linux-kernel - [PATCH v3 1/2] hung_task: Introduce helper for hung task warning

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Message-ID: <20251216030036.1822217-2-atomlin@atomlin.com>
Date: Mon, 15 Dec 2025 22:00:35 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: akpm@...ux-foundation.org,
	lance.yang@...ux.dev,
	mhiramat@...nel.org,
	gregkh@...uxfoundation.org,
	pmladek@...e.com
Cc: sean@...e.io,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/2] hung_task: Introduce helper for hung task warning

Consolidate the multi-line console output block for reporting a hung
task into a new helper function, hung_task_diagnostics(). This improves
readability in the main check_hung_task() loop and makes the diagnostic
output structure easier to maintain and update in the future.

Signed-off-by: Aaron Tomlin <atomlin@...mlin.com>
---
 kernel/hung_task.c | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index d2254c91450b..5902573200c0 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -223,6 +223,32 @@ static inline void debug_show_blocker(struct task_struct *task, unsigned long ti
 }
 #endif
 
+/**
+ * hung_task_diagnostics - Print structured diagnostic info for a hung task.
+ * @t: Pointer to the detected hung task.
+ *
+ * This function consolidates the printing of core diagnostic information
+ * for a task found to be blocked.
+ */
+static inline void hung_task_diagnostics(struct task_struct *t)
+{
+	unsigned long blocked_secs = (jiffies - t->last_switch_time) / HZ;
+	const char *coredump_msg = "      Blocked by coredump.";
+	const char *disable_msg =
+		"\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
+		" disables this message.";
+
+	pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
+	       t->comm, t->pid, blocked_secs);
+	pr_err("      %s %s %.*s\n",
+	       print_tainted(), init_utsname()->release,
+	       (int)strcspn(init_utsname()->version, " "),
+	       init_utsname()->version);
+	if (t->flags & PF_POSTCOREDUMP)
+		pr_err("%s\n", coredump_msg);
+	pr_err("%s\n", disable_msg);
+}
+
 static void check_hung_task(struct task_struct *t, unsigned long timeout,
 		unsigned long prev_detect_count)
 {
@@ -252,16 +278,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout,
 	if (sysctl_hung_task_warnings || hung_task_call_panic) {
 		if (sysctl_hung_task_warnings > 0)
 			sysctl_hung_task_warnings--;
-		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
-		       t->comm, t->pid, (jiffies - t->last_switch_time) / HZ);
-		pr_err("      %s %s %.*s\n",
-			print_tainted(), init_utsname()->release,
-			(int)strcspn(init_utsname()->version, " "),
-			init_utsname()->version);
-		if (t->flags & PF_POSTCOREDUMP)
-			pr_err("      Blocked by coredump.\n");
-		pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
-			" disables this message.\n");
+		hung_task_diagnostics(t);
 		sched_show_task(t);
 		debug_show_blocker(t, timeout);
 
-- 
2.51.0