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

read-write to 0xffff8881000670a8 of 8 bytes by interrupt on cpu 1:
 wq_worker_tick+0x66/0x3c0 kernel/workqueue.c:1333
 scheduler_tick+0x13e/0x1d0 kernel/sched/core.c:5672
 update_process_times+0xf5/0x110 kernel/time/timer.c:2076
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x244/0x2c0 kernel/time/tick-sched.c:1492
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x217/0x700 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x20d/0x7b0 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1063 [inline]
 __sysvec_apic_timer_interrupt+0x52/0x190 arch/x86/kernel/apic/apic.c:1080
 sysvec_apic_timer_interrupt+0x68/0x80 arch/x86/kernel/apic/apic.c:1074
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
 kcsan_setup_watchpoint+0x3fe/0x410 kernel/kcsan/core.c:705
 commit_echoes drivers/tty/n_tty.c:762 [inline]
 n_tty_receive_char+0x4b1/0x670 drivers/tty/n_tty.c:1442
 n_tty_receive_buf_standard+0x4bd/0x2e20 drivers/tty/n_tty.c:1611
 __receive_buf drivers/tty/n_tty.c:1635 [inline]
 n_tty_receive_buf_common+0x7e5/0xbc0 drivers/tty/n_tty.c:1734
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1780
 tty_ldisc_receive_buf+0x60/0xe0 drivers/tty/tty_buffer.c:387
 tty_port_default_receive_buf+0x59/0x90 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x1ca/0x400 drivers/tty/tty_buffer.c:495
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

read-write to 0xffff8881000670a8 of 8 bytes by interrupt on cpu 0:
 wq_worker_tick+0x66/0x3c0 kernel/workqueue.c:1333
 scheduler_tick+0x13e/0x1d0 kernel/sched/core.c:5672
 update_process_times+0xf5/0x110 kernel/time/timer.c:2076
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x244/0x2c0 kernel/time/tick-sched.c:1492
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x217/0x700 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x20d/0x7b0 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1063 [inline]
 __sysvec_apic_timer_interrupt+0x52/0x190 arch/x86/kernel/apic/apic.c:1080
 sysvec_apic_timer_interrupt+0x68/0x80 arch/x86/kernel/apic/apic.c:1074
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
 is_atomic kernel/kcsan/core.c:264 [inline]
 should_watch kernel/kcsan/core.c:277 [inline]
 check_access kernel/kcsan/core.c:752 [inline]
 __tsan_read8+0xfd/0x180 kernel/kcsan/core.c:1025
 n_tty_process_echo_ops drivers/tty/n_tty.c:595 [inline]
 __process_echoes+0x153/0x6a0 drivers/tty/n_tty.c:714
 flush_echoes drivers/tty/n_tty.c:812 [inline]
 __receive_buf drivers/tty/n_tty.c:1637 [inline]
 n_tty_receive_buf_common+0x8e6/0xbc0 drivers/tty/n_tty.c:1734
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1780
 tty_ldisc_receive_buf+0x60/0xe0 drivers/tty/tty_buffer.c:387
 tty_port_default_receive_buf+0x59/0x90 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x1ca/0x400 drivers/tty/tty_buffer.c:495
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x00000000000cf850 -> 0x00000000000d1f60

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3227 Comm: kworker/u4:7 Not tainted 6.6.0-rc4-syzkaller-00284-gb9ddbb0cde2a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: events_unbound flush_to_ldisc
==================================================================