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workqueue: add cmdline parameter workqueue.panic_on_stall

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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.

Signed-off-by: Sangmoon Kim <sangmoon.kim@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Sangmoon Kim 2024-08-06 14:12:09 +09:00 • committed by Tejun Heo
parent 8400291e28
commit 073107b39e
1 changed files with 16 additions and 0 deletions
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16
kernel/workqueue.c
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@ -7398,6 +7398,9 @@ static struct timer_list wq_watchdog_timer;
static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
static unsigned int wq_panic_on_stall;
module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644);
/*
* Show workers that might prevent the processing of pending work items.
* The only candidates are CPU-bound workers in the running state.
@ -7449,6 +7452,16 @@ static void show_cpu_pools_hogs(void)
rcu_read_unlock();
}
static void panic_on_wq_watchdog(void)
{
static unsigned int wq_stall;
if (wq_panic_on_stall) {
wq_stall++;
BUG_ON(wq_stall >= wq_panic_on_stall);
}
}
static void wq_watchdog_reset_touched(void)
{
int cpu;
@ -7521,6 +7534,9 @@ static void wq_watchdog_timer_fn(struct timer_list *unused)
if (cpu_pool_stall)
show_cpu_pools_hogs();
if (lockup_detected)
panic_on_wq_watchdog();
wq_watchdog_reset_touched();
mod_timer(&wq_watchdog_timer, jiffies + thresh);
}