On 03/14, Oleg Nesterov wrote: > > On 03/14, Josh Triplett wrote: > > > > On Sat, Mar 14, 2015 at 11:38:29AM -0700, Thiago Macieira wrote: > > > On Saturday 14 March 2015 15:32:35 Oleg Nesterov wrote: > > > > It is not clear to me what do_wait() should do with ->autoreap child, even > > > > ignoring ptrace. > > > > > > > > Just suppose that real_parent has a single "autoreap" child. Should > > > > wait(NULL) hanf then? > > > > > > It should ignore the child that is set to autoreap. wait(NULL) should return - > > > ECHILD, indicating there are no children waiting to be reaped. > > > > Right. And I don't think the current code does this. I think we need > > to change wait_consider_task to early-return for ->autoreap just as it > > does for task_state == EXIT_DEAD. > > No. This EXIT_DEAD is absolutely different. And this is another indication > that you might use it wrongly ;) > > What we actually want is BUG_ON(task_state == EXIT_DEAD) here. We do not > want the EXIT_DEAD tasks in ->children/ptraced lists. These EXIT_DEAD tasks > complicate the exit/wait/reparent paths. > > However, currently this is TODO. The main problem is the locking in > wait_task_zombie(), we can set EXIT_DEAD and remove the task from list > under read_lock(). Let me clarify in case I confused you. The EXIT_DEAD check in do_wait() paths doesn't mean "autoreap". It means that this thread/process (depending on ptrace) was already reaped. It was reaped by our sub-thread, or it was reaped because we ignore SIGCHLD, or other reasons. This doesn't matter. In short, EXIT_DEAD means: we have to keep this thread on lists until the task which set this state calls release_task(). Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
