1 files changed, 31 insertions, 18 deletions

diff --git a/kernel/panic.c b/kernel/panic.c
index 463c9295bc28..5cfea8302d23 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -34,6 +34,7 @@
 #include <linux/ratelimit.h>
 #include <linux/debugfs.h>
 #include <linux/sysfs.h>
+#include <linux/context_tracking.h>
 #include <trace/events/error_report.h>
 #include <asm/sections.h>
 
@@ -211,9 +212,6 @@ static void panic_print_sys_info(bool console_flush)
 		return;
 	}
 
-	if (panic_print & PANIC_PRINT_ALL_CPU_BT)
-		trigger_all_cpu_backtrace();
-
 	if (panic_print & PANIC_PRINT_TASK_INFO)
 		show_state();
 
@@ -243,6 +241,30 @@ void check_panic_on_warn(const char *origin)
 		      origin, limit);
 }
 
+/*
+ * Helper that triggers the NMI backtrace (if set in panic_print)
+ * and then performs the secondary CPUs shutdown - we cannot have
+ * the NMI backtrace after the CPUs are off!
+ */
+static void panic_other_cpus_shutdown(bool crash_kexec)
+{
+	if (panic_print & PANIC_PRINT_ALL_CPU_BT)
+		trigger_all_cpu_backtrace();
+
+	/*
+	 * Note that smp_send_stop() is the usual SMP shutdown function,
+	 * which unfortunately may not be hardened to work in a panic
+	 * situation. If we want to do crash dump after notifier calls
+	 * and kmsg_dump, we will need architecture dependent extra
+	 * bits in addition to stopping other CPUs, hence we rely on
+	 * crash_smp_send_stop() for that.
+	 */
+	if (!crash_kexec)
+		smp_send_stop();
+	else
+		crash_smp_send_stop();
+}
+
 /**
  *	panic - halt the system
  *	@fmt: The text string to print
@@ -333,23 +355,10 @@ void panic(const char *fmt, ...)
 	 *
 	 * Bypass the panic_cpu check and call __crash_kexec directly.
 	 */
-	if (!_crash_kexec_post_notifiers) {
+	if (!_crash_kexec_post_notifiers)
 		__crash_kexec(NULL);
 
-		/*
-		 * Note smp_send_stop is the usual smp shutdown function, which
-		 * unfortunately means it may not be hardened to work in a
-		 * panic situation.
-		 */
-		smp_send_stop();
-	} else {
-		/*
-		 * If we want to do crash dump after notifier calls and
-		 * kmsg_dump, we will need architecture dependent extra
-		 * works in addition to stopping other CPUs.
-		 */
-		crash_smp_send_stop();
-	}
+	panic_other_cpus_shutdown(_crash_kexec_post_notifiers);
 
 	/*
 	 * Run any panic handlers, including those that might need to
@@ -679,6 +688,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 void warn_slowpath_fmt(const char *file, int line, unsigned taint,
 		       const char *fmt, ...)
 {
+	bool rcu = warn_rcu_enter();
 	struct warn_args args;
 
 	pr_warn(CUT_HERE);
@@ -693,11 +703,13 @@ void warn_slowpath_fmt(const char *file, int line, unsigned taint,
 	va_start(args.args, fmt);
 	__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
 	va_end(args.args);
+	warn_rcu_exit(rcu);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt);
 #else
 void __warn_printk(const char *fmt, ...)
 {
+	bool rcu = warn_rcu_enter();
 	va_list args;
 
 	pr_warn(CUT_HERE);
@@ -705,6 +717,7 @@ void __warn_printk(const char *fmt, ...)
 	va_start(args, fmt);
 	vprintk(fmt, args);
 	va_end(args);
+	warn_rcu_exit(rcu);
 }
 EXPORT_SYMBOL(__warn_printk);
 #endif