From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 B39301F4176 for ; Wed, 4 Mar 2026 18:41:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772649681; cv=none; b=UWgQPGGA8OQzP3TETFr5oP+kAFhJ+iDER0/IirvHvwt3bE21q0lH1mRLKUt0Pv2A+6Nc2tFL/WouVYUvc0UZl8KC/gYmGfM7NRcNVLcEQGlmrrVPH7rih5ajCOURMIdAUY+3fc5pMlrYQNCPE4rgFsDXNUnVB4k/I9akGU4ljCE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772649681; c=relaxed/simple; bh=zScxt0snREk9NzbM8RdCSaRcdNNh0NoxJ16ZvJ5ARIM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=gHnkrtjyvyqBhV9f19KCyU9QBvOxgMKfns56cFsXBsPxIHiu4weDiT7yYRYDSN+A946GjJUOzQb8VhltH4qf7StYbJVmE1j/gpzLH6Ja6Q/uOXYg4M6bZgt4Ussau1ANYOOTXx1uIc8VeSlSWSzl9TnDMEjOznUOyMiGEeXX3qA= 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=LSxSckXb; arc=none smtp.client-ip=170.10.133.124 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="LSxSckXb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772649678; 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; bh=LiB+0HDLX0vNzFw1JbcWNWlCrJQlrTlgk1zqLduPGAw=; b=LSxSckXb4jo4cUH198nB+c3ANiNt6xs0lXiZtrIuiYXLeOjb4VY+mzM7lyufxn5GdZyuDn Ra4OA+Q8QMm3QmI1H2ASSftSJqh++hv2d0DihuMwz86XGz3h/o8UaQphk+TPQt7vx4xYMf VZCGEbAJbGZRGg3aBKqloh5BUDREWxQ= Received: from mx-prod-mc-05.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-658-IrRKhMNqN_qc2qNbEbjWlA-1; Wed, 04 Mar 2026 13:41:17 -0500 X-MC-Unique: IrRKhMNqN_qc2qNbEbjWlA-1 X-Mimecast-MFC-AGG-ID: IrRKhMNqN_qc2qNbEbjWlA_1772649675 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 67E1C1956096; Wed, 4 Mar 2026 18:41:15 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.89.197]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9190C180049D; Wed, 4 Mar 2026 18:41:13 +0000 (UTC) From: Waiman Long To: Chen Ridong , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Frederic Weisbecker Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Jon Hunter , Waiman Long Subject: [PATCH] cgroup/cpuset: Call rebuild_sched_domains() directly in hotplug Date: Wed, 4 Mar 2026 13:41:00 -0500 Message-ID: <20260304184100.71015-1-longman@redhat.com> Precedence: bulk X-Mailing-List: cgroups@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 10.30.177.93 Besides deferring the call to housekeeping_update(), commit 6df415aa46ec ("cgroup/cpuset: Defer housekeeping_update() calls from CPU hotplug to workqueue") also defers the rebuild_sched_domains() call to the workqueue. So a new offline CPU may still be in a sched domain or new online CPU not showing up in the sched domains for a short transition period. That could be a problem in some corner cases and can be the cause of a reported test failure[1]. Fix it by calling rebuild_sched_domains_cpuslocked() directly in hotplug as before. If isolated partition invalidation or recreation is being done, the housekeeping_update() call to update the housekeeping cpumasks will still be deferred to a workqueue. In commit 3bfe47967191 ("cgroup/cpuset: Move housekeeping_update()/rebuild_sched_domains() together"), housekeeping_update() is called before rebuild_sched_domains() because it needs to access the HK_TYPE_DOMAIN housekeeping cpumask. That is now changed to use the static HK_TYPE_DOMAIN_BOOT cpumask as HK_TYPE_DOMAIN cpumask is now changeable at run time. As a result, we can move the rebuild_sched_domains() call before housekeeping_update() with the slight advantage that it will be done in the same cpus_read_lock critical section without the possibility of interference by a concurrent cpu hot add/remove operation. As it doesn't make sense to acquire cpuset_mutex/cpuset_top_mutex after calling housekeeping_update() and immediately release them again, move the cpuset_full_unlock() operation inside update_hk_sched_domains() and rename it to cpuset_update_sd_hk_unlock() to signify that it will release the full set of locks. Fixes: 6df415aa46ec ("cgroup/cpuset: Defer housekeeping_update() calls from CPU hotplug to workqueue") Tested-by: Jon Hunter Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 59 ++++++++++++++++++++++-------------------- 1 file changed, 31 insertions(+), 28 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 271bb99b1b9d..f7657b325490 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -881,7 +881,7 @@ static int generate_sched_domains(cpumask_var_t **domains, /* * Cgroup v2 doesn't support domain attributes, just set all of them * to SD_ATTR_INIT. Also non-isolating partition root CPUs are a - * subset of HK_TYPE_DOMAIN housekeeping CPUs. + * subset of HK_TYPE_DOMAIN_BOOT housekeeping CPUs. */ for (i = 0; i < ndoms; i++) { /* @@ -890,7 +890,7 @@ static int generate_sched_domains(cpumask_var_t **domains, */ if (!csa || csa[i] == &top_cpuset) cpumask_and(doms[i], top_cpuset.effective_cpus, - housekeeping_cpumask(HK_TYPE_DOMAIN)); + housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT)); else cpumask_copy(doms[i], csa[i]->effective_cpus); if (dattr) @@ -1331,17 +1331,22 @@ static bool prstate_housekeeping_conflict(int prstate, struct cpumask *new_cpus) } /* - * update_hk_sched_domains - Update HK cpumasks & rebuild sched domains + * cpuset_update_sd_hk_unlock - Rebuild sched domains, update HK & unlock * - * Update housekeeping cpumasks and rebuild sched domains if necessary. - * This should be called at the end of cpuset or hotplug actions. + * Update housekeeping cpumasks and rebuild sched domains if necessary and + * then do a cpuset_full_unlock(). + * This should be called at the end of cpuset operation. */ -static void update_hk_sched_domains(void) +static void cpuset_update_sd_hk_unlock(void) + __releases(&cpuset_mutex) + __releases(&cpuset_top_mutex) { + /* force_sd_rebuild will be cleared in rebuild_sched_domains_locked() */ + if (force_sd_rebuild) + rebuild_sched_domains_locked(); + if (update_housekeeping) { - /* Updating HK cpumasks implies rebuild sched domains */ update_housekeeping = false; - force_sd_rebuild = true; cpumask_copy(isolated_hk_cpus, isolated_cpus); /* @@ -1352,22 +1357,19 @@ static void update_hk_sched_domains(void) mutex_unlock(&cpuset_mutex); cpus_read_unlock(); WARN_ON_ONCE(housekeeping_update(isolated_hk_cpus)); - cpus_read_lock(); - mutex_lock(&cpuset_mutex); + mutex_unlock(&cpuset_top_mutex); + } else { + cpuset_full_unlock(); } - /* force_sd_rebuild will be cleared in rebuild_sched_domains_locked() */ - if (force_sd_rebuild) - rebuild_sched_domains_locked(); } /* - * Work function to invoke update_hk_sched_domains() + * Work function to invoke cpuset_update_sd_hk_unlock() */ static void hk_sd_workfn(struct work_struct *work) { cpuset_full_lock(); - update_hk_sched_domains(); - cpuset_full_unlock(); + cpuset_update_sd_hk_unlock(); } /** @@ -3232,8 +3234,7 @@ ssize_t cpuset_write_resmask(struct kernfs_open_file *of, free_cpuset(trialcs); out_unlock: - update_hk_sched_domains(); - cpuset_full_unlock(); + cpuset_update_sd_hk_unlock(); if (of_cft(of)->private == FILE_MEMLIST) schedule_flush_migrate_mm(); return retval ?: nbytes; @@ -3340,8 +3341,7 @@ static ssize_t cpuset_partition_write(struct kernfs_open_file *of, char *buf, cpuset_full_lock(); if (is_cpuset_online(cs)) retval = update_prstate(cs, val); - update_hk_sched_domains(); - cpuset_full_unlock(); + cpuset_update_sd_hk_unlock(); return retval ?: nbytes; } @@ -3515,8 +3515,7 @@ static void cpuset_css_killed(struct cgroup_subsys_state *css) /* Reset valid partition back to member */ if (is_partition_valid(cs)) update_prstate(cs, PRS_MEMBER); - update_hk_sched_domains(); - cpuset_full_unlock(); + cpuset_update_sd_hk_unlock(); } static void cpuset_css_free(struct cgroup_subsys_state *css) @@ -3925,11 +3924,13 @@ static void cpuset_handle_hotplug(void) rcu_read_unlock(); } - /* - * Queue a work to call housekeeping_update() & rebuild_sched_domains() - * There will be a slight delay before the HK_TYPE_DOMAIN housekeeping - * cpumask can correctly reflect what is in isolated_cpus. + * rebuild_sched_domains() will always be called directly if needed + * to make sure that newly added or removed CPU will be reflected in + * the sched domains. However, if isolated partition invalidation + * or recreation is being done (update_housekeeping set), a work item + * will be queued to call housekeeping_update() to update the + * corresponding housekeeping cpumasks after some slight delay. * * We rely on WORK_STRUCT_PENDING_BIT to not requeue a work item that * is still pending. Before the pending bit is cleared, the work data @@ -3938,8 +3939,10 @@ static void cpuset_handle_hotplug(void) * previously queued work. Since hk_sd_workfn() doesn't use the work * item at all, this is not a problem. */ - if (update_housekeeping || force_sd_rebuild) - queue_work(system_unbound_wq, &hk_sd_work); + if (force_sd_rebuild) + rebuild_sched_domains_cpuslocked(); + if (update_housekeeping) + queue_work(system_dfl_wq, &hk_sd_work); free_tmpmasks(ptmp); } -- 2.53.0