Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Cure nr_iowait_cpu() users
  init: Fix comment
  init, sched: Fix race between init and kthreadd

1 files changed, 12 insertions, 0 deletions

diff --git a/init/main.c b/init/main.c
index ac2e4a5f59ee..a42fdf4aeba9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -424,18 +424,26 @@ static void __init setup_command_line(char *command_line)
  * gcc-3.4 accidentally inlines this function, so use noinline.
  */
 
+static __initdata DECLARE_COMPLETION(kthreadd_done);
+
 static noinline void __init_refok rest_init(void)
 	__releases(kernel_lock)
 {
 	int pid;
 
 	rcu_scheduler_starting();
+	/*
+	 * We need to spawn init first so that it obtains pid 1, however
+	 * the init task will end up wanting to create kthreads, which, if
+	 * we schedule it before we create kthreadd, will OOPS.
+	 */
 	kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 	numa_default_policy();
 	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 	rcu_read_lock();
 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 	rcu_read_unlock();
+	complete(&kthreadd_done);
 	unlock_kernel();
 
 	/*
@@ -857,6 +865,10 @@ static noinline int init_post(void)
 
 static int __init kernel_init(void * unused)
 {
+	/*
+	 * Wait until kthreadd is all set-up.
+	 */
+	wait_for_completion(&kthreadd_done);
 	lock_kernel();
 
 	/*