1 files changed, 23 insertions, 1 deletions

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index ba5070ce5765..2f194e965715 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -12,7 +12,7 @@
 #include <linux/cpu.h>
 #include <linux/init.h>
 #include <linux/kthread.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/percpu.h>
 #include <linux/sched.h>
 #include <linux/stop_machine.h>
@@ -41,6 +41,7 @@ struct cpu_stopper {
 };
 
 static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
+static bool stop_machine_initialized = false;
 
 static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
 {
@@ -386,6 +387,8 @@ static int __init cpu_stop_init(void)
         cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu);
         register_cpu_notifier(&cpu_stop_cpu_notifier);
 
+        stop_machine_initialized = true;
+
         return 0;
 }
 early_initcall(cpu_stop_init);
@@ -485,6 +488,25 @@ int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
                                             .num_threads = num_online_cpus(),
                                             .active_cpus = cpus };
 
+        if (!stop_machine_initialized) {
+                /*
+                 * Handle the case where stop_machine() is called
+                 * early in boot before stop_machine() has been
+                 * initialized.
+                 */
+                unsigned long flags;
+                int ret;
+
+                WARN_ON_ONCE(smdata.num_threads != 1);
+
+                local_irq_save(flags);
+                hard_irq_disable();
+                ret = (*fn)(data);
+                local_irq_restore(flags);
+
+                return ret;
+        }
+
         /* Set the initial state and stop all online cpus. */
         set_state(&smdata, STOPMACHINE_PREPARE);
         return stop_cpus(cpu_online_mask, stop_machine_cpu_stop, &smdata);