rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5970/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=15377, q=1684 ncpus=2)
task:kworker/1:7     state:R  running task    
 stack:21576 pid:5970  tgid:5970  ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: usb_hub_wq hub_event

Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288
 irqentry_exit+0x36/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x62/0x350 kernel/locking/lockdep.c:5872
Code: a9 3e 12 83 f8 07 0f 87 bc 02 00 00 89 c0 48 0f a3 05 62 84 13 0f 0f 82 74 02 00 00 8b 35 1a b6 13 0f 85 f6 0f 85 8d 00 00 00 <48> 8b 44 24 30 65 48 2b 05 b9 a8 3e 12 0f 85 c7 02 00 00 48 83 c4
RSP: 0018:ffffc90004f9f728 EFLAGS: 00000206

RAX: 0000000000000046 RBX: ffffffff8e5c1220 RCX: 0000000044cc4503
RDX: 0000000000000000 RSI: ffffffff8de2ace0 RDI: ffffffff8c162900
RBP: 0000000000000002 R08: 78c0bcff48f16eae R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
 kernfs_root+0x34/0x2a0 fs/kernfs/kernfs-internal.h:75
 kernfs_root_is_locked fs/kernfs/kernfs-internal.h:109 [inline]
 kernfs_rcu_name fs/kernfs/kernfs-internal.h:119 [inline]
 kernfs_sd_compare fs/kernfs/dir.c:349 [inline]
 kernfs_link_sibling+0x269/0x770 fs/kernfs/dir.c:380
 kernfs_add_one+0x20a/0x840 fs/kernfs/dir.c:810
 kernfs_create_link+0x1a9/0x240 fs/kernfs/symlink.c:48
 sysfs_do_create_link_sd+0x90/0x140 fs/sysfs/symlink.c:44
 sysfs_do_create_link fs/sysfs/symlink.c:80 [inline]
 sysfs_create_link+0x61/0xc0 fs/sysfs/symlink.c:92
 usb_new_device+0xeef/0x1a60 drivers/usb/core/hub.c:2711
 hub_port_connect drivers/usb/core/hub.c:5566 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x2f34/0x4fe0 drivers/usb/core/hub.c:5952
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>