2 files changed, 9 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index 59d229a2a3e0..879b3aacac32 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -237,7 +237,7 @@ static void wake_offline_cpus(void)
                 if (!cpu_online(cpu)) {
                         printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
                                cpu);
-                        cpu_up(cpu);
+                        WARN_ON(cpu_up(cpu));
                 }
         }
 }
diff --git a/kernel/kexec.c b/kernel/kexec.c
index c8380ad203bc..28c57069ef68 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1683,6 +1683,14 @@ int kernel_kexec(void)
                 kexec_in_progress = true;
                 kernel_restart_prepare(NULL);
                 migrate_to_reboot_cpu();
+
+                /*
+                 * migrate_to_reboot_cpu() disables CPU hotplug assuming that
+                 * no further code needs to use CPU hotplug (which is true in
+                 * the reboot case). However, the kexec path depends on using
+                 * CPU hotplug again; so re-enable it here.
+                 */
+                cpu_hotplug_enable();
                 printk(KERN_EMERG "Starting new kernel\n");
                 machine_shutdown();
         }