From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, "Paul E. McKenney" <paulmck@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
Eric Dumazet <edumazet@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, KP Singh <kpsingh@kernel.org>
Subject: [PATCH rcu 16/32] rcu-tasks: Make RCU Tasks Trace stall warning handle idle offline tasks
Date: Mon, 20 Jun 2022 15:53:55 -0700 [thread overview]
Message-ID: <20220620225411.3842519-16-paulmck@kernel.org> (raw)
In-Reply-To: <20220620225402.GA3842369@paulmck-ThinkPad-P17-Gen-1>
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@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
---
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
next prev parent reply other threads:[~2022-06-20 22:55 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 22:54 [PATCH rcu 0/32] RCU Tasks updates for v5.20 Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 01/32] rcu-tasks: Check for abandoned callbacks Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 02/32] rcu-tasks: Split rcu_tasks_one_gp() from rcu_tasks_kthread() Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 03/32] rcu-tasks: Move synchronize_rcu_tasks_generic() down Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 04/32] rcu-tasks: Drive synchronous grace periods from calling task Paul E. McKenney
2022-09-01 10:36 ` Sascha Hauer
2022-09-01 17:27 ` Paul E. McKenney
2022-09-01 17:33 ` Paul E. McKenney
2022-09-02 11:52 ` Sascha Hauer
2022-09-02 12:04 ` Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 05/32] rcu-tasks: Merge state into .b.need_qs and atomically update Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 06/32] rcu-tasks: Remove rcu_tasks_trace_postgp() wait for counter Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 07/32] rcu-tasks: Make trc_read_check_handler() fetch ->trc_reader_nesting only once Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 08/32] rcu-tasks: Idle tasks on offline CPUs are in quiescent states Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 09/32] rcu-tasks: Handle idle tasks for recently offlined CPUs Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 10/32] rcu-tasks: RCU Tasks Trace grace-period kthread has implicit QS Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 11/32] rcu-tasks: Make rcu_note_context_switch() unconditionally call rcu_tasks_qs() Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 12/32] rcu-tasks: Simplify trc_inspect_reader() QS logic Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 13/32] rcu-tasks: Add slow-IPI indicator to RCU Tasks Trace stall warnings Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 14/32] rcu-tasks: Flag offline CPUs in " Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 15/32] rcu-tasks: Make RCU Tasks Trace stall warnings print full .b.need_qs field Paul E. McKenney
2022-06-20 22:53 ` Paul E. McKenney [this message]
2022-06-20 22:53 ` [PATCH rcu 17/32] rcu-tasks: Add data structures for lightweight grace periods Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 18/32] rcu-tasks: Track blocked RCU Tasks Trace readers Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 19/32] rcu-tasks: Untrack blocked RCU Tasks Trace at reader end Paul E. McKenney
2022-06-20 22:53 ` [PATCH rcu 20/32] rcu-tasks: Add blocked-task indicator to RCU Tasks Trace stall warnings Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 21/32] rcu-tasks: Move rcu_tasks_trace_pertask() before rcu_tasks_trace_pregp_step() Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 22/32] rcu-tasks: Avoid rcu_tasks_trace_pertask() duplicate list additions Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 23/32] rcu-tasks: Scan running tasks for RCU Tasks Trace readers Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 24/32] rcu-tasks: Pull in tasks blocked within " Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 25/32] rcu-tasks: Stop RCU Tasks Trace from scanning idle tasks Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 26/32] rcu-tasks: Stop RCU Tasks Trace from scanning full tasks list Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 27/32] rcu-tasks: Maintain a count of tasks blocking RCU Tasks Trace grace period Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 28/32] rcu-tasks: Eliminate RCU Tasks Trace IPIs to online CPUs Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 29/32] rcu-tasks: Disable and enable CPU hotplug in same function Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 30/32] rcu-tasks: Update comments Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 31/32] rcu-tasks: Be more patient for RCU Tasks boot-time testing Paul E. McKenney
2022-06-20 22:54 ` [PATCH rcu 32/32] rcu-tasks: Use delayed_work to delay rcu_tasks_verify_self_tests() Paul E. McKenney
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