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From:   Liam Howlett <liam.howlett@oracle.com>
To:     Suren Baghdasaryan <surenb@google.com>
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Subject: Re: [PATCH v10 1/3] mm: rearrange madvise code to allow for reuse
Thread-Topic: [PATCH v10 1/3] mm: rearrange madvise code to allow for reuse
Thread-Index: AQHXtwbqRHUtflHT6EeCVViEJ7Fas6vCbdyAgACa+ACAAeENgIAACJcAgAFP6QA=
Date:   Wed, 6 Oct 2021 17:33:12 +0000
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* Suren Baghdasaryan <surenb@google.com> [211005 17:31]:
> On Tue, Oct 5, 2021 at 2:00 PM Liam Howlett <liam.howlett@oracle.com> wro=
te:
> >
> > * Suren Baghdasaryan <surenb@google.com> [211004 12:18]:
> > > On Mon, Oct 4, 2021 at 12:03 AM Rolf Eike Beer <eb@emlix.com> wrote:
> > > >
> > > > > --- a/mm/madvise.c
> > > > > +++ b/mm/madvise.c
> > > > > @@ -63,76 +63,20 @@ static int madvise_need_mmap_write(int behavi=
or)
> > > > >  }
> > > > >
> > > > >  /*
> > > > > - * We can potentially split a vm area into separate
> > > > > - * areas, each area with its own behavior.
> > > > > + * Update the vm_flags on regiion of a vma, splitting it or merg=
ing it as
> > > >                                 ^^
> > >
> > > Thanks! Will fix in the next version.
> >
> > Since you'll be respinning for this comment, can you please point out
> > that the split will keep the VMA as [vma->vm_start, new_end)?  That is,
> > __split_vma() is passed 0 for new_below.  It might prove useful since
> > the code is being reused.
>=20
> Hmm. There are two cases here:
>=20
>         if (start !=3D vma->vm_start) {
>                 ...
>                 error =3D __split_vma(mm, vma, start, 1);
>         }
>=20
> and
>=20
>         if (end !=3D vma->vm_end) {
>                 ...
>                 error =3D __split_vma(mm, vma, end, 0);
>         }
>=20
> so, I don't think such a comment would be completely correct, no?

Yes, you are correct.  I'm not sure how I missed that.

Thanks,
Liam=