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BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff888124417890 of 8 bytes by task 3921 on cpu 1:
 list_add_tail_lockless fs/eventpoll.c:1158 [inline]
 ep_poll_callback+0x29c/0x510 fs/eventpoll.c:1248
 __wake_up_common+0xbc/0x130 kernel/sched/wait.c:93
 __wake_up_common_lock kernel/sched/wait.c:123 [inline]
 __wake_up_sync_key+0x83/0xc0 kernel/sched/wait.c:190
 sock_def_readable+0x61/0xe0 net/core/sock.c:2909
 __netlink_sendskb net/netlink/af_netlink.c:1250 [inline]
 netlink_broadcast_deliver net/netlink/af_netlink.c:1382 [inline]
 do_one_broadcast net/netlink/af_netlink.c:1467 [inline]
 netlink_broadcast_filtered+0x991/0xb40 net/netlink/af_netlink.c:1511
 netlink_broadcast+0x35/0x50 net/netlink/af_netlink.c:1535
 uevent_net_broadcast_untagged lib/kobject_uevent.c:330 [inline]
 kobject_uevent_net_broadcast lib/kobject_uevent.c:408 [inline]
 kobject_uevent_env+0x8c6/0xc40 lib/kobject_uevent.c:592
 kobject_uevent+0x18/0x20 lib/kobject_uevent.c:641
 device_del+0xa13/0xa80 drivers/base/core.c:2887
 del_gendisk+0x7be/0x800 block/genhd.c:938
 sd_remove+0x93/0x100 drivers/scsi/sd.c:3471
 __device_release_driver drivers/base/dd.c:1108 [inline]
 device_release_driver_internal+0x32e/0x4b0 drivers/base/dd.c:1139
 device_release_driver+0x15/0x20 drivers/base/dd.c:1162
 bus_remove_device+0x1c6/0x210 drivers/base/bus.c:533
 device_del+0x502/0xa80 drivers/base/core.c:2877
 __scsi_remove_device+0x163/0x220 drivers/scsi/scsi_sysfs.c:1428
 scsi_forget_host+0x9b/0x100 drivers/scsi/scsi_scan.c:1871
 scsi_remove_host+0xd3/0x430 drivers/scsi/hosts.c:180
 quiesce_and_remove_host drivers/usb/storage/usb.c:864 [inline]
 usb_stor_disconnect+0xc8/0x120 drivers/usb/storage/usb.c:1084
 usb_unbind_interface+0x175/0x530 drivers/usb/core/driver.c:436
 __device_release_driver drivers/base/dd.c:1108 [inline]
 device_release_driver_internal+0x32e/0x4b0 drivers/base/dd.c:1139
 device_release_driver+0x15/0x20 drivers/base/dd.c:1162
 bus_remove_device+0x1c6/0x210 drivers/base/bus.c:533
 device_del+0x502/0xa80 drivers/base/core.c:2877
 usb_disable_device+0x24a/0x7a0 drivers/usb/core/message.c:1245
 usb_disconnect+0x206/0x4a0 drivers/usb/core/hub.c:2217
 hub_port_connect drivers/usb/core/hub.c:5059 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
 port_event drivers/usb/core/hub.c:5494 [inline]
 hub_event+0x13c9/0x2bd0 drivers/usb/core/hub.c:5576
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

read to 0xffff888124417890 of 8 bytes by task 5034 on cpu 0:
 list_empty_careful include/linux/list.h:300 [inline]
 ep_events_available fs/eventpoll.c:379 [inline]
 ep_poll fs/eventpoll.c:1855 [inline]
 do_epoll_wait+0x2e2/0x870 fs/eventpoll.c:2333
 __do_sys_epoll_wait fs/eventpoll.c:2343 [inline]
 __se_sys_epoll_wait fs/eventpoll.c:2340 [inline]
 __x64_sys_epoll_wait+0x4d/0x60 fs/eventpoll.c:2340
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5034 Comm: systemd-udevd Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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