Re: [PATCH v2] mm: memcontrol: protect the memory in cgroup from being oom killed

On Thu 08-12-22 11:46:44, chengkaitao wrote:

From: chengkaitao <redacted>

We created a new interface <memory.oom.protect> for memory, If there is
the OOM killer under parent memory cgroup, and the memory usage of a
child cgroup is within its effective oom.protect boundary, the cgroup's
tasks won't be OOM killed unless there is no unprotected tasks in other
children cgroups. It draws on the logic of <memory.min/low> in the
inheritance relationship.

It has the following advantages,
1. We have the ability to protect more important processes, when there
is a memcg's OOM killer. The oom.protect only takes effect local memcg,
and does not affect the OOM killer of the host.
2. Historically, we can often use oom_score_adj to control a group of
processes, It requires that all processes in the cgroup must have a
common parent processes, we have to set the common parent process's
oom_score_adj, before it forks all children processes. So that it is
very difficult to apply it in other situations. Now oom.protect has no
such restrictions, we can protect a cgroup of processes more easily. The
cgroup can keep some memory, even if the OOM killer has to be called.

Signed-off-by: chengkaitao <redacted>
---
v2: Modify the formula of the process request memcg protection quota.

The new formula doesn't really address concerns expressed previously.
Please read my feedback carefully again and follow up with questions if
something is not clear.
-- 
Michal Hocko
SUSE Labs