[PATCH v7 2/2] hung_task: Always print basic hung task info header

[Aaron Tomlin <atomlin@atomlin.com>]

From: Petr Mladek <pmladek@suse.com>

Currently, hung_task_info() completely suppresses any warning messages
once the warning budget is reached. This leaves the system completely
blind to any future hung tasks, even though we only wanted to suppress
heavy process stack dumps.

Modify hung_task_info() to always print the basic single-line error message
about a hung task, regardless of whether the warning budget has been
exhausted. Restrict only the verbose details (such as stack dumps,
taint/release status, and blockers) to when the warning budget is intact
or panic is triggered.

Additionally, update the notice printed upon warning exhaustion to clarify
that future reports will only omit process details rather than being completely
suppressed.

Assisted-by: gemini-3.5-flash
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
---
 kernel/hung_task.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 4e1fb0db79d1..6ebb3a87ac65 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -244,17 +244,19 @@ static void hung_task_info(struct task_struct *t, unsigned long timeout,
 		hung_task_call_panic = true;
 	}
 
+	/* Always print the blocked message */
+	pr_err("INFO: task %s:%d blocked%s for more than %ld seconds.\n",
+	       t->comm, t->pid, t->in_iowait ? " in I/O wait" : "",
+	       (jiffies - t->last_switch_time) / HZ);
+
 	/*
 	 * The given task did not get scheduled for more than
 	 * CONFIG_DEFAULT_HUNG_TASK_TIMEOUT. Therefore, complain
-	 * accordingly
+	 * accordingly with full details if the budget is not exhausted.
 	 */
 	if (hung_task_warnings_printed || hung_task_call_panic) {
 		if (hung_task_warnings_printed > 0)
 			hung_task_warnings_printed--;
-		pr_err("INFO: task %s:%d blocked%s for more than %ld seconds.\n",
-		       t->comm, t->pid, t->in_iowait ? " in I/O wait" : "",
-		       (jiffies - t->last_switch_time) / HZ);
 		pr_err("      %s %s %.*s\n",
 			print_tainted(), init_utsname()->release,
 			(int)strcspn(init_utsname()->version, " "),
@@ -267,7 +269,7 @@ static void hung_task_info(struct task_struct *t, unsigned long timeout,
 		debug_show_blocker(t, timeout);
 
 		if (!hung_task_warnings_printed)
-			pr_info("Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings\n");
+			pr_info("Future hung task reports won't print details about each process, see sysctl kernel.hung_task_warnings\n");
 	}
 
 	touch_nmi_watchdog();
-- 
2.55.0