When a CPU is offline, its idle task can appear to be running, but it
cannot be doing anything while CPU-hotplug operations are excluded.
This commit takes advantage of that fact by making trc_check_slow_task()
check for task_curr(t) && cpu_online(task_cpu(t)), and recording
full information in that case.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Neeraj Upadhyay <quic_neeraju@xxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxx>
---
kernel/rcu/tasks.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 5eefbab7f2edb..64eb4d7b142e3 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1476,7 +1476,7 @@ static int trc_check_slow_task(struct task_struct *t, void *arg)
{
struct trc_stall_chk_rdr *trc_rdrp = arg;
- if (task_curr(t))
+ if (task_curr(t) && cpu_online(task_cpu(t)))
return false; // It is running, so decline to inspect it.
trc_rdrp->nesting = READ_ONCE(t->trc_reader_nesting);
trc_rdrp->ipi_to_cpu = READ_ONCE(t->trc_ipi_to_cpu);
--
2.31.1.189.g2e36527f23
