The patch titled
Subject: mm/mmu_notifier.c: remove mmu_notifier_synchronize()
has been added to the -mm tree. Its filename is
mm-mmu_notifier-remove-mmu_notifier_synchronize.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-mmu_notifier-remove-mmu_notifier_synchronize.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-mmu_notifier-remove-mmu_notifier_synchronize.patch
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------------------------------------------------------
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Subject: mm/mmu_notifier.c: remove mmu_notifier_synchronize()
Contrary to its name, mmu_notifier_synchronize() does not synchronize the
notifier's SRCU instance, but rather waits for RCU callbacks to finished,
i.e. it invokes rcu_barrier(). The RCU documentation is quite clear on
this matter, explicitly calling out that rcu_barrier() does not imply
synchronize_rcu().
As there are no callers of mmu_notifier_synchronize() and it's unclear
whether any user of mmu_notifier_call_srcu() will ever want to barrier on
their callbacks, simply remove the function.
Link: http://lkml.kernel.org/r/20181106134705.14197-1-sean.j.christopherson@xxxxxxxxx
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmu_notifier.h | 1 -
mm/mmu_notifier.c | 7 -------
2 files changed, 8 deletions(-)
--- a/include/linux/mmu_notifier.h~mm-mmu_notifier-remove-mmu_notifier_synchronize
+++ a/include/linux/mmu_notifier.h
@@ -420,7 +420,6 @@ static inline void mmu_notifier_mm_destr
extern void mmu_notifier_call_srcu(struct rcu_head *rcu,
void (*func)(struct rcu_head *rcu));
-extern void mmu_notifier_synchronize(void);
#else /* CONFIG_MMU_NOTIFIER */
--- a/mm/mmu_notifier.c~mm-mmu_notifier-remove-mmu_notifier_synchronize
+++ a/mm/mmu_notifier.c
@@ -35,13 +35,6 @@ void mmu_notifier_call_srcu(struct rcu_h
}
EXPORT_SYMBOL_GPL(mmu_notifier_call_srcu);
-void mmu_notifier_synchronize(void)
-{
- /* Wait for any running method to finish. */
- srcu_barrier(&srcu);
-}
-EXPORT_SYMBOL_GPL(mmu_notifier_synchronize);
-
/*
* This function can't run concurrently against mmu_notifier_register
* because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
_
Patches currently in -mm which might be from sean.j.christopherson@xxxxxxxxx are
mm-mmu_notifier-remove-mmu_notifier_synchronize.patch
