INFO: task kworker/u4:6:683 blocked for more than 143 seconds. Not tainted 5.5.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:6 D24432 683 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: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+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: 4 locks held by kworker/u4:6/683: #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: ffffc900028e7dc0 (net_cleanup_work){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239 #2: ffffffff8a4d6c08 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa1/0xb10 net/core/net_namespace.c:551 #3: ffffffff8a563320 (hashlimit_mutex){+.+.}, at: hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1253 [inline] #3: ffffffff8a563320 (hashlimit_mutex){+.+.}, at: hashlimit_net_exit+0x16d/0x3d0 net/netfilter/xt_hashlimit.c:1276 1 lock held by khungtaskd/1128: #0: ffffffff899a3e00 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5333 1 lock held by rsyslogd/9686: #0: ffff8880a92c25e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/9776: #0: ffff888099b09090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005a9b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9777: #0: ffff8880a82a0090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005aab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9778: #0: ffff88809099d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005abb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9779: #0: ffff88809f284090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005a7b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9780: #0: ffff888095715090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005a8b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9781: #0: ffff88809fd03090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005a1b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9782: #0: ffff888094d99090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900059fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.3/20016: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1128 Comm: khungtaskd Not tainted 5.5.0-rc6-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: 20016 Comm: syz-executor.3 Not tainted 5.5.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:trace_softirqs_on+0x174/0x3e0 kernel/locking/lockdep.c:3495 Code: 00 49 8d bc 24 70 08 00 00 48 b8 00 00 00 00 00 fc ff df 41 c7 85 94 08 00 00 01 00 00 00 41 c7 84 24 80 08 00 00 01 00 00 00 <48> 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 23 02 00 00 49 8d bc 24 44 RSP: 0018:ffffc900055c7748 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffffffff86765892 RCX: 1ffffffff16cec9c RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88802fc8ac70 RBP: ffffc900055c7760 R08: 0000000000000001 R09: fffff52002f0d60a R10: fffff52002f0d609 R11: ffffc9001786b04b R12: ffff88802fc8a400 R13: ffff88802fc8a400 R14: ffffc9001786b000 R15: 0000000000000001 FS: 00007f5b9c06c700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000009eb6f000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __local_bh_enable_ip+0x1cf/0x270 kernel/softirq.c:177 __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+0x232/0x340 net/netfilter/xt_hashlimit.c:373 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+0x454/0x920 net/ipv4/netfilter/ip_tables.c:564 translate_table+0xcb4/0x17d0 net/ipv4/netfilter/ip_tables.c:717 do_replace net/ipv4/netfilter/ip_tables.c:1136 [inline] do_ipt_set_ctl+0x2fe/0x4c2 net/ipv4/netfilter/ip_tables.c:1672 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline] nf_setsockopt+0x77/0xd0 net/netfilter/nf_sockopt.c:115 ip_setsockopt net/ipv4/ip_sockglue.c:1260 [inline] ip_setsockopt+0xdf/0x100 net/ipv4/ip_sockglue.c:1240 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: 0033:0x45b349 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:00007f5b9c06bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f5b9c06c6d4 RCX: 000000000045b349 RDX: 0000000000000040 RSI: 0004000000000000 RDI: 0000000000000003 RBP: 000000000075c070 R08: 000000000000002f R09: 0000000000000000 R10: 0000000020000380 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000009d9 R14: 00000000004cb40c R15: 000000000075c07c