From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: [PATCH v2 3/4] cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated Date: Fri, 17 Mar 2023 11:15:07 -0400 Message-ID: <20230317151508.1225282-4-longman@redhat.com> References: <20230317151508.1225282-1-longman@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1679066135; 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=xGXOF5DEcP6pwvx1eYY/0gGWQNDYbTOSJx5veuAvjus=; b=c1RRVw1pITr3l1jTRSK/jsvuWpTOtgk78Ei7Ggt0lzo9rvbZ+bHGoU94KcG+l8hIjP1/9M VyHwL6idgAvk4rKkvq/ZZPmeEhOHe6VJYFPWc/rnvQG9tqJTfEv/0DtaRqW65MMWMEaB1n y7h+xx8UOmsY02tg8Fctl17S25apBM0= In-Reply-To: <20230317151508.1225282-1-longman@redhat.com> List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo , Zefan Li , Johannes Weiner , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Will Deacon , Peter Zijlstra , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Juri Lelli , Waiman Long Similar to commit 3fb906e7fabb ("group/cpuset: Don't filter offline CPUs in cpuset_cpus_allowed() for top cpuset tasks"), the whole set of possible CPUs including offline ones should be used for setting cpumasks for tasks in the top cpuset when a cpuset partition is modified as the hotplug code won't update cpumasks for tasks in the top cpuset when CPUs become online or offline. Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 5b8d763555b0..db8793a2082f 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1209,7 +1209,9 @@ void rebuild_sched_domains(void) * * Iterate through each task of @cs updating its cpus_allowed to the * effective cpuset's. As this function is called with cpuset_rwsem held, - * cpuset membership stays stable. + * cpuset membership stays stable. For top_cpuset, task_cpu_possible_mask() + * is used instead of effective_cpus to make sure all offline CPUs are also + * included as hotplug code won't update cpumasks for tasks in top_cpuset. */ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus) { @@ -1219,15 +1221,18 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus) css_task_iter_start(&cs->css, 0, &it); while ((task = css_task_iter_next(&it))) { - /* - * Percpu kthreads in top_cpuset are ignored - */ - if (top_cs && (task->flags & PF_KTHREAD) && - kthread_is_per_cpu(task)) - continue; + const struct cpumask *possible_mask = task_cpu_possible_mask(task); - cpumask_and(new_cpus, cs->effective_cpus, - task_cpu_possible_mask(task)); + if (top_cs) { + /* + * Percpu kthreads in top_cpuset are ignored + */ + if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task)) + continue; + cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus); + } else { + cpumask_and(new_cpus, possible_mask, cs->effective_cpus); + } set_cpus_allowed_ptr(task, new_cpus); } css_task_iter_end(&it); -- 2.31.1