------------[ cut here ]------------
WARNING: CPU: 1 PID: 16897 at lib/timerqueue.c:65 timerqueue_del+0xff/0x150 lib/timerqueue.c:65
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 16897 Comm: kworker/u4:5 Not tainted 5.6.0-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:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 fixup_bug arch/x86/kernel/traps.c:170 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:timerqueue_del+0xff/0x150 lib/timerqueue.c:65
Code: e8 86 5c ff ff 4c 89 e1 48 ba 00 00 00 00 00 fc ff df 48 c1 e9 03 80 3c 11 00 75 43 48 89 45 08 e9 75 ff ff ff e8 a1 ad a9 f9 <0f> 0b e9 3f ff ff ff 48 89 df e8 32 57 e7 f9 eb 86 48 89 df e8 a8
RSP: 0018:ffffc900016d78d0 EFLAGS: 00010093
RAX: ffff88804600a4c0 RBX: ffffe8ffffc88c00 RCX: ffffffff87c9832c
RDX: 0000000000000000 RSI: ffffffff87c983ef RDI: 0000000000000006
RBP: ffff8880ae7297c8 R08: ffff88804600a4c0 R09: ffffed1015ce7104
R10: ffff8880ae73881b R11: ffffed1015ce7103 R12: ffffe8ffffc88c00
R13: 0000000000000001 R14: ffff8880ae729700 R15: 0000000000000000
 __remove_hrtimer+0xc8/0x1e0 kernel/time/hrtimer.c:997
 remove_hrtimer kernel/time/hrtimer.c:1037 [inline]
 hrtimer_try_to_cancel kernel/time/hrtimer.c:1169 [inline]
 hrtimer_try_to_cancel+0x287/0x5b0 kernel/time/hrtimer.c:1151
 hrtimer_cancel+0x13/0x40 kernel/time/hrtimer.c:1278
 napi_disable+0xbe/0xe0 net/core/dev.c:6520
 gro_cells_destroy net/core/gro_cells.c:101 [inline]
 gro_cells_destroy+0x117/0x390 net/core/gro_cells.c:92
 ip6gre_dev_free+0x15/0x60 net/ipv6/ip6_gre.c:1388
 netdev_run_todo+0x449/0x760 net/core/dev.c:9657
 ip6gre_exit_batch_net+0x4ed/0x700 net/ipv6/ip6_gre.c:1606
 ops_exit_list.isra.0+0x103/0x150 net/core/net_namespace.c:189
 cleanup_net+0x511/0xa50 net/core/net_namespace.c:603
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2266
 worker_thread+0x96/0xe20 kernel/workqueue.c:2412
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

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