WARNING: CPU: 0 PID: 3038 at kernel/kthread.c:87 free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 3038 Comm: syz-executor6 Not tainted 4.14.0-rc5-mm1+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1c4/0x1e0 kernel/panic.c:546
 report_bug+0x211/0x2d0 lib/bug.c:183
 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:177
 do_trap_no_signal arch/x86/kernel/traps.c:211 [inline]
 do_trap+0x260/0x390 arch/x86/kernel/traps.c:260
 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:297
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310
 invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
RSP: 0018:ffff8801db207768 EFLAGS: 00010206
RAX: ffff8801d1d2a040 RBX: ffff8801c5ea5d00 RCX: ffffffff8148d7e2
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8801c5ea5db8
RBP: ffff8801db207770 R08: 0000000000000001 R09: 1ffff1003b640edc
R10: ffff8801db2076a8 R11: 0000000000000001 R12: 1ffff1003b640ef0
R13: 1ffff1003b640ef4 R14: 0000000000000000 R15: ffff8801db2077e0
 free_task+0x134/0x1a0 kernel/fork.c:390
 __put_task_struct+0x229/0x3b0 kernel/fork.c:668
 put_task_struct include/linux/sched/task.h:95 [inline]
 delayed_put_task_struct+0xca/0x3d0 kernel/exit.c:180
 __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
 rcu_do_batch kernel/rcu/tree.c:2676 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2897 [inline]
 rcu_process_callbacks+0xd74/0x17d0 kernel/rcu/tree.c:2914
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:284
 invoke_softirq kernel/softirq.c:364 [inline]
 irq_exit+0x1cc/0x200 kernel/softirq.c:405
 exiting_irq arch/x86/include/asm/apic.h:540 [inline]
 smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052
 apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:770
 </IRQ>
RIP: 0010:arch_local_irq_enable arch/x86/include/asm/paravirt.h:787 [inline]
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x56/0x70 kernel/locking/spinlock.c:197
RSP: 0018:ffff8801d23777f8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff11
RAX: dffffc0000000000 RBX: ffff8801db2256c0 RCX: 0000000000000000
RDX: 1ffffffff0b58f3b RSI: 0000000000000001 RDI: ffffffff85ac79d8
RBP: ffff8801d2377800 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d2744300
R13: 1ffff1003a46ef08 R14: ffff8801d1d2a040 R15: ffff8801d1d2a040
 finish_lock_switch kernel/sched/sched.h:1349 [inline]
 finish_task_switch+0x1d3/0x740 kernel/sched/core.c:2665
 context_switch kernel/sched/core.c:2801 [inline]
 __schedule+0x8f3/0x2060 kernel/sched/core.c:3374
 schedule+0xf5/0x430 kernel/sched/core.c:3433
 freezable_schedule include/linux/freezer.h:171 [inline]
 do_nanosleep+0x224/0x6e0 kernel/time/hrtimer.c:1473
 hrtimer_nanosleep+0x2b2/0x860 kernel/time/hrtimer.c:1527
 SYSC_nanosleep kernel/time/hrtimer.c:1559 [inline]
 SyS_nanosleep+0x175/0x1f0 kernel/time/hrtimer.c:1546
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x47deb0
RSP: 002b:00007ffef0ac01a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000023
RAX: ffffffffffffffda RBX: 0000000002881914 RCX: 000000000047deb0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ffef0ac01b0
RBP: 0000000000000082 R08: 0000000000000bde R09: 0000000002881940
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000e1a
R13: 0000000000000008 R14: 000000000000a312 R15: 0000000000000016
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..