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([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5634ca16da7sm15469803e0c.17.2026.01.12.09.53.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jan 2026 09:54:03 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: Date: Mon, 12 Jan 2026 12:53:49 -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 12/33] cpuset: Provide lockdep check for cpuset lock held To: Frederic Weisbecker , LKML Cc: =?UTF-8?Q?Michal_Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org References: <20260101221359.22298-1-frederic@kernel.org> <20260101221359.22298-13-frederic@kernel.org> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/11/26 8:43 PM, Waiman Long wrote: > On 1/1/26 5:13 PM, Frederic Weisbecker wrote: >> cpuset modifies partitions, including isolated, while holding the cpuset >> mutex. >> >> This means that holding the cpuset mutex is safe to synchronize against >> housekeeping cpumask changes. >> >> Provide a lockdep check to validate that. >> >> Signed-off-by: Frederic Weisbecker >> --- >>   include/linux/cpuset.h | 2 ++ >>   kernel/cgroup/cpuset.c | 7 +++++++ >>   2 files changed, 9 insertions(+) >> >> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h >> index a98d3330385c..1c49ffd2ca9b 100644 >> --- a/include/linux/cpuset.h >> +++ b/include/linux/cpuset.h >> @@ -18,6 +18,8 @@ >>   #include >>   #include >>   +extern bool lockdep_is_cpuset_held(void); >> + >>   #ifdef CONFIG_CPUSETS >>     /* >> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c >> index 3afa72f8d579..5e2e3514c22e 100644 >> --- a/kernel/cgroup/cpuset.c >> +++ b/kernel/cgroup/cpuset.c >> @@ -283,6 +283,13 @@ void cpuset_full_unlock(void) >>       cpus_read_unlock(); >>   } >>   +#ifdef CONFIG_LOCKDEP >> +bool lockdep_is_cpuset_held(void) >> +{ >> +    return lockdep_is_held(&cpuset_mutex); >> +} >> +#endif >> + >>   static DEFINE_SPINLOCK(callback_lock); >>     void cpuset_callback_lock_irq(void) > > The cgroup/for-next tree already have a similar > lockdep_assert_cpuset_lock_held() defined. So you can drop this patch > if this series won't land in the next merge window. Sorry, the other new lockdep API isn't exactly the same as what you propose here. So it is not a replacement for your use case. Sorry for the noise. Cheers, Longman