linux-kernel - [PATCH] sched/debug,sched/core: Reset hung task detector while processing sysrq-t

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Message-Id: <20230607180958.4112039-1-xqjcool@gmail.com>
Date:   Wed,  7 Jun 2023 11:09:58 -0700
From:   Qingjie Xing <xqjcool@...il.com>
To:     mingo@...hat.com
Cc:     peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, brauner@...nel.org,
        linux-kernel@...r.kernel.org, xqjcool@...il.com
Subject: [PATCH] sched/debug,sched/core: Reset hung task detector while processing sysrq-t

On devices with multiple CPUs and multiple processes, outputting lengthy
sysrq-t content on a slow serial port can consume a significant amount
of time. We need to reset the hung task detector to avoid false hung task
alerts.

Signed-off-by: Qingjie Xing <xqjcool@...il.com>
---
 kernel/sched/core.c  | 1 +
 kernel/sched/debug.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a68d1276bab0..5773283b752c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9176,6 +9176,7 @@ void show_state_filter(unsigned int state_filter)
 		 */
 		touch_nmi_watchdog();
 		touch_all_softlockup_watchdogs();
+		reset_hung_task_detector();
 		if (state_filter_match(state_filter, p))
 			sched_show_task(p);
 	}
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 0b2340a79b65..43065808b425 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -904,6 +904,7 @@ void sysrq_sched_debug_show(void)
 		 */
 		touch_nmi_watchdog();
 		touch_all_softlockup_watchdogs();
+		reset_hung_task_detector();
 		print_cpu(NULL, cpu);
 	}
 }
-- 
2.40.1