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Date: Mon, 6 Aug 2007 11:40:55 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [patch] radix-tree: use indirect bit
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On Thu, 2 Aug 2007 07:24:46 +0200 Nick Piggin <npiggin@suse.de> wrote:

> Rather than sign direct radix-tree pointers with a special bit, sign
> the indirect one that hangs off the root. This means that, given a
> lookup_slot operation, the invalid result will be differentiated from
> the valid (previously, valid results could have the bit either set or
> clear).
> 
> This does not affect slot lookups which occur under lock -- they
> can never return an invalid result. Is needed in future for lockless
> pagecache.

so.. we added 30 bytes of text to radix-tree.o for no purpose?