linux-kernel - [PATCH RFC 3/3] kernel/watchdog: add option to dump system info when system is locked up

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Message-Id: <20250507104322.30700-4-feng.tang@linux.alibaba.com>
Date: Wed,  7 May 2025 18:43:22 +0800
From: Feng Tang <feng.tang@...ux.alibaba.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Petr Mladek <pmladek@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Lance Yang <ioworker0@...il.com>,
	linux-kernel@...r.kernel.org
Cc: Feng Tang <feng.tang@...ux.alibaba.com>
Subject: [PATCH RFC 3/3] kernel/watchdog: add option to dump system info when system is locked up

Kernel panic code utilizes sys_show_info() to dump needed system
information to help debugging. Similarly, add this debug option for
software/hardware lockup cases, and 'lockup_print' is the knob to
control what information should be printed out.

Signed-off-by: Feng Tang <feng.tang@...ux.alibaba.com>
---
 kernel/watchdog.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9fa2af9dbf2c..60afcb0247ab 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -52,6 +52,14 @@ static int __read_mostly watchdog_hardlockup_available;
 struct cpumask watchdog_cpumask __read_mostly;
 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
 
+/*
+ * A bitmask to control what kinds of system info to be printed when a
+ * software/hardware lockup is detected, it could be task, memory, lock etc.
+ * Refer panic.h for details of bit definition.
+ */
+unsigned long lockup_print;
+core_param(lockup_print, lockup_print, ulong, 0644);
+
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 
 # ifdef CONFIG_SMP
@@ -212,6 +220,7 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
 				clear_bit_unlock(0, &hard_lockup_nmi_warn);
 		}
 
+		sys_show_info(lockup_print);
 		if (hardlockup_panic)
 			nmi_panic(regs, "Hard LOCKUP");
 
@@ -774,6 +783,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 		}
 
 		add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
+
+		sys_show_info(lockup_print);
 		if (softlockup_panic)
 			panic("softlockup: hung tasks");
 	}
-- 
2.39.5 (Apple Git-154)