ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x90 kernel/workqueue.c:4850
------------[ cut here ]------------
WARNING: CPU: 0 PID: 22 at lib/debugobjects.c:287 debug_print_object.cold+0xa7/0xdb lib/debugobjects.c:287
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 22 Comm: kworker/u4:1 Not tainted 4.14.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 panic+0x1f9/0x42d kernel/panic.c:183
 __warn.cold+0x2f/0x30 kernel/panic.c:547
 report_bug+0x20a/0x248 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963
RIP: 0010:debug_print_object.cold+0xa7/0xdb lib/debugobjects.c:287
RSP: 0018:ffff8880a9a2f900 EFLAGS: 00010082
RAX: 0000000000000061 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff86ac0860 RDI: ffffed1015345f16
RBP: ffffffff86abbae0 R08: 0000000000000061 R09: 0000000000000000
R10: fffffbfff14a8ce1 R11: ffff8880a9a1e5c0 R12: ffffffff813b94a0
R13: 0000000000000000 R14: ffffffff8a6e3348 R15: ffff8880a403ba10
 __debug_check_no_obj_freed lib/debugobjects.c:747 [inline]
 debug_check_no_obj_freed+0x3cd/0x6e4 lib/debugobjects.c:776
 kfree+0xbb/0x260 mm/slab.c:3814
 kvfree+0x45/0x50 mm/util.c:416
 device_release+0x15f/0x1a0 drivers/base/core.c:833
 kobject_cleanup lib/kobject.c:646 [inline]
 kobject_release lib/kobject.c:675 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x13e/0x1f0 lib/kobject.c:692
 netdev_run_todo+0x4a9/0x710 net/core/dev.c:7954
 default_device_exit_batch+0x2e7/0x380 net/core/dev.c:8740
 ops_exit_list.isra.0+0xef/0x140 net/core/net_namespace.c:145
 cleanup_net+0x3bb/0x820 net/core/net_namespace.c:484
 process_one_work+0x813/0x1540 kernel/workqueue.c:2114
 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2248
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

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