arm64: mm: Test for pmd_sect() in vmemmap_check_pmd()

Commit 2045a3b ("mm/sparse-vmemmap: generalise vmemmap_populate_hugepages()")
introduces the vmemmap_check_pmd() while does not verify if the entry is a
section mapping, as is already done for Loongarch & X86.
The update includes a check for pmd_sect(). Only if pmd_sect() returns true,
further vmemmap population for the addr is skipped.

Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20250102074047.674156-1-quic_zhenhuah@quicinc.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: Zhenhua Huang

arch/arm64/mm/mmu.c

@@ -1169,7 +1169,8 @@ int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
 				unsigned long addr, unsigned long next)
 {
 	vmemmap_verify((pte_t *)pmdp, node, addr, next);
-	return 1;
+
+	return pmd_sect(READ_ONCE(*pmdp));
 }
 
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,