From: John Ogness <john.ogness@linutronix.de>
Date: Mon, 18 Sep 2023 20:27:41 +0000
Subject: [PATCH 120/134] lockdep: Mark emergency section in lockdep splats
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz

Mark an emergency section within print_usage_bug(), where
lockdep bugs are printed. In this section, the CPU will not
perform console output for the printk() calls. Instead, a
flushing of the console output will triggered when exiting
the emergency section.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/locking/lockdep.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -56,6 +56,7 @@
 #include <linux/kprobes.h>
 #include <linux/lockdep.h>
 #include <linux/context_tracking.h>
+#include <linux/console.h>
 
 #include <asm/sections.h>
 
@@ -3971,6 +3972,8 @@ print_usage_bug(struct task_struct *curr
 	if (!debug_locks_off() || debug_locks_silent)
 		return;
 
+	nbcon_cpu_emergency_enter();
+
 	pr_warn("\n");
 	pr_warn("================================\n");
 	pr_warn("WARNING: inconsistent lock state\n");
@@ -3999,6 +4002,8 @@ print_usage_bug(struct task_struct *curr
 
 	pr_warn("\nstack backtrace:\n");
 	dump_stack();
+
+	nbcon_cpu_emergency_exit();
 }
 
 /*