Re: [PATCH] mm,oom: use per signal_struct flag rather than clear TIF_MEMDIE

[Oleg Nesterov <oleg@redhat.com>]

On 06/28, Michal Hocko wrote:
>
> On Mon 27-06-16 23:09:04, Oleg Nesterov wrote:
> > On 06/27, Michal Hocko wrote:
> > >
> > > Yes this is really unfortunate. I am trying to converge to per mm
> > > behavior as much as possible. We are getting there slowly but not yet
> > > there.
> >
> > Yes, agreed, everything should be per-mm.
> >
> > Say wake_oom_reaper/oom_reap_task. It is simply ugly we pass task_struct
> > to oom_reap_task(), it should work with mm_struct. Again, this is because
> > of TIF_MEMDIE/exit_oom_victim.  Except pr_info(), but this is minor...
>
> I was also tempted to get back to the mm based queing but I think that
> the pr_info is quite useful.

It is, I agree. But this is solveable, I think. If nothing else, we can even
do another for_each_thread() loop and report all tasks which use this mm, or
we can pass pid/mm tuple. Lets discus this later, this is not that important.

> > As for memory reserve access, I feel that we should only set this flag
> > if task == current... but this needs more discussion.
>
> That would certainly be something to discuss. If we have other reliable
> way to detect the oom victim and when it terminates then TIF_MEMDIE on
> the current and only for memory reserves would be viable. Let's see
> whether we can keep the killed mm around and use it as an indicator.
> This would be a natural follow up cleanup.

Agreed, this looks certainly better than what we have now. Although I am
not sure I fully understand the details, but it seems that everything would
be better anyway ;)

Oleg.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>