======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.5.3721/19895 is trying to acquire lock:
ffff88801c6af220 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_unlink_sibling+0xa3/0x320 fs/kernfs/dir.c:441

but task is already holding lock:
ffff88801c6af188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3d/0xf0 fs/kernfs/dir.c:1744

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #10 (&root->kernfs_rwsem){++++}-{4:4}:
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1590
       kernfs_add_one+0x38/0x850 fs/kernfs/dir.c:820
       kernfs_create_dir_ns+0xfc/0x1a0 fs/kernfs/dir.c:1125
       internal_create_group+0x36f/0xf40 fs/sysfs/group.c:176
       cpuhp_invoke_callback+0x3ab/0x9a0 kernel/cpu.c:194
       cpuhp_issue_call+0x1b8/0x970 kernel/cpu.c:2354
       __cpuhp_setup_state_cpuslocked+0x431/0x880 kernel/cpu.c:2507
       __cpuhp_setup_state+0xf4/0x300 kernel/cpu.c:2536
       do_one_initcall+0x11d/0x760 init/main.c:1382
       do_initcall_level init/main.c:1444 [inline]
       do_initcalls init/main.c:1460 [inline]
       do_basic_setup init/main.c:1479 [inline]
       kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
       kernel_init+0x1f/0x1e0 init/main.c:1582
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #9 (cpuhp_state_mutex){+.+.}-{4:4}:

-> #8 (cpu_hotplug_lock){++++}-{0:0}:
       percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
       percpu_down_read include/linux/percpu-rwsem.h:77 [inline]
       cpus_read_lock+0x42/0x170 kernel/cpu.c:490
       static_key_disable+0x12/0x20 kernel/jump_label.c:247
       __inet_hash_connect+0x1378/0x1e40 net/ipv4/inet_hashtables.c:1074
       tcp_v4_connect+0xeb0/0x1b40 net/ipv4/tcp_ipv4.c:307
       __inet_stream_connect+0x208/0xfa0 net/ipv4/af_inet.c:685
       inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:756
       __sys_connect_file+0x141/0x1a0 net/socket.c:2154
       __sys_connect+0x141/0x170 net/socket.c:2173
       __do_sys_connect net/socket.c:2179 [inline]
       __se_sys_connect net/socket.c:2176 [inline]
       __x64_sys_connect+0x72/0xb0 net/socket.c:2176
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #7 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x41/0xf0 net/core/sock.c:3780
       lock_sock include/net/sock.h:1709 [inline]
       inet_shutdown+0x67/0x410 net/ipv4/af_inet.c:919
       nbd_mark_nsock_dead+0xae/0x5c0 drivers/block/nbd.c:318
       sock_shutdown+0x16b/0x200 drivers/block/nbd.c:411
       nbd_clear_sock drivers/block/nbd.c:1427 [inline]
       nbd_config_put+0x1eb/0x750 drivers/block/nbd.c:1451
       nbd_release+0xb7/0x190 drivers/block/nbd.c:1756
       blkdev_put_whole+0xb0/0xf0 block/bdev.c:737
       bdev_release+0x47f/0x6d0 block/bdev.c:1160
       blkdev_release+0x15/0x20 block/fops.c:705
       __fput+0x3ff/0xb40 fs/file_table.c:469
       task_work_run+0x150/0x240 kernel/task_work.c:233
       exit_task_work include/linux/task_work.h:40 [inline]
       do_exit+0x8b8/0x2b60 kernel/exit.c:976
       do_group_exit+0xd5/0x2a0 kernel/exit.c:1118
       get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
       arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
       __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
       exit_to_user_mode_loop+0x86/0x4a0 kernel/entry/common.c:98
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
       syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
       do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
       blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
       blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x584/0x6c0 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
       submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x264/0x8e0 fs/buffer.c:2444
       filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4106
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xd1/0x370 block/partitions/core.c:723
       adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
       blkdev_get_whole+0x187/0x290 block/bdev.c:764
       bdev_open+0x2c7/0xe40 block/bdev.c:973
       blkdev_open+0x34e/0x4f0 block/fops.c:697
       do_dentry_open+0x6d8/0x1660 fs/open.c:949
       vfs_open+0x82/0x3f0 fs/open.c:1081
       do_open fs/namei.c:4699 [inline]
       path_openat+0x208c/0x31a0 fs/namei.c:4858
       do_file_open+0x20e/0x430 fs/namei.c:4887
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
       blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
       blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x584/0x6c0 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
       submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x264/0x8e0 fs/buffer.c:2444
       filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4106
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xd1/0x370 block/partitions/core.c:723
       adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
       blkdev_get_whole+0x187/0x290 block/bdev.c:764
       bdev_open+0x2c7/0xe40 block/bdev.c:973
       blkdev_open+0x34e/0x4f0 block/fops.c:697
       do_dentry_open+0x6d8/0x1660 fs/open.c:949
       vfs_open+0x82/0x3f0 fs/open.c:1081
       do_open fs/namei.c:4699 [inline]
       path_openat+0x208c/0x31a0 fs/namei.c:4858
       do_file_open+0x20e/0x430 fs/namei.c:4887
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:199 [inline]
       __synchronize_srcu+0xa2/0x300 kernel/rcu/srcutree.c:1481
       blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline]
       blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline]
       blk_mq_quiesce_queue block/blk-mq.c:304 [inline]
       blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299
       elevator_switch+0x17b/0x7e0 block/elevator.c:576
       elevator_change+0x352/0x530 block/elevator.c:681
       elevator_set_default+0x29e/0x360 block/elevator.c:754
       blk_register_queue+0x412/0x590 block/blk-sysfs.c:946
       __add_disk+0x73f/0xe40 block/genhd.c:528
       add_disk_fwnode+0x118/0x5c0 block/genhd.c:597
       add_disk include/linux/blkdev.h:785 [inline]
       nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:1984
       nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692
       do_one_initcall+0x11d/0x760 init/main.c:1382
       do_initcall_level init/main.c:1444 [inline]
       do_initcalls init/main.c:1460 [inline]
       do_basic_setup init/main.c:1479 [inline]
       kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
       kernel_init+0x1f/0x1e0 init/main.c:1582
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       elevator_change+0x1bc/0x530 block/elevator.c:679
       elevator_set_none+0x92/0xf0 block/elevator.c:769
       blk_mq_elv_switch_none block/blk-mq.c:5112 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5157 [inline]
       blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5222
       nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1489
       nbd_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2239
       genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
       genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
       genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
       netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894
       sock_sendmsg_nosec net/socket.c:792 [inline]
       __sock_sendmsg net/socket.c:807 [inline]
       ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2657
       ___sys_sendmsg+0x190/0x1e0 net/socket.c:2711
       __sys_sendmsg+0x170/0x220 net/socket.c:2743
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#49){++++}-{0:0}:
       blk_alloc_queue+0x610/0x790 block/blk-core.c:461
       blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4431
       __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4478
       nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954
       nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692
       do_one_initcall+0x11d/0x760 init/main.c:1382
       do_initcall_level init/main.c:1444 [inline]
       do_initcalls init/main.c:1460 [inline]
       do_basic_setup init/main.c:1479 [inline]
       kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
       kernel_init+0x1f/0x1e0 init/main.c:1582
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4348 [inline]
       fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4362
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4489 [inline]
       slab_alloc_node mm/slub.c:4843 [inline]
       kmem_cache_alloc_noprof+0x4c/0x6e0 mm/slub.c:4873
       __kernfs_iattrs+0x124/0x3e0 fs/kernfs/inode.c:36
       kernfs_iattrs fs/kernfs/inode.c:59 [inline]
       __kernfs_setattr+0x4d/0x3c0 fs/kernfs/inode.c:72
       kernfs_iop_setattr+0xda/0x130 fs/kernfs/inode.c:126
       notify_change+0xb25/0x1330 fs/attr.c:556
       do_truncate+0x1df/0x240 fs/open.c:68
       handle_truncate fs/namei.c:4307 [inline]
       do_open fs/namei.c:4703 [inline]
       path_openat+0x2a55/0x31a0 fs/namei.c:4858
       do_file_open+0x20e/0x430 fs/namei.c:4887
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1590
       kernfs_unlink_sibling+0xa3/0x320 fs/kernfs/dir.c:441
       __kernfs_remove+0x308/0x910 fs/kernfs/dir.c:1546
       kernfs_remove_by_name_ns+0x68/0xf0 fs/kernfs/dir.c:1749
       kernfs_remove_by_name include/linux/kernfs.h:639 [inline]
       cgroup_rm_file kernel/cgroup/cgroup.c:1758 [inline]
       cgroup_addrm_files+0x790/0xb90 kernel/cgroup/cgroup.c:4483
       css_clear_dir+0x117/0x2c0 kernel/cgroup/cgroup.c:1788
       kill_css+0x16f/0x490 kernel/cgroup/cgroup.c:6109
       cgroup_destroy_locked+0x281/0x710 kernel/cgroup/cgroup.c:6194
       cgroup_rmdir+0x7b/0x300 kernel/cgroup/cgroup.c:6311
       kernfs_iop_rmdir+0x106/0x170 fs/kernfs/dir.c:1318
       vfs_rmdir fs/namei.c:5366 [inline]
       vfs_rmdir+0x328/0x8a0 fs/namei.c:5339
       filename_rmdir+0x31a/0x5c0 fs/namei.c:5421
       __do_sys_rmdir fs/namei.c:5444 [inline]
       __se_sys_rmdir fs/namei.c:5441 [inline]
       __x64_sys_rmdir+0x46/0x70 fs/namei.c:5441
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &root->kernfs_iattr_rwsem --> cpuhp_state_mutex --> &root->kernfs_rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&root->kernfs_rwsem);
                               lock(cpuhp_state_mutex);
                               lock(&root->kernfs_rwsem);
  lock(&root->kernfs_iattr_rwsem);

 *** DEADLOCK ***

5 locks held by syz.5.3721/19895:
 #0: ffff88807858a420 (sb_writers#10){.+.+}-{0:0}, at: filename_rmdir+0x1ff/0x5c0 fs/namei.c:5410
 #1: ffff888075220b38 (&type->i_mutex_dir_key#6/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1073 [inline]
 #1: ffff888075220b38 (&type->i_mutex_dir_key#6/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2914 [inline]
 #1: ffff888075220b38 (&type->i_mutex_dir_key#6/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2938 [inline]
 #1: ffff888075220b38 (&type->i_mutex_dir_key#6/1){+.+.}-{4:4}, at: filename_rmdir+0x258/0x5c0 fs/namei.c:5414
 #2: ffff888067c8a908 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #2: ffff888067c8a908 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: vfs_rmdir fs/namei.c:5351 [inline]
 #2: ffff888067c8a908 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: vfs_rmdir+0xed/0x8a0 fs/namei.c:5339
 #3: ffffffff8e84a808 (cgroup_mutex){+.+.}-{4:4}, at: cgroup_lock include/linux/cgroup.h:394 [inline]
 #3: ffffffff8e84a808 (cgroup_mutex){+.+.}-{4:4}, at: cgroup_kn_lock_live+0x116/0x520 kernel/cgroup/cgroup.c:1732
 #4: ffff88801c6af188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3d/0xf0 fs/kernfs/dir.c:1744

stack backtrace:
CPU: 0 UID: 0 PID: 19895 Comm: syz.5.3721 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825
 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1590
 kernfs_unlink_sibling+0xa3/0x320 fs/kernfs/dir.c:441
 __kernfs_remove+0x308/0x910 fs/kernfs/dir.c:1546
 kernfs_remove_by_name_ns+0x68/0xf0 fs/kernfs/dir.c:1749
 kernfs_remove_by_name include/linux/kernfs.h:639 [inline]
 cgroup_rm_file kernel/cgroup/cgroup.c:1758 [inline]
 cgroup_addrm_files+0x790/0xb90 kernel/cgroup/cgroup.c:4483
 css_clear_dir+0x117/0x2c0 kernel/cgroup/cgroup.c:1788
 kill_css+0x16f/0x490 kernel/cgroup/cgroup.c:6109
 cgroup_destroy_locked+0x281/0x710 kernel/cgroup/cgroup.c:6194
 cgroup_rmdir+0x7b/0x300 kernel/cgroup/cgroup.c:6311
 kernfs_iop_rmdir+0x106/0x170 fs/kernfs/dir.c:1318
 vfs_rmdir fs/namei.c:5366 [inline]
 vfs_rmdir+0x328/0x8a0 fs/namei.c:5339
 filename_rmdir+0x31a/0x5c0 fs/namei.c:5421
 __do_sys_rmdir fs/namei.c:5444 [inline]
 __se_sys_rmdir fs/namei.c:5441 [inline]
 __x64_sys_rmdir+0x46/0x70 fs/namei.c:5441
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f796cf9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f796deb9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f796d215fa0 RCX: 00007f796cf9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000240
RBP: 00007f796d032c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f796d216038 R14: 00007f796d215fa0 R15: 00007ffe63e455c8
 </TASK>