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: 11d, last: 11d
Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in hub_event usb 19 2026d 2201d 0/28 auto-closed as invalid on 2020/01/02 20:34
linux-4.14 INFO: task hung in hub_event 5 1197d 1219d 0/1 auto-closed as invalid on 2022/05/10 10:19
linux-6.1 INFO: task hung in hub_event (2) 1 579d 579d 0/3 auto-obsoleted due to no activity on 2023/12/29 05:51
upstream INFO: task hung in hub_event (2) usb 27 1196d 1241d 0/28 closed as invalid on 2022/02/08 09:40
linux-5.15 INFO: task hung in hub_event (2) 1 485d 485d 0/3 auto-obsoleted due to no activity on 2024/04/01 17:35
upstream INFO: task hung in hub_event (3) usb 370 1d06h 828d 0/28 upstream: reported on 2023/01/14 20:19
linux-6.1 INFO: task hung in hub_event (3) 8 14d 17d 0/3 upstream: reported on 2025/04/04 18:12
linux-5.15 INFO: task hung in hub_event (3) 1 274d 274d 0/3 auto-obsoleted due to no activity on 2024/10/29 18:51
linux-5.15 INFO: task hung in hub_event 3 597d 760d 0/3 auto-obsoleted due to no activity on 2023/12/12 00:26
linux-6.1 INFO: task hung in hub_event 2 742d 771d 0/3 auto-obsoleted due to no activity on 2023/08/08 09:24

Sample crash report:
INFO: task kworker/0:1:13 blocked for more than 144 seconds.
      Not tainted 5.15.179-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1     state:D stack:24824 pid:   13 ppid:     2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5029 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6375
 schedule+0x11b/0x1f0 kernel/sched/core.c:6458
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6517
 __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/0:1/13:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90000d27d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff8880256a8220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff8880256a8220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8880256ab5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8880256ab5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8880256ab5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8880256ab5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8880256ab5c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff88814821f768 (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
5 locks held by kworker/1:2/1106:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900044d7d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888148202220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888148202220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8881482055c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8881482055c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8881482055c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8881482055c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8881482055c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff88814821f768 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
2 locks held by kworker/u4:3/1196:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000491fd20 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
5 locks held by kworker/0:3/1335:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90004eefd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff8881481b2220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff8881481b2220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8881481b55c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8881481b55c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8881481b55c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8881481b55c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8881481b55c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
1 lock held by udevd/3545:
 #0: ffff888020c58518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x14d/0xa50 block/bdev.c:820
2 locks held by getty/3933:
 #0: ffff88802c6dc098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002ce32e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
2 locks held by syz-executor/4173:
 #0: ffff888020c55d18 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:915
 #1: ffff8880210b6468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1365
3 locks held by kworker/0:4/4208:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900030afd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x280/0x740 kernel/rcu/tree_exp.h:845
5 locks held by kworker/1:4/4210:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900030dfd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888025654220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888025654220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8880256575c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8880256575c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8880256575c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8880256575c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8880256575c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
3 locks held by kworker/u4:5/4225:
5 locks held by kworker/0:8/4248:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90002e0fd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff8881481e0220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff8881481e0220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8881481e35c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8881481e35c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8881481e35c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8881481e35c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8881481e35c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888148147368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
1 lock held by udevd/4301:
 #0: ffff888020c58518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x14d/0xa50 block/bdev.c:820
4 locks held by kworker/u4:15/4930:
 #0: ffff8880b8e3a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa8/0x140 kernel/sched/core.c:483
 #1: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x53d/0x810 kernel/sched/psi.c:891
 #2: ffff888079094d40 (&wdev->mtx){+.+.}-{3:3}, at: sdata_lock net/mac80211/ieee80211_i.h:1036 [inline]
 #2: ffff888079094d40 (&wdev->mtx){+.+.}-{3:3}, at: ieee80211_ibss_work+0xa0/0x1480 net/mac80211/ibss.c:1685
 #3: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
1 lock held by udevd/4968:
 #0: ffff888020c55d18 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x14d/0xa50 block/bdev.c:820
5 locks held by kworker/0:10/5310:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900048afd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888148114220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888148114220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8881481175c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8881481175c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8881481175c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8881481175c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8881481175c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
5 locks held by kworker/1:10/6890:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90003f9fd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888025446220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888025446220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8881481095c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8881481095c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8881481095c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8881481095c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8881481095c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888023d8c168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
5 locks held by kworker/0:11/6971:
 #0: ffff8880183b2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000473fd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff88802562e220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff88802562e220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781
 #3: ffff8880256415c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline]
 #3: ffff8880256415c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 #3: ffff8880256415c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #3: ffff8880256415c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #3: ffff8880256415c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline]
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline]
 #4: ffff888025140568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835
3 locks held by kworker/1:13/7163:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90004cb7d20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x350/0x740 kernel/rcu/tree_exp.h:845
2 locks held by kworker/0:12/8012:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900032efd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
2 locks held by kworker/0:13/8074:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90003dafd20 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
2 locks held by syz.2.1022/8241:
 #0: ffff888020c58518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:915
 #1: ffff88814720c468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_release+0x4d/0x1f0 drivers/block/loop.c:2070

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.179-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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4301 Comm: udevd Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:lock_acquire+0xf5/0x4f0 kernel/locking/lockdep.c:5596
Code: 00 89 d8 48 0f a3 05 02 be a7 0c 73 0d e8 93 6b 08 00 84 c0 0f 84 b9 02 00 00 48 c7 c0 54 d3 0a 8e 48 c1 e8 03 42 0f b6 04 28 <84> c0 0f 85 dd 02 00 00 83 3d 80 f1 a7 0c 00 0f 84 3f 01 00 00 65
RSP: 0018:ffffc90000007b60 EFLAGS: 00000807
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8162e19c
RDX: 0000000000000000 RSI: ffffffff8af9fa60 RDI: ffffffff8af9fa20
RBP: ffffc90000007cb0 R08: dffffc0000000000 R09: fffffbfff1c153f6
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000000f74
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100f9f0470
FS:  00007fb6c4b2dc80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f999e245000 CR3: 0000000020b63000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:363 [inline]
 snd_hrtimer_callback+0x56/0x370 sound/core/hrtimer.c:38
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x598/0xcf0 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x13b/0x4b0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
Code: 9c 8f 44 24 20 42 80 3c 23 00 74 08 4c 89 f7 e8 72 f0 80 f7 f6 44 24 21 02 75 4e 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 97 00 0e f7 65 8b 05 08 d1 b8 75 85 c0 74 3f 48 c7 04 24 0e 36
RSP: 0018:ffffc900032ff800 EFLAGS: 00000206
RAX: f3fa1596ed295700 RBX: 1ffff9200065ff04 RCX: ffffffff96a95f03
RDX: dffffc0000000000 RSI: ffffffff8aab2a60 RDI: 0000000000000001
RBP: ffffc900032ff8a0 R08: ffffffff81871b70 R09: fffffbfff2d8ade9
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff9200065ff00 R14: ffffc900032ff820 R15: 0000000000000246
 __debug_check_no_obj_freed lib/debugobjects.c:982 [inline]
 debug_check_no_obj_freed+0x455/0x4e0 lib/debugobjects.c:1003
 free_pages_prepare mm/page_alloc.c:1345 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x281/0xcf0 mm/page_alloc.c:3317
 free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
 free_slab mm/slub.c:2015 [inline]
 discard_slab mm/slub.c:2021 [inline]
 __unfreeze_partials+0x1b7/0x210 mm/slub.c:2507
 put_cpu_partial+0x132/0x1a0 mm/slub.c:2587
 do_slab_free mm/slub.c:3487 [inline]
 ___cache_free+0xe3/0x100 mm/slub.c:3506
 qlist_free_all+0x36/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x162/0x180 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0xf3/0x280 mm/slub.c:3233
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 locks_alloc_lock fs/locks.c:346 [inline]
 flock_make_lock fs/locks.c:515 [inline]
 __do_sys_flock fs/locks.c:2200 [inline]
 __se_sys_flock+0x15d/0x5b0 fs/locks.c:2181
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb6c4c58fc7
Code: ae 30 fa ff 48 8b 04 24 eb 05 e8 ec 33 00 00 48 83 c4 68 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 49 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 31 9e 0d 00 f7 d8 64 89 01 48
RSP: 002b:00007fffa7a79de8 EFLAGS: 00000202 ORIG_RAX: 0000000000000049
RAX: ffffffffffffffda RBX: 000055ded0ce5400 RCX: 00007fb6c4c58fc7
RDX: 00000000000a0800 RSI: 0000000000000005 RDI: 0000000000000008
RBP: 000055ded0ce5400 R08: 00000000ffffffff R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000202 R12: 000055ded0cf59c0
R13: 000055ded0cd7060 R14: 0000000000000008 R15: 000055ded0cc6910
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.