From: David Hildenbrand <david@redhat.com>
To: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>, linux-mm@kvack.org
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH mm-unstable v2 1/6] mm: Add folio_estimated_mapcount()
Date: Wed, 25 Jan 2023 11:20:03 +0100 [thread overview]
Message-ID: <477bbc1e-a60a-cfce-d31e-0b4bdd5f6429@redhat.com> (raw)
In-Reply-To: <20230124012210.13963-2-vishal.moola@gmail.com>
On 24.01.23 02:22, Vishal Moola (Oracle) wrote:
> folio_estimated_mapcount() takes in a folio and calls page_mapcount() on
> the first page of that folio.
>
> This is necessary for folio conversions where we only care about either the
> entire_mapcount of a large folio, or the mapcount of a not large folio.
>
> This is in contrast to folio_mapcount() which calculates the total
> number of the times a folio and its subpages are mapped.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
> include/linux/mm.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c9db257f09b3..543c360f7ecc 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -875,6 +875,11 @@ static inline int page_mapcount(struct page *page)
> return mapcount;
> }
>
> +static inline int folio_estimated_mapcount(struct folio *folio)
> +{
> + return page_mapcount(folio_page(folio, 0));
> +}
> +
> int folio_total_mapcount(struct folio *folio);
>
> /**
I'm sorry, but "estimated" as absolutely unclear semantics. You could
have a THP mapped into 9999 processes using THP and the estimation would
be "0".
Huh? Absolutely unclear and confusing. No thanks.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2023-01-25 10:20 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-24 1:22 [PATCH mm-unstable v2 0/6] Convert various mempolicy.c functions Vishal Moola (Oracle)
2023-01-24 1:22 ` [PATCH mm-unstable v2 1/6] mm: Add folio_estimated_mapcount() Vishal Moola (Oracle)
2023-01-24 3:23 ` kernel test robot
2023-01-25 10:20 ` David Hildenbrand [this message]
2023-01-25 10:24 ` David Hildenbrand
2023-01-25 21:29 ` David Hildenbrand
2023-01-25 22:09 ` Vishal Moola
2023-01-26 8:37 ` David Hildenbrand
2023-01-28 0:48 ` Jane Chu
2023-01-30 9:34 ` David Hildenbrand
2023-01-28 13:20 ` Yin, Fengwei
2023-01-24 1:22 ` [PATCH mm-unstable v2 2/6] mm/mempolicy: Convert queue_pages_pmd() to queue_folios_pmd() Vishal Moola (Oracle)
2023-01-24 1:22 ` [PATCH mm-unstable v2 3/6] mm/mempolicy: Convert queue_pages_pte_range() to queue_folios_pte_range() Vishal Moola (Oracle)
2023-01-24 1:22 ` [PATCH mm-unstable v2 4/6] mm/mempolicy: Convert queue_pages_hugetlb() to queue_folios_hugetlb() Vishal Moola (Oracle)
2023-01-24 1:22 ` [PATCH mm-unstable v2 5/6] mm/mempolicy: Convert queue_pages_required() to queue_folio_required() Vishal Moola (Oracle)
2023-01-24 1:22 ` [PATCH mm-unstable v2 6/6] mm/mempolicy: Convert migrate_page_add() to migrate_folio_add() Vishal Moola (Oracle)
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