syzbot


INFO: task hung in netlink_dump (2)

Status: upstream: reported on 2026/04/18 17:22
Reported-by: syzbot+cd848ab7597dc0b26315@syzkaller.appspotmail.com
First crash: 4d15h, last: 4d14h
Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in netlink_dump (5) net 1 123 577d 636d 0/29 auto-obsoleted due to no activity on 2024/12/01 23:22
upstream INFO: task hung in netlink_dump (2) net 1 2 1517d 1517d 0/29 auto-closed as invalid on 2022/05/26 21:32
upstream INFO: task hung in netlink_dump (7) net 1 1 199d 199d 0/29 auto-obsoleted due to no activity on 2026/01/04 01:58
upstream INFO: task hung in netlink_dump net 1 1 1687d 1687d 0/29 auto-closed as invalid on 2021/12/07 11:04
linux-6.1 INFO: task hung in netlink_dump 1 3 783d 801d 0/3 auto-obsoleted due to no activity on 2024/06/09 02:46
upstream INFO: task hung in netlink_dump (3) net 1 78 800d 958d 0/29 closed as invalid on 2024/02/12 15:10
linux-5.15 INFO: task hung in netlink_dump 1 3 675d 680d 0/3 auto-obsoleted due to no activity on 2024/09/25 04:53
linux-6.1 INFO: task hung in netlink_dump (3) 1 1 511d 511d 0/3 auto-obsoleted due to no activity on 2025/03/08 04:08
linux-6.1 INFO: task hung in netlink_dump (4) 1 2 344d 382d 0/3 auto-obsoleted due to no activity on 2025/08/22 04:23
linux-6.1 INFO: task hung in netlink_dump (2) 1 1 679d 679d 0/3 auto-obsoleted due to no activity on 2024/09/21 04:37
upstream INFO: task hung in netlink_dump (6) net 1 1 458d 458d 0/29 auto-obsoleted due to no activity on 2025/04/20 06:11
linux-6.6 INFO: task hung in netlink_dump 1 1 118d 118d 0/2 auto-obsoleted due to no activity on 2026/04/05 05:43
upstream INFO: task hung in netlink_dump (4) net 1 72 745d 785d 25/29 fixed on 2024/04/12 18:02

Sample crash report:
INFO: task dhcpcd:5434 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:20968 pid:5434  ppid:5433   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 netlink_dump+0x78f/0xe50 net/netlink/af_netlink.c:2263
 __netlink_dump_start+0x5f1/0x810 net/netlink/af_netlink.c:2372
 netlink_dump_start include/linux/netlink.h:338 [inline]
 rtnetlink_rcv_msg+0xe1d/0xfa0 net/core/rtnetlink.c:6431
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2200
 __do_sys_sendto net/socket.c:2212 [inline]
 __se_sys_sendto net/socket.c:2208 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2208
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb29e414407
RSP: 002b:00007ffdd8f367c0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fb29e38a740 RCX: 00007fb29e414407
RDX: 0000000000000014 RSI: 00007ffdd8f36850 RDI: 0000000000000012
RBP: 00007ffdd8f36834 R08: 00007ffdd8f36834 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffdd8f57140
R13: 00007fb29e38a6c8 R14: 00007ffdd8f36930 R15: 00007ffdd8f46f10
 </TASK>
INFO: task kworker/u4:14:12541 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:14   state:D stack:21736 pid:12541 ppid:2      flags:0x00004000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 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+0xa5d/0x15d0 kernel/workqueue.c:2730
 worker_thread+0xa55/0xfc0 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:13881 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:21168 pid:13881 ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 nsim_destroy+0x3f/0x180 drivers/net/netdevsim/netdev.c:417
 __nsim_dev_port_del+0x14d/0x1b0 drivers/net/netdevsim/dev.c:1428
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline]
 nsim_dev_reload_destroy+0x283/0x480 drivers/net/netdevsim/dev.c:1662
 nsim_drv_remove+0x58/0x170 drivers/net/netdevsim/dev.c:1677
 device_remove drivers/base/dd.c:567 [inline]
 __device_release_driver drivers/base/dd.c:1272 [inline]
 device_release_driver_internal+0x468/0x7a0 drivers/base/dd.c:1295
 bus_remove_device+0x342/0x400 drivers/base/bus.c:576
 device_del+0x522/0x910 drivers/base/core.c:3872
 device_unregister+0x20/0xc0 drivers/base/core.c:3913
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:310 [inline]
 del_device_store+0x2b1/0x370 drivers/net/netdevsim/bus.c:219
 kernfs_fop_write_iter+0x3b6/0x520 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+0x46c/0x990 fs/read_write.c:584
 ksys_write+0x150/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3f8635d04e
RSP: 002b:00007ffc58ef9998 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055558158d500 RCX: 00007f3f8635d04e
RDX: 0000000000000001 RSI: 00007ffc58ef9a20 RDI: 0000000000000005
RBP: 00007f3f86433514 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc58ef9a20 R14: 00007f3f87144620 R15: 0000000000000003
 </TASK>
INFO: task syz.2.2543:13997 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.2543      state:D stack:27016 pid:13997 ppid:13326  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 tun_detach drivers/net/tun.c:698 [inline]
 tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3511
 __fput+0x234/0x970 fs/file_table.c:384
 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+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f399bd9c819
RSP: 002b:00007fff30319668 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fff30319750 RCX: 00007f399bd9c819
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000000c0e5a R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b33420000 R11: 0000000000000246 R12: 00007fff30319790
R13: 00007f399c015fac R14: 00000000000c0fc5 R15: 00007f399c015fa0
 </TASK>
INFO: task syz.0.2545:14005 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2545      state:D stack:24936 pid:14005 ppid:13590  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 __tun_chr_ioctl+0x400/0x2000 drivers/net/tun.c:3121
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f638ad9c819
RSP: 002b:00007f638bc23028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f638b015fa0 RCX: 00007f638ad9c819
RDX: 0000200000000140 RSI: 00000000400454ca RDI: 0000000000000008
RBP: 00007f638ae32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f638b016038 R14: 00007f638b015fa0 R15: 00007ffe46a59ab8
 </TASK>
INFO: task syz.0.2545:14006 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2545      state:D stack:25896 pid:14006 ppid:13590  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 netlink_dump+0x78f/0xe50 net/netlink/af_netlink.c:2263
 __netlink_dump_start+0x5f1/0x810 net/netlink/af_netlink.c:2372
 netlink_dump_start include/linux/netlink.h:338 [inline]
 rtnetlink_rcv_msg+0xe1d/0xfa0 net/core/rtnetlink.c:6431
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmsg net/socket.c:2677 [inline]
 __do_sys_sendmsg net/socket.c:2686 [inline]
 __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f638ad9c819
RSP: 002b:00007f638bc02028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f638b016090 RCX: 00007f638ad9c819
RDX: 0000000000048084 RSI: 0000200000000380 RDI: 0000000000000009
RBP: 00007f638ae32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f638b016128 R14: 00007f638b016090 R15: 00007ffe46a59ab8
 </TASK>
INFO: task syz.1.2551:14027 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.2551      state:D stack:26120 pid:14027 ppid:13083  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmsg net/socket.c:2677 [inline]
 __do_sys_sendmsg net/socket.c:2686 [inline]
 __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5ce839c819
RSP: 002b:00007f5ce92f3028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f5ce8616090 RCX: 00007f5ce839c819
RDX: 0000000000000000 RSI: 0000200000000080 RDI: 0000000000000009
RBP: 00007f5ce8432c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5ce8616128 R14: 00007f5ce8616090 R15: 00007ffc6c973d78
 </TASK>
INFO: task syz-executor:14030 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25320 pid:14030 ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2200
 __do_sys_sendto net/socket.c:2212 [inline]
 __se_sys_sendto net/socket.c:2208 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2208
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f489955d04e
RSP: 002b:00007ffc5de936b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055557d3e5500 RCX: 00007f489955d04e
RDX: 0000000000000028 RSI: 00007f489a344670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffc5de93734 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f489a344670 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:14034 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25320 pid:14034 ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2200
 __do_sys_sendto net/socket.c:2212 [inline]
 __se_sys_sendto net/socket.c:2208 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2208
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f771db5d04e
RSP: 002b:00007ffe7d6cbb68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055556f808500 RCX: 00007f771db5d04e
RDX: 0000000000000028 RSI: 00007f771e944670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffe7d6cbbe4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f771e944670 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:14037 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25320 pid:14037 ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x6a9/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2200
 __do_sys_sendto net/socket.c:2212 [inline]
 __se_sys_sendto net/socket.c:2208 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2208
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1cdd15d04e
RSP: 002b:00007ffce01cee38 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055558f2c3500 RCX: 00007f1cdd15d04e
RDX: 0000000000000028 RSI: 00007f1cddf44670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffce01ceeb4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f1cddf44670 R15: 0000000000000000
 </TASK>
Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
1 lock held by klogd/5128:
 #0: ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
2 locks held by dhcpcd/5434:
 #0: ffff88804d458690 (nlk_cb_mutex-ROUTE){+.+.}-{3:3}, at: __netlink_dump_start+0xf4/0x810 net/netlink/af_netlink.c:2336
 #1: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: netlink_dump+0x78f/0xe50 net/netlink/af_netlink.c:2263
2 locks held by getty/5532:
 #0: ffff88802d6ab0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x433/0x1390 drivers/tty/n_tty.c:2217
3 locks held by kworker/0:6/5879:
 #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+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90004c57d00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90004c57d00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: reg_check_chans_work+0x92/0xd90 net/wireless/reg.c:2463
3 locks held by kworker/u4:14/12541:
 #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+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90004bbfd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90004bbfd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
3 locks held by kworker/u4:15/12542:
 #0: ffff88802c942538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff88802c942538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90004bcfd00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90004bcfd00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4718
4 locks held by kworker/u4:16/12543:
 #0: ffff88801a254938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff88801a254938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90004bdfd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90004bdfd00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3b57d0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x14c/0xbb0 net/core/net_namespace.c:606
 #3: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xf2/0xa80 net/core/dev.c:11644
5 locks held by kworker/u4:17/12544:
 #0: ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: __schedule+0x2176/0x45a0 kernel/sched/core.c:6695
 #2: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #2: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #2: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 #2: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: batadv_nc_worker+0xd2/0x610 net/batman-adv/network-coding.c:719
 #3: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: psi_enqueue kernel/sched/stats.h:143 [inline]
 #3: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: enqueue_task+0x26d/0x2b0 kernel/sched/core.c:2098
 #4: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: psi_enqueue kernel/sched/stats.h:143 [inline]
 #4: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: enqueue_task+0x26d/0x2b0 kernel/sched/core.c:2098
7 locks held by syz-executor/13881:
 #0: ffff888021090418 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x21b/0x990 fs/read_write.c:580
 #1: ffff88805ca2cc88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x520 fs/kernfs/file.c:343
 #2: ffff888024bdfe90 (kn->active#53){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff888024bdfe90 (kn->active#53){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x23a/0x520 fs/kernfs/file.c:344
 #3: ffffffff8dca2848 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: del_device_store+0xd8/0x370 drivers/net/netdevsim/bus.c:209
 #4: ffff8880196b40e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline]
 #4: ffff8880196b40e8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
 #4: ffff8880196b40e8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb6/0x7a0 drivers/base/dd.c:1292
 #5: ffff8880196b5250 (&devlink->lock_key#2){+.+.}-{3:3}, at: nsim_drv_remove+0x50/0x170 drivers/net/netdevsim/dev.c:1676
 #6: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3f/0x180 drivers/net/netdevsim/netdev.c:417
1 lock held by syz.2.2543/13997:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3511
1 lock held by syz.0.2545/14005:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x400/0x2000 drivers/net/tun.c:3121
2 locks held by syz.0.2545/14006:
 #0: ffff88806990f690 (nlk_cb_mutex-ROUTE){+.+.}-{3:3}, at: __netlink_dump_start+0xf4/0x810 net/netlink/af_netlink.c:2336
 #1: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: netlink_dump+0x78f/0xe50 net/netlink/af_netlink.c:2263
1 lock held by syz.1.2551/14027:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14030:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14034:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14037:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14040:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14045:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14049:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14052:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14058:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14063:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14068:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14072:
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6472

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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+0xf3d/0xf80 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:arch_irqs_disabled_flags arch/x86/include/asm/irqflags.h:126 [inline]
RIP: 0010:lockdep_hardirqs_off+0x4c/0x100 kernel/locking/lockdep.c:4451
Code: 90 00 00 00 48 89 fb 65 8b 05 38 69 7d 75 a9 00 00 f0 00 74 68 83 3d e2 77 a6 0c 00 75 15 48 c7 04 24 00 00 00 00 9c 8f 04 24 <f7> 04 24 00 02 00 00 75 79 65 8b 05 fc 39 7c 75 85 c0 74 56 65 4c
RSP: 0018:ffffffff8ce07cc8 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffffff817ab178 RCX: 69b24efd387c5100
RDX: 0000000000000000 RSI: ffffffff8acaca00 RDI: ffffffff8b1c8e60
RBP: ffffffff8ce07d90 R08: ffff8880b8e3c087 R09: 1ffff110171c7810
R10: dffffc0000000000 R11: ffffed10171c7811 R12: 1ffffffff19c0fa0
R13: dffffc0000000000 R14: ffffffff8ce9346c R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49b981c589 CR3: 000000000cf32000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 trace_hardirqs_off+0x12/0x40 kernel/trace/trace_preemptirq.c:87
 tick_nohz_idle_enter+0x118/0x260 kernel/time/tick-sched.c:1165
 do_idle+0x9a/0x590 kernel/sched/idle.c:276
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401
 rest_init+0x2e2/0x300 init/main.c:744
 arch_call_rest_init+0xe/0x10 init/main.c:841
 start_kernel+0x459/0x4e0 init/main.c:1086
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/18 18:59 linux-6.6.y 9760bf04666d 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in netlink_dump
2026/04/18 17:21 linux-6.6.y 9760bf04666d 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in netlink_dump
* Struck through repros no longer work on HEAD.