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([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id a1e0cc1a2514c-944124c452asm16438567241.13.2026.01.12.06.51.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jan 2026 06:51:35 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: Date: Mon, 12 Jan 2026 09:51:28 -0500 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 cgroup/for-6.20 v4 4/5] cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict To: =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: Tejun Heo , Johannes Weiner , Jonathan Corbet , Shuah Khan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Sun Shaojie , Chen Ridong , Chen Ridong References: <20260112040856.460904-1-longman@redhat.com> <20260112040856.460904-5-longman@redhat.com> <2naek52bbrod4wf5dbyq2s3odqswy2urrwzsqxv3ozrtugioaw@sjw5m6gizl33> Content-Language: en-US In-Reply-To: <2naek52bbrod4wf5dbyq2s3odqswy2urrwzsqxv3ozrtugioaw@sjw5m6gizl33> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/12/26 5:51 AM, Michal Koutný wrote: > On Sun, Jan 11, 2026 at 11:08:55PM -0500, Waiman Long wrote: >> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > ... >> @@ -2632,6 +2641,9 @@ Cpuset Interface Files >> >> The root cgroup is always a partition root and its state cannot >> be changed. All other non-root cgroups start out as "member". >> + Even though the "cpuset.cpus.exclusive*" control files are not >> + present in the root cgroup, they are implicitly the same as >> + "cpuset.cpus". > cpuset.cpus.effective (that one is on root cpuset cg) > > (This was likely lost among my v2 comments.) Sorry, I might have missed this comment of yours. The "cpuset.cpus.exclusive" file lists all the CPUs that can be granted to its children as exclusive CPUs. The cgroup root is an implicit partition root where all its CPUs can be granted to its children whether they are online or offline. "cpuset.cpus.effective" OTOH ignores the offline CPUs as well as exclusive CPUs that have been passed down to existing descendant partition roots so it may differ from the implicit "cpuset.cpus.exclusive". Cheers, Longman