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INFO: task hung in udp_tunnel_nic_device_sync_work

Status: closed as invalid on 2025/09/10 00:16
Subsystems: net
[Documentation on labels]
First crash: 225d, last: 174d
Cause bisection: failed (error log, bisect log)
  
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in udp_tunnel_nic_device_sync_work (2) net 1 syz 1 61d 61d 0/29 closed as invalid on 2026/02/18 04:33
Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/08/16 06:32 18m retest repro upstream report log

Sample crash report:
INFO: task kworker/u4:2:31 blocked for more than 143 seconds.
      Not tainted 6.16.0-syzkaller-11105-ga6923c06a3b2 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D stack:22032 pid:31    tgid:31    ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: udp_tunnel_nic udp_tunnel_nic_device_sync_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1360 kernel/locking/mutex.c:760
 udp_tunnel_nic_device_sync_work+0x29/0xa50 net/ipv4/udp_tunnel_nic.c:736
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task syz-executor:5509 blocked for more than 148 seconds.
      Not tainted 6.16.0-syzkaller-11105-ga6923c06a3b2 #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21064 pid:5509  tgid:5509  ppid:1      task_flags:0x40054c flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1360 kernel/locking/mutex.c:760
 tun_detach drivers/net/tun.c:634 [inline]
 tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3433
 __fput+0x449/0xa70 fs/file_table.c:468
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:966
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
 get_signal+0x1286/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/02 06:25 upstream a6923c06a3b2 7368264b .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root INFO: task hung in udp_tunnel_nic_device_sync_work
2025/08/26 00:15 linux-next 7fa4d8dc380f bf27483f .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in udp_tunnel_nic_device_sync_work
2025/08/22 03:30 upstream 3957a5720157 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in udp_tunnel_nic_device_sync_work
2025/08/22 03:30 upstream 3957a5720157 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in udp_tunnel_nic_device_sync_work
2025/08/26 04:51 upstream b6add54ba618 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in udp_tunnel_nic_device_sync_work
2025/08/29 13:44 net 5189446ba995 3e1beec6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in udp_tunnel_nic_device_sync_work
2025/07/10 04:34 net-next 6a971e48e2d8 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in udp_tunnel_nic_device_sync_work
* Struck through repros no longer work on HEAD.