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Subject[PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range()
Date
From: Joerg Roedel <jroedel@suse.de>

Now that the mmu_notifier_invalidate_range() calls are in
place, add the call-back to allow subsystems to register
against it.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
include/linux/mmu_notifier.h | 28 ++++++++++++++++++++++------
mm/mmu_notifier.c | 15 +++++++++++++++
2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 6959dc8..50dc679 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
@@ -110,9 +110,19 @@ struct mmu_notifier_ops {
* invalidate_range_start() is called when all pages in the
* range are still mapped and have at least a refcount of one.
*
+ * invalidate_range() is called between invalidate_range_start()
+ * and invalidate_range_end() when the memory management code
+ * removed mappings to pages in the range and is about to free
+ * them. This captures the point when pages are unmapped but
+ * not yet freed.
+ * Note that invalidate_range() might be called only on a
+ * sub-range of the range passed to the corresponding
+ * invalidate_range_start() call.
+ *
* invalidate_range_end() is called when all pages in the
* range have been unmapped and the pages have been freed by
- * the VM.
+ * the VM. It might be called under the ptl spin-lock, so this
+ * notifier is not allowed to preempt.
*
* The VM will remove the page table entries and potentially
* the page between invalidate_range_start() and
@@ -138,6 +148,8 @@ struct mmu_notifier_ops {
void (*invalidate_range_start)(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start, unsigned long end);
+ void (*invalidate_range)(struct mmu_notifier *mn, struct mm_struct *mm,
+ unsigned long start, unsigned long end);
void (*invalidate_range_end)(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start, unsigned long end);
@@ -182,6 +194,8 @@ extern void __mmu_notifier_invalidate_page(struct mm_struct *mm,
unsigned long address);
extern void __mmu_notifier_invalidate_range_start(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);
extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
unsigned long start, unsigned long end);

@@ -231,6 +245,8 @@ static inline void mmu_notifier_invalidate_range_start(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_invalidate_range_end(struct mm_struct *mm,
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 41cefdf..d1bdea0 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -165,6 +165,21 @@ void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
}
EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range_start);

+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);
+
void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
--
1.9.1


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