Merge Pull Request from: @zhengzengkai 
 
Some applications has large code and data segment, and this causes high
TLB miss when page size is 4K. Mapping these apps into hugetlbfs will
boost their performance. A userspace tool libhugetlbfs can do this but
it seems to stopped development since 2020, and it does not support
debugging.
Tmpfs supports transparent hugepage, but it will be split into small
pages during copy-on-write. Userspace hotpatch will do mprotect on code
segment and trigger pmd split, and some users think performance
degradation after hotpatch is unacceptable.
This patch set implements hugetlb support in exec, and solved the
debugging issue. 
 
Link:https://gitee.com/openeuler/kernel/pulls/59 
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> 
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>