INFO: task hung in ip6_tnl_exit_batch_net

Status: upstream: reported on 2026/08/19 09:45
Reported-by: syzbot+eea2e3e700ef8a3080aa@syzkaller.appspotmail.com
First crash: 9d18h, last: 9d18h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in ip6_tnl_exit_batch_net (3) net 1 1 1284d 1284d 0/29 auto-obsoleted due to no activity on 2023/05/22 13:26
upstream INFO: task hung in ip6_tnl_exit_batch_net net 1 3 2176d 2305d 0/29 auto-closed as invalid on 2020/12/11 16:12
upstream INFO: task hung in ip6_tnl_exit_batch_net (2) net 1 1 1521d 1521d 0/29 auto-closed as invalid on 2022/09/27 10:20

Sample crash report:
INFO: task kworker/u4:5:1003 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:5    state:D stack:22648 pid:1003  ppid:2      flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 ip6_tnl_exit_batch_net+0xcc/0x630 net/ipv6/ip6_tunnel.c:2300
 ops_exit_list net/core/net_namespace.c:178 [inline]
 cleanup_net+0x792/0xbb0 net/core/net_namespace.c:652
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/19 09:44 linux-6.6.y d27334b2888c 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in ip6_tnl_exit_batch_net
* Struck through repros no longer work on HEAD.