From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-83.mta1.migadu.com [95.215.58.83]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6ECB43546F5 for ; Mon, 28 Sep 2026 01:40:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.83 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790559658; cv=none; b=kh+NWoUCvNQXPOzUFzxojSVhYDsK8U2HJ3RCNuzrITwFP/ua2NtUYM0HuRWLchLDw5zsPkYEoAuZsQjHeOGTNxoTCKwCVOEe/9g5donFP0TwBrL5NsCpXxQ/gg9n8DnSWpDGIgstLi4/kWNrzB+rjgWlNhp0JrIRslpncus74/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790559658; c=relaxed/simple; bh=hzHwDE34v1HLmM8SoW5+6io0DFeC9cWq420KEx5tFCc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YUYG3nhXjl9OOP1FML8zhEgP3vu78yziaJ2HNfEmNIEEnf6Yz+xseThcsL0xOJLiKs071pjg4xd/s3ykz2LOfeq6RpFSFQDvBsN6gIF6qy8lVaXRGxLu5yKj5ojgPxdOEwnyCy366Y7OHtof754I1LxJUYVU3CX757/3eQbt0dI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nQxaTHE7; arc=none smtp.client-ip=95.215.58.83 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) header.d=linux.dev header.i=@linux.dev header.b="nQxaTHE7" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=hzHwDE34v1HLmM8SoW5+6io0DFeC9cWq420KEx5tFCc=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790559654; v=1; x=1791164454; b=nQxaTHE7BjvQVVY4VZUMZCCjobGsoNBvy8YQqfjXDEe9zMAGre/xHFi3VPukhT2ZGRcMOx5o tjIkHaOSJhG/AXvbtpe4/Qy8UkAxdoFgiwlP+J2WLINCWLLd2hHZ3IiC1brYrVgMX2fGJjz1ChP GcrMBq4Q93hOab3FAMKIFGec= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 00eae308403adc8e; Mon, 28 Sep 2026 01:40:54 +0000 X-Mizu-Trace-ID: 00eae308403adc8e X-Migadu-Flow: FLOW_OUT Message-ID: <93e48fe3-d229-4870-af8a-32431d236211@linux.dev> Date: Mon, 28 Sep 2026 09:40:49 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/3] cgroup/cpuset: prevent activating local partition over remote one To: Hui Peng , Waiman Long , Guopeng Zhang , Tejun Heo , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: Shuah Khan , Chen Ridong , cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260924042729.1908863-1-benquike@gmail.com> <20260924042729.1908863-3-benquike@gmail.com> From: Ridong Chen In-Reply-To: <20260924042729.1908863-3-benquike@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/24/2026 12:27 PM, Hui Peng wrote: > Commit 6da580ec656a ("cgroup/cpuset: Don't allow creation of local > partition over a remote one") added a check in update_prstate() to reject > creating a top-level local partition whose cs->exclusive_cpus intersects > subpartitions_cpus. > > However, if a top-level cgroup A1 has a child A1/A2 enabled as a remote > partition on a subset of its exclusive CPUs (X2-3 on A1, CX2-3:P2 on > A1/A2), and A1 is then set to "root" (P1, becoming "root invalid" via > update_prstate() because its exclusive CPUs intersect subpartitions_cpus) > followed by expanding its CPUs to include additional non-remote CPUs > (CX1-3), update_cpumask() / update_exclusive_cpumask() calls > validate_partition() without going through update_prstate(). Because > validate_partition() does not check trialcs->exclusive_cpus against > subpartitions_cpus, A1 transitions from "root invalid" to a valid local > partition over the existing remote partition A1/A2 and triggers: > > WARNING: kernel/cgroup/cpuset.c:1943 at update_parent_effective_cpumask+0x189b/0x1fd0 > > Check trialcs->exclusive_cpus against subpartitions_cpus in > validate_partition() when !is_partition_valid(cs), and add a regression > test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. > Was this message assisted by an LLM? It would be helpful if you could provide the reproducer as I replied earlier, so that it can be understood more easily and tested. > Tested in QEMU on Linux 7.3.0-rc3 using > tools/testing/selftests/cgroup/test_cpuset_prs.sh. > > Fixes: 6da580ec656a ("cgroup/cpuset: Don't allow creation of local partition over a remote one") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Hui Peng > --- > kernel/cgroup/cpuset.c | 4 ++++ > tools/testing/selftests/cgroup/test_cpuset_prs.sh | 2 ++ > 2 files changed, 6 insertions(+) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 7381fa8502e7..7c5b4a8f1f3a 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -2415,6 +2415,10 @@ static enum prs_errcode validate_partition(struct cpuset *cs, struct cpuset *tri > if (cpumask_empty(trialcs->effective_xcpus)) > return PERR_INVCPUS; > > + if ((parent == &top_cpuset) && !is_partition_valid(cs) && > + cpumask_intersects(trialcs->exclusive_cpus, subpartitions_cpus)) > + return PERR_REMOTE; > + > if (prstate_housekeeping_conflict(trialcs->partition_root_state, > trialcs->effective_xcpus)) > return PERR_HKEEPING; > diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh > index b732078bf319..4a451350ad84 100755 > --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh > +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh > @@ -321,6 +321,8 @@ TEST_MATRIX=( > " C1-3:P2 X4:P2 . . . X3:P2 . . 0 A1:1-2|XA1:1-3|A2:3:XA2:3 A1:P2|A2:P2 1-3" > " C0-3:P2 . . C4-6 C0-4 . . . 0 A1:0-4|B1:5-6 A1:P2|B1:P0" > " C0-3:P2 . . C4-6 C0-4:C0-3 . . . 0 A1:0-3|B1:4-6 A1:P2|B1:P0 0-3" > + " X2-3 CX2-3:P2 . . P1:CX1-3 . . . 0 A1:1|A2:2-3|XA2:2-3 \ > + A1:P-1|A2:P2 2-3" > > # Local partition invalidation tests > " C0-3:X1-3:P2 C1-3:X2-3:P2 C2-3:X3:P2 \ -- Best regards Ridong