linux-kernel - Re: [PATCH v2 16/28] mm: Remove page_cache_add_speculative() and page_cache_get

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Message-ID: <0babe6ec-19d7-715b-4b0c-e476922434f5@nvidia.com>
Date:   Mon, 10 Jan 2022 21:14:10 -0800
From:   John Hubbard <jhubbard@...dia.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>, linux-mm@...ck.org
Cc:     Christoph Hellwig <hch@...radead.org>,
        William Kucharski <william.kucharski@...cle.com>,
        linux-kernel@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH v2 16/28] mm: Remove page_cache_add_speculative() and
 page_cache_get_speculative()

On 1/9/22 20:23, Matthew Wilcox (Oracle) wrote:
> These wrappers have no more callers, so delete them.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
>   include/linux/mm.h      |  7 +++----
>   include/linux/pagemap.h | 11 -----------
>   2 files changed, 3 insertions(+), 15 deletions(-)

Confirmed that at this point in the series there are no more callers.

Reviewed-by: John Hubbard <jhubbard@...dia.com>


thanks,
-- 
John Hubbard
NVIDIA

> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index d3769897c8ac..b249156f7cf1 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1291,10 +1291,9 @@ static inline void put_page(struct page *page)
>    * applications that don't have huge page reference counts, this won't be an
>    * issue.
>    *
> - * Locking: the lockless algorithm described in page_cache_get_speculative()
> - * and page_cache_gup_pin_speculative() provides safe operation for
> - * get_user_pages and page_mkclean and other calls that race to set up page
> - * table entries.
> + * Locking: the lockless algorithm described in folio_try_get_rcu()
> + * provides safe operation for get_user_pages(), page_mkclean() and
> + * other calls that race to set up page table entries.
>    */
>   #define GUP_PIN_COUNTING_BIAS (1U << 10)
>   
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 704cb1b4b15d..4a63176b6417 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -283,17 +283,6 @@ static inline struct inode *folio_inode(struct folio *folio)
>   	return folio->mapping->host;
>   }
>   
> -static inline bool page_cache_add_speculative(struct page *page, int count)
> -{
> -	VM_BUG_ON_PAGE(PageTail(page), page);
> -	return folio_ref_try_add_rcu((struct folio *)page, count);
> -}
> -
> -static inline bool page_cache_get_speculative(struct page *page)
> -{
> -	return page_cache_add_speculative(page, 1);
> -}
> -
>   /**
>    * folio_attach_private - Attach private data to a folio.
>    * @folio: Folio to attach data to.