IPVS: sync thread started: state = BACKUP, mcast_ifn = lo, syncid = 0, id = 0
IPVS: stopping backup sync thread 30184 ...
IPVS: sync thread started: state = MASTER, mcast_ifn = syz_tun, syncid = 3, id = 0
IPVS: sync thread started: state = BACKUP, mcast_ifn = lo, syncid = 0, id = 0
IPVS: stopping backup sync thread 30212 ...
INFO: task syz-executor2:30162 blocked for more than 120 seconds.
      Not tainted 4.9.94-g8683408 #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D28456 30162   3847 0x20020004
 ffff8801d92a1800 0000000000000000 ffff8801ccbfda40 ffff8801d9b73000
 ffff8801db321b98 ffff8801d461f7a0 ffffffff838c040d ffff8801ccbfda40
 0000000000000002 ffffffff8536dc80 00ff8801d461f768 ffff8801db322468
Call Trace:
 [<ffffffff838c1a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff838cde21>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff838c4bd3>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff838c4bd3>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff838c4bd3>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff838c4bd3>] wait_for_completion+0x203/0x2e0 kernel/sched/completion.c:122
 [<ffffffff8119ba26>] kthread_stop+0xa6/0x5d0 kernel/kthread.c:513
 [<ffffffff838ad2cd>] stop_sync_thread.cold.9+0x260/0x363 net/netfilter/ipvs/ip_vs_sync.c:1998
 [<ffffffff831bc2d4>] do_ip_vs_set_ctl+0x654/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2403
 [<ffffffff830b7e7d>] compat_nf_sockopt net/netfilter/nf_sockopt.c:145 [inline]
 [<ffffffff830b7e7d>] compat_nf_setsockopt+0x10d/0x130 net/netfilter/nf_sockopt.c:155
 [<ffffffff832219d7>] compat_ip_setsockopt+0xa7/0xe0 net/ipv4/ip_sockglue.c:1275
 [<ffffffff8322af37>] inet_csk_compat_setsockopt+0x97/0x120 net/ipv4/inet_connection_sock.c:914
 [<ffffffff8324184d>] compat_tcp_setsockopt+0x3d/0x70 net/ipv4/tcp.c:2766
 [<ffffffff82ef6854>] compat_sock_common_setsockopt+0xb4/0x150 net/core/sock.c:2717
 [<ffffffff82ff4ffc>] C_SYSC_setsockopt net/compat.c:398 [inline]
 [<ffffffff82ff4ffc>] compat_SyS_setsockopt+0x14c/0x2a0 net/compat.c:381
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff838d2a10>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/516:
 #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
2 locks held by getty/3748:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838cf4b2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007082>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
3 locks held by kworker/0:2/28991:
 #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: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor2/30162:
 #0:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff831bc2c5>] do_ip_vs_set_ctl+0x645/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2402
2 locks held by syz-executor2/30217:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff831bc58d>] do_ip_vs_set_ctl+0x90d/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2397
1 lock held by ipvs-b:6:0/30212:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

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

NMI backtrace for cpu 1
CPU: 1 PID: 516 Comm: khungtaskd Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d96ffd08 ffffffff81d9b509 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d96ffd40
 ffffffff81da6837 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81d9b509>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9b509>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da6837>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81da67ca>] 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
 [<ffffffff838d14dc>] 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
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84429800 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff8123254a>] 
c [<ffffffff8123254a>] mark_lock+0xaa/0x1280 kernel/locking/lockdep.c:3039
RSP: 0018:ffff8801db207cb8  EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffffffff8442a0c8 RCX: 1ffffffff088541d
RDX: 1ffffffff0a6c7c2 RSI: ffffffff8442a0c8 RDI: ffffffff85363e10
RBP: ffff8801db207d00 R08: ffffffff8442a0e8 R09: 0000000000000001
R10: ffffffff84429800 R11: 0000000000000001 R12: ffffffff85363de0
R13: 0000000000001000 R14: 000000000000000c R15: ffffffff84429800
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000157eb10 CR3: 00000001c1238000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801db322520
c 0000000041b58ab3
c ffffffff844def20
c dffffc0000000000
c
 ffffffff8442a0c8
c 000000000000002f
c 0000000000000000
c ffffffff8442a0b4
c
 ffffffff8442a0ea
c ffff8801db207eb8
c ffffffff812349a4
c 0000000000000136
c
Call Trace:
 <IRQ> 
d [<ffffffff812349a4>] __lock_acquire+0x654/0x4070 kernel/locking/lockdep.c:3306
 [<ffffffff81238e30>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff812b529a>] seqcount_lockdep_reader_access include/linux/seqlock.h:80 [inline]
 [<ffffffff812b529a>] read_seqcount_begin include/linux/seqlock.h:163 [inline]
 [<ffffffff812b529a>] ktime_get+0x11a/0x1e0 kernel/time/timekeeping.c:757
 [<ffffffff812cc8ec>] tick_nohz_irq_enter kernel/time/tick-sched.c:1144 [inline]
 [<ffffffff812cc8ec>] tick_irq_enter+0xcc/0x220 kernel/time/tick-sched.c:1165
 [<ffffffff81148ed3>] irq_enter+0xb3/0xd0 kernel/softirq.c:345
 [<ffffffff838d5a3a>] smp_reschedule_interrupt+0xa/0x90 arch/x86/kernel/smp.c:267
 [<ffffffff838d3610>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff838cff16>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838cf555>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff838cf555>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff81069fa0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:286
 [<ffffffff838d0375>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81220e35>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81220e35>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81220e35>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff838bd1dc>] rest_init+0x183/0x189 init/main.c:409
 [<ffffffff84a73943>] start_kernel+0x67e/0x6b2 init/main.c:664
 [<ffffffff84a7229a>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff84a723db>] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:177
Code: 
c01 
c00 
c00 
c49 
c81 
cec 
cb0 
c01 
c00 
c00 
c49 
c81 
cc4 
c40 
cf0 
c35 
c85 
c49 
c8d 
c7c 
c24 
c30 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c48 
c89 
cfa 
c48 
cc1 
cea 
c03 
c80 
c3c 
c02 
c00 
c<0f> 
c85 
c41 
c0e 
c00 
c00 
c4d 
c85 
c6c 
c24 
c30 
c74 
c5f 
c41 
cbd 
c01 
c00 
c00 
c00 
c48 
c83 
c