arm64: mm: hugetlb: add support for free vmemmap pages of HugeTLB

The preparation of supporting freeing vmemmap associated with each
infrastructure is ready, so now we can support it for arm64.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>

arch/arm64/mm/mmu.c

@@ -22,6 +22,7 @@
 #include <linux/io.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
+#include <linux/hugetlb.h>
 
 #include <asm/barrier.h>
 #include <asm/cputype.h>
@@ -1109,6 +1110,10 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 	pmd_t *pmdp;
 
 	WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
+
+	if (is_hugetlb_free_vmemmap_enabled() && !altmap)
+		return vmemmap_populate_basepages(start, end, node, altmap);
+
 	do {
 		next = pmd_addr_end(addr, end);
 

fs/Kconfig

@@ -239,9 +239,9 @@ config HUGETLB_PAGE
 
 config HUGETLB_PAGE_FREE_VMEMMAP
 	def_bool HUGETLB_PAGE
-	depends on X86_64
+	select HAVE_BOOTMEM_INFO_NODE if X86_64
 	depends on SPARSEMEM_VMEMMAP
-	depends on HAVE_BOOTMEM_INFO_NODE
+	depends on X86_64 || ARM64
 
 config MEMFD_CREATE
 	def_bool TMPFS || HUGETLBFS