From: Juri Lelli <juri.lelli@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
linux-kernel@vger.kernel.org,
"Dietmar Eggemann" <dietmar.eggemann@arm.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Ben Segall" <bsegall@google.com>, "Mel Gorman" <mgorman@suse.de>,
"Valentin Schneider" <vschneid@redhat.com>,
"K Prateek Nayak" <kprateek.nayak@amd.com>,
"Luca Abeni" <luca.abeni@santannapisa.it>,
"Mathieu Poirier" <mathieu.poirier@linaro.org>,
"Waiman Long" <longman@redhat.com>,
"Ridong Chen" <ridong.chen@linux.dev>,
"Tejun Heo" <tj@kernel.org>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Michal Koutný" <mkoutny@suse.com>,
"Shuah Khan" <shuah@kernel.org>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
"Clark Williams" <clrkwllms@kernel.org>,
cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH v2 01/21] sched: Reject SCHED_FLAG_KEEP_PARAMS before reserving deadline bandwidth
Date: Thu, 5 Nov 2026 08:14:41 +0100 [thread overview]
Message-ID: <auws4cpKvQnmNM4f@jlelli-thinkpadt14gen4.remote.csb> (raw)
In-Reply-To: <20261104211207.1392343-2-mathieu.desnoyers@efficios.com>
Hello,
On 04/11/26 16:11, Mathieu Desnoyers wrote:
> __sched_setscheduler() returns -EINVAL for a SCHED_FLAG_KEEP_PARAMS
> request that would change scheduling class, after sched_dl_overflow()
> has reserved the bandwidth of the request, and nothing gives it back.
> Switching a SCHED_OTHER task to SCHED_DEADLINE that way fails and leaks
> the runtime that sched_setattr() filled in from the task's slice, up to
> 100ms with a custom one, into the root domain's total_bw. Repeated, it
> makes the root domain refuse every deadline task, and refuse to offline
> its last CPU.
>
> Reserve the bandwidth after that check, last of the checks. A refused
> request also leaves sched_reset_on_fork as it was again.
>
> Fixes: 8a70415351ba ("sched: Reject SCHED_FLAG_KEEP_PARAMS when it would change scheduling class")
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> ---
Makes sense to me.
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Thanks,
Juri
next prev parent reply other threads:[~2026-11-05 7:14 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 21:11 [PATCH v2 00/21] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 01/21] sched: Reject SCHED_FLAG_KEEP_PARAMS before reserving deadline bandwidth Mathieu Desnoyers
2026-11-05 7:14 ` Juri Lelli [this message]
2026-11-04 21:11 ` [PATCH v2 02/21] sched: Refuse SCHED_FLAG_KEEP_PARAMS that would change the policy Mathieu Desnoyers
2026-11-05 7:15 ` Juri Lelli
2026-11-04 21:11 ` [PATCH v2 03/21] sched/deadline: Do not admit bandwidth for parameters that are kept Mathieu Desnoyers
2026-11-05 10:20 ` Juri Lelli
2026-11-04 21:11 ` [PATCH v2 04/21] sched/deadline: Do not divide by zero active CPUs of a root domain Mathieu Desnoyers
2026-11-04 21:46 ` sashiko-bot
2026-11-05 10:53 ` Juri Lelli
2026-11-04 21:11 ` [PATCH v2 05/21] sched/deadline: Do not BUG() on a deadline task with no active CPU allowed Mathieu Desnoyers
2026-11-05 10:59 ` Juri Lelli
2026-11-04 21:11 ` [PATCH v2 06/21] sched/deadline: Do not lose a throttled task switched out and back Mathieu Desnoyers
2026-11-04 22:09 ` sashiko-bot
2026-11-05 14:48 ` Juri Lelli
2026-11-04 21:11 ` [PATCH v2 07/21] sched/deadline: Do not release a departing sleeper's bandwidth twice Mathieu Desnoyers
2026-11-04 22:15 ` sashiko-bot
2026-11-04 21:11 ` [PATCH v2 08/21] selftests/sched: Add a test of SCHED_DEADLINE policy round trips Mathieu Desnoyers
2026-11-05 15:00 ` Juri Lelli
2026-11-04 21:11 ` [PATCH v2 09/21] sched/deadline: Keep departing bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-04 22:44 ` sashiko-bot
2026-11-04 21:11 ` [PATCH v2 10/21] selftests/sched: Test SCHED_DEADLINE " Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 11/21] sched/deadline: Do not take a waking task's bandwidth off a runqueue it left Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 12/21] sched/debug: Show the deadline bandwidth of each runqueue Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 13/21] sched/deadline: Rebuild the root domains' accounting without cpusets too Mathieu Desnoyers
2026-11-04 23:18 ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 14/21] selftests/sched: Add a test of SCHED_DEADLINE bandwidth accounting Mathieu Desnoyers
2026-11-04 21:12 ` [PATCH v2 15/21] sched/deadline: Record the root domain holding a task's bandwidth Mathieu Desnoyers
2026-11-04 23:31 ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 16/21] sched/deadline: Move a task's bandwidth only where room was made Mathieu Desnoyers
2026-11-04 21:12 ` [PATCH v2 17/21] cgroup/cpuset: Give back the bandwidth an attach did not move Mathieu Desnoyers
2026-11-04 23:56 ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 18/21] sched/deadline: Credit a rebuild to a CPU that can hold the bandwidth Mathieu Desnoyers
2026-11-05 0:18 ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 19/21] sched: Clear cpuset_locked where the policy check retries Mathieu Desnoyers
2026-11-05 16:43 ` Andrea Parri
2026-11-05 17:08 ` Mathieu Desnoyers
2026-11-04 21:12 ` [PATCH v2 20/21] sched/deadline: Cancel the replenishment timer with the parameters Mathieu Desnoyers
2026-11-05 0:25 ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 21/21] sched/deadline: Count the bandwidth a boosted task is given Mathieu Desnoyers
2026-11-05 0:36 ` sashiko-bot
[not found] ` <CGME20261105111941eucas1p1b50e9720b000ca86204aff3977c9fcbb@eucas1p1.samsung.com>
2026-11-05 11:19 ` [PATCH v2 00/21] sched/deadline: bandwidth accounting fixes and selftests Marek Szyprowski
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