syzbot


INFO: task hung in hub_event (4)

Status: upstream: reported on 2025/04/10 12:17
Reported-by: syzbot+25072eda2fded61742b5@syzkaller.appspotmail.com
First crash: 56d, last: 42d
Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in hub_event usb 19 2071d 2247d 0/28 auto-closed as invalid on 2020/01/02 20:34
linux-4.14 INFO: task hung in hub_event 5 1242d 1264d 0/1 auto-closed as invalid on 2022/05/10 10:19
linux-6.1 INFO: task hung in hub_event (2) 1 625d 625d 0/3 auto-obsoleted due to no activity on 2023/12/29 05:51
upstream INFO: task hung in hub_event (2) usb 27 1242d 1287d 0/28 closed as invalid on 2022/02/08 09:40
linux-5.15 INFO: task hung in hub_event (2) 1 530d 530d 0/3 auto-obsoleted due to no activity on 2024/04/01 17:35
upstream INFO: task hung in hub_event (3) usb 394 8h32m 873d 0/28 upstream: reported on 2023/01/14 20:19
linux-6.1 INFO: task hung in hub_event (3) 8 59d 62d 0/3 upstream: reported on 2025/04/04 18:12
linux-5.15 INFO: task hung in hub_event (3) 1 319d 319d 0/3 auto-obsoleted due to no activity on 2024/10/29 18:51
linux-5.15 INFO: task hung in hub_event 3 642d 805d 0/3 auto-obsoleted due to no activity on 2023/12/12 00:26
linux-6.1 INFO: task hung in hub_event 2 787d 816d 0/3 auto-obsoleted due to no activity on 2023/08/08 09:24

Sample crash report:
INFO: task kworker/1:0:21 blocked for more than 144 seconds.
      Not tainted 5.15.180-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:0     state:D stack:23864 pid:   21 ppid:     2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518
 __mutex_lock_common+0xe34/0x25a0 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 port_event drivers/usb/core/hub.c:5753 [inline]
 hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/0:0/7:
 #0: ffff88801c720538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90000cc7d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888147d3b220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888147d3b220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff888147d3e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff888147d3e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff888147d3e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff888147d3e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff888147d3e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff88814805d868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff88814805d868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff88814805d868 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff88814805d868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
5 locks held by kworker/1:0/21:
 #0: ffff88801c720538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90000db7d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff8880259a5220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff8880259a5220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8880259f05c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8880259f05c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8880259f05c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8880259f05c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8880259f05c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
1 lock held by khungtaskd/27:
 #0: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/1:2/1108:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90004a97d20 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
5 locks held by kworker/0:3/2284:
 #0: ffff88801c720538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900062ffd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888147f4b220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888147f4b220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff888147f4e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff888147f4e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff888147f4e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff888147f4e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff888147f4e5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888147f6fa68 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888147f6fa68 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888147f6fa68 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888147f6fa68 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
1 lock held by dhcpcd/3838:
 #0: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x2a5/0x1ae0 net/ipv4/devinet.c:1077
2 locks held by getty/3925:
 #0: ffff88802cb55098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025c62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
5 locks held by kworker/0:6/4212:
 #0: ffff88801c720538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90003d7fd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888025977220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888025977220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff88802599a5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff88802599a5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff88802599a5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff88802599a5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff88802599a5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888025712868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
3 locks held by kworker/u4:5/4220:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90003defd20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
3 locks held by kworker/1:8/4242:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90003dffd20 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:74
2 locks held by kworker/u4:8/4281:
5 locks held by kworker/u4:11/4296:
 #0: ffff8880175cd938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000441fd20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8dc38350 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x166/0xc90 net/core/net_namespace.c:572
 #3: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock_unregistering net/core/dev.c:11619 [inline]
 #3: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0x1ac/0x3f0 net/core/dev.c:11657
 #4: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #4: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x350/0x740 kernel/rcu/tree_exp.h:845
1 lock held by syz-executor/8693:
 #0: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #0: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x350/0x740 kernel/rcu/tree_exp.h:845
1 lock held by syz.8.950/9089:
 #0: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: do_ip_setsockopt net/ipv4/ip_sockglue.c:951 [inline]
 #0: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: ip_setsockopt+0x504/0x3f80 net/ipv4/ip_sockglue.c:1430
2 locks held by syz.7.952/9103:
 #0: ffffffff8dc2bea8 (vlan_ioctl_mutex){+.+.}-{3:3}, at: sock_ioctl+0x526/0x770 net/socket.c:1219
 #1: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: vlan_ioctl_handler+0x114/0x9a0 net/8021q/vlan.c:555
1 lock held by syz.7.952/9107:
 #0: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x956/0xef0 net/core/rtnetlink.c:5647

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 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+0xe72/0xeb0 kernel/hung_task.c:369
 kthread+0x3f6/0x4f0 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 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/24 17:02 linux-5.15.y f7347f400572 9882047a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in hub_event
2025/04/10 12:27 linux-5.15.y 0c935c049b5c 988b336c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in hub_event
2025/04/10 12:16 linux-5.15.y 0c935c049b5c 988b336c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in hub_event
* Struck through repros no longer work on HEAD.