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BUG: KCSAN: data-race in timer_clear_idle / trigger_dyntick_cpu.isra.0

write to 0xffff88812c01dbe4 of 1 bytes by task 0 on cpu 0:
 timer_clear_idle+0x42/0x50 kernel/time/timer.c:1676
 tick_nohz_restart_sched_tick kernel/time/tick-sched.c:854 [inline]
 __tick_nohz_idle_restart_tick+0x36/0x1b0 kernel/time/tick-sched.c:1155
 tick_nohz_idle_exit+0x1af/0x1e0 kernel/time/tick-sched.c:1196
 do_idle+0xb1/0x290 kernel/sched/idle.c:282
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 rest_init+0xec/0xf6 init/main.c:632
 arch_call_rest_init+0x17/0x37
 start_kernel+0xcd4/0xcfc init/main.c:971
 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490
 x86_64_start_kernel+0x72/0x76 arch/x86/kernel/head64.c:471
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

read to 0xffff88812c01dbe4 of 1 bytes by interrupt on cpu 1:
 trigger_dyntick_cpu.isra.0+0x75/0x100 kernel/time/timer.c:577
 internal_add_timer kernel/time/timer.c:596 [inline]
 __mod_timer kernel/time/timer.c:1054 [inline]
 mod_timer+0x3b1/0x780 kernel/time/timer.c:1101
 sk_reset_timer+0x2d/0xd0 net/core/sock.c:2840
 tcp_send_delayed_ack+0x21d/0x2b0 net/ipv4/tcp_output.c:3734
 __tcp_ack_snd_check+0x3d8/0x580 net/ipv4/tcp_input.c:5268
 tcp_ack_snd_check net/ipv4/tcp_input.c:5309 [inline]
 tcp_rcv_established+0x750/0xf50 net/ipv4/tcp_input.c:5730
 tcp_v4_do_rcv+0x3b5/0x520 net/ipv4/tcp_ipv4.c:1619
 tcp_v4_rcv+0x1c30/0x1e20 net/ipv4/tcp_ipv4.c:2001
 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_sublist_rcv_finish+0xf8/0x140 net/ipv4/ip_input.c:549
 ip_list_rcv_finish net/ipv4/ip_input.c:599 [inline]
 ip_sublist_rcv+0x418/0x550 net/ipv4/ip_input.c:607
 ip_list_rcv+0x2f5/0x322 net/ipv4/ip_input.c:642
 __netif_receive_skb_list_ptype net/core/dev.c:5241 [inline]
 __netif_receive_skb_list_ptype net/core/dev.c:5230 [inline]
 __netif_receive_skb_list_core+0x350/0x5c0 net/core/dev.c:5289
 __netif_receive_skb_list net/core/dev.c:5341 [inline]
 netif_receive_skb_list_internal+0x5d8/0x830 net/core/dev.c:5436
 gro_normal_list.part.0+0x3a/0xb0 net/core/dev.c:5547
 gro_normal_list net/core/dev.c:5560 [inline]
 gro_normal_one+0x162/0x170 net/core/dev.c:5559
 napi_skb_finish net/core/dev.c:5887 [inline]
 napi_gro_receive+0x288/0x300 net/core/dev.c:5919
 receive_buf+0x284/0x30d0 drivers/net/virtio_net.c:1061
 virtnet_receive drivers/net/virtio_net.c:1323 [inline]
 virtnet_poll+0x436/0x7d0 drivers/net/virtio_net.c:1428
 napi_poll net/core/dev.c:6582 [inline]
 net_rx_action+0x3ae/0xa90 net/core/dev.c:6650
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 do_IRQ+0x81/0x130 arch/x86/kernel/irq.c:263
 ret_from_intr+0x0/0x21
 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:686
 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x1c2/0x290 kernel/sched/idle.c:269
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 start_secondary+0x168/0x1b0 arch/x86/kernel/smpboot.c:264
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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