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BUG: KCSAN: data-race in tick_nohz_next_event / tick_sched_timer

write to 0xffffffff88164010 of 4 bytes by interrupt on cpu 1:
 tick_sched_do_timer kernel/time/tick-sched.c:141 [inline]
 tick_sched_timer+0x214/0x230 kernel/time/tick-sched.c:1321
 __run_hrtimer+0x154/0x4b0 kernel/time/hrtimer.c:1524
 __hrtimer_run_queues kernel/time/hrtimer.c:1588 [inline]
 hrtimer_interrupt+0x37c/0xa40 kernel/time/hrtimer.c:1650
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0xa3/0x280 arch/x86/kernel/apic/apic.c:1097
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_apic_timer_interrupt+0x80/0xd0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581
 arch_atomic64_read arch/x86/include/asm/atomic64_64.h:22 [inline]
 atomic64_read include/asm-generic/atomic-instrumented.h:838 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
 find_watchpoint kernel/kcsan/core.c:118 [inline]
 check_access kernel/kcsan/core.c:588 [inline]
 __tsan_read8+0x4a/0x180 kernel/kcsan/core.c:801
 ipv4_mtu+0xb8/0x200 net/ipv4/route.c:1319
 dst_mtu include/net/dst.h:198 [inline]
 ip_dst_mtu_maybe_forward include/net/ip.h:443 [inline]
 ip_skb_dst_mtu include/net/ip.h:454 [inline]
 __ip_finish_output+0x229/0x3e0 net/ipv4/ip_output.c:299
 ip_finish_output+0x39/0x160 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:290 [inline]
 ip_output+0xf6/0x1a0 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:443 [inline]
 ip_local_out net/ipv4/ip_output.c:125 [inline]
 __ip_queue_xmit+0x9b3/0x9e0 net/ipv4/ip_output.c:530
 ip_queue_xmit+0x34/0x40 net/ipv4/ip_output.c:544
 __tcp_transmit_skb+0x1320/0x1810 net/ipv4/tcp_output.c:1246
 tcp_transmit_skb net/ipv4/tcp_output.c:1264 [inline]
 tcp_write_xmit+0x1a7e/0x3f40 net/ipv4/tcp_output.c:2527
 __tcp_push_pending_frames+0x68/0x1c0 net/ipv4/tcp_output.c:2705
 tcp_push+0x2da/0x2f0 net/ipv4/tcp.c:733
 tcp_sendmsg_locked+0x1bf9/0x2200 net/ipv4/tcp.c:1411
 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1441
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg net/socket.c:671 [inline]
 sock_write_iter+0x1a1/0x200 net/socket.c:998
 call_write_iter include/linux/fs.h:1882 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x665/0x6f0 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff88164010 of 4 bytes by task 0 on cpu 0:
 tick_nohz_next_event+0x21d/0x310 kernel/time/tick-sched.c:754
 tick_nohz_get_sleep_length+0xca/0x140 kernel/time/tick-sched.c:1107
 menu_select+0x328/0x1030 drivers/cpuidle/governors/menu.c:283
 cpuidle_select+0x3d/0x50 drivers/cpuidle/cpuidle.c:317
 cpuidle_idle_call kernel/sched/idle.c:205 [inline]
 do_idle+0x1eb/0x310 kernel/sched/idle.c:276
 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:372
 rest_init+0xd8/0xe0 init/main.c:708
 arch_call_rest_init+0xa/0xb
 start_kernel+0x608/0x6d0 init/main.c:1048
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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