Re: [RFC 1/6] mm, page_alloc: fix more premature OOM due to race with cpuset update

Michal Hocko
2017-05-18T09:08:47Z

On Wed 17-05-17 10:25:09, Cristopher Lameter wrote:
> On Wed, 17 May 2017, Michal Hocko wrote:
>
> > > If you have screwy things like static mbinds in there then you are
> > > hopelessly lost anyways. You may have moved the process to another set
> > > of nodes but the static bindings may refer to a node no longer
> > > available. Thus the OOM is legitimate.
> >
> > The point is that you do _not_ want such a process to trigger the OOM
> > because it can cause other processes being killed.
>
> Nope. The OOM in a cpuset gets the process doing the alloc killed. Or what
> that changed?
>
> At this point you have messed up royally and nothing is going to rescue
> you anyways. OOM or not does not matter anymore. The app will fail.

Not really. If you can trick the system to _think_ that the intersection
between mempolicy and the cpuset is empty then the OOM killer might
trigger an innocent task rather than the one which tricked it into that
situation.
--
Michal Hocko
SUSE Labs