INFO: task kworker/u4:3:129 blocked for more than 143 seconds. Not tainted 5.6.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:3 D23832 129 2 0x80004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4082 schedule+0xdc/0x2b0 kernel/sched/core.c:4156 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4215 __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:1253 [inline] hashlimit_net_exit+0x16d/0x3d0 net/netfilter/xt_hashlimit.c:1276 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+0xa05/0x17a0 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: 4 locks held by kworker/u4:3/129: #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff8880a9a85928 ((wq_completion)netns){+.+.}, at: process_one_work+0x8dd/0x17a0 kernel/workqueue.c:2235 #1: ffffc900013f7dc0 (net_cleanup_work){+.+.}, at: process_one_work+0x917/0x17a0 kernel/workqueue.c:2239 #2: ffffffff8a742548 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa1/0xb10 net/core/net_namespace.c:551 #3: ffffffff8a7d2620 (hashlimit_mutex){+.+.}, at: hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1253 [inline] #3: ffffffff8a7d2620 (hashlimit_mutex){+.+.}, at: hashlimit_net_exit+0x16d/0x3d0 net/netfilter/xt_hashlimit.c:1276 1 lock held by khungtaskd/1126: #0: ffffffff89bac240 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5333 1 lock held by rsyslogd/9536: #0: ffff888094e22b60 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:821 2 locks held by getty/9626: #0: ffff88809873b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9627: #0: ffff8880986a6090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000185b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9628: #0: ffff88808b994090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000184b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9629: #0: ffff8880986ed090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000183b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9630: #0: ffff8880978c4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9631: #0: ffff88809829d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000186b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9632: #0: ffff88809847c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.2/2122: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1126 Comm: khungtaskd Not tainted 5.6.0-rc1-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: 2122 Comm: syz-executor.2 Not tainted 5.6.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0x816/0x4a00 kernel/locking/lockdep.c:3949 Code: 44 8b bd 18 ff ff ff 4c 8b 9d 20 ff ff ff 49 c7 c5 d0 d3 a5 8a 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 0f b6 14 02 <4c> 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 db 14 00 00 8b RSP: 0018:ffffc900019075f0 EFLAGS: 00000802 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 707d04c4ff9a2ff5 RDX: 0000000000000000 RSI: 000000001d21b30e RDI: ffff8880555e8c61 RBP: ffffc90001907708 R08: 1ffffffff16a338f R09: fffffbfff16a3390 R10: ffff8880555e8c40 R11: ffff8880555e8380 R12: 0000000058c46479 R13: ffffffff8aa5d3d0 R14: ffff8880555e8c18 R15: 0000000000000000 FS: 00007f87b1469700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000075c000 CR3: 000000008b592000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4484 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:343 [inline] htable_selective_cleanup+0xa1/0x340 net/netfilter/xt_hashlimit.c:368 htable_destroy net/netfilter/xt_hashlimit.c:408 [inline] htable_put+0x174/0x220 net/netfilter/xt_hashlimit.c:435 hashlimit_mt_destroy+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 udpv6_setsockopt+0x68/0xb0 net/ipv6/udp.c:1564 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: 0033:0x45b3b9 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:00007f87b1468c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f87b14696d4 RCX: 000000000045b3b9 RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000490 R09: 0000000000000000 R10: 0000000020000a00 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000a04 R14: 00000000004d4570 R15: 000000000075bf2c