linux-kernel - Re: [patch] my mmu notifiers

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Message-ID: <20080219231157.GC18912@wotan.suse.de>
Date:	Wed, 20 Feb 2008 00:11:57 +0100
From:	Nick Piggin <npiggin@...e.de>
To:	Andrea Arcangeli <andrea@...ranet.com>
Cc:	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>, steiner@....com,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com, Christoph Lameter <clameter@....com>
Subject: Re: [patch] my mmu notifiers

On Tue, Feb 19, 2008 at 02:58:51PM +0100, Andrea Arcangeli wrote:
> On Tue, Feb 19, 2008 at 09:43:57AM +0100, Nick Piggin wrote:
> > anything when changing the pte to be _more_ permissive, and I don't
> 
> Note that in my patch the invalidate_pages in mprotect can be
> trivially switched to a mprotect_pages with proper params. This will
> prevent page faults completely in the secondary MMU (there will only
> be tlb misses after the tlb flush just like for the core linux pte),
> and it'll allow all the secondary MMU pte blocks (512/1024 at time
> with my PT lock design) to be updated to have proper permissions
> matching the core linux pte.

Sorry, I realise I still didn't get this through my head yet (and also
have not seen your patch recently). So I don't know exactly what you
are doing...

But why does _anybody_ (why does Christoph's patches) need to invalidate
when they are going to be more permissive? This should be done lazily by
the driver, I would have thought.
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