linux-kernel - Re: [patch 2/3] mmu_notifier: Callbacks to invalidate address ranges

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Message-ID: <20080201103737.GI26420@sgi.com>
Date:	Fri, 1 Feb 2008 04:37:38 -0600
From:	Robin Holt <holt@....com>
To:	Christoph Lameter <clameter@....com>
Cc:	Robin Holt <holt@....com>, Andrea Arcangeli <andrea@...ranet.com>,
	Avi Kivity <avi@...ranet.com>, Izik Eidus <izike@...ranet.com>,
	kvm-devel@...ts.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, steiner@....com,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com
Subject: Re: [patch 2/3] mmu_notifier: Callbacks to invalidate address
	ranges

On Fri, Feb 01, 2008 at 04:32:21AM -0600, Robin Holt wrote:
> On Thu, Jan 31, 2008 at 08:43:58PM -0800, Christoph Lameter wrote:
> > On Thu, 31 Jan 2008, Robin Holt wrote:
> > 
> > > > Index: linux-2.6/mm/memory.c
> > > ...
> > > > @@ -1668,6 +1678,7 @@ gotten:
> > > >  		page_cache_release(old_page);
> > > >  unlock:
> > > >  	pte_unmap_unlock(page_table, ptl);
> > > > +	mmu_notifier(invalidate_range_end, mm, 0);
> > > 
> > > I think we can get an _end call without the _begin call before it.
> > 
> > If that would be true then also the pte would have been left locked.
> > 
> > We always hit unlock. Maybe I just do not see it?
> 
> Maybe I haven't looked closely enough, but let's start with some common
> assumptions.  Looking at do_wp_page from 2.6.24 (I believe that is what
> my work area is based upon).  On line 1559, the function begins being
> declared.
> 
> On lines 1614 and 1630, we do "goto unlock" where the _end callout is
> soon made.  The _begin callout does not come until after those branches
> have been taken (occurs on line 1648).
> 
> Thanks,
> Robin

Ignore this thread, I am going to throw a patch against the new version.

Thanks,
Robin
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