Message ID | 20240924094515.3561410-6-liwei391@huawei.com (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | tracing: Fix several deadlock/race issues in timerlat and hwlat tracer | expand |
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index 3bd6071441ad..4c228ccb8a38 100644 --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -370,7 +370,8 @@ static int kthread_fn(void *data) get_sample(); local_irq_enable(); - mutex_lock(&hwlat_data.lock); + if (mutex_lock_interruptible(&hwlat_data.lock)) + break; interval = hwlat_data.sample_window - hwlat_data.sample_width; mutex_unlock(&hwlat_data.lock);
Another "hung task" error was reported during the test, and i figured out the deadlock scenario is as follows: T1 [BP] | T2 [AP] | T3 [hwlatd/1] | T4 work_for_cpu_fn() | cpuhp_thread_fun() | kthread_fn() | hwlat_hotplug_workfn() _cpu_down() | stop_cpu_kthread() | | mutex_lock(&hwlat_data.lock) cpus_write_lock() | kthread_stop(hwlatd/1) | mutex_lock(&hwlat_data.lock) | __cpuhp_kick_ap() | wait_for_completion() | | cpus_read_lock() It constitutes ABBA deadlock indirectly between "cpu_hotplug_lock" and "hwlat_data.lock", make the mutex obtaining in kthread_fn() interruptible to fix this. Fixes: ba998f7d9531 ("trace/hwlat: Support hotplug operations") Signed-off-by: Wei Li <liwei391@huawei.com> --- kernel/trace/trace_hwlat.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)