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[88.156.142.67]) by smtp.gmail.com with ESMTPSA id e1-20020a05651236c100b004bd8534ebbcsm1109894lfs.37.2022.12.19.07.15.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Dec 2022 07:15:14 -0800 (PST) From: Krzysztof Kozlowski To: "Rafael J. Wysocki" , Len Brown , Pavel Machek , Greg Kroah-Hartman , Kevin Hilman , Ulf Hansson , Daniel Lezcano , Lorenzo Pieralisi , Sudeep Holla , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Krzysztof Kozlowski , Adrien Thierry , Brian Masney , linux-rt-users@vger.kernel.org Subject: [PATCH v2 3/5] cpuidle: psci: Do not suspend topology CPUs on PREEMPT_RT Date: Mon, 19 Dec 2022 16:15:01 +0100 Message-Id: <20221219151503.385816-4-krzysztof.kozlowski@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221219151503.385816-1-krzysztof.kozlowski@linaro.org> References: <20221219151503.385816-1-krzysztof.kozlowski@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1752656109308285796?= X-GMAIL-MSGID: =?utf-8?q?1752656109308285796?= Realtime kernels are not supposed to go into deep sleep modes (neither system nor CPUs) because the latencies might become unpredictable. Therefore actual power suspending of CPU topology is not that important. On the other hand, this runtime PM of CPU topology is not compatible with PREEMPT_RT: 1. Core cpuidle path disables IRQs. 2. Core cpuidle calls cpuidle-psci. 3. cpuidle-psci in __psci_enter_domain_idle_state() calls pm_runtime_put_sync_suspend() and pm_runtime_get_sync() which use spinlocks (which are sleeping on PREEMPT_RT): BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/0 preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 1 lock held by swapper/0/0: #0: ffff20524613c1a0 (&dev->power.lock){+.+.}-{3:3}, at: __pm_runtime_suspend+0x30/0xac irq event stamp: 18776 hardirqs last enabled at (18775): [] tick_nohz_idle_enter+0x7c/0x17c hardirqs last disabled at (18776): [] do_idle+0xe0/0x300 softirqs last enabled at (4310): [] __local_bh_enable_ip+0x98/0x280 softirqs last disabled at (4288): [] cgroup_idr_alloc.constprop.0+0x0/0xd0 Preemption disabled at: [] schedule_preempt_disabled+0x20/0x30 CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 6.1.0-rt5-00322-gb49b67f1d8dc #1 Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT) Call trace: dump_backtrace.part.0+0xe0/0xf0 show_stack+0x18/0x40 dump_stack_lvl+0x8c/0xb8 dump_stack+0x18/0x34 __might_resched+0x17c/0x214 rt_spin_lock+0x5c/0x100 __pm_runtime_suspend+0x30/0xac __psci_enter_domain_idle_state.constprop.0+0x60/0x104 psci_enter_domain_idle_state+0x18/0x2c cpuidle_enter_state+0x220/0x37c cpuidle_enter+0x38/0x50 do_idle+0x258/0x300 cpu_startup_entry+0x28/0x30 rest_init+0x104/0x180 arch_post_acpi_subsys_init+0x0/0x18 start_kernel+0x6fc/0x73c __primary_switched+0xbc/0xc4 Cc: Adrien Thierry Cc: Brian Masney Cc: linux-rt-users@vger.kernel.org Signed-off-by: Krzysztof Kozlowski --- drivers/cpuidle/cpuidle-psci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c index 57bc3e3ae391..9d971cc4b12b 100644 --- a/drivers/cpuidle/cpuidle-psci.c +++ b/drivers/cpuidle/cpuidle-psci.c @@ -72,7 +72,7 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev, ct_irq_enter_irqson(); if (s2idle) dev_pm_genpd_suspend(pd_dev); - else + else if (!IS_ENABLED(CONFIG_PREEMPT_RT)) pm_runtime_put_sync_suspend(pd_dev); ct_irq_exit_irqson(); @@ -85,7 +85,7 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev, ct_irq_enter_irqson(); if (s2idle) dev_pm_genpd_resume(pd_dev); - else + else if (!IS_ENABLED(CONFIG_PREEMPT_RT)) pm_runtime_get_sync(pd_dev); ct_irq_exit_irqson();