On Mon, Oct 28, 2024 at 1:57 PM Pierre Gondois <pierre.gondois@xxxxxxx> wrote:
>
> The following BUG was triggered. sugov_update_shared() locks a
> raw_spinlock while cpc_write() locks a spinlock. To have a correct
> wait-type order, update rmw_lock to a raw_spinlock.
>
> Also save irq state.
>
> =============================
> [ BUG: Invalid wait context ]
> 6.12.0-rc2-XXX #406 Not tainted
> -----------------------------
> kworker/1:1/62 is trying to lock:
> ffffff8801593030 (&cpc_ptr->rmw_lock){+.+.}-{3:3}, at: cpc_write+0xcc/0x370
> other info that might help us debug this:
> context-{5:5}
> 2 locks held by kworker/1:1/62:
> #0: ffffff897ef5ec98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x50
> #1: ffffff880154e238 (&sg_policy->update_lock){....}-{2:2}, at: sugov_update_shared+0x3c/0x280
> stack backtrace:
> CPU: 1 UID: 0 PID: 62 Comm: kworker/1:1 Not tainted 6.12.0-rc2-g9654bd3e8806 #406
> Workqueue: 0x0 (events)
> Call trace:
> dump_backtrace+0xa4/0x130
> show_stack+0x20/0x38
> dump_stack_lvl+0x90/0xd0
> dump_stack+0x18/0x28
> __lock_acquire+0x480/0x1ad8
> lock_acquire+0x114/0x310
> _raw_spin_lock+0x50/0x70
> cpc_write+0xcc/0x370
> cppc_set_perf+0xa0/0x3a8
> cppc_cpufreq_fast_switch+0x40/0xc0
> cpufreq_driver_fast_switch+0x4c/0x218
> sugov_update_shared+0x234/0x280
> update_load_avg+0x6ec/0x7b8
> dequeue_entities+0x108/0x830
> dequeue_task_fair+0x58/0x408
> __schedule+0x4f0/0x1070
> schedule+0x54/0x130
> worker_thread+0xc0/0x2e8
> kthread+0x130/0x148
> ret_from_fork+0x10/0x20
>
> Fixes: 60949b7b8054 ("ACPI: CPPC: Fix MASK_VAL() usage")
> Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
> ---
>
> Notes:
> v2:
> - Do the actual changes.
>
> drivers/acpi/cppc_acpi.c | 9 +++++----
> include/acpi/cppc_acpi.h | 2 +-
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index c3fc2c05d868..1a40f0514eaa 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -867,7 +867,7 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
>
> /* Store CPU Logical ID */
> cpc_ptr->cpu_id = pr->id;
> - spin_lock_init(&cpc_ptr->rmw_lock);
> + raw_spin_lock_init(&cpc_ptr->rmw_lock);
>
> /* Parse PSD data for this CPU */
> ret = acpi_get_psd(cpc_ptr, handle);
> @@ -1087,6 +1087,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> struct cpc_reg *reg = ®_res->cpc_entry.reg;
> struct cpc_desc *cpc_desc;
> + unsigned long flags;
>
> size = GET_BIT_WIDTH(reg);
>
> @@ -1126,7 +1127,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> return -ENODEV;
> }
>
> - spin_lock(&cpc_desc->rmw_lock);
> + raw_spin_lock_irqsave(&cpc_desc->rmw_lock, flags);
> switch (size) {
> case 8:
> prev_val = readb_relaxed(vaddr);
> @@ -1141,7 +1142,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> prev_val = readq_relaxed(vaddr);
> break;
> default:
> - spin_unlock(&cpc_desc->rmw_lock);
> + raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags);
> return -EFAULT;
> }
> val = MASK_VAL_WRITE(reg, prev_val, val);
> @@ -1174,7 +1175,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> }
>
> if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
> - spin_unlock(&cpc_desc->rmw_lock);
> + raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags);
>
> return ret_val;
> }
> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
> index 76e44e102780..62d368bcd9ec 100644
> --- a/include/acpi/cppc_acpi.h
> +++ b/include/acpi/cppc_acpi.h
> @@ -65,7 +65,7 @@ struct cpc_desc {
> int write_cmd_status;
> int write_cmd_id;
> /* Lock used for RMW operations in cpc_write() */
> - spinlock_t rmw_lock;
> + raw_spinlock_t rmw_lock;
> struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
> struct acpi_psd_package domain_info;
> struct kobject kobj;
> --
Applied (with edited changelog) as 6.12-rc material, thanks!
