mm/dynamic_hugetlb: fix compound_nr incorrect

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I641XX


CVE: NA

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Patch 1378a5ee ("mm: store compound_nr as well as compound_order") add
a new member compound_nr in struct page, and use this new member insteal
of compound_order in hugetlb_cgroup_move_parent() to compute the nr_pages.

In free_hugepage_to_hugetlb(), we reset page->mapping to NULL for each
subpage. Since page->mapping and page->compound_nr is union, we reset
page->compound_nr too unexpectly. This will finally result the nr_pages
incorrect in hugetlb_cgroup_move_parent() and can't release hugetlb_cgroup.

Fix this problem by reset page->compound_nr using set_compound_order().

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