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Date: Fri, 3 Oct 2003 22:47:27 -0700
From: "David S. Miller" <davem@redhat.com>
To: Andrew Morton <akpm@osdl.org>
Cc: joe.korty@ccur.com, linux-kernel@vger.kernel.org, riel@redhat.com,
       andrea@suse.de
Subject: Re: mlockall and mmap of IO devices don't mix
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On Fri, 3 Oct 2003 17:27:27 -0700
Andrew Morton <akpm@osdl.org> wrote:

> Maybe it's best to not overload VM_RESERVED in this manner, but to always
> mark /dev/mem as VM_IO. 

Just in cast is isn't clear, it should be defined that anything
that sets VM_IO on an mmap() area should prefill the page tables
as a side effect of such a mmap() request.

Then things like mlockall() have simple semantics on VM_IO area, they
end up being a nop.