INFO: task hung in snd_seq_midisynth_remove

Status: upstream: reported on 2026/08/03 07:27
Reported-by: syzbot+188512c7f571c94b5006@syzkaller.appspotmail.com
First crash: 76d, last: 44d
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in snd_seq_midisynth_remove 1 7 36d 81d 0/3 upstream: reported on 2026/07/29 13:07

Sample crash report:
INFO: task kworker/1:8:4236 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:8     state:D stack:24688 pid: 4236 ppid:     2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 snd_seq_midisynth_remove+0x68/0x4e0 sound/core/seq/seq_midi.c:432
 __device_release_driver drivers/base/dd.c:1249 [inline]
 device_release_driver_internal+0x487/0x710 drivers/base/dd.c:1282
 bus_remove_device+0x2dd/0x400 drivers/base/bus.c:531
 device_del+0x63f/0xa80 drivers/base/core.c:3615
 snd_seq_device_dev_disconnect+0x39/0x40 sound/core/seq_device.c:182
 __snd_device_disconnect sound/core/device.c:63 [inline]
 snd_device_disconnect_all+0xcf/0x200 sound/core/device.c:215
 snd_card_disconnect+0x385/0x7d0 sound/core/init.c:528
 usb_audio_disconnect+0x283/0x6f0 sound/usb/card.c:971
 usb_unbind_interface+0x203/0x870 drivers/usb/core/driver.c:458
 __device_release_driver drivers/base/dd.c:1249 [inline]
 device_release_driver_internal+0x487/0x710 drivers/base/dd.c:1282
 bus_remove_device+0x2dd/0x400 drivers/base/bus.c:531
 device_del+0x63f/0xa80 drivers/base/core.c:3615
 usb_disable_device+0x3e7/0x8a0 drivers/usb/core/message.c:1472
 usb_disconnect+0x33c/0x8a0 drivers/usb/core/hub.c:2292
 hub_port_connect drivers/usb/core/hub.c:5346 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5642 [inline]
 port_event drivers/usb/core/hub.c:5804 [inline]
 hub_event+0x1d64/0x5260 drivers/usb/core/hub.c:5886
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task syz.6.1656:11543 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.1656      state:D stack:26032 pid:11543 ppid:  5110 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 gadget_dev_desc_UDC_store+0xed/0x2e0 drivers/usb/gadget/configfs.c:276
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x30b/0x400 fs/configfs/file.c:229
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3c02d6a159
RSP: 002b:00007f3c00f80028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3c02ff2180 RCX: 00007f3c02d6a159
RDX: 000000000000000b RSI: 0000200000000680 RDI: 0000000000000006
RBP: 00007f3c02e01024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3c02ff2218 R14: 00007f3c02ff2180 R15: 00007fffb892a408
 </TASK>
INFO: task syz.3.1693:11668 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.1693      state:D stack:24528 pid:11668 ppid:  4196 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 gadget_dev_desc_UDC_store+0xed/0x2e0 drivers/usb/gadget/configfs.c:276
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x30b/0x400 fs/configfs/file.c:229
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fddae0dc159
RSP: 002b:00007fddac2f2028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fddae364180 RCX: 00007fddae0dc159
RDX: 000000000000000b RSI: 0000200000000680 RDI: 0000000000000007
RBP: 00007fddae173024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fddae364218 R14: 00007fddae364180 R15: 00007fff58dc0d78
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/1:0/21:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90000db7d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff88803dde4240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x283/0x3380 drivers/net/netdevsim/fib.c:1480
1 lock held by khungtaskd/27:
 #0: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3948:
 #0: ffff88814d0bf098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900026562e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
8 locks held by kworker/1:8/4236:
 #0: ffff88801be48138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000317fd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff88814834b220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline]
 #2: ffff88814834b220 (&dev->mutex){....}-{3:3}, at: hub_event+0x178/0x5260 drivers/usb/core/hub.c:5832
 #3: ffff88807d395220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline]
 #3: ffff88807d395220 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0xf8/0x8a0 drivers/usb/core/hub.c:2283
 #4: ffff88807639b1a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline]
 #4: ffff88807639b1a8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1064 [inline]
 #4: ffff88807639b1a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa1/0x710 drivers/base/dd.c:1279
 #5: ffffffff8d3f5a08 (register_mutex#6){+.+.}-{3:3}, at: usb_audio_disconnect+0xd0/0x6f0 sound/usb/card.c:960
 #6: ffff88802397e200 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline]
 #6: ffff88802397e200 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1064 [inline]
 #6: ffff88802397e200 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa1/0x710 drivers/base/dd.c:1279
 #7: ffffffff8d3bcca8 (register_mutex#7){+.+.}-{3:3}, at: snd_seq_midisynth_remove+0x68/0x4e0 sound/core/seq/seq_midi.c:432
2 locks held by kworker/0:11/4834:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000328fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
3 locks held by kworker/1:10/10262:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900040c7d00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #2: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
2 locks held by kworker/1:12/10266:
 #0: ffff888016c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900041d7d00 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
8 locks held by syz.0.1654/11534:
 #0: ffff8880649940f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff88801d94a460 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff8880772bf288 (&buffer->mutex){+.+.}-{3:3}, at: configfs_write_iter+0x7d/0x400 fs/configfs/file.c:226
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: configfs_write_iter+0x20e/0x400 fs/configfs/file.c:229
 #4: ffff888074961310 (&gi->lock){+.+.}-{3:3}, at: gadget_dev_desc_UDC_store+0xed/0x2e0 drivers/usb/gadget/configfs.c:276
 #5: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_unregister_driver+0x56/0x4c0 drivers/usb/gadget/udc/core.c:1651
 #6: ffff888075a58200 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline]
 #6: ffff888075a58200 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1064 [inline]
 #6: ffff888075a58200 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa1/0x710 drivers/base/dd.c:1279
 #7: ffffffff8d3bcca8 (register_mutex#7){+.+.}-{3:3}, at: snd_seq_midisynth_remove+0x68/0x4e0 sound/core/seq/seq_midi.c:432
5 locks held by syz.6.1656/11543:
 #0: ffff88805feed4f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff88801d94a460 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff88805f8f6288 (&buffer->mutex){+.+.}-{3:3}, at: configfs_write_iter+0x7d/0x400 fs/configfs/file.c:226
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: configfs_write_iter+0x20e/0x400 fs/configfs/file.c:229
 #4: ffff888074961310 (&gi->lock){+.+.}-{3:3}, at: gadget_dev_desc_UDC_store+0xed/0x2e0 drivers/usb/gadget/configfs.c:276
5 locks held by syz.3.1693/11668:
 #0: ffff88807c9c9770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff88801d94a460 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff88801ab9ca88 (&buffer->mutex){+.+.}-{3:3}, at: configfs_write_iter+0x7d/0x400 fs/configfs/file.c:226
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: configfs_write_iter+0x20e/0x400 fs/configfs/file.c:229
 #4: ffff888074961310 (&gi->lock){+.+.}-{3:3}, at: gadget_dev_desc_UDC_store+0xed/0x2e0 drivers/usb/gadget/configfs.c:276
1 lock held by syz.7.1749/11956:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.8.1763/12042:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
5 locks held by syz.9.1735/12066:
 #0: ffff88807da7d270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff88801d94a460 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff88802fe67088 (&buffer->mutex){+.+.}-{3:3}, at: configfs_write_iter+0x7d/0x400 fs/configfs/file.c:226
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: configfs_write_iter+0x20e/0x400 fs/configfs/file.c:229
 #4: ffff888074961310 (&gi->lock){+.+.}-{3:3}, at: gadget_dev_desc_UDC_store+0xed/0x2e0 drivers/usb/gadget/configfs.c:276
1 lock held by syz.5.1849/12514:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
5 locks held by syz.1.1868/12630:
 #0: ffff8880224719f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff88801d94a460 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff88807a1d4288 (&buffer->mutex){+.+.}-{3:3}, at: configfs_write_iter+0x7d/0x400 fs/configfs/file.c:226
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
 #3: ffff88801abed278 (&p->frag_sem){++++}-{3:3}, at: configfs_write_iter+0x20e/0x400 fs/configfs/file.c:229
 #4: ffff888074961310 (&gi->lock){+.+.}-{3:3}, at: os_desc_b_vendor_code_store+0xab/0x160 drivers/usb/gadget/configfs.c:835
1 lock held by syz.4.1913/12868:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.2.1929/13002:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.0.1930/13020:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.6.1933/13158:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.3.1926/13168:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.7.1934/13371:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.8.1935/13411:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.9.1936/13413:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.1.1940/13453:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
2 locks held by kworker/u4:26/13475:
1 lock held by syz.5.1943/13479:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.4.1939/13491:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.2.1946/13521:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.0.1945/13523:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.3.1947/13541:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.6.1948/13569:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.7.1951/13597:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.8.1952/13622:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.9.1953/13638:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.1.1954/13653:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.5.1955/13672:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
1 lock held by syz.4.1956/13693:
 #0: ffffffff8ced1388 (udc_lock){+.+.}-{3:3}, at: usb_gadget_probe_driver+0x7b/0x380 drivers/usb/gadget/udc/core.c:1604
2 locks held by syz-executor/13694:
 #0: ffffffff8d44d008 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline]
 #0: ffffffff8d44d008 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3443
 #1: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #1: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 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+0xe1b/0xe60 kernel/hung_task.c:369
 kthread+0x42e/0x520 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: 13467 Comm: kworker/u4:19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: bat_events batadv_nc_worker
RIP: 0010:arch_irqs_disabled_flags arch/x86/include/asm/irqflags.h:127 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:134 [inline]
RIP: 0010:lock_release+0x57e/0x8a0 kernel/locking/lockdep.c:5646
Code: a5 7e 83 f8 01 0f 85 83 00 00 00 4c 8b 64 24 50 43 c6 44 2c 04 00 48 c7 84 24 80 00 00 00 00 00 00 00 9c 8f 84 24 80 00 00 00 <f7> 84 24 80 00 00 00 00 02 00 00 43 c6 44 2c 04 f8 75 6f 41 f7 c7
RSP: 0018:ffffc90003d0fac0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 3c2807179fe6f01a RCX: 4fddde68a8380000
RDX: 0000000000000002 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a4540
RBP: ffffc90003d0fbd0 R08: ffffffff8d8b122f R09: 1ffffffff1b16245
R10: dffffc0000000000 R11: fffffbfff1b16246 R12: 1ffff920007a1f64
R13: dffffc0000000000 R14: ffff888029b16420 R15: 0000000000000246
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555d8499ef70 CR3: 000000001b1a0000 CR4: 00000000003506f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083
DR3: ffffffffefffff15 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rcu_read_unlock include/linux/rcupdate.h:773 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
 batadv_nc_worker+0x255/0x5c0 net/batman-adv/network-coding.c:723
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/04 04:55 linux-5.15.y 0996e0926f6b 801f0966 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in snd_seq_midisynth_remove
2026/08/26 17:40 linux-5.15.y 945fa863f02c a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in snd_seq_midisynth_remove
2026/08/06 21:54 linux-5.15.y 9c7634c60784 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in snd_seq_midisynth_remove
2026/08/03 07:26 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in snd_seq_midisynth_remove
* Struck through repros no longer work on HEAD.