syzbot

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BUG: KCSAN: data-race in n_tty_kick_worker / n_tty_receive_buf_common

read to 0xffffc900081fd05c of 1 bytes by task 15579 on cpu 0:
 n_tty_kick_worker+0x2d/0x160 drivers/tty/n_tty.c:204
 n_tty_read+0xfbc/0x1070 drivers/tty/n_tty.c:2186
 iterate_tty_read drivers/tty/tty_io.c:858 [inline]
 tty_read+0x19c/0x430 drivers/tty/tty_io.c:933
 call_read_iter include/linux/fs.h:2068 [inline]
 do_iter_readv_writev+0x2fb/0x380 fs/read_write.c:723
 do_iter_read+0x192/0x5d0 fs/read_write.c:786
 vfs_readv fs/read_write.c:906 [inline]
 do_readv+0x171/0x2c0 fs/read_write.c:943
 __do_sys_readv fs/read_write.c:1034 [inline]
 __se_sys_readv fs/read_write.c:1031 [inline]
 __x64_sys_readv+0x41/0x50 fs/read_write.c:1031
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffffc900081fd05c of 1 bytes by task 15573 on cpu 1:
 n_tty_receive_buf_common+0x370/0x4e70 drivers/tty/n_tty.c:1635
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1680
 tty_ldisc_receive_buf+0x5b/0xf0 drivers/tty/tty_buffer.c:451
 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:471 [inline]
 flush_to_ldisc+0x1c5/0x300 drivers/tty/tty_buffer.c:521
 process_one_work+0x3f6/0x960 kernel/workqueue.c:2307
 worker_thread+0x616/0xa70 kernel/workqueue.c:2454
 kthread+0x1bf/0x1e0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15573 Comm: kworker/u4:127 Not tainted 5.17.0-rc4-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
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