Re: [PATCH] fs, mm: account filp and names caches to kmemcg

[Johannes Weiner <hannes@cmpxchg.org>]

On Fri, Oct 13, 2017 at 08:35:55AM +0200, Michal Hocko wrote:
> On Thu 12-10-17 15:03:12, Johannes Weiner wrote:
> > All I'm saying is that, when the syscall-context fails to charge, we
> > should do mem_cgroup_oom() to set up the async OOM killer, let the
> > charge succeed over the hard limit - since the OOM killer will most
> > likely get us back below the limit - then mem_cgroup_oom_synchronize()
> > before the syscall returns to userspace.
> 
> OK, then we are on the same page now. Your initial wording didn't
> mention async OOM killer. This makes more sense. Although I would argue
> that we can retry the charge as long as out_of_memory finds a victim.
> This would return ENOMEM to the pathological cases where no victims
> could be found.

I think that's much worse because it's even harder to test and verify
your applications against.

If syscalls can return -ENOMEM on OOM, they should do so reliably.