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BUG: KCSAN: data-race in run_timer_softirq / try_to_del_timer_sync

write to 0xffff88812c01dc88 of 8 bytes by interrupt on cpu 0:
 expire_timers kernel/time/timer.c:1451 [inline]
 __run_timers kernel/time/timer.c:1774 [inline]
 __run_timers kernel/time/timer.c:1741 [inline]
 run_timer_softirq+0xb1c/0xbd0 kernel/time/timer.c:1787
 __do_softirq+0x118/0x34a kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082
 do_softirq.part.0+0x66/0x70 kernel/softirq.c:337
 do_softirq kernel/softirq.c:329 [inline]
 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:189
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 get_next_corpse net/netfilter/nf_conntrack_core.c:2150 [inline]
 nf_ct_iterate_cleanup+0x127/0x2e0 net/netfilter/nf_conntrack_core.c:2173
 nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2258 [inline]
 nf_ct_iterate_cleanup_net+0xe2/0xf0 net/netfilter/nf_conntrack_core.c:2243
 masq_device_event+0x84/0xa0 net/netfilter/nf_nat_masquerade.c:88
 notifier_call_chain+0xda/0x160 kernel/notifier.c:83
 __raw_notifier_call_chain kernel/notifier.c:361 [inline]
 raw_notifier_call_chain+0x33/0x50 kernel/notifier.c:368
 call_netdevice_notifiers_info net/core/dev.c:1948 [inline]
 call_netdevice_notifiers_info+0x96/0x110 net/core/dev.c:1933
 call_netdevice_notifiers_extack net/core/dev.c:1960 [inline]
 call_netdevice_notifiers net/core/dev.c:1974 [inline]
 dev_close_many+0x251/0x390 net/core/dev.c:1549
 rollback_registered_many+0x2f7/0xa00 net/core/dev.c:8803
 unregister_netdevice_many net/core/dev.c:9986 [inline]
 unregister_netdevice_many+0x5d/0x230 net/core/dev.c:9981
 __rtnl_newlink+0xe8c/0xfb0 net/core/rtnetlink.c:3374
 rtnl_newlink+0x5f/0x90 net/core/rtnetlink.c:3391
 rtnetlink_rcv_msg+0x1d0/0x4e0 net/core/rtnetlink.c:5454
 netlink_rcv_skb+0xaf/0x260 net/netlink/af_netlink.c:2469
 rtnetlink_rcv+0x22/0x30 net/core/rtnetlink.c:5472
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x390/0x4c0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x4cf/0x8a0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x98/0xc0 net/socket.c:672
 ____sys_sendmsg+0x493/0x4c0 net/socket.c:2362
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2416
 __sys_sendmsg+0x9b/0x150 net/socket.c:2449
 __do_sys_sendmsg net/socket.c:2458 [inline]
 __se_sys_sendmsg net/socket.c:2456 [inline]
 __x64_sys_sendmsg+0x4c/0x60 net/socket.c:2456
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812c01dc88 of 8 bytes by task 10 on cpu 1:
 try_to_del_timer_sync+0x40/0xb0 kernel/time/timer.c:1226
 del_timer_sync+0x68/0xa0 kernel/time/timer.c:1366
 schedule_timeout+0x106/0x280 kernel/time/timer.c:1899
 rcu_gp_fqs_loop+0x34c/0x540 kernel/rcu/tree.c:1674
 rcu_gp_kthread+0x113/0x1e0 kernel/rcu/tree.c:1836
 kthread+0x203/0x230 kernel/kthread.c:268
 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 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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