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([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-889a85f02efsm76981516d6.46.2025.12.16.06.58.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Dec 2025 06:58:03 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <5a35692f-2800-4fd4-9c23-97d0284293df@redhat.com> Date: Tue, 16 Dec 2025 09:58:02 -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 -next] cpuset: add cpuset1_online_css helper for v1-specific operations To: =?UTF-8?Q?Michal_Koutn=C3=BD?= , Chen Ridong Cc: tj@kernel.org, hannes@cmpxchg.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com References: <20251216012845.2437419-1-chenridong@huaweicloud.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12/16/25 9:03 AM, Michal Koutný wrote: > On Tue, Dec 16, 2025 at 08:13:53PM +0800, Chen Ridong wrote: >> Regarding the lock assertions: cpuset_mutex is defined in cpuset.c and is not visible in >> cpuset-v1.c. Given that cpuset v1 is deprecated, would you prefer that we add a helper to assert >> cpuset_mutex is locked? Is that worth? > It could be un-static'd and defined in cpuset-internal.h. (Hopefully, we > should not end up with random callers of the helper but it's IMO worth > it for docs and greater safety.) I would suggest defining a "assert_cpuset_lock_held(void)" helper function and put the declaration in include/linux/cpuset.h together with cpuset_lock/unlock() to complete the full set. This will allow other kernel subsystems to acquire the cpuset_mutex and assert that the mutex was held. > >> Should we guard with !cpuset_v2() or !is_in_v2mode()? >> >> In cgroup v1, if the cpuset is operating in v2 mode, are these flags still valid? > I have no experience with this transitional option so that made me look > at the docs and there we specify it only affects behaviors of CPU masks, > not the extra flags. So I wanted to suggest !cpuset_v2(), correct? The "cpuset_v2_mode" mount flag is used for making the behavior of cpuset.{cpus,mems}.effective in v1 behave like in v2. It has no effect on other v1 specific control files. So cpuset1_online_css() should only be called if "!cpuset_v2()". Cheers, Longman > > Thanks, > Michal