v4.19.13 snapshot.
diff --git a/lib/bust_spinlocks.c b/lib/bust_spinlocks.c
new file mode 100644
index 0000000..ab71949
--- /dev/null
+++ b/lib/bust_spinlocks.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * lib/bust_spinlocks.c
+ *
+ * Provides a minimal bust_spinlocks for architectures which don't have one of their own.
+ *
+ * bust_spinlocks() clears any spinlocks which would prevent oops, die(), BUG()
+ * and panic() information from reaching the user.
+ */
+
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/spinlock.h>
+#include <linux/tty.h>
+#include <linux/wait.h>
+#include <linux/vt_kern.h>
+#include <linux/console.h>
+
+
+void __attribute__((weak)) bust_spinlocks(int yes)
+{
+ if (yes) {
+ ++oops_in_progress;
+ } else {
+#ifdef CONFIG_VT
+ unblank_screen();
+#endif
+ console_unblank();
+ if (--oops_in_progress == 0)
+ wake_up_klogd();
+ }
+}