linux-kernel - Re: [PATCH] mm/thp: Rename TRANSPARENT_HUGEPAGE_NEVER_DAX to

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Message-ID: <83625129-26c9-8885-7367-bb56bc5367f3@redhat.com>
Date:   Thu, 16 Mar 2023 15:57:12 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Yang Shi <shy828301@...il.com>
Subject: Re: [PATCH] mm/thp: Rename TRANSPARENT_HUGEPAGE_NEVER_DAX to
 _UNSUPPORTED

On 15.03.23 18:16, Peter Xu 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.
> 
> Cc: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>
> Cc: Yang Shi <shy828301@...il.com>
> Signed-off-by: Peter Xu <peterx@...hat.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_fault *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, unsigned 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_UNSUPPORTED))
>   		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.


We should also fixup that comment then, no?

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb