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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
7398static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;7398static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
7399static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;7399static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
7400 7400
7401static unsigned int wq_panic_on_stall;
7402module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644);
7403
7401/*7404/*
7402 * Show workers that might prevent the processing of pending work items.7405 * Show workers that might prevent the processing of pending work items.
7403 * The only candidates are CPU-bound workers in the running state.7406 * 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
7449 rcu_read_unlock();7452 rcu_read_unlock();
7450}7453}
7451 7454
7455static 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
7452static void wq_watchdog_reset_touched(void)7465static void wq_watchdog_reset_touched(void)
7453{7466{
7454 int cpu;7467 int cpu;
@@ -7521,6 +7534,9 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) · 66 unmodified lines
7521 if (cpu_pool_stall)7534 if (cpu_pool_stall)
7522 show_cpu_pools_hogs();7535 show_cpu_pools_hogs();
7523 7536
7537 if (lockup_detected)
7538 panic_on_wq_watchdog();
7539
7524 wq_watchdog_reset_touched();7540 wq_watchdog_reset_touched();
7525 mod_timer(&wq_watchdog_timer, jiffies + thresh);7541 mod_timer(&wq_watchdog_timer, jiffies + thresh);
7526}7542}