locking/lockdep: Print more debug information - report name and key when look_up_lock...

Printing this information will be helpful:

  ------------[ cut here ]------------
  Looking for class "l2tp_sock" with key l2tp_socket_class, but found a different class "slock-AF_INET6" with the same key
  WARNING: CPU: 1 PID: 14195 at kernel/locking/lockdep.c:940 look_up_lock_class+0xcc/0x140
  Modules linked in:
  CPU: 1 PID: 14195 Comm: a.out Not tainted 6.0.0-rc6-dirty #863
  Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
  RIP: 0010:look_up_lock_class+0xcc/0x140

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/bd99391e-f787-efe9-5ec6-3c6dc4c587b0@I-love.SAKURA.ne.jp

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 64a13eb560781c84ff5d809c3a7b0276e2152a23..e3375bc40dadc7b56482cd52a04a53f69c764df3 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -934,8 +934,10 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
                         * Huh! same key, different name? Did someone trample
                         * on some memory? We're most confused.
                         */
-                       WARN_ON_ONCE(class->name != lock->name &&
-                                    lock->key != &__lockdep_no_validate__);
+                       WARN_ONCE(class->name != lock->name &&
+                                 lock->key != &__lockdep_no_validate__,
+                                 "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n",
+                                 lock->name, lock->key, class->name);
                        return class;
                }
        }