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Message-Id: <20190108173242.74244-1-willemdebruijn.kernel@gmail.com>
Date: Tue, 8 Jan 2019 12:32:42 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, edumazet@...gle.co, j.vosburgh@...il.com,
vfalico@...il.com, andy@...yhouse.net,
Willem de Bruijn <willemb@...gle.com>,
syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net] bonding: update nest level on unlink
From: Willem de Bruijn <willemb@...gle.com>
A network device stack with multiple layers of bonding devices can
trigger a false positive lockdep warning. Adding lockdep nest levels
fixes this. Update the level on both enslave and unlink, to avoid the
following series of events ..
ip netns add test
ip netns exec test bash
ip link set dev lo addr 00:11:22:33:44:55
ip link set dev lo down
ip link add dev bond1 type bond
ip link add dev bond2 type bond
ip link set dev lo master bond1
ip link set dev bond1 master bond2
ip link set dev bond1 nomaster
ip link set dev bond2 master bond1
.. from still generating a splat:
[ 193.652127] ======================================================
[ 193.658231] WARNING: possible circular locking dependency detected
[ 193.664350] 4.20.0 #8 Not tainted
[ 193.668310] ------------------------------------------------------
[ 193.674417] ip/15577 is trying to acquire lock:
[ 193.678897] 00000000a40e3b69 (&(&bond->stats_lock)->rlock#3/3){+.+.}, at: bond_get_stats+0x58/0x290
[ 193.687851]
but task is already holding lock:
[ 193.693625] 00000000807b9d9f (&(&bond->stats_lock)->rlock#2/2){+.+.}, at: bond_get_stats+0x58/0x290
[..]
[ 193.851092] lock_acquire+0xa7/0x190
[ 193.855138] _raw_spin_lock_nested+0x2d/0x40
[ 193.859878] bond_get_stats+0x58/0x290
[ 193.864093] dev_get_stats+0x5a/0xc0
[ 193.868140] bond_get_stats+0x105/0x290
[ 193.872444] dev_get_stats+0x5a/0xc0
[ 193.876493] rtnl_fill_stats+0x40/0x130
[ 193.880797] rtnl_fill_ifinfo+0x6c5/0xdc0
[ 193.885271] rtmsg_ifinfo_build_skb+0x86/0xe0
[ 193.890091] rtnetlink_event+0x5b/0xa0
[ 193.894320] raw_notifier_call_chain+0x43/0x60
[ 193.899225] netdev_change_features+0x50/0xa0
[ 193.904044] bond_compute_features.isra.46+0x1ab/0x270
[ 193.909640] bond_enslave+0x141d/0x15b0
[ 193.913946] do_set_master+0x89/0xa0
[ 193.918016] do_setlink+0x37c/0xda0
[ 193.921980] __rtnl_newlink+0x499/0x890
[ 193.926281] rtnl_newlink+0x48/0x70
[ 193.930238] rtnetlink_rcv_msg+0x171/0x4b0
[ 193.934801] netlink_rcv_skb+0xd1/0x110
[ 193.939103] rtnetlink_rcv+0x15/0x20
[ 193.943151] netlink_unicast+0x3b5/0x520
[ 193.947544] netlink_sendmsg+0x2fd/0x3f0
[ 193.951942] sock_sendmsg+0x38/0x50
[ 193.955899] ___sys_sendmsg+0x2ba/0x2d0
[ 193.960205] __x64_sys_sendmsg+0xad/0x100
[ 193.964687] do_syscall_64+0x5a/0x460
[ 193.968823] entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fixes: 7e2556e40026 ("bonding: avoid lockdep confusion in bond_get_stats()")
Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
drivers/net/bonding/bond_main.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index a9d597f28023..485462d3087f 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1963,6 +1963,9 @@ static int __bond_release_one(struct net_device *bond_dev,
if (!bond_has_slaves(bond)) {
bond_set_carrier(bond);
eth_hw_addr_random(bond_dev);
+ bond->nest_level = SINGLE_DEPTH_NESTING;
+ } else {
+ bond->nest_level = dev_get_nest_level(bond_dev) + 1;
}
unblock_netpoll_tx();
--
2.20.1.97.g81188d93c3-goog
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