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Date: Tue, 07 Oct 2008 10:20:57 -0500
From: Christoph Lameter <cl@linux-foundation.org>
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To: Matt Mackall <mpm@selenic.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-mm <linux-mm@kvack.org>,
       Nick Piggin <nickpiggin@yahoo.com.au>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [BUG] SLOB's krealloc() seems bust
References: <1223387841.26330.36.camel@lappy.programming.kicks-ass.net>	 <48EB6D2C.30806@linux-foundation.org> <1223391655.13453.344.camel@calx>
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Matt Mackall wrote:

> We can't dynamically determine whether a pointer points to a kmalloced
> object or not. kmem_cache_alloc objects have no header and live on the
> same pages as kmalloced ones.

Could you do a heuristic check? Assume that this is a kmalloc object and then
verify the values in the small control block? If the values are out of line
then this cannot be a kmalloc'ed object.