On Wed, Sep 23, 2026 at 08:32:08AM -0700, Sean Christopherson wrote:
> > > + return -EBUSY;
> > > +
> > > for (i = 0; i < HBP_NUM; i++) {
> > > struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]);
> > >
> >
> > Note how the other -EBUSY return is a WARN. Why is silently not doing
> > anything not a WARN in this case?
>
> Probably because the WARN would trigger anytime KGDB's NMI craziness happens
> to
> hit a vCPU, i.e. isn't a kernel bug.
Yeah, but using KGDB to install a watchpoint would then have
perf/ptrace/whatnot trip the "Can't find any breakpoint slot" case and
WARN, even though it isn't actually their fault either.
