mm/dynamic_hugetlb: check free_pages_prepares when split pages

hulk inclusion
category: bugfix
bugzilla: 46904 https://gitee.com/openeuler/kernel/issues/I4Y0XO



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The hugepages may still remain PG_uptodate flags when freed. When splitting
hugepage to pages, the flag is not clear. This causes the page to be allocated
with PG_uptodate flags and user may read incorrect datas.

In order to solve this problem and similar problems, add free_pages_prepares()
to clear page when splitting pages to small pool.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>