syzbot


INFO: task hung in hub_port_init

Status: upstream: reported on 2025/07/07 19:43
Reported-by: syzbot+9e7a55a530aaf49033be@syzkaller.appspotmail.com
First crash: 15d, last: 15d
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in hub_port_init 1 C done 15888 1351d 1751d 20/29 fixed on 2021/11/10 00:50
linux-5.15 INFO: task hung in hub_port_init origin:upstream 1 C error 98 39d 834d 0/3 upstream: reported C repro on 2023/04/11 08:33
upstream INFO: task hung in hub_port_init (3) usb 1 C error 730 3d12h 848d 0/29 upstream: reported C repro on 2023/03/28 12:23
linux-4.14 INFO: task hung in hub_port_init 1 C error 6032 990d 1754d 0/1 upstream: reported C repro on 2020/10/03 08:19
upstream INFO: task hung in hub_port_init (2) usb 1 C error 486 883d 1345d 22/29 fixed on 2023/02/24 13:50
linux-4.19 INFO: task hung in hub_port_init 1 C 4279 875d 1754d 0/1 upstream: reported C repro on 2020/10/03 09:24
linux-6.1 INFO: task hung in hub_port_init origin:upstream 1 C error 68 9d09h 864d 0/3 upstream: reported C repro on 2023/03/11 21:39

Sample crash report:
INFO: task kworker/1:4:5828 blocked for more than 144 seconds.
      Not tainted 6.6.96-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:4     state:D stack:22728 pid:5828  ppid:2      flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 usb_kill_urb+0x1c6/0x2f0 drivers/usb/core/urb.c:713
 usb_start_wait_urb+0x18d/0x4b0 drivers/usb/core/message.c:65
 usb_internal_control_msg drivers/usb/core/message.c:103 [inline]
 usb_control_msg+0x233/0x3e0 drivers/usb/core/message.c:154
 get_bMaxPacketSize0 drivers/usb/core/hub.c:4785 [inline]
 hub_port_init+0xbf3/0x2760 drivers/usb/core/hub.c:4981
 hub_port_connect drivers/usb/core/hub.c:5430 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5641 [inline]
 port_event drivers/usb/core/hub.c:5801 [inline]
 hub_event+0x2513/0x49c0 drivers/usb/core/hub.c:5883
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5550:
 #0: ffff88802dce30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz-executor/5786:
5 locks held by kworker/1:4/5828:
 #0: ffff8880196b7d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff8880196b7d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc900047efd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900047efd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888025c2a190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:992 [inline]
 #2: ffff888025c2a190 (&dev->mutex){....}-{3:3}, at: hub_event+0x185/0x49c0 drivers/usb/core/hub.c:5829
 #3: ffff888025c2e508 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3187 [inline]
 #3: ffff888025c2e508 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5398 [inline]
 #3: ffff888025c2e508 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5641 [inline]
 #3: ffff888025c2e508 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5801 [inline]
 #3: ffff888025c2e508 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x21a1/0x49c0 drivers/usb/core/hub.c:5883
 #4: ffff8880257f7868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5399 [inline]
 #4: ffff8880257f7868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5641 [inline]
 #4: ffff8880257f7868 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5801 [inline]
 #4: ffff8880257f7868 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x21c9/0x49c0 drivers/usb/core/hub.c:5883
1 lock held by syz.1.1977/12527:
3 locks held by syz-executor/12531:

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d c3 bf 39 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56
RSP: 0018:ffffffff8ca07d80 EFLAGS: 000002c2
RAX: 34fcaf02bc583100 RBX: ffffffff81618a7b RCX: 34fcaf02bc583100
RDX: 0000000000000001 RSI: ffffffff8aaab2c0 RDI: ffffffff8afc6d00
RBP: ffffffff8ca07eb8 R08: ffff8880b8e36d4b R09: 1ffff110171c6da9
R10: dffffc0000000000 R11: ffffed10171c6daa R12: ffffffff8e4a7fa8
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1952670
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f95ed1b66c0 CR3: 0000000076bde000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1eb/0x510 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 rest_init+0x2e2/0x300 init/main.c:732
 arch_call_rest_init+0xe/0x10 init/main.c:829
 start_kernel+0x459/0x4e0 init/main.c:1074
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/07 19:43 linux-6.6.y a5df3a702b2c 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in hub_port_init
* Struck through repros no longer work on HEAD.