mm: hugetlb_vmemmap: introduce ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP

The feature of minimizing overhead of struct page associated with each
HugeTLB page is implemented on x86_64, however, the infrastructure of this
feature is already there, we could easily enable it for other
architectures.  Introduce ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP for other
architectures to be easily enabled.  Just select this config if they want
to enable this feature.

Link: https://lkml.kernel.org/r/20220331065640.5777-1-songmuchun@bytedance.comSigned-off-by: Muchun Song <songmuchun@bytedance.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Tested-by: Barry Song <baohua@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/x86/Kconfig

@@ -121,6 +121,7 @@ config X86
 	select ARCH_WANTS_NO_INSTR
 	select ARCH_WANT_GENERAL_HUGETLB
 	select ARCH_WANT_HUGE_PMD_SHARE
+	select ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP	if X86_64
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select ARCH_WANTS_THP_SWAP		if X86_64
 	select ARCH_HAS_PARANOID_L1D_FLUSH

fs/Kconfig

@@ -245,9 +245,17 @@ config HUGETLBFS
 config HUGETLB_PAGE
 	def_bool HUGETLBFS
 
+#
+# Select this config option from the architecture Kconfig, if it is preferred
+# to enable the feature of minimizing overhead of struct page associated with
+# each HugeTLB page.
+#
+config ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP
+	bool
+
 config HUGETLB_PAGE_FREE_VMEMMAP
 	def_bool HUGETLB_PAGE
-	depends on X86_64
+	depends on ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP
 	depends on SPARSEMEM_VMEMMAP
 
 config HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON