--- /dev/null
+From 76da0704507bbc51875013f6557877ab308cfd0a Mon Sep 17 00:00:00 2001
+From: WANG Cong <xiyou.wangcong@gmail.com>
+Date: Tue, 20 Jun 2017 11:42:27 -0700
+Subject: ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
+
+From: WANG Cong <xiyou.wangcong@gmail.com>
+
+commit 76da0704507bbc51875013f6557877ab308cfd0a upstream.
+
+In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
+I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired,
+unfortunately, as reported by jeffy, netdev_wait_allrefs()
+could rebroadcast NETDEV_UNREGISTER event until all refs are
+gone.
+
+We have to add an additional check to avoid this corner case.
+For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED,
+for dev_change_net_namespace(), dev->reg_state is
+NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
+
+Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
+Reported-by: jeffy <jeffy.chen@rock-chips.com>
+Cc: David Ahern <dsahern@gmail.com>
+Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
+Acked-by: David Ahern <dsahern@gmail.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ net/ipv6/route.c | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+--- a/net/ipv6/route.c
++++ b/net/ipv6/route.c
+@@ -2827,7 +2827,11 @@ static int ip6_route_dev_notify(struct n
+ net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
+ net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
+ #endif
+- } else if (event == NETDEV_UNREGISTER) {
++ } else if (event == NETDEV_UNREGISTER &&
++ dev->reg_state != NETREG_UNREGISTERED) {
++ /* NETDEV_UNREGISTER could be fired for multiple times by
++ * netdev_wait_allrefs(). Make sure we only call this once.
++ */
+ in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev);
+ #ifdef CONFIG_IPV6_MULTIPLE_TABLES
+ in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev);