Syzbot reports a problem that a warning will be triggered while searching a lock class in look_up_lock_class().

The cause of the issue is that a new name is created and used by lockdep_set_subclass() instead of using the existing one. This results in two lock classes with the same key but different name pointers and a WARN_ONCE() is triggered because of that in look_up_lock_class().

To fix this, change lockdep_set_subclass() to use the existing name instead of a new one. Hence, no new name will be created by lockdep_set_subclass(). Hence, the warning is avoided.

Reported-by: syzbot+7f4a6f7f7051474e40ad@syzkaller.appspotmail.com Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks") Cc: stable@vger.kernel.org Signed-off-by: Ahmed Ehab bottaawesome633@gmail.com --- v4->v5: - Changed the subject - Changed the changelog to be more detailed

include/linux/lockdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 08b0d1d9d78b..df8fa5929de7 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -173,7 +173,7 @@ static inline void lockdep_init_map(struct lockdep_map *lock, const char *name, (lock)->dep_map.lock_type)

#define lockdep_set_subclass(lock, sub) \ - lockdep_init_map_type(&(lock)->dep_map, #lock, (lock)->dep_map.key, sub,\ + lockdep_init_map_type(&(lock)->dep_map, (lock)->dep_map.name, (lock)->dep_map.key, sub,\ (lock)->dep_map.wait_type_inner, \ (lock)->dep_map.wait_type_outer, \ (lock)->dep_map.lock_type)