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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id n21sm7693768qtn.17.2020.03.28.18.06.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 28 Mar 2020 18:06:55 -0700 (PDT) From: Qian Cai To: tglx@linutronix.de Cc: mingo@redhat.com, bp@alien8.de, rjw@rjwysocki.net, lenb@kernel.org, peterz@infradead.org, linux-acpi@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Qian Cai Subject: [PATCH] x86/acpi: fix a deadlock with cpu hotplug Date: Sat, 28 Mar 2020 21:06:40 -0400 Message-Id: <20200329010640.14251-1-cai@lca.pw> X-Mailer: git-send-email 2.21.0 (Apple Git-122.2) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Similar to the commit 0266d81e9bf5 ("acpi/processor: Prevent cpu hotplug deadlock") except this is for acpi_processor_ffh_cstate_probe(): "The problem is that the work is scheduled on the current CPU from the hotplug thread associated with that CPU. It's not required to invoke these functions via the workqueue because the hotplug thread runs on the target CPU already. Check whether current is a per cpu thread pinned on the target CPU and invoke the function directly to avoid the workqueue." Since CONFIG_ACPI_PROCESSOR (for cstate.c) selects CONFIG_ACPI_CPU_FREQ_PSS (for processor_throttling.c) on x86, just declare call_on_cpu() from for processor_throttling.c as an external function and use it in cstate.c. WARNING: possible circular locking dependency detected ------------------------------------------------------ cpuhp/1/15 is trying to acquire lock: ffffc90003447a28 ((work_completion)(&wfc.work)){+.+.}-{0:0}, at: __flush_work+0x4c6/0x630 but task is already holding lock: ffffffffafa1c0e8 (cpuidle_lock){+.+.}-{3:3}, at: cpuidle_pause_and_lock+0x17/0x20 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (cpu_hotplug_lock){++++}-{0:0}: cpus_read_lock+0x3e/0xc0 irq_calc_affinity_vectors+0x5f/0x91 __pci_enable_msix_range+0x10f/0x9a0 pci_alloc_irq_vectors_affinity+0x13e/0x1f0 pci_alloc_irq_vectors_affinity at drivers/pci/msi.c:1208 pqi_ctrl_init+0x72f/0x1618 [smartpqi] pqi_pci_probe.cold.63+0x882/0x892 [smartpqi] local_pci_probe+0x7a/0xc0 work_for_cpu_fn+0x2e/0x50 process_one_work+0x57e/0xb90 worker_thread+0x363/0x5b0 kthread+0x1f4/0x220 ret_from_fork+0x27/0x50 -> #0 ((work_completion)(&wfc.work)){+.+.}-{0:0}: __lock_acquire+0x2244/0x32a0 lock_acquire+0x1a2/0x680 __flush_work+0x4e6/0x630 work_on_cpu+0x114/0x160 acpi_processor_ffh_cstate_probe+0x129/0x250 acpi_processor_evaluate_cst+0x4c8/0x580 acpi_processor_get_power_info+0x86/0x740 acpi_processor_hotplug+0xc3/0x140 acpi_soft_cpu_online+0x102/0x1d0 cpuhp_invoke_callback+0x197/0x1120 cpuhp_thread_fun+0x252/0x2f0 smpboot_thread_fn+0x255/0x440 kthread+0x1f4/0x220 ret_from_fork+0x27/0x50 other info that might help us debug this: Chain exists of: (work_completion)(&wfc.work) --> cpuhp_state-up --> cpuidle_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(cpuidle_lock); lock(cpuhp_state-up); lock(cpuidle_lock); lock((work_completion)(&wfc.work)); *** DEADLOCK *** 3 locks held by cpuhp/1/15: #0: ffffffffaf51ab10 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x69/0x2f0 #1: ffffffffaf51ad40 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x69/0x2f0 #2: ffffffffafa1c0e8 (cpuidle_lock){+.+.}-{3:3}, at: cpuidle_pause_and_lock+0x17/0x20 Call Trace: dump_stack+0xa0/0xea print_circular_bug.cold.52+0x147/0x14c check_noncircular+0x295/0x2d0 __lock_acquire+0x2244/0x32a0 lock_acquire+0x1a2/0x680 __flush_work+0x4e6/0x630 work_on_cpu+0x114/0x160 acpi_processor_ffh_cstate_probe+0x129/0x250 acpi_processor_evaluate_cst+0x4c8/0x580 acpi_processor_get_power_info+0x86/0x740 acpi_processor_hotplug+0xc3/0x140 acpi_soft_cpu_online+0x102/0x1d0 cpuhp_invoke_callback+0x197/0x1120 cpuhp_thread_fun+0x252/0x2f0 smpboot_thread_fn+0x255/0x440 kthread+0x1f4/0x220 ret_from_fork+0x27/0x50 Signed-off-by: Qian Cai --- arch/x86/kernel/acpi/cstate.c | 3 ++- drivers/acpi/processor_throttling.c | 2 +- include/acpi/processor.h | 3 +++ 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c index caf2edccbad2..49ae4e1ac9cd 100644 --- a/arch/x86/kernel/acpi/cstate.c +++ b/arch/x86/kernel/acpi/cstate.c @@ -161,7 +161,8 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu, /* Make sure we are running on right CPU */ - retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx); + retval = call_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx, + false); if (retval == 0) { /* Use the hint in CST */ percpu_entry->states[cx->index].eax = cx->address; diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c index 532a1ae3595a..122f63cacd86 100644 --- a/drivers/acpi/processor_throttling.c +++ b/drivers/acpi/processor_throttling.c @@ -897,7 +897,7 @@ static long __acpi_processor_get_throttling(void *data) return pr->throttling.acpi_processor_get_throttling(pr); } -static int call_on_cpu(int cpu, long (*fn)(void *), void *arg, bool direct) +int call_on_cpu(int cpu, long (*fn)(void *), void *arg, bool direct) { if (direct || (is_percpu_thread() && cpu == smp_processor_id())) return fn(arg); diff --git a/include/acpi/processor.h b/include/acpi/processor.h index 47805172e73d..9569b3467553 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -297,6 +297,9 @@ static inline void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx } #endif +/* in processor_throttling.c */ +int call_on_cpu(int cpu, long (*fn)(void *), void *arg, bool direct); + /* in processor_perflib.c */ #ifdef CONFIG_CPU_FREQ -- 2.21.0 (Apple Git-122.2)