On Tue, 14 Jul 2015, Andrew Morton wrote:
> > --- a/include/linux/oom.h
> > +++ b/include/linux/oom.h
> > @@ -12,6 +12,14 @@ struct notifier_block;
> > struct mem_cgroup;
> > struct task_struct;
> >
> > +struct oom_control {
> > + struct zonelist *zonelist;
> > + nodemask_t *nodemask;
> > + gfp_t gfp_mask;
> > + int order;
> > + bool force_kill;
> > +};
>
> Some docs would be nice.
>
Ok!
> gfp_mask and order are what the page-allocating caller originally asked
> for, I think? They haven't been mucked with?
>
Yes, it's a good opportunity to make them const.
> It's somewhat obvious what force_kill does, but why is it provided, why
> is it set? And what does it actually kill? A process which was
> selected based on the other fields...
>
It's removed in the next patch since it's unneeded, so I'll define what
order == -1 means.
> Also, it's a bit odd that zonelist and nodemask are here. They're
> low-level implementation details whereas the other three fields are
> high-level caller control stuff.
>
Zonelist and nodemask are indeed pretty weird here. We use them to
determine if the oom kill is constrained by cpuset and/or mempolicy,
respectively so we don't kill things unnecessarily and leave a cpuset
still oom, for example. We could determine that before actually calling
the oom killer and passing the enum oom_constraint in, but its purpose is
for the oom killer so it's just a part of that logical unit.
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