arm64/juno-r2: Kernel panic in cgroup_fj_stress.sh on next-20250904

[John Stultz]

On Fri, Sep 5, 2025 at 10:50 AM John Stultz <jstultz at google.com> wrote:
>
> On Fri, Sep 5, 2025 at 6:21 AM Naresh Kamboju <naresh.kamboju at linaro.org> wrote:
> >
> > Kernel warnings and a panic were observed on Juno-r2 while running
> > LTP controllers (cgroup_fj_stress.sh) on the Linux next-20250904 with
> > SCHED_PROXY_EXEC=y enabled build.
> >
> > Regression Analysis:
> > - New regression? yes
> > - Reproducibility? yes
> >
> > First seen on next-20250904
> > Bad: next-20250904
> > Good: next-20250822
> >
> > Test regression: next-20250904 juno-r2 cgroup_fj_stress.sh kernel panic
> >
> > Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>
>
> Thank you for the testing and the report here!
>
> > Juno-r2:
> >  * LTP controllers
> >    * cgroup_fj_stress.sh
> >
> > Test crash:
> > cgroup_fj_stress_net_cls_1_200_one:
> > [  365.917504] /usr/local/bin/kirk[402]: cgroup_fj_stress_net_cls_1_200_one:
> > start (command: cgroup_fj_stress.sh net_cls 1 200 one)
> > [  374.230110] ------------[ cut here ]------------
> > [  374.230132] WARNING: lib/timerqueue.c:55 at
> > timerqueue_del+0x68/0x70, CPU#5: swapper/5/0
>
> This looks like we are removing a timer that was already removed from the queue.
>
> I don't see anything obvious right away in the delta that would clue
> me into what's going on, but I'll try to reproduce this.

So far I've not been able to reproduce this in my environment.  If you
are able to reproduce this easily, could you try enabling
CONFIG_DEBUG_OBJECTS_TIMERS to see if it shows anything?

thanks
-john