WARNING: CPU: 1 PID: 3001 at kernel/kthread.c:87 free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3001 Comm: syzkaller733715 Not tainted 4.14.0-rc7-next-20171102+ #37
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:ffff8801db307768 EFLAGS: 00010206
RAX: ffff8801cebf8600 RBX: ffff8801c4439040 RCX: ffffffff814937d2
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8801c44391c8
RBP: ffff8801db307770 R08: 0000000000000000 R09: 1ffff1003b660ed4
R10: ffff8801cebf8600 R11: 0000000000000001 R12: 1ffff1003b660ef0
R13: 1ffff1003b660ef4 R14: 0000000000000000 R15: ffff8801db3077e0
 free_task+0x134/0x1a0 kernel/fork.c:390
 __put_task_struct+0x229/0x3b0 kernel/fork.c:663
 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:2935 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2902 [inline]
 rcu_process_callbacks+0xd74/0x17d0 kernel/rcu/tree.c:2919
 __do_softirq+0x29d/0xbb2 kernel/softirq.c:284
 invoke_softirq kernel/softirq.c:364 [inline]
 irq_exit+0x1d3/0x210 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:ffff8801ce1477f8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff11
RAX: dffffc0000000000 RBX: ffff8801db325c80 RCX: 0000000000000000
RDX: 1ffffffff0bd9673 RSI: 0000000000000001 RDI: ffffffff85ecb398
RBP: ffff8801ce147800 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ce644140
R13: 1ffff10039c28f08 R14: ffff8801cebf8600 R15: ffff8801cebf8600
 finish_lock_switch kernel/sched/sched.h:1349 [inline]
 finish_task_switch+0x1d3/0x740 kernel/sched/core.c:2663
 context_switch kernel/sched/core.c:2799 [inline]
 __schedule+0x8f3/0x2060 kernel/sched/core.c:3372
 schedule+0xf5/0x430 kernel/sched/core.c:3431
 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: 0033:0x4442b0
RSP: 002b:00007ffcc260f278 EFLAGS: 00000246 ORIG_RAX: 0000000000000023
RAX: ffffffffffffffda RBX: 0000000000001284 RCX: 00000000004442b0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ffcc260f280
RBP: 0000000000000086 R08: 0000000000000bb9 R09: 00000000025cb880
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000001284
R13: 0000000000406e20 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..