From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.164 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793883859; b=X8OrcuC6rCBmlo/Tf5Ts2Pf94XBVHa/n0gRMZUom6VrPmV0Msye4XifjWEnHPicNAK1z RcU394BMfw0PbczEuoDO73SuTMZ28JI+NBJeT5JGac0aQVKMT/oTd3Scg6ujgqPNHGGcC XY693tbm2rDrm6rY96Op8bTbTTy9o9nb+BSDG35h41gN/KdGE3gJQXfWmrMG/b7oH7B6y V96pdnR1OcwOlUuQFeXj+kJcwcR0WjgL99zJmZ7+uG/13ubO28JDiqrtSDoi3RuhZmEu5 Vi9TDeFUazhrZtn7zGTkGi7qVkgEA+ywkhFeIxJLeMdmGi/9HiB1X55Yqpozf99jdqA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793883859; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=ljVZDzVIXJjcd9Ou8caC5YIrs7Owo+UZn82NsoYNtFI=; b=sCY/R0TFx5DXsKfoog1eYZdBuyeCVLRobqz1CKTddoPxtr6ZqNkityKDcBFQRI0tc0l+ kj90TfwP1vto6eQ0rWU5x6aEJpJMnhW5CelJ9r4cLP1y9sXNHwl4kBPZ+IJNCfgitmVZi f6LxahG4ZNosQmpA/Cbb9+9VR9Ndtm6StKuiLMjxKRlvJiAYU7wVw//evQoNV7ru58bUn rC5p6mc/8JmEx8JcLpw/jrOaGhTQvqxs0fbEDxnr3PpbhJ4LGUi776ubFqvEYIXmEMx65 DYln8X6V0LRCpCRvd8tNisqyLoOd4gFSjZu818euM1ImM4wzCkXtSrH8Z1FeLh+Xqow== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=KmDJwRsB; arc=none smtp.remote-ip=91.218.175.164 Received: from mta0.migadu.com (out-164.mta0.migadu.com [91.218.175.164]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A019606A335 for ; Thu, 5 Nov 2026 13:04:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 4A019606A335 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=KmDJwRsB X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=RdjxbMsSdN+BD16PpNIf6U9zDl/xhZz69PMzEzEBZV8=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793883855; v=1; x=1794488655; b=KmDJwRsBKprnFPcDORCicIJiAY9nl8/3fGVAlrwAOfOdq4opTQyBx5FBqq63tBwz6jxa1UH0 UhewUSJjK0EDYlcaWBsILIBq3dYfq9Pbep9OFyuCM87RhvyUAOF19OhOjpDfSzo0FVtREig6yic ym8fvIRB53sk8YliBbb9wrBQ= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id f4856373a4f80b9b; Thu, 05 Nov 2026 13:04:15 +0000 X-Mizu-Trace-ID: f4856373a4f80b9b X-Migadu-Flow: FLOW_OUT From: Guopeng Zhang To: longman@redhat.com, tj@kernel.org, ridong.chen@linux.dev Cc: guopeng.zhang@linux.dev, hannes@cmpxchg.org, mkoutny@suse.com, shuah@kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Guopeng Zhang Subject: [PATCH v2 3/3] cgroup/cpuset: Release isolated CPUs when the parent is invalid Date: Thu, 5 Nov 2026 21:03:44 +0800 Message-ID: <20261105130344.664336-4-guopeng.zhang@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261105130344.664336-1-guopeng.zhang@linux.dev> References: <20261105130344.664336-1-guopeng.zhang@linux.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Guopeng Zhang An isolated partition can be invalidated after its parent has already become invalid. update_parent_effective_cpumask() then skips returning CPUs to the parent, but also skips removing them from isolated_cpus. The invalid child continues to isolate CPUs that no longer belong to any valid isolated partition. For example, on a 32-CPU system with all CPUs online and without isolcpus= or nohz_full= boot parameters: cd /sys/fs/cgroup echo +cpuset > cgroup.subtree_control mkdir A echo 0,2-31 > A/cpuset.cpus echo root > A/cpuset.cpus.partition echo +cpuset > A/cgroup.subtree_control mkdir A/B echo 2-3 > A/B/cpuset.cpus echo isolated > A/B/cpuset.cpus.partition cat cpuset.cpus.isolated 2-3 echo 0 > /sys/devices/system/cpu/cpu1/online cat A/B/cpuset.cpus.partition isolated invalid cat cpuset.cpus.isolated 2-3 Release the invalidated child's isolated CPUs when its parent is no longer a valid partition. Use isolated_cpus_release() to preserve CPUs still covered by a valid isolated ancestor and by boot isolation. After this fix, cpuset.cpus.isolated is empty for this reproducer. Fixes: 11e5f407b64a ("cgroup/cpuset: Keep track of CPUs in isolated partitions") Signed-off-by: Guopeng Zhang --- kernel/cgroup/cpuset.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index fc5454c2740f..f3b808cea51c 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1976,10 +1976,15 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, /* * Make the current partition invalid. */ - if (is_partition_valid(parent)) + if (is_partition_valid(parent)) { adding = cpumask_and(tmp->addmask, cs->effective_xcpus, parent->effective_xcpus); + } else if (old_prs == PRS_ISOLATED) { + /* No valid parent will release these isolated CPUs. */ + cpumask_copy(tmp->addmask, cs->effective_xcpus); + isolated_cpus_release(cs, tmp->addmask); + } if (old_prs > 0) new_prs = -old_prs; -- 2.43.0