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Date: Mon, 18 Feb 2002 22:53:45 -0300 (BRT)
From: Rik van Riel <riel@conectiva.com.br>
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To: Linus Torvalds <torvalds@transmeta.com>
Cc: Daniel Phillips <phillips@bonn-fries.net>, Hugh Dickins <hugh@veritas.com>,
        <dmccr@us.ibm.com>, Kernel Mailing List <linux-kernel@vger.kernel.org>,
        <linux-mm@kvack.org>, Robert Love <rml@tech9.net>, <mingo@redhat.co>,
        Andrew Morton <akpm@zip.com.au>, <manfred@colorfullife.com>,
        <wli@holomorphy.com>
Subject: Re: [RFC] Page table sharing
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On Mon, 18 Feb 2002, Linus Torvalds wrote:
> On Mon, 18 Feb 2002, Rik van Riel wrote:
> >
> > We'll need protection from the swapout code.
>
> Absolutely NOT.
>
> If the swapout code unshares or shares the PMD, that's a major bug.
>
> The swapout code doesn't need to know one way or the other, because the
> swapout code never actually touches the pmd itself, it just follows the
> pointers - it doesn't ever need to worry about the pmd counts at all.

The swapout code can remove a page from the page table
while another process is in the process of unsharing
the page table.

We really want to make sure that the copied-over page
table doesn't point to a page which just got swapped
out.

regards,

Rik
-- 
"Linux holds advantages over the single-vendor commercial OS"
    -- Microsoft's "Competing with Linux" document

http://www.surriel.com/		http://distro.conectiva.com/

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