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    Subject[RFC V7 PATCH 13/19] memory-hotplug: check page type in get_page_bootmem
    Date
    From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

    There is a possibility that get_page_bootmem() is called to the same page many
    times. So when get_page_bootmem is called to the same page, the function only
    increments page->_count.

    CC: David Rientjes <rientjes@google.com>
    CC: Jiang Liu <liuj97@gmail.com>
    CC: Len Brown <len.brown@intel.com>
    CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    CC: Paul Mackerras <paulus@samba.org>
    CC: Christoph Lameter <cl@linux.com>
    Cc: Minchan Kim <minchan.kim@gmail.com>
    CC: Andrew Morton <akpm@linux-foundation.org>
    CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    CC: Wen Congyang <wency@cn.fujitsu.com>
    Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
    ---
    mm/memory_hotplug.c | 15 +++++++++++----
    1 files changed, 11 insertions(+), 4 deletions(-)
    diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
    index 5f9f8c7..d85af6d 100644
    --- a/mm/memory_hotplug.c
    +++ b/mm/memory_hotplug.c
    @@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res)
    static void get_page_bootmem(unsigned long info, struct page *page,
    unsigned long type)
    {
    - page->lru.next = (struct list_head *) type;
    - SetPagePrivate(page);
    - set_page_private(page, info);
    - atomic_inc(&page->_count);
    + unsigned long page_type;
    +
    + page_type = (unsigned long) page->lru.next;
    + if (page_type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
    + page_type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE){
    + page->lru.next = (struct list_head *) type;
    + SetPagePrivate(page);
    + set_page_private(page, info);
    + atomic_inc(&page->_count);
    + } else
    + atomic_inc(&page->_count);
    }

    /* reference to __meminit __free_pages_bootmem is valid
    --
    1.7.1


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