==================================================================
BUG: KCSAN: data-race in tick_sched_do_timer / tick_sched_do_timer

write to 0xffffffff85caf310 of 4 bytes by interrupt on cpu 0:
 tick_sched_do_timer+0xc0/0xe0 kernel/time/tick-sched.c:132
 tick_sched_timer+0x43/0xe0 kernel/time/tick-sched.c:1289
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x288/0x600 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 check_kcov_mode kernel/kcov.c:68 [inline]
 __sanitizer_cov_trace_pc+0x1a/0x50 kernel/kcov.c:102
 ip_hdr include/linux/ip.h:21 [inline]
 ip_select_ident_segs include/net/ip.h:499 [inline]
 __ip_queue_xmit+0x2d2/0xa40 net/ipv4/ip_output.c:525
 ip_queue_xmit+0x45/0x60 include/net/ip.h:236
 __tcp_transmit_skb+0xdeb/0x1cd0 net/ipv4/tcp_output.c:1158
 __tcp_send_ack+0x246/0x300 net/ipv4/tcp_output.c:3685
 tcp_send_ack+0x34/0x40 net/ipv4/tcp_output.c:3691
 tcp_cleanup_rbuf+0x130/0x360 net/ipv4/tcp.c:1575
 tcp_recvmsg+0x633/0x1a30 net/ipv4/tcp.c:2179

read to 0xffffffff85caf310 of 4 bytes by interrupt on cpu 1:
 tick_sched_do_timer+0x33/0xe0 kernel/time/tick-sched.c:128
 tick_sched_timer+0x43/0xe0 kernel/time/tick-sched.c:1289
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x288/0x600 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 __read_once_size include/linux/compiler.h:227 [inline]
 arch_atomic64_read arch/x86/include/asm/atomic64_64.h:22 [inline]
 atomic64_read include/asm-generic/atomic-instrumented.h:925 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:28 [inline]
 find_watchpoint kernel/kcsan/core.c:85 [inline]
 __kcsan_check_watchpoint+0xbb/0x180 kernel/kcsan/core.c:322
 __tsan_write8+0x18/0x40 kernel/kcsan/kcsan.c:31
 ipt_do_table+0x702/0xe40 net/ipv4/netfilter/ip_tables.c:299
 iptable_mangle_hook+0x7a/0x260 net/ipv4/netfilter/iptable_mangle.c:82
 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
 nf_hook_slow+0x83/0x160 net/netfilter/core.c:512
 nf_hook include/linux/netfilter.h:260 [inline]
 NF_HOOK include/linux/netfilter.h:303 [inline]
 ip_rcv+0x12f/0x1a0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================