4.20-stable review patch. If anyone has any objections, please let me know.
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From: Marc Zyngier marc.zyngier@arm.com
[ Upstream commit c8101f7729daee251f4f6505f9d135ec08e1342f ]
Creating a macvtap on a DSA-backed interface results in the following splat when lockdep is enabled:
[ 19.638080] IPv6: ADDRCONF(NETDEV_CHANGE): lan0: link becomes ready [ 23.041198] device lan0 entered promiscuous mode [ 23.043445] device eth0 entered promiscuous mode [ 23.049255] [ 23.049557] ============================================ [ 23.055021] WARNING: possible recursive locking detected [ 23.060490] 5.0.0-rc3-00013-g56c857a1b8d3 #118 Not tainted [ 23.066132] -------------------------------------------- [ 23.071598] ip/2861 is trying to acquire lock: [ 23.076171] 00000000f61990cb (_xmit_ETHER){+...}, at: dev_set_rx_mode+0x1c/0x38 [ 23.083693] [ 23.083693] but task is already holding lock: [ 23.089696] 00000000ecf0c3b4 (_xmit_ETHER){+...}, at: dev_uc_add+0x24/0x70 [ 23.096774] [ 23.096774] other info that might help us debug this: [ 23.103494] Possible unsafe locking scenario: [ 23.103494] [ 23.109584] CPU0 [ 23.112093] ---- [ 23.114601] lock(_xmit_ETHER); [ 23.117917] lock(_xmit_ETHER); [ 23.121233] [ 23.121233] *** DEADLOCK *** [ 23.121233] [ 23.127325] May be due to missing lock nesting notation [ 23.127325] [ 23.134315] 2 locks held by ip/2861: [ 23.137987] #0: 000000003b766c72 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x338/0x4e0 [ 23.146231] #1: 00000000ecf0c3b4 (_xmit_ETHER){+...}, at: dev_uc_add+0x24/0x70 [ 23.153757] [ 23.153757] stack backtrace: [ 23.158243] CPU: 0 PID: 2861 Comm: ip Not tainted 5.0.0-rc3-00013-g56c857a1b8d3 #118 [ 23.166212] Hardware name: Globalscale Marvell ESPRESSOBin Board (DT) [ 23.172843] Call trace: [ 23.175358] dump_backtrace+0x0/0x188 [ 23.179116] show_stack+0x14/0x20 [ 23.182524] dump_stack+0xb4/0xec [ 23.185928] __lock_acquire+0x123c/0x1860 [ 23.190048] lock_acquire+0xc8/0x248 [ 23.193724] _raw_spin_lock_bh+0x40/0x58 [ 23.197755] dev_set_rx_mode+0x1c/0x38 [ 23.201607] dev_set_promiscuity+0x3c/0x50 [ 23.205820] dsa_slave_change_rx_flags+0x5c/0x70 [ 23.210567] __dev_set_promiscuity+0x148/0x1e0 [ 23.215136] __dev_set_rx_mode+0x74/0x98 [ 23.219167] dev_uc_add+0x54/0x70 [ 23.222575] macvlan_open+0x170/0x1d0 [ 23.226336] __dev_open+0xe0/0x160 [ 23.229830] __dev_change_flags+0x16c/0x1b8 [ 23.234132] dev_change_flags+0x20/0x60 [ 23.238074] do_setlink+0x2d0/0xc50 [ 23.241658] __rtnl_newlink+0x5f8/0x6e8 [ 23.245601] rtnl_newlink+0x50/0x78 [ 23.249184] rtnetlink_rcv_msg+0x360/0x4e0 [ 23.253397] netlink_rcv_skb+0xe8/0x130 [ 23.257338] rtnetlink_rcv+0x14/0x20 [ 23.261012] netlink_unicast+0x190/0x210 [ 23.265043] netlink_sendmsg+0x288/0x350 [ 23.269075] sock_sendmsg+0x18/0x30 [ 23.272659] ___sys_sendmsg+0x29c/0x2c8 [ 23.276602] __sys_sendmsg+0x60/0xb8 [ 23.280276] __arm64_sys_sendmsg+0x1c/0x28 [ 23.284488] el0_svc_common+0xd8/0x138 [ 23.288340] el0_svc_handler+0x24/0x80 [ 23.292192] el0_svc+0x8/0xc
This looks fairly harmless (no actual deadlock occurs), and is fixed in a similar way to c6894dec8ea9 ("bridge: fix lockdep addr_list_lock false positive splat") by putting the addr_list_lock in its own lockdep class.
Signed-off-by: Marc Zyngier marc.zyngier@arm.com Reviewed-by: Florian Fainelli f.fainelli@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/dsa/master.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/net/dsa/master.c +++ b/net/dsa/master.c @@ -179,6 +179,8 @@ static const struct attribute_group dsa_ .attrs = dsa_slave_attrs, };
+static struct lock_class_key dsa_master_addr_list_lock_key; + int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp) { int ret; @@ -190,6 +192,8 @@ int dsa_master_setup(struct net_device * wmb();
dev->dsa_ptr = cpu_dp; + lockdep_set_class(&dev->addr_list_lock, + &dsa_master_addr_list_lock_key);
ret = dsa_master_ethtool_setup(dev); if (ret)