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

Alexander Gordeev
2025-06-05T09:04:43Z

On Wed, Jun 04, 2025 at 07:40:43PM +0200, Claudio Imbrenda wrote:
> > > > 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()
> >
> > I think I do not get you. We are in a system call and also in_atomic(),
> > so faulthandler_disabled() is true and handle_fault_error_nolock(regs, 0)
> > is called (above).
>
> what is the psw in regs?
> is it not the one that was being used when the exception was triggered?

Hmm, right. I assume is_kernel_fault() returns false not because
user_mode(regs) is true, but because we access the secondary AS.

Still, to me it feels wrong to trigger that warning due to a user
process activity. But anyway:

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>