From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 9694B42EED9 for ; Wed, 27 May 2026 15:38:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779896337; cv=none; b=bhmHMPQWZRszKvvuRDx0OXqCTQtof/Hra16wvckn6md4g9/CkfkJ8hwPhFgM8M7JXqJE6tOpKuUQl9HcMtFsKbzPq/1sUpbIL+qkId5JwCJ6+QnU076XyHnroBcdCcPU8RKj54YwdXQVizWFBvijld8izIFU2s19/4duPeDRLhU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779896337; c=relaxed/simple; bh=vXaHGpo/cOpKoi25nWttdUbf6C9e0+GWhw1wTzmdFDc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RzQCOFmPEWvc0J5m/nRXiB5akcbBb8ikPUi9c52+JTJrDGVKRPgcguS1j98oXLjWDQEMONrm1+4eyHbpMcWf2AXc2K4+WGZcdt6mgSCLaB+Yr5a13XYe8s7ABgKwCJrv5Xq0MbjMSns1LMWwM83vXPV+WeowdJz28pg1hK90sow= 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=itilgD80; arc=none smtp.client-ip=170.10.129.124 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="itilgD80" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1779896333; 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=l7MH3OtjWXO3O907SYH4/EiI2G1a5AP5AYerCApbaVM=; b=itilgD80YTcbOeKyMuLATDzHQQzsULjDdyFUCCajpo1Jz2mRxK/YYrcdLcKEg9t0jlPdu8 Ty1ks5KBHVBoEc6uhx4f83qS9QxV8YLtap534Ee1gSBvHdDTqSaoZvutCEB4qArhpQGcO6 Zj3n9l2a7yD2em+ywaxDCHlhyybBMAY= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-679-kxy6W9r-OXG8Mbocx97J9w-1; Wed, 27 May 2026 11:38:49 -0400 X-MC-Unique: kxy6W9r-OXG8Mbocx97J9w-1 X-Mimecast-MFC-AGG-ID: kxy6W9r-OXG8Mbocx97J9w_1779896328 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id ACB051956096; Wed, 27 May 2026 15:38:47 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.81.53]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 20D961800465; Wed, 27 May 2026 15:38:46 +0000 (UTC) From: Waiman Long To: Chen Ridong , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Ingo Molnar , Peter Zijlstra Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Aaron Tomlin , Waiman Long Subject: [PATCH-next v3 2/5] cgroup/cpuset: Expand the scope of cpuset_can_attach_check() Date: Wed, 27 May 2026 11:37:57 -0400 Message-ID: <20260527153800.1557449-3-longman@redhat.com> In-Reply-To: <20260527153800.1557449-1-longman@redhat.com> References: <20260527153800.1557449-1-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 3.4.1 on 10.30.177.111 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. No functional change is expected. Reviewed-by: Chen Ridong Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 70 +++++++++++++++++++++++++----------------- 1 file changed, 42 insertions(+), 28 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index d720bcc7ef83..4457c4f11fce 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2964,19 +2964,56 @@ static int update_prstate(struct cpuset *cs, int new_prs) return 0; } +/* + * cpuset_can_attach() and cpuset_attach() specific internal data + * Protected by cpuset_mutex + */ static struct cpuset *cpuset_attach_old_cs; +static bool attach_cpus_updated; +static bool attach_mems_updated; /* * Check to see if a cpuset can accept a new task * 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; + + /* + * Update attach specific data + */ + attach_cpus_updated = !cpumask_equal(cs->effective_cpus, oldcs->effective_cpus); + attach_mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems); + + /* + * 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() || attach_cpus_updated || attach_mems_updated; + + /* + * 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; } @@ -3023,29 +3060,10 @@ 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) @@ -3140,7 +3158,6 @@ static void cpuset_attach(struct cgroup_taskset *tset) struct cgroup_subsys_state *css; struct cpuset *cs; struct cpuset *oldcs = cpuset_attach_old_cs; - bool cpus_updated, mems_updated; bool queue_task_work = false; cgroup_taskset_first(tset, &css); @@ -3148,9 +3165,6 @@ static void cpuset_attach(struct cgroup_taskset *tset) lockdep_assert_cpus_held(); /* see cgroup_attach_lock() */ mutex_lock(&cpuset_mutex); - cpus_updated = !cpumask_equal(cs->effective_cpus, - oldcs->effective_cpus); - mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems); /* * In the default hierarchy, enabling cpuset in the child cgroups @@ -3158,7 +3172,7 @@ static void cpuset_attach(struct cgroup_taskset *tset) * in effective cpus and mems. In that case, we can optimize out * by skipping the task iteration and update. */ - if (cpuset_v2() && !cpus_updated && !mems_updated) { + if (cpuset_v2() && !attach_cpus_updated && !attach_mems_updated) { cpuset_attach_nodemask_to = cs->effective_mems; goto out; } @@ -3175,7 +3189,7 @@ static void cpuset_attach(struct cgroup_taskset *tset) * not set. */ cpuset_attach_nodemask_to = cs->effective_mems; - if (!is_memory_migrate(cs) && !mems_updated) + if (!is_memory_migrate(cs) && !attach_mems_updated) goto out; cgroup_taskset_for_each_leader(leader, css, tset) { @@ -3590,7 +3604,7 @@ 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