======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
kworker/u9:1/19169 is trying to acquire lock:
ffff888140460188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_find_and_get_ns+0x2f/0x70 fs/kernfs/dir.c:938

but task is already holding lock:
ffffffff8f2d0e08 (dev_pm_qos_sysfs_mtx){+.+.}-{4:4}, at: dev_pm_qos_constraints_destroy+0x28/0x780 drivers/base/power/qos.c:254

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #10 (dev_pm_qos_sysfs_mtx){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
       dev_pm_qos_constraints_destroy+0x28/0x780 drivers/base/power/qos.c:254
       dpm_sysfs_remove+0x70/0xb0 drivers/base/power/sysfs.c:831
       device_del+0x1a0/0x9f0 drivers/base/core.c:3853
       device_unregister+0x1d/0xe0 drivers/base/core.c:3919
       mce_device_remove arch/x86/kernel/cpu/mce/core.c:2748 [inline]
       mce_cpu_pre_down+0x326/0x640 arch/x86/kernel/cpu/mce/core.c:2809
       cpuhp_invoke_callback+0x3d5/0xa10 kernel/cpu.c:195
       cpuhp_thread_fun+0x47e/0x6f0 kernel/cpu.c:1105
       smpboot_thread_fn+0x3f7/0xae0 kernel/smpboot.c:160
       kthread+0x3c5/0x780 kernel/kthread.c:463
       ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #9 (cpuhp_state-down){+.+.}-{0:0}:
       cpuhp_lock_acquire kernel/cpu.c:104 [inline]
       cpuhp_kick_ap_work+0xa4/0xbd0 kernel/cpu.c:1184
       _cpu_down+0x37b/0xf40 kernel/cpu.c:1422
       __cpu_down_maps_locked+0x6c/0x90 kernel/cpu.c:1468
       work_for_cpu_fn+0x55/0xa0 kernel/workqueue.c:6770
       process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
       process_scheduled_works kernel/workqueue.c:3340 [inline]
       worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
       kthread+0x3c5/0x780 kernel/kthread.c:463
       ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #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+0x42/0x160 kernel/cpu.c:491
       static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190
       udp_tunnel_encap_enable include/net/udp_tunnel.h:203 [inline]
       setup_udp_tunnel_sock+0x39b/0x680 net/ipv4/udp_tunnel_core.c:92
       l2tp_tunnel_register+0x9c8/0xbb0 net/l2tp/l2tp_core.c:1679
       pppol2tp_tunnel_get.constprop.0+0x3f0/0x540 net/l2tp/l2tp_ppp.c:662
       pppol2tp_connect+0xb1b/0x1ce0 net/l2tp/l2tp_ppp.c:710
       __sys_connect_file+0x141/0x1a0 net/socket.c:2089
       __sys_connect+0x13b/0x160 net/socket.c:2108
       __do_sys_connect net/socket.c:2114 [inline]
       __se_sys_connect net/socket.c:2111 [inline]
       __x64_sys_connect+0x72/0xb0 net/socket.c:2111
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/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:1700 [inline]
       inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:913
       nbd_mark_nsock_dead+0xae/0x5d0 drivers/block/nbd.c:318
       recv_work+0x66b/0xa70 drivers/block/nbd.c:1021
       process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
       process_scheduled_works kernel/workqueue.c:3340 [inline]
       worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
       kthread+0x3c5/0x780 kernel/kthread.c:463
       ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x423/0x12d0 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2138
       __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+0xcbd/0x15f0 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2376
       blk_mq_dispatch_list+0x514/0x1300 block/blk-mq.c:2939
       blk_mq_flush_plug_list block/blk-mq.c:2987 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2959
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
       blk_finish_plug block/blk-core.c:1252 [inline]
       blk_finish_plug block/blk-core.c:1249 [inline]
       __submit_bio+0x542/0x690 block/blk-core.c:651
       __submit_bio_noacct_mq block/blk-core.c:724 [inline]
       submit_bio_noacct_nocheck+0x53d/0xbe0 block/blk-core.c:755
       submit_bio_noacct+0x5bd/0x1f40 block/blk-core.c:879
       submit_bh fs/buffer.c:2829 [inline]
       block_read_full_folio+0x4db/0x850 fs/buffer.c:2461
       filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2496
       do_read_cache_folio+0x266/0x5c0 mm/filemap.c:4096
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xd4/0x370 block/partitions/core.c:722
       adfspart_check_ICS+0x93/0x940 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:141 [inline]
       blk_add_partitions block/partitions/core.c:589 [inline]
       bdev_disk_changed+0x723/0x1520 block/partitions/core.c:693
       blkdev_get_whole+0x187/0x290 block/bdev.c:765
       bdev_open+0x2c7/0xe40 block/bdev.c:974
       blkdev_open+0x34e/0x4f0 block/fops.c:698
       do_dentry_open+0x748/0x1590 fs/open.c:962
       vfs_open+0x82/0x3f0 fs/open.c:1094
       do_open fs/namei.c:4628 [inline]
       path_openat+0x2078/0x3140 fs/namei.c:4787
       do_filp_open+0x20b/0x470 fs/namei.c:4814
       do_sys_openat2+0x121/0x290 fs/open.c:1430
       do_sys_open fs/open.c:1436 [inline]
       __do_sys_openat fs/open.c:1452 [inline]
       __se_sys_openat fs/open.c:1447 [inline]
       __x64_sys_openat+0x174/0x210 fs/open.c:1447
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/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+0x1aa/0x1ca0 kernel/locking/mutex.c:776
       nbd_queue_rq+0xbd/0x12d0 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2138
       __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+0xcbd/0x15f0 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2376
       blk_mq_dispatch_list+0x514/0x1300 block/blk-mq.c:2939
       blk_mq_flush_plug_list block/blk-mq.c:2987 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2959
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
       blk_finish_plug block/blk-core.c:1252 [inline]
       blk_finish_plug block/blk-core.c:1249 [inline]
       __submit_bio+0x542/0x690 block/blk-core.c:651
       __submit_bio_noacct_mq block/blk-core.c:724 [inline]
       submit_bio_noacct_nocheck+0x53d/0xbe0 block/blk-core.c:755
       submit_bio_noacct+0x5bd/0x1f40 block/blk-core.c:879
       submit_bh fs/buffer.c:2829 [inline]
       block_read_full_folio+0x4db/0x850 fs/buffer.c:2461
       filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2496
       do_read_cache_folio+0x266/0x5c0 mm/filemap.c:4096
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xd4/0x370 block/partitions/core.c:722
       adfspart_check_ICS+0x93/0x940 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:141 [inline]
       blk_add_partitions block/partitions/core.c:589 [inline]
       bdev_disk_changed+0x723/0x1520 block/partitions/core.c:693
       blkdev_get_whole+0x187/0x290 block/bdev.c:765
       bdev_open+0x2c7/0xe40 block/bdev.c:974
       blkdev_open+0x34e/0x4f0 block/fops.c:698
       do_dentry_open+0x748/0x1590 fs/open.c:962
       vfs_open+0x82/0x3f0 fs/open.c:1094
       do_open fs/namei.c:4628 [inline]
       path_openat+0x2078/0x3140 fs/namei.c:4787
       do_filp_open+0x20b/0x470 fs/namei.c:4814
       do_sys_openat2+0x121/0x290 fs/open.c:1430
       do_sys_open fs/open.c:1436 [inline]
       __do_sys_openat fs/open.c:1452 [inline]
       __se_sys_openat fs/open.c:1447 [inline]
       __x64_sys_openat+0x174/0x210 fs/open.c:1447
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/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:197 [inline]
       __synchronize_srcu+0xa2/0x250 kernel/rcu/srcutree.c:1503
       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+0x149/0x1b0 block/blk-mq.c:299
       elevator_switch+0x17d/0x7f0 block/elevator.c:576
       elevator_change+0x38b/0x570 block/elevator.c:680
       elevator_set_default+0x2d2/0x390 block/elevator.c:753
       blk_register_queue+0x384/0x4e0 block/blk-sysfs.c:932
       __add_disk+0x74a/0xf00 block/genhd.c:528
       add_disk_fwnode+0x13f/0x5d0 block/genhd.c:597
       add_disk include/linux/blkdev.h:785 [inline]
       nbd_dev_add+0x783/0xbb0 drivers/block/nbd.c:1984
       nbd_init+0x181/0x320 drivers/block/nbd.c:2692
       do_one_initcall+0x123/0x680 init/main.c:1378
       do_initcall_level init/main.c:1440 [inline]
       do_initcalls init/main.c:1456 [inline]
       do_basic_setup init/main.c:1475 [inline]
       kernel_init_freeable+0x5c8/0x920 init/main.c:1688
       kernel_init+0x1c/0x2b0 init/main.c:1578
       ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
       elevator_change+0x1ed/0x570 block/elevator.c:678
       elv_iosched_store+0x3e8/0x4a0 block/elevator.c:811
       queue_attr_store+0x26b/0x310 block/blk-sysfs.c:859
       sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142
       kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352
       iter_file_splice_write+0xa24/0x12b0 fs/splice.c:738
       do_splice_from fs/splice.c:938 [inline]
       direct_splice_actor+0x192/0x6c0 fs/splice.c:1161
       splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
       do_splice_direct_actor fs/splice.c:1204 [inline]
       do_splice_direct+0x174/0x240 fs/splice.c:1230
       do_sendfile+0xb06/0xe50 fs/read_write.c:1370
       __do_sys_sendfile64 fs/read_write.c:1431 [inline]
       __se_sys_sendfile64 fs/read_write.c:1417 [inline]
       __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1417
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#66){++++}-{0:0}:
       blk_alloc_queue+0x610/0x750 block/blk-core.c:461
       blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4415
       __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4462
       null_add_dev+0xf2e/0x1eb0 drivers/block/null_blk/main.c:1999
       null_create_dev drivers/block/null_blk/main.c:2097 [inline]
       null_init+0x2c9/0x610 drivers/block/null_blk/main.c:2169
       do_one_initcall+0x123/0x680 init/main.c:1378
       do_initcall_level init/main.c:1440 [inline]
       do_initcalls init/main.c:1456 [inline]
       do_basic_setup init/main.c:1475 [inline]
       kernel_init_freeable+0x5c8/0x920 init/main.c:1688
       kernel_init+0x1c/0x2b0 init/main.c:1578
       ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4301 [inline]
       fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4315
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4904 [inline]
       slab_alloc_node mm/slub.c:5239 [inline]
       kmem_cache_alloc_lru_noprof+0x5f/0x770 mm/slub.c:5282
       alloc_inode+0xc3/0x240 fs/inode.c:348
       iget_locked+0x1d9/0x6d0 fs/inode.c:1470
       kernfs_get_inode+0x46/0x470 fs/kernfs/inode.c:253
       kernfs_fill_super fs/kernfs/mount.c:308 [inline]
       kernfs_get_tree+0x62a/0xb60 fs/kernfs/mount.c:392
       sysfs_get_tree+0x41/0x140 fs/sysfs/mount.c:31
       vfs_get_tree+0x8e/0x330 fs/super.c:1751
       fc_mount fs/namespace.c:1199 [inline]
       do_new_mount_fc fs/namespace.c:3636 [inline]
       do_new_mount fs/namespace.c:3712 [inline]
       path_mount+0x7bf/0x23a0 fs/namespace.c:4022
       do_mount fs/namespace.c:4035 [inline]
       __do_sys_mount fs/namespace.c:4224 [inline]
       __se_sys_mount fs/namespace.c:4201 [inline]
       __x64_sys_mount+0x293/0x310 fs/namespace.c:4201
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&root->kernfs_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+0x1669/0x2890 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
       down_read+0x9b/0x460 kernel/locking/rwsem.c:1537
       kernfs_find_and_get_ns+0x2f/0x70 fs/kernfs/dir.c:938
       kernfs_find_and_get include/linux/kernfs.h:612 [inline]
       sysfs_unmerge_group+0x61/0x170 fs/sysfs/group.c:405
       dev_pm_qos_constraints_destroy+0x30/0x780 drivers/base/power/qos.c:260
       dpm_sysfs_remove+0x70/0xb0 drivers/base/power/sysfs.c:831
       device_del+0x1a0/0x9f0 drivers/base/core.c:3853
       device_unregister+0x1d/0xe0 drivers/base/core.c:3919
       hci_conn_del_sysfs+0xdd/0x1a0 net/bluetooth/hci_sysfs.c:79
       hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline]
       hci_conn_del+0x680/0x11d0 net/bluetooth/hci_conn.c:1234
       hci_abort_conn_sync+0x76a/0xb20 net/bluetooth/hci_sync.c:5721
       abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2962
       hci_cmd_sync_work+0x1ab/0x470 net/bluetooth/hci_sync.c:332
       process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
       process_scheduled_works kernel/workqueue.c:3340 [inline]
       worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
       kthread+0x3c5/0x780 kernel/kthread.c:463
       ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

other info that might help us debug this:

Chain exists of:
  &root->kernfs_rwsem --> cpuhp_state-down --> dev_pm_qos_sysfs_mtx

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(dev_pm_qos_sysfs_mtx);
                               lock(cpuhp_state-down);
                               lock(dev_pm_qos_sysfs_mtx);
  rlock(&root->kernfs_rwsem);

 *** DEADLOCK ***

5 locks held by kworker/u9:1/19169:
 #0: ffff8880340a9948 ((wq_completion)hci1){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc9000459fc90 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff888076df4ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x175/0x470 net/bluetooth/hci_sync.c:331
 #3: ffff888076df40c0 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x13f/0xb20 net/bluetooth/hci_sync.c:5702
 #4: ffffffff8f2d0e08 (dev_pm_qos_sysfs_mtx){+.+.}-{4:4}, at: dev_pm_qos_constraints_destroy+0x28/0x780 drivers/base/power/qos.c:254

stack backtrace:
CPU: 0 UID: 0 PID: 19169 Comm: kworker/u9:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci1 hci_cmd_sync_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x340 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+0x1669/0x2890 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
 down_read+0x9b/0x460 kernel/locking/rwsem.c:1537
 kernfs_find_and_get_ns+0x2f/0x70 fs/kernfs/dir.c:938
 kernfs_find_and_get include/linux/kernfs.h:612 [inline]
 sysfs_unmerge_group+0x61/0x170 fs/sysfs/group.c:405
 dev_pm_qos_constraints_destroy+0x30/0x780 drivers/base/power/qos.c:260
 dpm_sysfs_remove+0x70/0xb0 drivers/base/power/sysfs.c:831
 device_del+0x1a0/0x9f0 drivers/base/core.c:3853
 device_unregister+0x1d/0xe0 drivers/base/core.c:3919
 hci_conn_del_sysfs+0xdd/0x1a0 net/bluetooth/hci_sysfs.c:79
 hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline]
 hci_conn_del+0x680/0x11d0 net/bluetooth/hci_conn.c:1234
 hci_abort_conn_sync+0x76a/0xb20 net/bluetooth/hci_sync.c:5721
 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2962
 hci_cmd_sync_work+0x1ab/0x470 net/bluetooth/hci_sync.c:332
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>