On Fri, May 13 2022 at 15:16, Ricardo Neri wrote: > On Mon, May 09, 2022 at 04:03:39PM +0200, Thomas Gleixner wrote: >> > + /* If we are here, IPI shorthands are enabled. */ >> > + apic->send_IPI_allbutself(NMI_VECTOR); >> >> So if the monitored cpumask is a subset of online CPUs, which is the >> case when isolation features are enabled, then you still send NMIs to >> those isolated CPUs. I'm sure the isolation folks will be enthused. > > Yes, I acknowledged this limitation in the cover letter. I should also update > Documentation/admin-guide/lockup-watchdogs.rst. > > This patchset proposes the HPET NMI watchdog as an opt-in feature. > > Perhaps the limitation might be mitigated by adding a check for > non-housekeeping > and non-monitored CPUs in exc_nmi(). However, that will not eliminate the > problem of isolated CPUs also getting the NMI.
Right. It's a mess...
