syzbot


INFO: task hung in rtnetlink_rcv_msg (2)

Status: upstream: reported on 2026/05/16 14:21
Reported-by: syzbot+40666be185ef012c4b9a@syzkaller.appspotmail.com
First crash: 54d, last: 2d13h
Similar bugs (18)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in rtnetlink_rcv_msg 1 1 1091d 1091d 0/3 auto-obsoleted due to no activity on 2023/10/22 21:13
linux-4.19 INFO: task hung in rtnetlink_rcv_msg (2) 1 14 1634d 1813d 0/1 auto-closed as invalid on 2022/05/18 11:30
linux-4.19 INFO: task hung in rtnetlink_rcv_msg (3) 1 8 1246d 1480d 0/1 upstream: reported on 2022/06/20 23:55
linux-4.19 INFO: task hung in rtnetlink_rcv_msg 1 11 2065d 2387d 0/1 auto-closed as invalid on 2021/03/12 19:03
upstream INFO: task hung in rtnetlink_rcv_msg (2) net 1 C inconclusive 548 473d 681d 0/29 closed as invalid on 2025/04/18 16:40
linux-5.15 INFO: task hung in rtnetlink_rcv_msg (4) origin:upstream 1 syz 4 25d 96d 0/3 upstream: reported syz repro on 2026/04/05 04:20
linux-6.1 INFO: task hung in rtnetlink_rcv_msg (3) origin:upstream 1 C error 21 96d 658d 0/3 upstream: reported C repro on 2024/09/19 14:16
linux-5.15 INFO: task hung in rtnetlink_rcv_msg (3) 1 1 449d 449d 0/3 auto-obsoleted due to no activity on 2025/07/26 04:34
upstream INFO: task hung in rtnetlink_rcv_msg net 1 C inconclusive inconclusive 1970 731d 2694d 26/29 fixed on 2024/07/09 19:14
linux-4.14 INFO: task hung in rtnetlink_rcv_msg 1 1 1226d 1226d 0/1 upstream: reported on 2023/03/01 21:15
linux-5.15 INFO: task hung in rtnetlink_rcv_msg (2) 1 70 601d 893d 0/3 auto-obsoleted due to no activity on 2025/01/24 13:11
android-6-12 INFO: task hung in rtnetlink_rcv_msg (2) 1 191 2h48m 169d 0/1 premoderation: reported on 2026/01/21 16:59
linux-6.1 INFO: task hung in rtnetlink_rcv_msg (2) 1 67 731d 895d 0/3 auto-obsoleted due to no activity on 2024/09/17 07:45
linux-6.1 INFO: task hung in rtnetlink_rcv_msg 1 1 1016d 1016d 0/3 auto-obsoleted due to no activity on 2024/01/09 18:18
android-6-12 INFO: task hung in rtnetlink_rcv_msg 1 265 238d 384d 0/1 auto-obsoleted due to no activity on 2026/01/02 16:22
linux-6.6 INFO: task hung in rtnetlink_rcv_msg 1 3 157d 249d 0/2 auto-obsoleted due to no activity on 2026/05/14 04:07
upstream INFO: task hung in rtnetlink_rcv_msg (3) net 1 4 399d 440d 0/29 auto-obsoleted due to no activity on 2025/09/03 19:16
upstream INFO: task hung in cangw_pernet_exit (3) can 1 syz unreliable 290 1655d 1761d 0/29 closed as invalid on 2022/02/08 10:22

Sample crash report:
INFO: task dhcpcd:5436 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:dhcpcd          state:D stack:21032 pid:5436  ppid:5435   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f779fa60407
RSP: 002b:00007ffd73ead5a0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f779f9d6740 RCX: 00007f779fa60407
RDX: 0000000000000000 RSI: 00007ffd73ec1780 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd73ed19b0
R13: 00007f779f9d66c8 R14: 0000000000000030 R15: 00007ffd73ec1780
 </TASK>
INFO: task kworker/u4:19:5971 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:19   state:D stack:22096 pid:5971  ppid:2      flags:0x00004000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 linkwatch_event+0xe/0x60 net/core/link_watch.c:286
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task syz-executor:12807 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22344 pid:12807 ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 register_nexthop_notifier+0x88/0x240 net/ipv4/nexthop.c:3636
 nsim_fib_create+0x94f/0xb20 drivers/net/netdevsim/fib.c:1589
 nsim_drv_probe+0x798/0xb90 drivers/net/netdevsim/dev.c:1586
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x247/0xae0 drivers/base/dd.c:718
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:880
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:910
 __device_attach_driver+0x2ca/0x510 drivers/base/dd.c:1038
 bus_for_each_drv+0x252/0x2e0 drivers/base/bus.c:459
 __device_attach+0x2c1/0x420 drivers/base/dd.c:1110
 bus_probe_device+0x180/0x260 drivers/base/bus.c:580
 device_add+0x87c/0xc40 drivers/base/core.c:3700
 nsim_bus_dev_new drivers/net/netdevsim/bus.c:290 [inline]
 new_device_store+0x37c/0x690 drivers/net/netdevsim/bus.c:167
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3703d5e68e
RSP: 002b:00007ffd7f1559c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000555562fba500 RCX: 00007f3703d5e68e
RDX: 0000000000000003 RSI: 00007ffd7f155a50 RDI: 0000000000000005
RBP: 00007f3703e34716 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007ffd7f155a50 R14: 00007f3704b54620 R15: 0000000000000003
 </TASK>
INFO: task syz.3.2397:12880 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.2397      state:D stack:27048 pid:12880 ppid:5775   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 tun_detach drivers/net/tun.c:698 [inline]
 tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3514
 __fput+0x221/0x940 fs/file_table.c:418
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbf6bd9de59
RSP: 002b:00007ffc37ae8b08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fbf6c027da0 RCX: 00007fbf6bd9de59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fbf6c027da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007fbf6c027cb0 R11: 0000000000000246 R12: 000000000007b6f9
R13: 00007fbf6c02609c R14: 000000000007b4ba R15: 00007fbf6c026090
 </TASK>
INFO: task syz.1.2399:12886 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.2399      state:D stack:23784 pid:12886 ppid:12547  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9dc399de59
RSP: 002b:00007f9dc4943028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9dc3c25fa0 RCX: 00007f9dc399de59
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 000000000000000a
RBP: 00007f9dc3a33e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9dc3c26038 R14: 00007f9dc3c25fa0 R15: 00007ffea95af9f8
 </TASK>
INFO: task syz.2.2401:12891 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.2401      state:D stack:25832 pid:12891 ppid:5777   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 tcx_link_attach+0xf4/0x960 kernel/bpf/tcx.c:318
 link_create+0x390/0x720 kernel/bpf/syscall.c:5084
 __sys_bpf+0x4d7/0x890 kernel/bpf/syscall.c:5547
 __do_sys_bpf kernel/bpf/syscall.c:5581 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5579 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5579
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa7c5f9de59
RSP: 002b:00007fa7c6e2d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fa7c6225fa0 RCX: 00007fa7c5f9de59
RDX: 0000000000000020 RSI: 00002000000003c0 RDI: 000000000000001c
RBP: 00007fa7c6033e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa7c6226038 R14: 00007fa7c6225fa0 R15: 00007ffe5e9e3428
 </TASK>
INFO: task syz.2.2401:12892 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.2401      state:D stack:25832 pid:12892 ppid:5777   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 tcx_prog_detach+0xf5/0x610 kernel/bpf/tcx.c:67
 __sys_bpf+0x682/0x890 kernel/bpf/syscall.c:5489
 __do_sys_bpf kernel/bpf/syscall.c:5581 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5579 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5579
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa7c5f9de59
RSP: 002b:00007fa7c6e0c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fa7c6226090 RCX: 00007fa7c5f9de59
RDX: 0000000000000020 RSI: 0000200000000200 RDI: 0000000000000009
RBP: 00007fa7c6033e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa7c6226128 R14: 00007fa7c6226090 R15: 00007ffe5e9e3428
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
4 locks held by kworker/u4:11/3451:
 #0: ffff88801a25c938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff88801a25c938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #1: ffffc9000d367d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc9000d367d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #2: ffffffff8e3c8b10 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x14c/0xbb0 net/core/net_namespace.c:606
 #3: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xf2/0xa00 net/core/dev.c:11644
1 lock held by dhcpcd/5436:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
2 locks held by getty/5536:
 #0: ffff88802da9f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900015d72f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
3 locks held by kworker/u4:17/5968:
 #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #1: ffffc90004fcfd00 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90004fcfd00 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #2: ffffffff8cfcd110 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_disable+0x12/0x20 kernel/jump_label.c:244
3 locks held by kworker/u4:19/5971:
 #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #1: ffffc90004fffd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90004fffd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #2: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
3 locks held by kworker/0:3/10863:
 #0: ffff888017c71d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c71d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #1: ffffc90003b57d00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90003b57d00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #2: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: reg_check_chans_work+0x92/0xd90 net/wireless/reg.c:2463
3 locks held by kworker/u4:2/12456:
 #0: ffff88814c418d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff88814c418d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #1: ffffc900058c7d00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc900058c7d00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2730
 #2: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4723
7 locks held by syz-executor/12807:
 #0: ffff888030578418 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580
 #1: ffff888043809488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x520 fs/kernfs/file.c:343
 #2: ffff888141bd53e8 (kn->active#54){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff888141bd53e8 (kn->active#54){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x236/0x520 fs/kernfs/file.c:344
 #3: ffffffff8dcb6aa8 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: new_device_store+0x13d/0x690 drivers/net/netdevsim/bus.c:160
 #4: ffff88804c705130 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1094 [inline]
 #4: ffff88804c705130 (&dev->mutex){....}-{3:3}, at: __device_attach+0x89/0x420 drivers/base/dd.c:1085
 #5: ffff88804c706250 (&devlink->lock_key#6){+.+.}-{3:3}, at: nsim_drv_probe+0xc8/0xb90 drivers/net/netdevsim/dev.c:1537
 #6: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: register_nexthop_notifier+0x88/0x240 net/ipv4/nexthop.c:3636
1 lock held by syz.3.2397/12880:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3514
1 lock held by syz.1.2399/12886:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz.2.2401/12891:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: tcx_link_attach+0xf4/0x960 kernel/bpf/tcx.c:318
1 lock held by syz.2.2401/12892:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: tcx_prog_detach+0xf5/0x610 kernel/bpf/tcx.c:67
1 lock held by syz-executor/12898:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12899:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12906:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12910:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12917:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12920:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12922:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12927:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12934:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12937:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473
1 lock held by syz-executor/12939:
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d5b08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6473

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 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+0xf59/0xfa0 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 12455 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__lock_acquire+0xffb/0x7d80 kernel/locking/lockdep.c:5132
Code: 01 c1 29 d0 41 89 d6 41 c1 c6 10 41 31 c6 01 ca 44 89 f3 c1 c3 13 44 29 f1 31 cb 41 01 d6 29 da 41 89 dc 41 c1 c4 04 41 31 d4 <48> c7 c0 e0 9f 8c 8e 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85 89 0d
RSP: 0018:ffffc900052f75a0 EFLAGS: 00000006
RAX: 000000001f047545 RBX: 00000000a1c956d9 RCX: 00000000a44ec5e9
RDX: 000000006ae15d22 RSI: 00000000cf961f63 RDI: ffffffff911e7500
RBP: ffffc900052f77e8 R08: dffffc0000000000 R09: 1ffffffff223cea0
R10: dffffc0000000000 R11: fffffbfff223cea1 R12: 00000000767430b8
R13: ffff88802852da00 R14: 00000000ff10b4ab R15: 00000000ebcdb742
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a00055f000 CR3: 0000000025407000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
 debug_object_activate+0x6c/0x500 lib/debugobjects.c:747
 debug_timer_activate kernel/time/timer.c:782 [inline]
 __mod_timer+0x8d2/0xd60 kernel/time/timer.c:1119
 queue_delayed_work_on+0x131/0x200 kernel/workqueue.c:2006
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/07 23:07 linux-6.6.y da47cbc25466 76cdc0c0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in rtnetlink_rcv_msg
2026/05/16 14:20 linux-6.6.y 4d922539ad7d a15a64a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in rtnetlink_rcv_msg
* Struck through repros no longer work on HEAD.