Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in r871xu_dev_remove
INFO: task kworker/1:1:28 blocked for more than 143 seconds.
Not tainted 6.6.44-syzkaller-g721391060066-dirty #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1 state:D stack:27456 pid:28 ppid:2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0xca5/0x30d0 kernel/sched/core.c:6698
schedule+0xe7/0x1b0 kernel/sched/core.c:6772
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6831
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x5bd/0x9d0 kernel/locking/mutex.c:747
unregister_netdev+0x12/0x30 net/core/dev.c:11102
r871xu_dev_remove+0x291/0x480 drivers/staging/rtl8712/usb_intf.c:596
usb_unbind_interface+0x1e0/0x8d0 drivers/usb/core/driver.c:458
device_remove drivers/base/dd.c:569 [inline]
device_remove+0x122/0x170 drivers/base/dd.c:561
__device_release_driver drivers/base/dd.c:1272 [inline]
device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1295
bus_remove_device+0x22f/0x420 drivers/base/bus.c:574
device_del+0x39d/0xa60 drivers/base/core.c:3838
usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1416
usb_disconnect+0x2e1/0x890 drivers/usb/core/hub.c:2276
hub_port_connect drivers/usb/core/hub.c:5329 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5629 [inline]
port_event drivers/usb/core/hub.c:5789 [inline]
hub_event+0x1be4/0x4f50 drivers/usb/core/hub.c:5871
process_one_work+0x889/0x15e0 kernel/workqueue.c:2631
process_scheduled_works kernel/workqueue.c:2704 [inline]
worker_thread+0x8b9/0x12a0 kernel/workqueue.c:2785
kthread+0x2c6/0x3b0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:293
</TASK>
Showing all locks held in the system:
3 locks held by kworker/0:1/9:
#0: ffff888109ba9138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x789/0x15e0 kernel/workqueue.c:2606
#1: ffffc9000009fd80 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7eb/0x15e0 kernel/workqueue.c:2607
#2: ffffffff89ad6da8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4684
6 locks held by kworker/1:1/28:
#0: ffff88810a64fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x789/0x15e0 kernel/workqueue.c:2606
#1: ffffc900001e7d80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7eb/0x15e0 kernel/workqueue.c:2607
#2: ffff888104f2b190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:992 [inline]
#2: ffff888104f2b190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f50 drivers/usb/core/hub.c:5817
#3: ffff888114cd9190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:992 [inline]
#3: ffff888114cd9190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x10a/0x890 drivers/usb/core/hub.c:2267
#4: ffff888100f5b160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:992 [inline]
#4: ffff888100f5b160 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
#4: ffff888100f5b160 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1292
#5: ffffffff89ad6da8 (rtnl_mutex){+.+.}-{3:3}, at: unregister_netdev+0x12/0x30 net/core/dev.c:11102
1 lock held by khungtaskd/29:
#0: ffffffff888aece0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff888aece0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff888aece0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6614
1 lock held by kworker/u4:7/1043:
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:558 [inline]
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1375 [inline]
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1684 [inline]
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x290/0x30d0 kernel/sched/core.c:6613
3 locks held by kworker/1:2/1939:
#0: ffff888109ba9138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x789/0x15e0 kernel/workqueue.c:2606
#1: ffffc9000393fd80 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7eb/0x15e0 kernel/workqueue.c:2607
#2: ffffffff89ad6da8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4684
1 lock held by klogd/2494:
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:558 [inline]
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1375 [inline]
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1684 [inline]
#0: ffff8881f653b318 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x290/0x30d0 kernel/sched/core.c:6613
2 locks held by dhcpcd/2543:
#0: ffffffff89ad6da8 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x1d3/0x1f10 net/ipv4/devinet.c:1091
#1: ffff88811928cdb0 (&padapter->mutex_start){+.+.}-{3:3}, at: netdev_open+0x32/0x840 drivers/staging/rtl8712/os_intfs.c:392
2 locks held by getty/2563:
#0: ffff88810af530a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc900000432f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfc9/0x1480 drivers/tty/n_tty.c:2216
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.6.44-syzkaller-g721391060066-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 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+0xf87/0x1210 kernel/hung_task.c:379
kthread+0x2c6/0x3b0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:293
</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:48 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt+0x1b/0x30 drivers/acpi/processor_idle.c:111
Tested on:
commit: 72139106 Linux 6.6.44
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17be7b65980000
kernel config: https://syzkaller.appspot.com/x/.config?x=cc2e57d9f035477b
dashboard link: https://syzkaller.appspot.com/bug?extid=ca2eaaadab55de6a5a42
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=11be7b65980000
