From: Paul E. McKenney <paulmck@xxxxxxxxxx>
[ Upstream commit ef1ef3d47677dc191b88650a9f7f91413452cc1b ]
The rcu_scale_shutdown() and kfree_scale_shutdown() kthreads/functions
use wait_event() to wait for the rcuscale test to complete. However,
each updater thread in such a test waits for at least 100 grace periods.
If each grace period takes more than 1.2 seconds, which is long, but
not insanely so, this can trigger the hung-task timeout.
This commit therefore replaces those wait_event() calls with calls to
wait_event_idle(), which do not trigger the hung-task timeout.
Reported-by: kernel test robot <yujie.liu@xxxxxxxxx>
Reported-by: Liam Howlett <liam.howlett@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Tested-by: Yujie Liu <yujie.liu@xxxxxxxxx>
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Stable-dep-of: 23fc8df26dea ("rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/rcu/rcuscale.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 4452c3c4060ce..74be0b6438fb3 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -579,8 +579,7 @@ static int compute_real(int n)
static int
rcu_scale_shutdown(void *arg)
{
- wait_event(shutdown_wq,
- atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
+ wait_event_idle(shutdown_wq, atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
smp_mb(); /* Wake before output. */
rcu_scale_cleanup();
kernel_power_off();
@@ -693,8 +692,8 @@ kfree_scale_cleanup(void)
static int
kfree_scale_shutdown(void *arg)
{
- wait_event(shutdown_wq,
- atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
+ wait_event_idle(shutdown_wq,
+ atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
smp_mb(); /* Wake before output. */
--
2.39.2
