From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 965F5367B90 for ; Tue, 2 Jun 2026 02:32:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780367548; cv=none; b=tBA5tWcqAARwEWjSFL9/08jEl5wsyYe5h9aujZ1iWlecp/JEcE+1dHrUzjrQsPuydhryfjwtI2VhJ3O6OPsdN4eefqrD057/ylCPh3QL39XhC693bHabr3z/NJv7wuIZB9JDbaHP+7mwOprDpAmq09Q8O608Ei4VRW0tizMEv8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780367548; c=relaxed/simple; bh=Ha+GLcoT+d9T71Kb0/2qK0ydN3RAS84T8DmJICgVA5c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dm/WnAmcekMA0B+mcI4Tbe5rApTfmDlYba7VsQm8axDSIgHkgXmVnP1dhGYlUFqEL6lcqsWN7BiJNTf8WIh4xqqOpJbH3dXp4FyMEOzutXj8LMMNOofL1QtAUif7+q8mgjL7aWaqJz7ubcZ7lMuUApv4loigprfel2RFbQ8Dxe4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ORydZClM; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ORydZClM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1780367545; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xyGU4Uu7TBP3fnhGw8V6NIlxG+lhDxqP5/XKrDp/tpw=; b=ORydZClMf9m8FVaz9GTzKamALrb4QpRvA+W/B915dkSMj+YMpy2ptcoAHB+OJqUM/UIBV+ NJKRwa0hNnC69ldTeoruUMbnLbLGRdfc88HQ0wbvdXQWf3fckKdrCwf7vDISafdtnOs9+I KCgJvZJzT7VSQ3XMuuV3MoaskdMa1X0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-638-RltBZh7YMdu_PuO0Pk34kw-1; Mon, 01 Jun 2026 22:32:22 -0400 X-MC-Unique: RltBZh7YMdu_PuO0Pk34kw-1 X-Mimecast-MFC-AGG-ID: RltBZh7YMdu_PuO0Pk34kw_1780367541 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B4050180034C; Tue, 2 Jun 2026 02:32:20 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.88.124]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E3AE319560A6; Tue, 2 Jun 2026 02:32:18 +0000 (UTC) From: Waiman Long To: Chen Ridong , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Peter Zijlstra Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Aaron Tomlin , Guopeng Zhang , Waiman Long Subject: [PATCH-next v5 3/6] cgroup/cpuset: Expand the scope of cpuset_can_attach_check() Date: Mon, 1 Jun 2026 22:32:00 -0400 Message-ID: <20260602023203.248077-4-longman@redhat.com> In-Reply-To: <20260602023203.248077-1-longman@redhat.com> References: <20260602023203.248077-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Expand the scope of cpuset_can_attach_check() by including the setting of setsched flag inside cpuset_can_attach_check() with the new @oldcs and @psetsched argument. As cpuset_can_attach_check() is also called from cpuset_can_fork(), set the new arguments to NULL from that caller. While at it, expose the source and destination cpuset cpu/memory check results in the new attach_cpus_updated and attach_mems_updated static flags so that these flags can be used directly from cpuset_attach() without the need to do the same computations again. Two new global attach related flags are added (attach_cpus_updated & attach_mems_updated) which are set to indicate that CPUs or memory nodes are updated. These 2 flags are set in cpuset_can_attach() and are used in cpuset_attach() for optimization. Since cpuset_mutex will be released between the 2 calls, it is possible that an intervening cpuset action may change the CPU or node mask of the relevant cpusets, so check is added to set these flags if the effective_cpus or effective_mems of those cpusets is changed. Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 52 ++++++++++++++++++++++++------------------ 1 file changed, 30 insertions(+), 22 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 5c1f3ee48d5d..5c777b1237a8 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2982,12 +2982,39 @@ static struct cpuset *cpuset_attach_old_cs; * For v1, cpus_allowed and mems_allowed can't be empty. * For v2, effective_cpus can't be empty. * Note that in v1, effective_cpus = cpus_allowed. + * + * Also set the boolean flag passed in by @psetsched depending on if + * security_task_setscheduler() call is needed and @oldcs is not NULL. */ -static int cpuset_can_attach_check(struct cpuset *cs) +static int cpuset_can_attach_check(struct cpuset *cs, struct cpuset *oldcs, + bool *psetsched) { if (cpumask_empty(cs->effective_cpus) || (!is_in_v2_mode() && nodes_empty(cs->mems_allowed))) return -ENOSPC; + + if (!oldcs) + return 0; + + /* + * Skip rights over task setsched check in v2 when nothing changes, + * migration permission derives from hierarchy ownership in + * cgroup_procs_write_permission()). + */ + *psetsched = !cpuset_v2() || + !cpumask_equal(cs->effective_cpus, oldcs->effective_cpus) || + !nodes_equal(cs->effective_mems, oldcs->effective_mems); + + /* + * A v1 cpuset with tasks will have no CPU left only when CPU hotplug + * brings the last online CPU offline as users are not allowed to empty + * cpuset.cpus when there are active tasks inside. When that happens, + * we should allow tasks to migrate out without security check to make + * sure they will be able to run after migration. + */ + if (!is_in_v2_mode() && cpumask_empty(oldcs->effective_cpus)) + *psetsched = false; + return 0; } @@ -3034,29 +3061,10 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) mutex_lock(&cpuset_mutex); /* Check to see if task is allowed in the cpuset */ - ret = cpuset_can_attach_check(cs); + ret = cpuset_can_attach_check(cs, oldcs, &setsched_check); if (ret) goto out_unlock; - /* - * Skip rights over task setsched check in v2 when nothing changes, - * migration permission derives from hierarchy ownership in - * cgroup_procs_write_permission()). - */ - setsched_check = !cpuset_v2() || - !cpumask_equal(cs->effective_cpus, oldcs->effective_cpus) || - !nodes_equal(cs->effective_mems, oldcs->effective_mems); - - /* - * A v1 cpuset with tasks will have no CPU left only when CPU hotplug - * brings the last online CPU offline as users are not allowed to empty - * cpuset.cpus when there are active tasks inside. When that happens, - * we should allow tasks to migrate out without security check to make - * sure they will be able to run after migration. - */ - if (!is_in_v2_mode() && cpumask_empty(oldcs->effective_cpus)) - setsched_check = false; - cgroup_taskset_for_each(task, css, tset) { ret = task_can_attach(task); if (ret) @@ -3601,7 +3609,7 @@ static int cpuset_can_fork(struct task_struct *task, struct css_set *cset) mutex_lock(&cpuset_mutex); /* Check to see if task is allowed in the cpuset */ - ret = cpuset_can_attach_check(cs); + ret = cpuset_can_attach_check(cs, NULL, NULL); if (ret) goto out_unlock; -- 2.54.0