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

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Thu, Aug 28, 2025 at 02:57:03PM +0800, Yafang Shao wrote:
> On Wed, Aug 27, 2025 at 11:34 PM Lorenzo Stoakes
> <lorenzo.stoakes@oracle.com> wrote:
> >
> > +cc cgroup people, please do include them on this stuff.
>
> sure.

Be good to cc on future respins for the whole series also! :) just so everybody
is in the loop, thanks!

>
> >
> > BTW I see there is a BPF [STORAGE & CGROUPS] section in MAINTAINERS and
> > kernel/bpf/cgroup.c etc. anything useful there for us?
>
> BPF local storage can assist in implementing this feature. However, we
> still need to introduce a new helper, bpf_mm_get_mem_cgroup(), to
> retrieve the mem_cgroup from an mm_struct.
>
> >
> > 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.
> >
> > What locking guarantees do we have that this is all fine?
>
> As explained by Shakeel,  no locking is needed for this stuff.

Thanks, I responded there.

>
> >
> > >
> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > > ---
> > >  mm/bpf_thp.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> >
> > Also not to be nitty (but I'm going to be anyway :P) but I'm not in love with
> > the filename here.
> >
> > So now we have
> >
> > - khugepaged.c
> > - huge_memory.c
> > - bpf_thp.c
> >
> > Let's maybe call it huge_memory_bpf.c for consistency?
>
> makes sense.
>
> > And obv as mentioned
> > before, add it to the MAINTAINERS in the THP section plz.
>
> will do it.

Thank you on both! :)

>
>
> --
> Regards
> Yafang

Cheers, Lorenzo