From 12cc41f671e775df9fae57f17ac73e7f39a64a01 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.vnet.ibm.com>
Date: Mon, 16 Apr 2018 19:58:59 +0300
Subject: [PATCH] lazy-pages: merge_iov_lists: fix corner case of empty
 destination

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
---
 criu/uffd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/criu/uffd.c b/criu/uffd.c
index 180ac4817..55de798ab 100644
--- a/criu/uffd.c
+++ b/criu/uffd.c
@@ -419,6 +419,14 @@ static void merge_iov_lists(struct list_head *src, struct list_head *dst)
 {
 	struct lazy_iov *iov, *p, *n;
 
+	if (list_empty(src))
+		return;
+
+	if (list_empty(dst)) {
+		iov = list_first_entry(src, struct lazy_iov, l);
+		list_move(&iov->l, dst);
+	}
+
 	list_for_each_entry_safe(iov, n, src, l) {
 		list_for_each_entry(p, dst, l) {
 			if (iov->start < p->start) {