IPVS: sync thread started: state = BACKUP, mcast_ifn = syz_tun, syncid = 4, id = 0
IPVS: stopping backup sync thread 14470 ...
INFO: task syz-executor6:14467 blocked for more than 120 seconds.
      Not tainted 4.4.125-g38f41ec #21
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D ffff8800b28df790 26992 14467   3847 0x20020004
 ffff8800b28df790 ffff8801bbbb1800 ffffffff8516bcb0 ffff8801c8342120
 ffff8801c8342000 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffff8800ac876000 ffff8801c8341800 0000000000000000
Call Trace:
 [<ffffffff8376b82a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff83776b40>] schedule_timeout+0x3a0/0x970 kernel/time/timer.c:1515
 [<ffffffff8376e919>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff8376e919>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff8376e919>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff8376e919>] wait_for_completion+0x209/0x2e0 kernel/sched/completion.c:122
 [<ffffffff8119165e>] kthread_stop+0x12e/0x790 kernel/kthread.c:497
 [<ffffffff830b5129>] stop_sync_thread+0x3d9/0x740 net/netfilter/ipvs/ip_vs_sync.c:1995
 [<ffffffff8309e088>] do_ip_vs_set_ctl+0x228/0xba0 net/netfilter/ipvs/ip_vs_ctl.c:2362
 [<ffffffff82f9d7da>] compat_nf_sockopt net/netfilter/nf_sockopt.c:145 [inline]
 [<ffffffff82f9d7da>] compat_nf_setsockopt+0xfa/0x130 net/netfilter/nf_sockopt.c:155
 [<ffffffff83104beb>] compat_ip_setsockopt+0x8b/0xd0 net/ipv4/ip_sockglue.c:1251
 [<ffffffff8310ddc5>] inet_csk_compat_setsockopt+0x95/0x120 net/ipv4/inet_connection_sock.c:914
 [<ffffffff831236dd>] compat_tcp_setsockopt+0x3d/0x70 net/ipv4/tcp.c:2652
 [<ffffffff82df7d12>] compat_sock_common_setsockopt+0xb2/0x140 net/core/sock.c:2670
 [<ffffffff82edfde9>] C_SYSC_setsockopt net/compat.c:384 [inline]
 [<ffffffff82edfde9>] compat_SyS_setsockopt+0x149/0x290 net/compat.c:367
 [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
 [<ffffffff8377b2aa>] sysenter_flags_fixed+0xd/0x17
1 lock held by syz-executor6/14467:
 #0:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff8309e079>] do_ip_vs_set_ctl+0x219/0xba0 net/netfilter/ipvs/ip_vs_ctl.c:2361
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff811c7ebc>]  [<ffffffff811c7ebc>] __read_once_size include/linux/compiler.h:218 [inline]
RIP: 0010:[<ffffffff811c7ebc>]  [<ffffffff811c7ebc>] atomic_read arch/x86/include/asm/atomic.h:27 [inline]
RIP: 0010:[<ffffffff811c7ebc>]  [<ffffffff811c7ebc>] nr_iowait_cpu+0x6c/0x80 kernel/sched/core.c:2873
RSP: 0018:ffffffff84207d70  EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8801db21f4c0 RCX: ffffffff812d5aca
RDX: 0000000000000000 RSI: ffff8801db219c40 RDI: ffff8801db21fdf8
RBP: ffffffff84207d80 R08: ffff88021fffd018 R09: 0000000000000008
R10: ffffed0043fffa01 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8801db219cd8 R15: ffff8801db219c40
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbaf43ce140 CR3: 00000001d0d3a000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000 000000541b1e21bd ffffffff84207dc8 ffffffff812d5b02
 00000000002074b0 000000541b1e21bd ffff8801db219c40 000000541b1e21bd
 ffff8801db219cd0 000000541b1e21bd ffffffff84208000 ffffffff84207de8
Call Trace:
 [<ffffffff812d5b02>] update_ts_time_stats+0x112/0x1f0 kernel/time/tick-sched.c:446
 [<ffffffff812d5fe6>] tick_nohz_stop_idle+0x26/0x70 kernel/time/tick-sched.c:460
 [<ffffffff812d821f>] tick_nohz_idle_exit+0x2cf/0x3d0 kernel/time/tick-sched.c:943
 [<ffffffff81221cf5>] cpu_idle_loop kernel/sched/idle.c:267 [inline]
 [<ffffffff81221cf5>] cpu_startup_entry+0x2a5/0x8f0 kernel/sched/idle.c:301
 [<ffffffff837667b9>] rest_init+0x189/0x190 init/main.c:410
 [<ffffffff84823811>] start_kernel+0x6b9/0x6ee init/main.c:682
 [<ffffffff84822312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84822454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: df 48 8d bb 38 09 00 00 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 0c 48 63 83 38 09 00 00 <5b> 41 5c 5d c3 e8 fa 71 33 00 eb ed e8 13 72 33 00 eb b1 90 55 
NMI backtrace for cpu 1
CPU: 1 PID: 486 Comm: khungtaskd Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bacf0000 task.stack: ffff8800bac80000
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bac87cb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bac87ce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f5a0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c420009e80 CR3: 00000000acff6000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f5a0 ffffffff847f0b40 fffffbfff08fdc1c dffffc0000000000
 ffff8801db31bca0 ffff8800bac87d00 ffffffff810b9abb ffffffff839f6dc0
 0000000000000003 ffff8800bac87d60 ffffffff81d11764 ffffffff8141b993
Call Trace:
 [<ffffffff810b9abb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d11764>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9b54>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff813695ca>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff813695ca>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813695ca>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813695ca>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff81190b48>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83779d95>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 2b 33 17 00 4c 89 e7 57 9d 0f 1f