WARNING: CPU: 0 PID: 3051 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: 3051 Comm: syz-executor1 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: ffff8801d22ae480 RBX: ffff8801c429c700 RCX: ffffffff8148d7e2
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8801c429c7b8
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:debug_lockdep_rcu_enabled.part.3+0x37/0x60 kernel/rcu/update.c:300
RSP: 0018:ffff8801d1cb7cc8 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff11
RAX: 0000000000000007 RBX: ffff8801d22ae480 RCX: ffffffff819768ae
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffff8801d22aecec
RBP: ffff8801d1cb7cd0 R08: ffff88021fff901c R09: ffff88021fff9008
R10: ffff88021fff9010 R11: ffff88021fff901d R12: 0000000000000000
R13: ffffffff851e1880 R14: 0000000000000018 R15: 0000000000000023
 debug_lockdep_rcu_enabled+0x77/0x90 kernel/rcu/update.c:299
 ___might_sleep+0x8a/0x470 kernel/sched/core.c:6012
 __might_sleep+0x95/0x190 kernel/sched/core.c:6000
 __might_fault+0xab/0x1d0 mm/memory.c:4527
 _copy_to_user+0x2c/0xc0 lib/usercopy.c:24
 copy_to_user include/linux/uaccess.h:154 [inline]
 put_timespec64+0xef/0x180 kernel/time/time.c:918
 SYSC_clock_gettime kernel/time/posix-timers.c:1063 [inline]
 SyS_clock_gettime+0x12f/0x160 kernel/time/posix-timers.c:1051
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x45560a
RSP: 002b:0000000000a6f9f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e4
RAX: ffffffffffffffda RBX: 000000000131f914 RCX: 000000000045560a
RDX: 0000000000000000 RSI: 0000000000a6fa00 RDI: 0000000000000001
RBP: 0000000000000082 R08: 0000000000000001 R09: 000000000131f940
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000003f
R13: 0000000000000013 R14: 0000000000008b34 R15: 0000000000000016
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..