[PATCH 45/48] rcutorture: Make stall-tasks directly exit when rcutorture tests end

Uladzislau Rezki (Sony)
2024-05-07T09:36:18Z

From: Zqiang <qiang.zhang1211@gmail.com>

When the rcutorture tests start to exit, the rcu_torture_cleanup() is
invoked to stop kthreads and release resources, if the stall-task
kthreads exist, cpu-stall has started and the rcutorture.stall_cpu
is set to a larger value, the rcu_torture_cleanup() will be blocked
for a long time and the hung-task may occur, this commit therefore
add kthread_should_stop() to the loop of cpu-stall operation, when
rcutorture tests ends, no need to wait for cpu-stall to end, exit
directly.

Use the following command to test:

insmod rcutorture.ko torture_type=srcu fwd_progress=0 stat_interval=4
stall_cpu_block=1 stall_cpu=200 stall_cpu_holdoff=10 read_exit_burst=0
object_debug=1
rmmod rcutorture

[15361.918610] INFO: task rmmod:878 blocked for more than 122 seconds.
[15361.918613] Tainted: G W
6.8.0-rc2-yoctodev-standard+ #25
[15361.918615] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[15361.918616] task:rmmod state:D stack:0 pid:878
tgid:878 ppid:773 flags:0x00004002
[15361.918621] Call Trace:
[15361.918623] <TASK>
[15361.918626] __schedule+0xc0d/0x28f0
[15361.918631] ? __pfx___schedule+0x10/0x10
[15361.918635] ? rcu_is_watching+0x19/0xb0
[15361.918638] ? schedule+0x1f6/0x290
[15361.918642] ? __pfx_lock_release+0x10/0x10
[15361.918645] ? schedule+0xc9/0x290
[15361.918648] ? schedule+0xc9/0x290
[15361.918653] ? trace_preempt_off+0x54/0x100
[15361.918657] ? schedule+0xc9/0x290
[15361.918661] schedule+0xd0/0x290
[15361.918665] schedule_timeout+0x56d/0x7d0
[15361.918669] ? debug_smp_processor_id+0x1b/0x30
[15361.918672] ? rcu_is_watching+0x19/0xb0
[15361.918676] ? __pfx_schedule_timeout+0x10/0x10
[15361.918679] ? debug_smp_processor_id+0x1b/0x30
[15361.918683] ? rcu_is_watching+0x19/0xb0
[15361.918686] ? wait_for_completion+0x179/0x4c0
[15361.918690] ? __pfx_lock_release+0x10/0x10
[15361.918693] ? __kasan_check_write+0x18/0x20
[15361.918696] ? wait_for_completion+0x9d/0x4c0
[15361.918700] ? _raw_spin_unlock_irq+0x36/0x50
[15361.918703] ? wait_for_completion+0x179/0x4c0
[15361.918707] ? _raw_spin_unlock_irq+0x36/0x50
[15361.918710] ? wait_for_completion+0x179/0x4c0
[15361.918714] ? trace_preempt_on+0x54/0x100
[15361.918718] ? wait_for_completion+0x179/0x4c0
[15361.918723] wait_for_completion+0x181/0x4c0
[15361.918728] ? __pfx_wait_for_completion+0x10/0x10
[15361.918738] kthread_stop+0x152/0x470
[15361.918742] _torture_stop_kthread+0x44/0xc0 [torture
7af7f9cbba28271a10503b653f9e05d518fbc8c3]
[15361.918752] rcu_torture_cleanup+0x2ac/0xe90 [rcutorture
f2cb1f556ee7956270927183c4c2c7749a336529]
[15361.918766] ? __pfx_rcu_torture_cleanup+0x10/0x10 [rcutorture
f2cb1f556ee7956270927183c4c2c7749a336529]
[15361.918777] ? __kasan_check_write+0x18/0x20
[15361.918781] ? __mutex_unlock_slowpath+0x17c/0x670
[15361.918789] ? __might_fault+0xcd/0x180
[15361.918793] ? find_module_all+0x104/0x1d0
[15361.918799] __x64_sys_delete_module+0x2a4/0x3f0
[15361.918803] ? __pfx___x64_sys_delete_module+0x10/0x10
[15361.918807] ? syscall_exit_to_user_mode+0x149/0x280

Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
kernel/rcu/rcutorture.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 3f9c3766f52b..456185d9e6c0 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2489,8 +2489,8 @@ static int rcu_torture_stall(void *args)
preempt_disable();
pr_alert("%s start on CPU %d.\n",
__func__, raw_smp_processor_id());
- while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
- stop_at))
+ while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(), stop_at) &&
+ !kthread_should_stop())
if (stall_cpu_block) {
#ifdef CONFIG_PREEMPTION
preempt_schedule();
--
2.39.2