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    Subject[PATCH net-next -v5 3/4] mm: introduce __get_page() and __put_page()
    Date
    Introduce __get_page() and __put_page() to operate on the
    base page or head of a compound page for the cases when a
    page is known to be a base page or head of a compound page.

    Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
    ---
    include/linux/mm.h | 21 ++++++++++++++-------
    mm/swap.c | 6 +++---
    2 files changed, 17 insertions(+), 10 deletions(-)

    diff --git a/include/linux/mm.h b/include/linux/mm.h
    index 73a52aba448f..5683313c3e9d 100644
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -902,7 +902,7 @@ static inline struct page *virt_to_head_page(const void *x)
    return compound_head(page);
    }

    -void __put_page(struct page *page);
    +void __put_single_or_compound_page(struct page *page);

    void put_pages_list(struct list_head *pages);

    @@ -1203,9 +1203,8 @@ static inline bool is_pci_p2pdma_page(const struct page *page)
    #define page_ref_zero_or_close_to_overflow(page) \
    ((unsigned int) page_ref_count(page) + 127u <= 127u)

    -static inline void get_page(struct page *page)
    +static inline void __get_page(struct page *page)
    {
    - page = compound_head(page);
    /*
    * Getting a normal page or the head of a compound page
    * requires to already have an elevated page->_refcount.
    @@ -1214,6 +1213,11 @@ static inline void get_page(struct page *page)
    page_ref_inc(page);
    }

    +static inline void get_page(struct page *page)
    +{
    + __get_page(compound_head(page));
    +}
    +
    bool __must_check try_grab_page(struct page *page, unsigned int flags);
    struct page *try_grab_compound_head(struct page *page, int refs,
    unsigned int flags);
    @@ -1228,10 +1232,8 @@ static inline __must_check bool try_get_page(struct page *page)
    return true;
    }

    -static inline void put_page(struct page *page)
    +static inline void __put_page(struct page *page)
    {
    - page = compound_head(page);
    -
    /*
    * For devmap managed pages we need to catch refcount transition from
    * 2 to 1, when refcount reach one it means the page is free and we
    @@ -1244,7 +1246,12 @@ static inline void put_page(struct page *page)
    }

    if (put_page_testzero(page))
    - __put_page(page);
    + __put_single_or_compound_page(page);
    +}
    +
    +static inline void put_page(struct page *page)
    +{
    + __put_page(compound_head(page));
    }

    /*
    diff --git a/mm/swap.c b/mm/swap.c
    index af3cad4e5378..565cbde1caea 100644
    --- a/mm/swap.c
    +++ b/mm/swap.c
    @@ -111,7 +111,7 @@ static void __put_compound_page(struct page *page)
    destroy_compound_page(page);
    }

    -void __put_page(struct page *page)
    +void __put_single_or_compound_page(struct page *page)
    {
    if (is_zone_device_page(page)) {
    put_dev_pagemap(page->pgmap);
    @@ -128,7 +128,7 @@ void __put_page(struct page *page)
    else
    __put_single_page(page);
    }
    -EXPORT_SYMBOL(__put_page);
    +EXPORT_SYMBOL(__put_single_or_compound_page);

    /**
    * put_pages_list() - release a list of pages
    @@ -1153,7 +1153,7 @@ void put_devmap_managed_page(struct page *page)
    if (count == 1)
    free_devmap_managed_page(page);
    else if (!count)
    - __put_page(page);
    + __put_single_or_compound_page(page);
    }
    EXPORT_SYMBOL(put_devmap_managed_page);
    #endif
    --
    2.33.0
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