[PATCH v9 2/2] hung_task: Log summary line when warning budget is exhausted

[Aaron Tomlin]

Once the warning budget is exhausted, hung_task_info() stops printing
per-task details. To provide visibility without causing additional log
spam, emit a single aggregate summary line at the end of each watchdog
scan when hung tasks are detected and the warning budget is exhausted.

Keep per-task reports budgeted to avoid flooding dmesg or causing
ring buffer overflows during system-wide hangs.

Suggested-by: Petr Mladek <pmladek@xxxxxxxx>
Suggested-by: Lance Yang <lance.yang@xxxxxxxxx>
Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxxx>
---
 kernel/hung_task.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 53499fbead83..f5eb75325f3a 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -268,7 +268,7 @@ 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();
@@ -354,6 +354,10 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 		return;
 	}
 
+	if (!hung_task_warnings_printed && !hung_task_call_panic)
+		pr_info("hung_task: %lu hung tasks detected, warning budget exhausted\n",
+			this_round_count);
+
 	if (need_warning || hung_task_call_panic) {
 		si_mask |= SYS_INFO_LOCKS;
 
-- 
2.55.0