From 9d02330abd3ecdacc43fc6b16a5668e7e94b7562 Mon Sep 17 00:00:00 2001 From: Li Zhe Date: Thu, 23 Nov 2023 16:40:22 +0800 Subject: softlockup: serialized softlockup's log If multiple CPUs trigger softlockup at the same time with 'softlockup_all_cpu_backtrace=0', the softlockup's logs will appear staggeredly in dmesg, which will affect the viewing of the logs for developer. Since the code path for outputting softlockup logs is not a kernel hotspot and the performance requirements for the code are not strict, locks are used to serialize the softlockup log output to improve the readability of the logs. Link: https://lkml.kernel.org/r/20231123084022.10302-1-lizhe.67@bytedance.com Signed-off-by: Li Zhe Reviewed-by: Petr Mladek Reviewed-by: Douglas Anderson Cc: Lecopzer Chen Cc: Pingfan Liu Cc: Zefan Li Cc: John Ogness Signed-off-by: Andrew Morton --- kernel/watchdog.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/watchdog.c') diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 5cd6d4e26915..bf30a6fac665 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -448,6 +448,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) struct pt_regs *regs = get_irq_regs(); int duration; int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; + static DEFINE_SPINLOCK(watchdog_output_lock); if (!watchdog_enabled) return HRTIMER_NORESTART; @@ -514,6 +515,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) /* Start period for the next softlockup warning. */ update_report_ts(); + spin_lock(&watchdog_output_lock); pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); @@ -523,6 +525,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) show_regs(regs); else dump_stack(); + spin_unlock(&watchdog_output_lock); if (softlockup_all_cpu_backtrace) { trigger_allbutcpu_cpu_backtrace(smp_processor_id()); -- cgit