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BUG: KCSAN: data-race in __mod_timer / timer_clear_idle

write to 0xffff88812c01cb24 of 1 bytes by task 0 on cpu 0:
 timer_clear_idle+0x2e/0x40 kernel/time/timer.c:1675
 tick_nohz_idle_retain_tick+0x3e/0x40 kernel/time/tick-sched.c:1004
 cpuidle_idle_call kernel/sched/idle.c:203 [inline]
 do_idle+0x290/0x320 kernel/sched/idle.c:269
 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:365
 rest_init+0xd8/0xe0 init/main.c:705
 arch_call_rest_init+0xa/0xb
 start_kernel+0x608/0x6d0 init/main.c:1043
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

read to 0xffff88812c01cb24 of 1 bytes by interrupt on cpu 1:
 forward_timer_base kernel/time/timer.c:891 [inline]
 __mod_timer+0xb87/0xf00 kernel/time/timer.c:983
 mod_timer+0x1b/0x20 kernel/time/timer.c:1100
 sk_reset_timer+0x1f/0xa0 net/core/sock.c:2951
 tcp_send_delayed_ack+0x191/0x250 net/ipv4/tcp_output.c:3748
 __tcp_ack_snd_check+0x326/0x500 net/ipv4/tcp_input.c:5285
 tcp_rcv_established+0xed6/0x1110 net/ipv4/tcp_input.c:5710
 tcp_v4_do_rcv+0x25e/0x480 net/ipv4/tcp_ipv4.c:1629
 tcp_v4_rcv+0x2159/0x23e0 net/ipv4/tcp_ipv4.c:2011
 ip_protocol_deliver_rcu+0x1f9/0x400 net/ipv4/ip_input.c:204
 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ip_local_deliver+0x1d6/0x2a0 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:441 [inline]
 ip_sublist_rcv_finish net/ipv4/ip_input.c:550 [inline]
 ip_list_rcv_finish net/ipv4/ip_input.c:600 [inline]
 ip_sublist_rcv+0x4d4/0x5a0 net/ipv4/ip_input.c:608
 ip_list_rcv+0x262/0x290 net/ipv4/ip_input.c:643
 __netif_receive_skb_list_ptype net/core/dev.c:5322 [inline]
 __netif_receive_skb_list_core+0x34b/0x450 net/core/dev.c:5370
 __netif_receive_skb_list+0x298/0x310 net/core/dev.c:5422
 netif_receive_skb_list_internal+0xda/0x330 net/core/dev.c:5529
 gro_normal_list net/core/dev.c:5640 [inline]
 gro_normal_one net/core/dev.c:5652 [inline]
 napi_skb_finish net/core/dev.c:5980 [inline]
 napi_gro_receive+0x329/0x5a0 net/core/dev.c:6012
 receive_buf+0x7a4/0xcf0 drivers/net/virtio_net.c:1082
 virtnet_receive drivers/net/virtio_net.c:1346 [inline]
 virtnet_poll+0x2fa/0x780 drivers/net/virtio_net.c:1451
 napi_poll+0x154/0x480 net/core/dev.c:6682
 net_rx_action+0x1ba/0x530 net/core/dev.c:6750
 __do_softirq+0x198/0x360 kernel/softirq.c:292
 run_ksoftirqd+0x2f/0x60 kernel/softirq.c:630
 smpboot_thread_fn+0x347/0x530 kernel/smpboot.c:165
 kthread+0x210/0x220 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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