From 95085568f4bf46aa4eb4c22bc91659b0ec4adcf1 Mon Sep 17 00:00:00 2001
From: Ben Kochie <superq@gmail.com>
Date: Mon, 6 Apr 2026 10:27:30 +0200
Subject: [PATCH] Fix kernel_hung for no data

Return an ErrNoData for the kernel_hung collector if the file does
not exist.

Fixes: https://github.com/prometheus/node_exporter/issues/3612

Signed-off-by: Ben Kochie <superq@gmail.com>
---
 collector/kernel_hung_linux.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/collector/kernel_hung_linux.go b/collector/kernel_hung_linux.go
index 8403977ded..d77c504b6c 100644
--- a/collector/kernel_hung_linux.go
+++ b/collector/kernel_hung_linux.go
@@ -16,8 +16,10 @@
 package collector
 
 import (
+	"errors"
 	"fmt"
 	"log/slog"
+	"os"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/procfs"
@@ -54,6 +56,10 @@ var (
 func (c *kernelHungCollector) Update(ch chan<- prometheus.Metric) error {
 	kernelHung, err := c.fs.KernelHung()
 	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			c.logger.Debug("hung_task_detect_count does not exist")
+			return ErrNoData
+		}
 		return err
 	}