linux-kernel - Re: [PATCH 03/15] kmemleak: Add the slab memory allocation/freeing hooks

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Message-ID: <84144f020812181206o3d85fbd3t6b30346d7cf76d9d@mail.gmail.com>
Date:	Thu, 18 Dec 2008 22:06:21 +0200
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	"Christoph Lameter" <cl@...ux-foundation.org>
Cc:	"Catalin Marinas" <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/15] kmemleak: Add the slab memory allocation/freeing hooks

On Thu, Dec 18, 2008 at 9:35 PM, Christoph Lameter
<cl@...ux-foundation.org> wrote:
> On Thu, 18 Dec 2008, Catalin Marinas wrote:
>
>> OK, but is there a chance that an stale pointer remains in such caches?
>
> Definitely. The pointers are never cleared. There are counters in the
> caches that are used to index into an array.
>
>> There seems to be the transfer_objects() function that moves pointers
>> around but doesn't clear the source values.
>
> No need to. The counter updates take care of things.

For kmemleak, that's a problem. Unless we explicitly annotate the
caches, it will scan them and think that there's a pointer to a leaked
object (i.e. false negative). Catalin already took care of the per-CPU
caches but AFAICT we still need to take care of the per-node caches
and the shared caches.
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