From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 60AD8391E52 for ; Sat, 10 Oct 2026 22:20:20 +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=1791670821; cv=none; b=gEpEklEra5qYl99yX0YLJVeY9Qs5j2smQ9yeSiOro8ksrMM3xh/gtnq36epkkQiVCHGLlk2ui7lwMuQhmnDnKjr9eDbuLbI1N97YKKpTsbSozinRExOygeF+gPF2MKcTmasTOs5UH0TGp8RkPRxxT2cI8PEb3Nr+kCHz8snWejU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791670821; c=relaxed/simple; bh=sEJSSYm1pDBnnokCg8ILR9hMgvVje2eTkQp2q/G4hLc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=L4TAim2KyN9s0/fc2vIk2JaHUL8UZdqqm5jxEmW5b7UJD1Slm5g9L2MfGDCC8rqE2VKZdzQWmwJBwkz4PRuN9Zdou0Agb1iy96WLp/2V5Fzq8DFkph3xQTKudrN3JiRhJ/bfQhEXnhywWU6rVtHmJjMznGRuCNabTSWUosWpb3Y= 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=Cogsk8li; 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="Cogsk8li" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1791670819; 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=PomvpSh0nZEAh/f/qBOy12NCtYdVqGfFVKpPbxTp5eU=; b=Cogsk8li3gJHiUMv/WkaeGzbheYaDik6EzdHFTD7WguLJnrXlrqaLZddjW5hJIpk2UvslG g5q0c1i6H5WctSqbqa0VUotfGUNPtNwh/YA3NN8k+hvC5xbWMHFKngvJpP9tzWQXWx4D7N MGEegn/dBXC9H4jGXwGX7kxytPYDBgc= 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-207-h3wbTMjTPHGFYCntpH6ibg-1; Sat, 10 Oct 2026 22:20:14 +0000 X-MC-Unique: h3wbTMjTPHGFYCntpH6ibg-1 X-Mimecast-MFC-AGG-ID: h3wbTMjTPHGFYCntpH6ibg_1791670812 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 85DB518007EB; Sat, 10 Oct 2026 22:20:12 +0000 (UTC) Received: from llong-thinkpadp16vgen1.redhat.corp (headnet03.pony-001.prod.iad2.dc.redhat.com [10.2.32.114]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 8C6151800473; Sat, 10 Oct 2026 22:20:09 +0000 (UTC) From: Waiman Long To: Ridong Chen , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Hui Peng , Guopeng Zhang , Waiman Long Subject: [PATCH-next v2 4/6] cgroup/cpuset: Properly disabling partition when partition state switching fails Date: Sat, 10 Oct 2026 18:19:36 -0400 Message-ID: <20261010221938.243859-5-longman@redhat.com> In-Reply-To: <20261010221938.243859-1-longman@redhat.com> References: <20261010221938.243859-1-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: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Before commit 103b08709e8a ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping"), the partition state can be freely switched from "root" to "isolated" and vice versa. After that commit, the switch from "root" to "isolated" can fail if it exhausts all the housekeeping CPUs. Later on, the switch from "isolated" to "root" can also fail if some of the partition CPUs are boot-time isolated by "isolcpus". A local or remote partition is made invalid when the switch fails. However there are 2 problems with the existing invalidation code. 1) Both the subpartitions_cpus and isolated_cpus are not properly updated. 2) In the case of remote partition with remote_partition flag set, it is not cleared. Fix this by calling the proper partition disabling function in this case. On an x86 test system with boot option "isolcpus=10 cgroup_debug" set and more than 16 cores, the following commands were executed after boot. # cd /sys/fs/cgroup # echo +cpuset > cgroup.subtree_control # cat cpuset.cpus.isolated 10 # mkdir A # echo 10-12 > A/cpuset.cpus # echo isolated > A/cpuset.cpus.partition # cat A/cpuset.cpus.partition isolated Before the patch: # echo root > A/cpuset.cpus.partition # cat A/cpuset.cpus.partition root invalid (partition config conflicts with housekeeping setup) # cat cpuset.cpus.isolated .__DEBUG__.cpuset.cpus.subpartitions 10-12 10-12 After the patch: # echo root > A/cpuset.cpus.partition # cat A/cpuset.cpus.partition root invalid (partition config conflicts with housekeeping setup) # cat cpuset.cpus.isolated .__DEBUG__.cpuset.cpus.subpartitions 10 Reported-by: Tejun Heo Link: https://lore.kernel.org/lkml/7f4c57b26ad120ab30adf35653f1dd94@kernel.org/ Fixes: 4a74e418881f ("cgroup/cpuset: Check partition conflict with housekeeping setup") Fixes: 103b08709e8a ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping") Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index fb41cd76add6..df1619d7a701 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2863,6 +2863,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) struct cpuset *parent = parent_cs(cs); struct tmpmasks tmpmask; bool isolcpus_updated = false; + bool disable_partition = false; if (old_prs == new_prs) return 0; @@ -2920,15 +2921,21 @@ static int update_prstate(struct cpuset *cs, int new_prs) */ compute_excpus(cs, tmpmask.new_cpus); if (prstate_housekeeping_conflict(new_prs, parent_prs, - tmpmask.new_cpus, NULL)) + tmpmask.new_cpus, NULL)) { + disable_partition = true; err = PERR_HKEEPING; - else + } else { isolcpus_updated = true; + } } else { /* * Switching back to member is always allowed even if it * disables child partitions. */ + disable_partition = true; + } + + if (disable_partition) { if (is_remote_partition(cs)) remote_partition_disable(cs, &tmpmask); else @@ -2937,7 +2944,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) /* * Invalidation of child partitions will be done in - * update_cpumasks_hier(). + * update_cpumasks_hier() below. */ } out: @@ -2956,8 +2963,8 @@ static int update_prstate(struct cpuset *cs, int new_prs) isolated_cpus_update(old_prs, new_prs, cs->effective_xcpus); spin_unlock_irq(&callback_lock); - /* Force update if switching back to member & update effective_xcpus */ - update_cpumasks_hier(cs, &tmpmask, !new_prs); + /* Force update if partition is disabled & update effective_xcpus */ + update_cpumasks_hier(cs, &tmpmask, disable_partition); /* A newly created partition must have effective_xcpus set */ WARN_ON_ONCE(!old_prs && (new_prs > 0) -- 2.55.0