linux-kernel - Re: [PATCH] mmu notifiers #v7

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Message-ID: <20080229130905.GS8091@v2.random>
Date:	Fri, 29 Feb 2008 14:09:05 +0100
From:	Andrea Arcangeli <andrea@...ranet.com>
To:	Christoph Lameter <clameter@....com>
Cc:	Jack Steiner <steiner@....com>, Nick Piggin <npiggin@...e.de>,
	akpm@...ux-foundation.org, Robin Holt <holt@....com>,
	Avi Kivity <avi@...ranet.com>, Izik Eidus <izike@...ranet.com>,
	kvm-devel@...ts.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	general@...ts.openfabrics.org,
	Steve Wise <swise@...ngridcomputing.com>,
	Roland Dreier <rdreier@...co.com>,
	Kanoj Sarcar <kanojsarcar@...oo.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com
Subject: Re: [PATCH] mmu notifiers #v7

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.
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