pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits
authorOleg Nesterov <oleg@tv-sign.ru>
Tue, 2 Sep 2008 21:35:49 +0000 (14:35 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 3 Sep 2008 02:21:38 +0000 (19:21 -0700)
commit950bbabb5a804690a0201190de5c22837f72f83f
tree0d198ac02244138936acdf201c80aa4cd2da0bbc
parentadd0d4dfd660e9e4fd0af3eac3cad23583c9558f
pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits

We don't change pid_ns->child_reaper when the main thread of the
subnamespace init exits.  As Robert Rex <robert.rex@exasol.com> pointed
out this is wrong.

Yes, the re-parenting itself works correctly, but if the reparented task
exits it needs ->parent->nsproxy->pid_ns in do_notify_parent(), and if the
main thread is zombie its ->nsproxy was already cleared by
exit_task_namespaces().

Introduce the new function, find_new_reaper(), which finds the new
->parent for the re-parenting and changes ->child_reaper if needed.  Kill
the now unneeded exit_child_reaper().

Also move the changing of ->child_reaper from zap_pid_ns_processes() to
find_new_reaper(), this consolidates the games with ->child_reaper and
makes it stable under tasklist_lock.

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=11391

Reported-by: Robert Rex <robert.rex@exasol.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c
kernel/pid_namespace.c