Re: [PATCH bpf-next v3 10/17] mm: introduce bpf_task_is_oom_victim() kfunc

[Matt Bobrowski <mattbobrowski@google.com>]

On Mon, Jan 26, 2026 at 06:44:13PM -0800, 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>
> Suggested-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/oom_kill.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 8f63a370b8f5..53f9f9674658 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -1381,10 +1381,24 @@ __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);
> +}

Why not just do a direct memory read (i.e., task->signal->oom_mm)
within the BPF program? I'm not quite convinced that a BPF kfunc
wrapper for something like tsk_is_oom_victim() is warranted as you can
literally achieve the same semantics without one.