[PATCH] mm/mmap.c: silence variable 'new_start' set but not used

[YueHaibing <yuehaibing@huawei.com>]

'new_start' is used in is_hugepage_only_range(),
which do nothing in some arch. gcc will warning:

mm/mmap.c: In function acct_stack_growth:
mm/mmap.c:2311:16: warning: variable new_start set but not used [-Wunused-but-set-variable]

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index e2dbed3..56c2a92 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2308,7 +2308,7 @@ static int acct_stack_growth(struct vm_area_struct *vma,
 			     unsigned long size, unsigned long grow)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	unsigned long new_start;
+	unsigned long __maybe_unused new_start;
 
 	/* address space limit tests */
 	if (!may_expand_vm(mm, vma->vm_flags, grow))
-- 
2.7.4