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authorSukadev Bhattiprolu <sukadev@us.ibm.com>2007-10-18 23:40:13 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-19 11:53:40 -0700
commit3eb07c8c8adb6f0572baba844ba2d9e501654316 (patch)
tree5c3d527f6b003b316d41119320ebd5c589c8afd0 /kernel/exit.c
parent0fbc26a6cfab9f377e82e28225f2c0c6b4661e5c (diff)
pid namespaces: destroy pid namespace on init's death
Terminate all processes in a namespace when the reaper of the namespace is exiting. We do this by walking the pidmap of the namespace and sending SIGKILL to all processes. Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Acked-by: Pavel Emelyanov <xemul@openvz.org> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index d9e8e5ee9d7..567909fd6be 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -879,7 +879,32 @@ static inline void exit_child_reaper(struct task_struct *tsk)
if (likely(tsk->group_leader != task_child_reaper(tsk)))
return;
- panic("Attempted to kill init!");
+ if (tsk->nsproxy->pid_ns == &init_pid_ns)
+ panic("Attempted to kill init!");
+
+ /*
+ * @tsk is the last thread in the 'cgroup-init' and is exiting.
+ * Terminate all remaining processes in the namespace and reap them
+ * before exiting @tsk.
+ *
+ * Note that @tsk (last thread of cgroup-init) may not necessarily
+ * be the child-reaper (i.e main thread of cgroup-init) of the
+ * namespace i.e the child_reaper may have already exited.
+ *
+ * Even after a child_reaper exits, we let it inherit orphaned children,
+ * because, pid_ns->child_reaper remains valid as long as there is
+ * at least one living sub-thread in the cgroup init.
+
+ * This living sub-thread of the cgroup-init will be notified when
+ * a child inherited by the 'child-reaper' exits (do_notify_parent()
+ * uses __group_send_sig_info()). Further, when reaping child processes,
+ * do_wait() iterates over children of all living sub threads.
+
+ * i.e even though 'child_reaper' thread is listed as the parent of the
+ * orphaned children, any living sub-thread in the cgroup-init can
+ * perform the role of the child_reaper.
+ */
+ zap_pid_ns_processes(tsk->nsproxy->pid_ns);
}
fastcall NORET_TYPE void do_exit(long code)