[PATCH] User namespaces: Only put the userns when we unhash the uid

[KOSAKI Motohiro]

> From: Serge E. Hallyn <serue at us.ibm.com>
>
> uids in namespaces other than init don't get a sysfs entry.
>
> For those in the init namespace, while we're waiting to remove
> the sysfs entry for the uid the uid is still hashed, and
> alloc_uid() may re-grab that uid without getting a new
> reference to the user_ns, which we've already put in free_user
> before scheduling remove_user_sysfs_dir().
>
> Reported-by: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>
> Signed-off-by: Serge E. Hallyn <serue at us.ibm.com>
> Acked-by: David Howells <dhowells at redhat.com>
> Tested-by: Ingo Molnar <mingo at elte.hu>

ok, thanks good patch.
  Tested-by: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>