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Date: Tue, 9 Sep 2014 17:43:54 +0200
From: Joerg Roedel <joro@...tes.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Rik van Riel <riel@...hat.com>,
Hugh Dickins <hughd@...gle.com>, Mel Gorman <mgorman@...e.de>,
Johannes Weiner <jweiner@...hat.com>
Cc: Jerome Glisse <jglisse@...hat.com>, jroedel@...e.de,
joro@...tes.org, Jay.Cornwall@....com, Oded.Gabbay@....com,
John.Bridgman@....com, Suravee.Suthikulpanit@....com,
ben.sander@....com, Jesse Barnes <jbarnes@...tuousgeek.org>,
David Woodhouse <dwmw2@...radead.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
iommu@...ts.linux-foundation.org
Subject: [PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range()
From: Joerg Roedel <jroedel@...e.de>
Now that the mmu_notifier_invalidate_range() calls are in
place, add the call-back to allow subsystems to register
against it.
Reviewed-by: Andrea Arcangeli <aarcange@...hat.com>
Reviewed-by: Jérôme Glisse <jglisse@...hat.com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
include/linux/mmu_notifier.h | 37 ++++++++++++++++++++++++++++++++-----
mm/mmu_notifier.c | 25 +++++++++++++++++++++++++
2 files changed, 57 insertions(+), 5 deletions(-)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 877d1c8..aa1a6bf 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -95,11 +95,11 @@ struct mmu_notifier_ops {
/*
* invalidate_range_start() and invalidate_range_end() must be
* paired and are called only when the mmap_sem and/or the
- * locks protecting the reverse maps are held. The subsystem
- * must guarantee that no additional references are taken to
- * the pages in the range established between the call to
- * invalidate_range_start() and the matching call to
- * invalidate_range_end().
+ * locks protecting the reverse maps are held. If the subsystem
+ * can't guarantee that no additional references are taken to
+ * the pages in the range, it has to implement the
+ * invalidate_range() notifier to remove any references taken
+ * after invalidate_range_start().
*
* Invalidation of multiple concurrent ranges may be
* optionally permitted by the driver. Either way the
@@ -141,6 +141,29 @@ struct mmu_notifier_ops {
void (*invalidate_range_end)(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start, unsigned long end);
+
+ /*
+ * invalidate_range() is either called between
+ * invalidate_range_start() and invalidate_range_end() when the
+ * VM has to free pages that where unmapped, but before the
+ * pages are actually freed, or outside of _start()/_end() when
+ * page-table pages are about to be freed.
+ *
+ * If invalidate_range() is used to manage a non-CPU TLB with
+ * shared page-tables, it not necessary to implement the
+ * invalidate_range_start()/end() notifiers, as
+ * invalidate_range() alread catches the points in time when an
+ * external TLB range needs to be flushed.
+ *
+ * The invalidate_range() function is called under the ptl
+ * spin-lock and not allowed to sleep.
+ *
+ * Note that this function might be called with just a sub-range
+ * of what was passed to invalidate_range_start()/end(), if
+ * called between those functions.
+ */
+ void (*invalidate_range)(struct mmu_notifier *mn, struct mm_struct *mm,
+ unsigned long start, unsigned long end);
};
/*
@@ -186,6 +209,8 @@ extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
unsigned long start, unsigned long end);
extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
unsigned long start, unsigned long end);
+extern void __mmu_notifier_invalidate_range(struct mm_struct *mm,
+ unsigned long start, unsigned long end);
static inline void mmu_notifier_release(struct mm_struct *mm)
{
@@ -240,6 +265,8 @@ static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
+ if (mm_has_notifiers(mm))
+ __mmu_notifier_invalidate_range(mm, start, end);
}
static inline void mmu_notifier_mm_init(struct mm_struct *mm)
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 950813b..a900637 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -192,6 +192,16 @@ void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+ /*
+ * Call invalidate_range here too to avoid the need for the
+ * subsystem of having to register an invalidate_range_end
+ * call-back when there is invalidate_range already. Usually a
+ * subsystem registers either invalidate_range_start()/end() or
+ * invalidate_range(), so this will be no additional overhead
+ * (besides the pointer check).
+ */
+ if (mn->ops->invalidate_range)
+ mn->ops->invalidate_range(mn, mm, start, end);
if (mn->ops->invalidate_range_end)
mn->ops->invalidate_range_end(mn, mm, start, end);
}
@@ -199,6 +209,21 @@ void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
}
EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range_end);
+void __mmu_notifier_invalidate_range(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ struct mmu_notifier *mn;
+ int id;
+
+ id = srcu_read_lock(&srcu);
+ hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+ if (mn->ops->invalidate_range)
+ mn->ops->invalidate_range(mn, mm, start, end);
+ }
+ srcu_read_unlock(&srcu, id);
+}
+EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range);
+
static int do_mmu_notifier_register(struct mmu_notifier *mn,
struct mm_struct *mm,
int take_mmap_sem)
--
1.9.1
--
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