Re: [PATCH] powercap: intel_rapl: Fix kernel panic during PMU unbind

[Rafael J. Wysocki (Intel)]

On Sat, Aug 15, 2026 at 8:45 PM Sumeet R.P. <sumeet4linux@xxxxxxxxx> wrote:
>
> On Sun, Jul 26, 2026 at 9:33 AM Sumeet Pawnikar <sumeet4linux@xxxxxxxxx> wrote:
> >
> > rapl_package_add_pmu() fails internally at perf_pmu_register(),
> > and rapl_pmu_update() leaves the global rapl_pmu.pmu structure
> > zero-initialized via memset and returns an error. But any
> > previously probed packages retain has_pmu = true.
> >
> > When the driver is subsequently unbound or removed,
> > rapl_package_remove_pmu_locked() sees has_pmu == true and
> > unconditionally calls perf_pmu_unregister(&rapl_pmu.pmu) on the
> > zeroed-out structure. This attempts a list_del_rcu() on a NULL
> > list head, immediately causing a kernel panic.
> >
> > Fix this by checking if the PMU is actually registered before
> > attempting to unregister it.
> >
> > Signed-off-by: Sumeet Pawnikar <sumeet4linux@xxxxxxxxx>
>
> Hi Rafael,
>
> Gentle ping.
> Any chance for this to go into next rc ?

It looks like I lost track of it, sorry.

Can you please resend it and make sure that your name in the S-o-b tag
is the same as in the From: header?

> > ---
> >  drivers/powercap/intel_rapl_common.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c
> > index 1006d183d508..22100f1ca222 100644
> > --- a/drivers/powercap/intel_rapl_common.c
> > +++ b/drivers/powercap/intel_rapl_common.c
> > @@ -1652,7 +1652,8 @@ void rapl_package_remove_pmu_locked(struct rapl_package *rp)
> >                         return;
> >         }
> >
> > -       perf_pmu_unregister(&rapl_pmu.pmu);
> > +       if (rapl_pmu.registered)
> > +               perf_pmu_unregister(&rapl_pmu.pmu);
> >         memset(&rapl_pmu, 0, sizeof(struct rapl_pmu));
> >  }
> >  EXPORT_SYMBOL_NS_GPL(rapl_package_remove_pmu_locked, "INTEL_RAPL");
> > --
> > 2.43.0
> >