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workqueue: add cmdline parameter workqueue.panic_on_stall

When we want to debug the workqueue stall, we can immediately make a panic to get the information we want. In some systems, it may be necessary to quickly reboot the system to escape from a workqueue lockup situation. In this case, we can control the number of stall detections to generate panic. workqueue.panic_on_stall sets the number times of the stall to trigger panic. 0 disables the panic on stall.

Sangmoon Kim committed 2 years ago

Commit 073107b1 parent 84002911 file · +16 −0Browse files

Showing the changes to kernel/workqueue.c (1 of 1 file). Show all

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kernel/workqueue.c+16−0
@@ -7398,6 +7398,9 @@ static struct timer_list wq_watchdog_timer; · 7397 unmodified lines
73987398 static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
73997399 static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
74007400
7401+static unsigned int wq_panic_on_stall;
7402+module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644);
7403+
74017404 /*
74027405 * Show workers that might prevent the processing of pending work items.
74037406 * The only candidates are CPU-bound workers in the running state.
@@ -7449,6 +7452,16 @@ static void show_cpu_pools_hogs(void) · 45 unmodified lines
74497452 rcu_read_unlock();
74507453 }
74517454
7455+static void panic_on_wq_watchdog(void)
7456+{
7457+ static unsigned int wq_stall;
7458+
7459+ if (wq_panic_on_stall) {
7460+ wq_stall++;
7461+ BUG_ON(wq_stall >= wq_panic_on_stall);
7462+ }
7463+}
7464+
74527465 static void wq_watchdog_reset_touched(void)
74537466 {
74547467 int cpu;
@@ -7521,6 +7534,9 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) · 66 unmodified lines
75217534 if (cpu_pool_stall)
75227535 show_cpu_pools_hogs();
75237536
7537+ if (lockup_detected)
7538+ panic_on_wq_watchdog();
7539+
75247540 wq_watchdog_reset_touched();
75257541 mod_timer(&wq_watchdog_timer, jiffies + thresh);
75267542 }