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

write to 0xffff88812bf1b6e4 of 1 bytes by task 0 on cpu 1:
 timer_clear_idle+0x42/0x50 kernel/time/timer.c:1590
 tick_nohz_restart_sched_tick kernel/time/tick-sched.c:836 [inline]
 __tick_nohz_idle_restart_tick+0x36/0x1b0 kernel/time/tick-sched.c:1137
 tick_nohz_idle_exit+0x1af/0x1e0 kernel/time/tick-sched.c:1178
 do_idle+0xb0/0x2c0 kernel/sched/idle.c:276
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:354
 start_secondary+0x207/0x260 arch/x86/kernel/smpboot.c:264
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241

read to 0xffff88812bf1b6e4 of 1 bytes by interrupt on cpu 0:
 trigger_dyntick_cpu.isra.0+0x75/0x100 kernel/time/timer.c:573
 internal_add_timer kernel/time/timer.c:592 [inline]
 __mod_timer kernel/time/timer.c:1049 [inline]
 mod_timer+0x312/0x7a0 kernel/time/timer.c:1096
 sk_reset_timer+0x2d/0x70 net/core/sock.c:2830
 tcp_send_delayed_ack+0x21d/0x2b0 net/ipv4/tcp_output.c:3648
 __tcp_ack_snd_check+0x3c8/0x4e0 net/ipv4/tcp_input.c:5202
 tcp_ack_snd_check net/ipv4/tcp_input.c:5243 [inline]
 tcp_rcv_established+0x750/0xf50 net/ipv4/tcp_input.c:5664
 tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1542
 tcp_v4_rcv+0x1a03/0x1bf0 net/ipv4/tcp_ipv4.c:1923
 ip_protocol_deliver_rcu+0x51/0x470 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================