sparc64: Fix hugepage page table free

Make sure the start adderess is aligned to PMD_SIZE
boundary when freeing page table backing a hugepage
region. The issue was causing segfaults when a region
backed by 64K pages was unmapped since such a region
is in general not PMD_SIZE aligned.
Signed-off-by: Nitin Gupta <nitin.m.gupta@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/mm/hugetlbpage.c

@@ -461,6 +461,22 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 	pgd_t *pgd;
 	unsigned long next;
 
+	addr &= PMD_MASK;
+	if (addr < floor) {
+		addr += PMD_SIZE;
+		if (!addr)
+			return;
+	}
+	if (ceiling) {
+		ceiling &= PMD_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		end -= PMD_SIZE;
+	if (addr > end - 1)
+		return;
+
 	pgd = pgd_offset(tlb->mm, addr);
 	do {
 		next = pgd_addr_end(addr, end);