mm/hugetlb: optimize the surplus state transfer code in move_hugetlb_state()

We should not transfer the per-node surplus state when we do not cross the
node in order to save some cpu cycles

Link: https://lkml.kernel.org/r/20210308112809.26107-3-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -5682,6 +5682,12 @@ void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
 		SetHPageTemporary(oldpage);
 		ClearHPageTemporary(newpage);
 
+		/*
+		 * There is no need to transfer the per-node surplus state
+		 * when we do not cross the node.
+		 */
+		if (new_nid == old_nid)
+			return;
 		spin_lock(&hugetlb_lock);
 		if (h->surplus_huge_pages_node[old_nid]) {
 			h->surplus_huge_pages_node[old_nid]--;