INFO: task hung in fqdir_free_fn (3)

Status: upstream: reported on 2026/10/05 05:19
Reported-by: syzbot+2ef26a0cee23b28dabae@syzkaller.appspotmail.com
First crash: 5d09h, last: 5d09h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 INFO: task hung in fqdir_free_fn 1 32 339d 476d 0/1 auto-obsoleted due to no activity on 2026/01/05 06:30
linux-5.15 INFO: task hung in fqdir_free_fn 1 1 807d 807d 0/3 auto-obsoleted due to no activity on 2024/11/01 18:36
android-6-12 INFO: task hung in fqdir_free_fn (2) 1 24 22d 245d 0/1 premoderation: reported on 2026/02/07 13:12
upstream INFO: task hung in fqdir_free_fn net 1 4 702d 811d 0/29 auto-obsoleted due to no activity on 2025/02/05 05:14
linux-5.15 INFO: task hung in fqdir_free_fn (2) 1 1 273d 273d 0/3 auto-obsoleted due to no activity on 2026/04/19 19:10

Sample crash report:
INFO: task kworker/1:16:5642 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:16    state:D stack:25328 pid: 5642 ppid:     2 flags:0x00004000
Workqueue: events fqdir_free_fn
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_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 do_wait_for_common+0x295/0x460 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 rcu_barrier+0x406/0x4c0 kernel/rcu/tree.c:4108
 fqdir_free_fn+0x2f/0x130 net/ipv4/inet_fragment.c:166
 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.2.1729:11570 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1729      state:D stack:25776 pid:11570 ppid:  4248 flags:0x00004002
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
 perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239
 _free_event+0x84f/0xe30 kernel/events/core.c:5174
 put_event kernel/events/core.c:5268 [inline]
 perf_event_release_kernel+0x7c4/0x850 kernel/events/core.c:5393
 perf_release+0x37/0x40 kernel/events/core.c:5403
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x635/0x2110 kernel/exit.c:890
 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004
 get_signal+0x7eb/0x12e0 kernel/signal.c:2913
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:157 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:280
RIP: 0033:0x7f38547fef49
RSP: 002b:00007f38525f11c0 EFLAGS: 00000202 ORIG_RAX: 00000000000001b3
RAX: 0000000000000000 RBX: 00007f38547ba4e0 RCX: 00007f38547fef49
RDX: 00007f38547ba4e0 RSI: 0000000000000058 RDI: 00007ffcec3c14a0
RBP: 00007f38525f16c0 R08: 00007f38525f16c0 R09: 00007ffcec3c1587
R10: 0000000000000008 R11: 0000000000000202 R12: ffffffffffffffe8
R13: 000000000000006e R14: 00007ffcec3c14a0 R15: 00007ffcec3c1588
 </TASK>
INFO: task syz.1.1733:11568 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1733      state:D stack:26608 pid:11568 ppid:  4240 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
 perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239
 _free_event+0x84f/0xe30 kernel/events/core.c:5174
 put_event kernel/events/core.c:5268 [inline]
 perf_event_release_kernel+0x7c4/0x850 kernel/events/core.c:5393
 perf_release+0x37/0x40 kernel/events/core.c:5403
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:184
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb76d887159
RSP: 002b:00007ffee7229758 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fb76db10da0 RCX: 00007fb76d887159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fb76db10da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007fb76db10cb0 R11: 0000000000000246 R12: 00000000000ad028
R13: 00007fb76db0f27c R14: 00000000000acf47 R15: 00007fb76db0f270
 </TASK>
INFO: task syz.0.1734:11585 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1734      state:D stack:29040 pid:11585 ppid:  4247 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
 perf_trace_init+0x4c/0x2d0 kernel/trace/trace_event_perf.c:221
 perf_tp_event_init+0x89/0x110 kernel/events/core.c:10112
 perf_try_init_event+0x12b/0x3d0 kernel/events/core.c:11611
 perf_init_event kernel/events/core.c:11675 [inline]
 perf_event_alloc+0xf78/0x21d0 kernel/events/core.c:11967
 __do_sys_perf_event_open kernel/events/core.c:12505 [inline]
 __se_sys_perf_event_open+0x6f5/0x1bb0 kernel/events/core.c:12397
 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: 0033:0x7fea7c468159
RSP: 002b:00007fea7a6c0028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007fea7c6effa0 RCX: 00007fea7c468159
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000140
RBP: 00007fea7c4ff06b R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fea7c6f0038 R14: 00007fea7c6effa0 R15: 00007fff86eb63b8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31efa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:1/144:
 #0: ffff888016dcd938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900016efd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d4418d0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:589
 #3: ffffffff8c323a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #3: ffffffff8c323a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
1 lock held by dhcpcd/3852:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
2 locks held by getty/3946:
 #0: ffff88802c553098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
3 locks held by syz-executor/4248:
 #0: ffff88807e4913f0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1020 net/bluetooth/hci_core.c:1755
 #1: ffff88807e490478 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x408/0x1020 net/bluetooth/hci_core.c:1800
 #2: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1519 [inline]
 #2: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622
4 locks held by kworker/u5:3/4250:
 #0: ffff88802249a938 ((wq_completion)hci19#2){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90002f5fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888065cb4478 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0xbb/0xa10 net/bluetooth/hci_event.c:3334
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline]
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367
4 locks held by kworker/u5:4/4252:
 #0: ffff88807eab4938 ((wq_completion)hci18#2){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90002f7fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888065cb0478 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0xbb/0xa10 net/bluetooth/hci_event.c:3334
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline]
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367
4 locks held by kworker/u5:5/4254:
 #0: ffff888076794138 ((wq_completion)hci15#2){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90002f9fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888065c9c478 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0xbb/0xa10 net/bluetooth/hci_event.c:3334
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline]
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367
4 locks held by kworker/u5:6/4255:
 #0: ffff888076d2c938 ((wq_completion)hci17#2){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90002fafd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888065cac478 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0xbb/0xa10 net/bluetooth/hci_event.c:3334
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline]
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367
2 locks held by kworker/1:6/4304:
 #0: ffff888016c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900031afd00 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
3 locks held by kworker/1:16/5642:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90003aafd00 (fqdir_free_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8c323930 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0xa1/0x4c0 kernel/rcu/tree.c:4043
3 locks held by kworker/1:33/7169:
 #0: ffff888016c71938 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000336fd00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: reg_check_chans_work+0x82/0xa90 net/wireless/reg.c:2437
3 locks held by kworker/1:35/7173:
 #0: ffff88802b616538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000344fd00 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4672
2 locks held by kworker/0:37/7296:
4 locks held by kworker/u4:7/9048:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90003bcfd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
 #3: ffffffff8c323a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #3: ffffffff8c323a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
7 locks held by kworker/0:40/9837:
1 lock held by syz.2.1729/11570:
 #0: ffffffff8c36c808 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239
1 lock held by syz.7.1731/11559:
 #0: ffffffff8c36c808 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239
1 lock held by syz.1.1733/11568:
 #0: ffffffff8c36c808 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239
2 locks held by syz.0.1734/11585:
 #0: ffffffff9636b918 (&pmus_srcu){....}-{0:0}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #1: ffffffff8c36c808 (event_mutex){+.+.}-{3:3}, at: perf_trace_init+0x4c/0x2d0 kernel/trace/trace_event_perf.c:221
1 lock held by syz-executor/11678:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11700:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11704:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11708:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11714:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11717:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11723:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11725:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11726:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11730:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11733:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11739:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11740:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/11742:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
4 locks held by kworker/u5:0/11743:
 #0: ffff888076d2f138 ((wq_completion)hci16#2){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90002f0fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888065ca8478 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0xbb/0xa10 net/bluetooth/hci_event.c:3334
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline]
 #3: ffffffff8d594a88 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367
1 lock held by syz-executor/11748:
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695

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

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: 9837 Comm: kworker/0:40 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: wg-crypt-wg0 wg_packet_tx_worker
RIP: 0010:local_add_negative arch/x86/include/asm/local.h:96 [inline]
RIP: 0010:perf_swevent_event+0x325/0x540 kernel/events/core.c:9636
Code: e8 e0 71 e0 ff eb 16 e8 d9 71 e0 ff eb 0f e8 d2 71 e0 ff e9 15 02 00 00 e8 c8 71 e0 ff 48 8b 04 24 31 f6 4c 01 a0 f8 01 00 00 <0f> 99 c3 40 0f 98 c6 bf 02 00 00 00 e8 0a 74 e0 ff 84 db 75 0a e8
RSP: 0018:ffffc9000304f228 EFLAGS: 00000057
RAX: ffff8880759429c8 RBX: 0000000000000008 RCX: ffff888021793b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc9000304f300 R08: ffffffff8d8b2bef R09: 1ffffffff1b1657d
R10: dffffc0000000000 R11: fffffbfff1b1657e R12: 0000000000000001
R13: ffff8880b9035120 R14: 1ffff1100eb28577 R15: 0000000000000008
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002980 CR3: 000000005a9fc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10057
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 82 fc 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc9000304f720 EFLAGS: 00000206
RAX: 0596775aca39a500 RBX: 1ffff92000609ee8 RCX: 0596775aca39a500
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4b80
RBP: ffffc9000304f800 R08: ffffffff902141bf R09: 1ffffffff2042837
R10: dffffc0000000000 R11: fffffbfff2042838 R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 nf_hook include/linux/netfilter.h:259 [inline]
 __ip6_local_out+0x806/0x850 net/ipv6/output_core.c:149
 ip6_local_out+0x26/0x120 net/ipv6/output_core.c:159
 ip6tunnel_xmit include/net/ip6_tunnel.h:160 [inline]
 udp_tunnel6_xmit_skb+0x4b7/0x8b0 net/ipv6/ip6_udp_tunnel.c:110
 send6+0x5a0/0x8d0 drivers/net/wireguard/socket.c:152
 wg_socket_send_skb_to_peer+0x10d/0x1c0 drivers/net/wireguard/socket.c:178
 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
 wg_packet_tx_worker+0x1d3/0x7b0 drivers/net/wireguard/send.c:276
 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 (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/05 05:18 linux-5.15.y a051a4bf909f 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: task hung in fqdir_free_fn
* Struck through repros no longer work on HEAD.