Re: [PATCH][v2] ACPI: processor_idle: Mark LPI enter functions as __cpuidle

["lihuisong (C)" <lihuisong@huawei.com>]

On 6/16/2026 3:26 PM, lirongqing wrote:
> From: Li RongQing <lirongqing@baidu.com>
>
> When function tracing or Kprobes is enabled, entering an ACPI Low
> Power Idle (LPI) state triggers the following RCU splat:
>
>    RCU not on for: acpi_idle_lpi_enter+0x4/0xd8
>    WARNING: CPU: 8 PID: 0 at include/linux/trace_recursion.h:162 function_trace_call+0x1e8/0x228
>
> The acpi_idle_lpi_enter() function is invoked within the cpuidle
> path after RCU has already been disabled for the current local CPU.
> Consequently, ftrace's function_trace_call() expects RCU to be
> actively watching before recording trace data, emitting a warning
> if it is not.
>
> Fix this by annotating acpi_idle_lpi_enter(), the generic __weak
> stub, and the RISC-V implementation of acpi_processor_ffh_lpi_enter()
> with __cpuidle. This moves these functions into the '.cpuidle.text'
> section, implicitly disabling ftrace instrumentation (notrace) along
> this sensitive path and preventing trace-induced RCU warnings during
> idle entry.
>
> Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
LGTM,
Acked-by: lihuisong@huawei.com