Re: [PATCH] mm, oom: distinguish blockable mode for mmu notifiers

[Andrew Morton]

On Tue, 17 Jul 2018 10:12:01 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote:

> > Any suggestions regarding how the driver developers can test this code
> > path?  I don't think we presently have a way to fake an oom-killing
> > event?  Perhaps we should add such a thing, given the problems we're
> > having with that feature.
> 
> The simplest way is to wrap an userspace code which uses these notifiers
> into a memcg and set the hard limit to hit the oom. This can be done
> e.g. after the test faults in all the mmu notifier managed memory and
> set the hard limit to something really small. Then we are looking for a
> proper process tear down.

Chances are, some of the intended audience don't know how to do this
and will either have to hunt down a lot of documentation or will just
not test it.  But we want them to test it, so a little worked step-by-step
example would help things along please.