Re: [PATCH] s390/mm: Fix in_atomic() handling in do_secure_storage_access()

Claudio Imbrenda
2025-06-04T16:49:05Z

On Wed, 4 Jun 2025 18:27:49 +0200
Alexander Gordeev <agordeev@linux.ibm.com> wrote:

> On Tue, Jun 03, 2025 at 03:49:36PM +0200, Heiko Carstens wrote:
> > diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> > index 3829521450dd..e1ad05bfd28a 100644
> > --- a/arch/s390/mm/fault.c
> > +++ b/arch/s390/mm/fault.c
> > @@ -441,6 +441,8 @@ void do_secure_storage_access(struct pt_regs *regs)
> > if (rc)
> > BUG();
> > } else {
> > + if (faulthandler_disabled())
> > + return handle_fault_error_nolock(regs, 0);
> >
>
> This could trigger WARN_ON_ONCE() in handle_fault_error_nolock():
>
> if (WARN_ON_ONCE(!si_code))
> si_code = SEGV_MAPERR;
>
> Would this warning be justified in this case (aka user_mode(regs) ==
> true)?

I think so, because if we are in usermode, we should never trigger
faulthandler_disabled()

>
> > mm = current->mm;
> > mmap_read_lock(mm);
> > vma = find_vma(mm, addr);