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

read to 0xffffffff85cb2790 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:1292
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x288/0x600 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1638
 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
 find_watchpoint kernel/kcsan/core.c:55 [inline]
 __kcsan_check_watchpoint+0x66/0x180 kernel/kcsan/core.c:266
 __tsan_read8+0x15/0x30 kernel/kcsan/kcsan.c:36
 ip_hdr include/linux/ip.h:21 [inline]
 ipt_do_table+0x8e/0xe60 net/ipv4/netfilter/ip_tables.c:244
 iptable_filter_hook+0x4a/0x60 net/ipv4/netfilter/iptable_filter.c:37
 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_local_deliver+0x1e5/0x210 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

write to 0xffffffff85cb2790 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:1292
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x288/0x600 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1638
 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
 _copy_to_iter+0x1e6/0xa20 lib/iov_iter.c:610
 copy_to_iter include/linux/uio.h:138 [inline]
 simple_copy_to_iter+0x3f/0x60 net/core/datagram.c:515
 __skb_datagram_iter+0x23b/0x460 net/core/datagram.c:445
 skb_copy_datagram_iter+0x66/0x170 net/core/datagram.c:529
 skb_copy_datagram_msg include/linux/skbuff.h:3471 [inline]
 tcp_recvmsg+0x106c/0x1a30 net/ipv4/tcp.c:2133
 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838
 sock_recvmsg_nosec net/socket.c:871 [inline]
 sock_recvmsg net/socket.c:889 [inline]
 sock_recvmsg+0x92/0xb0 net/socket.c:885

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7255 Comm: syz-fuzzer Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================