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-rw-r--r--kernel/locking/lockdep.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ba77ab5..a0831e1 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);
}
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