INFO: task kworker/u8:2:43 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:20520 pid:43    tgid:43    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 afs_cell_purge+0x3d9/0x540 fs/afs/cell.c:894
 afs_net_exit+0x50/0x100 fs/afs/main.c:147
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49a/0x990 net/core/net_namespace.c:252
 cleanup_net+0x4de/0x820 net/core/net_namespace.c:695
 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>

Showing all locks held in the system:
4 locks held by ksoftirqd/1/30:
1 lock held by khungtaskd/38:
 #0: ffffffff8d5aa840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8d5aa840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8d5aa840 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:2/43:
 #0: ffff888019ad4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff888019ad4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffffc90000b47ba0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
 #1: ffffc90000b47ba0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
 #2: ffffffff8e856420 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x820 net/core/net_namespace.c:669
2 locks held by getty/5557:
 #0: ffff88823bf400a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e7e2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1400 drivers/tty/n_tty.c:2222
3 locks held by kworker/1:3/5859:
 #0: ffff88813ff55138 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff88813ff55138 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffffc90004867ba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
 #1: ffffc90004867ba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
 #2: ffff88803c150260 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x224/0x3e0 drivers/net/netdevsim/fib.c:1490
3 locks held by udevd/7062:
 #0: ffff888035194480 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
 #1: ffff8880353f5d78 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1025 [inline]
 #1: ffff8880353f5d78 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3360 [inline]
 #1: ffff8880353f5d78 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: do_renameat2+0x3b9/0xa50 fs/namei.c:5311
 #2: ffff8880b8934400 ((lock)#4){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline]
 #2: ffff8880b8934400 ((lock)#4){+.+.}-{3:3}, at: mlock_drain_local+0x13f/0x4b0 mm/mlock.c:216
1 lock held by udevd/7379:
10 locks held by syz-executor/8066:
2 locks held by kworker/u8:15/8765:
 #0: ffff88813ff69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff88813ff69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffffc900069e7ba0 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
 #1: ffffc900069e7ba0 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
1 lock held by syz.6.410/9128:
 #0: ffff8880362d0dd0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:330 [inline]
 #0: ffff8880362d0dd0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x214/0x4d0 mm/util.c:579
5 locks held by syz.6.410/9129:
2 locks held by syz.9.413/9148:
2 locks held by modprobe/9165:

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
 watchdog+0xf60/0xfa0 kernel/hung_task.c:495
 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>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 9164 Comm: syz.5.416 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0033:0x7fa9351f09d0
Code: 49 8b 47 10 48 39 f0 72 6e 48 63 cd 48 01 c1 49 39 4f 08 72 4c 8d 4d ff 85 ed 74 33 66 0f 1f 44 00 00 48 39 f0 72 1b 4d 8b 07 <49> 89 c1 49 29 f1 47 0f b6 0c 08 45 84 c9 74 08 45 88 0c 00 49 8b
RSP: 002b:00007fa9335954a0 EFLAGS: 00000202
RAX: 000000000039ed92 RBX: 00007fa933595540 RCX: 00000000000000bd
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00007fa9335955e0
RBP: 0000000000000102 R08: 00007fa92b176000 R09: 0000000000000000
R10: 0000000000000000 R11: 00007fa933595550 R12: 0000000000000001
R13: 00007fa9353cdc40 R14: 0000000000000000 R15: 00007fa9335955e0
FS:  00007fa9335966c0 GS:  0000000000000000