From nobody Sat Feb 7 19:41:03 2026 Received: from relay.smtp-ext.broadcom.com (relay.smtp-ext.broadcom.com [192.19.144.207]) (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 8444A332915; Mon, 27 Oct 2025 22:44:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.19.144.207 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761605080; cv=none; b=H2IjCZi7UGo97CmUhv6xLK796mckW1G/OtTSFDZazW1MHIc5TIh61DLTaExep6r2zZXcrrGaJDenhu+wmBmp6/6TDZa1mAxPLyvDfeIFlzSvxaJx7+7AgCEGAVnSgOH/BPKOKGaLZXyZPRksfKDn5iQl6rlXre8uwjWS19kP8Y8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761605080; c=relaxed/simple; bh=zmbCaPOzgGv6cTQN82X12pgX4PFQ+szt+cRvH1+ZgjY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mubqv04SdDwtL4j47gFEzHbWI9LbFSvOjuZf/yEYcwESppGOJ6tjTtPN6DmwxDoNaWZcXu16KF/4Wl6tq6No5t8Fztf+khGHHbB++AU1m9vJJe2EDCTDeoKMjzuqJgujbJRnl4tECioxY+3KxEg3Z44Ng3ydOODUkIMa4IiQbj8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=broadcom.com; spf=fail smtp.mailfrom=broadcom.com; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b=ZGi7U6Nr; arc=none smtp.client-ip=192.19.144.207 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=broadcom.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=broadcom.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="ZGi7U6Nr" Received: from mail-lvn-it-01.broadcom.com (mail-lvn-it-01.lvn.broadcom.net [10.36.132.253]) by relay.smtp-ext.broadcom.com (Postfix) with ESMTP id A016DC0003F8; Mon, 27 Oct 2025 15:44:37 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 relay.smtp-ext.broadcom.com A016DC0003F8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=broadcom.com; s=dkimrelay; t=1761605077; bh=zmbCaPOzgGv6cTQN82X12pgX4PFQ+szt+cRvH1+ZgjY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZGi7U6NrJNRAvOKvqAdUIfJdE4i5yg8CGQbgEG7XP/Sj90KN4AYPhHS63JDFUMP1N UJQo8SfzcDZwyYlfm9DhrAfIqd7x9HPBMiiV4g3CExqwYzn3eM0M6qcXUDb806QFWn PwpgqaQbdIKhJKpBlorKiRmWkfn6J5aduHqa4BJU= Received: from stbirv-lnx-1.igp.broadcom.net (stbirv-lnx-1.igp.broadcom.net [10.67.48.32]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail-lvn-it-01.broadcom.com (Postfix) with ESMTPSA id 3EFEA1800053F; Mon, 27 Oct 2025 15:44:07 -0700 (PDT) From: Florian Fainelli To: stable@vger.kernel.org Cc: Doug Berger , Peter Zijlstra , Florian Fainelli , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org (open list:SCHEDULER), Greg Kroah-Hartman , Sasha Levin , bcm-kernel-feedback-list@broadcom.com Subject: [PATCH stable 5.4] sched/deadline: only set free_cpus for online runqueues Date: Mon, 27 Oct 2025 15:43:47 -0700 Message-Id: <20251027224351.2893946-3-florian.fainelli@broadcom.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251027224351.2893946-1-florian.fainelli@broadcom.com> References: <20251027224351.2893946-1-florian.fainelli@broadcom.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Doug Berger [ Upstream commit 382748c05e58a9f1935f5a653c352422375566ea ] Commit 16b269436b72 ("sched/deadline: Modify cpudl::free_cpus to reflect rd->online") introduced the cpudl_set/clear_freecpu functions to allow the cpu_dl::free_cpus mask to be manipulated by the deadline scheduler class rq_on/offline callbacks so the mask would also reflect this state. Commit 9659e1eeee28 ("sched/deadline: Remove cpu_active_mask from cpudl_find()") removed the check of the cpu_active_mask to save some processing on the premise that the cpudl::free_cpus mask already reflected the runqueue online state. Unfortunately, there are cases where it is possible for the cpudl_clear function to set the free_cpus bit for a CPU when the deadline runqueue is offline. When this occurs while a CPU is connected to the default root domain the flag may retain the bad state after the CPU has been unplugged. Later, a different CPU that is transitioning through the default root domain may push a deadline task to the powered down CPU when cpudl_find sees its free_cpus bit is set. If this happens the task will not have the opportunity to run. One example is outlined here: https://lore.kernel.org/lkml/20250110233010.2339521-1-opendmb@gmail.com Another occurs when the last deadline task is migrated from a CPU that has an offlined runqueue. The dequeue_task member of the deadline scheduler class will eventually call cpudl_clear and set the free_cpus bit for the CPU. This commit modifies the cpudl_clear function to be aware of the online state of the deadline runqueue so that the free_cpus mask can be updated appropriately. It is no longer necessary to manage the mask outside of the cpudl_set/clear functions so the cpudl_set/clear_freecpu functions are removed. In addition, since the free_cpus mask is now only updated under the cpudl lock the code was changed to use the non-atomic __cpumask functions. Signed-off-by: Doug Berger Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Florian Fainelli --- kernel/sched/cpudeadline.c | 34 +++++++++------------------------- kernel/sched/cpudeadline.h | 4 +--- kernel/sched/deadline.c | 8 ++++---- 3 files changed, 14 insertions(+), 32 deletions(-) diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index 5cc4012572ec..af0048b08ea0 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -142,12 +142,13 @@ int cpudl_find(struct cpudl *cp, struct task_struct *= p, * cpudl_clear - remove a CPU from the cpudl max-heap * @cp: the cpudl max-heap context * @cpu: the target CPU + * @online: the online state of the deadline runqueue * * Notes: assumes cpu_rq(cpu)->lock is locked * * Returns: (void) */ -void cpudl_clear(struct cpudl *cp, int cpu) +void cpudl_clear(struct cpudl *cp, int cpu, bool online) { int old_idx, new_cpu; unsigned long flags; @@ -160,7 +161,7 @@ void cpudl_clear(struct cpudl *cp, int cpu) if (old_idx =3D=3D IDX_INVALID) { /* * Nothing to remove if old_idx was invalid. - * This could happen if a rq_offline_dl is + * This could happen if rq_online_dl or rq_offline_dl is * called for a CPU without -dl tasks running. */ } else { @@ -171,9 +172,12 @@ void cpudl_clear(struct cpudl *cp, int cpu) cp->elements[new_cpu].idx =3D old_idx; cp->elements[cpu].idx =3D IDX_INVALID; cpudl_heapify(cp, old_idx); - - cpumask_set_cpu(cpu, cp->free_cpus); } + if (likely(online)) + __cpumask_set_cpu(cpu, cp->free_cpus); + else + __cpumask_clear_cpu(cpu, cp->free_cpus); + raw_spin_unlock_irqrestore(&cp->lock, flags); } =20 @@ -204,7 +208,7 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl) cp->elements[new_idx].cpu =3D cpu; cp->elements[cpu].idx =3D new_idx; cpudl_heapify_up(cp, new_idx); - cpumask_clear_cpu(cpu, cp->free_cpus); + __cpumask_clear_cpu(cpu, cp->free_cpus); } else { cp->elements[old_idx].dl =3D dl; cpudl_heapify(cp, old_idx); @@ -213,26 +217,6 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl) raw_spin_unlock_irqrestore(&cp->lock, flags); } =20 -/* - * cpudl_set_freecpu - Set the cpudl.free_cpus - * @cp: the cpudl max-heap context - * @cpu: rd attached CPU - */ -void cpudl_set_freecpu(struct cpudl *cp, int cpu) -{ - cpumask_set_cpu(cpu, cp->free_cpus); -} - -/* - * cpudl_clear_freecpu - Clear the cpudl.free_cpus - * @cp: the cpudl max-heap context - * @cpu: rd attached CPU - */ -void cpudl_clear_freecpu(struct cpudl *cp, int cpu) -{ - cpumask_clear_cpu(cpu, cp->free_cpus); -} - /* * cpudl_init - initialize the cpudl structure * @cp: the cpudl max-heap context diff --git a/kernel/sched/cpudeadline.h b/kernel/sched/cpudeadline.h index 0adeda93b5fb..ecff718d94ae 100644 --- a/kernel/sched/cpudeadline.h +++ b/kernel/sched/cpudeadline.h @@ -18,9 +18,7 @@ struct cpudl { #ifdef CONFIG_SMP int cpudl_find(struct cpudl *cp, struct task_struct *p, struct cpumask *l= ater_mask); void cpudl_set(struct cpudl *cp, int cpu, u64 dl); -void cpudl_clear(struct cpudl *cp, int cpu); +void cpudl_clear(struct cpudl *cp, int cpu, bool online); int cpudl_init(struct cpudl *cp); -void cpudl_set_freecpu(struct cpudl *cp, int cpu); -void cpudl_clear_freecpu(struct cpudl *cp, int cpu); void cpudl_cleanup(struct cpudl *cp); #endif /* CONFIG_SMP */ diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 023d52d2a0f1..fd4acba1a98b 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1372,7 +1372,7 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 = deadline) if (!dl_rq->dl_nr_running) { dl_rq->earliest_dl.curr =3D 0; dl_rq->earliest_dl.next =3D 0; - cpudl_clear(&rq->rd->cpudl, rq->cpu); + cpudl_clear(&rq->rd->cpudl, rq->cpu, rq->online); } else { struct rb_node *leftmost =3D dl_rq->root.rb_leftmost; struct sched_dl_entity *entry; @@ -2297,9 +2297,10 @@ static void rq_online_dl(struct rq *rq) if (rq->dl.overloaded) dl_set_overload(rq); =20 - cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu); if (rq->dl.dl_nr_running > 0) cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr); + else + cpudl_clear(&rq->rd->cpudl, rq->cpu, true); } =20 /* Assumes rq->lock is held */ @@ -2308,8 +2309,7 @@ static void rq_offline_dl(struct rq *rq) if (rq->dl.overloaded) dl_clear_overload(rq); =20 - cpudl_clear(&rq->rd->cpudl, rq->cpu); - cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); + cpudl_clear(&rq->rd->cpudl, rq->cpu, false); } =20 void __init init_sched_dl_class(void) --=20 2.34.1