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From:   Mina Almasry <almasrymina@google.com>
Date:   Tue, 28 Jun 2022 13:03:55 -0700
Message-ID: <CAHS8izPt+h59x1em6z7YbKg+u2f1fMyx6EZ0gwSZ_xu7AM6S-g@mail.gmail.com>
Subject: Re: [RFC PATCH 05/26] hugetlb: add CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
To:     "manish.mishra" <manish.mishra@nutanix.com>
Cc:     James Houghton <jthoughton@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Peter Xu <peterx@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Jue Wang <juew@google.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
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On Mon, Jun 27, 2022 at 5:29 AM manish.mishra <manish.mishra@nutanix.com> wrote:
>
>
> On 24/06/22 11:06 pm, James Houghton wrote:
> > This adds the Kconfig to enable or disable high-granularity mapping. It
> > is enabled by default for architectures that use
> > ARCH_WANT_GENERAL_HUGETLB.
> >
> > There is also an arch-specific config ARCH_HAS_SPECIAL_HUGETLB_HGM which
> > controls whether or not the architecture has been updated to support
> > HGM if it doesn't use general HugeTLB.
> >
> > Signed-off-by: James Houghton <jthoughton@google.com>
> reviewed-by:manish.mishra@nutanix.com

Mostly minor nits,

Reviewed-by: Mina Almasry <almasrymina@google.com>

> > ---
> >   fs/Kconfig | 7 +++++++
> >   1 file changed, 7 insertions(+)
> >
> > diff --git a/fs/Kconfig b/fs/Kconfig
> > index 5976eb33535f..d76c7d812656 100644
> > --- a/fs/Kconfig
> > +++ b/fs/Kconfig
> > @@ -268,6 +268,13 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON
> >         to enable optimizing vmemmap pages of HugeTLB by default. It can then
> >         be disabled on the command line via hugetlb_free_vmemmap=off.
> >
> > +config ARCH_HAS_SPECIAL_HUGETLB_HGM

Nit: would have preferred just ARCH_HAS_HUGETLB_HGM, as ARCH implies
arch-specific.

> > +     bool
> > +
> > +config HUGETLB_HIGH_GRANULARITY_MAPPING
> > +     def_bool ARCH_WANT_GENERAL_HUGETLB || ARCH_HAS_SPECIAL_HUGETLB_HGM

Nit: would have preferred to go with either HGM _or_
HIGH_GRANULARITY_MAPPING (or whatever new name comes up), rather than
both, for consistency's sake.

> > +     depends on HUGETLB_PAGE
> > +
> >   config MEMFD_CREATE
> >       def_bool TMPFS || HUGETLBFS
> >