diff options
Diffstat (limited to 'kernel/pid_namespace.c')
| -rw-r--r-- | kernel/pid_namespace.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 8a98b1af9376..46e0d5a3f91f 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -247,7 +247,24 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) set_current_state(TASK_INTERRUPTIBLE); if (pid_ns->pid_allocated == init_pids) break; + /* + * Release tasks_rcu_exit_srcu to avoid following deadlock: + * + * 1) TASK A unshare(CLONE_NEWPID) + * 2) TASK A fork() twice -> TASK B (child reaper for new ns) + * and TASK C + * 3) TASK B exits, kills TASK C, waits for TASK A to reap it + * 4) TASK A calls synchronize_rcu_tasks() + * -> synchronize_srcu(tasks_rcu_exit_srcu) + * 5) *DEADLOCK* + * + * It is considered safe to release tasks_rcu_exit_srcu here + * because we assume the current task can not be concurrently + * reaped at this point. + */ + exit_tasks_rcu_stop(); schedule(); + exit_tasks_rcu_start(); } __set_current_state(TASK_RUNNING); |