From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 325F233987F; Thu, 28 May 2026 20:32:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780000367; cv=none; b=EiqPuc+cHjx5ouQEM/YhaGaXh0bcCC4ATKwwmV4v2Mq7wDo7GkQG7UId5DcojFLLzr6b9WVw0gfAUKSAYY89HxfyhGjECG7XrfzPy2HQwyfPBjHR6uH8xCb8KsmwaozXPNLmpwYE8YJihTzAcnnnnyvpvSlgJxr86hBcxaKtqCw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780000367; c=relaxed/simple; bh=XNJx3QDv4p6lxkTWVQjTF4/ZgD+CV4joTfenuaEX1cE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ur+1e8InU68vzPnJ3d8io+0Mqe+HEilN92q6XUHavjAKWxwY09wMjq1yYPABi0+IwIWaIKKzDECVU+Wz+6aWDoCD+hDG4RVFQKUX0XYH097ADzjHmgc7YwPrvF1xtE6lI1+OKmhl2uuZl0W0CEJ4zKcA2LGmQGubXFo/ZKU1DeM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=opbH9FH6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="opbH9FH6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90E841F000E9; Thu, 28 May 2026 20:32:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780000366; bh=81Ke31HSxU+PM0tgtwkDaDt3qCKgilkmiOUY1OY7bo4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=opbH9FH6vMtk9wyiK1T2to31S78UpTFaurau1YIsMQFYnUt/LnBqf3EI4Sl0vTiv3 SFDDA6yU1F59vIQSLsJO2s7y87zOgF8Bz094F985tWvmxLFHdtsj9VHVXX2E3Wh5j6 tRphYCtfc9HCM44CTz69BMt8h7dakrHanKGSqohg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Peter Zijlstra (Intel)" , Venkat Rao Bagalkote , Shrikanth Hegde , Marek Szyprowski , Sasha Levin Subject: [PATCH 6.12 020/272] sched/deadline: Stop dl_server before CPU goes offline Date: Thu, 28 May 2026 21:46:34 +0200 Message-ID: <20260528194629.949050676@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194629.379955525@linuxfoundation.org> References: <20260528194629.379955525@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra (Intel) [ Upstream commit ee6e44dfe6e50b4a5df853d933a96bdff5309e6e ] 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") Closes: https://lore.kernel.org/all/8218e149-7718-4432-9312-f97297c352b9@linux.ibm.com Signed-off-by: Peter Zijlstra (Intel) Reported-by: Venkat Rao Bagalkote Signed-off-by: Shrikanth Hegde Signed-off-by: Peter Zijlstra (Intel) Tested-by: Marek Szyprowski Tested-by: Shrikanth Hegde Signed-off-by: Sasha Levin --- kernel/sched/core.c | 2 ++ kernel/sched/deadline.c | 3 +++ 2 files changed, 5 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9b238c9c71c67..1b1ddd24cb227 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8319,10 +8319,12 @@ int sched_cpu_dying(unsigned int cpu) sched_tick_stop(cpu); rq_lock_irqsave(rq, &rf); + update_rq_clock(rq); if (rq->nr_running != 1 || rq_has_pinned_tasks(rq)) { WARN(true, "Dying CPU not properly vacated!"); dump_rq_tasks(rq, KERN_WARNING); } + dl_server_stop(&rq->fair_server); rq_unlock_irqrestore(rq, &rf); calc_load_migrate(rq); diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index a6c699e43111d..cb8eff0ebd228 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1848,6 +1848,9 @@ void dl_server_start(struct sched_dl_entity *dl_se) if (!dl_se->dl_runtime || dl_se->dl_server_active) return; + if (WARN_ON_ONCE(!cpu_online(cpu_of(rq)))) + return; + dl_se->dl_server_active = 1; enqueue_dl_entity(dl_se, ENQUEUE_WAKEUP); if (!dl_task(dl_se->rq->curr) || dl_entity_preempt(dl_se, &rq->curr->dl)) -- 2.53.0