syzbot

nf_conntrack: default automatic helper assignment has been turned off for security reasons and CT-based  firewall rule not found. Use the iptables CT target to attach helpers instead.
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 	1-....: (105000 ticks this GP) idle=d9e/1/0x4000000000000002 softirq=15903/15904 fqs=26216 
rcu: 	 (t=105010 jiffies g=31397 q=1102)
NMI backtrace for cpu 1
CPU: 1 PID: 4312 Comm: syz-executor3 Not tainted 4.18.0-rc7-next-20180803+ #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:162 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1340
 print_cpu_stall.cold.78+0x2fb/0x59c kernel/rcu/tree.c:1478
 check_cpu_stall kernel/rcu/tree.c:1550 [inline]
 __rcu_pending kernel/rcu/tree.c:3276 [inline]
 rcu_pending kernel/rcu/tree.c:3319 [inline]
 rcu_check_callbacks+0xd93/0x1660 kernel/rcu/tree.c:2665
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x3eb/0x10c0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x2f3/0x750 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1028 [inline]
 smp_apic_timer_interrupt+0x165/0x730 arch/x86/kernel/apic/apic.c:1053
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:867
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783 [inline]
RIP: 0010:lock_release+0x4dc/0xa30 kernel/locking/lockdep.c:3946
Code: 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 cd 03 00 00 48 83 3d bb 56 92 06 00 0f 84 c4 02 00 00 48 8b bd e8 fe ff ff 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 01 c3 48 c7 03 00
RSP: 0018:ffff88019e6876a8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 1ffff10033cd0eda RCX: 0000000000000005
RDX: 1ffffffff0fe361d RSI: dffffc0000000000 RDI: 0000000000000286
RBP: ffff88019e6877d8 R08: 1ffff10033cd0ede R09: ffff88019e687530
R10: ffffed0038a7fe66 R11: ffff8801c53ff333 R12: ffff88019e67e1c0
R13: ffffffff87f92760 R14: ffff88019e67e1c0 R15: ffff88019e6876f0
 rcu_lock_release include/linux/rcupdate.h:249 [inline]
 rcu_read_unlock include/linux/rcupdate.h:683 [inline]
 pin_kill+0x821/0xb80 fs/fs_pin.c:55
 group_pin_kill+0xdd/0x290 fs/fs_pin.c:101
 namespace_unlock+0x1c7/0x210 fs/namespace.c:1293
 do_umount fs/namespace.c:1487 [inline]
 ksys_umount+0x861/0x1310 fs/namespace.c:1582
 __do_sys_umount fs/namespace.c:1593 [inline]
 __se_sys_umount fs/namespace.c:1591 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1591
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459537
Code: 44 00 00 b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 dd 8a fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 bd 8a fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe1e0715a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 000000000001b005 RCX: 0000000000459537
RDX: 000000000000000c RSI: 0000000000000002 RDI: 00007ffe1e072690
RBP: 00007ffe1e072690 R08: 0000000000000001 R09: 0000000000efa940
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000125
R13: 0000000000000000 R14: 000000000000000c R15: badc0ffeebadface