IPVS: sync thread started: state = BACKUP, mcast_ifn = veth0_to_bridge, syncid = 0, id = 0
INFO: task syz-executor4:10924 blocked for more than 120 seconds.
      Not tainted 4.9.94-g8683408 #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D27512 10924   3866 0x00000004
 ffff8801d834b000 0000000000000000 ffff8801c7785500 ffff8801d9b73000
 ffff8801db321b98 ffff8801d8aef7b0 ffffffff839e140d 17689392b3be4faf
 fffffbfff0b32510 ffff880100000001 00fffbff00000000 ffff8801db322468
Call Trace:
 [<ffffffff839e2a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839eee21>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e5bd3>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff839e5bd3>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff839e5bd3>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff839e5bd3>] wait_for_completion+0x203/0x2e0 kernel/sched/completion.c:122
 [<ffffffff8119ba26>] kthread_stop+0xa6/0x5d0 kernel/kthread.c:513
 [<ffffffff839ce2cd>] stop_sync_thread.cold.9+0x260/0x363 net/netfilter/ipvs/ip_vs_sync.c:1998
 [<ffffffff832dd2d4>] do_ip_vs_set_ctl+0x654/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2403
 [<ffffffff831d8d1d>] nf_sockopt net/netfilter/nf_sockopt.c:105 [inline]
 [<ffffffff831d8d1d>] nf_setsockopt+0x6d/0xc0 net/netfilter/nf_sockopt.c:114
 [<ffffffff8334291a>] ip_setsockopt+0x9a/0xb0 net/ipv4/ip_sockglue.c:1249
 [<ffffffff833627b8>] tcp_setsockopt+0x88/0xe0 net/ipv4/tcp.c:2755
 [<ffffffff8301775a>] sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
 [<ffffffff83014516>] SYSC_setsockopt net/socket.c:1772 [inline]
 [<ffffffff83014516>] SyS_setsockopt+0x166/0x260 net/socket.c:1751
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f2313>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
3 locks held by kworker/0:1/25:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((addr_chk_work).work){+.+...}, at: [<ffffffff8118ad48>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830af6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
2 locks held by khungtaskd/518:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423bb0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3675:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d565c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3771:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f04b2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8211c622>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor4/10924:
 #0:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff832dd2c5>] do_ip_vs_set_ctl+0x645/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2402
2 locks held by syz-executor4/10934:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830af6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff832dd58d>] do_ip_vs_set_ctl+0x90d/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2397
1 lock held by ipvs-b:4:0/10932:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830af6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 518 Comm: khungtaskd Not tainted 4.9.94-g8683408 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8707d08 ffffffff81eb0aa9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d8707d40
 ffffffff81ebbdd7 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb0aa9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0aa9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebbdd7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebbd6a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7e64>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c54>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c54>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c54>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f24dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff839f0f16