From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 970F572631; Tue, 25 Nov 2025 00:50:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764031818; cv=none; b=FJQqR53oEC8EYwyDqD0APEyolGDdmcBZIDMvQoleuGyhMb4T7Qez4r8SBcD1Pnuxv+OwV+K0nSiLL6m2xsS2RM3eu9bBz9VUW7chPfCCh1rNXvOpiEl6g5FVZCWTDh+Td+ooz/0z85Kcpp3zqZjbnqiUq4wWXpDetQfrvBwsWiY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764031818; c=relaxed/simple; bh=Gljfu2M+nxI7lRXNC09U1YtjnkntKqF8eZ1HhHNAZWQ=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=Qb6Nm0qkb+++ODLl6A4u5ofA+/tmjdBtRs/aw9Ri6nV8wFN3anpeSrB3VRU0OZNgre5rFhMZRBy1tKRlz4DDW0iJ6pa8oHNA/WOJj21Hqyth50qQCnHXXwIZtZ0SAz5sEvazsMXkLI9f5MAPNIIs50AMswm8FfnsuZMB+B8wP0g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4dFkbl2PftzYQtLr; Tue, 25 Nov 2025 08:49:23 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id B41CA1A018D; Tue, 25 Nov 2025 08:50:12 +0800 (CST) Received: from [10.67.111.176] (unknown [10.67.111.176]) by APP4 (Coremail) with SMTP id gCh0CgA3YV5E_SRpLryqBw--.29731S2; Tue, 25 Nov 2025 08:50:12 +0800 (CST) Message-ID: Date: Tue, 25 Nov 2025 08:50:12 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH -next] cpuset: Remove unnecessary checks in rebuild_sched_domains_locked From: Chen Ridong To: longman@redhat.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, daniel.m.jordan@oracle.com, lujialin4@huawei.com, chenridong@huawei.com References: <20251118083643.1363020-1-chenridong@huaweicloud.com> Content-Language: en-US In-Reply-To: <20251118083643.1363020-1-chenridong@huaweicloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CM-TRANSID:gCh0CgA3YV5E_SRpLryqBw--.29731S2 X-Coremail-Antispam: 1UD129KBjvJXoWxXrWUtw4kWr4rZrW5WF4Uurg_yoW5XFWkpF Z5Gay7Z3y5Kr1UC39xta9rZryF9a1DJanrt3ZxWr18AFy7A3Wvkryjk3W3XryUur9xCw1U AFn09wsxWFnFyFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUyGb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxkF7I0En4kS14v26r1q6r43MxAIw28IcxkI7VAK I48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7 xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xII jxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw2 0EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x02 67AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IUbmii3UUUUU== X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ On 2025/11/18 16:36, Chen Ridong wrote: > From: Chen Ridong > > Commit 406100f3da08 ("cpuset: fix race between hotplug work and later CPU > offline")added a check for empty effective_cpus in partitions for cgroup > v2. However, thischeck did not account for remote partitions, which were > introduced later. > > After commit 2125c0034c5d ("cgroup/cpuset: Make cpuset hotplug processing > synchronous"),cgroup v2's cpuset hotplug handling is now synchronous. This > eliminates the race condition with subsequent CPU offline operations that > the original check aimed to fix. > > Instead of extending the check to support remote partitions, this patch > removes the redundant partition effective_cpus check. Additionally, it adds > a check and warningto verify that all generated sched domains consist of > active CPUs, preventing partition_sched_domains from being invoked with > offline CPUs. > > Signed-off-by: Chen Ridong > --- > kernel/cgroup/cpuset.c | 29 ++++++----------------------- > 1 file changed, 6 insertions(+), 23 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index daf813386260..1ac58e3f26b4 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -1084,11 +1084,10 @@ void dl_rebuild_rd_accounting(void) > */ > void rebuild_sched_domains_locked(void) > { > - struct cgroup_subsys_state *pos_css; > struct sched_domain_attr *attr; > cpumask_var_t *doms; > - struct cpuset *cs; > int ndoms; > + int i; > > lockdep_assert_cpus_held(); > lockdep_assert_held(&cpuset_mutex); > @@ -1107,30 +1106,14 @@ void rebuild_sched_domains_locked(void) > !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) > return; > > - /* > - * With subpartition CPUs, however, the effective CPUs of a partition > - * root should be only a subset of the active CPUs. Since a CPU in any > - * partition root could be offlined, all must be checked. > - */ > - if (!cpumask_empty(subpartitions_cpus)) { > - rcu_read_lock(); > - cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) { > - if (!is_partition_valid(cs)) { > - pos_css = css_rightmost_descendant(pos_css); > - continue; > - } > - if (!cpumask_subset(cs->effective_cpus, > - cpu_active_mask)) { > - rcu_read_unlock(); > - return; > - } > - } > - rcu_read_unlock(); > - } > - > /* Generate domain masks and attrs */ > ndoms = generate_sched_domains(&doms, &attr); > > + for (i = 0; i < ndoms; ++i) { > + if (WARN_ON_ONCE(!cpumask_subset(doms[i], cpu_active_mask))) > + return; > + } > + > /* Have scheduler rebuild the domains */ > partition_sched_domains(ndoms, doms, attr); > } Friendly ping. -- Best regards, Ridong