在 2025/9/8 17:11, Michal Hocko 写道:
> On Mon 08-09-25 16:16:38, Jinjiang Tu wrote:
>> 在 2025/9/8 15:46, Michal Hocko 写道:
>>> On Sat 06-09-25 09:56:16, Jinjiang Tu wrote:
>>>> In our use case, movable nodes are in all cpusets, so that movable nodes can be
>>>> used by all tasks. Even though we move tasks into cpusets that only allow to allocate
>>>> from movable nodes, oom_cpuset_eligible()->cpuset_mems_allowed_intersects() returns true for
>>>> all tasks.
>>> Right but this is because you allowed _all_ tasks to allocate from those
>>> movable nodes so why would that be an unexpected behavior?
>>>
>>>> Maybe when oc->nodemask == movable nodes, only select tasks whose mempolicy intersects with oc->nodemask.
>>>> Like the following:
>>>>
>>>> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
>>>> index eb83cff7db8c..e56b6de836a6 100644
>>>> --- a/mm/mempolicy.c
>>>> +++ b/mm/mempolicy.c
>>>> @@ -2328,6 +2328,9 @@ bool mempolicy_in_oom_domain(struct task_struct *tsk,
>>>>           if (!mask)
>>>>                   return ret;
>>>> +       if (!nodes_intersects(*oc->nodemask, node_states[N_CPU]))
>>>> +               ret = false;
>>>> +
>>> Nope, this doesn't really make much sense TBH. I believe you should stop
>>> special casing cpuless nodes and look into the actual configuration and
>>> check how to make cpuset based OOM tasks selection. Your underlying
>>> problem is not about no CPUs assigned to a numa node but an allocation
>>> constrain based on movability of allocations so you need to find a
>>> solution that is dealing with that constrain.
>> Many tasks are in the root cpuset, systemd for example. The root cpuset
>> contains all nodes, we couldn't exclude cpu-less nodes.
>>
>> If we reply on cpuset based OOM tasks selection, tasks in root cpuset may
>> still be selected.
> If you start by killing tasks from the cpuset of the currently
> allocating task then this shouldn't really happen, right?

Yes, indeed.