dhugetlb: backport dynamic hugetlb feature

hulk inclusion
category: feature
bugzilla: 46904, https://gitee.com/openeuler/kernel/issues/I6BDME


CVE: NA

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This feature has already beed supported on x86_64 and this is the origin
description:

 Dynamic hugetlb which is based on Hugetlb, supports to be splited
 dynamically in a specified cgroup. We add a hugetlb_pool in a
 mem_cgroup to manage dynamic hugetlb for corresponding cgroup.
 After dynamic hugepages are allocated for a cgroup, these hugepages
 can be used as 1G/2M/4K pages by split/merge opreation.

It is now supported on arm64. This feature will be limited to depends on
ARM64_4K_PAGES and not support cont-bits hugepage. We merge the previous
patches into one patch which is patch[1]. While merge the code ,we found
some code can be isolated by config DYNAMIC_HUGETLB, so we add patch[2] to
re-isolated them. In patch[3], we restrict the feature on mentioned limit.
The patch[4] add skip of dissolve hugepage which may conflict with memory
hotplug and memory failure. The patch[5] set DYNAMIC_HUGETLB to y in
hulk_defconfig to enable by default.

This patch includes all previous patches and the patches list is recorded
in bugzilla.

Signed-off-by: Liu Shixin <liushixin2@hauwei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>