[PATCH] namespaces: exit_task_namespaces() invalidates nsproxy

exit_task_namespaces() has replaced the former exit_namespace().  It
invalidates task->nsproxy and associated namespaces.  This is an issue for
the (futur) pid namespace which is required to be valid in exit_notify().

This patch moves exit_task_namespaces() after exit_notify() to keep nsproxy
valid.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Andrey Savochkin <saw@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/exit.c

@@ -920,7 +920,6 @@ fastcall NORET_TYPE void do_exit(long code)
 	exit_sem(tsk);
 	__exit_files(tsk);
 	__exit_fs(tsk);
-	exit_task_namespaces(tsk);
 	exit_thread();
 	cpuset_exit(tsk);
 	exit_keys(tsk);
@@ -935,6 +934,7 @@ fastcall NORET_TYPE void do_exit(long code)
 	tsk->exit_code = code;
 	proc_exit_connector(tsk);
 	exit_notify(tsk);
+	exit_task_namespaces(tsk);
 #ifdef CONFIG_NUMA
 	mpol_free(tsk->mempolicy);
 	tsk->mempolicy = NULL;