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    Subject[PATCH/RFC] Add helper for allocating and freeing discontiguous page array.
    Date
    Hi Andrew,

    you suggested this helper and so I implemented it :-)
    Diff is against Linus' current git. Compile tested with allyesconfig.
    Checked with checkpatch.

    Best Regards

    Ingo Oeser

    Signed-off-by: Ingo Oeser <ioe-lkml@rameria.de>
    ---
    include/linux/gfp.h | 2 ++
    mm/page_alloc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
    2 files changed, 50 insertions(+), 0 deletions(-)

    diff --git a/include/linux/gfp.h b/include/linux/gfp.h
    index e8003af..0e2453a 100644
    --- a/include/linux/gfp.h
    +++ b/include/linux/gfp.h
    @@ -249,5 +249,7 @@ void page_alloc_init(void);
    void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
    void drain_all_pages(void);
    void drain_local_pages(void *dummy);
    +int alloc_page_array(struct page **pages, unsigned int count, gfp_t gfp_mask);
    +void free_page_array(struct page **pages, unsigned int count);

    #endif /* __LINUX_GFP_H */
    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 27b8681..459e4bb 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -1757,6 +1757,54 @@ void free_pages_exact(void *virt, size_t size)
    }
    EXPORT_SYMBOL(free_pages_exact);

    +
    +/**
    + * free_page_array - free a number of physically non-contiguous pages.
    + * @pages: the array for pages to free
    + * @count: the number of pages to free
    + */
    +void free_page_array(struct page **pages, unsigned int count)
    +{
    + unsigned int i;
    +
    + for (i = 0; i < count; ++i) {
    + if (pages[i])
    + __free_page(pages[i]);
    + }
    +}
    +EXPORT_SYMBOL_GPL(free_page_array);
    +
    +/**
    + * alloc_page_array - allocate a number of physically non-contiguous pages.
    + * @pages: the array for pages to allocate into
    + * @count: the number of pages to allocate
    + * @gfp_mask: GFP flags for the allocation
    + *
    + * alloc_page_array can satisfy any number of pages.
    + *
    + * NOTE: The array of pages in pages is NOT physically or virtually contiguous!
    + * Use alloc_pages or similiar for physically contiguous pages or vmalloc
    + * and friends for virtually contiguous pages.
    + *
    + * Memory allocated by this function can be release via free_page_array.
    + *
    + * Returns 0 on success and %-ENOMEM on failure.
    + */
    +int alloc_page_array(struct page **pages, unsigned int count, gfp_t gfp_mask)
    +{
    + unsigned int i;
    +
    + for (i = 0; i < count; ++i) {
    + pages[i] = alloc_page(gfp_mask);
    + if (!pages[i] && i > 0) {
    + free_page_array(pages, i);
    + return -ENOMEM;
    + }
    + }
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(alloc_page_array);
    +
    static unsigned int nr_free_zone_pages(int offset)
    {
    struct zoneref *z;
    --
    1.5.4.3


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