1 files changed, 3 insertions, 0 deletions

diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index c69938e4b0d5..9ac959ef4cae 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -83,6 +83,7 @@ int percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release,
         atomic_long_set(&ref->count, start_count);
 
         ref->release = release;
+        ref->confirm_switch = NULL;
         return 0;
 }
 EXPORT_SYMBOL_GPL(percpu_ref_init);
@@ -102,6 +103,8 @@ void percpu_ref_exit(struct percpu_ref *ref)
         unsigned long __percpu *percpu_count = percpu_count_ptr(ref);
 
         if (percpu_count) {
+                /* non-NULL confirm_switch indicates switching in progress */
+                WARN_ON_ONCE(ref->confirm_switch);
                 free_percpu(percpu_count);
                 ref->percpu_count_ptr = __PERCPU_REF_ATOMIC_DEAD;
         }