Re: [PATCH] mm/oom_kill: kill current in OOM when binding to cpu-less nodes

[Michal Hocko <mhocko@suse.com>]

On Thu 04-09-25 16:25:52, Michal Hocko wrote:
> On Thu 04-09-25 21:44:31, Jinjiang Tu wrote:
> > out_of_memory() selects tasks without considering mempolicy. Assuming a
> > cpu-less NUMA Node, ordinary process that don't set mempolicy don't
> > allocate memory from this cpu-less Node, unless other NUMA Nodes are below
> > low watermark. If a task binds to this cpu-less Node and triggers OOM, many
> > tasks may be killed wrongly that don't occupy memory from this Node.
> 
> I can see how a miconfigured task that binds _only_ to memoryless nodes
> should be killed but this is not what the patch does, right?  Could you
> tell us more about the specific situation? 

Now I have realized that I have misread the patch. You are indeed trying
to kill the allocating task only if the allocation nodemask _does_not_
intersect with nodes with CPUs. This is better than I original
understood but still rather ad-hoc heuristic. It doesn't represent the
movability of cpuless nodes and also adds a heuristic that would be
really hard to get rid of later on. As mentioned in other reply I would
recommend looking into using cpusets for this purpose.

-- 
Michal Hocko
SUSE Labs