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Date: Wed, 23 Mar 2005 13:10:42 +1100
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: "David S. Miller" <davem@davemloft.net>
CC: Andrew Morton <akpm@osdl.org>, hugh@veritas.com, tony.luck@intel.com,
       benh@kernel.crashing.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] freepgt: free_pgtables use vma list
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David S. Miller wrote:

>On Tue, 22 Mar 2005 17:10:13 -0800
>Andrew Morton <akpm@osdl.org> wrote:
>
>
>>Hugh Dickins <hugh@veritas.com> wrote:
>>
>>>On Tue, 22 Mar 2005, Luck, Tony wrote:
>>> > 
>>> > But I'm still confused by all the math on addr/end at each
>>> > level.
>>>
>>> You think the rest of us are not ;-?
>>>
>>umm, given the difficulty which you guys are having with this, I get a bit
>>worried about clarity, simplicity and maintainability of the end result.
>>
>
>We're working on it, trust me :-)
>
>I have a simplification in mind that should take care of the issue
>that led us to these problems.  We should simply pass in "ceiling"
>as "-1" instead of "0".  Every single test against ceiling is
>really done against "ceiling - 1".
>
>Therefore, passing ceiling in as "top - 1" and then adjusting the
>tests will clean this up substantially and make is much simpler.
>
>

The ugly thing you get with an inclusive ceiling is that your masking
becomes more difficult I think.

I might try to attack this from another angle and see if I can come up
with something.