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Tue, 10 Nov 2026 22:55:08 -0800 (PST) X-Received: by 2002:a05:600c:4f55:b0:4a7:8fe8:130c with SMTP id 5b1f17b1804b1-4ba0938197dmr25954715e9.28.1794380108281; Tue, 10 Nov 2026 22:55:08 -0800 (PST) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.29.158.90]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4ba09517bc7sm24307235e9.3.2026.11.10.22.55.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 22:55:07 -0800 (PST) Date: Wed, 11 Nov 2026 07:55:05 +0100 From: Juri Lelli To: Mathieu Desnoyers Cc: peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, tglx@kernel.org, will@kernel.org, boqun@kernel.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, luca.abeni@santannapisa.it, mathieu.poirier@linaro.org, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, shuah@kernel.org, bigeasy@linutronix.de, clrkwllms@kernel.org, parri.andrea@gmail.com, m.szyprowski@samsung.com, kayracizmeci@gmail.com, weihengqiuu@gmail.com, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH v5 12/29] sched/deadline: Reject SCHED_DEADLINE on exited tasks Message-ID: References: <20261108185406.1549770-1-mathieu.desnoyers@efficios.com> <20261108185406.1549770-13-mathieu.desnoyers@efficios.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261108185406.1549770-13-mathieu.desnoyers@efficios.com> Hello, On 08/11/26 13:53, Mathieu Desnoyers wrote: > From: Juri Lelli > > sched_setattr(SCHED_DEADLINE) on a zombie task succeeds and charges > total_bw via sched_dl_overflow(), but the task has already done its > final schedule() and will never run again. Nothing releases the reserved > bandwidth. Repeating this fills total_bw to the admission cap, after > which sched_setattr(SCHED_DEADLINE) and CPU offline fail with -EBUSY. > > Reject sched_setattr(SCHED_DEADLINE) on exited tasks with -ESRCH. > > A task of the class that exited, switched to another policy, runs > switched_from_dl(), which decrements the count of deadline tasks of its > cpuset that cgroup_task_dead() decremented already: at 0 with a deadline > task left in it, the cpuset is skipped by the next rebuild of the root > domains' accounting, and that task's bandwidth with it. Reject that as > well. The deadline_bw_test selftest added later in this series has the > case, death_zombie_switched: on v7.4-rc1 the switch is accepted, and > the one-CPU partition root the zombie ran in admits 9 tasks of 10% after > a rebuild, with a task of 30% still in it, where 6 are due. > > Fixes: 332ac17ef5bf ("sched/deadline: Add bandwidth management for SCHED_DEADLINE tasks") > Reported-by: Weiheng Qiu > Closes: https://lore.kernel.org/all/3f6e6c87-645b-45fd-8fc6-8da5bc5b82d8@gmail.com/ > Link: https://lore.kernel.org/all/20261103-b4-sched-dl-bw-fixes-v1-4-dd761fe005b4@redhat.com/ > Cc: stable@vger.kernel.org > Signed-off-by: Juri Lelli > [mathieu: reject a task of the class leaving it too, found by the > Sashiko AI review of the patch] > Signed-off-by: Mathieu Desnoyers > --- Looks good to me, thanks! Best, Juri