syzbot

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BUG: KCSAN: data-race in device_del / mm_update_next_owner

write to 0xffff888009f46064 of 4 bytes by task 22491 on cpu 1:
 memalloc_noio_save include/linux/sched/mm.h:197 [inline]
 device_del+0x123/0x9a0 drivers/base/core.c:3087
 device_unregister+0x11/0x30 drivers/base/core.c:3148
 usb_remove_ep_devs+0x31/0x50 drivers/usb/core/endpoint.c:215
 usb_disconnect+0x353/0x4b0 drivers/usb/core/hub.c:2236
 hub_port_connect drivers/usb/core/hub.c:5073 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5362 [inline]
 port_event drivers/usb/core/hub.c:5508 [inline]
 hub_event+0x13bb/0x2b60 drivers/usb/core/hub.c:5590
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 process_scheduled_works kernel/workqueue.c:2334 [inline]
 worker_thread+0x7ef/0xb90 kernel/workqueue.c:2420
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff888009f46064 of 4 bytes by task 28626 on cpu 0:
 mm_update_next_owner+0x1e9/0x4c0 kernel/exit.c:387
 exit_mm+0x2ff/0x370 kernel/exit.c:485
 do_exit+0x3c2/0x15a0 kernel/exit.c:796
 do_group_exit+0x16f/0x170 kernel/exit.c:906
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:917
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:915
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:915
 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: 0 PID: 28626 Comm: syz-executor.4 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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