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BUG: KCSAN: data-race in __kernfs_remove / cleanup_glue_dir

write to 0xffff88812b1c9240 of 8 bytes by task 8732 on cpu 1:
 kernfs_unlink_sibling fs/kernfs/dir.c:396 [inline]
 __kernfs_remove+0x592/0x6a0 fs/kernfs/dir.c:1331
 kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1357
 sysfs_remove_dir+0x7a/0x90 fs/sysfs/dir.c:102
 __kobject_del lib/kobject.c:620 [inline]
 kobject_del+0xbe/0x110 lib/kobject.c:643
 device_del+0x9e7/0xa40 drivers/base/core.c:3115
 device_unregister+0x11/0x30 drivers/base/core.c:3135
 bdi_unregister+0x2b9/0x350 mm/backing-dev.c:877
 release_bdi mm/backing-dev.c:893 [inline]
 kref_put include/linux/kref.h:65 [inline]
 bdi_put+0x8a/0x190 mm/backing-dev.c:901
 generic_shutdown_super+0x1c4/0x210 fs/super.c:478
 kill_anon_super+0x23/0x40 fs/super.c:1108
 fuse_kill_sb_anon+0xe2/0x110 fs/fuse/inode.c:1361
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
 exit_to_user_mode_prepare+0x1b2/0x210 kernel/entry/common.c:190
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:265
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812b1c9240 of 8 bytes by task 14441 on cpu 0:
 kobject_has_children include/linux/kobject.h:135 [inline]
 cleanup_glue_dir+0xce/0x140 drivers/base/core.c:2625
 device_del+0x9f2/0xa40 drivers/base/core.c:3116
 device_unregister+0x11/0x30 drivers/base/core.c:3135
 bdi_unregister+0x2b9/0x350 mm/backing-dev.c:877
 release_bdi mm/backing-dev.c:893 [inline]
 kref_put include/linux/kref.h:65 [inline]
 bdi_put+0x8a/0x190 mm/backing-dev.c:901
 generic_shutdown_super+0x1c4/0x210 fs/super.c:478
 kill_anon_super+0x23/0x40 fs/super.c:1108
 fuse_kill_sb_anon+0xe2/0x110 fs/fuse/inode.c:1361
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
 exit_to_user_mode_prepare+0x1b2/0x210 kernel/entry/common.c:190
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:265
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14441 Comm: syz-executor.4 Not tainted 5.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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