INFO: rcu_tasks detected stalls on tasks:
ffff888028d0ddc0: .. nvcsw: 3080/3080 holdout: 1 idle_cpu: -1/1
task:kworker/1:2     state:R  running task     stack:21832 pid:996   tgid:996   ppid:2      task_flags:0x4208160 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5583 [inline]
 __schedule+0x17dd/0x5830 kernel/sched/core.c:7382
 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7662
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:543 [inline]
 irqentry_exit+0x14f/0x9b0 kernel/entry/common.c:154
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5947
Code: ff ff ff e8 d0 aa 60 0a f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 d2 34 3d 13 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d c7 19 1d
RSP: 0018:ffffc90004e965e8 EFLAGS: 00000286
RAX: 00ac49964bb98500 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 00000000baec8a92 RSI: ffffffff8e9347d2 RDI: ffffffff8c8ea380
RBP: ffff888028d0ddc0 R08: ffffffff8178798f R09: 0000000000000000
R10: ffffc90004e96778 R11: fffff520009d2cf1 R12: ffffffff9015a420
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 rcu_read_lock include/linux/rcupdate.h:849 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
 unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
 __unwind_start+0x514/0x660 arch/x86/kernel/unwind_orc.c:787
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:264 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2780 [inline]
 slab_free mm/slub.c:6630 [inline]
 kfree+0x1c5/0x650 mm/slub.c:6923
 ath6kl_usb_post_recv_transfers+0x3c3/0x680 drivers/net/wireless/ath/ath6kl/usb.c:459
 ath6kl_usb_start_recv_pipes drivers/net/wireless/ath/ath6kl/usb.c:497 [inline]
 hif_start drivers/net/wireless/ath/ath6kl/usb.c:702 [inline]
 ath6kl_usb_power_on+0x6a/0x280 drivers/net/wireless/ath/ath6kl/usb.c:1061
 ath6kl_hif_power_on drivers/net/wireless/ath/ath6kl/hif-ops.h:136 [inline]
 ath6kl_core_init+0x1e1/0x10c0 drivers/net/wireless/ath/ath6kl/core.c:97
 ath6kl_usb_probe+0x14b9/0x15b0 drivers/net/wireless/ath/ath6kl/usb.c:1162
 usb_probe_interface+0x751/0xe00 drivers/usb/core/driver.c:399
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:707
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:869
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:899
 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1027
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2bd/0x430 drivers/base/dd.c:1131
 device_initial_probe+0x9c/0x100 drivers/base/dd.c:1190
 __bus_probe_device+0x126/0x220 drivers/base/bus.c:614
 device_add+0x7d7/0xb80 drivers/base/core.c:3778
 usb_set_configuration+0x1bb5/0x2260 drivers/usb/core/message.c:2280
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
 usb_probe_device+0x1c3/0x3b0 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:707
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:869
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:899
 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1027
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2bd/0x430 drivers/base/dd.c:1131
 device_initial_probe+0x9c/0x100 drivers/base/dd.c:1190
 __bus_probe_device+0x126/0x220 drivers/base/bus.c:614
 device_add+0x7d7/0xb80 drivers/base/core.c:3778
 usb_new_device+0x9aa/0x1690 drivers/usb/core/hub.c:2713
 hub_port_connect drivers/usb/core/hub.c:5585 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x28e8/0x4d30 drivers/usb/core/hub.c:5971
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>