syzbot


INFO: task hung in ath6kl_usb_power_off (5)

Status: upstream: reported on 2026/01/29 06:40
Reported-by: syzbot+9b8909ebe75a0e3e758e@syzkaller.appspotmail.com
First crash: 115d, last: 6d19h
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in ath6kl_usb_power_off wireless 1 7454 1381d 2147d 22/29 fixed on 2023/02/24 13:50
linux-5.15 INFO: task hung in ath6kl_usb_power_off (3) 1 1 603d 603d 0/3 auto-obsoleted due to no activity on 2025/01/05 17:18
linux-5.15 INFO: task hung in ath6kl_usb_power_off (4) 1 1 259d 259d 0/3 auto-obsoleted due to no activity on 2025/12/16 04:15
linux-5.15 INFO: task hung in ath6kl_usb_power_off (2) 1 2 784d 807d 0/3 auto-obsoleted due to no activity on 2024/07/08 14:28
linux-5.15 INFO: task hung in ath6kl_usb_power_off 1 1 1048d 1048d 0/3 auto-obsoleted due to no activity on 2023/10/19 06:26

Sample crash report:
INFO: task kworker/1:2:1107 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:2     state:D stack:22320 pid: 1107 ppid:     2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 do_wait_for_common+0x2a2/0x450 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 flush_workqueue+0x664/0x13d0 kernel/workqueue.c:2882
 hif_detach_htc drivers/net/wireless/ath/ath6kl/usb.c:861 [inline]
 ath6kl_usb_power_off+0x34/0x40 drivers/net/wireless/ath/ath6kl/usb.c:1060
 ath6kl_hif_power_off drivers/net/wireless/ath/ath6kl/hif-ops.h:143 [inline]
 ath6kl_core_init+0xac4/0x1090 drivers/net/wireless/ath/ath6kl/core.c:257
 ath6kl_usb_probe+0x1302/0x1410 drivers/net/wireless/ath/ath6kl/usb.c:1160
 usb_probe_interface+0x5c5/0xb20 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a8/0x480 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_set_configuration+0x1991/0x1fd0 drivers/usb/core/message.c:2223
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x139/0x270 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a8/0x480 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_new_device+0xd65/0x1660 drivers/usb/core/hub.c:2632
 hub_port_connect drivers/usb/core/hub.c:5497 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
 port_event drivers/usb/core/hub.c:5799 [inline]
 hub_event+0x2e4a/0x55e0 drivers/usb/core/hub.c:5881
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task udevd:20747 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:23120 pid:20747 ppid:  3560 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 device_lock include/linux/device.h:764 [inline]
 uevent_show+0x17a/0x330 drivers/base/core.c:2408
 dev_attr_show+0x50/0xb0 drivers/base/core.c:2110
 sysfs_kf_seq_show+0x316/0x4c0 fs/sysfs/file.c:61
 seq_read_iter+0x49b/0xd50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2167 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x759/0xd60 fs/read_write.c:485
 ksys_read+0x152/0x260 fs/read_write.c:623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc66f5e3407
RSP: 002b:00007ffc7dee2e10 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fc66f4f5880 RCX: 00007fc66f5e3407
RDX: 0000000000001000 RSI: 000056225007d550 RDI: 0000000000000008
RBP: 00007fc66f72bff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007fc66f72bea0 R14: 0000000000000000 R15: 00005622500830d0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31f320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
5 locks held by kworker/1:2/1107:
 #0: ffff888017ae0d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90004887d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff888024478220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #2: ffff888024478220 (&dev->mutex){....}-{3:3}, at: hub_event+0x19f/0x55e0 drivers/usb/core/hub.c:5827
 #3: ffff888078fd5220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff888078fd5220 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x480 drivers/base/dd.c:954
 #4: ffff8880629cf1a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #4: ffff8880629cf1a8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x480 drivers/base/dd.c:954
2 locks held by getty/3949:
 #0: ffff88802c752098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
2 locks held by kworker/1:14/4493:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90003c2fd00 ((work_completion)(&m->mpeg_thread)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
4 locks held by udevd/20747:
 #0: ffff8880624a8d58 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff8880602f6088 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: ffff888061f0e660 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: ffff8880629cf1a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff8880629cf1a8 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17a/0x330 drivers/base/core.c:2408
2 locks held by kworker/0:13/24238:
 #0: ffff888016c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc900031efd00 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 26625 Comm: kworker/u4:10 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:unwind_next_frame+0xcb/0x1d90 arch/x86/kernel/unwind_orc.c:-1
Code: 48 bf 01 00 00 00 e8 d4 54 1d 00 4c 8d 7b 50 4c 89 f8 48 c1 e8 03 48 89 44 24 30 42 80 3c 30 00 74 08 4c 89 ff e8 95 37 89 00 <4c> 89 7c 24 28 4d 8b 37 4d 85 f6 74 30 49 81 c6 88 00 00 00 4c 89
RSP: 0018:ffffc9000391f2e8 EFLAGS: 00000246
RAX: 1ffff92000723e7f RBX: ffffc9000391f3a8 RCX: ffffffff962dcf00
RDX: dffffc0000000000 RSI: ffffffff8946f09e RDI: ffffffff81351d2c
RBP: ffffc9000391f3f0 R08: ffffc9000391f470 R09: 0000000000000007
R10: dffffc0000000000 R11: fffff52000723e81 R12: ffffffff8946f09e
R13: ffffc9000391fb80 R14: dffffc0000000000 R15: ffffc9000391f3f8
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564bce7bb008 CR3: 0000000046c29000 CR4: 00000000003506e0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002
DR3: ffffffffefffff15 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 ieee80211_bss_info_update+0x846/0xa70 net/mac80211/scan.c:232
 ieee80211_rx_bss_info net/mac80211/ibss.c:1123 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1614 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x1700/0x2ab0 net/mac80211/ibss.c:1643
 ieee80211_iface_process_skb net/mac80211/iface.c:1459 [inline]
 ieee80211_iface_work+0x70e/0xc60 net/mac80211/iface.c:1513
 cfg80211_wiphy_work+0x221/0x260 net/wireless/core.c:433
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/17 14:02 linux-5.15.y 93741761e5e3 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in ath6kl_usb_power_off
2026/05/17 11:55 linux-5.15.y 93741761e5e3 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in ath6kl_usb_power_off
2026/05/12 03:49 linux-5.15.y de8dfb3f0278 d168f260 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in ath6kl_usb_power_off
2026/04/13 10:42 linux-5.15.y 91d48252ad4b 9530ccf9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in ath6kl_usb_power_off
2026/03/12 18:11 linux-5.15.y 91d48252ad4b 4efadf07 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in ath6kl_usb_power_off
2026/01/29 06:40 linux-5.15.y 9eec9a14ee10 0adc945e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in ath6kl_usb_power_off
* Struck through repros no longer work on HEAD.