linux-kernel - Re: Extending mmu_notifiers to handle __xip

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Message-ID: <Pine.LNX.4.64.0802011115180.18163@schroedinger.engr.sgi.com>
Date:	Fri, 1 Feb 2008 11:17:08 -0800 (PST)
From:	Christoph Lameter <clameter@....com>
To:	Robin Holt <holt@....com>
cc:	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: Extending mmu_notifiers to handle __xip_unmap in a sleepable
 context?

On Fri, 1 Feb 2008, Robin Holt wrote:

> Currently, it is calling mmu_notifier _begin and _end under the
> i_mmap_lock.  I _THINK_ the following will make it so we could support
> __xip_unmap (although I don't recall ever seeing that done on ia64 and
> don't even know what the circumstances are for its use).

Its called under lock yes.

The problem with this fix is that we currently have the requirement that 
the rmap invalidate_all call requires the pagelock to be held. That is not 
the case here. So I used _begin/_end to skirt the issue.

If you do not need the Pagelock to be held (it holds off modifications on 
the page!) then we are fine.

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