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From: Peter Zijlstra <peterz@infradead.org>
To: Vineeth Remanan Pillai <vineeth@bitbyteword.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
	Ilya Maximets <i.maximets@ovn.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	vineethrp@google.com, shraash@google.com
Subject: Re: [v6.12] WARNING: at kernel/sched/deadline.c:1995 enqueue_dl_entity (task blocked for more than 28262 seconds)
Date: Mon, 9 Dec 2024 11:55:14 +0100	[thread overview]
Message-ID: <20241209105514.GK21636@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <CAO7JXPhdv+Jx_UpAq=-aG-BKwiyjZ2kvuZDM4+GLjbya_=ZJsw@mail.gmail.com>

On Fri, Dec 06, 2024 at 11:57:30AM -0500, Vineeth Remanan Pillai wrote:

> I was able to reproduce this WARN_ON couple of days back with
> syzkaller. dlserver's dl_se gets enqueued during a update_curr while
> the dlserver is stopped. And subsequent dlserver start will cause a
> double enqueue. 

Right, I spotted that hole late last week. There is this thread:

  https://lore.kernel.org/all/20241209094941.GF21636@noisy.programming.kicks-ass.net/T/#u

Where I just added this thunk:

  @@ -1674,6 +1679,12 @@ void dl_server_start(struct sched_dl_entity *dl_se)
 
 void dl_server_stop(struct sched_dl_entity *dl_se)
 {
+	if (current->dl_server == dl_se) {
+		struct rq *rq = rq_of_dl_se(dl_se);
+		trace_printk("stop fair server %d\n", cpu_of(rq));
+		current->dl_server = NULL;
+	}
+
 	if (!dl_se->dl_runtime)
 		return;
 
Which was my attempt at plugging said hole. But since I do not have
means of reproduction, I'm not at all sure it is sufficient :/


  parent reply	other threads:[~2024-12-09 10:55 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-04 12:47 Ilya Maximets
2024-12-06 15:18 ` Joel Fernandes
2024-12-06 16:57   ` Vineeth Remanan Pillai
2024-12-06 17:24     ` Joel Fernandes
2024-12-09 10:48       ` Juri Lelli
2024-12-09 10:55     ` Peter Zijlstra [this message]
2024-12-09 12:29       ` Vineeth Remanan Pillai
2024-12-09 12:34         ` Ilya Maximets
2024-12-10  0:31           ` Ilya Maximets
2024-12-09 12:56         ` Peter Zijlstra
2024-12-09 13:56           ` Vineeth Remanan Pillai
2024-12-09 14:01             ` Peter Zijlstra
2024-12-09 14:12               ` Vineeth Remanan Pillai
2024-12-10  0:34           ` Ilya Maximets
2024-12-10  2:52             ` Vineeth Remanan Pillai
2024-12-10  2:58               ` Vineeth Remanan Pillai
2024-12-10  9:28                 ` Ilya Maximets
2024-12-10 23:16                   ` Ilya Maximets
2024-12-11  2:30                     ` Vineeth Remanan Pillai
2024-12-11  9:48                       ` Ilya Maximets
2024-12-10 16:11               ` Marcel Ziswiler
2024-12-10 16:08           ` Marcel Ziswiler

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