W dniu 1.12.2024 o 18:05, Chris Bainbridge pisze:
> This splat happens on suspend/resume on a HP laptop. It doesn't appear
> to be a recent regression, as a bisect only leads to 560af5dc839e
> ("lockdep: Enable PROVE_RAW_LOCK_NESTING with PROVE_LOCKING.") - so
> most likely the issue has been around for a while, but a recent kernel
> build with lockdep enabled will now show it.
Hello,
Thank you for this bug report.
The cause is that timekeeping_suspend takes a raw spinlock called "tick_freeze_lock". With this lock taken, this function indirectly calls mc146818_avoid_UIP, which takes a normal spinlockcalled
"rtc_lock".
It is not permissible to take a normal spinlock while holding a raw spinlock due to issues on PREEMPT_RT kernels:
https://docs.kernel.org/locking/locktypes.html#raw-spinlock-t-on-rt
