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ast@kernel.org, ziy@nvidia.com, yuzhao@google.com, baolin.wang@linux.alibaba.com, usamaarif642@gmail.com, joel.granados@kernel.org, richard.weiyang@gmail.com, geert+renesas@glider.be, tim.c.chen@linux.intel.com, linux@treblig.org, alexander.shishkin@linux.intel.com, lillian@star-ark.net, chenhuacai@kernel.org, francesco@valla.it, guoweikang.kernel@gmail.com, link@vivo.com, jpoimboe@kernel.org, masahiroy@kernel.org, brauner@kernel.org, thomas.weissschuh@linutronix.de, oleg@redhat.com, mjguzik@gmail.com, andrii@kernel.org, wangfushuai@baidu.com, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-i2c@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, rcu@vger.kernel.org, linux-nfs@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: [PATCH v17 29/47] cpu/hotplug: use a weaker annotation in AP thread Date: Thu, 2 Oct 2025 17:12:29 +0900 Message-Id: <20251002081247.51255-30-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20251002081247.51255-1-byungchul@sk.com> References: <20251002081247.51255-1-byungchul@sk.com> X-Brightmail-Tracker: H4sIAAAAAAAAAzXSe0hTcRQH8H73tTtpcJmiN3sysOihaVmcIqI/+uP+0YsCoxLyppc2m7Nm aWqWlpI9NN+SU5tFuqaVuEhNrWVq6lCmE9OYmSHDMi11OU3LNqX/Ppzz5Xv+OTQuvU160wrV RUGt4pUyyo1wG1te4use+EnuP9bgCb1JRgJ+2VMJKHxeQUFq1X0SzM/KEaTULhCw0NCCIK8r C4epyr8UjL6bRFBg04igdPgvBiVDAziMdRViUKTJQjBYaiPAlPEQA03+DQxyn9ZhMFuqF4Gm w0LCF12BCOaHAmDUlkWBvWcIg4q7NhwaPm4Gy6tCChI1Dudpo4mEtoInBGSP2xB0G7UY6Cby SWjRekKHppOEnv46BO9+fccgu1tLwe+BGhJ6sx5Q0P67HYPUpmkcKifKKEiaGkQwN+MsLrIH gL1cT+3z5xwp6QSnN7zEuIriCsTZH9/AuWRDDNcwrSW4zA5frrZgQMRpqy5xyU1jJGfQbeIe 1X/FuCr9LYormRvBOWtvPcWNd3aKjqw+6bYnTFAqogX11r0hbvLiEf/zn8WX0wy1KBHNi24j Mc0ygWzG45vkf8/8yaZcppgNbF/fLO6yB7OONaTZFjM4Y1rF9nZtcdmdOcC+nGxBLhOMD5uU o3dmaFrC7GRn7rkvVa5lyyuNizVi59gyZCJcljI72JQfydhSpkzManLRklewb3V9RAaSaNEy 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OETyhY6jfJ1nkOLHQs8pvu1rDeYf1nL8uc4k3lXpp/nCey/p7av/lKzdL2g12YJ+cbJSor40 sCTzjTin2OFCuWiCPo3EDMcu576Hz1NRptg/uBcvRskox7IJnKO4XxRlkvXM5bq8C6M8i93M Ob+4UZQxq+DyLjREPAwjZVdy30tn/YqczzXa23/GiCNnX68HR1nGruBMQ4VEGZLUoGkNKFaj y05XabQrFhnS1EadJmfRvoz0ZhT5JduJiXN30IhvQwdiGSSPkXoVfrVMpMo2GNM7EMeQ8lip sr5HLZPuVxmPCfqMvfojWsHQgeYwWB4n3bRLUMrYg6osIU0QMgX9b5VgxPG5qHpP91hiSfBC aBynTMbYD/8/L9npyNmekprxvLLu7OzEoHZd17XhLeLuUafiP29qwj+BAx5uTWZCy47wqUNK Z9KJGUhITg3MXKU8HHMx/9Bw1SvZgs8f2c3+uJ2rNyYcT15falwwGDbuznrqUuC7M1z1yta/ HcR6z1/bdMWZvtJ4OTaoVUsTSb1B9QMgdJtnRwMAAA== X-CFilter-Loop: Reflected Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" cb92173d1f0 ("locking/lockdep, cpu/hotplug: Annotate AP thread") was introduced to make lockdep_assert_cpus_held() work in AP thread. However, the annotation is too strong for that purpose. We don't have to use more than try lock annotation for that. rwsem_acquire() implies: 1. might be a waiter on contention of the lock. 2. enter to the critical section of the lock. All we need in here is to act 2, not 1. So trylock version of annotation is sufficient for that purpose. Now that dept partially relies on lockdep annotaions, dept interpets rwsem_acquire() as a potential wait and might report a deadlock by the wait. Replace it with trylock version of annotation. Signed-off-by: Byungchul Park --- kernel/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index db9f6c539b28..285d7fa55523 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -538,7 +538,7 @@ int lockdep_is_cpus_held(void) =20 static void lockdep_acquire_cpus_lock(void) { - rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_); + rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 1, _THIS_IP_); } =20 static void lockdep_release_cpus_lock(void) --=20 2.17.1