syzbot

netlink:[ 1001.787435][ T5840] ==================================================================
BUG: KCSAN: data-race in wq_watchdog_reset_touched / wq_watchdog_touch

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+0xc7a/0xcd0 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
 __tsan_read8+0x7/0x1f0 kernel/kcsan/core.c:530
 unmap_single_vma+0x144/0x200 mm/memory.c:1282
 unmap_vmas+0xda/0x1a0 mm/memory.c:1314
 exit_mmap+0x13e/0x300 mm/mmap.c:3161
 __mmput kernel/fork.c:1079 [inline]
 mmput+0xea/0x280 kernel/fork.c:1100
 exit_mm kernel/exit.c:485 [inline]
 do_exit+0x4c9/0x18f0 kernel/exit.c:804
 do_group_exit+0xb4/0x1c0 kernel/exit.c:921
 __do_sys_exit_group kernel/exit.c:932 [inline]
 __se_sys_exit_group kernel/exit.c:930 [inline]
 __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:930
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812bf172c8 of 8 bytes by task 5840 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
 __nla_validate_parse.cold+0x24/0x4f lib/nlattr.c:393
 __nla_parse+0x4c/0x70 lib/nlattr.c:478
 nla_parse_nested_deprecated include/net/netlink.h:1166 [inline]
 fq_change+0x77/0x840 net/sched/sch_fq.c:765
 fq_init+0x262/0x2a4 net/sched/sch_fq.c:892
 qdisc_create+0x322/0x990 net/sched/sch_api.c:1237
 tc_modify_qdisc+0x288/0x10c0 net/sched/sch_api.c:1652
 rtnetlink_rcv_msg+0x1d3/0x500 net/core/rtnetlink.c:5224
 netlink_rcv_skb+0xb0/0x260 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:5242
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x354/0x430 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x456/0x770 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:657
 ___sys_sendmsg+0x2b7/0x5d0 net/socket.c:2311
 __sys_sendmmsg+0x123/0x350 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg net/socket.c:2439 [inline]
 __x64_sys_sendmmsg+0x64/0x80 net/socket.c:2439
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5840 Comm: syz-executor.0 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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