Allocation of a hugetlb page for the hugetlb pool is done by the routine
alloc_pool_huge_page.  This routine will allocate contiguous pages from a
low level allocator, prep the pages for usage as a hugetlb page and then
add the resulting hugetlb page to the pool.

In the 'prep' stage, optional vmemmap optimization is done.  For
performance reasons we want to perform vmemmap optimization on multiple
hugetlb pages at once.  To do this, restructure the hugetlb pool
allocation code such that vmemmap optimization can be isolated and later
batched.

The code to allocate hugetlb pages from bootmem was also modified to
allow batching.

No functional changes, only code restructure.

Link: https://lkml.kernel.org/r/20231019023113.345257-3-mike.kravetz@oracle.comSigned-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Konrad Dybcio <konradybcio@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Usama Arif <usama.arif@bytedance.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>