From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F35CEC432BE for ; Wed, 25 Aug 2021 21:40:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB7DD6112D for ; Wed, 25 Aug 2021 21:40:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233463AbhHYVlH (ORCPT ); Wed, 25 Aug 2021 17:41:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39445 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233651AbhHYVlG (ORCPT ); Wed, 25 Aug 2021 17:41:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629927619; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=r5oKiyiuhTrPLojQ5m5cdMpX7cAe0uq7IPb0/BukX9s=; b=Wj36EjhQ/7wrDBnXaoEq+0k8WwN2eokjG8lIKLSb90PCoML+T0mOc/3cqwdXByZigon9rq NJt18R9pD7DAMCTJ/F40XcNBYpfQe7TDQ6TRGdkVF2qfKC1+qEuA6s8nhPWL7mxKAwOwPc IGR+Ozq7fuTbPVDPxDGAxQEaUGVX9XU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-179-T8eKzJBzP0OISW3tCs6ztw-1; Wed, 25 Aug 2021 17:40:16 -0400 X-MC-Unique: T8eKzJBzP0OISW3tCs6ztw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 91FC91934104; Wed, 25 Aug 2021 21:40:14 +0000 (UTC) Received: from llong.com (unknown [10.22.18.37]) by smtp.corp.redhat.com (Postfix) with ESMTP id B78EA1B472; Wed, 25 Aug 2021 21:40:07 +0000 (UTC) From: Waiman Long To: Tejun Heo , Zefan Li , Johannes Weiner , Jonathan Corbet , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Roman Gushchin , Phil Auld , Peter Zijlstra , Juri Lelli , Frederic Weisbecker , Marcelo Tosatti , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Waiman Long Subject: [PATCH v7 2/6] cgroup/cpuset: Show invalid partition reason string Date: Wed, 25 Aug 2021 17:37:46 -0400 Message-Id: <20210825213750.6933-3-longman@redhat.com> In-Reply-To: <20210825213750.6933-1-longman@redhat.com> References: <20210825213750.6933-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are a number of different reasons which can cause a partition to become invalid. A user seeing an invalid partition may not know exactly why. To help user to get a better understanding of the underlying reason, The cpuset.cpus.partition control file, when read, will now report the reason why a partition become invalid. When a partition does become invalid, reading the control file will show "root invalid ()" where is a string that describes why the partition is invalid. Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 46 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 43 insertions(+), 3 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index ddea05e4d1f0..eb2e81f9326b 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -78,6 +78,24 @@ struct fmeter { spinlock_t lock; /* guards read or write of above */ }; +/* + * Invalid partition error code + */ +enum prs_errcode { + PERR_NONE = 0, + PERR_INVCPUS, + PERR_NOCPUS, + PERR_PARENT, + PERR_HOTPLUG, +}; + +static const char * const perr_strings[] = { + [PERR_INVCPUS] = "Invalid change to cpuset.cpus", + [PERR_PARENT] = "Parent is no longer a partition root", + [PERR_NOCPUS] = "Parent unable to distribute cpu downstream", + [PERR_HOTPLUG] = "No cpu available due to hotplug", +}; + struct cpuset { struct cgroup_subsys_state css; @@ -163,6 +181,9 @@ struct cpuset { /* Handle for cpuset.cpus.partition */ struct cgroup_file partition_file; + + /* Invalid partition error code, not lock protected */ + enum prs_errcode prs_err; }; /* @@ -272,8 +293,13 @@ static inline int is_partition_root(const struct cpuset *cs) static inline void notify_partition_change(struct cpuset *cs, int old_prs, int new_prs) { - if (old_prs != new_prs) - cgroup_file_notify(&cs->partition_file); + if (old_prs == new_prs) + return; + cgroup_file_notify(&cs->partition_file); + + /* Reset prs_err if not invalid */ + if (new_prs != PRS_ERROR) + WRITE_ONCE(cs->prs_err, PERR_NONE); } static struct cpuset top_cpuset = { @@ -1243,6 +1269,8 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, cpu_active_mask)) part_error = true; cpumask_copy(tmp->addmask, parent->effective_cpus); + if ((READ_ONCE(cpuset->prs_err) == PERR_NONE) && part_error) + WRITE_ONCE(cpuset->prs_err, PERR_INVCPUS); } } else { /* @@ -1264,6 +1292,8 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, part_error = (is_partition_root(cpuset) && !parent->nr_subparts_cpus) || cpumask_equal(tmp->addmask, parent->effective_cpus); + if (is_partition_root(cpuset) && part_error) + WRITE_ONCE(cpuset->prs_err, PERR_NOCPUS); } if (cmd == partcmd_update) { @@ -1427,6 +1457,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) * When parent is invalid, it has to be too. */ new_prs = PRS_ERROR; + WRITE_ONCE(cp->prs_err, PERR_PARENT); break; } } @@ -2546,6 +2577,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) static int sched_partition_show(struct seq_file *seq, void *v) { struct cpuset *cs = css_cs(seq_css(seq)); + const char *err; switch (cs->partition_root_state) { case PRS_ENABLED: @@ -2555,7 +2587,11 @@ static int sched_partition_show(struct seq_file *seq, void *v) seq_puts(seq, "member\n"); break; case PRS_ERROR: - seq_puts(seq, "root invalid\n"); + err = perr_strings[READ_ONCE(cs->prs_err)]; + if (err) + seq_printf(seq, "root invalid (%s)\n", err); + else + seq_puts(seq, "root invalid\n"); break; } return 0; @@ -3155,6 +3191,10 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) spin_lock_irq(&callback_lock); cs->partition_root_state = PRS_ERROR; spin_unlock_irq(&callback_lock); + if (parent->partition_root_state == PRS_ERROR) + WRITE_ONCE(cs->prs_err, PERR_PARENT); + else + WRITE_ONCE(cs->prs_err, PERR_HOTPLUG); notify_partition_change(cs, old_prs, PRS_ERROR); } cpuset_force_rebuild(); -- 2.18.1