linux-kernel - Re: [RFC/PATCH 3/3] SLOB: make ksize() more strict for page allocator pass-through

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Message-Id: <1211396840.18026.276.camel@calx>
Date:	Wed, 21 May 2008 14:07:20 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Pekka J Enberg <penberg@...helsinki.fi>
Cc:	linux-kernel@...r.kernel.org, clameter@....com,
	lethal@...ux-sh.org, dhowells@...hat.com
Subject: Re: [RFC/PATCH 3/3] SLOB: make ksize() more strict for page
	allocator pass-through


On Wed, 2008-05-21 at 21:26 +0300, Pekka J Enberg wrote:
> From: Pekka Enberg <penberg@...helsinki.fi>
> 
> This patch re-uses the PG_slab flag for marking SLOB bigblock pages so we can
> check that the pointer passed ksize() was really allocated by SLOB.

Ok, first, BUG_ON is wrong.

We already know users (ie nommu memory usage reporting) are abusing this
interface. Making them blow up is unnecessary. Just give them wrong
answers. Issuing a warning might be a good idea for debugging.

Second, I'd prefer to keep this sort of debugging code out of SLOB.
SLUB is much better suited to debugging allocator abuse.

-- 
Mathematics is the supreme nostalgia of our time.

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