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From: K Prateek Nayak <kprateek.nayak@amd.com>
To: Juri Lelli <juri.lelli@redhat.com>
Cc: Andrea Righi <arighi@nvidia.com>,
	John Stultz <jstultz@google.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Connor O'Brien <connoro@google.com>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	"Valentin Schneider" <vschneid@redhat.com>,
	Suleiman Souhlal <suleiman@google.com>,
	Metin Kaya <Metin.Kaya@arm.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Zimuzo Ezeozue <zezeozue@google.com>,
	Waiman Long <longman@redhat.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	"Qais Yousef" <qyousef@layalina.io>,
	Xuewen Yan <xuewen.yan94@gmail.com>,
	kuyo chang <kuyo.chang@mediatek.com>, hupu <hupu.gm@gmail.com>,
	Zhan Xusheng <zhanxusheng@xiaomi.com>,
	"zhidao su (Xiaomi)" <soolaugust@gmail.com>,
	Hui Su <sh_def@163.com>,
	"Shubhang Kaushik (Ampere)" <sh@gentwo.org>,
	<kernel-team@android.com>
Subject: Re: [PATCH v33 7/7] sched/proxy: Add deactivated (sleeping) owner handling to find_proxy_task()
Date: Thu, 29 Oct 2026 08:57:11 +0530	[thread overview]
Message-ID: <faec8c94-0837-430b-ba60-00fa4a8a5eb4@amd.com> (raw)
In-Reply-To: <auHQJ8vq6VtL2Uf0@jlelli-thinkpadt14gen4.remote.csb>

Hello Juri,

On 10/28/2026 4:06 PM, Juri Lelli wrote:
>> Ack! But this is only needed for wakeup so just:
>>
>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>> index c0ebdcde5fe5..20c388b55c50 100644
>> --- a/kernel/sched/deadline.c
>> +++ b/kernel/sched/deadline.c
>> @@ -2657,7 +2657,7 @@ static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused
>>  	struct rq_flags rf;
>>  	struct rq *rq;
>>  
>> -	if (READ_ONCE(p->__state) != TASK_WAKING)
>> +	if (task_on_rq_migrating(rq))
>>  		return;
>>  
>>  	rq = task_rq(p);
>> ---
>>
>> should be enough then?
> 
> It is enough, but I now fear too 'broad'? :)
> 
> Looks like dl_task_offline_migration() ends up here via set_task_cpu();
> in that case the task was throttled and found the cpu was running on has
> been hotplugged so it needs a new cpu at replenishment. All bandwidth
> accouting is done by dl_task_offline_migration() itself, the task is not
> WAKING so migrate_task_rq_dl() has nothing to do and bails early
> correctly. If we use task_on_rq_migrating() it won't bail early anymore
> and double subtracting? Adding !p->is_blocked seems to cover this case
> as well?

Ack! '!task_on_migrating(p) && p->is_blocked' should cover all cases.

That said, the way dl_task_offline_migration() migrates the throttled
task off an offline rq is interesting :-)

-- 
Thanks and Regards,
Prateek


  reply	other threads:[~2026-10-29  3:27 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-23 22:04 [PATCH v33 0/7] Sleeping Owner Handling for Proxy Execution (v33) John Stultz
2026-10-23 22:04 ` [PATCH v33 1/7] sched/psi: Preserve sleep-persistent PSI flags on off-CPU sleeping dequeues John Stultz
2026-10-24 11:44   ` Peter Zijlstra
2026-10-26  5:00     ` K Prateek Nayak
2026-10-26  4:32   ` K Prateek Nayak
2026-10-26  5:16   ` Zhan Xusheng
2026-10-29 22:02   ` Tejun Heo
2026-10-23 22:04 ` [PATCH v33 2/7] sched/core: Use the scheduling context for remote ticks John Stultz
2026-10-24 13:44   ` Kayra Cizmeci
2026-10-23 22:04 ` [PATCH v33 3/7] sched/core: Activate blocked donor when no owner is found John Stultz
2026-10-24  8:33   ` Andrea Righi
2026-10-26  3:02     ` K Prateek Nayak
2026-10-23 22:04 ` [PATCH v33 4/7] sched/proxy: Set TASK_RUNNING when shortcuting return migration John Stultz
2026-10-24  8:36   ` Andrea Righi
2026-10-26  3:09     ` K Prateek Nayak
2026-10-23 22:04 ` [PATCH v33 5/7] sched/proxy: Break cyclic proxy chains by deactivating blocked tasks John Stultz
2026-10-24 21:19   ` Kayra Cizmeci
2026-10-23 22:04 ` [PATCH v33 6/7] sched/proxy: Detect cycles in proxy walks earlier John Stultz
2026-10-24 15:34   ` Kayra Cizmeci
2026-10-23 22:04 ` [PATCH v33 7/7] sched/proxy: Add deactivated (sleeping) owner handling to find_proxy_task() John Stultz
2026-10-24  9:07   ` Andrea Righi
2026-10-26  4:26     ` K Prateek Nayak
2026-10-27 16:22       ` Juri Lelli
2026-10-28  3:36         ` K Prateek Nayak
2026-10-28 10:01           ` Juri Lelli
2026-10-28 10:11             ` K Prateek Nayak
2026-10-28 10:36               ` Juri Lelli
2026-10-29  3:27                 ` K Prateek Nayak [this message]
2026-10-26  7:40   ` K Prateek Nayak
2026-10-26 19:59   ` Kayra Cizmeci

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