Executive brief
The Linux kernel's ACPI power management subsystem, which handles low-power idle states on processors, was triggering spurious RCU (Read-Copy-Update) warnings when function tracing or kernel probes were enabled. This is a code quality issue that could interfere with kernel debugging and instrumentation, but does not expose a security vulnerability or create a direct impact on system availability.
Technical details
The vulnerability is a RCU warning triggered when acpi_idle_lpi_enter() is invoked within the cpuidle path after RCU has been disabled for the local CPU. When ftrace function tracing or Kprobes are enabled, function_trace_call() expects RCU to be actively watching and emits a warning if it is not. The fix annotates acpi_idle_lpi_enter(), acpi_processor_ffh_lpi_enter() (generic stub and RISC-V implementation), and related functions with __cpuidle, which moves them into the '.cpuidle.text' section with implicit notrace annotation, preventing trace-induced RCU warnings during idle entry. This is a diagnostic/code quality fix rather than a security patch.
Affected products
- Linux Linux kernel multiple versions
Timeline
- 2026-08-28: disclosed: CVE-2026-80611 published
- 2026-06-16: patched: Fix committed by Li RongQing