mm: hugetlb: fix type of delta parameter and related local variables in gather_surplus_pages()

On 64-bit machine, delta variable in hugetlb_acct_memory() may be larger
than 0xffffffff, but gather_surplus_pages() can only use the low 32-bit
value now.  So we need to fix type of delta parameter and related local
variables in gather_surplus_pages().

Link: https://lkml.kernel.org/r/1605793733-3573-1-git-send-email-liu.xiang@zlingsmart.comReported-by: Ma Chenggong <ma.chenggong@zlingsmart.com>
Signed-off-by: Liu Xiang <liu.xiang@zlingsmart.com>
Signed-off-by: Pan Jiagen <pan.jiagen@zlingsmart.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Liu Xiang <liuxiang_1999@126.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -1944,13 +1944,14 @@ struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
  * Increase the hugetlb pool such that it can accommodate a reservation
  * of size 'delta'.
  */
-static int gather_surplus_pages(struct hstate *h, int delta)
+static int gather_surplus_pages(struct hstate *h, long delta)
 	__must_hold(&hugetlb_lock)
 {
 	struct list_head surplus_list;
 	struct page *page, *tmp;
-	int ret, i;
-	int needed, allocated;
+	int ret;
+	long i;
+	long needed, allocated;
 	bool alloc_ok = true;
 
 	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;