Re: [v7 5/5] mm, oom: cgroup v2 mount option to disable cgroup-aware OOM killer

[Roman Gushchin]

On Thu, Sep 07, 2017 at 10:03:24AM -0500, Christopher Lameter wrote:
> On Thu, 7 Sep 2017, Roman Gushchin wrote:
> 
> > > Really? From what I know and worked on way back when: The reason was to be
> > > able to contain the affected application in a cpuset. Multiple apps may
> > > have been running in multiple cpusets on a large NUMA machine and the OOM
> > > condition in one cpuset should not affect the other. It also helped to
> > > isolate the application behavior causing the oom in numerous cases.
> > >
> > > Doesnt this requirement transfer to cgroups in the same way?
> >
> > We have per-node memory stats and plan to use them during the OOM victim
> > selection. Hopefully it can help.
> 
> One of the OOM causes could be that memory was restricted to a certain
> node set. Killing the allocating task is (was?) default behavior in that
> case so that the task that has the restrictions is killed. Not any task
> that may not have the restrictions and woiuld not experience OOM.

As I can see, it's not the default behavior these days. If we have a way
to select a victim between memcgs/tasks which are actually using
the corresponding type of memory, it's much better than to kill
an allocating task.