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 1/4] sched/core: Fixed missing rq clock update before calling set_rq_offline()
Date: Thu, 8 Jun 2023 14:33:09 +0800 [thread overview]
Message-ID: <20230608063312.79440-2-jiahao.os@bytedance.com> (raw)
In-Reply-To: <20230608063312.79440-1-jiahao.os@bytedance.com>
This is triggered during cpu offline when CONFIG_CPU_FREQ is enabled
and cpufreq is set to powersave:
------------[ cut here ]------------
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 24 PID: 754 at kernel/sched/sched.h:1496
enqueue_top_rt_rq+0x139/0x160
Call Trace:
<TASK>
? intel_pstate_update_util+0x3b0/0x3b0
rq_offline_rt+0x1b7/0x250
set_rq_offline.part.120+0x28/0x60
rq_attach_root+0xc4/0xd0
cpu_attach_domain+0x3dc/0x7f0
? __schedule+0x65e/0x1310
partition_sched_domains_locked+0x2a5/0x3c0
rebuild_sched_domains_locked+0x477/0x830
? percpu_rwsem_wait+0x140/0x140
rebuild_sched_domains+0x1b/0x30
cpuset_hotplug_workfn+0x2ca/0xc90
? balance_push+0x56/0x120
? _raw_spin_unlock+0x15/0x30
? finish_task_switch+0x98/0x2f0
? __switch_to+0x116/0x410
? __schedule+0x65e/0x1310 ? internal_add_timer+0x42/0x60
? _raw_spin_unlock_irqrestore+0x23/0x40
? add_timer_on+0xd5/0x130
process_one_work+0x1bc/0x3d0
worker_thread+0x4c/0x380
? preempt_count_add+0x56/0xa0
? rescuer_thread+0x310/0x310
kthread+0xe6/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
More detailed key function call graph:
rq_offline_rt()
__disable_runtime()
sched_rt_rq_enqueue()
enqueue_top_rt_rq()
cpufreq_update_util() <-- depends on CONFIG_CPU_FREQ
data->func(data, *rq_clock(rq)*, flags)
intel_pstate_update_util() <-- powersave policy callback function
Before calling set_rq_offline() we need to update the rq clock to avoid
using the old rq clock, and use rq_lock_irqsave()/rq_unlock_irqrestore()
to replace raw_spin_rq_lock_irqsave()/raw_spin_rq_unlock_irqrestore() to
ensure that rq->clock_update_flags are cleared before updating the rq
clock.
Steps to reproduce:
1. Enable CONFIG_SMP and CONFIG_CPU_FREQ when compiling the kernel
2. echo 1 > /sys/kernel/debug/clear_warn_once
3. cpupower -c all frequency-set -g powersave
4. Run some rt tasks e.g. Create 5*n rt (100% running) tasks (on a
system with n CPUs)
5. Offline cpu one by one until the warninng is triggered
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
---
kernel/sched/topology.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 6682535e37c8..b89497696880 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -487,15 +487,17 @@ static void free_rootdomain(struct rcu_head *rcu)
void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
struct root_domain *old_rd = NULL;
- unsigned long flags;
+ struct rq_flags rf;
- raw_spin_rq_lock_irqsave(rq, flags);
+ rq_lock_irqsave(rq, &rf);
if (rq->rd) {
old_rd = rq->rd;
- if (cpumask_test_cpu(rq->cpu, old_rd->online))
+ if (cpumask_test_cpu(rq->cpu, old_rd->online)) {
+ update_rq_clock(rq);
set_rq_offline(rq);
+ }
cpumask_clear_cpu(rq->cpu, old_rd->span);
@@ -515,7 +517,7 @@ void rq_attach_root(struct rq *rq, struct root_domain *rd)
if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
set_rq_online(rq);
- raw_spin_rq_unlock_irqrestore(rq, flags);
+ rq_unlock_irqrestore(rq, &rf);
if (old_rd)
call_rcu(&old_rd->rcu, free_rootdomain);
--
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 ` Hao Jia [this message]
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 ` [PATCH v4 4/4] sched/core: Avoid multiple calling update_rq_clock() in unthrottle_offline_cfs_rqs() Hao Jia
2023-06-08 21:06 ` 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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