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Wysocki" , Christian Loehle , Daniel Lezcano , Lorenzo Pieralisi , Marco Crivellari , Peter Zijlstra , Phil Auld , Sudeep Holla , Thomas Gleixner , Ulf Hansson , Waiman Long , linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, "Paul E. McKenney" Subject: [PATCH 05/47] cpuidle: Move CPUHP_AP_CPU_PM_STARTING post stop_machine() Date: Thu, 5 Nov 2026 17:30:03 +0100 Message-ID: <20261105163045.38862-6-frederic@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261105163045.38862-1-frederic@kernel.org> References: <20261105163045.38862-1-frederic@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes all the teardown callbacks while stopping all CPUs in the system. This doesn't mix-up well with running RT or isolated tasks. In order to transition smoothly from global stop_machine to finer grained synchronization between teardown callbacks and the other CPUs, a new stop machine post function has been introduced to be executed after the main one with IRQs still disabled while other CPUs can exit stop_machine(). The teardown callback here only touches local data and also the local power device under its power lock. Therefore it should be safe to run against other CPUs. Move this teardown callback to post stop_machine() accordingly. Signed-off-by: Frederic Weisbecker --- kernel/cpu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 58bb74f0fcb0..acc6a0e6446c 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1275,7 +1275,7 @@ void clear_tasks_mm_cpumask(int cpu) static int take_cpu_down(void *_param) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); - enum cpuhp_state target = max((int)st->target, CPUHP_AP_RCUTREE_DYING); + enum cpuhp_state target = max((int)st->target, CPUHP_AP_CPU_PM_STARTING); int err, cpu = smp_processor_id(); /* Ensure this CPU doesn't handle any more interrupts. */ @@ -1303,7 +1303,7 @@ static int take_cpu_down_post(void *_param) enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); int cpu = smp_processor_id(); - WARN_ON(st->state != CPUHP_AP_RCUTREE_DYING); + WARN_ON(st->state != CPUHP_AP_CPU_PM_STARTING); /* * Invoke the former CPU_DYING callbacks. DYING must not fail! */ -- 2.53.0