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From: Andrea Arcangeli <andrea@qumranet.com>
Subject: [ofa-general] Re: [PATCH] mmu notifiers #v7
Date: Fri, 29 Feb 2008 14:09:05 +0100
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To: Christoph Lameter <clameter@sgi.com>
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On Thu, Feb 28, 2008 at 05:03:01PM -0800, Christoph Lameter wrote:
> I thought you wanted to get rid of the sync via pte lock?

Sure. _notify is happening inside the pt lock by coincidence, to
reduce the changes to mm/* as long as the mmu notifiers aren't
sleep capable.

> What changes to do_wp_page do you envision?

Converting it to invalidate_range_begin/end.

> What is the trouble with the current do_wp_page modifications? There is 
> no need for invalidate_page() there so far. invalidate_range() does the 
> trick there.

No trouble, it's just that I didn't want to mangle over the logic of
do_wp_page unless it was strictly required, the patch has to be
obviously safe. You need to keep that bit of your patch to make the
mmu notifiers sleepable.