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=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 7A5E7C63793 for ; Tue, 20 Jul 2021 14:25:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6042F6120F for ; Tue, 20 Jul 2021 14:25:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239570AbhGTNpA (ORCPT ); Tue, 20 Jul 2021 09:45:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38145 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239847AbhGTNjR (ORCPT ); Tue, 20 Jul 2021 09:39:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626790794; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=kydm/WGOt7L+xqgLRjO/qrii4XIoUJyUJ2jQIcmKKhI=; b=JbWA3MWHm/4hFmqaFQ7K60N2PdZOEI0srDrSL7p3yVOK3BC3BMhjGjT75Pl6dnFqMGJwgo G/QK5l2nqa2AJRztR6opTqMkpAugQpOSgEFkrWhb65YLzefV9PWjgGaoRmt03c7KkmXZRO Gt+7mqglzk0+wRHf5HxTk+JWmyvyTC8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-321-ASqZChOtMaub8Yl4V92dKA-1; Tue, 20 Jul 2021 10:19:53 -0400 X-MC-Unique: ASqZChOtMaub8Yl4V92dKA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5894B100C662; Tue, 20 Jul 2021 14:19:51 +0000 (UTC) Received: from llong.com (ovpn-116-153.rdu2.redhat.com [10.10.116.153]) by smtp.corp.redhat.com (Postfix) with ESMTP id F1369369A; Tue, 20 Jul 2021 14:19:45 +0000 (UTC) From: Waiman Long To: Tejun Heo , Zefan Li , Johannes Weiner , Jonathan Corbet , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Roman Gushchin , Phil Auld , Peter Zijlstra , Juri Lelli , Frederic Weisbecker , Marcelo Tosatti , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Waiman Long Subject: [PATCH v3 3/9] cgroup/cpuset: Fix violation of cpuset locking rule Date: Tue, 20 Jul 2021 10:18:28 -0400 Message-Id: <20210720141834.10624-4-longman@redhat.com> In-Reply-To: <20210720141834.10624-1-longman@redhat.com> References: <20210720141834.10624-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The cpuset fields that manage partition root state do not strictly follow the cpuset locking rule that update to cpuset has to be done with both the callback_lock and cpuset_mutex held. This is now fixed by making sure that the locking rule is upheld. Fixes: 3881b86128d0 ("cpuset: Add an error state to cpuset.sched.partition") Fixes: 4b842da276a8 ("cpuset: Make CPU hotplug work with partition) Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 58 +++++++++++++++++++++++++----------------- 1 file changed, 35 insertions(+), 23 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index b00982e6f6d8..04a6951abe2a 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1148,6 +1148,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, struct cpuset *parent = parent_cs(cpuset); int adding; /* Moving cpus from effective_cpus to subparts_cpus */ int deleting; /* Moving cpus from subparts_cpus to effective_cpus */ + int new_prs; bool part_error = false; /* Partition error? */ percpu_rwsem_assert_held(&cpuset_rwsem); @@ -1183,6 +1184,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, * A cpumask update cannot make parent's effective_cpus become empty. */ adding = deleting = false; + new_prs = cpuset->partition_root_state; if (cmd == partcmd_enable) { cpumask_copy(tmp->addmask, cpuset->cpus_allowed); adding = true; @@ -1247,11 +1249,11 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, switch (cpuset->partition_root_state) { case PRS_ENABLED: if (part_error) - cpuset->partition_root_state = PRS_ERROR; + new_prs = PRS_ERROR; break; case PRS_ERROR: if (!part_error) - cpuset->partition_root_state = PRS_ENABLED; + new_prs = PRS_ENABLED; break; } /* @@ -1260,10 +1262,10 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, part_error = (prev_prs == PRS_ERROR); } - if (!part_error && (cpuset->partition_root_state == PRS_ERROR)) + if (!part_error && (new_prs == PRS_ERROR)) return 0; /* Nothing need to be done */ - if (cpuset->partition_root_state == PRS_ERROR) { + if (new_prs == PRS_ERROR) { /* * Remove all its cpus from parent's subparts_cpus. */ @@ -1272,7 +1274,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, parent->subparts_cpus); } - if (!adding && !deleting) + if (!adding && !deleting && (new_prs == cpuset->partition_root_state)) return 0; /* @@ -1299,6 +1301,9 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, } parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus); + + if (cpuset->partition_root_state != new_prs) + cpuset->partition_root_state = new_prs; spin_unlock_irq(&callback_lock); return cmd == partcmd_update; @@ -1321,6 +1326,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) struct cpuset *cp; struct cgroup_subsys_state *pos_css; bool need_rebuild_sched_domains = false; + int new_prs; rcu_read_lock(); cpuset_for_each_descendant_pre(cp, pos_css, cs) { @@ -1360,7 +1366,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) * update_tasks_cpumask() again for tasks in the parent * cpuset if the parent's subparts_cpus changes. */ - if ((cp != cs) && cp->partition_root_state) { + new_prs = cp->partition_root_state; + if ((cp != cs) && new_prs) { switch (parent->partition_root_state) { case PRS_DISABLED: /* @@ -1370,7 +1377,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) */ WARN_ON_ONCE(cp->partition_root_state != PRS_ERROR); - cp->partition_root_state = PRS_DISABLED; + new_prs = PRS_DISABLED; /* * clear_bit() is an atomic operation and @@ -1391,11 +1398,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) /* * When parent is invalid, it has to be too. */ - cp->partition_root_state = PRS_ERROR; - if (cp->nr_subparts_cpus) { - cp->nr_subparts_cpus = 0; - cpumask_clear(cp->subparts_cpus); - } + new_prs = PRS_ERROR; break; } } @@ -1407,8 +1410,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) spin_lock_irq(&callback_lock); cpumask_copy(cp->effective_cpus, tmp->new_cpus); - if (cp->nr_subparts_cpus && - (cp->partition_root_state != PRS_ENABLED)) { + if (cp->nr_subparts_cpus && (new_prs != PRS_ENABLED)) { cp->nr_subparts_cpus = 0; cpumask_clear(cp->subparts_cpus); } else if (cp->nr_subparts_cpus) { @@ -1435,6 +1437,10 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) = cpumask_weight(cp->subparts_cpus); } } + + if (new_prs != cp->partition_root_state) + cp->partition_root_state = new_prs; + spin_unlock_irq(&callback_lock); WARN_ON(!is_in_v2_mode() && @@ -1944,25 +1950,25 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, */ static int update_prstate(struct cpuset *cs, int new_prs) { - int err; + int err, old_prs = cs->partition_root_state; struct cpuset *parent = parent_cs(cs); struct tmpmasks tmpmask; - if (new_prs == cs->partition_root_state) + if (old_prs == new_prs) return 0; /* * Cannot force a partial or invalid partition root to a full * partition root. */ - if (new_prs && (cs->partition_root_state < 0)) + if (new_prs && (old_prs == PRS_ERROR)) return -EINVAL; if (alloc_cpumasks(NULL, &tmpmask)) return -ENOMEM; err = -EINVAL; - if (!cs->partition_root_state) { + if (!old_prs) { /* * Turning on partition root requires setting the * CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed @@ -1981,14 +1987,12 @@ static int update_prstate(struct cpuset *cs, int new_prs) update_flag(CS_CPU_EXCLUSIVE, cs, 0); goto out; } - cs->partition_root_state = PRS_ENABLED; } else { /* * Turning off partition root will clear the * CS_CPU_EXCLUSIVE bit. */ - if (cs->partition_root_state == PRS_ERROR) { - cs->partition_root_state = PRS_DISABLED; + if (old_prs == PRS_ERROR) { update_flag(CS_CPU_EXCLUSIVE, cs, 0); err = 0; goto out; @@ -1999,8 +2003,6 @@ static int update_prstate(struct cpuset *cs, int new_prs) if (err) goto out; - cs->partition_root_state = PRS_DISABLED; - /* Turning off CS_CPU_EXCLUSIVE will not return error */ update_flag(CS_CPU_EXCLUSIVE, cs, 0); } @@ -2017,6 +2019,12 @@ static int update_prstate(struct cpuset *cs, int new_prs) rebuild_sched_domains_locked(); out: + if (!err) { + spin_lock_irq(&callback_lock); + cs->partition_root_state = new_prs; + spin_unlock_irq(&callback_lock); + } + free_cpumasks(NULL, &tmpmask); return err; } @@ -3080,8 +3088,10 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) if (is_partition_root(cs) && (cpumask_empty(&new_cpus) || (parent->partition_root_state == PRS_ERROR))) { if (cs->nr_subparts_cpus) { + spin_lock_irq(&callback_lock); cs->nr_subparts_cpus = 0; cpumask_clear(cs->subparts_cpus); + spin_unlock_irq(&callback_lock); compute_effective_cpumask(&new_cpus, cs, parent); } @@ -3095,7 +3105,9 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) cpumask_empty(&new_cpus)) { update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp); + spin_lock_irq(&callback_lock); cs->partition_root_state = PRS_ERROR; + spin_unlock_irq(&callback_lock); } cpuset_force_rebuild(); } -- 2.18.1