netdev - Re: [syzbot] [wireguard?] INFO: task hung in wg_netns_pre

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Message-ID: <68f595d8.050a0220.91a22.043c.GAE@google.com>
Date: Sun, 19 Oct 2025 18:52:25 -0700
From: syzbot <syzbot+f2fbf7478a35a94c8b7c@...kaller.appspotmail.com>
To: Jason@...c4.com, andrew+netdev@...n.ch, davem@...emloft.net, 
	edumazet@...gle.com, jason@...c4.com, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	syzkaller-bugs@...glegroups.com, wireguard@...ts.zx2c4.com
Subject: Re: [syzbot] [wireguard?] INFO: task hung in wg_netns_pre_exit (5)

syzbot has found a reproducer for the following issue on:

HEAD commit:    88224095b4e5 Merge branch 'net-dsa-lantiq_gswip-clean-up-a..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17b28de2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=913caf94397d1b8d
dashboard link: https://syzkaller.appspot.com/bug?extid=f2fbf7478a35a94c8b7c
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10796b04580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f3cb46a2b9fc/disk-88224095.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d43ffbc738d/vmlinux-88224095.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9817e4fdd10a/bzImage-88224095.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f2fbf7478a35a94c8b7c@...kaller.appspotmail.com

INFO: task kworker/u8:8:6081 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:8    state:D stack:23424 pid:6081  tgid:6081  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 wg_netns_pre_exit+0x1c/0x1d0 drivers/net/wireguard/device.c:419
 ops_pre_exit_list net/core/net_namespace.c:161 [inline]
 ops_undo_list+0x187/0x990 net/core/net_namespace.c:234
 cleanup_net+0x4d8/0x820 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task syz-executor:6161 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25608 pid:6161  tgid:6161  ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.