Re: [PATCH v6 mm-new 02/10] mm: thp: add a new kfunc bpf_mm_get_mem_cgroup()

[Yafang Shao <laoar.shao@gmail.com>]

On Thu, Aug 28, 2025 at 4:46 AM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> On Tue, Aug 26, 2025 at 03:19:40PM +0800, Yafang Shao wrote:
> > We will utilize this new kfunc bpf_mm_get_mem_cgroup() to retrieve the
> > associated mem_cgroup from the given @mm. The obtained mem_cgroup must
> > be released by calling bpf_put_mem_cgroup() as a paired operation.
> >
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > ---
> >  mm/bpf_thp.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 50 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/bpf_thp.c b/mm/bpf_thp.c
> > index fbff3b1bb988..b757e8f425fd 100644
> > --- a/mm/bpf_thp.c
> > +++ b/mm/bpf_thp.c
> > @@ -175,10 +175,59 @@ static struct bpf_struct_ops bpf_bpf_thp_ops = {
> >       .name = "bpf_thp_ops",
> >  };
> >
> > +__bpf_kfunc_start_defs();
> > +
> > +/**
> > + * bpf_mm_get_mem_cgroup - Get the memory cgroup associated with a mm_struct.
> > + * @mm: The mm_struct to query
> > + *
> > + * The obtained mem_cgroup must be released by calling bpf_put_mem_cgroup().
> > + *
> > + * Return: The associated mem_cgroup on success, or NULL on failure. Note that
> > + * this function depends on CONFIG_MEMCG being enabled - it will always return
> > + * NULL if CONFIG_MEMCG is not configured.
> > + */
> > +__bpf_kfunc struct mem_cgroup *bpf_mm_get_mem_cgroup(struct mm_struct *mm)
> > +{
> > +     return get_mem_cgroup_from_mm(mm);
> > +}
> > +
> > +/**
> > + * bpf_put_mem_cgroup - Release a memory cgroup obtained from bpf_mm_get_mem_cgroup()
> > + * @memcg: The memory cgroup to release
> > + */
> > +__bpf_kfunc void bpf_put_mem_cgroup(struct mem_cgroup *memcg)
> > +{
> > +#ifdef CONFIG_MEMCG
> > +     if (!memcg)
> > +             return;
> > +     css_put(&memcg->css);
> > +#endif
>
> Just use mem_cgroup_put() here.

i will change it and thanks for the clarification.

-- 
Regards
Yafang