caches). So if we only disable
SLUB_DEBUG_ON, then slub debugging and kmemcheck debugging can still
be mixed at boot-time, but kmemcheck will take precedence unless
slub_debug= is specified.

Can you rethink whether SLUB_DEBUG or SLUB_DEBUG_ON is the one we
really want to depend on !KMEMCHECK, and either submit a new patch or
convince me that this is sufficient?

Thanks!


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