INFO: task kworker/u4:0:14506 blocked for more than 143 seconds.
      Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:0    D23648 14506      2 0x80004000
Workqueue: netns cleanup_net
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
 __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
 __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
 hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1267 [inline]
 hashlimit_net_exit+0x16d/0x3d0 net/netfilter/xt_hashlimit.c:1290
 ops_exit_list.isra.0+0xb1/0x160 net/core/net_namespace.c:172
 cleanup_net+0x549/0xb10 net/core/net_namespace.c:589
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Showing all locks held in the system:
1 lock held by khungtaskd/1132:
 #0: ffffffff899a3f40 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334
1 lock held by rsyslogd/9536:
 #0: ffff888095281ae0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801
2 locks held by getty/9626:
 #0: ffff8880a04f3090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc9000193b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9627:
 #0: ffff8880a5083090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900019cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9628:
 #0: ffff8880a3994090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc9000194b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9629:
 #0: ffff8880a8958090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900019bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9630:
 #0: ffff8880a871c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900019ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9631:
 #0: ffff8880a2f3d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc9000199b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9632:
 #0: ffff8880937c4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900018f72e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
4 locks held by kworker/u4:0/14506:
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline]
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline]
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: set_work_data kernel/workqueue.c:615 [inline]
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline]
 #0: ffff88821b78e528 ((wq_completion)netns){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2235
 #1: ffffc90002757dc0 (net_cleanup_work){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239
 #2: ffffffff8a4c97c8 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa1/0xb10 net/core/net_namespace.c:551
 #3: ffffffff8a555ca0 (hashlimit_mutex){+.+.}, at: hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1267 [inline]
 #3: ffffffff8a555ca0 (hashlimit_mutex){+.+.}, at: hashlimit_net_exit+0x16d/0x3d0 net/netfilter/xt_hashlimit.c:1290
3 locks held by kworker/u4:3/26634:
 #0: ffff8880ae837358 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1215 [inline]
 #0: ffff8880ae837358 (&rq->lock){-.-.}, at: __schedule+0x232/0x1f90 kernel/sched/core.c:4029
 #1: ffffc900018d7dc0 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239
 #2: ffff8880ae827258 (&base->lock){-.-.}, at: lock_timer_base+0x56/0x1b0 kernel/time/timer.c:936
1 lock held by syz-executor.3/26664:

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

NMI backtrace for cpu 1
CPU: 1 PID: 1132 Comm: khungtaskd Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xb11/0x10c0 kernel/hung_task.c:289
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 26664 Comm: syz-executor.3 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x16/0x20 kernel/kcov.c:276
Code: 48 89 e5 48 8b 4d 08 e8 d8 fe ff ff 5d c3 66 0f 1f 44 00 00 55 89 f2 89 fe bf 05 00 00 00 48 89 e5 48 8b 4d 08 e8 ba fe ff ff <5d> c3 0f 1f 84 00 00 00 00 00 55 48 89 f2 48 89 fe bf 07 00 00 00
RSP: 0018:ffffc900019f7708 EFLAGS: 00000097
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffffffff817a93e0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: ffffc900019f7708 R08: ffff88805e720080 R09: fffff5200739f20a
R10: fffff5200739f209 R11: ffffc90039cf904b R12: ffffffff86765d79
R13: ffff88805e720080 R14: ffffc90039cf9000 R15: 00000000092aab32
FS:  00007fab55e92700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000a78030 CR3: 0000000092f11000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 trace_hardirqs_off+0x50/0x240 kernel/trace/trace_preemptirq.c:41
 __local_bh_enable_ip+0x11a/0x270 kernel/softirq.c:171
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_bh+0x2c/0x30 kernel/locking/spinlock.c:207
 spin_unlock_bh include/linux/spinlock.h:383 [inline]
 htable_selective_cleanup+0x219/0x330 net/netfilter/xt_hashlimit.c:387
 htable_destroy net/netfilter/xt_hashlimit.c:422 [inline]
 htable_put+0x176/0x220 net/netfilter/xt_hashlimit.c:449
 hashlimit_mt_destroy_v2+0x56/0x70 net/netfilter/xt_hashlimit.c:971
 cleanup_match+0xde/0x170 net/ipv6/netfilter/ip6_tables.c:478
 find_check_entry.isra.0+0x4da/0x9d0 net/ipv6/netfilter/ip6_tables.c:582
 translate_table+0xd15/0x1860 net/ipv6/netfilter/ip6_tables.c:734
 do_replace net/ipv6/netfilter/ip6_tables.c:1153 [inline]
 do_ip6t_set_ctl+0x2fe/0x4c8 net/ipv6/netfilter/ip6_tables.c:1681
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x77/0xd0 net/netfilter/nf_sockopt.c:115
 ipv6_setsockopt net/ipv6/ipv6_sockglue.c:949 [inline]
 ipv6_setsockopt+0x147/0x180 net/ipv6/ipv6_sockglue.c:933
 tcp_setsockopt net/ipv4/tcp.c:3158 [inline]
 tcp_setsockopt+0x8f/0xe0 net/ipv4/tcp.c:3152
 sock_common_setsockopt+0x94/0xd0 net/core/sock.c:3149
 __sys_setsockopt+0x261/0x4c0 net/socket.c:2130
 __do_sys_setsockopt net/socket.c:2146 [inline]
 __se_sys_setsockopt net/socket.c:2143 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2143
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45aff9
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fab55e91c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007fab55e926d4 RCX: 000000000045aff9
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000490 R09: 0000000000000000
R10: 0000000020000580 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009c1 R14: 00000000004d3820 R15: 000000000075bf2c