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-rw-r--r--mm/mmu_notifier.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 96edb33..eff6b88 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -236,6 +236,37 @@ void __mmu_notifier_invalidate_range(struct mm_struct *mm,
}
EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range);
+/*
+ * Must be called while holding mm->mmap_sem for either read or write.
+ * The result is guaranteed to be valid until mm->mmap_sem is dropped.
+ */
+bool mm_has_blockable_invalidate_notifiers(struct mm_struct *mm)
+{
+ struct mmu_notifier *mn;
+ int id;
+ bool ret = false;
+
+ WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem));
+
+ if (!mm_has_notifiers(mm))
+ return ret;
+
+ 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_start &&
+ !mn->ops->invalidate_range_end)
+ continue;
+
+ if (!(mn->ops->flags & MMU_INVALIDATE_DOES_NOT_BLOCK)) {
+ ret = true;
+ break;
+ }
+ }
+ srcu_read_unlock(&srcu, id);
+ return ret;
+}
+
static int do_mmu_notifier_register(struct mmu_notifier *mn,
struct mm_struct *mm,
int take_mmap_sem)
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