From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D85EFC48BC2 for ; Wed, 23 Jun 2021 17:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC869611C9 for ; Wed, 23 Jun 2021 17:39:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229999AbhFWRlc (ORCPT ); Wed, 23 Jun 2021 13:41:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:36024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229959AbhFWRl0 (ORCPT ); Wed, 23 Jun 2021 13:41:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 832A261220; Wed, 23 Jun 2021 17:39:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624469949; bh=5Ymqz7+dfCEdV4LpMjbEdgXWNoISuPRvOh+2+wrrHvA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I/oteDY7V63qhKbb+cXbE3z58I/O5UA83juHinSKkHEoBr5A0ZEOTpFDLRzwVhBMj KA7UtbHiHviZi6cN6jbytrImqHKRHqrPSsjG/v80TzG090Q/MDWBDlq1BXs5+yMsTs UurLu3viM9vj7UxMI2aR5pM167G4Wp7lkTeiabrdvl5i999s6zJc9Wni3yDRSZG8v0 isbXbIEqxkdW+cEK45i/N5kF7mMG88M+gqo6E3hsAd6KF/H1SCxdOXwbOHeMsUEyGd u7LMtU4uj8izv7LNpnZldP92C5whTfWAeSh7sXlW8fQPsHANJnkkUO4MUIqrU1p9wD 0ofI3dsoyjVqQ== From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , Dietmar Eggemann , Daniel Bristot de Oliveira , Valentin Schneider , Mark Rutland , kernel-team@android.com, Valentin Schneider Subject: [PATCH v10 03/16] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Date: Wed, 23 Jun 2021 18:38:35 +0100 Message-Id: <20210623173848.318-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210623173848.318-1-will@kernel.org> References: <20210623173848.318-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Asymmetric systems may not offer the same level of userspace ISA support across all CPUs, meaning that some applications cannot be executed by some CPUs. As a concrete example, upcoming arm64 big.LITTLE designs do not feature support for 32-bit applications on both clusters. Modify guarantee_online_cpus() to take task_cpu_possible_mask() into account when trying to find a suitable set of online CPUs for a given task. This will avoid passing an invalid mask to set_cpus_allowed_ptr() during ->attach() and will subsequently allow the cpuset hierarchy to be taken into account when forcefully overriding the affinity mask for a task which requires migration to a compatible CPU. Cc: Tejun Heo Cc: Johannes Weiner Reviewed-by: Valentin Schneider Signed-off-by: Will Deacon --- include/linux/cpuset.h | 2 +- kernel/cgroup/cpuset.c | 43 +++++++++++++++++++++++++----------------- 2 files changed, 27 insertions(+), 18 deletions(-) diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index ed6ec677dd6b..414a8e694413 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -185,7 +185,7 @@ static inline void cpuset_read_unlock(void) { } static inline void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask) { - cpumask_copy(mask, cpu_possible_mask); + cpumask_copy(mask, task_cpu_possible_mask(p)); } static inline void cpuset_cpus_allowed_fallback(struct task_struct *p) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 6ec7303d5b1f..4e7c271e3800 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -372,18 +372,29 @@ static inline bool is_in_v2_mode(void) } /* - * Return in pmask the portion of a cpusets's cpus_allowed that - * are online. If none are online, walk up the cpuset hierarchy - * until we find one that does have some online cpus. + * Return in pmask the portion of a task's cpusets's cpus_allowed that + * are online and are capable of running the task. If none are found, + * walk up the cpuset hierarchy until we find one that does have some + * appropriate cpus. * * One way or another, we guarantee to return some non-empty subset * of cpu_online_mask. * * Call with callback_lock or cpuset_mutex held. */ -static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) +static void guarantee_online_cpus(struct task_struct *tsk, + struct cpumask *pmask) { - while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) { + const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); + struct cpuset *cs; + + if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_online_mask))) + cpumask_copy(pmask, cpu_online_mask); + + rcu_read_lock(); + cs = task_cs(tsk); + + while (!cpumask_intersects(cs->effective_cpus, pmask)) { cs = parent_cs(cs); if (unlikely(!cs)) { /* @@ -393,11 +404,13 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) * cpuset's effective_cpus is on its way to be * identical to cpu_online_mask. */ - cpumask_copy(pmask, cpu_online_mask); - return; + goto out_unlock; } } - cpumask_and(pmask, cs->effective_cpus, cpu_online_mask); + cpumask_and(pmask, pmask, cs->effective_cpus); + +out_unlock: + rcu_read_unlock(); } /* @@ -2199,15 +2212,13 @@ static void cpuset_attach(struct cgroup_taskset *tset) percpu_down_write(&cpuset_rwsem); - /* prepare for attach */ - if (cs == &top_cpuset) - cpumask_copy(cpus_attach, cpu_possible_mask); - else - guarantee_online_cpus(cs, cpus_attach); - guarantee_online_mems(cs, &cpuset_attach_nodemask_to); cgroup_taskset_for_each(task, css, tset) { + if (cs != &top_cpuset) + guarantee_online_cpus(task, cpus_attach); + else + cpumask_copy(cpus_attach, task_cpu_possible_mask(task)); /* * can_attach beforehand should guarantee that this doesn't * fail. TODO: have a better way to handle failure here @@ -3302,9 +3313,7 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) unsigned long flags; spin_lock_irqsave(&callback_lock, flags); - rcu_read_lock(); - guarantee_online_cpus(task_cs(tsk), pmask); - rcu_read_unlock(); + guarantee_online_cpus(tsk, pmask); spin_unlock_irqrestore(&callback_lock, flags); } -- 2.32.0.93.g670b81a890-goog