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

write to 0xffffc90016719000 of 8 bytes by task 10801 on cpu 0:
 put_tty_queue drivers/tty/n_tty.c:320 [inline]
 n_tty_receive_char_fast drivers/tty/n_tty.c:1451 [inline]
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1609 [inline]
 __receive_buf drivers/tty/n_tty.c:1644 [inline]
 n_tty_receive_buf_common+0x14a8/0x1e70 drivers/tty/n_tty.c:1742
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1771
 tiocsti drivers/tty/tty_io.c:2196 [inline]
 tty_ioctl+0x8cd/0xfc0 drivers/tty/tty_io.c:2572
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl fs/ioctl.c:753 [inline]
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl+0xc9/0x130 fs/ioctl.c:760
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:760
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffc90016719000 of 8 bytes by task 7 on cpu 1:
 n_tty_receive_char_fast drivers/tty/n_tty.c:1446 [inline]
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1609 [inline]
 __receive_buf drivers/tty/n_tty.c:1644 [inline]
 n_tty_receive_buf_common+0xf94/0x1e70 drivers/tty/n_tty.c:1742
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1777
 tty_ldisc_receive_buf+0x61/0xf0 drivers/tty/tty_buffer.c:461
 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:38
 receive_buf drivers/tty/tty_buffer.c:481 [inline]
 flush_to_ldisc+0x1b5/0x2b0 drivers/tty/tty_buffer.c:533
 process_one_work+0x3cb/0x990 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x210/0x220 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7 Comm: kworker/u4:0 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
==================================================================