syzbot

INFO: task kworker/u4:17:30030 blocked for more than 143 seconds.
      Not tainted 6.2.0-syzkaller-13563-gf915322fe014 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:17   state:D
 stack:26488 pid:30030 ppid:2      flags:0x00004000
Workqueue: netns cleanup_net

Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5304 [inline]
 __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
 schedule+0xc3/0x180 kernel/sched/core.c:6698
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6757
 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
 ppp_exit_net+0xe4/0x3b0 drivers/net/ppp/ppp_generic.c:1129
 ops_exit_list net/core/net_namespace.c:169 [inline]
 cleanup_net+0x6d2/0xb80 net/core/net_namespace.c:613
 process_one_work+0x915/0x13a0 kernel/workqueue.c:2390
 worker_thread+0xa63/0x1210 kernel/workqueue.c:2537
 kthread+0x270/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: 
ffffffff8d1279f0
 (
rcu_tasks.tasks_gp_mutex
){+.+.}-{3:3}
, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510