On Mon, Jun 30, 2025 at 02:31:00PM +0200, Alexander Gordeev wrote:
> On Thu, Jun 26, 2025 at 08:31:37PM +0500, Sabyrzhan Tasbolatov wrote:
>
> Hi Sabyrzhan,
>
> > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> > index d54e89f8c3e..32c432df24a 100644
> > --- a/mm/kasan/generic.c
> > +++ b/mm/kasan/generic.c
> > @@ -36,6 +36,17 @@
> > #include "kasan.h"
> > #include "../slab.h"
> >
> > +/*
> > + * Initialize Generic KASAN and enable runtime checks.
> > + * This should be called from arch kasan_init() once shadow memory is
> > ready.
> > + */
> > +void __init kasan_init_generic(void)
> > +{
> > + static_branch_enable(&kasan_flag_enabled);
>
> s390 crashes at this line, when the whole series is applied.
>
> FWIW, it looks like kasan is called while its state is not yet finalized.
> E.g. whether calling __asan_report_store4_noabort() before
> kasan_init_generic()
> is expected?
It crashes because with this conversion a call to static_branch_enable() is
introduced. This one get's called way before jump_label_init() init has been
called. Therefore the STATIC_KEY_CHECK_USE() in static_key_enable_cpuslocked()
triggers.
This again tries to emit a warning. Due to lack of console support that early
the kernel crashes.
One possible solution would be to move the kasan init function to
arch/s390/kernel/setup.c, after jump_label_init() has been called.
If we want this, is a different question.
It seems to work, so I see no reason for not doing that.
Vasily, since you did nearly all of the KASAN work for s390, do you have any
opinion about this?
