From: Hao Jia <jiahao.os@bytedance.com>
To: mingo@redhat.com, peterz@infradead.org, mingo@kernel.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
vschneid@redhat.com, mgorman@techsingularity.net
Cc: linux-kernel@vger.kernel.org, Hao Jia <jiahao.os@bytedance.com>
Subject: [PATCH v4 4/4] sched/core: Avoid multiple calling update_rq_clock() in unthrottle_offline_cfs_rqs()
Date: Thu, 8 Jun 2023 14:33:12 +0800 [thread overview]
Message-ID: <20230608063312.79440-5-jiahao.os@bytedance.com> (raw)
In-Reply-To: <20230608063312.79440-1-jiahao.os@bytedance.com>
This WARN_DOUBLE_CLOCK warning is triggered during cpu offline.
------------[ cut here ]------------
rq->clock_update_flags & RQCF_UPDATED
WARNING: CPU: 0 PID: 3323 at kernel/sched/core.c:741
update_rq_clock+0xaf/0x180
Call Trace:
<TASK>
unthrottle_cfs_rq+0x4b/0x300
rq_offline_fair+0x89/0x90
set_rq_offline.part.118+0x28/0x60
rq_attach_root+0xc4/0xd0
cpu_attach_domain+0x3dc/0x7f0
partition_sched_domains_locked+0x2a5/0x3c0
rebuild_sched_domains_locked+0x477/0x830
rebuild_sched_domains+0x1b/0x30
cpuset_hotplug_workfn+0x2ca/0xc90
? balance_push+0x56/0xf0
? _raw_spin_unlock+0x15/0x30
? finish_task_switch+0x98/0x2f0
? __switch_to+0x291/0x410
? __schedule+0x65e/0x1310
process_one_work+0x1bc/0x3d0
worker_thread+0x4c/0x380
? preempt_count_add+0x92/0xa0
? rescuer_thread+0x310/0x310
kthread+0xe6/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
The rq clock has been updated before the set_rq_offline()
function runs, so we don't need to call update_rq_clock() in
unthrottle_offline_cfs_rqs().
We only need to call rq_clock_start_loop_update() before the
loop starts and rq_clock_stop_loop_update() after the loop
to avoid this warning.
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
---
kernel/sched/fair.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index af9604f4b135..9e961e0ec971 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6124,6 +6124,13 @@ static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
lockdep_assert_rq_held(rq);
+ /*
+ * The rq clock has already been updated before the
+ * set_rq_offline() runs, so we should skip updating
+ * the rq clock again in unthrottle_cfs_rq().
+ */
+ rq_clock_start_loop_update(rq);
+
rcu_read_lock();
list_for_each_entry_rcu(tg, &task_groups, list) {
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
@@ -6146,6 +6153,8 @@ static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
unthrottle_cfs_rq(cfs_rq);
}
rcu_read_unlock();
+
+ rq_clock_stop_loop_update(rq);
}
#else /* CONFIG_CFS_BANDWIDTH */
--
2.37.0 (Apple Git-136)
next prev parent reply other threads:[~2023-06-08 6:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 6:33 [PATCH v4 0/4] Fix some warnings about rq clock Hao Jia
2023-06-08 6:33 ` [PATCH v4 1/4] sched/core: Fixed missing rq clock update before calling set_rq_offline() Hao Jia
2023-06-08 6:33 ` [PATCH v4 2/4] sched/core: Avoid double calling update_rq_clock() in __balance_push_cpu_stop() Hao Jia
2023-06-08 6:33 ` [PATCH v4 3/4] sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle() Hao Jia
2023-06-08 6:33 ` Hao Jia [this message]
2023-06-08 21:06 ` [PATCH v4 4/4] sched/core: Avoid multiple calling update_rq_clock() in unthrottle_offline_cfs_rqs() Benjamin Segall
2023-06-09 3:19 ` [External] " Hao Jia
2023-06-09 20:11 ` Benjamin Segall
2023-06-12 2:40 ` Hao Jia
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