[PATCH] hung task: NMI when hung and going to panic

[Sasha Levin <levinsasha928@gmail.com>]

NMI all CPUs when detected a hung task and the hung task code is configured
to panic.

This lets us get stack trace of all CPUs which makes life easier trying to
debug a deadlock, and the NMI doesn't change anything since the next step is
a kernel panic.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 kernel/hung_task.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index c21449f..6df6149 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -108,8 +108,10 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 
 	touch_nmi_watchdog();
 
-	if (sysctl_hung_task_panic)
+	if (sysctl_hung_task_panic) {
+		trigger_all_cpu_backtrace();
 		panic("hung_task: blocked tasks");
+	}
 }
 
 /*
-- 
1.7.8.4