Re: [PATCH v2 15/23] mm: introduce bpf_task_is_oom_victim() kfunc

Tejun Heo
2025-10-28T17:32:55Z

On Mon, Oct 27, 2025 at 04:21:58PM -0700, Roman Gushchin wrote:
> Export tsk_is_oom_victim() helper as a BPF kfunc.
> It's very useful to avoid redundant oom kills.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
> ---
> mm/oom_kill.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 72a346261c79..90bb86dee3cf 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -1397,11 +1397,25 @@ __bpf_kfunc int bpf_out_of_memory(struct mem_cgroup *memcg__nullable,
> return ret;
> }
>
> +/**
> + * bpf_task_is_oom_victim - Check if the task has been marked as an OOM victim
> + * @task: task to check
> + *
> + * Returns true if the task has been previously selected by the OOM killer
> + * to be killed. It's expected that the task will be destroyed soon and some
> + * memory will be freed, so maybe no additional actions required.
> + */
> +__bpf_kfunc bool bpf_task_is_oom_victim(struct task_struct *task)
> +{
> + return tsk_is_oom_victim(task);
> +}

In general, I'm not sure it's a good idea to add kfuncs for things which are
trivially accessible. Why can't things like this be provided as BPF helpers?

Thanks.

--
tejun