[patch 6/6] mmu_notifier: Add invalidate_all()

[Christoph Lameter <clameter@sgi.com>]

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when a task exits we can remove all external pts at once. At that point the
extern mmu may also unregister itself from the mmu notifier chain to avoid
future calls.

Note the complications because of RCU. Other processors may not see that the
notifier was unlinked until a quiescent period has passed!

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

---
 include/linux/mmu_notifier.h |    4 ++++
 mm/mmap.c                    |    1 +
 2 files changed, 5 insertions(+)

Index: linux-2.6/include/linux/mmu_notifier.h
===================================================================
--- linux-2.6.orig/include/linux/mmu_notifier.h	2008-01-28 14:02:18.000000000 -0800
+++ linux-2.6/include/linux/mmu_notifier.h	2008-01-28 14:15:49.000000000 -0800
@@ -62,6 +62,10 @@ struct mmu_notifier_ops {
 				struct mm_struct *mm,
 				unsigned long address);
 
+	/* Dummy needed because the mmu_notifier() macro requires it */
+	void (*invalidate_all)(struct mmu_notifier *mn, struct mm_struct *mm,
+				int dummy);
+
 	/*
 	 * lock indicates that the function is called under spinlock.
 	 */
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c	2008-01-28 14:15:49.000000000 -0800
+++ linux-2.6/mm/mmap.c	2008-01-28 14:15:49.000000000 -0800
@@ -2034,6 +2034,7 @@ 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);
 	arch_exit_mmap(mm);
 
 	lru_add_drain();

--