1 files changed, 15 insertions, 1 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ba77ab5f64dd..a0831e1b99f4 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -551,7 +551,21 @@ static void print_lockdep_cache(struct lockdep_map *lock)
 
 static void print_lock(struct held_lock *hlock)
 {
-        print_lock_name(hlock_class(hlock));
+        /*
+         * We can be called locklessly through debug_show_all_locks() so be
+         * extra careful, the hlock might have been released and cleared.
+         */
+        unsigned int class_idx = hlock->class_idx;
+
+        /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
+        barrier();
+
+        if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
+                printk("<RELEASED>\n");
+                return;
+        }
+
+        print_lock_name(lock_classes + class_idx - 1);
         printk(", at: ");
         print_ip_sym(hlock->acquire_ip);
 }