INFO: task hung in fib_net_exit_batch (4)

Status: closed as invalid on 2026/10/06 01:52
Subsystems: net
Labels: prio:high
[Documentation on labels]
First crash: 194d, last: 87d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log)
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
2e49299f assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: task hung in fib_net_exit_batch (4) 2026/05/19 01:05 2026/05/19 01:05 2026/05/19 02:46 9f74d399
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in fib_net_exit_batch 1 6 847d 860d 0/3 auto-obsoleted due to no activity on 2024/09/25 07:15
upstream INFO: task hung in fib_net_exit_batch net 1 2 1564d 1567d 0/29 auto-closed as invalid on 2022/09/29 00:33
upstream INFO: task hung in fib_net_exit_batch (2) net 1 19 593d 870d 0/29 auto-obsoleted due to no activity on 2025/05/27 12:53
upstream INFO: task hung in fib_net_exit_batch (3) net 1 1 305d 305d 0/29 auto-obsoleted due to no activity on 2026/03/10 22:11
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/05/07 08:01 42m retest repro upstream report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/09/02 05:50 0m bisect fix upstream error
2026/07/17 10:15 2h57m bisect fix upstream OK (0) job log log
2026/06/13 14:42 4h50m bisect fix upstream OK (0) job log log

Sample crash report:
INFO: task kworker/u8:0:12 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0    state:D stack:23792 pid:12    tgid:12    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7183
 __schedule_loop kernel/sched/core.c:7262 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7277
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7334
 __mutex_lock_common kernel/locking/mutex.c:712 [inline]
 __mutex_lock+0xced/0x1b10 kernel/locking/mutex.c:806
 fib_net_exit_batch+0x15/0x130 net/ipv4/fib_frontend.c:1676

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/16 12:06 upstream aec2f682d47c df15c5f3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in fib_net_exit_batch
2026/06/16 21:15 net fbc6a80cb5d3 0e4b3e40 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in fib_net_exit_batch
2026/05/14 14:07 net-next 1f8fd0fe5641 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in fib_net_exit_batch
2026/04/23 01:20 net-next 1f5ffc672165 b10da5ec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in fib_net_exit_batch
2026/04/02 10:36 net-next f1359c240191 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in fib_net_exit_batch
2026/03/31 20:28 linux-next 36ece9697e89 aeea1c72 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in fib_net_exit_batch
* Struck through repros no longer work on HEAD.