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BUG: KCSAN: data-race in n_tty_flush_buffer / n_tty_lookahead_flow_ctrl

write to 0xffffc90002903270 of 8 bytes by task 32265 on cpu 0:
 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+0x3b1/0x530 drivers/tty/tty_io.c:624
 tty_vhangup drivers/tty/tty_io.c:694 [inline]
 tty_ioctl+0x607/0xbe0 drivers/tty/tty_io.c:2742
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
 x64_sys_call+0x1690/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read-write to 0xffffc90002903270 of 8 bytes by task 29029 on cpu 1:
 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:3236 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3317
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3398
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x0000000000003287 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 29029 Comm: kworker/u8:30 Not tainted 6.13.0-syzkaller-08265-g9c5968db9e62 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: events_unbound flush_to_ldisc
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