Hi Paul,

FYI, there are new sparse warnings show up in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/dev
head:   8113c34a896f3a5b898224be4fc34771443f3d76
commit: 02b40ca09ad3f4d1db211b8a87c3b2b2461887d0 [20/22] cpu: wean _cpu_down() from __stop_machine()

+ kernel/cpu.c:294:25: sparse: incorrect type in argument 1 (different modifiers)
  kernel/cpu.c:294:25:    expected int ( *threadfn )( ... )
  kernel/cpu.c:294:25:    got int ( static [toplevel] [noreturn] *<noident> )( ... )
  kernel/cpu.c:519:13: sparse: symbol 'arch_disable_nonboot_cpus_begin' was not declared. Should it be static?
  kernel/cpu.c:523:13: sparse: symbol 'arch_disable_nonboot_cpus_end' was not declared. Should it be static?
  kernel/cpu.c:567:13: sparse: symbol 'arch_enable_nonboot_cpus_begin' was not declared. Should it be static?
  kernel/cpu.c:571:13: sparse: symbol 'arch_enable_nonboot_cpus_end' was not declared. Should it be static?
  kernel/cpu.c:624:6: sparse: symbol 'cpu_hotplug_disable_before_freeze' was not declared. Should it be static?
  kernel/cpu.c:636:6: sparse: symbol 'cpu_hotplug_enable_after_thaw' was not declared. Should it be static?
  kernel/cpu.c:204:9: sparse: context imbalance in 'clear_tasks_mm_cpumask' - different lock contexts for basic block

Due to this:

static int __noreturn cpu_down_kthread(void *unused)
           ~~~~~~~~~~

vim +294 kernel/cpu.c
   278					pr_alert("cpu_down_kthread: affinity failed errno %d\n",
   279						 tcd_param.ret);
   280			}
   281			if (tcd_param.ret == 0) {
   282				local_irq_disable();
   283				tcd_param.ret = take_cpu_down(&tcd_param);
   284				local_irq_enable();
   285			}
   286		}
   287	}
   288	
   289	/* Spawn cpu_down_kthread() at boot time. */
   290	static int __init cpu_down_init(void)
   291	{
   292		struct sched_param sp;
   293	
 > 294		cpu_down_task = kthread_create(cpu_down_kthread, NULL, "cpudown");
   295		if (IS_ERR(cpu_down_task)) {
   296			cpu_down_task = NULL;
   297			pr_alert("Creating cpu_down_task failed: CPU removal disabled.\n");
   298			return 0;
   299		}
   300		sp.sched_priority = MAX_RT_PRIO;
   301		sched_setscheduler_nocheck(cpu_down_task, SCHED_FIFO, &sp);
   302		return 0;

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0-DAY kernel build testing backend         Open Source Technology Centre
Fengguang Wu, Yuanhan Liu                              Intel Corporation