diff options
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 14 | ||||
| -rw-r--r-- | include/linux/sched/sysctl.h | 7 | ||||
| -rw-r--r-- | kernel/hung_task.c | 20 | ||||
| -rw-r--r-- | kernel/sysctl.c | 11 |
4 files changed, 50 insertions, 2 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 3b00b9223157..861820d27c19 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -335,6 +335,20 @@ Path for the hotplug policy agent. Default value is "``/sbin/hotplug``". +hung_task_all_cpu_backtrace: +================ + +If this option is set, the kernel will send an NMI to all CPUs to dump +their backtraces when a hung task is detected. This file shows up if +CONFIG_DETECT_HUNG_TASK and CONFIG_SMP are enabled. + +0: Won't show all CPUs backtraces when a hung task is detected. +This is the default behavior. + +1: Will non-maskably interrupt all CPUs and dump their backtraces when +a hung task is detected. + + hung_task_panic =============== diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h index 7b4d3a49b6c5..660ac49f2b53 100644 --- a/include/linux/sched/sysctl.h +++ b/include/linux/sched/sysctl.h @@ -7,6 +7,13 @@ struct ctl_table; #ifdef CONFIG_DETECT_HUNG_TASK + +#ifdef CONFIG_SMP +extern unsigned int sysctl_hung_task_all_cpu_backtrace; +#else +#define sysctl_hung_task_all_cpu_backtrace 0 +#endif /* CONFIG_SMP */ + extern int sysctl_hung_task_check_count; extern unsigned int sysctl_hung_task_panic; extern unsigned long sysctl_hung_task_timeout_secs; diff --git a/kernel/hung_task.c b/kernel/hung_task.c index b22b5eeab3cb..ce76f490126c 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -53,9 +53,18 @@ int __read_mostly sysctl_hung_task_warnings = 10; static int __read_mostly did_panic; static bool hung_task_show_lock; static bool hung_task_call_panic; +static bool hung_task_show_all_bt; static struct task_struct *watchdog_task; +#ifdef CONFIG_SMP +/* + * Should we dump all CPUs backtraces in a hung task event? + * Defaults to 0, can be changed via sysctl. + */ +unsigned int __read_mostly sysctl_hung_task_all_cpu_backtrace; +#endif /* CONFIG_SMP */ + /* * Should we panic (and reboot, if panic_timeout= is set) when a * hung task is detected: @@ -127,6 +136,9 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) " disables this message.\n"); sched_show_task(t); hung_task_show_lock = true; + + if (sysctl_hung_task_all_cpu_backtrace) + hung_task_show_all_bt = true; } touch_nmi_watchdog(); @@ -191,10 +203,14 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) rcu_read_unlock(); if (hung_task_show_lock) debug_show_all_locks(); - if (hung_task_call_panic) { + + if (hung_task_show_all_bt) { + hung_task_show_all_bt = false; trigger_all_cpu_backtrace(); - panic("hung_task: blocked tasks"); } + + if (hung_task_call_panic) + panic("hung_task: blocked tasks"); } static long hung_timeout_jiffies(unsigned long last_checked, diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 587ed0494f2f..34c1278951b9 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2437,6 +2437,17 @@ static struct ctl_table kern_table[] = { }, #endif #ifdef CONFIG_DETECT_HUNG_TASK +#ifdef CONFIG_SMP + { + .procname = "hung_task_all_cpu_backtrace", + .data = &sysctl_hung_task_all_cpu_backtrace, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +#endif /* CONFIG_SMP */ { .procname = "hung_task_panic", .data = &sysctl_hung_task_panic, |