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BUG: KCSAN: data-race in device_del / mm_update_next_owner

write to 0xffff8881025e6024 of 4 bytes by task 10954 on cpu 0:
 memalloc_noio_save include/linux/sched/mm.h:197 [inline]
 device_del+0x123/0xa20 drivers/base/core.c:3089
 device_unregister drivers/base/core.c:3150 [inline]
 device_destroy+0x63/0xa0 drivers/base/core.c:3696
 tty_unregister_device+0x4e/0xd0 drivers/tty/tty_io.c:3188
 gsmld_detach_gsm drivers/tty/n_gsm.c:2407 [inline]
 gsmld_close+0x6c/0x140 drivers/tty/n_gsm.c:2476
 tty_ldisc_close drivers/tty/tty_ldisc.c:488 [inline]
 tty_ldisc_kill drivers/tty/tty_ldisc.c:636 [inline]
 tty_ldisc_hangup+0x35d/0x490 drivers/tty/tty_ldisc.c:755
 __tty_hangup+0x467/0x610 drivers/tty/tty_io.c:625
 tty_vhangup+0x13/0x20 drivers/tty/tty_io.c:698
 pty_close+0x272/0x290 drivers/tty/pty.c:79
 tty_release+0x255/0x9f0 drivers/tty/tty_io.c:1679
 __fput+0x243/0x4d0 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:151
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881025e6024 of 4 bytes by task 11232 on cpu 1:
 mm_update_next_owner+0x1e9/0x4c0 kernel/exit.c:387
 exit_mm+0x2b5/0x320 kernel/exit.c:482
 do_exit+0x3c2/0x15a0 kernel/exit.c:793
 do_group_exit+0x16f/0x170 kernel/exit.c:903
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:914
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:912
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:912
 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: 11232 Comm: syz-executor.1 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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