On Sun, Mar 15, 2015 at 08:55:06PM +0100, Oleg Nesterov wrote: > On 03/15, Josh Triplett wrote: > > On Sun, Mar 15, 2015 at 03:52:23PM +0100, Oleg Nesterov wrote: > > > On 03/15, Josh Triplett wrote: > > > > Add a CLONE_AUTOREAP flag to request this behavior unconditionally, > > > > > > Yes, CLONE_AUTOREAP is much better. And I agree (mostly) with that > > > we should rely on do_notify_parent(). > > > > > > Howver the patch still doesn't look right. First of all, ->autoreap > > > should be per-process, not per-thread. > > > > Ah, you're thinking of the case where the parent process launches a > > ... > > Not really, although we probably need more sanity checks. > > It should be per-process simply because this "autoreap" affects the whole > process. And the sub-threads are already "autoreap". And these 2 autoreap's > semantics differ, we should not confuse them. Will the approach I suggested, of having clones with CLONE_THREAD inherit the autoreap value rather than setting it from CLONE_AUTOREAP, implement the semantics you're looking for? Also, are you suggesting that CLONE_AUTOREAP with CLONE_THREAD should produce -EINVAL, or just that it should be ignored? > > (As an aside, what *is* the use case for CLONE_PARENT without > > CLONE_THREAD?) > > To me CLONE_PARENT is another historical mistake and the source of misc > problems ;) I kinda figured. :) > > > And there are ptrace/mt issues, > > > it seems. Just for example, we should avoid EXIT_TRACE if autoreap in > > > wait_task_zombie() even if we are going to re-notify parent. > > > > I don't see how EXIT_TRACE can happen in wait_task_zombie if autoreap is > > set. wait_task_zombie does a cmpxchg with exit_state and doesn't > > proceed unless exit_state was EXIT_ZOMBIE, and I don't see how we can > > ever reach the EXIT_ZOMBIE state if autoreap. > > Because you again forgot about ptrace ;) > > Josh. Let me try to summarise this later when I have time. Again, I am > not sure, perhaps this is even simpler than I currently think. And let > me apologize in advance, most probably I will be busy tomorrow. I look forward to your later review and feedback. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
