From nobody Fri Dec 19 12:31:29 2025 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 D05E0270ED2 for ; Wed, 5 Nov 2025 04:39:23 +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=1762317565; cv=none; b=S1E0Rm0tOzD3K6JpnLbuFZiAMgKJnWiJdXBN0akVOhLVG66b0bgTAVYwG/psiPbOz0BbAME4fjxbWNjoO8zl+ZOYlE3nFFvbeP+lR8RxS7zpr1QfdNdMi1BIePdx5hgXTegCAplueMBTXMIkaynplqyvRTMzUx0oyKzP0wowgas= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762317565; c=relaxed/simple; bh=PRMJcyYJl61mZBeSGGgiHzEd0shtT9jlqiAi1ex1Arw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZDuNz8kE/O7uILabthSuF2utGRr7iJ5M/+Qi3FXnPQMygZr/bf3Vir1GuKttAw+TkyAd9CnIqWLbR9xHJRcnTMsoM/K+Ri2rb284//3xn12o9czZWGCVCnISS1V1eAUGujP7wDUy8jrHuYwqlPYbBCyiOcANgavVagTecvsIwRQ= 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=Ljf5b1Cg; 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="Ljf5b1Cg" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1762317563; 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=wQG5O0jywdiZSfV+8D+TD6Dmb/AbN0MrtQRlMhnkX3c=; b=Ljf5b1CgNc9nFnlNzj3nyi2MHwaQsL/Ik0IkoEnyk8rOUxkIuoPMP/PpTOo1n5b6U8Q72Y LSEE4SiR4MVNvZUMd8KIuEB2puICuHzUHB16/KiIanScMfHGERTnZunrC5S0LX/xFnXgue PMA8OoOLcWHngEcWr7SGLE4C6EyMsF4= Received: from mx-prod-mc-06.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-517--pHnmFIJO1CImlX9mI_A5w-1; Tue, 04 Nov 2025 23:39:19 -0500 X-MC-Unique: -pHnmFIJO1CImlX9mI_A5w-1 X-Mimecast-MFC-AGG-ID: -pHnmFIJO1CImlX9mI_A5w_1762317558 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DAB1118011EF; Wed, 5 Nov 2025 04:39:17 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.89.34]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 33E18195608E; Wed, 5 Nov 2025 04:39:16 +0000 (UTC) From: Waiman Long To: Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Ridong , Gabriele Monaco , Frederic Weisbecker , Waiman Long Subject: [cgroup/for-6.19 PATCH v3 5/5] cgroup/cpuset: Globally track isolated_cpus update Date: Tue, 4 Nov 2025 23:38:48 -0500 Message-ID: <20251105043848.382703-6-longman@redhat.com> In-Reply-To: <20251105043848.382703-1-longman@redhat.com> References: <20251105043848.382703-1-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: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Content-Type: text/plain; charset="utf-8" The current cpuset code passes a local isolcpus_updated flag around in a number of functions to determine if external isolation related cpumasks like wq_unbound_cpumask should be updated. It is a bit cumbersome and makes the code more complex. Simplify the code by using a global boolean flag "isolated_cpus_updating" to track this. This flag will be set in isolated_cpus_update() and cleared in update_isolation_cpumasks(). No functional change is expected. Signed-off-by: Waiman Long Reviewed-by: Chen Ridong --- kernel/cgroup/cpuset.c | 73 ++++++++++++++++++++---------------------- 1 file changed, 35 insertions(+), 38 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 2daf58bf0bbb..90288efe5367 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -81,6 +81,13 @@ static cpumask_var_t subpartitions_cpus; */ static cpumask_var_t isolated_cpus; =20 +/* + * isolated_cpus updating flag (protected by cpuset_mutex) + * Set if isolated_cpus is going to be updated in the current + * cpuset_mutex crtical section. + */ +static bool isolated_cpus_updating; + /* * Housekeeping (HK_TYPE_DOMAIN) CPUs at boot */ @@ -1327,6 +1334,8 @@ static void isolated_cpus_update(int old_prs, int new= _prs, struct cpumask *xcpus cpumask_or(isolated_cpus, isolated_cpus, xcpus); else cpumask_andnot(isolated_cpus, isolated_cpus, xcpus); + + isolated_cpus_updating =3D true; } =20 /* @@ -1334,15 +1343,12 @@ static void isolated_cpus_update(int old_prs, int n= ew_prs, struct cpumask *xcpus * @new_prs: new partition_root_state * @parent: parent cpuset * @xcpus: exclusive CPUs to be added - * Return: true if isolated_cpus modified, false otherwise * * Remote partition if parent =3D=3D NULL */ -static bool partition_xcpus_add(int new_prs, struct cpuset *parent, +static void partition_xcpus_add(int new_prs, struct cpuset *parent, struct cpumask *xcpus) { - bool isolcpus_updated; - WARN_ON_ONCE(new_prs < 0); lockdep_assert_held(&callback_lock); if (!parent) @@ -1352,13 +1358,11 @@ static bool partition_xcpus_add(int new_prs, struct= cpuset *parent, if (parent =3D=3D &top_cpuset) cpumask_or(subpartitions_cpus, subpartitions_cpus, xcpus); =20 - isolcpus_updated =3D (new_prs !=3D parent->partition_root_state); - if (isolcpus_updated) + if (new_prs !=3D parent->partition_root_state) isolated_cpus_update(parent->partition_root_state, new_prs, xcpus); =20 cpumask_andnot(parent->effective_cpus, parent->effective_cpus, xcpus); - return isolcpus_updated; } =20 /* @@ -1366,15 +1370,12 @@ static bool partition_xcpus_add(int new_prs, struct= cpuset *parent, * @old_prs: old partition_root_state * @parent: parent cpuset * @xcpus: exclusive CPUs to be removed - * Return: true if isolated_cpus modified, false otherwise * * Remote partition if parent =3D=3D NULL */ -static bool partition_xcpus_del(int old_prs, struct cpuset *parent, +static void partition_xcpus_del(int old_prs, struct cpuset *parent, struct cpumask *xcpus) { - bool isolcpus_updated; - WARN_ON_ONCE(old_prs < 0); lockdep_assert_held(&callback_lock); if (!parent) @@ -1383,14 +1384,12 @@ static bool partition_xcpus_del(int old_prs, struct= cpuset *parent, if (parent =3D=3D &top_cpuset) cpumask_andnot(subpartitions_cpus, subpartitions_cpus, xcpus); =20 - isolcpus_updated =3D (old_prs !=3D parent->partition_root_state); - if (isolcpus_updated) + if (old_prs !=3D parent->partition_root_state) isolated_cpus_update(old_prs, parent->partition_root_state, xcpus); =20 cpumask_and(xcpus, xcpus, cpu_active_mask); cpumask_or(parent->effective_cpus, parent->effective_cpus, xcpus); - return isolcpus_updated; } =20 /* @@ -1452,17 +1451,24 @@ static bool prstate_housekeeping_conflict(int prsta= te, struct cpumask *new_cpus) return false; } =20 -static void update_isolation_cpumasks(bool isolcpus_updated) +/* + * update_isolation_cpumasks - Update external isolation related CPU masks + * + * The following external CPU masks will be updated if necessary: + * - workqueue unbound cpumask + */ +static void update_isolation_cpumasks(void) { int ret; =20 - lockdep_assert_cpus_held(); - - if (!isolcpus_updated) + if (!isolated_cpus_updating) return; =20 + lockdep_assert_cpus_held(); + ret =3D workqueue_unbound_exclude_cpumask(isolated_cpus); WARN_ON_ONCE(ret < 0); + isolated_cpus_updating =3D false; } =20 /** @@ -1587,8 +1593,6 @@ static inline bool is_local_partition(struct cpuset *= cs) static int remote_partition_enable(struct cpuset *cs, int new_prs, struct tmpmasks *tmp) { - bool isolcpus_updated; - /* * The user must have sysadmin privilege. */ @@ -1616,11 +1620,11 @@ static int remote_partition_enable(struct cpuset *c= s, int new_prs, return PERR_HKEEPING; =20 spin_lock_irq(&callback_lock); - isolcpus_updated =3D partition_xcpus_add(new_prs, NULL, tmp->new_cpus); + partition_xcpus_add(new_prs, NULL, tmp->new_cpus); list_add(&cs->remote_sibling, &remote_children); cpumask_copy(cs->effective_xcpus, tmp->new_cpus); spin_unlock_irq(&callback_lock); - update_isolation_cpumasks(isolcpus_updated); + update_isolation_cpumasks(); cpuset_force_rebuild(); cs->prs_err =3D 0; =20 @@ -1643,15 +1647,12 @@ static int remote_partition_enable(struct cpuset *c= s, int new_prs, */ static void remote_partition_disable(struct cpuset *cs, struct tmpmasks *t= mp) { - bool isolcpus_updated; - WARN_ON_ONCE(!is_remote_partition(cs)); WARN_ON_ONCE(!cpumask_subset(cs->effective_xcpus, subpartitions_cpus)); =20 spin_lock_irq(&callback_lock); list_del_init(&cs->remote_sibling); - isolcpus_updated =3D partition_xcpus_del(cs->partition_root_state, - NULL, cs->effective_xcpus); + partition_xcpus_del(cs->partition_root_state, NULL, cs->effective_xcpus); if (cs->prs_err) cs->partition_root_state =3D -cs->partition_root_state; else @@ -1661,7 +1662,7 @@ static void remote_partition_disable(struct cpuset *c= s, struct tmpmasks *tmp) compute_excpus(cs, cs->effective_xcpus); reset_partition_data(cs); spin_unlock_irq(&callback_lock); - update_isolation_cpumasks(isolcpus_updated); + update_isolation_cpumasks(); cpuset_force_rebuild(); =20 /* @@ -1686,7 +1687,6 @@ static void remote_cpus_update(struct cpuset *cs, str= uct cpumask *xcpus, { bool adding, deleting; int prs =3D cs->partition_root_state; - int isolcpus_updated =3D 0; =20 if (WARN_ON_ONCE(!is_remote_partition(cs))) return; @@ -1722,9 +1722,9 @@ static void remote_cpus_update(struct cpuset *cs, str= uct cpumask *xcpus, =20 spin_lock_irq(&callback_lock); if (adding) - isolcpus_updated +=3D partition_xcpus_add(prs, NULL, tmp->addmask); + partition_xcpus_add(prs, NULL, tmp->addmask); if (deleting) - isolcpus_updated +=3D partition_xcpus_del(prs, NULL, tmp->delmask); + partition_xcpus_del(prs, NULL, tmp->delmask); /* * Need to update effective_xcpus and exclusive_cpus now as * update_sibling_cpumasks() below may iterate back to the same cs. @@ -1733,7 +1733,7 @@ static void remote_cpus_update(struct cpuset *cs, str= uct cpumask *xcpus, if (xcpus) cpumask_copy(cs->exclusive_cpus, xcpus); spin_unlock_irq(&callback_lock); - update_isolation_cpumasks(isolcpus_updated); + update_isolation_cpumasks(); if (adding || deleting) cpuset_force_rebuild(); =20 @@ -1794,7 +1794,6 @@ static int update_parent_effective_cpumask(struct cpu= set *cs, int cmd, int deleting; /* Deleting cpus from parent's effective_cpus */ int old_prs, new_prs; int part_error =3D PERR_NONE; /* Partition error? */ - int isolcpus_updated =3D 0; struct cpumask *xcpus =3D user_xcpus(cs); int parent_prs =3D parent->partition_root_state; bool nocpu; @@ -2073,14 +2072,12 @@ static int update_parent_effective_cpumask(struct c= puset *cs, int cmd, * and vice versa. */ if (adding) - isolcpus_updated +=3D partition_xcpus_del(old_prs, parent, - tmp->addmask); + partition_xcpus_del(old_prs, parent, tmp->addmask); if (deleting) - isolcpus_updated +=3D partition_xcpus_add(new_prs, parent, - tmp->delmask); + partition_xcpus_add(new_prs, parent, tmp->delmask); =20 spin_unlock_irq(&callback_lock); - update_isolation_cpumasks(isolcpus_updated); + update_isolation_cpumasks(); =20 if ((old_prs !=3D new_prs) && (cmd =3D=3D partcmd_update)) update_partition_exclusive_flag(cs, new_prs); @@ -3103,7 +3100,7 @@ static int update_prstate(struct cpuset *cs, int new_= prs) else if (isolcpus_updated) isolated_cpus_update(old_prs, new_prs, cs->effective_xcpus); spin_unlock_irq(&callback_lock); - update_isolation_cpumasks(isolcpus_updated); + update_isolation_cpumasks(); =20 /* Force update if switching back to member & update effective_xcpus */ update_cpumasks_hier(cs, &tmpmask, !new_prs); --=20 2.51.1