swap: cleanup duplicated WARN_ON in add_to_avail_list

Patch series "fix WARN_ON in add_to_avail_list".


Empty check for plist_node is checked in add_to_avail_list and plist_add. 
Drop the duplicate one in add_to_avail_list.

Link: https://lkml.kernel.org/r/20230627120833.2230766-1-mawupeng1@huawei.com
Link: https://lkml.kernel.org/r/20230627120833.2230766-2-mawupeng1@huawei.comSigned-off-by: Ma Wupeng <mawupeng1@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swapfile.c

@@ -714,10 +714,8 @@ static void add_to_avail_list(struct swap_info_struct *p)
 	int nid;
 
 	spin_lock(&swap_avail_lock);
-	for_each_node(nid) {
-		WARN_ON(!plist_node_empty(&p->avail_lists[nid]));
+	for_each_node(nid)
 		plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]);
-	}
 	spin_unlock(&swap_avail_lock);
 }