On Thu 01-10-15 17:41:15, Oleg Nesterov wrote: > On 10/01, Michal Hocko wrote: > > > > On Thu 01-10-15 17:00:10, Oleg Nesterov wrote: > > > On 10/01, Michal Hocko wrote: > > > > > > > > On Wed 30-09-15 20:24:05, Oleg Nesterov wrote: > > > > [...] > > > > > It is possible that the group leader > > > > > has the pending SIGKILL because its sub-thread originated the > > > > > coredump, > > > > > in this case we must not skip this process. > > > > > > > > I do not understand this. If the group leader has SIGKILL pending it > > > > will die anyway regardless whether we send another sigkill or not, no? > > > > > > Yes it will die, but only after the coredump is finished. > > > > > > Suppose we have a thread group with the group leader P and another > > > thread T. If T starts the coredump, it sends SIGKILL to P and waits > > > until it parks in exit_mm(). Then T actually dumps the core which may > > > need more memory, a lot of time, etc. > > > > > > We need to kill this process. Yes, P is already killed and it sleeps > > > in TASK_UNINTERRUPTIBLE so this thread does not need SIGKILL. But > > > do_send_sig_info(P) will also find T and kill it too to make > > > dump_interrupted() == T. > > > > I am still utterly confused :( Where do we kill T if it is not in the > > same thread group with P? > > But it is in the same thread group?
The whole loop is about sending sigkill to a process from a different thread group though. And this is what confused me completely. But I got the point finally. zap_process will add SIGKILL to all threads but the current which will go on without being killed and if this is not a thread group leader then we would miss it. Thanks for the clarification and feel free to add Acked-by: Michal Hocko <[email protected]> -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
