linux-kernel - Re: [PATCH 3/4] kmemcheck v4

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Date:	Thu, 14 Feb 2008 22:18:16 +0200
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Vegard Nossum <vegard.nossum@...il.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Daniel Walker <dwalker@...sta.com>,
	Ingo Molnar <mingo@...e.hu>,
	Richard Knutsson <ricknu-0@...dent.ltu.se>,
	Andi Kleen <andi@...stfloor.org>,
	Christoph Lameter <clameter@....com>
Subject: Re: [PATCH 3/4] kmemcheck v4

Vegard Nossum wrote:
>  From 4ce1c09e38b2402dc04f0246916f3c23abe8f3e1 Mon Sep 17 00:00:00 2001
> From: Vegard Nossum <vegard.nossum@...il.com>
> Date: Thu, 14 Feb 2008 19:25:39 +0100
> Subject: [PATCH] kmemcheck: make SLUB use kmemcheck
> 
> With kmemcheck enabled, SLUB needs to do this:
> 
> 1. Request twice as much memory as would normally be needed. The bottom 
> half
>    of the memory is what the user actually sees and uses; the upper half
>    contains the so-called shadow memory, which stores the status of each 
> byte
>    in the bottom half, e.g. initialized or uninitialized.
> 2. Tell kmemcheck which parts of memory that should be marked 
> uninitialized.
>    There are actually a few more states, such as "not yet allocated" and
>    "recently freed".
> 
> If a slab cache is set up using the SLAB_NOTRACK flag, it will never return
> memory that can take page faults because of kmemcheck.
> 
> If a slab cache is NOT set up using the SLAB_NOTRACK flag, callers can 
> still
> request memory with the __GFP_NOTRACK flag. This does not prevent the page
> faults from occuring, however, but marks the object in question as being
> initialized so that no warnings will ever be produced for this object.
> 
> Signed-off-by: Vegard Nossum <vegardno@....uio.no>

Looks good to me.

Reviewed-by: Pekka Enberg <penberg@...helsinki.fi>
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