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References: <20230315171642.1244625-1-peterx@redhat.com>
In-Reply-To: <20230315171642.1244625-1-peterx@redhat.com>
From:   Yang Shi <shy828301@gmail.com>
Date:   Wed, 15 Mar 2023 14:06:27 -0700
Message-ID: <CAHbLzkrUMztboKPKsbDjiiJDRuY6bTmix64Te_cXezE-ugxvog@mail.gmail.com>
Subject: Re: [PATCH] mm/thp: Rename TRANSPARENT_HUGEPAGE_NEVER_DAX to _UNSUPPORTED
To:     Peter Xu <peterx@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
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On Wed, Mar 15, 2023 at 10:16=E2=80=AFAM Peter Xu <peterx@redhat.com> wrote=
:
>
> TRANSPARENT_HUGEPAGE_NEVER_DAX has nothing to do with DAX.  It's set when
> has_transparent_hugepage() returns false, checked in hugepage_vma_check()
> and will disable THP completely if false.  Rename it to reflect its real
> purpose.

Makes sense to me. Reviewed-by: Yang Shi <shy828301@gmail.com>

>
> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  include/linux/huge_mm.h | 2 +-
>  mm/huge_memory.c        | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 70bd867eba94..9a3a3af2dd80 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -79,7 +79,7 @@ static inline vm_fault_t vmf_insert_pfn_pud(struct vm_f=
ault *vmf, pfn_t pfn,
>  }
>
>  enum transparent_hugepage_flag {
> -       TRANSPARENT_HUGEPAGE_NEVER_DAX,
> +       TRANSPARENT_HUGEPAGE_UNSUPPORTED,
>         TRANSPARENT_HUGEPAGE_FLAG,
>         TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
>         TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index b0ab247939e0..913e7dc32869 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -88,7 +88,7 @@ bool hugepage_vma_check(struct vm_area_struct *vma, uns=
igned long vm_flags,
>         /*
>          * If the hardware/firmware marked hugepage support disabled.
>          */
> -       if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER=
_DAX))
> +       if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUP=
PORTED))
>                 return false;
>
>         /* khugepaged doesn't collapse DAX vma, but page fault is fine. *=
/
> @@ -464,7 +464,7 @@ static int __init hugepage_init(void)
>                  * Hardware doesn't support hugepages, hence disable
>                  * DAX PMD support.
>                  */
> -               transparent_hugepage_flags =3D 1 << TRANSPARENT_HUGEPAGE_=
NEVER_DAX;
> +               transparent_hugepage_flags =3D 1 << TRANSPARENT_HUGEPAGE_=
UNSUPPORTED;
>                 return -EINVAL;
>         }
>
> --
> 2.39.1
>