pidns: fix free_pid() to handle the first fork failure

"case 0" in free_pid() assumes that disable_pid_allocation() should
clear PIDNS_HASH_ADDING before the last pid goes away.

However this doesn't happen if the first fork() fails to create the
child reaper which should call disable_pid_allocation().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/pid.c b/kernel/pid.c
index ebe5e80b10f8495a3d6459e0203821f987237df0..9b9a26698144e126486e162955e49561514b1ce8 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -273,6 +273,11 @@ void free_pid(struct pid *pid)
                         */
                        wake_up_process(ns->child_reaper);
                        break;
+               case PIDNS_HASH_ADDING:
+                       /* Handle a fork failure of the first process */
+                       WARN_ON(ns->child_reaper);
+                       ns->nr_hashed = 0;
+                       /* fall through */
                case 0:
                        schedule_work(&ns->proc_work);
                        break;