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BUG: KCSAN: data-race in del_timer / enqueue_timer

read to 0xffff888098e49480 of 8 bytes by task 1623 on cpu 0:
 del_timer+0x3b/0xb0 kernel/time/timer.c:1198
 mld_ifc_stop_timer+0x30/0xa0 net/ipv6/mcast.c:1060
 ipv6_mc_down+0x6c/0xf0 net/ipv6/mcast.c:2546
 addrconf_ifdown+0xb15/0xce0 net/ipv6/addrconf.c:3844
 addrconf_notify+0x35e/0x1550 net/ipv6/addrconf.c:3633
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:83
 __raw_notifier_call_chain kernel/notifier.c:361 [inline]
 raw_notifier_call_chain+0x37/0x50 kernel/notifier.c:368
 call_netdevice_notifiers_info net/core/dev.c:1893 [inline]
 call_netdevice_notifiers_info+0x9a/0x120 net/core/dev.c:1878
 call_netdevice_notifiers_extack net/core/dev.c:1905 [inline]
 call_netdevice_notifiers net/core/dev.c:1919 [inline]
 dev_close_many+0x24f/0x380 net/core/dev.c:1544
 rollback_registered_many+0x2f5/0xa40 net/core/dev.c:8721
 rollback_registered+0xd2/0x160 net/core/dev.c:8789
 unregister_netdevice_queue net/core/dev.c:9888 [inline]
 unregister_netdevice_queue+0x199/0x2e0 net/core/dev.c:9881
 unregister_netdevice include/linux/netdevice.h:2674 [inline]
 __tun_detach+0xad3/0xb90 drivers/net/tun.c:723
 tun_detach drivers/net/tun.c:740 [inline]
 tun_chr_close+0x71/0xb0 drivers/net/tun.c:3455
 __fput+0x1e1/0x520 fs/file_table.c:280
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888098e49480 of 8 bytes by task 10 on cpu 1:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x210 kernel/time/timer.c:540
 __internal_add_timer+0x4f/0x60 kernel/time/timer.c:553
 internal_add_timer kernel/time/timer.c:595 [inline]
 __mod_timer kernel/time/timer.c:1053 [inline]
 schedule_timeout+0x2a0/0x6e0 kernel/time/timer.c:1894
 rcu_gp_fqs_loop+0x37c/0x580 kernel/rcu/tree.c:1661
 rcu_gp_kthread+0x143/0x230 kernel/rcu/tree.c:1821
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10 Comm: rcu_preempt Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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