Change reparent_to_init to reparent_to_kthreadd

When a kernel thread calls daemonize, instead of reparenting the thread to
init reparent the thread to kthreadd next to the threads created by
kthread_create.

This is really just a stop gap until daemonize goes away, but it does
ensure no kernel threads are under init and they are all in one place that
is easy to find.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/exit.c

@@ -26,6 +26,7 @@
 #include <linux/profile.h>
 #include <linux/mount.h>
 #include <linux/proc_fs.h>
+#include <linux/kthread.h>
 #include <linux/mempolicy.h>
 #include <linux/taskstats_kern.h>
 #include <linux/delayacct.h>
@@ -254,26 +255,25 @@ static int has_stopped_jobs(struct pid *pgrp)
 }
 
 /**
- * reparent_to_init - Reparent the calling kernel thread to the init task of the pid space that the thread belongs to.
+ * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
  *
  * If a kernel thread is launched as a result of a system call, or if
- * it ever exits, it should generally reparent itself to init so that
- * it is correctly cleaned up on exit.
+ * it ever exits, it should generally reparent itself to kthreadd so it
+ * isn't in the way of other processes and is correctly cleaned up on exit.
  *
  * The various task state such as scheduling policy and priority may have
  * been inherited from a user process, so we reset them to sane values here.
  *
- * NOTE that reparent_to_init() gives the caller full capabilities.
+ * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
  */
-static void reparent_to_init(void)
+static void reparent_to_kthreadd(void)
 {
 	write_lock_irq(&tasklist_lock);
 
 	ptrace_unlink(current);
 	/* Reparent to init */
 	remove_parent(current);
-	current->parent = child_reaper(current);
-	current->real_parent = child_reaper(current);
+	current->real_parent = current->parent = kthreadd_task;
 	add_parent(current);
 
 	/* Set the exit signal to SIGCHLD so we signal init on exit */
@@ -400,7 +400,7 @@ void daemonize(const char *name, ...)
 	current->files = init_task.files;
 	atomic_inc(&current->files->count);
 
-	reparent_to_init();
+	reparent_to_kthreadd();
 }
 
 EXPORT_SYMBOL(daemonize);