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

[Alexei Starovoitov]

On Sun, Feb 1, 2026 at 9:39 PM Matt Bobrowski <mattbobrowski@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxx>
> > Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
> > ---
> >  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.

+1
there is no need for this kfunc.