Re: [PATCH 0/2] mm->owner to mm->memcg fixes

[Eric W. Biederman]

Michal Hocko <mhocko@xxxxxxxxxx> writes:

> On Wed 23-05-18 14:46:43, Eric W. Biederman wrote:
> [...]
>> As two processes sharing an mm is useless and highly unlikely there is
>> no need to handle this case well, it just needs to be handled well
>> enough to prevent an indefinite loop.  So when css_tryget_online fails
>> just treat the mm as belong to the root memory cgroup.
>
> Does that mean that a malicious user can construct such a task and
> runaway from its limits?

Unfortunately if the memory cgroup is delegated than yes that can
happen.  So removing the loop in get_mem_cgroup_from_mm won't work.

Eric