Michal Hocko <mho...@kernel.org> writes: > On Fri 01-06-18 10:25:59, Eric W. Biederman wrote: >> Michal Hocko <mho...@kernel.org> writes: >> >> > On Fri 01-06-18 09:32:42, Eric W. Biederman wrote: >> >> Michal Hocko <mho...@kernel.org> writes: >> > [...] >> >> > Group leader exiting early without tearing down the whole thread >> >> > group should be quite rare as well. No question that somebody might do >> >> > that on purpose though... >> >> >> >> The group leader exiting early is a completely legitimate and reasonable >> >> thing to do, even if it is rare. >> > >> > I am not saying it isn't legitimate. But the most common case is the >> > main thread waiting for its threads or calling exit which would tear the >> > whole group down. Is there any easy way to achieve this other than tkill >> > to group leader? Calling exit(3) from the leader performs group exit >> > IIRC. >> >> pthread_exit from the group leader. > > Right, forgot to mention this one but this would be quite exotic, > right?
Not exotic. It is easy to do and well defined. It would be easy to do if you are running a thread pool and closing unnecessary threads. Or frankly anything where the application is not assigning a special role to the initial thread. It does seem rare enough that no one has noticed how attrocious mm_update_next_owner is until now. My key point is that it is easy to trigger which makes the current mm_update_next_owner a fundamentally flawed design, and something that needs to be fixed. Eric
