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Date: Tue, 24 Apr 2007 10:48:40 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
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To: Hugh Dickins <hugh@veritas.com>
cc: Andrew Morton <akpm@linux-foundation.org>, Nick Piggin <npiggin@suse.de>,
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Subject: Re: Pagecache: find_or_create_page does not call a proper page
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On Tue, 24 Apr 2007, Hugh Dickins wrote:

> > And if a page is in the wrong area then it can be bounced before I/O 
> > is performed on it.
> 
> I think that much is also true, but not where the problem lies.
> Isn't the problem that filesystems using these block devices
> expect their metadata to be accessible without kmap calls?

Metadata is not movable nor subject to memory policies. It will never be 
mapped into a process space.