Re: [RFC PATCH] mm, oom: introduce vm.sacrifice_hugepage_on_oom

[Chris Down]

Eiichi Tsukata writes:
> > > But that comes with a challenge: despite listening on cgroup for
> > > pressure notifications (which happen from those runtime events we do
> > > not control),
> >
> > We do also have global pressure (PSI) counters. Have you tried to look
> > into those and try to back off even when the situation becomes critical?
>
> Yes. PSI counters help us to some extent. But we've found that in some cases
> OOM can happen before we observe memory pressure if memory bloat occurred
> rapidly. The proposed failsafe mechanism can cover even such a situation.
> Also, as I mentioned in commit message, oom notifiers doesn't work if OOM
> is triggered by memory allocation for kernel.

Hmm, do you have free swap? Without it, we can trivially go from fine to OOM in 
a totally binary fashion. As long as there's some swap space available, there 
should be a clear period where pressure is rising prior to OOM.