From: Pavel Emelyanov Make task release its namespaces after it has reparented all his children to child_reaper, but before it notifies its parent about its death. The reason to release namespaces after reparenting is that when task exits it may send a signal to its parent (SIGCHLD), but if the parent has already exited its namespaces there will be no way to decide what pid to dever to him - parent can be from different namespace. The reason to release namespace before notifying the parent it that when task sends a SIGCHLD to parent it can call wait() on this taks and release it. But releasing the mnt namespace implies dropping of all the mounts in the mnt namespace and NFS expects the task to have valid sighand pointer. Thanks to Oleg for pointing out some races that can apear and helping with patches and fixes. Signed-off-by: Pavel Emelyanov Cc: Oleg Nesterov Cc: Sukadev Bhattiprolu Cc: Paul Menage Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton --- kernel/exit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/exit.c~pid-namespaces-move-exit_task_namespaces kernel/exit.c --- a/kernel/exit.c~pid-namespaces-move-exit_task_namespaces +++ a/kernel/exit.c @@ -773,6 +773,7 @@ static void exit_notify(struct task_stru * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) */ forget_original_parent(tsk); + exit_task_namespaces(tsk); write_lock_irq(&tasklist_lock); /* @@ -983,7 +984,6 @@ fastcall NORET_TYPE void do_exit(long co module_put(tsk->binfmt->module); proc_exit_connector(tsk); - exit_task_namespaces(tsk); exit_notify(tsk); #ifdef CONFIG_NUMA mpol_free(tsk->mempolicy); _