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

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Message-Id: <1229618308.16418.50.camel@pc1117.cambridge.arm.com>
Date:	Thu, 18 Dec 2008 16:38:28 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	linux-kernel@...r.kernel.org, cl@...ux-foundation.org
Subject: Re: [PATCH 03/15] kmemleak: Add the slab memory allocation/freeing
	hooks

On Thu, 2008-12-18 at 12:46 +0200, Pekka Enberg wrote:
> On Fri, 2008-12-12 at 14:27 +0000, Catalin Marinas wrote:
> > > Do you take care of the per-node lists as well?
> > 
> > I can't figure out what other location should be erased.
> 
> As far as I can tell, you need to tell kmemleak not to scan the alien
> caches and the shared array that is shared by all CPUs that belong to
> one node. I'm adding Christoph to the CC in case he wants to comment on
> this.

In the ____cache_alloc() kmemleak clears the
cachep->array->entry[ac->avail] pointer but this may not be enough as
freed and later re-allocated objects may have pointers in the alien
cache (is that correct?). A better approach (haven't tried it yet) would
be not to scan objects allocated via alloc_arraycache() at all. However,
there is still the initarray_cache/generic which are automatically
scanned via the data section (unless I add an attribute to place them in
a different, not scanned, section).

-- 
Catalin

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