I don't think this matters, but still... force_quiescent_state: * cpu_online_map is updated by the _cpu_down() * using __stop_machine(). Since we're in irqs disabled * section, __stop_machine() is not exectuting, hence * the cpu_online_map is stable. * * However, a cpu might have been offlined _just_ before * we disabled irqs while entering here. * And rcu subsystem might not yet have handled the CPU_DEAD * notification, leading to the offlined cpu's bit * being set in the rcp->cpumask. * * Hence cpumask = (rcp->cpumask & cpu_online_map) to prevent * sending smp_reschedule() to an offlined CPU. */ cpus_and(cpumask, rcp->cpumask, cpu_online_map); cpu_clear(rdp->cpu, cpumask); for_each_cpu_mask_nr(cpu, cpumask) smp_send_reschedule(cpu); However, // called by __stop_machine take_cpu_down() arch/x86/kernel/smpboot.c:cpu_disable_common() /* * HACK: * Allow any queued timer interrupts to get serviced * This is only a temporary solution until we cleanup * fixup_irqs as we do for IA64. */ local_irq_enable(); mdelay(1); local_irq_disable(); ... remove_cpu_from_maps(cpu); So it is possible to send the ipi to the dying CPU. I know nothing about this low-level irq code, most probably this is harmless. We already did clear_local_APIC(), but I don't understand what it does. Oleg. -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
