Re: [PATCH v2] mm, memcg: avoid oom if cgroup is not populated

[Yafang Shao <laoar.shao@gmail.com>]

On Wed, Nov 27, 2019 at 7:41 PM Michal Hocko <mhocko@kernel.org> wrote:
>
> On Wed 27-11-19 12:11:24, David Hildenbrand wrote:
> [...]
> > 4. This patch on its own (if there are no processes, there is nothing to
> > kill) does not sound too wrong to me. Instead of an endless loop
> > (besides signals) where we can't make any progress, we exit right away.
>
> mem_cgroup_out_of_memory returns false when there is no oom victim
> selected and then we break out.
>
> My main objection to the patch is that it adds a subtle inconsitency.

I don't want to argue inconsitency or consitency with you.

> Admins are simply not going to see that the memcg was OOM due to the
> limit change and OOM killer cannot do anything about that.

Printing something like "OOM and no tasks" can esily fix this issue,
if you insist that we should print something.
You can ignore my feedback if you would like to.

> No tasks vs.
> no killable task doesn't make any real difference. There is simply no
> way to get out of that situation.

Well, I don't want to argue with you again.

Thanks
Yafang