--- zzzz-none-000/linux-4.9.279/kernel/fork.c	2021-08-08 06:38:54.000000000 +0000
+++ puma7-atom-6591-750/linux-4.9.279/kernel/fork.c	2023-02-08 11:43:43.000000000 +0000
@@ -1644,6 +1644,7 @@
 
 #ifdef CONFIG_DEBUG_MUTEXES
 	p->blocked_on = NULL; /* not blocked yet */
+	spin_lock_init(&p->blocked_on_ptrlock);
 #endif
 #ifdef CONFIG_BCACHE
 	p->sequential_io	= 0;