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shakeel.butt@linux.dev, 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: H4sIAAAAAAAAA+NgFrrDJMWRmVeSWpSXmKPExsXC9ZZnoa6wyb0Mg5M7BSwurb7A4sDo8WLz TMYAxigum5TUnMyy1CJ9uwSujHkvDAoecFb0bt7J2MD4h72LkZNDQsBE4uvJA8ww9o+/k9lA bDYBdYkbN36CxUUEFCQ29z5jBbGZBU7LSFy7qANiCwv4SGz7dIwRxGYRUJVonLIKqIaDg1fA TOJHvzDESHmJ1RsgxnMChS8/PM0CYgsJmEq0vm9hgqhZzikxeyojhC0pcXDFDZYJjLwLGBlW MQpl5pXlJmbmmOhlVOZlVugl5+duYgT6eVntn+gdjJ8uBB9iFOBgVOLhvaB6N0OINbGsuDL3 EKMEB7OSCG/CijsZQrwpiZVVqUX58UWlOanFhxilOViUxHmNvpWnCAmkJ5akZqemFqQWwWSZ ODilGhjNHgq61zB//OQi9e757iYn47eMCyc+eGq0PuTfjIizDCq9a7N/Thd6lZ1apHxglel5 s9xPouq79slNjr0l+Ndr3saqFbbfTRhqAmt0hHfa6onzPHCIybbqDj4i/+HnKit+yXkii7eL KqyUfFj56muz2vKIm3rBOVrfWGY/z1vRePH+qqI3yX+UWIozEg21mIuKEwEpvUvz7wEAAA== X-Brightmail-Tracker: H4sIAAAAAAAAAzWSfUhTexjH+53z2zlnw9VpSR6sSBbjgmRvVDy9YP4RdIreKKG4l2ijTm05 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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) 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_); } static void lockdep_release_cpus_lock(void) -- 2.17.1