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Fri, 17 Oct 2025 05:55:24 +0000 (GMT) Received: from perf (unknown [10.229.95.91]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20251017055524epsmtip17f2d85c56e9b08636122013814729936~vMZvVgE0t2236022360epsmtip1G; Fri, 17 Oct 2025 05:55:24 +0000 (GMT) Date: Fri, 17 Oct 2025 15:01:05 +0900 From: Youngmin Nam To: Juri Lelli Cc: Shrikanth Hegde , peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, m.szyprowski@samsung.com, venkat88@linux.ibm.com, jstultz@google.com, d7271.choe@samsung.com, soohyuni.kim@samsung.com, bongkyu7.kim@samsung.com, youngmin.nam@samsung.com, jkkkkk.choi@samsung.com Subject: Re: [PATCH] sched/deadline: stop dl_server before CPU goes offline Message-ID: X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 In-Reply-To: X-CMS-MailID: 20251017055524epcas2p2b7cadb80f5d09c4003ccb66d4c39c9dc X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----PDOc320tARUDg5oiqWLD4tz058SOCZsoCdAHhD7Rt0rJ7P1y=_b9054_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P cpgsPolicy: CPGSC10-234,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20251017055524epcas2p2b7cadb80f5d09c4003ccb66d4c39c9dc References: <20251009184727.673081-1-sshegde@linux.ibm.com> ------PDOc320tARUDg5oiqWLD4tz058SOCZsoCdAHhD7Rt0rJ7P1y=_b9054_ Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline On Tue, Oct 14, 2025 at 11:11:31AM +0200, Juri Lelli wrote: > Hello, > > On 10/10/25 00:17, Shrikanth Hegde wrote: > > From: Peter Zijlstra (Intel) > > > > IBM CI tool reported kernel warning[1] when running a CPU removal > > operation through drmgr[2]. i.e "drmgr -c cpu -r -q 1" > > > > WARNING: CPU: 0 PID: 0 at kernel/sched/cpudeadline.c:219 cpudl_set+0x58/0x170 > > NIP [c0000000002b6ed8] cpudl_set+0x58/0x170 > > LR [c0000000002b7cb8] dl_server_timer+0x168/0x2a0 > > Call Trace: > > [c000000002c2f8c0] init_stack+0x78c0/0x8000 (unreliable) > > [c0000000002b7cb8] dl_server_timer+0x168/0x2a0 > > [c00000000034df84] __hrtimer_run_queues+0x1a4/0x390 > > [c00000000034f624] hrtimer_interrupt+0x124/0x300 > > [c00000000002a230] timer_interrupt+0x140/0x320 > > > > Git bisects to: commit 4ae8d9aa9f9d ("sched/deadline: Fix dl_server getting stuck") > > > > This happens since: > > - dl_server hrtimer gets enqueued close to cpu offline, when > > kthread_park enqueues a fair task. > > - CPU goes offline and drmgr removes it from cpu_present_mask. > > - hrtimer fires and warning is hit. > > > > Fix it by stopping the dl_server before CPU is marked dead. > > > > [1]: https://lore.kernel.org/all/8218e149-7718-4432-9312-f97297c352b9@linux.ibm.com/ > > [2]: https://github.com/ibm-power-utilities/powerpc-utils/tree/next/src/drmgr > > > > [sshegde: wrote the changelog and tested it] > > Fixes: 4ae8d9aa9f9d ("sched/deadline: Fix dl_server getting stuck") > > Reported-by: Venkat Rao Bagalkote > > Closes: https://lore.kernel.org/all/8218e149-7718-4432-9312-f97297c352b9@linux.ibm.com > > Signed-off-by: Peter Zijlstra (Intel) > > Signed-off-by: Shrikanth Hegde > > Tested-by: Marek Szyprowski > > Tested-by: Shrikanth Hegde > > Looks good to me. > > Acked-by: Juri Lelli > > Thanks! > Juri > Hi All, Could we expect this patch to address the following issue as well? https://lore.kernel.org/all/aMKTHKfegBk4DgjA@jlelli-thinkpadt14gen4.remote.csb/ Thanks, Youngmin. ------PDOc320tARUDg5oiqWLD4tz058SOCZsoCdAHhD7Rt0rJ7P1y=_b9054_ Content-Type: text/plain; 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