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From: Christoph Lameter <clameter@sgi.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <andrea@qumranet.com>, Robin Holt <holt@sgi.com>,
	Avi Kivity <avi@qumranet.com>, Izik Eidus <izike@qumranet.com>,
	Nick Piggin <npiggin@suse.de>,
	kvm-devel@lists.sourceforge.net,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	steiner@sgi.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, daniel.blueman@quadrics.com,
	Hugh Dickins <hugh@veritas.com>
Subject: Re: [patch 1/6] mmu_notifier: Core code
Date: Wed, 30 Jan 2008 11:28:15 -0800 (PST)	[thread overview]
Message-ID: <Pine.LNX.4.64.0801301125390.27491@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <1201713032.28547.234.camel@lappy>

How about just taking the mmap_sem writelock in release? We have only a 
single caller of mmu_notifier_release() in mm/mmap.c and we know that we 
are not holding mmap_sem at that point. So just acquire it when needed?

Index: linux-2.6/mm/mmu_notifier.c
===================================================================
--- linux-2.6.orig/mm/mmu_notifier.c	2008-01-30 11:21:57.000000000 -0800
+++ linux-2.6/mm/mmu_notifier.c	2008-01-30 11:24:59.000000000 -0800
@@ -18,6 +19,7 @@ void mmu_notifier_release(struct mm_stru
 	struct hlist_node *n, *t;
 
 	if (unlikely(!hlist_empty(&mm->mmu_notifier.head))) {
+		down_write(&mm->mmap_sem);
 		rcu_read_lock();
 		hlist_for_each_entry_safe_rcu(mn, n, t,
 					  &mm->mmu_notifier.head, hlist) {
@@ -26,6 +28,7 @@ void mmu_notifier_release(struct mm_stru
 				mn->ops->release(mn, mm);
 		}
 		rcu_read_unlock();
+		up_write(&mm->mmap_sem);
 		synchronize_rcu();
 	}
 }

  reply	other threads:[~2008-01-30 19:28 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-30  2:29 [patch 0/6] [RFC] MMU Notifiers V3 Christoph Lameter
2008-01-30  2:29 ` [patch 1/6] mmu_notifier: Core code Christoph Lameter
2008-01-30 15:37   ` Andrea Arcangeli
2008-01-30 15:53     ` Jack Steiner
2008-01-30 16:38       ` Andrea Arcangeli
2008-01-30 19:19       ` Christoph Lameter
2008-01-30 22:20         ` Robin Holt
2008-01-30 23:38           ` Andrea Arcangeli
2008-01-30 23:55             ` Christoph Lameter
2008-01-31  0:12               ` [kvm-devel] " Andrea Arcangeli
2008-01-31  1:27                 ` Christoph Lameter
2008-01-30 17:10     ` Peter Zijlstra
2008-01-30 19:28       ` Christoph Lameter [this message]
2008-01-30 18:02   ` Robin Holt
2008-01-30 19:08     ` Christoph Lameter
2008-01-30 19:14     ` Christoph Lameter
2008-01-30  2:29 ` [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges Christoph Lameter
2008-01-30  2:29 ` [patch 3/6] mmu_notifier: invalidate_page callbacks for subsystems with rmap Christoph Lameter
2008-01-30 18:03   ` Robin Holt
2008-01-30  2:29 ` [patch 4/6] MMU notifier: invalidate_page callbacks using Linux rmaps Christoph Lameter
2008-01-30  2:29 ` [patch 5/6] mmu_notifier: Callbacks for xip_filemap.c Christoph Lameter
2008-01-30  2:29 ` [patch 6/6] mmu_notifier: Add invalidate_all() Christoph Lameter
  -- strict thread matches above, loose matches on Subject: below --
2008-02-15  6:48 [patch 0/6] MMU Notifiers V7 Christoph Lameter
2008-02-15  6:49 ` [patch 1/6] mmu_notifier: Core code Christoph Lameter
2008-02-16  3:37   ` Andrew Morton
2008-02-16  8:45     ` Avi Kivity
2008-02-16  8:56       ` Andrew Morton
2008-02-16  9:21         ` Avi Kivity
2008-02-16 10:41     ` Brice Goglin
2008-02-16 10:58       ` Andrew Morton
2008-02-16 19:31         ` Christoph Lameter
2008-02-16 19:21     ` Christoph Lameter
2008-02-17  3:01       ` Andrea Arcangeli
2008-02-17 12:24         ` Robin Holt
2008-02-17  5:04     ` Doug Maxey
2008-02-18 22:33   ` Roland Dreier
2008-02-08 22:06 [patch 0/6] MMU Notifiers V6 Christoph Lameter
2008-02-08 22:06 ` [patch 1/6] mmu_notifier: Core code Christoph Lameter
2008-01-28 20:28 [patch 0/6] [RFC] MMU Notifiers V2 Christoph Lameter
2008-01-28 20:28 ` [patch 1/6] mmu_notifier: Core code Christoph Lameter
2008-01-28 22:06   ` Christoph Lameter
2008-01-29  0:05   ` Robin Holt
2008-01-29  1:19     ` Christoph Lameter
2008-01-29 13:59   ` Andrea Arcangeli
2008-01-29 14:34     ` Andrea Arcangeli
2008-01-29 19:49     ` Christoph Lameter
2008-01-29 20:41       ` Avi Kivity
2008-01-29 16:07   ` Robin Holt
2008-02-05 18:05   ` Andy Whitcroft
2008-02-05 18:17     ` Peter Zijlstra
2008-02-05 18:19     ` Christoph Lameter

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