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BUG: KCSAN: data-race in n_tty_flush_buffer / n_tty_lookahead_flow_ctrl

write to 0xffffc90000ebf270 of 8 bytes by task 8404 on cpu 1:
 reset_buffer_flags drivers/tty/n_tty.c:328 [inline]
 n_tty_flush_buffer+0x9f/0x190 drivers/tty/n_tty.c:359
 tty_ldisc_hangup+0x72/0x370 drivers/tty/tty_ldisc.c:699
 __tty_hangup+0x3c6/0x540 drivers/tty/tty_io.c:630
 tty_vhangup+0x17/0x20 drivers/tty/tty_io.c:700
 pty_close+0x262/0x280 drivers/tty/pty.c:79
 tty_release+0x20c/0x940 drivers/tty/tty_io.c:1760
 __fput+0x192/0x6f0 fs/file_table.c:422
 ____fput+0x15/0x20 fs/file_table.c:450
 task_work_run+0x13a/0x1a0 kernel/task_work.c:222
 get_signal+0xeee/0x1080 kernel/signal.c:2689
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read-write to 0xffffc90000ebf270 of 8 bytes by task 11 on cpu 0:
 n_tty_lookahead_flow_ctrl+0x48/0x130 drivers/tty/n_tty.c:1507
 tty_port_default_lookahead_buf+0x8a/0xc0 drivers/tty/tty_port.c:59
 lookahead_bufs drivers/tty/tty_buffer.c:428 [inline]
 flush_to_ldisc+0x31c/0x410 drivers/tty/tty_buffer.c:498
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x700 kernel/workqueue.c:3390
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x0000000000000006 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11 Comm: kworker/u8:0 Not tainted 6.10.0-syzkaller-10729-g3c3ff7be9729 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Workqueue: events_unbound flush_to_ldisc
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