syzbot

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BUG: KCSAN: data-race in __tty_hangup / tty_hung_up_p

write to 0xffff88812ace5b28 of 8 bytes by task 530 on cpu 0:
 __tty_hangup+0x23a/0x610 drivers/tty/tty_io.c:616
 tty_vhangup+0x13/0x20 drivers/tty/tty_io.c:698
 pty_close+0x298/0x2c0 drivers/tty/pty.c:79
 tty_release+0x255/0xa00 drivers/tty/tty_io.c:1679
 __fput+0x1df/0x460 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:135
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:139 [inline]
 exit_to_user_mode_prepare+0x1bb/0x220 kernel/entry/common.c:166
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:241
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812ace5b28 of 8 bytes by task 536 on cpu 1:
 tty_hung_up_p+0x1c/0x40 drivers/tty/tty_io.c:748
 n_tty_write+0x292/0xae0 drivers/tty/n_tty.c:2327
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x3fc/0x5e0 drivers/tty/tty_io.c:1046
 vfs_write+0x1d6/0x690 fs/read_write.c:576
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 536 Comm: syz-executor.1 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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