* [syzbot] [i2c?] [usb?] INFO: task hung in em28xx_i2c_unregister
@ 2026-08-31 21:17 syzbot
2026-09-01 1:26 ` Hillf Danton
0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2026-08-31 21:17 UTC (permalink / raw)
To: andi.shyti, linux-i2c, linux-kernel, linux-usb, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: a23cbb05744b Merge tag 'timers-urgent-2026-08-30' of git:/..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12a6d379580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=f669f02a0fcc5b2148f2
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d1f379580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eed599d932fb/disk-a23cbb05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74e8c268c325/vmlinux-a23cbb05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aa91aebf1baf/bzImage-a23cbb05.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f669f02a0fcc5b2148f2@syzkaller.appspotmail.com
INFO: task kworker/1:3:1865 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:3 state:D stack:22152 pid:1865 tgid:1865 ppid:2 task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7362
schedule_timeout+0xc0/0x2c0 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:100 [inline]
__wait_for_common kernel/sched/completion.c:121 [inline]
wait_for_common kernel/sched/completion.c:132 [inline]
wait_for_completion+0x2ca/0x5e0 kernel/sched/completion.c:153
i2c_del_adapter+0x281/0x430 drivers/i2c/i2c-core-base.c:1841
em28xx_i2c_unregister+0x4b/0x60 drivers/media/usb/em28xx/em28xx-i2c.c:1029
em28xx_release_resources+0x14c/0x240 drivers/media/usb/em28xx/em28xx-cards.c:3764
em28xx_usb_disconnect+0x19f/0x2f0 drivers/media/usb/em28xx/em28xx-cards.c:4455
usb_unbind_interface+0x295/0x9f0 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:618 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x4f5/0x880 drivers/base/dd.c:1372
bus_remove_device+0x444/0x560 drivers/base/bus.c:664
device_del+0x524/0x8f0 drivers/base/core.c:3965
usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478
usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2350
hub_port_connect drivers/usb/core/hub.c:5420 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
port_event drivers/usb/core/hub.c:5884 [inline]
hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5966
process_one_work kernel/workqueue.c:3387 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
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>
INFO: task syz.4.136:6293 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.136 state:D stack:27896 pid:6293 tgid:6293 ppid:5809 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7362
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
device_lock include/linux/device.h:1104 [inline]
usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
ptrace_notify+0x27c/0x2b0 kernel/signal.c:2524
ptrace_report_syscall include/linux/ptrace.h:416 [inline]
ptrace_report_syscall_exit+0x2d/0x50 include/linux/ptrace.h:477
arch_ptrace_report_syscall_exit include/linux/entry-common.h:233 [inline]
syscall_exit_work include/linux/entry-common.h:266 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:297 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:334 [inline]
do_syscall_64+0x4a0/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd16879e159
RSP: 002b:00007fd168b4fba8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fd168b4fc90 RCX: 00007fd16879e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004d940 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2e620000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd168a25fac R14: 00007fd168a25fa8 R15: 00007fd168a25fa0
</TASK>
INFO: task syz.2.135:6294 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.135 state:D stack:27096 pid:6294 tgid:6294 ppid:5785 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7362
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
device_lock include/linux/device.h:1104 [inline]
usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
ptrace_notify+0x27c/0x2b0 kernel/signal.c:2524
ptrace_report_syscall include/linux/ptrace.h:416 [inline]
ptrace_report_syscall_exit+0x2d/0x50 include/linux/ptrace.h:477
arch_ptrace_report_syscall_exit include/linux/entry-common.h:233 [inline]
syscall_exit_work include/linux/entry-common.h:266 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:297 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:334 [inline]
do_syscall_64+0x4a0/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1b3299e159
RSP: 002b:00007f1b32d4fba8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f1b32d4fc90 RCX: 00007f1b3299e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004d997 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2d220000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1b32c25fac R14: 00007f1b32c25fa8 R15: 00007f1b32c25fa0
</TASK>
INFO: task syz.5.133:6295 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.133 state:D stack:27096 pid:6295 tgid:6295 ppid:5796 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7362
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
device_lock include/linux/device.h:1104 [inline]
usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
ptrace_notify+0x27c/0x2b0 kernel/signal.c:2524
ptrace_report_syscall include/linux/ptrace.h:416 [inline]
ptrace_report_syscall_exit+0x2d/0x50 include/linux/ptrace.h:477
arch_ptrace_report_syscall_exit include/linux/entry-common.h:233 [inline]
syscall_exit_work include/linux/entry-common.h:266 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:297 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:334 [inline]
do_syscall_64+0x4a0/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe6b1f9e159
RSP: 002b:00007fe6b234fba8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fe6b234fc90 RCX: 00007fe6b1f9e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004d99d R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2dd20000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe6b2225fac R14: 00007fe6b2225fa8 R15: 00007fe6b2225fa0
</TASK>
INFO: task syz.0.132:6296 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.132 state:D stack:27096 pid:6296 tgid:6296 ppid:5770 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7362
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
device_lock include/linux/device.h:1104 [inline]
usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
ptrace_notify+0x27c/0x2b0 kernel/signal.c:2524
ptrace_report_syscall include/linux/ptrace.h:416 [inline]
ptrace_report_syscall_exit+0x2d/0x50 include/linux/ptrace.h:477
arch_ptrace_report_syscall_exit include/linux/entry-common.h:233 [inline]
syscall_exit_work include/linux/entry-common.h:266 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:297 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:334 [inline]
do_syscall_64+0x4a0/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa0c859e159
RSP: 002b:00007fa0c894fba8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fa0c894fc90 RCX: 00007fa0c859e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004d9a7 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2c820000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa0c8825fac R14: 00007fa0c8825fa8 R15: 00007fa0c8825fa0
</TASK>
INFO: task syz.1.134:6297 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.134 state:D stack:27592 pid:6297 tgid:6297 ppid:5775 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7362
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
device_lock include/linux/device.h:1104 [inline]
usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
ptrace_notify+0x27c/0x2b0 kernel/signal.c:2524
ptrace_report_syscall include/linux/ptrace.h:416 [inline]
ptrace_report_syscall_exit+0x2d/0x50 include/linux/ptrace.h:477
arch_ptrace_report_syscall_exit include/linux/entry-common.h:233 [inline]
syscall_exit_work include/linux/entry-common.h:266 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:297 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:334 [inline]
do_syscall_64+0x4a0/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa70379e159
RSP: 002b:00007fa703b4fba8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fa703b4fc90 RCX: 00007fa70379e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004d9ba R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2cb20000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa703a25fac R14: 00007fa703a25fa8 R15: 00007fa703a25fa0
</TASK>
Showing all locks held in the system:
locks held by pr/ttyS0/16: 2, last CPU#1:
#0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
#0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
#0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
#1: ffffffff9ad31098 (&port_lock_key){-...}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline]
#1: ffffffff9ad31098 (&port_lock_key){-...}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0 drivers/tty/serial/8250/8250_core.c:413
locks held by khungtaskd/32: 1, last CPU#0:
#0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6837
locks held by kworker/1:3/1865: 6, on CPU#1:
#0: ffff8880232e7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff8880232e7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff8880232e7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
#0: ffff8880232e7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
#1: ffffc900063f7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc900063f7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc900063f7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
#1: ffffc900063f7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
#2: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
#3: ffff888024c051d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff888024c051d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0 drivers/usb/core/hub.c:2341
#4: ffff88802b4031a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff88802b4031a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
#4: ffff88802b4031a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369
#5: ffff888058201cf0 (&dev->lock#3){+.+.}-{4:4}, at: em28xx_release_resources+0x75/0x240 drivers/media/usb/em28xx/em28xx-cards.c:3758
locks held by getty/5374: 2, on CPU#0:
#0: ffff888036cae0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by udevd/6066: 4, on CPU#1:
#0: ffff888035016f38 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0 fs/seq_file.c:183
#1: ffff888055824c80 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5d/0x420 fs/kernfs/file.c:165
#2: ffff88807ff67a58 (kn->active#28){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#2: ffff88807ff67a58 (kn->active#28){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x420 fs/kernfs/file.c:166
#3: ffff888024c051d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline]
#3: ffff888024c051d8 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
locks held by syz.4.136/6293: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
locks held by syz.2.135/6294: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
locks held by syz.5.133/6295: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
locks held by syz.0.132/6296: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
locks held by syz.1.134/6297: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_release+0x80/0x780 drivers/usb/core/devio.c:1099
locks held by syz.6.137/6384: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.7.138/6385: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.8.139/6386: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.9.140/6387: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.3.141/6388: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.0.142/6484: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.1.143/6485: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.2.144/6486: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.4.146/6490: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.6.150/6564: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.7.151/6565: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.8.153/6566: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.9.154/6567: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.3.162/6643: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.0.163/6645: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.1.164/6646: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.2.166/6648: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.4.174/6724: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.7.176/6725: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.6.175/6726: 1, on CPU#1:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.8.178/6727: 1, on CPU#0:
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802a64a1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd7/0x1030 kernel/hung_task.c:561
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>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 16 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 5e e2 55 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 af ab c5 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 1a e4 74 06 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001578b8 EFLAGS: 00000002
RAX: 1ffffffff35a6200 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff8571d400 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9ad310c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124dda000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe39d825fa4 CR3: 000000006a5fc000 CR4: 00000000003526f0
Call Trace:
<TASK>
serial_in drivers/tty/serial/8250/8250.h:128 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2013
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline]
__serial8250_console_fifo_write+0x346/0x3e0 drivers/tty/serial/8250/8250_port.c:3372
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline]
__serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline]
serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3493
nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1
nbcon_emit_one kernel/printk/nbcon.c:1157 [inline]
nbcon_kthread_func+0x679/0x880 kernel/printk/nbcon.c:1271
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>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [syzbot] [i2c?] [usb?] INFO: task hung in em28xx_i2c_unregister
2026-08-31 21:17 [syzbot] [i2c?] [usb?] INFO: task hung in em28xx_i2c_unregister syzbot
@ 2026-09-01 1:26 ` Hillf Danton
2026-09-01 6:55 ` syzbot
0 siblings, 1 reply; 3+ messages in thread
From: Hillf Danton @ 2026-09-01 1:26 UTC (permalink / raw)
To: syzbot; +Cc: linux-kernel, syzkaller-bugs
> Date: Mon, 31 Aug 2026 14:17:40 -0700 [thread overview]
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: a23cbb05744b Merge tag 'timers-urgent-2026-08-30' of git:/..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12a6d379580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
> dashboard link: https://syzkaller.appspot.com/bug?extid=f669f02a0fcc5b2148f2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d1f379580000
#syz test
--- x/drivers/i2c/i2c-core-base.c
+++ y/drivers/i2c/i2c-core-base.c
@@ -1844,7 +1844,7 @@ void i2c_del_adapter(struct i2c_adapter
*/
init_completion(&adap->dev_released);
device_unregister(&adap->dev);
- wait_for_completion(&adap->dev_released);
+ wait_for_completion_timeout(&adap->dev_released, 50 * HZ);
/* free bus id */
mutex_lock(&core_lock);
--
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [syzbot] [i2c?] [usb?] INFO: task hung in em28xx_i2c_unregister
2026-09-01 1:26 ` Hillf Danton
@ 2026-09-01 6:55 ` syzbot
0 siblings, 0 replies; 3+ messages in thread
From: syzbot @ 2026-09-01 6:55 UTC (permalink / raw)
To: hdanton, linux-kernel, syzkaller-bugs
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in module_put
BUG: unable to handle page fault for address: ffffffff8188f427
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD eb4b067 P4D eb4b067 PUD eb4c063 PMD 18001a1
Oops: Oops: 0003 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6682 Comm: syz.3.60 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline]
RIP: 0010:raw_atomic_try_cmpxchg include/linux/atomic/atomic-arch-fallback.h:2130 [inline]
RIP: 0010:raw_atomic_dec_if_positive include/linux/atomic/atomic-arch-fallback.h:2560 [inline]
RIP: 0010:atomic_dec_if_positive include/linux/atomic/atomic-instrumented.h:1594 [inline]
RIP: 0010:module_put+0x4c/0x1a0 kernel/module/main.c:956
Code: f0 04 00 00 4c 89 f7 be 04 00 00 00 e8 cd da 86 00 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 75 76 41 8b 06 89 c1 ff c9 78 53 <f0> 41 0f b1 0e 75 f3 4c 8b 74 24 28 66 90 65 8b 05 a7 b3 e3 11 83
RSP: 0018:ffffc9000420f968 EFLAGS: 00010206
RAX: 000000000004be8e RBX: ffffffff8188ef37 RCX: 000000000004be8d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8188f427
RBP: dffffc0000000000 R08: ffffffff8188f42a R09: 1ffffffff0311e85
R10: dffffc0000000000 R11: fffffbfff0311e86 R12: dffffc0000000000
R13: ffff888073654ac8 R14: ffffffff8188f427 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888124cda000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff8188f427 CR3: 000000002933a000 CR4: 00000000003526f0
Call Trace:
<TASK>
i2c_put_adapter+0x3e/0x60 drivers/i2c/i2c-core-base.c:2660
i2cdev_release+0x5a/0x90 drivers/i2c/i2c-dev.c:632
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x73a/0x2360 kernel/exit.c:1008
do_group_exit+0x22d/0x2f0 kernel/exit.c:1151
get_signal+0x121b/0x12c0 kernel/signal.c:3039
arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf1d95e98e
Code: Unable to access opcode bytes at 0x7fbf1d95e964.
RSP: 002b:00007fbf1e795b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: 0000000000000004 RBX: 00007fbf1e7966c0 RCX: 00007fbf1d95e98e
RDX: 0000000000080100 RSI: 00007fbf1e795c00 RDI: ffffffffffffff9c
RBP: 00007fbf1e795c00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007fbf1dc26038 R14: 00007fbf1dc25fa0 R15: 00007fbf1dd4fa48
</TASK>
Modules linked in:
CR2: ffffffff8188f427
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline]
RIP: 0010:raw_atomic_try_cmpxchg include/linux/atomic/atomic-arch-fallback.h:2130 [inline]
RIP: 0010:raw_atomic_dec_if_positive include/linux/atomic/atomic-arch-fallback.h:2560 [inline]
RIP: 0010:atomic_dec_if_positive include/linux/atomic/atomic-instrumented.h:1594 [inline]
RIP: 0010:module_put+0x4c/0x1a0 kernel/module/main.c:956
Code: f0 04 00 00 4c 89 f7 be 04 00 00 00 e8 cd da 86 00 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 75 76 41 8b 06 89 c1 ff c9 78 53 <f0> 41 0f b1 0e 75 f3 4c 8b 74 24 28 66 90 65 8b 05 a7 b3 e3 11 83
RSP: 0018:ffffc9000420f968 EFLAGS: 00010206
RAX: 000000000004be8e RBX: ffffffff8188ef37 RCX: 000000000004be8d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8188f427
RBP: dffffc0000000000 R08: ffffffff8188f42a R09: 1ffffffff0311e85
R10: dffffc0000000000 R11: fffffbfff0311e86 R12: dffffc0000000000
R13: ffff888073654ac8 R14: ffffffff8188f427 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888124cda000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff8188f427 CR3: 000000002933a000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: f0 04 00 lock add $0x0,%al
3: 00 4c 89 f7 add %cl,-0x9(%rcx,%rcx,4)
7: be 04 00 00 00 mov $0x4,%esi
c: e8 cd da 86 00 call 0x86dade
11: 4c 89 f0 mov %r14,%rax
14: 48 c1 e8 03 shr $0x3,%rax
18: 42 0f b6 04 20 movzbl (%rax,%r12,1),%eax
1d: 84 c0 test %al,%al
1f: 75 76 jne 0x97
21: 41 8b 06 mov (%r14),%eax
24: 89 c1 mov %eax,%ecx
26: ff c9 dec %ecx
28: 78 53 js 0x7d
* 2a: f0 41 0f b1 0e lock cmpxchg %ecx,(%r14) <-- trapping instruction
2f: 75 f3 jne 0x24
31: 4c 8b 74 24 28 mov 0x28(%rsp),%r14
36: 66 90 xchg %ax,%ax
38: 65 8b 05 a7 b3 e3 11 mov %gs:0x11e3b3a7(%rip),%eax # 0x11e3b3e6
3f: 83 .byte 0x83
Tested on:
commit: 786262be Merge tag 'edac_updates_for_v7.3_rc2' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16cf9c15580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=f669f02a0fcc5b2148f2
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=142e9c15580000
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-01 6:55 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-08-31 21:17 [syzbot] [i2c?] [usb?] INFO: task hung in em28xx_i2c_unregister syzbot
2026-09-01 1:26 ` Hillf Danton
2026-09-01 6:55 ` syzbot
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