linux-kernel - mmu_notifier: Move mmu_notifier_release up to get rid of the invalidat

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Message-ID: <Pine.LNX.4.64.0801311421110.22290@schroedinger.engr.sgi.com>
Date:	Thu, 31 Jan 2008 14:21:58 -0800 (PST)
From:	Christoph Lameter <clameter@....com>
To:	Andrea Arcangeli <andrea@...ranet.com>
cc:	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>, steiner@....com,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com
Subject: mmu_notifier: Move mmu_notifier_release up to get rid of the
 invalidat_all() callback

mmu_notifier: Move mmu_notifier_release up to get rid of invalidate_all()

It seems that it is safe to call mmu_notifier_release() before we tear down
the pages and the vmas since we are the only executing thread. mmu_notifier_release
can then also tear down all its external ptes and thus we can get rid
of the invalidate_all() callback.

During the final teardown no mmu_notifier calls are registered anymore which
will speed up exit processing.

Is this okay for KVM too?

Signed-off-by: Christoph Lameter <clameter@....com>

---
 include/linux/mmu_notifier.h |    4 ----
 mm/mmap.c                    |    3 +--
 2 files changed, 1 insertion(+), 6 deletions(-)

Index: linux-2.6/include/linux/mmu_notifier.h
===================================================================
--- linux-2.6.orig/include/linux/mmu_notifier.h	2008-01-31 14:17:17.000000000 -0800
+++ linux-2.6/include/linux/mmu_notifier.h	2008-01-31 14:17:28.000000000 -0800
@@ -59,10 +59,6 @@ struct mmu_notifier_ops {
 	void (*release)(struct mmu_notifier *mn,
 			struct mm_struct *mm);
 
-	/* Dummy needed because the mmu_notifier() macro requires it */
-	void (*invalidate_all)(struct mmu_notifier *mn, struct mm_struct *mm,
-				int dummy);
-
 	/*
 	 * age_page is called from contexts where the pte_lock is held
 	 */
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c	2008-01-31 14:16:51.000000000 -0800
+++ linux-2.6/mm/mmap.c	2008-01-31 14:17:10.000000000 -0800
@@ -2036,7 +2036,7 @@ void exit_mmap(struct mm_struct *mm)
 	unsigned long end;
 
 	/* mm's last user has gone, and its about to be pulled down */
-	mmu_notifier(invalidate_all, mm, 0);
+	mmu_notifier_release(mm);
 	arch_exit_mmap(mm);
 
 	lru_add_drain();
@@ -2048,7 +2048,6 @@ void exit_mmap(struct mm_struct *mm)
 	vm_unacct_memory(nr_accounted);
 	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
 	tlb_finish_mmu(tlb, 0, end);
-	mmu_notifier_release(mm);
 
 	/*
 	 * Walk the list again, actually closing and freeing it,

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