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Date: Mon, 10 Apr 2023 16:12:06 +0800
From: Hao Jia <jiahao.os@...edance.com>
To: mingo@...hat.com, peterz@...radead.org, mingo@...nel.org,
juri.lelli@...hat.com, vincent.guittot@...aro.org,
dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
mgorman@...hsingularity.net
Cc: linux-kernel@...r.kernel.org, Hao Jia <jiahao.os@...edance.com>
Subject: [PATCH 2/2] sched/core: Avoid double calling update_rq_clock()
There are some double rq clock update warnings are triggered.
------------[ cut here ]------------
rq->clock_update_flags & RQCF_UPDATED
WARNING: CPU: 17 PID: 138 at kernel/sched/core.c:741
update_rq_clock+0xaf/0x180
Call Trace:
<TASK>
__balance_push_cpu_stop+0x146/0x180
? migration_cpu_stop+0x2a0/0x2a0
cpu_stopper_thread+0xa3/0x140
smpboot_thread_fn+0x14f/0x210
? sort_range+0x20/0x20
kthread+0xe6/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
------------[ cut here ]------------
rq->clock_update_flags & RQCF_UPDATED
WARNING: CPU: 54 PID: 0 at kernel/sched/core.c:741
update_rq_clock+0xaf/0x180
Call Trace:
<TASK>
unthrottle_cfs_rq+0x4b/0x300
__cfsb_csd_unthrottle+0xe0/0x100
__flush_smp_call_function_queue+0xaf/0x1d0
flush_smp_call_function_queue+0x49/0x90
do_idle+0x17c/0x270
cpu_startup_entry+0x19/0x20
start_secondary+0xfa/0x120
secondary_startup_64_no_verify+0xce/0xdb
------------[ 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
For the __balance_push_cpu_stop() case, we remove update_rq_clock() from
the __migrate_task() function to avoid double updating the rq clock.
And in order to avoid missing rq clock update, add update_rq_clock()
call before migration_cpu_stop() calls __migrate_task().
This also works for unthrottle_cfs_rq(), so we also removed
update_rq_clock() from the unthrottle_cfs_rq() function to avoid
warnings caused by calling it multiple times, such as
__cfsb_csd_unthrottle() and unthrottle_offline_cfs_rqs(). and
in order to avoid missing rq clock update, we correspondingly add
update_rq_clock() calls before unthrottle_cfs_rq() runs.
Note that the rq clock has been updated before the set_rq_offline()
function runs, so we don't need to add update_rq_clock() call in
unthrottle_offline_cfs_rqs().
Signed-off-by: Hao Jia <jiahao.os@...edance.com>
---
kernel/sched/core.c | 11 +++++++----
kernel/sched/fair.c | 9 ++++++---
2 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0d18c3969f90..c1abd88ec1ed 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2376,7 +2376,6 @@ static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
if (!is_cpu_allowed(p, dest_cpu))
return rq;
- update_rq_clock(rq);
rq = move_queued_task(rq, rf, p, dest_cpu);
return rq;
@@ -2434,10 +2433,12 @@ static int migration_cpu_stop(void *data)
goto out;
}
- if (task_on_rq_queued(p))
+ if (task_on_rq_queued(p)) {
+ update_rq_clock(rq);
rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
- else
+ } else {
p->wake_cpu = arg->dest_cpu;
+ }
/*
* XXX __migrate_task() can fail, at which point we might end
@@ -10759,8 +10760,10 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota,
cfs_rq->runtime_enabled = runtime_enabled;
cfs_rq->runtime_remaining = 0;
- if (cfs_rq->throttled)
+ if (cfs_rq->throttled) {
+ update_rq_clock(rq);
unthrottle_cfs_rq(cfs_rq);
+ }
rq_unlock_irq(rq, &rf);
}
if (runtime_was_enabled && !runtime_enabled)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6986ea31c984..03ced34e992e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5438,8 +5438,6 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
cfs_rq->throttled = 0;
- update_rq_clock(rq);
-
raw_spin_lock(&cfs_b->lock);
cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
list_del_rcu(&cfs_rq->throttled_list);
@@ -5518,6 +5516,7 @@ static void __cfsb_csd_unthrottle(void *arg)
struct rq_flags rf;
rq_lock(rq, &rf);
+ update_rq_clock(rq);
/*
* Since we hold rq lock we're safe from concurrent manipulation of
@@ -5547,6 +5546,7 @@ static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
bool first;
if (rq == this_rq()) {
+ update_rq_clock(rq);
unthrottle_cfs_rq(cfs_rq);
return;
}
@@ -5563,6 +5563,7 @@ static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
#else
static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
{
+ update_rq_clock(rq_of(cfs_rq));
unthrottle_cfs_rq(cfs_rq);
}
#endif
@@ -5640,8 +5641,10 @@ static bool distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
if (local_unthrottle) {
rq = cpu_rq(this_cpu);
rq_lock_irqsave(rq, &rf);
- if (cfs_rq_throttled(local_unthrottle))
+ if (cfs_rq_throttled(local_unthrottle)) {
+ update_rq_clock(rq);
unthrottle_cfs_rq(local_unthrottle);
+ }
rq_unlock_irqrestore(rq, &rf);
}
--
2.37.0
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