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    Subject[patch 2/4] mm: page_alloc: generalize order handling in __free_pages_bootmem()
    Date
    __free_pages_bootmem() used to special-case higher-order frees to save
    individual page checking with free_pages_bulk().

    Nowadays, both zero order and non-zero order frees use free_pages(),
    which checks each individual page anyway, and so there is little point
    in making the distinction anymore. The higher-order loop will work
    just fine for zero order pages.

    Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
    ---
    mm/page_alloc.c | 34 ++++++++++++----------------------
    1 files changed, 12 insertions(+), 22 deletions(-)

    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 4d5e91c..1efacb3 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -692,33 +692,23 @@ static void __free_pages_ok(struct page *page, unsigned int order)
    local_irq_restore(flags);
    }

    -/*
    - * permit the bootmem allocator to evade page validation on high-order frees
    - */
    void __meminit __free_pages_bootmem(struct page *page, unsigned int order)
    {
    - if (order == 0) {
    - __ClearPageReserved(page);
    - set_page_count(page, 0);
    - set_page_refcounted(page);
    - __free_page(page);
    - } else {
    - unsigned int nr_pages = 1 << order;
    - unsigned int loop;
    -
    - prefetchw(page);
    - for (loop = 0; loop < nr_pages; loop++) {
    - struct page *p = &page[loop];
    + unsigned int nr_pages = 1 << order;
    + unsigned int loop;

    - if (loop + 1 < nr_pages)
    - prefetchw(p + 1);
    - __ClearPageReserved(p);
    - set_page_count(p, 0);
    - }
    + prefetchw(page);
    + for (loop = 0; loop < nr_pages; loop++) {
    + struct page *p = &page[loop];

    - set_page_refcounted(page);
    - __free_pages(page, order);
    + if (loop + 1 < nr_pages)
    + prefetchw(p + 1);
    + __ClearPageReserved(p);
    + set_page_count(p, 0);
    }
    +
    + set_page_refcounted(page);
    + __free_pages(page, order);
    }


    --
    1.7.7.3


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