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BUG: KCSAN: data-race in wq_watchdog_reset_touched / wq_watchdog_touch

write to 0xffff88812bf172c8 of 8 bytes by task 7248 on cpu 1:
 wq_watchdog_touch+0x61/0xae kernel/workqueue.c:5759
 touch_softlockup_watchdog+0x2a/0x40 kernel/watchdog.c:283
 touch_nmi_watchdog include/linux/nmi.h:135 [inline]
 wait_for_xmitr+0x6f/0x1b0 drivers/tty/serial/8250/8250_port.c:1978
 serial8250_console_putchar+0x28/0x50 drivers/tty/serial/8250/8250_port.c:3110
 uart_console_write+0x9b/0xd0 drivers/tty/serial/serial_core.c:1928
 serial8250_console_write+0x3a0/0x500 drivers/tty/serial/8250/8250_port.c:3174
 univ8250_console_write+0x47/0x60 drivers/tty/serial/8250/8250_core.c:587
 call_console_drivers kernel/printk/printk.c:1791 [inline]
 console_unlock+0x935/0xb80 kernel/printk/printk.c:2473
 vprintk_emit+0x38f/0x4e0 kernel/printk/printk.c:1996
 vprintk_default+0x31/0x50 kernel/printk/printk.c:2023
 vprintk_func+0x85/0x140 kernel/printk/printk_safe.c:386
 printk+0x69/0x91 kernel/printk/printk.c:2056
 vlan_device_event.cold+0x18/0x2c net/8021q/vlan.c:385
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:95

write to 0xffff88812bf172c8 of 8 bytes by interrupt on cpu 0:
 wq_watchdog_reset_touched+0x8c/0xe0 kernel/workqueue.c:5699
 wq_watchdog_timer_fn+0x270/0x2b0 kernel/workqueue.c:5752
 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0x912/0xd20 kernel/time/timer.c:1788
 __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:536 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 rep_nop arch/x86/include/asm/processor.h:650 [inline]
 cpu_relax arch/x86/include/asm/processor.h:655 [inline]
 mutex_spin_on_owner+0x15d/0x1a0 kernel/locking/mutex.c:579
 mutex_optimistic_spin kernel/locking/mutex.c:673 [inline]
 __mutex_lock_common kernel/locking/mutex.c:959 [inline]
 __mutex_lock.isra.0+0x3ab/0x740 kernel/locking/mutex.c:1103
 __mutex_lock_slowpath+0x1f/0x30 kernel/locking/mutex.c:1364
 mutex_lock+0x2d/0x40 kernel/locking/mutex.c:284
 rtnl_lock+0x1e/0x30 net/core/rtnetlink.c:72

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_dad_work
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