5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ahmed Ehab <bottaawesome633@xxxxxxxxx>
commit d7fe143cb115076fed0126ad8cf5ba6c3e575e43 upstream.
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 a lock instance has a different name pointer than previous registered
one stored in lock class, and 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.
[boqun: Reword the commit log to state the correct issue]
Reported-by: <syzbot+7f4a6f7f7051474e40ad@xxxxxxxxxxxxxxxxxxxxxxxxx>
Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ahmed Ehab <bottaawesome633@xxxxxxxxx>
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Link: https://lore.kernel.org/lkml/20240824221031.7751-1-bottaawesome633@xxxxxxxxx/
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/lockdep.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -233,7 +233,7 @@ static inline void lockdep_init_map(stru
(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)
