Hello, syzbot found the following issue on: HEAD commit: 6a70f89c Merge tag 'nfs-for-5.8-3' of git://git.linux-nfs... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17607db3100000 kernel config: https://syzkaller.appspot.com/x/.config?x=a160d1053fc89af5 dashboard link: https://syzkaller.appspot.com/bug?extid=4c0c011e71ae95a85ffe compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17ba6d7d100000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13b72dd7100000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+4c0c011e71ae95a85ffe at syzkaller.appspotmail.com BUG: MAX_LOCKDEP_CHAINS too low! turning off the locking correctness validator. CPU: 1 PID: 30234 Comm: kworker/u4:3 Not tainted 5.8.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bond1453 bond_resend_igmp_join_requests_delayed Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 add_chain_cache kernel/locking/lockdep.c:3063 [inline] lookup_chain_cache_add kernel/locking/lockdep.c:3162 [inline] validate_chain kernel/locking/lockdep.c:3183 [inline] __lock_acquire.cold+0x11/0x3f8 kernel/locking/lockdep.c:4380 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:353 [inline] br_multicast_add_group+0x68/0x740 net/bridge/br_multicast.c:546 br_ip6_multicast_add_group net/bridge/br_multicast.c:622 [inline] br_ip6_multicast_add_group net/bridge/br_multicast.c:606 [inline] br_ip6_multicast_mld2_report net/bridge/br_multicast.c:1048 [inline] br_multicast_ipv6_rcv net/bridge/br_multicast.c:1712 [inline] br_multicast_rcv+0x1083/0x4730 net/bridge/br_multicast.c:1747 br_dev_xmit+0x708/0x1510 net/bridge/br_device.c:87 __netdev_start_xmit include/linux/netdevice.h:4611 [inline] netdev_start_xmit include/linux/netdevice.h:4625 [inline] xmit_one net/core/dev.c:3556 [inline] dev_hard_start_xmit+0x193/0x950 net/core/dev.c:3572 __dev_queue_xmit+0x2091/0x2d60 net/core/dev.c:4131 bond_dev_queue_xmit+0xf8/0x1c0 drivers/net/bonding/bond_main.c:302 bond_3ad_xor_xmit drivers/net/bonding/bond_main.c:4258 [inline] __bond_start_xmit drivers/net/bonding/bond_main.c:4398 [inline] bond_start_xmit+0x534/0xfc0 drivers/net/bonding/bond_main.c:4426 __netdev_start_xmit include/linux/netdevice.h:4611 [inline] netdev_start_xmit include/linux/netdevice.h:4625 [inline] xmit_one net/core/dev.c:3556 [inline] dev_hard_start_xmit+0x193/0x950 net/core/dev.c:3572 __dev_queue_xmit+0x2091/0x2d60 net/core/dev.c:4131 neigh_hh_output include/net/neighbour.h:498 [inline] neigh_output include/net/neighbour.h:507 [inline] ip6_finish_output2+0x7f1/0x17b0 net/ipv6/ip6_output.c:117 __ip6_finish_output net/ipv6/ip6_output.c:143 [inline] __ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128 ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176 dst_output include/net/dst.h:443 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] mld_sendpack+0x92a/0xdb0 net/ipv6/mcast.c:1679 mld_send_report+0xc3/0x230 net/ipv6/mcast.c:1881 ipv6_mc_rejoin_groups net/ipv6/mcast.c:2637 [inline] ipv6_mc_netdev_event+0x287/0x480 net/ipv6/mcast.c:2650 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2027 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline] call_netdevice_notifiers+0x79/0xa0 net/core/dev.c:2053 bond_resend_igmp_join_requests_delayed+0x5d/0x170 drivers/net/bonding/bond_main.c:590 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller at googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches