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BUG: KCSAN: data-race in __tty_hangup / do_sys_poll

write to 0xffff8881225ffd28 of 8 bytes by task 11531 on cpu 1:
 __tty_hangup+0x160/0x440 drivers/tty/tty_io.c:616
 tty_vhangup+0x1d/0x30 drivers/tty/tty_io.c:698
 pty_close+0x248/0x2d0 drivers/tty/pty.c:79
 tty_release+0x281/0x8e0 drivers/tty/tty_io.c:1679
 __fput+0x1e9/0x500 fs/file_table.c:280
 ____fput+0x1b/0x30 fs/file_table.c:313
 task_work_run+0xba/0x120 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x38b/0x3b0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881225ffd28 of 8 bytes by task 11532 on cpu 0:
 vfs_poll include/linux/poll.h:88 [inline]
 do_pollfd fs/select.c:859 [inline]
 do_poll fs/select.c:907 [inline]
 do_sys_poll+0x47f/0x990 fs/select.c:1001
 __do_sys_ppoll fs/select.c:1101 [inline]
 __se_sys_ppoll fs/select.c:1081 [inline]
 __x64_sys_ppoll+0x156/0x190 fs/select.c:1081
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11532 Comm: syz-executor.3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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