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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAC9BC6FD18 for ; Tue, 18 Apr 2023 12:36:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231736AbjDRMgu (ORCPT ); Tue, 18 Apr 2023 08:36:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231734AbjDRMgs (ORCPT ); Tue, 18 Apr 2023 08:36:48 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8766D1CFA3 for ; Tue, 18 Apr 2023 05:36:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EBBE76329E for ; Tue, 18 Apr 2023 12:36:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A699C433D2; Tue, 18 Apr 2023 12:36:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681821406; bh=Mm2rEEx2hyEpBLAKeS/Lejbac1rsPNS4FbFGOlXlyUM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EilBoBi7iJm19/8Nb8sIfKxXj1Uhou0qeQjM7YBEwgMpGkKnTbMUL21mEOtAd//XD jZfCI/XEF22EVQNV1H56Ss4t79LEhTIvleI0mvBnYHi56me5+ZQMkULW9V7AW8F/W6 GOBYMLjTWOHIHqlUMreWU0yDlnG3TbpUb5l89l2A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Michal=20Koutn=C3=BD?= , Waiman Long , Tejun Heo Subject: [PATCH 5.10 114/124] cgroup/cpuset: Add cpuset_can_fork() and cpuset_cancel_fork() methods Date: Tue, 18 Apr 2023 14:22:13 +0200 Message-Id: <20230418120313.936253661@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120309.539243408@linuxfoundation.org> References: <20230418120309.539243408@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Waiman Long commit eee87853794187f6adbe19533ed79c8b44b36a91 upstream. In the case of CLONE_INTO_CGROUP, not all cpusets are ready to accept new tasks. It is too late to check that in cpuset_fork(). So we need to add the cpuset_can_fork() and cpuset_cancel_fork() methods to pre-check it before we can allow attachment to a different cpuset. We also need to set the attach_in_progress flag to alert other code that a new task is going to be added to the cpuset. Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups") Suggested-by: Michal Koutný Signed-off-by: Waiman Long Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cpuset.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 83 insertions(+), 5 deletions(-) --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2151,6 +2151,18 @@ static int fmeter_getrate(struct fmeter static struct cpuset *cpuset_attach_old_cs; +/* + * Check to see if a cpuset can accept a new task + * For v1, cpus_allowed and mems_allowed can't be empty. + */ +static int cpuset_can_attach_check(struct cpuset *cs) +{ + if (!is_in_v2_mode() && + (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) + return -ENOSPC; + return 0; +} + /* Called by cgroups to determine if a cpuset is usable; cpuset_rwsem held */ static int cpuset_can_attach(struct cgroup_taskset *tset) { @@ -2165,10 +2177,8 @@ static int cpuset_can_attach(struct cgro percpu_down_write(&cpuset_rwsem); - /* allow moving tasks into an empty cpuset if on default hierarchy */ - ret = -ENOSPC; - if (!is_in_v2_mode() && - (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) + ret = cpuset_can_attach_check(cs); + if (ret) goto out_unlock; cgroup_taskset_for_each(task, css, tset) { @@ -2185,7 +2195,6 @@ static int cpuset_can_attach(struct cgro * changes which zero cpus/mems_allowed. */ cs->attach_in_progress++; - ret = 0; out_unlock: percpu_up_write(&cpuset_rwsem); return ret; @@ -2913,6 +2922,68 @@ static void cpuset_bind(struct cgroup_su } /* + * In case the child is cloned into a cpuset different from its parent, + * additional checks are done to see if the move is allowed. + */ +static int cpuset_can_fork(struct task_struct *task, struct css_set *cset) +{ + struct cpuset *cs = css_cs(cset->subsys[cpuset_cgrp_id]); + bool same_cs; + int ret; + + rcu_read_lock(); + same_cs = (cs == task_cs(current)); + rcu_read_unlock(); + + if (same_cs) + return 0; + + lockdep_assert_held(&cgroup_mutex); + percpu_down_write(&cpuset_rwsem); + + /* Check to see if task is allowed in the cpuset */ + ret = cpuset_can_attach_check(cs); + if (ret) + goto out_unlock; + + ret = task_can_attach(task, cs->effective_cpus); + if (ret) + goto out_unlock; + + ret = security_task_setscheduler(task); + if (ret) + goto out_unlock; + + /* + * Mark attach is in progress. This makes validate_change() fail + * changes which zero cpus/mems_allowed. + */ + cs->attach_in_progress++; +out_unlock: + percpu_up_write(&cpuset_rwsem); + return ret; +} + +static void cpuset_cancel_fork(struct task_struct *task, struct css_set *cset) +{ + struct cpuset *cs = css_cs(cset->subsys[cpuset_cgrp_id]); + bool same_cs; + + rcu_read_lock(); + same_cs = (cs == task_cs(current)); + rcu_read_unlock(); + + if (same_cs) + return; + + percpu_down_write(&cpuset_rwsem); + cs->attach_in_progress--; + if (!cs->attach_in_progress) + wake_up(&cpuset_attach_wq); + percpu_up_write(&cpuset_rwsem); +} + +/* * Make sure the new task conform to the current state of its parent, * which could have been changed by cpuset just after it inherits the * state from the parent and before it sits on the cgroup's task list. @@ -2946,6 +3017,11 @@ static void cpuset_fork(struct task_stru else guarantee_online_cpus(cs, cpus_attach); cpuset_attach_task(cs, task); + + cs->attach_in_progress--; + if (!cs->attach_in_progress) + wake_up(&cpuset_attach_wq); + percpu_up_write(&cpuset_rwsem); } @@ -2959,6 +3035,8 @@ struct cgroup_subsys cpuset_cgrp_subsys .attach = cpuset_attach, .post_attach = cpuset_post_attach, .bind = cpuset_bind, + .can_fork = cpuset_can_fork, + .cancel_fork = cpuset_cancel_fork, .fork = cpuset_fork, .legacy_cftypes = legacy_files, .dfl_cftypes = dfl_files,