INFO: task kworker/u4:5:483 blocked for more than 143 seconds. Not tainted 5.5.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:5 D25512 483 2 0x80004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4082 schedule+0x188/0x210 kernel/sched/core.c:4156 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4215 __mutex_lock_common+0x11f1/0x2f30 kernel/locking/mutex.c:1033 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118 hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1253 [inline] hashlimit_net_exit+0x40/0x210 net/netfilter/xt_hashlimit.c:1276 ops_exit_list net/core/net_namespace.c:172 [inline] cleanup_net+0x6f8/0xb80 net/core/net_namespace.c:589 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Showing all locks held in the system: 4 locks held by kworker/u4:5/483: #0: ffff88821bb8e528 ((wq_completion)netns){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff88821bb8e528 ((wq_completion)netns){+.+.}, at: process_one_work+0x763/0x10f0 kernel/workqueue.c:2237 #1: ffffc90002857d78 (net_cleanup_work){+.+.}, at: process_one_work+0x7a5/0x10f0 kernel/workqueue.c:2239 #2: ffffffff895882e8 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa5/0xb80 net/core/net_namespace.c:551 #3: ffffffff895a7030 (hashlimit_mutex){+.+.}, at: hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1253 [inline] #3: ffffffff895a7030 (hashlimit_mutex){+.+.}, at: hashlimit_net_exit+0x40/0x210 net/netfilter/xt_hashlimit.c:1276 1 lock held by khungtaskd/1132: #0: ffffffff892d9588 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 2 locks held by udevd/4279: 1 lock held by rsyslogd/8601: #0: ffff8880a63d65e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x279/0x310 fs/file.c:821 2 locks held by getty/8691: #0: ffff88809f96e090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8692: #0: ffff88809c4f5090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8693: #0: ffff888091741090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8694: #0: ffff8880a2a29090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000174b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8695: #0: ffff8880a9617090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000174f2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8696: #0: ffff88808cac0090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017572e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8697: #0: ffff88809113b090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000170b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.3/20676: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1132 Comm: khungtaskd Not tainted 5.5.0-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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaa/0x190 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x16f/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd40/0xd60 kernel/hung_task.c:289 kthread+0x332/0x350 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: 20676 Comm: syz-executor.3 Not tainted 5.5.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:hlock_class kernel/locking/lockdep.c:163 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:2879 [inline] RIP: 0010:validate_chain+0xa7/0x7be0 kernel/locking/lockdep.c:2935 Code: 89 d8 48 c1 e8 06 48 8d 3c c5 60 a8 02 8a be 08 00 00 00 e8 db 43 57 00 48 ba 00 00 00 00 00 fc ff df 48 0f a3 1d 49 55 a6 08 <72> 23 48 c7 c0 e0 80 43 8a 48 c1 e8 03 8a 04 10 84 c0 0f 85 c0 52 RSP: 0018:ffffc900017674c0 EFLAGS: 00000057 RAX: 0000000000000001 RBX: 0000000000000a04 RCX: ffffffff815c5305 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff8a02a9a0 RBP: ffffc900017676c0 R08: dffffc0000000000 R09: fffffbfff1405535 R10: fffffbfff1405535 R11: 0000000000000000 R12: ffff888047b1cce0 R13: ffff888047b1cc90 R14: 24c7d913196b36c8 R15: ffff888047b1c400 FS: 00007f957be17700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c007f7da88 CR3: 00000000401da000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __lock_acquire+0xc5a/0x1bc0 kernel/locking/lockdep.c:3954 lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x34/0x50 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:343 [inline] htable_selective_cleanup+0x99/0x320 net/netfilter/xt_hashlimit.c:368 htable_destroy net/netfilter/xt_hashlimit.c:408 [inline] htable_put+0x213/0x2a0 net/netfilter/xt_hashlimit.c:435 hashlimit_mt_destroy_v1+0x58/0x60 net/netfilter/xt_hashlimit.c:964 cleanup_match net/ipv4/netfilter/ip_tables.c:460 [inline] cleanup_entry+0x152/0x3b0 net/ipv4/netfilter/ip_tables.c:645 translate_table+0x203b/0x2230 net/ipv4/netfilter/ip_tables.c:728 do_replace net/ipv4/netfilter/ip_tables.c:1136 [inline] do_ipt_set_ctl+0x2c3/0x550 net/ipv4/netfilter/ip_tables.c:1672 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline] nf_setsockopt+0x27a/0x2a0 net/netfilter/nf_sockopt.c:115 ip_setsockopt+0xd8/0xf0 net/ipv4/ip_sockglue.c:1260 udp_setsockopt+0x79/0x90 net/ipv4/udp.c:2640 ipv6_setsockopt+0x12e/0x160 net/ipv6/ipv6_sockglue.c:939 tcp_setsockopt+0xbe/0xd0 net/ipv4/tcp.c:3159 sock_common_setsockopt+0x99/0xb0 net/core/sock.c:3149 __sys_setsockopt+0x582/0x720 net/socket.c:2130 __do_sys_setsockopt net/socket.c:2146 [inline] __se_sys_setsockopt net/socket.c:2143 [inline] __x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2143 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b399 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:00007f957be16c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f957be176d4 RCX: 000000000045b399 RDX: 0000000000000040 RSI: 0004000000000000 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000300 R09: 0000000000000000 R10: 0000000020000340 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000a05 R14: 00000000004cb675 R15: 000000000075bf2c