On Fri, 11 Jan 2019, h...@zytor.com wrote: > I still don't see why can't simply spin in the #BP handler until the > patch is complete.
I think this brings us to the already discussed possible deadlock, when one CPU#0 is in the middle of text_poke_bp(), CPU#1 is spinning inside spin_lock_irq*(&lock) and CPU#2 hits the breakpont while holding that very 'lock'. Then we're stuck forever, because CPU#1 will never handle the pending sync_core() IPI (it's not NMI). Or have I misunderstood what you meant? -- Jiri Kosina SUSE Labs
