syzbot

INFO: task kworker/0:6:5909 blocked for more than 143 seconds.
      Not tainted 6.16.0-rc3-syzkaller-00072-gee88bddf7f2f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:6     state:D stack:19480 pid:5909  tgid:5909  ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x16f5/0x4d00 kernel/sched/core.c:6785
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6878
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6935
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:747
 hub_port_connect drivers/usb/core/hub.c:5433 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
 port_event drivers/usb/core/hub.c:5835 [inline]
 hub_event+0x21cb/0x4a00 drivers/usb/core/hub.c:5917
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e13ee60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e13ee60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e13ee60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
5 locks held by kworker/1:1/44:
 #0: ffff8880216f3d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff8880216f3d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc90000b47bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000b47bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffff888144f51198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline]
 #2: ffff888144f51198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a00 drivers/usb/core/hub.c:5863
 #3: ffff888144f54510 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3220 [inline]
 #3: ffff888144f54510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5432 [inline]
 #3: ffff888144f54510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
 #3: ffff888144f54510 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5835 [inline]
 #3: ffff888144f54510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x21a3/0x4a00 drivers/usb/core/hub.c:5917
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5433 [inline]
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5835 [inline]
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21cb/0x4a00 drivers/usb/core/hub.c:5917
5 locks held by kworker/1:2/1209:
2 locks held by getty/5595:
 #0: ffff888030dcb0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
5 locks held by kworker/0:6/5909:
 #0: ffff8880216f3d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff8880216f3d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc9000455fbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000455fbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffff888144f23198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline]
 #2: ffff888144f23198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a00 drivers/usb/core/hub.c:5863
 #3: ffff888144f26510 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3220 [inline]
 #3: ffff888144f26510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5432 [inline]
 #3: ffff888144f26510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
 #3: ffff888144f26510 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5835 [inline]
 #3: ffff888144f26510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x21a3/0x4a00 drivers/usb/core/hub.c:5917
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5433 [inline]
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5835 [inline]
 #4: ffff888144bb3a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21cb/0x4a00 drivers/usb/core/hub.c:5917
4 locks held by udevd/6379:
 #0: ffff88806d84dc30 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xb7/0xe10 fs/seq_file.c:182
 #1: ffff8880b8723f08 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x314/0x6d0 kernel/sched/psi.c:975
 #2: ffffffff99caf770 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0xbb/0x420 lib/debugobjects.c:818
 #3: ffff88807a7fce08 (&lockref->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #3: ffff88807a7fce08 (&lockref->lock){+.+.}-{3:3}, at: fast_dput+0xdd/0x430 fs/dcache.c:827
1 lock held by syz.2.2876/16483:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-rc3-syzkaller-00072-gee88bddf7f2f #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:470
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5821 Comm: syz-executor Not tainted 6.16.0-rc3-syzkaller-00072-gee88bddf7f2f #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:206 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:238 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:test_ti_thread_flag include/linux/thread_info.h:126 [inline]
RIP: 0010:fpregs_assert_state_consistent+0x71/0x150 arch/x86/kernel/fpu/core.c:862
Code: e8 74 f5 57 00 81 e5 00 00 20 00 0f 85 a3 00 00 00 e8 23 f1 57 00 4c 8d b3 40 19 00 00 48 89 df be 08 00 00 00 e8 3f 77 bb 00 <48> 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 b9 74 bb 00
RSP: 0018:ffffc90003f9feb8 EFLAGS: 00000056
RAX: ffffffff81685d01 RBX: ffff888031941e00 RCX: ffffffff81685d61
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888031941e00
RBP: 0000000000000000 R08: ffff888031941e07 R09: 1ffff110063283c0
R10: dffffc0000000000 R11: ffffed10063283c1 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888031943740 R15: dffffc0000000000
FS:  000055556c464500(0000) GS:ffff888125d51000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff265d7e2d8 CR3: 0000000078944000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_exit_to_user_mode_prepare+0x9/0x50 arch/x86/include/asm/entry-common.h:63
 exit_to_user_mode_prepare include/linux/entry-common.h:332 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x177/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f73d158d2fd
Code: a8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb b5 e8 a8 48 00 00 0f 1f 84 00 00 00 00 00 80 3d 41 82 1f 00 00 74 17 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec
RSP: 002b:00007ffe38486c38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f73d158d2fd
RDX: 0000000000000004 RSI: 00007ffe38486c4c RDI: 0000000000000003
RBP: 0000000000000000 R08: 000000002c2faa1e R09: 7fffffffffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe38487060
R13: 0000000000000004 R14: 00007ffe38486c4c R15: 00007ffe38486ce0
 </TASK>