1 files changed, 7 insertions, 1 deletions

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index d5c89e0dd0e6..51ce60c35f4c 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -133,7 +133,13 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref,
         /* paired with smp_store_release() in percpu_ref_reinit() */
         smp_read_barrier_depends();
 
-        if (unlikely(percpu_ptr & __PERCPU_REF_ATOMIC))
+        /*
+         * Theoretically, the following could test just ATOMIC; however,
+         * then we'd have to mask off DEAD separately as DEAD may be
+         * visible without ATOMIC if we race with percpu_ref_kill().  DEAD
+         * implies ATOMIC anyway.  Test them together.
+         */
+        if (unlikely(percpu_ptr & __PERCPU_REF_ATOMIC_DEAD))
                 return false;
 
         *percpu_countp = (unsigned long __percpu *)percpu_ptr;