lockdep: Add a missing initialization hint to the "INFO: Trying to register non-static key" message

Since this message is printed when dynamically allocated spinlocks (e.g.
kzalloc()) are used without initialization (e.g. spin_lock_init()),
suggest to developers to check whether initialization functions for objects
were called, before making developers wonder what annotation is missing.

[ mingo: Minor tweaks to the message. ]

Signed-off-by: Tetsuo Handa <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

kernel/locking/lockdep.c

···
 		/* Debug-check: all keys must be persistent! */
 		debug_locks_off();
 		pr_err("INFO: trying to register non-static key.\n");
-		pr_err("the code is fine but needs lockdep annotation.\n");
+		pr_err("The code is fine but needs lockdep annotation, or maybe\n");
+		pr_err("you didn't initialize this object before use?\n");
 		pr_err("turning off the locking correctness validator.\n");
 		dump_stack();
 		return false;