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From: Robin Holt <holt@sgi.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Robin Holt <holt@sgi.com>, Andrea Arcangeli <andrea@qumranet.com>,
	Avi Kivity <avi@qumranet.com>, Izik Eidus <izike@qumranet.com>,
	kvm-devel@lists.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	steiner@sgi.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, daniel.blueman@quadrics.com
Subject: Re: [patch 2/4] mmu_notifier: Callbacks to invalidate address ranges
Date: Fri, 1 Feb 2008 17:35:28 -0600	[thread overview]
Message-ID: <20080201233528.GE12099@sgi.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0802011517430.20608@schroedinger.engr.sgi.com>

On Fri, Feb 01, 2008 at 03:19:32PM -0800, Christoph Lameter wrote:
> On Fri, 1 Feb 2008, Robin Holt wrote:
> 
> > We are getting this callout when we transition the pte from a read-only
> > to read-write.  Jack and I can not see a reason we would need that
> > callout.  It is causing problems for xpmem in that a write fault goes
> > to get_user_pages which gets back to do_wp_page that does the callout.
> 
> Right. You placed it there in the first place. So we can drop the code 
> from do_wp_page?

No, we need a callout when we are becoming more restrictive, but not
when becoming more permissive.  I would have to guess that is the case
for any of these callouts.  It is for both GRU and XPMEM.  I would
expect the same is true for KVM, but would like a ruling from Andrea on
that.

Thanks,
Robin

WARNING: multiple messages have this Message-ID (diff)
From: Robin Holt <holt-sJ/iWh9BUns@public.gmane.org>
To: Christoph Lameter <clameter-sJ/iWh9BUns@public.gmane.org>
Cc: Andrea Arcangeli <andrea-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
	Peter Zijlstra
	<a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org>,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	steiner-sJ/iWh9BUns@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
	kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
	daniel.blueman-xqY44rlHlBpWk0Htik3J/w@public.gmane.org,
	Robin Holt <holt-sJ/iWh9BUns@public.gmane.org>
Subject: Re: [patch 2/4] mmu_notifier: Callbacks to invalidate address	ranges
Date: Fri, 1 Feb 2008 17:35:28 -0600	[thread overview]
Message-ID: <20080201233528.GE12099@sgi.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0802011517430.20608-RYO/mD75kfhx2SFC9UQUAuF7EQX82lMiAL8bYrjMMd8@public.gmane.org>

On Fri, Feb 01, 2008 at 03:19:32PM -0800, Christoph Lameter wrote:
> On Fri, 1 Feb 2008, Robin Holt wrote:
> 
> > We are getting this callout when we transition the pte from a read-only
> > to read-write.  Jack and I can not see a reason we would need that
> > callout.  It is causing problems for xpmem in that a write fault goes
> > to get_user_pages which gets back to do_wp_page that does the callout.
> 
> Right. You placed it there in the first place. So we can drop the code 
> from do_wp_page?

No, we need a callout when we are becoming more restrictive, but not
when becoming more permissive.  I would have to guess that is the case
for any of these callouts.  It is for both GRU and XPMEM.  I would
expect the same is true for KVM, but would like a ruling from Andrea on
that.

Thanks,
Robin

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WARNING: multiple messages have this Message-ID (diff)
From: Robin Holt <holt@sgi.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Robin Holt <holt@sgi.com>, Andrea Arcangeli <andrea@qumranet.com>,
	Avi Kivity <avi@qumranet.com>, Izik Eidus <izike@qumranet.com>,
	kvm-devel@lists.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	steiner@sgi.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, daniel.blueman@quadrics.com
Subject: Re: [patch 2/4] mmu_notifier: Callbacks to invalidate address ranges
Date: Fri, 1 Feb 2008 17:35:28 -0600	[thread overview]
Message-ID: <20080201233528.GE12099@sgi.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0802011517430.20608@schroedinger.engr.sgi.com>

On Fri, Feb 01, 2008 at 03:19:32PM -0800, Christoph Lameter wrote:
> On Fri, 1 Feb 2008, Robin Holt wrote:
> 
> > We are getting this callout when we transition the pte from a read-only
> > to read-write.  Jack and I can not see a reason we would need that
> > callout.  It is causing problems for xpmem in that a write fault goes
> > to get_user_pages which gets back to do_wp_page that does the callout.
> 
> Right. You placed it there in the first place. So we can drop the code 
> from do_wp_page?

No, we need a callout when we are becoming more restrictive, but not
when becoming more permissive.  I would have to guess that is the case
for any of these callouts.  It is for both GRU and XPMEM.  I would
expect the same is true for KVM, but would like a ruling from Andrea on
that.

Thanks,
Robin

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  reply	other threads:[~2008-02-01 23:35 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-01  5:04 [patch 0/4] [RFC] EMMU Notifiers V5 Christoph Lameter
2008-02-01  5:04 ` Christoph Lameter
2008-02-01  5:04 ` [patch 1/4] mmu_notifier: Core code Christoph Lameter
2008-02-01  5:04   ` Christoph Lameter
2008-02-01 10:55   ` Robin Holt
2008-02-01 10:55     ` Robin Holt
2008-02-01 10:55     ` Robin Holt
2008-02-01 11:04     ` Robin Holt
2008-02-01 11:04       ` Robin Holt
2008-02-01 19:14     ` Christoph Lameter
2008-02-01 19:14       ` Christoph Lameter
2008-02-01 19:14       ` Christoph Lameter
2008-02-01  5:04 ` [patch 2/4] mmu_notifier: Callbacks to invalidate address ranges Christoph Lameter
2008-02-01  5:04   ` Christoph Lameter
2008-02-01 10:49   ` Robin Holt
2008-02-01 10:49     ` Robin Holt
2008-02-01 10:49     ` Robin Holt
2008-02-01 19:14     ` Christoph Lameter
2008-02-01 19:14       ` Christoph Lameter
2008-02-01 19:14       ` Christoph Lameter
2008-02-01 22:09   ` Robin Holt
2008-02-01 22:09     ` Robin Holt
2008-02-01 23:19     ` Christoph Lameter
2008-02-01 23:19       ` Christoph Lameter
2008-02-01 23:35       ` Robin Holt [this message]
2008-02-01 23:35         ` Robin Holt
2008-02-01 23:35         ` Robin Holt
2008-02-02  0:05         ` Christoph Lameter
2008-02-02  0:05           ` Christoph Lameter
2008-02-02  0:05           ` Christoph Lameter
2008-02-02  0:21           ` Robin Holt
2008-02-02  0:21             ` Robin Holt
2008-02-02  0:21             ` Robin Holt
2008-02-02  0:38             ` Robin Holt
2008-02-02  0:38               ` Robin Holt
2008-02-02  0:38               ` Robin Holt
2008-02-03  2:23         ` Andrea Arcangeli
2008-02-03  2:23           ` Andrea Arcangeli
2008-02-03  2:23           ` Andrea Arcangeli
2008-02-01  5:04 ` [patch 3/4] mmu_notifier: invalidate_page callbacks Christoph Lameter
2008-02-01  5:04   ` Christoph Lameter
2008-02-01  5:04 ` [patch 4/4] mmu_notifier: Support for driverws with revers maps (f.e. for XPmem) Christoph Lameter
2008-02-01  5:04   ` Christoph Lameter
2008-02-01 11:58 ` Extending mmu_notifiers to handle __xip_unmap in a sleepable context? Robin Holt
2008-02-01 11:58   ` Robin Holt
2008-02-01 11:58   ` Robin Holt
2008-02-01 12:10   ` Robin Holt
2008-02-01 12:10     ` Robin Holt
2008-02-01 12:10     ` Robin Holt
2008-02-01 19:17   ` Christoph Lameter
2008-02-01 19:17     ` Christoph Lameter
2008-02-01 19:17     ` Christoph Lameter
2008-02-03  1:39 ` [patch 0/4] [RFC] EMMU Notifiers V5 Andrea Arcangeli
2008-02-03  1:39   ` Andrea Arcangeli
2008-02-03 13:41 ` Robin Holt
2008-02-03 13:41   ` Robin Holt
2008-02-03 13:41   ` Robin Holt
  -- strict thread matches above, loose matches on Subject: below --
2008-01-25  5:56 [patch 0/4] [RFC] MMU Notifiers V1 Christoph Lameter
2008-01-25  5:56 ` [patch 2/4] mmu_notifier: Callbacks to invalidate address ranges Christoph Lameter
2008-01-25  5:56   ` Christoph Lameter

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